TOTAL HIP REPLACEMENT IN DWARFS

Abstract

Introduction and Aims: Genetic defects causing dwarfism occur in approximately one in 10,000 live births. There are over 200 types, with achondoplasia, spondyloepiphyseal dysplasia, diastrophic dwarfism and hypopituitarism being the most common. Another frequent cause of short stature is juvenile rheumatoid arthritis. Most types of dwarfism result in arthrosis of major joints, resulting in significant disability. Hip replacement can offer significant improvement in quality of life, but there are inherent difficulties due to size and anatomic variations.

Method: Short stature of less than 4 feet 10 inches was defined as dwarfism. Eight patients meeting this criterion underwent total hip replacement, either primary or revision, with six being bilateral, resulting in a total of 14 hips for study. The diagnoses were: two JRA, two Mucolipdosis III, one Dyastrophic Dwarfism, one Spondyloepiphyseal Dysplasia, one Thalasemia, and one Congenital Rickets. In each case, a CT-based custom cementless femoral component was used. The patients were followed prospectively with the Harris hip scale and serial radiographs. Average follow-up was nine years (two to 14).

Results: The average total Harris hip score improved from 35 pre-operatively to 66 at last follow-up, with the average Harris pain score increasing from 10 to 31 (out of a maximum of 44). Five hips have been reoperated: two for combined acetabular and femoral loosening, one for acetabular loosening, one for recurrent dislocation and one for late hematogenous infection.

Conclusions: Hip replacement in dwarfs presents a complex technical challenge, but can result in significant improvement in pain, function and quality of life. CT-based custom femoral components are recommended.