Surgical assessment of the proximal thoracic curve in adolescent idiopathic scoliosis

Abstract

Existing predictive signs as available in current literature may miss potential proximal thoracic (PT) curve deterioration and shoulder imbalance, following selective main thoracic (MT) curve correction in adolescent idiopathic scoliosis (AIS). The present study is an attempt to evaluate and complement these signs, through a retrospective study of 56 AIS patients who underwent correction and fusion from 1986 till 2003 with follow-up 4-16 years. Forty-nine had fusion of MT curve, 7 of MT and PT. Cotrel-Dubousset instrumentation in 45, Luque in 12. Preoperative data: MT 50 degrees (40 degrees -80 degrees), PT 25 degrees (0 degrees -50 degrees), shoulder elevation from -4 cm (right) to 2 cm (left), clavicle angle from -14 degrees to 5 degrees , PT bending correction from 0 to 100% and T1 tilt from -15 degrees to 14 degrees . We introduced the first rib index (FRI), i.e., the difference between the diameter of right and left first rib arch as a percentage of the sum of both diameters, averaging from -22.7 to 14.3%. (Minus signs refer to or predict right, while positive left shoulder elevation.) Evaluation included all predictive parameters as related principally to postoperative left shoulder elevation > or =1 cm, patient satisfaction and surgeon fulfillment. Postoperative correction MT curve 53% (23-83%) and PT 35% (0-100%). One progressive paraplegic started 40 min following normal wake-up test. Immediate decompression, full recovery. Three cases with wound infection recovered after late removal of instrumentation. Loss of correction > or =10 degrees in five. Fifteen had postoperative persisting left shoulder elevation > or =1 cm. Seven of these expressed dissatisfaction. Statistically FRI proved valuable predictive factor always in combination with previously described signs. We concluded that a postoperative left shoulder elevation >/=2 cm is a potential cause of dissatisfaction and may be prevented with thorough validation of all predictive signs, principally the FRI.

Does patient perception of shoulder balance correlate with clinical balance?

“…Shoulder imbalance due to elevated left shoulder is a topic frequently found in the literature. Consequently, different treatment strategies have been designed to improve it [21,22]. Such imbalance is often associated with those types of scoliosis with a structured upper thoracic curve, i.e.…”

Is neck tilt and shoulder imbalance the same phenomenon? A prospective analysis of 89 adolescent idiopathic scoliosis patients (Lenke type 1 and 2)

“…Qiu et al [31] also demonstrated that discrepancy often exists between radiographic shoulder balance and cosmetic shoulder balance in AIS patients with double thoracic curve. Smyrnis et al [11] introduced the first rib index (FRI) as a predictor for shoulder imbalance.…”

“…The incidence of shoulder imbalance has been reported to be between 23 and 32 % [11][12][13]. Shoulder imbalance is associated with T1 tilt, pre-operative shoulder height, first rib inclination, coracoid height difference, clavicle angle, radiological shoulder height, clavicle\rib intersection distance and pre-operative proximal thoracic (PT) curve [14][15][16].…”

Clinically orientated classification incorporating shoulder balance for the surgical treatment of adolescent idiopathic scoliosis

“…Angles subtended with the left shoulder up are positive and those with the left shoulder down are negative. By convention, we define symmetric shoulders as having a clavicle angle as less than 2° [16].…”