Mo Sha

Voltage-gated potassium channel Kv1.3 is highly expressed in human osteosarcoma and promotes osteosarcoma growth.

Deregulation of voltage-gated potassium channel subunit Kv1.3 has been reported in many tumors. Kv1.3 promotes tumorigenesis by enhancing cell proliferation while suppressing apoptosis. However, the expression and function of Kv1.3 in osteosarcoma are unknown. In the present study, we detected the expression of Kv1.3 in human osteosarcoma cells and tissues by RT-PCR, Western blot and immunohistochemistry. We further examined cell proliferation and apoptosis in osteosarcoma MG-63 cells and xenografts following knockdown of Kv1.3 by short hairpin RNA (shRNA). We found that Kv1.3 was upregulated in human osteosarcoma. Knockdown of Kv1.3 significantly suppressed cell proliferation and increased apoptosis as demonstrated by enhanced cleavage of poly (ADP-ribose) polymerase (PARP) and the activation of Caspase-3/7. Furthermore, adenovirus delivered shRNA targeting Kv1.3 significantly inhibited the growth of MG-63 xenografts. Taken together, our results suggest that Kv1.3 is a novel molecular target for osterosarcoma therapy.

A minimally invasive anterior approach to reduction and screw fixation of coronoid fractures

We investigated a minimally invasive anterior approach to reduce and fix coronoid fractures with a screw in eight consecutive patients and evaluated seven patients at a minimum of 1 year (mean, 78 weeks; range, 61–89 weeks). It was only possible to repair seven of eight coronoid fractures. The average time to radiographic healing was 12 weeks and all healed without the screw loosening, migration or breakage. Endoscopy permitted an excellent view of coronoid fractures, allowing anatomic fixation, and as it avoided extensive soft tissue dissection, this method preserved soft tissue attachments of small coronoid fragments. This method was safe and minimally invasive.

A BIOMECHANICAL STUDY OF SHEAR LOAD ON BONE–SCREW INTERFACE OF THORACOLUMBAR VERTEBRAE

Vertebral screw failure by cutting through or pulling out of the vertebral body is common in intraoperative and postoperative stages of anterior thoracolumbar surgery, especially in osteoporotic patients. This biomechanical study was conducted to investigate the maximum shear force thoracolumbar vertebrae can withstand and the corresponding displacement of screws and analyze their correlation with vertebral bone mineral density. Forty individual vertebra specimens (T11-L3) were obtained from eight fresh adult cadaveric thoracolumbar spine specimens and randomly divided into an experimental group and a control group. Screws were placed in the center point of vertebrae and penetrated the contralateral cortex. Shear loading and axial pullout tests were conducted on the experimental group while only axial pullout test was conducted on the control group. The maximum shear forces and maximum axial pullout forces were recorded. The conditions of vertebral body destruction and screw channel were observed and the maximum axial pullout forces were recorded and analyzed. A large amount of thread bone debris was observed in the control group. In the experimental group, however, only a small amount of thread bone debris was observed; the widths of screw paths were larger than those in the control group and gradually increased from screw tips in the direction of loading. The vertebral bodies had an average shear strength of 536.63±82.99N, and the corresponding average screw displacement was 8.79±1.08mm. Linear regression analysis showed that the shear strength had a significant positive correlation with vertebral bone mineral density (BMD) (r=0.958, P 0.05); the difference in maximum axial pullout strength between the destruction and the control groups was significant (P<0.01). These results indicated that vertebral BMD positively correlated with the maximum shear force and negatively with the screw displacement. It is important that the corrective strength for spinal deformity may affect bone–screw interface in anterior thoracolumbar surgery.

Biomechanical Study Comparing a New Combined Rod-plate System With Conventional Dual-rod and Plate Systems

Most anterior spinal instrumentation systems are designed as either a plate or dual-rod system and have corresponding limitations. Dual-rod designs may offer greater adjustability; however, this system also maintains a high profile and lacks a locking design. Plate systems are designed to be stiffer, but the fixed configuration is not adaptable to the variety of vertebral body shapes. The authors designed a new combined rod-plate system (D-rod) to overcome these limitations and compared its biomechanical performance with the conventional dual-rod and plate system. Eighteen pig spinal specimens were divided into 3 groups (6 per group). An L1 corpectomy was performed and fixed with the D-rod (group A; n=6), Z-plate (Sofamor Danek, Memphis, Tennessee) (group B; n=6), or Ventrofix (Synthes, Paoli, Pennsylvania) (group C; n=6) system. T13-L2 range of motion was measured with a 6 degrees of freedom (ie, flexion-extension, lateral bending, and axial rotation) spine simulator under pure moments of 6.0 Nm. The D-rod and Ventrofix specimens were significantly stiffer than the Z-plate specimens (P<.05) based on results obtained from lateral bending and flexion-extension tests. The D-rod and Z-plate specimens were significantly stiffer than the Ventrofix specimens (P<.05) in axial rotation. The D-rod combines the advantages of the plate and dual-rod systems, where the anterior rod exhibits the design of a low-profile locking plate, enhanced stability, and decreased interference of the surrounding vasculature. The posterior rods function in compression and distraction, and the dual-rod system offers greater adjustability and control over screw placement. The results indicate that it may provide adequate stability for anterior thoracolumbar reconstruction.

Design and Biomechanical Properties of a New Reconstruction Device for Treating Thoracolumbar Burst Fractures

Implants currently used for reconstruction of a burst vertebral body are associated with complications, including subsidence, nonunion, and substantial intraoperative blood loss. A new reconstruction device, the U-Cage (Double Engine Medical Material Ltd, Xiamen, Fujian, China), was designed to minimize complications.Six intact adult cadaver thoracolumbar (T11-L3) spines were collected and scanned by dual-energy X-ray absorptiometry (DEXA). The stiffness of the burst spine was subsequently compared with its previous intact state during flexion/extension, lateral bending, and rotation, and then subjected to a cyclic test to predict cage subsidence and device loosening. Axial load was applied continuously until failure to test the peak load that the specimen could withstand during the cyclic test. The correlation of bone mineral density and peak load was also analyzed. The instrumented specimens were found to be equivalent to intact bone in all directions (P>.05), with the exception of left rotation (P<.05). All specimens could withstand the cyclic test, and no subsidence or loosening of the device was detected. Average peak load for the instrumented specimens was 4137.5 N, which correlated with the average bone mineral density (r=0.915; P=.011).Thoracolumbar burst fractures instrumented with a U-Cage and anterolateral D-rod fixation achieved a stiffness similar to that of intact spines. This procedure may avoid the subsidence of the cage in vivo and serve as a better option for treating thoracolumbar burst fractures.

Early results of thoraco lumbar burst fracture treatment using selective corpectomy and rectangular cage reconstruction

Background: Subsidence and late fusion are commonly observed in anterior subtotal corpectomy and reconstruction for treating thoracolumbar burst fractures. The subsidence rate of this surgical method was reported from 19.6% to 75% in the literatures, which would cause treatment failure. Thus, an improvement of anterior surgery technique should be studied to reduce these complications. Materials and Methods: 130 patients of thoracolumbar burst fractures treated by minimal corpectomy, decompression and U cage, between January 2009 and December 2010 were included in this study. The hospital Ethical Committee approved the protocols. The American Spinal Injury Association (ASIA) scale, visual analog scales, and Oswestry Disability Index (ODI) scores were used for clinical evaluation. The local kyphosis angle, vertebral height (one level above the fractured vertebral to one level below), canal stenosis, and fusion status were used to assess radiological outcome. All complications and demographic data such as number of male/female patients, average age, mode of trauma, burst level involved, mean surgery time and blood lost were reported. Results: 120 patients were followed up for 24 months. Most patients had improvement of at least 1 ASIA grade, and all experienced pain reduction. The mean ODI score steadily decreased after the surgery (P < 0.01). Approximately, 83.3% of patients achieved solid fusion at 3 months and reached 98.3% at 6 months. The kyphosis angle and radiographic height were corrected significantly after the surgery and with a nonsignificant loss of correction at 24 months (P > 0.05). The average canal stenosis index was increased from 39% to 99% after surgery. No cage subsidence or implant failure was observed. Conclusions: The clinical outcomes described here suggest that the selective corpectomy and rectangular cage reconstruction can effectively promote solid fusion and eliminate complications related to subsidence or implant failure.

