# Morphometrical Study of Scapular Glenoid Cavities Dr. Girish V.Patil ? , Dr. Sanjeev I. Kolagi ? & Dr. Umesh Ramdurg ? Abstract-Shape and dimensions of the glenoid cavity are important in the design and fitting of glenoid components for total shoulder arthroplasty. An understanding of variations in normal anatomy of the glenoid is essential while evaluating pathological conditions like osseous bankart lesions and osteochondral defects. In the present study done on 224 dry scapulae, three glenoid diameters were measured. The average superiorinferior diameter on right and the left side were 33.68±4.32mm and 32.09±4.11mm respectively. The average anteriorposterior diameter of the lower half of the right glenoid was 23.29±2.34mm and that of the left glenoid was 24.90±2,95mm. the mean diameter of the upper half of the right glenoid was 15.74±1.75mm and that of the left glenoid was 16.81±1.74mm. The left glenoid cavity was slightly shorter in length, but broader especially in the upper part as compared to the left glenoid cavity. The current study also recorded a higher percentage of glenoid cavities having the glenoid notch in the anterior margin of the glenoid as compared to earlier studies. While evaluating defects and lesions of the glenoid, this fact could be useful. Smaller dimensions of the glenoid cavities in the south Indian population may have to be taken into consideration while designing and fitting glenoid components while performing total shoulder arthroplasty. # I. # Introduction he scapula is an integral part of the connection between the upper extremity and the axial skeleton. Lateral angle of the scapula is a shallow, pyriform articular surface-the Glenoid cavity, also known as Glenoid fossa of the scapula. Glenoid cavity is directed laterally and forward and articulates with the head of the humerus and form Gleno-humeral joint. The vertical diameter of the Glenoid cavity is the longest and it is broader below than above. The surface is covered with hyaline cartilage in the fresh state and its slightly raised margins give attachment to a fibrocartilaginous structure-the glenoid labrum which deepens the cavity (Richard LM, Newell 2005 1 ). Shoulder joint between shallow glenoid fossa and hemispherical head of humerus is a ball and socket type of synovial joint. It has maximum movement but less stability. The factors contributing to stability the shoulder joint are the deepening of the glenoid cavity by the glenoid labrum; the suprahumeral support provided by the coracoacromial arch, the capsule is strengthened by the fusion of tendons of rotator cuff muscles and glenohumeral and coracohumeral ligaments. Shoulder joint is frequently dislocated inferiorly due to having less support in that region of the joint. During trauma,dislocation with fracture of glenoid are also common. During treatment repair of the labrum and reinforcing the capsule by an overlapping repair and rearrangement of anterior muscle, total shoulder replacement is also being used as treatment (Chummy S. Sinnatomby 20062). Total shoulder arthroplasty has proven to provide predictable improvement in pain and function in patients with a degenerative shoulder joint and an intact rotator cuff. Various shapes of the glenoid cavity have been described based on the presence of a notch on anterior glenoid rim. It has been found that if the notch is distinct then the glenoid labrum is not fixed to the bony margin of the notch but bridges the notch itself. This could make the shoulder joint less resistant to dislocating forces (Prescher A. and Klmpen T. 19973) Because of unusual and complex morphology features of the scapula, and the lack of complete quantitative anatomic studies, the current study was undertaken to describe the glenoid cavity quantitatively with its dimensions and shape. # II. # Materials This study was done on 224 dry, unpaired adult human scapulae of unknown sex obtained from department of Anatomy Srinivas Institute of medical Sciences, Mangalore. Scapula having clear and intact glenoid cavity were selected for the study. All the measurements were taken in millimeters using sliding calipers. # III. # Methods The following parameters were studied in the glenoid cavity of the dry scapula 1. Superior-Inferior glenoid diameter (SI): Represents the maximum distance from the inferior point on the glenoid margin to the most prominent point of the supraglenoid tubercle. 2. Anterior-Posterior glenoid diameter (AP-1): Represents the maximum breadth of the articular margin 3. Anterior-Posterior glenoid diameter (AP-2): Reprethe anterior-posterior diameter (Breadth) of the top half of the glenoid cavity at the mid-point between the superior rim and the mid-equator. 