Selection of proximal fusion level for adult degenerative lumbar scoliosis.

INTRODUCTION: There is controversy regarding the appropriate proximal fusion level for adult degenerative scoliosis. Ideally, the horizontal vertebra is chosen for the upper instrumented vertebra to create a balanced spine. Fusion to T10 is recommended to prevent junctional problems at the proximal adjacent segment. The purpose of this retrospective study was to determine the optimal proximal fusion level for adult degenerative lumbar scoliosis. MATERIALS AND METHODS: Fifty-one patients with adult degenerative lumbar scoliosis (mean age 64.6 years) who underwent posterior instrumentation were analyzed after a minimum 2-year follow-up. The average number of levels fused was 5.9 segments (range 3-9) with distal fusion at L5 in 30 patients and S1 in 21 patients. The upper instrumented vertebra (UIV) ranged from T9 to L2. According to the relationship between UIV, horizontal vertebra (HV) and upper end vertebra (UEV), the patients were divided into three groups in the coronal plane: Group HV (UIV = HV or above); Group HV-UEV (UIV = between HV and UEV); and Group UEV (UIV = UEV or below). In the sagittal plane; the patients were divided into Group T9-10 (UIV = T9-10), Group T11-12 and Group L1-2. RESULTS: Proximal adjacent segment disease (ASD) was identified in 13 (25 %) out of 51 patients, including junctional kyphosis (n = 5), compression fractures (n = 4), progression of disc wedging (n = 2) and spinal stenosis (n = 2). Group UEV had more ASD (9 of 16 patients) compared to Group HV (2 of 21 patients) and Group HV-UEV (2 of 14 patients). It appeared that neutral vertebra could be a criterion for the selection of UIV in the coronal plane. Among the groups divided in the sagittal plane, proximal ASD was found in 47 % of 19 patients in Group L1-2, which was notably higher than 9 % in Group T9-10 and 20 % in Group T11-12. CONCLUSIONS: Proximal adjacent segment disease developed more commonly when the proximal fusion stopped at the UEV or below in adult degenerative lumbar scoliosis. UIV must be above UEV in the coronal plane. Fusion to T11 or T12 was acceptable when UIV was above UEV, since there was no significant difference in the rate of proximal adjacent segment between fusion to T10 and fusion to T11 or T12.

Arthrodesis to L5 versus S1 in long instrumentation and fusion for degenerative lumbar scoliosis.

There is a debate regarding the distal fusion level for degenerative lumbar scoliosis. Whether a healthy L5-S1 motion segment should be included or not in the fusion remains controversial. The purpose of this study was to determine the optimal indication for the fusion to the sacrum, and to compare the results of distal fusion to L5 versus the sacrum in the long instrumented fusion for degenerative lumbar scoliosis. A total of 45 patients who had undergone long instrumentation and fusion for degenerative lumbar scoliosis were evaluated with a minimum 2 year follow-up. Twenty-four patients (mean age 63.6) underwent fusion to L5 and 21 patients (mean age 65.6) underwent fusion to the sacrum. Supplemental interbody fusion was performed in 12 patients in the L5 group and eleven patients in the sacrum group. The number of levels fused was 6.08 segments (range 4-8) in the L5 group and 6.09 (range 4-9) in the sacrum group. Intraoperative blood loss (2,754 ml versus 2,938 ml) and operative time (220 min versus 229 min) were similar in both groups. The Cobb angle changed from 24.7 degrees before surgery to 6.8 degrees after surgery in the L5 group, and from 22.8 degrees to 7.7 degrees in the sacrum group without statistical difference. Correction of lumbar lordosis was statistically better in the sacrum group (P = 0.03). Less correction of lumbar lordosis in the L5 group seemed to be associated with subsequent advanced L5-S1 disc degeneration. The change of coronal and sagittal imbalance was not different in both groups. Subsequent advanced L5-S1 disc degeneration occurred in 58% of the patients in the L5 group. Symptomatic adjacent segment disease at L5-S1 developed in five patients. Interestingly, the development of adjacent segment disease was not related to the preoperative grade of disc degeneration, which proved minimal degeneration in the five patients. In the L5 group, there were nine patients of complications at L5-S1 segment, including adjacent segment disease at L5-S1 and loosening of L5 screws. Seven of the nine patients showed preoperative sagittal imbalance and/or lumbar hypolordosis, which might be risk factors of complications at L5-S1. For the patients with sagittal imbalance and lumbar hypolordosis, L5-S1 should be included in the fusion even if L5-S1 disc was minimal degeneration.

