Aims. Medial unicompartmental knee arthroplasty (UKA) is undertaken in patients with a passively correctable varus deformity. Our hypothesis was that restoration of natural soft tissue tension would result in a comparable lower limb alignment with the contralateral normal lower limb after mobile-bearing medial UKA. Patients and Methods. In this retrospective study, hip-knee-ankle (HKA) angle, position of the weight-bearing axis (WBA) and knee joint line obliquity (KJLO) after mobile-bearing medial UKA was compared with the normal (clinically and radiologically) contralateral lower limb in 123 patients. Results. Postoperatively, HKA angle was restored to within ±3° of the contralateral lower limb in 87% of patients andWBA passed within ±1 Kennedy and White's tibial zone of the contralateral normal lower limb in 95% of patients. The difference in the mean KJLO between the two groups was not significant (p=0.05) and the KJLO was within ±3° of the contralateral normal lower limb in 96% of patients. Conclusion. Lower limb alignment & knee joint line obliquity after mobile-bearing medial UKA were comparable to the unaffected contralateral limb in most patients. Clinical Relevance. Comparison with the contralateral normal lower limb is a reliable method to evaluate and validate limb mechanical alignment after mobile-bearing medial UKA

Introduction. The hip-knee-ankle (HKA) angle between the mechanical axis of the femur (FM) and the mechanical axis of the tibia (TM) is the standard parameter to assess the coronal alignment of the lower extremity. TM is the line between the center of the tibial spines notch (Point T) and the center of the tibial plafond. However, this theory is based on the premise that TM coincides the anatomical axis of the tibia (TA). Fig.1a shows typical varus knee with medial shift of the tibial articular surface. In this case, TM does not coincide TA. Fig. 2 demonstrates the error of HKA angle when Point T locates medial to TA. Fig.2a shows normal alignment. Fig.2b shows varus alignment. Fig. 2c shows the tibia with medial shift of the tibial articular surface. The tibia has 7 degrees varus articular inclination in Fig.2b and 2c. However, HKA angle is 0 degree in Fig.2c. HKA angle underestimates varus deformity in knees with medial shift of the tibial articular surface. However, the degree of medial shift of the tibial articular surface is obscure. In this study, detailed anatomical configuration of the proximal tibia was evaluated. The effect of the value of HKA angle on the coronal alignment in TKA was then discussed. Methods. This study consists of 117 knees. On the AP view radiograph of the tibia, three distance and two angle parameters were measured. Those were tibial articular surface width, distance between medial edge of the tibial articular surface and Point T, distance from TA to Point T. Angle between TM and TA, and the varus inclination angle of the tibial articular surface relative to the perpendicular line to TA. Results. The mean width of the tibial articular surface was 87.8mm. The mean distance between Point T and medial edge of the articular surface was 43.6mm. Point T located at the center of the tibial articular surface. The mean distance from TA to Point T was 5.6mm. The mean angle between TM and TA was 1.0 degrees. The inclination angle of the tibial articular surface was 8.2 degrees. Discussion. The results clearly showed that varus knees had medial shift of the tibial articular surface. In such knees, the ankle shifts laterally relative to the Point T and HKA angle underestimates the varus deformity. The value of HKA angle also influences the evaluation of the coronal alignment of the lower extremity in TKA (Fig. 3). When the tibial tray is set based on the tibial articular surface width in order to cover the cut surface of the tibia, HKA angle shows the alignment as valgus when the tibial tray is set perpendicular to TA (Fig. 3a). In order to obtain zero degree of HKA angle, the tibial tray should be set perpendicular to TM. This alignment is varus (Fig. 3b). Reduction osteotomy is one procedure to match the value of HKA angle and the true alignment (Fig. 3c). In this technique, HKA angle is zero degree, and TM and TA coincide. For figures, please contact authors directly.

