The ACL Handbook: Knee Biology, Mechanics, and Treatment
Abstract
ACL injuries affect the lives of hundreds of thousands of people each year. Treatment is far from perfect, and physicians and patients face challenges such as high failure rates in adolescent athletes and the inability to slow the accelerated progression of arthritis after an ACL rupture, for example. The ACL Handbook takes a complete view of ACL injuries and treatments, discussing:
- Normal ACL and knee mechanics
- The body's response to ACL injury
- Development of new treatment methods
Ideal for orthopedists, sports medicine physicians, and physical therapists, The ACL Handbook is a unique resource for information on the basic and applied science of ACL injury, repair, and the future of treatment.
Chapters (20)
... Fibroblasts are also located in the collagen line, functioning as cell communication to coordinate cellular and metabolic processes, as well as producing and maintaining the extracellular matrix. [3][4][5][6] When the ligament is exposed to extended loading, it will increase in mass and failure load, especially if the load is greater than the sustainable amount, causing partial or complete ligament rupture. Complete ligament rupture requires surgical reconstruction using autograft or allograft. ...
... Regardless of this advantage, autograft is also associated with some morbidity, such as discomfort and decreased range of motion over donor area, which may affect postoperative rehabilitation. [5][6][7] Alternatively, allograft is a tissue taken from donor of the same species. There are some advantages for using allograft, such as shorter surgery time and lack of donor-site morbidity. ...
... 8 Despite this, some studies consider allograft as the best substitute to autograft. 6 A standard method to evaluate remodeling process of bone tendon graft healing is a histologic examination of graft tissue. 9,10 Because of the difficulties getting human histologic examination due to research ethics, there are a limited number of experimental studies that directly compared autograft and allograft ligamentization, and some contradiction studies over which one is the best graft option for ACL reconstruction. ...
Objective: The purpose of this meta-analysis is to compare ligament healing on autograft and allograft in anterior cruciate ligament (ACL) reconstruction.
Methods: The selection of appropriate studies was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We made a statistical analysis using a review manager. Electronic reports were searched using the PubMed, Medline, and Cochrane Library databases. The inclusion criteria were animal studies and cellular histology of both grafts as an outcome.
Results: The initial search revealed 412 potential articles. After duplicates were removed, 246 articles remained. Then, 14 articles were obtained and screened for relevance and eligibility. The relevant articles were searched manually, checking for eligibility and details in order not to miss included reports. Subsequently, 5 studies were included, with a total of 232 samples, reporting the biopsied results with quantitative histology of ligament healing between allograft and autograft. The biopsy samples in those studies were examined under light or electron microscope, to analyze the cellular distribution area and ligamentization stages in each group. Meta-analyses found significant difference between autograft and allograft (Heterogeneity, I2 = 89%; Mean Difference, 95% confidence interval [CI] = −34.92, −54.90, −14.93; p = 0.0006). There is also a significant difference on both graft in cellular count at over 24 weeks (Heterogeneity, I2 = 26%; Mean Difference, 95% CI = −14.59, −16.24, −12.94; p < 0.00001).
Conclusion: In the current meta-analysis, autograft shows a significant difference when compared to allograft, with more cellular accumulation and faster remodeling response on the ligamentization process being noticed in the former. However, a larger clinical trial will be needed to emphasize this literature's result.
... In the USA about 100,000 ACL reconstructions (ACLR) are performed annually (De Wang et al., 2018) and in the Netherlands about 9000 (Engelen-van Melick et al., 2014). ACL tears do not spontaneously heal, among other reasons, due to its low vascularity (The ACL Handbook, 2013). Therefore, autografts (Slone et al., 2015), allografts (Wright et al., 2010;McGuire and Hendricks, 2009), and bioengineered strategies (Fleming et al., 2009;Kiapour and Murray, 2014) have been developed to treat ACL tears (Jones et al., 2017). ...
... Ligaments and tendons are fundamentally different both in function and composition. Different from tendon grafts currently used in the clinic, the ACL consists of two bundles: the anteromedial (AM) and the posterolateral (PL) bundle, which both contribute to knee stability in their own specific way (The ACL Handbook, 2013;Skelley et al., 2017). Additionally, the ACL has a characteristic wavy and helical crimp pattern of collagen type-I (Freeman et al., 2009), together with a relatively high elastin content (Smith et al., 2014). ...
