Test-retest reliability and longitudinal validity of drop vertical jump biomechanics during rehabilitation after ACL reconstruction.

Hip and knee biomechanics measured during a drop vertical jump (DVJ) can be used to assess patients undergoing rehabilitation after anterior cruciate ligament (ACL) reconstruction. To confidently interpret such data for use as outcome measures, additional information about reliability and validity is required. Therefore, the objective of this study was to estimate the test-retest reliability and longitudinal validity of selected lower limb biomechanics assessed during a DVJ in patients undergoing rehabilitation after ACL reconstruction. Biomechanical analysis of the DVJ in primary unilateral ACL reconstruction patients (22.3 ± 5.5y) were tested twice within 1 week at 6 months post-surgery (n = 46), and again at 12 months post-surgery (n = 36). Peak and initial contact knee angles and moments, hip impulse, vertical ground reaction forces (VGRF), isokinetic knee extension and flexion strength, and global ratings of change (GRC) were assessed. Reliability was evaluated based on the 6-month post-surgery data using intraclass correlation coefficients (ICC2,1), standard errors of measurement and minimum detectable change. Longitudinal validity was evaluated by assessing change from 6 to 12 months, using standardized response means (SRM), and by assessing the correlation (Pearson's r) of change in landing biomechanics with change in strength, and GRC. ICCs ranged from 0.58 to 0.90 for peak knee abduction and flexion moments, 0.44-0.85 for knee flexion and abduction angles, 0.82-0.93 for VGRFs, and 0.42-0.65 for hip impulse. SRMs and correlations of change ranged from 0.00 to 0.50. Reliability and longitudinal validity of DVJ measures varied, ranging from poor-to-excellent; the present results assist in their interpretation when assessed during rehabilitation after ACL reconstruction.

Responders to Medial Opening Wedge High Tibial Osteotomy for Knee Osteoarthritis.

OBJECTIVE: Medial opening wedge high tibial osteotomy (HTO) aims to improve symptoms for patients with knee osteoarthritis (OA) and varus alignment, yet the likelihood of achieving a minimum clinical threshold of response and the factors predictive of response are unclear. We evaluated the proportion of patients meeting responder criteria based on the Outcome Measures in Rheumatology-Osteoarthritis Research Society International consensus 2 years after medial opening wedge HTO and investigated predictors of response. METHODS: Patients in a prospective cohort with symptomatic knee OA and varus alignment completed the Knee Injury and Osteoarthritis Outcome Score questionnaire < 3 months before and 2 years after HTO. For our primary analysis, we calculated the proportion of responders with ≥ 20% relative improvement and an absolute change of ≥ 10 points in pain and function from baseline. We performed logistic regression to evaluate the association of predictors with response and completed sex-disaggregated analyses. RESULTS: At a mean of 20.3 (SD 6.2) months post-HTO, 406 patients (78%) met the responder criteria. Older age, higher BMI, and larger postoperative mechanical axis angles (ie, slight valgus) were associated with increased odds of achieving responder criteria, although odds ratios were small. When stratified by sex, 316/405 male patients (78%) and 90/118 female patients (76%) met the responder criteria. CONCLUSION: Based on responder criteria for knee OA, 78% of patients undergoing medial opening wedge HTO were responders at 2 years postsurgery. Although patients who are younger, male, and nonobese are viewed as appropriate candidates for HTO, patients who are female, are older, and have a high BMI also achieve sizable improvements in pain and function.

Changes and Associations Between Gait Biomechanics and Knee Inflammation After Aspiration and Glucocorticoid Injection for Knee Osteoarthritis.

