Expression of epidermal growth factor and transforming growth factor alpha in interfacial membranes retrieved at revision total hip arthroplasty.

BACKGROUND: The interfacial membrane between bone and implant has been shown to be a key tissue in the process of aseptic loosening of total hip arthroplasty. The cells within the interfacial membrane produce numerous inflammatory mediators which, through complex mechanisms, cause periprosthetic osteolysis and aseptic loosening. Both epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha) have similar biological functions. They have been found to stimulate bone resorption. OBJECTIVE: To investigate the presence, cellular localisation, and extent of expression of EGF and TGFalpha in interfacial membrane retrieved from revision total hip arthroplasty and compare it with that in synovial membrane from primary total hip arthroplasty. METHODS: Ten interfacial membranes and 10 synovial membranes were stained with avidin-biotin-peroxidase complex for EGF and TGFalpha. The staining process was done using the Lab Vision Autostainer. The results were measured by a semiautomatic VIDAS image analysis system. RESULTS: Immunoreactivity for both EGF and TGFalpha was found in the endothelial cells of blood vessels, macrophages, and fibroblasts, both in interfacial membranes and synovial membranes. However, the number of EGF (980 (370)) and TGFalpha (1070 (360)) positive cells per mm(2) was greater in interfacial membranes than in the synovial membranes (220 (200), 270 (100); p<0.01). CONCLUSION: It is suggested that owing to their increased expression in interfacial membrane, EGF and TGFalpha may have an important pathogenetic role in stimulating periprosthetic bone resorption in aseptic loosening of total hip arthroplasty.

The clinical and radiological outcome of the rotating hinged knee prostheses in the long-term.

BACKGROUND AND AIMS: Opinions about hinged knee prostheses vary a lot in different studies. We wanted to examine our series in order to gain long-term information about this kind of knee prosthesis. MATERIAL AND METHODS: Forty-eight (18 Kinematic Hinge and 30 Link Endo Model) rotating hinged knee prostheses were implanted in the Hospital of Invalid Foundation. All knees were retrospectively followed up for an average of 66.3 months and examined for clinical or radiological factors indicating the overall outcome. RESULTS: In the latest review there were 10 patients (20.8%) regarded as having unsatisfactory and 35 patients (79.2%) satisfactory results. Eighty-four per cent of the patients were subjectively satisfied with the operation, mostly because of the painless result. CONCLUSIONS: Taking into account the very poor initial status of these patients, we recommend the rotating hinged prostheses still to be used in severely instable knees awaiting revision.

Proliferation of the hypertrophic chondrocytes of the growth plate after physeal distraction. An experimental study in rabbits.

Reports on the effects of physeal distraction on chondrocyte proliferation are controversial, and the biologic mechanism of lengthening is still open. Proliferation of the growth plate chondrocytes was studied after gradual physeal distraction in 12 growing rabbits. Distraction of the distal femoral physis was performed with an external fixation device for three to 14 days. Proliferating cells were labeled with 5-bromo-2'-deoxyuridine one hour before killing the animal, and labeled chondrocytes were localized with a specific monoclonal antibody. Labeled chondrocytes were observed in the hypertrophic zone after distraction of three to seven days, in addition to labeling in the proliferative zone; in the remaining physes, the distribution of labeled cells was normal. Physeal widening occurred in all distracted specimens, and a fracture-separation, usually through the hypertrophic zone, in all but one. The labeled hypertrophic cells were seen on the epiphyseal side of the separation gap, five to 20 cells in each specimen. Although hypertrophic chondrocytes are known to be metabolically active, proliferation of these cells has never been reported before. Hypertrophic chondrocytes seem capable of proliferation under special circumstances.

Nonspecific diskitis in children. A nonmicrobial disease?

