Biomedical subjects

Wen-Jer Chen

Publications and source records attributed to Wen-Jer Chen.

At least 37 records · Page 2Linked to original sources

PubMed2004

Relation between laminectomy and development of adjacent segment instability after lumbar fusion with pedicle fixation.

STUDY DESIGN: A retrospective study of 101 patients who had undergone posterolateral lumbar fusion, to analyze the association between adjacent instability and the extent of laminectomy. OBJECTIVES: To investigate the hypothesis that the integrity of the posterior complex (spinous process/supraspinous ligament/spinous process) between the fused segments and the neighboring motion segments significantly influences lumbar spine stability. SUMMARY OF BACKGROUND DATA: Spinal fusion with pedicle fixation accelerates the degeneration of adjacent motion segments. The lowest cranial motion segment is the most common level for the development of adjacent instability. Laminectomy, including removal of the spinous process, supraspinous ligament, interspinous ligament, lamina and ligamentum flavum, jeopardizes the integrity of the posterior complex of the spine. METHODS: This study enrolled 101 patients, followed up for at least 6 years, who had been treated with posterolateral lumbar fusion with pedicle fixation because of lumbar spondylolisthesis. The diagnosis of adjacent instability depended on the dynamic lateral views of the lumbosacral spine during each follow-up. The integrity of the posterior complex was based on the extent of laminectomy and the fusion level. RESULTS: At the cranial adjacent motion segment, 2 of 31 (6.5%) patients with preserved posterior complex integrity between the fused segment and motion segment developed adjacent instability, compared with 17 of 70 (24.3%) without preserved posterior complex integrity. At the caudal adjacent motion segment, none of 13 patients (0%) with preserved integrity developed adjacent instability, compared with 3 of 54 (5.6%) without preserved integrity. CONCLUSIONS: Damaging the integrity of the posterior complex between the fused segments and the neighboring motion segments may jeopardize lumbar spine stability. Sacrificing either the supraspinous ligament or the tendon insertion points on the spinous processes leads to an accelerated development of adjacent instability.

Adult↗

PubMed2004

Serious pyogenic spondylitis following vertebroplasty--a case report.

STUDY DESIGN: The aim of this case report is to examine the problem of serious pyogenic spondylitis that may follow vertebroplasty. OBJECTIVES: To report 1 case of serious pyogenic spondylitis caused by percutaneous vertebroplasty with polymethyl methacrylate. SUMMARY OF BACKGROUND DATA: Serious pyogenic spondylitis caused by percutaneous vertebroplasty with polymethyl methacrylate is a rare complication. We herein report a case of pyogenic spondylitis that occurred after the patient had undergone vertebroplasty. METHODS: A 78-year-old woman with a T12 osteoporotic compression fracture, and without a magnetic resonance imaging sign of infection, underwent percutaneous vertebroplasty using polymethyl methacrylate without complication. RESULTS.: About 1 month after the operation, the patient was readmitted because of severe backache, and the diagnosis of pyogenic spondylitis was made using radiograph and magnetic resonance imaging. Anterior inter-body fusion with a strut bone graft after debridement and posterior instrumentation were then performed. CONCLUSIONS: Vertebroplasty should proceed under sterile conditions. Excluding the possibility of spinal infection before surgery and a detailed evaluation assuring that the patient is without systemic infectious disease before the vertebroplasty procedure is crucial.

Abscess↗

PubMed2004

Arthroscopic anterior cruciate ligament reconstruction with periosteum-enveloping hamstring tendon graft.

Tendon-bone incorporation of a tendon graft within the bone tunnel is of priority concern when using for anterior cruciate ligament (ACL) reconstruction. Superior healing process and stronger healing strength can be achieved when periosteum is sutured on the tendon inserted into a bone tunnel. We applied this idea to ACL reconstruction for enhancing tendon graft-bone tunnel healing. This is a prospective clinical outcome study with this surgical technique at minimal 2 years follow-up. Periosteum-enveloping hamstring tendon graft has been used in 68 patients. Data from 62 patients who had been followed up completely were analyzed. All patients suffered from a grade 3 or higher grade of Lachman and anterior drawer test with a positive pivot-shift test. Clinical assessments included the Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, KT-1000 instrumented testing, thigh muscle assessment, and radiographic evaluation. The median Lysholm knee score was 59 (40-70) and 94 (60-100) points (P<0.01) before and after surgery. After reconstruction, 81% of patients were able to return to moderate or strenuous activity. Four (6%) patients were found to exhibit grade 2 or more ligament laxity. Complete range of motion could be achieved in 86% of patients. Three patients (5%) had positive pivot shift. Finally, 92% of patients were assessed as normal or nearly normal rating by IKDC guideline. Bone tunnels enlargement of more than 1 mm was identified in 5% of femoral tunnels and 6% of tibial tunnels. The study shows that a satisfactory result can be achieved with the periosteum-enveloping hamstring tendon graft in ACL reconstruction. Periosteum can be easily harvested at the proximal tibia from a routine incision for hamstring tendon harvesting. Besides the potential for improving tendon-bone healing, enveloped periosteum may help to seal the intra-articular tunnel opening in the early postoperative period, and thus avoid synovial fluid reflux into the tunnel. Bone tunnel enlargement could be reduced.