Short fusion versus long fusion for degenerative lumbar scoliosis.

The extent of fusion for degenerative lumbar scoliosis has not yet been determined. The purpose of this study was to compare the results of short fusion versus long fusion for degenerative lumbar scoliosis. Fifty patients (mean age 65.5 +/- 5.1 years) undergoing decompression and fusion with pedicle screw instrumentation were evaluated. Short fusion was defined as fusion within the deformity, not exceeding the end vertebra. Long fusion was defined as fusion extended above the upper end vertebra. The lower end vertebra was included in the fusion in all the patients. The short fusion group included 28 patients and the long fusion group included 22 patients. Patients' age and number of medical co-morbidities were similar in both the groups. The number of levels fused was 3.1 +/- 0.9 segments in the short fusion group and 6.5 +/- 1.5 in the long fusion group. Before surgery, the average Cobb angle was 16.3 degrees (range 11-28 degrees ) in the short fusion group and 21.7 degrees (range 12-33 degrees ) in the long fusion group. The correction of the Cobb angle averaged 39% in the short fusion group and 72% in the long fusion group with a statistical difference (P = 0.001). Coronal imbalance improved significantly in the long fusion group more than in the short fusion group (P = 0.03). The correction of lateral listhesis was better in the long fusion group (P = 0.02). However, there was no difference in the correction of lumbar lordosis and sagittal imbalance between the two groups. Ten of the 50 patients had additional posterolateral lumbar interbody fusion at L4-5 or L5-S1. The interbody fusion had a positive influence in improving lumbar lordosis, but was ineffective at restoring sagittal imbalance. Early perioperative complications were likely to develop in the long fusion group. Late complications included adjacent segment disease, loosening of screws, and pseudarthrosis. Adjacent segment disease developed in ten patients in the short fusion group, and in five patients in the long fusion group. In the short fusion group, adjacent segment disease occurred proximally in all of the ten patients. Loosening of distal screws developed in three patients, and pseudarthrosis at L5-S1 in one patient in the long fusion group. Reoperation was performed in four patients in the long fusion group and three patients in the short fusion group. In conclusion, short fusion is sufficient for patients with small Cobb angle and good spinal balance. For patients with severe Cobb angle and rotatory subluxation, long fusion should be carried out to minimize adjacent segment disease. For patients who have severe sagittal imbalance, spinal osteotomy is an alternative technique to be considered. As long fusion is likely to increase early perioperative complications, great care should be taken for high-risk patients to avoid complications.

Measurement of polyethylene wear in total hip arthroplasty--accuracy versus ease of use.

The aim of this study was to compare the accuracy of four different methods for measuring wear using an apparatus that simulates known amounts of three dimensional wear. Wear was measured using the manual methods reported by Charnley, Livermore, Dorr and Wan and the computerized method reported by Devane. Only the method reported by Devane measured the three-dimensional (superior and anterior) wear with a reasonable accuracy, with a mean measurement error of 0.21 mm. With superior wear alone, Charnley's method underestimated the extent of wear by 16.6%, with a mean error of 0.35 mm; Livermore's method estimated wear to within 9.5%, with a mean error of 0.16 mm; Devane's method estimated wear to within 9.5%, with a mean error of 0.15 mm; and Dorr's method underestimated wear by 25.4%, with a mean error of 0.56 mm. Dorr's method was modified as a result of the experimental tests. The clinical application of the new method showed comparable data to that using the Devane method. In conclusion, this new method can be used to estimate the average wear in groups of patients accurately.

Lipoma arborescens of the knee.

Lipoma arborescens are rare lesions, typically located in the knee. They have a predilection for the suprapatellar pouch in the knee joint, but can also occur in any area of the knee joint. Magnetic resonance imaging of lipoma arborescens often reveals subchondral bone cyst and/or bone erosions, and there may appear to be a correlation between lipoma arborescens and osteoarthritis. We describe a case of histologically proven lipoma arborescens in the suprapatellar pouch and infrapatellar area of the knee with no damage to the posterior compartment and bone erosion in the proximal tibia without osteoarthritis.

Total hip arthroplasty using S-ROM prosthesis for dysplastic hip.

