The efficacy and safety of the tourniquet are discussed, in particular with regard to the blood saving and tissue damage induced by ischemia. The quality of exsanguination and tissue necrosis in the compression zone are significant prognostic factors. The objective of this study was to evaluate the efficacy and safety of a new tourniquet system combining efficient and controlled exsanguination (figure 1) and ischemia maintained by pressure on a minimal surface (figure 2). The hypothesis tested was that the new system allowed tourniquet to reduce blood loss compared to conventional withers without increasing the risk of complications. Two groups of 30 patients undergoing total knee arthroplasty (TKA) were compared. There were 39 women and 21 men with a mean age of 67 years and a mean BMI of 34. The study group was operated with the innovative tourniquet and followed prospectively. The control group was operated with the traditional tourniquet and analyzed retrospectively.INTRODUCTION
MATERIAL
An appropriate positioning of a total knee replacement (TKR) is a prerequisite for a good functional outcome and a prolonged survival. Navigation systems may facilitate this proper positioning. Patient specific templates have been developed to achieve at least the same accuracy than conventional instruments at a lower cost. We hypothesised that there was no learning curve at our academic department when using patient specific templates for TKR instead of the routinely used navigation system. The first 20 patients operated on for TKR at our academic department using a patient specific template entered the study. All patients had a pre-operative CT-scan planning with a dedicated software. The patient specific templates were positioned on the bone according to the best fit technique. The position of the templates was controlled at each step of the procedure by the navigation system, and eventually corrected to achieve the expected goal. The discrepancy between the initial and the final positioning was recorded. The paired difference between each set of measurement was analysed with appropriate statistical tests at a 0.05 level of significance.Introduction
Material
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.
Total knee arthroplasty (TKA) is an effective technique to treat end-stage knee osteoarthritis, targeting the restore a physiological knee kinematics. However, studies have shown abnormal knee kinematics after TKA which may lead to suboptimal clinical outcomes. Posterior slope of the tibial component may significantly impact the knee kinematics. There is currently no consensus about the most appropriate slope. The goal of the present study was to analyse the impact of different prosthetic slopes on the kinematics of a PCL-preserving TKA, with the hypothesis that posterior slopes can alter the knee kinematics. A PCL-retaining TKA (Optetrak CR, Exactech, Gainesville, FL) was performed by a board-certified orthopaedic surgeon on one fresh frozen cadaver that had a non arthritic knee with an intact PCL. Intact knee kinematic was assessed using a computer-assisted orthopaedic surgery (CAOS) system (ExactechGPS®, Blue-Ortho, Grenoble, FR) Then, TKA components were implanted using the guidance of the CAOS system. The implanted tibial baseplate was specially designed to allow modifying the posterior slope without repeatedly removing/assembling the tibial insert with varying posterior slopes, avoiding potential damages to the soft-tissue envelope. Knee kinematic was evaluated by performing a passive range of motion 3 separate times at each of the 4 posterior slopes: 10°, 7°, 4° and 1°, and recorded by the navigation system. Femorotibial rotation, antero-posterior (AP) translation and hip-knee-ankle (HKA) angle were plotted with regard to the knee flexion angle. Tibial slopes of 1° and 4° significantly altered the normal rotational kinematics. Tibial slopes of 7° and 10° led to a kinematics close to the original native knee. All tibial slopes significantly altered the changes in HKA before 90° of knee flexion, without significant difference between the different slopes tested. The magnitude of change was small. There was no significant change in the AP kinematics between native knee and all tested tibial slopes. Changing the tibial slope significantly impacted the TKA kinematics. However, in the implant studied, only the rotational kinematics were significantly impacted by the change in tibial slope. Tibial slopes of 7° and 10° led rotational kinematics that were closest to that of a normal knee. Alterations in knee kinematics related to changing tibial slope may be related to a change in the PCL strain. However, these results must be confirmed by other tests involving more specimens.
