Biomechanical Comparison of Two Pediatric Blade Plate Designs in Proximal Femoral Osteotomies

Comparison of Locked Plates and Blade Plates for Varus Osteotomy of the Proximal Femur by the Finite Element Method

Objective:  The present study compared the difference in load and pressure distribution behavior of the blade plate and locked plate for varus osteotomy of the proximal femur per the finite element method. Methods:  Modeling was performed by scanning a medium-sized left femur with medial valgus deformity made of polyurethane. Results:  The stiffness of the locked plate is higher compared with that of the blade plate. However, this difference was not significant. In addition, the locked plate has proximal locking screws to ensure that the bending moments on the screws are smaller during loading. Conclusion:  In summary, both plates are well-established and effective. However, the study using the finite element method plays a fundamental role in understanding the load and pressure distribution of the implant. Moreover, it opens up new possibilities for further studies, including surgical proposals and customized implant materials.

Conventional versus locked plates for hip dislocation in cerebral palsy: a matched cohort analysis

PURPOSE

Bone quality of non-ambulatory patients with cerebral palsy (CP) is a matter of concern for proximal femoral varus derotational osteotomies (VDRO). Locking plates (LCP) have been designed to compensate this biological downfall. Little data exist comparing the LCP with the conventional femoral blade plate.

METHODS

We retrospectively studied 32 patients submitted to VDRO (40 hips), operated with blade plates or LCP. Groups were matched, and the minimal follow-up was 36 months. Clinical (age at surgery, sex, GMFCS class, CP patterns) and radiological characteristics (neck shaft angle [NSA], acetabular index [AI], Reimers migration index [MP] and time until bone healing), as well as postoperative complications and the cost of treatment, were evaluated.

RESULTS

Preoperative clinical characteristics and radiographic measurements were comparable, except for a higher AI in the BP group (p < 0.01). Mean follow-up was longer in the LCP group (57.35 vs 34.6 months). Mean NSA, AI and MP had comparable correction with surgery (p < 0.01). At final follow-up, dislocation recurrence speed was higher in BP group although not statistically significant (0.56% vs 0.35%/month; p = 0.29). The complication rate was similar in both groups (p > 0.05). Finally, the cost of the treatment was 62% higher in the LCP group (p = 0.01).

CONCLUSION

Our cohorts showed LCP or BP equivalence clinically and radiographically in mid-term follow-up, with the former increasing the cost of treatment by a mean of 62%. This may raise a question on the real necessity of locked implants for these operations.

LEVEL OF EVIDENCE

Level III-Retrospective comparative study.