Association of Admission Nutritional Status Evaluated by Prognostic Nutritional Index With One-Year Walking Independence After Primary Total Hip Arthroplasty for Osteonecrosis of the Femoral Head: A Retrospective Matched Cohort Study Based on 1,152 Patients.

BACKGROUND

Malnutrition is significantly associated with unfavorable outcomes, but the relevant prognostic assessment is not emphasized in patients who have osteonecrosis of the femoral head (ONFH). This study aimed to assess the association between preoperative nutritional status evaluated by the prognostic nutritional index (PNI) and walking independence at one year postoperatively in patients who have ONFH undergoing primary total hip arthroplasty (THA).

METHODS

This was a retrospective analysis of prospectively collected data from patients admitted to a tertiary referral hospital who had ONFH and underwent primary unilateral THA from October 30, 2014 to April 26, 2019. The restricted cubic spline was used to assess the dose-effect relationship between PNI and recovery of walking independence. Propensity score matching was performed to balance potential preoperative confounders, and multivariable conditional logistic regression analysis was applied to assess the association between malnutrition and losing walking independence (LWI) with perioperative and follow-up factors for further adjustment. Inverse probability treatment weighting and sensitivity analyses were performed to test the robustness of the results. Subgroup analyses were used to determine potential population heterogeneity.

RESULTS

We found a negative relationship between admission PNI levels and recovery of walking independence at one year postoperatively, and that low PNI (< 42.2) was independently associated with a 2.35-fold (95% confidence interval [CI], 1.16 to 4.77; P = 0.018) increased risk of LWI. The results were overall robust. Considerable heterogeneities were observed in the subgroups of age, labor intensity, American Society of Anesthesiologists class, Charlson's comorbidity index, and Association Research Circulation Osseous stage (P for interaction < 0.05).

CONCLUSIONS

Preoperative low-level PNI is a significant risk factor for LWI after THA in patients who have ONFH. This finding supports nutritional screening and interventions for surgeons in decision-making for elective surgery and postoperative rehabilitation management.