Background

HTO successfully reduces medial knee pain and improve knee function. However, residual pain during strenuous activities, such as running, is not unusual. HTO normalises walking gait somewhat but pain can cause an individual to alter their gait. The degree to which pain is tolerated during exercise after surgery, and the impact that exercise intensity has on pain levels and gait, is unknown. The purpose of this study was to compare changes in pain levels and gait during walking and jogging at different intensities between HTO patients and healthy, age-matched controls.

Methods

Eleven HTO patients (mean age 55.7 ± 8.6 years; mean BMI 28.5 ± 4.1 kg/m2; 7 males) and eleven age-matched healthy control subjects (mean BMI 24.8 ± 4.1 kg/m2; 5 males) completed the exercise protocol in this study. Knee function and pain was assessed prior to testing using a KOOS questionnaire, a VAS pain score, and a pain intensity score (PIS). Eight bouts of 3 minutes of exercise were performed on a flat treadmill by each participant: 4 bouts walking (performed at RPE 9, 11, 13, and 15) and 4 bouts jogging (performed at RPE 9, 11, 13, 15). Spatiotemporal gait parameters and knee pain were measured during each bout of exercise.

Results

Knee function prior to testing was significantly worse in the HTO group compared to the Control group. Pain according to the VAS and PIS was not significantly different between groups prior to exercise. No significant differences in gait parameters were detected between groups for all bouts of exercise. The HTO group always reported higher absolute VAS and PIS values compared to the Control group during each exercise test, however for bouts 1, 2, and 3 (walking RPE 9, 11, and 13, respectively) median differences were not statistically significant. Median VAS and PIS scores for bout 4 (walking RPE 15), and all jogging bouts, were significantly higher in the HTO group versus the Control group, but never exceeded 0.5/10 (IQR 0-3).

Conclusion

HTO patients demonstrated a normalised gait with very low pain levels in the mid-term after surgery during short bouts of exercise, regardless of the exercise intensity and despite having worse knee function than the control group. HTO patients can expect a post-operative return to physical activity, including high-intensity jogging, without a compromised gait and with minimal residual pain.