Purpose: To identify the morphological patterns of suprascapular notch stenosis.
Methods: Suprascapular notch space capacity was assessed by morphometric analysis of 333 dry scapulae. Suprascapular notch parameters-superior transverse distance, middle width, depth, medial border length and lateral border length-were measured. The probable suprascapular notch stenosis was referenced by (1) comparing each obtained parameter measurement to the range of the suprascapular nerve diameter, and (2) quantifying the reduced parameters. Finally, the morphological pattern was determined based on the collective reduction of the parameters and their alignments.
Results: Five types of suprascapular notch based on depth to superior transverse distance ratio were identified and assessed. Type-I showed low incidence of stenosis (6/333) and low frequency within type (6/28) with potential risk of horizontal compression. Type-II showed relatively low incidence of stenosis (9/333) and low frequency within type (9/50) with undetermined pattern. Type-III showed relatively higher incidence of stenosis (47/333) but low frequency within type (47/158) with potential risk of vertical compression. Type-IV (foramen) showed low incidence of stenosis (6/333) and relatively lower frequency within type (6/26) with potential risk of encircled compression. Finally, type-V (discrete) showed relatively high incidence of stenosis (40/333) and high frequency within type (40/71) with potential risk of vertical compression. The suprascapular notch was found to be stenosed beyond its capacity to accommodate the suprascapular nerve in 49/333. Type-V is at most risk followed by Type-III.
Conclusions: Suprascapular notch stenosis takes three morphological patterns: horizontal, vertical or mixed. An osteoplasty of suprascapular notch margins may be required beside the common surgical approach of the superior transverse scapular ligamentectomy.
Keywords: Entrapment neuropathy; Incisura scapulae; Nerve compression; Scapula; Space capacity; Stenosis; Suprascapular nerve; Suprascapular notch; Types; Variations.