Objective To observe the clinical features of polypoidal choroidal vasculopathy (PCV) in Chinese patients.Methods Nine cases (9 eyes ) were examined with fundus examination, fundus fluorescein angiography (FFA) and indocyanine green angiography angiography (ICGA).Results FFA and ICGA showed the branching vascular networks (7 cases) and polyplike dilation at terminals of branches (9 cases), which mainly located in macular area (8 cases) and in peripapillary area (1 case), and which accompanied hemorrhagic or serous pigment epithelial detachment in 7 cases,and 4 of 7 cases had a significant horizontal black-white damarcation line. It definitely differed from fine choroidal neovascularization (CNV).Conclusion PCV in Chinese patients has the cardinal clinical features, i.e., polyplike lesions located mainly in macular area and most cases accompanied by hemorrhagic or serous pigment epithelium detachment. (Chin J Ocul Fundus Dis，2003，19：269-332)
Objective To establish a finite element model of the knee joint based on coronal plane alignment of the knee (CPAK) typing method, and analyze the biomechanical characteristics of different types of knee joints.Methods The finite element models of the knee joint were established based on CT scan data of 6 healthy volunteers. There were 5 males and 1 female with an average age of 24.2 years (range, 23-25 years). There were 3 left knees and 3 right knees. According to the CPAK typing method, the knees were rated as types Ⅰ to Ⅵ. Under the same material properties, boundary conditions, and axial loading, biomechanical simulations were performed on the finite element model of the knee joint. Based on the Von Mises stress nephogram and displacement nephogram, the peak stresses of the meniscus, femoral cartilage, and tibial cartilage, and the displacement of the meniscus were compared among different types of knee joints. Results The constructed finite element model of the knee joint was verified to be effective, and the stress and displacement results were consistent with previous literature. Under the axial load of 1 000 N, the stress nephogram showed that the stress distribution of the medial and lateral meniscus and tibial cartilage of CPAK type Ⅲ knee joint was the most uneven. The peak stresses of the lateral meniscus and tibial cartilage were 9.969 6 MPa and 2.602 7 MPa, which were 173% and 165% of the medial side, respectively. The difference of peak stress between the medial and lateral femoral cartilage was the largest in type Ⅳ knee joint, and the medial was 221% of the lateral. The displacement nephogram showed that the displacement of the medial meniscus was greater than that of the lateral meniscus except for types Ⅲ and Ⅵ knee joints. The difference between medial and lateral meniscus displacement of type Ⅲ knee joint was the largest, the lateral was 170% of the medial. Conclusion In the same type of joint line obliquity (JLO), the medial and lateral stress distribution of the knee was more uniform in varus and neutral positions than in valgus position. At the same time, the distal vertex of JLO subgroup can help to reduce the uneven medial and lateral stress distribution of varus knee, but increase the uneven distribution of valgus knee.
Mobile-bearing unicompartmental knee arthroplasty (UKA) is prone to rotational malalignment of the femoral component. Moreover, existing biomechanical studies frequently overlook the mechanical impact of patients’ bone quality on such surgical errors. To investigate the coupling effect of femoral component transverse rotation and bone quality on the biomechanical environment, a finite element model incorporating intact soft tissues was constructed. Based on bone mineral density variations, three models were established: normal bone (B1), osteopenia (B2), and osteoporosis (B3). Nine rotational conditions ranging from –14° to 14° in the transverse plane were simulated. Quantitative analysis revealed that external rotation significantly elevated the contact pressure on the polyethylene liner. Conversely, internal rotation (–14°) increased the lateral meniscus stress by approximately 16.8% compared to the neutral alignment (0°) via a “linkage mechanism”. Group B3 exhibited a pseudo “cushion effect”, wherein the peak strain of the tibial cancellous bone reached 5 883.9 με, exceeding the pathological threshold of 4 000 με; additionally, compared with Group B1, their average strain in the cortical bone increased by approximately 79.7%. In conclusion, transverse rotational malalignment of the femoral component serves as a direct mechanical trigger disrupting the biomechanical balance in UKA, and osteoporosis significantly amplifies this risk of failure. Therefore, for patients with compromised bone mass, strict neutral alignment must be pursued intraoperatively to circumvent cancellous bone microfractures and early prosthesis subsidence.
Objective To discuss operative strategies of posterior deformity vertebra resection and instrumentation fixation in the treatment of congenital scol iosis or kyphoscol iosis in child and adolescent patients, and to evaluate the surgicalresults. Methods From May 2003 to December 2007, 28 patients with congenital scol iosis or kyphoscol iosis were treatedwith one stage posterior deformity vertebra resection. There were 11 males and 17 females with an average age of 9.6 years (1.5-17.0 years). The locations were thoracic vertebra in 13 cases, thoracolumbar vertebra in 10 cases, and lumbar vertebra in 5 cases. All the patients underwent one stage posterior deformity vertebra resection, fusion and correction with pedicle instrumentation. According to different types of deformities, the patients underwent three different surgeries: hemivertebra resection (13 patients), hemivertebra resection combined contralateral unsegmental resection (7 patients), and total vertebral column resection (8 patients). Based on short or long segmental pedicle instrumentation, deformities were corrected and fixed, in 7 patients with short segmental fixation (group A), in 13 patients with long segmental fixation with hemivertebra resection or combined contralateral unsegmental resection (group B), and in 8 patients with long segmental fixation with total vertebral column resection (group C). The operative duration and the volume of blood loss were recorded, and the correction rate was calculated through measurement of Cobb angles of scol iosis and kyphosis before and after operation. Results The operation time of groups A, B, and C was (98 ± 17), (234 ± 42), and (383 ± 67) minutes, respectively, and the blood loss during operation was (330 ± 66), (1 540 ± 120), and (4 760 ± 135) mL, respectively; showing significant differences among three groups (P lt; 0.05). All patients achieved one-stage heal ing of incision. No deep infection, respiratory failure or deep vein thrombosis occurred. One patient had the signs of ischemical reperfusion injury of spinal cord 6 hours after operation and recovered after 2 weeks of relative therapy in group C; no neurological compl ication occurred in other patients. The mean follow-up period was 32.8 months (24-72 months). Intervertebral rigid fusion was identified from radiological data 6 months after operation according to contiguous callus crossed intervertebral gap and maintenance of correction results. No instrumentation failure occurred. There were significant differences in the Cobb angle between before and after operations (P lt; 0.01). There were significant differences in the corrective rate of scol iosis between groups A, B and group C (P lt; 0.05). Meanwhile, there were significant differences in the corrective rate of kyphosis between groups A, C and group B (P lt; 0.05). Conclusion One-stage posterior deformity vertebra resection has a good capabil ity of correcting congenital scol iosis or kyphoscol iosis on coronal and sagittal plane rel ied on removal deformity origin. It is important to select appropriated strategies on deformity resection and segmental fixation according to different ages and deformity situations of patient.
Objective To invest igate the ef fect iveness and signi f icance of percutaneous endoscopic discectomy followed by interbody fusion using B-Twin expandable spinal spacer for degenerative lumbosacral disc disease. Methods Between January 2007 and August 2008, 21 patients with degenerative lumbosacral disc disease were treated with endoscopic discectomy followed by interbody fusion using B-Twin expandable spinal spacer. Among them, there were 13 males and 8 females with an average age of 52 years (range, 28-79 years). And the disease duration ranged from 3 months to 40 years (median, 9 months). The affected segments included T11, 12, T12-L1, L1, 2, and L2, 3 in 1 case respectively, L4, 5 in 4 cases, and L5, S1 in 13 cases. All patients had intractable low back pain or lower extremity radicular symptoms. The placement methods of B-Twin expandable spinal spacer were double sides in 15 cases and single side in 6 cases. Oswestry Disabil ity Index (ODI) and Macnab grading were used to determine the function recovery after operation. And Suk’s standard was used to determine the fusion effects by X-ray. Results All 21 patients were followed up 18 months to 3 years (mean, 23.8 months). Sciatica symptoms disappeared after operation in 19 cases, no significant improvement occurred in 2 cases of thoracic disease. The ODI scores were 79% ± 16% at preoperation, 30% ± 9% at 1 month, 26% ± 10% at 3 months, 21% ± 12% at 6 months, and 20% ± 10% at 18 months after operation, showing significant differences between pre- and postoperation (P lt; 0.05). According to Macnab grading at 6 months postoperatively, the results were excellent in 14 cases, good in 5 cases, and fair in 2 cases with an excellent and good rate of 90.5%. According to Suk et al. standard, the results were excellent in 1 case, good in 19 cases, and poor in 1 case with an excellent and good rate of 95.2%. The muscle strength of the lower extremities had no improvement in 1 case of T11, 12 disc protrusion; pedicle screws fixation and decompression laminectomy were given after 6 months, but no improvement was achieved during follow-up. Protrusion recurred after 4 months in 1 case of L4, 5 disc protrusion, then was cured by laminectomy discectomy. The remaining patients achieved postoperative rel ief. Conclusion Endoscope combined with interbody fusion is a good combination to solve lumbar instabil ity. B-Twin expandable spinal spacer is a minimally invasive fusion choice of L4, 5 and L5, S1.