R. Moyer

Biomechanical effects of valgus knee bracing: a systematic review and meta-analysis

To review and synthesize the biomechanical effects of valgus knee bracing for patients with medial knee osteoarthritis (OA). Electronic databases were searched from their inception to May 2014. Two reviewers independently determined study eligibility, rated study quality and extracted data. Where possible, data were combined into meta-analyses and pooled estimates with 95% confidence intervals (CI) for standardized mean differences (SMD) were calculated. Thirty studies were included with 478 subjects tested while using a valgus knee brace. Various biomechanical methods suggested valgus braces can decrease direct measures of medial knee compressive force, indirect measures representing the mediolateral distribution of load across the knee, quadriceps/hamstring and quadriceps/gastrocnemius co-contraction ratios, and increase medial joint space during gait. Meta-analysis from 17 studies suggested a statistically significant decrease in the external knee adduction moment (KAM) during walking, with a moderate-to-high effect size (SMD = 0.61; 95% CI: 0.39, 0.83; P < 0.001). Meta-regression identified a near-significant association for the KAM effect size and duration of brace use only (β, -0.01; 95% CI: -0.03, 0.0001; P = 0.06); with longer durations of brace use associated with smaller treatment effects. Minor complications were commonly reported during brace use and included slipping, discomfort and poor fit, blisters and skin irritation. Systematic review and meta-analysis suggests valgus knee braces can alter knee joint loads through a combination of mechanisms, with moderate-to-high effect sizes in biomechanical outcomes.

Alignment, body mass and their interaction on dynamic knee joint load in patients with knee osteoarthritis

OBJECTIVE To examine the interaction and relative contributions of frontal plane alignment and body mass on dynamic knee joint loading in patients with knee osteoarthritis (OA). METHODS We completed three-dimensional gait analyses and hip-to-ankle standing anteroposterior radiographs on 487 patients with knee OA referred to a tertiary care center specializing in orthopaedics. RESULTS Using sequential (hierarchical) linear regression, the interaction term (mechanical axis anglexmass) contributed significantly (P<0.001) to a model (total adjusted R(2)=0.70) predicting the external knee adduction moment, that included mechanical axis angle (R(2)=0.37) and mass (R(2)=0.06) while controlling for age, sex, height, Kellgren and Lawrence grade, pain score during walking, gait speed, toe out angle and trunk lean (R(2)=0.25). When the sample was split into tertiles for mass, mechanical axis angle accounted for 32-54% of explained variance in knee adduction moment. In the tertile with greatest mass, results suggest a 3.2 N m increase in knee load for every 1 degrees increase in varus alignment. When split into tertiles for mechanical axis angle, mass accounted for 6-10% of explained variance in the knee adduction moment. In the tertile with the most varus alignment, results suggest a 0.4 N m increase in knee load for every 1 kg increase in mass. CONCLUSION Our findings describe the interaction between alignment and body mass on dynamic knee joint loading, with the association between alignment and load highest in patients with the highest mass. Our findings also emphasize the role of malalignment on knee load at all levels of mass, and have implications for better understanding risk factors and intervention strategies for knee OA.

Valgus Bracing for Knee Osteoarthritis: A Meta‐Analysis of Randomized Trials

To evaluate the effects of valgus knee bracing on pain and function, and compliance and complications, in patients with medial knee osteoarthritis (OA).

Osteoarthritis year in review 2014: mechanics--basic and clinical studies in osteoarthritis.

The purpose of this review was to highlight recent research in mechanics and osteoarthritis (OA) by summarizing results from selected studies spanning basic and clinical research methods. Databases were searched from January 2013 through to March 2014. Working in pairs, reviewers selected 67 studies categorized into four themes--mechanobiology, ambulatory mechanics, biomechanical interventions and mechanical risk factors. Novel developments in mechanobiology included the identification of cell signaling pathways that mediated cellular responses to loading of articular cartilage. Studies in ambulatory mechanics included an increased focus on instrumented knee implants and progress in computational models, both emphasizing the importance of muscular contributions to load. Several proposed biomechanical interventions (e.g., shoe insoles and knee braces) produced variable changes in external knee joint moments during walking, while meta-analysis of randomized clinical trials did not support the use of lateral wedge insoles for decreasing pain. Results from high quality randomized trials suggested diet with or without exercise decreased indicators of knee joint load during walking, whereas similar effects from exercise alone were not detected with the measures used. Data from longitudinal cohorts suggested mechanical alignment was a risk factor for incidence and progression of OA, with the mechanism involving damage to the meniscus. In combination, the basic and clinical studies highlight the importance of considering multiple contributors to joint loading that can evoke both protective and damaging responses. Although challenges clearly exist, future studies should strive to integrate basic and clinical research methods to gain a greater understanding of the interactions among mechanical factors in OA and to develop improved preventive and therapeutic strategies.

