The Blocking Flap for Ulnar Nerve Instability After In Situ Release: Technique and a Grading System of Ulnar Nerve Instability to Guide Treatment

A novel classification of intraoperative ulnar nerve instability to aid transposition surgery

HYPOTHESIS

The purpose of this study was to compare inter- and intraobserver agreement of a novel intraoperative subluxation classification for patients undergoing ulnar nerve surgery at the elbow. We hypothesize there will be strong inter- and intraobserver agreement of the 4-category classification system, and reviewers will have substantial confidence while reviewing the classification system.

METHODS

Four blinded fellowship-trained orthopedic hand surgeons reviewed 25 videos in total on 2 separate viewings, 21 days apart. Variables collected were ulnar subluxation classification (A, B, C, or D) and a confidence metric. Subsequent to primary data collection, classification grading was stratified into A/B or C/D subgroups for further analysis. Cohen κ scores were used to evaluate all variables collected in this study. The interpretation of κ scores included ≤0.0 as no agreement, 0.01-0.20 as none to slight, 0.21-0.40 as fair, 0.41-0.60 as moderate, 0.61-0.80 as substantial, and 0.81-1.0 as almost perfect agreement.

RESULTS

Interobserver agreement of subluxation classification as a 4-category scale demonstrated a moderate agreement on first viewing, second viewing, and when both viewings were combined (κ = 0.51, 0.51, and 0.51 respectively). Seventy-five percent (3 of 4) of reviewers had moderate intraobserver agreement for ulnar nerve subluxation classification, whereas 1 reviewer had substantial intraobserver classification (κ = 0.72). Overall, there was high confidence in 65% of classification scores in the second round of viewing, which improved from 58% in the first viewing round. When ulnar subluxation classification selections were regrouped into classes A/B or C/D, 100% of reviewers had substantial interobserver (κ = 0.74-0.75) and substantial to almost perfect intraobserver (κ = 0.71-0.91) agreement.

CONCLUSIONS

The 4-category classification was reproducible within and between reviewers. Agreement appeared to increase when simplifying the classification to 2 categories, which may provide guidance to surgical decision making. The validation of a reproducible classification scheme for intraoperative ulnar subluxation may aid with decision making and further postoperative outcomes research.

In Situ Stabilization of the Ulnar Nerve as an Alternative to Transposition in Traumatic Ulnar Nerve Instability: A Case Report

CASE

We present the case of a 25-year-old male sports climber treated with in situ ulnar nerve stabilization for ulnar nerve instability (UNI) by using 2 fascial flaps.

CONCLUSION

Symptomatic UNI has traditionally been managed with subcutaneous or submuscular ulnar nerve transposition. Transposition is relatively invasive and when performed subcutaneously, embeds the ulnar nerve in an exposed location, which may render it prone to mechanical injury in physically active patients. In situ stabilization may be a less invasive alternative to transposition in select patients involved in sports such as rock climbing.

Nerve entrapment around elbow

Entrapment neuropathy around elbow is a common cause of disability across all age groups. The major nerves that traverse the elbow are ulnar, median and radial nerves and their branches. Cubital tunnel syndrome leading to ulnar nerve compression can often present with significant pain, paresthesia or weakness. Median and Radial nerve compression around the elbow, albeit less frequent, can also lead to significant morbidity and must be kept in the differential diagnosis when dealing with patients complaining of persistent pain around the elbow and weakness of forearm/hand muscles. Electrodiagnostic studies can be a useful adjunct to clinical examination, to help localize the site and quantify the grade of compression. Management should involve a trial of conservative treatment and failing that, surgical treatment should be considered. We hereby provide an overview of nerve entrapments around the elbow including their applied anatomy, etiology, clinical assessment and overview of the current concepts in surgical treatment.

Classification and Treatment of Ulnar Nerve Subluxation Following Endoscopic Cubital Tunnel Release

Purpose

Endoscopic cubital tunnel release (ECuTR) is an effective procedure to alleviate cubital tunnel syndrome. To improve patient outcomes and lessen concerns regarding ulnar nerve subluxation (UNS) after ECuTR, the current study proposes an intraoperative UNS classification system and subsequent treatment protocol. We present a preliminary report of patients treated under these guidelines.

Methods

We retrospectively reviewed 87 patients (100 ECuTRs). Nerve mobility was classified during surgery, in which grade 1 = no movement or partial subluxation; deep retrocondylar groove and/or no generalized hypermobility (no further intervention); grade 2 = partial subluxation; shallow retrocondylar groove and/or inherent generalized hypermobility (required medial epicondylectomy); and grade 3 = complete anterior dislocation (required medial epicondylectomy or anterior transposition). Clinical outcomes at final follow-up (mean ± SD, 34 ± 20.3 weeks; range, 5–89 weeks) were collected and included Disabilities of the Arm, Shoulder, and Hand questionnaires, visual analog scale pain score, grip and pinch strength, 2-point discrimination, and range of motion.

Results

We report 37 patients (42 cases), grade 1 (n = 30), grade 2 (n = 1), and grade 3 (n = 11). Gross grip strength, lateral, 3-jaw chuck, and precision pinch strength recovered 87%, 90%, 105%, and 87%, respectively. Wrist and elbow range of motion returned to normal limits, 2-point discrimination improved to normal scores at final follow-up, Disabilities of the Arm, Shoulder, and Hand scores were reduced from 59.8 before to 29.9 after surgery, and visual analog scale pain score improved from 7.2 before to 2.5 after surgery (P < .001).

Conclusions

To our knowledge, this is the first study to classify UNS after ECuTR and describe a guideline for ensuing treatment. Our preliminary report of patients shows satisfactory outcomes, which suggests that our intraoperative UNS classification system has promise in preventing adverse complications of ulnar nerve hypermobility after ECuTR.