... Additionally, the ACL has a characteristic wavy and helical crimp pattern of collagen type-I (Freeman et al., 2009), together with a relatively high elastin content (Smith et al., 2014). These factors make ACL a compliant tissue at low strains and a high load-bearing tissue at high strains (The ACL Handbook, 2013). Contrary, tendons grafts have a higher collagen type-I density, a lower collagen type-III density, and lower elastin density when compared to human ACLs (Hadjicostas et al., 2008;West and Harner, 2005). ...
Approximately 1% of active individuals participating in sports rupture their anterior cruciate ligaments (ACL) every year, which is currently reconstructed using tendon autografts. Upon reconstruction, clinical issues of concern are ACL graft rupture, persistent knee instability, limited return to sports, and early onset of osteoarthritis (OA). This happens because tendon autografts do not have the same compositional, structural, and mechanical properties as a native ACL. To overcome these problems, we propose to use decellularized bone-ACL-bone allografts in ACL reconstruction (ACLR) as a mechanically robust, biocompatible, and immunologically safe alternative to autografts. Here, a decellularization protocol combined with sterilization using supercritical carbon dioxide (scCO2) was used to thoroughly decellularize porcine and human ACLs attached to tibial and femoral bone blocks. The specimens were named ultrACLean and their compositional, structural, and mechanical properties were determined. Our results indicate that: 1) decellularization of ultrACLean allografts leads to the removal of nearly 97% of donor cells, 2) ultrACLean has mechanical properties which are not different to native ACL, 3) ultrACLean maintained similar collagen content and decreased GAG content compared to native ACL, and 4) ultrACLean is not cytotoxic to seeded tendon-derived cells in vitro. Results from an in vivo pilot experiment showed that ultrACLean is biocompatible and elicits a moderate immunological response. In summary, ultrACLean has proven to be a mechanically competent and biocompatible graft with the potential to be used in ACLR surgery.
... Une fois la reprise de l'entraînement réalisée, tout n'est pas encore gagné pour le patient/sportif. C'est malheureusement pendant les premiers mois de retour à l'entraînement que l'on retrouve le plus de reblessure (rupture itérative ou controlatérale) [14,37]. Durant cette phase, le travail athlétique est poursuivi par le sportif et il semble important qu'une prise en charge rééducative soit poursuivie, axée sur les déficits persistants (de mobilité, de force, de proprioception). ...
... Selon les caractéristiques anatomiques et biomécaniques du « système 4 barres » constitué par le pivot central, Chambat [2,17] en conclut que seule une « non isométrie favorable » doit être recherchée, c'est-à-dire une position qui met le transplant en tension lors de l´extension; ainsi, comme pour le LCA natif, il existera lors de l´extension un recrutement progressif des fibres, allant des plus antérieures (les plus isométriques) vers les plus postérieure. Pour cela, il faut positionner le transplant au niveau fémoral juste en arrière du point isométrique, car il s´agit de la position anatomique [2,20,21]. ...
Recent studies about anterior cruciate ligament (ACL) surgery have focused on a better control of rotational stability, but ACL reconstruction is always a topical issue. The purpose of our study was to evaluate clinical and radiological outcomes after the use of the technique for anatomical reconstruction of the ACL with fascia lata, according to Macintosh technique modified by J.H Jaeger. We conducted a study of a continuous series of 80 patients between 2005 and 2019. All patients were assessed according to the International Knee Documentation Committee (IKDC) score and the Lysholm and Tegner scale. All our patients were rated as excellent with an average score of 92. Occasional lateral residual pain was reported by 8 patients. Residual jerk accounted for 2.5%. Radiological examination did not show ballooning or arthrosis at the last follow-up. Anterior cruciate ligament reconstruction is a common procedure that has become more reliable over time. But pivot shift (Jerk test) requires a lateral tenodesis "external rotation", especially in athletes.
... Journal of Orthopaedic Surgery 28(1) ...
Introduction
The effect of leg dominance on anterior cruciate ligament (ACL) injuries has been studied with some studies noting a propensity for injuries in the non-dominant leg. Its effect on post-ACL reconstruction recovery, however, is not well known. The authors hypothesize that dominant limb injuries undergo rehabilitation faster and positively affect early functional outcome scores and return to sports and set about studying these effects.
