Minimal clinically important change of knee flexion in people with knee osteoarthritis after non-surgical interventions using a meta-analytical approach.

BACKGROUND: Minimal clinically important change (MCIC) represents the minimum patient-perceived improvement in an outcome after treatment, in an individual or within a group over time. This study aimed to determine MCIC of knee flexion in people with knee OA after non-surgical interventions using a meta-analytical approach. METHODS: Four databases (MEDLINE, Cochrane, Web of Science and CINAHL) were searched for studies of randomised clinical trials of non-surgical interventions with intervention duration of ≤ 3 months that reported change in (Δ) (mean change between baseline and immediately after the intervention) knee flexion with Δ pain or Δ function measured using tools that have established MCIC values. The risk of bias in the included studies was assessed using version 2 of the Cochrane risk-of-bias tool for randomised trials (RoB 2). Bayesian meta-analytic models were used to determine relationships between Δ flexion with Δ pain and Δ function after non-surgical interventions and MCIC of knee flexion. RESULTS: Seventy-two studies (k = 72, n = 5174) were eligible. Meta-analyses included 140 intervention arms (k = 61, n = 4516) that reported Δ flexion with Δ pain using the visual analog scale (pain-VAS) and Δ function using the Western Ontario and McMaster Universities Osteoarthritis Index function subscale (function-WOMAC). Linear relationships between Δ pain at rest-VAS (0-100 mm) with Δ flexion were - 0.29 (- 0.44; - 0.15) (ß: posterior median (CrI: credible interval)). Relationships between Δ pain during activity VAS and Δ flexion were - 0.29 (- 0.41, - 0.18), and Δ pain-general VAS and Δ flexion were - 0.33 (- 0.42, - 0.23). The relationship between Δ function-WOMAC (out of 100) and Δ flexion was - 0.15 (- 0.25, - 0.07). Increased Δ flexion was associated with decreased Δ pain-VAS and increased Δ function-WOMAC. The point estimates for MCIC of knee flexion ranged from 3.8 to 6.4°. CONCLUSIONS: The estimated knee flexion MCIC values from this study are the first to be reported using a novel meta-analytical method. The novel meta-analytical method may be useful to estimate MCIC for other measures where anchor questions are problematic. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022323927.

Are Kinematics an Indicator of Outcome After Total Knee Arthroplasty?

BACKGROUND: A proportion of total knee arthroplasty (TKA) patients are dissatisfied postoperatively, particularly with their ability to perform higher-demand activities including deep-kneeling and step-up where kinematic parameters are more demanding. The purpose of this study was to examine the relationship between knee kinematics of step-up and deep-kneeling and patient-reported outcome measures following TKA. METHODS: Sixty-four patients were included at minimum 1-year follow-up. Participants performed a step-up and deep-kneeling task which was imaged via single-plane fluoroscopy. 3-dimensional prosthesis computer-aided design models were registered to the fluoroscopy, yielding in-vivo kinematic data. Associations between kinematics and patient-reported outcome measures, including Oxford Knee Score, American Knee Society Score, surgical satisfaction, and pain were assessed using log-transformed step-wise linear regressions. RESULTS: A higher total Oxford Knee Score was associated with more external rotation and more adduction at maximal flexion during kneeling and more external rotation and minimum flexion during step-up. Improved American Knee Society Score was associated with increased internal-external rotation during step-up. Improved surgical satisfaction was associated with greater maximum flexion and more external rotation at maximal flexion during deep-kneeling and more femoral internal rotation at terminal extension during step-up. An improved pain score was associated with greater maximum flexion and more femoral external rotation during deep-kneeling, as well as greater internal femoral rotation during step-up. CONCLUSION: The ability to move through full flexion/extension range and end-of-range rotation is important kinematic parameters that influence patient-reported outcome measures. Implant designs and postoperative rehabilitation should continue to focus on achieving these kinematic targets for enhanced outcomes after TKA.

Minimal important change and difference for knee osteoarthritis outcome measurement tools after non-surgical interventions: a systematic review.