INTRODUCTION. The restoration of physiological kinematics is one of the goals of a total knee arthroplasty (TKA). Navigation systems have been developed to allow an accurate and precise placement of the implants. But its application to the intraoperative measurement of knee kinematics has not been validated. The hypothesis of this study was that the measurement of the knee axis, femoral rotation, femoral translation with respect to the tibia, and medial and lateral femorotibial gaps during continuous passive knee flexion by the navigation system would be different from that by fluoroscopy taken as reference. MATERIAL – METHODS. Five pairs of knees of preserved specimens were used. The e.Motion FP ® TKA (B-Braun Aesculap, Tuttlingen, Germany) was implanted using the OrthoPilot TKA 4.3 version and Kobe version navigation system (B-Braun Aesculap, Tuttlingen, Germany). Kinematic recording by the navigation system was performed simultaneously with fluoroscopic recording during a continuous passive flexion-extension movement of the prosthetic knee. Kinematic parameters were extracted from the fluoroscopic recordings by image processing using JointTrack Auto ® software (University of Florida, Gainesville, USA). The main criteria were the axis of the knee measured by the angle between the center of the femoral head, the center of the knee and the center of the ankle (HKA), femoral rotation, femoral translation with respect to the tibia, and medial and lateral femorotibial gaps. The data analysis was performed by a Kappa correlation test. The agreement of the measurements was assessed using the intraclass correlation coefficient (ICC) and its 95% confidence interval. RESULTS. The respective CCIs were as follows: HKA angle 0.839 [0.820; 0.856]; femoral translation 0.560 [0.517; 0.600]; femoral rotation 0.652 [0.616; 0.686]; medial femorotibial gap 0.905 [0.894; 0.916]; lateral femorotibial gap 0.767 [0.740; 0.791]. DISCUSSION. Measurements of TKA kinematics by the navigation system and by fluoroscopy were consistent for HKA angle and medial and lateral femorotibial gaps, but not for femoral translation and femoral rotation. These differences can be explained by a methodological bias. At the end of this work, the specific navigation system cannot be considered as a reliable instrument for measuring the kinematics of a TKA

Background. Alignment and soft tissue (ligament) balance are two variables that are under the control of a surgeon during replacement arthroplasty of the knee. Mobile bearing medial unicompartmental knee replacements have traditionally advocated sizing the prosthesis based on soft tissue balance while accepting the natural alignment of the knee, while fixed bearing prosthesis have tended to correct alignment to a pre planned value, while meticulously avoiding overcorrection. The dynamic loading parameters like peak adduction moment (PKAM) and angular adduction Impulse (Add Imp) have been studied extensively as proxies for medial compartment loading. In this investigation we tried to answer the question whether correcting static alignment, which is the only alignment variable under the control of the surgeon actually translates into improvement in dynamic loading during gait. We investigated the effect of correction of static alignment parameter Hip Knee Ankle (HKA) angle and dynamic alignment parameter in coronal plane, Mean Adduction angle (MAA) on 1st Peak Knee Adduction Moment (PKAM) and Angular Adduction Impulse (Add Imp) following medial unicompartmental knee replacements. Methods. Twenty four knees (20 patients) underwent instrumented gait analysis (BTS Milan, 12 cameras and single Kistler force platform measuring at 100 Hz) before and after medial uni compartmental knee replacement. The alignment was measured using long leg alignment views, to assess Hip Knee Ankle (HKA) angle. Coronal plane kinetics namely 1st Peak Knee Adduction Moment (PKAM) and angular adduction impulse (Add Imp)- which is the moment time integral of the adduction moment curve were calculated to assess medial compartment loading. Single and multiple regression analyses were done to assess the effect of static alignment parameters (HKA angle) and dynamic coronal plane alignment parameters (Mean Adduction Angle – MAA) on PKAM and Add Imp. Results. 12 knees had mobile bearing prosthesis implanted while the other 12 had fixed bearing prosthesis. The mean correction for HKA angle was 2.78 degrees (SD ± 1.32 degrees). There was no significant difference in correction of alignment (HKA) between mobile bearing and fixed bearing groups. MAA and HKA angles were significant predictors of dynamic loading parameters, PKAM and Add Imp (p<0.05). Correction of HKA angle was found to be a better predictor of dynamic loading. We assessed the percentage improvement in loading (%ΔPKAM & %ΔAdd. Imp) and its relationship to correction of HKA (Δ HKA) angle Correction of alignment in the form of HKA (Δ HKA) angle was found to be a very strong predictor of improvement of loads (R = 0.90 for %ΔAdd. Imp and R = 0.50 for %Δ PKAM). Conclusion. Correction of alignment (HKA Angle) predicts improvement in loads through medial compartment of knee. One degree correction resulted in 7% improvement of load through the medial unicompartmental knee replacement

Osteotomies for valgus deformity are much less frequent than those for varus deformity as evidenced by published series which are, on one hand, less numerous and on the other hand, based on far fewer cases. For genu varum deformity, it has been proved that navigation allows to reach easier the preoperative correction goal. Our hypothesis was that navigation for genu valgum could be as accurate as for genu varum deformity. The aim of this paper was to present the mid-term results of 29 computer-assisted osteotomies for genu valgum deformity performed between September 2001 and March 2013. The series was composed of 27 patients (29 knees), 20 females and 7 males, aged from 15 to 63 years (mean age: 42.4+/−14.3 years). The preoperative functional status was evaluated according to the Lyshölm-Tegner score. The mean score was of 64+/−20.5 points (18–100). The stages of osteoarthritis were evaluated according to modified Ahlbäck's criteria. We operated on 12 stage 1, 9 stage 2, 5 stage 3 and 1 stage 4. 2 female patients had no osteoarthritis but a particularly unesthetic deformity (of which one was related to an overcorrected tibial osteotomy). The pre and postoperative HKA angle was measured according to Ramadier's protocol. We measured also the medial tibial mechanical angle (MTMA) and the medial femoral mechanical angle (MFMA). The mean preoperative HKA angle was 189.3°+/−3.9° (181° to 198°); the mean MFMA was 97.2° +/− 2.6° (93° to 105°) and the mean MTMA was 90.1° +/− 2.8° (86° to 95°). The goal of the osteotomies was to obtain an HKA angle of 179° +/− 2° and a MTMA of 90°+/2° in order to avoid an oblique joint line. We performed 24 femoral osteotomies (14 medial opening wedge and 10 lateral closing wedge) and 5 double osteotomies (medial tibial closing wedge + lateral opening wedge osteotomy). The functional results were evaluated according to Lyshölm-Tegner, IKS and KOO Scores, which were obtained after revision or telephone call. We did not find any complication except a transient paralysis of the common fibular nerve. 23 patients (4 lost to follow-up) were reviewed at a mean follow-up of 50.9+/−38.8 months (6–144). The mean Lyshölm-Tegner score was 92.9+/−4 points (86–100), the mean KOO score 89.7+/−9.3 (68–100), the mean IKS ≪knee≫ score 88.7 +/−11.4 points (60 à 100) and the mean ≪function≫ score 90.6 +/−13.3 points (55–100). 22 of the 23 reviewed patients (25 knees) were very satisfied or satisfied of the result. Regarding the radiological results, the mean HKA angle was of 180.1°+/−1.9° (176° to 185°), the mean MFMA of 90.7°+/−2.5° (86°-95°) and the mean MTMA of 89.1°+/−1.9° (86°-92°). The preoperative goal was reached in 86.2% (25/29) of the cases for HKA angle and in 100% of the cases for MTMA when performing double level osteotomy (5 cases). At this follow-up, no patient was revised to TKA. Computer-assisted osteotomies for genu valgum deformity lead to excellent results a mid-term follow-up. Navigation is very useful to reach the preoperative goal

Introduction. The current standard for alignment in total knee arthroplasty (TKA) is neutral mechanical axis within 3° of varus or valgus deviation [1]. This configuration has been shown to reduce wear and optimally distribute load on the polyethylene insert [2]. Two key factors (patient-specific hip-knee-ankle (HKA) angle and surgical component alignment) influence load distribution, kinematics and soft-tissue strains across the tibiofemoral (TF) joint. Improvements in wear characteristics of TKA materials have facilitated a trend for restoring the anatomic joint line [3]. While anatomic component alignment may aid in restoring more natural kinematics, the influence on joint loads and soft-tissue strains should be evaluated. The purpose of the current study was to determine the effect of varus component alignment in combination with a variety of HKA limb alignments on joint kinematics, loads and soft-tissue strain. Methods. A dynamic three-dimensional finite element model of the lower limb of a TKA patient was developed. Detailed description of the model has been previously published [4]. The model included femur, tibia and patella bones, TF ligaments, patellar tendon, quadriceps and hamstrings, and was virtually implanted with contemporary cruciate-retaining fixed-bearing TKA components. The model was initially aligned in ideal mechanical alignment with neutral HKA limb alignment. A design-of-experiments (DOE) study was performed whereby component placement was altered from neutral to 3° and 7° varus alignment, and HKA angle was altered from neutral to ±3° and ±7° (valgus and varus) (Figure 1). Results. HKA angle has a greater influence on kinematics, particularly PF medial-lateral (M-L) translation in early flexion and TF internal-external (I-E) rotation; at 60° flexion change in TF I-E rotation due to HKA angle was 12.4° compared to change due to component V-V alignment of 2.3° (Figure 1). Component alignment was the main factor in overall TF loads; varus component alignment increased the medial force, external torque and valgus torque acting on the insert. Shear force at the bone-implant interface increased by 15% (∼90N) with varus component rotation of 7°. Varus component alignment increased forces in the lateral structures and reduced forces in the medial structures (Figure 2). Both valgus HKA angle and varus component alignment altered M-L load distribution by reducing medial forces and increasing lateral forces (Figure 3). Discussion. Placement of TKA components in anatomic alignment has potential to better integrate the implants with the soft-tissues of the joint and may better reproduce natural kinematics. However, varus component alignment in conjunction with valgus HKA limb alignment substantially alters M-L distribution of load across the condyles, increasing the load on the lateral condyle. Varus component alignment will result in load distributions which are different from their mechanically aligned counterparts. As such, pre-clinical evaluation of components used in varus alignment should ensure that components are robust to loading conditions which will be encountered across the range of TKA patient HKA alignments

