Safety of recombinant human bone morphogenetic protein-2 after spinal laminectomy in the dog.

STUDY DESIGN: This was a randomized, blinded trial of the safety of the application of recombinant human bone morphogenetic protein (rhBMP)-2 or autologous bone graft onto a laminectomy defect of the dog in the presence or absence of a dural membrane puncture. OBJECTIVE: To test the safety of rhBMP-2 in an application in which direct contact of the material with neural tissue occurs. SUMMARY OF BACKGROUND DATA: Application of rhBMP-2 in laboratory animals stimulates local bone formation to effect spinal fusion and healing of segmental bone defects. The use of rhBMP-2 as a bone graft substitute in spinal fusion would eliminate donor site morbidity and may augment the rate of successful fusion. Because rhBMP-2 may unintentionally come in contact with neural tissue, the consequences of such a safety issue must be addressed in an animal model before human trials. METHODS: Twenty skeletally mature beagles underwent spinal exposure followed by bilateral laminectomy at L5. In half of the dogs, a puncture wound was made to the dura with the expression of cerebrospinal fluid at the site of the puncture. In randomly selected animals, the exposed dural elements received either autologous bone graft with the bone removed from the laminectomy site or an implant of the rhBMP-2 device. The animals was observed for 12 weeks with periodic clinical examinations and monthly computed tomographic scans. RESULTS: There was no clinical, radiographic, or histologic evidence of neurologic abnormalities in these animals. The rhBMP-2 stimulated bone growth in the laminectomy defect and came into direct contact with the dural membrane. There was no evidence of abnormal mineralization within the thecal sac or in the spinal cord itself. CONCLUSIONS: The rhBMP-2 implant stimulated bone formation in the laminectomy site. Neither autologous bone, rhBMP-2, nor the dural puncture had deleterious consequences for the animals.

Anatomical dissection of the deep posterior compartment and its correlation with clinical reports of chronic compartment syndrome involving the deep posterior compartment.

Patients with clinical presentation of deep posterior chronic compartment syndrome (CCS) frequently have symptoms limited to either proximal or distal components of the deep posterior compartment. In this study the posterior aspect of 15 cadaver legs was dissected to document anatomical separations and delineate boundaries, if any, of the deep posterior compartment and to correlate the findings to these patients. Origins of flexor hallucis longus (FHL), flexor digitorum longus (FDL), and tibialis posterior (TP), as well as whether TP existed in its own osseofascial compartment, were noted. Ten specimens had an identifiable distinct layer of tissue separating the deep posterior compartment into two potentially clinically relevant components. Much of this layer was derived from origins of FDL and its anatomical position in relation to the TP muscle. In seven of these cases, FDL had a significant fibular origin in addition to the well-established tibial origin. This essentially compartmentalized the distal third of the tibialis posterior as it descends anterior and medial to FDL in the lower one-third of the leg in five specimens. No cadaver possessed a significant fascial septum encasing TP and separating it from other deep posterior muscles. This study confirms the existence of a proximal and distal sub-compartment of the deep posterior compartment as a variant and supports the most frequent clinical presentation of deep posterior CCS as involving either the distal or proximal deep compartment, rather than the entire deep posterior compartment. The anatomic arrangement of muscles in the deep posterior compartment creates sub-compartments, which may explain the successful outcomes following a deep compartment release limited to symptomatic portion(s) of the deep compartment.

Cigarette smoking and its orthopedic consequences.

Cigarette smoking and its ramifications are coming under increasing scrutiny in the field of orthopedic surgery. Smoking has been implicated in impeding bone metabolism and fracture repair, and increasing the rate of postoperative infection and the incidence of nonunion. This article reviews the current body of knowledge on these topics, as well as the potential adverse effects of smoking on wound healing and microsurgical procedures. An in-depth discussion on the pathophysiologic mechanisms of nicotine is also included.