Research Reviews

Although the trigger for initiation of spinal curvature in patients with adolescent idiopathic scoliosis remains unclear, there is increasing recognition of features that contribute to progression of the curvature in the growing spine.  In a study published in The Bone & Joint Journal, researchers describe their finding of asymmetrical growth centers in scoliotic vertebrae, with delayed appearance of the epiphyseal ring ossification center on the concave side of apical and peri-apical vertebrae, but no difference in the rate of appearance of the ossification centers in the end vertebrae.  They noted these findings by analysis of computed tomography scans in both structural and non-structural curves, and explained their results by noting the asymmetrical loading force on the vertebral body in the presence of deformity.  Because the epiphyseal ring ossification center, also known as the ring apophysis, contributes to the formation of the vertebral endplate, the researchers concluded that this asymmetrical growth plays a role in the progression of scoliosis.  The article is titled, “Asymmetrical ossification in the epiphyseal ring of patients with adolescent idiopathic scoliosis.”

In an article published in The Bone & Joint Journal titled “The role of femoral neck anteversion in the development of osteoarthritis in dysplastic hips“, researchers examined the CT scans of 36 patients with unilateral osteoarthritis and bilateral hip dysplasia. They calculated correlation coefficients between various geometric measures in the hip and the presence of osteoarthritis. They noted a slightly higher average femoral neck anteversion angle (19 degrees compared to 12 degrees) in the arthritic hips, despite similar lateral center-edge angles (12.2 versus 13.3) and concluded that these findings suggest an increased femoral neck anteversion angle is an important component of the increased risk of osteoarthritis in hips with acetabular dysplasia. However, as their analysis was done retrospectively and osteoarthritis was already present, there was no information to aid in determining whether treatment of the prearthritic dysplastic hip should target femoral anteversion in addition to addressing acetabular coverage. In addition, their univariable correlation coefficients were similar for both anterior acetabular sector angle and femoral neck anteversion angle, implying that axial estimates of acetabular coverage should be considered in addition to the lateral center edge angle.  More research is required in this area.

In a multicenter prospective cohort study of patients undergoing treatment for Scheuermann kyphosis, the characteristics associated with surgical and non-surgical treatment were evaluated using radiographic and anthropomorphic measures as well as patient reported outcomes on the Scoliosis Research Society questionnaire. The authors noted that among 150 patients enrolled in this study, 77 patients were treated nonoperatively and 73 were treated with surgery. The factors associated with a selection of surgical treatment were increased age, higher BMI, greater T2-12 kyphosis (but no difference in maximal sagittal Cobb angle), and increased pelvic incidence and pelvic tilt, as well as scores indicating worse pain and appearance. The authors concluded that radiographic features are likely not the sole factor under consideration. The study was titled, “What are the Indications for Spinal Fusion Surgery in Scheuermann Kyphosis?” and was published in the Journal of Pediatric Orthopaedics.

In an article published ahead of print in the Journal of Pediatric Orthopaedics, titled “Results of Casting in Severe Curves in Infantile Scoliosis,” Stasikelis and Carpenter report the outcome of serial derotational casting for children with severe infantile scoliosis (curves greater than 50 degrees). They report that even at this magnitude, the treatment led to curve resolution in nine of 26 idiopathic cases and 3 of 18 non-idiopathic cases, and in all cases the casting was effective in delaying surgical procedures of instrumentation. This study suggests that the option of EDF casting may be considered a useful strategy even with later diagnosis or initiation of treatment in cases of infantile scoliosis.

In the article, “Prognosis for Congenital Scoliosis Due to a Unilateral Failure of Vertebral Segmentation,” McMaster and McMaster published results of 171 patients from the Scottish National Spine Deformity Center, Royal Hospital for Sick Children, Edinburgh. Among these patients, the presence of congenital scoliosis caused by a unilateral unsegmented bar was associated with a 2-3 degree per year progression of scoliosis prior to age 10 years, and a more rapid progression after age 10 years of 4-7 degrees. In this study, 36 patients had immediate surgery, and an additional 74 patients underwent later surgery. The authors noted that the prognosis depends on multiple factors, including the remaining growth, the extent and location of the unsegmented vertebral structures, and the existing growth imbalance. The article was published in The Journal of Bone & Joint Surgery.

