The development of femoral osteopenia in ovariectomized rats is not reduced by high intensity treadmill training: a mechanical and densitometric study.

The effect of treadmill running on the development of osteopenia was investigated in adult ovariectomized (OVX) rats compared with sedentary OVX and sedentary sham-operated rats. The rats were 3 months old with a mean weight of 214 g. OVX rats were fed a low calcium diet (0.

Passive muscle tension augments the anterior cruciate ligament. An in vivo study in the rat.

The contribution by passive muscle tension to the structural load-bearing capacity of the anterior (cruciate) ligament in the anesthetized rat was investigated. Using a stereomicroscope, the joint capsule and ligaments of the right knee, except the anterior ligament, were cut and the menisci removed leaving the anterior ligament and the tendons of the denervated muscle to constrain the knee. The ligament was tested in tension until failure, using a loading rate of 2.

The neuronal regulation of fracture healing. Effects of sciatic nerve resection in rat tibia.

The effect of sciatic nerve resection on tibial fracture healing was studied in rats 25 days post-trauma. To prevent differences in loading between sham-operated and nerve-resected animals the fractured limbs were cast-immobilized. On radiograms 8 of 11 fractures in the sham-operated animals showed very little callus formation in contrast to only 1 of 8 fractures in the group with nerve resection.

Extracellular matrix metalloproteinases around loose total hip prostheses.

We have explored the tissue localization of extracellular matrix metalloproteinases MMP-1 (fibroblast collagenase), MMP-2 (72-kDa gelatinase/Type IV collagenase), MMP-3 (stromelysin), MMP-8 (polymorphonuclear leukocyte collagenase) and MMP-9 (92-kDa gelatinase/Type IV collagenase) in the tissues around loose hip prostheses. The findings were compared with those in synovial tissues obtained from patients with a fractured femoral neck. MMP-type specific antisera were applied in the sensitive avidin-biotin-peroxidase complex methods.

Muscle contraction increases the in vivo structural strength to the same degree in osteopenic and normal rat tibiae.

The increase in structural capacity due to muscle contraction in the lower leg was investigated in osteopenic and normal rats. Osteopenia was induced by ovariectomy combined with a low-calcium diet (0.01%).

Muscle contraction increases the strength of healing tibial fracture in the rat.

Tibial fractures in 7-week-old rats were fixed with intramedullary nails. After 25 days of healing the nails were removed and the tibiae loaded in vivo with intact soft tissues until refracture. The animals were tested in three-point anterior cantilever bending either during muscle contraction (n 8) or with relaxed muscles (n 8).

Fracture strength prediction in rat femoral shaft and neck by single photon absorptiometry of the femoral shaft.

The bone mineral content (BMC) and bone mineral density (BMD) of the femoral midshaft from 15 skeletally mature male rats were measured by Single Photon Absorptiometry (SPA), and comparisons made to fracture strength of the femoral diaphysis and the femoral neck. In stepwise regression the factors contributing significantly to the ultimate bending moment of the shaft were BMC and femoral length. BMC correlated strongly with the ultimate bending moment of the femoral diaphysis (r2 = 0.

Does granulocyte depletion protect against ischaemic muscle necrosis?

Male Wistar rats were submitted to complete hindlimb ischaemia for 4.5 h. Six animals were injected with antineutrophilic serum (ANS) pre- and post-operatively, and eight animals received normal sheep serum (NSS).

Muscle function after mid-shaft femoral shortening. A prospective study with a two-year follow-up.

We performed isokinetic knee testing to assess thigh muscle function in ten patients (12 legs) before and after mid-shaft femoral shortening averaging 46 mm (27 to 70). Tests were at angular velocities of 60 degrees/sec and 180 degrees/sec, and were performed preoperatively and after 3, 6, 12 and 24 months. Isokinetic tests at two years showed a significant reduction in muscle function in both quadriceps and hamstrings, but recovery of function was significantly better for the hamstrings.

Pentoxifylline reduces skeletal muscle necrosis after acute hindlimb ischemia in rats.

Complete ischemia in the left hindlimb was maintained for 3.5 h in 16 rats randomized into two equal groups. One group served as control, the other was treated with pentoxifylline before, during and after the ischemic period.

Muscle function after femoral shortening osteotomies at the subtrochanteric and mid-diaphyseal level. A follow-up study.

Relative femoral shortening length at the subtrochanteric (ST) and mid-diaphyseal (MD) level was compared with isokinetic muscle strength more than 2 years postoperatively. For the ST level no upper limit for shortening length could be detected. For MD osteotomies the relative shortening length was negatively correlated to muscle strength.