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.

Outcomes for patients with the same disease treated inside and outside of randomized trials: a systematic review and meta-analysis

Background: It is unclear whether participation in a randomized controlled trial (RCT), irrespective of assigned treatment, is harmful or beneficial to participants. We compared outcomes for patients with the same diagnoses who did (“insiders”) and did not (“outsiders”) enter RCTs, without regard to the specific therapies received for their respective diagnoses. Methods: By searching the MEDLINE (1966–2010), Embase (1980–2010), CENTRAL (1960–2010) and PsycINFO (1880–2010) databases, we identified 147 studies that reported the health outcomes of “insiders” and a group of parallel or consecutive “outsiders” within the same time period. We prepared a narrative review and, as appropriate, meta-analyses of patients’ outcomes. Results: We found no clinically or statistically significant differences in outcomes between “insiders” and “outsiders” in the 23 studies in which the experimental intervention was ineffective (standard mean difference in continuous outcomes −0.03, 95% confidence interval [CI] −0.1 to 0.04) or in the 7 studies in which the experimental intervention was effective and was received by both “insiders” and “outsiders” (mean difference 0.04, 95% CI −0.04 to 0.13). However, in 9 studies in which an effective intervention was received only by “insiders,” the “outsiders” experienced significantly worse health outcomes (mean difference −0.36, 95% CI −0.61 to −0.12). Interpretation: We found no evidence to support clinically important overall harm or benefit arising from participation in RCTs. This conclusion refutes earlier claims that trial participants are at increased risk of harm.

Combined Tibial Tubercle Osteotomy With Medial Opening Wedge High Tibial Osteotomy Minimizes Changes in Patellar Height A Prospective Cohort Study With Historical Controls

Background: Medial opening wedge high tibial osteotomy (HTO) for the treatment of varus gonarthrosis can be associated with inadvertent decreases in patellar height. Hypothesis: Decreases in patellar height observed after medial opening wedge HTO can be minimized with the addition of a tibial tubercle osteotomy (TTO). Study Design: Cohort study; Level of evidence, 3. Methods: Twenty-nine patients undergoing medial opening wedge HTO with a concurrent TTO were matched with 29 controls who previously underwent medial opening wedge HTO without a TTO. Both groups had substantial varus malalignment (mean mechanical axis angle, −10° ± 3°) requiring large corrections. Measurements of patellar height and posterior tibial slope were calculated from standing lateral radiographs and compared preoperatively and 6 months postoperatively. Patellar height measures included the Blackburne-Peel index, Caton-Deschamps index, Miura-Kawamura index, Insall-Salvati ratio, and modified Insall-Salvati ratio. Results: The changes in the Blackburne-Peel, Caton-Deschamps, and Miura-Kawamura indices were significantly less in the HTO/TTO group versus the HTO group. There were 3 of 29 (10%) new cases that met the radiographic criteria for patella infera in the HTO/TTO group versus 11 of 29 (38%) new cases of patella infera found postoperatively in the HTO group, suggesting an absolute risk reduction of 28% with TTO. The changes in the Blackburne-Peel and Caton-Deschamps indices were correlated to a larger preoperative varus deformity in the coronal plane (r = 0.52 and r = 0.41, respectively). Conclusion: The addition of a TTO when performing a medial opening wedge HTO minimizes the decreases in patellar height associated with the procedure.

Combined versus individual effects of a valgus knee brace and lateral wedge foot orthotic during stair use in patients with knee osteoarthritis

The aim of this study was to investigate the combined and individual biomechanical effects of a valgus knee brace and a lateral wedge foot orthotic during stair ascent and descent in patients with knee osteoarthritis (OA). Thirty-five patients with varus alignment and medial knee OA were prescribed a custom valgus knee brace and lateral wedge foot orthotic. Knee angles and moments in the frontal and sagittal planes were determined from 3D gait analysis completed under four randomized conditions: (1) control (no knee brace or foot orthotic), (2) knee brace, (3) foot orthotic, and (4) combined knee brace and foot orthotic. Additional measures included the vertical ground reaction force, trunk lean, toe out and gait speed. During the combined use of a knee brace and foot orthotic, significant decreases in the knee adduction angle (2.17, 95%CI: 0.50-3.84, p=0.013) and 2nd peak EKAM (0.35, 95%CI: 0.17-0.52, p<0.001) were observed during stair descent; and significant increases in the EKFM were observed during stair ascent (0.54, 95%CI: 0.30-0.78, p<0.001) and descent (1stpk: 0.48, 95%CI: 0.15-0.80, p=0.005; 2ndpk: 0.55, 95%CI: 0.34-0.76, p<0.001). Fewer gait compensations were observed between conditions during stair descent compared to ascent, except for toe out. Findings suggest greater effects on gait when both knee brace and foot orthotic are used together, resulting in a more normal gait pattern. However, whether or not a true change in knee joint load can be inferred when using these orthoses remains unclear. Further research is required to determine the clinical importance of the observed changes.

