Angle of approach to the superior rotator cuff of arthroscopic instruments depends on the acromial morphology: an experimental study in 3D printed human shoulders

BACKGROUND Portal placement is a key factor for the success of arthroscopic procedures, particularly in rotator cuff repair. We hypothesize that the acromial anatomy may strongly determine the position of the shoulder bony landmarks and limit the surgeon's freedom to position the arthroscopic approaches in direction towards the acromion. The purpose of this study was to analyze the relation between different acromial shapes and the freedom of movement of arthroscopic instruments relative to the rotator cuff from standardized arthroscopic portals in a laboratory study on 3D shoulder models. METHODS 3D models of shoulders with a broad range of different acromial shapes were printed using CT and MRI scans. Angles from the portals to defined points on the rotator cuff and the supraglenoid tubercle were measured. In conventional radiographs, the critical shoulder angle, the scapular body acromial angle, and the glenoid acromial angle were measured and compared with the measured angles to the rotator cuff. RESULTS There was a large variation of angles of approach of instruments to the rotator cuff between the seven shoulders for each portal. From the joint line portal and the posterior edge portal, the biggest angles were measured to the posterior cuff. From the intermediate portal, the angles were largest to the intermediate rotator cuff and from the anterior portals to the anterior cuff. To the supraglenoid tubercle, best access was from anterior. For all portals, there was a big correlation between the glenoid acromial angle and the scapular body acromial angle with the angles of approach to the tendon and especially to the supraglenoid tubercle. CONCLUSION The access to the rotator cuff from almost every portal is influenced by the acromial shape. As hypothesized, a small (small GAA) and flat (big SBAA) acromion provide an easier approach to the rotator cuff from almost every portal. Therefore, it may severely influence the instruments maneuverability

Magnetic Resonance Imaging Findings in the Knee Before and After Long-Distance Running-Documentation of Irreversible Structural Damage? A Systematic Review

BACKGROUND Various studies have investigated structural knee changes after running, with conflicting results. PURPOSE To perform a systematic review of acute changes in knee structures as detected by magnetic resonance imaging (MRI) after running and assess the reversibility of these changes. STUDY DESIGN Systematic review. METHODS A systematic literature search in Medline, Cochrane, Embase, and Scopus was performed. Articles that fulfilled predefined inclusion criteria were included and systematically reviewed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. RESULTS A total of 19 studies were included in this review. All studies performed standard knee MRI; 6 studies additionally performed T1ρ and T2 mapping. Sixteen studies assessed cartilage or meniscal morphological changes. Ten found no significant morphological changes after running. Six studies showed significant changes at the first follow-up. Six performed a second follow-up. Five showed no change compared with baseline and the first follow-up, and 1 showed a significant recovery compared with the first follow-up and no significant difference compared with baseline. Five of the 6 studies performing T1ρ and T2 mapping found significant changes in T2 and T1ρ values at the first follow-up. Three performed a second follow-up. Two found a significant recovery of T2 but no recovery of T1ρ. One study did not find a significant change compared with baseline. Ten studies assessed the patellar tendon, ligaments, synovial fluid, or subchondral bone. Changes at the first follow-up were not significant. A second follow-up was performed in 5 studies. All studies discovered recovery from the first follow-up. CONCLUSION These data suggest that healthy athletes who have no risk factors for degenerative joint disease may present fleeting quantitative alterations after running. No irreversible, qualitative harmful effects seemed to occur, with the exception of persistent T1ρ elevation representing a proteoglycan depletion. Whether T1ρ changes need more than 3 months to recover or represent permanent structural damage remains to be investigated