Background. Massive rotator cuff tears and consequent cuff-deficient arthritis (CTA) of the shoulder can cause severe shoulder dysfunction in the elderly. Reverse total shoulder arthroplasty (RTSA) has been widely used for treatment of CTA in all over the world since its introduction in the 90's. In Japan, however, we have just started to clinically use RTSA from April 2014. In addition, we have only one choice of the implants (Aequalis Reverse, Tornier) currently, and only one size of the base-plate of the glenoid component (29 mm in diameter) is available so far. Japanese, especially elderly people, have generally smaller figure than Caucasians. We are not sure whether the base-plate would fit for the smaller Japanese. The purpose of this study was to measure the size of the glenoids in Japanese using CT images and to examine that they would fit the 29 mm base-plate. Methods. The shoulders without osteoarthritis of the glenohumeral joint were eligible for the study. The subjects consisted of 30 shoulders including 10 elderly males, 10 elderly females, and 10 younger males, and the mean ages were 73 (range, 63–81), 74 (range, 65–89), and 32 (range, 27–36) years old, respectively. Mean heights and weights were 164 cm (range, 156–179) and 59 kg (range, 49–72), 154 cm (range, 151–161) and 57 kg (range, 48–65), and 173 cm (range, 162–179) and 72 kg (range, 61–100), respectively. CT images with a 0.3 mm slice pitch were used for the analysis. The images were loaded into a DICOM viewer (OsiriX), and a slice for simulated implantation of the base-plate was created using the multi-planar reconstruction (Figure 1), which had 10° of inferior tilt to the glenoid face. The width of the glenoid in the antero-posterior direction was measured at 14 mm above the inferior edge of the glenoid. Results. Mean widths for the elderly males, elderly females, and younger males were 27.7 mm (range, 24.8–28.9), 25.3 mm (range, 24.4–25.9), and 27.8 mm (range, 25.9–29.8), respectively. Discussion. The present study revealed that most of the younger and elderly males would fit the 29 mm base-plate. However, the glenoid width of all elderly females in this study was much smaller than the base-plate diameter. The base-plate with smaller diameter is indispensable for Japanese, and the pre-operative planning may be important for secure surgeries

Introduction. Shoulder motion results from a complex interaction between the interconnected segments of the shoulder girdle. Coordination is necessary for normal shoulder function and is achieved by synchronous and coordinated muscle activity. During rotational movements, the humeral head translates on the glenoid fossa in the anterior-posterior plane. Tension developed by the rotator cuff muscles compresses the humeral head into the glenoid fossa. This acts to limit the degree of humeral head translation and establishes a stable GH fulcrum about which the arm can be moved. Previous studies have been limited by the use of contrived movement protocols and muscular coordination has not been previously considered with regard to shoulder rotation movements. This study reports the activation profile and coordination of 13 muscles and 4 muscle groups during a dynamic rotational movement task based on activities of daily living. Methods. Eleven healthy male volunteers were included in the study. Electromyography (EMG) was recorded from 13 muscles (10 surface and 3 fine-wire intramuscular electrodes) using a wireless EMG system. EMG was recorded during a movement task in which the shoulder was consecutively rotated internally (phase 1) and externally (phase 2) with a weight in the hand. Muscle group data was calculated by ensemble averaging the activity of the individual component muscles. Mean signal amplitude and Pearson correlation coefficient (PCC) analysed muscle activation and coordination, respectively. Results. The mean length of phase 1 (internal rotation) and phase 2 (external rotation) was 1.1s (SD+0.15) and 1.09s (SD+0.18), respectively with no significant difference between them. Mean signal amplitude was significantly higher during external rotation for the anterior, middle and posterior deltoid, teres major and the rotator cuff muscles (Table 1). Significant positive correlations were identified between the activation patterns of the deltoid and rotator cuff groups (PCC=0.95, p=<0.001), the deltoid and latissimus dorsi-teres major groups (PCC=0.74, p=<0.001) and the latissimus dorsi-teres major and rotator cuff groups (PCC=0.87, p=<0.001) (Figure1). Discussion. The subscapularis is extensively described as an internal rotator of the glenohumeral joint; however, during this study it was primarily active during external rotation. During activities of daily living the subscapularis balances the force generated by the supraspinatus and infraspinatus by contracting eccentrically as external rotation progresses. This balance between the anterior and posterior rotator cuff maintains anterior-posterior stability of the humeral head on the glenoid fossa. There is a highly coordinated and synchronous relationship between all the major muscle groups of the shoulder during rotational activities, which ensures glenohumeral joint stability. The function of the shoulder muscles is task specific. This has important implications when considering the impact of muscle pathology on shoulder dysfunction and the treatment strategies employed

