The effect of operative technique on ulnar nerve strain following surgery for cubital tunnel syndrome

Ulnar nerve anteposition with adipofascial flap, an alternative treatment for severe cubital syndrome

BACKGROUND

Ulnar nerve entrapment at the elbow is the second most common cause of nerve entrapment in the upper limb. Surgical techniques mainly include simple decompression, decompression with anterior transposition and medial epicondylectomy.

METHODS

We performed decompression with anterior transposition and protected ulnar nerve by adipofascial flap (a random flap with radial based vascularization, harvested through the avascular plane of Scarpa's fascia. We analyzed patients who underwent ulnar nerve ante-position from 2015 to 2022 according to inclusion and exclusion criteria for a total of 57 patients. All patients included were graded on the McGowan's classification Messina criteria and the British Medical Research Council modified by Mackinnon and Dellon.

RESULTS

The average McGowan's score was 2.4 (± 0.6), Messina's criteria 91.2% indicated a satisfactory or excellent result, sensibility at 6 months was 98.5% S3 or more. A preferential technique has not yet been defined.

CONCLUSIONS

The adipofascial flap offers numerous advantages in providing a pliable, vascular fat envelope, which mimics the natural fatty environment of peripheral nerves and creates favorable micro-environmental conditions to contribute to neural regeneration via axon outgrowth.

Long-term Reoperation Rate for Cubital Tunnel Syndrome: Subcutaneous Transposition Versus In Situ Decompression

Background: The purpose of this study was to compare the long-term revision rate of in situ ulnar nerve decompression with anterior subcutaneous transposition surgery for idiopathic cubital tunnel syndrome. Methods: This retrospective, multicenter, cohort study compared patients who underwent ulnar nerve surgery with a minimum 5 years of follow-up. The primary outcome studied was the need for revision cubital tunnel surgery. In total, there were 132 cases corresponding to 119 patients. The cohorts were matched for age and comorbidity. Results: The long-term reoperation rate for in situ decompression was 25% compared with 12% for anterior subcutaneous transposition. Seventy-eight percent of revisions of in situ decompression were performed within the first 3 years. Younger age and female sex were identified as independent predictors of need for revision. Conclusions: In the long-term follow-up, in situ decompression is seen to have a statistically significant higher reoperation rate compared with subcutaneous transposition.

The effect of injurious compression on the elastic, hyper-elastic and visco-elastic properties of porcine peripheral nerves

The aim of this study was to characterise the viscoelastic and hyper-elastic properties of the ulnar nerve before and after compression has been induced, in order to aid the understanding of how the mechanical properties of nerves are altered during nerve compression, a contributing factor to cubital tunnel syndrome. Ulnar nerves were dissected from porcine legs and tensile tested to 10% strain. The Young's modulus and Yeoh hyper-elastic model were used to evaluate the materials elastic and hyper-elastic properties respectively. Dynamic mechanical analysis (DMA) was used to evaluate the viscoelastic properties over a range of frequencies between 0.5 Hz and 38 Hz. The nerves were then compressed to 40% for 60 s and the same tests were carried out after compression. The nerves were stiffer after compression, the mean Young's modulus before was 0.181 MPa and increased to 0.601 MPa after compression. The mean shear modulus calculated from the Yeoh hyper-elastic model was also higher after compression increasing from 5 kPa to 7 kPa. After compression, these properties had significantly increased (p < 0.05). The DMA results showed that the nerves exhibit frequency dependent viscoelastic behaviour across all tested frequencies. The median values of storage modulus before compression ranged between 0.605 and 0.757 MPa across the frequencies and after compression between 1.161 MPa and 1.381 MPa. There was a larger range of median values for loss modulus, before compression, median values ranged between 0.073 MPa and 0.216 MPa and after compression from 0.165 MPa to 0.410 MPa. There was a significant increase in both storage and loss modulus after compression (p < 0.05). The mechanical properties of the nerve change following compression, however the response to decompression in vivo requires further evaluation to determine whether the observed changes persist, which may have implications for clinical recovery after surgical decompression in entrapment neuropathy.

