Background
High tibial osteotomy (HTO) is an established treatment for medial compartment osteoarthritis of the knee with varus malalignment. Medial opening wedge osteotomy eliminates most of the disadvantages of the lateral closing wedge osteotomy. Nevertheless, the changes in tibial slope and patellar height after opening wedge HTO with frequent occurrence of patella baja make subsequent knee arthroplasty more difficult.
Purpose
The purpose of this study was to evaluate the results of a simple technique for medial opening wedge HTO with internal fixation and early mobilization in patients with combined medial compartment osteoarthritis and varus alignment of the knee.
Patients and methods
Opening-wedge HTO and internal fixation with a standard AO large-fragment T plate with posterior tricortical iliac bone autograft was assessed. Forty-five patients with 61 knees with combined medial femorotibial osteoarthritis and varus deformity of the knee were treated with opening wedge HTO. There were 21 women with 29 knees, with a mean age 45.5 years (30–58 years), and 24 men with 32 knees, with a mean age 41.63 years (30–55 years). Mean follow-up was 35.9 months (13–62 months). Radiographic measurements [femorotibial angle, tibial slope, Insall–Salvati, and Blackburne–Peel (BP) ratios] were taken preoperatively and postoperatively and on follow-up. Preoperative and postoperative (last follow up) values of these parameters were compared.
Results
Fifty of the 61 (82%) knees had an excellent or good result, whereas in 11 knees there was recurrent pain. There were no implant failures, loss or correction, delayed union, or nonunion. Femorotibial angle was changed from a mean of −7.2° of varus into a mean of 8.3° of valgus (=0.000). Tibial slope was significantly decreased from a mean of 11.4° to a mean of 9.2° (=0.002). Insall–Salvati ratio was significantly increased from a mean of 1.1 to a mean of 1.2 (=0.000). There was a significant decrease in the BP ratio from a mean of 0.9 to a mean of 0.7 (=0.005). Twenty-five percent of postoperative BP values satisfied the criteria for patella infera (BP<0.54).
Conclusion
Opening wedge HTO using a simple technique with rigid fixation and early mobilization decreased the posterior inclination of the tibial slope, straightened the patellar tendon, and elevated the tibiofemoral joint line. The decrease in the inclination of the posterior slope of the tibia and the stretching of the patellar ligament compensate for the elevation of the joint line. This together with the early mobilization protocol resulted in the low incidence of patella infera.