Effects of a Medial Unloader Brace on Gait Mechanics in Patients with Osteochondritis Dissecans

Abstract

Background:Non-operative treatment for osteochondritis dissecans (OCD) of the knee traditionally includes casting, bracing, and activity restrictions. An unloader brace is an option that may result in improved compliance due to the ability of the patient to continue daily activities while maintaining brace wear, and it may have biomechanical advantages for lesion healing. However, the biomechanical efficacy of a medial unloader brace has not been confirmed in a pediatric population.Hypothesis/Purpose:To determine whether the use of a medial unloader brace alters gait mechanics in patients with medial femoral condyle OCD. We hypothesized that while knee alignment in the coronal plane will remain unaltered, the valgus moment will decrease due to the applied tension of the adjusted unloader brace.Methods:Fifteen medial femoral condylar OCD patients (14 male, 12.7±2.6 years, 156.9±14.8 cm, and 52.0±16.2 kg) were tested utilizing a medial Ossur Unloader One knee brace. All patients performed over-ground walking at a self-selected speed under three brace conditions: no brace (NB), unadjusted (U), and adjusted (A; prescribed tension applied). Pelvis and lower extremity kinematic and kinetic data were computed in the sagittal, coronal, and transverse planes during single-limb stance phase (SLS). Wilcoxon signed-rank tests were performed to identify statistical differences between brace conditions (α=0.05), and clinical significance was only determined when statistically significant joint angle and moment differences were greater than 3° and 0.1Nm/kg, respectively.Results:Between braced conditions, mean knee valgus was not statistically significant, however, peak internal knee valgus moment consistently decreased with each brace condition (NB-A: 0.06 Nm/kg, p=0.017). Similarly, hip abduction moment at the second peak of SLS decreased while wearing the brace (NB-U: p=0.061, NB-A: 0.07 Nm/kg, p=0.009).Conclusion:Peak knee valgus moment was decreased during walking with an adjusted medial unloader brace. These results highlight potential biomechanical advantages of a medial unloader brace for medial femoral condylar OCD. Future work will measure compliance of brace wear and compare additional brace designs.Table 1.Coronal plane hip and knee kinematics and kinetics (Mean ± SD) for each brace condition.Figure 1.Average coronal knee angle and moment throughout gait cycle