Fracture neck of femur in severe coxa-vara – Challenging management in an Achondroplasia patient

Abstract

Achondroplasia is a skeletal dysplasia of autosomal dominant inheritance. Fibroblast growth factor receptor 3 mutation at p16.3 locus of chromosome 4 leads to inhibition of sub-chondral growth. Middle aged achondroplastic patient with left fracture neck of femur following a fall of heavy object. It was a challenging case because of coxa-vara and meticulous templating is needed. 38 year old male sustained fracture neck of left femur in severe coxa-vara. Closed reduction with 16 mm partially threaded cannulated cancellous screw perpendicular to native neck- shaft angle. At regular follow up, mild lysis was seen around the screw and implant removal was done. Now with neck of femur non-union, walking full weight bearing with walker. The future course included excision arthroplasty or custom made prosthesis. Achrondroplasia characterised by defects in en-chondral bone formation leading to retarded cartilage growth. Literature search on peri-articular fracture management showed peadiatric disatal femur fracture fixed with percutaneous screws. In adult, neck of femur fracture is managed by percutaneous screw, DHS or prosthesis. Due to altered geometry of proximal femur DHS and Prosthesis was deferred.Early failure of CC screws in our case is due to perpendicular placement of screws which increased strain due to altered bio-mechanics. Achondroplastic dwarfs live a normal life. They are prone to peri-articular fractures because of anatomical variations. We wanted to highlight the difficulties and importance of pre-op planning and implant choice of fracture fixation in an adult achondroplasia patient.