OBJECTIVES: To systematically review and provide estimates of the minimal important change (MIC) and difference (MID) for outcome tools in people with knee osteoarthritis (OA) after non-surgical interventions. Design A systematic review. DATA SOURCES: MEDLINE, CINAHL, Web of Science, Scopus and Cochrane databases were searched up to 21 September 2021. ELIGIBILITY CRITERIA: We included studies that calculated MIC and MID using any calculation method including anchor, consensus and distribution methods, for any knee OA outcome tool after non-surgical interventions. DATA EXTRACTION AND SYNTHESIS: We extracted reported MIC, MID and minimum detectable change (MDC) estimates. We used quality assessment tools appropriate to the studies' methods to screen out low-quality studies. Values were combined to produce a median and range, for each method. RESULTS: Forty-eight studies were eligible (anchor-k=12, consensus-k=1 and distribution-k=35). MIC values for 13 outcome tools including Knee injury and Osteoarthritis Outcome Score (KOOS)-pain, activities of daily living (ADL), quality of life (QOL) and Western Ontario and McMaster Universities Arthritis Index (WOMAC)-function were estimated using 5 high-quality anchor studies. MID values for 23 tools including KOOS-pain, ADL, QOL and WOMAC-function, stiffness and total were estimated using 6 high-quality anchor studies. One moderate quality consensus study reported MIC for pain, function and global assessment. MDC values from distribution method estimates for 126 tools including KOOS-QOL and WOMAC-total were estimated using 38 good-to-fair-quality studies. CONCLUSION: Median MIC, MID and MDC estimates were reported for outcome tools in people with knee OA after non-surgical interventions. The results of this review clarify the current understanding of MIC, MID and MDC in the knee OA population. However, some estimates suggest considerable heterogeneity and require careful interpretation. PROSPERO REGISTRATION NUMBER: CRD42020215952.

Evidence for key individual characteristics associated with outcomes following combined first-line interventions for knee osteoarthritis: A systematic review.

OBJECTIVE: To identify individual characteristics associated with outcomes following combined first-line interventions for knee osteoarthritis. METHODS: MEDLINE, CINAHL, Scopus, Web of Science Core Collection and the Cochrane library were searched. Studies were included if they reported an association between baseline factors and change in pain or function following combined exercise therapy, osteoarthritis education, or weight management interventions for knee osteoarthritis. Risk of bias was assessed using Quality in Prognostic Factor Studies. Data was visualised and a narrative synthesis was conducted for key factors (age, sex, BMI, comorbidity, depression, and imaging severity). RESULTS: 32 studies were included. Being female compared to male was associated with 2-3 times the odds of a positive response. Older age was associated with reduced odds of a positive response. The effect size (less than 10% reduction) is unlikely to be clinically relevant. It was difficult to conclude whether BMI, comorbidity, depression and imaging severity were associated with pain and function outcomes following a combined first-line intervention for knee osteoarthritis. Low to very low certainty evidence was found for sex, BMI, depression, comorbidity and imaging severity and moderate certainty evidence for age. Varying study methods contributed to some difficulty in drawing clear conclusions. CONCLUSIONS: This systematic review found no clear evidence to suggest factors such as age, sex, BMI, OA severity and presence of depression or comorbidities are associated with the response to first-line interventions for knee OA. Current evidence indicates that some groups of people may respond equally to first-line interventions, such as those with or without comorbidities. First-line interventions consisting of exercise therapy, education, and weight loss for people with knee OA should be recommended irrespective of sex, age, obesity, comorbidity, depression and imaging findings.

Effects of neuromuscular gait modification strategies on indicators of knee joint load in people with medial knee osteoarthritis: A systematic review and meta-analysis.

