In vivo 3D Kinematics of Axis of Rotation in Malunited Monteggia Fracture Dislocation

Abstract

Background: Normal elbow joint kinematics has been widely studied in cadaver, whilst in vivo study, especially of the forearm, is rare. Our study analyses, in vivo, the kinematics of normal forearm and of malunited forearm using a three-dimensional computerized simulation system. Methods: We examined 8 patients with malunited Monteggia fracture and 4 controls with normal elbow joint. The ulna and radius were reconstructed from CT data placing the forearm in three different positions; full pronation, neutral, and full supination using computer bone models. We analyzed the axis of rotation 3-dimentionally based on the axes during forearm rotation from full pronation to full supination. Results: Axis of rotation of normal forearm was pitch line, with a mean range of 2 mm, from full pronation to full supination, connecting the radial head center proximally and ulnar fovea distally. In normal forearm, the mean range was 1.32 mm at the proximal radioulnar joint and 1.51 mm at the distal radioulnar joint. However in Monteggia fracture patients, this range changed to 7.65 mm at proximal and 4.99 mm at distal radoulnar joint. Conclusions: During forearm rotation, the axis of rotation was constant in normal elbow joint but unstable in malunited Monteggia fracture patients as seen with radial head instability. Therefore, consideration should be given not only to correcting deformity but also to restoring AOR by 3D kinematics analysis before surgical treatment of such fractures. (Clin Shoulder Elb 2014;17(1):25-30)

In vivo 3-dimensional Kinematics of Cubitus Valgus after Non-united Lateral Humeral Condyle Fracture

“…First, screw axis, which is determined in terms of rotation around and translation along one unique axis, i.e., the 3D deformity axis, using the screw displacement axis technique, was calculated during flexion, and we defined it as the axis of rotation (AOR). 4,5) Movements of AOR during flexion in groups were compared. We then calculated the rotational axis of the ulno-humeral joint in the position from full extension to full flexion.…”

“…[1][2][3] However, a few studies have reported the use of 3D imaging in the upper extremity, including the hand and elbow. 4,5) In general, if patients with nonunion of the lateral humeral condyle fracture have no symptoms, there is no need for surgical treatment. However, nonunion of the lateral humeral condyle fracture combined with cubitus valgus deformity and instability often results in pain in the elbow, along with ulnar neuropathy and cosmetic problems.…”