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. 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.INTRODUCTION
MATERIAL – METHODS
Accurate diagnosis of peri-prosthetic joint infection is critical to allow adequate treatment. Currently, the criteria of the Musculo-Skeletal Infection Society (MSIS) serve as a validated reference tool. More recently, these criteria have been modified for better accuracy. The goal of this study was to compare retrospectively the diagnostic accuracy of these two different tools in cases of known peri-prosthetic hip or knee infection or in aseptic cases and to analyze one additional criterion: presence of an early loosening (prior to 2 years after implantation). All cases of hip or knee prosthesis exchange operated on at our department during the year 2017 have been selected. There were 130 cases in 127 patients: 67 men and 60 women, with a mean age of 69 years − 69 total hip (THA) and 61 total knee (TKA) arthroplasties. 74 cases were septic and 53 cases were aseptic. All criteria included in both classifications were collected: presence of a fistula, results of bacteriological samples, ESR and CRP levels, analysis of the joint fluid, histological analysis. Additionally, the presence of an early loosening was recorded. The diagnosis accuracy of the classical MSIS classification and of the 2018 modification were assessed and compared with a Chi-square test at a 0.05 level of significance.Introduction
Material – Methods
Chronic ruptures of the quadriceps tendon after total knee arthroplasty (TKA) are rare but are a devastating complication. The objective of this study was to validate the use of fresh frozen total fresh quadriceps tendon allografts for quadriceps tendon reconstruction. The hypothesis of this work was that the graft was functional in more than 67% of cases, a higher percentage than the results of conventional treatments. We designed a continuous monocentric retrospective study of all patients operated on between 2009 and 2017 for a chronic rupture of the quadriceps tendon after TKA by quadriceps allograft reconstruction. The usual demographic and perioperative data and the rehabilitation protocols followed were collected. Initial and final radiographs were analyzed to measure patellar height variation. The main criterion was the possibility of achieving an active extension of the knee with a quadriceps contraction force greater than or equal to 3/5 or the possibility of lifting the heel off the ground in a sitting position.Introduction
Material – methods
Deep venous thrombosis (DVT) is a potentially serious complication after total hip (THA) and knee (TKA) arthroplasty, traditionally justifying aggressive prophylaxis with low molecular weight heparin (LMWH) or direct oral anticoagulants (DOA) at the cost of an increased risk of bleeding. However, fast-track procedures might reduce the DVT risk and decrease the cost-benefit ratio of the current recommendations. The objective of this study was to compare thrombotic and bleeding risk in an unselected population of elective THA and TKA with a fast-track procedure. A series of 1,949 patients were analyzed prospectively. There were 1,136 women and 813 men, with a mean age of 70 years. In particular, 16% were previously treated by antiplatelet agents and 8% by anticoagulants. All patients followed a fast-track procedure including early walking within 24 hours of surgery, and 80% of patients returned home after surgery, with a mean length of stay of 3 days (THA) or 4 days (TKA). The occurrence of a thromboembolic event or hemorrhagic complication has been identified.Introduction
MATERIAL - METHODS
Bone and joint infections (BJI) are associated with a heavy morbidity and high health costs. Comorbidities, device associated infections and complicated journeys are associated with increased mortality, treatment failures and costs. For this reason, 24 referral centers (RC) have been created in 2009 in order to advise about management of “complex” BJI in weekly multidisciplinary meetings (MM). Since end of 2012, data from these meetings are gathered in a national database. We aimed to describe the data from this French registry of BJI and determine factors associated with the definition of “complex” BJI. Demographic, clinical, microbiologic and therapeutic characteristics of patients are systematically recorded in the database. Data from the first presentation in RC for each adult patients are presented. Complexity of BJI is recorded after each meeting according to 4 criteria (first failure, complex antibiotic therapy, precarious underlying conditions or complex surgical procedure). Part of unavailable data have been completed by pattern extraction from text-encoded commentaries. Factors associated with complexity were determined by multivariate logistic regression.Aim
Method
