Proximal Tibial Open Wedge Osteotomy. A Clinical Prospective, Randomized RSA-trial.

In the treatment of osteoarthritis of the medial compartment of the knee, Open wedge high tibial osteotomy is a good choice of treatment for the young and active patient.

However it leaves an open gap which has to be filled with a bone substitute and requires stable fixation.

Hitherto the golden standard has been autograft taken from iliac crest but there are donorsite related problems and limited amount available.

Recently injectable and resorbable calciumphosphate-cements have been introduced and used with promising results in fractures of the distal radius, calcaneus and lateral tibial condyle.

These new cements seem to be a good alternative to other bone substitutes providing high initial strength that might promote early mobilisation; it resorbs and promotes osteoconduction securing safe healing.

The aim of the present study is to evaluate whether there is any difference in clinical outcome, correction, stability and healing in open-wedge osteotomies with three different bone substitutes: Autograft from iliac crest and the injectable calciumphosphate-cement Calcibon and as control a group with an empty gap.

Osteosynthesis is performed with the Dynafix® system (EBI) The investigation is performed as a randomised prospective clinical trial including 45 patients with a planned 2 years follow-up period.

Clinical outcome is evaluated with: Hospital of special surgery score, KOOS, SF 12 and Lysholm score.

Routine standing x-rays is performed. Stability is assessed with Roentgen Stereophotogrammetric Analysis (RSA) that provides the opportunity of exact 3-dimensional measuring of eventual loss of correction.

This combined with urine and serum bone-healing markers gives a very precise picture of the healing in the bone-gap.

To asses the cartilage of the knee MRI is performed and biochemical markers fore Collagen type II degradation are measured.