OBJECTIVES: This systematic review aimed to determine the effects of neuromuscular gait modification strategies on indicators of medial knee joint load in people with medial knee osteoarthritis. METHODS: Databases (Embase, MEDLINE, Cochrane Central, CINAHL and PubMed) were searched for studies of gait interventions aimed at reducing medial knee joint load indicators for adults with medial knee osteoarthritis. Studies evaluating gait aids or orthoses were excluded. Hedges' g effect sizes (ES) before and after gait retraining were estimated for inclusion in quality-adjusted meta-analysis models. Certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. RESULTS: Seventeen studies (k = 17; n = 362) included two randomised placebo-controlled trials (RCT), four randomised cross-over trials, two case studies and nine cohort studies. The studies consisted of gait strategies of ipsilateral trunk lean (k = 4, n = 73), toe-out (k = 6, n = 104), toe-in (k = 5, n = 89), medial knee thrust (k = 3, n = 61), medial weight transfer at the foot (k = 1, n = 10), wider steps (k = 1, n = 15) and external knee adduction moment (KAM) biofeedback (k = 3, n = 84). Meta-analyses found that ipsilateral trunk lean reduced early stance peak KAM (KAM1, ES and 95%CI: -0.67, -1.01 to -0.33) with a dose-response effect and reduced KAM impulse (-0.37, -0.70 to -0.04) immediately after single-session training. Toe-out had no effect on KAM1 but reduced late stance peak KAM (KAM2; -0.42, -0.73 to -0.11) immediately post-training for single-session, 10 or 16-week interventions. Toe-in reduced KAM1 (-0.51, -0.81 to -0.20) and increased KAM2 (0.44, 0.04 to 0.85) immediately post-training for single-session to 6-week interventions. Visual, verbal and haptic feedback was used to train gait strategies. Certainty of evidence was very-low to low according to the GRADE approach. CONCLUSION: Very-low to low certainty of evidence suggests that there is a potential that ipsilateral trunk lean, toe-out, and toe-in to be clinically helpful to reduce indicators of medial knee joint load. There is yet little evidence for interventions over several weeks.

An efficient hybrid method for 3D to 2D medical image registration.

PURPOSE: The purpose of this paper is to present a method for registration of 3D computed tomography to 2D single-plane fluoroscopy knee images to provide 3D motion information for knee joints. This 3D kinematic information has unique utility for examining joint kinematics in conditions such as ligament injury, osteoarthritis and after joint replacement. METHODS: We proposed a non-invasive rigid body image registration method which is based on two different multimodal similarity measures. This hybrid registration method helps to achieve a trade-off among different challenges including, time complexity and accuracy. RESULTS: We performed a number of experiments to evaluate the performance of the proposed method. The experimental results show that the proposed method is as accurate as one of the most recent registration methods while it is several times faster than that method. CONCLUSION: The proposed method is a non-invasive, fast and accurate registration method, which can provide 3D information for knee joint kinematic measurements. This information can be very helpful in improving the accuracy of diagnosis and providing targeted treatment.

Influence of component design on in vivo tibiofemoral contact patterns during kneeling after total knee arthroplasty: a systematic review and meta-analysis.

PURPOSE: Modern TKR prostheses are designed to restore healthy kinematics including high flexion. Kneeling is a demanding high-flexion activity. There have been many studies of kneeling kinematics using a plethora of implant designs but no comprehensive comparisons. Visualisation of contact patterns allows for quantification and comparison of knee kinematics. The aim of this systematic review was to determine whether there are any differences in the kinematics of kneeling as a function of TKR design. METHODS: A search of the published literature identified 26 articles which were assessed for methodologic quality using the MINORS instrument. Contact patterns for different implant designs were compared at 90° and maximal flexion using quality-effects meta-analysis models. RESULTS: Twenty-five different implants using six designs were reported. Most of the included studies had small-sample sizes, were non-consecutive, and did not have a direct comparison group. Only posterior-stabilised fixed-bearing and cruciate-retaining fixed-bearing designs had data for more than 200 participants. Meta-analyses revealed that bicruciate-stabilised fixed-bearing designs appeared to achieve more flexion and the cruciate-retaining rotating-platform design achieved the least, but both included single studies only. All designs demonstrated posterior-femoral translation and external rotation in kneeling, but posterior-stabilised designs were more posterior at maximal flexion when compared to cruciate retaining. However, the heterogeneity of the mean estimates was substantial, and therefore, firm conclusions about relative behaviour cannot be drawn. CONCLUSION: The high heterogeneity may be due to a combination of variability in the kneeling activity and variations in implant geometry within each design category. There remains a need for a high-quality prospective comparative studies to directly compare designs using a common method. LEVEL OF EVIDENCE: Systematic review and meta-analysis Level IV.

