Arthrographic examination of the pseudocapsule of the hip after posterior dislocation of total hip arthroplasty

We examined the pseudocapsule in ten patients with posterior dislocation after total hip arthroplasty (THA) using arthrography to investigate the relationship between dislocation and the state of the pseudocapsule. The pattern of contrast medium pooling demonstrated on tangential views was evaluated. In five patients with early dislocation arthrography showed leakage indicating lack of pseudocapsule whereas there was no leakage in five patients with late dislocation. Repeat arthrography revealed healing of the pseudocapsule could progress by 6–8 weeks after dislocation. These findings suggest that the difference in the pseudocapsule between those who dislocate early and late may explain different clinical outcomes in the two groups.