OBJECTIVE: Although knee inflammation is thought to adversely affect joint function in patients with knee osteoarthritis (OA), the effects of reducing knee inflammation on gait biomechanics and strength are unknown. Our objectives were to compare ultrasound (US) measures of knee inflammation, gait biomechanics, knee extension and flexion strength, and pain before and after knee aspiration and glucocorticoid injection, and to explore associations among changes. METHODS: Forty-nine patients (69 knees) with symptomatic knee OA and synovitis were tested before and 3-4 weeks after US-guided knee aspiration and glucocorticoid injection. At each visit, participants completed US assessments for inflammatory features of knee OA, 3D gait analysis, isokinetic knee extension and flexion strength tests, and Knee Osteoarthritis Outcome Score (KOOS) pain subscales. Linear and polynomial mixed-effects regression models were used to investigate changes and their associations. RESULTS: Changes were observed for the synovitis score (unstandardized ß [post-injection minus pre-injection] -0.55/9 [95% confidence interval (95% CI) -0.97, -0.12]), effusion depth (-1.05 mm [95% CI -1.07, -0.39]), KOOS pain (unstandardized ß 5.91/100 [95% CI 1.86, 9.97]), peak external knee flexion and extension moments (KFM; 3.33 Nm [95% CI 0.45, 6.22]), KEM (-2.99 Nm [95% CI -5.93, -0.05]), and knee extension strength (4.70 Nm [95% CI 0.39, 9.00]) and flexion strength (3.91 Nm [95% CI 1.50, 6.81]). The external KFM increased during 13-38% and 76-89% of stance post-injection. When controlled for time, greater synovitis was associated with lower knee extension strength, while lower pain was associated with increased knee extension and flexion strength. CONCLUSION: In patients with knee OA and synovitis, reduced inflammation and pain after aspiration and glucocorticoid injection are associated with changes in knee gait biomechanics and strength.

High tibial osteotomy to neutral alignment improves medial knee articular cartilage composition.

PURPOSE: The purpose of this study was to: (1) test the hypothesis that HTO improves articular cartilage composition in the medial compartment without adversely affecting the lateral compartment and patella, and; (2) explore associations between knee alignment and cartilage composition after surgery. METHODS: 3T MRI and standing radiographs were obtained from 34 patients before and 1-year after HTO. Articular cartilage was segmented from T2 maps. Mechanical axis angle (MAA), posterior tibial slope, and patellar height were measured from radiographs. Changes in T2 and radiographic measures were assessed using paired t tests, and associations were assessed using Pearson correlation coefficients. RESULTS: The mean (SD) MAA before and after HTO was - 6.5° (2.4) and 0.6° (3.0), respectively. There was statistically significant shortening [mean (95%CI)] of T2 in the medial femur [- 2.8 ms (- 4.2; - 1.3), p < 0.001] and medial tibia [- 2.2 ms (- 3.3; - 1.0), p < 0.001], without changes in the lateral femur [- 0.5 ms (- 1.6; 0.6), p = 0.3], lateral tibia [0.2 ms (- 0.8; 1.1), p = NS], or patella [0.5 ms (- 1.0; 2.1), p = NS). Associations between radiographic measures and T2 were low. 23% of the increase in lateral femur T2 was explained by postoperative posterior tibial slope (r = 0.48). CONCLUSION: Performing medial opening wedge HTO without overcorrection improves articular cartilage composition in the medial compartment of the knee without compromising the lateral compartment or the patella. Although further research is required, these results suggest HTO is a disease structure-modifying treatment for knee OA.

Total knee replacement after high tibial osteotomy: time-to-event analysis and predictors.