Type of study/level of evidence

Therapeutic IV.

Ulnar nerve subluxation and dislocation: a review of the literature

The pathogenesis of ulnar nerve subluxation and dislocation is widely debated. Upon elbow flexion, the ulnar nerve slips out of the groove for the ulnar nerve, relocates medial or anterior to the medial epicondyle, and returns to its correct anatomical position upon extension. This chronic condition can cause neuritis or neuropathy; however, it has also been suggested that it protects against neuropathy by reducing tension along the nerve. This article reviews the extant literature with the aim of bringing knowledge of the topic into perspective and standardizing terminology.

In idiopathic cubital tunnel syndrome, ulnar nerve excursion and instability can be reduced by repairing Osborne's ligament after simple decompression

Osborne's modified decompression involves repairing Osborne's ligament beneath the ulnar nerve after simple decompression for idiopathic cubital tunnel syndrome. In this retrospective interrupted time series, 31 patients underwent modified simple decompression and 20 patients underwent conventional simple decompression. In the modified simple decompression group, the ulnar nerve length was measured at operation in full elbow flexion and extension before and after repair of Osborne's ligament. Ulnar nerve instability during elbow motion was measured using ultrasonography before operation and at 12 months after operation. In patients treated by modified simple decompression, the ulnar nerve length in full elbow flexion reduced significantly after repair of Osborne's ligament. At 12 months after surgery, the grade of ulnar nerve instability was lower in the modified simple decompression group than in the conventional simple decompression group. The clinical outcomes did not differ significantly between the groups at 24 months after operation. Level of evidence: III.

Intraoperative Subluxation of the Ulnar Nerve: Use of a Triceps Sling Reconstruction Technique

PURPOSE

To determine whether the triceps sling reconstruction technique is a safe and effective treatment of intraoperative ulnar nerve subluxation after in situ decompression.

METHODS

Twelve patients who underwent a triceps sling reconstruction for intraoperative ulnar nerve subluxation after in situ release were retrospectively reviewed. The triceps sling technique consists of harvesting a small, distally based strip of triceps tendon and suturing the proximal end of the strip to the posterior aspect of the released Osborne ligament. Thus, a sling is created between the medial epicondyle and the olecranon, preventing the nerve from subluxating. Patients were clinically evaluated before and after surgery. Visual analog scale pain scores, static 2-point discrimination, strength, and Disabilities of the Arm, Shoulder, and Hand score were assessed.

RESULTS

At a mean follow-up of 31 months (range, 24-38 months), there was a significant improvement in mean visual analog pain scores from 8.6 to 0.2. Static 2-point discrimination was improved from a mean of 9.1 mm before surgery to 5.7 mm afterward. Strength improved by a mean of 33% and 30% with grip and pinch, respectively. Mean Disabilities of the Arm, Shoulder, and Hand score improved from 45.9 to 3.7. No subluxation of the ulnar nerve was noted after surgery. No other complications were noted. No reoperations were required during the follow-up period.

CONCLUSIONS

Triceps sling reconstruction is a safe treatment in patients with intraoperative ulnar nerve subluxation after in situ decompression.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The Triceps Traction Test: A Decision Tool for the Choice of Stabilizing Flap After In Situ Decompression of the Ulnar Nerve

PURPOSE

Recent evidence demonstrates that in situ decompression has comparable outcomes to other surgical techniques for cubital tunnel syndrome. However, this technique does not address the instability of the ulnar nerve, a common indication to transpose the ulnar nerve. Transposition of the ulnar nerve can potentially devascularize the ulnar nerve, stabilizing flaps block subluxation of the ulnar nerve and thereby negate the need for transposition. Flaps originating from the triceps and the flexor-pronator fascia could be used to stabilize the ulnar nerve. Herein, we present a novel intraoperative test, the "triceps traction test" and our algorithm for choosing a stabilizing flap when ulnar nerve instability is encountered after in situ decompression.

Outcomes of ulnar nerve anterior transmuscular transposition and significance of ulnar nerve instability in cubital tunnel syndrome

BACKGROUND

We investigated the experience of a single surgeon with ulnar nerve anterior transmuscular transposition with the patient in the lateral decubitus position for cubital tunnel syndrome.

METHODS

The medical records of all patients who underwent primary or revision ulnar nerve anterior transmuscular transposition were screened to define a cohort of 156 patients (162 limbs) for further study of demographic and disease-specific data and retrospective assessment of short-term outcomes. Ulnar neuropathy severity was stratified by McGowan grade. A prospective cohort composed of 49 patients (51 limbs) with a minimum 2-year follow-up volunteered to complete patient outcome surveys, and some presented for an ulnar nerve-focused examination to assess long-term outcomes.

RESULTS

The overall patient satisfaction rate was 92%, with statistically significant improvements in ulnar sensation and intrinsic strength at short- and long-term follow-up. Outcomes were better for lower McGowan grades than for higher grades and better in primary cases than in revision cases. Ulnar nerve instability was observed in 69 of 162 cases (43%) in this series. A major complication occurred in 7 cases (4.3%), but all were mitigated by contributory patient-related factors. Reoperation for recurrent ulnar paresthesia was required in 4 cases (2.5%). No operations or outcomes were compromised by the lateral decubitus position.

DISCUSSION AND CONCLUSION

Ulnar nerve anterior transmuscular transposition in the lateral decubitus position is a good surgical option for primary or recurrent cubital tunnel syndrome and remains our preferred procedure. The high prevalence of ulnar nerve instability observed in this study is a factor worthy of consideration by surgeons and patients weighing the surgical options for ulnar neuropathy at the elbow.