Results of hip arthrodesis in adolescents by using the cobra-head plate for internal fixation

A retrospective study was conducted to examine the efficacy and potential morbidity of hip fusion using the Cobra-head plate in adolescents. A heterogeneous group of 11 adolescents, with recalcitrant hip pain and an average age of 14.6 years, underwent unilateral hip arthrodesis with the Cobra-head plate for internal fixation. Seven (64%) patients achieved an uneventful clinical and radiographic arthrodesis after a mean postoperative interval of 7.4 months. Four index operations (36%) were complicated by pseudarthrosis. All patients who developed a postoperative pseudarthrosis ranked at or above the 90th percentile for their age-determined weight. The relationship between the percentile-weight-for-age and the incidence of pseudarthrosis was statistically significant (p < or = 0.001). Hip-arthrodesis procedures with the Cobra-head plate in adolescents at or above the 90th percentile weight-for-age are associated with an unacceptably high rate of pseudarthrosis. In this subset of patients, alternate or supplementary stabilization methods should be considered.