Osteotomy for medial gonarthrosis is most often done as a proximal tibial valgus osteotomy, either as a closing wedge osteotomy (HTO) or as an opening wedge osteotomy including hemicallostasis (HCO). In case of lateral gonarthrosis the osteotomy is done as a proximal tibial varus osteotomy, closing or opening wedge or as a distal femoral varus osteotomy depending on the anatomy of the knee. The early period after osteotomy is influenced by complications to osteotomy. Complications depend on the operative method and localisation of surgery. Short- and long-term results are presented as knee scores or survivorship of high tibial osteotomy. Most often used scores are the HSS-score, NHP-score and the knee scores according to Lysholm and Tegner. Scores from the patient’s perspective are NHP, SF-36. KOOS (Knee Injury and Osteoarthritis Outcome Score) was introduced recently, and only short-term results are available.
Immediate postoperative results The closing wedge osteotomy is the golden standard and reported complications are peroneal palsy in 0 – 8%, infection in 1 – 3%, fracture of the tibial plateau and delayed union in 3 – 5% and thromboembolism in 2 – 4%. When the opening wedge method including HCO is used peroneal palsy is extremely seldom, delayed union is reported in 2%, major pin-tract infection in 2 – 20 % and thromboembolism in 2 – 4%. Short-term results The short-term results are generally good and one to two years after osteotomy excellent and good results are reported in 85 – 97 %. All five partial scales in KOOS with the exception of sports/ recreation function were significantly improved 3 – 4 months postoperatively.
Evaluations of osteotomies using survivorship of the osteotomy, with conversion to a total knee as the endpoint, show an expected rate of survival of 73–94% at 5 years, 51–85 % at ten years, 39–68 % at 15 years and 30% at 20 years. Analysis of risk factors show that age older than 50 years, presence of lateral tibial thrust and insufficient valgus correction were significantly associated with probability of early failure. Evaluations using knee scores with a mean follow-up time of 5 – 10 years show excellent and good result in 64 – 80%. At follow-up 11– 15 years after surgery the fraction good and excellent knees is 55 – 60% and 16– 20 years after osteotomy a minority of the knees are good or excellent, at most 46%. Stage of arthrosis: Good long-term results are reported for knees with early medial arthrosis with at most obliteration of the medial joint space or just minimal bone attrition. Results after HCO on knees with more advanced gonarthrosis are reported with a short follow-up and the change of osseous correction after osteotomy was less compared to HTO. Only minimal progress of arthrosis after osteotomy is reported in most papers. The results of some studies indicate that the greater the surgical correction, the slower the progress of the medial joint arthrosis. Alignment of the knee: Most reports find better clinical results and less risk for failure when the osteotomy is corrected to a slight over-correction of the knee alignment. There is however no consensus on the smallest correction needed to change the load on the medial arthrotic compartment.
The condition is uncommon and a minority of the papers on osteotomy for gonarthrosis concern osteotomy for lateral gonarthrosis. The aim of osteotomy for lateral gonarthrosis is to achieve a varus alignment of the knee with a joint line obliquity, which after surgery is less than 10 degrees. That affects the method, which is either a proximal tibial osteotomy or a distal femoral osteotomy. Most often the aetiology of the deformity is posttraumatic. Immediate postoperative results When using the opening wedge osteotomy on tibia transient nerve palsy is reported in 9–50%. Infection is reported in 2% and thromboembolism in 2 – 4%. Pin tract infection when using HCO is reported in 2 – 20%. In a multicenter follow-up distal femoral varus osteotomy 11 complications were recorded in 32 patients (five non unions, three deep infections and three cases with a stiff knee). Short-term results Short-term results one to two years after surgery are reported excellent and good in 85 – 95%. Results 5 – 15 years Five to ten years after surgery good and excellent results are reported in 75 − 77%, and in 11 – 15 years after surgery in 50 – 80%. Results are much better in recent reports because of better patient selection and operative technique. The tibial varus osteotomy can be used in knees with less than 12 degrees of valgus. Furthermore the tilting of the tibiofemoral joint line should postoperatively be less than 10 degrees. Otherwise a distal femoral osteotomy should be used. Persistent excessive obliquity of the tibiofemoral joint line predisposes instability with risk of compromising the result. To summarize: Osteotomy is effective in a patient with a medial or a lateral gonarthrosis at most Stage II according to the classification of Ahlbäck, under the age of between 50 and 60 years and of high demands by reason of lifestyle and occupation. Aim at an overcorrection so when the osteotomy is healed you should have a slight overcorrection in valgus in medial gonarthrosis and in varus when you have a lateral gonarthrosis. Furthermore the joint line obliquity should postoperatively be less than 10 degrees. With this selection of patients and with a good surgical technique your patient can expect a probability of having a good knee in about 70 % after ten years. After ten years it is more difficult to make a prognosis for your patients knee.
