No abstract

In the application of "rigid" plates for diaphyseal fractures, lack of callus healing and overprotection of the underlying bone are viewed by many investigators as undesirable consequences. Potential solutions offered to overcome these deficiencies include modification of the timing of plate removal, use of biologically degradable materials for plates so that stress-shielding can be minimized, and use of less rigid plate fixation systems. This study emphasizes the selection of appropriate design criteria for less rigid plate-fixation systems. To accomplish this goal, the axial, bending, and torsional stiffness parameters are considered in place of the oversimplified terms such as "flexible plate" or "elastic fixation." With the aid of finite element modeling and simplified bench experiments, we performed parametric studies and singled out the plate axial stiffness as the dominant factor in altering the bone stresses. As a result, we designed two experimental plates, one a thin Ti-6Al-4V (titanium with 6% aluminum and 4% vanadium) alloy plate with low stiffness in axial and bending directions, and the other a tubular stainless steel plate with low stiffness in the axial direction but moderate stiffness in bending and torsional directions. The low-stiffness Ti-6Al-4V alloy plate was first tested in a demanding bilateral canine midshaft osteotomy, and proved to be inadequate. Both experimental plates were successful in the unilateral osteotomies, with the tubular plate yielding the best results. After 6 months of plating, the bones beneath the tubular plate had superior mechanical and structural properties as compared to those of the control "rigid" stainless steel and the Ti-6Al-4V alloy plates. Application of this plate prolonged for 9 months did not cause reduction in bone properties and strength. The success of the tubular plate is due to its moderate bending and torsional stiffnesses, which provide adequate fixation to achieve callus union, while its low axial stiffness permits the underlying bone to share the physiological stresses needed for bone remodeling. These drastic changes in mechanical demands on the internal fixation plate during the early healing phase and the postunion remodeling phase are discussed.

We have treated 75 cases of spinal tuberculosis with chemotherapy as outpatients. The drugs used were INH, rifampicin and ethambutol for the 48 adults, and INH, rifampicin and PAS for the 27 children. No operations, apart from the evacuation of large abscesses, were carried out. Every patient was followed up for at least three years and the outcome was judged to be favourable in 95%. This is better than in some series in which radical surgery has been used. Although we recognize the advantages of operation in certain circumstances, we believe that our conservative regimen can be confidently recommended for use in less privileged countries, where adequate facilities for hospital treatment may not be available.

Oxidative stress caused apoptosis of rat notochordal cells via both intrinsic and extrinsic (Type I and Type II) pathways. Because caspase inhibitors are being used in clinical trials, inhibition of both pathways using caspase inhibitors might be of future therapeutic importance in oxidative stress-induced apoptosis of notochordal cells. Our results suggest that inhibition of inappropriate or premature oxidative stress-induced apoptosis of notochordal cells may delay the starting point of disc degeneration.

This article describes a new technique for the arthroscopic reduction and fixation of anterior cruciate ligament (ACL) tibial avulsion fractures using bioabsorbable suture anchors. This described technique requires the use of anterolateral, anteromedial, medial mid-patellar, and lateral mid-patellar portals. A suture hook loaded with No. 2 polydioxanone (PDS) was used to pierce the ACL through the anteromedial or anterolateral portal, and bioabsorbable suture anchors were inserted through the medial and lateral mid-patellar portals. The five patients treated using this technique were evaluated at 1 year postoperatively. All patients showed bony union without anterior laxity or flexion contracture. The described technique provides firm fixation of fracture fragment and can be used in both skeletally immature and mature patients.