Abnormal rib count in scoliosis surgery: impact on the reporting of spinal fusion levels.

PURPOSE: Variation in rib numbering has been noted in adolescent idiopathic scoliosis (AIS), but its effect on the reporting of fusion levels has not been studied. We hypothesized that vertebral numbering variations can lead to differing documentation of fusion levels. METHODS: We examined the radiographs of 161 surgical AIS patients and 179 control patients without scoliosis. For AIS patients, the operative report of fusion levels was compared to conventional vertebral labeling from the first thoracic level and proceeding caudal. We defined normal counts as 12 thoracic (rib-bearing) and five lumbar (non-rib-bearing) vertebrae. We compared our counts with data from 181 anatomic specimens. RESULTS: Among AIS patients, 22 (14 %) had an abnormal number of ribs and 29 (18 %) had either abnormal rib or lumbar count. In 12/29 (41 %) patients, the operative report differed from conventional labeling by one level, versus 3/132 (2 %) patients with normal numbering (p < 0.001). However, there were no cases seen of wrong fusion levels based on curve pattern. Among controls, 11 % had abnormal rib count (p = 0.41) compared to the rate in AIS. Anatomic specimen data did not differ in abnormal rib count (p = 1.0) or thoracolumbar pattern (p = 0.59). CONCLUSIONS: The rate of numerical variations in the thoracolumbar vertebrae of AIS patients is equivalent to that in the general population. When variations in rib count are present, differences in numbering levels can occur. In the treatment of scoliosis, no wrong fusion levels were noted. However, for both scoliosis patients and the general population, we suggest adherence to conventional labeling to enhance clarity.

Is there a relationship between thoracic dimensions and pulmonary function in early-onset scoliosis?

STUDY DESIGN: Cross-sectional retrospective analysis. OBJECTIVE: To examine the degree of correlation between thoracic dimension outcome measures and pulmonary function in early-onset scoliosis (EOS). SUMMARY OF BACKGROUND DATA: Change in thoracic dimension (TD) measurements and spine length are commonly reported outcome measures after treatment for EOS. Although ultimately improving or maintaining pulmonary function is the goal of EOS treatment strategies, it is unclear whether commonly reported 2-dimensional TD measurements represent good predictors of pulmonary function. METHODS: A cross-sectional analysis of patients including all diagnoses obtained from 2 EOS databases containing TD measurements and pulmonary function data was performed. Relationships between individual TD measurements and pulmonary function measurements were assessed using the Pearson correlation analysis. TD measurements (pelvic inlet width, T1-T12 height, T1-S1 height, and coronal chest width) and standard pulmonary function measurements were compared. TD percentiles normalized for pelvic inlet width were also calculated and correlated with pulmonary function measurement percentiles. Univariate and multivariate linear regression analyses determined whether TD measurements could predict pulmonary function. RESULTS: There were 121 patients (65 females, 56 males) in the study. Mean age at evaluation was 9.3 years (range, 2.7-18.1 yr). T1-T12 height, T1-S1 height, maximal chest width, and pelvic inlet width were all significantly correlated with forced air volume expelled in 1 second, total forced air volume, and total lung capacity (correlation coefficients [r] 0.33-0.61; all P<0.001). T1-T12 predicted percentile (normalized for pelvic width) was significantly correlated with forced air volume expelled in 1 second and total forced air volume predicted percentiles (r=0.32, P<0.001 and r=0.27, P=0.004, respectively). Regression analysis determined that T1-T12 percentile was a significant predictor of forced air volume expelled in 1 second percentile and total forced air volume percentiles. Regression analysis found no predictive factors of total lung capacity percentile. CONCLUSION: Traditional 2-dimensional TD measurements (T1-T12 height) used to measure outcomes in EOS can be used as weak predictors of pulmonary function outcome. However, better outcome measures need to be developed, such as 3-dimensional and dynamic measurements. LEVEL OF EVIDENCE: 3.

Gain in spinal height from surgical correction of idiopathic scoliosis.

