Primary Targeted Muscle Reinnervation in Above-Knee Amputations in Patients with Unsalvageable Limbs from Limb-Threatening Ischemia or Infection
Brian L Chang, MD1, Josh Mondshine, BS1, Christopher E. Attinger, MD2 and Grant M. Kleiber, MD3, (1)Georgetown University, Washington, DC, (2)Plastic Surgery, MedStar Georgetown University Hospital, Washington, DC, (3)Medstar Georgetown University Hospital, Washington, DC
Introduction
Amputees frequently suffer from chronic pain in both their residual limbs (RLP) and phantom limbs (PLP) following their amputation. While the etiology of their pain is multifactorial, a significant portion can be attributed to the transected sensory nerves, where symptomatic neuromas can cause RLP and aberrances in the CNS-PNS loop leading to PLP. Targeted muscle reinnervation (TMR) is a nerve transfer technique that has been demonstrated to improve pain secondarily and at time of amputation. Most of the literature has reported outcomes on young, otherwise healthy patients undergoing amputations for trauma or cancer resection. To date, no studies have reported on the efficacy of primary TMR at time of above-knee level amputations in the setting of limb-threatening ischemia or infection.
Materials and Methods
This study is a retrospective review of a single-surgeon experience with TMR in patients undergoing above-knee level amputations from January 2018 to December 2019. Patient charts were reviewed for the comorbidities in the Charlson Comorbidity Index (CCI). Post-operative notes were assayed for presence and absence of RLP and PLP, overall pain severity, chronic narcotic use, and ambulatory status. A control group of patients undergoing lower limb amputation who did not receive TMR from January 2014 to December 2018 was used for comparison.
Results
28 patients with above-knee level amputations and primary TMR were included in this study. 64% were male with an average age of 67 years, and BMI of 28.7. 71% have PAD, 64% diabetes, 21% with prior MI, 39% with prior stroke, and a CCI of 5.7. The tibial and common peroneal nerves were transferred in all cases to motor branches to the gastrocnemius, soleus, semimembranosus, semitendinosus, and biceps femoris. The posterior femoral cutaneous nerve was transferred in six patients, and the saphenous nerve in three patients. 58 patients with above-knee level amputations without TMR were included for comparison. The TMR group had significantly less overall pain (42.9% vs. 67.2%, P = 0.03) and RLP (21.4% vs. 43.1%, P = 0.04) and trended towards less PLP (25.0% vs. 39.7%, P = 0.19), overall pain severity (4.2 vs. 6.9, P = 0.07), and narcotic use (10.7% vs. 25.9%, P = 0.11). 42.9% of TMR patients were ambulatory with an average follow-up of 4.4 months, compared to 17.2% of non-TMR at 14.3 months.
Conclusions
TMR can safely and effectively be performed at time of an above-knee level amputation and improves pain outcomes.
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