PURPOSE: The purpose of this study was to evaluate the clinical and radiological results of total hip arthroplasty using a proximal modular femoral stem in patients who had secondary coxarthrosis associated with a dysplastic hip. MATERIALS AND METHODS: Forty-two patients (45 hips) with secondary coxarthrosis were evaluated after undergoing primary total hip arthroplasty using an S-ROM proximal modular femoral stem. The average follow-up was 80 months (range: 60 to 96 months). Clinical and radiological assessments were performed based on the Harris hip score and the radiological changes around the prosthesis. RESULTS: The average Harris hip score improved from 52.2 points to 88.5 points. All femoral stems showed stable fixation; there were 37 cases by bony ingrowth and 8 cases by stable fibrous ingrowth. Neither osteolysis nor progressive radiolucent lines around the femoral stem were found at the last follow-up. Forty-one hips (91.9%) revealed excellent or good clinical results at the most recent follow-up. CONCLUSION: For advanced secondary coxarthrosis, total hip arthroplasty with the use of the proximal modular femoral stem yielded good mid-term results with respect to the clinical and radiological criteria.

Long-term results of total hip arthroplasty with an extensively porous coated stem in patients younger than 45 years old.

PURPOSE: This study analyzed the long-term results of cementless total hip arthroplasty using an extensively porous coated stem in patients younger than 45 years old. MATERIALS AND METHODS: The clinical and radiographic results of 45 hips from 38 patients who underwent cementless total hip replacement arthroplasty with an AML prosthesis were reviewed retrospectively. The average follow-up was 12 years (range, 10-15 years). RESULTS: The average Harris hip score at the time of final follow-up was 87.3 (range 77-94) points. Forty two hips (93.3%) showed excellent and good clinical results. Osteolysis occurred around the stem in 20 hips (44.4%) and around the cup in 26 hips (57.8%). Stress-mediated femoral resorption was observed in 33 hips (73.3%) at 10 years. There was no incidence of resorption progressing after 5 years postoperatively. There was no stem loosening. Five hips were revised for osteolysis, cup loosening and polyethylene wear. CONCLUSION: The long term results of total hip arthroplasty using an extensively porous coated stem were acceptable, and there was no case involving the progression of proximal bone resorption.

Risk factors of sagittal decompensation after long posterior instrumentation and fusion for degenerative lumbar scoliosis.

STUDY DESIGN: A retrospective study of clinical results of operative treatment for degenerative lumbar scoliosis. OBJECTIVE: To determine the risk factors of sagittal decompensation after long instrumentation and fusion to L5 or S1. SUMMARY OF BACKGROUND DATA: Little is known about the risk factors for sagittal decompensation, which was defined in this study as sagittal C7 plumb falling anterior >8 cm from the posterosuperior corner of the sacrum. METHODS: Forty-five patients (mean age: 64.4 year) with adult degenerative lumbar scoliosis were reviewed retrospectively with a minimum 2 years. The mean number of levels fused was 6.1 +/- 1.6 segments. The upper instrumented vertebra ranged from T9 to L2. The lower instrumented vertebra was L5 and S1 in 24 and 21 patients, respectively. RESULTS: Sagittal decompensation (SD) developed in 19 patients. The most significant risk factors of SD were preoperative sagittal imbalance and high pelvic incidence. The preoperative sagittal C7 plumb was more positive (67.9 mm) in the decompensation group than in the balance group (37.0 mm) (P = 0.002). There was a significant difference in pelvic incidence between 61.7 degrees in the decompensation and 54.9 degrees in the balance group (P = 0.01). The preoperative lumbar lordosis was hypolordotic in the decompensation group, however, it was not found to be a risk factor. Pseudarthrosis was identified at the lumbosacral junction in 5 patients, and 4 of them (80%) had SD. SD developed in 55% of patients who had loosening of the distal screws and 50% of patients with hypolordotic lumbar fusion. Distal adjacent segment disease was more likely to cause SD than proximal adjacent segment disease. CONCLUSION: Sagittal decompensation is common after long posterior instrumentation and fusion for degenerative lumbar scoliosis. It is mostly associated with complications at the distal segments, including pseudarthrosis and implant failure at the lumbosacral junction. Restoration of optimal lumbar lordosis and secure lumbosacral fixation is necessary especially in patients with preoperative sagittal imbalance and high pelvic incidence in order to prevent sagittal decompensation after surgery.

Complications in posterior fusion and instrumentation for degenerative lumbar scoliosis.

