K.M. Leitch

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.

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).

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.

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.

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 individuals 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.

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.

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

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.

191 COMBINED EFFECTS OF A VALGUS KNEE BRACE AND LATERAL WEDGE ORTHOTIC ON DYNAMIC KNEE JOINT LOADING IN PATIENTS WITH MEDIAL COMPARTMENT KNEE OSTEOARTHRITIS

Purpose: A number of conservative strategies are suggested to modify the external knee adduction moment and potentially decrease the rate of disease progression for patients with medial compartment knee osteoarthritis (OA). The aim of this study was to compare the effects of a custom-fit knee brace and foot orthotic, when used separately and together, on frontal plane lever arm and external adduction moment about the knee in patients with knee OA.

182 THE EFFECTS OF CHANGES IN BODY COMPOSITION ON DYNAMIC KNEE JOINT LOADING

Methods: Twelve subjects with a traumatic-onset meniscal tear were recruited for this study (11 males; mean age: 19.5±3.0 yrs; 10 lateral tears/2 medial tears). Testing consisted of gait analysis and questionnaires. Retro-reflective markers were placed prior to five walking trials at a self-selected speed. Marker position was recorded with a motion capture system (Motion Analysis Corp), and ground reaction forces were recorded with two force platforms (Advanced Mechanical Technology Inc). The stance phase was analyzed bilaterally, and the variables were sagittal plane knee angle excursion during weight acceptance and from the end of weight-acceptance to midstance, and peak vertical ground reaction force (PVGRF) at heel strike and toe-off. Subjects self-reported knee pain intensity on the 11-point (0–10) numeric rating scale (NRS), fear of movement/re-injury on the shortened Tampa Scale for Kinesophobia (TSK-11), and pain catastrophizing on the Pain Catastrophizing Scale (PCS). Knee angle excursions and PVGRFs were compared between sides with paired t-tests. If a significant difference was found, the magnitude of asymmetry was computed (knee angle excursion: uninjured side-injured side; PVGRF (injured side/uninjured side) *100]. Pearson’s Product Moment correlation determined the association between gait asymmetry and questionnaire scores. Results: Gait variables and questionnaire scores are reported in the Table. Knee angle excursion during weight acceptance and from weight acceptance to mid-stance was reduced on the injured side compared to the uninjured side (p = 0.009 and p =.023, respectively). PVGRF at heel strike and toe-off was not significantly different between sides (p = 0.794 and p=0.869). The asymmetry in knee angle excursion during weight acceptance was negatively correlated with NRS score (r = −0.580, p = 0.048). The asymmetry in knee angle excursion from weight acceptance to midstance was negatively correlated with TSK-11 score (r = −0.833, p = 0.001). Conclusions: Knee angle excursion on the injured side was reduced during the stance phase of gait in people with traumatic meniscal tear. During weight acceptance, knee pain intensity increased as the magnitude of asymmetry decreased; and from the end of weight acceptance until midstance, fear of movement/re-injury increased as the magnitude of asymmetry decreased. Thus, subjects with greater knee motion on the injured side displayed elevated pain and fear of movement/re-injury. These data indicate a potential link between biomechanical measures and relevant psychosocial factors from the fearavoidance model. Although mean PVGRF was not significantly different between sides, asymmetry was as high as 12% (either underor overloading on the injured side) for some subjects.