BACKGROUND: An important aim of high tibial osteotomy (HTO) is to prevent or delay the need for total knee replacement (TKR). We sought to estimate the frequency and timing of conversion from HTO to TKR and the factors associated with it. METHODS: We prospectively evaluated patients with osteoarthritis (OA) of the knee who underwent medial opening wedge HTO from 2002 to 2014 and analyzed the cumulative incidence of TKR in July 2019. The presence or absence of TKR on the HTO limb was identified from the orthopedic surgery reports and knee radiographs contained in the electronic medical records for each patient at London Health Sciences Centre. We used cumulative incidence curves to evaluate the primary outcome of time to TKR. We used multivariable Cox proportional hazards analysis to assess potential preoperative predictors including radiographic disease severity, malalignment, correction size, pain, sex, age, body mass index (BMI) and year of surgery. RESULTS: Among 556 patients who underwent 643 HTO procedures, the cumulative incidence of TKR was 5% (95% confidence interval [CI] 3%-7%) at 5 years and 21% (95% CI 17%-26%) at 10 years. With the Cox proportional hazards multivariable model, the following preoperative factors were significantly associated with an increased rate of conversion: radiographic OA severity (adjusted hazard ratio [HR] 1.96, 95% CI 1.12-3.45), pain (adjusted HR 0.85, 95% CI 0.75-0.96)], female sex (adjusted HR 1.67, 95% CI 1.08-2.58), age (adjusted HR 1.50 per 10 yr, 95% CI 1.17-1.93) and BMI (adjusted HR 1.31 per 5 kng/m2, 95% CI 1.12-1.53). INTERPRETATION: We found that 79% of knees did not undergo TKR within 10 years after undergoing medial opening wedge HTO. The strongest predictor of conversion to TKR is greater radiographic disease at the time of HTO.

Knee-specific gait biomechanics are reliable when collected in multiple laboratories by independent raters.

Multi-centre gait biomechanics studies provide the opportunity to increase sample size and the confidence in results, yet differences between centres may introduce additional error. While previous investigations have compared gait biomechanics from different laboratories assessed by different raters, estimates of relative reliability, measurement error, and thresholds for real change are still unknown. These metrics are imperative to interpret multi-centre study results. Therefore, we examined the reliability of gait biomechanics assessed in two different laboratories, by two different raters, and using the same study sample. Twelve healthy participants underwent gait assessments by two raters in two laboratories at different institutions. Identical protocols were used to collect five walking trials per participant. Discrete data were examined for knee joint angles and moments, gait speed, and stride length. Reliability was assessed using the intraclass correlation coefficient (ICC), standardized error of the measurement (SEM), minimum detectable difference (MDD), and Bland and Altman plots. All spatiotemporal, joint angle, and joint moment measures had ICCs = 0.83-0.94, except for the knee adduction moment peak in late stance (ICC = 0.69 and 0.72). The knee adduction moment SEMs indicate that measurement errors due to the laboratory effect are between 0.19% and 0.31% body weight times height (0.03-0.05 Nm/kg). Meanwhile, measurement error for the knee flexion-extension angle is <2°. Our results are similar to previous test-retest reliability results from a single laboratory, and multiple laboratories, while adding previously unreported reliability metrics necessary for interpreting multi-centre study results.

Associations Between Cadence and Knee Loading in Patients With Knee Osteoarthritis.

OBJECTIVE: To test the hypothesis that higher walking cadence is associated with lower knee loading, while controlling for walking speed, in patients with medial compartment tibiofemoral osteoarthritis (OA). METHODS: A total of 691 patients underwent quantitative gait analysis, including 3-dimensional knee moments and temporospatial parameters. Using multivariate linear regression, we tested the association of walking cadence with the knee adduction moment angular impulse (a surrogate measure of medial knee compartment load throughout the stance), while controlling for walking speed. We repeated the analysis while also adjusting for sex, age, body mass index, radiographic OA, knee pain, lateral trunk lean, foot progression angle, and mechanical axis angle, and while replacing the knee adduction moment angular impulse with other surrogate measures of knee loading. RESULTS: While controlling for walking speed, we found that a lower cadence was associated with higher knee adduction moment angular impulse (standardized ß = -0.396, P < 0.001), suggesting a 0.02% body weight × height × seconds (%BW × Ht × s) decrease in impulse for each step per minute increase in cadence (unstandardized ß -0.020 %BW × Ht × s [95% confidence interval -0.027, -0.015]), and remained consistent after adjusting for covariates. A lower cadence was also associated with higher first (standardized ß = -0.138, P = 0.010) and second peak knee adduction moment (standardized ß = -0.132, P = 0.018), higher peak knee flexion moment (standardized ß = -0.128, P = 0.049), and vertical ground reaction force (standardized ß = -0.116, P = 0.035) in the adjusted analyses. CONCLUSION: When controlling for walking speed, we found that a lower cadence is associated with higher knee loading per step in patients with medial tibiofemoral OA. Future research should investigate the potential beneficial biomechanical and clinical effects of increasing walking cadence in patients with knee OA.

