[Tönnis and Kalchschmidt triple pelvic osteotomy]

With three precise osteotomies it is possible to move the acetabulum to achieve sufficient coverage in dysplastic hips.

Main indication is a painful dysplastic hip. Other acetabular pathologies, such as retroversion can also be addressed. In recent years young patients with Legg-Calve-Perthes disease

Patients with an arthrosis (Tönnis level 2) and obesity often have poor results. Therefore the combination of these parameters should be seen as a contraindication.

The operation starts with the patient in a lateral decubitus position. The first incision is parallel to the sacrotuberal ligament. The gluteus maximus muscle is spread until the ligament itself with its bony connection at the tuber ischiadicum is visible. After putting two special retractors in the foramen obturatorium and one to the spina ischiadica, osteotomy of the os ischium is performed from the incisura ischiadica to the foramen obturatorium. For the next osteotomy the os pubis is approached and it should be performed subperiostally. The vasa and nervus obturatorius and femoralis should be protected. At the os ilium the abdominal muscles are separated from the iliac crest. The third osteotomy has a 90° angle and starts at the linea terminalis and leads just below the spina iliaca anterior superior iliac spine. The acetabulum can now be moved with a Schanz screw. At this point it is necessary to elevate the os pubis while moving the acetabulum laterally. This prevents a lateralization and reduces the distance at the iliac osteotomy. The osteosynthesis is performed with screws at the os ilium and also at the os pubis.

Patients are advised to avoid weight bearing for 12 weeks. In the first 6 weeks they are allowed to perform a maximum flexion of 60°.

According to the Harris hip score 80.4 % of the patients showed good and very good results after 11.5 years. In cases with arthrosis and obesity a higher rate of poor results were found.