Surgical management of omega deformity in a patient with neurofibromatosis type 1: a case report.

PURPOSE: To describe the surgical treatment in a patient with a partial omega deformity in the thoracic spine with neurofibromatosis type 1. METHODS: The patient was a 55-year-old man with an omega deformity, which is defined as a curvature in which the end vertebra is positioned at the level of, above, or below the apical vertebra (i.e., a horizontal line bisecting it). We performed halo gravity traction (HGT) for 7 weeks, followed by posterior spinal instrumented nearly equal in situ fusion from T2-L5 with three femoral head allografts and a local bone autograft. We avoided reconstruction of the thoracic anterior spine because of his severe pulmonary dysfunction. RESULTS: HGT improved the % vital capacity from 32.5 to 43.5%, and improved the Cobb angle of the kyphosis from > 180° before traction to 144° after traction. The Cobb angle of kyphosis and scoliosis changed from > 180° preoperatively to 155° and 146°, respectively, postoperatively, and 167° and 156°, respectively, at final follow-up. His postoperative respiratory function deteriorated transiently due to bilateral pleural effusions and compressive atelectasis, which was successfully treated with a frequent change of position and nasal high flow for 1 week. At final follow-up, his pulmonary function improved from 0.86 to 1.04 L in VC, and from 32.5 to 37.9% in %VC. However, there was no overall improvement in preoperative distress following surgery, although his modified Borg scale improved from 3 preoperatively to 0.5 postoperatively. One month after discharge, he felt worsening respiratory distress (SpO2:75%) and was readmitted for pulmonary hypertension for 2 months. He was improved by non-invasive positive pressure ventilation (biphasic positive airway pressure) for 1 week, medication and daily lung physiotherapy. Thereafter, he has been receiving permanent daytime (0.5 L/min) and nighttime (2 L/min) oxygen therapy at home. A solid arthrodesis through the fusion area was confirmed on computed tomography. However, the kyphosis correction loss was 12° (i.e., 155°-167°), while the scoliosis correction loss was 10° (i.e., 146°-156°) at 2 years of recovery. CONCLUSIONS: We suggest that nearly equal in situ fusion is a valid option for preventing further deformity deterioration and avoiding fatal complications.

Surgical Management of Intraosseous Neurofibroma in Cervical Spine: A Case Report.

CASE: A 30-year-old man had cervical radiculomyelopathy and neck pain caused by a massive intraosseous neurofibroma (IONF) originating from the C6 vertebrae. We performed posterior tumor resection with spinal instrumentation and fusion from C3 to T2 and a follow-up resection procedure of the remaining C6 anterior tumor, sacrificing the affected vertebral artery (VA), which accordingly required bypass surgery at 2 months recovery. Reconstruction using a titanium mesh cage was successfully performed. There were no local recurrences at 2 years postoperatively. CONCLUSIONS: Total tumor resection split into 2 stages with sacrifice of the affected VA is a feasible option for treatment of IONF.

Transforaminal Lumbar Interbody Fusion with Double Banana Cages: Clinical Evaluations and Finite Element Model Analysis.

STUDY DESIGN: Clinical and basic study. OBJECTIVES: This study aimed to investigate whether transforaminal lumbar interbody fusion (TLIF) using 2 banana-shaped cages leads to good clinical outcomes. METHODS: First, we conducted a clinical study to compare outcomes among patients who underwent TLIF using different types or numbers of cages. Propensity matched patients in each group were reviewed. Thirty-four patients who underwent surgery with 2 bullet-shaped cages (group A), 34 with a banana-shaped cage (group B), and 34 with 2 banana-shaped cages (group C) were compared. Twelve months after the surgery, bony fusion and cage subsidence were evaluated. RESULTS: The mean amount of cage subsidence was 14.9% in group A, 19.9% in group B, and 11.8% in group C. Subsidence in group B was significantly greater than that in group C (P < .01). Radiological bony fusion was not achieved in 2 cases in group B. Second, we performed a finite element model (FEM) analysis to determine the biomechanical stress of the vertebral endplate by comparing the single-banana cage construct with a double banana-shaped cage construct. FEM analysis showed that the maximum stress of the endplate in the single-cage model was 1.72-times greater than the maximum stress in the double-cage model. Furthermore, the maximal stress in the single-cage model was significantly higher than in the double-cage model during lumbar extension and side bending. CONCLUSION: This study showed that TLIF with double banana-shaped cages led to good clinical outcomes with less cage subsidence, probably because of decreased mechanical stress on the vertebral endplate.