How to position a unicompartmental knee replacement (UKR) remains a matter of debate. We suggest an original technique based on the intra-operative anatomic and dynamic analysis of the operated knee by a navigation system, with a patient-specific reconstruction by the UKR. The goal of the current study was to assess the feasibility of the new technique and its potential pitfalls. 100 patients were consecutively operated on by implantation of a UKR with help of a well validated, non-image based navigation system, by one single surgeon. There were 41 men and 59 women, with a mean age of 68 years (range, 51 to 82 years). After data registration, the navigation system provided the dynamic measurement of the coronal tibio-femoral mechanical angle in full extension. The reducibility of the deformation was assessed by a manually applied torque in the valgus direction. The patient-specific analysis was based on the following hypotheses: 1) The normal medial laxity in full extension is 2° (after previous studies), 2) there was no abnormal medial laxity (which may be routinely accepted for varus knees) and 3) the total reducibility is the sum of the patient's own medial laxity and of the bone and cartilage loss. We assumed that the optimal correction may be calculated by the angle of maximal reducibility, less 2° to respect the normal medial laxity. The bone resections were performed accordingly to this calculated goal. No ligamentous balance or retension was performed. The fine tuning of the remaining laxity was performed by adapting the height of polyethylene component with a 1 mm step. The final measurements (coronal tibio-femoral angle in full extension and medial laxity in full extension) were performed with the navigation system after the final components fixation. The implantation had to fulfill these two parameters: optimal correction as defined previously, and a 2 ± 1° of medial laxity.Objectives
Methods
The goal of this retrospective study was to compare two different processes of pain control after total knee arthroplasty (TKA): local anesthesia versus femoral nerve block. The tested hypothesis was that the patient's ability to be discharged was obtained sooner with the local anesthesia process. 110 patients consecutively operated on for TKA by a single surgeon without any selection criterion were included. The study group included 58 patients operated on under general anesthesia with infiltration of the surgical field with local anesthesia. The control group included 52 patients operated on under general anesthesia and continuous femoral nerve block. In the study group, 200 ml of ropivacaïne 5% were injected into the surgical field, and an intra-articular catheter was left to allow continuous infusion of ropivacaïne (20 ml/h during 24 hours). The control group was treated by a femoral nerve block with ropivacaïne during 24 hours. Discharge was considered allowed when the patient was able to walk independently, go upstairs and downstairs independently, when the knee flexed over 90° and if the subjective pain assessment (VAS) was under 3/10.Objectives
Methods
An optimal reconstruction of the joint anatomy and physiology during revision total knee replacement (RTKR) is technically demanding. The standard navigation systems were developed for primary procedures, and their adaptation to RTKR is difficult. We present a new navigation software dedicated to RTKR. The rationale of this new software was to allow a virtual planning of the joint reconstruction just after removal of the primary prosthesis. The new software was developed on the basis of a non-image based navigation system which has been extensively validated for implantation of a primary TKR. Following changes have been implemented: 1) to define and control the vertical level of the joint space on both tibia and femoral side; 2) to measure the tibio-femoral gaps independently in flexion et en extension on both medial and lateral tibio-femoral joints; 3) to virtually plan and control the vertical level and the orientation of the tibia component; 4) to virtually plan and control the sizing and the 3D positioning of the femoral component (figure 1); 5) to virtually plan and control the potential bone resection; 6) to virtually plan and control the potential bone defects and their reconstruction (bone graft or augments) (figure 2); 7) to virtually plan and control the size, the length and the orientation of the stems extensions independently on the femoral and on the tibia side (figure 3). The validity of the concept has been tested by 20 patients operated on for RTKR for any reason, with a routine reconstruction with a cemented, unconstrained revision implant. The accuracy of the experimental software was assessed 1) during the procedure after implantation of the RTKR by measuring the medial and lateral laxity in full extension and 90° of knee flexion with the navigation system, and 2) on post-operative radiographs.Objectives