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

Introduction. Coronal misalignment of the lower limbs is closely related to the onset and progression of osteoarthritis. In cases of severe genu varus or valgus, evaluating this alignment can assist in choosing specific surgical strategies. Furthermore, restoring satisfactory alignment after total knee replacement promotes longevity of the implant and better functional results. Knee coronal alignment is typically evaluated with the Hip-Knee-Ankle (HKA) angle. It is generally measured on standing AP long-leg radiographs (LLR). However, patient positioning influences the accuracy of this 2D measurement. A new 3D method to measure coronal lower limb alignment using low-dose EOS images has recently been developed and validated. The goal of this study was to evaluate the relevance of this technique when determining knee coronal alignment in a referral population, and more specifically to evaluate how the HKA angle measured with this 3D method differs from conventional 2D methods. Materials and methods. 70 patients (140 lower extremities) were studied for 2D and 3D lower limb alignment measurements. Each patient received AP monoplane and biplane acquisition of their entire lower extremities on the EOS system according the classical protocols for LLR. For each patient, the HKA angle was measured on this AP X-ray with a 2D viewer. The biplane acquisition was used to perform stereoradiographic 3D modeling. Valgus angulation was considered positive, varus angulation negative. Student's T-test was used to determine if there was a bias in the HKA angle measurement between these two methods and to assess the effect of flexion/hyperextension, femoral rotation and tibial rotation on the 2D measurements. One operator did measurements 2 times. Results. The average total dose for both acquisitions was 0.75mGy (± 0.11mGy). The 2D and 3D measurements are reported in table 1. Intraoperator reliability was >0,99 for all measurements. In the whole series, 2D–3D HKA differences were >2° in 34% of cases, >3° in 22% of cases, >5° in 9% of cases and >10° in 3% of cases >10°. We compared 2D and 3D measurements according to the degree of flessum/recurvatum (> or <5° and > or <10°). The results are reported in table 2. The statistical analysis of parameters influencing 2D/3D measurements is reported in table 3. Discussion and conclusion. The HKA angle is typically assessed from 2D long-leg radiographs. However, several studies highlighted that 2D assessment of this angle may be affected by patient's positioning. Radtke showed that lower limb rotation during imaging significantly affected measurements of coronal plane knee alignment. Brouwer showed that axial rotation had an even greater effect on the apparent limb alignment on AP radiographs when the knee was flexed. This last finding is particularly relevant as many lower extremities present some amount of flexion or hyperextension, especially in aging subjects. This low dose biplanar EOS acquisitions provide a more accurate evaluation of coronal alignment compared to 2D, eliminating bias due to wrong knee positioning. This study points out the interest of EOS in outliers patients and opens new perspectives for preoperative planning and postoperative control of deformity correction or knee joint replacement