The influence of total knee arthroplasty design on kneeling kinematics: a prospective randomized clinical trial.

AIMS: Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs. METHODS: In total, 68 patients were randomized to either a posterior stabilized (PS-FB), cruciate-retaining (CR-FB), or rotating platform (CR-RP) design. Of these patients, 64 completed a minimum one year follow-up. Patients completed full-flexion kneeling while being imaged using single-plane fluoroscopy. Kinematics were calculated by registering the 3D implant models onto 2D-dynamic fluoroscopic images and exported for analysis. RESULTS: CR-FB designs had significantly lower maximal flexion (mean 116° (SD 2.1°)) compared to CR-RP (123° (SD 1.6°)) and PS-FB (125° (SD 2.1°)). The PS-FB design displayed a more posteriorly positioned femur throughout flexion. Furthermore, the CR-RP femur was more externally rotated throughout kneeling. Finally, individual patient kinematics showed high degrees of variability within all designs. CONCLUSION: The increased maximal flexion found in the PS-FB and CR-RP designs were likely achieved in different ways. The PS-FB design uses a cam-post to hold the femur more posteriorly preventing posterior impingement. The external rotation within the CR-RP design was surprising and hasn't previously been reported. It is likely due to the polyethylene bearing being decoupled from flexion. The findings of this study provide insights into the function of different knee arthroplasty designs in the context during deep kneeling and provide clinicians with a more kinematically informed choice for implant selection and may allow improved management of patients' functional expectations. Cite this article: Bone Joint J 2021;103-B(1):105-112.

Shape is only a weak predictor of deep knee flexion kinematics in healthy and osteoarthritic knees.

Tibiofemoral shape influences knee kinematics but little is known about the effect of shape on deep knee flexion kinematics. The aim of this study was to examine the association between tibiofemoral joint shape and kinematics during deep kneeling in patients with and without osteoarthritis (OA). Sixty-one healthy participants and 58 patients with end-stage knee OA received a computed tomography (CT) of their knee. Participants completed full flexion kneeling while being imaged using single-plane fluoroscopy. Six-degree-of-freedom kinematics were measured by registering a three-dimensional (3D)-static CT onto 2D-dynamic fluoroscopic images. Statistical shape modeling and bivariate functional principal component analysis (bfPCA) were used to describe variability in knee shape and kinematics, respectively. Random-forest-regression models were created to test the ability of shape to predict kinematics controlling for body mass index, sex, and group. The first seven modes of the shape model up to three modes of the bfPCAs captured more than 90% of the variation. The ability of the random forest models to predict kinematics from shape was low, with no more than 50% of the variation being explained in any model. Furthermore, prediction errors were high, ranging between 24.2% and 29.4% of the data. Variations in the bony morphology of the tibiofemoral joint were weakly associated with the kinematics of deep knee flexion. The models only explained a small amount of variation in the data with high error rates indicating that additional predictors need to be identified. These results contribute to the clinical understanding of knee kinematics and potentially the expectations placed on high-flexion total knee replacement design.

Age has a minimal effect on knee kinematics: A cross-sectional 3D/2D image-registration study of kneeling.

INTRODUCTION: Kneeling is an activity of daily living which becomes difficult with knee pathology and increasing age. This study aimed to capture kneeling kinematics in six-degrees-of-freedom in healthy adults as a function of age. METHODS: 67 healthy knee participants aged from 20 to 90 years were categorised into four 20-year age-groups. 3D knee kinematics were captured using 3D/2D image-registration of CT scan and fluoroscopy during kneeling. Kinematic variables of position, displacement and rate-of-change in six-degrees-of-freedom were compared between age-groups while controlling for University of California Los Angeles activity scale and the Assessment of Quality of Life physical score. RESULTS: Over the entire kneeling cycle there were few differences between the age-groups. Results are reported as pairwise contrasts. At 110° flexion, 80+ knees were more varus than 20-39 and 40-69 (4.9° (95%CI: 0.6°, 9.1°) and 6.4° (2.1°, 10.7°), respectively). At 120° flexion, the 80+ age-group femur was 5.5 (0.0, 11.0) mm more anterior than 20-39. Between 120° to maximum flexion, 80+ knees rotated into valgus more than 20-39, 40-59 and 60-79 (5.5° (1.2°, 9.8°); 5.5° (1.1°, 9.8°); and 4.5° (0.9°, 7.5°), respectively). CONCLUSION: This is the first study to report kneeling knee kinematics of ageing using 3D/2D image registration. We found that ageing does not change knee kinematics under 80 years, and there are minimal changes between 120° and maximum flexion between the younger and 80+ age-groups. Thus, difficulty kneeling should not be considered to be an inevitable consequence of ageing.