Adolescent↗

PubMed2004

Tibial inlay technique with quadriceps tendon-bone autograft for posterior cruciate ligament reconstruction.

Surgical reconstruction of the posterior cruciate ligament (PCL) is indicated in a PCL-deficient knee with symptomatic instability and injury to other ligaments. However, the choice of graft tissues remains controversial. The tibial inlay method has the benefit of preventing the acute turn associated with transtibial reconstruction and permitting accurate anatomic placement of the graft. This study describes an arthroscopic-assisted inlay technique for PCL reconstruction using quadriceps tendon-patellar bone autograft. This technique is a reasonable alternative for PCL reconstruction.

Arthroscopy↗

PubMed2004

Double-bundle posterior cruciate ligament reconstruction using inlay technique with quadriceps tendon-bone autograft.

Surgical reconstruction of the posterior cruciate ligament (PCL) is indicated in a PCL-deficient knee with symptomatic instability and multiple ligament injuries. The results of the traditional tunnel method for PCL reconstruction remain uncertain. The tibial inlay method offers the benefit of preventing the acute-turn associated with transtibial reconstruction. Additionally, the double-bundled graft appears to restore normal knee laxity across the full range of flexion. This study presents an inlay technique for arthroscopic PCL reconstruction with double-bundled quadriceps tendon-patellar bone autograft. This technique offers a reasonable alternative for PCL reconstruction.

Arthroscopy↗

PubMed2004

The effect of sagittal alignment on adjacent joint mobility after lumbar instrumentation--a biomechanical study of lumbar vertebrae in a porcine model.

BACKGROUND: The mechanisms and changes in range of motion of neighboring mobile segment (adjacent level) after the instrumented posterior stabilization are not completely understood. This study aims to investigate the effect of sagittal alignment on the adjacent joint mobility after lumbar instrumentation. METHODS: Eight fresh porcine lumbar spines were instrumented with pedicle screw implants from L2 to L4. Each specimen was tested in three different sagittal alignments. Group A were instrumented in lordotic alignment (lordosis 20 degrees ), Group B in straight alignment (lordosis 0 degrees ), and Group C in kyphotic alignment (kyphosis 20 degrees ). Hydraulic testing machine was used to generate an increasing moment in flexion and extension respectively for each specimen. The vertebral displacement of the disc between L1-L2 and L4-L5 were measured simultaneously with an extensometer. FINDINGS: There were no significant differences in vertebral displacement between the three different sagittal alignments in both the superior and inferior adjacent segments under extension motion. However, under flexion motion, the vertebral displacement on the superior adjacent segment (L1-L2) with kyphotic alignment was statistically larger than that of the straight and lordotic alignments (P = 0.0198 and P = 0.000473 respectively), and no differences were found between the three different sagittal alignments on the inferior adjacent segment (L4-L5). INTERPRETATION: The iatrogenically produced kyphotic lumbar spine by posterior instrumentation might cause larger adjacent joint mobility on the superior adjacent joint as compared to the instrumented lordotic lumbar spine. This study implies that an instrumented spine in lordosis is less likely to develop adjacent instability than a kyphotic spine.

Animals↗

PubMed2004

Computer-assisted fluoroscopic navigation of pedicle screw insertion: an in vivo feasibility study.

BACKGROUND: Accurate placement of pedicle screws is difficult. PATIENTS AND METHODS: We evaluated the feasibility and accuracy of pedicle screw insertion assisted by a real-time, 2-dimensional (2D) image-guided navigation system in 12 patients who underwent thoraco-lumbar and/or lumbar stabilization. 66 pedicle screws were inserted either by senior spine surgeons or residents. The accuracy of positioning of the screws was evaluated using postoperative plain radiographs and thin-cut CT. RESULTS: 61 of the 66 screws were inserted successfully. 5 screw insertions showed structural violations: 4 on the medial and 1 on the lateral pedicle wall. The accuracy was higher in the sagittal plane than in the axial plain. There was no difference between the surgical error rates caused by the senior surgeons and the residents. INTERPRETATION: Using computer-assisted 2D fluoroscopic image navigation, it is possible to achieve reliable and accurate pedicle screw insertion during low thoracic and lumbar spinal surgery.

