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Effect of Unloader knee brace on medial compartment joint space during gait in knee osteoarthritis patients

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Created On: 09/01/2020

Effect of Unloader knee brace on medial compartment joint space during gait in knee osteoarthritis patients

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Key take away

The unloader knee brace had a small but significant increase in medial compartment dynamic joint space during gait, while no significant differences were found in vertical GRF during gait. This finding suggested that decreased external limb loading was not responsible for an increase in medial joint space with bracing. The subjects described reduced pain when wearing the brace. Prescribing the brace to OA patients can cause real changes in joint mechanics that improve pain and function.

Background

This study aimed to examine the effect of the unloader brace on medial compartment dynamic joint space (DJS) during gait, while simultaneously recording ground reaction force (GRF) in varus knee osteoarthritis (OA) patients. This was done via a highly accurate biplane radiography system which permitted the continuous measurement of DJS from heel strike through the midstance phase of gait. It was hypothesized that during gait, DJS in the medial compartment would be more with the unloader brace during gait as compared without the brace.

Method

After two weeks of using the unloader brace, ten varus knee OA patients (age 52 ± eight years) walked with and without the brace on an instrumented treadmill, and biplane radiographs of the OA knees were acquired at 100 Hz. Medial compartment DJS was determined from heel strike to terminal stance (0–40% of the gait cycle) via a validated volumetric model-based tracking process that matched subject-specific 3D bone models to the biplane radiographs. The GRF during gait was assembled at 1000 Hz. Repeated-measures ANOVA was used to explore differences in medial compartment DJS and GRF between the unbraced and braced conditions. A subjective questionnaire concerning the brace use in patients was also collected at the time of the analysis.

Result

There was a small but significant increase (0.3mm) in dynamic joint space in the medial compartment with the unloader brace than without the brace during gait (P = 0.005). No significant difference was observed regarding vertical GRF between the two conditions. The questionnaire depicted that the participants felt reduced pain when wearing the brace.

Conclusion

Unloader brace has a significant effect of increasing medial compartment DJS during gait. It supports the underlying premise that the unloader brace reduces pain by increasing medial joint space during the dynamic loading activities.