We report the case of a 12-year-old boy with flexion loss in the left elbow caused by deficient of the concavity corresponding to the coronoid fossa in the distal humerus. The range of motion (ROM) was 15°/100°, and pain was induced by passive terminal flexion. Plain radiographs revealed complete epiphyseal closure, and computed tomography (CT) revealed a flat anterior surface of the distal humerus; the coronoid fossa was absent. Then, the bony morphometric contour was surgically recreated using a navigation system and a three-dimensional elbow joint model. A three-dimensional model of the elbow joint was made preoperatively and the model comprising the distal humerus was milled so that elbow flexion flexion of more than 140° could be achieved against the proximal ulna and radius. Navigation-assisted surgery (contouring arthroplasty) was performed using CT data from this milled three-dimensional model. Subsequently, an intraoperative passive elbow flexion of 135° was obtained. However, active elbow flexion was still inadequate one year after operation, and a triceps lengthening procedure was performed. At the final follow-up one year after triceps lengthening, a considerable improvement in flexion was observed with a ROM of −12°/125°. Plain radiographs revealed no signs of degenerative change, and CT revealed the formation of the radial and coronoid fossae on the anterior surface of the distal humerus. Navigation-assisted surgery for deformity of the distal humerus based on a contoured three-dimensional model is extremely effective as it facilitates evaluation of the bony morphometry of the distal humerus. It is particularly useful as an indicator for milling the actual bone when a model of the mirror image of the unaffected side cannot be applied to the affected side as observed in our case.

This study examined the inhibitory effects of anti-TNF-a antibody (anti-TNF) and a new bisphosphonate (TRK-530) on peri-implant oseteolysis in a rat model with continuous infusion of polyethylene particles. TRK-530 is a novel synthetic bisphophonate to have a direct effect on osteoclastic bone resorption as well as suppressive effects on bone resorbing cytokines from macrophages.

Materials and methods: Sixty Wister rats were randomized to three groups (n=20 each). In each rat, a Kirshner wire (K-wire) was inserted into the femur and polyethylene particles (HDPE, mean size; 2 microns) were continuously infused into the knee joint using an osmotic pump. The animals were subcutaneously injected with saline (control group) or 1 mg/kg of TRK (TRK group) or intraperitoneally injected with 100 mg of anti-TNF (anti-TNF group) every second day after surgery until 8 weeks. At 4 weeks or 8 weeks after surgery, rats were sacrificed. Rdiographs were evaluated for the presence of osteolysis, thereafter, garnulation tissues were stored for PCR analysis for IL-1 mRNA as well as TNF-a mRNA. Then, femurs were prepared for the histology.

Results: Radiographic peri-implant osteolysis was seen more frequently in TRK group compared to other two groups (p< 0.01). The interfacial membrane was significantly thinner in TRK and anti-TNF group compared to the control group (p< 0.01). The average number of osteoclasts around K-wire was significantly fewer in the TRK group compared to the other groups (p< 0.01). The expression of IL-1 mRNA and TNF-a mRNA was significantly suppressed in the TRK group at 8 weeks after surgery.

Discussion: The present study demonstrates that cumulative effects of TRK such as the suppression of bone resorbing cytokines as well as direct suppression of osteoclasts reduce the polyethylene induced peri-implant osteolysis. In addition, single anti-cytokine therapy appears not to be enough to inhibit peri-implant osteolysis in our model.