Estimating the Elbow Carrying Angle With an Electrogoniometer: Acquisition of Data and Reliability of Measurements
Abstract
The carrying angle value and its pathological variations are important in the management of elbow fractures and in the diagnosis of diseases of lateral and medial epicondyles. Few investigators have studied the carrying angle in-vivo. In clinical practice, the carrying angle of the elbow is assessed by radiographs or goniometers, to evaluate reduction of distal humerus or radial head fractures and epicondyles pathologies.
This article presents a noninvasive procedure to estimate the carrying angle in full-extension by a 3D digitizer suitable for orthopedic applications. We also performed an experimental analysis of reliability, by comparing repeated acquisitions both by the same operator and by two different operators. Two operators performed the acquisitions on 37 healthy patients. Mean carrying angle was 12.7°±3.8°. Women and men presented a mean carrying angle value of 12.90°±3.95° and 12.40°±3.64°, respectively. Right and left carrying angle values were respectively 12.55°±3.50° and 12.81°±4.11°. Neither limb side (P=0.76) nor gender significant differences (P=.57) were found. Mean values were consistent to the literature, interoperator repeatability was good (ICC=0.7) and intraoperator repeatability excellent (ICC=0.85). A further advantage of this methodology is the automatic inclusion of the calculation of the flexion and pronation angle. This evaluation was never included in previous approaches and it could be useful in clinical and rehabilitative fields.
Illustration showing the anatomic landmark points and reference axes for measuring the carrying angle. X, Y, and Z identify the reference system of the arm and x, y, and z identify the reference system of the forearm.
Frequency histogram showing the carrying angle values and normal distribution curve.
