Preoperative gait adaptations persist one year after surgery in clinically well-functioning total hip replacement patients

The purpose of this study was to evaluate whether preoperative gait adaptations persist one year after THR in the same set of subjects. The hypothesis tested was that hip dynamic range of motion and peak external moments during walking return to normal after THR. Hip kinematics and kinetics were measured for 28 subjects before and one year after THR and compared to those of 25 subjects with radiographically normal hips. All THR subjects improved clinically after surgery with Harris hip scores improving from 33-85 (average 53) to 61-100 (average 95) (sign test p<0.001). Preoperatively dynamic hip range of motion (ROM), and all peak external moments were reduced compared to normal (Mann-Whitney p< or =0.040). Improvement was seen in the ROM and all but the frontal plane, and external rotation peak moments (Friedman p< or =0.023). The preoperative and postoperative values of the ROM, and peak flexion, abduction and external rotation moments were all significantly correlated (Spearman p<0.020) indicating a possible learned effect from before THR surgery. Postoperative THR subjects continued to have a significantly lower than normal ROM, and peak adduction and peak internal rotation moments (Mann-Whitney p< or =0.003). Despite good to excellent clinical functional outcome, gait in THR patients does not return to normal by one year after surgery. Aggressive muscle strengthening is currently not emphasized after THR surgery. Some THR patients may benefit from more intensive rehabilitation before and after surgery.