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.