Favourable mid-term isokinetic strength after primary THA combined with a modified enhanced recovery after surgery concept (ERAS) in a single blinded randomized controlled trial

Purpose: Muscular deficits as part of severe osteoarthritis of the hip may persist for up to two years following total hip arthroplasty (THA). No study has evaluated the mid-term benefit of a modified enhanced-recovery-after-surgery (ERAS) concept on muscular strength of the hip in detail thus far. We (1) investigated if a modified ERAS-concept for primary THA improves the mid-term rehabilitation of muscular strength and (2) compared the clinical outcome using validated clinical scores.

Methods: In a prospective, single-blinded, randomized controlled trial we compared patients receiving primary THA with a modified ERAS concept (n = 12, ERAS-group) and such receiving conventional THA (n = 12, non-ERAS) at three months and one year postoperatively. For assessment of isokinetic muscular strength, a Biodex-Dynamometer was used (peak-torque, total-work, power). The clinical outcome was evaluated by using clinical scores (Patient-Related-Outcome-Measures (PROMs), WOMAC-index (Western-Ontario-and-McMaster-Universities-Osteoarthritis-Index), HHS (Harris-Hip-Score) and EQ-5D-3L-score.

Results: Three-months postoperatively, isokinetic strength (peak-torque, total-work, power) and active range of motion was significantly better in the modified ERAS group. One year postoperatively, the total work for flexion was significantly higher than in the Non-ERAS group, whilst peak-torque and power did not show significant differences. Evaluation of clinical scores revealed excellent results at both time points in both groups. However, we could not detect any significant differences between both groups in respect of the clinical outcome.

Conclusion: With regard to muscular strength, this study supports the implementation of an ERAS concept for primary THA. The combination with a modified ERAS concept lead to faster rehabilitation for up to one-year postoperatively, reflected by significant higher muscular strength (peak-torque, total-work, power). Possibly, because common scores are not sensitive enough, the results are not reflected in the clinical outcome. Further larger randomized controlled trials are necessary for long-term evaluation.