4. Shape of the glenoid cavity: A piece of white sheet was placed on the glenoid cavity and held firmly in position to trace the shape of the glenoid cavity. The side of the point of a lead pencil was rubbed along the rim of the glenoid cavity to get a tracing of the shape of the glenoid cavity on the paper. IV. # Stastical Evaluation The mean and standard error of the glenoid cavity in various dimensions were calculated. The morphometric values of both sides were analyzed using an unpaired t-test. V. # Observation and Results In 224 dry scapulae, 104 belonging to the right side and 120 to the left side. Abbreviations used in the following tables are In the present study, the superior -inferior diameters of the glenoid cavity on the right side varied from 25 to 42 mm, with an average of 33.68±4.32mm. on left side the superior -inferior diameter from 25 to 42, with a mean of 32.09±4.11mm. Statistically Highly significant value was found while comparing the SI diameters of the right glenoid with that of the left glenoid cavity (P<0.001 ) In this study, the AP 1-glenoid diameter of the right and left sides varies from 17 to 27mm and 17 to 28mm respectively. The average maximum breadth of the right glenoid was 23.29±2.34mm and the maximum breadth of the left glenoid was 24.90±2,95mm. Statistically Highly significant value was found while comparing the AP 1 diameter of the right glenoid with that of the left glenoid (P<0.001). The range for the AP2 diameter of the glenoid cavity was 12 to 20mm and the mean for the same was 15.74±1.75mm. the AP2 diameter for the left glenoid varied from 12 to 21mm, while the mean for the left glenoid was 16.81±1.74mm. # Volume XIV Issue II Version I # Year ( ) # 2014 # H While comparing the AP2 diameter of the right and left glenoid cavities, statistically important difference was found (P<0.001). While examining the various shapes of the glenoid cavity in the present study. It was found that the could mainly be of 3 types. It was classified as inverted comma shaped if the anterior glenoid notch was distinct, as pear shaped if the anterior glenoid notch was indistinct and as oval shaped if the anterior glenoid notch was absent. On the right side out of the total 104 glenoid cavities examined 36 were found to have inverted comma shape. And the incidence of this shape was calculated to be 34.62%. the number of glenoids having pear shape on the right side was 49 and the incidence was found to be 47.12%.oval glenoid cavities were 19 in number on the right side and the incidence was 18.27%. On the left side, glenoids with the inverted comma shape were 39 in number out of the total 120 scapulae examined. The incidence of inverted comma shaped glenoid was 32.5%. 54 glenoids on the left side were found to have the pear shape and incidence of pear shaped glenoid was 45%. The oval glenoid cavities were 27 in number and the incidence of oval glenoid was 22.5%. # VI. # Discussion In the present study an effort has been made to find the average diameters of the glenoid cavity of the scapula and the incidence of various shapes of the glenoid cavity in the south Indian population. Several authors have attempted to determine the glenoid diameters in the course of their research. This has been performed in a variety of ways, including direct measurement of dry scapulae, direct measurement of fresh or embalmed cadavers, radiographic measureement of scapulae harvested from cadavers and radiographic measurement in living patients. These studies have been performed on different populations. In evaluating the data presented in this study, a comparison to work by others reveals several differences as well as similarities # Summary and Conclusion Knowledge of the shape and dimensions of the glenoid are important in the design and fitting of glenoid components for total shoulder arthroplasty. An understanding of variations in normal anatomy of the glenoid is essential while evaluating pathological conditions like osseous bankart lesions and osteochondral defects. In the present study done on 224 dry scapulae, three glenoid diameters were measured. The superiorinferior, anterior-posterior diameter of the lower half of the glenoid and the anterior-posterior diameter of the upper half of the glenoid. The average superior-inferior diameter on right and the left side were 33.68±4.32mm and 32.09±4.11mm respectively. The average anteriorposterior diameter of the lower half of the right glenoid was 23.29±2.34mm and that of the left glenoid was 24.90±2,95mm. The mean diameter of the upper half of the right glenoid was 15.74±1.75mm and that of the left glenoid was 16.81±1.74mm. The left glenoid cavity was slightly shorter in length, but broader especially in the upper part as compared to the right glenoid cavity. The current study also recorded a higher percentage of glenoid cavities having the glenoid notch in the anterior margin of the glenoid as compared to earlier studies. While evaluating defects and lesions of the glenoid, this fact could be useful. By observing the tables in the discussion it can be implied that the values observed in the present study, through coinciding with that of some of the studies are mostly less than that recorded by many of the observers. This implies that the smaller dimensions of the glenoid cavities in the south Indian population may have to be taken into consideration while designing and fitting glenoid components while performing total shoulder arthroplasty in this population, Volume XIV Issue II Version I Year ( ) 2014 21. SI-superior inferior glenoid diameter2. AP 1-anterior-posterior glenoid diameter(maximum breadth of the articular surface)3. AP 2-anterior -posterior glenoid diameter of theupper half of the glenoid cavity.4. SD -standard deviation5. P -P value6. mm-millimeters 3Sl.NoPointsRightLeft1Number of bones1041202Range17 