Abstract
High tibial osteotomy (HTO) is a surgical procedure that involves cutting the proximal tibia in an attempt to change the weight bearing axis from the medial to the lateral compartment of the knee. It is especially appropriate for young and middle age active patients who have a primary, degenerative arthrosis involving the medial compartment in a malaligned limb, and causing pain and functional limitation.
Over the last ten years, the indications for HTO have expanded to include patients with initial cartilage damage that can be treated with one of the new cartilage repair techniques and patients with chronic ligament deficiency, associated with a varus malalignment. The opening wedge HTO is a relatively new technique, compared to the Coventry’s lateral closing wedge osteotomy. It turns upside down the method of correction of the varus deformity, adding a wedge medially and is based on a dedicated system of instruments and plates (Arthrex, Naples, Florida).
In the international literature, many series have shown encouraging middle-term results following HTO. The majority of authors agree that there is a gradual decline in the quality of the result with time. In general, HTO has been demonstrated to be effective for approximately five years in 85–90% of the patients, and for about two thirds (65%) of them over ten years from the operation. Aglietti, in a review of 139 knees that had HTO, noted excellent and good results in 64% of the knees after a follow-up period of at least 10 years. However, a tendency for results to deteriorate with time was observed, with satisfactory results in 64% with more than 10 years follow-up evaluation, 70% of the knees with six to 10 years evaluation and 87% of the knees with two to five years evaluation. Insall (21) reported 97% of good results at two years, 85% good results at five years and 63% good results at nine years. At nine years, deterioration in these patients was primarily the result of time, and not recurrence of deformity. In contrast with Insall, other authors have reported instead that deterioration of results is due to recurrence of deformity.
From our personal experience, we have a series of 55 patients, six bilateral, operated on between 1992 and 2000, with the opening wedge technique, follow-up six to 14 years. The average age was 49 years, 32 men and 23 women. The results were evaluated using the International Knee Documentation Committee (IKDC) rating scale and the Hospital for Special Surgery (HSS) scoring system. Pre-operatively, 38 patients belonged to group “C” and 17 to group “D” of the IKDC rating scale. At follow up, all the 38 patients of group C passed to group B. Of the 17 patients in group D, 13 passed to group C and 4 to group B. All the patients improved their conditions at least one category. The same results evaluated with the HSS score system resulted in 33 knees poor and 22 fair before the HTO. At follow up, we had 14 excellent, 38 good and 3 fair. These particularly satisfying results may be influenced by the improper use of the HSS score system, which was designed to evaluate results in prosthetic replacement surgery.
Correspondence should be addressed to Associate Professor N. Susan Stott at Orthopaedic Department, Starship Children’s Hospital, Private Bag 92024, Auckland, New Zealand
