Factors contributing to glenoid baseplate micromotion in reverse shoulder arthroplasty: a biomechanical study.

BACKGROUND: Reverse shoulder arthroplasty (RSA) is typically performed in patients with cuff tear arthropathy. A common type of RSA baseplate has a central peg and 4 peripheral screws inserting into the glenoid surface. Baseplate failure is a significant postoperative complication that reduces prosthetic longevity and usually requires revision surgery. This study evaluated the contribution of mechanical factors on initial baseplate fixation. MATERIALS AND METHODS: This study simulated glenoid baseplate loading in a RSA. A half-fractional factorial design was used to test 5 factors: bone density (160 or 400 kg/m3), screw length (18 or 36 mm), number of screws (2 or 4), screw angle (neutral or diverging), and central peg length (13.5 or 23.5 mm). Trials were cyclically loaded at a 60° angle with 500 N for 1000 cycles. Micromotion at 4 peripheral screw positions was analyzed using a multifactorial analysis of variance (P < .05). RESULTS: We found an increase in micromotion with 3 scenarios: (1) lower bone density at all screw positions; (2) shorter central peg length at the inferior, superior and anterior screws; and (3) shorter screw length at the inferior and anterior screws. There were interactions between bone density and screw length at the inferior and anterior screws and between bone density and central peg length at the inferior, superior, and anterior screws. DISCUSSION: Greater bone density, a longer central peg, and longer screws provide improved initial glenoid fixation in an RSA, whereas the number of screws, and the angle of screw insertion do not. These findings may help minimize baseplate failure and revision operations.

A scoping review of biomechanical testing for proximal humerus fracture implants.

BACKGROUND: Fixation failure is a relatively common sequela of surgical management of proximal humerus fractures (PHF). The purpose of this study is to understand the current state of the literature with regard to the biomechanical testing of proximal humerus fracture implants. METHODS: A scoping review of the proximal humerus fracture literature was performed, and studies testing the mechanical properties of a PHF treatment were included in this review. Descriptive statistics were used to summarize the characteristics and methods of the included studies. RESULTS: 1,051 proximal humerus fracture studies were reviewed; 67 studies met our inclusion criteria. The most common specimen used was cadaver bone (87%), followed by sawbones (7%) and animal bones (4%). A two-part fracture pattern was tested most frequently (68%), followed by three-part (23%), and four-part (8%). Implants tested included locking plates (52%), intramedullary devices (25%), and non-locking plates (25%). Hemi-arthroplasty was tested in 5 studies (7%), with no studies using reverse total shoulder arthroplasty (RTSA) implants. Torque was the most common mode of force applied (51%), followed by axial loading (45%), and cantilever bending (34%). Substantial testing diversity was observed across all studies. CONCLUSIONS: The biomechanical literature was found to be both diverse and heterogeneous. More complex fracture patterns and RTSA implants have not been adequately tested. These gaps in the current literature will need to be addressed to ensure that future biomechanical research is clinically relevant and capable of improving the outcomes of challenging proximal humerus fracture patterns.

Comparison of stable and unstable pertrochanteric femur fractures managed with 2- and 4-hole side plates.

BACKGROUND: Sliding hip screw (SHS) fixation traditionally involves the use of 4-hole side plates; however, 4-hole plates have disadvantages, including longer surgery and greater postoperative pain, and there is little evidence that they provide increased stability. We compared 2- and 4-hole side plates in stable and unstable pertrochanteric fractures. METHODS: We prospectively enrolled consecutive patients with pertrochanteric femoral fractures treated between Jan. 1, 2004, and Apr. 30, 2009, with a 135° SHS using either a 2- or 4-hole side plate, based on surgeon preference. RESULTS: A total of 327 patients were managed with an SHS device (252 women, 75 men). There were 208 stable fracture patterns (AO/OTA 31 A1, A2.1) and 119 unstable (AO/OTA 31 A2.2, A2.3, A3). We managed 172 patients with 2-hole plates and 155 with 4-hole plates. The average duration of surgery (30.44 v. 51.45 min), blood loss (26.0 v. 31.3 g/L) and transfusion requirements (43% v. 31. 60% transfusion) were significantly lower with the 2-hole than the 4-hole plate. There was no significant difference in length of stay (19 v. 16 d). With stable fractures there was no significant difference in failure rate (6.3% v. 4.9%). In unstable fractures there was a significantly higher rate of failure using 2-hole side plates (24.4% v. 10.8%). CONCLUSION: In stable fractures, use of an SHS with a 2-hole side plate results in shorter surgery and less blood loss/transfusion than a 4-hole side plate, with equivalent survival. In unstable fractures, there is a greater than 2-fold rate of failure when a 2-hole side plate is used.

CONTEXTE: La vis coulissante pour hanche (SHS) implique habituellement la pose de plaques latérales à 4 perforations; toutefois, ce type de plaque comporte des inconvénients, notamment une durée de chirurgie plus longue et des douleurs postopératoires plus persistantes, et il n'a pas été démontré qu'elle confère plus de stabilité. Nous avons comparé les plaques à 2 et à 4 perforations dans des fractures pertrochantériennes stables et instables. MÉTHODES: Nous avons inscrit de manière prospective des patients consécutifs ayants de fractures pertrochantériennes du fémur et traités entre le 1er janvier 2004 et le 30 avril 2009 au moyen d'une SHS de 135° et d'une plaque latérale à 2 ou à 4 perforations, selon la préférence du chirurgien. RÉSULTATS: En tout, 327 patients ont été traités de la sorte (252 femmes, 75 hommes). Nous comptions 208 fractures stables (AO/OTA 31 A1, A2.1) et 119 fractures instables (AO/OTA 31 A2.2, A2.3, A3). Nous avons traité 172 patients au moyen de plaques à 2 perforations, et 155 au moyen de plaques à 4 perforations. La durée moyenne de la chirurgie (30,44 c. 51,45 min), les pertes sanguines (26,0 c. 31,3 g/L) et les besoins transfusionnels (43 % c. 31,60 % transfusés) ont été significativement moindres avec les plaques à 2 perforations qu'avec les plaques à 4 perforations. On n'a noté aucune différence significative pour ce qui est de la durée du séjour hospitalier (19 c. 16 jours). En ce qui concerne les fractures stables, il n'y a pas eu de différence significative au plan du taux d'échec thérapeutique (6,3 % c. 4,9 %). En ce qui concerne les fractures instables, on a noté un taux significativement plus élevé d'échecs avec les plaques à 2 perforations (24,4 % c. 10,8 %). CONCLUSION: Dans les fractures stables, l'utilisation d'une SHS et d'une plaque latérale à 2 perforations permet une chirurgie plus brève et cause moins de pertes sanguines et de transfusions que la plaque à 4 perforations, sans différence au plan de la survie. Dans les fractures instables, on observe un taux 2 fois plus élevé d'échecs lorsqu'on utilise une plaque latérale à 2 perforations.

Solutions for patient activation will yield the greatest benefit.

In the context of fiscal scarcity and abundant consumer health technologies, robust choices must be made. In this article, the authors assert that technologies that will yield the greatest return on investment for patients, providers and health system payers should be prioritized. They present three technology solutions that enable high-needs patients and their advocates to actively participate in their care: an audiovisual record of patient-education that can be accessed and shared post-consultation to improve retention; patient-friendly care plans that enable more active participation in shared decision-making; and personal health coaching to foster sustainable behaviour change.