Navigation systems have proved allowing performing measurement of the lower limb axis with a good accuracy, but the mandatory use of reference pins or screws limit their use to the operating room. The use of non-invasive navigation systems has been suggested to overcome this limitation. We conducted a prospective study to assess the validity of such a measurement system with non-invasive fixation of the reference arrays. The main goal was to compare this method with a standard, invasive navigation system requiring bony fixation of the arrays. The following hypothesis was tested: there will be a significant difference between the simultaneous measurement of the mechanical femoro-tibial angle by a standard navigation system and by the non-invasive navigation system. 20 patients scheduled for total or partial knee arthroplasty were included after giving their informed consent. There were 7 men and 13 women with a median age of 65 years (range, 55 to 90). The median coronal deformation measured by X-rays was 8° of varus (range, 5° valgus to 22 ° varus). The same navigation system was used for both invasive and non-invasive measurements, but the basic algorithms were adapted for the non-invasive technique. For the non-invasive technique, metallic plates were strapped on the thigh and the calf to allow arrays fixation (fig. 1). Coronal femoro-tibial mechanical angle (CMFA) in maximal extension without stress was recorded by the non invasive system. This non-invasive analysis was immediately followed by surgery, and the same angle was measured intra-operatively with the invasive system. Comparisons between non-invasive and invasive measurements were performed using a Wilcoxon test, after checking that their distribution followed a normal distribution, and an equivalence testing with limits of ±3°. The correlation between the two sets of measurements was analyzed using a correlation test Spearman rank. The analysis of the concordance of the two sets of measurements was performed using Bland and Altman tests. The significance level INTRODUCTION
MATERIAL AND METHODS
Total knee arthroplasty (TKA) is considered a highly successful procedure. Survival rates of more than 90% after 10 years are generally reported. However, complications and revisions may still occur for many reasons, and some of them may be related to the operative technique. Computer assistance has been suggested to improve the accuracy of implantation of a TKA (Jenny 2005). Short term results are still controversial (Roberts 2015). However, few long term results have been documented (Song 2016). The present study was designed to evaluate the long-term (more than 10 years) results of a TKA which was routinely implanted with help of a non-image based navigation system. The 5- to 8-year of this specific TKA has already been documented (Jenny 2013). The hypothesis of this study will be that the 10 year survival rate of this TKA will be improved in comparison to historical papers when analyzing survival rates and knee function as evaluated by the Knee Society Score (KSS). All patients operated on between 2001 and 2004 for implantation of a navigated TKA were eligible for this study. Usual demographic and peri-operative items have been record. All patients were prospectively followed with clinical and radiological examination. All patients were contacted after the 10 year follow-up for repeat clinical and radiological examination (KSS, Oxford knee questionnaire and knee plain X-rays). Patients who did not return were interviewed by phone call. For patients lost of follow-up, family or general practitioner was contacted to obtain relevant information about prosthesis survival. Survival curve was plotted according to Kaplan-Meier.INTRODUCTION
MATERIAL AND METHODS
The goal of the study was to perform quality control with a commercially available navigation system when introducing PST technique at our academic department. The learning curve was assessed by the Cumulative Sum (CUSUM) test. We hypothesized that the PST process for TKA was immediately under control after its introduction when analyzed with the CUSUM technique. The first 50 TKAs implanted with the use of PST at an academic department were scheduled to enter in a prospective, observational study. All TKAs were implanted by an experienced, high volume senior consultant with high experience in knee navigation. PSTs were carefully positioned over the bone and articular surfaces to the best fit position, without any navigated information. Then the 3D femoral and tibia PSTs positioning were recorded. The surgical procedure was then completed following the routine navigated procedure with standard navigated templates. To assess the 3D positioning of each template individually and of both templates together as a surrogate of the final TKA positioning, one point was given for each item inside the target, giving a maximal femur and tibia scores of 4 points, and a maximal knee score of 8 points, when all items were fulfilled. Following dataset was used for CUSUM chart plotting: allowable slack = 0.5SD, acceptable limit score = 6 points for knee score and 2 points for femur and tibia scores. For each measurement Mx, two CUSUMs (upper and lower CUSUMs) were calculated. These sums were plotted against the rank of the observation i. A trend in the process results in a change in the slope of the CUSUM, whereas the values are expected to fluctuate around a horizontal line if the process is in control. The process was considered out of control if upper CUSUM or lower CUSUM is outside the acceptable deviation interval.INTRODUCTION