Reliability and validity of knee angles and moments in patients with osteoarthritis using a treadmill-based gait analysis system.

BACKGROUND: Although commonly used to study knee osteoarthritis (OA), relatively little is known about the reliability and validity of three-dimensional (3D) gait biomechanics derived from treadmill-based systems. RESEARCH QUESTION: Using a treadmill-based gait analysis system, our objectives were to: 1) estimate the test-retest reliability of frontal and sagittal plane knee angles and moments in knee OA patients; 2) examine concurrent validity by estimating the associations between treadmill-based and overground (gold standard) measures; and 3) examine known-groups validity by comparing measures between knee OA patients and matched healthy controls. METHODS: 34 patients and 16 controls completed 3D gait analyses using treadmill-based and overground systems. Treadmill walking speed was matched to self-selected overground speed. Marker set, knee angle and moment calculations were consistent for both systems. Patients completed a second test session using the treadmill-based system <24 h later but within 1 week of the first test session. Variables calculated from knee angle and moment gait waveforms during stance were evaluated using Bland and Altman plots, Intraclass Correlation Coefficients (ICC), Pearson correlations (r) and t-tests. RESULTS: Visual inspection of the Bland and Altman plots did not reveal any systematic differences between test and retest sessions; however, limits of agreement (LoA) were larger for the sagittal plane than the frontal plane. Mean differences between sessions for knee angles were <0.25 degrees and <0.18 %BW*ht for knee moments. ICCs ranged from 0.57-to-0.93 for test-retest reliability. Pearson correlations between treadmill and overground systems ranged from 0.56-to-0.97. Although highly associated, there were substantial differences in the moments, emphasizing they cannot be used interchangeably. Patients had greater first peak knee adduction moments (KAM) than controls [mean difference (95 %CI): 0.55 (-1.07, -0.04), p = 0.03]. SIGNIFICANCE: Results suggest frontal and sagittal plane knee angles and moments in patients with knee OA evaluated using a treadmill-based system are reliable and valid.

Strong independent associations between gait biomechanics and pain in patients with knee osteoarthritis.

We investigated the simple and multivariate associations between knee pain and gait biomechanics. 279 patients with medial knee osteoarthritis (OA) and discordant changes in pain between limbs after walking completed bilateral three-dimensional gait analysis. For each limb, patients rated their pain before and after a 6-min walk and the change in pain was recorded as an increase (≥1 points) or not (≤0 points). Among paired limbs, the simple and multivariate associations between an increase in pain and the external moments in each orthogonal plane were evaluated using conditional logistic regression. The analyses were then repeated for knee angles. Univariate analyses demonstrated associations in each plane that varied in both magnitude and direction, with larger associations for the knee moments [Odds Ratio (95% confidence interval) = first peak adduction moment: 2.80 (2.02, 3.88), second peak adduction moment: 2.36 (1.73, 3.24), adduction impulse: 6.65 (3.50, 12.62), flexion moment: 0.46 (0.36, 0.60), extension moment: 0.56 (0.44, 0.71), internal rotation moment: 7.54 (3.32, 17.13), external rotation moment: 0.001 (0.00, 0.04)]. Multivariate analyses with backward elimination resulted in a model including only the adduction impulse [5.35 (2.51, 11.42)], flexion moment [0.32 (0.22, 0.46)] and extension moment [0.28 (0.19, 0.42)]. The varus, flexion and extension angles were included in the final multivariate model for the knee angles. When between-person confounding is lessened by comparing limbs within patients, there are strong independent associations between knee pain and multiple external knee moments that vary in magnitude and direction. While controlling for other knee moments, a greater adduction impulse and lower flexion and extension moments were independently associated with greater odds of an increase in pain.

