In Vivo Biomechanics after Total Hip Arthroplasty: a State-of-the-art Systematic Review.

Purpose:This systematic review aimed to synthesize current literature on in vivo biomechanics following total hip arthroplasty, emphasizing objective laboratory assessments and surgical modifiers to address persistent functional deficits despite favorable clinical outcomes. Methods:A PRISMA-guided systematic review was conducted across seven databases (PROSPERO: CRD42024550457). Eligible studies included human subjects with objective postoperative biomechanical assessments (e.g. 3D motion analysis, force plates, dual fluoroscopy) compared against healthy or contralateral limbs. Data on spatiotemporal parameters, kinematics, kinetics, and surgical subgroups were extracted from 50 included studies. Results:Key findings revealed persistent reductions in hip joint power, gait speed, and stride length, along with joint loading asymmetries >1 year post-operatively. While the direct anterior approach showed faster early gait normalization, the surgical approach had a minimal long-term impact. Conversely, restoring femoral offset and anteversion was strongly associated with improved kinetics. Older patients exhibited greater compensatory trunk movements. Conclusion:The choice of surgical approach has a limited influence on long-term biomechanical restoration. Surgeons should instead prioritize offset restoration, implant choice, and functional component orientation, as static imaging fails to capture dynamic edge-loading. Future rehabilitation must target persistent kinetic asymmetries that standard clinical scores overlook.