Adult↗

PubMed2004

Effect of postoperative lumbar sagittal alignment on the development of adjacent instability.

OBJECTIVE: This study investigated the effect of postoperative lumbar sagittal alignment on the development of adjacent segment instability. METHODS: The patients were retrospectively divided into two groups (hypolordotic and hyperlordotic) using the lumbar lordosis on lateral lumbosacral view. Diagnosis of adjacent segment instability depended on the dynamic lateral views of the lumbosacral spine. RESULTS: Thirteen (21.7%) cases developed adjacent segment instability during the 6-year follow-up. The two groups had no significant difference in rates of developing adjacent segment instability. CONCLUSION: Restoring the lordosis of the lumbar curve during one motion segment fusion does not prevent the development of adjacent instability.

Aged↗

PubMed2004

Arthroscopic posterior cruciate ligament reconstruction with quadriceps tendon autograft: minimal 3 years follow-up.

BACKGROUND: Various autografts or allografts have been used for posterior cruciate ligament (PCL) reconstruction. Quadriceps tendon-patellar bone autograft is considered a good graft choice. HYPOTHESIS: Quadriceps tendon-patellar bone graft for PCL reconstruction can achieve a satisfactory clinical outcome after 3 years postoperatively. STUDY DESIGN: Retrospective review of prospectively collected data. METHODS: From 1996, the graft has been used in 32 patients. Twenty-nine patients with a minimum of 3 years of follow-up were analyzed. RESULTS: Twenty-four (83%) patients achieved good or excellent results by Lysholm knee rating. Sixteen (55%) patients could return to moderate or strenuous activity. Twenty-five (86%) patients had ligament laxity of less than 5 mm. Twenty-four (83%) patients were rated as normal or nearly normal by International Knee Documentation Committee (IKDC) guidelines. Twenty-four (83%) and 26 (90%) patients could achieve recovery of extensor and flexor muscle strength to 80% or more of normal knee, respectively. A statistically significant difference exists in thigh girth difference, extensor strength, and flexor strength before and after reconstruction. CONCLUSION: Our study revealed satisfactory clinical subjective and objective results at a minimum 3 years follow-up. Quadriceps tendon autograft has the advantage of being self-available, a relatively easier arthroscopic technique, and having a suitable size, making it an acceptable graft choice for PCL reconstruction.

Adult↗

PubMed2004

Intervertebral disc herniation in adolescents.

BACKGROUND: The purpose of this study was to review surgery-proven lumbar disc herniation in adolescents with an emphasis on the distinguishing features. METHODS: Twenty-eight adolescents between 14 and 18 years old had lumbar discectomy after conservative treatment for 9 months. Indications for surgery were intractable pain and failure of conservative treatment for more than 6 weeks. Lumbar spine apophyseal ring fracture was found in 10 of the 24 patients (42%) who had computed tomography studies. Seven patients had piecemeal excision of the fractured apophysis together with the discectomy. RESULTS: All but three patients could raise their leg more than 70 degrees after the operation. The latest follow-up was conducted an average of 6.1 years after surgery. Good or excellent results were noted in 93% of the patients. Two patients had follow-up operations for recurrent disc herniation and wound infection. CONCLUSION: Apophyseal ring fracture was a feature in adolescent disc herniation that requires surgical intervention. Early computed tomography study is proposed to detect apophyseal ring lesion, which may lead to failure of conservative treatment. Excision of the fractured ring apophysis is suggested in addition to discectomy when the canal space is occupied.

Adolescent↗

PubMed2004

Leiomyoma of the hand mimicking a pearl ganglion.

Leiomyomas rarely occur in the hand. To our knowledge, there have been no reports of a leiomyoma of the hand mimicking a pearl ganglion in the English literature. We report such a case with a leiomyoma of the right third finger in a 59-year-old woman. The tumor was excised together with the underlying sheet of tissue. The pathology revealed that the tumor was linked to the underlying structure of a vascular wall by a stalk of tumor tissue. This report serves to remind clinicians to include leiomyoma in the differential diagnosis when encountering a 'ganglion-like lesion'. Also, this report demonstrates the link between a leiomyoma and its underlying origin.

