Constrained tripolar acetabular liner effective in patients with high risk of dislocation: Study

The study is published in the Journal of Orthopaedics.

A.Derksen and colleagues carried out the present study with the aim to determine number and type of failures and revisions after usage of a constrained tripolar acetabular liner in patients with high risk of dislocation. Potential correlations between these failures and the factors included were analyzed.

With constrained liners, restricted range of motion (ROM) is responsible for impingement leading to high likelihood of failure, depending on the design, with various failure modes.

In this retrospective study 55 participants in 68 cases were included after treatment with constrained tripolar acetabular liner. Patient specific data as well as surgery and implant specific data were collected. Radiological images were assessed. Furthermore, the gluteal function was analyzed. The parameters were statistically verified with regard to their influence on the failure of the constrained tripolar liner.

The results showed that-

1. This study included 16 cases (in nine participants) of postoperative failure.
2. This results in a survival rate of 76.5% regarding the number of cases after 17 months.
3. The statistical analysis of the different parameters considered that the number of previous surgeries has a significant (p = 0.027) influence on the failure.

Hence, the authors concluded that "this retrospective study shows that treatment with constrained tripolar acetabular liners is a satisfactory method of treatment in cases with a high risk of dislocation.

However, they further inferred that in cases with an increasing number of previous surgeries, an increased risk of failure was found. Therefore, in such cases, this type of supply treatment should be treated critically."