A chronic pressure ulcer model in the nude mouse.

The pathophysiology of pressure ulcers is not yet fully understood. Widely used experimental models lead to pressure ulcers in the skin and the subcutaneous tissue only. The aim of the present study was to develop a clinically relevant deep pressure ulcer model in nude mice involving all relevant tissue layers. Balb/c nude mice were anesthetized and a steel disk was implanted under the great gluteus muscle. Full recovery was allowed for 10 days. Pressure was then periodically applied (2 hours compression, 1 hour recovery) using a Neodymium magnet in conjunction with the disk in the unanesthetized mouse. Cycles were repeated for 1, 4, 6, 8, or 10 times. Controls underwent the same procedure without placement of the magnet. The pressure ulcer grade was found to be cycle dependent,with the highest degree after 10 cycles. Histological evaluations revealed signs of necrosis in the skin and subcutaneous fat after four, and in the muscle after eight and 10 cycles of compression. Polymorphnuclear granulocyte infiltration in certain layers was found to be dependent on the number of cycles. We conclude that this clinically relevant nude mouse model can be used to investigate the mechanism of pressure ulcer development and to study new therapeutic approaches.

Bilateral lower leg replantation versus prosthetic replacement: long-term outcome of amputation after an occupational railroad accident.

BACKGROUND: This retrospective study investigated three very similar cases of bilateral lower leg amputation. The aim was to determine which of two therapeutical procedures is associated with better long-term outcome: replantation or primary treatment of the stumps and subsequent prosthetic replacement. METHODS: Evaluation included clinical examination, gait analysis, and a workup of the psychosocial background. Health problems were documented using the Nottingham Health Profile. Follow-up assessments were performed 6, 7, and 18 years after the trauma. RESULTS: One patient underwent successful bilateral lower leg replantation and continued to work for the same employer. Two patients underwent prosthetic replacement. One became a social outcast confined to a wheelchair. The other patient had a good psychosocial background, similar to that of the patient who underwent replantation. He showed a better gait analysis on even ground than the replantation patient, but the findings were vice versa for uneven ground. CONCLUSIONS: The decision between replantation and prosthetic replacement after bilateral lower leg amputation is case related and cannot be generalized. Patients who have undergone these procedures require long-term psychological and physiotherapeutic care to achieve a good long-term surgical outcome.