Inter-limb differences in total hip arthroplasty patients four to five years after surgery: a cross-sectional study

Abstract

BackgroundːTotal hip arthroplasty (THA) is a successful method to reduce pain in end-stage hip osteoarthritis (OA) patients. If the pre-operatively existing deficits in the affected limb are persisting years after THA has not been thoroughly researched. Therefore, the aim of the study was to investigate potential side-to-side differences in long-time THA patients.MethodsːSixteen patients (age: 65.20 ± 5.32 years), who had undergone unilateral THA four to five years ago and ten, healthy, age-matched controls (age = 60.85 ± 7.57 years) were examined for maximum isometric hip muscle strength, range of motion (ROM) of the hip joint, balance and gait on both limbs. Paired t-testes were used to assess the inter-limb differences in THA patients and controls and unpaired t-tests were applied to investigate differences between the two groups.ResultsːIn THA patients, significant deficits on the operated side were found for the center of pressure (COP) length, hip abduction torque and ROM of hip extension with small to medium effects. Compared to the controls, THA patients demonstrated highly significantly reduced hip strength in flexion, extension, abduction and adduction as well as limited ROM in hip flexion and abduction.ConclusionsːA few side-to-side difference were present in THA patients four to five years after the surgery, although the general hip muscle weakness and restricted hip ROM compared to the controls was more severe. Postoperative training focusing on strengthening hip muscles should be continued months and years after the surgery in order to compensate persisting deficits.Trial registrationːDRKS, DRKS00016945. Registered 12 March 2019 – Retrospectively registered, http://www.drks.de/DRKS00016945