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Technical Note

Arthroscopic Decompression of a Bony Suprascapular Foramen

Vivek Agrawal, M.D.

Abstract: Arthroscopic decompression of the suprascapular nerve by transection of the trans-verse scapular ligament has only recently been described. Arthroscopic decompression of a bonysuprascapular notch foramen has not been previously reported. This article presents a case report andoutlines an arthroscopic technique to safely decompress a bony suprascapular notch. In the subacro-mial space, a lateral portal is used for viewing and a posterior portal for instrumentation. The medialwall of the subacromial bursa located behind the acromioclavicular joint is debrided with the shaverfacing laterally and superiorly. The posterior acromioclavicular artery is routinely coagulated. Asuperomedial portal is now established using spinal needle localization. A smooth 5.5-mm cannulais placed in this portal and the coracoclavicular ligaments (trapezoid and conoid) are followed to thecoracoid. The smooth cannula serves nicely to sweep and retract the suprascapular artery andassociated fibrofatty tissue from the field of view while allowing instrumentation and visualization ofthe suprascapular notch. The course of the suprascapular nerve and morphology of the notch isconfirmed. A Kerrison punch rongeur, routinely used in spine surgery, is introduced through thesuperomedial portal and a notchplasty is performed safely, allowing decompression of the supras-capular nerve. Key Words: Arthroscopic technique—Shoulder pain—Suprascapular foramen—Suprascapular nerve—Suprascapular notch.

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he suprascapular notch (SSN), located medial to thecoracoid at the anterior and superior border of the

capula, is a potential site of compression of the supra-capular nerve (SN). First described in 1936 by Thom-s,1 it continues to be an often overlooked cause ofhoulder pain and dysfunction. Many etiologies haveeen associated with SN entrapment, including bluntrauma, rotator cuff tear, instability, compressive lesionsuch as ganglion cysts, passage of the suprascapularrtery through the SSN, crutch use, repetitive tractionnjury in athletics, and variations in SSN morphology,ncluding a bony foramen.2 Multiple reports have onlyecently described techniques for minimally invasive re-

From The Shoulder Center, Zionsville, Indiana, U.S.A.The author reports no conflict of interest.Address correspondence and reprint requests to Vivek Agrawal, M.D.,

he Shoulder Center, 10801 N. Michigan Rd., Ste. 100, Zionsville, IN6077, U.S.A. E-mail: DrAgrawal@TheShoulderCenter.com

© 2009 by the Arthroscopy Association of North America

c0749-8063/09/2503-8281$36.00/0doi:10.1016/j.arthro.2008.06.014

Arthroscopy: The Journal of Arthroscopic and Related S

ease of the transverse scapular ligament, further raisingwareness of SN entrapment as an overlooked cause ofhronic shoulder pain.3-6 Arthroscopic decompression ofbony SSN foramen has not been previously reported.e present a case report and outline a technique to

ermit the arthroscopic surgeon to safely address bonytenosis of the SN at the SSN.

SURGICAL TECHNIQUE

A 41-year-old woman was referred to our shoulderlinic with a 7-year history of persistent shoulder painhat started after she jerked her shoulder pulling on aart loaded with books. She had been evaluated byultiple orthopaedic surgeons over the past 7 years

nd had 4 previous shoulder operations without relieff her postinjury pain. Initial examination of the pa-ient at our clinic was significant for posterior anduperior shoulder pain without evidence of cervicalathology, instability, or labrum pathology. Suspi-

ious of occult suprascapular neuropathy, an electro-

325urgery, Vol 25, No 3 (March), 2009: pp 325-328

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326 V. AGRAWAL

iagnostic study of her upper extremity along with anagnetic resonance arthrogram were recommended.he electrodiagnostic study confirmed neuropathy of

he SN at both the SSN and spinoglenoid notchSGN), consistent with a “double crush” phenome-on.7 To further confirm the diagnosis, the patient waseferred for a confirmatory selective SN block. TheN block provided excellent but transient relief of herain. After reviewing the risks, benefits, and optionsor treatment, including our arthroscopic approach toN decompression, she wished to proceed with arthro-copic treatment.

The SN was decompressed at the SGN by transect-ng the spinoglenoid ligament as described bylancher.8 Our approach to visualize the SSN is sim-

lar to the approach described by Lafosse,6 with sev-ral modifications. We use a semilateral decubitusosition for shoulder arthroscopy (Fig 1). The anat-my and vascularity of the subacromial space haseen elegantly described and is helpful in planningpproaches to the SN and medial wall of the subacro-ial bursa.9 After completing glenohumeral evalua-

ion and treatment, the arthroscope is introduced intohe subacromial space via the posterior portal. Annterolateral portal is established for outflow using annside-outside technique, ensuring that both portalsre within the subacromial bursa. A lateral portal withpinal needle localization is used to ensure an optimalngle of approach. An arthroscopic shaver is intro-uced through the lateral portal, and the posterior wall

IGURE 1. Lateral decubitus position with portals for suprascap-lar notch approach outlined. (A, anterior portal; L, lateral portal;, posterior portal; SM, superomedial portal.)

