title: Evolving concept of bipolar bone loss and the Hill-Sachs lesion: from "engaging/non-engaging" lesion to "on-track/off-track" lesion.
abstract: For anterior instability with glenoid bone loss comprising 25% or more of the inferior glenoid diameter (inverted-pear glenoid), the consensus of recent authors is that glenoid bone grafting should be performed. Although the engaging Hill-Sachs lesion has been recognized as a risk factor for recurrent anterior instability, there has been no generally accepted method for quantifying the Hill-Sachs lesion and then integrating that quantification into treatment recommendations, taking into account the geometric interplay of various sizes and various orientations of bipolar (humeral-sided plus glenoid-sided) bone loss. We have developed a method (both radiographic and arthroscopic) that uses the concept of the glenoid track to determine whether a Hill-Sachs lesion will engage the anterior glenoid rim, whether or not there is concomitant anterior glenoid bone loss. If the Hill-Sachs lesion engages, it is called an "off-track" Hill-Sachs lesion; if it does not engage, it is an "on-track" lesion. On the basis of our quantitative method, we have developed a treatment paradigm with specific surgical criteria for all patients with anterior instability, both with and without bipolar bone loss.
authors.affiliation: Department of Shoulder Surgery, Concordia Hospital for Special Surgery, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Giacomo
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Itoi
authors.affiliation: The San Antonio Orthopaedic Group, San Antonio, Texas, U.S.A.. Electronic address: ssburkhart@msn.com.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Burkhart
mesh_terms: D001182:Arthroscopy / Q000379:methods; D001862:Bone Resorption / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D016025:Bone Transplantation; D019317:Evidence-Based Medicine; D006801:Humans; D021621:Imaging, Three-Dimensional; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology / Q000601:surgery*; D012008:Recurrence; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed