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Assessment of knee instability in ACL-injured knees using weight-bearing computed tomography (WBCT): a novel protocol and preliminary results
Abstract
To propose a protocol for assessing knee instability in ACL-injured knees using weight-bearing computed tomography (WBCT).
We enrolled five patients with unilateral chronic ACL tears referred for WBCT. Bilateral images were obtained in four positions: bilateral knee extension, bilateral knee flexion, single-leg stance with knee flexion and external rotation, and single-leg stance with knee flexion and internal rotation. The radiation dose, time for protocol acquisition, and patients’ tolerance of the procedure were recorded. A blinded senior radiologist assessed image quality and measured the anterior tibial translation (ATT) and femorotibial rotation (FTR) angle in the ACL-deficient and contralateral healthy knee.
All five patients were male, aged 23–30 years old. The protocol resulted in a 16.2 mGy radiation dose and a 15-min acquisition time. The procedure was well-tolerated, and patient positioning was uneventful, providing good-quality images. In all positions, the mean ATT and FTR were greater in ACL-deficient knees versus the healthy knee, with more pronounced differences observed in the bilateral knee flexion position. Mean lateral ATT in the flexion position was 9.1±2.8 cm in the ACL-injured knees versus 4.0±1.8 cm in non-injured knees, and mean FTR angle in the bilateral flexion position was 13.5°±7.7 and 8.6°±4.6 in the injured and non-injured knees, respectively.
Our protocol quantitatively assesses knee instability with WBCT, measuring ATT and FTR in diverse knee positions. It employs reasonable radiation, is fast, well-tolerated, and yields high-quality images. Preliminary findings suggest ACL-deficient knees show elevated ATT and FTR, particularly in the 30° flexion position.
Foot and ankle pathologies are among the most prevalent conditions within the human locomotor system. Imaging examinations are crucial for diagnosing, treating, and achieving satisfactory functional outcomes for these conditions. However, conventional imaging exams often fail to capture all the necessary details for precise analysis, necessitating the use of multiple imaging modalities to evaluate bones, ligaments, cartilage, and other structures.
This research aims to explore computational technologies and algorithms for 3D reconstruction and fusion of foot and ankle images, alongside the analysis, segmentation, classification, and evaluation techniques applied to these images.
The study investigates different computational approaches for 3D reconstruction and multimodal image fusion, integrating X-ray and MRI data. Advanced segmentation and classification techniques are applied to enhance the precision of structural assessment. Additionally, we assess the availability and quality of databases for training and validating these models.
Our findings highlight a significant gap in research concerning these specific applications, as well as a shortage of suitable databases for 3D reconstruction and fusion of images from X-rays and MRI.
The study emphasizes the need for dedicated datasets and further research to develop effective computational solutions for multimodal foot and ankle imaging.
Purpose
To compare the anterior translation and internal rotation of tibia on magnetic resonance imaging (MRI) between adult and adolescent patients with anterior cruciate ligament (ACL) tears.
Methods
Patients who underwent isolated ACL reconstruction from January 2013 to May 2021 were retrospectively reviewed. The exclusion criteria included incomplete data, poor image quality, a prior ACL surgery, and concomitant fractures or other ligament injuries. The enrolled patients were divided into two groups based on their ages: an adult group (age > 19 years) and an adolescent group (15 to 19 years of age). Anterior tibial translation and femorotibial rotation were measured on MRI. A Student’s t-test was used for the statistical analysis comparing the adult and adolescent groups.
Results
A total of 365 patients (279 adults and 86 adolescents) were enrolled in the present study. The anterior tibial translation in the adult group (4.8 ± 4.4 mm) and the adolescent group (5.0 ± 4.2 mm) was not significantly different ( p = 0.740). On the other hand, the tibial internal rotation in the adult group (5.6 ± 5.0 degree) was significantly greater compared to the adolescent group (4.2 ± 5.6 degree) ( p = 0.030). The intraclass correlation coefficients (ICC) of the measured data from two independent observers showed excellent reliability (0.964 and 0.961 for anterior tibial translation and tibial internal rotation, respectively).
Conclusion
The adult patients with ACL tears exhibited significant greater tibial internal rotation compared to the adolescent patients, whereas the magnitude of the anterior tibial translation was similar in both groups. Care should be taken if clinicians plan to establish the cutoff point values for diagnosis of ACL tears using the femorotibial internal rotation angle.
Objective
To compare computer-based 3D-analysis for quantification of the femorotibial joint space width (JSW) using weight-bearing cone beam CT(WB-CT), non-weight-bearing multi-detector CT (NWB-CT), and weight-bearing conventional radiographs (WB-XR).
Design
Twenty-six participants prospectively underwent NWB-CT, WB-CT, and WB-XR of the knee. For WB-CT and NWB-CT, the average and minimal JSW was quantified by 3D-analysis of the minimal distance of any point of the subchondral tibial bone surface and the femur. Associations with mechanical leg axes and osteoarthritis were evaluated. Minimal JSW of WB-CT was further compared to WB-XR. Two-tailed p-values of <0.05 were considered significant.
Results
Significant differences existed of the average medial and lateral JSW between WB-CT and NWB-CT (medial: 4.7 vs. 5.1 mm [p=0.028], lateral: 6.3 vs. 6.8mm [p=0.008]). The minimal JSW on WB-XR (medial:3.1 mm, lateral:5.8 mm) were significantly wider compared to WB-CT and NWB-CT (both medial:1.8 mm, lateral:2.9 mm, all p<0.001), but not significantly different between WB-CT and NWB-CT (all p≥0.869). Significant differences between WB-CT and NWB-CT existed in participants with varus knee alignment for the average and the minimal medial JSW (p=0.004 and p=0.011) and for participants with valgus alignment for the average lateral JSW (p=0.013). On WB-CT, 25% of the femorotibial compartments showed bone-on-bone apposition, which was significantly higher when compared to NWB-CT (10%,p=0.008) and WB-XR (8%,p=0.012).
Conclusion
Combining WB-CT with 3D-based assessment allows detailed quantification of the femorotibial joint space and the effect of knee alignment on JSW. WB-CT demonstrates significantly more bone-on-bone appositions, which are underestimated or even undetectable on NWB-CT and WB-XR.
Purpose:
To evaluate the influence of time from injury and meniscus tears on the side-to-side difference in anterior tibial translation (SSD-ATT) as measured on lateral monopodal weightbearing radiographs in both primary and secondary ACL deficiencies.
Methods:
Data from 69 patients (43 males/26 females, median age 27-percentile 25-75: 20-37), were retrospectively extracted from their medical records. All had a primary or secondary ACL deficiency as confirmed by MRI and clinical examination, with a bilateral weightbearing radiograph of the knees at 15°-20° flexion available. Meniscal status was assessed on MRI images by a radiologist and an independent orthopaedic surgeon. ATT and posterior tibial slope (PTS) were measured on the lateral monopodal weightbearing radiographs for both the affected and the contralateral healthy side. A paired t-test was used to compare affected/healthy knees. Independent t-tests were used to compare primary/secondary ACL deficiencies, time from injury (TFI) (≤ 4 years/ > 4 years) and meniscal versus no meniscal tear.
Results:
ATT of the affected side was significantly greater than the contralateral side (6.2 ± 4.4 mm vs 3.5 ± 2.8 mm; p < 0.01). There was moderate correlation between ATT and PTS in both the affected and healthy knees (r = 0.43, p < 0.01 and r = 0.41, p < 0.01). SSD-ATT was greater in secondary ACL deficiencies (4.7 ± 3.8 vs 1.9 ± 3.2 mm; p < 0.01), patients with a TFI greater than 4 years (4.2 ± 3.8 vs 2.0 ± 3.0 mm; p < 0.01) and with at least one meniscal tear (3.9 ± 3.8 vs 0.7 ± 2.2 mm; p < 0.01). Linear regression showed that, in primary ACL deficiencies, SSD-ATT was expected to increase (+ 2.7 mm) only if both a meniscal tear and a TFI > 4 years were present. In secondary ACL deficiencies, SSD-ATT was mainly influenced by the presence of meniscal tears regardless of the TFI.
