Inverse relationship between preoperative radiographic severity and postoperative pain in patients with osteoarthritis who have undergone total joint arthroplasty.

OBJECTIVES

To determine cross-sectionally the influence of risk factors on chronic pain following total joint replacement (TJR) of the knee (TKR) or the hip (THR).

METHODS

Eight hundred sixty post-TKR and 928 post-THR patients were studied. Western Ontario and McMaster Osteoarthritis Index pain scores taken on average 3.2 years postsurgery were correlated to preoperative radiographic severity measured by Kellgren-Lawrence grade (K/L) grade for the knee, Croft grade, and minimum joint space width (minJSW) for the hip and presence of comorbidities.

RESULTS

Known risk factors were able to explain less than 20% of the variance in pain scores post-TJR. The presence of chronic widespread pain determined a higher risk of high pain in both TKR cases (odds ratio (OR) = 3.15 95%CI 1.86-5.30) and THR cases (OR = 5.02 95%CI 2.76-9.14). Other risk factors common to both TKR and THR pain postsurgery were the presence of depression, higher body mass index, younger age, and female gender. Interestingly, low radiographic grade at the index joint presurgery (defined as tibiofemoral K/L <3 for the knee and minJSW >2 mm for the hip) resulted in a significantly increased risk of high pain post-TJR (OR = 1.56; 95%CI 1.04-2.36).

CONCLUSIONS

The risk factors contributing to chronic pain post-TJR remain mostly unknown. Individuals with lower preoperative radiographic OA severity undergoing TJR are more likely to experience high pain post-TJR.