Associations of Quadriceps and Prefemoral Fat Pad MRI Parameters With Postoperative Pain and Functional Outcomes After Total Knee Arthroplasty in Patients With Knee Osteoarthritis

AIM: To investigate the relationship between quantitative magnetic resonance imaging parameters of the quadriceps fat pad (QFP) and prefemoral fat pad (PFP) and pain and functional outcomes at 1 month after total knee arthroplasty (TKA) in patients with knee osteoarthritis. METHODS: We retrospectively collected the clinical and imaging data of patients with knee osteoarthritis who underwent primary unilateral TKA at Shihezi People’s Hospital between October 2025 and April 2026 and had completed knee magnetic resonance imaging before surgery. The following imaging parameters were extracted: (1) QFP: the craniocaudal diameter, anteroposterior diameter, oblique diameter, T1 value, T2 value, proton density (PD) value, high signal intensity, and mass effect; and (2) PFP: maximum thickness and high signal intensity. Postoperative pain and physical function scores at 1 month after surgery were obtained from the medical record system. Spearman correlation analysis and multiple linear regression analysis were performed to identify imaging markers associated with postoperative clinical outcomes. RESULTS: Spearman correlation analysis showed that the T2 value, hyperintensity, and mass effect of the QFP, as well as the hyperintensity and maximum thickness of the PFP, were positively correlated with postoperative pain and physical function scores. Multiple linear regression analysis showed that the T2 value of QFP, mass effect, QFP hyperintensity, and PFP hyperintensity were significantly associated with postoperative pain. The T2 value of QFP, mass effect, and PFP hyperintensity and maximum thickness were significantly associated with postoperative physical function scores. CONCLUSIONS: This retrospective study showed that quantitative and morphological parameters of the QFP and PFP extracted from preoperative routine magnetic resonance imaging (MRI) were significantly associated with postoperative pain and functional outcomes in patients with knee osteoarthritis undergoing TKA. These findings suggest that specific imaging features may be associated with poorer outcomes and provide preliminary evidence for clinical consideration. However, prospective studies with larger sample sizes are warranted to validate these exploratory findings.