Conclusion:
SSD-ATT was significantly greater in secondary ACL deficiencies, patients with a TFI greater than 4 years and with at least one meniscal tear. These results confirm that SSD-ATT is a time- and meniscal-dependent parameter, supporting the concept of gradual sagittal decompensation in ACL-deficient knees, and point out the importance of the menisci as secondary restraints of the anterior knee laxity. Monopodal weightbearing radiographs may offer an easy and objective method for the follow-up of ACL-injured patients to identify early signs of soft tissue decompensation under loading conditions.
Level of evidence:
Level III.
Imaging plays a key role in the preoperative diagnosis, surgical planning, and postsurgical assessment of the foot, ankle, and knee pathologies. Interpreting diagnostic imaging accurately is crucial for the clinical practice of orthopedic surgeons. Although among the most used imaging modalities, radiographic assessments are amenable to errors for various technical reasons and superposition of bones. Computed tomography (CT) is a conventional imaging procedure that provides high-resolution images, but fails in considering a truly weight-bearing (WB) condition. In an attempt to overcome this limitation, WB cone beam CT technology has being successfully employed in the clinical practice for the past decade. Besides economically viable and safe, the WB cone beam CT considers WB conditions and provides high-quality scans, thus allowing an equitable and correct interpretation. This review aims to address extensive description and discussion on WBCT, including imaging quality; costs; time consumption; and its applicability in common foot, ankle, and knee, conditions. With this technology increasing popularity, and considering the extensive literature on medical research, radiologists and orthopedic surgeons need to understand its potential applications and use it optimally. Level of Evidence III, Systematic review of level III studies.
Purpose
To compare weight-bearing cone-beam computer tomography (CBCT) and conventional computer tomography (CT)-based measurements of patellofemoral alignment and stability in patients surgically treated for recurrent patellar dislocation. These scans implied respectively single-leg up-right posture, the knee flexed, and lower limb muscles activation, versus supine position with the knee extended.
Methods
A total of 17 patients (11 males/6 females) after surgical reconstruction with fascia lata allograft for recurrent patellofemoral dislocation were analyzed at 60-month follow-up. Tilt and congruence angles and tibial tuberosity–trochlear groove (TT-TG) offset were measured on images obtained from CBCT and conventional CT scans by three independent and expert radiologists. Paired t tests were performed to compare measurements obtained from the two scans. Inter-rater reliability was assessed using a two-way mixed-effects model intra-class correlation coefficient (ICC).
Results
Only TT-TG offset was found significantly smaller ( p < 0.001) in CBCT (mean 9.9 ± 5.3 mm) than in conventional CT (mean 15.9 ± 4.9 mm) scans. ICC for tilt and congruence angles and for TT-TG offset ranged between 0.80–0.94 with measurements in CBCT scans, between 0.52 and0.78 in conventional CT.
Conclusion
In patients surgically treated for recurrent patellar dislocation, TT-TG offset was found overestimated with conventional CT. All measurements of patellofemoral stability and alignment were found more consistent when obtained with weight-bearing CBCT compared to conventional CT.
In the last decade, cone-beam computed tomography technology with improved designs allowing flexible gantry movements has allowed both supine and standing weight-bearing imaging of the lower extremity. There is an increasing amount of literature describing the use of weightbearing computed tomography in patients with foot and ankle disorders. To date, there is no review article summarizing this imaging modality in the foot and ankle. Therefore, we performed a systematic literature review of relevant clinical studies targeting the use of weightbearing computed tomography in diagnosis of patients with foot and ankle disorders. Furthermore, this review aims to offer insight to those with interest in considering possible future research opportunities with use of this technology.
Level of evidence:
Level V, expert opinion.
Purpose:
To investigate differences in joint space width (JSW) and meniscal extrusion (ME) between non-weight bearing (NWB) and weight bearing (WB) examinations of knee joints with medial compartment osteoarthritis (OA) using a cone-beam CT (CBCT) extremity imaging system.
Materials and methods:
In this IRB approved prospective study, informed consent was obtained for 17 patients symptomatic for OA (11 F,6M; 31-78 years, mean 56 years) and 18 asymptomatic controls (0 F,18M; 29-48 years, mean 38.5 years) enrolled for CBCT exams in NWB and WB positions. Three independent observers measured medial tibiofemoral JSW and ME. Measurements were compared between NWB and WB images using paired Wilcoxon signed-rank sum test.
Results:
OA subjects exhibited a statistically significant reduction in JSW between NWB and WB scans (average JSWNWB(OA)=2.1mm and JSWWB(OA)=1.5mm, p=0.016) and increase in ME (average MENWB(OA)=6.9mm and MEWB(OA)=8.2mm, p=0.018)). For non-OA subjects, the change in JSW and ME between NWB and WB exams was reduced (average JSWNWB(nonOA)=3.7mm and JSWWB(nonOA)=3.4mm; average MENWB(nonOA)=2.6mm and MEWB(nonOA)=2.7mm) and was not statistically significant. Inter-observer agreement was evaluated using Bland-Altman limits of agreement, with good agreement for all measurements (correlation coefficient 0.89-0.98).
Conclusion:
The ability to conduct NWB and WB exams in CBCT with a dose profile that is favorable in comparison to multidetector CT (MDCT) and with image quality sufficient for morphological analysis of joint space narrowing and meniscal extrusion could provide a valuable tool for OA diagnosis and treatment assessment.
To prospectively compare patellofemoral and femorotibial alignment in supine non-weight-bearing computed tomography (NWBCT) and upright weight-bearing CT (WBCT) and assess the differences in joint alignment.
NWBCT and WBCT images of the knee were obtained in 26 patients (mean age, 57.0 ± 15.9 years; range, 21-81) using multiple detector CT for NWBCT and cone-beam extremity CT for WBCT. Two musculoskeletal radiologists independently quantified joint alignment by measuring femorotibial rotation, tibial tuberosity-trochlear groove distance (TTTG), lateral patellar tilt angle, lateral patellar shift, and medial and lateral femorotibial joint space widths. Significant differences between NWBCT and WBCT were sought using Wilcoxon signed-rank test (P-value < 0.05).
Significant differences were found for femorotibial rotation (the NWBCT mean changed from 2.7° ± 5.1 (reader 1)/2.6° ± 5.6 (reader 2) external rotation to WBCT 0.4° ± 7.7/0.2° ± 7.5 internal rotation; P = 0.009/P = 0.004), TTTG (decrease from NWBCT (13.8 mm ± 5.1/13.9 mm ± 3.9) to WBCT (10.5 mm ± 5.0/10.9 mm ± 5.2; P = 0.008/P = 0.002), lateral patellar tilt angle (decrease from NWBCT (15.6° ± 6.7/16.9° ± 7.4) to WBCT (12.5° ± 7.7/15.0° ± 6.2; P = 0.011/P = 0.188). The medial femorotibial joint space decreased from NWBCT (3.9 mm ± 1.4/4.5 mm ± 1.3) to WBCT (2.9 mm ± 2.2/3.5 mm ± 2.2; P = 0.003/P = 0.004). Inter-reader agreement ranged from 0.52-0.97.
Knee joint alignment changes significantly in the upright weight-bearing position using CT when compared to supine non-weight-bearing CT.
• Cone-beam extremity CT offers upright weight-bearing examinations of the lower extremities. • Knee alignment changes significantly in an upright position compared to supine position. • Tibial tuberosity-trochlear groove distance (TTTG) is less pronounced in a weight-bearing position. • The weight-bearing position leads to a decrease of the lateral patellar tilt angle.
