中村 順一

The number of patients showing lumbar degenerative scoliosis, including disc wedging, has increased, and examination of the mechanism of spinal nerve compression due to lateral and rotational mobility of the lumbar spine is necessary. Thirty-two patients with L4-L5 disc wedging but without antero- or retrospondylolisthesis and ten age-matched controls were examined. The angle of disc wedging and change in the angle between left and right bending were evaluated by anterior-posterior X-ray images of patients while they were in a standing position. The degree of disc degeneration and existence of vacuum phenomena were evaluated at the L4-L5 discs. Rotational mobility between maximal right and left rotation was examined by computed tomography (CT). Rotational mobility was measured using the spinal transverse processes of L4 and L5. The relationship between these factors was statistically evaluated using multivariate analysis and Spearman's correlation test. There was a significant increase in the average rotational mobility of the L4-L5 disc-wedging group. In the L4-L5 disc-wedging group, the increased angle of disc wedging and change in the angle between left and right bending correlated with increased rotational mobility. The degree of disc degeneration did not affect rotational mobility. However, existence of vacuum phenomena increased the rotational mobility of the L4-L5 disc-wedging group. This is the first study to evaluate the rotational hypermobility of L4-L5 disc wedging in patients without antero- or retrospondylolisthesis using kinematic CT. Increases in the wedging angle and abnormal instability of lateral bending correlated with increased rotational mobility. For surgical planning of degenerative L4-L5 disc wedging, it is important to consider rotational hypermobility using kinematic CT or X-ray imaging findings of lateral bending.

STUDY DESIGN: Prospective cohort study. OBJECTIVE: To examine the relationship between low back pain after discectomy for disc herniation and Modic type 1 change. SUMMARY OF BACKGROUND DATA: Lumbar vertebral bone marrow change is divided into Modic types. Some reports indicate that Modic type 1 is related to low back pain, but the reliability of this assertion is unclear. The current study examines changes in low back pain in patients with lumbar disc herniation and Modic type 1 change after lumbar discectomy without fusion surgery. METHODS: Forty-five patients with lumbar disc herniation showing normal or Modic type 1 signals in their bone marrow were selected (mean age 35 years). All patients suffered low back and leg pain because of lumbar disc herniation, and underwent a discectomy without fusion. We evaluated change in low back pain [Visual analogue scale (VAS) score, Japanese Orthopedic Association score (JOAS), and Oswestry Disability Index (ODI)] before, 12 and 24 months after surgery. RESULTS: Twenty-three patients showed Modic type 1 signals and 22 patients showed normal intensity before surgery. VAS score, JOAS, and ODI were not significantly different between the normal and Modic type 1 groups. VAS score, JOAS, and ODI improved after surgery in both groups (P>0.05). Low back pain after surgery evaluated from the 3 scores was not significantly different in the 2 groups 12 or 24 months after surgery (P>0.05). CONCLUSION: Discectomy improved low back pain in patients suffering from lumbar disc herniation. Patients with or without Modic type 1 change showed a similar improvement of low back pain score. Low back pain in patients with disc herniation appears to mainly originate from disc or nerve root compression, and decompression surgery without fusion is an option for these patients, even those with Modic type 1 changes.

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.

BACKGROUND: Clinically, the origin of low back pain is unknown. The pain may originate from the lumbar muscles directly, or it may be referred pain from the spine. Dorsal root ganglion (DRG) neurons with dichotomizing axons have been reported in several species and are thought to be related to referred pain. However, these neurons, which have dichotomizing axons to the lumbar facet joints and to the lumbar muscle, have not been fully investigated. METHODS: Two neurotracers - 1,1'-dioctadecyl-3,3,3',3'- tetramethyl-indocarbocyanine perchlorate (DiI) and fluorogold (FG) - were used in the present double-labeling study. DiI crystals were placed in the right L5/6 facet joint, and FG was applied to right multifidus muscles at the L5 level in 10 rats. Two weeks later, bilateral DRGs from L1 through L6 were harvested, sectioned, and observed under a fluorescence microscope. RESULTS: DiI-labeled DRG neurons innervating the L5/6 facet joint (5.17% of the total DRG neurons) were distributed from L1 to L6. FG-labeled DRG neurons innervating the lower back muscle (15.9% of the total) were also distributed from L1 to L6. Double-labeled DRG neurons were found from L1 to L6. The ratio of total double-labeled/total DiI-labeled DRG neurons was 17% and that of total double-labeled/total FG-labeled DRG neurons was 7%. Approximately 17% of all DRG neurons innervating the facet joints had other axons that extended to the lower back muscle. CONCLUSIONS: This finding provides a possible neuroanatomical explanation for referred low back muscle pain from the lower facet joints.

