The suprascapular notch (SSN) is the typical site of compression and injury of the suprascapular nerve (SN), which results in a neuropathy known as suprascapular nerve entrapment. The SSN is enclosed from the top by the superior traverse scapular ligament (STSL), creating a tunnel for the SN. On the both sides of the suprascapular notch, below the STSL, the anterior coracoscapular ligament (ACSL) is found. This fibrous band can potentially narrow the opening and contribute to the occurrence of suprascapular entrapment syndrome. This study presents a first case of a bifid anterior coracoscapular ligament coexisting with atypical suprascapular nerve course that has never been described in the literature. Knowledge of such anatomical variations can be helpful in arthroscopic and open procedures of the suprascapular region and confirms the safety of operative decompression for entrapment of the suprascapular nerve

Jędrzejewski, K.

Polguj, M.

Topol, M.

English

Via Medica Journals

Folia Morphol. Vol. 71, No. 4, pp. 282–284Copyright © 2012 Via MedicaISSN 0015–5659www.fm.viamedica.plC A S E   R E P O R T282Address for correspondence: M. Polguj, Department of Angiology, Chair of Anatomy, Medical University of Lodz, ul. Narutowicza 60,90–136 Łódź, Poland, e-mail: michal.polguj@umed.lodz.plThe bifid anterior coracoscapular ligament:a new morphological variationand its potential clinical implicationsM. Polguj1, K. Jędrzejewski2, M. Topol21Department of Angiology, Chair of Anatomy, Medical University of Lodz, Lodz, Poland2Department of Normal and Clinical Anatomy, Chair of Anatomy, Medical University of Lodz, Lodz, Poland[Received 13 August 2012; Accepted 15 October 2012]The suprascapular notch (SSN) is the most common site of compression andinjury of the suprascapular nerve (SN), which results in a neuropathy known asSN entrapment. The SSN is enclosed from the top by the superior transversescapular ligament (STSL), creating a tunnel for the SN. On both sides of theSSN, below the STSL, the anterior coracoscapular ligament is found. This fi-brous band can potentially narrow the opening and contribute to the occur-rence of suprascapular entrapment syndrome. This study presents the first caseof a bifid anterior coracoscapular ligament coexisting with an atypical SN course,which has never been described in the literature before. Knowledge of suchanatomical variations can be helpful in arthroscopic and open procedures ofthe suprascapular region and confirms the safety of operative decompressionfor entrapment of the SN. (Folia Morphol 2012; 71, 4: 282–284)Key words: anterior coracoscapular ligament, anatomical variation,suprascapular nerve entrapment, suprascapular nerveINTRODUCTIONThe suprascapular notch (SSN) is a groove on theupper edge of the scapula. It is enclosed from thetop by the superior transverse scapular ligament(STSL), converting it into an osteofibrous passage.The SSN is the most common place for suprascapu-lar nerve (SN) entrapment, which results in poorlylocalised dull pain over the lateral and posterior as-pects of the shoulder, as well as weakened abduc-tion and external rotation of the upper extremity.This neuropathy is a considerable clinical problembecause it is often diagnosed incorrectly; the symp-toms are nonspecific and therefore it is usually dia-gnosed late when the supra- and infraspinatusmuscles have atrophied [4, 11]. Arthroscopic tech-niques for SN decompression have recently beendescribed with successful results [3, 7]. However,the safety and success of these arthroscopic proce-dures are predicated on a thorough understandingof the anatomy of the suprascapular region. Pre-vious studies confirm that anatomical variationsfound in the suprascapular region are significant,as they can increase the chance of SN compression[1, 2, 5, 8–10, 12, 13].In 2002, Avery et al. [1] were the first to de-scribe an additional, singular fibrous band