[Show abstract][Hide abstract] ABSTRACT: When researchers describe data from their studies, there is no rule defining the best way to represent results. Therefore, collecting and explaining results from personal research or understanding data from publications is not always straightforward. These issues are even worse in fields such as biomedical engineering, where researchers from different backgrounds, usually engineers and surgeons, need to interact and exchange information. For these reasons, the purpose of this study is to introduce and illustrate an innovative method to represent, concisely and intuitively, biomechanical knee behavior, called KneePrints.
To test the KneePrints method, a huge amount of data from previously published sensitivity analyses were used and represented both with conventional techniques and with this new graphical method. Then, a survey has been distributed among different international specialists in the orthopedic field, such as surgeons and researchers. In the survey, interviewees were asked to select the favorite method that addressed to be the most effective to show the same results.
Collecting the outcomes from the survey, the KneePrints method resulted to be more effective than standard graphs, such as tables and histograms. KneePrints method has been selected to be clearer in representing outputs and more immediate in results understanding independently from the occupation of the interviewees by the survey. The general preference for the KneePrints is 63 %, up to 74 % being surgeons’ choice.
The innovative KneePrints method has been endorsed to be effective in representing and making more understandable knee joint outputs. This method can be extended also to other topics.
[Show abstract][Hide abstract] ABSTRACT: Posterior-stabilized (PS) total knee arthroplasty (TKA) designs were introduced to compensate for the resected or deficient posterior cruciate ligament and to avoid paradoxical anterior sliding of the femur. Knee joint stability may differ among patients and, therefore, orthopaedic companies developed several solutions to compensate for these differences. In particular, conventional PS designs are used for conventional TKA and semi-constrained PS designs are mainly applied in revision surgery or in conventional surgery when there is a compromised soft tissue envelope. However, despite good functional long-term results, a better understanding of forces acting on the post of the polyethylene insert is needed to find an eventual correlation with the risk of post-cam failure or loosening of the tibial baseplate for the two PS solutions. To the authors’ best knowledge, no literature data is currently available to compare the two solutions. In this paper, a validated numerical model was developed to analyse and compare the posterior of the post-cam mechanism of the same TKA design with conventional and semi-constrained inserts during several motor tasks. For each solution, different motor tasks show different values of maximum post-cam force. Comparing the two solutions, a general slightly higher force (range between 3 and 5%) is observed in the semi-constrained solution. The results concerning the conventional solution are in agreement with the literature. After this analysis, we can report that a semi-constrained design shows only slightly higher posterior post-cam contact force, and thus would not be expected to significantly increase the risk of failure of the post-cam mechanism, as compared to a conventional PS design.
[Show abstract][Hide abstract] ABSTRACT: Total knee arthroplasty (TKA) is a very successful surgical procedure. However, implant failures and patient dissatisfaction still persist. Sometimes surgeons are not able to understand and explain these negative performances because the patient's medical images "look good", but the patient "feels bad". Apart from radiograph imaging and clinical outcome scores, conventionally used follow-up methods are mainly based on the analysis of knee kinematics. However, even if kinematics remains close to the "normal" range of motion, the patient may still complain about pain and functional limitations. To provide more insight into this paradox, a better quantitative understanding of TKA mechanics must be developed. For this purpose, improved techniques for clinical follow-up, combining kinetics and kinematics analysis, should be introduced to help surgeons to assess and understand TKA performance.
An analysis on four TKA designs was performed, and the changes in kinematics and in kinetics induced by several implant configurations (simulating implant malalignment and different knee anatomy) were compared. More specifically, analysed tibio-femoral and patello-femoral contact forces and tibio-femoral kinematics were analysed during a squat task up to 120°.
The results from this study show that contact forces (with changes up to 67 %) are more heavily affected by malconfigurations than kinematics, for which maximum deviations are of the order of 5 mm or 5°, similar to the simulated surgical errors. The results present a similar trend for the different designs.
The results confirm the hypothesis that kinematics is not the only and also not the most relevant parameter to predict or explain knee function after TKA. In the future, techniques to analyse knee kinetics should be integrated in the clinical follow-up.
