Correlation of Radiographic, Clinical and Patient Assessment of Shoulder Balance Following Fusion Versus Non-Fusion of the Proximal Thoracic Curve in Adolescent Idiopathic Scoliosis

St. Louis, MO, USA

INTRODUCTION: Traditionally, radiographic features of a structural proximal thoracic (PT) curve have been T1 tilt, PT Cobb angle and PT side bending Cobb, however, these do not always correlate with clinical shoulder balance.

PURPOSE: To correlate radiographic and clinical features of shoulder balance and the PT curve with patient satisfaction outcomes at a minimum 2-yr follow-up.

METHODS: 109 pts (single surgeon) with AIS and a PT curve of greater than or equal to 20° (ave 32°, range 20-78°) were evaluated in terms of shoulder balance and curve flexibility/correction. Four groups were analyzed: Group 1 - PSF to T2 (PT curve included, n=23), Group 2 - PSF to T3 (PT curve partially included, n=24), Group 3 - PSF to t4 or T5 (PT curve not included, n=21) and Group 4 - ASF to T5 or T6 (PT not included, n=41). PT, MT and TL-L coronal, side bending (SB) and sagittal Cobb measurements were assessed preop, 1 week postop and min. 2-yr postop (ave 3.2 yrs, range 2.0-7.6 yrs). In addition to T1 tilt, clavicle angle (angle of tangential apical line connecting clavicles), coracoid height, trapezius area (horizontal distance of the T2 pedicle to second rib-clavicle intersection) first rib-clavicle height (vertical distance of first rib apex to superior clavicle), and PT, MT and TL-L AVT. Shoulder asymmetry as measured by the radiographic soft tissue shadow was graded as balanced (‹ 1 cm), slight (1-2 cm), moderate (2-3 cm) or significant (› 3 cm). A postop patient questionnaire addressed shoulder balance and overall appearance at most recent follow-up.

RESULTS: Radiographic: Preop PT measurements correlating with postop shoulder balance (p ‹ 0.05) included the clavicle angle (3/4 groups with a trend toward statistical significance in the 4th group), coracoid height (2/4 groups), preop MT curve (2/4 groups) and the preop MT SB (2/4 groups). All other measurements, including T1 tilt, did not correlate with postop shoulder balance. PT curve correction was greatest in Group 1 - PSF to T2 (12° ave) and Group 4 - ASF to T5 or T6 (12°).

Clinical: Shoulder balance improved in all four groups (range 0.38-1.00 grades). There was no difference in shoulder balance between groups (p=0.2723).

Patient Assessment: All 4 groups reported improvement in self perceived shoulder balance (22% - no change, 41% - improved 1 grade, 20% - improved 2 grades, 16% - improved 3 grades). No patient reported worsening of shoulder balance. There was no significant difference between the 4 groups.

CONCLUSIONS: The clavicle angle, not T1 tilt or PT side bending Cobb, provided the best preop radiographic prediction of postop shoulder balance. In each of the 4 groups, postop shoulder balance and clinical appearance also improved and correlated with patient postop assessments. Interestingly, spontaneous PT curve correction following an ASF was the same as instrumented PT curve correction following PSF to T2.