Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Management-Techniques

The technique and approach of surgical decompression of the suprascapular nerve is dependent on the location of the presumed etiology of the nerve dysfunction. If the pathology is at the suprascapular notch, then the transverse scapular ligament and suprascapular notch may be approached anteriorly, superiorly, or posteriorly.

The anterior approach uses a saber-type incision, just medial to the coracoid. Generally, however, the anterior approach is recommended because of the complexity and risk of this dissection as well as poor visualization. The superior approach is a relatively quick procedure, with minimal morbidity.

The transverse scapular ligament is easily identified using the superior approach and splitting the trapezius in line with its fibers; this approach is more difficult in muscular patients and in those without atrophy of the supraspinatus. Anatomical studies have identified the topographical landmarks for the superior approach.

The transverse scapular ligament is situated 1.3 cm posterior to the posterior clavicular edge, 2.9 cm medial to the acromioclavicular joint, and 4 cm below the skin. The trapezius is elevated from the spine of the scapula and separated from the supraspinatus with the posterior approach. Alternatively, the trapezius may be split in line, with its fibers superior to the scapular spine, to avoid trapezial detachment.

Splitting the trapezius muscle posteriorly risks injury to the spinal accessory nerve. The senior author prefers trapezius muscle elevation from the scapular spine when a posterior approach is indicated; using the posterior approach, the transverse scapular ligament and ganglion are easily identified.

Regardless of the approach that is used, the principles of suprascapular nerve decompression with or without cyst excision are the same. Initially, the transverse scapular ligament is cut, taking care to protect vascular structures that rest on the ligament. Sectioning of the transverse scapular ligament should occur at its medial insertion to minimize the risk of injury to the suprascapular nerve and vessels that are positioned more laterally on the ligament and taking care to protect the superficial artery.

The suprascapular notch can be narrow or sharp (“V”-shaped) because of development or trauma. When the notch is narrow, a notchplasty can be performed by resecting the medial notch wall using Kerrison rongeurs, a burr, and/or curette. If a notchplasty is required, the surgeon should smooth the cut bony edges of the notch with bone wax. Recently, endoscopic division of the transverse scapular ligament, decompressing the suprascapular nerve, has been suggested and discussed.

If the nerve is compressed at the spinoglenoid notch, then the posterior surgical approach is used. Frequently, the spinoglenoid ligament can be exposed just by retracting the deltoid and elevating the infraspinatus. Some surgeons recommend partial deltoid detachment from the scapular spine to enhance visualization. Once the infraspinatus is elevated, the spinoglenoid ligament is identified and sectioned.

Frequently, a notchplasty is performed with a burr when the etiology is felt to be traction of the nerve or tethering at the base of the spine of the scapula, but this is somewhat controversial. Occasionally, a Kerrison rongeur or curette may be useful to assist in performing the notchplasty. Following the notchplasty, the surgeon needs to be sure the raw edge of bone is smoothed, using bone wax to reduce friction to and scarring of the nerve.

It is the philosophy of some surgeons to release the transverse scapular ligament in conjunction with posterior release, even if the physical examination and EMG findings suggest that the offending area of compression is at the spinoglenoid notch. The logic behind this approach is to address potential double-crush situations. Both ligaments can be cut through the same posterior approach, but the trapezius must be detached from the spine of the scapula to reach the transverse scapular ligament.

To detach and reattach the trapezius to get to the transverse scapular ligament requires an increased length of postoperative immobilization and carries the potential for increased morbidity. Endoscopic visualization and sectioning of the spinoglenoid ligament have been discussed recently, but to our knowledge, no studies have been published.

Assessment of the results of surgery is difficult, because most published series are small and retrospective, with only short-term follow up and no control group. Assessment is further complicated by the lack of natural history studies for comparison. One complicating factor is the difficulty of knowing how long after the onset of suprascapular nerve injury the patient presents; another is difficulty quantifying the degree of atrophy at presentation, producing difficulty in measuring postoperative change.

Anecdotally, following surgery, most patients note immediate relief of the pain that they felt preoperatively. In most cases, surgical decompression of the nerve generally does not help with regeneration of the nerve or with resolution of the atrophy.

Following surgery, muscular strengthening exercises should be performed to restore balance to the rotator cuff musculature. With appropriate rehabilitation, muscle function can be maximized to provide the balance needed for overhead sports.

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