Retrograde nailing versus locking plate osteosynthesis of proximal humeral fractures: a biomechanical study

• Published in: Journal of shoulder and elbow surgery Vol. 21; no. 5; pp. 618 - 624
• Main Authors: Dietz, Sven-Oliver, MD, Hartmann, Frank, MD, Schwarz, Thomas, Nowak, Tobias E., MD, Enders, Annalisa, MD, Kuhn, Sebastian, MD, Hofmann, Alexander, MD, Rommens, Pol Maria, MD
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01.05.2012; Elsevier
• Subjects: Biological and medical sciences; Biomechanical Phenomena; biomechanics of proximal humerus; Biomechanics. Biorheology; Bone Nails; Bone Plates; Bone Screws; Diseases of the osteoarticular system; Fracture Fixation, Internal - instrumentation; Fundamental and applied biological sciences. Psychology; Humans; Injuries of the limb. Injuries of the spine; intramedullary implants; locking plates; Medical sciences; Orthopedics; Prosthesis Design; Proximal humeral fracture; Radiography; retrograde nailing; Retron; Shoulder Fractures - diagnostic imaging; Shoulder Fractures - physiopathology; Shoulder Fractures - surgery; Tissues, organs and organisms biophysics; Traumas. Diseases due to physical agents; biomechanics of proximal humerus; Retron; locking plates; Biomechanical Study; retrograde nailing; Basic Science Study; Proximal humeral fracture; intramedullary implants; Proximal; Diseases of the osteoarticular system; Rheumatology; Osteosynthesis; Nailing; Fracture; Trauma; Biomechanics; Treatment; Surgery; Humerus; Comparative study; Locking
• ISSN: 1058-2746; 1532-6500
• DOI: 10.1016/j.jse.2011.04.013

Background In locking plate osteosynthesis of proximal humeral fractures, secondary varus malalignment is a specific complication. Retron nails (Tantum AG, Neumunster, Germany), among others, have been designed to improve medial support of the calcar humeri. The aim of our biomechanical study was to examine whether Retron nails provide increased stiffness for axial loads and adequate stiffness for torsional loads when compared with Philos plates (Synthes AG, Umkirch, Germany). Materials and methods Twenty-two fresh-frozen paired humeri were collected. After potting the specimens, intact bones were exposed to sinusoidal axial (10-120 N) and torsional (±2.5 Nm) loading for 8 cycles to calculate the initial stiffness and exclude pairs with differences. Afterward, an unstable proximal humeral fracture (AO 11-A3) was created by means of an oscillating saw, and the respective osteosynthesis devices were implanted. After another 4 cycles, initial changes in stiffness were measured. Subsequently, all specimens were tested for 1,000 cycles of loading before final stiffness was assessed. Results We found no statistically significant differences between Retron and Philos specimens after 4 or 1,000 cycles of loading. Conclusion Our study suggests that retrograde nailing provides sufficient stability for axial and torsional loading in 2-part fractures of proximal humeri.