Do Patients With Diabetes Have Poorer Improvements in Patient-Reported Outcomes After Total Knee Arthroplasty?

Diabetes is one of the most common comorbidities in patients undergoing total knee arthroplasty (TKA) for osteoarthritis. However, the evidence remains unclear on how it affects patient-reported outcome measures after TKA.

We reviewed prospectively collected data of 2840 patients who underwent primary unilateral TKA between 2008 and 2018, of which 716 (25.2%) had diabetes. All patients had their HbA1c measured within 1 month before surgery, and only well-controlled diabetics (HbA1c <8.0%) were allowed to proceed with surgery. Patient demographics and comorbidities were recorded, and multiple regression was performed to evaluate the impact of diabetes on improvements in patient-reported outcome measures (Short Form 36 (SF-36), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Knee Society Score (KSS)) and knee range of motion (ROM).

Compared with nondiabetics, patients with diabetes were more likely to possess a higher body mass index (P-value <.001), more comorbidities (P-value <.001), and poorer preoperative SF-36 Physical Component Summary (PCS) (P-value <.001), WOMAC (P-value = .002), KSS-function (P-value <.001), and knee ROM (P-value <.001). Multiple regression showed that diabetic patients experienced marginally poorer improvements in KSS-knee (−1.22 points, P-value = .025) and knee ROM (−1.67°, P-value = .013) than nondiabetics. However, there were no significant differences in improvements for SF-36 PCS (P-value = .163), Mental Component Summary (P-value = .954), WOMAC (P-value = .815), and KSS-function (P-value = .866).

Patients with well-controlled diabetes (HbA1c <8.0%) can expect similar improvements in general health and osteoarthritis outcomes (SF-36 PCS and Mental Component Summary, WOMAC, and KSS-function) compared with nondiabetics after TKA. Despite having marginally poorer improvements in knee-specific outcomes (KSS-knee and knee ROM), these differences are unlikely to be clinically significant.