The reverse ball and socket shoulder replacement, employing a humeral socket and glenosphere, has revolutionized the treatment of patients with arthritis and rotator cuff insufficiency. The RSP (DjO Surgical, Inc., Austin, Texas) is one such device, characterized by a lateral center of rotation and approved for use in the United States since 2004. Multiple studies by the implant design team have documented excellent outcomes and low revision rates for the RSP, but other published outcomes data are relatively sparse. The objective of this study is to report on the complications and early outcomes in the first consecutive 60 RSPs implanted in 57 patients by a single shoulder replacement surgeon between 2004 and 2010. Forty-four patients were female and mean age at the time of reverse shoulder arthroplasty was 75 years (range 54 to 92 years). The RSP was used as a primary arthroplasty in 42 shoulders and to revise a failed prosthetic shoulder arthroplasty in 18 shoulders. During the study period, 365 shoulder replacements were implanted so that the RSP was used selectively, accounting for only 17% of all shoulder arthroplasties (8.4% for 2004-2007, 24.2% for 2008-2010). Most patients had pseudoparalysis and profound shoulder dysfunction so that mean pre-operative active forward elevation was to 45°, active abduction to 43°, active internal rotation to the buttock, and the mean pre-operative Simple Shoulder Test (SST) score was 1 out of 12. At final follow-up, mean active forward elevation had improved to 101° (p<0.0001), active abduction to 91° (p<0.0001), active internal rotation to the lumbosacral junction (p<0.001), and the mean final SST score was 7 out of 12. There were 16 complications in 14 patients, including 7 reoperations in 6 patients (11%): 3 closed reductions for dislocation, 2 open revisions for instability and for a dissociated liner in the same patient, one evacuation of a hematoma, and one open reduction and internal fixation of a post-operative scapular spine fracture. Two additional scapular spine or acromion fractures and one acromioclavicular joint separation developed postoperatively that impacted outcome adversely but did not require re-operation. None of the glenoid baseplates or humeral stems has been revised and no deep infections have occurred. Experience with reverse shoulder arthroplasty appears to influence the reoperation rate, as 3 of the reoperations occurred following the first 15 reverse shoulder arthroplasties. Overall improvements in active motion and self-assessed shoulder function were comparable to those reported previously. Final active motion results were somewhat lower than those reported previously, which may relate to the selection of predominately pseudoparalytic patients for reverse shoulder arthroplasty in this series. Use of the RSP device for reverse shoulder arthroplasty leads to improved motion and function in carefully selected older patients with pseudoparalysis or a failed shoulder replacement. Re-operations and complications occur but the learning curve may not be as steep as previously reported. This may relate to specific features of the implant system used in this series, as well as to surgeon experience

Introduction: A secure repair of the subscapularis represents an integral part of any surgery involving the anterior approach to the shoulder. Dysfunction of the subscapularis leads not only to poor functional results but also to anterior joint instability which is potentially untreatable. We have devised a new technique of double row fixation of the subscapularis using two suture anchors. Aim: To evaluate the biomechanical strength of this double row technique against the established methods of simple suturing and transosseous repair techniques. Method: Twenty matched pairs of human cadaveric shoulders were allocated into 3 groups. Group 1 consisted of 10 shoulders repaired with the double row technique. This involved incising the subscapularis along the bicipital groove and a lesser tuberosity osteotomy carried out leaving the subscapularis attached to a thin island of bone. A suture anchor (Twinfix) was then inserted just medial to the osteotomy site and the tendon repaired to bone using two horizontal mattress sutures. A second anchor was inserted laterally to supplement the repair with two simple suture knots. The remaining 10 contralateral shoulders were allocated equally between groups 2 and 3. In group 2, the subscapularis was divided longitudinally 1cm medial to the bicipital groove and repaired with simple interrupted suture knots. In group 3, the subscapularis was incised at its insertion to lesser tuberosity and the tendon repaired to the osteotomy site by multiple transosseous sutures through drill holes in the anterior humeral cortex. The suture material used in all three groups was identical and consisted of an ultra high molecular weight poly-ethylene suture (Ultrabraid). To simulate the direction of pull of the subscapularis, the testing block was tilted 45 degrees while a vertically applied distraction force was applied. A custom made jig was used to measure the amount of displacement in response to a gradually applied load. All specimens were tested to failure. The mode of failure of each fixational construct was recorded. Results: The load to failure was found to be significantly higher in the double row repair technique compared to simple suturing and transosseous methods. Simple suturing failed by suture cutting out of soft tissue and tranosseous repair failed by a combination of the suture cutting out through bone and soft tissue. Conclusion: This new double row technique is simple to perform and preliminary biomechanical testing has shown this to be superior in terms of fixational strength compared to established methods. Additional advantages of this technique which have not been taken into account in this in vitro study include non violation of the subscapularis tendon with bone to bone healing

The June 2012 Shoulder & Elbow Roundup³⁶⁰ looks at: reverse shoulder replacement; torn rotator cuffs and platelet-rich fibrin; rotator cuff repair; frozen shoulder; whether an arthroscopic rotator cuff repair actually heals; the torn rotator cuff’s effect on activities of daily living; subacromial impingement; how to improve the reliability of the Constant-Murley score; and failure of the Neer modification of an open Bankart procedure.