MATERIAL AND METHODS
The patient-specific templates (PST) for total knee arthroplasty (TKA) have been developed to improve accuracy of implantation, decrease operating time and decrease costs. There remains controversy about the accuracy of PST in comparison with either navigated or conventional instruments. Furthermore, the learning curve after introducing PST has not been well defined. The goal of the present study was to perform quality control with a commercially available navigation system and the CUCUM test when introducing PST technique at our academic department. The first 50 TKAs implanted with the use of PST at an academic department were scheduled to enter in a prospective, observational study. PSTs were designed to obtain a neutral coronal alignment. All TKAs were implanted by an experienced, high volume senior consultant with high experience in knee navigation. PSTs were carefully positioned over the bone and articular surfaces to the best fit position, without any navigated information. Then the 3D femoral and tibia PSTs positioning were recorded by the navigation system. The difference between expected and achieved position was calculated, and an accuracy score was calculated and plotted according to the rank of observation into a CUSUM test.INTRODUCTION
MATERIAL AND METHODS
Unicompartmental knee arthroplasty (UKA) is considered a highly successful procedure. However, complications and revisions may still occur, and some may be related to the operative technique. Computer assistance has been suggested to improve the accuracy of implantation of a UKA. The present study was designed to evaluate the long-term (more than 10 years) results of an UKA which was routinely implanted with help of a non-image based navigation system. All patients operated on between 2004 and 2005 for implantation of a navigated UKA were included. Usual demographic and peri-operative items have been record. All patients were prospectively followed with clinical and radiological examination. All patients were contacted after the 10 year follow-up for repeat clinical and radiological examination (KSS, Oxford knee questionnaire and knee plain X-rays). Patients who did not return were interviewed by phone call. For patients lost of follow-up, family or general practitioner was contacted to obtain relevant information about prosthesis survival. Survival curve was plotted according to Kaplan-Meier.INTRODUCTION
MATERIAL AND METHODS
Whether pre-operative microbiological sampling contributes to the management of chronic peri-prosthetic infection remains controversial. We assessed agreement between the results of pre-operative and intra-operative samples in patients undergoing single-stage prosthesis exchange to treat chronic peri-prosthetic infection. The tested hypothesis was that agreement between pre-operative and intra-operative samples exceeds 75% in patients undergoing single-stage exchange of a hip or knee prosthesis to treat chronic peri-prosthetic infection. This single-centre retrospective study included 85 single-stage prosthesis exchange procedures in 82 patients with chronic peri-prosthetic infection at the hip or knee. Agreement between pre-operative and intra-operative sample results was evaluated. Changes to the initial antibiotic regimen made based on the intra-operative sample results were recorded. Associations between sample agreement and infection-free survival were assessed.Aim
Method
The diagnosis of peri-prosthetic infection is sometimes difficult to assess, and there is no universal diagnostic test. The recommendations currently accepted include several diagnostic criteria, and are based mainly on the results of deep bacteriological samples, which only provide the diagnosis after surgery. A predictive score of the infection might improve the peri-operative management before repeat surgery after total hip arthroplasty (THA). The goal of this study was to attempt defining a composite score using conventional clinical, radiological and biological data that can be used to predict the positive and negative diagnosis of peri-prosthetic infection before repeat surgery after THA. The tested hypothesis was that the score thus defined allowed an accurate differentiation between infected and non-infected cases in more than 75% of the cases. 104 cases of repeat surgery for any cause after THA were analyzed retrospectively: 61 cases of infection and 43 cases without infection. There were 54 men and 50 women, with a mean age of 70 ± 12 years (range, 30 to 90 years). A univariate analysis looked for individual discriminant factors between infected and uninfected case file records. A multivariate analysis integrated these factors concomitantly. A composite score was defined, and its diagnostic effectiveness was assessed by the percentage of correctly classified cases and by sensitivity and specificity.Aim
Method
