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Background Osteonecrosis of the femoral head (ONFH) is an important indication for total hip arthroplasty in Taiwan. We demonstrated the etiologies of ONFH and outcomes based on stratification of patients according to different etiologies. Methods We reviewed medical records and images from January 2000 to May 2010 in our database with the diagnosis of “osteonecrosis of the femoral head.” We categorized all patients into different etiologies, including corticosteroid, alcohol, and idiopathic. All patients received subsequent follow up for ipsilateral precollapse ONFH and contralateral disease-free femoral head status after initial diagnosis. Results Of the 1153 patients who had undergone 1674 hip surgeries including core decompression and total hip replacement, alcohol use was the most prevalent etiology in our population (45.2%). Patients with corticosteroid- and alcohol-associated ONFH were younger and more likely to have bilateral disease. Patients with alcohol- or steroid-associated ONFH were found to have a higher rate of contralateral disease and faster progression of precollapse ONFH than patients who had or had not undergone core decompression. Conclusion Alcohol use had the greatest impact on ONFH in our population. Nonidiopathic ONFH patients had the worst outcome. Understanding the nature of progression of ONFH and incidence of contralateral disease may provide great prognostic value to detect and perform early intervention.

This is a retrospective study carried out to evaluate the clinical results of patients with osteoporosis and various spinal diseases treated surgically with polymethylmethacrylate (PMMA)-augmented cannulated pedicle screws, and to compare this method with the needle injection technique in terms of the clinical results and fixation strength.To report a technique using PMMA-augmented cannulated pedicle screws for fixation in osteoporotic spines and to compare its clinical results and biomechanical characteristics with the needle injection technique.Many studies have shown that PMMA-augmented pedicle screws can significantly increase the stiffness and strength of the screw. Various designs of cannulated screws have been used for cement augmentation in experimental studies; however, clinical reports using these screws in osteoporotic patients are rare. A practical and reliable technique and optimal screw design have not yet been established.Forty-five patients (23 women, 22 men), mean age of 71.37 years (range, 53-94 y), with osteoporosis and various spinal diseases underwent spinal decompression and instrumentation with PMMA augmentation of cannulated pedicle screws. Preoperative and postoperative visual analog scale scores for pain and the Oswestry disability index questionnaire data were analyzed. Screw migration, which is the distance from the screw tip to the anterior cortex and the upper endplate of the vertebra, was also evaluated immediately after surgery and at the mean follow-up of 15.9 months. These clinical results were then compared with those reported for the needle injection technique. The pullout strength, insertional, and backout torque of these 2 techniques were compared using osteoporotic synthetic bone (0.12 g/cm).A total of 255 out of 283 cannulated screws were augmented with PMMA. The mean visual analog scale pain score of these patients improved from 9.5 to 3.1 (P0.01) and the functional Oswestry disability index score improved from 71% to 28.9% (P0.01). Kyphotic deformity of the compression fracture group (19 patients) was improved from an average of 9.38 to 3.27 degrees after surgery, and to 5.45 degrees at the final follow-up (P0.01). There was no significant vertical screw migration when the screws' distances were compared just after the operation and at the final follow-up (P0.01). However, significant horizontal screw migration was found in lesions below the L2 level (P0.01). There was no major neurovascular injury, except in 1 patient, who had persistent left thigh pain due to cement leakage at the L1 level, and the symptom was controlled with analgesics. The clinical results of both techniques were satisfactory and there were no significant differences. Although the pullout strength and screw backout torque was significantly higher in the needle injection group (234.1 vs. 187.8 N, 1119.6 vs. 836.7 N mm, respectively), the operation time was shorter and the cement leakage rate was less in the cannulated pedicle screw group than that of the needle injection group (211.4 vs. 296.3 min, 14.05% vs. 26.2%, respectively).The technique of cannulated pedicle screws with PMMA augmentation used in this study can be an option for osteoporotic patients with various spinal diseases who require spinal instrumentation.

