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Purpose: Adjacent segment degeneration (ASD) is one of the major complications of lumbar fusion. Several previous retrospective studies reported ASD after PLIF. However, few reports evaluated whether decompression surgery combined with fusion surgery increases the rate of complications in adjacent segments. The purpose of the current study was to investigate the degeneration in decompressed adjacent segments after PLIF., Methods: A total of 23 patients (12 men, 11 women; average age, 58.6) who underwent PLIF surgery [1 level (n = 9), 2 levels (n = 8), 3 levels (n = 4), 4 levels (n = 2)] were included. Additional adjacent decompression above or below the level of interbody fusion was performed at 25 levels and no adjacent decompression was performed at 15 levels. We retrospectively investigated ASD by X-ray films of all 40 adjacent segments (above and below fusion level) and clinical outcomes of all 23 cases., Results: Of the 40 adjacent segments, 19 (47.5%) showed ASD and 9 (22.5%) showed symptomatic ASD. In the 19 segments with ASD, ASD occurred in 16 of 25 (64.0%) segments at decompressed sites compared with 3 of 15 (20.0%) non-decompressed sites. The ratio of ASD in adjacent segments was significantly higher at decompressed sites than at non-decompressed sites (p < 0.01)., Conclusion: ASD occurs frequently in association with additional decompression above or below the level of PLIF. In cases in which the adjacent segments require decompression, a surgical strategy that preserves as much of the posterior complex as possible should be selected.

Background: Our purpose was to examine platelet-rich plasma (PRP) for its effect on bone formation and to follow the immunohistochemical changes in calcitonin gene-related peptide (CGRP) in dorsal root ganglion neurons innervating the discs as a possible index of nociceptive nerve transmission in a rat model., Methods: A total of seventy rats were used. Ten constituted a non-punctured disc sham group, while another ten rats constituted a group that underwent puncture of the L4-L5 discs. Forty rats were in experimental groups in which the L4-L5 discs were punctured; posterolateral lumbar arthrodesis was performed with PRP (the PRP group) or without the use of PRP (the normal arthrodesis group), with twenty rats in each group. The remaining ten rats were used as blood donors. Four and eight weeks after surgery, microcomputed tomography examinations were done to evaluate the amount of bone and the L4-L5 spines were harvested to evaluate bone union, followed by resection of dorsal root ganglion neurons. The percentages of Fluoro-Gold-labeled and CGRP-immunoreactive neurons were calculated., Results: The platelet count and the concentration of growth factors in PRP were higher than those in blood (p &lt; 0.05). The bone volumes observed in the PRP group were significantly greater than those of the normal arthrodesis group at four and eight weeks (p &lt; 0.05). Three (30%; 95% confidence interval [CI], 6% to 65%) of ten rats in the normal arthrodesis group and eight (80%; 95% CI, 44% to 98%) of ten rats in the PRP group were considered to have bone fusion four weeks after surgery (p &lt; 0.05). At eight weeks, seven (70%; 95% CI, 34% to 94%) of ten rats in the normal arthrodesis group and nine (90%; 95% CI, 55% to 99%) of ten rats in the PRP group were considered to have bone fusion (p = 0.27). The proportion of CGRP-immunoreactive neurons was significantly greater in the punctured group than in the other groups. There were no significant differences between the normal arthrodesis group and the PRP group., Conclusions: PRP appears to promote bone formation in rats and has a tendency to shorten the period of bone union in this rat model of posterolateral lumbar arthrodesis, but it did not influence the proportion of CGRP-immunoreactive neurons, a likely indicator of inflammatory pain originating from the degenerative intervertebral disc., Clinical Relevance: The ability of PRP in this model suggests that it may be able to shorten the period of union and lead to an early return to social activities after treatment.

