Symptomatic Ulnar Nerve Compression After Biceps-to-Triceps Tendon Transfer for Elbow Extension Reconstruction in Tetraplegia: A Case Report

Abstract

Introduction

Medially routed biceps-to-triceps tendon transfer for elbow extension reconstruction in spinal cord injury (SCI) has proven to be a reliable procedure. This technique classically places the tendon transfer superficial to a paralyzed ulnar nerve, with a theoretical risk of compression neuropathy.

Case presentation

A 21-year-old male with a C5 American Spinal Injury Association Impairment Scale (AIS) grade B SCI who underwent bilateral biceps-to-triceps tendon transfers presented with new-onset paresthesias in the ring and small fingers 10.5 years following initial reconstructive surgery. These symptoms were accompanied by triggered upper extremity spasticity following repeated elbow flexion exercises. Clinical exam findings and ultrasound imaging were consistent with bilateral ulnar nerve compression. Surgical exploration revealed that the ulnar nerve was severely compressed by the tendinous part of the biceps bilaterally. The surgical technique used to decompress the ulnar nerve and perform an anterior transposition without taking down the rerouted biceps tendon is described. The patient demonstrated favorable post-operative outcomes.

Conclusion

Compression of a paralyzed ulnar nerve in a tetraplegic patient after medially routed biceps-to-triceps tendon transfer can present with both classical and/or atypical findings. Although rare, this complication can be managed surgically by anterior transposition of the ulnar nerve without taking down the rerouted biceps tendon. The senior authors have modified their technique and now recommend passing the rerouted biceps tendon deep to the ulnar nerve to avoid compression neuropathy.

Introduction

Regaining arm and hand function has been ranked the top priority by persons with tetraplegia in functions that would improve their quality of life above sexual function, trunk stability, and bowel and bladder function [1]. Elbow extension reconstruction is critical in the tetraplegic population as it allows for an increase in personal workspace, the ability to reach overhead, perform pressure relief maneuvers, and allows for more efficient manual wheelchair propulsion [2]. Active elbow extension also allows for more precise positioning of the hand in space by producing an antagonistic force against elbow flexion, which is important for conducting coordinated movements [3]. For these reasons, elbow extension reconstruction in tetraplegic patients is key to restoring autonomy and a critical component of upper extremity reconstruction.

Elbow extension is commonly achieved via one of two tendon transfer procedures in the spinal cord injury (SCI) population: the deltoid-to-triceps transfer or the biceps-to-triceps transfer [4]. Each method has its advantages and disadvantages with strong advocates for each procedure [4]. The biceps-to-triceps transfer is a well-known reliable surgery that can be used to achieve active antigravity elbow extension [3, 5–7]. The biceps tendon can be rerouted in a medial or lateral direction during tendon transfer. Nowadays, medial routing is more commonly employed to avoid compression of the radial nerve—one of the typically remaining functional peripheral nerves due to its higher segmental innervation. Iatrogenic injury of the radial nerve would lead to loss of wrist extension and any accompanying tenodesis grasp [3, 8]. Medial routing has been achieved by positioning the biceps tendon superficial to the paralyzed ulnar nerve in those requiring elbow extension reconstruction with the theoretical risk of ulnar nerve compression [2–4, 9].

To date, there have been no reported cases of symptomatic ulnar neuropathy following biceps-to-triceps transfer. We present a case of symptomatic delayed bilateral ulnar nerve compression following a medially routed biceps-to-triceps transfer in a C5 American Spinal Injury Association Impairment Scale (AIS) B SCI patient. The surgical technique used to decompress the ulnar nerve with preservation of the tendon transfer is detailed and imaged.

Case presentation

This is a 21-year-old male who sustained a C5 AIS B SCI after being struck by an automobile while riding his bicycle. He was classified as International Classification for Surgery of the Hand in Tetraplegia (ICSHT) group 3 on the right and group 2 on the left. In addition to other procedures being performed to restore hand function, elbow extension was initially reconstructed with bilateral biceps-to-triceps tendon transfers performed by the senior author (S.K.) at 4 years post-SCI. A right-sided biceps-to-triceps tendon rupture initially occurred 3 months postoperatively and was revised with a flexor carpi radialis autograft. Five months later, the right side underwent a secondary revision procedure following stretching of the biceps-to-triceps tendon transfer resulting in a 45° elbow extension lag.

