Abstract
The aim of this study was to examine the results of medial opening wedge high tibial osteotomies in which TRISOITE (hydroxyapatite tricalcium phosphate composite) wedges have been used as bone graft substitute and to compare the histological results with the clinical outcome.
There were 36 medial opening wedge high tibial osteotomy performed in 33 patients with a mean age of 45 years. Medial compartment osteoarthritis with varus alignment was the indication in 32 patients. All were followed to union with a minimum follow up of 6 months (average 50 months).
The surgical technique involved creating an oblique upper tibial osteotomy at an angle of 60 degrees from distal-medial to proximal lateral, passing distal to the insertion of the patellar ligament and preserving the lateral cortex. The osteotomy was opened to the desired angle of correction and preformed Triosite wedges were inserted. Stabilisation was obtained with a contoured titanium T-plate (ENZTEC). Re-operation was required for metal removal or conversion to total knee replacement in 10 cases. All of these patients had a biopsy of the osteotomy site.
The clinical notes and x-rays were retrospectively reviewed. One patient developed a superficial infection post-operatively which was successfully treated with intravenous antibiotics. Bone grafting was required to achieve union in 1 case (2.8%). There were no cases of varus deformity recurrence as a result of graft collapse. Biopsies provided microscopic evidence of bony incorporation around the tricalcium phosphate with bone healing. Three patients were converted to total knee replacement with no problems at the osteotomy site.
Triosite wedges appear to be a reliable synthetic bone graft substitute to act as a scaffold for bone healing in opening wedge osteotomies. They reduce the morbidity associated with iliac crest bone graft.
Correspondence should be addressed to: Associate Professor N. Susan Stott, Orthopaedic Department, Starship Children’s Hospital, Private Bag 92024, Auckland, New Zealand.