Methods
This is a retrospective study of 254 patients from a single institution who underwent ACL reconstruction for acute ACL ruptures and the results were compared between patients with dominant and non-dominant limb injuries. Objective measurements including the KT-1000, single-leg hop distance and Biodex knee extension peak torque were used to evaluate recovery. Pre- and post-operative functional outcome scores such as the International Knee Documentation Committee (IKDC), Tegner activity score and Lysholm knee scale were documented.
Results
Early functional outcomes were similar. Minimal clinically important difference (MCID) improvement in IKDC scores was achieved in 69.7% of the dominant versus 66.0% of the non-dominant injury group ( p = 0.99), 75.2% versus 79.6% ( p = 0.45) for the Lysholm knee scale, and 81.6% versus 84.9% ( p = 0.50) for the Tegner activity score. The majority of patients in both subgroups had a return of at least 80% of peak knee flexion and extension peak torque at 5.4 months post-operatively; 92.9% of subjects with a non-dominant leg injury and 87.2% with a dominant leg injury had returned to their pre-injury sports 1 year from surgery.
Conclusions
Results from this study suggest that despite theoretical differences, leg dominance does not have a significant impact on short-term functional outcomes and return to sports. Objective measurements suggest that limb strength recovers at a comparable rate. Injuries to either leg demonstrate equally positive improvement post-ACL reconstruction given the same post-operative rehabilitation.
Level of Evidence
III, retrospective comparative study.
Level of Evidence
III, retrospective cohort study.
... In recent years, injuries to the anterior cruciate ligament (ACL) have become a real epidemic. The injury most often concerns young, physically active individuals aged 15-25 years [1]. As many as 70% of ACL injuries are non-contact injuries, which most frequently occur during a sudden change of running direction or landing after a jump [2,3]. ...
Introduction: Injury to the anterior cruciate ligament (ACL) causes disorders in the functional capabilities of the limb, both in daily life and during attempts to return to full physical activity, and in a later period it contributes to the development of degenerative disease. Aim of the research: Determination of the level of quality of life in patients after ACL reconstruction using the LARS synthetic ligament or autogenous ST/GR graft 4 years after surgery. Material and methods: Into the study were qualified 96 patients who had undergone reconstruction due to injury to the anterior cruciate ligament. The patients were divided into two groups according to the type of material used for reconstruction. The study group included 44 (45.8%) patients who were operated on using the LARS synthetic ligament. The control group comprised 52 (54.2%) patients who were implanted with an autogenous graft from semitendinous or gracilis muscle. The study was conducted using the SF36v2 questionnaire for the assessment of quality of life.
Results: The patients expressed the most negative evaluations of quality of life in the domain of General Health (GH) (x= 62.5 scores) and Mental Health (MH) (x = 70.4 scores), whereas most positive evaluations concerned the domain related with role limitations – caused both by physical health (Role Pysical – RP) and emotional problems (Role Emotional – RE) (x > 95 scores). No statistically significant differences in the level of the quality of life were observed in the two selected groups; however, the evaluation of the quality of life in the area of social functioning and psychological health were slightly higher in the group of patients who had undergone surgery using the LARS method.
Conclusions: The quality of life of patients within the period of 4 years after ACL reconstruction procedure using the LARS
... 1 Among these injuries rupture of the anterior cruciate ligament (ACL), appearing due to rotary motion of the knee joint with fixed lower leg, 2,3 is the most frequent ligament injury (47%) and results in dynamic destabilization and loss of mobility. [4][5][6] Conventional reconstructions are made of autologous tissue of the patellar and semitendinosus tendon. 6,7 Disadvantages such as the limited availability, the high morbidity rate and a deviant mechanical behavior 8,9 lead to the introduction of non-resorbable synthetic grafts, such as the Leeds-Keio prosthesis. ...
Traumatic rupture of the anterior cruciate ligament (ACL) can cause local destabilization and loss of mobility. Reconstruction using engineered ACL grafts is rarely successful due to sub-optimal material choice and mechanical performance.
Thus, the presented work demonstrates the fabrication of various embroidered single- and bi-component scaffolds made of two commercially available monofilament threads (polydioxanone, poly(lactic acid-co-ɛ- caprolactone)) as well as a novel melt spun poly(L-lactic acid) multifilament and their mechanical analysis by tensile tests and under cyclic loading.
