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Corresponding author: Shiro Yoshida, MD, PhD, Christine M. Kleinert Institute for Hand and Microsurgery, 225 Abraham Flexner Way, Suite 850, Louisville, KY 40202.
To assess the outcomes of double fascial flap stabilization in managing ulnar nerve subluxation after a simple decompression procedure for cubital tunnel syndrome.
Methods
We conducted a retrospective review of 20 patients who experienced ulnar nerve subluxation after simple decompression and were treated with double fascial flap stabilization between 2016 and 2018. Fascial flaps were harvested from the flexor carpi ulnaris and the septum between the triceps and biceps. Patients were classified using McGowan criteria and outcomes were measured using the visual analog scale, grip strength, and the criteria of Messina and Messina for recovery. In addition, we assessed ulnar nerve instability after in situ decompression in 10 fresh cadavers. Tang’s grading and measuring system was used to measure ulnar instability.
Results
There were 13 excellent and 7 good outcomes (65% and 35%, respectively). Mean follow-up duration was 9.1 months (range, 3–23 months). Mean visual analog scale scores improved significantly from 5.8 before to 1.3 after surgery. Mean Quick–Disabilities of the Arm, Shoulder, and Hand scores improved significantly from 37.9 before to 10.9 after surgery. Mean grip strength compared with the contralateral side improved significantly from 73.9% before to 89.6% after surgery. Anatomic cadaveric dissection revealed that 6 of 10 cadavers (60%) met the criterion of moderate to severe ulnar nerve instability.
Conclusions
Double fascial flap stabilization with simple decompression resulted in excellent short-term clinical results. This technique provides an alternative strategy to prevent ulnar nerve instability with the advantage of preserving nerve vascularity. Long-term follow-up is required to evaluate the potential impact on recurrence or failure of simple decompression.
Multiple studies have indicated in situ release to be as effective as other treatments, with the advantage of limited dissection and less nerve devascularization.
Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: part 1.
However, reports on the management of ulnar nerve subluxation with in situ decompression are limited. When subluxation is noted, ulnar nerve transposition is generally recommended.
In addition, regarding the recurrence of CubTS, ulnar nerve instability is common after simple decompression. Postoperative dislocation of the ulnar nerve potentially causes recurrence of CubTS as a result of the release of the Osborne ligament
We hypothesized that simple decompression with in situ stabilization would preserve nerve vascularity while preventing subluxation or CubTS recurrence. The purpose of this study was to evaluate the clinical outcomes of a double fascial flap stabilization technique for managing ulnar nerve subluxation after simple decompression. In addition, we sought to determine the relation between nerve subluxation and dislocation in a cadaveric model.
Materials and Methods
After we obtained approval from our institutional review board, a senior surgeon performed a retrospective review of CubTS surgery from 2016 to 2018. A total of 201 patients underwent simple decompression for CubTS. Double fascial flap stabilization was indicated rather than anterior transposition if the ulnar nerve was found to be unstable during surgery. Exclusion criteria included a history of trauma, elbow arthritis, or less than 3 months’ follow-up. All patients were diagnosed clinically with CubTS and were treated with double fascial flap stabilization for the unstable nerve after an in situ release (Table 1). Nerve conduction studies and electromyography were routinely ordered, but 2 patients underwent surgery without nerve conduction studies and electromyography owing to aggravating symptoms after conservative treatment. All patients were evaluated before and after surgery using the visual analog scale (VAS) score, grip strength, and Quick–Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and were classified based on McGowan’s classification
In this evaluation, excellent scores indicate complete resolution of symptoms; good scores indicate a general resolution of symptoms but with mild residual decreased sensibility and residual motor weakness; fair scores indicate improvement after surgery but with persistent residual sensory changes, motor loss, and muscle wasting; and poor scores indicate no improvement or worsening of the condition after surgery.