Excessive under correction of varus deformity may lead to early failure and overcorrection may cause progressive degeneration of the lateral compartment following medial unicompartmental knee arthroplasty (UKA). However, what influences the postoperative limb alignment in UKA is still not clear. This study aimed to evaluate postoperative limb alignment in minimally-invasive Oxford medial UKAs and the influence of factors such as preoperative limb alignment, insert thickness, age, BMI, gender and surgeon's experience on postoperative limb alignment. Clinical and radiographic data of 122 consecutive minimally-invasive Oxford phase 3 medial unicompartmental knee arthroplasties (UKAs) performed in 109 patients by a single surgeon was analysed. Ninety-four limbs had a preoperative hip-knee-ankle (HKA) angle between 170°-180° and 28 limbs (23%) had a preoperative hip-knee-ankle (HKA) angle <170°. The mean preoperative HKA angle of 172.6±3.1° changed to 177.1±2.8° postoperatively. For a surgical goal of achieving 3° varus limb alignment (HKA angle=177°) postoperatively, 25% of limbs had an HKA angle >3° of 177° and 11% of limbs were left overcorrected (>180°). Preoperative HKA angle had a strong correlation (r=0.53) with postoperative HKA angle whereas insert thickness, age, BMI, gender and surgeon's experience had no influence on the postoperative limb alignment. Minimally invasive Oxford phase 3 UKA can restore the limb alignment within acceptable limits in majority of cases. Preoperative limb alignment may be the only factor which influences postoperative alignment in minimally-invasive Oxford medial UKAs. Although the degree of correction achieved postoperatively from the preoperative deformity was greater in limbs with more severe preoperative varus deformity, these knees tend to remain in more varus or under corrected postoperatively. Overcorrection was more in knees with lesser preoperative deformity. Hence enough bone may need to be resected from the tibia in knees with lesser preoperative deformity to avoid overcorrection whereas limbs with large preoperative varus deformities may remain under corrected

Introduction. At a minimum 12 years follow-up the Authors performed a matched paired study between 2 groups: Bi-Unicompartimental (femoro-tibial) versus Total Knee Replacements, both navigated, they hypothesised that Bi-UKR guarantees a clinical score and patient satisfaction at least similar to TKR without differences in survivorship. Materials and Methods. 19 BI-UKR (1999–2003) were included in the study (group A). Every single patients in group A was matched to a computer-assisted TKR implanted in the same period (group B). The clinical outcome was evaluated using the Knee Society Score, the GIUM Score and the WOMAC Arthritis Index. Radiographically the HKA angle and the Frontal Tibial Component angle (FTC) were. Statistical analysis of the results was performed and Kaplan-Meir survival rate was assessed in both the groups. Results. No statistically significant difference was seen for the Knee Society, Functional and GIUM scores between the 2 groups. Statistically significant better WOMAC Function and Stiffness indexes were registered for the Bi-UKR group. All the TKR implants still remained positioned within 4 degrees of an ideal HKA angle of 180° and ideal FTC angle of 90° with a statistically significant better alignment compared to the Bi-UKR group. The Kaplan-Meier survival did not show any statistical significant differences in survivorship. Discussion. At 12 years minimum follow-up there are no significant differences in survivorship and clinical score despite a worse implant alignment WOMAC function and stiffness scores are still statistically better in the Bi-UKR group

The hip centre (HC) in Computer Assisted Orthopedic Surgery (CAOS) can be determined either with anatomical (AA) or functional approaches (FA). AA is considered as the reference while FA compute the hip centre of rotation (CoR). Four main FA can be used in CAOS: the Gammage, Halvorsen, pivot, and least-moving point (LMP) methods. The goal of this paper is to evaluate and compare with an in-vitro experiment (a) the four main FA for the HC determination, and (b) the impact on the HKA. The experiment has been performed on six cadavers. A CAOS software application has been developed for the acquisitions of (a) the hip rotation motion, (b) the anatomical HC, and (c) the HKA angle. Two studies have been defined allowing (a) the evaluation of the precision and the accuracy of the four FA with respect to the AA, and (b) the impact on the HKA angle. For the pivot, LMP, Gammage and Halvorsen methods respectively: (1) the maximum precision reach 14.2, 22.8, 111.4 and 132.5 mm; (2) the maximum accuracy reach 23.6, 40.7, 176.6 and 130.3 mm; (3) the maximum error of the frontal HKA is 2.5°, 3.7°, 12.7° and 13.3°; and (4) the maximum error of the sagittal HKA is 2.3°, 4.3°, 5.9°, 6.1°. The pivot method is the most precise and accurate approach for the HC localisation and the HKA computation

Total knee arthroplasty(TKA) for patients with severe varus deformity has become common operation in Japan because of the rapid aging of the population. Treatment of severe malalignment, instability and bone defects is important. Here we report the clinical results of total knee arthroplasty for 23 knees with severe varus deformity. We defined a severe varus knee femorotibial angle(FTA) as one exceeding 195 degrees. The average observation period was 64 months. Autologous bone graft was performed for 3 knees and augmentation and long tibia stem was used for 3 knees. We used SF-36 for clinical evaluation. Image assessment was based on the standing HKA(Hip-Knee-Ankle)angle, and the Knee Society TKA roentgenographic evaluation and scoring system. The mean SF-36 score improved from 47.6 points to 63.7 points after TKA. The standing mean HKA angle was 204°(range 197° to 215°) before surgery and was corrected to 185°(range 176° to 195°). The post-operative standing HKA angle was classified as HKA>184°, 184°>HKA>177°, HKA<176°. A clear zone appeared in zone1 on tibia APX-ray in 4 knees belonging to the HKA>184° group. Our 23 knees achieved good results, and careful postoperative observation is still necessary especially in the vgarus group