Selected scaffolds, adjusted by material composition and textile parameters, revealed a load–strain behavior comparable to native lapin ACL tissue exhibiting a sufficient amount of elastic deformation within the toe-region of 1.7%, scaffold stiffness of 123 N/mm and adequate maximum tensile load (300 N) and strain (20%). Therefore, the design of resorbable embroidered bi-component scaffolds represents a promising approach to replace artificial non-resorbable ligament grafts and allows for innovative tissue engineering strategies.
The current gold standard technique for the treatment of anterior cruciate ligament (ACL) injury is reconstruction with a tendon autograft. These treatments have a relatively high failure and re-rupture rate and are associated with early-onset osteoarthritis, developing within two decades of injury. Furthermore, both autografting and allografting come with several drawbacks. Tissue engineering and additive manufacturing present exciting new opportunities to explore 3D scaffolds as graft substitutes. We previously showed that 3D-printed scaffolds using low-cost equipment are suitable for tissue engineering approaches to regenerative medicine. Here, we hypothesize that Lay-Fomm 60, a commercially available nanoporous elastomer, may be a viable tissue engineering candidate for an ACL graft substitute. We first printed nanoporous thermoplastic elastomer scaffolds using low-cost desktop 3D printers and determined the mechanical and morphological properties. We then tested the impact of different surface coatings on primary human ACL fibroblast adhesion, growth, and ligamentous matrix deposition in vitro. Our data suggest that poly-L-lysine-coated Lay-Fomm 60 scaffolds increased ligament fibroblast activity and matrix formation when compared to uncoated scaffolds but did not have a significant effect on cell attachment and proliferation. Therefore, uncoated 3D printed Lay-Fomm 60 scaffolds may be viable standalone scaffolds and warrant further research as ligament tissue engineering and reconstruction grafts.
Patellofemoral pain syndrome (PFPS, patellar chondromalacia) after knee surgery is an important problem in sports medicine, solutions to which have not been developed enough.
Objective : to determine the effect of complex treatment using an injectable chondroprotector and special exercise therapy on the functional state, statokinetic stability and severity of PFPS in athletes after reconstruction of the anterior cruciate ligament (ACL) of the knee joint.
Patients and methods . An observational randomized controlled trial included 40 athletes after ACL reconstruction. The patients were divided into two groups. In the control group (n=20), a special rehabilitation technique was used after ACL reconstruction. In the main group (n=20), along with a similar method of rehabilitation, patients received a course of intramuscular injections of Alflutop (1 ml, No. 20). The duration of rehabilitation treatment was 1 month.
Pain was assessed using a numerical rating scale and knee joint function using the Kujala questionnaire, statokinetic stability was assessed before and after complex rehabilitation treatment.
Results and discussion . One month after the start of rehabilitation measures, both groups showed a significant decrease in pain intensity and an improvement in the functional state of the knee joint according to the Kujala questionnaire. The study of statokinetic stability indicators showed that after the course of rehabilitation in both groups, when standing with open eyes, there was a decrease in the area of the common center of pressure — CCOP (p<0.05) and an improvement in statokinetic stability, and when standing with eyes closed, a decrease in the CCOP area (p<0.05). At the same time, the difference in the results before and after the course of rehabilitation in the main group was significantly greater than in the control (p<0.05). The speed of the CCOP movement with open eyes in both groups did not change significantly: when standing with eyes closed, its positive dynamics was revealed after the course of rehabilitation (p<0.05).
Conclusion . Intramuscular SYSADOA injection therapy, which was used as part of a rehabilitation program, reduced pain and improved the function of the knee joint and had a positive effect on statokinetic stability in athletes after ACL reconstruction.
Aims
The anterior cruciate ligament (ACL) is known to have a poor wound healing capacity, whereas other ligaments outside of the knee joint capsule such as the medial collateral ligament (MCL) apparently heal more easily. Plasmin has been identified as a major component in the synovial fluid that varies among patients. The aim of this study was to test whether plasmin, a component of synovial fluid, could be a main factor responsible for the poor wound healing capacity of the ACL.