The malignant transformation of osteoid osteoma in the cervical spine to high-grade osteosarcoma: a case report and review of literature.

PURPOSE: Osteoid osteoma occasionally occur in the spine, but their malignant transformation is not common. We present an extremely rare case of the malignant transformation of an osteoid osteoma to high-grade osteosarcoma that formed in the pedicle and spread to the lateral mass of the cervical spine. CASE PRESENTATION: We report the case of an 18-year-old man who suffered from neck pain as an initial symptom. The size of the radiolucent lesion was 12 mm in diameter at the time of diagnosis. Intralesional tumour resection and autologous bone grafting were performed. The remaining tumour grew gradually for 40 months after the surgery; therefore, the tumour had grown rapidly till 51 months after the initial diagnosis. At this stage, the tumour size was approximately 6-fold larger than the initial size, and resulted in progressive paraplegia. A biopsy revealed that the tumour had transformed into a high-grade osteosarcoma. Heavy charged particle irradiation was performed to control tumour growth. CONCLUSIONS: There is a possibility of malignant transformation of osteoid osteoma. Patients with osteoid osteoma or osteoblastoma should be carefully observed, especially for recurrent tumours after an intralesional resection.

Spontaneous morphological remodelling of the O-C1 joint after posterior fusion for occipitocervical dislocation.

BACKGROUND: Traumatic occipitocervical dislocation (OCD) occurs due to fatal high-energy injury. Modern screw-based constructs enable successful reduction and stabilisation. In view of this, there are no previous reports on the spontaneous remodelling of the O-C1 joint after posterior fusion. We report the first case of postoperative spontaneous remodelling and stabilisation of the O-C1 joint after traumatic OCD.Case description: A 9-year-old girl suffered from traumatic OCD, accompanied by complete rupture of the O-C1-C2 ligamentous complex. Halo-vest fixation, and subsequently posterior fusion surgery from the occipital bone to C2, with autologous iliac crest bone graft and an allograft were performed. However, we could not achieve complete reduction of the O-C1 joint during surgery owing to extremely severe instability.Postoperative X-ray and computed tomography scan showed incomplete reduction of the O-C1 joint. Insufficient congruity of the O-C1 joint persisted. Afterwards, gradual spontaneous remodelling of the O-C1 joint occurred, both anteriorly and posteriorly 3 months postoperatively. Solid union was achieved 6 months postoperatively. Two years later, bilateral O-C1 joints in the patient were completely reformed and restabilised by incredible vigorous remodelling. Insufficient reduction and persisting poor joint congruence after surgery for OCD was probably restabilised by further spontaneous remodelling of articular morphology in such a young patient. CONCLUSIONS: Postoperative spontaneous remodelling of the O-C1 joint after posterior reconstruction for OCD may occur in young patients. Incomplete reduction of the O-C1 joint during surgery may be acceptable due to the possibility of postoperative bone remodelling and restabilisation.

Compensatory Pelvic Retro-Rotation Associated with a Decreased Quality of Life in Patients with Normal Sagittal Balance.

STUDY DESIGN: Cross-sectional observational study. PURPOSE: To examine whether pelvic rotation as a compensatory mechanism for sagittal imbalance is related to quality of life (QOL). OVERVIEW OF LITERATURE: Poor sagittal alignment is associated with compensatory pelvic retroversion and decreased QOL. Whether the compensatory pelvic tilt (PT) influences QOL is unclear. METHODS: Overall, 134 subjects aged ≥20 years with lower back pain were included (104 females; mean age, 70±9.8 years). Sagittal vertical alignment (SVA) and PT were analyzed radiographically. Patients were stratified into three groups based on SVA values: good alignment (group G), intermediate alignment (group I), and poor sagittal alignment (group P). Patients in group I were further categorized into two groups: low PT and high PT. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) was used for clinical assessment, and the scores were compared between groups. RESULTS: As SVA increased, PT and lumbar lordosis (LL) increased and decreased, respectively. PT and LL differed significantly between groups G and P (p<0.01 for each comparison). Within group I, there was no significant difference in SVA between the high PT and low PT groups, suggesting that the high PT group had acquired a compensated sagittal balance. Importantly, all domains in the JOABPEQ (except for lower back pain) were significantly lower in the high PT group than in the low PT group (p<0.05 for every comparison). CONCLUSIONS: This study showed that focusing solely on SVA as a single indicator can cause important losses in QOL to be overlooked in patients with lumbar disorders. Although pelvic retroversion can compensate for sagittal balance, it is associated with a significant decrease in QOL. To improve the assessment of patients with lumbar disorders, PT should be considered besides SVA.