Osteoblastoma occurring in the region of the hip is very rare, and vague symptoms with uncharacteristic radiographic features often lead to misdiagnosis. Because of radiographic and histological similarities, it must be carefully distinguished from osteoid osteoma, aneurysmal bone cyst, giant cell tumor, and osteosarcoma. Computed tomography is the preferred imaging modality as it is able to detect the nidus and images will not exhibit the flare phenomenon caused by surrounding inflammation seen with magnetic resonance imaging. For hip joint lesions in weight-bearing areas, intralesional curettage may achieve satisfactory outcomes as compared with wide resection. We herein report two cases of osteoblastoma in the hip region in which diagnosis was delayed that were successfully treated with curettage and followed by high-speed burring.

Study design A single-institution, single-surgeon retrospective review. Objective To evaluate the clinical results of long posterior instrumentation with short posterior or posterolateral fusion for pyogenic spondylodiscitis of the thoracic and lumbar spine retrospectively. Summary of background data There are controversies concerning the optimal treatment for pyogenic spondylodiscitis, in terms of approach, grafting, and instrumentation. Reports of long posterior fixation with short fusion without debridement of infected tissue for pyogenic spondylodiscitis are rare. Methods From June 1997 to June 2007, 48 patients with pyogenic spondylodiscitis were treated. The indications for surgery were neurological compromise, significant vertebral body destruction with kyphosis and segmental instability, failure of medical treatment, and the need for tissue diagnosis. All patients received long posterior instrumentation with or without posterior decompression, depending on whether the patients had neurological deficit. During operation, no debridement of infected tissue was done. Clinical outcomes were assessed using the criteria of Kirkaldy-Willis and the visual analogue scale for pain. The neurological outcome was graded using Frankel grading system. Segmental kyphotic angle and fusion were recorded and analyzed. Results The average follow-up time was 64 months. The visual analogue scale scores improved from an average of 7.2 before surgery to 2.2 after surgery. Twenty-eight patients with initial neurological impairment had an average improvement of 1.03 grades, using the Frankel grading system, at the final follow-up. The segmental kyphotic deformity improved by an average of 8.5° immediately after operation and lost an average correction of 3.0° at the final follow-up. No relapse of infection was found among these 48 patients. Conclusion The posterior approach with long segmental fixation and short posterior or posterolateral fusion without debridement of the infected tissue was effective for pyogenic spondylodiscitis of the thoracic and lumbar spine.

Study design A finite element analysis to simulate the behavior of lumbar spines implanted with a posterior dynamic neutralization system, Dynesys, under displacement-controlled loading. Objective To investigate whether Dynesys spacers with different diameters would alter the distribution of range of motion, disk stress, and facet contact force at the Dynesys bridging level and the cranial adjacent level. Summary of background data The Dynesys system is designed to preserve intersegmental motion and reduce loading at adjacent levels, but clinical reports do not support these claims. This system has been shown to be almost as stiff as rigid fixation, which acts to hinder intersegmental motion. Few studies have investigated methods of reducing this stiffness. Methods In the finite element study, a previously validated lumbar spine model was used. Five Dynesys constructs with different spacer diameters (0.8, 0.9, 1.0, 1.1, and 1.2 times the original standard size) were implanted into the spine model and bore 4 displacement-controlled loading cases: flexion, extension, torsion, and lateral bending. Resultant range of motions (ROMs), disk stress, and facet contact forces at the bridged level and the cranial adjacent level were compared with the results of a spine model without Dynesys implantation. Results The results of ROMs, disk stress, and facet contact forces at the bridged levels were all less than those in the intact spine, except for contact forces at the left facet under lateral bending, facet contact forces at the right facet under torsion, and disk stress under torsion. The results of ROMs, disk stress, and facet contact forces at the cranial adjacent levels were all higher than those in the intact spine. Conclusions The results of the present study show that changing the diameter of the spacers will alter the stiffness of the Dynesys construct. Dynesys constructs with larger diameters behave stiffer under flexion but behave softer under extension, torsion, and lateral bending. Changing the diameter of the Dynesys spacers does not significantly influence the load distribution at adjacent levels.

