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OBJECTIVEThe aim of this retrospective study was to analyze the influence of upper instrumented vertebra (UIV) translation from the C7 plumb line (C7PL) on the long-term postoperative results of patients with main thoracic (MT) adolescent idiopathic scoliosis (AIS).METHODSTwenty-five patients had been treated surgically for AIS with a Lenke type 1 curve and had been followed up for a mean period of 18.2 years. Radiographic parameters, pulmonary function measurements, and clinical outcomes were compared between the patients (n = 15) with UIV translation < 20 mm and those (n = 10) with UIV translation ≥ 20 mm at the final follow-up. Correlations between UIV translation and radiographic or pulmonary function parameters were analyzed.RESULTSPatients with ≥ 20 mm UIV translation at the final follow-up had a significantly larger preoperative UIV translation than that in the patients with < 20 mm UIV translation at follow-up. The former group also had a significantly lower correction rate of the MT curve, higher chest cage ratio, and lower radiographic shoulder height (p = 0.01, 0.005, and 0.025, respectively) at the final follow-up. The Scoliosis Research Society (SRS)–30 Questionnaire scores were equivalent between the two groups. Correlation analysis showed that the following parameters were significantly associated with UIV translation: MT curve correction rate (r = -0.481, p = 0.015), chest cage ratio (r = 0.673, p < 0.001), and percent-predicted forced expiratory volume in 1 second (r = -0.455, p = 0.033).CONCLUSIONSThe UIV translation should be considered an important factor that influences postoperative results. In MT AIS patients whose preoperative upper end vertebra (UEV) is distant from the C7PL, the UIV should be selected above the UEV to prevent large UIV translation at the postoperative follow-up.

BackgroundContext Consensus regarding the optimal upper vertebra to be instrumented during surgical treatment of Lenke 5C thoracolumbar and lumbar adolescent idiopathic scoliosis (AIS) remains limited. Purpose This study aimed to assess whether a short fusion strategy is appropriate for correction of a Lenke 5C AIS curve by anterior correction and fusion surgery using dual-rod instrumentation. Study Design This study design used retrospective comparative analysis of a prospectively collected, consecutive, non-randomized series of patients at a single institution. Patient Sample Thirty consecutive patients with Lenke 5C AIS treated with anterior correction and fusion surgery using dual-rod instrumentation were included. Outcome Measures Patient demographics, radiographic measurements, and Scoliosis Research Society-22 questionnaire (SRS-22) scores were the outcome measures for this study. Methods Thirty patients were treated surgically for AIS with a Lenke 5C curve (mean age, 14.4 years [11–19 years)]) and followed up for a mean period of 17.2 years (12–23 years). Radiographical parameters and clinical outcomes were compared between patients treatment with the end vertebra (EV) instrumented (n=14) and those treated by short fusion (S group) with instrumentation starting at the vertebra one level caudal to the EV (n=16 patients). There were no study-specific biases related to conflicts of interest. Results In the EV group, a mean preoperative Cobb angle of 56° was corrected to 5° after surgery and to 8° at the final follow-up. In the S group, a mean preoperative Cobb angle of 55° was corrected to 10° after surgery and 14° at the final follow-up. The mean correction rate at the final follow-up was significantly lower in the S group (74%) than in the EV group (86%; p=.020). The coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, and clinical outcomes evaluated using SRS-22 did not differ between the two groups. Conclusions The short fusion strategy, which involves instrumentation of the vertebra one level caudal to the upper EV, can be considered as an alternative to the conventional strategy, which includes instrumentation of the upper EV, for treating Lenke 5C curves via anterior spinal fusion.

Background context With the increase of the elderly population, osteoporotic vertebral fractures have been frequently reported. Surgical intervention is usually recommended in osteoporotic vertebral collapse with neurologic deficits. However, very few reports on surgical interventions exist. Purpose To compare surgical results of anterior and posterior procedures for treating osteoporotic thoracolumbar vertebral collapse with sustained neurologic deficits. Study design Retrospective comparative study. Patient sample Fifty patients who sustained osteoporotic thoracolumbar vertebral collapse with neurologic deficits were treated either by anterior decompression and strut graft (n=32) or by posterior decompression and pedicle screw fixation with vertebroplasty (n=18). Outcome measures Incidence of complications, sagittal Cobb angle, spinal canal encroachment, and Japanese Orthopedic Association score. Methods The authors retrospectively reviewed the results of a consecutive series of patients undergoing anterior decompression and strut graft or posterior decompression and pedicle screw fixation with vertebroplasty for osteoporotic thoracolumbar vertebral collapse with neurologic deficits. Operative notes, clinical charts, and radiographs were analyzed. Results Operative time was similar between the groups, but intraoperative blood loss was significantly lower in the posterior group. All patients showed neurologic recovery. No significant difference was observed in the neurologic improvement, kyphosis correction angle, and loss of correction. Perioperative respiratory complications were found in 11 patients (34%) in the anterior group. In the anterior group, early posterior reinforcement was required in patients with very low bone density below 0.60 g/cm 2 and/or in those with three segments of instrumentation for two vertebral collapses. Posterior group patients did not undergo additional surgery. Conclusions Anterior reconstruction for osteoporotic vertebral collapse is significant because anterior elements, particularly those at the thoracolumbar junction, play a major role in load bearing. However, difficulties arise when anterior reconstruction is performed in cases with very low bone density and in those with multiple vertebral collapse.

Study design Retrospective review. Objective To assess the long-term outcomes of anterior spinal fusion (ASF) for treating thoracic adolescent idiopathic scoliosis (AIS). Summary of background data Although ASF is reported to provide good coronal and sagittal correction of the main thoracic (MT) AIS curves, the long-term outcomes of ASF is unknown. Methods A consecutive series of 25 patients with Lenke 1 MT AIS were included. Outcome measures comprised radiographical measurements, pulmonary function, and Scoliosis Research Society outcome instrument (SRS-30) scores (preoperative SRS-30 scores were not documented). Postoperative surgical revisions and complications were recorded. Results Twenty-five patients were followed-up for 12 to 18 years (average, 15.2 yr). The average MT Cobb angle correction rate and the correction loss at the final follow-up were 56.7% and 9.2°, respectively. The average preoperative instrumented level of kyphosis was 8.3°, which significantly improved to 18.6° (P = 0.0003) at the final follow-up. The average percent-predicted forced vital capacity and forced expiratory volume in 1 second were significantly decreased during long-term follow-up measurements (73% and 69%; P = 0.0004 and 0.0016, respectively). However, no patient had complaints related to pulmonary function. The average total SRS-30 score was 4.0. Implant breakage was not observed. All patients, except 1 who required revision surgery, demonstrated solid fusion. Late instrumentation-related bronchial problems were observed in 1 patient who required implant removal and bronchial tube repair, 13 years after the initial surgery. Conclusion Overall radiographical findings and patient outcome measures of ASF for Lenke 1 MT AIS were satisfactory at an average follow-up of 15 years. ASF provides significant sagittal correction of the main thoracic curve with long-term maintenance of sagittal profiles. Percent-predicted values of forced vital capacity and forced expiratory volume in 1 second were decreased in this cohort; however, no patient had complaints related to pulmonary function.

Aims A total of 30 patients with thoracolumbar/lumbar adolescent idiopathic scoliosis (AIS) treated between 1989 and 2000 with anterior correction and fusion surgery using dual-rod instrumentation were reviewed. Patients and Methods Radiographic parameters and clinical outcomes were compared among patients with lowest instrumented vertebra (LIV) at the lower end vertebra (LEV; EV group) (n = 13) and those treated by short fusion (S group), with LIV one level proximal to EV (n = 17 patients). Results The allocation of the surgical technique was determined by the flexibility of the TL/L curves and/or neutral vertebrae located one level above LEV as determined on preoperative radiographs. If these requirements were met a short fusion was performed. The mean follow-up period was 21.4 years (16 to 27). The mean correction rate at final follow-up was significantly lower in the S group (74 sd 11%) than in the EV group (88 sd 13%) (p = 0.004).Coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, and clinical outcomes evaluated by the Scoliosis Research Society-22 questionnaire scores were equivalent between the two groups. Conclusion Short fusion strategy, which uses LIV one level proximal to LEV can be considered as an alternative to the conventional strategy, which includes LEV in the fusion, when highly flexible TL/L curves are confirmed and/or neutral vertebrae are located one level above LEV in patients with thoracolumbar/lumbar AIS curves. Take home message: Short fusion strategy can be considered as an alternative to the conventional strategy in patients with thoracolumbar/lumbar AIS curves undergoing anterior spinal fusion with dual-rod instrumentation. Cite this article: Bone Joint J 2016;98-B:402–9.