BACKGROUND: Recent studies have revealed that the low-affinity nerve growth factor receptor, p75 neurotrophin receptor (p75NTR), is important in inflammatory pain. Moreover, p75NTR immunoreactive sensory nerve and dorsal root ganglion (DRG) neurons have been found to innervate lumbar intervertebral discs. The purpose of the current study was to investigate the effect of p75NTR saporin, a toxin used to destroy p75NTR, on calcitonin gene-related peptide (CGRP), an inflammatory neuropeptide associated with pain, in DRG neurons innervating punctured intervertebral discs in rats. METHODS: The neurotracer fluorogold (FG) was applied to the surfaces of L5/6 discs to label their innervating DRG neurons (n = 30). Of 30 rats, 10 were in a nonpunctured disc sham surgery control group (nonpuncture group), and the other 20 were in experimental groups in which intervertebral discs were punctured with a 23-gauge needle. p75NTR saporin was applied to the discs of 10 rats (puncture + p75NTR saporin group) and the other 10 received the same volume of saline (puncture + saline group). At 14 days after surgery, DRGs from L1 to L6 were harvested, sectioned, and immunostained for CGRP, and the proportions of CGRP-immunoreactive DRG neurons was evaluated. RESULTS: Of the FG-labeled neurons innervating the L5/6 disc, the proportion of CGRP-immunoreactive neurons was 32% +/- 6% (mean +/- SE) in the nonpuncture group, 47.2% +/- 8% in the puncture + saline group, and 34.6% +/- 9% in the puncture + p75NTR saporin group. The proportion of CGRP-immunoreactive neurons was significantly greater in the puncture + saline group compared with the nonpuncture and puncture + p75NTR saporin groups (P < 0.01). CONCLUSIONS: Half of the DRG neurons innervating the discs were positive for CGRP in the puncture + saline group. CGRP is important for mediating inflammatory and nerve-injured pain and may be important in discogenic pain. However, p75NTR saporin suppressed CGRP expression in DRG neurons. Therefore, p75NTR may be an important receptor for mediating discogenic pain via CGRP expression.

Elderly postmenopausal women who have osteoporosis sometimes experience low back pain, however, the relationship between low back pain and osteoporosis in the absence of vertebral fractures remains unclear. We examined the relationship between bone mineral density (BMD), bone resorption and low back pain in elderly female patients who did not have osteoporotic vertebral fractures. The average BMD was 0.675 g/cm(2) when assessed by dual-energy X-ray absorptiometry (DEXA). Patients were excluded from the study if they had vertebral fractures revealed by radiography, CT scans or MRI. Bisphosphonate (risedronate) was administered for 4 months. The visual analogue scale (VAS) pain score, Roland Morris Disability Questionnaire (RDQ), Short Form-36 (SF-36) questionnaire, BMD and N-terminal telopeptide of type I collagen (NTx; a marker for bone resorption) were examined before and after treatment. DEXA did not increase significantly, but serum and urinary NTx were decreased (-51.4% and -62.0%, respectively) after 4 months of risedronate treatment (p<0.01). The assessment was repeated using the VAS score, RDQ and SF-36, which revealed an improvement after risedronate treatment (p<0.01). A decrease in serum and urinary NTx was associated with improvement of low back pain, suggesting that despite the absence of vertebral fractures, bone resorption due to osteoporosis may cause low back pain.

