| Purpose: The purpose of this study was to investigate normal bonyanatomy of the glenoid rim of Chinese adults, to measure innerglenoid rim angle and outer glenoid rim angle, and to define theangles for successful anchor insertion for arthroscopic labralrepairs. Type of Study: An anatomic study using cadavericshoulder specimens. Methods:12unpaired isolated humanglenoids (6right,6left) without any evidence of trauma were forstudying. The glenoid specimens were scanned using320-slice CT(Aquilion ONE), then reconstruction glenoid to a three dimensionalmodel Using materialise’s interactive medical image control system(MIMICS) and to obtain cross-sectional images in6different planes.Inner glenoid rim angles (angle between lines drawn from the edgeof the glenoid rim to the innermost bony margins of both the glenoidarticular surface and the glenoid neck, marked as angle α) andouter glenoid rim angle (angle between line drawn from the edge ofthe glenoid rim to the outermost bony margins of glenoid articularsurface and line drawn tangency of outmost bony margins ofglenoid neck, marked as angle β) were measured from thecross-sectional pQCT images of the glenoids at8positions: the2-o’clock,3-,4-,5-,6-,7-,8-, and9-o’clock positions. Glenoid morphology was noted for each position. Draw the glenoid jointsurface on paper with lines drawn as clock, described circles with3-6o’clock as center,12mm as radius, mark the intersection pointof the circle and the glenoid rim as point A. lines between center ofcircle and point A was intersected with major axis of glenoid, anglebetween these lines was measured as minimum insertion angle ofanchor, marked as angle γ. All statistical analyses were performedwith SPSS16.0. Normal distribution of the data was confirmed withKolmogorov-Smirnov test. Paired t-test was performed to detectdifferences in the angles between two locations of same group.Two independent samples t-test was performed to detectdifferences in the angles between same location of left and right.Analysis of variance (ANOVA) was performed to detect differencesin the angles between right and left, and different locations of theglenoid rim.(P<0.05). Results: the angle αfrom the2-o’clock to the9-o’clock were56°±5°，54°±7°，51°±7°，62°±6°，88°±4°，74°±10°，59°±10°，51°±6°，respectively. The angle βfrom the2-o’clock to the9-o’clock were53°±5°,51°±8°，53°±10°，60°±7°，88°±4°，72°±13°，63°±12°，55°±6°，respectively. The smallest αwas at the4-o’clock position, however the smallest β was at the3-o’clock position. No significant difference were noted between αand β on each location of glenoid rim. Asymmetric morphology of the glenoid was noted with an almost straight line extendingmedially from the rim at the3-o’clock position, whereas a concavemorthology was noted at the9-o’clock position. Similary at the4-and5-o’clock position, the scapular bony surface did not curvetoward the base as markedly as it did at the correspondingposterior8-and7-o’clock position. Angle γfrom the3-o’clock to the9-o’clock were24°±4°，55°±5°，86°±6°，119°±3°. No significantdifference of any angle at the same position was noted between leftand right. Conclusions: The available bone mass for the anchorinsertion was found to vary depending ong the position of theglenoid rim. Both rim angle and glenoid morthology for eachposition must be considered when selecting the ideal anchorinsertion angle for Bankart repair. Meanwhile, minimum insertionangle of anchor should also be considered before anchor insertion.Angles reported here were useful for arthroscopic Bankart repair. |
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