We performed statistical analysis using Student t test to compare pre- and postoperative VAS, QuickDASH, and grip strength scores. P values less than .05 were considered statically significant. In addition, we assessed instability and subluxation of the ulnar nerve in elbow extension and flexion after in situ decompression in 10 fresh cadavers. Tang’s
grading and measuring system was used to measure ulnar instability (Table 3). Nerve instability was measured by a single fellowship-trained hand surgeon to determine how much the medial edge of the nerve translated past the sagittal plane of the most medial aspect of the medial epicondyle and how much the anteromedial edge of the nerve translated past the coronal plane of the most posterior aspect of the medial epicondyle (Fig. 1). Less than 2 mm subluxation was considered grade 1; grade 2 was defined as 2 mm subluxation or greater. Grade 3 was gross instability of the nerve, defined as nerve dislocation out of the retrocondylar groove. Double fascial flap stabilization was then performed for positive specimens and ulnar nerve stability was checked.
Table 3Grading System of Ulnar Nerve Instability by Tang
Figure 1Posterior picture of left ulnar nerve release demonstrating medial translation of the nerve. The ulnar nerve is located just below the ruler and shows it breaking the sagittal plane of the most medial aspect of the medial epicondyle in the elbow flexion position: that is, the nerve is subluxing medial to the epicondyle. Because the subluxation is greater than 2 mm, this is grade 2 instability. The blue dot in this picture is the most medial–posterior aspect of the medial epicondyle. The white dot is the edge of the ulnar nerve.
After general or regional anesthesia, the patient is positioned supine with the upper extremity centered on an arm table. A sterile tourniquet is used, allowing placement high in the axilla or 10 cm proximal to the medial epicondyle to allow decompression of the arcade of Struthers. The procedure is carried out under loupe magnification and tourniquet control. The first surgical step of the procedure consists of in situ decompression of the ulnar nerve. An 8-cm incision is made centered over the cubital tunnel (Fig. 2A). Within the deep subcutaneous layer, branches of the medial antebrachial cutaneous nerve are identified and gently protected 1.5 cm proximal and 3.5 cm distal to the medial epicondyle. The nerve is then decompressed proximal to distal along the length of the cubital tunnel. Once the nerve is completely released, the elbow is flexed to evaluate for ulnar nerve instability. If the nerve is subluxating over the medial epicondyle, the fascial flap stabilization technique is indicated.
Figure 2A With the elbow flexed at 90°, an 8-cm incision is made over the ulnar nerve, centered over the cubital tunnel. B The double fascial flaps, shown as rectangles measuring 5 cm long and 2 cm wide, based on the medial epicondyle (M), are designed on the flexor carpal ulnaris fascia and the septum between triceps and biceps muscles. C The double flaps have been raised from the muscle and septum. D The flaps have been sutured to the medial side of the triceps fascia with the elbow in full flexion. The elevator showed enough loose tension of the double fascial flaps.
Fascial flaps are then designed as rectangles 5 cm long and 2 cm wide. There are 2 reasons for this size. First, an adequate fascial flap size is needed to avoid causing a site of compression; if the flap is smaller, new compression can develop. Second, if the flap is too large, the donor muscle can be exposed and bleed. We attempted to avoid unnecessary exposure. The distal flap is elevated from the flexor carpi ulnaris fascia based on the medial epicondyle. The proximal flap is elevated from the septum and fascia between the triceps and biceps muscle and is based on the superior medial epicondyle. The flaps are then transposed posteriorly and secured to the medial triceps with 3.0 monofilament synthetic absorbable surgical suture to stabilize the ulnar nerve. It is important for the elbow to be in full flexion when securing the fascial flaps (Fig. 2B–D). Elbow flexion and extension are then repeated several times to assess flap tension and stability and confirm whether there is sufficient space for ulnar nerve gliding to avoid re-compression. Once verified, routine closure is performed and a soft tissue dressing without an orthosis is applied. After surgery, patients are allowed to use the arm for activities of daily living, but heavy lifting is restricted for 3 weeks.
Results
After surgery, 13 patients had excellent clinical outcomes (65%) and 7 patients had good ones (35%), as defined by the modified criteria of Messina and Messina.
