Knud S. Christensen

Recombinant human vascular endothelial growth factor enhances bone healing in an experimental nonunion model

The re-establishment of vascularity is an early event in fracture healing; upregulation of angiogenesis may therefore promote the formation of bone. We have investigated the capacity of vascular endothelial growth factor (VEGF) to stimulate the formation of bone in an experimental atrophic nonunion model. Three groups of eight rabbits underwent a standard nonunion operation. This was followed by interfragmentary deposition of 100 microg VEGF, carrier alone or autograft. After seven weeks, torsional failure tests and callus size confirmed that VEGF-treated osteotomies had united whereas the carrier-treated osteotomies failed to unite. The biomechanical properties of the groups treated with VEGF and autograft were identical. There was no difference in bone blood flow. We considered that VEGF stimulated the formation of competent bone in an environment deprived of its normal vascularisation and osteoprogenitor cell supply. It could be used to enhance the healing of fractures predisposed to nonunion.

Effects of locally applied vascular endothelial growth factor (VEGF) and VEGF-inhibitor to the rabbit tibia during distraction osteogenesis.

Introduction: Therapeutic angiogenesis, a novel concept in tissue engineering, is neo‐formation of blood vessels in a tissue upon delivery of an angiogenic growth factor to the tissue. We hypothesised that therapeutic angiogenesis could enhance bone formation and challenged the hypothesis in an experimental model of distraction osteogenesis.

Patellectomy - a 20-year follow-up

Twenty-seven patients with 28 patellectomies were re-examined after an average of 20 years. Twelve knees rated as excellent, ten as good and six as fair. Even though 12 patients had strenuous work, only three patients had changed occupation. Quadriceps power was on average two-thirds that of the opposite limb. Radiographs showed incipient femoro-tibial arthrosis in four patients only.

Tibial bone loss and soft-tissue defect treated simultaneously with Ilizarov-technique--a case report

Copyright

Inflatable splints: do they cause tissue ischaemia?

The effect of increasing pneumatic splint pressure on cutaneous oxygen tension measured transcutaneously (TcPO2) was investigated in 12 subjects. The mean initial TcPO2 was 70.6 mmHg. TcPO2 decreased linearly on increasing the pressure within the splint. TcPO2 became zero at a mean splint pressure of 28 mmHg. Second, three accepted methods used by the ambulance crew to assess inflation pressures of the splint were investigated and found to be unreliable. In the light of these findings the risk of ischaemic complications as a result of applying pneumatic splints to a fractured limb is discussed. We advocate a recommended maximum splint pressure of 15 mmHg and that the splint should be manufactured with a security blow-off valve set at 15 mmHg.

Long posterior flap versus equal sagittal flaps in below-knee amputation for ischaemia

We analysed the complication rate in 140 below-knee amputations in relation to surgical technique and the presence of diabetes. In all cases, the skin perfusion pressure was measured below the knee before operation to provide an objective evaluation of the microcirculation. In diabetic patients we found a significantly higher complication rate after using a long posterior flap than after equal sagittal flaps. No such difference could be demonstrated in non-diabetic patients. We suggest that the higher incidence of atherosclerotic lesions in the three major arteries below the knee in diabetic patients may account for the difference. We recommend the use of the sagittal technique for below-knee amputation in diabetic patients.

Selection of lower limb amputation level not aided by transcutaneous pO2 measurements.

The transcutaneous oxygen pressure measurements were evaluated as supplementary ones for predicting stump healing in 58 below-the-knee and 16 above-the-knee amputations; the lower level was selected if the skin perfusion pressure was greater than 30 mm Hg below the knee. The failure rates in below-the-knee and above-the-knee amputations were 17 and 25 percent, respectively, and unrelated to the transcutaneous oxygen pressure measured at the amputation level. We conclude that no further information is acquired by measuring transcutaneous oxygen pressure.

Results of amputation for gangrene in diabetic and non-diabetic patients. Selection of amputation level using photoelectric measurements of skin-perfusion pressure.

Evaluation was done of 235 patients who had had 273 primary amputations for gangrene. Measurements of local skin-perfusion pressure or systolic blood pressure were made in 222 limbs (188 patients). For the other fifty-one limbs, for which no measurements of pressure were available, the surgeon elected to perform an above-the-knee amputation in nine of seventeen diabetic limbs and a below-the-knee amputation in eight. An above-the-knee amputation was selected by the surgeon for thirty-two of thirty-four non-diabetic limbs and a below-the-knee amputation, for two for which no measurements of pressure were available. Local skin-perfusion pressure was measured distal to the knee before amputation, using a standardized photoelectric technique in 203 limbs and systolic blood-pressure measurements in nineteen. Skin-perfusion pressure was also measured above the knee in seventy-six of the 222 limbs in which a pressure was determined below the knee. These measurements were made available to the surgeon for use as an adjuvant guide to clinical assessment in selecting the appropriate level of amputation. Seventy-four patients (ninety-two amputations) had diabetes and 114 patients (130 amputations) did not. The limbs of the diabetic patients had a significantly higher skin-perfusion pressure at the below-the-knee level (p less than 0.001) than did those of the non-diabetic patients. The ratios of below-the-knee to above-the-knee amputations for the diabetic and non-diabetic patients were 3.8 to one and 1.3 to one (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Mid-tibial distraction osteogenesis redistributes bone blood flow A microsphere study in rabbits

Background Distraction osteogenesis can be used for the treatment of osteomyelitis and nonunion, conditions thought to benefit from increased blood flow in the bone tissue of the distracted limb. We have questioned whether such an increase occurs, and investigated the spatial distribution of bone blood flow after distraction osteogenesis. Methods The tibiae of 8 rabbits were lengthened 10 mm by a standard midtibial distraction osteogenesis procedure. 2 weeks into the consolidation phase, the bone and soft tissue blood flow of the distracted and the contralateral extremity were measured using radioactive microspheres. Results The absolute bone blood flow of the distracted tibia was 4% lower than that of the non-distracted side, representing a 41% decrease in the proximal metaphysis, a smaller decrease in the proximal epiphysis, distal metaphysis and distal epiphysis, and an increase in the diaphysis. Interpretation Mid-tibial distraction osteogenesis redistributed the bone blood flow of the distracted tibia, but absolute tibial blood flow did not increase. Our results do not confirm previous research in this field.

Volkmann's ischaemic contracture due to limb compression in drug-induced coma

A case of Volkmanns contracture secondary to prolonged compression of the limb is presented. The events developed in a patient who had been comatose following an overdose of alcohol and a sedative drug.