The current treatment methods for diffuse intraarticular or extraarticular type pigmented villonodular synovitis (PVNS) include arthroscopic synovectomy or staged anterior and posterior open synovectomies. However, it is unclear whether simultaneous anterior and posterior synovectomies achieve local control and recovery of function.We therefore determined the recurrence rate and function in patients with diffuse PVNS treated with anterior and posterior synovectomies and adjuvant radiotherapy.We retrospectively reviewed all 19 patients with diffuse PVNS involving the knee treated with anterior and posterior synovectomies and adjuvant radiotherapy between January 2001 and November 2007. From the records, we determined local recurrence and Tegner-Lysholm scores. The minimum followup was 42 months (median, 98 months; range, 42-143 months).Postoperative MRI revealed residual tumor in five of the 19 patients, although three had no disease progression during followup and had knee scores of 86 to 90. Two patients had recurrences at 6 and 9 months with knee scores of 88 at 42 months and 90 at 68 months. The mean Tegner-Lysholm knee score improved from 59 to 93 points. Mean maximum extension and flexion angles improved from 11° to 2° and from 76° to 127°, respectively.Compared with the literature, simultaneous anterior and posterior synovectomies associated with postoperative radiotherapy provided rates of residual or recurrent tumor and knee function recovery comparable to that with staged synovectomies reported in the literature.Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Displacement-controlled finite element analysis was used to evaluate the mechanical behavior of the lumbar spine after insertion of the Dynesys dynamic stabilization system.This study aimed to investigate whether different depths of screw placement of Dynesys would affect load sharing of screw, range of motion (ROM), annulus stress, and facet contact force.In clinical follow-up, a high rate of screw complications and adjacent segment disease were found after using Dynesys. The pedicle screw in the Dynesys system is not so easy to implant into the standard position and causes the screw to protrude more prominently from the pedicle. Little is known about how the biomechanical effects are influenced by the Dynesys screw profile.The Dynesys was implanted in a 3-dimensional, nonlinear, finite element model of the L1 to L5 lumbar spine. Different depths of screw position were modified in this model by 5 and 10 mm out of the pedicle. The model was loaded to 150 N preload and controlled the same ROMs by 20, 15, 8, and 20 degrees in flexion, extension, torsion, and lateral bending, respectively. Resultant ROM, annulus stress, and facet contact force were analyzed at the surgical and adjacent level.Under flexion, extension, and lateral bending, the Dynesys provided sufficient stability at the surgical level, but increased the ROM at the adjacent level. Under flexion and lateral bending, the Dynesys alleviated annulus stress at the surgical level, but increased annulus stress at the adjacent level. Under extension, the Dynesys decreased facet loading at the surgical level but increased facet loading at the adjacent level.This study found that the Dynesys system was able to restore spinal stability and alleviate loading on disc and facet at the surgical level, but greater ROM, annulus stress, and facet loading were found at the adjacent level. In addition, profile of the screw placement caused only a minor influence on the ROM, annulus stress, and facet loading, but the screw stress was noticeably increased.