Methods
The effects of increasing concentrations of plasmin (0, 0.1, 1, 10, and 50 µg/ml) onto the wound closing speed (WCS) of primary ACL-derived ligamentocytes (ACL-LCs) were tested using wound scratch assay and time-lapse phase-contrast microscopy. Additionally, relative expression changes (quantitative PCR (qPCR)) of major LC-relevant genes and catabolic genes were investigated. The positive controls were 10% fetal calf serum (FCS) and platelet-derived growth factor (PDGF).
Results
WCS did not differ significantly among no plasmin versus each of the tested concentrations (six donors). The positive controls with PDGF and with FCS differed significantly from the negative controls. However, we found a trend demonstrating that higher plasmin concentrations up-regulate the expression of matrix metalloproteinase 13 ( MMP13), 3 ( MMP3), and tenomodulin ( TNMD).
Conclusion
The clinical relevance of this study is the possibility that it is not solely the plasmin, but also additional factors in the synovial fluid of the knee, that may be responsible for the poor healing capacity of the ACL. Cite this article: Bone Joint Res 2020;9(9):543–553.
PurposeTo determine clinical and neuromuscular properties in patients with normal or sub-normal subjective knee function after finalisation of 6 months’ post-operative rehabilitation following anterior cruciate ligament reconstruction (ACLR).Methods
Sixty patients after primary anatomical single-bundle hamstring ACLR were prospectively enrolled. Demographics, subjective, clinical and functional status of the injured knee were recorded at baseline, 6 and 12 months post-operatively. Return to pre-injury activities time (months) was monitored. Tensiomyography and isokinetic dynamometry of thigh muscles were performed at 6 months, when standard ACLR rehabilitation is finalized. Based on their IKDC Subjective Knee Evaluation scores at 6 months, they were assigned into “Normal” or “Sub-normal” group. All the above measured parameters were then compared between the two groups.ResultsAt 6 months’ timeline, 21 patients (35%) perceived their knee function as “Normal”, while 39 (65%) were “Sub-normal”. There were no differences in clinical status between both groups, but patients in Normal group achieved higher IKDC, Lysholm, Tegner scores as well as higher single-leg hop test. They were taller, had lower body mass index and more of them achieved their preinjury level of activity at 12 months (67% vs. 33%). Tensiomyography revealed higher biceps femoris as well as semitendinosus and semimembranosus radial displacement values on the operated leg in Normal group. Isokinetic dynamometry showed significantly higher normalised peak torque and average power of knee extensor muscles.Conclusions
Patients who perceive their knee function as normal at 6 months following ACLR presented with better neuromuscular properties of the thigh muscles. Decreased hamstring stiffness seems to be the key to higher return-to-preinjury activity. Postoperative rehabilitation should be more focused on reducing hamstring stiffness in addition to improving knee extensor muscle strength.Level of evidence II (prospective cohort study).
Full-text available at: https://rdcu.be/b3tYI
A rupture of the anterior cruciate ligament (ACL) is the most common knee ligament injury. Current applied reconstruction methods have limitations in terms of graft availability and mechanical properties. A new approach could be the use of a tissue engineering construct that temporarily reflects the mechanical properties of native ligament tissues and acts as a carrier structure for cell seeding. In this study, embroidered scaffolds composed of polylactic acid (PLA) and poly(lactic-co-ε-caprolactone) (P(LA-CL)) threads were tested mechanically for their viscoelastic behavior under in vitro degradation. The relaxation behavior of both scaffold types (moco: mono-component scaffold made of PLA threads, bico: bi-component scaffold made of PLA and P(LA-CL) threads) was comparable to native lapine ACL. Most of the lapine ACL cells survived 32 days of cell culture and grew along the fibers. Cell vitality was comparable for moco and bico scaffolds. Lapine ACL cells were able to adhere to the polymer surfaces and spread along the threads throughout the scaffold. The mechanical behavior of degrading matrices with and without cells showed no significant differences. These results demonstrate the potential of embroidered scaffolds as an ACL tissue engineering approach.
Background
Anterior cruciate ligament (ACL) injury is one of the most common injuries of the knee joint and is becoming more prevalent. While ACL reconstruction is considered the “gold standard” of treatment, some studies have demonstrated natural spontaneous healing of the ACL in humans, rabbits, and rats. At this time, the mechanism of ACL healing is poorly understood.
Aims
The purpose of this study was to determine the process of ACL healing by examining the molecular and histological changes in the acute phases, using an ACL-Transection model and a spontaneous ACL healing model.