f the subacromial bursa is removed to improve visu- s

lization. The arthroscope is switched to the lateralortal for viewing and the shaver and radiofrequencyevice are introduced from the posterior portal. Theoracoacromial (CA) ligament is visualized and fol-owed medially. The acromioclavicular (AC) joint isocalized but not exposed. The medial wall of theubacromial bursa is now removed to allow access tohe SSN. The posterior AC artery is located immedi-tely posterior to the AC joint and is routinely coag-lated. A modified superomedial (SM) portal is nowstablished under direct visualization using spinal nee-le localization.10 A smooth 5.5-mm cannula is in-roduced, and the shaver and radiofrequency devicere used for further dissection via the SM portal.he CA ligament is followed towards the coracoid.he coracoclavicular ligaments (trapezoid andonoid) are identified. The conoid ligament is visu-lized and followed inferiorly to its attachment tohe coracoid. Frequently, this can be done with aentle sweeping motion along these ligaments. Theoracoid insertion of the transverse scapular liga-ent is seen perpendicular to the coracoid insertion

f the conoid ligament. Use of the shaver and ra-iofrequency device are restricted to the space lat-ral to the medial border of the coracoid to avoidnjury to the suprascapular artery. Blunt dissectionan often proceed inferiorly and medially from theoracoid while maintaining contact with bone, al-owing the SSN, suprascapular artery, and SN to beisualized and safely retracted without directly dis-urbing these structures. The morphology of theSN is now defined (Fig 2). In most cases, the

ransverse scapular ligament is easily transected viahe SM portal using arthroscopic scissors. For aony or stenotic SSN foramen, as in the presentase, a Kerrison punch rongeur is introducedhrough the SM portal to perform a foraminotomy.he superior and lateral walls of the SSN are de-ompressed in a controlled manner.11 Kerrison ron-eurs are routinely used for bone removal in spineurgery and are available in multiple sizes andonfigurations in most facilities. Upon completionf the SSN decompression, a probe is used to con-rm mobility of the SN by lifting it out of the SSN.ostoperatively, the patient reported resolution ofer longstanding posterior and superior shoulderain and was extremely pleased with her outcome.

DISCUSSION

Although the prevalence of suprascapular compres-

ion neuropathy is thought to be rare, its role in

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327DECOMPRESSION OF A BONY SUPRASCAPULAR FORAMEN

houlder pain and dysfunction is probably underap-reciated. The morphology, particularly a stenotic orony notch of the SSN, may be associated with aredilection to suprascapular nerve injury.2 The trans-erse scapular ligament, despite connecting 2 regionsf the same bone, has been shown to have fibrocarti-age entheses, indicating that it experiences both com-ressive and tensile loading.12 Consistent with thesendings, bony bridges at the SSN are also seen morerequently with increasing age.13 Of the 700 speci-ens examined by Edelson,14 11.8% had a completely

r partially ossified transverse scapular ligament. In a

IGURE 2. (A) Right shoulder with bony suprascapular notchoramen. (B) Left shoulder with more commonly encountereduperior transverse scapular ligament. (A, suprascapular artery; N,uprascapular nerve; STSL, superior transverse scapular ligament;SN, suprascapular notch.)

ecent update to the classification proposed by Ren- s

achary et al.,2 Natsis et al.15 examined 423 scapulasnd noted an 8% incidence of a bony foramen (typesV and V).

From May 2007 to May 2008, 2 of the 44 patientseen at our tertiary care shoulder clinic for arthro-copic SN decompression at the SSN had a bony SSNoramen. To establish the diagnosis of suprascapulareuropathy, we request electrodiagnostic studies afterdetailed clinical evaluation to confirm the diagnosis

nd predict an expected outcome for treatment.16 Inur experience, electrodiagnostic studies of the shoul-er girdle are highly variable in diagnostic quality.herefore, a single experienced examiner familiarith the electrodiagnostic criteria for SN pathologyerformed most of the studies.16 For patients withsolated SN lesions, we often use a selective SN blocks a further diagnostic and confirmatory measure be-ore proceeding with arthroscopy.

Several techniques for arthroscopic transverse scapu-ar ligament release along with early clinical results haveeen recently reported.3-6,10 In the preliminary clinicaleries of 10 patients reported by Lafosse et al.,6 nonead SN compression as a result of bony stenosis.owever, he recommended using an arthroscopic burr

o address bony stenosis.6

This technique has several advantages: the SM por-al is a safe distance from the SN and relativelyamiliar to most arthroscopic surgeons.10 The SMortal allows a more direct approach to dissection ofhe deep surface of coracoclavicular ligaments and theSN, and the smooth cannula in this portal servesicely as a soft tissue retractor avoiding the need fornother portal. Kerrison punch rongeurs are specifi-ally designed for decompression of spinal stenosisnd uniquely suited to arthroscopic decompression ofuprascapular nerve stenosis. For our initial case withbony SSN foramen, we started with a burr as sug-

ested by Lafosse; however, given the proximity ofhe neurovascular structures, we felt that the Kerrisonunch offered a greater margin of safety and control.e completed the case with the Kerrison punch and

sed it exclusively for the second patient with a bonySN. The technique is adaptable and appropriate forariations in SSN anatomy.Arthroscopic decompression of the suprascapular

erve with a bony SSN foramen has not been previ-usly reported. This technique provides the arthro-copic surgeon another approach to safely decompresshe suprascapular nerve at the SSN in cases of bony

tenosis using commonly available instruments.

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328 V. AGRAWAL

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