A retrospective study to evaluate the clinical results of patients with osteoporosis and various spinal diseases treated surgically with polymethylmethacrylate (PMMA) augmented pedicle screw.To report a novel technique using PMMA for pedicle screw augmentation in osteoporotic spinal surgery.Many studies have proved that the stiffness and strength of pedicle screw fixation can be significantly increased when the pedicle screw is augmented with various cements. However, most of those studies were experimental. Clinical reports using those materials for pedicle screw augmentation are rare and a practical and reliable technique for primary pedicle screw augmentation with cement has not yet been established.Forty-one patients [23 female, 18 male, mean age 75.1 (50-90) years] with osteoporosis and various spinal diseases underwent spinal decompression and instrumentation with PMMA augmentation of pedicle screw. Pre-and postoperative scores for visual analogue scale for pain and Oswestry disability index questionnaire were analyzed. The screw migration, which is the distance from the screw tip to the anterior cortex and upper endplate of vertebra, was also evaluated immediately after the operation and at the mean 22.3 months final follow-up. RESULTS.: Totally 291 of 300 screws were augmented with PMMA. There was neither neurologic deterioration nor symptomatic cement leakage after surgery. The mean visual analogue scale pain score of these patients improved from 9.2 to 1.5 (P0.01) and the functional Oswestry disability index score improved from 77.5% to 44.2% (P0.01). Kyphotic deformity was improved from average 23.2 degrees to 11.9 degrees after surgery, and to 14.9 degrees at final follow-up (P0.01). The average loss of kyphosis correction was 3 degrees. There was no significant screw migration when the screws distances just after operation and at the final follow-up were compared (P0.01).The presented technique of PMMA for augmentation of pedicle screw is a safe, reliable, and practical technique for osteoporotic patients who also had various spinal diseases and need spinal instrumentation.

Study design A prospective clinical trial was conducted. Objectives To compare the results of fusion versus nonfusion for surgically treated burst fractures of the thoracolumbar and lumbar spine. Summary of background data The operative results of surgically treated burst fractures with short segmental fixation have been well documented. There is no report comparing the results of fusion and nonfusion. Methods Fifty-eight patients were included in this study, with the inclusion criteria as follows: neurologically intact spine with a kyphotic angle > or = 20 degrees, decreased vertebral body height > or = 50% or a canal compromise > or = 50%, incomplete neurologic deficit with a canal compromise 50%, complete neurologic deficit, and multilevel spinal injury or multiple traumas. All patients were randomly assigned to fusion or nonfusion groups, and operative treatment with posterior reduction and instrumentation was carried out. Posterior fusion with autogenous bone graft was performed for the fusion group (n = 30), and no fusion procedure was done for the nonfusion group (n = 28). The average follow-up period was 41 months (range, 24-71 months). Results The average loss of kyphotic angle was not statistically significant between these 2 groups. The radiographic parameters were statistically significantly better in the nonfusion group, including angular change in the flexion-extension lateral view (4.8 degrees vs. 1.0 degrees), lost correction of decreased vertebral body height (3.6% vs. 8.3%), intraoperative estimated blood loss (303 mL vs. 572 mL), and operative time (162 minutes vs. 224 minutes). The scores on the low back outcome scale were not statistically significant for these 2 groups. Conclusions The short-term results of short segmental fixation without fusion for surgically treated burst fractures of the thoracolumbar spine were satisfactory. The advantages of instrumentation without fusion are the elimination of donor site complications, saving more motion segments, and reducing blood loss and operative time.

Study design We retrospectively compared magnetic resonance images (MRIs) of tuberculous (TB) spondylitis and pyogenic spondylitis. Objective To identify differences between the diseases. Summary of background data Clinical and imaging findings of the 2 diseases are hard to distinguish. MRI may show important differences and aid in early diagnosis and treatment. Methods We compared 22 MRI parameters in 33 patients with TB spondylitis (average age, 66 years) and in 33 patients with pyogenic spondylitis (average age, 65 years). Results Seventeen parameters significantly differed between the groups. The most important were local and heterogeneous enhancement of the vertebral body in all patients with TB spondylitis, diffuse and homogeneous enhancement of the vertebral body in 94% of patients with pyogenic spondylitis, vertebral intraosseous abscess with rim enhancement (TB vs. pyogenic, 79% vs. 0%), disc abscess with rim enhancement (9% vs. 64%), and well-defined paraspinal abnormal signal intensity (82% vs. 18%). Conclusions Most parameters occurred in both diseases. Distinctive findings were a pattern of bone destruction with relative disc preservation and heterogeneous enhancement for TB spondylitis and a diskitis pattern (disc destruction) with peridiscal bone destruction and homogeneous enhancement for pyogenic spondylitis. These MRI parameters may facilitate the differential diagnosis of these diseases.

