Objectives: To evaluate the effect of resurfacing versus standard total hip replacement on post26
surgery hip and knee muscle strength recovery in a prospective randomized controlled trial at the
27 Department of Orthopaedics, University Hospital, Odense, Denmark. Methods: Forty-three patients
28 were randomized into (A) standard total hip arthroplasty (S-THA) and (B) resurfacing total hip
29 arthroplasty (R-THA). Pre-surgery assessment and follow-up were conducted (8, 26 and 52 wks).
30 Maximal isometric muscle strength (Nm) and between-limb asymmetry for the knee
31 extensors/flexors, hip adductors/abductors, hip extensors/ flexors were analysed Results: Maximal
32 knee extensor and hip abductor strength were higher in S-THA than R-THA at 52 wks post surgery
33 (P ≤ 0.05) and hip extensors tended to be higher in S-THA at 52 wks (P=0.06). All muscle groups
34 showed substantial between-limb strength asymmetry (7 to 29%) with the affected side being
35 weakest (P ≤ 0.05) and hip flexors being most affected. Asymmetry was present in half of the
36 muscle groups at 26 wks (P ≤ 0.05), and remained present for the hip flexors and hip adductors at
37 52 wks (P ≤ 0.05). Conclusions: R-THA patients showed an attenuated and delayed recovery in
38 maximal lower limb muscle strength (in 2/6 muscle groups) compared to S-THA. Notably, the
39 attenuated strength recovery following R-THA was most markedly manifested in the late phase (1
40 yr) of post surgical recovery, and appeared to be due to the detachment of the lower half of the
41 gluteus maximus muscle rather than implant design per se. Thus, the present data failed to support
42 the hypothesis that R-THA would result in an enhanced strength rehabilitation compared to S-THA.
43 Further, between-limb asymmetry remained present for hip flexors and adductors after 52 wks