Methods
The appropriate treatment for chronically infected TKR is controversial. One-stage exchange is believed to be possible only in selected cases, but the respective indications and contra-indications and the criteria of selection are not fully validated. We wanted to test the relevance of the commonly used selection criteria by comparing two groups of patients: the control group operated on with a routine one-stage exchange without selection criteria, and the study group operated on by one stage exchange on selected patients only. We hypothesized that selected one-stage exchange gives fewer failures than routine one-stage exchange procedure. We performed a retrospective study of 108 cases selected in a database of 600 patients with an infected total knee arthroplasty. The database resulted from a French multicenter trial of specialized surgeons in reference institutions, including all consecutive cases operated on between 2000 and 2010. There were 64 women and 44 men with a mean age of 69 years. All patients were followed-up for a minimal period of two years or when septic failure occurred. The patients were divided into two groups: patients operated on in a center using a routine one-stage exchange policy, and patients operated on in a center using a selected one-stage exchange policy. Patients were matched in the two groups according to body mass index and the aspect of the wound at the initial examination (one scar, several scars, presence of a fistula). The results were expressed as: free of infection, relapse or persistence of the index infection, occurrence of a new infection. The repartition was compared in the two groups by a Chi² test at a 0.05 level of significance. The cumulative survivorship was plotted with infection recurrence for any reason as the end point.Objectives
Methods
Quantification of the anterior and rotational laxity of the knee allows recognising an anterior cruciate ligament (ACL) insufficiency and assessing the severity of the lesion. The new GNRB system has demonstrated an improved accuracy and precision in the assessment of the anterior laxity. However, it is not known if this pre-operative measurement is a good predictor of the intra-operative measurement of the knee laxity, especially in the rotational plane. We tested the following hypotheses: 1) the pre-operative anterior knee laxity measured with the GNRB system is predictive for the intra-operative measurement of the anterior knee laxity by a navigation system, and 2) the pre-operative anterior knee laxity measured with the GNRB system is predictive for the intra-operative measurement of the rotational knee laxity by a navigation system, 40 patients operated on for ACL reconstruction were included. The anterior knee translation was assessed before the operation with the GNRB system with a force of 250 N at 25° of knee flexion. The anterior knee translation and the internal-external range of rotation was measured intra-operatively before and after ACL reconstruction with the navigation system. The correlation between 1) the measurements of the anterior laxity by the GNRB system and the navigation system, and 2) the measurements of the anterior translation by the GNRB system and the rotational knee motion measured by the navigation system, were assessed. There was a significant difference between the measurements of the mean knee anterior laxity by the GNRB system (9.1 ± 2.9 mm) and by the navigation system (11.3 ± 4.0 mm) (p<0.001). There was no significant correlation between the two techniques (R2 = 0.01). However, a satisfactory agreement between the two techniques was observed (R2 = 0.03), with a systematic bias of −3.3 mm for GNRB measurements in comparison to navigated measurements. There was neither significant correlation nor satisfactory agreement between the two techniques when predicting the rotational motion of the knee. When used prior to ACL reconstruction, the GNRB system underestimates the anterior laxity of the knee that will be measured during the reconstruction by a navigation system, and does not predict the amount of rotational laxity. It is difficult to predict accurately the anterior and rotational knee laxity by pre-operative measurements.
