[Femoral lengthening. A critical review of ten-year results]

To evaluate the results of femoral lengthening in the patients treated from 2000 to 2009 in whom complete radiographic data were available and the lengthening procedure involved mainly the use of a Mephisto fixator.

A total of 28 femoral lengthening procedures were carried out in 26 patients,16 girls and 10 boys. The external fixator Mephisto was used in 24 cases; fixators Prospon and Orthofix in one and three cases, respectively. Fifteen patients were treated for congenital short femur, the rest had secondary femoral shortening due to following pathologies: distal femoral epiphysiolysis in five children, proximal femoral osteomyelitis in one child, avascular necrosis of the femoral head in one, diaphyseal femur fracture in one, enchondromatosis of the distal femur with growth plate destruction in one, and contralateral femur overgrowth following a fracture in one child. The average age at the beginning of treatment was 11 (range, 4-16) years. Complications were classified as mild, serious and critical. The results were statistically analysed using several statistical tests.

The average parameter values for the group included: total femoral lengthening, 40.2.mm (SD±11.1); osteotomy index (OI), 41 % (SD±9.8); lengthening percentage (LP), 10.9 % (SD±3.8); lengthening index (LI), 14.5 (SD±3.5) days/cm; hea- ling index (HI), 52.6 (SD±20.1) days/cm; and consolidation index (CI), 93.3 (SD±40.0) days/cm. Mild complications were recorded in 11 (39.2 %), and serious and critical in eight patients (28.6 %). Fourteen patients (53.8 %) were free of any complications. Two complications were concurrently found in five patients (17.9 %). There was a statistically significant difference in the LP values related to the number of complications (p=0.019). No significant relationship was recorded on comparison of the HI value with the patient's age at the time of surgery (p=0.836) and patient's gender (p=0.546) (Mann- Whitney test). The relationship of the OI value to the HI value was non-significant (p=0.492), as was the relationship between the osteotomy technique (oscillating or Gigli saw osteotomy) and the occurrence of complications (p=1.000) (Fisher's exact test). Correlation between the LI and HI values was significant (p<0.001).

The results of healing after lengthening, as assessed by the healing and the consolidation index, were in agreement with other authors' data. The lower number of complications, particularly fractures of bone regenerate, can be explained by the facts that, in our study, the lengthening percentage was lower and that the post-operative care was strictly observed, including dynamic axial loading which stimulates bone consolidation at the lengthened section, with adherence to the proof of three developed cortices.

Our results did not confirm the assumption that slower lengthening will have a favourable effect on the healing index. Key words: femoral lengthening, external fixator, complications.