Radiographic Assessment of Lower Limb Lengthening in Achondroplastic Patients, Using the Ilizarov Frame: A 5-19 Year Follow up Study

Abstract

Background: The effectiveness of the Ilizarov ring fixator in correcting achondroplasia’s lower limb deformities is known. However, whether the long term postoperative result is comparable to normal population standards, has not been analyzed. Materials and Methods: Nineteen (19) achondroplastic patients, 12 males and 7 females, aged 19-38 years, who at the age of 9-19 years, had undergone both tibia and femur lengthening, using the Ilizarov method, were included in the study. Patients were evaluated 5-19 years after their last surgery, using standardized long lower limb anteroposterior and lateral standing radiographs. Tibial and femoral lengthening gain was measured. A comparison between the achondroplastic patients at follow up and comparative radiographic parameters of the normal population was made, concerning– at the frontal plane- LPFA (lateral proximal femoral angle), LDFA (lateral distal femoral angle), MPTA (medial proximal tibial angle), LDTA (lateral distal tibial angle) and MAD (mechanical axis deviation) and – at the sagittal plane- PDFA (posterior distal femoral angle), PPTA (posterior proximal tibial angle) and ADTA (anterior distal tibial angle). Results: Mean angle values at follow up were: LPFA 118, LDFA 95.5, MPTA 87.8, LDTA 93, PDFA 85.1, PPTA 84, ADTA 88.3 while MAD mean value was 28. LPFA, LDFA, LDTA, PPTA, ADTA and MAD values were statistically significantly different (p<0.001) between achondroplastic patients and normal population. Conclusions: The use of the Ilizarov method for lower limb deformity correction, in achondroplastic patients, provides a functional length gain. It substantially corrects the three-dimensional deformities of the disease but, it does not restore the radiological image within normal standards. Level of Evidence Level II, Retrospective Prognostic study.