Objective To observe the changes of force bearing area and pressures of the rabbit tibiofemoral contact area and the biomechanical reconstruction level of joint after meniscal allograft. Methods A total of 28 Japanese rabbits were involved, weighing 3.0-3.5 kg, male or female. Of 28 rabbits, 7 were selected as meniscus donors, the remaining 21 rabbits were randomized into group A (n=7), group B (n=7), and group C (n=7). Group A underwent single knee opening and suturing, group B underwent medial meniscus excision and suturing, and group C underwent medial meniscus allograft after medial meniscus excision and suturing. The rabbits were sacrified at 12 weeks after operation for biomechanical observation through biomechanical machine and color imaging system. The meniscus tissue specimens were harvested from groups A and C to perform histological and immunohistochemical staining. Results After operation, all rabbits in 3 groups survived to the end of experiment. There were significant differences in the force bearing area and pressures at 0-90° flexion between group B and groups A, C (P lt; 0.05) at 12 weeks, showing no significant difference between group A and group C (P gt; 0.05); and there were significant differences in the force bearing area and pressures at 120° flexion among 3 groups (P lt; 0.05). The histological observation showed that the number of cartilage cells and collagen fibers returned to normal in group C, and the immunohistochemical staining showed that transplanted meniscus of group C contained large amounts of collagen fibers consisting of collagen type I and collagen type II. After 12 weeks of operation, the collagen type I contents were 0.612 5 ± 0.059 8 in group A and 0.587 2 ± 0.063 9 in group C, showing no significant difference (t=0.765, P=0.465); the collagen type II contents were 0.772 4 ± 0.081 5 and 0.814 3 ± 0.051 7, respectively, showing no significant difference (t= —0.136, P=0.894). Conclusion The allograft of rabbit meniscus can significantly increase the force bearing area of the tibiofemoral contact area and reduce the average pressure. Therefore, biomechanically speaking, the meniscus allograft can protect the articular cartilage and reconstruct the biomechanical balance.
Objective To investigate the cl inical effect of vacuum seal ing drainage (VSD) on late-stage large skin avulsion injury with infection. Methods From May 2007 to August 2008, 9 patients with large-area skin avulsion injury and infection were treated. There were 1 male and 8 females aged 9-52 years old (median 27 years old). All patients suffered from closed skin avulsion injury involving the lower back, buttock, and part of the thigh. The injury area varied from 30 cm × 25 cm to92 cm × 38 cm. The time between injury and hospital admission was 15-23 days. The skin avulsion injury was compl icated with pelvis fracture, urethral injury, anal injury, sacrum exposure, and l imb fractures. The interval between hospital admission and operation was 3-23 hours. Free spl it-thickness skin graft was performed after the focus debridement and three VSD treatments (40-60 kPa). Results After three VSD treatments, no patient had general pyemia and severe local tissue necrosis or infection, the tissue edema in the skin avulsion area was alleviated obviously, and all the wound cavities were closed. All the wounds in the graft site healed after 28-45 days of treatment (average 39 days), and all the donor sites healed. Nine patients were followed up for 4-14 months (average 10 months). The appearance of the reparative area was good, and there was no occurrence of joint dysfunction in the injured area due to scar contracture. Conclusion VSD is effective in treating late-stage large skin avulsion injury with infection.