Study design A retrospective study. Objectives To investigate the clinical and radiographic results of spinal reconstruction using Kaneda anterior spinal instrumentation for osteoporotic vertebral collapse. Summary of background data Recent advances in osteoporotic vertebral fracture treatment including kyphoplasty changes the role of major surgery for these pathologies. However, osteoporotic vertebral collapse with neurologic compromise remains requiring surgical decompression and reconstruction. Methods Thirty-one consecutive patients who underwent anterior spinal reconstruction for osteoporotic vertebral collapse with neurologic deficits were reviewed retrospectively. Twenty-six patients had single vertebral collapse and 5 had multiple lesions. They were 10 males and 21 females with mean age of 71 years. Mean follow-up period was 57 months. For anterior column support, iliac bone graft was used in 1 patient, cylindrical titanium cages in 12, and bioactive ceramic spacers in 18 patients. Kaneda anterior instrumentation was used in all the patients. Radiographic and clinical assessments were performed preoperatively and at the final follow-up. Results All the patients showed neurologic recovery. Visual analog scales (0 to 10) of low back pain and sciatic pain were 5.8 and 4.2 before surgery, and 2.1 and 0.6 at the final follow-up, respectively. Mean kyphosis of operative levels was 31 degrees before surgery, and improved to 13 degrees immediately after surgery and 21 degrees at the final follow-up. Posterior reinforcement was required in 6 patients (19%), who had severe osteoporosis and/or underwent multilevel corpectomies. Solid fusion was achieved in all patients at the final follow-up. Conclusions The current study demonstrated the advantages of anterior spinal reconstruction in osteoporotic vertebral collapse: (1) safe and reliable decompression could be performed, and (2) 80% of patients were successfully treated with anterior spinal reconstruction alone. However, patients with multilevel corpectomies and/or severe osteoporosis highly required posterior reinforcement.

Aims The aims of our study were to provide long-term information on the behaviour of the thoracolumbar/lumbar (TL/L) curve after thoracic anterior correction and fusion (ASF) and to determine the impact of ASF on pulmonary function. Patients and Methods A total of 41 patients (four males, 37 females) with main thoracic (MT) adolescent idiopathic scoliosis (AIS) treated with ASF were included. Mean age at surgery was 15.2 years (11 to 27). Mean follow-up period was 13.5 years (10 to 18). Results For the TL/L curve, the mean curve flexibility evaluated with supine pre-operative bending radiographs was 78.6% (standard deviation 16.5%), with no significant loss of correction observed. On comparing patients with an increase of the TL/L curve increase (> 4º, n = 9, 22%) to those without, significant differences were observed in the correction rate of the MT curve at the final follow-up (p = 0.011), correction loss of the MT curve (p = 0.003) and the proportion of patients who had semi-rigid instrumentation (p = 0.003). Pre-operative percentage predicted forced vital capacity (%FVC) was 80%, dropping to 72% at final follow-up (p < 0.001). The Scoliosis Research Society questionnaire score was not significantly different between patients with and without a TL/L curve increase (p = 0.606). Spontaneous lumbar curve correction (SLCC) was maintained up to 18 years following selective ASF in most patients and demonstrated significant correlation with maintenance of MT curve correction. Conclusion Maintenance of MT curve correction using rigid instrumentation provided stable SLCC over time. An observed 8% decrease in %FVC indicates that ASF should be reserved for patients with no or only mild pulmonary impairment. Cite this article: Bone Joint J 2016;98-B:997–1002.

OBJECTIVE Several studies have reported favorable results of posterolateral fusion (PLF) with pedicle screw systems (PSs) for isthmic spondylolisthesis. However, the best indication and limitations of this method still remain unclear. The present study aimed to analyze the radiological risk factors of pseudoarthrosis and/or instrumentation failure after PLF with PSs in isthmic spondylolisthesis, and to determine the limitations of this method. METHODS The study group comprised of 101 patients with isthmic spondylolisthesis who underwent PLF with PSs. Follow-up was performed for more than 5 years. Statistical analyses with multivariate logistic regression models were used to identify risk factors of pseudoarthrosis and/or instrument failures associated with PLF with PSs. RESULTS Average follow-up was 8 years. Fusion rate was 95%. There were instrument breakage in 6 patients, and pseudoarthrosis in 5. Statistical analysis with a logistic regression model revealed that preoperative % disc height (odds ratio: 3.60 per 10%, P

Study design Retrospective comparative study of the postoperative subsidence of two interbody devices following posterior or transforaminal lumbar interbody fusion (PLIF/TLIF) for degenerative spondylolisthesis of the lumbar spine. Objective To assess certain radiograph characteristics of PLIF/TLIF using two interbody fusion devices at L4-L5. Summary of background data PLIF can achieve spinal stabilization with vertebral body support and direct neural decompression. Although various interbody devices have been used in PLIF procedures, no radiographic studies have compared the load-bearing capabilities of open box and fenestrated tube interbody cages. Methods Seventy-five patients who underwent one-level PLIF in the L4-L5 [corrected] segment for degenerative spondylolisthesis were retrospectively reviewed with a minimum 2-year follow-up. Fenestrated tube (Group FT: n = 30 [corrected]) or open box (Group OB: n = 45 [corrected]) cages were used for the PLIF procedure. The following radiographic parameters were evaluated to compare the load-bearing capabilities: disc space height (DH); percent increase and decrease of disc height (% IDH and % DDH, respectively); and percent coverage of the cage on the endplate (% CC). Results There were no significant differences in the baseline data, including age, segmental instability and osteoporotic status, between the two groups. Anterior %IDH and % CC were significantly higher in Group OB than in Group FT (% IDH: 69.4% vs. 57.3%; % OC: 24.5% vs. 12.9%), and anterior and posterior % DDH were significantly higher in Group FT than in Group OB (anterior: -2.9% vs. -.1%; posterior: -6.6% vs. -.3%). Although the restored DH gradually reduced over time in both groups, significant reduction to the preoperative level only occurred in Group FT. Conclusions The load-bearing capabilities of the open box cage are superior to those of the fenestrated tube cage. Since there were no significant differences between the baseline status of the two groups, the larger cross-sectional area and stable framework design of the open box cage appears to bring about a greater load-bearing capability. Therefore, the open box cage seems to be biomechanically more advantageous as an interbody device for PLIF than the fenestrated tube cage.

Object There are no published reports of unilateral transforaminal lumbar interbody fusion (TLIF) in which two Brantigan I/F cages were placed per level through a single portal to achieve bilateral anterior-column support. The authors describe such a surgical technique and evaluate the clinical outcomes of this procedure. Methods Data obtained in 86 (93.5%) of the first 92 consecutive patients who underwent the procedure were retrospectively reviewed; the minimum follow-up duration was 2 years. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scoring system. Disc height, disc angle, cage positioning in the axial plane, and fusion status were radiographically evaluated. The mean follow-up period was 33.8 months. The mean improvement in the JOA score was 77.2%. Fusion was successful in 93% of the cases. According to the Farfan method, the mean anterior and posterior disc heights increased from 20.2 and 16.9% preoperatively to 35.9 and 22.7% at follow up, respectively (p < 0.01). The mean disc angle increased from 4.8° preoperatively to 7.5° at last follow-up examination (p < 0.01). Two cages were correctly placed to achieve bilateral anterior-column support in greater than 85% of the cases. The following complications occurred: hardware migration in two patients and deep infection cured by intravenous antibiotic therapy in one patient. Conclusions Unilateral TLIF involving the placement of two Brantigan cages per level led to good clinical results. Two Brantigan cages were adequately placed via a single portal, and reliable bilateral anterior-column support was achieved. Although the less invasive unilateral approach was used, the outcomes were as good as those in many reported series of posterior lumbar interbody fusion in which the Brantigan cages were placed via the bilateral approach.

