TMR and the Risk of Postsurgical Complications

While targeted muscle reinnervation (TMR) has shown tremendous promise for relieving neuroma pain, phantom limb pain, and residual limb pain, there have been no large, randomized trials exploring its rates of complications compared to traditional amputations.

To address this issue, Deeyor et al. conducted a study using a national database to determine the long-term complications of patients undergoing TMR vs. traditional amputation to address any potential benefits and downsides of the procedure. Their findings, they hoped, would be able to help guide the use of TMR in the general population.

Comparing Complications in TMR vs. Traditional Amputation

Using the PearlDiver Mariner dataset, one of the largest datasets of health insurance claims in the U.S., the study authors analyzed a total of 76,528 patients who had undergone an amputation between 2015 and 2020. Of these, 116 patients underwent TMR, while the rest experienced a traditional amputation.

Here are some of their key findings:

• • Differences in Complications: There was no statistically significant difference in TMR complications when compared to traditional amputation complications, even after controlling for gender, age and Charlson Comorbidity Index.
  • Average Overall Costs: Average overall costs for TMR vs. traditional amputation at one year were similar between the two groups at $32,632 vs. $36,219 respectively.

The study authors note that their findings show that the majority of complications and costs likely arise from the need for the amputation itself and not the respective procedures. They acknowledge that this is an important finding because two major critiques of TMR include that the increased upfront operative time could potentially increase risks of TMR complications and the costs of care.

The lack of a significant difference in cost between the two procedures is thought to be an important finding because TMR involves multiple nerve transfers, which increases the immediate cost of care.

Further, their findings showed that the initial investment in TMR could produce long-term cost savings by reducing the use of narcotics, increasing the likelihood of ambulation, reducing chronic pain, and more successfully returning a patient to their daily activities.

TMR Can Improve Outcomes in Even Highly Comorbid Amputees

Deeyor et al. had found that even after controlling for comorbidities, patients undergoing TMR were not significantly more likely to have a TMR complication. In their study published just a year earlier, Chang et al. showed similar results—even with patients who were highly comorbid.

Chang et al. examined 100 highly comorbid patients who had undergone TMR at the time of below-knee amputation, and 100 similarly comorbid patients who had undergone below-knee amputation prior to their initiation of their TMR protocol. Their study is the first of its kind to examine the efficacy and safety of TMR for below-knee amputation in medically comorbid patients.

TMR complications that required operative debridement and revision were lower than those who received traditional amputation, at 16% vs. 30%.

Patients who underwent TMR were also significantly more likely to be pain-free after their procedure than patients who had undergone traditional amputation, at 71% vs. 36%, and were more likely to be ambulating at their most recent follow-up, at 91% vs. 71%.

The study authors note that this is an “impactful” finding because many amputees are unable to ambulate due to pain, which highlights the ability of TMR to relieve pain to such an important degree.

Chang et al. suggest that TMR should be performed by all surgeons who perform lower extremity amputations and peripheral nerve transfers, given its benefits in a high-risk patient population.