ISAKOS Congress 2021

2021 ISAKOS Biennial Congress Paper


The Anatomical Concave Surface Area Method, a 3-Dimensional Quantification of Glenoid Bone Loss in Shoulder Instability

Marine Launay, MEng, Greenslopes, QLD AUSTRALIA
Muhammad Naghman Choudhry, MBChB, MRCS, FRCS, Brisbane AUSTRALIA
Nicholas Green, MEng, Brisbane AUSTRALIA
Jashint Maharaj, MBBS, MPHTM, Brisbane, QLD AUSTRALIA
Peter Pivonka, PhD AUSTRALIA
Kenneth Cutbush, MBBS, FRACS, FAOrthA, Spring Hill, QLD AUSTRALIA
Ashish Gupta, MBBS, MSc, FRACS, Brisbane, QLD AUSTRALIA

Shoulder Surgery QLD Reserach Institute, Brisbane, QLD, AUSTRALIA

FDA Status Not Applicable


The ACSA method uses a 3-Dimensional area-based quantification accounting for the concavity of the glenoid fossa to estimate instability-related glenoid bone loss.



Recurrent shoulder instability may be associated with glenoid erosion and bone loss. Quantification of glenoid bone loss influences surgical procedure contemplated and preoperative planning of stabilisation procedures.


This study aimed to quantify the concave surface area of glenoid bone loss, utilizing 3-Dimensional (3D) segmented models of the scapula. Comparisons with methods utilizing the glenoid rim for bone loss estimations (best circle fit method and glenoid height/width method) were also investigated.


36 consecutive preoperative bilateral Computed Tomography (CT) scans of patients eligible for primary stabilization procedure were selected from our institutional surgical database (mean age 29 ± 9 years, 31 males and 5 females). Bilateral CT scan segmentation allowed for generation of 3D models of both scapulae. The Anatomical Concave Surface Area (ACSA) of the inferior glenoid was mapped using the diameter of the best-fit circle of the healthy glenoid using 3-Matic 13.0 software (Materialise, Leuven, Belgium). A ratio of the difference between surface areas of both glenoids (healthy and pathological) against the anatomical circular surface area of the healthy glenoid (ACSA method) was calculated to estimate bone loss. These results were compared with glenoid bone loss estimations obtained using the best circle fit and glenoid height/width methods. Inter- and intra-observer reliabilities were also calculated.


The average bone loss calculated using the ACSA, best circle fit and glenoid height/width methods were 9.4 ± 6.7%, 14.3 ± 6.8% and 17.6 ± 7.2% respectively. The ACSA method showed excellent inter-observer reliability with Intraclass Correlation Coefficient (ICC) of 0.95 compared to the best circle fit (ICC = 0.71) and glenoid height/width (ICC = 0.79) methods.


This study showed that use of 3D anatomical concave surface area method to quantify instability-related glenoid bone loss is reliable and provides results that are less than methods utilizing the glenoid rim for bone loss estimations.

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