The impact of pre-existing ulnar nerve instability on the surgical treatment of cubital tunnel syndrome: a systematic review

BACKGROUND

The decision to perform nerve transposition (NT) or in situ decompression (SD) during surgical treatment of cubital tunnel syndrome is often based on nerve subluxation through elbow motion. This review assesses what impact nerve instability has on study design and reported outcomes.

METHODS

A search was performed with Boolean operators: "ulnar nerve" OR "cubital tunnel" AND "decompression" OR "transposition" on PubMed, Clinical Key, and CINAHL to identify primary studies comparing NT and SD that report pre-existing nerve instability. Primary outcome was the effect of instability on study design. Secondary outcomes were nerve instability, patient-reported scores, and complications.

RESULTS

Five studies met criteria after screening 134 articles. In 3 studies, nerve instability dictated treatment. Prospective randomization was maintained in 1 study. Included cases totaled 464 SD and 304 NT. The complication rate was 8.6% overall, 4.3% for SD and 21.1% for NT. Bishop scores were 56.9% excellent and 37.3% good for stable nerves and 62.0% excellent and 29.3% good for unstable nerves.

CONCLUSIONS

Very few studies report ulnar nerve instability, and study design is biased by ulnar nerve subluxation. Outcomes showed similar symptomatic improvement for both decompressed and transposed groups with higher complication rates for the transposed group.

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.

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.

Retrospective, nonrandomized analysis of subcutaneous anterior transposition versus in situ decompression of the ulnar nerve of military service members

HYPOTHESIS

The objective of this study was to compare the subjective and objective midterm functional clinical outcomes of subcutaneous anterior transposition (SAT) vs. in situ decompression (SD) of the ulnar nerve for the treatment of cubital tunnel syndrome.

METHODS

The US Military Health System was queried to identify all cases of ulnar neuroplasty (Current Procedural Terminology code 64718) between 2006 and 2010. Patient charts were reviewed to identify cases of isolated SAT and SD, and demographic and surgical variables were collected. The primary outcome variable was the Disabilities of the Arm, Shoulder and Hand score. The inclusion criteria were isolated primary SAT or SD and adult active-duty service members with a minimum 6-year telephone follow-up. Terminal follow-up was determined by a telephone interview. The exclusion criteria were revision procedures, trauma, cases that included other procedures (eg, medial epicondylectomy, submuscular transposition, arthroscopy, or fracture fixation), non-active-duty service members, patients without a minimum 6-year telephone follow-up, and patients who had incomplete medical records or could not be reached to complete the survey.

RESULTS

A total of 65 SD and 67 SAT patients met the inclusion and exclusion criteria, with a 72% telephone interview response rate. The average age was 32.3 years for all patients, with an average follow-up period of 6.5 years for SD patients and 6.3 years for SAT patients. SD patients had a lower mean Disabilities of the Arm, Shoulder and Hand score than SAT patients. No difference in reoperation rate was found.

CONCLUSION

The active-duty cohort reported positive outcomes and a low reoperation rate at 6-year follow-up both after SAT and after SD. SD patients had mildly superior clinical outcomes compared with SAT patients.

Anterior Subcutaneous Transposition of the Ulnar Nerve Affects Elbow Range of Motion: A Mean 13.5 Years of Follow-up

BACKGROUND

Surgical decompression of the ulnar nerve is effective for cubital tunnel syndrome. However, deep approaches may result in iatrogenic elbow stiffness. This long-term study was to evaluate the range of motion (ROM) of the elbow and functional outcomes after anterior subcutaneous transposition.