Study Design: A prospective interventional trial, using a rat model of lumbar interbody fusion., Objective: To examine the potential efficacy of platelet-rich plasma (PRP) for lumbar interbody fusion, using hydroxyapatite (HA)., Summary of Background Data: PRP is an autologous product containing a high concentration of platelets in a small volume of plasma and has osteoinductive effects. HA has osteoconductive ability and has been used in combination with autogenous bone for spine fusion. However, reports using PRP with HA for spine fusion are very few. The purpose of this study was to examine the efficacy of PRP with HA for spinal interbody fusion and at the same time to estimate the change in immunoreactivity of the inflammatory neuropeptide, calcitonin gene-related peptide (CGRP), in dorsal root ganglion (DRG) neurons innervating spinal discs., Methods: A total of 35 Sprague-Dawley rats were used in this study. Twenty-one rats were used for conducting interbody fusion experiments, 7 rats were used as immunostaining controls, and 7 other rats were used as blood donors for making PRP. L5-L6 interbody fusion was performed on 21 rats using HA + PRP (n = 7), HA + platelet-poor plasma (n = 7), or HA + saline (n = 7). Simultaneously, Fluoro-Gold neurotracer was applied to the intervertebral space to detect DRG neurons innervating the discs. L5-L6 lumbar radiographs were obtained and lumbar DRGs were immunostained for CGRP. The rate of bone union and the change in CGRP immunoreactive DRG neurons innervating the discs were evaluated and compared among groups., Results: All L5-L6 lumbar discs were fused in the PRP + HA group (fused 7/total 7), whereas only 1 case was fused in the platelet-poor plasma group (1 of 7) and no cases in the HA-only group (0 of 7), which was a significant difference. Upon immunohistochemical analysis, CGRP-positive neurons innervated L5-L6 intervertebral discs in nonunion cases, and these were significantly increased compared with those in union cases., Conclusion: Our study suggests that using PRP with HA was beneficial for spine fusion. This combination may promote bone union and also decrease inflammatory neuropeptide in sensory neurons innervating the discs.

Study Design: Prospective trial., Objective: To examine the bone union and clinical results after unilateral or bilateral instrumented posterolateral fusion surgery using a local bone graft., Summary of Background Data: The iliac crest bone graft technique for lumbar posterolateral fusion surgery is widely used; however, donor site problems such as pain and sensory disturbance have been reported. Local bone has been used for bilateral multisegment fusion surgery; however, outcomes have been poor because of insufficient amounts of local bone used. This study evaluated unilateral and bilateral posterolateral fusion at 3 levels using a local bone graft., Methods: Sixty-two patients diagnosed with degenerated spondylolisthesis at 3 levels were divided into 2 groups. All underwent decompression and bilateral instrumented posterolateral fusion. However, a unilateral local bone graft was used in 32 patients and bilateral local bone graft was used in 30 patients. The amount of bone grafting, proportion of patients with bone union, duration of bone union, visual analog scale score, Japanese Orthopedic Association score, and Oswestry Disability Index were evaluated before and 2 years after surgery., Results: Visual analog scale score, Japanese Orthopedic Association score, and Oswestry Disability Index were not significantly different between the 2 groups before and after surgery (P > 0.05). The amount of local bone graft used for each segment was significantly less in the bilateral group (P < 0.05). The proportion of patients with rates of bone union and instability were 86% and 9%, respectively, in the unilateral group, but significantly poorer at 60% and 34% in the bilateral group., Conclusion: If multisegment fusion (3-level fusion) is performed, bilateral local bone grafting results in a poor rate of bone union because of an insufficiency of local bone. Unilateral bone grafting is recommended because better rates of bone union and stability are achieved.