Patients with serious spinal disc disorders will benefit from a novel artificial disc system that is suitable for clinical use in replacement arthroplasty. The disc is composed of a biomimetic three-dimensional (3D) fabric with a triaxial fiber alignment that has superior mechanical properties when compared to conventional implants. This disc improves on the constitutional imperfections of biological intervertebral discs by eliminating the risk of rupture and delamination. The fabric bonds firmly to disc bodies, and functions in combination with bioactive bioresorbable pins and scaffolds as a stand-alone system that maintains the position of the disc and promotes bone growth at the interface. The disc has high biocompatibility and can maintain biomimetic “J-shaped” stress–strain behavior for up to sixty-three million alternating stresses, which is the equivalent of natural biological movements for a period of more than 30 years. This technology exemplifies how, in the best biomaterials, biological flexibility may occasionally overcome artificial rigidity.

The risk-reducing effect of alendronate on vertebral fractures has been consistently reported. In a 2-year, randomized, double-blind, active drug-controlled (1 microg alfacalcidol) double-dummy study, we also reported that alendronate (5.0 mg) had a fracture-reducing effect in Japanese patients with preexisting vertebral fractures. The present report describes the risk-reducing effect of alendronate (5.0 mg) for 3 years in postmenopausal osteoporotic patients. The 3-year treatment period consisted of the original 2-year double-blind study followed by a 1-year extension. A total of 170 postmenopausal female patients were involved in the third year; 90 received alendronate and 80 received alfacalcidol. Both efficacy and safety were analyzed in these 170 patients. Vertebral fracture was determined by quantitative morphometry, and vertebral bone mineral density (BMD) was measured by the DXA method (dual-energy X-ray absorptiometry). The primary efficacy endpoint was the incidence of vertebral fracture, excluding fracture cases that occurred in the first 6 months after treatment initiation. The cumulative incidence of vertebral fracture at 3 years was 7.8% (7/90) in the alendronate group and 18.8% (15/80) in the alfacalcidol group, indicating a significantly reduced risk of fractures in the alendronate group (relative risk = 0.41, 95% CI = 0.18-0.97). Lumbar spine BMD increased by 9.2% in the alendronate group (n = 26) and by 1.4% in the alfacalcidol group (n = 22) at 3 years. The safety profile of alendronate during 3 years of treatment was similar to that of alfacalcidol. The present study thus demonstrated that treatment with alendronate 5.0 mg for 3 years increased vertebral BMD and reduced the risk of vertebral fractures in Japanese, postmenopausal women with osteoporosis.

This study aimed to investigate the long-term clinical results of the apatite wollastonite-containing glass ceramic (AWGC) iliac spacer and to discuss its efficacy in reconstruction of the bone graft donor site at the iliac crest. Thirty-one patients were studied for more than 10 years. All patients underwent anterior spinal fusion using autogenous tricortical iliac bone graft. After harvest of tricortical iliac bone graft, an AWGC iliac spacer ranging from 15 mm to 70 mm in length was press-fitted into the gap. Long-term clinical results were obtained from radiological and blood examinations. Thirty patients (97%) were satisfied with the spacer. There was new bone formation around the spacer on the radiograph. There was no abnormal silicon concentration in blood examinations. AWGC iliac spacer appears to be useful in the reconstruction of harvested iliac crest. New bone formation occurs, reducing the defect size.

Object. This 2-year experimental study was conducted to investigate the efficacy of a bioactive three-dimensional (3D) fabric disc for lumbar intervertebral disc replacement. The authors used a bioresorbable spinal fixation rod consisting of a forged composite of particulate unsintered hydroxyapatite/poly-l-lactide acid (HA/PLLA) for stability augmentation. The biomechanical and histological alterations as well as possible device-related loosening were examined at 2 years postoperatively. Methods. Two lumbar intervertebral discs (L2–3 and L4–5) were replaced with the 3D fabric discs, which were augmented by two titanium screws and a spanning bioresorbable rod (HA/PLLA). The segmental biomechanics and interface bone ingrowth were investigated at 6, 15, and 24 months postoperatively, and results were compared with the other two surgical groups (3D fabric disc alone; 3D fabric disc with additional anterior instrumentation stabilization). The 3D fabric disc and HA/PLLA—spinal segments demonstrated segmental mobility at 15 and 24 months; however, the range of motion (ROM) in flexion—extension decreased to 49 and 40%, respectively, despite statistically equivalent preserved torsional ROM. Histologically there was excellent osseous fusion at the 3D fabric disc surface—vertebral body interface. At 2 years posttreatment, no adverse tissue reaction nor aseptic loosening of the device was observed. Conclusions. Intervertebral disc replacement with the 3D fabric disc was viable and when used in conjunction with the bioresorbable HA/PLLA spinal augmentation. Further refinements of device design to create a stand-alone type are necessary to obviate the need for additional spinal stabilization.

Object The posterior ligamentous complex (PLC) in the thoracic and lumbar spine is one of the region's important stabilizers. The precise diagnosis of PLC injury is required to evaluate the instability of the injured spine; however, the accuracy of magnetic resonance (MR) imaging for diagnosing PLC injury has remained unclear. In this study, the authors compared preoperative MR imaging findings with direct intraoperative observation of PLC injury, clarifying the former's diagnostic accuracy regarding detection of PLC injury associated with the thoracic and lumbar fractures. Methods Data obtained in 35 patients who sustained thoracic or lumbar injuries were reviewed. There were 17 burst fractures, six flexion—distraction injuries, and 12 fracture dislocations. Each patient underwent MR imaging examination within 3 weeks of injury. Three radiologists independently evaluated sagittal MR images in a blinded fashion. The PLC-related information was retrospectively collected from each operative record. The diagnostic accuracy of MR imaging was analyzed by comparing imaging-documented intraoperative findings. The PLC injuries were detected in 23 patients (65.7%) by direct observation during posterior spinal procedures. The diagnostic accuracy of MR imaging in detecting injury of the supraspinous ligament (SSL) and interspinous ligament (ISL) was 90.5 and 94.3%, respectively. The specificity of T1-weighted MR imaging alone for depicting the SSL was significantly greater than T2-weighted imaging alone (p < 0.05). The overall mean κ coefficient for MR imaging findings of PLC injury was 0.803, which indicated excellent interobserver reliability; that for ISL (0.915) was significantly greater than that for SSL (0.69) (p < 0.05). Conclusions This study clarified a high diagnostic accuracy and interobserver reliability of MR imaging for PLC injury. The precise diagnosis of PLC injury is essential to determine the mechanical instability of the injured thoracic and lumbar spine, especially in differentiating unstable (three-column) burst fractures from the relatively stable (two-column) type. The authors conclude that MR imaging is a powerful diagnostic tool to evaluate PLC injury associated with thoracic and lumbar fractures.

STUDY DESIGN A new artificial intervertebral disc was developed, and its intrinsic biomechanical properties, bioactivity, and the effectiveness as a total disc replacement were evaluated in vitro and in vivo. OBJECTIVES To introduce a new artificial intervertebral disc and to evaluate the in vitro mechanical properties, fusion capacity to bone, and segmental biomechanics in the total intervertebral disc replacement using a sheep lumbar spine. SUMMARY OF BACKGROUND DATA The loss of biologic fusion at the bone-implant interface and prosthetic failures have been reported in previous artificial discs. There have been no clinically applicable discs with detailed experimental testing of in vivo mechanics and interface fusion capacity. METHODS The artificial intervertebral disc consists of a triaxial three-dimensional fabric (3-DF) woven with an ultra-high molecular weight polyethylene fiber, and spray-coated bioactive ceramics on the disc surface. The arrangement of weave properties was designed to produce mechanical behavior nearly equivalent to the natural intervertebral disc. Total intervertebral disc replacement at L2-L3 and L4-L5 was performed using 3-DF disc with or without internal fixation in a sheep lumbar spine model. The segmental biomechanics and interface histology were evaluated after surgery at 4 and 6 months. RESULTS The tensile-compressive and torsional properties of prototype 3-DF were nearly equivalent to those of human lumbar disc. The lumbar segments replaced with 3-DF disc alone showed a significant decrease of flexion-extension range of motion to 28% of control values as well as partial bony fusion at 6 months. However, the use of temporary fixation provided a nearly physiologic mobility of the spinal segment after implant removal as well as excellent bone-disc fusion at 6 months. CONCLUSION An artificial intervertebral disc using a three-dimensional fabric demonstrated excellent in vitro and in vivo performance in both biomechanics and interface histology. There is a potential for future clinical application.