to 2717 to 283Mean23.2924.904Standard deviation2.342.955Statistical significancet =20.32, P<0.001 4Sl.NoPointsRightLeft1Number of bones1041202Range12 to 2012 to 213Mean15.7416.814Standard deviation1.751.745Statistical significancet =53.5, P<0.001 5Number of bonesShape of glenoidIncidence of shape36Inverted comma34.62%49Pear47.12%19Oval18.27%Total-104-- 639Inverted comma32.5%54Pear45.0%27Oval22.5%Total-120-- 7ObserversNo of specimensMean SI diameterMallon4 et al (1992)2835±4.1mmIannotti5 et al (1992)14039±3.5mmVon Schroeder6 et al (2001) 3036±4mmChurchill7 et al (2001)Male 20037.5±2.2mmFemale 14432.6±1.8mmLuis Rios Frutos8 (2002)Male-6536.08±2.0mmFemale 3831.17±1.7mmOzer et al9 (2006)Male 9438.71±2.71mmFemale 9233.79±3.08mmKarelse et al10 (2007)4035.9±3.6mmPresent studyRight 10433.68±4.32mmLeft 12032.09±4.11mm 9ObserversNo of specimensMean AP2 diameterIannotti et al (1992)14023±2.7mmPresent studyRight 10415.74±1.75mmLeft 12016.81±1.74mmTable 10 : Comparison of percentage of occurrence of glenoid notch by various authorsObservers% of glenoid with notch (inverted% of glenoids withoutcomma + pear shaped)notch (oval)Prescher A andRight + left -55%Right + left -45%Klumpen T (1997)Present studyRight -81.74%Right -18.27%(2011)Left-77.5%Left-22.5%VII. © 2014 Global Journals Inc. (US) * The Scapula principles of construction and stress HAnetzberger RPutz Acta Anat Basel 156 1996 * Frazer,s Anatomy of the human skeleton, sixth edition ASBreathnach J and A Churchill Ltd 1965 * Traumatic glenohumaral bone defects and their relationship to failure of arthroscopic bankart repairs: Significance of the inverted-pear glenoid and the humeral engaging Hill-Sachs lesion SSBurkhart DeBeer JF Arthroscopy 16 2000 * Quantifying glenoid bone loss arthroscopically in shoulder instability SSBurkhart Arthroscopy 18 2002 * Last's anatomy, Regional and applied SChummy Sinnatamby 2006 London Eleventh edition. Churchill livingstone * Glenoid size, inclination, and version: An anatomic study RSChurchill J Shoulder elbow surg 10 2001 * Anatomy, Histology and Vascularity of the glenoid labrum. The journal of bone and joint surgery DECooper 1992 * DeWilde LF 2004 26 about the variability of the shape of the glenoid cavity. Surgical radiological anatomy * Quantitative anatomy of the scapula NAEbraheim American journal of orthopedics 29 4 2000 * Radiographic analysis of the bone defects in chronic anterior shoulder stability TBEdwards ABoulahia GWalch Arthroscopy 19 2003 * The anteroinferior labrum helps center the humeral head on the glenoid EVFehringer Journal of shoulder and Elbow surgery 12 2003 * Determination of sex from the clavicle and scapula in a Guatemalan contemporary rural population The Americal journal of Forensic medicine and Pathology 23 3 2002 Frutos LR * Glenohumeral articular contact areas and pressures following labral and osseous injury to the anteroinferior quadrant of the glenoid PEGries J Shoulder Elbow Surgery 11 5 2002 * Effects of the glenoid labrum and glenohumeral abduction on stability of the shoulder joint through concavity compression AMHalder The journal of bone and joint surgery 7 2001 * Glenoid-Labral socket. A constrained articular surface SMHowell BJGalinat Clinical orthopaedics and related research 1989 243 * The normal glenohumeral relationship J PIannotti Journal of Bone and Joint surgery 1992 * Quantitative assessment of classic bony bankart lesions by radiography and computed tomography EItoi Am J Sports Med 31 1 2003. Jan-Feb * Gross anatomy of the shoulder CMJobe MJCoen CARockwood Jr The shoulder Saunders 2004 third edition * The Pillars of the scapula AKarelse LKegels DeWilde L ; Rockwood CAJr The shoulder Philadelphia WB Saunders 2007 20 third edition * Sex determination using the scapula in medieval skeletons from east Anatolia Ozer Coll.Antropol 30 2006. 2006 * The Roentgenographic evaluation of anterior shoulder instability HPavlov Clinical orthopedics and Related research 194 1985 * Age-related changes of the glenoid labrum in normal shoulders MPfahler Journal of shoulder and Elbow surgery 12 2003 * Does the area of the glenoid cavity of the scapula show sexual dimorphism? APrescher TKlumpen Journal of anatomy 186 1995 * The glenoid notch and it's relation to the shape of the glenoid cavity of the scapula APrescher TKlumpen Journal of Anatomy 190 1997 * Gray's anatomy. The anatomical basis of clinical practice. Thirty-nine edition LRichard Newell Harcourt publications London 2005 * Glenoid rim Morphology in recurrent anterior glenohumeral instability HSugaya The journal of Bone and joint Surgery 85 5 2003 * Sublabral foramen and Buford complex: inferior extent of the unattached or abscent labrum in 50 patients MJTuite Radiology 223 2002 * Osseous anatomy of the scapula VonSchroeder HPKuiper SDBotte MJ Clinical orthopedics and related research 383 2001 * Posterior glenoid rim deficiency in recurrent (atraumatic) posterior DWeishaupt 2000 * Radiographic and geometric anatomy of the scapula WJMallon Clinical orthopedics 277 1992 * Developmental anatomy of the shoulder and anatomy of the glenohumeral joint. shoulder instability SJO'brien Skeletal Radiology 29 4 2004 * Osteochondral defect of the glenoid fossa: Cross-sectional imaging features YuJs GGreenway DResnick Radiology 1998. 2006