Study Design: Prospective trial., Objective: To examine the difference in bone union and clinical results after one-, two-, and three-level instrumented posterolateral fusion surgery using a local bone graft., Summary of Background Data: The iliac crest bone graft technique for lumbar posterolateral fusion surgery is widely used; however, donor site problems such as pain and sensory disturbance have been reported. Local bone has been used for fusion surgery; however, its reliability as a graft for multiple segments has not been fully reported., Methods: One hundred twenty-two patients diagnosed with degenerated spondylolisthesis were divided into three groups [spondylolisthesis at 1 level (n = 42), at 2 levels (n = 40), and at 3 levels (n = 40)]. All patients underwent decompression and instrumented posterolateral fusion with a local bone graft. The amount of bone graft, proportion of patients with (rate) and duration of bone union, Visual Analog Scale (VAS) score, Japanese Orthopedic Association Score (JOAS), and Oswestry Disability Index (ODI) were evaluated before and 2 years after therapy., Results: VAS score, JOA score, and ODI were not significantly different among the three groups before and after surgery (P > 0.05). Average amount of local bone graft used for one segment significantly decreased in proportion to the number of fusion levels (P < 0.05). The rate of bone union was 88% in the one-level group, 85% in the two-level group, and 62.5% in the three-level group, which was significantly lower than that in the one- and two-level groups (P < 0.05)., Conclusion: If one- and two-level posterolateral fusion were performed, the local bone graft technique provides a good and uniform bone union rate; however, for three-level fusion poor results were obtained because of an insufficient amount of local bone.

Background: Surgery for lumbar spondylolisthesis is widely performed. However, there have been no reports comparing posterolateral and anterior interbody fusion prospectively. We compared instrumented posterolateral fusion with anterior interbody fusion for L4 spondylolisthesis in a prospective study., Methods: Forty-six patients diagnosed with L4 degenerated spondylolisthesis were divided into two groups. Twenty-two consecutive patients underwent non-instrumented anterior interbody fusion using an iliac bone graft (ALIF; L4-L5 level), and 24 consecutive patients underwent instrumented posterolateral fusion with local bone (PLF; L4-L5 level). The rates of bone union, visual analog scale (VAS) score, Japanese Orthopedic Association (JOA) score, Oswestry Disability Index (ODI), surgical invasion, and complications were evaluated before and 2 years after surgery., Results: Age, VAS score, JOA score, and ODI were not significantly different between the two groups before surgery (P > 0.05). Success of bone union between the two groups was not significantly different (P > 0.05). Blood loss during surgery was significantly less; however, periods of bed rest and hospital stay were significantly longer in the ALIF group (P < 0.05). Overall patient satisfaction, and low back and leg pain in both groups were significantly improved after surgery; however, low back pain showed greater improvement in the ALIF group compared with the PLF group (P < 0.05). Complications such as donor site pain (4 patients in the ALIF group) and dural tearing (3 patients in the PLF group) were observed., Conclusions: If single level fusion for L4 spondylolisthesis is performed, both anterior and posterior methods reduce patients' low back and leg pain. Improvement of low back pain was significantly greater after ALIF; however, periods of hospital stay and of bed rest were significantly longer.

The iliac crest bone grafting (ICBG) technique for lumbar posterolateral fusion surgery is widely used; however, donor site problems such as pain and sensory disturbance have been reported. Local bone is available for fusion surgery, but its reliability as a graft has not been fully reported. In the current study, we examined single-level instrumented posterolateral fusion with a local bone graft versus an ICBG in a prospective randomized study. Eighty-two patients diagnosed with L4 degenerated spondylolisthesis were divided into two groups at random. Forty-two patients underwent instrumented posterolateral fusion with a local bone graft (L4-L5 level), and 40 patients underwent instrumented posterolateral fusion with an ICBG (L4-L5 level). Rate and duration of bone union, visual analog scale (VAS) score, Japanese orthopedic association score (JOAS), Oswestry Disability Index (ODI), and complications were evaluated before and 2 years after therapy. VAS score, JOAS, and ODI were not significantly different between the two groups before and after surgery (P > 0.05). Rate and average duration of bone union were 90% and 8.5 months in the local bone graft group, and 85% and 7.7 months in the ICBG group, but without significant difference (P > 0.05). Prolonged surgical time and complications such as donor site pain (8 patients) and sensory disturbance (6 patients) were observed in the ICBG group. If single-level posterolateral fusion was performed, local bone graft technique has the same bone union rate compared with ICBG, requires less surgical time, and has fewer complications.

