Prevalence and preoperative risk factors of phantom pain in patients undergoing nontraumatic lower limb amputation: A retrospective study

Background: Phantom limb pain (PLP) occurs frequently after lower limb amputation (LLA). However, there is no consensus on the incidence of PLP, particularly in nontraumatic amputations, because the incidence of PLP varies depending on the comorbidities involved. In addition, the incidence of PLP has been reported to vary by country in which the study was published, and there are few reports from Japan. Therefore, the aim of this study was to determine the incidence and related factors of PLP after amputation from nontraumatic causes and to report on PLP in Japan. Methods: Following the approval (approval number 2025—032) of the Medical Ethics Committee of our hospital, the medical records of patients who underwent above-knee amputation (AKA) or below-knee amputation (BKA) at our hospital between January 1, 2012, and December 31, 2024,were retrospectively reviewed. The primary outcome variable was the incidence of PLP. The inclusion criteria were patients over 18 years old who required nontraumatic AKA or BKA. Patients were excluded if they 1) died within 30 days of surgery or 2) were unable to communicate. For the statistical analysis, p < 0.05 was considered to indicate a significant difference. Results: The sample size was 330 patients with PLP occurring in 34 (10.5%). Multivariatelogistic regression including potential confounders suggested that age, preoperative pain, and preoperative serum albumin levels were independently associated with the development of PLP (adjusted odds ratio (OR) 0.96 [95% confidence interval (CI) 0.93–0.99], p= 0.003; adjusted OR 21.90 [95% CI 4.7–102.0], p< 0.001; and adjusted OR 2.11 [95% CI 1.08–4.12], p= 0.029, respectively). Conclusion: This study revealed a lower incidence (10.3%) of PLP than previous results published in the literature. The present findings revealed that younger age, the presence of preoperative pain, and higher preoperative serum albumin levels were associated with the development of PLP after AKA or BKA.