Computed tomography (CT) is an imaging test that is widely used worldwide to establish medical diagnoses and perform image-guided interventions. More recently, concern has been raised about the risk of carcinogenesis from medical radiation, with a focus on CT. The purpose of this article is to (a) describe the importance of educating radiology personnel, patients, and referring clinicians about the concerns over CT radiation, (b) describe commonly used CT parameters and radiation units, (c) discuss the importance of establishing a dedicated radiology team to manage CT radiation, and (d) describe specific CT techniques to minimize radiation while providing diagnostic examinations. © RSNA, 2014.
Objective evaluation of both antero-posterior translation and rotatory laxity of the knee remains a target to be accomplished. This is true for both preoperative planning and postoperative assessment of different ACL reconstruction emerging techniques. The ideal measurement tool should be simple, accurate and reproducible, while enabling to assess both ‘‘anatomy’’ and ‘‘function’’ during the same examination. The purpose of this study is to evaluate the clinical effectiveness of a new in-house developed testing device, the so-called Porto-knee testing device (PKTD). The PKTD is aimed to be used on the evaluation of both antero-posterior and rotatory laxity of the knee during MRI exams.
Between 2008 and 2010, 33 patients with ACLdeficient knees were enrolled for the purpose of this study. All patients were evaluated in the office and under anesthesia with Lachman test, lateral pivot-shift test and anterior drawer test. All cases were studied preoperatively with KT-1000 and MRI with PKTD, and examinations performed by independent observers blinded for clinical evaluation. During MRI, we have used a PKTD that applies antero-posterior translation and permits free tibial rotation through a standardized pressure (46.7 kPa) in the proximal posterior region of the leg. Measurements were taken for both knees and comparing side-to-side. Five patients with partial ruptures were excluded from the group of 33.
For the 28 remaining patients, 3 women and 25 men, with mean age of 33.4 ± 9.4 years, 13 left and 15 right knees were tested. No significant correlation was noticed for Lachman test and PKTD results (n.s.). Pivot-shift had a strong positive correlation with the difference in anterior translation registered in lateral and medial tibia plateaus of injured knees (cor. coefficient = 0.80; p\0.05), and with the difference in this parameter as compared to side-to-side (cor. coefficient = 0.83; p\0.05). Considering the KT-1000 difference between injured and healthy knees, a very strong positive correlation was found for side-to-side difference in medial (cor. coefficient = 0.73; p\0.05) and lateral (cor. coefficient = 0.5; p\0.05) tibial plateau displacement using PKTD.
The PKTD proved to be a reliable tool in assessment of antero-posterior translation (comparing with KT-1000) and rotatory laxity (compared with lateral pivotshift under anesthesia) of the ACL-deficient knee during MRI examination.
Therapeutic studies, Level IV.
Rotational knee laxity is an important measure in restoring knee stability following anterior cruciate ligament (ACL) injury, but is difficult to quantify with current clinical tools. The hypothesis of the study is that there is greater tibial rotation (TR) in women than men, and also in ACL-deficient than healthy knees.
Sixteen healthy (8 men, 26.8 ± 6.4 years; 8 women, 26.9 ± 3.8 years) and ten ACL-deficient (5 men, 33.6 ± 10.5 years; 5 women, 36.3 ± 10.7 years) subjects received bilateral knee MRI in 15° of flexion using a custom device to apply a constant axial compressive load (44 N). A rotational torque (3.35 Nm) was sequentially applied to obtain images at internal and external rotation positions. T (2)-weighted images were acquired in internal and external rotation. Images were segmented and TR was calculated. To assess reproducibility, six knees were scanned twice on separate days. Group comparisons were made with unpaired t tests, while intrasubject comparisons were made using paired t tests.
Healthy women demonstrated greater TR than men (13.6° ± 4.7° vs. 8.3° ± 3.6°; P = 0.001). Male ACL-deficient knees showed greater TR than the contralateral knee (15.7° ± 6.9° vs. 7.7° ± 5.6°; P = 0.003), and compared to male controls (P = 0.002). ACL-deficient women showed greater TR compared to their contralateral leg (15.1° ± 2.3° vs. 10.0° ± 4.3°; P = 0.01). The intraclass correlation coefficient of the TR measurement was 0.913, and the SEM = 1.1°.
Kinematic MRI is a reproducible method to quantify total knee rotation. Women have more rotational laxity than men, particularly in the external rotation position. ACL rupture leads to increased rotational laxity of the knee.
Retrospective case-control series, Level III.
Traumatic rupture of the anterior cruciate ligament (ACL) of the knee is one of the most frequent orthopaedic sports' injuries. However, the best operative reconstruction technique is still the focus of current discussions among experts. While single-bundle reconstruction primarily addresses anterior-posterior instability, the anatomical double-bundle reconstruction aims to stabilise anterior-posterior as well as rotational instability. So far no definite evidence to favour the one or the other technique exists due to the lack of an objective method for quantifying rotational knee stability. In this context several authors have recently reported on devices for the analysis of femorotibial rotation. However, most of these tools are still in the developmental stage. Therefore, the aim of this study was (1) to develop a new instrument for assessing rotational knee stability independent from the surrounding soft tissue with an adequate method of analysis and (2) to establish the possible field of application of this device in a human cadaver study. The so-called torsiometer evaluated was designed to assess internal and external knee joint rotation objectively in different flexion angles. Measurements were performed implying internal and external rotation at 90°, 30° and 0° knee flexion with and without intact ACL, respectively. Each measurement revealed valid and reproducible values. The restraint in ACL-absent knees was clearly lower and the course of rotation explicitly higher than in knee joints with intact ACL.
The primary role of the anterior cruciate ligament is to resist anterior subluxation of the tibia. When the ligament is torn, the tibia is free to sublux anteriorly when the leg is pulled forward. In addition to visualizing the anterior cruciate ligament directly, MR imaging can show joint alignment. The purpose of this study was to test the efficacy of MR images of anterior subluxation of the tibia for diagnosing complete tears of the anterior cruciate ligament.
We evaluated the records of 120 consecutive patients who underwent MR imaging of the knee and subsequently had arthroscopy. Arthroscopy showed a complete tear of the anterior cruciate ligament in 21 patients, a partial tear in eight patients, and an intact anterior cruciate ligament in 91 patients. Two radiologists together reviewed the MR images, and interpretation of anterior cruciate ligament integrity was reached by consensus. The anterior cruciate ligament was categorized as intact, completely torn, or partially torn on the basis of conventional MR imaging criteria. The degree of anterior subluxation of the tibia was measured on a separate occasion in random order by a radiologist who used a sagittal section through the middle of the lateral femoral condyle. On the selected image, two vertical lines parallel to the left and right margins of the image frame were drawn tangent to the posterior cortical margins of the lateral femoral and tibial condyles. Anterior subluxation of the tibia was determined by the distance in millimeters between these two lines and measured with calipers by using the 5-cm scale on the images. Measurements were considered reliable only to one half of the smallest increment of this scale (i.e., 5 mm). Accordingly, tibial subluxation (x) was measured in 5-mm increments, with x < or = 0 mm designated grade 0, 0 mm < x < or = 5 mm designated grade 1, 5 mm < x < or = 10 mm designated grade 2, and so forth.
Conventional MR imaging criteria had 90% sensitivity and 94% specificity for diagnosing complete tears of the anterior cruciate ligament. According to the receiver-operating-characteristic (ROC) curve, anterior subluxation of the tibia greater than 5 mm (grade 2 or greater) was considered to be the optimal threshold (sensitivity, 86%; specificity, 99%) for diagnosing complete tears of the anterior cruciate ligament. Notably, none of the six false-positive diagnoses of complete tears by conventional criteria (three partial tears and three intact ligaments at arthroscopy) were misdiagnosed when tibial subluxation was used as the diagnostic criterion. Subluxation greater than 5 mm can be falsely negative with chronic tears of the anterior cruciate ligament (n = 2) or when a displaced bucket-handle tear of the lateral meniscus blocks anterior subluxation of the tibia (n = 1).
