Interleukin-1 immunoreactive nerves in heterotopic bone induced by DBM.

The occurrence of interleukin-1-positive nerves was investigated by immunohistochemistry in developing heterotopic bone, induced by demineralized allogeneic bone matrix (DBM) in the rat. Interleukin-1 immunoreactivity was observed 1 week after implantation and remained until the end of the experiment at 12 weeks. Immunoreactive material was first identified in mononuclear cells at day 7. Interleukin-1 immunoreactive nerve fibers were first observed in the fibrous tissue at 2 weeks after implantation. A maximum density of fibers was reached at 8 weeks. Abundant immunofluorescent fibers were observed in the marrow tissue of the ossicles, and also in the surrounding fibrous tissue. A substantial number were vascular, but in the bone marrow most of the nerve fibers appeared as irregularly arranged, non-vascular terminals with ramifications and varicosities, intermingled between the marrow cells. No fibers could be detected in the proper bone tissue. The distribution of interleukin-1-positive nerves in the ossicles strongly resembled that previously observed in rat long bones. Moreover, the shape and distribution of the fibers exhibited a striking similarity to that of noradrenergic fibers identified previously both in ossicles and normal rat long bones. The late occurrence and predominant distribution in marrow tissue would seem to imply that neuronal interleukin-1 does not participate in the early differentiation of bone cells. The most important finding seems to be the presence of interleukin-1-positive nerve terminals in blood vessel walls and amidst marrow cells.

Enhancement of bone formation in rabbits by recombinant human growth hormone.

We studied the effect of human recombinant growth hormone on diaphyseal bone in 40 adult rabbits. The diaphyseal periosteum of one femur in each animal was mechanically stimulated by a nylon cerclage band. The bands induced an increase in bone formation, bone mineral content, and maximum torque capacity of the diaphyseal bone at 1 and 2 months. Growth hormone enhanced the anabolic effect of the cerclage bands on bone metabolism, evidenced by a further increase in torsional strength of the femurs.

Comparison of demineralized allogeneic bone matrix grafting (the Urist procedure) and the Ilizarov procedure in large diaphyseal defects in sheep.

The bone inductive capability of the Urist and Ilizarov procedures was compared in the repair of large diaphyseal defects in sheep. In 30 animals, a 4 cm segmental defect was created in the middle portion of the right femur and was stabilized with an external fixator. The sheep were divided into four groups according to the type of reconstruction of the defect. In group 1, a demineralized allogeneic bone matrix (DABM) cylinder was used; in group 2, DABM chips; and in group 3, gradual transport of a piece of bone detached from the proximal femoral fragment was used to fill the defect. Group 4 served as a control (the defect was left empty). New bone formation was assessed by serial radiographs until the time of death at 2 or 4 months. Postmortem specimens were analyzed with respect to bone mineral content, uptake of isotopes (45Ca and 3H-proline), and histology. The first signs of new bone formation were radiographically evident at 4 weeks. In the two groups in which reconstruction involved DABM (Urist procedures), new bone failed to form in eight of the 13 animals. Full bridging of the defect was observed at 8 weeks in one animal with a DABM cylinder and two with DABM chips. No decisive difference in bone yield could be demonstrated between the two Urist procedures. In the group treated with the Ilizarov procedure, new bone formation consistently occurred at a high rate; full bridging of the defect was observed in seven of the eight animals. Bone mineral scanning and histologic analysis essentially confirmed the radiographic results. Uptake of isotopes was selectively analyzed in two sheep from each experimental group in which new bone formation was exhibited in the defect; new bone formation was increased compared with that in the contralateral femur but was equal among the three experimental groups. Our study shows that gradual transport of a detached piece of autogeneic bone (Ilizarov procedure) is more effective than implantation of DABM (Urist procedure) in eliciting new bone formation in large diaphyseal defects in sheep. The variable bone induction by DABM may be explained by differences in host immune responses to the implants.

Stress protection by external fixation of the rabbit tibia.

Osteopenia of the tibia and femur caused by an external fixator in the tibia was studied in 14 rabbits. Eight rabbits were treated with a complete unilateral external fixator in one tibia, whereas the other tibia served as control. The other 6 animals had one leg operated on with inserting of all the pins but without the frame. This technique was chosen to compare osteopenia caused by stress protection and the effect of the pins. After 6 weeks, we found a 7 percent reduction in the bone mineral content in the tibial diaphyseal segment between the pins of the external fixator and no bone loss in the tibia that were operated on with only pins. In the femurs, there was a smaller decrease in the bone mineral content: respectively 3.2 percent (complete frame) and 2.9 percent (only pins). On all the operated on tibiae, there was an increase in the bone mineral content around the pins both proximally and distally.

Osteogenic enhancement of diaphyseal reconstruction. Comparison of bone grafts in the rabbit.

We investigated incorporation of autoclaved autografts in segmental defects of rabbit humeri for comparison with a previous study on similar grafts supplemented with demineralized allogeneic bone matrix (DABM). We also made similar reconstructions with frozen allografts--both DABM and nonsupplemented allografts. Before the animals were killed at 8 months, they underwent scintigraphy, showing that all 28 humeral reconstructions were metabolically active. Faxitrone radiography showed nonunion in three of nine with autoclaved autografts and in two of eight with frozen allografts, whereas all 11 DABM-supplemented frozen allografts had incorporated. Taking into account only the 23 healed reconstructions, the mean torsional strength in relation to the contralateral nonoperated on humeri was 0.81 for all three groups. Histologically, new bone enveloping, partly replacing, the implants was more abundant in DABM-supplemented reconstructions. Our study shows that osteogenic enhancement is more important than the type of nonviable bone chosen for diaphyseal repair. However, if healing is obtained, osteogenic enhancement per se does not increase the strength.

Long-term results of autotraction in the treatment of lumbago and sciatica. An attempt to correlate clinical results with objective parameters.

In a prospective study, 49 patients with sciatica radiating below the knee and with a duration of symptoms with no improvement for 6 weeks or more were treated with autotraction and followed up for 1 year. The patients were examined before and after treatment with thermography, and in addition to a clinical examination, they had to complete a form giving the history of their illness and an assessment of ADL. Seventy-nine percent of the patients conditions were good or improved after autotraction. These results were in accordance with the thermography and ADL score used as objective parameters. We therefore believe that the autotraction method of Gerturd Lind has a place in the treatment of chronic lumbago and sciatica.