Background context: The effects of aging and spinal degeneration on the mechanical properties of spinal ligaments are still unknown, although there have been several studies demonstrating those of normal spinal ligaments. Purpose: To investigate the mechanical properties of the human posterior spinal ligaments in human lumbar spine, and their relation to age and spinal degeneration parameters. Study design/setting: Destructive uniaxial tensile tests were performed on the human supraspinous and interspinous ligaments at L4–5 level. Their mechanical properties were compared with age and spinal degeneration using several imaging modalities. Patient sample: Twenty-four patients with lumbar degenerative diseases on whom posterior surgeries were performed, with the age ranging from 18 to 85 years. Outcome measures: The ultimate load and elastic stiffness as structural properties, the degree of disc degeneration, range of segmental motion, the disc height, disc space narrowing ratio and degree of facet degeneration as the parameters of spinal degeneration. Methods: Twenty-four supraspinous and interspinous ligaments at the L4–5 level were obtained from posterior surgeries of patients with lumbar degenerative disease. The mechanical tests of bone-ligament-bone complexes were performed in a uniaxial tensile fashion with a specially designed clamp device. The ultimate load and elastic stiffness were calculated as structural properties. The degree of disc degeneration, range of segmental motion, the disc height, disc space narrowing ratio and degree of facet degeneration were examined by using radiographs, computed tomography and magnetic resonance imaging. Results: The average and SD value of ultimate load, elastic stiffness, tensile strength and elastic modulus were 203±102.9 N, 60.6±36.7 N/mm, 1.2±0.6 Mpa and 3.3±2.1 Mpa, respectively. A significant negative correlation was found between age and tensile strength (p= 0.02). The specimens with facet degeneration showed lower values in tensile strength and elastic modulus than those without facet degeneration (p Conclusions: The mechanical strength of human lumbar posterior spinal ligaments decreases with age and facet degeneration, particularly in the ligament substance.

Study design An in vitro human cadaveric study comparing the effects of anterior and posterior sequential destabilization conditions on thoracic functional unit mechanics was studied. Objectives To investigate the biomechanical properties of the human thoracic spine. Summary of background data Few studies have addressed the mechanical role of the costovertebral joints under torsion in the stability of the human thoracic spine. Methods Sixteen functional spinal units with intact costovertebral joints were obtained from six human cadavers and randomized into two groups based on destabilization procedures: Group 1, anterior to posterior sequential resection; and Group 2, posterior to anterior sequential destabilization. Biomechanical testing was performed after each destabilization procedure, and the range of motion under maximum load was calculated. Results Group 1: Under flexion-extension, lateral bending, and axial rotation loading, discectomy increased the range of motion by 193%, 74%, and 111%, respectively. Moreover, subsequent right rib head resection further increased the range of motion by 81%, 84%, and 72%, respectively. Group 2: Under all loading conditions laminectomy + medial facetectomy resulted in a 22-30% increase in range of motion. Subsequent total facetectomy led to an additional 15-28% increase in range of motion. Conclusion The rib head joints serve as stabilizing structures to the human thoracic spine in the sagittal, coronal, and transverse planes. In anterior scoliosis surgery additional rib head resection after discectomy may achieve greater curve and rib hump correction. The lateral portion of the facet joints plays an important role in providing spinal stability and should be preserved to minimize postoperative kyphotic deformity and segmental instability when performing decompressive wide laminectomy.

STUDY DESIGN A retrospective study of 12 patients with congenital kyphoscoliosis caused by a single hemivertebra who underwent one-stage posterior hemivertebra resection and correction by posterior segmental instrumentation. OBJECTIVES To evaluate the surgical outcomes of 12 patients with hemivertebra treated by hemivertebra resection by single posterior approach and correction with segmental posterior instrumentation. SUMMARY OF BACKGROUND DATA Congenital scoliosis caused by hemivertebra causes extremely severe curves in some patients. Posterior fusion or posterior and anterior hemi-epiphysiodesis is performed to prevent progression of the deformity. The results of these procedures have been variable and not promising, especially in an adolescent patient with fixed kyphoscoliotic deformity. Hemivertebra resection offers more certain results and better correction of the deformity. To date, hemivertebra resection is performed by anterior and posterior approaches either by one-stage or two-stage operation. Few reports have been published describing a procedure consisting of one-stage posterior hemivertebra resection and correction of the deformity by segmental posterior instrumentation. METHODS A total of 12 patients with a single hemivertebra between the ages 8-24 years who underwent operative treatment were evaluated for a minimum of 2 years. All patients had a single nonincarcerated hemivertebra [T9 (1 patient), T10 (2), T11 (2), T12 (4), and L1 (3)]. After posterior hemivertebra resection, segmental posterior instrumentation was used for correction of the kyphoscoliotic deformity [CD (4 patients), Kaneda SR (2), and ISOLA (6)]. Radiographic evaluations were conducted on the preoperative, postoperative, and follow-up standing posteroanterior and lateral radiographs. RESULTS All 12 patients had kyphoscoliotic deformity. Preoperative scoliosis averaging 49 degrees was corrected to 18 degrees (correction rate, 64%). Preoperative kyphosis of 40 degrees was corrected to 17 degrees of kyphosis. Trunk shift of 23 mm was improved to 3 mm. Correction loss was 2 degrees in the frontal plane and 3 degrees in the sagittal plane, and no patients showed more than 5 degrees of correction loss. No intraoperative complications were noted. Solid fusion was obtained in all patients, and no implant failure was verified at the final radiographic evaluations. CONCLUSIONS This study indicated that correction of kyphoscoliosis caused by a single hemivertebra can be effectively conducted by one-stage posterior hemivertebra resection and correction using segmental posterior instrumentation. The operation was safe, and no associated adverse complications were noted. This procedure is best indicated for adolescent patients with a structural kyphoscoliotic deformity caused by a thoracic or thoracolumbar single hemivertebra.

Forty-eight knees in 44 patients who had a high tibial osteotomy performed for medial compartment osteoarthritis were reevaluated twice, once at 1 year after surgery and again at 10 to 15 years after the high tibial osteotomy, to determine the effects of high tibial osteotomy on progression of medial and lateral joint arthrosis. Radiologically, although arthrosis significantly increased in the medial and the lateral joint compartment, there was no significant difference in the degree of progression between the two compartments. There was a significant correlation between the progression of medial joint arthrosis evaluated at 10 years or more after surgery and the femorotibial angle measured at 1 year. There was no significant correlation between the progression of lateral joint arthrosis in 10 to 15 years and the femorotibial angle measured at 1 year. The average knee function score improved significantly from 59.1 +/- 5.5 points before surgery to 85.1 +/- 6.1 points at the 1-year followup. At the final followup, the clinical score (80.7 +/- 5.4) had deteriorated relative to the 1-year results but still was significantly better than the preoperative score. The current results indicate that the greater the surgical valgus correction, the slower the progression of medial joint arthrosis. Lateral joint arthrosis did not progress more quickly after high tibial osteotomy, even if an overcorrection was performed.

Object. Interbody fusion devices are rapidly gaining acceptance as a method of ensuring lumbar interbody arthrodesis. Although different types of devices have been developed, the comparative reconstruction stability remains controversial. It also remains unclear how different stress-shielded environments are created within the devices. Using a calf spine model, this study was designed to compare the construct stiffness afforded by 11 differently designed lumbar interbody fusion devices and to quantify their stress-shielding effects by measuring pressure within the devices. Methods. Sixty-six lumbar specimens obtained from calves were subjected to anterior interbody reconstruction at L4–5 by using one of the following interbody fusion devices: four different threaded fusion cages (BAK device, BAK Proximity, Ray TFC, and Danek TIBFD), five different nonthreaded fusion devices (oval and circular Harms cages, Brantigan PLIF and ALIF cages, and InFix device); two different types of allograft (femoral ring and bone dowel) were used. Construct stiffness was evaluated in axial compression, torsion, flexion, and lateral bending. Prior to testing, a silicon elastomer was injected into the cages and intracage pressures were measured using pressure needle transducers. Conclusions. No statistical differences were observed in construct stiffness among the threaded cages and nonthreaded devices in most of the testing modalities. Threaded fusion cages demonstrated significantly lower intracage pressures compared with nonthreaded cages and structural allografts. Compared with nonthreaded cages and structural allografts, threaded fusion cages afforded equivalent reconstruction stiffness but provided more stress-shielded environment within the devices.

