Preoperative Radiographic Osteoarthritis Severity Modifies the Effect of Preoperative Pain on Pain/Function After Total Knee Arthroplasty

Abstract

Background: Osteoarthritis (OA) severity as demonstrated by preoperative radiographs and preoperative pain play an important role in the indication for total knee arthroplasty (TKA). We investigated whether preoperative radiographic evidence of OA severity modified the effect of preoperative self-reported pain on postoperative pain and function 1 and 2 years after TKA for OA. Methods: Data from the Longitudinal Leiden Orthopaedics Outcomes of Osteoarthritis Study (LOAS), a multicenter cohort study on outcomes after TKA, were used. OA severity was assessed radiographically with the Kellgren and Lawrence (KL) score (range, 0 to 4). Pain and function were evaluated with the Knee injury and Osteoarthritis Outcome Score (KOOS). After adjustment for body mass index (BMI), age, sex, and the Mental Component Summary scores from the Short Form-12, multivariate linear regression analyses with an interaction term between the preoperative KL score and preoperative pain were performed. Results: The study included 559 patients. The preoperative KL score was independently associated with 1-year postoperative pain and function (β = 5.4, 95% confidence interval [CI] = 1.4 to 9.4, and β = 7.7, 95% CI = 3.2 to 12.2), while preoperative pain was associated only with postoperative pain (β = 0.3, 95% CI = 0.1 to 0.6) and not with postoperative function (β = 0.2, 95% CI = −0.2 to 0.5). Comparable associations were found between 2-year postoperative pain and KL score (β = 8.0, 95% CI = 3.2 to 12.7) and preoperative pain (β = 0.5, 95% CI = 0.1 to 0.8) and between 2-year postoperative function and KL score (β = 7.7, 95% CI = 3.2 to 12.2). The study showed a trend toward the KL score modifying the effect of preoperative pain on 1-year postoperative pain (β = −0.1, 95% CI = −0.1 to 0.0) and 2-year postoperative pain (β = −0.1, 95% CI = −0.2 to 0.0) and on 1 and 2-year function (β = −0.1, 95% CI = −0.2 to 0.0 for both), with the effect of preoperative pain on postoperative pain and function seeming to become less important when there was radiographic evidence of greater preoperative OA severity. Conclusions: Patients with less pain and higher KL grades preoperatively had better function and pain outcomes 1 and 2 years after TKA. However, the effect of preoperative pain on the postoperative outcomes seems to become less important when the patient has radiographic evidence of more severe OA. We believe that analysis of the severity of preoperative pain is an important proxy for optimal postoperative patient outcome. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Comparison of KOOS Scores of Middle-Aged Patients Undergoing Total Knee Arthroplasty to the General Dutch Population Using KOOS Percentile Curves: The LOAS Study

“…Finally, in our subgroup analyses, the patient numbers were rather small, especially for men, which hampered conclusiveness. However, despite the smaller patient number, our results were in line with previous findings [32].…”

“…Similarly, we observed less improvement postoperatively in patients having at least one comorbidity compared with patients without comorbidities. Furthermore, we observed greater improvements in patients with preoperatively more severe radiographic OA compared with patient with no to minimal radiographic OA, which is in line with previous findings in the LOAS study [32,33], and with others [34,35]. However, not all previous studies are in agreement [36,37], which could be explained by the inclusion of a limited patient number [36], including only patients with mild radiographic OA in contrast to also including patients with no radiographic OA [36,37], as well as other differences in patient characteristics such as higher age.…”

Hard truths about preoperative knee X-rays

“…On the other hand, there are issues inherent with diagnosis of OA with radiographs which confounds clinical practice. It is therefore timely and apt that van de Water et al (5) conducted a multicentre prospective cohort study of 599 patients, evaluating the effects of preoperative radiographic OA severity on preoperative pain. Their article is entitled, "Preoperative Radiographic Osteoarthritis Severity Modifies the Effect of Preoperative Pain on Pain/Function After Total Knee Arthroplasty: Results at 1 and 2 Years Postoperatively".…”

“…The authors reported that patients with milder radiographic OA were likely to be operated on as a result of their pain rather than radiographic OA severity, as confirmed by similar baseline pain levels across all four different Kellgren-Lawrence groups. Sources of pain that may not be evident on radiographs include extra-articular pathologies, psychosomatic conditions (6) or central pain sensitization (5). Patients with higher pain scores and lower Kellgren-Lawrence grades demonstrated more central pain sensitization (7), which subsequently lead to less improvement following TKA compared with patients with high Kellgren-Lawrence grades and high pain levels (5).…”

“…Sources of pain that may not be evident on radiographs include extra-articular pathologies, psychosomatic conditions (6) or central pain sensitization (5). Patients with higher pain scores and lower Kellgren-Lawrence grades demonstrated more central pain sensitization (7), which subsequently lead to less improvement following TKA compared with patients with high Kellgren-Lawrence grades and high pain levels (5). The effect of radiographical severity of OA and diffuse hyperalgesia effect on pre-and postoperative pain scores were previously also studied by Wylde et al (8).…”