The cementless Oxford unicompartmental knee replacement
has been demonstrated to have superior fixation on radiographs and
a similar early complication rate compared with the cemented version.
However, a small number of cases have come to our attention where,
after an apparently successful procedure, the tibial component subsides into
a valgus position with an increased posterior slope, before becoming
well-fixed. We present the clinical and radiological findings of
these six patients and describe their natural history and the likely
causes. Two underwent revision in the early post-operative period,
and in four the implant stabilised and became well-fixed radiologically with
a good functional outcome. This situation appears to be avoidable by minor modifications
to the operative technique, and it appears that it can be treated
conservatively in most patients. Cite this article:
High Tibial Osteotomy (HTO) is an established treatment for unicompartmental osteoarthritis of the knee with malalignment. The classic procedure for correcting varus deformity is the lateral closed wedge osteotomy of the tibia with osteotomy of the fibula. The disadvantages of this technique are well known. Open wedge osteotomy from the medial sideeliminates the risk of compartment syndrome and peroneal nerve injuries. A new fixation device (TomoFix(tm)) with an adapted surgical technique allows stable fixation of the osteotomy without the need to fill the osteotomy gap with bone grafts. In a prospective study, 92 consecutive cases were treated with this procedure. Bony healing with remodelling of the medial and posterior cortical bone was observed. Full weight-bearing was possible ten weeks after surgery. There were no implant failures. Complications included one delayed union, two revarisations and one deep infection. Keywords: High Tibial Osteotomy (HTO), openwedge osteotomy, TomoFix(tm) plate, medial osteoarthritis, varus knee