An anterior tibial subluxation greater than 5 mm (grade 2 or greater) is a simple objective measurement that serves as a helpful adjunctive sign in the diagnosis of complete tears of the anterior cruciate ligament. This sign also offers improved discrimination of complete from partial tears of the anterior cruciate ligament.
Purpose:
To identify the radiological predictive risk factors for anterior cruciate ligament reconstruction (ACLR) failure, compare the diagnostic accuracies of different parameters of conventional radiographs and magnetic resonance imaging (MRI), and determine the cutoff values for patients at higher risk.
Methods:
Twenty-eight patients who were diagnosed as ACLR failure via MRI or arthroscopic examination were included in the study group. They were matched to 56 patients who underwent primary ACLR with the same surgical technique and without graft failure at the minimum 24-month follow-up by age, sex, and body mass index. On true lateral whole-leg radiographs, the posterior tibial slope (PTS) referenced to the tibial mechanical axis (PTS-mechanical), PTS referenced to the tibial proximal anatomical axis (PTS-anatomical), and anterior tibial translation (ATT) were measured. On the sagittal slices of MRI, the medial tibial slope (MTS), medial tibial plateau (MTP) subluxation (MTPsublx), lateral tibial slope (LTS), and lateral tibial plateau (LTP) subluxation (LTPsublx) were obtained. Receiver operator characteristic (ROC) curves were constructed to compare the diagnostic performance and determine the cutoff values of different radiological parameters.
Results:
The study group demonstrated higher values of PTS-mechanical (10.7° ± 2.9° vs 8.7° ± 1.9°, p = 0.003), PTS-anatomical (13.2° ± 2.8° vs 10.5° ± 2.5°, p < 0.001), ATT (10.7 ± 3.3 mm vs 8.9 ± 2.2 mm, p = 0.014), LTS (9.4° ± 2.1° vs 5.5° ± 2.5°, p < 0.001), and LTPsublx (8.2 ± 2.8 mm vs 6.8 ± 1.9 mm, p = 0.009) as compared with the control group. The area under the ROC curve of LTS was significantly larger than that of PTS-mechanical (p = 0.006) and PTS-anatomical (p = 0.020). Based on the maximum Youden indexes, the cutoff values of PTS-mechanical, PTS-anatomical, and LTS were 10.1° (sensitivity, 64.3%; specificity, 78.6%), 12.0° (sensitivity, 71.4%; specificity, 71.4%), and 7.7° (sensitivity, 85.7%; specificity, 80.4%), respectively.
Conclusion:
Due to the morphological asymmetry of the MTP and LTP, steep LTS measured on MRI is the best radiological predictor of ACLR failure. Detailed measurement of the LTS on MRI is recommended to evaluate the risk of ACLR failure prior to the surgery.
Level of evidence:
III.
Background
Incompetence of the anterior cruciate ligament (ACL) confers knee laxity in the sagittal and axial planes that is measurable with clinical examination and diagnostic imaging.
Hypothesis
An ACL-deficient knee will produce a more vertical orientation of the lateral collateral ligament (LCL), allowing for the entire length of the LCL to be visualized on a single coronal slice (coronal LCL sign) on magnetic resonance imaging.
Study Design
Cohort study (diagnosis); Level of evidence, 3.
Methods
Charts were retrospectively reviewed from April 2009 to December 2017 for all patients treated with ACL reconstruction (constituting the ACL-deficient cohort). A control cohort was separately identified consisting of patients with a normal ACL and no pathology involving the collateral ligaments or posterior cruciate ligament. Patients were excluded for follow-up <2 years, incomplete imaging, and age >19 years. Tibial translation and femorotibial rotation were measured on magnetic resonance images, and posterior tibial slope was measured on a lateral radiograph of the knee. Imaging was reviewed for the presence of the coronal LCL sign.
Results
The 153 patients included in the ACL-deficient cohort had significantly greater displacement than the 70 control patients regarding anterior translation (5.8 vs 0.3 mm, respectively; P < .001) and internal rotation (5.2° vs −2.4°, P < .001). Posterior tibial slope was not significantly different. The coronal LCL sign was present in a greater percentage of ACL-deficient knees than intact ACL controls (68.6% vs 18.6%, P < .001). The presence of the coronal LCL sign was associated with greater anterior tibial translation (7.2 vs 0.2 mm, P < .001) and internal tibial rotation (7.5° vs –2.4°, P = .074) but not posterior tibial slope (7.9° vs 7.9°, P = .973) as compared with its absence. Multivariate analysis revealed that the coronal LCL sign was significantly associated with an ACL tear (odds ratio, 12.8; P < .001).
Conclusion
Our study provides further evidence that there is significantly more anterior translation and internal rotation of the tibia in the ACL-deficient knee and proves our hypothesis that the coronal LCL sign correlates with the presence of an ACL tear. This coronal LCL sign may be of utility for identifying ACL tears and anticipating the extent of axial and sagittal deformity.
Purpose
To evaluate the diagnostic value of stress radiography and determine the cutoff values for high-grade anterolateral rotatory laxity in complete anterior cruciate ligament (ACL)-deficient knees at different positions.
Methods
Forty-two patients with complete ACL rupture (group 1) and 37 normal subjects (group 2) were prospectively enrolled. The amount of anterior translation in the medial (MM) and lateral (LL) distance compartments and the difference between them (LL-MM distance) were measured using stress radiography at 30°, 45°, 60°, and 90° positions. The area under the receiver operating characteristic curve (AUC) was assessed for the presence of a high-grade (grade > 2) pivot shift.
Results
The MM and LL distances in group 1 were significantly different at 30° and 45° positions (P < 0.05). The AUC of the MM (AUC, 0.903) and LL (AUC, 0.901) distances at the 30° position was significantly higher than that of the other positions (P = 0.000); however, the cutoff values were different to diagnose ACL injury (MM vs. LL, 3.1 mm vs. 5.4 mm). A 2.1-mm cutoff for the LL-MM distance showed 78.4% sensitivity and 90.3% specificity for detecting the presence of a high-grade pivot shift (AUC = 0.905, P = 0.000).
Conclusion
The cutoff values of stress radiography differed according to anatomical references and knee flexion positions. Stress radiography of a 2.1 mm difference in LL-MM distance at 30° of knee flexion can be a reliable method for high-grade rotatory laxity in complete ACL-injured knees.
Level of evidence
Level 1, diagnostic study.
Background:
Knee laxity in the setting of anterior cruciate ligament (ACL) injury is often assessed through physical examination using the Lachman, pivot shift, and anterior drawer tests. The degree of laxity noted on these examinations may influence treatment decisions and prognosis.
Hypothesis:
Increased preoperative knee laxity is associated with increased risk of revision ACL reconstruction, increased risk of contralateral ACL reconstruction, and poorer patient-reported outcomes at 6 years postoperatively.
Study design:
Cohort study; Level of evidence, 2.
Methods:
2333 patients who underwent primary isolated ACL reconstruction without additional ligament injury were identified. Patients reported by the operating surgeons to have an International Knee Documentation Committee (IKDC) grade D Lachman, anterior drawer, or pivot shift examination were classified as having a high-grade laxity. Multiple logistic regression models were used to evaluate whether having high-grade preoperative laxity was predictive of increased odds of undergoing subsequent revision or contralateral ACL reconstruction within 6 years of the index procedure, controlling for patient age, sex, body mass index, Marx activity level, sport, graft type, medial meniscal treatment, and lateral meniscal treatment. Multiple linear regression modeling was used to evaluate whether having high-grade preoperative laxity was predictive of poorer IKDC or Knee injury and Osteoarthritis Outcome Score Knee-Related Quality of Life (KOOS-QOL) scores at 6 years postoperatively, after controlling for baseline score, patient age, ethnicity, sex, body mass index, marital status, smoking status, sport participation, competition level, Marx activity rating score, graft type, and articular cartilage and meniscal status.