Diagnosis, Differential↗

PubMed2004

Minimally invasive treatment of osteoporotic vertebral compression fracture.

BACKGROUND: The use of percutaneous vertebroplasty (PV) to treat osteoporotic vertebral fractures is increasing. This investigation assesses the efficacy and safety of PV for refractory pain owing to osteoporotic vertebral compression fractures. METHODS: A retrospective investigation of PV was conducted with a minimal of 1 year follow up. PV with polymethylmethacrylate (PMMA) was performed on 75 patients with osteoporotic vertebral compression fractures that responded poorly to the conservative therapy. Patients were asked to quantify their degree of pain using Huskisson's visual analogue scale to assess the clinical results. RESULTS: Eighty-seven vertebrae treated using PV in 70 patients were evaluated with a minimal of 1 year follow up. Pain, as assessed on the VAS, decreased from 80+/-16 mm before PV to 36+/-28 mm at 1 month after PV and 30+/-19 mm at the most recent follow up. The reduction in pain from the baseline to 1 month (p=0.031) and to final follow up (p=0.023) were both statistically significant. Sixty-two patients (85.5%) quickly returned to their pre-injury activity level and achieved better quality of life. CONCLUSIONS: PV is effective in pain reduction for painful vertebral compression fractures. It provided significant pain relief. Skillful techniques and careful safeguards can minimize the risks of PMMA migration.

Aged↗

PubMed2004

Anterior cervical spinal surgery for multilevel cervical myelopathy.

BACKGROUND: In multilevel spinal cord compression caused by cervical spondylosis, surgeons face the choice of performing a posterior route as a laminectomy or laminoplasty, or an anterior route as multiple adjacent interbody decompressions or corpectomies. The anterior cervical operation is not considered by some clinicians because of concerns about complications and the complexity of multilevel anterior cervical surgery. METHODS: In this retrospective study, 14 patients with multilevel cervical spondylosis who were operated on via an anterior route were enrolled to evaluate the complexity, safety, and clinical results. The collected parameters were operation time, blood loss, hospital days, and early and late complications for evaluating the operative complexity, radiographic follow-up for evaluating fusion, graft problems, implants problems, and the recovery rate using the Japanese Orthopaedic Association score (JOA score) for evaluating the operative results. RESULTS: The mean operation time was 363.4 min, and blood loss was 431.4 ml. An early complication was noted in 1 patient with combined deep vein thrombosis and a pulmonary embolism. Late complications were screw breakage in 1 patient and screw loosening in 5 patients. The mean duration of follow-up was 21.9 months. The mean recovery rate of the JOA score was 38.8% postoperatively and 51.9% at the final follow-up. The fusion rate was 100% in this series. CONCLUSIONS: Anterior cervical decompression and fusion for multilevel stenosis requires a longer operation time than posterior procedures; however, the clinical results are satisfactory.

Adult↗

PubMed2004

Recurrent giant cell tumor of the thoracic spine with bilateral pulmonary metastases.

Giant cell tumor (GCT) of bone is a challenging clinicopathologic entity. Despite its benign designation, it has the capacity to recur locally and develop rare pulmonary metastasis. We report a case of histologically proven recurrent GCT of the spine (T7-8) involving spinal cord compression, direct extension to 1 lung, and bilateral pulmonary metastases. A 30-year-old woman presented with back pain, and underwent anterior reconstruction for GCT of the T7 at another hospital. As her symptoms deteriorated, she underwent laminectomy at the same hospital 2 months after the first surgery. One year after the first surgery, she was referred to our hospital on account of a progressive neurological deficit and intractable back pain, and underwent an anterior tumor resection at T7-8 and reconstruction, due to tumor recurrence. Postoperatively, the patient did not show neurologic improvement, but her pain decreased. The patient displayed no respiratory difficulties and no apparent change in follow-up chest radiographs for more than 2 years since surgery. This is the first reported case of bilateral pulmonary metastases from GCT of the thoracic spine.

Adult↗

PubMed2004

Posterior decompression and stabilization for metastatic spine diseases.

