Classification and Morphological Parameters of the Scapular Spine

Abstract

Incidence of scapular spine (SS) fractures as a result of complications of reverse total shoulder arthroplasty is relatively high leading to inferior clinical outcomes and an increased risk of revision and dislocation. Fractures of SS because of trauma, including the acromion, constitute 6% to 23% of scapula fractures. The purpose of this study was to classify the SS and present specific geometrical parameters according to osteologic features. A total of 319 intact dry scapulae were collected and classified based on morphological characteristics and shape of the SS. Nine bony landmarks were also chosen and described for their relevance to regions of interest for scapular fixation. Five specific types of SS were noted and the most prevalent groups were Type 1 (Fusiform shape) (47.17%) and Type 5 (Horizontal S-shape) (19.18%). Overall, Types 3, 4, and 1 showed thicker landmark values compared to Type 5, with Type 2 having smaller values. Our classification into 5 distinct types allowed appreciation of the anatomical variance of SSs. The contours of Types 5 and 1 presented a more complex morphology and may lead to a worse surgical approach due to a fracture. As Types 2 and 5 were much thinner than the other types, these may be more susceptible to fractures.

Mitigating Fracture of the Acromion and Scapular Spine After Reverse Shoulder Arthroplasty

“…Other studies performing measurements mostly in Levy zone I on anteroposterior (AP) radiographs corroborated these findings by Werthel et al 8,16,20 . Measuring acromial midsubstance thickness more closely aligns with the risks reported by biomechanical studies 17,34-36 . Thus, the acromial midsubstance thickness on scapular Y-view may provide prognostic value, whereas the thickness of the anteromedial acromion (Levy zone I) has lesser relevance.…”

“…There is substantial heterogeneity in scapular morphology, which requires consideration during baseplate fixation and screw placement. Two in vitro scapula morphology studies, both of which measured the SS and acromion thicknesses in various planes, found that fusiform and s-shaped SS may be at a greater risk of fracture based on having multiple points of a significantly thinner acromion and SS 34,35 (Fig. 2).…”

Morphological Classification and Parameters of Spine of Scapula Among South Indian Population

“…Based on morphological classifications, Hua Jun Wang states that Type 1-Fusiform shape (47.17%) and Type 5-Horizontal S-shape (19.18%) were the most common, followed Type 4-Wooden club shape (13.21%) and Type 3-Thick rod shape (12.58%). Type 2-Slender -rod shape (7.86%) was the least common [9]. In our study the Type 5-S Shape (0%) was the least common, commonest being type 1-fusiform(35%), followed by type IV (28%) and type III(21%).…”

Locked 90°-double plating of scapular spine fracture after reverse shoulder arthroplasty with union and good outcome despite plate adjacent acromion fracture

“…Four weeks after surgery, the patient was brought to the emergency department and admitted overnight after a fall on ice at the train station. Radiographs ( figure 1A, B ) and a CT scan ( figure 1C ) confirmed a displaced lateral SS fracture at the base of acromion 1 in a type 1 fusiform shaped SS 2 as seen on the radiograph ( figure 1B ) and as confirmed on CT scan.…”