Results:
In total, 743 of 2325 patients (32.0%) were noted to have high-grade laxity on at least 1 physical examination test. High-grade Lachman was noted in 334 patients (14.4%), high-grade pivot shift was noted in 617 patients (26.5%), and high-grade anterior drawer was noted in 233 patients (10.0%). Six-year revision and contralateral ACL reconstruction data were available for 2129 patients (91.6%). High-grade prereconstruction Lachman was associated with significantly increased odds of ACL graft revision (odds ratio [OR], 1.76; 95% CI, 1.10-2.80, P = .02) and contralateral ACL reconstruction (OR, 1.68; 95% CI, 1.09-2.69; P = .019). High-grade prereconstruction pivot shift was associated with significantly increased odds of ACL graft revision (OR, 1.75; 95% CI, 1.19-2.54, P = .002) but not with significantly increased odds of contralateral ACL reconstruction (OR, 1.30; 95% CI, 0.89-1.87; P = .16). High-grade prereconstruction laxity was associated with statistically significantly lower 6-year IKDC (β = -2.26, P = .003), KOOS-QOL (β = -2.67, P = .015), and Marx activity scores (β = -0.54, P = .020), but these differences did not approach clinically relevant differences in patient-reported outcomes.
Conclusion:
High-grade preoperative knee laxity is predictive of increased odds of revision ACL reconstruction and contralateral ACL reconstruction 6 years after ACL reconstruction. Poorer patient-reported outcome scores in the high-grade laxity group were also noted, but the difference did not reach a level of clinical relevance.
Purpose:
To investigate the associations of medial tibial plateau slope (MTPS), lateral tibial plateau slope (LTPS), and coronal tibial plateau slope (CTPS) with anterior cruciate ligament (ACL) injury both in the general population and in different gender subgroups.
Methods:
PubMed, Ovid, Embase, and Scopus databases were searched through from inception to August 31, 2016. Observational studies reporting associations of MTPS/LTPS/CTPS with ACL injury were retrieved for analysis. Either a fixed- or random-effects model was used to calculate the overall standardized mean difference (SMD). Reviews, meeting abstracts, cadaver or animal studies, and other studies without disclosing full text were excluded in this study.
Results:
A total of 29 studies were included. Subjects with ACL injury exhibited a significant increase in MTPS (SMD: 0.34 [95% confidence interval (CI): 0.18, 0.49]; P < .0001) and LTPS (SMD: 0.49 [95% CI: 0.30, 0.68]; P < .00001), but not in the CTPS (SMD: 0.09 [95% CI: -0.10, 0.27]; P = .36), compared with controls. Meanwhile, significant differences in MTPS and LTPS were observed in the male subgroup (SMD: 0.41 [95% CI: 0.20, 0.62]; P = .0001 and SMD: 0.55 [95% CI: 0.26, 0.85]; P = .0002, respectively) but not in the female (SMD: 0.31 [95% CI: -0.02, 0.64]; P = .06 and SMD: 0.26 [95% CI: -0.04, 0.56]; P = .09, respectively).
Conclusions:
The present meta-analysis showed that the increases in MTPS and LTPS were overall risk factors of ACL injury. However, these slopes would only be considered as "at risk" for males, but not for females. In addition, it was also proved that CTPS was not a risk factor of ACL injury.
Level of evidence:
Level III, meta-analysis of Level II and III studies.
Background:
Rotation is one of the variables explaining lack of reproducibility in assessing hindfoot alignment. The hypothesis for this study was that a mathematical model predicts how this modifies radiographic hindfoot alignment measurements.
Methods:
A cadaveric lower limb, disjointed at knee level, was used. Sagittal and coronal planes were fixed using a custom clamp. Standard AP views were shot every five degrees and measured hindfoot alignments were compared to theoretical values obtained from a mathematical simulation.
Results:
Hindfoot angle was 7.04° at 0° rotation and 2.11° at -90°. Intra-class and inter-investigator correlation was 0.863. The t-test showed no significant difference (p=0.73). Intra-investigator correlation was 0.957. The R2 correlation index was 0.852.
Conclusions:
The mathematical model accurately predicted the variations of the hindfoot angle which was maximum when the foot was aligned with the X-rays source. It then decreased when the foot rotated away, following a parabolic curve.
OBJECTIVE. The objective of this study was to evaluate the accuracy of tibial rotation measurement as a secondary sign for diagnosing anterior cruciate ligament (ACL) tears with the use of MRI.
MATERIALS AND METHODS. A total of 893 MRI studies were retrospectively reviewed, and 239 patients were identified as having either an intact ACL (group 1; n = 182), an arthroscopically confirmed acutely torn ACL (group 2; n = 22), or a chronically torn ACL (group 3; n = 35). Tibial rotation was estimated by measuring the femorotibial angle (FTA).
RESULTS. The mean (± SD) FTA was significantly higher in group 2 (10.7° ± 4.8°) and group 3 (11° ± 5.5°) than in group 1 (3.2° ± 3.3°) (p < 0.001, for all cases). An FTA of 4.9° was the optimal threshold (sensitivity, 93%; specificity, 80%) for separating completely torn ACLs from intact ACLs. An FTA ranging from 4.9° to 5.5° (sensitivity, 95%; specificity, 80%) indicated a complete acute ACL tear, whereas an FTA of 5.6° or greater (sensitivity, 91.4%; specificity, 83.5%) suggested a complete chronic ACL tear.
CONCLUSION. An increased FTA indicates alteration in the femorotibial anatomic relationship and could be of value in assessing ACL tears in patients with equivocal signs on MRI.
To demonstrate factors that can affect interpretation of ACL tear using anterior tibial translation sign and to compare the cut-off value of anterior tibial translation sign in the present study with previous studies.
This was a retrospective descriptive research study. The authors included all patients who underwent both MRI and arthroscopy of the knee in King Chulalongkorn Memorial Hospital from January 2002 to March 2010. Anterior tibial translation distance was measured. For patients with intact A CL, tests for correlation between anterior tibial translation distance and demographic data were performed. For patients with ACL tear, a receiver operating characteristic (ROC) analysis was performed in order to determine the best cut-off value for an anterior tibial translation sign.
One hundred seventeen patients were enrolled in this study and classified as follows: intact ACL (n = 58), partial ACL tear (n = 19), and complete ACL tear (n = 40). Anterior tibial translation distances for each subgroup were 1.5, 5.0, and 7.6mm, respectively. Significant mean distance differences for each pair of subgroups were found. No significant correlations between anterior tibial translation distance and sex, height, and weight were found. There was, however, a significant correlation between anterior tibial translation distance and age. For diagnosis of partial and complete ACL tear cut-off distances of 3.5 mm and 5.5 mm provided the best accuracy, respectively.
There is correlation between anterior tibial translation distance and age. The authors may possibly imply that, using anterior tibial translation distance in young age group patients for diagnosing ACL tear may increase the false-positive rate. The authors introduce a cut-off distance of 3.5 mm to classify patients as having intact ACL or ACL tear.
Background:
The purpose of this study was to identify the effects that X-ray source misalignment has on common measurements made from anterior-poster (AP) and medial-lateral (ML) view foot radiographs.
Methods:
A cadaveric foot model was used to obtain ML radiographs with ±25 degree transverse plane misalignment. From these images the calcaneal pitch angle (CPA) and lateral talometatarsal angle (LTMA) were measured. AP images were captured with up to 30 degree sagittal plane misalignment as well as ±15 degree misalignment in the transverse plane at each sagittal angle. From these images the talonavicular coverage angle (TNCA) and talometatarsal angle (TMA) were measured.
Results:
On the ML images, the CPA was sensitive to transverse plane misalignment from -10 to -25 degrees and from 15 to 25 degrees (P < .005). The LTMA was a more reliable measurement than the CPA and did not demonstrate sensitivity to transverse plane misalignment. On the AP images, the TNCA and TMA were not sensitive to sagittal plane misalignment alone. However, at 0, 10, and 15 degrees sagittal misalignment the TNCA showed sensitivity to transverse plane misalignment (P < .0083).
