Cervical interbody fusion cages. An animal model with and without bone morphogenetic protein.

STUDY DESIGN: The Alpine goat model for multilevel anterior cervical discectomy and fusion was used to analyze the use of an intervertebral fusion device to promote an arthrodesis after anterior cervical discectomy. Comparisons were drawn with biomechanical, histologic, and radiographic data. OBJECTIVES: To analyze the use of an intervertebral fusion device, with and without a bone graft substitute, to promote an arthrodesis anterior cervical discectomy. SUMMARY OF BACKGROUND DATA: In previous studies, the goat cervical spine has proven to be an excellent model for examining the healing of fusions using bone grafts, instrumentation, or bone substitutes. METHODS: Three-level anterior cervical dissectomies were performed on 21 mature Alpine goats. Three treatment groups of seven goats each were used. Group I used a standard titanium cervical BAK device filled with autogenous bone graft. Group II used a hydroxyapatite-coated BAK device filled with autogenous bone graft. Group III used a BAK device filled with recombinant human bone morphogenetic protein-2. RESULTS: Radiographically, no cages became displaced. Lucencies were seen around 3 of the 21 cages in Group 1, 4 cages in Group II, and none in Group III. Fluorochrome analysis revealed that the recombinant human bone morphogenetic protein-2-filled cages had an accelerated rate of bone growth around and through each cage-vertebral body interface at 3 weeks. A successful arthrodesis was also more likely with a recombinant human bone morphogenetic protein-2-filled cage (95%) than the hydroxyapatite-coated (62%) or the standard (48%) cage. Biomechanical stiffness testing did not reveal any statistically significant differences between the three groups. There was a tendency for successfully arthrodesed interspaces to be stiffer than those that were not. CONCLUSIONS: The use of a threaded intervertebral fusion cage, with or without hydroxyapatite coating, filled with autogenous bone graft provides a fusion rate that is slightly better than those previously reported using autogenous interbody bone grafts with or without plate stabilization. Recombinant human bone morphogenetic protein-2-filled cages resulted in a much higher arthrodesis rate and accelerated bone formation compared with either autogenous bone-filled BAK devices, or autogenous interbody bone grafts with or without plate stabilization.

Hypertension control in Harare municipal clinics.

Treatment of hypertension is a growing burden on urban health services in Zimbabwe. In 1980, the Harare Health Department began a separate registry, staffed by a nurse, for management of patients with stable hypertension (diastolic blood pressure (DBP less than 100 mmHg) on treatment). We evaluated this programme in a retrospective review of 437 medical records. The average age of patients was 17.5 years; two-thirds were women. Upon referral 324 patients (74 percent) had a DBP less than mmHg. Sixty-five percent of patients had no DBP greater than 100 mmHg during follow-up. Patients with DBP greater than 20 mmHg were more likely to be treated with two drugs, seen more often or referred (p less than 05). One-third of patients enrolled between 1980-1986 were lost to follow-up. Of those who did not default, few attended regularly. We conclude that a nurse can successfully manage patients with stable hypertension, although more aggressive treatment and improved compliance would have resulted in better control. At current levels of loss to follow-up, this programme is unlikely to have much effect on the public health impact of hypertension. The main challenge is to improve patient compliance.