METHODS

A total of 115 patients (78 male and 37 female; mean age: 46.6 years) who underwent anterior subcutaneous transposition of the ulnar nerve between 2001 and 2005 were evaluated retrospectively; mean follow-up was 13.5 years. Elbow ROM was measured as flexion arc, flexion, and extension preoperatively and at the final follow-up, and compared via a mixed analysis of variance adjusting for age. Neuropathy was assessed preoperatively using a modified McGowan neuropathy grade and postoperatively using modified Wilson-Krout criteria. An ordinal logistic regression analysis used postoperative modified Wilson-Krout criteria as the outcome and preoperative factors as predictors.

RESULTS

Preoperative McGowan grades were Grade 1 in 14 patients (12.2%), Grade 2A in 28 (24.3%), Grade 2B in 53 (46.1%), and Grade 3 in 20 (17.4%) patients. Postoperatively, 66 patients (57.4%) had excellent results, 26 (22.6%) had good results, 16 (13.9%) had fair results, and 7 (6.1%) had poor results at the final follow-up, as per the Wilson-Krout criteria. There were no complications. Pre- and postoperative elbow ROM was significantly decreased in patients with previous trauma or surgery of the elbow compared with those without (P < 0.05). Anterior subcutaneous transposition of the ulnar nerve did not significantly affect elbow ROM regardless of previous trauma or surgical history nor preoperative ROM (P > 0.05), after adjusting for age. Patients with prolonged symptoms prior to surgery and worse neuropathy tended to have less satisfactory functional outcomes (P < 0.05), after adjusting for covariates.

CONCLUSIONS

Anterior subcutaneous transposition of the ulnar nerve is an effective and reliable treatment of cubital tunnel syndrome with satisfactory outcomes and minimal effect on elbow ROM.

Submuscular Versus Subcutaneous Ulnar Nerve Transposition: A Cadaveric Model Evaluating Their Role in Primary Ulnar Nerve Repair at the Elbow

PURPOSE

To investigate the length gained from subcutaneous and submuscular transposition of the ulnar nerve at the elbow. Specifically, the study aimed to define an expected nerve gap able to be overcome, and to determine if a difference between transposition techniques exists.

METHODS

Eleven cadaveric specimens from the scapula to fingertip were procured. In situ decompression and mobilization of the ulnar nerve at the elbow followed by simulated laceration of the nerve was performed. Nerves were marked 5 mm from the laceration site to facilitate overlap measurement and to simulate nerve end preparation to viable fascicles before primary coaptation. Nerve ends were attached to spring gauges set at 100 g of tension (strain ≤ 10%). Measurements of nerve overlap were obtained in varying degrees of wrist (0°, 30°, 60°) and elbow (0°, 15°, 30°, 45°, 60°, 90°) flexion. Measurements were performed after in situ decompression and mobilization, and then repeated after both subcutaneous and submuscular transposition.

RESULTS

Ulnar nerve transposition was found to increase nerve overlap at an elbow flexion of 30° or greater. No difference was seen between subcutaneous and submuscular transpositions at all wrist and elbow positions. In situ decompression and mobilization alone provided an average of 3.5 cm of length gain with the elbow extended. Transposition in conjunction with clinically feasible wrist and elbow flexion (30° and 60°, respectively) provided 5.2 cm of length gain. Controlling for mobilization, a statistically significant increase in overlap of approximately 2 cm was gained from transposition.

CONCLUSIONS

Although mobilization combined with wrist and elbow flexion may afford substantial gap reduction and should be used initially when approaching proximal ulnar nerve lacerations, transposition should be considered when faced with a large nerve gap greater than 3 cm at the elbow. No difference was seen between submuscular and subcutaneous transposition techniques.

CLINICAL RELEVANCE

This study defines the extent an ulnar nerve gap at the elbow can be overcome by in situ mobilization, joint positioning, and transposition. It additionally compares the efficacy of submuscular and subcutaneous transposition techniques in closing this gap.