Conclusion:
Misalignment of an X-ray source can lead to errors in the measurement of foot radiographic parameters, especially the CPA when there is transverse plane misalignment and the TNCA when there is both sagittal and transverse plane misalignment. The LTMA and TMA can be measured reliably, even with significant misalignment present.
Clinical relevance:
If a researcher or clinician is interested in measuring the CPA or TNCA, the current best practices guidelines for obtaining ML and AP images should be closely followed.
Excessive tibial rotation has been documented in anterior cruciate ligament (ACL) deficiency during walking. ACL reconstruction has been unable to correct this abnormality in activities that are more demanding than walking and involve both anterior and rotational loading of the knee. These findings persist regardless of graft selection for the ACL reconstruction (bone-patellar tendon-bone or semitendinosus gracilis). Based on this research work, we propose a theoretical perspective for the development of osteoarthritis in both the ACL-deficient and the ACL-reconstructed knee. We propose that excessive tibial rotation will lead to abnormal loading of the cartilage areas that are not commonly loaded in the healthy knee. Over time, this abnormal loading will lead to osteoarthritis. We hypothesise that the development of new surgical procedures and grafts, such as a more horizontally oriented femoral tunnel or a double-bundle ACL reconstruction, could possibly restore tibial rotation to normal levels and prevent future knee pathology. However, in vivo gait analysis studies are needed to examine the effects of these surgical procedures on tibial rotation. Prospective in vivo and in vitro studies are also necessary to verify or refute our theoretical proposition for the development of osteoarthritis.
Objective:
The purpose of this article is to describe weight-bearing CT of the lower extremity joints using a novel portable imager utilizing cone-beam CT technology.
Conclusion:
Cone-beam CT technology with new design and flexible gantry movements allows both supine and weight-bearing imaging of the lower extremities, with a reasonable radiation dose and excellent image quality. Weight-bearing CT of joints can provide important new clinical information in musculoskeletal radiology.
Introduction:
Injury to the anterior cruciate ligament (ACL) is common. While prior studies have shown that surgical reconstruction of the ACL can restore anterior-posterior kinematics, ACL-injured and reconstructed knees have been shown to have significant differences in tibial rotation when compared to uninjured knees. Our laboratory has developed an MR compatible rotational loading device to objectively quantify rotational stability of the knee following ACL injuries and reconstructions. Previous work from our group demonstrated a significant increase in total tibial rotation following ACL injuries. The current study is a prospective study on the same cohort of patients who have now undergone ACL reconstruction. We hypothesize that ACL reconstructed knees will have less tibial rotation relative to the pre-operative ACL deficient condition. We also hypothesize that ACL reconstructed knees will have greater rotational laxity when compared to healthy contralateral knees.
Methods:
Patients. Six of the ACL injured patients from our initial study who had subsequently undergone ACL reconstruction were evaluated 8.1 ± 2.9 months after surgery. All patients underwent single-bundle ACL reconstruction using anteromedial portal drilling of the femoral tunnel with identical post-operative regimens. Magnetic Resonance (MR) Imaging. Patients were placed in a supine position in the MR scanner on a custom-built loading device. Once secured in the scanner bore, an internal/external torque was applied to the foot. The tibiae were semi-automatically segmented with in-house software. Tibial rotation comparisons were made within subjects (i.e. side-to-side comparison between reconstructed and contralateral knees) and differences were explored using paired sample t-tests with significance set at p=0.05.
Results:
Regarding tibial rotation, in the ACL deficient state, these patients experienced an average of 5.9 ± 4.1° difference in tibial rotation between their ACL deficient and contralateral knees. However, there was a -0.2 ± 6.1° difference in tibial rotation of the ACL reconstructed knee when compared to the contralateral uninjured knee. Regarding tibial translation, ACL deficient patients showed a difference of 0.75 ± 1.4mm of anterior tibial translation between injured and healthy knees. After ACL reconstruction, there was a 0.2 ± 1.1mm difference in coupled anterior tibial translation of the ACL reconstructed knee compared to the contralateral knee. No significant differences in contact area between the two time points could be discerned.
Discussion:
The objective of our study was to assess the rotational laxity present in ACL reconstructed knees using a previously validated MRI-compatible rotational loading device. Our study demonstrated that ACL reconstruction can restore rotational laxity under load. This may speak to the benefit of an anteromedial drilling technique, which allows for a more horizontal and anatomically appropriate graft position.
The clinical diagnosis of the anterior cruciate ligament (ACL) tear is based on demonstrating anterior subluxation of the tibia on the femur. In any of the following perspectives, diagnostic (cutoff value confirming rupture), prognostic (treatment efficacy), and therapeutic (laxity influencing the treatment), this laxity can be measured on stress X-rays.
The diagnostic value of dynamic radiographs is low for ACL rupture. Passive Telos(®) X-rays have better diagnostic value, better radiologic quality, and are easier to carry out than active Franklin-type X-rays.
A cohort of 112 patients (28 females, 84 males; mean age, 33.7 years [range, 18-72 years]) with an indication for knee arthroscopy were studied prospectively. Before undergoing the arthroscopic treatment, two series of images of both knees were taken: one series of passive anterior drawer dynamic X-rays on a Telos(®) device at 250 N and a series of active anterior drawer dynamic X-rays according to Franklin (contraction of the quadriceps against 7 kg of weight at the ankle). The arthroscopic evaluation of the ACL (reference status) was compared to the anterior laxity measurements (absolute and differential) of each knee compartment (medial, lateral, and average) to determine the diagnostic value of the two radiological tests.
We found 70 patients with an "arthroscopically ruptured ACL", 32 with an "arthroscopically healthy ACL", and 10 with a "partial rupture". The measurement of the anterior drawer values on the dynamic X-rays (active and passive) by two independent observers was reliable and reproducible (ICC>0.80), particularly when using the medial compartment (ICC=0.96) and the differential values eliminating the interobserver measurement error and interindividual laxity variations. In terms of X-ray technique, the active images were more frequently painful and the radiographic result showed less good quality than the Telos images. The anterior drawer values in the "healthy ACL" group were significantly less than in the "ruptured ACL" group for the Telos(®) images, whether the measurements were absolute or differential. For the Franklin images, this difference was only significant for the absolute values. Used for diagnosis (4-mm differential on the medial compartment), the passive dynamic images had lower diagnostic values (Se=59% and Sp=90%) than the series reported in the literature, which were marked by great heterogeneity.
The measurement of anterior drawer values on Telos(®) and Franklin dynamic X-rays is a reliable and reproducible measurement, particularly when using the medial compartment and differential measurements. This small series did not demonstrate a diagnostic value for the Franklin images, contrary to the Telos(®) X-rays. Used for diagnostic purposes, the Telos(®) images had a low sensitivity; consequently, they should be used preferentially for prognostic or therapeutic purposes.
Level III, prospective case-control study.
The average medical radiation effective dose to the U.S. population in 2006 was estimated at approximately 3.0 mSv, an increase of 600% in a single generation. Computed tomography (CT) alone accounts for approximately half of this medical radiation dose. Ongoing advances suggest that CT will continue to be the most important contributor, by far, to medical doses in the United States. The use of ionizing radiation in medical imaging, including CT, provides valuable diagnostic information that undoubtedly benefits many patients. Exposure to radiation, however, is currently believed to carry a small, but nonzero, risk. Accordingly, the medical imaging community must ensure that the benefits of a radiologic examination in any given patient exceed the corresponding risks. It is also the responsibility of the radiologist to ensure that no more radiation is used than needed for obtaining diagnostic information in any radiologic examination, especially CT.
