The Effect of Humeral Rotation on Elbow Range-of-Motion Measurements
In 84 patients (85 elbows), a standard goniometer was used to measure elbow flexion and extension with the forearm in 2 positions: full supination (humeral condyles parallel to floor) and neutral forearm rotation (ulnohumeral joint in relative internal rotation). All measurements were made by the same surgeon with a standardized technique.
Mean absolute difference in elbow extension measurements was 8°. There was no difference in flexion between measurement positions. Mean difference between neutral and supinated measurements was 6° in extension. There was no difference in flexion for patients with contractures between 0° and 29°. In patients with flexion contractures of more than 30°, mean difference between neutral and supinated measurements was 12° in extension; there was no difference in flexion. Elbow goniometer extension measurements taken in neutral humeral rotation underestimated the degree of elbow hyperextension and elbow flexion contracture.
We recommend taking elbow flexion arc measurements in the true plane of motion, with the humerus externally rotated by fully supinating the forearm, such that the distal humeral condyles are parallel to the floor.
Elbow motion is crucial for activities of daily living and full function of the upper extremity.1 Measuring the elbow flexion arc accurately and consistently is an important part of the physical examination of patients with elbow pathology. Orthopedic surgeons rely on these measurements to follow patients over time, and they often base their treatment decisions on the range and progression/regression of motion arc.
In the clinical setting, elbow range of motion (ROM) is commonly measured with a handheld goniometer.2,3 The literature also suggests that goniometric measurements are highly reliable in the clinical setting and that intrarater reliability of elbow ROM measurements is high.2-4 Despite the routine use and clinical importance of flexion arc assessment, there is no universal recommendation regarding optimal measurement position. Textbooks and journal articles commonly do not specify arm position at time of elbow ROM measurements,5-8 and a literature review found no studies directly addressing this issue.
From a biomechanical standpoint, humeral rotation is often affected by forearm pronosupination position. Although forearm pronosupination is a product of the motion at the radioulnar joints, forearm position during elbow flexion arc measurement can influence the relationship of the distal humeral intercondylar axis to the plane of measurement. Full forearm supination rotates the distal humeral intercondylar axis externally to a position parallel to the floor and in line with the plane of measurement. Humeral rotation with the forearm in neutral pronosupination places the humeral condyles internally rotated relative to the floor. Therefore, for the purposes of this study, we defined full humeral external rotation and true plane of ulnohumeral motion as full forearm supination, and relative humeral and ulnohumeral joint internal rotation as neutral pronosupination.
Because of the potential for elbow ROM measurement changes caused by differences in the motion plane in which measurements are taken, some have advocated taking flexion arc measurements with the arm in full supination to allow measurements to be taken in the true plane of motion. We hypothesized that elbow flexion arc measurements taken with the forearm in neutral rotation would underestimate the extent of elbow flexion contractures compared with measurements taken in full supination.
Materials and Methods
This study received institutional review board approval. Eighty-four patients who presented with elbow dysfunction to a single shoulder and elbow orthopedic surgeon enrolled in the study. Skeletally immature patients and patients with a fracture or other disorder that prohibited elbow ROM were excluded. A standard goniometer was used to measure elbow flexion and extension with the humerus in 2 positions: full external rotation and neutral rotation.
All goniometer measurements were made by the same surgeon (to eliminate interobserver reliability error) using a standardized technique with the patient sitting upright. The goniometer was positioned laterally with its center of rotation over the lateral epicondyle, aligned proximally with the humeral head and distally with the center of the wrist. Measurements were obtained sequentially with the hand in both positions. For external rotation measurements, the patient’s arm was fully supinated to bring the humeral condyles parallel to the floor. For neutral positioning, the patient’s arm was placed in the “thumb-up” position with the hand perpendicular to the horizontal axis of the floor (Figures 1A–1C).
Data collected included demographics, diagnosis, hand dominance, affected side, and elbow ROM measurements with the hand in the 2 positions. These data were compiled and analyzed for all patients and then stratified into 3 groups by extent of elbow flexion contracture in the supinated position (group 1, hyperextension; group 2, 0°-29° elbow extension; group 3, ≥30° flexion contracture).
Statistically, paired t tests were used to identify differences between the 2 elbow ROM measurement methods. P < .05 was considered significant.
Results
Eighty-four (44 male, 40 female) consecutive patients (85 elbows) met the inclusion and exclusion criteria. Mean age was 51 years (range, 19-84 years). Seventy-six patients were right-handed, 7 were left-handed, and dominance was unknown in 1 patient. The right elbow was affected in 45 patients, the left in 38, and both in 1 patient. There were 25 different diagnoses, the most common of which was lateral epicondylitis; 7 patients had multiple disorders (Table).
The first set of data, elbow ROM measurements, was taken with all 84 patients analyzed as a single group. In neutral humeral rotation, mean elbow extension was 14° (range, 10°-72°), and mean elbow flexion was 134° (range, 72°-145°). In external rotation, mean elbow extension was 20° (range, 12°-87°), and mean elbow flexion was 134° (range, 72°-145°). For the group, mean absolute difference in elbow extension was 8° (range, 0°-30°; P < .0001); there was no difference between external rotation and neutral rotation in flexion (Figure 2).