BACKGROUND: The purpose of this study was to investigate the clinical results of posterior decompression and stabilization for metastatic diseases of the thoracolumbar spine. METHODS: From 1980 to 2001, 70 consecutive patients with spinal metastases underwent palliative surgery by posterior decompression of spinal cord and subsequent stabilization with instrumentation. There were 38 women and 32 men. Their ages ranged from 24 to 75 years (mean 58 years). We retrospectively reviewed medical records to analyze their survival, clinical presentations, image findings and surgical outcomes. RESULTS: Sixty-one patients (87%) survived longer than 3 months. Forty-nine patients (70%) survived longer than 6 months, of whom 35 patients were still alive at an average of 24 months (range 13-40 months) after surgery. All maintained spinal stability postoperatively. Forty-seven of 60 patients (78.3%) with severe pain obtained significant symptomatic relief for 3 months or more, and 38 of 54 (70.1%) paralyzed patients gained neural improvement. Of the 60 patients bedridden before surgery due to pain or paresis, 36 patients (60%) experienced an increase in activity tolerance. CONCLUSIONS: The results of this study shows that neurological recovery, pain relief and mobility can be enhanced by posterior decompression and stabilization in highly selective patients with spinal metastases.

Adult↗

PubMed2004

Magnetic resonance imaging characteristics of benign and malignant vertebral fractures.

BACKGROUND: Attempts to differentiate benign and malignant vertebral fractures may be difficult, particularly when there is no obvious evidence of malignancy. Since early diagnosis and appropriate management of malignant vertebral fractures are important, a reliable imaging modality is required. METHODS: From January 1996 to December 2002, 48 patients with malignant vertebral fractures and 50 patients with benign processes were studied. All patients underwent conventional magnetic resonance imaging (MRI) scanning for acute vertebral compression fractures within 2 months of presenting with the complaint. Seven MRI characteristics were used as criteria, including signal intensity, gadolinium enhancement, epidural compression, multiple compression fractures, associated paraspinal soft tissue mass, pedicle involvement, and posterior element involvement. The predictive value of each MRI characteristic for distinguishing malignant from benign osteoporotic vertebral fractures was tested by statistical analysis. RESULTS: Lesions with negative gadolinium enhancement were favored as benign fractures. A uniform signal change in multiple involved vertebra lesions, round, smooth margins with marked epidural compression, a paraspinal soft tissue mass, and pedicle and posterior element involvement were probable malignant characteristics. Among them an associated paraspinal soft tissue mass was found to be significant in predicting the probability of malignancy. CONCLUSIONS: Certain MRI characteristics allow early differentiation of benign and malignant vertebral fractures.

Adult↗

PubMed2003

Polymethylmethacrylate cement dislodgment following percutaneous vertebroplasty: a case report.

STUDY DESIGN: A case report is presented. OBJECTIVES: To report a rare complication of delayed cement displacement following percutaneous vertebroplasty. SUMMARY OF BACKGROUND DATA: Although percutaneous vertebroplasty is considered a minimally invasive procedure, it may result in several complications. To our knowledge, this is the first report of delayed cement displacement after percutaneous vertebroplasty. METHODS: A 69-year-old man with T12 osteoporotic compression fracture received percutaneous vertebroplasty. One month after surgery, the patient complained of progressive severe back pain, and roentgenographic image revealed a breakdown of the anterior cortex of the T12 vertebral body with anterior displacement of the bone cement. RESULTS: The complication was solved by one stage anterior and posterior operation: thoracoabdominal approach with removal of the displaced cement and posterior instrumentation from T11 to L1. The severe back pain with associated weakness improved after surgery. CONCLUSIONS: This complication is rare and likely to occur in treatment of osteoporotic vertebral fracture with avascular necrosis and anterior cortical defect.

Aged↗

PubMed2003

Fixation strength of three different graft types used in posterior cruciate ligament reconstruction.

Surgical reconstruction is generally recommended for PCL and associated ligament injuries. A variety of graft choices exist for PCL reconstruction surgery. This study evaluated the initial fixation strength of three grafts using in PCL reconstruction in a porcine model. Twenty fresh porcine knees were harvested and randomly assigned to four groups: bone-patellar tendon-bone graft, quadruple tendons graft, Achilles tendon graft, and normal PCL. After reconstruction the knee was tested on an MTS testing machine by translating the tibia posteriorly until failure at 30 degrees of flexion, neutral rotation, and anatomical vertical alignment. Biomechanical parameters including maximal failure load, stiffness, and failure modes, were analyzed and compared. In the maximal failure load, the four-strand tendon group was significantly greater than the other two grafts. However, it had greatest translation. There were no significant differences between the three grafts in stiffness. All three of these commonly used grafts had weaker initial fixation strength and stiffness than normal PCL. Graft failure occurred mainly at the tendon-bone junction and tendon-suture sites. The Patellar tendon group had significantly least translation during continuing loading.

Animals↗