Arthroscopic Bankart repair with peeling osteotomy of the anterior glenoid rim preserves glenoid morphology

BACKGROUND

A decrease in the glenoid size after arthroscopic Bankart repair (ABR) was common in shoulders without osseous fragments compared with those with osseous fragments. For cases of chronic recurrent traumatic anterior glenohumeral instability without osseous fragments, we have performed ABR with peeling osteotomy of the anterior glenoid rim (ABRPO) to make an intentional osseous Bankart lesion. The aim of this study was to compare the glenoid morphology after ABRPO with it after simple ABR.

METHODS

The medical records of patients who underwent arthroscopic stabilization for chronic recurrent traumatic anterior glenohumeral instability were retrospectively reviewed. Patients with an osseous fragment, with revision surgery and without complete data were excluded. Patients were assigned to 1 of 2 groups: Group A, ABR without peeling osteotomy procedure or Group B, with ABRPO procedure. Computed tomography was performed preoperatively and 1 year after surgery. The size of the glenoid bone loss was investigated by the assumed circle method. The following formula was used to calculate the decreased size of the glenoid: (Δ) = (postoperative size of the glenoid bone loss) - (preoperative size of the glenoid bone loss). The size of the glenoid 1 year after surgery was assessed to determine if it had decreased (Δ > 0%) or not decreased (Δ ≤ 0%) relative to the preoperative size.

RESULTS

This study evaluated 39 shoulders divided into 2 groups: 27 shoulders in Group A and 12 shoulders in Group B. In Group A, postoperative glenoid bone loss was significantly greater than preoperative glenoid bone loss (7.8 ± 6.2 vs. 5.5 ± 5.3, respectively, P = .02). In Group B, postoperative glenoid bone loss was significantly lower than preoperative glenoid bone loss (5.6 ± 5.4 vs. 8.7 ± 4.0, respectively, P = .02). The P value for the interaction of group (A or B) × time (preoperative or postoperative) was 0.001. The decreased size of the glenoid was significantly larger in Group A than in Group B (2.1 ± 4.2 vs. -3.1 ± 4.5, respectively, P = .001). The rate of shoulders in which the size of the glenoid decreased 1 year after surgery relative to the preoperative size was significantly higher in Group A than in Group B (63% [17/27] vs. 25% [3/2], respectively, P = .04).

CONCLUSIONS

The study showed that ABRPO preserved the glenoid size better than simple ABR without a peeling osteotomy procedure.

Effects of Increased Retroversion Angle on Glenoid Baseplate Fixation in Reverse Total Shoulder Arthroplasty: A Finite Element Analysis

Background

Increased glenoid retroversion occurs in patients with severe arthritis but its effect on baseplate fixation of a reverse total shoulder arthroplasty (rTSA) is not clear. The purpose of this study is to determine the effects of increasing glenoid retroversion on baseplate fixation in rTSA using finite element analysis (FEA) modelling.

Methods

Five sets of computerized tomographic (CT) images of healthy normal shoulders were selected and segmented with Amira (Thermo Fisher Scientific) to obtain the solid geometries. Scapula FEA models with 5°, 10°, 15°, 20° and 25° retroversion angles were generated for each healthy scapula geometry and a rTSA glenoid baseplate was implanted on each model. Maximum stress at the anterior and posterior portions of the glenoid and the micromotion between the bone and baseplate were recorded. After simulation with normal scapular bone material properties (Young's modulus 4GPa and Poisson's ratio 0.3), another set of simulations was run on each subject with a 25° retroversion angle and poor bone quality (Young's modulus 500 MPa and Poisson's ratio 0.3) to study a worst-case scenario. Micromotions in each model were also recorded. All statistical analysis was done with SPSS.

Results

Simulation results of models generated from the same subject but with different retroversion angles showed a clear pattern: as retroversion angle increased, the stresses increased posteriorly and decreased anteriorly. Also, micromotion between the bone and the baseplate increased with the increase of retroversion angle. With analysis of variance (ANOVA), we found that all three values change significantly as the retroversion angle increases (p < 0.001). The simulation results also showed that micromotion was large in shoulders with small glenoid size and poor bone quality. However, even in the model with the worst-case scenario (smallest glenoid size, poorest bone quality and 25° retroversion angle), the maximum micromotion and the maximum stresses are still within the safe range.

Discussion

In all cases with both normal and poor bone quality, the stresses and micromotion stayed below the threshold to allow for bone ingrowth of the glenoid baseplate to occur. Based on these results, for glenoid baseplates with a central peg/post and 4 screws for fixation, rTSA baseplate retroversion does not need to be corrected to less than 10° to provide good initial fixation as has been recommended for a cemented glenoid component and can withstand the initial stresses and micromotion up to 25° of retroversion.

Level of evidence

Basic Science Study; Computer Modeling.

Early clinical results of reverse total shoulder arthroplasty in the Korean population

BACKGROUND

We evaluated the short-term clinical outcomes and compared the component's sizes of reverse total shoulder arthroplasty (RTSA) in Korean Population.

MATERIALS AND METHODS

We performed an RTSA on 42 patients between December 2007 to February 2010. The mean age at surgery was 72.5 ± 5.6 (10 men, 32 women) and average follow-up period was 24 months. Twenty-two cuff tears arthropathy, 15 irreparable massive rotator cuff tears with pseudoparalysis, 5 proximal humeral fractures, and 2 infection cases were included. We evaluated clinical outcomes and also the intra- and postoperative complications to determine if any of the complications were unique to the use of a RTSA in a Korean population. In the anatomic study, 92 uninjured shoulders of 92 patients were used for measuring the inferior glenoid size, and we compared the component's sizes of RTSA with those of the normal population.

RESULTS

The ASES (American Shoulder and Elbow), UCLA, and KS (Knee Society) scores significantly improved from preoperative 35 (0-63), 12 (5-27), and 39 (3-81) to postoperative 68 (37-95), 24 (16-35), and 68 (34-88), respectively (P < .05). Postoperative complications were seen in 20% and scapular notching 35%. Three patients required further surgery for shoulder dislocation, periprosthetic fracture, and stem loosening. In the anatomic study, mean radius of the inferior glenoid was 17.1 ± 2.1 mm in male and 15.4 ± 1.6 mm in female.

CONCLUSION

The short-term clinical results of an RTSA in Korean population are excellent despite high complication rate. However, the size of the glenoid is sometimes smaller than the baseplate (29 mm diameter) in female patients. More adequate size of the glenoid component should be considered.