Surgical Management of Thoracolumbar Scoliosis Secondary to Hip Joint Ankylosis and Severe Pelvic Obliquity.

We report a rare case of a rigid spinal deformity with severe pelvic obliquity (PO) resulting from hip ankylosis caused by childhood tuberculosis (TB). A 66-year-old woman presented with left knee pain, chronic low back pain, and fatigability during walking. She presented with leg length discrepancy (LLD) due to an ankylosed right hip joint, severe PO, and secondary lumbar scoliosis. Total hip arthroplasty (THA) and adductor tendonectomy were performed prior to spine surgery, and posterior spinal correction and fusion were performed from T10 to the pelvis. Prior to spinal correction surgery, we predicted that it would be impossible to make the pelvis perfectly horizontal. Therefore, we positioned a prosthetic acetabular cup at a small inclination angle at the upper limit of anteversion; spinal correction and fusion were then performed. Her symptoms including fatigability during walking resolved and the sagittal spinal balance on standing improved dramatically. The preoperative and postoperative values of the thoracolumbar Cobb angle was 40° and 25°, lumbosacral Cobb angle was 60° and 14°, C7 plumb line shift was 24 and 0 mm, pelvic tilt was 15° and 19°, lumbar lordosis (LL) was 23° and 60°, pelvic incidence minus lumbar lordosis (PI-LL) was 38° and 1°, the sagittal vertical axis was 80 and 0 mm, and PO was 28° and 15°, respectively. We present a case of rigid spinal deformity accompanied by hip joint ankylosis and PO. Performing THA prior to spinal correction surgery is an alternative and feasible option for the treatment of this challenging pathology.

Ectopic gas in the fibular graft after anterior cervical corpectomy and fusion.

BACKGROUND: Ectopic gas in the graft is occasionally encountered upon follow-up computed tomography (CT) after anterior cervical corpectomy and fusion (ACCF). However, most cases lack inflammatory responses and manifestations of infection. Although the clinical significance of ectopic gas in the graft has not yet been established, to the best of our knowledge, no previous studies have described ectopic gas in the graft after ACCF. This study evaluated ectopic gas in the fibular graft upon follow-up CT after ACCF. METHODS: We reviewed 112 patients who underwent ACCF and follow-up CT, with a minimum follow-up period of 3 years. CT images were retrospectively reviewed to confirm the presence of ectopic gas in the graft and bone fusion. Bone fusion was defined as follows: mobility less than 2 mm between spinous processes on the flection-extension radiograph or a bone bridge on CT images. RESULTS: Of the 112 patients, 30 (27%) patients had ectopic gas in the fibular grafts. Among them, ectopic gas was initially observed 3 months after surgery (early onset) in 23 (77%) patients and 6 months after surgery (late-onset) in the remaining seven (23%) patients. Upon the latest follow-up CT, ectopic gas more frequently remained in late-onset (4/7, 57%) rather than in early-onset (3/23, 13%) cases (p = 0.033). Bone fusion was not observed when CT images exhibited ectopic gas in the graft, whereas ectopic gas was not observed when CT images exhibited bone fusion. CONCLUSION: Ectopic gas in the fibular graft was observed at both early and late-onset after ACCF; late-onset gas remained significantly. The remaining gas was strongly associated with pseudoarthrosis; therefore, pseudoarthrosis should be considered when ectopic gas in the graft is observed on CT images.

Diffuse midline glioma in the spinal cord with rapid respiratory deterioration.

BACKGROUND: Neurogenic acute respiratory failure is usually caused by either infection or vascular insufficiency. We report the case of a patient who developed acute respiratory failure secondary to a spinal tumor. CASE PRESENTATION: A 32-year-old man, presenting with numbness and muscle weakness in his legs for 2 weeks, was transferred to our hospital with worsening quadriplegia and development of respiratory symptoms. We carried out emergent spinal decompression and initiated steroid pulse therapy, with no resolution of symptoms; a tumor incision biopsy after contrast cervical magnetic resonance imaging revealed an intraspinal tumor with a pathological diagnosis of World Health Organization grade IV glioma. The patient developed bradycardia, severe sepsis, status epilepticus, and cardiopulmonary arrest due to hypoxemia and was treated with chemoradiotherapy under mechanical ventilation. He was later transferred to another hospital for subacute care. CONCLUSION: Acute respiratory failure caused by spinal tumors is uncommon. However, acute care practitioners should be mindful of neoplastic lesions as a potential cause.

