Background: Clinical evaluation of valgus elbow laxity is difficult.
The optimum position of elbow flexion and forearm rotation with which to
identify valgus laxity in a patient with an injury of the ulnar collateral
ligament of the elbow has not been determined. The purpose of the present
study was to determine the effect of forearm rotation and elbow flexion on
valgus elbow laxity.
Methods: Twelve intact cadaveric upper extremities were studied with
a custom elbow-testing device. Laxity was measured with the forearm in
pronation, supination, and neutral rotation at 30°, 50°, and 70°
of elbow flexion with use of 2 Nm of valgus torque. Testing was conducted with
the ulnar collateral ligament intact, with the joint vented, after cutting of
the anterior half (six specimens) or posterior half (six specimens) of the
anterior oblique ligament of the ulnar collateral ligament, and after complete
sectioning of the anterior oblique ligament. Laxity was measured in degrees of
valgus angulation in different positions of elbow flexion and forearm
Results: There were no significant differences in valgus laxity with
respect to elbow flexion within each condition. Overall, for both groups of
specimens (i.e., specimens in which the anterior or posterior half of the
anterior oblique ligament was cut), neutral forearm rotation resulted in
greater valgus laxity than pronation or supination did (p < 0.05).
Transection of the anterior half of the anterior oblique ligament did not
significantly increase valgus laxity; however, transection of the posterior
half resulted in increased valgus laxity in some positions. Full transection
of the anterior oblique ligament significantly increased valgus laxity in all
positions (p < 0.05).
Conclusions: The results of this in vitro cadaveric study
demonstrated that forearm rotation had a significant effect on varus-valgus
laxity. Laxity was always greatest in neutral forearm rotation throughout the
ranges of elbow flexion and the various surgical conditions.
Clinical Relevance: The information obtained from the present study
suggests that forearm rotation affects varus-valgus elbow laxity. Additional
investigation is warranted to determine if forearm rotation should be
considered in the evaluation and treatment of ulnar collateral ligament
injuries of the elbow joint.