Medial collateral ligament strain with partial posteromedial olecranon resection. A biomechanical study.
BACKGROUND
Partial resection of the posteromedial aspect of the olecranon in the treatment of valgus extension impingement osteophytosis is a well-described technique. It has been hypothesized that removal of the normal olecranon process, beyond the osteophytic margin, increases the strain in the anterior bundle of the medial collateral ligament.


METHODS
We used an electromagnetic tracking device to investigate the strain in the anterior bundle of the medial collateral ligament as a function of increasing applied torque and posteromedial resections of the olecranon in seven cadaveric elbows. Applied torques under valgus stress consisted of hand weight, hand weight plus 1.75 Nm, and hand weight plus 3.5 Nm. Resections were conducted in sequential 3-mm increments, from 0 to 9 mm. We measured changes in the length of the anterior and posterior bands of the anterior bundle of the medial collateral ligament with strain gauges. The strains of the two bands were averaged, and the average was reported.


RESULTS
The strain in the anterior bundle of the medial collateral ligament was found to increase with increasing flexion angle, valgus torque, and olecranon resection beyond 3 mm. In two elbows, the anterior bundle of the medial collateral ligament ruptured during testing following the 9-mm resection. There was a significant difference between the strain following the 6-mm resection and that following the 3-mm resection at 110 degrees of flexion with 3.5 Nm of added torque (p = 0.004).


CONCLUSIONS
In this in vitro cadaver study, an increase in flexion angle, an increase in valgus torque, and resection of > or =6 mm led to an increase in strain in the anterior bundle of the medial collateral ligament. The non-uniform change in strain related to 3 mm of resection suggests that resections of the posteromedial aspect of the olecranon of >3 mm may jeopardize the function of the anterior bundle.
Kamineni
Srinath
S
Department of Orthopaedics and Biomechanics, Imperial College London and Hillingdon Hospital NHS Trust, South Kensington Campus, London SW7 2AZ, United Kingdom.
ElAttrache
Neal S
NS
O'driscoll
Shawn W
SW
Ahmad
Christopher S
CS
Hirohara
Hirotsune
H
Neale
Patricia G
PG
An
Kai-Nan
KN
Morrey
Bernard F
BF
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D017885:Collateral Ligaments / Q000503:physiopathology*; D004551:Elbow Joint / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D014457:Ulna / Q000601:surgery*