Crystallization study and comparative in vitro-in vivo hydrolysis of PLA reinforcement ligament.

In the present work, the crystallization behavior and in vitro-in vivo hydrolysis rates of PLA absorbable reinforcement ligaments used in orthopaedics for the repair and reinforcement of articulation instabilities were studied. Tensile strength tests showed that this reinforcement ligament has similar mechanical properties to Fascia Latta, which is an allograft sourced from the ilio-tibial band of the human body. The PLA reinforcement ligament is a semicrystalline material with a glass transition temperature around 61 °C and a melting point of ~178 °C. Dynamic crystallization revealed that, although the crystallization rates of the material are slow, they are faster than the often-reported PLA crystallization rates. Mass loss and molecular weight reduction measurements showed that in vitro hydrolysis at 50 °C initially takes place at a slow rate, which gets progressively higher after 30-40 days. As found from SEM micrographs, deterioration of the PLA fibers begins during this time. Furthermore, as found from in vivo hydrolysis in the human body, the PLA reinforcement ligament is fully biocompatible and after 6 months of implantation is completely covered with flesh. However, the observed hydrolysis rate from in vivo studies was slow due to high molecular weight and degree of crystallinity.

Posteromedial dislocation of the elbow with lateral condyle fracture in children.

Posteromedial dislocation of the elbow in children is an extremely rare injury. The current study describes four boys with posteromedial dislocation of the elbow associated with a displaced fracture of the lateral humeral condyle. The patients ranged in age from 6 to 12 years (average age, 9 years 6 months). Closed reduction of the elbow dislocation and open reduction of the lateral humeral condyle fracture with fixation by Kirschner wires by a lateral approach was done in each patient. This was followed by 4 weeks immobilization wearing a long-arm cast. There were three excellent results and one good result. Healing and return of normal function occurred in all but one patient who had minor loss of full extension. Average duration of followup was 7 years 6 months (range, 3-13 years). Dislocation of the elbow associated with a displaced fracture of the lateral humeral condyle can be treated by closed reduction of the elbow dislocation and open anatomic reduction and fixation of the lateral condyle fracture with good results.