Bilateral vocal cord palsy after a posterior cervical laminoplasty.

PURPOSE: To report a patient with bilateral vocal cord palsy following cervical laminoplasty, who survived following a tracheotomy and intensive respiratory care. METHODS: Acute respiratory distress is a fatal complication of cervical spinal surgery. The incidence of bilateral vocal cord palsy after posterior cervical decompression surgery is extremely rare. The authors report a 71-year-old woman who suffered from cervical myelopathy due to ossification of the posterior longitudinal ligament. Open-door laminoplasty from C2 to C6 and laminectomy of C1 were performed. Following surgery, extubation was successfully conducted. Acute-onset dysphagia and stridor had occurred 2 h following extubation. A postoperative fiber optic laryngoscope revealed bilateral vocal cord palsy. After a tracheotomy and intensive respiratory care, she had completely recovered 2 months after surgery. DISCUSSION: One potential cause of this pathology was an intraoperative hyper-flexed neck position, which likely induced mechanical impingement of the larynx, resulting in swelling and edema of the vocal cords and recurrent laryngeal nerve paresis. Direct trauma of the vocal cords during intubation and extubation could have also induced vocal cord paralysis. CONCLUSIONS: We reported a case of bilateral vocal cord palsy associated with posterior cervical laminoplasty. Airway complications following posterior spinal surgery are rare, but they do occur; therefore, spine surgeons should be aware of them and take necessary precautions against intraoperative neck position, intubation technique, even positioning of the intratracheal tube.

Intracranial subarachnoid hemorrhage following cervical laminoplasty: a report of two cases.

Intracranial hemorrhage is a rare complication of spinal surgery. Case 1 was a 58-year-old man who underwent cervical laminoplasty. No apparent iatrogenic dural rupture or cerebrospinal fluid leakage was observed. An hour after the surgery, the patient had convulsions and became restless thereafter. CT revealed an intracranial subarachnoid hemorrhage (SAH). The patient recovered normal consciousness the next morning. Case 2 was a 68-year-old woman who underwent cervical laminoplasty without postoperative cerebrospinal fluid leakage. Six days after the surgery, the patient continued to complain of nausea and headache. By 13 days, the patient reported relief from her symptoms. There was no evidence of cerebral aneurysm, or vascular malformation in both cases. Patients undergoing cervical laminoplasty might be at risk for developing SAH. Careful attention to intraoperative neck positioning, strict monitoring and control of perioperative blood pressure, and complete dural repair are essential measures for preventing SAH.

Sagittal Alignment of a Strut Graft Affects Graft Subsidence and Clinical Outcomes of Anterior Cervical Corpectomy and Fusion.

STUDY DESIGN: Retrospective study. PURPOSE: The purpose of this study was to investigate the influence of sagittal alignment of the strut graft on graft subsidence and clinical outcomes after anterior cervical corpectomy and fusion (ACCF). OVERVIEW OF LITERATURE: ACCF is a common technique for the treatment of various cervical pathologies. Although graft subsidence sometimes occurs after ACCF, it is one cause for poor clinical results. Malalignment of the strut graft is probably one of the factors associated with graft subsidence. However, to the best of our knowledge, no prior reports have demonstrated correlations between the alignment of the strut graft and clinical outcomes. METHODS: We evaluated 56 patients (33 men and 23 women; mean age, 59 years; range, 33-84 years; 45 with cervical spondylotic myelopathy and 11 with ossification of the posterior longitudinal ligament) who underwent one- or two-level ACCF with an autogenous fibular strut graft and anterior plating. The Japanese Orthopaedic Association (JOA) score recovery ratio for cervical spondylotic myelopathy was used to evaluate clinical outcomes. The JOA score and lateral radiograms were evaluated 1 week and 1 year postoperatively. Patients were divided into two groups (a straight group [group I] and an oblique group [group Z]) based on radiographic assessment of the sagittal alignment of the strut graft. RESULTS: Group I showed a significantly greater JOA score recovery ratio (p<0.05) and a significantly lower graft subsidence than group Z (p<0.01). CONCLUSIONS: Our findings suggest that a straight alignment of the strut graft provides better clinical outcomes and lower incidence of graft subsidence after ACCF. In contrast, an oblique strut graft can lead to significantly increased strut graft subsidence and poor clinical results.

