Added transverse screw in tripod construct increases stiffness in Mason III radial head fractures: a finite element analysis.

BACKGROUND: The tripod screw configuration has been shown to offer similar stiffness characteristics to a laterally placed plate. However, concern has been raised that the construct may be prone to failure in scenarios where the screw intersects at the fracture line. We performed a finite element analysis to assess potentially ideal and unideal screw placements in the tripod construct among Mason III radial head fractures. METHODS: A 3-dimensional proximal radius model was developed using a computed tomography scan of an adult male radius. The fracture site was simulated with a uniform gap in transverse and sagittal planes creating a Mason type III fracture pattern comprising 3 fragments. Three configurations were modeled with varying screw intersection points in relation to the radial neck fracture line. A fourth configuration comprising an added transverse interfragmentary screw was also modeled. Loading scenarios included axial and shear forces to simulate physiological conditions. Von Mises stress and displacement were used as outcomes for analysis. RESULTS: Some variation can be seen among the tripod configurations, with a marginal tendency for reduced implant stress and greater stiffness when screw intersection is further from the neck fracture region. The construct with an added transverse interfragmentary screw demonstrated greater stiffness (2269 N/mm) than an equivalent tripod construct comprising 3 screws (612 N/mm). CONCLUSION: The results from this study demonstrate biomechanical similarity between tripod screw constructs including where screws intersect at the radial neck fracture line. An added fourth screw, positioned transversely across fragments, increased construct stiffness in our model.

Chronic Pectoralis Major Rupture Reconstruction With Interpositional Acellular Dermal Allograft.

Background: Pectoralis major tendon (PMT) rupture commonly occurs in males 20 to 39 years of age. PMT rupture is most often associated with gym-based exercise, with attempted bench press being the most common causative event, but it is also associated with contact or impact sports. Delayed presentation, misdiagnoses, and chronic PMT rupture can result in a therapeutic dilemma. Case Series: We present 2 cases of chronic PMT rupture that were operatively managed using acellular dermal allograft as an interposition graft. Patients' final follow-ups were at 20 and 30 months, respectively. Strength in their pectoralis major muscle was well preserved on the contralateral side: 88% for patient 1 and 110% for patient 2. Conclusion: Our reported technique using an interpositional acellular dermal allograft is a good option to treat chronic PMT rupture.

Nationwide trends in management of proximal humeral fractures: an analysis of 77,966 cases from 2008 to 2017.

BACKGROUND: There is no consensus as to the treatment of proximal humeral fractures (PHFs), particularly in elderly patients. There is increasing evidence that nonoperative management may have similar functional outcomes to operative management, which is potentially conflicting with increasingly improved surgical techniques and implants. The aim of this study was to investigate the changes in the incidence and management of PHFs across Australia over a 10-year period. MATERIALS AND METHODS: We retrospectively reviewed all hospitalizations of patients with PHFs from 2 Australian national health care databases from 2008 to 2017. We recorded the incidence of PHFs and annual utilization rates of commonly used treatment options including nonoperative management, hemiarthroplasty (HA), reverse total shoulder arthroplasty (RTSA), and open reduction-internal fixation (ORIF). RESULTS: The incidence of PHFs increased from 26.8 per 100,000 person-years in 2008 to 45.7 per 100,000 person-years in 2017. There was a decrease in operative management from 2008 to 2017, with 32.5% and 22.8% of all PHFs treated operatively in 2008 and 2017, respectively (P = .001). ORIF use decreased significantly from 76.6% to 72.6% (P = .004). RTSA use increased significantly from 4.1% to 24.5% (P < .001). HA use decreased significantly from 19.3% to 3% (P < .001). CONCLUSIONS: Whereas the incidence of PHFs increased, the operative management of PHFs decreased significantly from 2008 to 2017, particularly in patients aged 65 years or older. This decrease in operative management was in part due to a significant decrease in ORIF and HA use in patients aged 65 years or older. There was a significant increase in RTSA use.

A biomechanical study of headless compression screws versus a locking plate in radial head fracture fixation.

HYPOTHESIS: Fixation of a 3-part radial head fracture with cannulated compression screws will show equivalent stiffness to a locking plate under axial load. Debate exists regarding the management of Mason type III fractures, with many believing that open reduction and internal fixation provides advantages over other options. By virtue of their subarticular placement, screw fixation is less likely to cause impingement compared with plate fixation, which can result in loss of rotation and requirement for hardware removal. Insufficient fixation stability can lead to nonunions, necrosis of the radial head, pain, and instability. We tested the mechanical stability of fixation of simulated radial head fractures using headless compression screws compared with standard plate construct. METHODS: Standardized test constructs were created with repeatable osteotomy cuts and hardware placement on each Synbone model (Synbone AG, Malans, Switzerland). We presectioned 22 proximal radius Synbone models to simulate a 3-part radial head fracture. The models were fixed using a radial head locking plate or headless compression screws in a tripod construct. The constructs were potted into a compression test jig using 2-part epoxy resin. Compression testing was performed using a 30-kN Instron Universal machine (Instron, Norwood, MA, USA). The compression tool was spherical, representing the surface of the capitellum. RESULTS: There was no significant difference between the stiffness of the Synbone constructs under axial load. CONCLUSION: There was no significant difference between fixation stiffness of a 3-part radial head fracture with headless compression screws in a tripod structure vs. a locking plate in Synbone. Further study is required to allow clinical application.

Sonographic assessment of the subscapularis after reverse shoulder arthroplasty: impact of tendon integrity on shoulder function.

BACKGROUND: The deltopectoral approach for reverse shoulder arthroplasty (RSA) requires subscapularis tenotomy or lesser tuberosity osteotomy. Whether the subscapularis should be repaired at the conclusion of the procedure remains controversial. The present study sonographically assessed the subscapularis after RSA and evaluated the effect of tendon integrity on functional outcome. METHODS: All patients who had undergone RSA in the Gold Coast University Hospital between 2005 and 2016 were included. Sonography was performed by a blinded examiner. Function was assessed using the Disabilities of the Arm, Shoulder and Hand, the Constant-Murley, and Oxford Shoulder scores. Internal rotation ability was recorded on a 6-point scale. RESULTS: The study included 43 patients (48 shoulders). Median length of follow-up was 19 months (range, 4-132 months). On sonography, the subscapularis was graded intact in 6 shoulders (13%), intact with mild attenuation in 16 (33%), severely attenuated in 15 (31%), and not intact or absent in 11 (23%). Differences in Disabilities of the Arm, Shoulder and Hand, Constant-Murley, or Oxford Shoulder scores between intact and attenuated or absent subscapularis shoulders were not significant. Internal rotation scores were significantly higher in the intact and mildly attenuated tendon group than in the absent tendon group (U = 1.0, P = .001 and U = 28.5, P = .007, respectively). CONCLUSIONS: The present work is the first long-term outcome study of RSA using sonography to assess the subscapularis. Subscapularis integrity did not appear to have a measurable effect on patient outcome as measured by standard scores but was important for internal rotation ability after RSA.