Glenoid and humeral head bone defects have long been recognized as major determinants in recurrent shoulder instability as well as main predictors of outcomes after surgical stabilization. However, a universally accepted method to quantify them is not available yet. The purpose of the present study is to describe a new CT method to quantify bipolar bone defects volume on a virtually generated 3D model and to evaluate its reproducibility. A cross-sectional observational study has been conducted. Forty CT scans of both shoulders were randomly selected from a series of exams previously acquired on patients affected by anterior shoulder instability. Inclusion criterion was unilateral anterior shoulder instability with at least one episode of dislocation. Exclusion criteria were: bilateral shoulder instability; posterior or multidirectional instability, previous fractures and/or surgery to both shoulders; congenital or acquired inflammatory, neurological, or degenerative diseases. For all patients, CT exams of both shoulders were acquired at the same time following a standardized imaging protocol. The CT data sets were analysed on a standard desktop PC using the software 3D Slicer. Computer-based reconstruction of the Hill-Sachs and glenoid bone defect were performed through Boolean subtraction of the affected side from the contralateral one, resulting in a virtually generated bone fragment accurately fitting the defect. The volume of the bone fragments was then calculated. All measurements were conducted by two fellowship-trained orthopaedic shoulder surgeons. Each measurement was performed twice by one observer to assess intra-observer reliability. Inter and intra-observer reliability were calculated. Intraclass Correlation Coefficients (ICC) were calculated using a two-way random effect model and evaluation of absolute agreement. Confidence intervals (CI) were calculated at 95% confidence level for reliability coefficients. Reliability values range from 0 (no agreement) to 1 (maximum agreement). The study included 34 males and 6 females. Mean age (+ SD) of patients was 36.7 + 10.10 years (range: 25 – 73 years). A bipolar bone defect was observed in all cases. Reliability of humeral head bone fragment measurements showed excellent intra-observer agreement (ICC: 0.92, CI 95%: 0.85 – 0.96) and very good interobserver agreement (ICC: 0.89, CI 95%: 0.80 – 0.94). Similarly, glenoid bone loss measurement resulted in excellent intra-observer reliability (ICC: 0.92, CI 95%: 0.85 – 0.96) and very good inter-observer agreement (ICC: 0.84, CI 95%:0.72 – 0.91). In conclusion, matching affected and intact contralateral humeral head and glenoid by reconstruction on a computer-based virtual model allows identification of bipolar bone defects and enables quantitative determination of bone loss

The laterjet procedure is an important option in both primary and revision surgeries, especially in anterior shoulder instabilities that progress with glenoid bone loss. 12 patients who had a history of unsuccessful arthroscopic bankart repair and who underwent laterjet procedure in Ankara Atatürk Research and Training Hospital between 2013 and 2017 were included in the study and the patients were evaluated retrospectively. The mean age of the patients was calculated as 27.7 (range 21 to 38 years). Rowe and Walch-Duplay scores and operated shoulder (OS)-healthy shoulder (HS) range of motion (ROM) measurements were used to evaluate patients clinically and functionally. The mean follow-up time of the patients was calculated as 5.5±1.8 years. Firstly, no dislocation history was recorded in any patient afer the laterjet procedure. The mean Rowe score was calculated as 82.5 (range 60–100). Accordingly, 8 patients had excellent result, 3 patients had good result and 1 patient had fair result. The mean Walch-Duplay score was 81.4 (range 55–100). It was determined as excellent result in 6 patients, good result in 4 patients and fair result in 2 patients. Another data, joint ROM of the OS-HS of patients are shown in the table. There was some limitation in OS compared to the HS. p<0.05 value was accepted as statistically significant. While there was a statistically significant difference in external rotation (OS:35.2º, HS:56.4º)(p=0.003), internal rotation (OS:65.7º, HS:68.1º)(p=0.008) and flexion (OS:171.2º, HS:175.9º)(p=0.012) degrees but there was no statistically significant difference in abduction degrees (OS:164.3º, HS:170.4º) (p=0.089). In radiological evaluation, partial graft resorption was detected in 1 patient, but it was asymptomatic. The osteoarthritis which is one of the complications of laterjet procedure, was not detected radiologically. There are some limitations of the study. Firstly, it is a retrospective study. Secondly, the demographic features of the patients such as age, gender, profession and dominant hand are excluded. Thirdly, the mean follow-up time is not too long. Finally, some of the scales filled in are based on the patient's declaration, which may not yield sufficient objective results. In conclusion, the laterjet procedure is a suitable and reliable technique even for revision surgery in the treatment of anterior shoulder instability. It gives positive results in terms of shoulder stability and function. The major disadvantage was found to be the limitation of external rotation. Longer follow-up is needed for another outcomes and late complications, such as osteoarthritis. For any figures or tables, please contact the authors directly

Latarjet procedure (transfer of coracoid process to the anterior glenoid rim) has been widely used for severe anterior shoulder instability. The purpose of the present study was to investigate the intraarticular stress distribution after this procedure to clarify the pathomechanism of its postoperative complications. CT-DICOM data of the contralateral healthy shoulder in 10 patients with unilateral anterior shoulder instability (9 males and 1 female, age: 17–49) was used for the present study. Three-dimensional finite element models of the glenohumeral joint was developed using software, Mechanical Finder (RCCM, Japan). In each shoulder, a 25% bony defect was created in the anterior glenoid cavity, where coracoid process was transferred using two half-threaded screws. The arm position was determined as 0-degree and 90-degree abduction. While medial margin of the scapula was completely constrained, a standard compressive load (50 N) toward the centre of the glenoid was applied to the lateral wall of the greater tuberosity. A tensile load (20N) was also applied to the tip of coracoid process along the direction of conjoint tendon. Then, elastic analysis was performed, and the distribution pattern of Drucker-Prager equivalent stress was investigated in each model. The proximal half of the coracoid represented significantly lower equivalent stress than the distal half (p < 0.05). In particular, the lowest mean equivalent stress was seen in its proximal-medial-superficial part. On the other hand, a high stress concentration newly appeared in the antero-inferior aspect of the humeral head exactly on the site of coracoid bone graft. We assumed that the reduction of mean equivalent stress in the proximal half of the coracoid was caused by the stress shielding, which may constitute one of the pathogenetic factors of its osteolysis. A high stress concentration in the humeral head may eventually lead shoulder joint to osteoarthritis