No preview · Article · Jan 2015 · Knee Surgery Sports Traumatology Arthroscopy
[Show abstract][Hide abstract] ABSTRACT: Purpose To evaluate the long-term functional results of arthroscopic abrasion arthroplasty for the treatment of full-thickness cartilage lesions of the medial femoral condyle. Methods Between 1990 and 1996, 75 consecutive patients with isolated chondral lesions of the medial femoral condyle were treated with arthroscopic chondral abrasion. A retrospective analysis of the clinical results of this cohort was performed. The patients were evaluated according to the Knee Society Score questionnaire preoperatively, at 10 years postoperatively, and at final long-term follow-up at a mean of 20 years. At final follow-up, they were also assessed according to the Western Ontario and McMaster Universities Osteoarthritis Index. Patients were divided according to the lesion size and by age, and the Kaplan-Meier survivorship function (with second operation taken as an endpoint) for the various groups was calculated. Results At a mean of final follow-up of 20 years (range, 16.94 to 23.94 years), a positive functional outcome (Knee Society Score ¥70 points or no reoperation) was recorded in 67.9% of the patients. Twenty-year survivorship in this cohort was 71.4% (95% confidence interval, 0.5690 to 0.8590). The survivorship was 89.5% for patients younger than 50 years and 55.7% for patients aged 50 years or older. The functional results for patients with lesions smaller than 4 cm2 were significantly better than those for patients with lesions of 4 cm2 or greater (P =.031). There were no statistical differences between patients with and without associated lesions at the time of surgery. Conclusions Our hypothesis that there would be survivorship greater than 86% was disproved. However, arthroscopic abrasion arthroplasty can be a valid treatment for medial femoral condylar full-thickness defects of the knee, even in the long-term, particularly for younger patients and those with smaller lesions. Level of Evidence Level IV, therapeutic case series.
No preview · Article · Dec 2014 · Arthroscopy The Journal of Arthroscopic and Related Surgery
[Show abstract][Hide abstract] ABSTRACT: Background
The aim of this study was to investigate the involvement of the nitric oxide (NO) pathway in osteoarthritis (OA).
The study groups consisted of 32 patients with knee OA and 31 healthy controls. In peripheral venous blood samples (from the OA patients and the controls) and in synovial fluid samples (from the OA patients), the concentrations of L-arginine (ARN), asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) were evaluated. In plasma samples, thiobarbituric acid reactive substances (TBARS) were also measured.
Plasma ARN concentrations were lower in the OA patients than in controls (53.55±16.37 vs. 70.20±25.68 μmol/l) (P<0.05), while plasma ADMA concentrations were similar. Accordingly, the ARN/ADMA ratio was lower in the OA patients than in the control group (80.85±29.58 vs. 110.51±30.48, P<0.05). Plasma SDMA and TBARS concentrations were higher in the OA patients than in controls (0.69±0.15 vs. 0.60±0.10 μmol/l, P<0.05 and 1.21±0.29 vs. 0.55±0.12, respectively) (P<0.001). In the OA patients, ADMA concentrations were significantly higher in the synovial fluid than in plasma (0.75±0.09 vs. 0.69±0.14 μmol/l, P<0.05), as were ARN concentrations (76.96±16.73 vs. 53.55±16.73 μmol/l) (P<0.00001).
These results indicate a poor availability of NO in the synovial fluid of the OA patients, which may contribute to the progression of OA. The decreased ARN/ADMA ratio and the increased SDMA and TBARS in the plasma of the OA patients suggest an impairment of endothelial function in these subjects.
Full-text · Article · Nov 2013 · Medical science monitor: international medical journal of experimental and clinical research
[Show abstract][Hide abstract] ABSTRACT: Appropriate limb length (LL) and femoral offset (OS) after total hip arthroplasty (THA) are crucial for a successful and lasting outcome. However, intraoperative assessment is difficult. Computed navigation is effective but the use of radiation and of invasive bone references is cause of concern. Imageless, pinless navigation systems have been shown to be accurate in experimental studies. However, almost no clinical validation has been performed. We used a minimally-invasive computer-navigated system (MICNS) in conjunction with an imageless measurement technique for implanting 60 consecutive THAs. Head/neck trial components of different size were applied, and the differences in LL and femoral OS measurements were recorded and compared to the implant manufacturer's specifications, corrected for the anatomical variations of each patient. The imageless MICNS revealed a valid and accurate intra-operative tool for measuring LL and femoral OS in vivo.
No preview · Article · Oct 2013 · The Journal of arthroplasty
[Show abstract][Hide abstract] ABSTRACT: Coexistence of degenerative arthritis and calcium pyrophosphate dihydrate (CPPD) crystals (or radiological chondrocalcinosis) with osteoarthritis (OA) of the knees is frequent at the time of arthroplasty. Several studies suggest more rapid clinical and radiographic progression with CPPD than with OA alone. However, it is unclear whether chondrocalcinosis predisposes to higher risks of progression of arthritis in other compartments. QUESTION/PURPOSES: We questioned whether chondrocalcinosis influences clinical scores, degeneration of other compartments, rupture of the ACL, survivorship, reason for revision, or timing of failures in case of UKA.
