In regard to “Unusual case of absence of suprascapular notch and foramen”

Dear Editor,

We read the case report by Hegazy and Hegazy (2020), addressing an unusual case of absence of suprascapular notch and foramen, with interest. However, we would like to point out that this case is rather a discrete type of suprascapular notch (SSN), and it is not a rare case.

The suprascapular notch (SSN) is a notch presented as an indentation between two peaks where the suprascapular ligament attaches. The enclosing superior transverse scapular ligament (STSL), or its ossification forming a foramen, is a crucial component of the SSN anatomical definition (Rengachary et al., 1979; Duparc et al 2010; Polguj et al., 2011; Polguj et al., 2013; Kannan et al., 2014; Kumar et al., 2014; Al-Redouan et al., 2020). Even though evaluating the STSL on dry bones has its limitation, its two sites of attachments are observable and palpable on dry bones. A total absence of a SSN will entitle a non-existing ligament, and its attachment site can be evaluated on dry bone in close approximation of the site of omohyoid muscle attachment. This will constitute the SSN’s medial peak, while the SSN lateral peak is a part of the base of the coracoid process.

In 1942, Hrdlicka introduced five types of the SSN based on subjective observation of its shape, Type-I being the discrete form, and reported its prevalence to be 5.5% in a sample of 2722 scapulae (Hrdicka, 1942). In 1979, Rengachary et al. introduced an adopted six-type SSN classification based on its shape, Type-I having an absent notch and being defined by its wide depression, and it was found in 8% of 211 SSN samples (Rengachary et al., 1979). Additional studies used Rengachary’s classification and reported 12.4% (Albino et al., 2013) and 20% (Kannan et al., 2014) of the aforementioned SSN type in their samples. Another study applied a modified Rengachary’s classification and reported within the same category of SSN type to be 3.43% (Agrawal et al., 2001).

In 2011, Polguj et al. introduced a modified parametric form of SSN classification, in which Type-V donates the discrete type of SSN, and was found to be 11.6% in their dry-bone specimens collection (Polguj et al., 2011), and in 12.9% of CT-evaluated specimens (Polguj et al., 2013). Additional studies have reported this discrete type of SSN in 32.4% (Kumar et al., 2014) and 21.3% (Al-Redouan et al., 2020), respectively.

To our knowledge, we would place the reported SSN by (Hegazy and Hegazy, 2020) to be Type-I, according to the old classification introduced by Hrdicka (Hrdicka, 1942) and adopted by Rengachary et al. (Rengachary et al., 1979), based solely on the shape appearance of the SSN, as well as to be Type-V according to the more recent classification introduced by  Polguj et al. (Polguj et al., 2011), based on its appearance as a discrete notch, and its upper width versus depth parameters need to be measured to assess their ratio.