Total knee arthroplasty (TKA) can effectively treat end-stage knee osteoarthritis. For cruciate-retaining (CR) TKA, the posterior tibial slope (PTS) of the reconstructed proximal tibia plays a significant role in restoring normal knee kinematics as it directly affects the tension of the posterior cruciate ligament (PCL) [1]. However, conventional cadaveric testing of the impact of PTS on knee kinematics may damage/stretch the PCL, therefore impact the test reproducibility. The purpose of this study was to assess the reproducibility of a novel method for the evaluation of the effects of PTS on knee kinematics. Cemented CR TKAs (Logic CR, Exactech, Gainesville, FL, USA) were performed using a computer-assisted surgical guidance system (ExactechGPS®, Blue-Ortho, Grenoble, FR) on six fresh frozen non-arthritic knees (PCL presumably intact). The tibial baseplate was specially designed (Fig. 1) with a mechanism to modify the PTS in-situ. Knee kinematics, including anteroposterior (AP) translation, internal/external (IE) rotation, and hip-knee-ankle angles, were evaluated by performing a passive range of motion from extension up to ∼110° of flexion, three separate times at 5 PTSs: 10°, 7°, 4°, 1°, and then 10° again. The repeatability of the test was investigated by comparing the kinematics between the first and the last 10° tests. Any clinically relevant deviation (1.5° for the hip knee ankle angle, 1.5mm for anterior-posterior translation and 3° for internal-external rotation) would reflect damage to the soft-tissue envelope or the PCL during the evaluation. Potential damage of PCL was investigated by comparing the kinematic parameters from the first and last 10° slope tests at selected flexion angles (Table 1) by paired t-test, with statistical significance defined as p<0.05.Introduction
Materials and Methods
While total knee arthroplasty (TKA) improves postoperative function and relieves pain in the majority of patients with end stage osteoarthritis, its ability to restore normal knee kinematics is debated. Cadaveric studies using computer-assisted orthopaedic surgery (CAOS) system [1] are one of the most commonly used methods in the assessment of post-TKA knee kinematics. Commonly, these studies are performed with an open arthrotomy; which may impact the knee kinematics. The purpose of this cadaveric study was to compare the knee kinematics before and after (open or closed) arthrotomy. Kinematics of seven non-arthritic, fresh-frozen cadaveric knees (PCL presumably intact) was evaluated using a custom software application in an image-free CAOS system (ExactechGPS, Blue-Ortho, Grenoble, FR). Prior to the surgical incision, one tracker was attached to the diaphysis of each tibia and femur. Native intact knee kinematics was then assessed by performing passive range of motion (ROM) three separate times, from full extension to at least 110 degrees of flexion, with the CAOS system measuring and recording anatomical values, including flexion angle, internal-external (IE) rotation and anterior-posterior (AP) translation of the tibia relatively to the femur, and the hip-knee-ankle (HKA) angle. Next, an anterior incision with a medial parapatellar arthrotomy was performed, followed by acquisition of the anatomical landmarks used for establishing an anatomical coordinate system in which all the anatomical values were evaluated [2]. The passive ROM test was then repeated with closed and then open arthrotomy (patella manually maintained in the trochlea groove). The anatomical values before and after knee arthrotomy were compared over the range of knee flexion using the native knee values as the baseline.Introduction
Materials and Methods
One of the main goals of total knee arthroplasty (TKA) is to restore an adequate range of motion. The posterior femoral offset (PFO) may have a significant influence on the final flexion angle after TKA. The purpose of the present study was to compare the conventional, radiologic measurement of the PFO before and after TKA to the intra-operative, navigated measurement of the antero-posterior femoral dimension before and after TKA implantation. 100 consecutive cases referred for end-stage knee osteo-arthritis have been included. Inclusion criteria were the availability of pre-TKA and post-TKA lateral X-rays and a navigated TKA implantation. There was no exclusion criterion.INTRODUCTION
MATERIAL
Cemented total knee arthroplasty (TKA) is a widely accepted treatment for end-stage knee osteoarthritis. During this procedure, the surgeon targets proper alignment of the leg and balanced flexion/extension gaps. However, the cement layer may impact the placement of the component, leading to changes in the mechanical alignment and gap size. The goal of the study was to assess the impact of cement layer on the tibial mechanical alignment and joint gap during cemented TKA. Computer-assisted TKAs (ExactechGPS®, Blue-Ortho, Grenoble, FR) were performed by two fellowship trained orthorpaedic surgeons on five fresh-frozen non-arthritic pelvis-to-ankle cadaver legs. All the surgeries used a cemented cruciate retaining system (Optetrak Logic CR, Exactech, Gainesville, FL). After the bony resection, the proximal tibial resection plane was acquired by manually pressing an instrumented checker onto the resected tibial surface (resection plane). Once the prosthesis was implanted through standard cementing techniques, the top surface of the implanted tibial component was probed and recorded using an instrumented probe. A best fit plane was then calculated from the probed points and offset by the thickness of the prosthesis, representing the bottom plane of the component (component plane). The deviation of component alignment caused by the cement layer was calculated as the coronal and sagittal projection of the three-dimensional angle between the resection plane and the component plane. The deviation of the component height, reflecting a change in the joint gap, was assessed as the distance between the two planes calculated at the lowest points on the medial and lateral compartments of the proximal tibial surface. Statistical significance was defined as p≤0.05.INTRODUCTION