Training increases the in vivo strength of the lower leg: an experimental study in the rat.

The effect of training on bone strength has been investigated in rats. After 7 weeks of training, fracture strength of the tibia in vivo during muscle contraction and after resection was assessed. A group of 30 male rats 11 weeks old were randomized to exercise on a treadmill, sedentary (ordinary caging), and inactivity (right-sided patellar tendonectomy) groups.

Perfusion in the anterior tibial muscle measured by laser Doppler flowmetry after graded periods of hindlimb ischemia in rats.

In the present study laser Doppler flowmetry was used to evaluate skeletal muscle perfusion before and after acute hindlimb ischemia in rats. Three laser Doppler microprobes were placed in the anterior tibial muscles of both legs. Six animals were used as non-ischemic controls and 22 animals were subjected to complete ischemia in the left hindlimb for 0.

Muscle contribution to tibial fracture strength in rats.

We studied the contribution of anesthetized and dead muscle to the loading capacity of the tibia in ventral three-point cantilever bending directly by a newly developed method in rats. Ketamine anesthesia, known to give poor muscle relaxation, did not increase the loading capacity more than Hypnorm/Dormicum anesthesia and dead muscle. The ultimate bending moment increased by about 40 percent and the ultimate absorbed energy by about 85 percent when the tibia was tested in situ compared to testing in the dissected state; the tibia could withstand approximately 50 percent more deflection when loaded intact with soft tissues.

Muscle contraction increases the structural capacity of the lower leg: an in vivo study in the rat.

A model to study the contribution of muscle contraction to the structural capacity of the rat tibia was developed. The right lower leg was tested to failure in three-point ventral bending during electrically stimulated muscle contraction. The left lower leg was tested without stimulation, as a control.

Local hypothermia during ischemia or reperfusion in skeletal muscles.

A modified rat hindlimb tourniquet model was used to measure postischemic muscle necrosis. The effect of moderate local hypothermia to 20 degrees C during ischemia and reperfusion was investigated. Eighteen animals were kept in an incubator at 27 degrees C, and complete circulatory arrest was maintained for 3.

Fracture weakens ipsilateral long bones: mechanical and metabolic changes after femoral or tibial injury in rats.

We have studied the effect of tibial osteotomy on mechanical and metabolic properties of the femur, and the effects of femoral osteotomy or fracture on mechanical properties of the tibia in rats. In the bone ipsilateral to the trauma, there was a significant reduction of mechanical strength and stiffness, both in bending and torsion, compared with the contralateral side. The ipsilateral bone lost weight and the blood flow was increased.

Histological studies on postischemic rat skeletal muscles. With emphasis on the time of leukocyte invasion.

Several studies have suggested that the damage after ischemic injuries increases during reperfusion and that this reperfusion damage is mediated through granulocytes which invade the damaged area. The present study was undertaken to test these hypotheses by histological investigations of the anterior tibial muscles in a rat hind limb tourniquet model after 4.5 h of complete ischemia and graded periods of reperfusion.

Healing of cortical bone grafts in athymic rats.

We studied healing of allogeneic and syngeneic cortical tibial segment grafts in athymic and normal rats. After 3, 6, and 12 weeks, the weight, circulation, and mineralization rate of the healing segment, and mechanical strength and stiffness of the healing tibia were measured. There were no differences between allogeneic and syngeneic grafts in athymic and normal animals at 3 or 6 weeks.

Bilateral femoral shortening for unaccepted tallness.

We performed bilateral femoral shortening operations on 15 skeletally mature patients (11 women and four men). Their mean height pre-operatively was 193.5 cm and they were shortened by 5 to 9 cm.

Protective effect of low-grade hypothermia in experimental skeletal muscle ischemia.

In the present study, a rat hindlimb tourniquet model was used to investigate the effect of moderate hypothermia on ischemic muscle necrosis. Complete circulatory arrest was maintained for 4.5 h.

Early loss of fixation of femoral neck fractures. Comparison of three devices in 244 cases.

In successive series of displaced subcapital femoral neck fractures in the elderly, we operated on 75 cases with three Gouffon screws, 94 with three Mecron screws, and 75 with two von Bahr screws. Redisplacement within 3 months occurred in 20 Gouffon cases, 11 Mecron cases, and 12 von Bahr cases. Poor reduction contributed to the failures in all the groups.