Impact of postoperative nutritional status on the patients’ clinical outcomes and knee biomechanics following total knee arthroplasty in Japan: a prospective cohort study

Purpose: The impact of postoperative nutritional status on clinical outcomes and biomechanics following total knee arthroplasty remains largely unknown. This study aimed to assess this question using the prognostic nutritional index to evaluate the nutritional status of orthopedic participants.Methods: Patients with knee osteoarthritis who underwent total knee arthroplasty (n=49) in Japan were divided into two groups based on their 1-week postoperative prognostic nutritional index. Group L patients had a prognostic nutritional index <40, whereas Group H comprised patients with a prognostic nutritional index ≥40. Postoperative improvements in Knee Injury and Osteoarthritis Outcome Score were evaluated. The patients performed squats under single-fluoroscopic surveillance in the sagittal plane for biomechanical evaluation. A two-dimensional/three-dimensional registration technique was employed to measure the tibiofemoral kinematics. The axial rotation of the femoral component relative to the tibial component and the anteroposterior translation of the medial and lateral femorotibial contact points were measured.Results: Group H showed significantly higher pain scores than Group L at 12 and 36 months postoperatively and a significantly higher symptom score at 36 months postoperatively. The kinematic comparison revealed that the axial external rotation in Group L was larger than that in Group H from 70° to 80° with flexion. Moreover, in the medial anteroposterior translation, Group L was more anteriorly located than Group H, with flexion beyond 30°.Conclusion: The results suggest that a high postoperative nutritional status significantly improved pain and other symptoms and was associated with better knee biomechanics following total knee arthroplasty.