Degenerative Meniscal Tears and High Tibial Osteotomy: Do Current Treatment Algorithms Need to Be Realigned?

Degenerative medial meniscal tears (DMMTs) are a common feature of early knee osteoarthritis (OA). Varus alignment is a strong risk factor for medial compartment knee OA and its progression. We propose that high tibial osteotomy (HTO) should be considered much earlier in the treatment algorithm for patients presenting with recurring medial knee pain, varus alignment, and DMMT, absent of radiographic OA. We provide rationale for investigating HTO as a disease-modifying intervention for secondary prevention in knee OA, and present case examples as low-level proof of principle. Finally, caveats and challenges are discussed along with proposed future research.

Association Between Knee Load and Pain: Within-Patient, Between-Knees, Case-Control Study in Patients With Knee Osteoarthritis.

OBJECTIVE: The association between knee loading and pain in patients with knee osteoarthritis is reported to be low and of questionable importance, but may be confounded by several factors that differ between patients. We aimed to elucidate the association between dynamic knee load and pain by minimizing confounding using a study design that was within the same patient, with knees discordant for pain. METHODS: A total of 265 patients with knees discordant for pain (530 knees) rated the pain in each knee before and after walking for 6 minutes, and then underwent 3-dimensional gait analysis. RESULTS: The peak knee adduction moment and knee adduction impulse (proxies for medial knee loading) were associated with increased pain (odds ratio [OR] 2.43 [95% confidence interval (95% CI) 1.77-3.33] and OR 6.62 [95% CI 3.46-12.7], respectively) and remained significant after controlling for radiographic disease severity. When split into quartiles, ORs indicated knees in the highest loading quartile had greater odds of experiencing increased pain with walking (OR 4.7 95% CI 2.3-9.5] for peak adduction moment; OR 9.0 [95% CI 4.0-20.1] for adduction impulse) compared to knees in the lowest loading quartile. CONCLUSION: When between-patient confounding is minimized, there is a strong association between medial knee load and increased knee pain during walking.

Whole-body vibration of mice induces progressive degeneration of intervertebral discs associated with increased expression of Il-1ß and multiple matrix degrading enzymes.

OBJECTIVE: Whole-body vibration (WBV) is a popular fitness trend based on claims of increased muscle mass, weight loss and reduced joint pain. Following its original implementation as a treatment to increase bone mass in patients with osteoporosis, WBV has been incorporated into clinical practice for musculoskeletal disorders, including back pain. However, our recent studies revealed damaging effects of WBV on joint health in a murine model. In this report, we examined potential mechanisms underlying disc degeneration following exposure of mice to WBV. METHODS: Ten-week-old male mice were exposed to WBV (45 Hz, 0.3 g peak acceleration, 30 min/day, 5 days/week) for 4 weeks, 8 weeks, or 4 weeks WBV followed by 4 weeks recovery. Micro-computed tomography (micro-CT), histological, and gene expression analyses were used to assess the effects of WBV on spinal tissues. RESULTS: Exposure of mice to 4 or 8 weeks of WBV did not alter total body composition or induce significant changes in vertebral bone density. On the other hand, WBV-induced intervertebral disc (IVD) degeneration, associated with decreased disc height and degenerative changes in the annulus fibrosus (AF) that did not recover within 4 weeks after cessation of WBV. Gene expression analysis showed that WBV for 8 weeks induced expression of Mmp3, Mmp13, and Adamts5 in IVD tissues, changes preceded by increased expression of Il-1ß. CONCLUSIONS: Progressive IVD degeneration induced by WBV was associated with increased expression of Il-1ß within the IVD that preceded Mmp and Adamts gene induction. Moreover, WBV-induced IVD degeneration is not reversed following cessation of vibration.

Medial opening wedge high tibial osteotomy alters knee moments in multiple planes during walking and stair ascent.

