Internal plate fixation of fractures: short history and recent developments

Metal plates for internal fixation of fractures have been used for more than 100 years. Although initial shortcomings such as corrosion and insufficient strength have been overcome, more recent designs have not solved all problems. Further research is needed to develop a plate that accelerates fracture healing while not interfering with bone physiology

Direction-dependent resistance to flow in the endplate of the intervertebral disc : an ex vivo study

A comparison of the higher hydrostatic pressure in the nucleus of the healthy intervertebral disc during daily loading with the relatively lower osmotic swelling pressure in the disc during rest suggests the existence of direction-dependent flow resistance such that all of the fluid exuded from the disc during loading is recovered during rest. In this study, this direction-dependent resistance was demonstrated for flows through the cartilage endplates and the underlying marrow contact channels in the bony endplates. Using an ex vivo sheep endplate model, the resistance ratio (Rout/Rin) for flow through the endplate was 39.0 ± 3.8 (mean ± S.E.). In addition, a path of fluid flow through the marrow contact holes was revealed using fluorescent staining

Effect of tibial tuberosity advancement on femorotibial shear in cranial cruciate-deficient stifles. An in vitro study

OBJECTIVES: This in vitro study compares the femorotibial shear in canine stifles with intact and transected cranial cruciate ligaments (CrCL), before and after tibial tuberosity advancement (TTA) by measuring the distance between origin and insertion of the cruciate ligaments. METHODS: Radiodense markers were inserted into bones at the attachment sites of the cruciate ligaments in sixteen cadaveric stifles of adult dogs. Each stifle was then mounted in a testing apparatus. The distances between the markers were measured on mediolateral radiographs, performed on each stifle under three different situations: intact, after CrCL transection, and after performing a TTA. Stifles were loaded to create a constant tibiofemoral reaction force by maintaining the load parallel to the patellar ligament. Radiographs were taken in a preloaded and loaded state in the intact stifle and only in a loaded state after CrCL transection, and after performing a TTA. RESULTS: Loading the stifle joints after transection of the CrCL resulted in a mean lengthening of the CrCL marker distance of 22.4%. Loading the transected CrCL stifles after performing a TTA resulted in a mean shortening of the CrCL marker distance by 3.0% compared to the loaded intact condition. CLINICAL SIGNIFICANCE: This study demonstrates that, in loaded stifles with transected CrCLs, TTA causes a caudal shift in the cranial shear force, counteracting cranial subluxation of the tibia

Movement-induced orientation: a potential mechanisms of cartilage collagen network morphogenesis

Articular cartilage is a layer of tissue lining the articulating osseous ends in diarthroidal joints. Its primary function is to provide a durable, low friction, load-bearing surface. Cartilage on cartilage, lubricated with synovial fluid, has a coefficient of friction of 0.02–0.005 (Charnley 1959), and regularly provides problem-free performance for a lifetime. Although this may not seem so remarkable, comparison to synthetic bearings is quite revealing. The coefficient of friction for steel on steel lubricated with oil is 0.1 (Jones 1936) and that of dry Teflon on Teflon is 0.04 (Bowden and Tabor 1950). Furthermore, the life of mechanical bearings is often less than 20 years. Articular cartilage is an exceptional material with an optimal design for its function