Abstract
Aim To compare clinical outcome and complication rates in obese and non-obese patients five years following primary Total Knee Replacement (TKR) for osteoarthritis.
Methods 328 primary TKRs (283 patients) performed between 1995–1999 at a single institution, were followed up prospectively at intervals of 6, 18, 36 and 60 months following surgery and the clinical outcome based on the Knee Society Clinical rating system (subdivided into a Knee Score (KS) and Function score (FS)) recorded at each follow-up interval. The following complications were also recorded: peri-operative mortality, superficial wound infection, deep wound infection, deep vein thrombosis, and revision rate. Three separate comparisons were undertaken by subdividing the study sample into two sub-groups: (1) Group A comprised two subgroups based on body mass index (BMI) – Non-obese (BMI 15–30, 181 TKRs) or Obese (BMI> 30, 147 TKRs). (2) Group B comprised only female patients divided into two sub-groups based on BMI – ‘Non-obese females’ (BMI 15–30, 84 TKRs) or Obese females (BMI> 30, 87 TKRs). (3) Group C comprised two sub-groups based on body weight alone – weight < 100kg (300 TKRs) or weight > 100kg (28 TKRs). A repeated measures split-plot analysis of variance (SPANOVA) was used to evaluate the difference in the clinical outcome at five years between the sub-groups in Group A, B and C. The complication rates were also compared.
Results There was no significant difference in the KS at five years between sub-groups in Group A (p=0.2), B (p=0.2) or C (p=0.3). There was a statistically significant difference in the FS between the subgroups in Group A (p=0.01) and B (p=0.02) but the effect size (relative magnitude of the difference between means) was small (partial eta squared = 0.02 and 0.03, for Group A and B respectively). There was no significant difference in the FS between sub-groups in Group C (p=0.5). There was no significant difference in the complication rate between the sub-groups in Group A, B or C (p> 0.2 for all complications).
Conclusion Obesity does not influence clinical outcome, peri-operative mortality and complication rates five years following TKR. Further studies are required to determine the long-term success of TKR in obese patients.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