Statistical shape modelling reveals large and distinct subchondral bony differences in osteoarthritic knees.

Knee osteoarthritis (OA) results in changes such as joint-space narrowing and osteophyte formation. Radiographic classification systems group patients by the presence or absence of these gross anatomical features but are poorly correlated to function. Statistical-shape modelling (SSM) can detect subtle differences in 3D-bone geometry, providing an opportunity for accurate predictive models. The aim of this study was to describe and quantify the main modes of shape variation which distinguish end-stage OA from asymptomatic knees. Seventy-six patients with OA and 77 control participants received a CT of their knee. 3D models of the joint were created by manual segmentation. A template mesh was fitted to all meshes and rigidly aligned resulting in a set of correspondent meshes. Principal Component Analysis (PCA) was performed to create the SSM. Logistic regression was performed on the PCA weights to distinguish morphological features of the two groups. The first 7 modes of the SSM captured >90% shape variation with 6 modes best distinguishing between OA and asymptomatic knees. OA knees displayed sub-chondral bone expansion particularly in the condyles and posterior medial tibial plateau of up to 10 mm. The model classified the two groups with 95% accuracy, 96% sensitivity, 94% specificity, and 97% AUC. There were distinct features which differentiated OA from asymptomatic knees. Further research will elucidate how magnitude and location of shape changes in the knee influence clinical and functional outcomes.

Analysis of Kneeling by Medical Imaging Shows the Femur Moves Back to the Posterior Rim of the Tibial Plateau, Prompting Review of the Concave-Convex Rule.

BACKGROUND: Physical therapists assess joint movement by observation and palpation. New imaging technologies that enable vision of bones and joints during functional activities can be used to analyze joint kinematics and review traditional assumptions. PURPOSE: The purpose was to measure relations between flexion, rotation, and translation at the knee and to validate these visually. DESIGN: This was a prospective, observational study. METHODS: Twenty-five healthy participants aged >45 years (13 males) knelt from upright kneeling to full flexion with the foot free. Fluoroscopy recorded movement at 30 frames per second of x-ray. A computed tomography scan provided 3-dimensional data, which were registered to the fluoroscopy frames to provide a moving model. Motion in 6 degrees of freedom was analyzed for coupling of movements. RESULTS: Mean (standard deviation) flexion reached by participants was 142 (6)° in kneeling. Posterior femoral translation was coupled to flexion (r = 0.96). From 90° to 150° flexion, the femur translated posteriorly by 36 (3) mm to finish 23 (3) mm posterior to the center of the tibia at 150° flexion. From 90° to 150° flexion, the femur externally rotated from 8 (6)° to 16 (5)°. Flexion was coupled to rotation (r = 0.47). Abduction was <3° and lateral translation was <3 mm. Visually, the femur appeared to translate posteriorly until the femoral condyles rested on the posterior rim of the tibial plateau with concurrent external rotation so that the popliteal fossa aligned with the posterior margin of the medial tibial plateau. LIMITATIONS: A limitation of the study is that knee flexion can include squat and lunge as well as kneeling. CONCLUSION: Deep flexion requires femoral posterior translation and external rotation. These findings invite review of the concave-convex rule as it might apply to manual therapy of the knee.

Kinematics of knees with osteoarthritis show reduced lateral femoral roll-back and maintain an adducted position. A systematic review of research using medical imaging.