STUDY DESIGN Three types of anterior thoracolumbar multisegmental fixation were biomechanically compared in construct stiffness and rod-screw strain. OBJECTIVES To investigate the effects of rod diameter and rod number on construct stiffness and rod-screw strain in anterior thoracolumbar multisegmental instrumentation. SUMMARY OF BACKGROUND DATA No studies have been undertaken to investigate the biomechanical effects of rod diameter and rod number in thoracolumbar anterior instrumentation. METHODS Ten fresh-frozen calf spines (T13-L5) were used. After intact analysis, a total discectomy and transection of the ALL and PLL were performed at L1-L2, L2-L3, and L3-L4 with intervertebral reconstruction using carbon fiber cages. Three types of anterior fixation were then performed at L1-L4: 1) 4.75-mm diameter single-rod, 2) 4.75-mm dual-rod, and 3) 6.35-mm single-rod systems. Single screws at each vertebra were used for single-rod and two screws for dual-rod fixation. These systems share the same basic design except rod diameter. Nondestructive biomechanical testing was performed and included compression, torsion, flexion-extension, and lateral bending. Construct stiffness and rod-screw strain of the three reconstructions were compared. RESULTS The 6.35-mm single-rod fixation significantly improved construct stiffness compared with the 4.75-mm single rod fixation only under torsion (P < 0.05). The 4. 75-mm dual rod construct resulted in significantly higher stiffness than did both single-rod fixations (P < 0.05), except under compression. No statistical differences were observed in rod-screw strain between the two types of single rods, whereas dual-rod reconstruction exhibited less rod-screw strain (P < 0.05). CONCLUSIONS For single-rod fixation, increased rod diameter neither markedly improved construct stiffness nor affected rod-screw strain, indicating the limitations of a single-rod system. In thoracolumbar anterior multisegmental instrumentation, the dual-rod fixation provides higher construct stiffness and less rod-screw strain compared with single-rod fixation.

Study Design. This retrospective study was designed to analyze the results of the treatment with S1 pedicle screws and the Galveston technique of seven patients with sacroiliac dislocation. Objectives. To evaluate the effectiveness of the combined use of S1 pedicle screws and the Galveston technique for the treatment of sacroiliac dislocation. Summary of Background Data. Although several procedures for internal fixation of sacroiliac dislocation have been reported, there have been no reports discussing surgical treatment of sacroiliac dislocation by the combined use of S1 pedicle screws and the Galveston technique. Methods. Seven patients with sacroiliac dislocation were treated with pedicle screws of S1 and iliac rod according to the Galveston technique. In the seven patients, the dislocation was associated with vertical displacement of the sacroiliac joint and rotational deformity of the pelvic ring. They were classified into Type-C pelvic disruption according to the Tile’s classification. Three patients with disruption of the symphysis pubis underwent additional fixation of the symphysis using a dynamic compression plate. The remaining four patients were treated by the posterior procedure alone. Results. The vertical displacement was completely reduced in five patients, and the rotational deformity was completely corrected in four patients. The reduction was maintained at the time of the final follow-up evaluation. There were no perioperative complications with the exception of late infection in one patient. Conclusions. The combined use of S1 pedicle screws and the Galveston technique provided immediate stability and sufficient reduction for sacroiliac dislocation in seven patients in this study. This hybrid internal fixation procedure is useful for reduction and fixation of sacroiliac dislocation associated with the vertical and rotational instability of the pelvic ring.

Study design Motion characteristics of the lumbar spine in the sagittal plane were investigated in vivo using cineradiography. Objectives To evaluate the differences in motion characteristics of the normal lumbar spine between forward and backward flexion. Summary of background data Despite previous lumbar kinematic studies, differences in motion characteristics of the lumbar spine between forward and backward flexion remain unclear. Methods Cineradiographic motion analysis was performed in 10 asymptomatic healthy male volunteers for two different lumbar motions. The motions consisted of active forward flexion (from maximum extension to maximum flexion) and active backward flexion (from maximum flexion to maximum extension). Displacements of the anterior and posterior vertebral corners from L3/L4 to L5/S1 were measured continuously in reference to the local coordinate system. Parameters investigated were onset of segmental motion, velocity of segmental motion, and continuous motion profiles of the vertebral corners during the two different motions. Results During forward flexion, initial lumbar motion started stepwise from the upper level (L3/L4) to the lower levels with phase lags. Angular velocity at the onset of motion increased as the level descended. On the contrary, during backward flexion, initial motion started from the lower level (L5/S1) to the upper levels. There was no relation between velocity and spinal levels during backward flexion. Motion profiles of both anterior and posterior vertebral corners at L3/L4 and L4/L5 segments during forward flexion were similar to those during backward flexion. However, the motion profiles at L5/S1 segment during forward flexion were different from those during backward flexion. Conclusions During forward flexion of the lumbar spine, initial motion started from upper segments to the lower segments with phase lags. During backward flexion, initial motion started from the lower segments to the upper segments. Motion profiles of the vertebral corners during forward flexion were similar to those during backward flexion at L3/L4 and L4/L5. The motion profiles at L5/S1 were different between both flexions.

Retrospective evaluation of complications in 180 consecutive patients with cervical disorders who had been treated by using pedicle screw fixation systems.To determine the risks associated with pedicle screw fixation in the cervical spine and to emphasize the importance of preoperative planning and surgical techniques in reducing the risks of this procedure.Generally, pedicle screw fixation in the cervical spine has been considered too risky for the neurovascular structures. There have been several reports describing the complications of lateral mass screw-plate fixation. However, no studies have examined in detail the complications associated with cervical pedicle screw fixation.One hundred eighty patients who underwent cervical reconstructive surgery using cervical pedicle screw fixation were reviewed to clarify the complications associated with the pedicle screw fixation procedure. Cervical disorders were spinal injuries in 70 patients and nontraumatic lesions in 110 patients. Seven hundred twelve screws were inserted into the cervical pedicles, and the locations of 669 screws were radiologically evaluated.Injury of the vertebral artery occurred in one patient. The bleeding was stopped by bone wax, and no neurologic complication developed after surgery. On computed tomographic (CT) scan, 45 screws (6.7%) were found to penetrate the pedicle, and 2 of 45 screws caused radiculopathy. Besides these three neurovascular complications directly attributed to screw insertion, radiculopathy caused by iatrogenic foraminal stenosis from excessive reduction of the translational deformity was observed in one patient.The incidence of the clinically significant complications caused by pedicle screw insertion was low. Complications associated with cervical pedicle screw fixation can be minimized by sufficient preoperative imaging studies of the pedicles and strict control of screw insertion. Pedicle screw fixation is a useful procedure for reconstruction of the cervical spine in various kinds of disorders and can be performed safely.

For the purpose of reduction of polyethylene wear generated in artificial hip joints, concave dimples were formed on the surface of the metal femoral head by electrical discharge etching with the constant diameter of 0.5 mm, pitch of 1.2 mm, and depth of 0.1 mm. Using a hip joint simulator, the total amount of polyethylene wear was 7.2 mg in the concave-patterned condition and 23.1 mg in the nonpatterned condition. The reasons for the reduction of polyethylene wear by the concave pattern may be i) a reduction of abrasive wear by providing escape dimples for wear particles and ii) an improvement in the lubricity on the frictional surface by the supply of lubricant that is stored in dimples.

An experimental study was performed in 32 adult beagle dogs to clarify the effect of nonphysiologically high initial tension on the mechanical and histologic properties of in situ frozen anterior cruciate ligaments. Both anterior cruciate ligaments in each dog underwent the in situ freeze-thaw treatment. The tibial insertion of the ligament was then made free from the tibia along with a cylindrical bone block. In the right knee, an initial tension of 20 N was applied on the anterior cruciate ligament by translocating the bone block in the distal direction. In the left knee, this bone block was anatomically reduced. Each bone block was firmly fixed with an interference screw. Ten animals were sacrificed at 6 weeks and 10 at 12 weeks. The tensile strength and the tangent modulus in the highly tensioned knee were significantly less than those in the physiologically tensioned knee at 12 weeks. Histologically, cell nuclei appeared to be spindle-shaped in the physiologically tensioned knee, while oval nuclei and focal degenerative changes with a number of vacuoles were occasionally found in the matrix in the highly tensioned knee. This study demonstrated that a nonphysiologically high tension significantly deteriorates the mechanical properties of the in situ frozen anterior cruciate ligament compared with physiologic tension.