Anterior translation of the lateral compartment was hypothesized to correlate with the clinical grade of a pivot shift maneuver. Using a computer-assisted navigation system, this hypothesis was tested by recording the maximum anterior tibial translation in the medial and lateral compartment as well as the arc of rotation during the pivot shift maneuver. One hundred and fifty-four pivot shift examinations were performed on cadavers with various degrees of instability, and 24 pivot shift exams were performed on patients under anesthesia before and after ACL reconstruction. In all positive pivot shift exams, anterior tibial translations were found to be higher on in the lateral compartment compared to the medial compartment. In addition, an excellent correlation was found between the amount of lateral compartment translation and the clinical grade of the pivot shift; medial compartment translations and amount of knee rotation could not distinguish between clinical grades. Finally, a threshold of 6-7 mm of anterior tibial translation in the lateral compartment was necessary to produce a positive pivot shift. Taken together, these data suggest that monitoring lateral compartment translations during a pivot shift exam may be a convenient means to evaluate the outcomes of ACL surgery and that requisite increases in anterior translation of the lateral compartment are necessary for each progressive clinical grade of the pivot shift examination.
While the application of compressive joint loads and thigh muscle activity are associated with anterior tibial translation in vitro, less is known during early load acceptance in vivo. We investigated the effects of increasing axial loads on anterior tibial translation and thigh muscle activity in healthy knees during transition from non-weight bearing to early weight bearing.
Participants (11 males, 11 females) underwent 20%, 40%, and 60% body weight acceptance trials at 20 degrees knee flexion while electromagnetic sensors measured anterior tibial translation (mm), and surface electromyography recorded quadriceps and hamstring muscle onset times (ms) and amplitudes (% maximal voluntary isometric contraction). Repeated measures ANOVA compared values across loads. Pearson correlations examined relationships between anterior tibial translation and muscle onset times and amplitudes within each load.
As load increased, anterior tibial translation (Mean (standard deviation)) (20%=4.7 (1.7) mm<40%=7.1 (1.9) mm<60%=8.8 (2.1) mm), and quadriceps (20%=23.6 (14.9)% maximal voluntary isometric contraction <40%=32.7 (11.8)% maximal voluntary isometric contraction <60%=41.1 (13.5)% maximal voluntary isometric contraction) and hamstring (20%=15.5 (15.7)% maximal voluntary isometric contraction <40%=23.0 (16.4)% maximal voluntary isometric contraction <60%=27.6 (19.1)% maximal voluntary isometric contraction) activation increased, while quadriceps (20%=96.7 (28.4) ms>60% 80.2 (21.8) ms) and hamstring (20%=141.5 (65.0) ms and 40%=126.3 (68.8)>60% 107.6 (28.4) ms) onset times decreased (P0.05). There were no relationships between anterior tibial translation and muscle activation amplitudes (R=0.033-0.294) or onset times (R=-0.031-0.374) (P>0.09).
Greater axial loads near full knee extension during early weight acceptance result in greater anterior tibial translation, regardless of faster and stronger activation amplitudes. These findings support injury prevention programs aimed to reduce impact forces as they may in turn reduce anterior tibial translation and corresponding ligamentous strain during dynamic activity.
Anterior cruciate ligament reconstruction successfully reduces anterior knee instability, but its effect on rotatory stability is not fully understood. In addition, a definitive method for the quantitative evaluation of rotatory instability remains to be established.
Measurement of anterolateral tibial translation by open magnetic resonance imaging could positively correlate with the clinical grading of the pivot-shift test and would clarify residual rotatory abnormalities not shown by conventional methods for measurement of anterior stability.
Controlled laboratory study.
An anterior cruciate ligament-reconstructed group (n = 21) and an anterior cruciate ligament-deficient group (n = 20) were examined using a Slocum anterolateral rotatory instability test in open magnetic resonance imaging. Anterior tibial translation was measured at the medial and lateral compartments by evaluating sagittal images. Clinical knee stability was evaluated before the above measurement using the pivot-shift test, KT-2000 arthrometer, and stress radiography. A cutoff value for anterolateral tibial translation relating to pivot-shift was determined using a receiver operating characteristic curve.
Side-to-side differences of anterolateral tibial translation correlated with clinical grade of the pivot-shift test and stress radiography but not with KT-2000 arthrometry in both groups. The cutoff value was established as 3.0 mm. Although the mean anterolateral translation showed no difference, 9 reconstructed knees revealed greater than 3 mm of anterolateral tibial translation, whereas only 3 uninjured knees did.
Measurement using an open magnetic resonance imaging successfully quantified the remaining rotatory instability in anterior cruciate ligament-reconstructed knees.
This method is a useful means for quantifying anterior cruciate ligament function to stabilize tibial rotation.
The authors evaluated measurement of the degree of anterior subluxation ("translocation") of the tibia in regard to the femur as a predictor of anterior cruciate ligament (ACL) tear. Eighty-nine magnetic resonance (MR) imaging studies of patients with either an arthroscopically confirmed intact (n = 29), acutely torn (n = 27), or chronically torn (n = 33) ACL were retrospectively reviewed. The degree of translocation was measured on hard-copy images by using two methods. Buckling of the posterior cruciate ligament (PCL) was also evaluated. Anterior tibial translocation, when measured at the midsagittal plane of the lateral femoral condyle with regard to a plane parallel to the cephalocaudal axis of the image, was a relatively specific indicator of ACL disruption. Subluxation of 5 mm or more had 58% sensitivity, 93% specificity, and 69% accuracy for an ACL tear. All knees with subluxation of 7 mm or more had torn ACLs. Buckling of the PCL was less sensitive and less accurate than anterior translocation as an indicator of ACL disruption.
Meniscal injury has been well documented in association with injury to the anterior cruciate ligament. The purpose of this study was to evaluate the effect of anterior cruciate ligament transection and reconstruction on meniscal strain. Four differential variable reluctance transducer strain gauges were placed in the medial and lateral menisci of nine cadaveric knees. Each specimen was mounted to a six-degree-of-freedom knee testing device. Testing was conducted with the knee fully extended and at 45 degrees and 90 degrees of flexion, both with and without applied axial load. At each angle of flexion, an anterior and posterior tibial load was applied. Next, the anterior cruciate ligament was transected and the testing sequence was repeated. Finally, the ligament was reconstructed using a central one-third patellar tendon graft and the testing sequence was repeated. The results demonstrated statistically significant increases in meniscal strain in ligament-transected knees compared with intact specimens. A reduction in meniscal strain to a level similar to that detected in the ligament-intact knees was observed after anterior cruciate ligament reconstruction. These results have important clinical implications regarding the potentially deleterious effect of the anterior cruciate ligament-deficient knee on meniscal strain and the potential benefit of anterior cruciate ligament reconstruction.
Translation of the tibia relative to the femur was measured while a group of subjects with normal knees and group with anterior cruciate ligament (ACL) tears underwent transition from non-weightbearing to weightbearing stance. Subjects were positioned in the Vermont knee laxity device (VKLD) with muscles relaxed and the limb segment and compressive joint load offset (non-weightbearing). A lateral radiograph of the knee, with the posterior aspects of the femoral condyles superimposed, was obtained to document the position of the tibia relative to the femur. Immediately after, a compressive load equal to 40% of bodyweight was applied to each foot, and a second radiograph was obtained to document the change in position of the tibia relative to the femur. The transition from non-weightbearing to weightbearing produced a significant increase of anterior translation of the tibia relative to the femur (mean; 3.4 mm) for the subjects with ACL tears compared with the contralateral normal knees (0.8 mm). Similarly, there was a significant increase in anterior translation of the tibia for the subjects with ACL tears compared to the group of subjects with normal knees (1.2 mm). The fourfold increase in anterior translation of the tibia for the knees with ACL tears compared to the contralateral side is a concern because it is substantially greater than the 95% confidence limits of the side-to-side differences in anterior-posterior knee laxity measured from subjects with normal knees. This observation could explain, at least in part, one of the mechanisms that initiates damage to the meniscus and articular cartilage in subjects that have suffered an ACL tear.
