Mechanical Pain Sensitivity in Postamputation Pain

Objectives: Postamputation, clinical markers of pain-related peripheral and central nervous system hypersensitivity remain understudied. This study aimed to identify whether adults with postamputation pain demonstrate greater pain sensitivity in primary (ie, amputated region) and secondary (ie, nonamputated region) sites, as compared with pain-free peers and controls with intact limbs. Methods: Ninety-four participants postunilateral, transtibial amputation (59 with pain, 35 pain-free) and 39 controls underwent pain-pressure threshold (PPT) testing at 10 sites. Pain-pressure thresholds were normalized to sex-specific control data using Z score conversions. Normalized primary-site and secondary-site PPTs were compared between groups using multivariate analysis of variance (P<0.050). Results: Compared with pain-free peers, adults with postamputation pain demonstrated reduced normalized PPTs across primary and secondary sites (mean difference=0.61-0.74, P=0.001 to 0.007). Compared with controls, adults with postamputation pain demonstrated reduced normalized PPTs (mean difference=0.52, P=0.026) only at primary sites. Discussion: Adults with postamputation pain demonstrate greater amputated region pain sensitivity as compared with pain-free peers or controls with intact limbs, indicating peripheral sensitization persists even after limb healing. Secondary-site pain sensitivity was similar between controls and adults with postamputation pain, suggesting central nervous system hypersensitivity may not be ubiquitous with postamputation pain. Studies are needed to investigate mechanisms underlying pain sensitivity differences between adults with and without postamputation pain.