BACKGROUND: While several studies describe kinematics of healthy and osteoarthritic knees using the accurate imaging and computer modelling now possible, no systematic review exists to synthesise these data. METHOD: A systematic review extracted quantitative observational, quasi-experimental and experimental studies from PubMed, Scopus, Medline and Web of Science that examined motion of the bony or articular surfaces of the tibiofemoral joint during any functional activity. Studies using surface markers, animals, and in vitro studies were excluded. RESULTS: 352 studies were screened to include 23 studies. Dynamic kinematics were recorded for gait, step-up, kneeling, squat and lunge and quasi-static squat, knee flexion in side-lying or supine leg-press. Kinematics were described using a diverse range of measures including six degrees of freedom kinematics, contact patterns or the projection of the femoral condylar axis above the tibia. Meta-analysis of data was not possible since no three papers recorded the same activity with the same measures. Visual evaluation of data revealed that knees with osteoarthritis maintained a more adducted position and showed less posterior translation of the lateral femoral condylar axis than healthy knees. Variability in activities and in recording measures produced greater variation in kinematics, than did knee osteoarthritis. CONCLUSION: Differences in kinematics between osteoarthritic and healthy knees were observed, however, these differences were more subtle than expected. The synthesis and progress of this research could be facilitated by a consensus on reference systems for axes and kinematic reporting.

Squatting, lunging and kneeling provided similar kinematic profiles in healthy knees-A systematic review and meta-analysis of the literature on deep knee flexion kinematics.

BACKGROUND: Understanding healthy deep flexion kinematics will inform the design of conservative clinical rehabilitation strategies for knee osteoarthritis and contribute to improved knee prosthesis design. This study is a systematic review and meta-analysis of the kinematic outcomes measured at the healthy tibiofemoral joint during loaded deep knee flexion. METHODS: A computerised literature search and bibliography review without date restriction identified twelve studies with 164 participants aged 25-61 years in-vivo, and 69-93 years in-vitro. Flexion higher than 120° was achieved by squatting, lunging or kneeling. Measurement technologies in-vivo included radiographs, open MRI and 2D-3D MRI or CT image registration on fluoroscopy. Microscribe was used in-vitro. RESULTS: Outcomes were either six degrees-of-freedom based on femur movement or contact patterns on the tibial plateau. The meta-analysis demonstrated that in-vivo, between 120° and 135° of flexion, the tibia internally rotated (mean difference (MD) = 4.6°, 95% CI 3.55° to 5.64°). Both the medial-femoral-condyle and lateral-femoral-condyle translated posteriorly, (MD = 10.4 mm, 95% CI 6.9 to 13.9 mm) and (MD = 5.55 mm, 95% CI 4.64 to 6.46 mm) respectively. There was some evidence of femoral medial translation (3.8 mm) and adduction (1.9° to 3.3°), together with medial compression (1.7 mm) and lateral distraction (1.9) mm. CONCLUSIONS: Across the in-vivo studies, consistent kinematic patterns emerged; despite the various measurement technologies and reference methods. In contrast, in-vivo and in-vitro results were contradictory. TRIAL REGISTRATION: This systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 25 February 2017 (registration number: 42017057614).

Total Knee Arthroplasty Using Bicruciate-Stabilized or Posterior-Stabilized Knee Implants Provided Comparable Outcomes at 2 Years: A Prospective, Multicenter, Randomized, Controlled, Clinical Trial of Patient Outcomes.