Morphologic Changes in Contralateral Lumbar Foramen in Unilateral Cantilever Transforaminal Lumbar Interbody Fusion Using Kidney-type Intervertebral Spacers.

STUDY DESIGN: A retrospective study of 58 patients undergoing cantilever transforaminal lumbar interbody fusion (c-TLIF). OBJECTIVES: To evaluate morphologic changes in the intervertebral foramen (IVF) on the side contralateral to spacer insertion in patients undergoing c-TLIF using plain x-ray films and computed tomography scan. SUMMARY OF BACKGROUND DATA: The morphologic changes in the contralateral lumbar foramen in c-TLIF using unilateral insertion of spacers have not been well studied. MATERIALS AND METHODS: Fifty-eight consecutive patients with lumbar dysplastic changes or degenerative disk diseases underwent c-TLIF using 96 kidney-type spacers with local bone grafts. Radiographic findings (sagittal disk angle), computed tomography scan findings (coronal disk angle, disk height, foraminal height (FH), foraminal width, and cross-sectional area of IVF in contralateral lumbar foramen) were compared between preoperative period and 6 months after surgery. The correlations between contralateral lumbar foraminal dimensions and disk height, sagittal disk angle, and coronal disk angle were analyzed. RESULTS: After c-TLIF, sagittal angle, disk height, FH, foraminal width, and cross-sectional area of the IVF were significantly increased. Increase in posterior disk height showed a positive correlation with increases in FH, foraminal width, and cross-sectional area of IVF (r=0.235-0.511). However, the increase in sagittal disk angle showed a negative correlation with changes in foraminal width and cross-sectional area of IVF (r=-0.256 to -0.206). CONCLUSIONS: Lumbar foraminal dimensions on the side contralateral to spacer insertion increased significantly after c-TLIF, suggesting that c-TLIF enables indirect decompression of the contralateral nerve root. Although increase in posterior disk height was shown to be an important factor to increase contralateral foraminal size, segmental lordosis was a risk factor for a decrease in contralateral foraminal size.

Comparison of functional recovery in the very early period after surgery between plate and nail fixation for correction of stable femoral intertrochanteric fractures: a controlled clinical trial of 18 patients.

PURPOSE: This study aimed to compare the differences in functional recovery between patients undergoing plate and nail fixation in the very early period after surgery. METHOD: This study was designed as a controlled clinical trial that included 18 patients who were surgically treated with either dynamic hip screw as plate fixation or proximal femoral nail as nail fixation for stable intertrochanteric fractures. In particular, all patients selected for the study reported walking completely independently without the use of walking aids prior to sustaining their initial fracture. In all, 8 patients (mean age, 73.8 years; range, 65-89 years) were treated with plate fixation (group plate) and 10 patients (mean age, 79.7 years; range, 70-90 years) were treated with nail fixation (group nail). Functional evaluations were assessed every week after surgery using the Japanese Orthopaedic Association (JOA) hip functional scores and active range of motion (ROM) of the hip joint. RESULTS: The recovery of activities of daily living (ADLs) according to JOA hip functional scores at week 4 after surgery was significantly better in group nail than in group plate (P = .03), whereas active ROM of hip flexion improved significantly in group plate than in group nail at weeks 3 and 4 after surgery (P = .04 and P = .02, respectively). CONCLUSIONS: The results suggested that nail fixation may provide a more rapid recovery of ADLs than that of plate fixation in the very early period after surgery. However, plate fixation may provide better ROM of hip flexion than that of nail fixation.

Cervical symmetric dumbbell ganglioneuromas causing severe paresis.

We report an extremely rare case with bilateral and symmetric dumbbell ganglioneuromas of the cervical spine in an elderly patient. A 72-year-old man came by ambulance to our hospital due to progressive incomplete paraplegia. Magnetic resonance imaging demonstrated bilateral symmetric dumbbell tumors at the C1/2 level. We performed total resection of the intracanalar tumor, aiming at complete decompression of the spinal cord, and partial and subtotal resection of foraminal outside portions. Histopathological examination of the surgical specimen indicated the tumor cells to be spindle cells with the presence of ganglion cells and no cellular pleomorphism, suggesting a diagnosis of ganglioneuroma. Although the surgery was not curative, the postoperative course was uneventful and provided a satisfactory outcome. This is the fourth known case of cervical ganglioneuromas of the bilateral symmetric dumbbell type.