BACKGROUND: A relationship between spinal distraction and correction of the curvature of scoliosis has long been recognized. While attempts have been made to define the height that is lost with progression of scoliosis, much less information is available to define the height that is gained as a result of surgical correction of the curve and to quantify additional spinal growth after spine fusion. METHODS: The present study included 116 patients (mean age, 14.8 years) who underwent spinal instrumentation and fusion for the treatment of idiopathic scoliosis. The study group included ninety-one female patients and twenty-five male patients; all Lenke curve types were represented. The Cobb angle and the T1-L5 spinal height were evaluated on preoperative, postoperative, and two-year follow-up radiographs. Kyphosis, lordosis, and T1-L5 spinal length were measured on lateral radiographs. The Scoliosis Research Society (SRS) questionnaire was completed prior to surgery and at each visit. Multivariate linear regression defined the relationship between spinal height gain, Cobb angle correction, and other variables as well as final spinal height. RESULTS: The mean spinal height gain due to surgery was 27.1 mm (median, 25.1 mm; interquartile range, 14.5 to 37.9 mm; range, -3.8 to 66.1 mm). The magnitude of curve correction (mean, 38.2°; range, 6° to 67°), the number of vertebral levels fused (mean, 9.9; range, three to sixteen), and the preoperative stature (standing height) of the patient were all significant predictors (p < 0.01) of spinal height gain (R2 = 0.8508 for multivariate model). The mean changes in kyphosis and lordosis were small and were not significant predictors. An additional 4.6 mm of mean spinal height was gained at the time of the two-year follow-up; this increase was significantly related to young age, male sex, shorter fusions, and a Risser stage of ≤2 at the time of surgery (p < 0.01 for all in multivariate analysis). The SRS-30 scores improved significantly (p < 0.0001), independent of spinal height gain. CONCLUSIONS: Patients undergoing surgical correction of idiopathic scoliosis gain substantial height related to the magnitude of surgical correction, the number of levels fused, and preoperative stature. Continued spine growth by two years after surgery is associated with shorter fusions, skeletal immaturity, young age, and male sex. Height gain is a quantifiable outcome of the surgical correction of scoliosis.

Prediction of thoracic dimensions and spine length on the basis of individual pelvic dimensions: validation of the use of pelvic inlet width obtained by radiographs compared with computed tomography.

STUDY DESIGN: Retrospective review. OBJECTIVE: To validate the pelvic inlet width (PIW) measurement obtained on radiograph as an independent standard used to correlate with thoracic dimensions (TDs) in treated and untreated patients with early-onset scoliosis. SUMMARY OF BACKGROUND DATA: In children with early-onset scoliosis, the change in TD and spine length is a key treatment goal. Quantifying this change is confounded by varied growth rates and differing diagnoses. PIW measured on computed tomographic (CT) scan in patients without scoliosis has been shown to correlate with TD in an age-independent manner. METHODS: The first arm included 49 patients with scoliosis who had both a CT scan and pelvic radiograph. Agreement between PIW measurements on CT scan and radiograph was analyzed. The second arm consisted of 163 patients (age, 0.2-18.7 yr), with minimal spinal deformity (mean Cobb, 9.0°) and radiographs in which PIW was measurable. PIW was compared with previously published CT-based TD measurements; maximal chest width, T1-T12 height, and T1-S1 height. Linear regression analysis was used to develop and validate sex-specific predictive equations for each TD measurement on the basis of PIW. Interobserver reliability was evaluated for all measurements. RESULTS: Bland-Altman analysis indicated agreement with no dependence on observed value, but a consistent 8.5 mm (95% CI: 7.2-9.9 mm) difference in CT scan measurement compared with radiographical PIW measurement. Sex and PIW were significantly correlated to each TD measurement (P < 0.01). Predictive models were validated and may be used to estimate TD measurements on the basis of sex and radiographical PIW. Intraclass correlation coefficients for all measurements were between 0.978 and 0.997. CONCLUSION: PIW on radiographs and CT scan correlate in patients with deformity and with spine and TD in patients with minimal deformity. It is a fast, reliable method of assessing growth while lowering patient's radiation exposure. It can be reliably used to assess patients with early-onset scoliosis and the impact surgical treatment has on chest and spinal growth. LEVEL OF EVIDENCE: 3.

