Treatment of distal humeral fractures using conventional implants. Biomechanical evaluation of a new implant configuration.
BACKGROUND
In the face of costly fixation hardware with varying performance for treatment of distal humeral fractures, a novel technique (U-Frame) is proposed using conventional implants in a 180 degrees plate arrangement. In this in-vitro study the biomechanical stability of this method was compared with the established technique which utilizes angular stable locking compression plates (LCP) in a 90 degrees configuration.


METHODS
An unstable distal 3-part fracture (AO 13-C2.3) was created in eight pairs of human cadaveric humeri. All bone pairs were operated with either the "Frame" technique, where two parallel plates are distally interconnected, or with the LCP technique. The specimens were cyclically loaded in simulated flexion and extension of the arm until failure of the construct occurred. Motion of all fragments was tracked by means of optical motion capturing. Construct stiffness and cycles to failure were identified for all specimens.


RESULTS
Compared to the LCP constructs, the "Frame" technique revealed significant higher construct stiffness in extension of the arm (P = 0.01). The stiffness in flexion was not significantly different (P = 0.16). Number of cycles to failure was found significantly larger for the "Frame" technique (P = 0.01).


CONCLUSIONS
In an in-vitro context the proposed method offers enhanced biomechanical stability and at the same time significantly reduces implant costs.
Windolf
Markus
M
AO Research Institute, AO Foundation, Clavadelerstrasse 8, 7270 Davos, Switzerland. markus.windolf@aofoundation.org
Maza
Edgardo Ramos
ER
Gueorguiev
Boyko
B
Braunstein
Volker
V
Schwieger
Karsten
K
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001860:Bone Plates / Q000592:standards / Q000639:trends; D002102:Cadaver; D019544:Equipment Failure Analysis / Q000379:methods; D005260:Female; D005592:Fracture Fixation / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D006810:Humeral Fractures / Q000503:physiopathology / Q000601:surgery*; D006811:Humerus / Q000503:physiopathology / Q000601:surgery*; D016268:Internal Fixators / Q000592:standards* / Q000639:trends; D007593:Joint Instability / Q000503:physiopathology / Q000517:prevention & control / Q000601:surgery; D008297:Male; D011183:Postoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D011474:Prosthesis Design / Q000379:methods*; D019919:Prosthesis Implantation / Q000379:methods*; D016059:Range of Motion, Articular / Q000502:physiology; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology