Foot structure and knee joint kinetics during walking with and without wedged footwear insoles.

The relationship between static foot structure characteristics and knee joint biomechanics during walking, or the biomechanical response to wedged insoles are currently unknown. In this study, 3D foot scanning, dual X-ray absorptiometry and gait analysis methods were used to determine structural parameters of the foot and assess their relation to knee joint loading and biomechanical response to wedged insoles in 30 patients with knee osteoarthritis. In multiple linear regression models, foot fat content, height of the medial longitudinal arch and static hind foot angle were not associated with the magnitude of the knee adduction moment (R2 = 0.24, p = 0.060), knee adduction angular impulse (R2 = 0.21, p = 0.099) or 3D resultant knee moment (R2 = 0.23, p = 0.073) during gait. Furthermore, these foot structure parameters were not associated with the patients' biomechanical response to medial or lateral wedge footwear insoles (all p < 0.01). These findings suggest that static foot structure is not associated with gait mechanics at the knee, and that static foot structure alone cannot be utilized to predict an individual's biomechanical response to wedged footwear insoles in patients with knee osteoarthritis.

A three dimensional approach for quantifying resultant loading at the knee.

BACKGROUND: Clinical effectiveness of lateral wedges for knee osteoarthritis is inconsistent across studies. One explanation is that knee loading is not fully described by the peak frontal-plane knee moment. The purpose of this study was to propose a 3D resultant approach to describing moments at the knee and evaluate how this moment changes in response to lateral wedges. METHODS: Walking gait analysis was performed on 20 individuals with knee osteoarthritis, in their own shoes, with and without a six millimeter lateral wedge insole. Frontal-plane and 3D resultant moments were calculated for each participant and footwear condition. Paired t-tests identified differences between footwear conditions, correlations identified relationships between frontal-plane and 3D resultant moments, and regressions assessed relationships between moments and pain. RESULTS: Significant reductions to peak frontal-plane moments (p=0.001) and 3D resultant moments at the same time point (p=0.042) were observed with lateral wedges. While an overall significant correlation was observed between change in frontal-plane moments and change in 3D resultant moments with a lateral wedge (r=0.68, p=0.001), 5/20 participants experienced disparate results where the frontal-plane moment was reduced yet the 3D moment increased. CONCLUSIONS: While lateral wedges alter frontal-plane moment magnitude, the direction of change does not always correspond to the direction of change observed in the 3D resultant moment. Thus resultant knee load may sometimes increase with lateral wedges. CLINICAL RELEVANCE: Future prospective studies should evaluate if changes in 3D resultant moments, and thus total knee load, offer an explanation as to why some participants do not experience clinical benefit from lateral wedges.

Reduced knee adduction moments for management of knee osteoarthritis:: A three month phase I/II randomized controlled trial.

Wedged insoles are believed to be of clinical benefit to individuals with knee osteoarthritis by reducing the knee adduction moment (KAM) during gait. However, previous clinical trials have not specifically controlled for KAM reduction at baseline, thus it is unknown if reduced KAMs actually confer a clinical benefit. Forty-eight participants with medial knee osteoarthritis were randomly assigned to either a control group where no footwear intervention was given, or a wedged insole group where KAM reduction was confirmed at baseline. KAMs, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Physical Activity Scale for the Elderly (PASE) scores were measured at baseline. KOOS and PASE surveys were re-administered at three months follow-up. The wedged insole group did not experience a statistically significant or clinically meaningful change in KOOS pain over three months (p=0.173). Furthermore, there was no association between change in KAM magnitude and change in KOOS pain over three months within the wedged insole group (R2=0.02, p=0.595). Improvement in KOOS pain for the wedged insole group was associated with worse baseline pain, and a change in PASE score over the three month study (R2=0.57, p=0.007). As an exploratory comparison, there was no significant difference in change in KOOS pain (p=0.49) between the insole and control group over three months. These results suggest that reduced KAMs do not appear to provide any clinical benefit compared to no intervention over a follow-up period of three months. ClinicalTrials.gov ID Number: NCT02067208.

Knee angular impulse as a predictor of patellofemoral pain in runners.

BACKGROUND: Identification of mechanical factors associated with patellofemoral pain, the most prevalent running injury, is necessary to help in injury prevention, but unfortunately they remain elusive. HYPOTHESIS: Runners who develop patellofemoral pain have increased knee joint angular impulse in the frontal plane. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: A retrospective study compared knee abduction impulses of 20 patellofemoral pain patients with those of 20 asymptomatic patients. A second prospective study quantified knee angular impulses during the stance phase of running of 80 runners at the beginning of the summer running season. Epidemiologic data were then collected, recording the type and severity of injury of these runners during a 6-month running period. RESULTS: The patellofemoral pain patients in the retrospective study had significantly higher (P = .026) knee abduction impulses (17.0 +/- 8.5 Nms) than did the asymptomatic patients (12.5 +/- 5.5 Nms). Six patients developed patellofemoral pain during the prospective study. The prospective data showed that patients who developed patellofemoral pain had significantly higher (P = .042) knee abduction impulses (9.2 +/- 3.7 Nms) than did matched patients who remained uninjured (4.7 +/- 3.5 Nms). CONCLUSION: The data indicate that increased knee abduction impulses should be deemed risk factors that play a role in the development of patellofemoral pain in runners. CLINICAL RELEVANCE: Footwear and running style can influence knee angular impulse, and the appropriate manipulation of these variables may play a preventive role for patients who are predisposed to patellofemoral pain.

Effectiveness of patellar bracing for treatment of patellofemoral pain syndrome.

OBJECTIVE: To determine the effectiveness of patellar bracing for treatment of patellofemoral pain syndrome (PFPS). DESIGN: Prospective, randomized, single-blinded clinical trial. SETTING: Subjects recruited from the general population of the city of Calgary. SUBJECTS: A total of 136 subjects (79 females and 57 males with a total of 197 affected knees) diagnosed with PFPS. INTERVENTION: Subjects were randomly assigned to 1 of 4 treatment groups: (1) home exercise program, (2) patellar bracing, (3) home exercise program with patellar bracing, and (4) home exercise program with knee sleeve. OUTCOME MEASURES: The outcome measurements were knee function (KF) and 10-cm visual analogue scale (VAS) pain ratings for 3 different situations: knee pain during sport activity, knee pain 1 hour after sport activity, and knee pain after sitting with knees bent for 30 minutes. The outcome measurements were assessed at baseline and at 3, 6, and 12 weeks. The investigators were blinded to the treatment group of each subject. Calculations were made for 95% confidence intervals for the change in KF and VAS pain ratings from baseline measurement to 12 weeks. RESULTS: There was no difference in the 95% confidence intervals in the change of KF and VAS pain ratings among the 4 treatment groups over 12 weeks. CONCLUSIONS: Symptoms of PFPS improved over time in terms of pain and knee function regardless of the treatment group. Patellar bracing did not improve the symptoms of PFPS more quickly when added to a home program of leg strengthening. However, patellar bracing alone can improve the symptoms of PFPS.