Distraction-Based Treatment Maintains Predicted Thoracic Dimensions in Early-Onset Scoliosis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Examination of distraction-based treatment effect on thoracic dimensions in patients compared to predicted individual normal values, at initial treatment and subsequent follow-up after lengthenings. SUMMARY OF BACKGROUND DATA: Change in thoracic dimensions and spine length is an important outcome measure in treatment of children with early-onset scoliosis; however, it is difficult to use to make comparisons between patients and the normal population because of the heterogeneous nature of early-onset scoliosis. METHODS: Early-onset scoliosis patients treated with distraction-based therapy who had radiographic parameters (pelvic inlet width, chest width, and thoracic height) preoperatively, immediately postoperatively, and at a minimum 5-year follow-up were included. Individual thoracic measurements were compared with predicted normal measures based on pelvic inlet width, and expressed as a percentile of predicted measure. RESULTS: Comparisons were made in 41 patients; mean age at time of primary surgery was 4.5 years, and median follow-up was 6.5 years. Thoracic height percentile increased from a mean preoperative value of .78 to a postoperative percentile of .88 (p < .001); at long-term follow-up, it was .85. Absolute thoracic height increased at all 3 time points: 141.6, 159.79, and 203.45 mm, respectively Mean chest width was similar preoperatively (170 mm) and immediately postoperatively (166.5 mm) but increased at latest follow-up (206.9 mm). Chest width percentile was similar at all 3 times (.93, .90, and .91). CONCLUSIONS: Distraction-based treatment increases absolute thoracic height over time. There is significant improvement in the thoracic height percentile normalized after initial surgery, which was maintained over time. Measuring expected gains as a percentile normalized for pelvic width may be a more relevant outcome measure compared with measuring only absolute values.

Scoliosis after chest wall resection.

BACKGROUND DATA: There has been an increased focus on the role of rib abnormalities in the development of scoliosis. Rib resection may influence the development of scoliosis. Although scoliosis has been identified in patients after thoracotomy, most of the currently available information is from case reports. METHODS: We examined records of 37 patients who underwent a chest wall or rib resection for rib lesions at our institution during the period of 1992 to 2005. Adequate data was available in 21 patients. We gathered data on demographic information, location of resection, and changes in curvature after resection based on radiograph or scout CT films at the latest follow-up appointment. RESULTS: Fourteen of 21 patients developed scoliosis with a mean Cobb angle of 25.8° (10°-70°). Eleven of these 14 patients had a progressive spinal deformity after chest wall resection with an average change in curvature of 29° (10°-70°). Eight of those 11 developed a convex toward the resection, while 3/11 developed a convex away from the resection. Seven of the eight patients with resections that included a rib superior to the sixth rib developed scoliosis, while four of 13 with resections below the sixth rib developed scoliosis. CONCLUSION: Patients who have had a rib or chest wall resection are at risk for developing scoliosis, particularly if the resection is performed above the sixth rib.

Spondylolisthesis: Intra-rater and Inter-rater Reliabilities of Radiographic Sagittal Spinopelvic Parameters Using Standard Picture Archiving and Communication System Measurement Tools.

STUDY DESIGN: Reliability analysis. OBJECTIVE: To determine the intra-rater and inter-rater reliability of common sagittal spinopelvic measurements from Digital Imaging and Communications in Medicine images on a commercial Picture Archiving and Communication system for patients with developmental spondylolisthesis. SUMMARY OF BACKGROUND DATA: Computer-aided analysis of digital radiographs has been used in research protocols to define anatomic and positional characteristics of developmental spondylolisthesis. Previous studies have shown poor reliability and weak correlations of manual measurements used in clinical practice with research measurements, which limit the clinical value of prior research. METHODS: Five raters of varying experience measured lateral spinopelvic images of 30 patients with developmental spondylolisthesis. Measurements were repeated after 1 week. Intra-rater and inter-rater reliabilities for each measurement were determined. Measurements were compared with those obtained from a computer-based image enhancement research system. Continuous variables were assessed by analysis of variance, whereas kappa statistics were determined for categorical variables. RESULTS: Excellent intraclass correlations (ICC)s were obtained for all radiographic measurements based on linear values (slip ratio and C7 balance) as well as pelvic tilt angle. Angular measurements had good to excellent ICC but were weaker when the sacral plate was involved. There was poor agreement with classification of sacral doming. Some measurements had reduced reliability in the images with evidence of doming. CONCLUSIONS: Excellent ICCs were found with measurements of from Digital Imaging and Communications in Medicine images using commercial Picture Archiving and Communication System tools. Sacral doming affected the reliability. A radiographic classification of spondylolisthesis will be most reliable when based on slip ratio, C7 balance, and pelvic tilt.