STUDY DESIGN: Radiographic analysis was performed retrospectively. Outcomes and complications were collected prospectively. OBJECTIVES: To assess complications after posterior fusion and instrumentation for degenerative lumbar scoliosis, to determine risk factors of complications, and to analyze the clinical outcomes of surgery. SUMMARY OF BACKGROUND DATA: The complications after degenerative lumbar scoliosis surgery have reported to be high. Risk factors for developing complications are unknown. METHODS: Forty-seven patients (average age, 66.6 years; range, 48-83 years) with degenerative lumbar scoliosis undergoing posterior fusion and instrumentation were analyzed. Seven patients had additional posterior lumbar interbody fusion at the lumbosacral junction. The average number of levels fused was 4.7 +/- 2.2 segments. We evaluated the early perioperative (<3 months after surgery) and late complications. RESULTS: There were 14 early perioperative complications and 18 late complications. There was 1 case of mortality by pulmonary embolism. Early complications included ileus, urinary tract infection, transient delirium, superficial infection, and neurologic deficit. Late complications included adjacent segment diseases, pseudarthrosis, and loosening of screws. Adjacent segment disease developed at the proximal segment in 10 patients and at the distal segment in 5 patients. Pseudarthrosis was noted at the lumbosacral junction in 2 patients. Revision surgery was performed in 7 patients. Older patients (>65 years) had the tendency to increase early complications without statistical difference (P = 0.053). Excessive intraoperative blood loss was the most significant risk factor for the development of early perioperative complications, and number of levels fused was related to blood loss. Operative time and multiple medical comorbidities were not associated with higher complication rate. There were no specific factors related to the development of late complications. CONCLUSION: The complication rate after posterior fusion and instrumentation for degenerative lumbar scoliosis was 68%. Abundant blood loss was a significant risk factor for early perioperative complications. The improvement of Oswestry disability index was less in patients with late complications.

Biologic modification of ligamentum flavum cells by marker gene transfer and recombinant human bone morphogenetic protein-2.

STUDY DESIGN: The study involves an in vitro experiment using human ligamentum flavum (LF), adenovirus lacZ construct (Ad/lacZ), and recombinant human bone morphogenetic protein-2 (BMP-2). OBJECTIVES: To demonstrate the feasibility of marker gene transfer to human LF cells and the effect of BMP-2 on the osteogenic differentiation of human LF cells. SUMMARY OF BACKGROUND DATA: BMP-2 is a widely known pivotal osteoinductive agent. Clinically and experimentally, BMP-2 has proven to be an effective in spinal fusion. Degenerated LF has only been implicated to be of pathophysiological significance in spinal stenosis. However, biologic modifications of LF to enhance osteogenesis have not been attempted previously. MATERIALS AND METHODS: Human LF and cancellous bone from the ilium were harvested from patients with lumbar spinal stenosis. LF cells and osteoblasts were isolated and cultured, and adenovirus lacZ construct (Ad/ lacZ), luciferase construct (Ad/luciferase), and BMP-2 were designed and produced. LF cell cultures were then exposed to various concentrations of Ad/lacZ (25, 50, 75, 100, 150 multiplicity of infection) and BMP-2 (50, 100, 500, 1,000, and 1,500 ng/mL). Osteoblast cultures were used as a positive control for LF culture. LF cell cultures with Ad/luciferase served as viral controls for culture with Ad/ lacZ. The transgene expression of lacZ was assessed by X-gal stain and beta-galactosidase assay. Alkaline phosphatase, Von Kossa, and Alizarin red-S stains were used to confirm osteogenic differentiation and bone nodule formation. Immunocytochemical staining was also performed to detect osteocalcin expression. RESULTS: LF cell cultures transduced with Ad/lacZ showed extensive X-gal expression and increased beta-galactosidase activity compared to viral (Ad/luciferase) and saline controls. In LF cultures treated with BMP-2, robust alkaline phosphatase expression, and bone nodule formations were observed as evidenced by positive Von Kossa and Alizarin red-S staining, and the strong expression of osteocalcin. The osteogenic response of LF cells to BMP-2 was dose dependent. CONCLUSIONS: Human LF cells were found to be susceptible to adenovirus-mediated marker gene transfer, which offers the possibility of a new range of possible genetic modifications. In human LF cells, BMP-2 was found to markedly up-regulate the expression of osteogenic phenotypes and to induce bone nodule formation. The results of this study support the notion that biologically modified LF cells, i.e., LF cells treated with BMP-2, or with adenovirus-mediated BMP-2 cDNA gene transfer, may facilitate spinal fusion.