Medial opening wedge high tibial osteotomy is a surgical procedure intended to redistribute loads on the knee in patients with medial compartment knee osteoarthritis (OA). The surgery may affect moments in multiple planes during ambulation, with potential beneficial or detrimental effects on joint loads. The objective of this study was to investigate three-dimensional external knee moments before and after medial opening wedge high tibial osteotomy during level walking and during stair ascent. Fourteen patients with varus alignment and osteoarthritis primarily affecting the medial compartment of the tibiofemoral joint were assessed. Three-dimensional motion analyses during level walking and stair ascent was evaluated using inverse dynamics before, 6 and 12 months after surgery. Mean changes at 12 months suggested decreases in the peak knee adduction, flexion and internal rotation moments, with standardized response means ranging from 0.15 to 2.54. These decreases were observed despite increases in speed. Changes in alignment were associated with changes in the adduction and internal rotation moments, but not the flexion moment. Both pre- and postoperatively, the peak knee adduction moment was significantly lower (p=0.001) during stair ascent than during level walking, while the flexion and internal rotation moments were significantly higher (p<0.01). There were no changes in the knee moments on the non-surgical limb. Medial opening wedge high tibial osteotomy is associated with sustained (12 months) changes in knee moments in all three planes of motion during ambulation, suggesting substantial alterations of the loads on the knee during ambulation.

Radiostereometric analysis of early anatomical changes following medial opening wedge high tibial osteotomy.

BACKGROUND: The objective of this study was to use radiostereometric analysis (RSA) to evaluate the anatomical changes that occur in the tibia immediately after surgical correction with medial opening wedge high tibial osteotomy (HTO), and the changes that occur over the course of the first twelveweeks of osseous union. METHODS: Patients included nine males and one female, with a mean age of 49.0 ± 5.5 years and mean BMI of 28.4 ± 3.8 kg/m(2). The patients underwent HTO using a non-locking plate. RSA marker beads were inserted in the tibia, femur, and patella. RSA exams were first obtained intra-operatively prior to the osteotomy, and subsequently at one, two, four, six, and twelveweeks postoperatively. RESULTS: Patients were corrected from a mean alignment preoperatively of 8.6 ± 2.5° to 0.3 ± 1.9° postoperatively, with a mean osteotomy of 12.5 ± 3.6mm. Immediate tibia changes surrounding the osteotomy site included 9.2 ± 2.4° of valgus rotation and 6.2 ± 2.0mm of distal translation. Secondary motions included 2.5 ± 2.4° of internal rotation of the distal tibia, 1.8 ± 1.4mm of posterior movement of the femur, and 8.5 ± 3.4mm of patella baja. Micromotion between the proximal and distal tibial segments decreased over time. CONCLUSION: The results suggest that subtle changes to the anatomy occur, beyond what is intended with the procedure, but partial corrections of these phenomena occurred over the twelveweeks. Micromotion surrounding the osteotomy site decreased with osseous union.

Valgus bracing for knee osteoarthritis: a meta-analysis of randomized trials.

OBJECTIVE: To evaluate the effects of valgus knee bracing on pain and function, and compliance and complications, in patients with medial knee osteoarthritis (OA). METHODS: A meta-analysis of randomized controlled trials that compared changes in patient-reported pain and/or function in patients with medial knee OA was performed. Seven databases were searched from their inception to January 2014. Two reviewers independently determined study eligibility, rated risk of bias, and extracted data. Pooled estimates and 95% confidence intervals (95% CIs) for standardized mean differences (SMDs) for the improvement in pain (and function) were calculated. Event rates (proportions) were calculated for studies that reported complications. RESULTS: Six studies were included in the meta-analysis. Overall, there was a statistically significant difference favoring the valgus brace group for improvement in pain (SMD 0.33 [95% CI 0.13, 0.52], P = 0.001) and function (SMD 0.22 [95% CI 0.02, 0.41], P = 0.03). When compared to a control group that did not use an orthosis, the effect size was moderate for pain (SMD 0.56 [95% CI 0.03, 1.09], P = 0.04) and function (SMD 0.48 [95% CI 0.02, 0.95], P = 0.04). When compared to a control group that used a control orthosis, only a small, statistically significant effect for pain remained (SMD 0.33 [95% CI 0.08, 0.58], P = 0.01). Instructions for brace use varied considerably and compliance ranged from 45% to 100%. Up to 25% of patients reported minor complications with brace use. CONCLUSION: Meta-analysis of randomized trials suggests valgus bracing for medial knee OA results in small-to-moderate improvements in pain. Effect sizes vary based on study design and warrant future research.