We examined 24 patients with osteochondritis dissecans of the humeral capitellum to determine the results of nonoperative treatment. The average age of the patients at the initial examination was 13.3 years (range, 11 to 16). All the patients were advised to stop heavy use of the elbow for 6 months. At the last examination, at a mean follow-up period of 5.2 years, 4 patients (17%) had no residual elbow pain, 7 (29%) had pain only with heavy activities, and 13 (54%) had pain with activities of daily living. Final radiographs were obtained for 15 lesions, of which 3 lesions were assessed as healed, 3 as improved, and 9 as not improved. Five of 11 lesions in the early stage and all 4 advanced lesions failed to show radiographic improvement. These results suggest that osteochondritis dissecans of the capitellum has only a slight tendency to heal, and that instability can cause failure of the lesion to heal.

We present the long-term results of simple varus intertrochanteric osteotomy for osteonecrosis of the femoral head. We followed 26 hips in 20 patients, with a mean age at the time of surgery of 36 years, for a mean of 12.5 years. The mean varus angulation was 23°. The outcome in 19 of the hips (73%) was good or excellent; seven (27%) had a fair or poor result, with four needing some form of prosthetic arthroplasty. Simple varus intertrochanteric osteotomy is indicated, even if the extent of the capital infarct comprises more than 50% of the diameter of maximum radial distance from the circumference, provided that after operation the medial necrotic lesion measures less than two-thirds of the weight-bearing area, and the superolateral bone is normal.

Study design An in vivo sheep model was used to investigate the effect of spinal instrumentation on the healing process of posterolateral spinal fusion. Objectives To examine the role of spinal instrumentation during the healing process of posterolateral fusion. Summary of background data In long bone fractures, internal fixation improves the union rate but does not accelerate the healing process. Spinal instrumentation also improves the fusion rate in spinal arthrodesis. However, it remains unclear whether the use of spinal instrumentation expedites the healing process of spinal fusion. Methods Sixteen sheep underwent posterolateral spinal arthrodeses at L2-L3 and L4-L5 using equal amounts of autologous bone. One of those segments was selected randomly to be augmented with transpedicular screw fixation (Texas Scottish Rite Hospital spinal system). The animals were killed at 8 weeks or 16 weeks after surgery. Fusion status was evaluated by biomechanical testing, manual palpation, plain radiography, computed tomography, and histology. Results Instrumented fusion segments demonstrated significantly higher stiffness than did uninstrumented fusions at 8 weeks after surgery. Radiographic assessment and manual palpation showed that the use of spinal instrumentation improved the fusion rate at 8 weeks (47% versus 38% in radiographs, 86% versus 57% in manual palpation). Histologically, the instrumented fusions consisted of more woven bone than the uninstrumented fusions at 8 weeks after surgery. The 16-week-old fusion mass was diagnosed biomechanically, radiographically, and histologically as solid, regardless of pedicle screw augmentation. Conclusion The current study's results demonstrated that spinal instrumentation creates a stable mechanical environment to enhance the early bone healing of spinal fusion.

Effects of the overstressing induced by the harvest of grafts from the patellar tendon on the mechanical properties and morphometry of remaining tendon were studied using a rabbit model. The width of the patellar tendon was reduced by one-fourth or one-half equally removing the medial and lateral portions; by this surgery, the cross-sectional area was decreased by 25 or 50 percent from the original area. After all the rabbits were allowed unrestricted activities in cages for 3 to 12 weeks, their patellar tendons were harvested for mechanical and histological studies. The one-fourth removal induced no significant changes in the mechanical properties, but significantly increased the cross-sectional area. In the case of one-half removal, tensile strength and tangent modulus did not change in some tendons, although the cross-sectional area increased significantly. In the other central half tendons, mechanical strength decreased markedly, while the cross-sectional area increased; hypercellular areas and breakage of collagen bundles were observed in these tendons. These results indicate that the patellar tendon has an ability of functionally adapting to overstressing by changing the cross-sectional area, while keeping the mechanical properties unchanged, if the extent of overstressing is less than 30 percent.

Macrophage migration inhibitory factor (MIF) plays an important role in inflammation and immunity via autocrine/paracrine and endocrine routes. We examined the presence of MIF in the synovial fluids of rheumatoid arthritis (RA) patients. The content of MIF in the synovial fluid was quantitated by enzyme-linked immunosorbent assay which revealed that the concentration of MIF for RA patients was 85.7±35.2 ng/ml (mean±SD) ( n =25). In comparison, the concentrations for osteoarthritis patients and normal volunteers were 19.5±5.3 ng/ml ( n =12) and 10.4±1.1 ng/ml ( n =5), respectively. The expression of MIF mRNA and presence of MIF protein in the synovial tissues of RA were demonstrated by Northern blot and Western blot analyses, respectively. Immunohistochemical analysis revealed that positive staining was largely observed in the cytoplasm of infiltrating T lymphocytes, which might be the major source of MIF detected in the synovial fluids. The pathophysiological role of MIF in RA remains to be elucidated; however, the present results for the first time suggest the possibility that MIF is involved in the potentiation of inflammatory and immunological responses in rheumatoid joints.

Study design Cervical motion patterns were analyzed in a normal population and in patients with cervical instability by using cineradiography. Objectives To determine normal and pathologic motion patterns in the cervical spine through an in vivo continuous motion analysis. Summary of background data Cineradiographic techniques have been used in a limited number of studies to quantify spinal motion. There is a paucity of information regarding dynamic motion patterns in normal and pathologic cervical spines. Methods Ten healthy subjects and 12 patients with unstable cervical spines (C1-C2 subluxation caused by rheumatoid arthritis, n = 10; instability below C2, n = 2) were studied. Cervical motion during flexion from the maximum extension position was recorded using cineradiography. Cervical segmental motions (C1-C2 to C5-C6) were continuously measured through quantifying cineradiographic images projected on a digitizer. Results Normal cervical spines showed a well-regulated stepwise motion pattern that initiated at C1-C2 and transmitted to the lower segments with time lags. Pathologic spines showed a different order of onset of segmental motion. In patients with rheumatoid arthritis who had atlantoaxial subluxation, C1-C2 motion initiated significantly earlier than C2-C3 motion. In patients with segmental instability below C2, motion in the unstable segments preceded that in the upper intact segments. Conclusions Different motion patterns were observed between normal and pathologic cervical spines. Cineradiographic motion analysis is a valuable adjunctive technique, especially in diagnosis or evaluation of conditions that cannot be identified through conventional radiographic examination.

Changes in carpal kinematics under wrist distraction were studied in fresh cadaveric specimens. A magnetic tracking device measured kinematic motions of the scaphoid, lunate, and third metacarpal relative to the fixed radius in 3 planes of passive motion (coronal, sagittal, and "dart throwers") under progressive distraction loads. The change in percent contribution of the radiocarpal and midcarpal joints was calculated. Radiocarpal motion during extension was decreased as increasing traction was applied, but it increased with flexion. Motion of the scaphoid relative to the lunate was smaller in the oblique plane, resulting in less radiocarpal motion than in the sagittal plane. In the coronal plane, traction had little effect on radial deviation, but ulnar angulation of the scaphoid was greater with ulnar deviation of the wrist. These results suggest that different degrees of tension exist in the palmar and dorsal ligaments with the wrist under traction and during different planes of wrist motion. If wrist motion is desired during fixed traction, such as used clinically with external fixation, the dart-throwers motion (wrist extension with radial deviation and wrist flexion with ulnar deviation) appears to have the least impact on radiocarpal motion. If greater radiocarpal motion is desired, however, such as during postoperative mobilization, flexion-extension and radioulnar deviation will create more radiocarpal motion than the dart-thrower's motion. (J Hand Surg 1999;24A:113–120. Copyright © 1999 by the American Society for Surgery of the Hand.)

Macrophage migration inhibitory factor (MIF) is known as a pluripotent immunoregulatory cytokine involved in T-cell activation and inflammatory responses; however, no study on this protein in the peripheral nervous systems has been carried out. We here demonstrated for the first time expression of MIF mRNA and MIF protein in rat sciatic nerves by reverse transcription–polymerase chain reaction, Western blotting, and immunohistochemistry. Immunohistochemical analysis revealed positive staining of MIF, which was largely observed in Schwann cells. Furthermore, we examined MIF mRNA expression in the sciatic nerves by Northern blot analysis in the case of nerve transection. In both proximal and distal segments, the level of MIF mRNA started to increase 12 h after the nerve transection. The level remained high from 24 h up to day 7 after the injury. During the period from days 14 to 21, MIF mRNA sharply decreased to the pre-transection level. In immunohistochemistry, positive staining of MIF was largely observed in axons as well as non-neuronal cells in proximal segments at day 4 after transection. In the distal segments, contrastingly, endoneurial fibroblasts or Schwann cells migrating into neuronal fibers showed positive staining with Wallerian degeneration. Although the precise functions of MIF in the peripheral nerves remain to be elucidated, the present results could represent a major departure from the current state of knowledge, revealing a novel function in the degenerative–regenerative process.

