Radiographic measures of thoracic kyphosis in osteoporosis: Cobb and vertebral centroid angles.

OBJECTIVE: Several measures can quantify thoracic kyphosis from radiographs, yet their suitability for people with osteoporosis remains uncertain. The aim of this study was to examine the validity and reliability of the vertebral centroid and Cobb angles in people with osteoporosis. DESIGN AND PATIENTS: Lateral radiographs of the thoracic spine were captured in 31 elderly women with osteoporosis. Thoracic kyphosis was measured globally (T1-T12) and regionally (T4-T9) using Cobb and vertebral centroid angles. Multisegmental curvature was also measured by fitting polynomial functions to the thoracic curvature profile. Canonical and Pearson correlations were used to examine correspondence; agreement between measures was examined with linear regression. RESULTS: Moderate to high intra- and inter-rater reliability was achieved (SEM = 0.9-4.0 degrees ). Concurrent validity of the simple measures was established against multisegmental curvature (r = 0.88-0.98). Strong association was observed between the Cobb and centroid angles globally (r = 0.84) and regionally (r = 0.83). Correspondence between measures was moderate for the Cobb method r = 0.72), yet stronger for the centroid method (r = 0.80). The Cobb angle was 20% greater for regional measures due to the influence of endplate tilt. CONCLUSIONS: Regional Cobb and centroid angles are valid and reliable measures of thoracic kyphosis in people with osteoporosis. However, the Cobb angle is biased by endplate tilt, suggesting that the centroid angle is more appropriate for this population.

Computer-aided video analysis of vertebrofemoral motion during toe touching in healthy subjects.

OBJECTIVE: Despite widespread use of the toe touch test, the relative contribution from vertebral and hip movements has not been clearly established, largely because of unsatisfactory measurement techniques. This study aimed to reinvestigate the kinematics of toe touching by combining computerized videotape analysis with a new model of reference marker placement. METHOD: Twenty-two subjects were videotaped during active toe touching from upright standing. Computer software was then used to derive the sagittal thoracic, lumbar, and hip angles at .02-sec intervals throughout the movement. RESULTS: Hip flexion was directly proportional to toe touch distance (TTD) (r2 = .71) but not lumbar flexion (r2 = .17) or thoracic (r2 = .20) excursion. On average there was .8 degree of thoracolumbar flexion for every 1 degree of hip flexion; however, there were wide variations between subjects. In 19 of 22 subjects the thoracic spine flexed and extended relatively equal amounts during the test resulting in a small total thoracic excursion of 4.8 degrees flexion in unsuccessful toe touchers and 4.0 degrees extension in successful toe touchers. CONCLUSION: The separate contributions of hip, lumbar, and thoracic mobility to toe touching or any other vertebrofemoral motion can only be accurately determined by a measurement strategy that uses the plane of the pelvis to separate vertebral from hip motion and uses tangents at the limits of the thoracic and lumbar regions to separate lumbar from thoracic motion. Using this model the authors found that TTD is not a reliable indicator of either vertebral or hip mobility.

How should an unconscious person with a suspected neck injury be positioned?

INTRODUCTION: Awareness of the risk of spinal-cord damage in moving an unconscious person with a suspected neck injury into the "lateral recovery position," coupled with the even greater risk of inadequate airway management if the person is not moved, has resulted in a suggested modification to the lateral recovery position for use in this circumstance. HYPOTHESIS: It is proposed that the modification to the lateral recovery position reduces movement of the neck. In this modification, one of the patient's arms is raised above the head (in full abduction) to support the head and neck. The position is called the "HAINES modified recovery position." HAINES is an acronym for High Arm IN Endangered Spine. METHODS: Neck movements in two healthy volunteers were measured by the use of video-image analysis and radiographic studies when the volunteers were rolled from the supine position to both the lateral recovery position and the HAINES modified recovery position. RESULTS: For both subjects, the total degree of lateral flexion of the cervical spine in the HAINES modified recovery position was less than half of that measured during use of the lateral recovery position (while an open airway was maintained in each). CONCLUSION: An unconscious person with a suspected neck injury should be positioned in the HAINES modified recovery position. There is less neck movement (and less degree of lateral angulation) than when the lateral recovery position is used, and, therefore, HAINES use carries less risk of spinal-cord damage.