Staged medial opening wedge high tibial osteotomy for bilateral varus gonarthrosis: biomechanical and clinical outcomes.

PURPOSE: (1) To evaluate the effect of staged bilateral medial opening wedge high tibial osteotomy (HTO) on established biomechanical risk factors for disease progression and on validated measures of pain and function and (2) To compare outcomes in patients having the second surgery staged within or beyond 12 months of the first surgery. METHODS: Thirty-seven patients with bilateral varus alignment and medial compartment osteoarthritis underwent staged bilateral medial opening wedge HTO (21 within and 16 beyond 12 months). Patients underwent full-limb standing anteroposterior radiographs to determine frontal plane alignment (mechanical axis angle) and three-dimensional gait analysis to estimate the distribution of load across the tibiofemoral compartments (external knee adduction moment). Patients also completed the Knee Injury and Osteoarthritis Outcomes Scores (KOOS), the Lower Extremity Functional Scale, the Short Form Health Survey and the six-minute walk test (6MWT). Patients (both limbs) were evaluated before and approximately 6, 12 and 24 months after each surgery. RESULTS: There were statistically and clinically significant changes in both limbs that were of similar magnitudes and that remained relatively stable over time postoperatively. Mean (95% CI) improvements in outcomes were as follows. Mechanical axis angle: 9.4° (8.4°, 10.4°) (i.e. average change of both limbs), peak knee adduction moment: -1.7%BW*Ht (-2.1, -1.4 %BW*Ht) (i.e. average change of both limbs), 6MWT: 36.7 m (19.4, 54.0 m), SF-12 Physical Component Summary: 12.0 (8.5, 15.5) and KOOS Pain: 25.4 (19.6, 31.2). Other than the shorter time period to reach maximum benefit of both surgeries, there were no remarkable differences at final assessment between patients having surgeries staged within or beyond 12 months. CONCLUSIONS: The present findings demonstrate that patients with bilateral varus gonarthrosis experience marked improvements in established biomechanical risk factors for disease progression bilaterally (mechanical axis angles and external knee adduction moments), as well as clinically important improvements in patient-important outcomes, after staged medial opening wedge HTO. Current findings suggest no difference in outcomes for patients who have the second surgery staged within or beyond 12 months of the first surgery. LEVEL OF EVIDENCE: IV.

Changes in valgus and varus alignment neutralize aberrant frontal plane knee moments in patients with unicompartmental knee osteoarthritis.

To elucidate the effects of frontal plane lower limb alignment on gait biomechanics, we compared knee joint moments and frontal plane angular impulse before and after varus or valgus producing osteotomy in patients with lateral or medial compartment osteoarthritis, and in healthy participants with neutral alignment. Thirty-nine subjects participated (13 valgus gonarthrosis, 13 varus gonarthrosis, 13 controls). Patients underwent 3D gait analysis and radiographic assessment of alignment (mechanical axis angle; MAA) before and 6 months after surgery, and were compared to controls. Mean changes (95%CI) in frontal plane angular impulse indicated a 0.82%BW·Ht·s (0.49,1.14) increase in adduction impulse in patients after varus osteotomy, and a 0.61%BW·Ht·s (0.37,0.86) decrease in adduction impulse in patients after valgus osteotomy, equating to a 53% and 45% change from preoperative values, respectively. Preoperative frontal plane angular impulse was significantly different between both patient groups and controls before surgery, but not after. The cross-sectional data suggest that frontal plane angular impulse is very highly correlated to MAA before surgery (R=0.87), but not after (R=0.39), and that an adduction impulse predominates until 7° of valgus, at which point an abduction impulse predominates. The prospective surgical realignment data indicate that for every 1° change in MAA toward varus, there is a 0.1%BW·Ht·s (or 1.6 N m s) change in frontal plane knee angular impulse toward adduction, and vice versa. These overall findings illustrate the potent effects that lower limb alignment can have on frontal plane gait biomechanics.