The clinical features and results of treatment were reviewed in 17 traumatic palsies of the posterior interosseous nerve. Variations in clinical features depended on whether the recurrent branch or descending branch of the posterior interosseous nerve was injured. Seven patients had nerve repair, and two were treated by tendon transfers. Eight patients were treated conservatively. Sixteen of 17 patients recovered to more than M4 motor power at final follow-up. Associated muscle damage worsened the functional result.

STUDY DESIGN: Spinal kinematics after the implementation of rigid spinal instrumentation or the achievement of a solid fusion was studied using a sheep posterolateral spinal arthrodesis model. OBJECTIVE: To investigate the effects of rigid spinal instrumentation or solid fusion on spinal kinematic parameters. SUMMARY OF BACKGROUND DATA: Numerous studies have attempted to define spinal instability in terms of kinematics. Recent in vitro studies have documented the neutral zone, or a measure of spinal laxity, as more sensitive to spinal instability than the range of motion. METHODS: Seven skeletally mature sheep underwent a single-level posterolateral lumbar arthrodesis using autologous bone graft augmented with transpedicular screw fixation. The animals were killed 4 months after surgery. The identical surgical procedures were performed in seven sheep cadaveric spines, which served as acute postoperative controls. Each functional spinal unit was tested biomechanically before and after hardware removal. The experimental control groups consisted of destabilized spines and spines that underwent transpedicular screw fixation alone, whereas the fusion groups included spines that underwent posterolateral fusion alone or posterolateral fusion with instrumentation. RESULTS: Rigid instrumentation and solid fusion significantly decreased the neutral zone and range of motion in all testing modes. In axial rotation and lateral bending, solid fusion reduced the range of motion significantly more than transpedicular screw fixation alone. However, in all testing modes, the neutral zones showed no statistical difference between transpedicular screw fixation alone and fusion groups. CONCLUSIONS: The range of motion was an equivalent or better indicator of fixation or fusion stability compared with the neutral zone. Moreover, the immediate postoperative fixation stability, even if using transpedicular screw fixation, was less than the stability present after a solid fusion.

The chimeric transcript SYT-SSX is generated as a result of reciprocal translocation t(X;18), which is the primary cytogenetic abnormality found in, and appears to be specific for, synovial sarcoma. We performed a reverse transcriptase-polymerase chain reaction (RT-PCR) for SYT-SSX transcripts in a series of 84 tumors (61 soft tissue tumors and 23 bone tumors), including a variety of histologic types, to assess its usefulness in molecular diagnosis. Ten synovial sarcomas, three tumors initially unclassified, and one malignant peripheral nerve sheath tumor contained the chimeric transcripts. A review of the original slides and additional examination showed that a diagnosis of synovial sarcoma was appropriate for these cases. Additionally, in situ hybridization with an SSX1 probe indicated that the chimeric transcripts exist not only in the cells of special components but also in cells showing a variety of histologic patterns. Therefore, RT-PCR can be considered a useful molecular biological technique that can provide objective evidence for diagnosis of synovial sarcoma. Northern blot analysis with an SSX1 probe also detected chimeric SYT-SSX transcripts in the synovial sarcoma cases. The additional smaller bands, however, were also detected in six peripheral primitive neuroectodermal tumors (pPNETs) and one embryonal rhabdomyosarcoma. In five of these pPNETs, other bands ranging in size from 2.0 to 2.2 kb were also found, and it seems possible that these bands might represent novel karyotypic aberrations and/or splicing variants of SSX.

Although several types of intercarpal fusion have been advocated for the treatment of Kienbock's disease, the clinical outcome of each procedure is still inconclusive. The joint load and ligament tension based on a three-dimensional model were measured to determine which intercarpal fusion procedures unload the lunate and whether they alter the force transmission through the entire wrist joint. Ten theoretical models of wrists were used to simulate three different operative procedures: capitate-hamate fusion, scapho-trapezial-trapezoidal fusion, and scaphocapitate fusion. A discrete element analysis technique was used to perform these investigations. The joint force and ligament tension of normal wrists and of simulated operative procedures were calculated according to the deformation of each spring element, simulating the articular cartilage and the carpal ligaments. Scaphocapitate and scapho-trapezial-trapezoidal fusions significantly decreased the joint force at the radiolunate joint and the lunocapitate joint compared with the intact wrist. In contrast, these fusions significantly increased this value at the radioscaphoid joint in comparison with the intact wrist. In the midcarpal joint, scaphocapitate fusion also increased the joint force at the scapho-trapezial-trapezoidal joints and at the triquetral-hamate joint, whereas scapho-trapezial-trapezoidal fusion increased it at the scapho-capitate joint. Capitate-hamate fusion yielded no significant changes of the joint forces through the entire wrist joint. In the analysis of ligament tension, scaphocapitate and scapho-trapezial-trapezoidal fusions significantly decreased the tension only in the dorsal scapholunate ligament. These findings demonstrate that scaph-ocapitate and scapho-trapezial-trapezoidal fusions are effective in decompressing the lunate. By contrast, capitate-hamate fusion is ineffective in reducing lunate compression. Although scaphocapitate and scapho-trapezial-trapezoidal fusions are recommended for the treatment of Kienbock's disease, clinicians should consider that the increase of force transmission through the radioscaphoid and the midcarpal joints may lead to early degenerative changes after these procedures have been performed.

The authors report the case of a patient with rotatory posterior subluxation of the occiput on the atlas associated with tropism of the O-C1 articulations. Lateral flexion-extension plain films demonstrated 5 mm of posterior translation of the occiput on the atlas. Tomographs revealed tropism of the O-C1 articulations, and CT scans on extension demonstrated posterior rotatory subluxation of the occiput on the atlas. The patient had no osseous abnormality caudally below the atlantoaxial joint, and underwent posterior occipitoatlantal fusion by wiring. At the 4-year follow-up, the grafted bone had been incorporated, and the patient was completely free from preoperative symptoms. In the present patient, occipitoatlantal instability is presumed to have derived from articular tropism.

Alendronate (4-amino-1-hydroxybutylidene-1,1-bisphosphonate) is a potent inhibitor of bone resorption. The efficacy and safety of 36 weeks of treatment with alendronate were evaluated in Japanese women with osteoporosis, osteoporotic osteopenia or artificial menopause. The bone mineral density (BMD) of the lumbar vertebrae, markers of bone and calcium metabolism and clinical symptoms were monitored. A total of 113 randomly selected patients with osteoporosis or osteopenia were enrolled in the study, of whom 12 were excluded from the analyses because of lack of data. As a result, 101 patients were evaluated for the safety of the drug. Since eight patients were excluded from the efficacy analysis, 93 were evaluated. The incidence of adverse effects in the placebo (P), alendronate 2.5 mg/day (L) and alendronate 10 mg/day (H) groups increased with increasing dose of alendronate, being 6.1, 14.3 and 18.2%, respectively. The most common adverse effects were gastrointestinal symptoms, none of which was serious. Lumbar BMD increased after 36 weeks of drug administration to 5.21%, 5.64% and -0.90% in the L, H and P groups, respectively (P < 0.001, L vs. P and H vs. P). Serum alkaline phosphatase activity, serum osteocalcin and urinary deoxypyridinoline excretion were significantly decreased in a dose-related manner. Serum calcium and phosphorus were also significantly decreased after alendronate administration. Serum intact PTH was transiently increased. The present results indicate that alendronate effectively decreases bone turnover in a dose-related manner and increases lumbar BMD at a dosage of 2.5 mg/day, the lowest dose used in this study, in Japanese patients with osteoporosis.

