Incidence and Patient-Level Risk Factors for Complex Regional Pain Syndrome Following Cubital Tunnel Surgery

Purpose: Complex regional pain syndrome (CRPS) is a debilitating complication reported after upper-extremity surgeries, yet its incidence following isolated cubital tunnel surgery (CuTS) remains undefined. This study aimed to estimate the incidence of CRPS after isolated CuTS and to identify independent patient-level risk factors. Methods: A retrospective cohort study was conducted using the TriNetX research database. Patients who underwent a single isolated CuTS between 2000 and 2024 were identified. One-year cumulative incidences of CRPS type I and type II were calculated, excluding individuals with additional upper-extremity trauma or surgery within 1 year before or after CuTS. Separately, multivariable Cox proportional hazards models were performed in the overall CuTS population to evaluate associations between pertinent demographic and clinical factors and time to CRPS development, allowing prior upper-extremity injury and procedural history to be assessed as potential predictors. Results: The query identified 9,719 patients who met inclusion criteria. At 1 year after surgery, the incidences of CRPS type I and type II were 0.20% and 0.13%, respectively. Women were associated with significantly increased hazard of CRPS I but not CRPS II (HR: 2.16, 95% CI: 1.47-3.17). Preexisting fibromyalgia and polyneuropathy were independently associated with increased hazards of both CRPS subtypes. Prior upper-extremity nerve injury and prior forearm or wrist surgery were associated with increased risk of CRPS I, whereas previous proximal nerve injury and sedative-, hypnotic-, or anxiolytic-related disorders were associated with increased risk of CRPS II. Conclusions: CRPS following isolated CuTS is exceedingly rare, with an overall 1-year incidence rate of approximately 0.33%. However, identifiable patient-level risk factors, including female sex, preexisting polyneuropathy and fibromyalgia, selected upper-extremity nerve injuries and surgical procedures, were independently associated with increased risk. These findings provide a uniquely large estimate of CRPS risk following CuTS, offering important insight for preoperative counseling and individualized risk stratification. Type of study/level of evidence: Prognosis II.