Study Design: Prospective radiographic outcome analysis., Objective: Radiographic evaluation of the rigidity of monocortical and tricortical purchase in lumbosacral fixation., Summary of Background Data: The lumbosacral junction continues to be a difficult region to obtain a successful spinal arthrodesis and is one of the primary regions for construct failure. In inserting sacral screws, 3 types of purchase are known: monocortical, bicortical, and tricortical. Among them no clinical or basic studies have compared monocortical with tricortical purchase., Methods: Ninety consecutive patients diagnosed with spondylolisthesis who underwent lumbosacral fixation were evaluated. Fifty-three patients were treated with a monocortical approach and the other 37 patients were treated with a tricortical approach. Patients underwent surgery for posterolateral fusion or transforaminal lumbar interbody fusion (TLIF) according to their diagnosis. Their radiologic findings, radiolucent zones around sacral screws, and lumbosacral instability of more than 2° flexion just after the surgery and 1 year later were compared. The angulation and length of the inserted screw were also measured and evaluated., Results: There were no significances in the distributions of gender, average age, proportion of fixation method, and fusion range between the monocortical and tricortical groups (P > 0.05). Radiolucent zones and lumbosacral instability were more prevalent in the monocortical group than were in the tricortical group. Smaller angulation also affected the outcome in the monocortical group while screw length did not. Multivariate logistic regression analysis of possible risk factors revealed that female gender (odds ratio [OR]: 3.56, 95% confidence interval [CI]: 1.18-10.8), TLIF operative method (OR: 5.54, 95% CI: 1.08-8.2), number of fusion levels (OR: 1.84, 95% CI: 1.05-3.18), and monocortical purchase (OR: 7.11, 95% CI: 1.58-31.9) were statistically significant., Conclusion: More loosening of sacral screws was radiographically observed in the monocortical purchase group than in the tricortical group 1 year after the lumbosacral fixation surgery. A statistical analysis indicated that the tricortical approach should be used for patients undergoing multilevel fusion including lumbosacral junction by TLIF.

Study Design: Prospective cohort study., Objective: To examine the change of Modic Type 1 to Type 2 after posterolateral fusion surgery., Summary of Background Data: Lumbar vertebral bone marrow change is divided into Modic types. Magnetic resonance imaging reveals Modic Type 1 and 2 signals. Some reports indicate that with time, Type 1 signals (intervertebral instability) change to Type 2 (restabilization), but the reliability of this assertion is unclear. The current study examines the change of Modic Type 1 signals to Type 2 after posterolateral fusion surgery., Methods: Patients with Modic Type 1 and 2 signals were selected (mean age, 65 years). All patients suffered low back pain and leg pain due to lumbar spinal canal stenosis, and underwent decompression and posterolateral fusion surgery. We evaluated change in Modic signal and severity of low back pain (Visual analogue scale score, Japanese Orthopedic Association score, and Oswestry Disability Index before and 24 months after surgery., Results: Of 21 patients with Modic Type 1 signals before surgery, 2 cases changed to normal bone marrow, 9 to Type 2, and 12 remained Type 1. Of 12 patients with Type 2 signals, none changed to Type 1, 2 changed to normal bone marrow, and 10 remained Type 2. Visual analogue scale score, Japanese Orthopedic Association score, and Oswestry Disability Index improved after surgery; however, low back pain was not significantly associated with signal change after surgery (P > 0.05)., Conclusion: In the current study, Modic Type 1 signals changed to Type 2; however, Type 2 did not change to Type 1, suggesting that Type 2 signals indicate a stabilized stage. For Modic Type 1 and 2 signals, there were changes to normal bone marrow signals in 4 cases. Therefore, degenerated bone marrow may be able to regenerate after surgical stabilization. We did not show a significant difference between low back pain and signal type.