BACKGROUND: The bicruciate-stabilized (BCS) knee arthroplasty was developed to replicate normal knee kinematics. We examined the hypothesis that patients with osteoarthritis requiring total knee arthroplasty (TKA) will have better functional outcome and satisfaction with the BCS implant compared with an established posterior cruciate-stabilized implant. METHODS: This multicenter, randomized, controlled trial compared the clinical outcomes of a BCS implant against an established posterior cruciate-stabilized implant with 2-year follow-up. Of the patients awaiting primary knee arthroplasty for osteoarthritis, 228 were randomized to receive either a posterior-stabilized or BCS implant. Primary outcomes were knee flexion and Oxford Knee Score. Secondary outcomes were rate of complications and adverse events (AEs). Tertiary outcomes included Knee Society Score, University of California, Los Angeles, activity score, Patella scores, EQ-5D, 6-minute walk time, and patient satisfaction. RESULTS: Complete data were recorded for 98 posterior-stabilized implants and 97 BCS implants. Twelve patients had bilateral knee implants. There was no difference between the groups for any of the measures at either 1 or 2 years. At 2 years, knee flexion was 119 ± 0.16 and 120 ± 1.21 degrees for the posterior-stabilized and BCS implants, respectively, (mean, standard error, P = .538) and Oxford Knee Scores were 40.4 ± 0.69 and 40.0 ± 0.67 (P = .828), respectively. There were similar device-related AEs and revisions in each group (AEs 18 vs 22; P = .732; revisions 3 vs 4; P = .618). CONCLUSION: There was no evidence of clinical superiority of one implant over the other at 2 years.

An Ecological Study of Anterior Cruciate Ligament Reconstruction, Part 2: Functional Performance Tests Correlate With Return-to-Sport Outcomes.

BACKGROUND: Additional high-quality prospective studies are needed to better define the objective criteria used in relation to return-to-sport decisions after anterior cruciate ligament (ACL) reconstruction in active populations. PURPOSE: To investigate prospectively the relationship between functional performance test results at 24 weeks postoperative and return-to-sport activity (Tegner activity score) at 12 and 24 months, respectively, after synthetic (ligament advanced reinforcement system [LARS]) and autograft (doubled semitendinosus/gracilis [2ST/2GR]) ACL reconstructions. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 64 patients who underwent ACL reconstruction (32 LARS, 32 2ST/2GR autograft; mean age, 27.9 years; body mass index [BMI], 24.9 kg/m2) were assessed preoperatively and at staged intervals postoperatively up to 24 weeks for isokinetic testing of quadriceps and hamstring average power per repetition at 60 deg/s and 180 deg/s, a battery of hop tests, peak vertical ground-reaction force (vGRF), and time to peak vGRF (in seconds) during a step- and jump-down task onto a force platform and peak speed (m/s) using a global positioning system (GPS unit) during a running task. A cohort of 32 healthy matched participants (mean age, 26.31 years; BMI, 25.7 kg/m2) were also tested to act as reference. Pearson correlation was calculated to assess correlation of each performance measure at 24 weeks postoperative with activity outcomes (Tegner score) at 12 and 24 months. RESULTS: The strongest correlation between physical performance tests and return-to-sport outcomes was observed with peak speed during running. Large correlations were also observed for hamstring isokinetic power and hop test for distance. Moderate correlations were observed for timed hop, peak vGRF during a jump-down task, and quadriceps isokinetic power. No statistical correlations were observed for time to peak vGRF during a step-down and jump-down task as well as peak vGRF during a step-down task. When the performance tests were pooled together, mean postoperative improvements of 24% were observed from preoperative to 24 weeks within the surgical cohort. For each performance test, preoperative level of function strongly correlated with performance levels on the same test at 24 weeks. DISCUSSION: The results of this study indicate that clinicians might seek to prioritize these tests and the rehabilitation themes they imply when seeking to maximize postoperative ACL activity outcomes. The observed strength between pre- and postoperative performance tests and return-to-sport outcomes within this study highlights the potential value of preoperative conditioning before undergoing ACL reconstruction. Future research should examine absolute predictive criterion thresholds for functional performance-based tests and reinjury risk reduction after ACL reconstruction.

Vertical stiffness is not related to anterior cruciate ligament elongation in professional rugby union players.

