Intravenous pamidronate reduces osteoporosis and improves formation of the regenerate during distraction osteogenesis. A study in immature rabbits.

We examined the effect on bone mineral density (BMD) of a single dose of 3 mg/kg of the bisphosphonate, pamidronate (Novartis) in distraction osteogenesis in immature rabbits. Seventeen rabbits (9 control, 8 given pamidronate) were examined by dual-energy x-ray absorptiometry. There was a significant increase in the BMD in the pamidronate group compared with the control animals. The mean areal BMD (g/cm2) in the bone proximal and distal to the regenerate was increased by 40% and 39%, respectively, compared with the control group (p < 0.05). The BMD of the regenerate bone was increased by a mean of 43% (p < 0.05). There was an increase of 22% in the mean area of regenerate formed in the pamidronate group (p < 0.05). Histological examination of bone in nine rabbits (5 control, 4 pamidronate) showed an increase in osteoblastic rimming and mineralisation of the regenerate, increased formation of bone around the pin sites and an increase in the cortical width of the bone adjacent to the regenerate in the rabbits given pamidronate. Pamidronate had a markedly positive effect. It reduced the disuse osteoporosis normally associated with lengthening using an external fixator and increased the amount and density of the regenerate bone. Further study is required to examine the mechanical properties of the regenerate after the administration of pamidronate.

Effect of pamidronate on distraction osteogenesis and fixator-related osteoporosis.

We examined the effect on bone mineral density (BMD), bone mineral content (BMC) and mechanical properties of a single 1.0 mg/kg dose of the bisphosphonate pamidronate (Novartis), in a distraction osteogenesis model in immature rabbits. Twenty rabbits underwent a tibial osteotomy. Ten rabbits received pamidronate 1.0 mg/kg via ear vein intra-operatively while 10 received saline infusions only. After a 24 h latency, all underwent distraction of 0.375 mm twice daily for 15 days. The animals were culled at 42 days. After culling, the distracted and non-distracted tibiae were examined by quantitative computer tomography (QCT). The volumetric bone mineral density (vBMD, mg/cm(3)) in the bone proximal and distal to the regenerate in the operated limb was increased by a mean of 11 and 14%, respectively, compared to controls (P<0.05). The vBMD of the regenerate bone was increased by a mean of 8% over controls (NS, P=0.17). The bone mineral content (BMC, mg) was increased by 23% (proximal and distal) (P<0.05) in the bone surrounding the lengthening and there was a 17% trend towards an increase in the regenerate (NS, P=0.3). Four-point bending analysis documented that the load to failure was increased by 32% from 436 to 574 N (P<0.01) in the pamidronate group. The modulus of elasticity was not different between the control and pamidronate groups (P=0.3), and in both groups was only approximately one-third of the intact tibiae (P<0.001). The administration of a single dose of pamidronate can improve the bone mineral density, content and mechanical properties of a bone undergoing distraction osteogenesis.

The hip in children with cerebral palsy. Predicting the outcome of soft tissue surgery.

This study reviewed 56 hips in 37 children with cerebral palsy who had undergone an adductor tenotomy alone or in combination with an anterior obturator neurectomy. The mean review period was 5.3 years. At latest review, 25 of 30 (83%) hips with a preoperative migration percentage of less than 40% were reduced, but 20 of 26 (77%) hips with a preoperative migration percentage of 40% or more were subluxated or dislocated. Surgery was unsuccessful for 13 of 15 hips with an acetabular index of more than 27 degrees. Percutaneous adductor tenotomy alone was as effective as the combination of an open procedure with an anterior obturator neurectomy. The age at the time of surgery did not have a significant effect on the outcome. The preoperative migration percentage was the only significant predictor of outcome in this group of children.

The pentothal test in the management of orthopaedic patients with hysterical illness.

Hysterical illness may be defined as symptoms normally associated with disease without pathological basis. Orthopaedics attracts more of these patients than most specialties. They are intensively and expensively investigated, yet clinicians remain anxious they are missing genuine pathology. We use examination under pentothal, without analgesia, to help distinguish real from imagined symptoms. The results of a review of patients evaluated under pentothal over the past two years are presented.

Zinc and genital infections.

The zinc status of 19 patients with chronic or recurrent genital infections and 18 patients with non-recurrent genital infections was assessed by measuring plasma and leucocyte zinc concentrations. Neither group of patients had plasma or leucocyte zinc concentrations that differed significantly from those of matched healthy controls. Each of six patients with chronic candidiasis had anergy to candidal antigen, as shown by delayed cutaneous hypersensitivity to intradermal injection of the antigen, but their zinc status was normal. This study provided no evidence of zinc deficiency in this small number of patients with acute non-recurrent or chronic recurrent genital infections.