Factors Associated With the Risk of Neuropathic Pain One Year After Total Knee Arthroplasty and the Protective Role of Local Infiltration Analgesia: A Registry-Based Prospective Cohort Study.

OBJECTIVE: To identify predictors of reduced risk for neuropathic pain (NP) one year after total knee arthroplasty (TKA) among patients who did not report NP before surgery. METHODS: We included primary TKAs performed between January 1, 2014, and June 30, 2022. NP was defined as Douleur Neuropathique en 4 Questions scores ≥4 before and one year after TKA. We selected patients without NP before surgery and ran simple log-binomial regressions and a multiple log-binomial regression on the presence or absence of NP at one year after surgery. We included predictive variables associated with patient characteristics (sex, age at surgery, body mass index [BMI], smoking status, diabetes, medication, and short-form 12-question [SF-12] mental scores) and operative variables (patella resurfacing, type of anesthesia, glucocorticoids, and local infiltration analgesia [LIA]). RESULTS: A total of 889 patients were included for initial analysis, with 636 included in the log-binomial regression. The incidence of NP at one year among the latter was 8.6% (55 of 636). LIA had a strong protective effect with an adjusted risk ratio (RR) of 0.45 (95% confidence interval [CI] 0.26-0.77). LIA led to an NP risk reduction of 6.1% (95% CI 1.4-10.7; 12.2% of NP without infiltration and 6.1% with). The other protective factors identified were higher SF-12 mental scores (adjusted RR 0.97; 95% CI 0.95-1.00), older age (adjusted RR per decade 0.78; 95% CI 0.59-1.03), and BMI <35 (adjusted RR 0.60; 95% CI 0.33-1.09). CONCLUSIONS: Our study identified factors associated with reduced risk of NP one year after TKA among patients without preoperative NP. The use of LIA was newly identified as being associated with a lower likelihood of NP after surgery.