Modern total knee replacements aim to reconstruct a physiological kinematic behaviour, and specifically femoral roll-back and automatic tibial rotation. A specific software derived from a clinically used navigation system was developed to allow in vivo registration of the knee kinematics before and after total knee replacement. The study was designed to test for the feasibility of the intra-operative registration of the knee kinematics during standard, navigated total knee replacement. The software measures the respective movement of the femur and the tibia, and specially antero-posterior translation and tibial rotation during passive knee flexion. Kinematic registration was performed twice during an usual procedure of navigated total knee replacement: 1) Before any bone resection or ligamentous balancing; 2) After fixation of the final implants. 200 cases of total knee replacement have been analysed. Post-operative kinematic was classified as following: 1) Occurrence of a normal femoral roll-back during knee flexion, no roll-back or paradoxical femoral roll-forward. 2) Occurrence of a normal tibial internal rotation during knee flexion, no tibial rotation or paradoxical tibial external rotation. All patients were followed up for a minimal period of 12 months, and reevaluated at the latest follow-up visit for clinical and functional results with completion of the Knee Society Scores. Recording the kinematic was possible in all cases. The results of both pre-operative and post-operative registrations were analysed on a qualitative manner. The results were close to those already published in both experimental and clinical studies. About femoral roll-back, 54% had a normal femoral roll-back during knee flexion after total knee replacement, 13% had no significant roll-back and 33% had a paradoxical femoral roll-forward. About tibia rotation, 65% had a normal tibia internal rotation during knee flexion, 16% had no significant tibia rotation and 19 had a paradoxical tibia external rotation. The mean Knee Score was 92/100 ± 10 points. There was a significant correlation between the post-operative kinematic behaviour and the Function Score, with better score for the patients having a physiological femoral roll-back and a physiological tibial internal rotation during knee flexion (p<0.01). Intra-operative analysis of the kinematic of the knee during total knee replacement may offer the chance to modify the kinematic behaviour of the implant and to choose the best fitted constraint to the patient's native knee in order to impact positively the functional result.
To restore a physiologic kinematic is one of the goals of total knee replacement (TKR). This study compared the intra-operative registration of the knee kinematics during standard, navigated TKR performed either with a well validated floating platform design with posterior cruciate (PCL) preservation, or with a newly designed TKR with a rotating platform and PCL substitution. It was hypothesised that this new design will significantly alter the kinematic recorded after TKR implantation in comparison to the conventional design. A standard navigation software has been modified to allow the intra-operative registration of the knee kinematic during a flexion-extension movement before and after implantation. Kinematic registration was performed twice: 1) before any bone resection or ligamentous balancing; 2) after fixation of the final implants. Post-operative kinematic was classified as following: 1) Occurrence of a normal femoral roll-back during knee flexion, no roll-back or paradoxical femoral roll-forward. 2) Occurrence of a normal tibial internal rotation during knee flexion, no tibial rotation or paradoxical tibial external rotation. 20 patients were operated on with either the PCL preserving or sacrificing designs. The kinematic behaviour was compared on a patient specific basis before and after the TKR. About femoral roll-back, 54% had a normal femoral roll-back during knee flexion after total knee replacement, 13% had no significant roll-back and 33% had a paradoxical femoral roll-forward. About tibia rotation, 65% had a normal tibia internal rotation during knee flexion, 16% had no significant tibia rotation and 19 had a paradoxical tibia external rotation. There was no difference of repartition between the two designs. The new software allows actually validating new designs of a TKR in terms of intra-operative kinematic behaviour.
Leg length discrepancy is a significant concern after total hip replacement (THR). We hypothesised that the intra-operative use of a navigation system was able to accurately control the leg length during THR. 50 cases have been prospectively analysed. There were 29 men and 21 women, with a mean age of 66.1 years (range, 50 to 80 years), all operated on for THR for end-stage hip osteoarthritis.Introduction
Material