MATERIAL
Total knee arthroplasty (TKA) is an effective technique to treat end-stage osteoarthritis of the knee. One important goal of the procedure is to restore physiological knee kinematics. However, fluoroscopy studies have consistently 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 after TKA. There is currently no consensus about the most appropriate slope. The goal of the present study was to analyze the impact of different prosthetic slopes on the kinematics of a PCL-preserving TKA. The tested hypothesis was that the knee kinematics will be different for all tested tibial slopes. PCL-retaining TKAs (Optetrak Logic CR, Exactech, Gainesville, FL) were performed by fellowship trained orthopedic surgeons on six fresh frozen cadaver with healthy knees and intact PCL. The TKA was implanted using a computer-assisted surgical navigation system (ExactechGPS®, Blue-Ortho, Grenoble, FR). The implanted tibial baseplate was specially designed (figure 1) 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.INTRODUCTION
MATERIAL
Measurement of range of motion is a critical item of any knee scoring system. Conventional measurements used in the clinical settings are not as precise as required. Smartphone technology using either inclinometer application or photographic technology may be more precise with virtually no additional cost when compared to more sophisticated techniques such as gait analysis or image analysis. No comparative analysis between these two techniques has been previously performed. The goal of the study was to compare these two technologies to the navigated measurement considered as the gold standard. Ten patients were consecutively included. Inclusion criterion was implantation of a TKA with a navigation system.INTRODUCTION
MATERIAL
Peri-prosthetic fungal infection is generally considered more difficult to cure than a bacterial infection. Two-stage exchange is considered the gold standard of surgical treatment. A recent study, however, reported a favorable outcome after one stage exchange in selected cases where the fungus was identified prior to surgery. The routine one stage exchange policy for bacterial peri-prosthetic infection involves the risk of identifying a fungal infection mimicking bacterial infection solely on intraoperative samples, i.e. after reimplantation, realizing actually a one stage exchange for fungal infection without pre-operative identification of the responsible fungus, which is considered to have a poor prognosis. We report two such cases of prosthetic hip and knee fungal infection. Despite this negative characteristic, no recurrence of the fungal infection was observed. CASE N°1: A 78 year old patient was referred for loosening of a chronically infected total hip arthroplasty (Staphylococcus aureus and Streptococcus dysgalactiae). One stage exchange was performed. Intraoperative bacterial cultures remained sterile. Two fungal cultures were positive for Candida albicans. Antifungal treatment was initiated for three months. No infection recurrence was observed at three year follow up. CASE N° 2: A 53-year-old patient was referred for loosening of a chronically infected total knee prosthesis (Staphylococcus aureus methicillin susceptible, Klebsiella pneumoniae and Staphylococcus epidermidis). One stage exchange was performed. Intraoperative bacterial cultures remained sterile. Five fungal cultures were positive for Candida albicans. Antifungal treatment was initiated for three months. No infection recurrence was observed at two-year follow-up. This experience suggests that eradication of fungal infection of a total hip or knee arthroplasty may be possible after one stage exchange even in cases where the diagnosis of fungal infection was not known before surgery, when the fungus was not identified and its antifungal susceptibility has not been evaluated before surgery. It is however not possible to propose this strategy as a routine procedure.INTRODUCTION
DISCUSSION
The diagnosis of peri-prosthetic infection may be difficult. But this diagnosis can guide antibiotic prophylaxis and implementation of intraoperative bacteriological samples. The hypothesis of this study was that a composite score using clinical, radiological and biological data could be used for positive and negative diagnostic of infection before reoperation on prosthetic hip or knee. 200 reoperations on hip and knee arthroplasty for any cause were analyzed retrospectively. 100 cases concerned infected cases, while the diagnosis of infection was excluded in the other 100 cases.INTRODUCTION
MATERIAL
