Reverse on-top plasty in mutilating hand injuries.

For crushing injury of the hand that involves 4-digit amputations sparing the thumb, lengthening of amputated stump and covering the defect are important for hand function. From March 2007 to September 2011, the authors performed "reverse on-top plasty" in 5 patients. The fifth metacarpal bone was disarticulated, turned over 180 degrees, and embedded in reverse direction so that the metacarpal base becomes the tip of new finger. Soft tissue defects were covered using anterolateral thigh free flap or reverse radial forearm flap. The mean follow-up period was 21.2 months, and major complications such as bony resorption did not occur. Static 2-point discrimination showed fair recovery of fingertip sense. Key pinch power was 76.4% of the uninjured hand. In conclusion, reverse on-top plasty is good in gaining more sufficient finger length and durability using cartilaginous portion of the fifth metacarpal bone than the previously used on-top plasty.