Suprascapular neuropathy in the setting of rotator cuff tears: study protocol for a double-blinded randomized controlled trial

Does suprascapular nerve release provide additional benefits for rotator cuff repair: a systematic review and meta-analysis

BACKGROUND

There is still a lack of consensus regarding whether suprascapular nerve decompression should be routinely performed with rotator cuff repair. Therefore, this meta-analysis aimed to evaluate whether additional suprascapular nerve release (SSNR) could improve shoulder functional outcomes and pain relief more than rotator cuff repair alone.

MATERIALS AND METHODS

We performed a literature review of electronic databases for noncomparative and comparative studies investigating the effect of SSNR in patients undergoing rotator cuff repair. The primary outcome was the change in shoulder function scores from the preoperative status, and the secondary outcome was the change in the visual analog scale (VAS) score of pain after surgery. A subgroup analysis was conducted based on the study design (noncomparative studies vs. comparative studies).

RESULTS

Nine studies comprising 279 participants were included. Our analysis demonstrated that the group that underwent SSNR had a better shoulder functional score after surgery than at preoperative assessment (standardized mean difference [SMD], 1.333, 95% confidence interval [CI], 0.708-1.959). No significant differences were identified in shoulder function improvement between those with and without SSNR, with an SMD of 0.163 (95% CI, -0.091 to 0.418). Likewise, the group with SSNR showed a decreased VAS score after surgery compared to their preoperative status (SMD, 0.910; 95% CI, 0.560-1.260). However, there was no significant difference in VAS change between those with and without SSNR, with an SMD of 0.431 (95% CI, -0.095 to 0.956).

CONCLUSION

The present meta-analysis revealed that SSNR might not be routinely needed in rotator cuff tendon repair as no additional benefits in functional improvement or pain relief were identified compared to rotator cuff tendon repair alone.

Outcomes of Arthroscopic Nerve Release in Patients Treated for Large or Massive Rotator Cuff Tears and Associated Suprascapular Neuropathy: A Prospective, Randomized, Double-Blinded Clinical Trial

BACKGROUND

Suprascapular neuropathy has been observed in the setting of rotator cuff tears (RCTs), but its association with these tears and their treatment are unclear.

HYPOTHESIS

Arthroscopic suprascapular nerve release during rotator cuff repair will not alter the outcomes of neuropathy.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 42 patients with large/massive reparable RCTs and suprascapular neuropathy were recruited and followed up at 6 and 12 months. Electrophysiological results as well as Disabilities of the Arm, Shoulder and Hand (DASH), American Shoulder and Elbow Surgeons (ASES), and Constant scores were evaluated at selected time periods. Patients were randomly assigned to 2 groups. Patients in the control group underwent arthroscopic repair of the rotator cuff without combined arthroscopic release of the superior transverse scapular ligament; in the second group, the superior transverse ligament was released. The primary outcome was to examine full suprascapular nerve recovery through electrophysiological changes between groups. The secondary/tertiary outcomes were analysis of clinical outcomes and assessment of the relation between RCT size and the degree of suprascapular nerve recovery. Patients, clinical staff members, and the neurologist were blinded to the type of surgical procedure.

RESULTS

Of 42 patients, 37 completed the follow-up at 12 months (median age, 64 years [range, 50-75 years]). Overall, 17 of 19 (89.5%) patients in the control group and 15 of 18 (83.3%) patients in the nerve release group had full nerve recovery, with no significant difference between the 2 groups. Clinically, all patients in both groups showed a significant improvement (P < .001), but no significant difference was observed between the 2 groups in terms of 12-month postoperative scores (control group: DASH: median, 5 [range, 0-21]; ASES: median, 88 [range, 83-98]; Constant: median, 86 [range, 70-98]) (nerve release group: DASH: median, 6 [range, 0-25]; ASES: median, 90 [range, 83-98]; Constant: median, 88 [range, 75-98]). Also, no significant difference was found between the 2 groups regarding other secondary and tertiary outcomes.

CONCLUSION

Combined arthroscopic release of the superior transverse scapular ligament and rotator cuff repair in patients with large/massive RCTs and suprascapular neuropathy did not produce statistically significant improved outcomes compared with repair of the rotator cuff alone.

REGISTRATION

NCT02318381 (ClinicalTrials.gov identifier).

Comparison of clinical outcome of decompression of suprascapular nerve at spinoglenoid notch for patients with posterosuperior massive rotator cuff tears and suprascapular neuropathy

PURPOSE

In the present study, we aimed to determine whether decompression of suprascapular nerve (SSN) at the spinoglenoid notch could lead to a better functional outcome for the patients who underwent repairment of rotator cuff due to posterosupeior massive rotator cuff tear (MRCT) and suprascapular neuropathy.

METHODS

A total of 20 patients with posterosuperior MRCT and suprascapular neuropathy were analyzed in the present work. The preoperative magnetic resonance imaging (MRI) showed rotator cuff tear in supraspinatus and infraspinatus. All patients underwent arthroscopic rotator cuff repair. Patients were divided into two groups (group A: non-releasing, group B: releasing) according to whether the SSN at the spinoglenoid notch was decompressed. The modified University of California at Los Angeles shoulder rating scale (UCLA) and visual analog scale (VAS) questionnaire were adopted to assess the function of the affected shoulder preoperatively and 12 months after the operation. Electromyography (EMG) and nerve conduction study (NCS) were used to evaluate the nerve condition. Patients underwent MRI and EMG/NCS at 6 months after operation and last follow-up.

