Factors influencing the outcomes of minimally invasive total hip arthroplasty: a systematic review

Introduction: The present systematic review investigated possible factors which may influence the surgical outcome of minimally invasive surgery for total hip arthroplasty (MIS THA). Methods: In January 2022, the Embase, Google Scholar, PubMed, and Scopus databases were accessed. All the clinical trials investigating the clinical outcome of MIS THA were considered. Results: Data from 9486 procedures were collected. Older age was moderately associated with greater Visual Analogue Scale (VAS) (P = 0.02) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (P = 0.009) at last follow-up, and shorter surgical duration (P = 0.01). Greater body mass index (BMI) at baseline was moderately associated with greater cup anteversion (P = 0.0009), Oxford Hip Score (OHS) at last follow-up (P = 0.04), longer surgical duration (P = 0.04), increased leg length discrepancy (P = 0.02), and greater rate of infection (P = 0.04). Greater VAS at baseline was weakly associated with greater VAS at last follow-up (P < 0.0001), total estimated blood lost (P = 0.01), and lower value of Harris Hip Score (HHS) (P = 0.0005). Greater OHS at baseline was associated with greater post-operative VAS (P = 0.01). Greater WOMAC at baseline was associated with lower cup anteversion (P = 0.009) and greater VAS (P = 0.02). Greater HHS at baseline was associated with shorter hospitalisation (P = 0.001). Conclusion: Older age and greater BMI may represent negative prognostic factors for MIS THA. The clinical outcome is strongly influenced by the preoperative status of patients.