Symptomatic neuromas have long been a problem for amputees, interfering with prosthetic comfort and causing residual pain that often requires treatment. During the last 15 to 20 years, surgeons have used targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) procedures to improve symptoms from neuromas. In TMR, surgeons transfer a mixed or sensory nerve to a “target” transected motor nerve to prevent disorganized axonal growth. RPNI is a less complicated procedure during which the free nerve end is implanted into a denervated free muscle graft, again to decrease disorganized sprouting of axons.
Advances in amputee care at US military centers, driven largely by recent overseas conflicts, have shown anecdotally that TMR and RPNI prevent neuroma formation when used prophylactically during initial amputation, and that they also relieve pain when used as secondary treatment for existing neuromas. In the April 22, 2021 issue of The Journal, Hoyt et al. reviewed records from Walter Reed National Military Medical Center to evaluate changes in pain scores, symptom resolution, and frequency of complications when TMR and/or RPNI were utilized.
The authors analyzed 87 nerve interface interventions in 80 lower extremity amputations that had at least 6 months of follow-up. Fifty-nine of the procedures (68%) were done to treat symptomatic neuromas at a median of 6.5 years after amputation, while 28 procedures (32%) were done for primary prophylaxis. Hoyt et al. found that the sciatic nerve was most likely to develop symptomatic neuromas after amputations at or above the knee, while the tibial and peroneal nerve distributions were most commonly symptomatic after amputations distal to the knee. TMR was utilized alone in 85% of the cases, and surgeons used RPNI most frequently to prevent pain in the sural and saphenous nerves.
Overall, symptom resolution after all procedures was 92% at the final follow-up. VAS pain scores improved from 4.3 to 1.7 points in the delayed-treatment group and did not vary by amputation level. The final mean pain score in the primary-prophylaxis group was 1.0 ±1.9. There were no significant differences in pain outcomes between the primary and delayed groups, but 6 patients in the delayed cohort required revision for residual limb or phantom limb pain. In patients with transtibial amputations, failure to address an asymptomatic tibial nerve during delayed TMR resulted in an increased risk of revision surgery.
Although retrospective in nature, this study shows some encouraging early data to support the primary and secondary use of TMR/RPNI in amputee care. More research is required to determine whether these results in wounded warriors can be replicated in a civilian amputee population.
Click here for a Commentary on this study by Ann R. Schwentker, MD.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
Most insults to the sciatic nerve arise from intervertebral disc conditions or spinal stenosis. However, beyond these common etiologies for sciatic-nerve problems are a host of other, rarer causes. This month’s “Case Connections” explores 4 such peculiar examples.
The springboard case report, from the October 12, 2016 edition of JBJS Case Connector, describes 3 instances of sciatica caused by nerve compression from a perineural cyst arising from a paralabral cyst. All 3 patients were successfully treated with arthroscopic decompression. Three additional JBJS Case Connector case reports summarized in the article focus on:
- A 70-year-old woman with a history of thromboembolism who experienced sciatic nerve palsy from an anticoagulant-induced hematoma
- A 31-year-old woman with sciatic endometriosis who was successfully treated by a team of gynecologists, orthopaedists, and microsurgeons
- A 66-year-old woman in whom sciatic nerve injury occurred after repeated attempts at closed reduction of a dislocated hip prosthesis
Orthopaedists evaluating patients with symptoms characteristic of sciatic-nerve pathology should recognize that these symptoms may arise from a variety of etiological pathways. These patients require a complete history-taking, a thorough physical exam, and an attempt to rule out all possible lumbar causes.
Every month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Here is a summary of selected findings from randomized studies cited in the January 21, 2015 Specialty Update on adult reconstructive knee surgery:
Minimizing Blood Loss
–A randomized study of 101 patients undergoing total knee arthroplasty (TKA) found that those receiving topical tranexamic acid (TXA) intra-articularly at the end of surgery had less blood loss and better postoperative hemoglobin levels than those who received a placebo.
–A randomized study of 50 TKA patients and 50 people undergoing total hip arthroplasty found that those receiving TXA had a significantly smaller decline in postoperative hemoglobin levels and needed 39% fewer units of transfused blood than a group that received normal saline solution.
–A randomized study of 126 patients who underwent denervation or not after TKA with unresurfaced patellae found that the denervation group had better pain scores at three months and higher satisfaction and better range of motion at two years.
–Two randomized studies evaluated the impact of patellar eversion versus lateral retraction/subluxation for joint exposure. One study (n=117) found no between-group differences in quadriceps strength at one year, and the other (n=66) found no between-group differences in pain scores or flexion at three months and one year.
Most of the implant-design studies summarized in this Specialty Update can be summed up as “no difference.” Specifically,
–Three randomized studies attempting to evaluate high-flexion TKA designs (n=74, n=278, and n=122) caused the authors of the update to suggest that “the intention of providing greater clinical flexion through high-flex arthroplasty designs does not translate to a meaningful difference in patient outcomes.”
–A randomized study of 124 patients found no differences in maximal post-TKA flexion or functional scores between a group that received a bicruciate-substituting implant and one that received a standard posterior-stabilized design.
–A randomized trial of 34 patients who received prostheses with either highly cross-linked polyethylene or conventional polyethylene found no differences in wear-particle number, size, or morphology after one year.
–A 4- to 6.5-year follow-up study of 56 patients who received either mobile or fixed bearings during TKA found that the mobile-bearing group had greater mean range of motion, but there were no between-group differences in satisfaction or functional scores.
Instrumentation and Technique
–A randomized study of 47 patients whose surgeons used either customized cutting blocks or traditional instruments found no differences in clinical outcomes or mean component alignment. Moreover, surgeons abandoned customized blocks in 32% of the cases because of malalignment.
–A randomized study of 129 patients whose surgical approach was either medial parapatellar or subvastus, all of whom were managed with minimally invasive techniques, found no differences in pain, narcotic consumption, functional outcomes, and Knee Society Scores at postoperative times ranging from three days to three months.
Postoperative Care and Pain Management
–A trial among 249 post-TKA patients who received either one-to-one physical therapy (PT), group-based PT, or a monitored home program found no difference in outcomes at 10 weeks and one year.
–A randomized study of 160 post-TKA patients investigating the effect of continuous passive motion (CPM) machines led the study authors to conclude that CPM is neither beneficial nor cost-effective.
–A small randomized study of pain-management protocols found that a “multimodal” approach that included peri-articular injection led to less pain, less narcotic use, and higher satisfaction for up to six weeks after surgery than a patient-controlled analgesia approach.
–A three-way randomized pain-management study of 100 patients led study authors to recommend against posterior capsule injections and to conclude that “a sciatic nerve block [for TKA] has a minimal effect on pain control.”
–A three-way randomized study of 120 TKA patients found that those receiving preoperative dexamethasone and ondansetron had less nausea, shorter hospital stays, and used less narcotic medication than those who received ondansetron alone. “Dexamethasone should be part of a comprehensive total joint arthroplasty protocol,” the study authors concluded.