gms | German Medical Science

Questionnaire: Biomechanical data demonstrate a higher fixation stability of a plate fixator compared to a spacer plate for the fixation of an open-wedge high tibial osteotomy (HTO). There are no in vivo data quantifying and comparing the fixation stability of different HTO implants. As a consequence, surgeons customize the rehab protocol to the projected fixation stability of their implant leaving us with numerous different rehab protocols. In this prospective 24-subject clinical trial, fixation stability was quantified over a 2- year period using radiostereometric analysis (RSA).

Methods: Patients were assigned to two treatment regimens: a spacer plate with 6 postoperative weeks of feather-touch weight bearing versus a plate fixator with 2 postoperative weeks of feather-touch weight bearing. We hypothesized that the higher fixation stability of a plate fixator would justify early weight-bearing.

Results and conclusions: Early after surgery, RSA data showed a significant higher lateral translation of the distal tibia and a significantly increased subsidence, varus and internal rotation of the tibial head in the spacer plate compared to the plate fixator group. In addition, weight bearing following spacer plate fixation induced significant higher micromotion 6 weeks after surgery compared to the plate fixator group. Three months after surgery, however, bone healing was achieved regardless of the used implant. Two years after surgery, clinical results as well as alignments were satisfactory and without group differences. We conclude that early weight bearing following plate fixator fixation is appropriate due to its high primary fixation stability. The 6-week period of delayed weight bearing following spacer plate fixation seems to be inadequate and should be prolonged presumably up to 8-10 weeks to avoid early revarisation.