H Simpson, Hisham Shalaby (Edinburgh, Royaume Uni)
Femoral lengthening using the Intramedullary Skeletal Kinetic Distractor (ISKD) is a new alternative technique to the standard method of lengthening using external fixation that carries the advantage of reducing the potential risk of infection and allowing more patient comfort. However, with a completely internal lengthening device such as the ISKD, the surgeon has less control over the lengthening process.
The study included 25 femora, with a mean shortening of 46 mm, for which femoral lengthening was performed using the ISKD. The aim was to assess the effect of different operative variables that the surgeon could control on the course of femoral lengthening and to correlate these variables with the incidence of uncontrolled-lengthening and failure of lengthening.
The desired length was achieved in 24 out of 25 limbs. Problems encountered included difficulty in achieving lengthening in 8 patients and uncontrolled lengthening in 5 patients. Our results showed a statistically significant (p<0.05) correlation between having 125 mm or more of the thick portion of the nail in the distal fragment and difficulty in achieving lengthening. The results also showed a statistically significant correlation between having 80 mm or less of the thick portion of the nail in the distal fragment and uncontrolled lengthening (p<0.05). This study suggest that problems encountered during this technique can be minimized by positioning of the osteotomy to allow more than 80 mm but less than 125 mm of the thick proximal portion of the ISKD in the distal fragment and by over-reaming 2.5 to 3.0 mm. The patients had early return of limb function; specifically knee flexion and weight bearing. We consider the ISKD to be an excellent new tool for the armamentarium of the trauma & orthopaedic surgeon.