Pelvic Obliquity Correction in Distraction-Based Growth Friendly Implants.

DESIGN: Multicenter retrospective review. OBJECTIVE: To evaluate radiographic outcomes and complication rates of patients treated with distraction based implants and pelvic fixation with either screws (sacral-alar-iliac [SAI] screws or iliac screws) or hooks (S hook iliac fixation). SUMMARY OF BACKGROUND DATA: Multiple options exist for pelvic fixation in distraction-based growing rod systems; however, limited comparative data are available. METHODS: Early-onset scoliosis (EOS) patients of all diagnoses with distraction-based implants that had pelvic fixation from 2000 to 2013 were reviewed from two EOS multicenter databases. Patients were divided into two groups by type of pelvic fixation: (1) screw group (SAI screws or iliac screws) or (2) S hooks. Exclusion criteria were as follows: index instrumentation ≥10 years old and follow up <2 years. A total of 153 patients met the inclusion criteria. Mean age at index surgery was 6.1 years (range 1.0-9.9 years) and mean follow-up was 4.9 years. RESULTS: Pelvic fixation in the 153 patients was as follows: screw group = 42 and S hook group = 111. When comparing patients with >20° of initial pelvic obliquity, the screw group had significantly more correction; mean 26° ± 13° for the screw group versus mean 17° ± 7° in the S hook group (p = .039). There was no significant difference in change in T1-S1 length (40 vs. 39 mm, p = .89) or correction of Cobb angle (30° vs. 24°, p = .24). The total complication rate for the screw group was 14% (6/42) versus 25% (28/111) in the S hook group, though this did not achieve significance (p = .25). The most common complications were device migration (13), implant failure (8), and implant prominence (4) for S hooks and implant failure (3), implant prominence (2), and device migration (1) for the screw group. CONCLUSION: In distraction-based growth-friendly constructs, pelvic fixation with screws achieved better correction of pelvic obliquity than S hooks. Complications were almost twice as common with S hooks than screws, though this did not reach statistical significance.

Confirming the Presence of Unrecognized Meniscal Injuries on Magnetic Resonance Imaging in Pediatric and Adolescent Patients With Anterior Cruciate Ligament Tears.

BACKGROUND: Prior research has shown decreased accuracy of meniscal injury detection using magnetic resonance imaging (MRI) for anterior cruciate ligament (ACL)-deficient adult patients as well as ACL-deficient pediatric and adolescent patients. The objectives of this study were the following: (1) assess the diagnostic ability of MRI in detecting meniscal injuries for pediatric and adolescent patients undergoing arthroscopic ACL reconstruction and (2) characterize the unrecognized meniscal injuries. METHODS: The sensitivity, specificity, positive predictive value, and negative predictive value of meniscal tears (medial, lateral, or both) on MRI were calculated for the 107 patients in this cohort. Fisher exact tests were used to compare event frequencies between medial meniscal (MM) and lateral meniscal (LM) tears. One-way analysis of variance tests were performed to compare event rates between the location and type of unrecognized meniscal tears. RESULTS: The median age of the cohort was 15 (range: 7 to 18). The sensitivity, specificity, positive predictive value, and negative predictive value of MRI in detecting meniscal tears (medial, lateral, or both) in ACL-deficient pediatric and adolescent patients was 62.3%, 68.4%, 78.2%, and 50.0%, respectively. There were 26 (24.3%) cases in which a meniscal injury was not detected on MRI, but was discovered arthroscopically (MM: 5 knees, LM: 20 knees, both: 1 knee). These unrecognized meniscal injuries were more commonly the LM than the MM (77.8%, P-value=0.100), a vertical/longitudinal tear type (77.8%, P-value <0.001), and located in the posterior horn (74.1%, P-value <0.001). CONCLUSIONS: In this ACL-deficient pediatric and adolescent cohort, there were 26 (24.3%) patients with unrecognized meniscal injuries. A vertical tear in the posterior horn was the most commonly unrecognized meniscal injury, supporting the findings of prior research postulating that the location and configuration of a tear influence the accuracy of MRI in detecting these injuries. More research is needed to investigate strategies to improve the detection of meniscal tears in pediatric and adolescent patients preoperatively. These findings have implications with regard to patient counseling, operative planning, anticipatory guidance with regard to postoperative rehabilitation, recovery expectations, and surgical outcomes. LEVEL OF EVIDENCE: Level IV.

Preventing Distal Junctional Kyphosis by Applying the Stable Sagittal Vertebra Concept to Selective Thoracic Fusion in Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Multicenter retrospective review. OBJECTIVE: To assess the effectiveness of using the stable sagittal vertebra (SSV) for selecting the lowest instrumented vertebrae (LIV) to prevent distal junctional kyphosis (DJK) in selective thoracic fusions. SUMMARY OF BACKGROUND DATA: Cho et al. reported that including the SSV in a fusion decreased the rate of DJK in thoracic hyperkyphosis. METHODS: A retrospective review was performed of patients from two pediatric hospitals with adolescent idiopathic scoliosis who underwent selective posterior thoracic fusion with the LIV at L2 or above from 2000 to 2012. Patients with less than 2 years' follow-up were excluded. The primary outcome measure was DJK, defined radiographically as ≥10° between the superior end plate of the LIV and the inferior end plate of the vertebra below on a standing lateral radiograph. We investigated the SSV, which was defined as the vertebral level at which 50% of the vertebral body was in front of the posterior sacral vertical line (PSVL) on a standing lateral radiograph. This particular definition was referred to as SSV. RESULTS: A total of 113 patients met the inclusion criteria. Mean age was 14.4 years. Mean Cobb angle was 58°. The overall rate of DJK was 7% (8/113). When the LIV was superior to SSV, the rate of DJK was 17% (8/46) versus 0% (0/67) when the LIV was at or inferior to SSV (p=.01). The rates of DJK for patients with the LIV one, two, and three levels above SSV were 17% (4/24), 7% (1/14), and 43% (3/7), respectively. There was no significant association between preoperative or postoperative maximum kyphosis, thoracic kyphosis, thoracolumbar kyphosis, pelvic incidence, sagittal balance or coronal balance, and development of DJK. CONCLUSION: Although LIV selection is complex, choosing the LIV at or below the SSV is a simple rule that minimizes the risk of DJK. LEVEL OF EVIDENCE: Level IV.