RESULTS

All patients were satisfied with the treatment. MRI showed that it was well-healed in 19 patients at 6 months after the operation. However, the fatty infiltration of supraspinatus and infraspinatus was not reversed. Only one patient in the non-releasing group showed the retear. The retear rate of group A and group B were 30% (3/10) and 20% (2/10) respectively at 12 months after the operation. One patient undergoing SSN decompression complained of discomfort in the infraspinatus area. His follow-up EMG after 6 months showed fibrillation potentials (1+) and positive sharp waves (1+) in the infraspinatus. The other patients' EMG results showed no abnormality. The postoperative UCLA and VAS scores were improved in both groups, and there was no significant difference in the follow-up outcomes between the two groups.

CONCLUSIONS

Patients with postersuperior MRCT and suprascapular neuropathy, decompression of suprascapular nerve at spinoglenoid notch didn't lead to a better functional outcome with the repairment of rotator cuff. Arthroscopic rotator cuff repair could reverse the suprascapular neuropathy.

LEVEL OF EVIDENCE

Level III.

Suprascapular nerve injury affects rotator cuff healing: A paired controlled study in a rat model

Purpose

We designed a paired controlled study to investigate the role of the suprascapular nerve (SSN) in rotator cuff healing using a rat tear model, and we hypothesised that rotator cuff healing is impaired in the absence of a healthy SSN.

Methods

Bilateral supraspinatus tenotomy from the great tuberosity was performed for 36 Wistar rats, which was then repaired immediately. A defect on the SSN was made on the right side, and a sham surgery was performed on the SSN at the left side. Twelve rats were sacrificed for biomechanical (six rats) and histological (six rats) testing, evaluated at 3, 6, and 9 weeks after surgery.

Results

The bone–tendon junction on the nerve-intact side showed significantly better biomechanical characteristics than the nerve-injured side in terms of maximum load, maximum stress over time, stiffness at 9 weeks, and Young's modulus at 3 and 9 weeks. On the nerve-injured side, significantly smaller fibrocartilage layers and muscle fibres could be obtained over time. In addition, on the nerve-injured side, inferior bone–tendon interface formation was obtained in terms of cell maturity, cell alignment, collagen orientation, and the occurrence of tidemark and Sharpey's fibres through 9 weeks. In addition, neuropeptide Y was secreted in the nerve-intact group at 6 and 9 weeks.

Conclusion

This study showed the inferior healing of the bone–tendon junction on the nerve-injured side compared with the nerve-intact side, which indicates that the SSN plays an important role in rotator cuff healing. Surgeons should pay more attention to SSN injury when treating patients with rotator cuff tear.

Reversal of Fatty Infiltration After Suprascapular Nerve Compression Release Is Dependent on UCP1 Expression in Mice

BACKGROUND

In large rotator cuff tears, retraction of the supraspinatus muscle creates suprascapular nerve traction and compression. However, suprascapular nerve transection, when used in previous models, is different from chronic compression of the suprascapular nerve in patients. To define the role of suprascapular nerve chronic injury in rotator cuff muscle atrophy and fatty infiltration, we developed a novel reversible suprascapular nerve compression mouse model.

QUESTIONS/PURPOSES

We asked: (1) Can suprascapular nerve injury be induced by compression but reversed after compression release? (2) Can muscle fatty infiltration be induced by suprascapular nerve compression and reversed after compression release? (3) Is white fat browning involved in fatty infiltration resorption?

METHODS

Mice in a common strain of C57BL/6J were randomly assigned to suprascapular nerve transection (n = 10), nerve compression (n = 10), nerve compression and release (n = 10), or sham control (n = 10) groups. To study the role or white fat browning on muscle fatty infiltration, additional UCP1 reporter mice (n = 4 for nerve compression and n = 4 for nerve compression release) and knockout mice (n = 4 for nerve compression and n = 4 for nerve compression release) were used. Nerve injury was testified using osmium tetroxide staining and neural muscular junction staining and then semiquantified by counting the degenerating axons and disrupted junctions. Muscle fatty infiltration was evaluated using Oil Red O staining and then semiquantified by measuring the area fraction of fat. Immunofluorescent and Oil Red O staining on UCP1 transgenic mice was conducted to testify whether white fat browning was involved in fatty infiltration resorption. Ratios of UCP1 positively stained area and fat area to muscle cross-section area were measured to semiquantify UCP1 expression and fatty infiltration in muscle by blinded reviewers. Analysis of variance with Tukey post hoc comparisons was used for statistical analysis between groups.

RESULTS

Suprascapular nerve injury was induced by compression but reversed after release. The ratios of degenerating axons were: sham control: 6% ± 3% (95% confidence interval [CI], 3%-10%); nerve compression: 58% ± 10% (95% CI, 45%-70% versus sham, p < 0.001); and nerve compression and release: 15% ± 9% (95% CI, 5%-26% versus sham, p = 0.050). The supraspinatus muscle percentage area of fatty infiltration increased after 6 weeks of nerve compression (19% ± 1%; 95% CI, 18%-20%; p < 0.001) but showed no difference after compression release for 6 weeks (5% ± 3%; 95% CI, 1%-10%; p = 0.054) compared with sham (2% ± 1%; 95% CI, 1%-3%). However, the fat area fraction in UCP1 knockout mice did not change after nerve compression release (6% ± 1%; 95% CI, 4%-8% at 2 weeks after compression and 5% ± 0.32%; 95% CI, 4%-6% after 2 weeks of release; p = 0.1095).

CONCLUSIONS

We developed a clinically relevant, reversible suprascapular nerve compression mouse model. Fatty infiltration resorption after compression release was mediated through white fat browning.

CLINICAL RELEVANCE

If the mechanism of browning of white fat in rotator cuff muscle fatty infiltration can be confirmed in humans, a UCP1 agonist may be an effective treatment for patients with suprascapular nerve injury.