An optimal reconstruction of the joint anatomy and physiology during revision total knee replacement (RTKR) is technically demanding. A new software was developed to allow a virtual planning of the joint reconstruction just after removal of the primary prosthesis. Following changes have been implemented to the standard navigation software: 1) to define and control the vertical level of the joint space on both tibia and femoral side, and to allow performing the potential change decided prior to the revision procedure according to the preoperative imaging planning; 2) to measure the tibio-femoral gaps independently in flexion et en extension on both medial and lateral tibio-femoral joints; 3) to virtually plan and control the vertical level and the orientation of the tibia component; 4) to virtually plan and control the sizing and the 3D positioning of the femoral component; 5) to virtually plan and control the potential bone resection; 6) to virtually plan and control the potential bone defects and their reconstruction (bone graft or augments); 7) to virtually plan and control the size, the length and the orientation of the stems extensions independently on the femoral and on the tibia side.Introduction
Material
We wanted to assess the possible correlation between the intra-operative kinematics of the knee and the clinical results after total knee replacement (TKR). 187 cases of TKR implanted with help of a navigation system for end-stage osteoarthritis have been prospectively analyzed. There were 127 women and 60 men, with a mean age of 71.4 years. Indication for TKR was osteoarthritis in 161 cases and inflammatory arthritis in 26 cases.INTRODUCTION
MATERIAL
The magnitude of knee flexion angle is a relevant information during clinical examination of the knee, and this item is a significant part of every knee scoring system. It is generally performed by visual analysis or with manual goniometers, but these techniques may be neither precise nor accurate. More sophisticated techniques are only possible in experimental studies. Smartphone technology might offer a new way to perform this measurement with increased accuracy. 20 patients operated on for unicompartmental or total knee replacement with help of a navigation system participated to the study. There were 13 women and 7 men with a mean age of 72.1 years.INTRODUCTION
MATERIAL
Polyethylene wear is one of the reasons for failure of total knee replacement (TKR). There are several reasons for wear, and the femoro-tibial contact area is an important factor. Mobile bearing, highly congruent prostheses might be more resistant to polyethylene wear than fixed bearing, incongruent prostheses. We evaluated the 5- to 8-year experience of three university departments by using an original system with following highlights: implantation with a navigation system, extended congruency up to 90° of flexion, floating polyethylene component with non-limited movements of rotation, antero-posterior translation and medio-lateral translation. 347 patients have been operated on in the three participating departments with this new prosthesis system between 2001 and 2004, and have been prospectively followed with clinical and radiologic examination with a minimal follow-up time of 5 years. There were 246 women and 101 men, with a mean age of 67 years.INTRODUCTION
MATERIAL
Polyethylene wear is one of the reasons for failure of total knee replacement (TKR). There are several reasons for wear, and the femoro-tibial contact area is an important factor. Mobile bearing, highly congruent prostheses might be more resistant to polyethylene wear than fixed bearing, incongruent prostheses. We evaluated the five- to eight-year experience of three university departments by using an original system with following highlights: implantation with a navigation system, extended congruency up to 90° of flexion, floating polyethylene component with non-limited movements of rotation, antero-posterior translation and medio-lateral translation. 347 patients have been operated on in the three participating departments with this new prosthesis system between 2001 and 2004, and have been prospectively followed with clinical and radiologic examination with a minimal follow-up time of five years. There were 246 women and 101 men, with a mean age of 67 years. Clinical and functional results have been analyzed according to the Knee Society scoring system. Accuracy of implantation has been assessed on post-operative long leg antero-posterior and lateral X-rays. Survival rate up to eight years has been calculated according to Kaplan and Meier, with mechanical revision or any revision as end-points. Complete patient history was obtained by 319 cases (92%). The mean clinical score was 93 points. The mean pain score was 47 points. The mean flexion angle was 118°. The mean functional score was 87 points. An optimal correction of the coronal femoro-tibial axis was obtained in 94% of the cases. Survival rate after eight years was 98.8% for mechanical revisions and 95.5% for all revisions. We confirmed the influence of the navigation system on the accuracy of implantation. The clinical and functional results after five to eight years are in line with the better results of the current literature after conventional implantation of non-congruent prostheses. The survival rate is comparable to the current standards. The influence of the design on polyethylene wear will need a longer follow-up.
