Increased Failure Rates After Anterior Cruciate Ligament Reconstruction With Soft-Tissue Autograft-Allograft Hybrid Grafts.

PURPOSE: To compare the rate of failure between a group of patients who underwent anterior cruciate ligament (ACL) reconstruction with an autograft-allograft hybrid soft-tissue graft and a matched group of patients who underwent ACL reconstruction with hamstring autograft. METHODS: From 2007 to 2012, 29 patients underwent hybrid ACL reconstruction performed by 4 fellowship-trained sports medicine surgeons at a single institution. Patients who underwent ACL reconstruction with hamstring autograft comprised the control group and were matched to patients in the hybrid group by sex, age, date of surgery, reconstruction technique, and method of femoral fixation. Graft failure was defined as revision ACL reconstruction or complete graft rupture on magnetic resonance imaging. Graft compromise was defined as magnetic resonance imaging evidence of partial graft rupture or arthroscopically identified partial graft rupture. Lysholm Knee Scoring Scale and International Knee Documentation Committee scores were obtained. RESULTS: Both groups included 10 men and 19 women, with a mean postoperative follow-up period of 44.4 ± 16.9 months in the hybrid group and 48.0 ± 15.2 months in the control group. Follow-up was obtained in 25 of 29 patients (86.2%) in the hybrid group, and each was matched to 1 patient who received hamstring autograft. The failure rate was 13.8% (4 of 29 patients) in the hybrid group compared with 3.4% (1 of 29) in the control group (P = .160). An additional 27.6% of hybrid group patients (7 of 29) had compromised grafts as defined earlier, as compared with 1 (3.4%) of the control patients (P = .022). Thus the overall hybrid graft failure/compromise rate was 37.9% (11 of 29) compared with 6.9% (2 of 29) for the hamstring autograft group (P = .005). In the hybrid group, the Lysholm score (80.2 ± 12.1) was significantly lower than that in the control autograft ACL group (89.9 ± 11.8) (P = .030). The International Knee Documentation Committee score for the hybrid ACL group (71.26 ± 19.5) was significantly worse than that for the autograft ACL group (85.7 ± 13.0) (P = .012). CONCLUSIONS: Allograft-autograft hybrid hamstring ACL grafts fail or become structurally compromised at a higher rate than matched autograft hamstring controls. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Radiographic assessment of lumbar facet distance spacing and pediatric spondylolysis.

STUDY DESIGN: Retrospective radiographic review. OBJECTIVE: The purpose of this article was to explore the relationship between interfacet spacing and pediatric spondylolysis. SUMMARY OF BACKGROUND DATA: Recent literature suggests that a potential cause of spondylolytic defects in adults is a narrowed interfacet spacing in the lower lumbar spine. This lack of space places them at increased risk for pars fractures with repetitive lumbar hyperextension. This relationship has not been explored in a pediatric population. METHODS: The anteroposterior lumbar spine radiographs of 41 pediatric patients with spondylolytic defects were compared with 41 unaffected controls. A standard digital caliper was used to measure interfacet distance. Vertebral body width and interpedicular distance were recorded as internal standards to control for varying vertebral size. Statistical analysis exploring the relationships of interfacet distances between the affected and unaffected groups was performed using a Mann-Whitney U test. RESULTS: The absolute increase in interfacet distance between adjacent levels was significantly smaller at the L4/L5 level in spondylolytic individuals (P = 0.023). When interpedicular distance was used to standardize for vertebral body size, a significantly smaller increase in the interpedicular distance was noted at the L4/5 level in spondylolytic individuals (P = 0.026). Similar results were obtained when body width was used to standardize for vertebral body size (P < 0.001). A similar trend was noticed at the L3/4 level when standardizing with interpedicular distance although these results were not significant (P = 0.098). CONCLUSION: A likely explanation for the etiology of lumbar pars defects is insufficient caudal increase in lumbar interfacet spacing. Further prospective studies are necessary to determine if unaffected individuals with a narrowed interfacet spacing are at increased risk of developing spondylolytic defects later in life.