Pathogenesis of Morquio A syndrome: an autopsied case reveals systemic storage disorder.

Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) is a lysosomal storage disorder caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase, which results in systemic accumulation of glycosaminoglycans (GAGs), keratan sulfate and chondroitin-6-sulfate. Accumulation of these GAGs causes characteristic features as disproportionate dwarfism associated with skeletal deformities, genu valgum, pigeon chest, joint laxity, and kyphoscoliosis. However, the pathological mechanism of systemic skeletal dysplasia and involvement of other tissues remain unanswered in the paucity of availability of an autopsied case and successive systemic analyses of multiple tissues. We report here a 20-year-old male autopsied case with MPS IVA, who developed characteristic skeletal features by the age of 1.5 years and died of acute respiratory distress syndrome five days later after occipito-C1-C2 cervical fusion. We pathohistologically analyzed postmortem tissues including trachea, lung, thyroid, humerus, aorta, heart, liver, spleen, kidney, testes, bone marrow, and lumbar vertebrae. The postmortem tissues relevant with clinical findings demonstrated 1) systemic storage materials in multiple tissues beyond cartilage, 2) severely vacuolated and ballooned chondrocytes in trachea, humerus, vertebrae, and thyroid cartilage with disorganized extracellular matrix and poor ossification, 3) appearance of foam cells and macrophages in lung, aorta, heart valves, heart muscle, trachea, visceral organs, and bone marrow, and 4) storage of chondrotin-6-sulfate in aorta. This is the first autopsied case with MPS IVA whose multiple tissues have been analyzed pathohistologically and these pathological findings should provide a new insight into pathogenesis of MPS IVA.

Fatal fat embolism syndrome in a case of isolated L1 vertebral fracture-dislocation.

Although fat embolism syndrome is a well-known complication of fractures of the long bones or pelvis, fat embolism syndrome occurring subsequent to fracture of the lumbar spine is rare. We report a fatal case of fat embolism syndrome characterized by fat and bone marrow embolism that occurred 36 h after an isolated fracture-dislocation of the L1 vertebra. A postmortem examination was performed and pathological finding demonstrated fat and bone marrow tissue which were disseminated in the bilateral pulmonary arteries. We need to be aware of the possibility of fat embolism syndrome as a complication of spinal fractures, including isolated vertebral body fractures.

Repair of pars defects by segmental transverse wiring for athletes with symptomatic spondylolysis: relationship between bony union and postoperative symptoms.

STUDY DESIGN: Retrospective study of surgery for spondylolysis patients. OBJECTIVE: To assess clinical outcome of bony union using multislice computed tomography after segmental wiring fixation. SUMMARY OF BACKGROUND DATA: How bony union affects surgical outcome of spondylolysis repair is unclear. METHODS: Forty-four athletes with symptomatic spondylolysis (33 men and 11 women; mean age, 24.2 ± 5.4 years) who underwent segmental wiring fixation were evaluated retrospectively at a mean follow-up of 85 ± 17 months. The level of spondylolysis was L5 in 42 cases, and both L4 and L5 in 2 cases, giving a total of 46 operative levels of vertebrae. Bony union using axial and sagittal reconstruction images of computed tomography, the Japanese Orthopaedic Association (JOA) score for back pain, and complications were reviewed. State of bony union was classified as bilateral union, unilateral union, or nonunion. The total score and the improvement ratio of the JOA score were compared among the 3 groups. RESULTS: Bilateral bony union was obtained in 29 cases (31 of 46 vertebrae, 67.4%). Six cases (13%) showed unilateral union, and 9 cases (19.6%) showed nonunion. JOA score increased significantly after surgery in all groups, average improvement rate was 78.9% in the bilateral group, 63.6% in the unilateral group, and 29.8% in the nonunion group; differences among the 3 groups were significant (P < 0.05). JOA score was significantly higher in the bilateral group than in the other 2 groups. CONCLUSION: Although symptoms were significantly ameliorated in all groups, the bilateral group showed the greatest improvement ratio in JOA score showing bony union to be an important factor in clinical outcome. However, there were a few exceptional cases with contradictory clinical and radiological outcomes. Thus, further studies are required to gain a better understanding of the other multiple factors affecting clinical outcome after spondylolysis repair.