Sensitivity of different measures of frontal plane alignment to medial and lateral joint space narrowing: From the osteoarthritis initiative

OBJECTIVES To explore cross-sectional relationships between a new radiographic measure of the femorotibial angle (FTA), the hip-knee-ankle angle (HKA), and the goniometry; to quantify sex differences between measures; and to evaluate the sensitivity of these measures to medial and lateral joint space narrowing (JSN). METHODS Concurrent validity was evaluated in 2123 knees from the osteoarthritis (OA) initiative using Pearson correlation coefficients (r) and Bland-Altman plots (offsets). Diagnostic validity with respect to JSN was evaluated using areas under the receiver-operating characteristic curves (AUC) and standardized mean differences (SMD). Analyses were stratified by sex and JSN. RESULTS JSN and sex contributed significantly to regression models predicting offsets between measures (p < 0.001), after controlling for age, BMI, and OA severity. There were weak correlations between FTA vs. goniometry (r: 0.16-0.22), and moderate correlations between FTA vs. HKA (r: 0.25-0.53) and HKA vs. goniometry (r: 0.40-0.67). The offset between the new FTA measure and HKA was larger in females than males (p < 0.001). Offsets between radiographic measures and goniometry also varied by sex and JSN (FTA: 2.9°-7.6°; HKA: 0.5°-2.4°). AUC (0.74-0.91) and SMD (0.53-3.80) between JSN strata were largest for FTA, whereas diagnostic validity was moderate for HKA (AUC: 0.69-0.80; SMD: 0.43-2.04) and weakest for handheld goniometry (AUC: 0.56-0.63; SMD: 0.07-0.90). CONCLUSIONS Compared to HKA, goniometry demonstrated poor diagnostic validity with respect to JSN. The new FTA measure, in contrast, represented a reasonable surrogate of radiographic disease severity (JSN). The new FTA measure was skewed in the varus direction when compared to HKA and more so in females. This requires cautious interpretation when measurements are related to previous studies.

The Value of Preoperative Exercise and Education for Patients Undergoing Total Hip and Knee Arthroplasty: A Systematic Review and Meta-analysis

Background: Existing evidence regarding the value of preoperative education and/or exercise (prehabilitation) for patients undergoing total joint replacement is conflicting. The purpose of this study was to conduct an updated, comprehensive systematic review with meta-analyses to determine the longitudinal effects and efficacy of prehabilitation on postoperative outcomes in patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA). Methods: We searched 11 electronic databases (MEDLINE, AMED, CINAHL, Embase, Scopus, ProQuest, PEDro, SportDiscus, PsycINFO, and Cochrane) from their inception to May 2016 for randomized controlled trials that compared changes in pain, function, strength, anxiety, and hospital length of stay following THA or TKA. Two reviewers independently determined study eligibility, rated study quality, and extracted data. There were no restrictions on study dates, patient characteristics, or the follow-up time point at which postoperative outcomes were measured. We excluded trials comparing 2 interventions. Methodological quality assessments were performed using the Cochrane risk-of-bias tool. We calculated pooled estimates, with 95% confidence intervals (CIs), of standardized mean differences (SMDs). Results: Thirty-five studies with 2,956 patients were included. After a preoperative program, patients undergoing THA, but not TKA, had significantly less postoperative pain than controls (SMD = 0.15, 95% CI = 0.03 to 0.27, p = 0.017). Postoperative function was also significantly improved compared with controls, with similar improvement after THA (SMD = 0.32, 95% CI = 0.15 to 0.50, p < 0.001) and TKA (SMD = 0.32, 95% CI = 0.06 to 0.57, p = 0.015). Significantly greater quadriceps strength was observed after TKA (SMD = 0.42, 95% CI = 0.16 to 0.68, p = 0.002). No significant differences in hamstring strength were observed between groups after TKA (p = 0.132). Small-to-moderate but nonsignificant improvements in anxiety (SMD = 0.17, 95% CI = −0.05 to 0.39; p = 0.128) were observed after THA, and length of stay was significantly shorter after TKA (SMD = 0.54, 95% CI = 0.24 to 0.84, p < 0.001) and THA (p = 0.027). Conclusions: Overall effect sizes for prehabilitation were small to moderate. In patients undergoing TKA, significant improvements were observed in function, quadriceps strength, and length of stay. In patients undergoing THA, significant improvements were observed in pain, function, and length of stay. Included studies were inconsistent with regard to the types of outcome measures reported, and the quality of the interventions varied. A more standardized approach to reporting of clinical trial interventions and patient compliance is needed to thoroughly evaluate the effects of prehabilitation on postoperative outcomes. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.