Bionic plate design for calcaneal fracture treatment. A biomechanical analysis and first clinical results.

PURPOSE: Calcaneal fracture treatment is challenging. Implant failure is one problem encountered with plate osteosynthesis. Therefore a new "bionic" plate was developed, which imitates the trabecular orientation of the human calcaneus. The aim of this study was to biomechanically test this new plate in comparison to a "standard" calcaneal locking plate and present the first clinical results. METHODS: Six "bionic" and six "standard" calcaneal plates were biomechanically tested for stability and fatigue using synthetic calcanei. Between 4/2012 and 04/2013 the first ten consecutive patients meeting the inclusion criteria were treated with the novel implant and followed-up clinically and radiologically. The 12-month follow-up results are reported. RESULTS: The "bionic" plate design showed significantly higher fatigue life (68%), load to failure (100%) and reduced displacement under load (90%) if compared to a "standard" locking plate. No major complications were seen; most notably there was no implant failure and no loss of reduction. Mean AOFAS/hindfoot score was 79 (69-86). CONCLUSIONS: The novel plate architecture offers higher stability and load tolerance while being more resistant to fatigue. The preliminary clinical results are promising. These findings will have to be proved by larger clinical trials.

Identification of novel cell-adhesion molecules in peripheral nerves using a signal-sequence trap.

The development and maintenance of myelinated nerves in the PNS requires constant and reciprocal communication between Schwann cells and their associated axons. However, little is known about the nature of the cell-surface molecules that mediate axon-glial interactions at the onset of myelination and during maintenance of the myelin sheath in the adult. Based on the rationale that such molecules contain a signal sequence in order to be presented on the cell surface, we have employed a eukaryotic-based, signal-sequence-trap approach to identify novel secreted and membrane-bound molecules that are expressed in myelinating and non-myelinating Schwann cells. Using cDNA libraries derived from dbcAMP-stimulated primary Schwann cells and 3-day-old rat sciatic nerve mRNAs, we generated an extensive list of novel molecules expressed in myelinating nerves in the PNS. Many of the identified proteins are cell-adhesion molecules (CAMs) and extracellular matrix (ECM) components, most of which have not been described previously in Schwann cells. In addition, we have identified several signaling receptors, growth and differentiation factors, ecto-enzymes and proteins that are associated with the endoplasmic reticulum and the Golgi network. We further examined the expression of several of the novel molecules in Schwann cells in culture and in rat sciatic nerve by primer-specific, real-time PCR and in situ hybridization. Our results indicate that myelinating Schwann cells express a battery of novel CAMs that might mediate their interactions with the underlying axons.