thatextends on the anterior side of the SSN, below theSTSL. The authors named this structure the anteri-or coracoscapular ligament (ACSL). Although thereare a few studies of the superior traverse scapularligament, only three descriptions of ACSL can befound in the literature [1, 2, 8]. Knowledge of themorphological variations of ACSL is vital as far assuprascapular neuropathy is concerned. Avery et283M. Polguj et al., The bifid anterior coracoscapular ligamental. [1] and Bayramoglu et al. [2] proposed that itmight reduce the space available for the SN pas-sage, predisposing it to trauma. The morphologyof the suprascapular region is important in avoid-ing an iatrogenic lesion of the SN during arthro-scopic and open procedures of the shoulder region[7, 13].In this study, we describe an example of a bifidACSL coexisting with an atypical SN course. To ourknowledge, such a case has never been publishedbefore.CASE REPORTDissection of the suprascapular region was per-formed on the left upper extremity of an 82-year-oldformalin-embalmed Caucasian female. The SN andcorresponding vessels were identified, and the bifidACSL was exposed. The measurements of the ACSLwere taken using two complementary methods:a classical approach using an electronic digimatic cal-liper (Mitutoyo Company, Tokyo, Japan) and a newone based on analysis of the digital photographicdocumentation of the ACSL taken using MultiScan-Base v.18.02 software (Computer Scanning System II,Warsaw, Poland).In the presented case, the ACSL was found tohave a common distal attachment to the lateralborder of the SSN. It extended medially with twofibrous bands that attached separately to the me-dial border of the SSN (Fig. 1). The common distalportion was 9.6 mm wide, and the upper and low-er portions at the point of medial attachmentwere, respectively, 4.1 mm and 3.6 mm wide. Thelength of the superior band was 32.0 mm and theinferior one was 33.6 mm. The area of the open-ing limited by the inferior border of the STSL andsuperior border of the ACSL was 32.66 mm2. Thesuprascapular vein ran between the STSL and theACSL (Figs. 1A, C). The SN and artery travelled in-ferior to the ACSL through a very narrow tunnel(Figs. 1B, C). The diameter of the suprascapularartery was significantly smaller than that of thesuprascapular vein. The shape of the SN travellingbelow the ACSL was flat; its width at this pointwas 7.2 mm.DISCUSSIONAvery et al. [1] describe the presence of theACSL in 60% of 54 dissected shoulders (41% ofthem bilaterally). Researchers have highlighted itsrole in the narrowing of the suprascapular fora-men, which can potentially increase the risk ofnerve entrapment. Bayramoglu et al. [2] confirmedthe presence of an ACSL in 6 of the 32 shoulders(18.8%) and proposed its presence as an addition-al aetiological factor of the condition. The influ-ence of the ACSL on SN entrapment is probablyalso affected by the shape of the SSN. Piyawinij-wong and Tantipoon [8] reported that the ACSLwas found in 19 of 64 cadavers (28%). Three typesof this structure are recognised. Type I (15.79%)Figure 1. Anterior view of structures at the suprascapular region;A, B. Structures at the cadaver; C. Schematic arrangements;ACSL — anterior coracoscapular ligament; STSL — superiortransverse scapular ligament; SV — suprascapular vein;SA — suprascapular artery; SN — suprascapular nerve.284Folia Morphol., 2012, Vol. 71, No. 4has a distal attachment extending to the anteriorsurface of the scapula further away from the bor-der of the SSN. In type II (63.16%) the ligament passesacross the SSN, subdividing it into two foramina.Type III (21.05%) has a distal attachment extendingto the nearby area of the bottom of the SSN.Our description of the SN course in the SSN issimilar to that of Avery et al. [1], who reported thatthe SN was found to pass below the ACSL, thusbringing the nerve in close contact to the bony floorof the SSN and