Cementless arthroplasty with a distal femoral shortening for the treatment of Crowe type IV developmental hip dysplasia

Background: Severe developmental dysplasia of the hip is a surgical challenge. The purpose of this study is to describe the cementless arthroplasty with a distal femoral shortening osteotomy for Crowe type IV developmental hip dysplasia and to report the results of this technique. Materials and Methods: 12 patients (2 male and 10 female) of Crowe type IV developmental hip dysplasia operated between January 2005 and December 2010 were included in the study. All had undergone cementless arthroplasty with a distal femoral shortening osteotomy. Acetabular cup was placed at the level of the anatomical position in all the hips. The clinical outcomes were assessed and radiographs were reviewed to evaluate treatment effects. Results: The mean followup for the 12 hips was 52 months (range 36-82 months). The mean Harris hip score improved from 41 points (range 28-54) preoperatively to 85 points (range 79-92) at the final followup. The mean length of bone removed was 30 mm (range 25-40 mm). All the osteotomies healed in a mean time of 13 weeks (range 10-16 weeks). There were no neurovascular injuries, pulmonary embolism or no infections. Conclusion: Our study suggests that cementless arthroplasty with a distal femoral shortening is a safe and effective procedure for severe developmental dysplasia of the hip.

Anterior D-rod and titanium mesh fixation for acute mid-lumbar burst fracture with incomplete neurologic deficits: A prospective study of 56 consecutive patients.

Background: Anterior decompression and reconstruction have gained wide acceptance as viable alternatives for unstable mid-lumbar burst fracture, but there are no mid and long term prospective studies regarding clinical and radiologic results of mid-lumbar burst fractures. Materials and Methods: An Institutional Review Board-approved prospective study of 56 consecutive patients of mid-lumbar burst fractures with a load-sharing score of 7 or more treated with anterior plating was carried out. All patients were evaluated for radiologic and clinical outcomes. The fusion status, spinal canal compromise, segmental kyphotic angle (SKA), vertebral body height loss (VBHL), and adjacent segment degeneration was examined for radiologic outcome, whereas the American Spinal Injury Association scale, the visual analog scale (VAS), and the employment status were used for clinical evaluation. Results: The patients underwent clinical and radiologic followup for at least 5 years after the surgery. At the last followup, there was no case of internal fixation failure, adjacent segment degeneration, and other complications. Interbody fusion was achieved in all cases. The average fusion time was 4.5 months. No patient suffered neurological deterioration and the average neurologic recovery was 1.3 grades on final observation. Based on VAS pain scores, canal compromise, percentage of VBHL and SKA, the difference was statistically significant between the preoperative period and postoperative or final followup (P < 0.05). Results at postoperative and final followup were better than the preoperative period. However, the difference was not significant between postoperative and final followup (P > 0.05). Thirty-four patients who were employed before the injury returned to work after the operation, 15 had changed to less strenuous work. Conclusion: Good mid term clinicoradiological results of anterior decompression with D-rod and titanium mesh fixation for suitable patients with mid-lumbar burst fractures with incomplete neurologic deficits can be achieved. The incident rate of complications was low. D-rod is a reliable implant and has some potential advantages in L4 vertebral fractures.