We retrospectively reviewed 206 patients (234 knees) who had UKAs between 1990 and 2000. Of these 234 knees, 85 had chondrocalcinosis at the time of surgery and 63 of the knees subsequently had radiographic evidence of chondrocalcinosis observed during followup. We evaluated patients with The Knee Society rating system and compared function and radiographic progression in the other compartments of patients without and with chondrocalcinosis.
The use of conventional NSAIDs, radiographic progression of OA in the opposite femorotibial compartment of the knee, failure of the ACL, and aseptic loosening did not occur more frequently among patients with chondrocalcinosis. The 15-year cumulative survival rates were 90% and 87% for the knees without and with chondrocalcinosis, respectively, using revision to TKA as the end point.
Our findings show chondrocalcinosis does not influence progression and therefore is not a contraindication to UKA.
No preview · Article · Dec 2011 · Clinical Orthopaedics and Related Research
[Show abstract][Hide abstract] ABSTRACT: Aim. Aim of this study is to evaluate arthroscopic anterior cruciate ligament (ACL) reconstruction using quadrupled hamstring tendons stabilized with a distal absorbable interference screw and a proximal suspension button device. Methods. This non-randomized prospective case series included 689 patients who underwent arthroscopic ACL reconstruction between March, 2007 and April, 2009. Follow-up visits were made at 3, 6, 12 and 24 months. Lysholm Knee Scale, International Knee Documentation Committee (IKDC) ratings and KT-1000 arthrometric evaluations were recorded for each patient. The operated knee was evaluated in comparison with the contralateral (healthy) knee. Results. The mean values at 24 months were: Lysholm Knee Score 93 points (range 90-97); IKDC 91 points (range 90-96). Arthrometric measurement at 134 N showed a mean anterior translation of 1.9 mm (range 0-4 mm), compared with the contralateral knee. Conclusion. Our results show good to excellent outcomes in patients who underwent ACL surgery with quadrupled hamstring tendon graft. This proximal fixation method should be considered a valid alternative in ACL surgery.
No preview · Article · Oct 2011 · Minerva Ortopedica e Traumatologica
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to determine if microfractures improve the outcome of high tibial osteotomy in patients with medial compartmental osteoarthritis in genu varum. Forty patients presenting with Outerbridge grade III and IV chondropathies on the femoral and/or the tibial joint surface underwent high tibial osteotomy with Puddu plates (Arthrex, Inc, Naples, Florida) for primary medial compartment osteoarthritis in genu varum at our institution. Patients were randomly assigned to either the high tibial osteotomy plus microfractures group (A; n=20) or the high tibial osteotomy alone group (B; n=20). Final assessment was conducted 5 years postoperatively, including clinical response measured by the International Knee Documentation Committee (IKDC), Lysholm score, and patient satisfaction score. All patients were blinded to the treatment received and followed the same rehabilitation protocol. A statistically significant improvement between pre- and postoperative values was observed for Lysholm and IKDC scores in both groups, without any statistically significant difference between them. Regarding the satisfaction score, there were no differences between the 2 groups in terms of preoperative self-assessment (P>.05), whereas postoperative subjective satisfaction at 5-year follow-up was significantly higher in group A than in group B (P=.0036).Our study results provide further evidence that medial tibial osteotomy is an effective surgical option for treating a varus knee associated with medial degenerative arthritis in patients wishing to continue accustomed levels of physical activity. In particular, patient satisfaction was higher among those who underwent the combined treatment involving high tibial osteotomy to correct femorotibial angle and microfractures.
[Show abstract][Hide abstract] ABSTRACT: Since its introduction in 1996, the Genesis II Total Knee System has produced good clinical results in patients undergoing primary total knee replacement. A systematic review of the literature-the first of its kind for this device-was undertaken to collect data on the Genesis II in order to provide a better understanding of its medium- to long-term performance. Of 124 Genesis II-related studies published in the literature, 11 met the eligibility criteria and were included in the final analysis. The included studies had a mean follow-up length of 38.1 months. Data from 1201 knees were available for review. Patients were an average of 70.5 years of age and predominantly female (63%). Findings indicated that the revision rate with this implant is low with up to 11.9 years of follow-up, with 14 revisions in total. The survival rate ranged from 100% at 1 and 2 years to 96.0% at 11.9 years. The mean Knee Society knee score improved 51.0 points from preoperative to postoperative evaluation. In conclusion, the Genesis II exhibited good clinical performance with up to 11 years follow-up, with an encouraging rate of survival and improvement in function. Additional studies with larger sample sizes and longer follow-up periods are needed to better understand the long-term performance of this implant.
