Double level osteotomy (DLO) for severe genu varum is not a common technique. We performed our first computer-assisted double level osteotomy (CADLO) in March 2001 and we published our preliminary results in 2005 and 2007. The rationale to perform this procedure is to avoid oblique joint line in order to have less difficulty in case of revision to a total knee arthroplasty (TKA). The goal of this paper is to present the results of 37 cases operated on between August 2001 and January 2010.

The series was composed of 35 patients (two bilateral), nine females and 26 males, aged from 39 to 64 years old (mean age: 50.5 +/− 7.5). We operated on 20 right knees and 17 left ones. The mean BMI was 29.3 +/− 4.3 for a mean height of 1.71 m and a mean weight of 85.8 kg. The functional status was evaluated according to the LYSHÖLM and TEGNER score. The mean score was of 42.4 +/− 8.9 points (22–69). According to modified AHLBÄCK criteria we operated on seven stage 2, 22 stage 3, five stage 4 and two stage 5. We measured HKA (Hip-Knee-Ankle) angle using RAMADIER's protocol and we also measured the femoral mechanical axis (FMA) and the tibial mechanical axis (TMA) to pose the right indication. These measures were respectively: 168° +/− 3.4° (159°–172°), 87.5° +/− 2.1 (83°–91°) for the FMA and 83.7° +/− 2.6° (78°–88°) for the TMA.

The inclusion criteria were a patient younger than 65 years old with a severe varus deformity (more than 8° − HKA angle ≤ to 172°) and a FMA at 91° or less. All the osteotomies were navigated using the ORTHOPILOT® device (B-BRAUN-AESCULAP, TUTTLINGEN, GERMANY). The procedure was performed as follows: after inserting the rigid-bodies and calibrating the lower leg, we did first the femoral closing wedge osteotomy (from 4 to 7 mm) which was fixed by a an AO T-Plate, and secondly, after checking the residual varus, the high tibial opening wedge osteotomy using a BIOSORB® wedge (Tricalcium phosphate) and a plate (AO T-plate or C-plate). The goals of the osteotomy were to achieve an HKA angle of 182° +/− 2° and a TMA angle of 90° +/− 2°.

The functional results were evaluated using the LYSHÖLM-TEGNER score and the KOOS score. The patients answered the questionnaire at revision or by phone, and the radiological results were assessed by plain radiographs and standing long leg X-Rays between three and six months postoperatively.

We had no complication in this series but one case of recurrence of the deformity related to an impaction of the femoral osteotomy on the medial side. Two patients were lost to follow-up after removing of the plates (24 months) but were included in the results because the file was complete at that date. All the patients were assessed at a mean follow-up of 43 +/− 27 months (12–108). The mean LYSHÖLM-TEGNER score was 78.7 +/− 7.5 points (59–91) and the mean KOOS score was 94.9 +/− 3.3 points (89–100). Thirty-five patients were satisfied (18) or very satisfied (17) of the result. Only two were poorly satisfied. Regarding the radiological results, if we exclude the patient who had a loss of correction, the goals were reached in 32 cases (89%) for the HKA angle and in 31 cases (86%) for the TMA with only one case at 93°. The mean angles were: 181.97° +/− 1,89° (177°–185°) for HKA, 89.86° +/− 1,85° (85°–93°) for TMA and 93.05° +/− 2.3° (89°–99°) for FMA. At that mid-term follow-up no patient had revision to a total knee arthroplasty.

DLO is a very demanding technique. Navigation can improve the accuracy of the correction compared to non computer-assisted osteotomies. The functional results are satisfying and the satisfaction of the patients is very high. Despite the difficulty of the procedure, complications are, in our hands, very rare. We recommend DLO for severe genu varum deformity in young patients to avoid oblique joint line, which will be difficult to revise to TKA.

Navigation of Uni knee arthroplasty (UKA) is not common. Usually the software includes navigation of the tibial as well as the femoral implant. In order to simplify the surgical procedure we thought that navigation of the tibial plateau alone could be a good option. Since 2005 we have been using a mobile bearing UKA of which the ancillary is based on dependent bone cuts. The tibial cut is made first and the femoral cut is automatically performed using cutting blocks inserted between the tibial cut and the distal end of the femur. Although we are satisfied with this procedure, it is not rare we have some difficulties getting the right under correction needed to get a good long-term result. The aim of this paper was to present our computer-assisted UKA technique and our preliminary radiological results in genu varum (17 cases) as well as genu valgum (6 cases) deformities.

The series was composed of 23 patients, 10 females and 13 males, aged from 63 to 88 years old (mean age: 75 +/− 8). The mean preoperative HKA (Hip-Knee-Ankle) angle was: 172.35° +/− 2.31° (167° to 176°) for the genu vara and 186.33° +/− 2.87° (182° to 189°) for the genu valga.

The goal of the navigation was to get an HKA angle of 177° +/− 2° for genu varum deformity and 183° +/− 2° for genu valgum.

We used the SURGETICS® device (PRAXIM, GRENOBLE, FRANCE) in the first six cases and the ORTHOPILOT® device (B-BRAUN-AESCULAP, TUTTLINGEN, GERMANY) in the other cases. The principles are the same for both devices. The 1rst step consists in inserting percutaneously the rigid-bodies on the distal end of the femur and on the proximal end of the tibia. Then, we locate the center of the hip by a movement of circumduction, the center of the ankle by palpating the malleoli and the center of the knee by palpating intra articular anatomic landmarks to get the HKA angle in real time. This step is probably the most important because it allows checking the reducibility of the deformity in order to avoid an over correction when inserting a mobile bearing prosthesis. The 3^rd step consists in navigation of the tibial cut such as the height of the resection, the tibial slope (3 to 5° posterior tibial slope) and the varus of the implant (2 to 3°). Once the tibial cut was done, we must use the conventional ancillary to perform the femoral bone cuts (distal and chamfer). The last step consists in inserting the trial implants and checking the HKA angle and the laxity of the medial or lateral side.

We used postoperative long leg X-Rays to evaluate the accuracy of navigation and plain radiographs to evaluate the right position of the implant.

As far as genu varum deformity was concerned, the mean postoperative HKA angle was 177.23° +/− 1.64° (173°–179°). The preoperative goal was reached in 94% of the cases. Moreover, this angle could be superimposed on the peroperative computer-assisted angle, which was 177° +/− 1.43° (p>0.05). For genu valgum, the mean postoperative HKA angle was 181° +/− 1.41° (179°–183°). The preoperative goal was reached in 66% of the cases but the series is too short to give any conclusion.

The navigation of tibial plateau alone can be used with accuracy, provided one has the right ancillary to use dependent bone cuts. The procedure is quick and needs only one tibial cutting guide equipped with a rigid-body. Our results, especially in genu varum deformity, are quite remarkable. Regarding genu valgum, the results seem to be less accurate, but the software was designed for medial UKA and the series is short, so, it is too soon to extrapolate any conclusion. The main interest in this navigation is to avoid too much under correction and even better to avoid over correction when the deformity is over reducible. Indeed, when one uses a mobile bearing plateau, the risk is to have a dislocation of the meniscus. So, when tightening the collateral ligaments, checking the lower limb axis may persuade not to use a mobile bearing plateau but rather a fixed plateau.