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

Aims. The aims of this retrospective study were to determine the incidence of extra-articular deformities (EADs), and determine their effect on postoperative alignment in knees undergoing mobile-bearing, medial unicompartmental knee arthroplasty (UKA). Patients and Methods. Limb mechanical alignment (hip-knee-ankle angle), coronal bowing of the femoral shaft and proximal tibia vara or medial proximal tibial angle (MPTA) were measured on standing, full-length hip-to-ankle radiographs of 162 patients who underwent 200 mobile-bearing, medial UKAs. Results. Incidence of EAD was 7.5% for coronal femoral bowing of >5°, 67% for proximal tibia vara of >3° (MPTA<87°) and 24.5% for proximal tibia vara of >6° (MPTA<84°). Mean postoperative HKA angle achieved in knees with femoral bowing ≤5° was significantly greater when compared to knees with femoral bowing >5° (p=0.04); in knees with proximal tibia vara ≤3° was significantly greater when compared to knees with proximal tibia vara >3° (p=0.0001) and when compared to knees with proximal tibia vara >6° (p=0.0001). Conclusion. Extra-articular deformities are frequently seen in patients undergoing mobile-bearing medial UKAs, especially in knees with varus deformity>10°. Presence of an EAD significantly affects postoperative mechanical limb alignment achieved when compared to limbs without EAD and may increase the risk of limbs being placed in varus>3° postoperatively. Clinical Relevance. Since the presence of an EAD, especially in knees with varus deformity>10°, may increase the risk of limbs being placed in varus>3° postoperatively and may affect long-term clinical and implant survival outcomes, UKR in such knees should be performed with caution

Background. The posterior slope of the tibial component in total knee arthroplasty (TKA) has been reported to vary widely even with computer assisted surgery. In the present study, we analyzed the influence of posterior tibial slope on one-year postoperative clinical outcome after posterior-stabilized (PS) -TKA to find out the optimal posterior slope of tibial component. Materials and Method. Seventy-three patients with varus type osteoarthritic (OA) knees underwent PS-TKA (Persona PS. R. ) were involved in this study. The mean age was 76.6 years old and preoperative HKA angle was 14.3 degrees in varus. Tibial bone cut was performed using standard extra-medullary guide with 7 degrees of posterior slope. The tibial slopes were radiographically measured by post-operative lateral radiograph with posterior inclination in plus value. The angle between the perpendicular line of the proximal fibular shaft axis and the line drawn along the superior margin of the proximal tibia represented the tibial slope angle. We assessed one-year postoperative clinical outcomes including active range of motion (ROM), patient satisfaction and symptoms scores using 2011 Knee Society Score (2011 KSS). The influences of posterior tibial slope on one-year postoperative parameters were analyzed using simple linear regression analysis (p<0.05). Results. The average posterior tibial slope was 6.4 ± 2.0 °. The average active ROM were −2.4 ± 6.6 ° in extension and 113.5± 12.6 ° in flexion. The mean one-year postoperative patient satisfaction and symptom scores were 29.3 ± 6.4 and 19.6 ± 3.9 points respectively. The active knee extension, satisfaction and symptom scores were significantly negatively correlated to the posterior tibial slope (r = −0.25, −0.31, −0.23). Discussion. In the present study, we have found significant influence of the posterior tibial slope on the one-year postoperative clinical outcomes in PS-TKA. The higher posterior slope would induce flexion contracture and deteriorate patient satisfaction and symptom. We had reported that the higher tibial posterior slope increased flexion gap and the component gap change during knee flexion in PS-TKA. Furthermore, another study reported that increase of the posterior tibia slope reduced the tension in the collateral ligaments and resulted in the knee laxity at flexion. The excessive posterior slope of tibial component would result in flexion instability, and adversely affected the clinical results including patient satisfaction and symptom. Conclusion. In the PS-TKA for varus type OA knees, excessive tibial posterior slope was found to adversely affect one-year postoperative knee extension and clinical outcome including patient satisfaction and symptom. Surgeons should aware of the importance of tibial slope on one-year postoperative clinical results and pay more attentions to the posterior tibial slope angle not to be excessive