Scarcity of Implants Has Partially Replaced Cervical Spondylotic Myelopathy Decompression and Instrumented Fusion with Implant-Less Expansile Cervical Laminoplasty: Poverty Teaches all the Arts

OBJECTIVE

The scarcity of implants during the economic crisis partially has replaced decompression and instrumented fusion for the treatment of cervical spondylotic myelopathy with implant-less expansile cervical laminoplasty (ECL). The aim of the study was to compare the results obtained with instrumented anterior cervical corpectomy and fusion with implant-less ECL.

METHODS

Patients suffering from cervical spondylotic myelopathy Nurick 3-5 with preoperative tethering and postoperative untethering were included. Exclusion criterion was kyphosis more than 10°. Patients were assessed according to 30-meter walking track (30mWT), Nurick, and modified Japanese Orthopaedic Association scale scores. Kinematic magnetic resonance imaging 3-dimensional subaxial spinal cord reconstructions were 3 dimensionally modeled to confirm preoperative pincer clamping and follow-up unclamping to measure subaxial spinal cord length and pia envelope area (PEA).

RESULTS

A total of 35 patients divided in the ECL (n = 19) and the anterior cervical corpectomy and fusion (n = 16) groups were selected from 534 patients operated on between September 1, 2008, and August 31, 2013 as the result of degenerative cervical disorders. Patients improved according to Nurick and modified Japanese Orthopaedic Association scores without differences between groups. Follow-up 30mWT analysis showed greater decrease in steps number and time in ECL group, creating the basis for further imaging analysis. Magnetic resonance imaging analysis showed that spinal cord length (mm) shortened more (4.47 ± 1.87 vs. 1.5 ± 2.5, t = -4.02; P = 0.0003) and PEA (mm²) shrank more (95.58 ± 43.73 vs. 22.94 ± 33.11, t = -5.45, P < 0.0001) in the ECL group. Multivariate logistic analysis showed that Δ 30mWT-time and Δ PEA were a very predictive model when area under the receiver operating characteristic curve is 0.98.

CONCLUSIONS

Our results created a nidus for further research of postdecompression spinal cord relaxation.

Regional Ulnar Nerve Strain Following Decompression and Anterior Subcutaneous Transposition in Patients With Cubital Tunnel Syndrome

PURPOSE

Simple decompression and anterior subcutaneous transposition are effective surgical interventions for cubital tunnel syndrome and yield similarly favorable outcomes. However, a substantial proportion of patients demonstrate unsatisfactory outcomes for reasons that remain unclear. We compared effects of decompression and transposition on regional ulnar nerve strain to better understand the biomechanical impacts of each strategy.

METHODS

Patients diagnosed with cubital tunnel syndrome and scheduled for anterior subcutaneous transposition surgery were enrolled. Simple decompression, circumferential decompression, and anterior transposition of the ulnar nerve were performed during the course of the transposition procedure. Regional ulnar nerve strain around the elbow was measured for each surgical intervention based on 4 wrist and elbow joint configurations.

RESULTS

With elbow extension at 180°, both circumferential decompression and anterior transposition resulted in approximately 68% higher nerve strains than simple decompression. Conversely, with elbow flexion, simple decompression resulted in higher average strains than anterior transposition. Limited regional differences in strain were observed for any surgical intervention with elbow extension. However, with elbow flexion, strains were higher in distal and central regions compared with the proximal region within all surgical groups, and proximal region strain was higher after simple decompression compared with anterior transposition.

CONCLUSIONS

As predicted by the altered anatomic course, anterior transposition results in lower ulnar nerve strains than simple decompression during elbow flexion and higher nerve strains during elbow extension. Irrespective of anatomic course, circumferential release of paraneurial tissues may also influence nerve strain. Nerve strain varies regionally and is influenced by surgery and joint configuration.

CLINICAL RELEVANCE

Our data provide insight into how surgery resolves and redistributes traction on the ulnar nerve. These findings may help inform which surgical procedure to perform for a specific patient, guide rehabilitation protocols, and suggest regions of anatomic concern during index and revision surgery.