RESUMO
STUDY DESIGN: Disk material removed (DMR) during L4-5 and L5-S1 transforaminal lumbar interbody fusion (T-LIF) surgery was compared to the corresponding bone graft (BG) volumes inserted at the time of fusion. A novel BG delivery tool (BGDT) was used to apply the BG. In order to establish the percentage of DMR during T-LIF, it was compared to DMR during anterior diskectomy (AD). This study was performed prospectively. SUMMARY OF BACKGROUND DATA: Minimal information is available as to the volume of DMR during a T-LIF procedure, and the relationship between DMR and BG delivered is unknown. BG insertion has been empiric and technically challenging. Since the volume of BG applied to the prepared disk space likely impacts the probability of arthrodesis, an investigation is justified. METHODS: A total of 65 patients with pathology at L4-5 and/or L5-S1 necessitating fusion were treated with a minimally invasive T-LIF procedure. DMR was volumetrically measured during disk space preparation. BG material consisting of local autograft, BG extender, and bone marrow aspirate were mixed to form a slurry. BG slurry was injected into the disk space using a novel BGDT and measured volumetrically. An additional 29 patients who were treated with L5-S1 AD were compared to L5-S1 T-LIF DMR to determine the percent of T-LIF DMR relative to AD. RESULTS: DMR volumes averaged 3.6±2.2 mL. This represented 34% of the disk space relative to AD. The amount of BG delivered to the disk spaces was 9.3±3.2 mL, which is 2.6±2.2 times the amount of DMR. The BGDT allowed uncomplicated filling of the disk space in <1 minute. CONCLUSION: The volume of DMR during T-LIF allows for a predictable volume of BG delivery. The BGDT allowed complete filling of the entire prepared disk space. The T-LIF diskectomy debrides 34% of the disk relative to AD.
RESUMO
STUDY DESIGN: The posterior ligament of the human sacroiliac joint was examined for nerves and nerve endings using histologic and immunohistochemical techniques. OBJECTIVE: To identify nerve fibers and mechanoreceptors in the posterior ligament. SUMMARY OF BACKGROUND DATA: According to the findings of previous studies, the human sacroiliac joint receives myelinated and unmyelinated axons that presumably conduct pain and proprioceptive impulses derived from mechanoreceptors and free nerve endings in the human sacroiliac joint. METHODS: Tissue obtained from six patients was stained with gold chloride and that obtained from six additional patients was stained using antibodies specific for substance P and protein gene product 9.5. RESULTS: The staining of joint tissue using the gold chloride technique showed myelinated and unmyelinated nerve fibers, two morphotypes of paciniform encapsulated mechanoreceptors, and a single nonpaciniform mechanoreceptor. Analysis using immunohistochemical staining for protein gene product 9.5 did not unequivocally show axons, nerve fascicles, or mechanoreceptors. Similarly, analysis based on immunohistochemical staining for substance P, one of several neurotransmitters known to signal pain from the periphery, showed reactive elements that may have been nerves, but because of background staining, could not be positively identified as such. CONCLUSIONS: The presence of nerve fibers and mechanoreceptors in the sacroiliac ligament demonstrates that the central nervous system receives information, certainly proprioceptive, and possibly pain from the sacroiliac joint. Although it is not known how the central nervous system uses such information, it seems reasonable to speculate that the proprioceptive information is used to optimize upper body balance at this joint. In addition, because the staining techniques used generally to show nerves and nerve elements in periarticular connective tissue are nonspecific, the distinction between neural and nonneural should be made on the basis of both morphologic and staining characteristics.