At a follow-up 12 years postoperatively, elbow extension strength reached Medical Research Council (MRC) grade 3+ on the right and 3 on the left. The patient presented with complaints of new onset paresthesias in the ring and small fingers bilaterally which had been present for 18 months (i.e., roughly 10.5 years after initial surgery) consistent with bilateral symptomatic ulnar nerve compression. Presenting symptoms were aggravated following repeated elbow flexion/extension movements, specifically during rowing exercises. In addition, the patient complained of shooting arm pain that repeatedly triggered upper extremity spasticity specifically while rowing. On physical examination, the patient had a positive Tinel sign at both cubital tunnels, no Tinel sign at the level of Guyon’s canal, and no palpable ulnar nerve subluxation at the elbow bilaterally. Sensation was normal in the C8 dermatomal distribution on the right side but absent on the left. Ultrasound imaging only performed on the left was suggestive of ulnar nerve compression at the site of the medially routed biceps tendon as evidenced by an hourglass deformity of the ulnar nerve. No other evident sites of compression were identified via ultrasonography.

Given the clinical diagnosis of compression neuropathy, the decision was made to proceed with bilateral ulnar nerve decompression and anterior transposition away from the rerouted biceps tendon. Prior to surgery, the authors were uncertain if the biceps tendon would have to be detached to decompress the ulnar nerve, and therefore, this decision was relegated to the intraoperative findings.

Upon operative exploration, both tendon transfers were found to be intact and under appropriate tension. The patient’s right arm (revision side) appeared to have a larger tendon mass with more adhesions and scar tissue around the nerve. Bilaterally, the site of compression was noted to be at the level of the biceps myotendinous junction, proximal to the medial epicondyle. Clear kinking of the ulnar nerve during passive elbow flexion was noted bilaterally (Fig. 1, Video 1). The same technique was used for ulnar nerve decompression bilaterally, which was performed as follows. First, tenolysis and circumferential dissection of the biceps-to-triceps tendon transfer was conducted to allow appropriate retraction and mobilization of the tendon/muscle belly unit, as well as exposure of the cubital tunnel region. This was done without compromising the integrity or tension of the tendon transfer. Ulnar nerve decompression and neurolysis were then completed as per standard technique when performing an anterior transposition. The ulnar nerve was transposed anteriorly and secured in a subfascial manner under three loosely approximated fascial flaps (Fig. 2, Video 1). The post-operative course was uneventful.

Fig. 1.

Site of ulnar nerve compression by medially routed biceps tendon (black arrow); passive elbow flexion demonstrating kinking of the ulnar nerve (white arrow).

Fig. 2. Intraoperative markings of fascial flaps used to secure the anteriorly transposed ulnar nerve.

A Radially based rectangular fascial flap (star). B Z-shaped fascial flaps (triangles).

At 7 months follow-up, the previously reported pain and muscle spasms had diminished with some recovery of subjective upper extremity strength potentially related to the reduction in pain. In addition, the patient’s ulnar nerve paresthesias had decreased. There was no change in elbow range of motion or strength and the patient was satisfied with the outcome.

Discussion

The incidence of ulnar nerve entrapment in the SCI population is much greater than that in the general population (i.e., 40% vs. <5%) [10, 11]. Contributing factors associated with this increased incidence are likely similar to those that have been described with carpal tunnel syndrome in SCI patients, such as manual wheelchair propulsion and considerable dependency on residual upper extremity function for activities of daily living, transfers, and weight-shifting maneuvers [12, 13]. Furthermore, diagnosing nerve entrapments in cervical SCI is challenging as patients often present with atypical symptoms, have substantial upper extremity motor deficits, and have sensory changes in the C5-T1 dermatomes [11]. While electrodiagnostic studies have been shown to be more sensitive in identifying peripheral nerve compression syndromes in SCI, much of the published literature has focused on paraplegic and not tetraplegic patients [14–16].

