Tag Archive | Cobb angle

Mehta Casting for Early-Onset Scoliosis: Predictors of Success

The treatment of early-onset scoliosis with Mehta casting is a long process, but if successful, it can delay or obviate the need for surgery. In the September 4, 2019 issue of JBJS, Fedorak et al. examine outcomes among 38 patients (mean age of 24 ± 15 months at time of first casting) who were treated with Mehta casting and followed for a mean of 8 ± 2 years. The retrospective review identified differences between patients who had a Cobb angle ≤15° (improvement group) at the most recent follow-up and those who had a Cobb angle of >15° (no-improvement group).

Forty-nine percent of children had achieved and maintained scoliosis of ≤15° at the time of the most recent follow-up, and 73% were improved by at least 20°, although 3 children ended up relapsing after meeting recommended criteria for discontinuation of casting. There was no significant difference in thoracic-height gain between the groups, demonstrating that even when scoliosis was not corrected, growth was maintained during cast treatment.

Patients in the improvement group had a mean age of 18.9 ± 12 months and scoliosis of 48.2° ± 14° at the initiation of treatment. Here are 3 additional factors that were associated with a greater likelihood of scoliosis of ≤15°:

  • A lower pre-treatment Cobb angle and traction Cobb angle
  • A smaller rib-vertebral angle difference on first-in-cast radiograph
  • A lower Cobb angle on first-in-cast radiograph

The authors note that although this study analyzed longer-term follow-up data than most other similar investigations, “treatment of early-onset scoliosis is not truly finished until skeletal maturity has been reached.”

3-D Imaging Provides More Accurate Picture of Scoliosis Deformities

Scoliosis is a three-dimensional deformity (coronal, axial, and sagittal), so it makes sense that a 3-D imaging method for evaluating the condition and measuring the impact of surgical correction would outperform traditional two-dimensional imaging techniques. That’s exactly what Newton et al. found in their Level II diagnostic study in the October 21, 2015 edition of The Journal of Bone & Joint Surgery.

The authors analyzed 3-D and 2-D images from 120 patients with adolescent idiopathic scoliosis (AIS), before and after surgery with segmented thoracic pedicle-screw instrumentation. The mean preoperative Cobb angle on the standard 2-D view was 55° ± 10°, while on the 3-D view it was 52° ± 9° (p ≤ 0.001). The mean T5-T12 kyphosis on the 2-D view measured 18° ± 13° preoperatively and 27° ± 6° postoperatively, while the mean T5-T12 kyphosis on the 3-D view measured 6° ± 14° preoperatively and 26° ± 6° postoperatively. The difference between the 2-D and 3-D measurements of T5-T12 kyphosis strongly correlated with apical vertebral rotation.

The significant preoperative overrepresentation of the T5-T12 kyphosis on standard 2-D imaging compared with 3-D assessments led the authors to conclude that “the sagittal profile evaluated by the standard lateral view is unreliable and often results in a false sense of thoracic kyphosis.” They go on to claim that “measurement with the 3-D, segmental local vertebral approach can be a useful, surgeon-oriented method for evaluating the deformity of scoliosis as well as the correction associated with surgical treatment.”