Eighteen patients were treated for nonspecific diskitis (diskitis without microbial cause) at the University Children's Hospital in Helsinki during 1970-1990. The mean age at admission was three years three months. The characteristic findings were restriction of spinal mobility and an elevated erythrocyte sedimentation rate (ESR). Radiographic narrowing of the affected disk space was seen four to five weeks after the initial symptoms. An operative biopsy was made in 16 patients, the histologic diagnosis being chronic or subacute nonspecific inflammation in ten, other nonspecific changes in two, and normal tissue in five. Treatment was either bed rest and antimicrobial medication, or bed rest alone. After a follow-up period of five months to nine years, all patients were clinically normal. All but two had radiographic signs of healed disk space defects. Nonspecific diskitis in children is an entity with unknown cause. The clinical picture is typical, but diagnostic difficulties may be encountered during the first weeks when radiographic signs are absent. The disease is self-limiting in most cases, and only minor radiographic changes remain after healing. The results after routine operative biopsy raise the question of a possible nonmicrobial cause.

Effects of distraction and compression on proliferation of growth plate chondrocytes. A study in rabbits.

An external fixation device was applied across the distal femoral physis in 30 rabbits, and distraction or compression was performed for 3-21 days; either no operation or a sham-operation was performed on the contralateral side. Proliferating cells were labeled with 5-bromo-2'-deoxyuridine, a thymidine analogue, and subsequently localized in decalcified histologic sections using a specific monoclonal antibody. The height of the proliferative and hypertrophic zones was increased after distraction; additionally, fracture-separation through the hypertrophic zone or at the junction of the physis and metaphysis was seen in 13 of the 15 specimens. Labeled cells were encountered only in the proliferative zone in all specimens except after early distraction, where labeled chondrocytes were seen close to the separation gap in the hypertrophic zone, too. Distraction had no effect on the number of labeled cells. A reduction in the height of the proliferative and hypertrophic zones occurred after compression, and the number of proliferating chondrocytes decreased.

Effects of physeal distraction on the vascular supply of the growth area: a microangiographical study in rabbits.

To study the effects of physeal distraction on growth plate vascularity, microangiography was performed in 45 growing rabbits. Marked enlargement of the epiphyseal arteries and defective metaphyseal capillary filling were observed in association with hyperplasia and separation of the physes after 3 days of distraction, and the changes still persisted locally in specimens distracted for 21 days. New capillaries were observed in the hyperplastic physes and in separation gaps at 21 days. Vascular anastomoses across the physes were noted after 6 weeks of follow-up. Epiphyseal capillary enlargement may indicate increased nutritional demands of the physis, whereas metaphyseal changes are probably related to separation in the hypertrophic chondrocyte zone.

Distraction effects on the physis in rabbits.

Gradual physeal distraction by external fixation was performed on the distal femur in 19 growing rabbits. The rate of distraction was 0.5-1 mm once daily. Distraction was continued for 1-21 days until killing. Lengthening of the femur and latitudinal growth of the distraction area were measured in radiographs. Morphologic changes in the physes were studied in histologic preparations. The length gained by distraction was maximally 5 mm. Latitudinal overgrowth was noted in specimens distracted for more than 13 days. Hyperplasia of the hypertrophic chondrocyte zone was seen after 1 day of distraction. Separation of the epiphysis from the metaphysis, mostly through the hypertrophic zone, occurred in 11 specimens. Both hyperplasia and separation were often seen in the same physis. In the separation gap, early signs of bone formation into a collagen frame were seen from the 7th day on. An accessory physis, located in the metaphysis and apparently growing interstitially, was noted in 1 specimen.

Early semiclosed intramedullary stabilization in osteogenesis imperfecta.

Fourteen patients with severe osteogenesis imperfecta (OI) were treated operatively by closed or semiclosed intramedullary stabilization, with nonextensible rods and nails. Altogether, 55 bones (both upper and lower limbs) were stabilized primarily. In infants with a severe form of OI (Sillence classification), the operative technique was modified significantly from those presented earlier in the literature. Early intramedullary stabilization, even soon after birth, seems justified in selected patients with severe OI. The possibilities for motor development are improved and later insertion of telescoping nails becomes easier.