Patella Fracture Case Study

Introduction

Patella fractures are common injuries of knee joint after certain degree of direct trauma. It accounts about 0.5% - 1.5% in all kind of bone fractures (1). The disruption of the extensor mechanism in knee restricts the range of moment of the joint. However, worldwide orthopedic surgeons still face a significant challenge in fixation methods (2). Open reduction and internal fixation is the golden surgical technique for transverse patella fractures. By using tension band wiring, it produces a compression force to the fracture site. The healing process of fracture relies on both the fixation techniques and implants used. Although this practice has been developed for more than 50 years, post-operative complications still exist in

It is a triangular shaped bone and acts like a shield to protect the knee structure behind. The existence of subcutaneous bursa makes the patella totally separated from the skin. The main body of patella is mostly covered by a thick layer of articular cartilage and surrounded by four quadriceps muscles. Those quadriceps tendons insert to the patella in order to provide the biomechanical function. It plays the most important role in the extensor mechanism of the knee joint (3). The quadriceps tendons and patellar tendons link up with patella to serve the function. Extension of knee can be achieved by the tension between quadriceps and patella. Flexion of knee is limited by the quadriceps tendon. As a whole structure, patella becomes a pulley to generate force between patella-femoral joint in order to support the body against gravity

Our objective is to study the healing quality of magnesium implants in a patella fracture pattern with respect to radiological, mechanical and histological assessments.

Study Design

In vivo animal experiment in rabbits.

Proposed Methods

The Laboratory Animal Service Center of the Chinese University of Hong Kong provided white rabbits. By using an oscillating saw, a standard transverse osteotomy was performed on the patella of left knee in New Zealand White Rabbits’ patella. Magnesium-based implants will be used for fixing the fracture. Then the operated limb was immobilized by a cast for six weeks. After the end of eight weeks and twelve weeks, the rabbits were euthanized and the samples were assessed mechanically by tensile testing. After the mechanical testing, the samples were embedded and sectioned for histological