In cases of ulnar neuropathy, the mean time from SCI to diagnosis was 26.2 (SD 16.5, median 26, range 1–53) years in a United Kingdom national study [11]. Six ulnar nerve decompressions were performed in tetraplegic upper extremities, of which 3 (50%) limbs had prior deltoid-to-triceps tendon transfers [11]. In the current case, the patient presented with symptoms of ulnar neuropathy beginning ~10.5 years following bilateral biceps-to-triceps transfers. Factors which presumably contributed to the earlier onset of symptoms in this patient include a history of medially routed biceps-to-triceps tendon transfers compressing the ulnar nerve at the elbow in addition to the patient’s history of regular rowing exercises causing repeated elbow flexion/extension movements.

In 2013, Mughal et al. presented a case of “silent” compression of the ulnar nerve in a patient who underwent medially routed biceps-to-triceps tendon transfer with simultaneous placement of an implantable functional electrical stimulation (FES) system [17]. This clinical entity was termed “silent” as there were no reported symptoms of ulnar nerve compression, however, ulnar neuropathy was eventually detected as ulnar-innervated muscles that stimulated preoperatively were not responding to FES stimulation postoperatively, suggesting an underlying nerve compression. Surgical exploration weeks later revealed that the main culprit was Osborne’s ligament causing compression of the nerve at the elbow [17]. Although the authors stated that the biceps muscle belly slightly distorted the ulnar nerve proximal to the cubital tunnel, they concluded that the tendinous part of the biceps-to-triceps transfer was not causing any compression [17]. Anterior submuscular transposition of the ulnar nerve was performed and subsequently ulnar-innervated muscles regained their ability to respond to FES stimulation [17]. The case presented herein is different in that the patient presented with certain overt signs and symptoms of ulnar neuropathy, present both clinically, and on ultrasound imaging. In other words, the presented patient did not have a “silent” compression neuropathy, as was described by Mughal et al. [17].

Critical features present in this case that must not be overlooked in tetraplegic patients are atypical features such as new onset upper extremity spasms and specific movements triggering augmented upper extremity spasticity. Interestingly, it was also noted that atypical tetraplegia-specific symptoms such as upper extremity spasms had resolved in another tetraplegic patient following carpal tunnel decompression in the United Kingdom cohort [11].

This is the first documented case of symptomatic ulnar neuropathy related to direct compression by a medially routed biceps tendon following a biceps-to-triceps tendon transfer. Previous reports describing surgical techniques for biceps tendon transfer over multiple decades have described passing the tendon superficial to the ulnar nerve [2–4, 9]. Although previously believed not to be a clinically relevant complication of this surgery, ulnar nerve compression seems to be a real clinical entity. This was demonstrated by the resolution of the patient’s symptoms shortly after anterior transposition without necessitating takedown of the tendon transfer. Despite the classic thinking being that patients requiring elbow extension reconstruction have a paralyzed ulnar nerve that cannot cause symptoms, we provide evidence demonstrating that symptomatic ulnar nerve compression is possible. The findings of this study highlight the importance of being wary of this complication, in both acute and delayed presentations. In addition, careful attention should be committed to not overlook new-onset classical as well as atypical symptoms such as increased spasticity. The senior authors have modified their biceps-to-triceps technique, now passing the biceps tendon deep to the ulnar nerve to avoid this potential complication. In the event of ulnar compression neuropathy due to biceps-to-triceps tendon transfer, anterior transposition can be achieved without taking down the medially routed tendon transfer as described, with favorable post-operative results.

Conclusion

Compression of a paralyzed ulnar nerve in a tetraplegic patient after medially routed biceps-to-triceps tendon transfer for elbow extension reconstruction can present with both classical and/or atypical findings. Although rare, this complication can be successfully managed surgically by anterior transposition of the ulnar nerve without taking down the rerouted biceps tendon. To avoid this complication, the senior authors have modified their technique and now recommend passing the rerouted biceps tendon deep to the ulnar nerve to avoid compression neuropathy.

Author contributions

NO: data collection, literature review, manuscript writing, manuscript submission and revisions. VG: study conception, data collection, literature review, manuscript writing. SHK: performed upper extremity reconstructive procedures on the patient. Manuscript editing. DT: performed ulnar nerve decompression and anterior transposition on the patient. Manuscript revisions and editing. EB: performed ulnar nerve decompression and anterior transposition on the patient. Manuscript revisions and editing.

Competing interests

The authors declare no competing interests.

Supplementary information

The online version contains supplementary material available at 10.1038/s41394-024-00689-4.