BACKGROUND: Novel research surrounding anterior cruciate ligament (ACL) injury is necessary because ACL injury rates have remained unchanged for several decades. An area of ACL risk mitigation which has not been well researched relates to vertical stiffness. The relationship between increased vertical stiffness and increased ground reaction force suggests that vertical stiffness may be related to ACL injury risk. However, given that increased dynamic knee joint stability has been shown to be associated with vertical stiffness, it is possible that modification of vertical stiffness could help to protect against injury. We aimed to determine whether vertical stiffness is related to measures known to load, or which represent loading of, the ACL. METHODS: This was a cross-sectional observational study of 11 professional Australian rugby players. Knee kinematics and ACL elongation were measured from a 4-dimensional model of a hopping task which simulated the change of direction manoeuvre typically observed when non-contact ACL injury occurs. The model was generated from a CT scan of the participant's knee registered frame by frame to fluoroscopy images of the hopping task. Vertical stiffness was calculated from force plate data. RESULTS: There was no association found between vertical stiffness and anterior tibial translation (ATT) or ACL elongation (r=-0.05; p=0.89, and r=-0.07; p=0.83, respectively). ATT was related to ACL elongation (r=0.93; p=0.0001). CONCLUSIONS: Vertical stiffness was not associated with ACL loading in this cohort of elite rugby players but a novel method for measuring ACL elongation in vivo was found to have good construct validity.

An Ecological Study of Anterior Cruciate Ligament Reconstruction, Part 1: Clinical Tests Do Not Correlate With Return-to-Sport Outcomes.

BACKGROUND: Additional high-quality prospective studies are needed to better define the objective criteria used in relation to return-to-sport decisions after synthetic (ligament advanced reinforcement system [LARS]) and autograft (hamstring tendon [2ST/2GR]) anterior cruciate ligament (ACL) reconstruction in active populations. PURPOSE: To prospectively investigate and describe the recovery of objective clinical outcomes after autograft (2ST/2GR) and synthetic (LARS) ACL reconstructions, as well as to investigate the relationship between these clinimetric test outcomes and return-to-sport activity (Tegner activity scale [TAS] score) at 12 and 24 months postoperatively. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 64 patients who underwent ACL reconstruction (32 LARS, 32 2ST/2GR autograft) and 32 healthy reference participants were assessed for joint laxity (KT-1000 arthrometer), clinical outcome (2000 International Knee Documentation Committee [IKDC] knee examination), and activity (TAS score) preoperatively and at 12, 16, 20, and 24 weeks and 12 and 24 months postoperatively. RESULTS: There was no significant correlation observed between clinical results using the 2000 IKDC knee examination and TAS score at 24 months (rs = 0.188, P = .137), nor were results for side-to-side difference (rs = 0.030, P = .814) or absolute KT-1000 arthrometer laxity of the surgical leg at 24 months postoperatively (rs = 0.076, P = .553) correlated with return-to-sport activity. Nonetheless, return-to-sport rates within the surgical cohort were 81% at 12 months and 83% at 24 months, respectively. No statistically significant differences were observed between physiological laxity of the uninjured knee within the surgical group compared with healthy knees within the reference group (P = .522). CONCLUSION: The results indicate that although relatively high levels of return-to-sport outcomes were achieved at 24 months compared with those previously reported in the literature, correlations between objective clinical tests and return-to-sport outcomes may not occur. Clinical outcome measures may provide suitable baseline information; however, the results of this study suggest that clinicians may need to place greater emphasis on other outcome measures when seeking to objectively promote safe return to sport.

The effect of limb dominance on lower limb functional performance--a systematic review.

Lower limb dominance (or lateral preference) could potentially effect functional performance. Clinicians are often asked to make judgements as to when a patient has sufficiently "recovered" from an injury, typically using strength and dynamic performance outcome measures. The primary purpose of this study was to systematically review the literature in relation to limb dominance within active adult populations and discuss some limitations to current methods and relate this to current clinical practice. A search of MEDLINE and CINAHL and EMBASE databases and reference lists of those articles identified was performed. Eleven articles were selected for meta-analysis. There was no statistical effect of limb dominance for any of the functional tests: isokinetic quadriceps and hamstring tests, hamstring:quadriceps ratios, single-leg hop for distance, single-leg vertical jump and vertical ground reaction force following a single-leg vertical jump. Pooled symmetry values varied from 94.6% to 99.6% across the tests, above the clinically accepted benchmark of 90% used in clinical practice. Although the results of this study must be used with discretion, asymmetries in the tasks described in this analysis should be viewed as undesirable and remedied accordingly. Further research is needed to quantify asymmetries, particularly in relation to sport-specific contexts.