INTRODUCTION. The functional and anatomical results of TKA revisions are less good than a primary TKA. The TKA revision frequency increases and we must improve our surgeries and prepare the next standard of these surgeries. The aim of this study was to evaluate the CAOS / one stage strategie to treat the knee PJIs. MATERIALS. In this prospective study, between September 2011 and December 2014, 41 patients treated for chronic knee PJI in a one stage revision. For all of them, an imageless CAOS system (ExactechGPS, Blue- Ortho, Gieres) was used. A personalised profile of revision was created. All surgeries were performed with the same protocole and by using the same Optetrak CC knee components (Exactech, Gainesville, FL). All operations were performed by a single senior surgeon. Indications for the revision TKA were (1) revision of a primary TKA or unicondylar knee arthroplasty (n=27) or (2) revision of revisionTKA (n=15). The measurement of the HKA angle, the Oxford score and the ROM were evaluated pre and post- operatively. RESULTS. 27 males and 14 females with an average age of 71 years old (55–87) were treated for a PIJ (1 unicompartimental prosthesis, 26 TKA and 15 RTKA). The mean follow-up was 41 months (30 months − 6 years). The average time of surgery was 135 mn (120–195) for an average hospitalisation duration of 10 days (7–16). No postoperative outliers were reported (mean preop.: −1,6°+/_−5,1° − Post- op. −0,3°+/_ −1,4°). The average ROM were 115° (90–130°) (Fig. 1). The rate of success for the infection was 92,7%. We report no specific CAS complications and all the navigations were finalised. In this series of complex cases, the rate of infection healing is 92,7%. DISCUSSION. Using CAOS is a safe option with no specific complication. Combined with one stage procedures, it should be an optimal medico-economical strategy for Knee revisions. This first series initiated the « GPS RTKA » project to create a dedicated software evaluated since January 2016 with immediate very good functional results and no complications. For figures and tables, please contact authors directly

PURPOSE. Lateral osteoarthritis of the valgus knee is a challenging problem, especially for young and active patients, where prosthetic replacement is not indicated. The purpose of the present study is to evaluate clinically and radiographically 91 patients with valgus knee treated with distal femoral varus osteotomy in mid and long term follow-up. METHODS. A clinical retrospective evaluation based on IKDC, OXFORD and WOMAC scores of 91 patients at 4 to 10 years of follow-up was performed. Subjective evaluation was based on a VAS for pain self-assessment. Radiographic evaluation was performed by an independent observer of all 91 patients at 2 to 6 years of follow-up. A survival analysis was performed assuming revision for any reason as primary endpoint. RESULTS. The present study reported a marked improvement in clinical score at a mean 8,3 years of follow-up with statistical significance (p<0.005). The radiographic evaluation revealed a reduction of 7,0° and 4,2° of FTA and HKA angles respectively (p<0.05) at a mean follow up of 4,3 years, while small differences were observed with TPA and PTS angles. The 8-years treatment survivorship was 95,6%. CONCLUSIONS. The present study demonstrates that distal femoral varus osteotomy is an effective and reliable option to manage lateral tibio-femoral compartment early degenerative joint disease in young- to middle-age patients, providing a satisfactory clinical improvement at a mean follow-up of 8 years. Furthermore, its survivorship at 8-years follow-up is over 95%

A comparative study on CT- and MRI-based patient specific matched guides (PSG) from the same manufacturer for the implantation of total knee arthroplasty (TKA) has not been undertaken. A total of 64 knees operated with CT based PSG was divided into two groups, with (n=32, CT. HK. ) or without (n=32, CT. NA. ) a history of a knee operation, and matched with a control group operated with MRI based PSG(n=64). Alignment of the biomechanical axis of the leg (HKA angle) and accuracy of individual implant alignment were measured on digital long-standing AP and sagittal radiographs. HKA and implant angles <3° deviation of the preoperative planned alignment were defined as correct. Peroperative implant size, OR time (min) and blood loss (ml) were compared. The average HKA angle in the CT. HK. group (177.0, 170.5 to 181.5, p=0.016) and mean varus-valgus alignment of the tibia component in the MRI group (90.6, 85.6 to 94.1, p=0.003) were statistically significant different. None of the outcome on the frontal femoral and lateral tibial component were statistically significant different. Percentage <3° deviation of the preoperative planned femoral flexion-extension alignment was better in the MRI group (84%, p=0.002), compared to the CT. HK. and CT. NA. group (respectively 30% and 42%). Average operation time was statistically significant shorter in favour of the MRI group (53.1, 34 to 80, p≤0.00), compared to the CT. HK. (70.8, 44 to 114) and CT. NA. group (59.2, 41 to 78). There is discrepancy between CT and MRI based PSG from the same manufacture because of patients who were not suitable for MRI due to history of a knee operation in the past. Whether these differences are clinically relevant is questionable. Future research needs to emphasise whether one of these two modalities, MRI or CT is superior compared to the other

