Silvan Beeler1, Laura Leoty2, Bettina Hochreiter1, Fabio Carrillo2, Tobias Götschi3, Tim Fischer4, Philipp Fürnstahl2, Christian Gerber1. 1. Department of Orthopaedic Surgery, University of Zürich, Balgrist University Hospital, Zürich, Switzerland. 2. Research in Orthopedic Computer Science (ROCS), University of Zürich, Balgrist University Hospital, Zürich, Switzerland. 3. Unit for Clinical and Applied Research, Balgrist University Hospital, Zürich, Switzerland. 4. Division of Radiology and Nuclear Medicine, Kantonsspital St. Gallen, St. Gallen, Switzerland.
Abstract
BACKGROUND: There is evidence that specific variants of scapular morphology are associated with dynamic and static posterior shoulder instability. To this date, observations regarding glenoid and/or acromial variants were analyzed independently, with two-dimensional imaging or without comparison with a healthy control group. Therefore, the purpose of this study was to analyze and describe the three-dimensional (3D) shape of the scapula in healthy and in shoulders with static or dynamic posterior instability using 3D surface models and 3D measurement methods. METHODS: In this study, 30 patients with unidirectional posterior instability and 20 patients with static posterior humeral head subluxation (static posterior instability, Walch B1) were analyzed. Both cohorts were compared with a control group of 40 patients with stable, centered shoulders and without any clinical symptoms. 3D surface models were obtained through segmentation of computed tomography images and 3D measurements were performed for glenoid (version and inclination) and acromion (tilt, coverage, height). RESULTS: Overall, the scapulae of patients with dynamic and static instability differed only marginally among themselves. Compared with the control group, the glenoid was 2.5° (P = .032), respectively, 5.7° (P = .001) more retroverted and 2.9° (P = .025), respectively, 3.7° (P = .014) more downward tilted in dynamic, respectively, static instability. The acromial roof of dynamic instability was significantly higher and on average 6.2° (P = .007) less posterior covering with an increased posterior acromial height of +4.8mm (P = .001). The acromial roof of static instability was on average 4.8° (P = .041) more externally rotated (axial tilt), 7.3° (P = .004) flatter (sagittal tilt), 8.3° (P = .001) less posterior covered with an increased posterior acromial height of +5.8 mm (0.001). CONCLUSION: The scapula of shoulders with dynamic and static posterior instability is characterized by an increased glenoid retroversion and an acromion that is shorter posterolaterally, higher, and more horizontal in the sagittal plane. All these deviations from the normal scapula values were more pronounced in static posterior instability.
BACKGROUND: There is evidence that specific variants of scapular morphology are associated with dynamic and static posterior shoulder instability. To this date, observations regarding glenoid and/or acromial variants were analyzed independently, with two-dimensional imaging or without comparison with a healthy control group. Therefore, the purpose of this study was to analyze and describe the three-dimensional (3D) shape of the scapula in healthy and in shoulders with static or dynamic posterior instability using 3D surface models and 3D measurement methods. METHODS: In this study, 30 patients with unidirectional posterior instability and 20 patients with static posterior humeral head subluxation (static posterior instability, Walch B1) were analyzed. Both cohorts were compared with a control group of 40 patients with stable, centered shoulders and without any clinical symptoms. 3D surface models were obtained through segmentation of computed tomography images and 3D measurements were performed for glenoid (version and inclination) and acromion (tilt, coverage, height). RESULTS: Overall, the scapulae of patients with dynamic and static instability differed only marginally among themselves. Compared with the control group, the glenoid was 2.5° (P = .032), respectively, 5.7° (P = .001) more retroverted and 2.9° (P = .025), respectively, 3.7° (P = .014) more downward tilted in dynamic, respectively, static instability. The acromial roof of dynamic instability was significantly higher and on average 6.2° (P = .007) less posterior covering with an increased posterior acromial height of +4.8mm (P = .001). The acromial roof of static instability was on average 4.8° (P = .041) more externally rotated (axial tilt), 7.3° (P = .004) flatter (sagittal tilt), 8.3° (P = .001) less posterior covered with an increased posterior acromial height of +5.8 mm (0.001). CONCLUSION: The scapula of shoulders with dynamic and static posterior instability is characterized by an increased glenoid retroversion and an acromion that is shorter posterolaterally, higher, and more horizontal in the sagittal plane. All these deviations from the normal scapula values were more pronounced in static posterior instability.
Authors: Alexander Maurer; Sandro F Fucentese; Christian W A Pfirrmann; Stephan H Wirth; Ali Djahangiri; Bernhard Jost; Christian Gerber Journal: J Shoulder Elbow Surg Date: 2011-10-29 Impact factor: 3.019
Authors: Rüdiger von Eisenhart-Rothe; Hermann Otto Mayr; Stefan Hinterwimmer; Heiko Graichen Journal: Am J Sports Med Date: 2009-11-25 Impact factor: 6.202
Authors: Florian B Imhoff; Roland S Camenzind; Elifho Obopilwe; Mark P Cote; Julian Mehl; Knut Beitzel; Andreas B Imhoff; Augustus D Mazzocca; Robert A Arciero; Felix G E Dyrna Journal: Knee Surg Sports Traumatol Arthrosc Date: 2019-06-28 Impact factor: 4.342
Authors: Peter N Chalmers; Lindsay Beck; Matthew Miller; Irene Stertz; Heath B Henninger; Robert Z Tashjian Journal: J Am Acad Orthop Surg Date: 2020-07-01 Impact factor: 3.020
Authors: Lukas Ernstbrunner; Thomas Häller; Manuel Waltenspül; Karl Wieser; Christian Gerber Journal: Clin Orthop Relat Res Date: 2021-09-01 Impact factor: 4.755