A Novel Hydrogel for Treatment and Prevention of Symptomatic Neuroma: Early Clinical Experience

Abstract

Background: Symptomatic neuroma is a debilitating complication of peripheral nerve injury. Techniques like targeted muscle reinnervation and regenerative peripheral nerve interfaces have shown promise but have critical limitations, including inconsistent efficacy, increased operative time and morbidity, and the need for microsurgical training specific to peripheral nerves. We present the first clinical experience with a sutureless, bioresorbable hydrogel (allay Nerve Cap) for the treatment and prevention of symptomatic neuroma.

Methods: A single-center retrospective review of 11 patients who underwent 12 nerve procedures (23 nerves) involving hydrogel nerve cap placement was conducted. Ten of the 12 procedures were prophylactic, and 2 were for established diagnosis of symptomatic neuroma. In the symptomatic neuroma group, pre- and postoperative visual analog scale scores were obtained. All patients had a minimum 6 months of follow-up and were monitored for the development of neuropathic symptoms. The time required for intraoperative nerve hydrogel application was recorded.

Results: No patients in the prophylactic group developed symptomatic neuromas or neuropathic symptoms postoperatively. Both patients with established symptomatic neuroma experienced a significant decrease in visual analog scale score (4 and 7 points, respectively). There were no hydrogel-related complications. Minor wound issues occurred in 3 patients, and 1 patient died approximately 6 months postoperatively due to her underlying medical condition. The duration of hydrogel application averaged 55 seconds per nerve.

Conclusions: Early experience with the hydrogel cap suggests it is a safe, effective, and scalable device for prevention and treatment of symptomatic neuroma across a broad range of procedures and anatomical locations.

Fig. 1.

Case 1. A, Full-thickness skin necrosis and synergistic gangrene following open reduction and internal fixation of right lower extremity fractures. B and C, Hydrogel nerve caps were applied to the tibial nerve, superficial peroneal nerve, and deep peroneal nerve at the time of below-knee amputation.

Fig. 2.

Case 2. Sciatic nerve at the time of conversion from below-knee to above-knee amputation. The sciatic nerve was split into 4 fascicles (A), and each was individually capped with hydrogel nerve caps along with the saphenous nerve (B).

Fig. 3.

Case 5: Radial-to-median sensory nerve transfers in a 76-year-old woman with chronic and severe left median neuropathy. A, Sensory nerve transfers were performed by transferring the proper digital nerves of the index finger and thumb to the sensory branches of the radial nerve at the proximal phalangeal level. B, Hydrogel nerve caps were applied to the transected proximal stumps of the proper digital nerves to the thumb and index finger.

Fig. 4.

Case 10. A, Preoperative markings showing the location of the Tinel sign marked with an “X”. B, A cutaneous branch of the superior cluneal nerve was identified precisely at the location of the preoperatively marked Tinel sign. C, The cluneal nerve was dissected proximally, and the deep fascia was released, where it split into 2 separate nerves that were treated with neurectomy. D, Hydrogel nerve caps were applied to the stumps of both nerves.

Fig. 5.

Case 11. A, A 17-year-old right-handed high school football quarterback had a powerful firework detonate in his right hand, requiring repeat debridement, provisional fixation, and eventual removal of metacarpals 3–5 due to persistent Enterobacter cloacae complex infection. B, An anterolateral thigh flap was harvested from the right thigh, including a branch of the lateral femoral cutaneous nerve, which was neurotized to the volar sensory branch of the ulnar nerve at the time of flap transfer. C and D, He subsequently developed a painful median nerve neuroma of the second and third web space branches and returned to the OR 5 months postoperatively for allograft reconstruction of digital nerves, Z-plasties, capsulotomies, tenolysis, and excision of large second and third web space branch neuromas followed by capping with hydrogel nerve caps.

Fig. 6.

Case 12. Osteomyelitis of the right long finger. Digital amputation was performed to the level of the proximal phalanx; however, traction neurectomy was deliberately not performed, intentionally leaving long digital nerve stumps (A). Nerve hydrogels were applied to the digital nerve stumps without traction neurectomy, and the skin was closed directly over the hydrogels (B).