 

In a study titled “Effect of Compliance Counseling on Brace Use and Success in Patients with Adolescent Idiopathic Scoliosis” in The Journal of Bone & Joint Surgery, Dr. Lori Karol and colleagues demonstrated that counseling adolescents about their compliance with the use of a scoliosis brace improved their use of the brace and also decreased the chance of scoliosis curve progression. The authors were able to validate the amount of brace wear for each patient in the study by using a sensor embedded within the scoliosis brace. For the counseling group, patients were informed at each visit about the data from the compliance monitor. For the comparison group, the physician, orthotist, and patient were not given access to the data about compliance. At the end of the study, comparison of data between groups showed that patients who were counseled wore their brace 3 hours more per day than the group that was not aware of the data. In addition, 36% of patients in that group progressed to curves greater than or equal to 50 degrees or to surgery, compared with only 25% of patients in the group with access about compliance data. The authors recommend that this type of compliance monitoring be incorporated into standard brace management protocols.

Controversy surrounds the question of determining when a selective thoracic fusion should be performed for adolescent idiopathic scoliosis with a Lenke Type 1C curve pattern. There is a risk for residual deformity when the lumbar curve is not fused, and multiple factors influence the final coronal alignment, including the coronal alignment prior to surgical treatment. In a paper from the Harms Study Group titled, “Is Decompensation Preoperatively a Risk in Lenke 1C Curves?“, the effect of coronal alignment prior to surgery on postoperative alignment was investigated. Decompensation was defined as a difference between the C7 and center sacral lines of greater than 2 centimeters. The authors found that decompensation to the left was common in this type of scoliosis, and that such decompensation did not always spontaneously correct after a selective thoracic fusion. This knowledge should be an important component of the preoperative planning and discussion. The research was published in the journal Spine.

 

In patients with acetabular dysplasia or developmental dysplasia of the hip, the biomechanics of edge loading at the acetabular rim may lead to clinically symptomatic labral tears. The preferred treatment for acetabular dysplasia in most adolescents and young adults, in the absence of significant degenerative joint disease, is a periacetabular osteotomy, which has been shown to improve the longevity of the hip joint. The question of whether or not to treat the labral tear while performing the periacetabular osteotomy was addressed in a retrospective comparitive study.

The authors found no difference in the clinical outcomes or the need for reoperation between patients who underwent concomitant treatment of the labral tear with the periacetabular osteotomy compared to those who underwent periacetabular osteotomy without treatment of the labral tear. Compared with patients who had no labral tear, both groups with the labral tear were slightly more likely to later require treatment of the labrum. The paper, “Do labral tears influence poor outcomes after periacetabular osteotomy for acetabular dysplasia?“, was published in The Bone and Joint Journal.

The presence of decreased bone density can hypothetically alter the growth or remodeling of bone in children, and some researchers have reported an association with adolescent idiopathic scoliosis.  However, in a paper in the journal Spine, researchers contended that comparing adolescents with scoliosis to those without scoliosis, lower body mass index was a more important determinant of decreased bone density, and among the 89 patients studied, none of them met the criteria for the definition of osteoporosis that was established by the International Society for Clinical Densitometry.  The paper is titled, “Adolescents With Idiopathic Scoliosis Are Not Osteoporotic.”

Spinal fusion in adolescent idiopathic scoliosis requires the use of bone grafting material, and options include autologous bone graft, which may be obtained from the iliac crest, or allograft bone material.  Many surgeons have asked whether harvesting autologous bone graft (in some cases, through a separate incision) will affect the clinical outcomes either in satisfaction with appearance or through donor site morbidity.  Using a prospective multi-center database, Crawford et al. compared the results of the Scoliosis Research Society (SRS)-22 questionnaire at 2 years after surgery in 342 patients who underwent iliac crest bone graft harvest to 563 patients who did not.  Their findings were published in Spine Deformity, “Outcomes Following Posterior Fusion for Adolescent Idiopathic Scoliosis With and Without Autogenous Iliac Crest Bone Graft Harvesting“.  The authors found that although operative blood loss estimates and operative times were greater when performing iliac crest bone graft during spinal fusion surgery, there was no difference in clinical outcomes measures by two years after surgery.  These findings suggest that autologous iliac crest bone graft remains an acceptable option for spinal fusion in adolescent idiopathic scoliosis.