Combined effects of a valgus knee brace and lateral wedge foot orthotic on the external knee adduction moment in patients with varus gonarthrosis.

OBJECTIVE: To test the hypothesis that a custom-fit valgus knee brace and custom-made lateral wedge foot orthotic will have greatest effects on decreasing the external knee adduction moment during gait when used concurrently. DESIGN: Proof-of-concept, single test session, crossover trial. SETTING: Biomechanics laboratory within a tertiary care center. PARTICIPANTS: Patients (n=16) with varus alignment and knee osteoarthritis (OA) primarily affecting the medial compartment of the tibiofemoral joint (varus gonarthrosis). INTERVENTIONS: Custom-fit valgus knee brace and custom-made full-length lateral wedge foot orthotic. Amounts of valgus angulation and wedge height were tailored to each patient to ensure comfort. MAIN OUTCOME MEASURES: The external knee adduction moment (% body weight [BW]*height [Ht]), frontal plane lever arm (cm), and ground reaction force (N/kg), determined from 3-dimensional gait analysis completed under 4 randomized conditions: (1) control (no knee brace, no foot orthotic), (2) knee brace, (3) foot orthotic, and (4) knee brace and foot orthotic. RESULTS: The reduction in knee adduction moment was greatest when concurrently using the knee brace and foot orthotic (effect sizes ranged from 0.3 to 0.4). The mean decrease in first peak knee adduction moment compared with control was .36% BW*Ht (95% confidence interval [CI], -.66 to -.07). This was accompanied by a mean decrease in frontal plane lever arm of .59cm (95% CI, -.94 to -.25). CONCLUSIONS: These findings suggest that using a custom-fit knee brace and custom-made foot orthotic concurrently can produce a greater overall reduction in the knee adduction moment, through combined effects in decreasing the frontal plane lever arm.

In-shoe plantar pressure measurements for patients with knee osteoarthritis: Reliability and effects of lateral heel wedges.

Although plantar pressure measurement systems are being used increasingly during gait analyses to investigate foot orthotics, there is limited information describing test-retest reliability of such measurements. Objectives of this study were to (1) examine the test-retest reliability of lateral heel pressure (LHP) and centre of pressure (COP) during walking with and without lateral heel wedges, and (2) evaluate the effects of 4° and 8° lateral heel wedges on the magnitude of LHP, the pathway of the COP and the peak external knee adduction moment (KAM) in subjects with and without knee osteoarthritis (OA). Twenty-six subjects, 12 patients with knee OA and 14 healthy subjects, were evaluated during three lateral heel wedge conditions (control, 4° and 8°) with standardized footwear. Three-dimensional analyses of gait with optical motion capture, floor-mounted force plate and in-shoe plantar pressure were completed on two occasions. Intraclass correlation coefficients (ICC(2, 1)) for LHP were excellent (0.79-0.83) while ICCs for COP in the medial-lateral and anterior-posterior directions were more variable (0.66-0.86). Reliability was slightly diminished when using heel wedges. Standard errors of measurement suggested considerable day-to-day variability in an individual's measures. Lateral heel wedges significantly (p<0.001) increased LHP, shifted COP anteriorly and laterally, and decreased the KAM. No significant differences were observed between subjects with and without OA. Although the day-to-day variability appears too large to confidently evaluate changes in individual patients, and decreases in reliability with increases in wedge size indicate caution, these results suggest in-shoe measurement of LHP and COP are appropriate for use in studies evaluating biomechanical effects of foot orthoses for knee OA.