Targeted Muscle Reinnervation Effectively Reduces Pain and Improves Ambulation Rates in a Highly Comorbid Patient Population Undergoing Lower Limb Amputation
Brian L Chang, MD, Christopher M Fleury, MD, Patrick W Harbour, MD, Christopher E. Attinger, MD and Grant M Kleiber, MD, Georgetown University, Washington, DC
Targeted muscle reinnervation (TMR) improves pain in patients with limb amputations. Most studies featured healthy patients who underwent amputations due to trauma or cancer. The success of TMR in patients who receive a lower extremity amputation due to uncompensated PVD or diabetes-related infections has not been studied. Since the inability to ambulate after amputation leads to a rapid decline in health and functional status, effective TMR may be critical in reducing post-amputation mortality in patients with uncompensated comorbidities. The purpose of this study is to evaluate the efficacy of TMR to reduce pain and improve ambulation in a comorbid patient population.
Materials and Methods
This study is a retrospective review of a single-surgeon experience with TMR in a patient population undergoing below-knee amputation from January to December 2018. Patient charts were reviewed for the comorbidities in the Charlson Comorbidity Index (CCI). Post-operative notes were assayed for patient's residual limb pain from 0 to 10, presence of neuropathic pain, severity of phantom limb pain, ambulatory status, and mortality. A control group of patients undergoing below-knee amputation who did not receive TMR from January to December 2017 was used for comparison.
54 patients were included in the TMR group with average age of 57, BMI of 29, and CCI of 5.4. 61% had PVD, 77% had DM, and 33% had ESRD. 46 patients were included in the non-TMR group with average age of 61, BMI of 31, and CCI of 5.4. Average time to follow-up for the TMR group was 3.1 months and 10.8 months for the non-TMR group. Relative to the non-TMR group, the TMR group demonstrated decreased residual limb pain (1.2 vs. 2.7, P = 0.02), neuropathic pain (12.0% vs. 45.2%, P < 0.01), and phantom limb pain (63.0% without pain vs. 47.8%; 1.9% with uncontrolled pain vs. 15.2%, P = 0.01). Ambulation rates were higher with TMR (86.8% vs. 61.9%, P = 0.01). Mortality rate for the TMR group at 1 year was 4.5% compared to 10.9% in the non-TMR group (P = 0.16).
TMR effectively reduces overall, neuropathic, and phantom limb pain in patients undergoing below-knee amputation in the setting of uncompensated comorbidity. More significantly, performing TMR in these patients is associated with increased rates of ambulation and decreased mortality. Decreasing pain and improving ambulation may be critical in improving further morbidity and mortality rates in this very comorbid, high-mortality risk patient population.
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