To determine the prevalence of radiographic knee osteoarthritis (OA) as well as knee-related symptoms and functional limitations in female soccer players 12 years after an anterior cruciate ligament (ACL) injury.
Female soccer players who sustained an ACL injury 12 years earlier were examined with standardized weight-bearing knee radiography and 2 self-administered patient questionnaires, the Knee Injury and Osteoarthritis Outcome Score questionnaire and the Short Form 36-item health survey. Joint space narrowing and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. The cutoff value to define radiographic knee OA approximated a Kellgren/Lawrence grade of 2.
Of the available cohort of 103 female soccer players, 84 (82%) answered the questionnaires and 67 (65%) consented to undergo knee radiography. The mean age at assessment was 31 years (range 26-40 years) and mean body mass index was 23 kg/m2 (range 18-40 kg/m2). Fifty-five women (82%) had radiographic changes in their index knee, and 34 (51%) fulfilled the criterion for radiographic knee OA. Of the subjects answering the questionnaires, 63 (75%) reported having symptoms affecting their knee-related quality of life, and 28 (42%) were considered to have symptomatic radiographic knee OA. Slightly more than 60% of the players had undergone reconstructive surgery of the ACL. Using multivariate analyses, surgical reconstruction was found to have no significant influence on knee symptoms.
A very high prevalence of radiographic knee OA, pain, and functional limitations was observed in young women who sustained an ACL tear during soccer play 12 years earlier. These findings constitute a strong rationale to direct increased efforts toward prevention and better treatment of knee injury.
The objective of the current study was to use fluoroscopy to accurately determine the three-dimensional (3D), in vivo, weight-bearing kinematics of 10 normal and five anterior cruciate ligament deficient (ACLD) knees. Patient-specific bone models were derived from computed tomography (CT) data. 3D computer bone models of each subject's femur, tibia, and fibula were recreated from the CT 3D bone density data. Using a model-based 3D-to-2D imaging technique registered CT images were precisely fit onto fluoroscopic images, the full six degrees of freedom motion of the bones was measured from the images. The computer-generated 3D models of each subject's femur and tibia were precisely registered to the 2D digital fluoroscopic images using an optimization algorithm that automatically adjusts the pose of the model at various flexion/extension angles. Each subject performed a weight-bearing deep knee bend while under dynamic fluoroscopic surveillance. All 10 normal knees experienced posterior femoral translation of the lateral condyle and minimal change in position of the medial condyle with progressive knee flexion. The average amount of posterior femoral translation of the lateral condyle was 21.07 mm, whereas the average medial condyle translation was 1.94 mm, in the posterior direction. In contrast, all five ACLD knees experienced considerable change in the position of the medial condyle. The average amount of posterior femoral translation of the lateral condyle was 17.00 mm, while the medial condyle translation was 4.65 mm, in the posterior direction. In addition, the helical axis of motion was determined between maximum flexion and extension. A considerable difference was found between the center of rotation locations of the normal and ACLD subjects, with ACLD subjects exhibiting substantially higher variance in kinematic patterns.
Objective
To asses the validity of three physical diagnostic tests for the demonstration of rupture of the anterior cruciate ligament (ACL): the anterior drawer test, the Lachman test, and the pivot shift test.
Design
Meta-analysis of diagnostic studies.
Data sources
From computerised searches of Medline (1966–2004) and Embase (1980–2004), publications were selected that were written in English, French, German, or Dutch and in which the value of at least one physical diagnostic test for rupture of the ACL was assessed in comparison with the findings from arthrotomy, arthroscopy, or MRI as the reference standard.
Study selection and assessment
Two investigators independently selected the publications, assessed the methodological quality, and extracted data using a standardised protocol.
Outcomes
Wherever appropriate and possible, an estimate was made of the (pooled) sensitivity, specificity, and positive and negative predictive value of each test with the aid of a meta-analysis.
Main results
There were 17 studies identified. None of these reported blinded assessment of test, and only 2 performed the gold standard in all included patients. Summary estimates of sensitivity and specificity were 62% (95% CI 42 to 78%) and 88% (95% CI 83 to 92%) for the anterior drawer test, 86% (95% CI 76 to 92%) and 91% (95% CI 79 to 96%) for the Lachman test, and 32% and 98% (95% CIs could not be calculated) for the pivot shift test, respectively.
Conclusions
Physical diagnostic tests may be useful in the diagnosis of ACL ruptures. The clinical relevance of the test results, however, depends largely on the prior probability of the presence of such a rupture and is therefore different for general practitioners and specialists.
Quantifying the effects of anterior cruciate ligament deficiency on joint biomechanics is critical in order to better understand the mechanisms of joint degeneration in anterior cruciate ligament-deficient knees and to improve the surgical treatment of anterior cruciate ligament injuries. We investigated the changes in position of the in vivo tibiofemoral articular cartilage contact points in anterior cruciate ligament-deficient and intact contralateral knees with use of a newly developed dual orthogonal fluoroscopic and magnetic resonance imaging technique.
Nine patients with an anterior cruciate ligament rupture in one knee and a normal contralateral knee were recruited. Magnetic resonance images were acquired for both the intact and anterior cruciate ligament-deficient knees to construct computer knee models of the surfaces of the bone and cartilage. Each patient performed a single-leg weight-bearing lunge as images were recorded with use of a dual fluoroscopic system at full extension and at 15 degrees , 30 degrees , 60 degrees , and 90 degrees of flexion. The in vivo knee position at each flexion angle was then reproduced with use of the knee models and fluoroscopic images. The contact points were defined as the centroids of the areas of intersection of the tibial and femoral articular cartilage surfaces.
The contact points moved not only in the anteroposterior direction but also in the mediolateral direction in both the anterior cruciate ligament-deficient and intact knees. In the anteroposterior direction, the contact points in the medial compartment of the tibia were more posterior in the anterior cruciate ligament-deficient knees than in the intact knees at full extension and 15 degrees of flexion (p < 0.05). No significant differences were observed with regard to the anteroposterior motion of the contact points in the lateral compartment of the tibia. In the mediolateral direction, there was a significant lateral shift of the contact points in the medial compartment of the tibia toward the medial tibial spine between full extension and 60 degrees of flexion (p < 0.05). The contact points in the lateral compartment of the tibia shifted laterally, away from the lateral tibial spine, at 15 degrees and 30 degrees of flexion (p < 0.05).
In the presence of anterior cruciate ligament injury, the contact points shift both posteriorly and laterally on the surface of the tibial plateau. In the medial compartment, the contact points shift toward the medial tibial spine, a region where degeneration is observed in patients with chronic anterior cruciate ligament injuries.
Excessive tibial rotation has been documented in anterior cruciate ligament (ACL) deficiency during walking. ACL reconstruction has been unable to correct this abnormality in activities that are more demanding than walking and involve both anterior and rotational loading of the knee. These findings persist regardless of graft selection for the ACL reconstruction (bone-patellar tendon-bone or semitendinosus gracilis). Based on this research work, we propose a theoretical perspective for the development of osteoarthritis in both the ACL-deficient and the ACL-reconstructed knee. We propose that excessive tibial rotation will lead to abnormal loading of the cartilage areas that are not commonly loaded in the healthy knee. Over time, this abnormal loading will lead to osteoarthritis. We hypothesise that the development of new surgical procedures and grafts, such as a more horizontally oriented femoral tunnel or a double-bundle ACL reconstruction, could possibly restore tibial rotation to normal levels and prevent future knee pathology. However, in vivo gait analysis studies are needed to examine the effects of these surgical procedures on tibial rotation. Prospective in vivo and in vitro studies are also necessary to verify or refute our theoretical proposition for the development of osteoarthritis.
The role of cruciate ligaments in maintaining knee joint stability
- G W Rong
- Y C Wang
- GW Rong