Techniques and systems are described for planning shoulder stability enhancement surgeries. A computing system may determine a size of a predicted premorbid glenoid bone of the patient of a patient, a size of a Bankart lesion on a morbid glenoid bone of the patient, and a size of a geodesic surface on a 3-dimensional model of a predicted premorbid humerus of the patient. The geodesic surface is defined at least in part by a projected medial border of a Hill-Sachs lesion on a morbid humerus and a projected medial border of a footprint of a humeral head of the morbid humerus. The computing system may determine, based on the three areal sizes, whether bone loss of the patient involves joint engagement. The computing system may output an indication of whether a shoulder stability enhancement surgery that includes a bone graft is recommended for the patient.