Variations in AP and frog-leg pelvic radiographs in a pediatric population.

INTRODUCTION: It is common for pediatric patients with a history of hip dysplasia to undergo anteroposterior (AP) and frog-leg (FL) lateral radiographs to monitor development of the hip. Because of sensitivity of pediatric tissues to ionizing radiation, we sought to document the relationship between AP and FL radiographs and to determine which image was better to assess acetabular dysplasia. METHODS: An Institutional Review Board-approved, retrospective review was conducted on 33 patients screened for hip dysplasia at a single institution. We sought to determine whether either film was more likely to be qualitatively better in position and whether there were differences in acetabular measures between the 2 radiographs. Standard measurements on AP and FL radiographs were made by 5 observers on 2 different occasions to assess interobserver and intraobserver variability. RESULTS: The mean age was 23+1 months, and 80% were female; none of the children had hip dysplasia. There was no statistical significance in the quotient of pelvic rotation (AP 1.2 + 0.1 degrees and FL 1.1 + 0.1 degrees; P = 0.84). There was a statistical difference in obturator height in mm (AP 16.0 + 0.3 and FL 17.8 + 0.2; P = 7.2E-10). The mean intraobserver variability for the acetabular index was 1.8 + 0.2 and 1.7 + 0.2 degrees for AP and FL alignments, respectively (P = 0.58), and the mean interobserver variability was 1.7 + 0.1 and 1.7 + 0.1 degrees, respectively (P = 0.75). The measurements of linear variability between the AP and FL showed no statistical significant difference with the exception of the left Hilgenreiner distance in mm (AP 1.00 + 0.08 and FL 0.81 + 0.08; P = 0.02). DISCUSSION: These results demonstrate that there is little clinical difference in variability of positioning and rotational variables between AP and FL radiographs for hip dysplasia. These results indicate that either image could be used assess to acetabular dysplasia thus decreasing risks of ionizing radiation. LEVEL OF EVIDENCE: Level III.

Hydrostatic comparison of nonpenetrating titanium clips versus conventional suture for repair of spinal durotomies.

STUDY DESIGN: Biomechanics. OBJECTIVE: To compare the hydrostatic strength of suture and nonpenetrating titanium clip repairs of standard spinal durotomies. SUMMARY OF BACKGROUND DATA: Dural tears are a frequent complication of spine surgery and can be associated with significant morbidity. Primary repair of durotomies with suture typically is attempted, but a true watertight closure can be difficult to obtain because of leakage through suture tracts. Nonpenetrating titanium clips have been developed for vascular anastomoses and provide a close apposition of the tissues without the creation of a suture tract. METHODS: Twenty-four calf spines were prepared with laminectomies and the spinal cord was evacuated leaving an intact dura. After Foley catheters were inserted from each end and inflated adjacent to a planned dural defect, the basal flow rate was measured and a 1-cm longitudinal durotomy was made with a scalpel. Eight repairs were performed for each material, which included monofilament suture, braided suture, and nonpenetrating titanium clips. The flow rate at 30, 60, and 90 cm of water and the time needed for each closure were measured. RESULTS: There was no statistically significant difference in the baseline leak rate for all 3 groups. There was no difference in the leakage rate of durotomies repaired with clips and intact specimens at any pressure. Monofilament and braided suture repairs allowed significantly more leakage than both intact and clip-repaired specimens at all pressures. The difference in leak rate increased as the pressure increased. Closing the durotomy with clips took less than half the time of closure with suture. CONCLUSION: Nonpenetrating titanium clips provide a durotomy closure with immediate hydrostatic strength similar to intact dura whereas suture repair with either suture was significantly less robust. The use of titanium clips was more rapid than that of suture repair.

Spinal duraplasty materials and hydrostasis: a biomechanical study: laboratory investigation.

OBJECT: Dural tears are a frequent complication of spinal surgery and contribute to significant morbidity. Occasionally, dural tears cannot be closed primarily and dural patch grafts must be utilized. No data exist on the comparative immediate hydrostatic strength of various patch materials used alone or with a biological adhesive in a spinal dural tear model. Thus, the authors conducted this study to determine the comparative effectiveness of various patch materials used with and without biological adhesive. METHODS: Twenty-four thoracic spines from calves were prepared with laminectomies and spinal cord evacuation, leaving the dura intact. Foley catheters were inflated on either side of a planned dural defect, and baseline hydrostasis was measured using a fluid column at 30, 60, and 90 cm of H(2)O. A standard dural defect (1 × 2 cm) was created, and 8 patches of each material (human fascia lata, Duragen, and Preclude) were sutured in place using 5-0 Prolene hemo-seal running sutures. Hydrostasis was again tested at the same pressures. Finally, a hydrogel sealant (Duraseal) was placed over the defect and hydrostasis was again tested. Results were analyzed with repeated measures ANOVA. RESULTS: The leakage rate increased significantly at each pressure tested for all conditions. There was no difference in leakage among the 3 patch materials at any of the pressures or for either condition (with or without sealant). All patch materials allowed significantly greater leakage than the intact condition at all pressures. The use of sealant reduced leakage significantly at the 30 and 60 mm Hg pressures to levels similar to the intact condition. At 90 mm Hg, leakage of the sealed construct was greater than at the intact condition but significantly less than without the use of sealant. CONCLUSIONS: All 3 dural patch materials were of similar hydrostatic strength and allowed greater leakage than at the intact condition. The use of sealant reduced the amount of leakage at all pressures compared with patching alone but allowed more leakage than the intact state at a high hydrostatic pressure (90 mm Hg).

Involvement of the spine in patients with multiple hereditary exostoses.

BACKGROUND: Extension of a vertebral exostosis into the spinal canal is rare, but many isolated cases have been reported in the literature. Three existing patients with multiple hereditary exostoses at our institution had development of neurologic findings and were found to have exostoses in the spinal canal. These findings led us to perform magnetic resonance imaging or computed tomographic scans for the remaining patients with multiple hereditary exostoses at our institution. METHODS: Forty-four patients at our institution (including twenty-six male patients and eighteen female patients) had multiple hereditary exostoses. Forty-three patients were evaluated with magnetic resonance imaging and one was evaluated with computed tomography to look for spinal column involvement. RESULTS: Thirty (68%) of the forty-four patients had exostoses arising from the spinal column, and twelve (27%) had lesions encroaching into the spinal canal. Thirty-six of the forty-four patients also had plain radiographs, but only six had radiographs that accurately identified the lesions and another six had radiographs that mistakenly identified lesions that were not confirmed with magnetic resonance imaging or computed tomography. Patients with lesions inside the spinal canal were typically asymptomatic and neurologically normal, with radiographs that did not demonstrate the lesion. Compared with female patients, male patients were more likely to have spinal lesions and more likely to have lesions encroaching into the spinal canal (p = 0.014). CONCLUSIONS: The risk that a patient with multiple hereditary exostoses has a lesion within the spinal canal is much higher than previously suspected (27%). Because the potential exists for serious neurologic injury to occur, we have begun to use magnetic resonance imaging to screen all patients who have multiple hereditary exostoses at least once during the growing years.