Muscular strength and function after total hip arthroplasty performed with three different surgical approaches: one-year follow-up study

Background: Surgical approach influences short-term muscular strength, and leg-strength asymmetry has been demonstrated after total hip arthroplasty (THA). We evaluated muscular strength, physical function and patient-reported outcome measures (PROMs) up to 12 months postoperatively, in patients operated on using 3 different surgical approaches.Methods: 60 patients scheduled for primary THA were allocated to the direct lateral (DLA), posterior (PA) or anterior (AA) approach. The following parameters were evaluated: leg press and abduction strength, pain, 6-minute walking test, Harris Hip Score and Hip disability and Osteoarthritis Outcome Score - Physical Function Shortform (HOOS-PS).Results: Abduction strength in the DLA group was significantly more reduced than the PA and AA groups 12 months postoperatively (p< 0.001). A significant interleg difference in abduction (p< 0.01) and leg press (p< 0.03) persisted in all groups up to 6 months, and up to 12 months in the DLA (p< 0.05). In the AA group, interleg difference in leg press was present up to 12 months (p= 0.01). Pain scores were higher in the DLA than the AA group at 6 months (p= 0.01). Patients in the PA group had better HOOS-PS score than those in the DLA group 3 months postoperatively (p= 0.02). No intergroup differences in pain or PROMs were found 12 months postoperatively.Conclusion: Patients operated via the DLA had reduced muscular strength, HOOS-PS scores and higher pain scores than those who underwent PA and AA type surgery. The non-operated leg was significantly stronger than the operated leg in all groups 6 months postoperatively and this persisted up to 12 months postoperatively for the DLA and AA groups. Clinical Trial Protocol number: ClinicalTrials.gov(NCT01506024).