Proximal Junctional Kyphosis After Vertical Expandable Prosthetic Titanium Rib Insertion.

STUDY DESIGN: Retrospective review of patients who had undergone vertical expandable prosthetic titanium rib (VEPTR) treatment at a single institution. OBJECTIVES: To evaluate whether clinically significant proximal junctional kyphosis (PJK) occurs after VEPTR insertion. SUMMARY OF BACKGROUND DATA: PJK is a potential problem after posterior spinal instrumentation and fusion. PJK after VEPTR insertion has not been well-described. METHODS: A total of 68 patients underwent VEPTR treatment between 1999 and 2009. Diagnosis, age at time of VEPTR insertion, location of VEPTR anchors, preoperative and postoperative scoliosis, T2-T12 kyphosis and PJK, time from VEPTR insertion to development of PJK, revision procedure for significant PJK, change in PJK after the revision procedure, and PJK at final follow-up were recorded. RESULTS: Four patients developed PJK (6%). One patient had congenital scoliosis with rib fusions, 1 had scoliosis associated with a syndrome, and 2 had neuromuscular scoliosis. Mean follow-up was 5.7 years. Average T2-T12 kyphosis and PJK before VEPTR insertion were 77° and 14°, respectively. Mean T2-T12 kyphosis and PJK after VEPTR insertion were 63° and 33°, respectively. Average T2-T12 kyphosis and PJK before the recommended revision procedure for treatment of PJK were 89° and 53°, respectively. All patients developed PJK within the first year after VEPTR insertion. Two patients underwent revision to growing rods. One of these patients had preoperative halo-gravity traction. Mean PJK in these 2 patients improved from 39° to 18° after revision and remained stable at 19° at an average follow-up of 2.9 years. CONCLUSIONS: PJK after VEPTR insertion can occur. Patients with preoperative thoracic hyperkyphosis may be at higher risk. PJK can develop within the first year of VEPTR treatment, and can become progressive and severe enough to require complex interventions. In this small case series, patients were revised to growing rods.

Alternative technique for open reduction and fixation of displaced pediatric medial epicondyle fractures.

PURPOSE: To describe an alternative positioning technique for the fixation of pediatric medial epicondyle fractures which offers some significant advantages over traditional supine positioning. METHODS: At our institution, 27 patients with a displaced medial epicondyle fracture requiring open reduction and fixation were positioned prone for the procedure. The internally rotated operative arm lies on the hand table with the elbow in a natural flexed, pronated position. The elbow can be brought into extension and flexion for appropriate intraoperative radiographs. The fracture is then reduced with the arm in flexion and pronation, without having to pull excessively on the fragment. After reduction, the fragment is held easily in place for surgical fixation. A similar group of patients from the same time period positioned supine was also examined and compared to the patients who had the surgery prone. RESULTS: The average age of the 27 patients was 11.2 years (range 5.1-16.9 years). Indications for operative treatment were displaced medial epicondyle fracture (14), medial epicondyle fracture with associated elbow dislocation (12), and medial epicondyle fracture with ulnar nerve symptoms (1). At a mean of 4.5 months of follow up (1-11 months), 7 patients required the removal of hardware for screw irritation. There were no infections in the 27 surgeries and there were no other intraoperative or postoperative complications. Mild loss of flexion and extension was common in the group. Patients who had surgery in the supine position were similar with regards to patient demographics and postoperative complications, including the need for screw removal. CONCLUSIONS: While displaced medial epicondyle fractures can be treated successfully with traditional positioning, placing patients prone for the fixation of pediatric medial epicondyle fractures offers some significant advantages over supine positioning.