OBJECTIVE: To clarify whether age at the time of the initial administration of corticosteroids is a risk factor for corticosteroid-associated osteonecrosis in children with systemic lupus erythematosus (SLE), using magnetic resonance imaging (MRI). METHODS: From 1986 to 2007, MRI was used to prospectively study 676 joints, including 72 joints (36 hips and 36 knees) in 18 pediatric patients with SLE (<15 years old), 100 joints (50 hips and 50 knees) in 25 adolescent patients with SLE (15-20 years old), and 504 joints (252 hips and 252 knees) in 126 adult patients with SLE (>20 years old), beginning just after corticosteroid administration, for at least 1 year. The followup rate was 100%. RESULTS: In pediatric patients, osteonecrosis developed in 4 joints (6%; all hips). In adolescent patients, osteonecrosis developed in 49 joints (49%; 18 hips and 31 knees). In adult patients, osteonecrosis developed in 207 joints (41%; 95 hips and 112 knees). The rate of osteonecrosis was significantly lower in pediatric patients than in adolescent or adult patients (P = 0.0001). Logistic regression analysis revealed that adolescent and adult patients had a significantly higher risk for osteonecrosis compared with pediatric patients, with an odds ratio of 10.3 (P < 0.0001). The youngest patients with osteonecrosis in the hip and knee were 14.9 years old and 15.5 years old, respectively. Osteonecrosis did not develop in patients younger than age 14 years. CONCLUSION: Our results suggest that age at the time of the initial administration of corticosteroids is associated with osteonecrosis in pediatric patients with SLE.

BACKGROUND: Hinge abduction is widely accepted as a poor prognostic factor in Legg-Calvé-Perthes disease (LCPD), whereas the exact definition of hinge abduction remains ill defined. The purpose of this diagnostic study was to refine the definition of hinge abduction in LCPD using conventional hip arthrography under general anesthesia. METHODS: Among 350 hips in 332 LCPD patients, we reviewed 92 hips in 90 patients (75 boys and 15 girls) who consecutively underwent arthrography under general anesthesia because of an expected poor prognosis. The mean age at LCPD onset was 8.2 years (range, 4-13 years). With respect to lateral pillar classification, 25 hips were classified as group B, 27 as B/C border, and 40 as C. Subluxation (>or=3-mm difference from unaffected side) was present in 81 (88%) of the 92 hips. The modified Waldenström classification was used for evaluating the radiographic stage of disease at the time of arthrography: 80 hips were classified as fragmentation stage and 12 as reossification stage. Hinge abduction was defined as an increased subluxation index in maximum abduction and/or a positive impingement sign. RESULTS: Under this definition, 11% (10 hips) of the study group had hinge abduction. The range of abduction under general anesthesia (40 degrees) was significantly greater than in the awake condition (24 degrees, P < 0.0001). CONCLUSIONS: The subluxation index and the impingement sign proved to be reliable indicators for diagnosing hinge abduction. Conventional arthrography remains useful. General anesthesia provided an analgesic effect and muscle relaxation. LEVEL OF EVIDENCE: Level II (diagnostic study, development of diagnostic criteria on the basis of consecutive patients).

PURPOSE: There is not always a good outcome after a femoral varus osteotomy (FVO) in those with Legg-Calvé-Perthes disease (LCPD), even when the severity warrants surgical treatment. The purpose of this study was to find arthrographic indicators for decision making regarding the likely surgical outcome of a FVO. METHODS: We used an image of an abduction position during preoperative arthrography under general anesthesia that simulated the post-operative relationship between the femoral head and the acetabulum. In the image, we defined two indicators of how deeply the deformed epiphysis was contained within the acetabulum: an acetabular head index in abduction and an epiphyseal slip-in index. Finding the contact point between the top of epiphysis and acetabulum was the key for the epiphyseal slip-in index measurement. In 37 patients (38 hips) who underwent FVOs based on our inclusion criteria, these two indices were measured retrospectively and were analyzed for a correlation with surgical outcome. Surgical outcome was evaluated using a combination of three factors: sphericity of the femoral head (Stulberg's classification), acetabular cover (acetabular head index), and the slope of acetabular roof. RESULTS: The outcome was acceptable in 20 hips (52.6%) and unacceptable in18 hips (47.4%). There was a statistically significance difference in epiphyseal slip-in index between the acceptable group (21.9 +/- 2.8%) and the unacceptable group (15.0 +/- 4.4%) (P < 0.0001). An index of 20% or more determined a safe zone for predicting an acceptable outcome with 80% sensitivity, 89% specificity, and a 7.2 likelihood ratio. However, the acetabular head index in abduction showed no such statistical significance. CONCLUSIONS: In this study, we found that the epiphyseal slip-in index was a reliable indicator for predicting the effectiveness of a FVO. It is worth measuring this index when a surgeon is considering a FVO for a patient with severe LCPD. (Level of Evidence Level III.).