We wanted to assess the possible correlation between the intra-operative kinematics of the knee and the clinical results after total knee replacement (TKR). 187 cases of TKR implanted with help of a navigation system for end-stage osteoarthritis have been prospectively analyzed. There were 127 women and 60 men, with a mean age of 71 years. Indication for TKR was osteoarthritis in 161 cases and inflammatory arthritis in 26 cases. A floating platform, PCL preserving, cemented TKR was implanted in all cases. A non-image based navigation system was used in all cases to help for accuracy of bone resections and ligamentous balancing. The standard navigation system was modified to allow recording the three-dimensional tibio-femoral movement during passive knee flexion during the surgical procedure. Two sets of records have been performed: before any intra-articular procedure and after final implantation. Only antero-posterior femoral translation (in mm) and internal-external femoral rotation (in degrees) have been recorded. Kinematic data have been analyzed in a quantitative manner (total amount of displacement) and in a qualitative manner (restoration of the physiological posterior femoral translation and femoral external rotation during knee flexion). Clinical and functional results have been analysed according to the Knee Society scoring system with a minimal follow-up of one year. Statistical links between kinematic data and Knee Society scores have been analysed with an ANOVA test and a Spearman correlation test at a 0.05 level of significance. 101 knees had a posterior femoral translation during flexion before and after TKR. 18 knees had a paradoxical anterior femoral translation during flexion before and after TKR. 51 knees had the pre-TKR paradoxical anterior femoral translation corrected to posterior femoral translation after TKR. 14 knees had the pre-TKR posterior femoral translation modified to a paradoxical anterior femoral translation after TKR. 91 knees had a femoral external rotation during flexion before and after TKR. 34 knees had a paradoxical femoral internal rotation during flexion before and after TKR. 50 knees had the pre-TKR paradoxical femoral internal rotation corrected to a femoral external rotation after TKR. Nine knees had the pre-TKR femoral external rotation modified to a paradoxical femoral internal rotation after TKR. There was a moderate statistical link between the reconstruction of a physiological kinematics after TKR and the Knee Society scores, with higher scores in the group of physiological kinematics after reconstruction. There was no correlation between the quantitative data and the Knee Society scores. To record the knee kinematics during TKR is feasible. This information might help the surgeon choosing the optimal reconstruction compromise. However, it is not well defined how to influence final kinematics during knee replacement. The exact influence of the quality of the kinematic reconstruction measured during surgery on the clinical and functional results has to be investigated more extensively.
Surgical navigation in joint replacement has been developed for more than 10 years. After the initial enthusiastic period, it appears that few surgeons have included this technology into their routine practice. The reasons for this backflow are lack of evidence of any clinical superiority for navigation implanted prostheses, higher costs and longer operative time. However, navigation systems have evolved, and might still belong to the future of joint replacement. Although most studies did not observe clinically relevant differences between navigated and conventional joint replacement, some registry studies identified significant advantages in favor of navigation: less blood loss, less early revision, subtle but relevant functional improvement… If TKR may be more forgiving, there is a trend to use less invasive implants (UKR), which are technically more demanding and may benefit from navigation. Ligamentous balancing may be more accurate and more reproducible with the help of navigation, and in that way patient specific templates may benefit from navigation. New techniques (short stem hip implants, hip resurfacing) have a relevant learning curve which may be fastened with navigation support. Another key point may be the individual joint reconstruction: anatomy is different from one patient to the other, and navigation may help detecting these subtle differences to adapt a more physiological joint reconstruction, instead reconstructing all joints on the same model. New navigation systems now available are designed in a more user-friendly style, with more straightforward workflow, and may be adapted to every surgeon's need. Finally, navigation system may act as documentation and quality control system for health care providers, as well as a very powerful research tool for scientists and manufacturers.
Computer-aided systems have been developed recently in order to improve the precision of implantation of unicompartmental knee replacement (UKR). Minimal invasive techniques may decrease the surgical trauma related to the prosthesis implantation, but there might be a concern about the potential for a loss of accuracy. Mobile bearing prostheses have been developed to decrease the risk of polyethylene wear, but are technically more demanding. Navigation might help to compensate for these difficulties. We wanted to combine the theoretical advantages of the three different techniques by developing a navigated, minimal invasive, mobile bearing unicompartmental knee prosthesis. 160 patients have been operated on at our institution with this system. The 81 patients with more than 2 year follow-up have been re-examined. Complications have been recorded. The clinical results have been analyzed according to the Knee Society Scoring System. The subjective results have been analyzed with the Oxford Knee Questionnaire. The accuracy of implantation has been analyzed on post-operative antero-posterior and lateral long leg X-rays. The 2-year survival rate has been calculated.INTRODUCTION
MATERIAL AND METHODS