While several different methods have been used to measure carpal kinematics, biplanar radiography is generally considered to be the most accurate and popular one. However, biplanar radiography is tedious and so only pseudo-dynamic kinematics can be measured. Recently, magnetic tracking system has been developed for the measurement of joint kinematics which is versatile and easy to use and so the possibility of measuring motions dynamically. In this study, the capability of a magnetic tracking device to accurately measure carpal kinematics was investigated by comparing it with biplanar radiography. The kinematics of the third metacarpal, scaphoid, and lunate in five fresh cadaveric specimens were measured using both methods as the wrists were placed in eight positions. The finite screw rotation of each bone with respect to the distal radius during selecting the seven wrist motions was calculated for both measuring techniques and compared. In general, the kinematics for all three bones measured by using either magnetic tracking device or biplanar radiography was identical and showed no statistical difference. The averaged differences ranged from 0.0 to 2.0°. These differences were due to the potential effect of the weight of the sensors and the interference of the attaching rod to the surrounding tissue. It is concluded that the application of the magnetic tracking device to carpal kinematics is warranted, if proper technical procedures as suggested are followed.

Study design This retrospective study was conducted to analyze the clinical results in 45 patients with nontraumatic lesions of the cervical spine treated by pedicle screw fixation. Objectives To evaluate the effectiveness of pedicle screw fixation in reconstructive surgery for nontraumatic cervical spinal disorders. Summary of background data Pedicle screw fixation for hangman's fracture of the axis and traumatic lesions of the middle and lower cervical spine has been reported; however, there have been no reports on pedicle screw fixation for nontraumatic lesions of the cervical spine. Methods Forty-five patients with nontraumatic lesions of the cervical spine underwent reconstructive surgery including pedicle screw fixation and fusion. Five patients underwent occipitocervical fixation for the lesion of the upper cervical spine, and one patient underwent separate occipitocervical fixation and cervicothoracic fixation. Cervical or cervicothoracic fixation was performed in 39 patients. Twenty-six of these patients underwent simultaneous laminectomy or laminoplasty. Supplemental anterior surgery was conducted for 15 patients. Results Solid fusion was obtained in all patients except eight with metastatic vertebral tumors who did not receive bone graft. Correction of kyphosis was adequate. There were no neurovascular complications, except one case of transient radiculopathy caused by screw threads. Conclusions Pedicle screw fixation is a useful procedure for posterior reconstruction of the cervical spine. This procedure does not require the lamina for stabilization, and should be especially valuable for simultaneous posterior decompression and fusion. The risk to neurovascular structures, however, cannot be completely eliminated.

Clear cell sarcoma (CCS), a rare tumour of deep soft tissues, often has a t(12; 22) (q13; q12) translocation that induces the formation of a hybrid EWS/ATF-1 gene. To investigate these alterations further, we established a new continuous cell line directly from a CCS taken from a 9-year-old girl. The cultures were characterized with respect to morphological, ultrastructural, immunohistochemical and karyotypical features and were tested by reverse transcription PCR (RT-PCR) for chimaeric EWS/ATF-1 transcripts. The continuous cell line, designated KAO, is tumorigenic in nude mice, and the resultant tumours resemble the primary CCS. The tumour cells and the cultured cells have melanosomes in their cytoplasm and are immunoreactive with the melanoma-specific antibody HMB45, but do not express S-100 protein. The cultured CCS cells have the t(12; 22)(q13; q12) translocation and express the hybrid EWS/ATF-1 gene. No transcripts of the hybrid gene were detected in a malignant cutaneous melanoma tested simultaneously. Although CCS and malignant melanoma are morphologically related, the present results suggest that their geneses differ at the chromosome and molecular levels. They also indicate that chromosome analysis and detection of fusion EWS/ATF-1 transcripts may be useful adjuvant tools for the diagnosis of CCS.

Study design The associations between vertebral body collapse and the size or location of the metastatic lesions were analyzed statistically to estimate the critical point of collapse. Objectives To determine risk factors for collapse, to estimate the predicted probability of collapse under various states of metastatic vertebral involvement, and to establish the criteria of impending collapse. Summary of background data Pathologic vertebral collapse brings about severe pain and paralysis in patients with cancer. Prevention of collapse plays a significant role in maintaining or improving their quality of life. Because no previous study has clarified the critical point of vertebral collapse, however, the optimum timing for prophylactic treatment has been unclear. Methods The size and location of metastatic tumor from Th1 to L5 were evaluated radiologically for 100 thoracic and lumbar vertebrae with osteolytic lesions. The correlations between collapse and the following risk factors (x1-x4) were determined by means of a multivariate logistic regression model: x1, tumor size (the percentage of tumor occupancy in the vertebral body [% TO]); x2, pedicle destruction, x3, posterior element destruction; and x4, costovertebral joint destruction. Results Significant risk factors were costovertebral joint destruction (odds ratio, 10.17; P = 0.021) and tumor size (odds ratio of every 10% increment in %TO, 2.44; P = 0.032) in the thoracic region (Th1-Th10), whereas, tumor size (odds ratio of every 10% increment in %TO, 4.35; P = 0.002) and pedicle destruction (odds ratio, 297.08; P = 0.009) were main factors in the thoracolumbar and lumbar spine (Th10-L5). The criteria of impending collapse were: 50-60% involvement of the vertebral body with no destruction of other structures, or 25-30% involvement with costovertebral joint destruction in the thoracic spine; and 35-40% involvement of vertebral body, or 20-25% involvement with posterior elements destruction in thoracolumbar and lumbar spine. Conclusions With respect to the timing and occurrence of vertebral collapse, there is a distinct discrepancy between the thoracic and thoracolumbar or lumbar spine. When a prophylactic treatment is required, the optimum timing and method of treatment should be selected according to the level and extent of the metastatic vertebral involvement.

We conducted a prospective, randomized, short-term study to clarify the effects of initial graft tension on clinical outcome after arthroscopically assisted anterior cruciate ligament reconstruction with autogenous dou bled semitendinosus and gracilis tendons connected in series with polyester tapes. Seventy Japanese patients with chronic, "isolated" anterior cruciate ligament tears were entered in the study. The patients were randomly divided into three groups based on initial graft tension: Group 1 (20 N), Group 2 (40 N), or Group 3 (80 N). No statistical differences were noted among the three groups with regard to their background factors. The patients were observed for 2 years or more after sur gery. Postoperatively, the average side-to-side differ ence in anterior laxity was 2.2 ± 2.4 mm in Group 1, 1.4 ± 1.8 mm in Group 2, and 0.6 ± 1.7 mm in Group 3. Analysis of variance testing showed that the post operative laxity in Group 3 was significantly less than that in Group 1. Spearman's rank-order correlation analysis also demonstrated significant correlation be tween the magnitude of initial graft tension and the magnitude of the postoperative laxity. This study dem onstrates that relatively high initial tension (up to 80 N) reduces the postoperative anterior laxity of the knee joint after anterior cruciate ligament reconstruction us ing the doubled autogenous hamstring tendons con nected in series with polyester tapes

Subjects of this study were 45 patients with 56 idiopathic congenital clubfeet (34 boys with 42 feet and 11 girls with 14 feet) who underwent successful conservative treatment. Radiologic examinations were performed at intervals of 3 months. In anteroposterior radiographs of bilateral feet, the period of appearance of the ossification center was observed for the first, second, and third cuneiform and the tarsal navicular. The ossification of the tarsal bones in the congenital clubfeet occurred later than that in the unaffected feet in boys. The difference between the clubfeet and the unaffected feet was particularly statistically significant for the tarsal navicular and the second cuneiform (p < 0.01). The tarsal naviculars, the first cuneiforms, and the second cuneiforms in clubfeet and in unaffected feet started to be ossified significantly earlier in girls than in boys. Ossification occurred out of order in three of 56 clubfeet and three of 34 unaffected feet.

A vascularised fibular strut graft was used for anterior spinal fusion in 16 patients with spinal kyphosis. The procedure was abandoned in three because of difficulty in establishing a vascular anastomosis and in one because the grafted fibula dislodged two days after operation. One patient died after five days. Of the 11 remaining patients, there were seven males and four females. Their ages at the time of operation averaged 30.9 years (12 to 71). The number of vertebrae fused averaged 6.7 (5 to 9) and the length of fibula grafted averaged 10.9 cm (6.5 to 18). Average follow-up was 54 months (27 to 84). Bone union occurred at both ends of the grafted fibula in all 11 patients, with an average time to union of 5.5 months (3 to 8). We did not see a fracture of the grafted fibula. Two patients had postoperative complications; the graft dislodged in one and laryngeal oedema occurred two days after operation in the other. A vascularised fibular strut graft provides a biomechanically stable and long-standing support in spinal fusion because the weak phase of creeping substitution does not take place in the graft.