Methods
Sixty adult male Wistar rats were randomly assigned to two groups: the ACL transection (ACLT) group and the controlled abnormal movement (CAM) group. Thirty rats were randomly assigned to three groups (day 1, day 3, and day 5). Then, all rats underwent an ACL transection procedure. The CAM group rats underwent controlled abnormal extra-articular tibial translation. Samples were harvested from rats and used for histological and biochemical analyses.
Results
Both, the ACLT and the CAM groups exhibited ruptured ACLs. However, in the CAM group, the ends of the proximal remnants were not retracted. Expressions of MMP-3 and PDGF-α increased, and expression of TGF-β1 decreased in the CAM group on day 5 (p < 0.01); PDGF-β expression in the CAM group increased significantly at each time point (p < 0.01).
Conclusion
Our results suggested that controlling abnormal movements changed intra-articular responses positively during the acute phase both histologically and biochemically.
Background:
Implicit (IF) and explicit (EF) feedback are two motor learning strategies demonstrated to alter movement patterns. There is conflicting evidence on which strategy produces better outcomes. The purpose of this study was to examine the effects of reduced IF and EF video feedback on lower extremity landing mechanics.
Methods:
Thirty participants (24 ± 2 years, 1.7 ± 0.1 m, 70 ± 11 kg) were randomly assigned to three groups: IF (n = 10), EF (n = 10), and control (CG) (n = 10). They performed twelve box-drop jumps three times a week on the training sessions for six weeks. Only IF and EF groups received video feedback on the training sessions. IF was cued to focus their attention on the overall jump, while EF was cued to focus on position of their knees. 3D lower extremity biomechanics were tested on testing sessions with no feedback. All sessions were at least 24 h apart from another. Testing sessions included baseline testing (pretest), testing after 3 training sessions with 100% feedback (pst1), testing after 6 training sessions with 33.3% feedback (pst2), testing after 6 training sessions with 16.6% feedback (Pst3), and testing 1 month after with no feedback (retention - ret). ANOVA compared differences between groups and time at initial contact and peak for hip flexion (HF, °) and abduction angle (HA, °), hip abduction moment (HAM, Nm/kgm), knee flexion (KF, °) and abduction angle (KA, °), knee abduction moment (KAM, Nm/kgm) and VGRF (N) (p < 0.05).
Results:
A significant main effect for group was found between IF and EF groups for HA (IF = - 6.7 ± 4; EF = - 9.4 ± 4.1) and KAM (IF = 0.05 ± 0.2; EF = - 0.07 ± 0.2) at initial contact, and peaks HA (IF = - 3.5 ± 4.5; EF = - 7.9 ± 4.7) and HAM (IF = 1.1 ± 0.6; EF = 0.9 ± 0.4). A significant main effect for time at initial contact for HF (pre = 32.4 ± 3.2; pst2 = 36.9 ± 3.2; pst3 = 37.9 ± 3.7; ret. = 34.1 ± 3.7), HAM (pre = 0.1 ± 0.1; pst1 = 0.04 ± 0.1; pst3 = 0.1 ± 0.01), KA (pre = 0.7 ± 1.1; pst1 = 0.2 ± 1.2; pst3 = 1.7 ± 1), and KAM (pre = 0.003 ± 0.1; pst3 = 0.01 ± 0.1) was found.
Discussion/conclusion:
We found that implicit feedback produced positive changes in landing mechanics while explicit feedback degraded motor learning. Our results indicate that implicit feedback should be used in programs to lower the ACL injury risk. We suggest that implicit feedback should be frequent in the beginning and not be reduced as much following the acquisition phase.
Injuries of the anterior cruciate ligament are the most common ligament injuries in the knee joint that require surgery for treatment. Their incidence is particularly high in adolescent female athletes that are involved in sports including soccer and basketball. As muscular imbalances at this particular age are likely contributors to the increased risk of injury in this group, specific exercise regimens can be actively pursued by the adolescent female athlete to prevent ACL injury from occurring. ACL injuries have potential immediate and long-term consequences, including surgery and lengthy rehabilitation as well as the development of osteoarthritis. The current gold standard of treatment involves replacement of the injured anterior cruciate ligament with a tendon graft to reestablish gross stability of the knee joint. Most commonly, sections of the hamstring tendon or the middle third of the patella tendon are used as the graft material. Recovery can be lengthy and contributes to the financial burden that comes with this injury. The long and intensive physical therapy that is needed after surgery focuses on strengthening the muscles around the knee to minimize the chance of reinjury. In the future, focus will be set on further improving injury prevention and the development of less invasive surgical techniques.
