Unloader knee brace increases medial compartment joint space during gait in knee osteoarthritis patients

Abstract

Objectives: Clinical outcome measures suggest the unloader brace provides small-to-moderate improvements in pain and function in varus knee osteoarthritis (OA) patients. However, controversy still exists as to whether the brace has the real effect of increasing tibiofemoral joint space in the medial compartment during functional activity. As a limitation, the previous studies did not report ground reaction forces (GRF) with and without the brace, which could be a confounding factor affecting joint space. Therefore, the purpose of the present study was to investigate the effect of an unloader brace on dynamic joint space in medial compartment in OA patients while simultaneously recording GRF during gait. The hypotheses were (1) dynamic joint space in the medial compartment would be greater with the unloader brace than without the brace during gait, and (2) GRF during gait would be smaller with the brace than without the brace. Methods: Ten varus knee OA patients were enrolled (Age: 52±8 years). After minimum 2-week daily use of the unloader brace, subjects walked (1.0 m/s) on an instrumented treadmill while biplane radiographs of the OA knees were acquired at 100 Hz. Tibiofemoral motion was determined from the biplane radiographs from initial contact to terminal stance phase (gait cycle: 0-40%) using a previously validated model-based tracking process. Dynamic joint space measurement in the medial compartment was performed using previously reported method. Briefly, the medial tibial plateau was divided into 9 sub-regions (Figure 1A) and the average minimum distance between femur and tibia subchondral bone was calculated in each region. The region with the smallest joint space over the three walking trials was selected for the analysis. GRF during gait were collected at 1000Hz and normalized by each subject's body weight. Output parameters were averaged over 10% intervals of the gait cycle. Two-way repeated measures ANOVA (gait cycle x brace condition) was used to explore differences in medial compartment dynamic joint space and GRF between the 2 conditions (unbraced and braced). Post-hoc paired t-tests identified the differences between the 2 conditions during the same gait cycle period. Significance level was set as P < 0.05. A subjective questionnaire for the brace usage was collected at the time of the test. Results: The dynamic joint space in the medial compartment was significantly greater with the unloader brace than without the brace during gait (P = 0.004) (Table 1, Figure 1B). The average difference between the 2 conditions was 0.27 mm (95% confidential interval: 0.12-0.43). No significant difference was observed in terms of GRF between unbraced and braced conditions. The questionnaire showed participants felt reduced pain (4.1±0.7 out of 5 scale) and were comfortable (3.8±0.8 out of 5) when wearing the brace. Conclusion:The unloader knee brace induced a small but significant increase in medial dynamic joint space during gait. Furthermore, no differences in GRF during gait were found between unbraced and ...

Biomechanical Effect of Valgus Knee Braces on the Treatment of Medial Gonarthrosis: A Systematic Review

“…Four studies reported the effects of valgus braces on GRF ( Figure 5(b) ). Three studies found no significant difference between braced and unbraced conditions [ 27 , 33 , 52 ]. However, Schmalz et al [ 38 ] argued that the horizontal force on the arthritic limb was increased by 16.4% BW in brace condition.…”

“…Dessinger et al [ 62 ] found that 80% of patients experienced a medial joint space increase of more than 1.0 mm at heel strike, while 65% had a similar change during midstance. Nagai et al [ 52 ] showed that the dynamic space of the medial compartment was significantly increased by 0.3 mm after wearing the brace. In addition, one study [ 63 ] found no significant difference in the separation of the medial and lateral compartments between the braced and unbraced conditions.…”

“…This systematic review was conducted to evaluate the spatiotemporal, kinematic/kinetic, morphological, and muscle effects of valgus braces on patients with medial gonarthrosis, suggesting that the valgus brace could significantly change the biomechanics of the knee joint during daily activities through a multitude of mechanisms. Studies found that the potential mechanisms of valgus braces included applying valgus moments at the knee to directly oppose KAM [ 21 , 23 , 26 , 28 ], altering the alignment of the lower limbs in the frontal plane [ 23 , 29 ], increasing medial joint space during gait [ 52 , 61 , 62 ], and increasing knee stability to reduce muscle cocontraction [ 21 , 72 ].…”

Are All Unloader Braces Created Equal? Recommendations for Evidence-Based Implementation of Unloader Braces for Patients with Unicompartmental Knee OA

“…19 In vivo and clinical imaging studies provide support that this mechanism of offloading is valid, though contrasting data have also been reported, 20 such that further validation is necessary. 15,19,21 Other Reported Mechanisms…”

Sagittal and Frontal Plane Knee Angular Jerk Effects During Prolonged Load Carriage

“…These increases in vertical ground reaction force may further load the knee joint and present as jerkier motion, particularly in the frontal plane, as the duration of walking progresses. Larger vertical ground reaction forces and jerkier frontal plane knee motions may load the medial knee joint compartment, increasing the pain and loss of articular cartilage that characterize knee osteoarthritis [118][119][120][121] . Yet, significant increases in jerky knee motion were limited to the frontal plane, despite the fact that individuals reportedly exhibit greater peak sagittal plane knee angles and moments as duration of walking progresses 32,58 .…”