Significance of chin-brow vertical angle in correction of kyphotic deformity of ankylosing spondylitis patients.
METHODS
A prospective study.


OBJECTIVE
To assess the significance of chin-brow vertical angle in planning and evaluating the correction of kyphotic deformity with ankylosis of the cervical spine in ankylosing spondylitis patients.


BACKGROUND
Accurate assessment and measurement of spinal kyphotic deformity is required when planning treatment and assessing its results.


METHODS
Thirty-four ankylosing spondylitis patients with cervical ankylosis who had undergone pedicle subtraction extension osteotomy for correction of kyphotic deformity were studied. Radiographic assessment for sagittal balance was performed by measuring thoracic kyphosis, lumbar lordosis, the distance between the vertical line on the anterosuperior point of T1 and that of S1, and sacral inclination. Chin-brow vertical angle was measured on the clinical photos of the patients. Clinical outcomes were assessed by a questionnaire.


RESULTS
The preoperative and postoperative chin-brow vertical angles were 35.5 degrees and 1.8 degrees, respectively. Final follow-up radiographs showed an increase in lumbar lordosis from 5.5 degrees to 43.2 degrees (an increase of 37.7 degrees ), and thoracic kyphosis remained stable from 50.4 degrees to 50.2 degrees. Sagittal imbalance significantly improved from 101.5 mm to 12.7 mm. The decreased chin-brow vertical angle correlated negatively with the correction angle. The patients with a chin-brow vertical angle of less than -10 degrees had significantly low scores on horizontal gaze.


CONCLUSIONS
Chin-brow vertical angle was an objective index for evaluating horizontal gaze. Based on the results of this study, measurement of chin-brow vertical angle is recommended for planning correction of kyphosis and accurate evaluation of treatment outcome.
Suk
Kyung-Soo
KS
Department of Orthopaedic Surgery, School of Medicine, Kyung-Hee University, Seoul, Korea. sks111@khmc.or.kr
Kim
Ki-Tack
KT
Lee
Sang-Hun
SH
Kim
Jin-Moon
JM
D000328:Adult; D002680:Chin; D005138:Eyebrows; D005145:Face / Q000473:pathology; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000209:etiology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013167:Spondylitis, Ankylosing / Q000150:complications*; D016896:Treatment Outcome