Assessment of rib hump deformity correction in adolescent idiopathic scoliosis with or without costoplasty using the double rib contour sign.

STUDY DESIGN: Level III-therapeutic study.

OBJECTIVE: The purpose of this study was to determine whether the addition of costoplasty in adolescent idiopathic scoliosis surgery improved correction of the rib hump deformity.

BACKGROUND: Trunk deformity is comprised of vertebral rotation, posterior vertebral element, and rib deformities. Surgical correction of the rotational deformity has been performed by segmental spinal instrumentation with vertebral derotation, but complete correction of the rib hump by derotation is rarely achieved.

METHODS: A multicenter registry database for adolescent idiopathic scoliosis was reviewed with the inclusion criteria of Lenke type I curves treated with posterior spinal fusion with or without costoplasty, instrumented with pedicle screws or hybrid constructs, with a minimum follow-up of 2 years. The first group (group I) was treated with pedicle screws, direct vertebral rotation, and no costoplasty, whereas the second group (group II) was treated with pedicle screws, vertebral rotation, and costoplasty. The rib index (RI), calculated from the double rib contour sign, and Cobb angle were measured radiographically and compared between groups.

RESULTS: The groups comprised 36 subjects in group I and 40 subjects in group II. The mean preoperative Cobb angles for groups I and II were 49.7 and 49.8 degrees, respectively, whereas the mean postoperative Cobb angles were 10.2 and 10.9 degrees, respectively. There was no difference in preoperative and postoperative values when comparing both groups (P=0.48 and 0.96, respectively). Before spine surgery, RI for groups I and II was 1.61 and 1.80, respectively. Postoperatively, the rib indices were 1.39 for group I and 1.29 for group II. These differences were found to be statistically significant (P=0.002 and 0.006, respectively). The amounts of correction of RI were 0.23 and 0.51 for groups I and II, respectively. This difference was found to be statistically significant (P<0.0001). The correction percentages were 13.7% and 28.3%, respectively. This difference was also found to be statistically significant (P<0.0001).

CONCLUSIONS: Costoplasty combined with pedicle screws and vertebral derotation may significantly improve rib hump deformity as opposed to pedicle screws and vertebral derotation alone.