Objective. To explore whether good postoperative alignment could be obtained through simple individual valgus resection angle using common instruments in total knee arthroplasty with lateral bowing femur. Methods. Data of 46 TKAs with lateral bowing femur were collected prospectively, the center of the femoral intercondylar notch was the fixed drilling hole whether preoperative planning or intraoperative implementing. The intramedullary rod was put into the femur as deep as possible, until completely entrance or the distal point of the rod contact with the lateral cortical bone of the femur, which prevent the further entrance of the rod. Individual valgus resection angle ranging from 7°to 9°was performed according to preoperative planning, followed by meticulous assessment of matching between cutting surface and valgus resection angle. Postoperative hip-knee-ankle (HKA) angle?medial tibial plate angle and position of lower extremity alignment passing through the tibial plate were measured. Results. The preoperative measurement valgus resection angle include 14 cases of 8°, 13 cases of 9°, 5 cases of 10°, 2 case of 11°. The postoperative mean medial tibial plate angle was 89.5°±0.5°, mean HKA angle was 179.3°±0.8°. 27(79.4%), 23(67.6%) and 16 (47.1%) cases had restoration of mechanical axis to ±3°, ±2°and ±1°of neutral respectively, and there were 7 (15.2%) outlier (±3°). Excluding 3 cases of actual performed 9°valgus resection angle while preoperative measurement larger than 9°, both components were aligned within 3° of neutral in 88.2% of the knees. 27 (79.4%) cases had lower extremity alignment passing through the middle third of tibial plate, 7 (20.6%) cases pass through the medial third of the tibial plate. Conclusions. Excellent postoperative alignment could be obtained through simple individual valgus resection angle using common instruments in total knee arthroplasty with lateral bowing femur

Although total knee arthroplasty (TKA) is a largely successful procedure to treat end-stage knee osteoarthritis (OA), some studies have shown postoperative abnormal knee kinematics. Computer assisted orthopaedic surgery (CAOS) technology has been used to understand preoperative knee kinematics with an open joint (arthrotomy). However, limited information is available on the impact of arthrotomy on the knee kinematics. This study compared knee kinematics before and after arthrotomy to the native knee using a CAOS system. Kinematics of a healthy knee from a fresh frozen cadaver with presumably intact PCL were evaluated using a custom software application in an image-free CAOS system (ExactechGPS, Blue-Ortho, Grenoble, FR). At the beginning of the test, four metal hooks were inserted into the knee away from the joint line (one on each side of the proximal tibia and the distal femur) for the application of 50N compressive load to simulate natural knee joint. Prior to incision, one tracker was attached to each tibia and femur on the diaphysis. Intact knee kinematics were recorded using the CAOS system by performing passive range of motion 3 times. Next, a computer-assisted TKA procedure was initiated with acquisition of the anatomical landmarks. The system calculated the previously recorded kinematics within the coordinate system defined by the landmarks. The test was then repeated with closed arthrotomy, and again with open arthrotomy with patella maintained in the trochlea groove. The average femorotibial AP displacement and rotation, and HKA angle before and after knee arthrotomy were compared over the range of knee flexion. Statistical analysis (ANOVA) was performed on the data at ∼0° (5°), 30°, 60°, 90° and 120° flexion. The intact knee kinematics were found to be similar to the kinematics with closed and open arthrotomy. Differences between the three situations were found, in average, as less than 0.25° (±0.2) in HKA, 0.7mm (±0.4) in femorotibial AP displacement and 2.3° (±1.4) in femorotibial rotation. Although some statistically significant differences were found, especially in the rotation of the tibia for low and high knee flexion angles, the majority is less than 1°/mm, and therefore clinically irrelevant. This study suggested that open and closed arthrotomy do not significantly alter the kinematics compared to the native intact knee (low RMS). Maintaining the patella in the trochlea groove with an open arthrotomy allows accurate assessment of the intact knee kinematics