intensifying the risk of neuropathy.However, on the contrary, Bayramoglu et al. [2] andPiyawinijwong and Tantipoon [8] describe the SNas always running between the STSL and ACSL. Usu-ally the diameter of the suprascapular nerve is2–3 mm [5, 6]. However, in our study, this nerve is7.2 mm wide with a flat shape, probably as a resultof compression by the ACSL. Also, the suprascapularartery runs with the nerve below the ACSL and oc-cupies a wider space than normal. This feature couldhave a clinical implication on all extremities, as thesuprascapular artery forms an important anasto-mosis with the dorsal scapular and circumflex scap-ular arteries.This paper represents the first report of bifid ACSLcoexisting with an atypical SN course. It is a newpiece of anatomy, but also one that has importantclinical implications. For example, should the SN betravelling alongside the suprascapular artery belowthe ACLS, an incision into the ligament for decom-pression may also increase the risk of injury to theartery. Therefore, any information concerning suchanatomical variations can be helpful in both arthro-scopic and open procedures in the suprascapularregion.ACKNOWLEDGEMENTSThe paper was supported by grant No. 502-03--1-031-01/502-14-115 from the the Medical Univer-sity of Lodz, Poland.REFERENCES1. Avery BW, Pilon FM, Barclay JK (2002) Anterior cora-coscapular ligament and suprascapular nerve entrap-ment. Clin Anat, 15: 383–386.2. Bayramoglu A, Demiryürek D, Tüccar E, Erbil M, Aldur MM,Tetik O, Doral MN (2003) Variations in anatomy at thesuprascapular notch possibly causing suprascapularnerve entrapment: an anatomical study. Knee SurgSports Traumatol Arthrosc, 11: 393–398.3. Bhatia DN, de Beer, JF, van Rooeyn KS, du Toit DF (2006)Arthroscopic suprascapular nerve decompression at thesuprascapular notch. Arthroscopy, 22: 1009–1013.4. Boykin RE, Friedman DJ, Higgins LD, Warner JJ (2010)Suprascapular neuropathy. J Bone Joint Surg Am, 92:2348–2364.5. Edelson JG (1995) Bony bridges and other variationsof the suprascapular notch. J Bone Joint Surg Br, 77:505–506.6. Hirokawa D, Eliezri Y, Desciak E, Campanelli C (2010)Suprascapular nerve injury during Mohs surgery andreview of the surgical anatomy of the nervous struc-tures of the supraclavicular triangle. Dermatol Surg,36: 1756–1758.7. Lafosse L, Tomasi A, Corbett S, Baier G, Willems K, Gobezie R(2007) Arthroscopic release of the suprascapular nerveentrapment at the suprascapular notch: technique andpreliminary results. Arthroscopy, 23: 34–42.8. Piyawinijwong S, Tantipoon P (2012) The anterior co-racoscapular ligament in Thais: Possible etiological fac-tor of suprascapular nerve entrapment. Siriraj Med J,64: S12–S14.9. Polguj M, Jędrzejewski K, Podgórski M. Topol M (2011)Morphometric study of the suprascapular notch: pro-posal of classification. Surg Radiol Anat, 33: 781–787.10. Polguj M, Jędrzejewski K, Majos A, Topol M (2012) Thetrifid superior transverse scapular ligament: a case reportand review of the literature. Folia Morph, 71: 118–120.11. Romeo AA, Rotenberg DD, Bach BR Jr (1999) Suprasca-pular neuropathy. J Am Acad Orthop Surg, 7: 358–367.12. Ticker JB, Djurasovic M, Strauch RJ, April EW, Pollock RG,Flatow EL, Bigliani LU (1998) The incidence of gan-glion cysts and other variations in anatomy along thecourse of the suprascapular nerve. J Shoulder ElbowSurg. 7: 472–478.13. Urgüden M, Ozdemir H, Dönmez B, Bilbasar H, Oguz N(2004) Is there any effect of suprascapular notch type iniatrogenic suprascapular nerve lesions? An anatomicalstudy. Knee Surg Sports Traumatol Arthrosc, 12: 241–245.

The bifid anterior coracoscapular ligament: a new morphological variation and its potential clinical implications

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The bifid anterior coracoscapular ligament: a new morphological variation and its potential clinical implications

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