Mean follow-up was 9.1 months (range, 3–23 months). Mean VAS scores improved significantly from 5.8 before to 1.3 after surgery (P < .001). Mean grip strength measurements compared with the contralateral side improved from 73.9% before to 89.6% after surgery (P < .04). Average preoperative and postoperative QuickDASH scores were 37.9 and 10.9, respectively (P < .001). One patient developed chronic regional pain syndrome; the patient recovered with nonsurgical treatment and improved sufficiently to have a good outcome according to the criteria of Messina and Messina 1 year after surgery. No recurrence or nerve dislocation was noted after surgery in this series.
Cadaveric study included in situ ulnar nerve decompression follow-up by assessment through passive range of motion. Results revealed that 6 of 10 specimens (60%) were defined as having moderate to severe instability according to the Tang
grading system. All specimens noted to have instability were managed with double fascial flap stabilization and were observed to be stable after the procedure (Table 4).
Table 4Grading of Ulnar Nerve Instability of Cadavers
Simple decompression of the ulnar nerve is widely performed because of its simple operative technique and fewer complications compared with transposition.
Most independent studies suggested that outcomes with simple decompression are equivalent to those with transposition. Because of the higher complication rate with transposition, many clinicians advocate simple decompression.
Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: part 1.
A recent Cochrane review and meta-analysis comparing simple decompression with anterior transposition supported this finding and found no significant difference in efficacy and a lower complication rate after simple decompression.
Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: part 1.
Anterior transposition with an unstable ulnar nerve was previously the operation of choice at our institution; however, the senior author has found more severe and frequent complications with this method than with simple decompression. Complications included compressive symptoms with elbow extension, recurrent subluxation, and persistent CubTS with kinking noted both proximally and distally upon reexploration. These potential complications can occur when moving the ulnar nerve away from its natural bed.
We hypothesized that simple decompression provides ulnar nerve mobility but promotes instability. Our assessment of the cadavers supported this hypothesis; we found that over half of patients treated with simple decompression required some form of stabilization or transposition as a result of decompression. This may explain the recurrence of CubTS after simple decompression.
However, the true relation between nerve subluxation with dislocation and the clinical outcome of decompression is unknown.
In an effort to address subluxation, we implemented the double fascial flap stabilization technique, which provided satisfactory results as shown. Similar attempts have been reported in which the fascia of the flexor pronator was used to stabilize the ulnar nerve.
Our concept is similar, with the advantage of 2 flaps dispersing tension over a wider area rather than a single pivot point, which may promote recurrent compression. This technique provides a less invasive alternative that does not disturb the nerve blood supply compared with anterior transposition.
This study had some limitations. First, the average follow-up was only 9.1 months; therefore, later-presenting complications such as recurrence may develop. For this reason, long-term follow-up must be carefully considered. Second, nerve conduction studies and electromyography were not performed in 2 patients, causing potential patient bias. Third, we did not compare isolated simple decompression with double fascial flap stabilization. However, the purpose of this study was to demonstrate an alternative to anterior transposition in the management of ulnar nerve instability after in situ decompression to determine whether the ulnar nerve was unstable during surgery. Fourth, postoperative ultrasound evaluation was not performed in this study. We attempted to check nerve stability clinically; no dislocation was identified. However, accurate evaluation techniques must be considered. Finally, a single fellowship-trained hand surgeon performed manual measurement in this cadaveric study. Digital imaging must be carefully considered for more accurate measurement.
We believe that double fascial flap stabilization with simple decompression technique provides a viable alternative to anterior transposition for intraoperative ulnar nerve subluxation after simple decompression. This limits unnecessary dissection and associated increased complications and risk for nerve injury. Further randomized trials and long-term follow-up are required to evaluate its potential impact on recurrence or failure after simple decompression for CubTS.
Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: part 1.
Declaration of interests: No benefits in any form have been received or will be received by the authors related directly or indirectly to the subject of this article.
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