[Show abstract][Hide abstract] ABSTRACT: Asymmetric dimethylarginine (ADMA), a methyl derivate of the amino acid arginine, is produced by the physiological degradation of methylated proteins. ADMA is the major endogenous inhibitor of nitric oxide synthase (NOS), the enzyme which synthesizes nitric oxide (NO), a molecule endowed with important anti-atherosclerotic properties. Increased plasma ADMA concentrations cause impaired NO synthesis leading to endothelial dysfunction and atherosclerotic vascular disease. Increased plasma ADMA levels mainly occur following inhibition of the enzyme responsible for ADMA catabolism, dimethylarginine dimethylaminohydrolase (DDAH), by oxidative stress triggered by several cardiovascular risk factors. This paper reviews the effects on cardiovascular function produced by ADMA administration to experimental animals and humans. In addition, a number of clinical conditions associated with increased plasma ADMA concentrations are considered. Then the growing body of literature indicating that plasma ADMA levels have a predictive value for major cardiovascular events in prospective studies is discussed. Finally, an analysis is provided of the published data concerning the possibility to modulate plasma ADMA levels using drugs belonging to different pharmacological classes.
No preview · Article · May 2009 · Medical science monitor: international medical journal of experimental and clinical research
[Show abstract][Hide abstract] ABSTRACT: Aim. Knee arthroscopy is the most common orthopedic procedure, but few data are available on the epidemiology of venous thromboembolism (VTE) after this kind of surgery. From this point of view, knee arthroscopy is considered a low-risk intervention, and clear indications for antithrombotic prophylaxis in this setting are lacking. Methods. From January 2000 to December 2006 we prospectively evaluated 1 800 patients undergoing knee arthroscopy, and considered at particularly low risk of VTE (no concomitant known risk factors, tourniquet time less than 30 min). These patients received weight-adjusted low molecular weight heparin (nadroparin calcium, 2 850 to 5 700 IU, one subcutaneous injection per day starting 6 hours after arthroscopy) for two weeks. Patients were followed-up for two weeks for the occurrence of symptomatic, instrumentally confirmed VTE, and/or bleeding episodes. Results. Seven cases of distal deep vein thrombosis were documented (overall incidence of VTE was 0.38%). The most frequent registered adverse events were mild hemarthrosis and reactions at injection site; no cases of major bleeding occurred. Conclusion. In this large cohort of low-risk patients, VTE appears as a possible complication of knee arthroscopy, though at an extent probably lowered by the systematic use of antithrombotic prophylaxis. The present study seems to support the feasibility of pharmacological antithrombotic prophylaxis in these patients, with encouraging indications as for benefit/risk ratio. Our experience might stimulate further efforts to better assess and face this open medical issue.
No preview · Article · Oct 2007 · Minerva Ortopedica e Traumatologica
[Show abstract][Hide abstract] ABSTRACT: Total knee replacement (TKR) infection represents only a small percentage of all the potential complications in joint replacement, but one that can lead to disastrous consequences. Two-stage revision, which has been proven to be the most effective technique in eradicating infection, includes prosthesis removal, positioning of an antibiotic-loaded spacer, and systemic antimicrobial therapy for at least 6 weeks. It has been suggested that there is better performance in terms of range of motion, pain, extensor mechanism shortening, and spacer-related bone loss if articulating spacers are used instead of fixed spacers. In this paper, we describe our results in two-stage revision of infected total knee arthroplasty with a minimum follow-up of 12 months on 14 patients treated by antibiotic-loaded custom-made articulating spacer as described by Villanueva et al. (Acta Orthop 77(2):329-332, 2006). The mean flexion achieved after the second stage of the revision was 120 degrees , ranging from 97 degrees to 130 degrees. The mean Hospital for Special Surgery score was 84. At 1 year after surgery, none of the knees showed any evidence of recurrence of the infection. Articulating spacers are a suitable alternative to fixed spacers with good range of motion after reimplantation and effectiveness against total knee replacement deep infections.