Study design Prospective, single-blinded, randomized study. Objectives To evaluate the efficacy of dilute betadine irrigation of spinal surgical wounds in prevention of postoperative wound infection. Summary and background Deep wound infection is a serious complication of spinal surgery that can jeopardize patient outcomes and increase costs. Povidoneiodine is a widely used antiseptic with bactericidal activity against a wide spectrum of pathogens, including methicillin-resistant Staphylococcus aureus. The aim of this study was to evaluate the efficacy of dilute betadine solution in the prevention of wound infection after spinal surgery. Methods Four hundred and fourteen patients undergoing spinal surgery were randomly assigned to two groups. In group 1 (208 patients), surgical wounds were irrigated with dilute betadine solution (3.5% betadine) before wound closure. Betadine irrigation was not used in group 2 (206 patients). Otherwise, perioperative management was the same for both groups. Results Mean length of follow-up was 15.5 months in both groups (range, 6-24 months). No wound infection occurred in group 1. One superficial infection (0.5%) and six deep infections (2.9%) occurred in group 2. The differences between the deep infection rate (P = 0.0146) and total infection rate (P = 0.0072) were significant between the two groups. Conclusions Our report is the first prospective, single-blinded, randomized study to evaluate the clinical effectiveness of dilute betadine solution irrigation for prevention of wound infection following spinal surgery. We recommended this simple and inexpensive measure following spinal surgery, particularly in patients with accidental wound contamination, risk factors for wound infection, or undergoing surgery in the absence of routine ultraviolet light, laminar flow, and isolation suits.

STUDY DESIGN A multisegmental cadaveric spine model was used to quantify the load-displacement behavior of intact spine specimens, specimens injured and stabilized using Bagby and Kuslich (BAK) cages as lumbar interbody fusion devices with or without posterior instrumentation across two levels. OBJECTIVES To compare the stabilities imparted by the cages placed using an oblique and conventional posterior approaches and to determine the effects of supplementary posterior instrumentation. SUMMARY OF BACKGROUND DATA The BAK cage as posterior lumbar interbody fusion (PLIF) has been used to restore disc height, reduce morbidity, provide immediate stability to the patients, and enhance fusion rates. The obliquely inserted BAK cage has the advantages of reducing exposure and precise implantation. The biomechanical efficacy of this procedure is sparse, especially in comparison to the PLIF with and without posterior instrumentation. METHODS Nine fresh human ligamentous spines (L2-S1) were affixed within a testing frame for determining their load-displacement behaviors. Load testing in clinically relevant modes was performed sequentially for the intact and the following procedures across the L4-S1 segment: posterior destabilization, stabilization using two parallel BAK cages (CBAK group) or one oblique BAK cage (OBAK group), further stabilization with posterior instrumentation, and finally cyclic loading in flexion-extension. Spatial positions of the LEDs attached to vertebral bodies were recorded using a three-dimensional motion measurement system. RESULTS When used alone to restore stability, the orientation of the cage affected the outcome. In flexion OBAK orientation and in extension CBAK orientation provided better stability (decrease in motion with respect to intact case), compared with the other orientation. In lateral bending, CBAK orientation was found to be better than OBAK. In axial mode, CBAK orientation was effective in both directions while OBAK was effective only in right axial rotation. With the supplementary posterior fixation, the differences in stability resulting from the orientations were not noticeable at all, both before and after cyclic tests. CONCLUSIONS Owing to the differences in the surgical approach and the amount of dissection, the stability for the cages when used alone as a function of cage orientation was different. These subtle differences were reduced by the use of posterior fixation device, underscoring the importance of using instrumentation when cages are used as PLIFs. However, the oblique insertion may be more favorable since it requires less exposure, enables precise implantation, and is less expensive, especially when used with supplementary instrumentation.