Supine Positioning in Primary Total Hip Replacement is Associated with a Shorter Hospital Stay Than Lateral Positioning: A Retrospective Propensity-Score Matched Cohort Study

Background: There is still no definite answer regarding the most advantageous patient positioning during total hip replacement (THR). We compared whether patient position (lateral vs supine) incur a difference on hospital length of stay (LOS) after primary THR. Methods: This retrospective cohort study included primary THR patients at a single tertiary center (2017–2022). THR patients prepared in the lateral decubitus position were compared to those in the supine position. Propensity score matching at a 1:4 ratio was applied to minimize selection bias. Matching covariates included age, sex, body weight, comorbidities (hypertension, diabetes), anesthesia time, and intraoperative tranexamic acid use. After matching, 990 patients were analyzed (792 lateral; 198 supine). Results: In supine group, the median LOS (5 days, IQR: 4–6) was shorter than the lateral group (5 days, IQR: 5–6; p<0.001). More supine patients were discharged before day 5 (45.5% vs 22.7%, p<0.001). Multivariate analysis revealed supine position as the strongest protective factor against long hospitalization (OR: 0.32, 95% CI: 0.23–0.46, p<0.001). Other notable predictors of long LOS included ASA ≥III (OR: 1.74), longer anaesthesia duration (OR: 1.78), and higher IV fluid administration (OR: 1.08). Patient positioning did not notably predict blood transfusion risk (OR: 1.32, p=0.144). Conclusion: THR patients in supine positioning have a substantial reduction in hospital LOS compared to patients in lateral decubitus positioning, with supine position providing a 68% reduction in risk of long hospitalization. The two groups showed no difference in blood transfusion requirements.