‘Nothing ruins good results like long term follow-up.’Author unknown
About 43 years ago, 2 bright young academic orthopaedic team doctors decided to review the results of anterior cruciate ligament (ACL) repair in their West Point cadet population. These initial results seemed very promising (greater than 80% good-to-excellent outcomes) at the 2-year follow-up published as an abstract in the Journal of Bone and Joint Surgery in 1972; however, instead of resting on their 2-year outcomes, they made the decision to look at this same group 5 years after surgery. What they found was very alarming and humbling in that the majority of this population had poor outcomes. Being of the highest moral integrity and calibre, they wrote up their results and submitted it to the American Journal of Sports Medicine in 1976. Ironically, the editor of the journal was the legendary Jack Hughston who was well known not to be an advocate of ACL surgery. This article most likely further fuelled his beliefs (‘gasoline on the fire’, so to say!). Since this publication over 40 years ago, there has been an explosion of basic science and clinical papers on ACL anatomy, biomechanics, healing, injury and surgical techniques. The purpose of revisiting this ‘Classic’ article is to acquire perspectives from both the original authors, Dr John Feagin and Dr Walton Curl, in conjunction with Dr Martha Murray, who is considered one of the leading experts on the science of ACL repair. This article begins with a detailed review of this ‘Classic’ and highlights the main take home points. Next, there is a discussion about the historical perspectives, the scientific and societal impact, and where we are today with basic and clinical science studies. We conclude with where we are with ACL repair in 2016 and make recommendations based on current evidence for this procedure in the spectrum of ACL surgery. The ultimate goal of this review is to expose our readership to the potential use of these techniques for select patients with ACL injuries. Most importantly, one must not overlook the primary take home message of this ‘Classic Revisited’, that careful and honest long-term follow-up is the key to evidence-based medicine.
Background:
Knee injuries are common in older adolescent and adult female soccer players, and abnormal valgus knee appearance characterized by low normalized knee separation (NKS) is a proposed injury risk factor. What constitutes normal NKS in younger adolescents and whether low NKS is an injury risk factor are unknown.
Purpose:
To determine the normal range of NKS using a drop-jump test in female perimenarchal youth soccer players and whether low NKS contributes to lower extremity injuries or knee injuries.
Study design:
Cohort study; Level of evidence, 2.
Methods:
From 2008 to 2012, a total of 351 female elite youth soccer players (age range, 11-14 years) were followed for 1 season, with complete follow-up on 92.3% of players. Baseline drop-jump testing was performed preseason. Lower extremity injuries during the season were identified using a validated, Internet-based injury surveillance system with weekly email reporting. Normalized knee separation at prelanding, landing, and takeoff was categorized 2 ways: as ≤10th percentile (most extreme valgus appearance) compared with >10th percentile and as a continuous measure of 1 SD. Poisson regression modeling with adjustment for clustering by team estimated the relative risk (RR) and 95% confidence interval (CI) of the association between the NKS and the risk of lower extremity and knee injury, stratified by menarche.
Results:
Of the study participants, 134 players experienced 173 lower extremity injuries, with 43 (24.9%) knee injuries. For postmenarchal players (n = 210), those with NKS ≤10th percentile were at 92% increased risk of lower extremity injury (RR, 1.92; 95% CI, 1.17-3.15) and a 3.62-fold increased risk of knee injury (RR, 3.62; 95% CI, 1.18-11.09) compared with NKS >10th percentile at prelanding and landing, respectively. Among postmenarchal players, there was an 80% increased risk of knee injury (RR, 1.80; 95% CI, 1.01-3.23) with a decrease of 1 SD in landing NKS and a 66% increased risk of knee injury (RR, 1.66; 95% CI, 1.04-2.64) with a decrease of 1 SD in takeoff NKS. Among premenarchal players (n = 141), there was no statistically significant association between the NKS at prelanding, landing, and takeoff and the risk of lower extremity or knee injury.
Conclusion:
Low NKS was associated with increased risk of lower extremity and knee injury only among postmenarchal players.
ResearchGate has not been able to resolve any references for this publication.