Effect of anular repair on the healing strength of the intervertebral disc: a sheep model.

STUDY DESIGN: The intervertebral disc, in a sheep model, was used to assess the effect of directly repairing three different anular incisions on the subsequent healing strength of the intervertebral disc. OBJECTIVES: To assess whether directly repairing an anular defect, made at the time of lumbar discectomy, could influence the healing rate and strength of the anulus fibrosus. METHODS: Twenty-four sheep underwent a retroperitoneal approach to five lumbar disc levels. An anular incision, followed by partial discectomy was done at each exposed level. Anular incisions used in this study consisted of 1) a straight transverse slit, 2) a cruciate incision, and 3) a window or box excision. Healing strength was measured at three time intervals: 2 weeks, 4 weeks, and 6 weeks. Each anular incision type was performed on 30 lumbar discs, 10 discs in each time interval. Five discs in each time interval underwent direct repair, and five discs were left unrepaired to heal as controls. The sheep were killed at 2, 4, and 6 weeks after surgery. The lumbar spines were removed en bloc, and the intervertebral discs were subjected to pressure-volume testing to assess the anular strength of repaired versus unrepaired disc injuries at each time interval. RESULTS: Statistical analysis was performed to evaluate the effects of healing time, incision technique, and repair on the pressure-volume characteristics of the involved discs. Pressure-volume testing showed trends of stronger healing for repaired discs, but at no time interval was any significant difference found between repaired and nonrepaired anular strength. Of the nonrepaired discs, the box incision was only 40 to 50% as strong as the slit or cruciate incised discs during early healing. CONCLUSION: Direct repair of anular incisions in the lumbar spine does not significantly alter the healing strength of the intervertebral disc after lumbar discectomy.

The role of prophylactic antibiotics in spinal instrumentation. A rabbit model.

STUDY DESIGN: A rabbit model was used to test the efficacy of cefazolin administered in various therapeutic regimens in preventing iatrogenic Staphylococcus aureus infections during spinal instrumentation. OBJECTIVE: To assess the efficacy of various prophylactic therapeutic regimens of cefazolin in preventing iatrogenic S. aureus infections during spinal instrumentation. SUMMARY OF BACKGROUND DATA: Previous studies have not dealt specifically with the occurrence of iatrogenic S. aureus infections during spinal instrumentation in a prospective fashion. METHODS: Twenty New Zealand White rabbits underwent a posterior approach to the lumbar spine. Fifteen of the animals then had double-braided 26-gauge surgical wire placed around bilateral L3-L4 and L4-L5 facet joints. A standardized volume of a 103 S. aureus/mL of solution was then inoculated onto the fusion-hardware site in all rabbits. The rabbits were divided into four groups receiving various antibiotic dose regimens. Five days after surgery, the animals were killed, and cultures were obtained. RESULTS: All of the rabbits receiving no antibiotic had fusion sites infected with S. aureus. None of the animals who received prophylactic cefazolin produced cultures that grew S. aureus. A specimen from one fusion site cultured Staphylococcus epidermidis, which is not sensitive to cefazolin. Analysis of these data using Fisher's exact test resulted in a P value of 0.008 when results in antibiotic groups were compared with those in a group receiving no antibiotics and a P value of 0.0003 when all groups were compared. CONCLUSIONS: This model was valid and reproducible for the study of spinal instrumentation and infection. In addition, the data support the efficacy and use of prophylactic intravenous antibiotics in preventing infection in spinal instrumentation and fusion surgery.

The effect of prophylactic antibiotics on iatrogenic intervertebral disc infections. a rabbit model.

STUDY DESIGN: A rabbit model was used to test the efficacy of two commonly used prophylactic antibiotics, cefazolin and vancomycin, in preventing iatrogenically introduced Staphylococcus aureus intervertebral disc infections. OBJECTIVE: This study was performed to assess the efficacy of two prophylactic antibiotics in preventing iatrogenically introduced Staphylococcus aureus intervertebral disc infections. SUMMARY OF BACKGROUND DATA: Previous studies have had conflicting results regarding the penetration of antibiotics into the nucleus pulposus and their ability to eradicate infection. METHODS: In this study, 40 adult New Zealand White rabbits underwent inoculation of 10(1) or 10(3) Staphylococcus aureus/ml into 3-6 lumbar intervertebral discs under direct visualization. Either no antibiotics (control groups) or various preoperative and postoperative dosing schedules of cefazolin or vancomycin were given intravenously. Five days after surgery, the discs were harvested and cultured. RESULTS: All 40 discs inoculated in the control groups became infected. None of the 35 discs inoculated in the cefazolin groups became infected. Infection developed in 23 of 107 discs inoculated in the vancomycin groups. Most notable of these were 17 of 17 positive cultures in animals given vancomycin 8 hours preoperatively only. CONCLUSIONS: Based on these results, it was concluded that intravenous cefazolin or vancomycin given within 1 hour before surgery can effectively prevent postoperative discitis. No advantage was found with additional postoperative antibiotics.

Musculoskeletal involvement in children with gastroschisis and omphalocele.

A review of 58 children with gastroschisis and 8 children with omphalocele showed 14 musculoskeletal problems in 11 children. These problems consisted of limb deformities in 6 children, spinal deformities in 4 children, and osteopenia in 3 children, with 1 of the osteopenic children developing pathological fractures. About one third (5/14) of the problems were arthrogrypotic in nature. The remainder were mild digital deformities, developmental or spondylodysplastic scolioses, and, rarely, congenital spinal deformities.

Musculoskeletal aspects of prune-belly syndrome. Description and pathogenesis.

OBJECTIVE: To determine the types and prevalence of musculoskeletal involvement in children with prune-belly syndrome, and to analyze the pathogenesis of the syndrome in relationship to the musculoskeletal deformities. DESIGN: A retrospective review of charts and roentgenograms along with a comprehensive review of 188 cases from the literature. SETTING: Tertiary care children's hospital. PARTICIPANTS: Twelve boys treated between 1975 and 1990. MEASUREMENTS/MAIN RESULTS: The prevalence of musculoskeletal involvement in patients was 45%. The involvement can be congenital (eg, clubfeet, limb deficiencies, teratologic hip dysplasia, and vertebral malformations) or developmental (eg, renal osteodystrophy, scoliosis, and pectus excavatum and/or pectus carinatum). The embryologic characteristics of congenital musculoskeletal problems correlate better with the embryologic theory of the prune-belly syndrome (an aberration of mesenchymal development around 6 weeks of gestation) than with the distal urinary tract obstructive theory. CONCLUSION: Since children with prune-belly syndrome are now living into adulthood, these musculoskeletal aspects will become important regarding potential morbidity.