Hilde Vandenneucker

Characterized Chondrocyte Implantation Results in Better Structural Repair When Treating Symptomatic Cartilage Defects of the Knee in a Randomized Controlled Trial Versus Microfracture

Background As the natural healing capacity of damaged articular cartilage is poor, joint surface injuries are a prime target for regenerative medicine. Characterized chondrocyte implantation uses an autologous cartilage cell therapy product that has been optimized for its biological potency to form stable cartilage tissue in vivo. Purpose To determine whether, in symptomatic cartilage defects of the femoral condyle, structural regeneration with characterized chondrocyte implantation is superior to repair with microfracture. Study Design Randomized controlled trial; Level of evidence, 1. Methods Characterized chondrocyte implantation was compared with microfracture in patients with single grade III to IV symptomatic cartilage defects of the femoral condyles in a multicenter trial. Patients aged 18 to 50 years were randomized to characterized chondrocyte implantation (n = 57) or microfracture (n = 61). Structural repair was blindly assessed in biopsy specimens taken at 1 year using (1) computerized histomorphometry and (2) evaluation of overall histological components of structural repair. Clinical outcome was measured using the self administered Knee injury and Osteoarthritis Outcome Score. Adverse events were recorded throughout the study. Results Characterized chondrocyte implantation resulted in better structural repair, as assessed by histomorphometry (P = .003) and overall histologic evaluation (P = .012). Aspects of structural repair relating to chondrocyte phenotype and tissue structure were superior with characterized chondrocyte implantation. Clinical outcome as measured by the Knee injury and Osteoarthritis Outcome Score at 12 to 18 months after characterized chondrocyte implantation was comparable with microfracture at this stage. Both treatment groups had a similar mean baseline overall Knee injury and Osteoarthritis Outcome Score (56.30 ± 13.61 and 59.53 ± 14.95 for microfracture and characterized chondrocyte implantation, respectively), which increased in both groups to 70.56 ± 12.39 and 72.63 ± 15.55 at 6 months, 73.26 ± 14.66 and 73.10 ± 16.01 at 12 months, and 74.73 ± 17.01 and 75.04 ± 14.50 at 18 months, respectively. Both techniques were generally well tolerated; the incidence of adverse events after characterized chondrocyte implantation was not markedly increased compared with that for microfracture. Conclusion One year after treatment, characterized chondrocyte implantation was associated with a tissue regenerate that was superior to that after microfracture. Short-term clinical outcome was similar for both treatments. The superior structural outcome may result in improved long-term clinical benefit with characterized chondrocyte implantation. Long-term follow-up is needed to confirm these findings.

The influence of tibial slope on maximal flexion after total knee arthroplasty

Many surgeons believe that increasing the tibial slope in total knee arthroplasty (TKA) is beneficial with regard to maximal postoperative flexion. Review of the clinical literature, however, does not confirm this hypothesis, neither does it give an answer to the question of how much flexion gain can be expected per degree extra tibial slope. The purpose of this study was, therefore, to evaluate and quantify the influence of tibial slope on maximal postoperative flexion in contemporary posterior cruciate ligament (PCL)-retaining TKA. Twenty-one cadaver simulations of a standard PCL-retaining TKA were studied while reproducing identical deep flexion femorotibial kinematics as documented by three-dimensional computer-aided videofluoroscopy from patients with well-functioning TKAs of the same design. In each knee the tibial component was consecutively implanted with 0° posterior slope, 4° posterior slope, and 7° posterior slope. Maximal flexion was recorded for each configuration. Average maximal flexion at 0° tibial slope was 104°, and increased significantly to 112° when the same knees were implanted with 4° tibial slope. Increasing the slope further to 7° again significantly improved average maximal flexion to 120°. When postoperative radiographic tibial slope was compared to maximal flexion, an average gain of 1.7° flexion for every degree extra tibial slope was noted. Increasing the tibial slope in PCL-retaining TKA does indeed improve maximal flexion before tibial insert impingement occurs against the femoral bone. The surgeon can expect an average gain of 1.7° flexion for every degree extra tibial slope.

Patient-specific Guides Do Not Improve Accuracy in Total Knee Arthroplasty: A Prospective Randomized Controlled Trial

BackgroundRecently, patient-specific guides (PSGs) have been introduced, claiming a significant improvement in accuracy and reproducibility of component positioning in TKA. Despite intensive marketing by the manufacturers, this claim has not yet been confirmed in a controlled prospective trial.Questions/purposesWe (1) compared three-planar component alignment and overall coronal mechanical alignment between PSG and conventional instrumentation and (2) logged the need for applying changes in the suggested position of the PSG.MethodsIn this randomized controlled trial, we enrolled 128 patients. In the PSG cohort, surgical navigation was used as an intraoperative control. When the suggested cut deviated more than 3° from target, the use of PSG was abandoned and marked as an outlier. When cranial-caudal position or size was adapted, the PSG was marked as modified. All patients underwent long-leg standing radiography and CT scan. Deviation of more than 3° from the target in any plane was defined as an outlier.ResultsThe PSG and conventional cohorts showed similar numbers of outliers in overall coronal alignment (25% versus 28%; p = 0.69), femoral coronal alignment (7% versus 14%) (p = 0.24), and femoral axial alignment (23% versus 17%; p = 0.50). There were more outliers in tibial coronal (15% versus 3%; p = 0.03) and sagittal 21% versus 3%; p = 0.002) alignment in the PSG group than in the conventional group. PSGs were abandoned in 14 patients (22%) and modified in 18 (28%).ConclusionsPSGs do not improve accuracy in TKA and, in our experience, were somewhat impractical in that the procedure needed to be either modified or abandoned with some frequency.Level of EvidenceLevel I, therapeutic study. See instructions for authors for a complete description of levels of evidence.

Septic Arthritis After Arthroscopic Anterior Cruciate Ligament Reconstruction A Retrospective Analysis of Incidence, Management and Outcome

BACKGROUND Septic arthritis after arthroscopic anterior cruciate ligament reconstruction is a rare complication. In the literature, several different managements are proposed. HYPOTHESIS The graft can be retained during treatment of a septic arthritis after anterior cruciate ligament reconstruction. STUDY DESIGN Case series; Level of evidence, 4. METHODS A retrospective analysis of knee joint infections occurring after arthroscopically assisted anterior cruciate ligament reconstructions was conducted. Fifteen patients were treated for postoperative septic arthritis of the knee after anterior cruciate ligament reconstruction between 1996 and 2005. All patients underwent an urgent extensive arthroscopic debridement (wash-out and synovectomy) and parenteral antibiotics and oral antibiotics subsequently. Repetitive wash-outs were performed if necessary. The average time at follow-up for our series was 58 months (range, 9-99 months). RESULTS Only 1 graft was removed during debridement because it was nonfunctional. All other patients retained their anterior cruciate ligament reconstruction. There was no reinfection. There were 2 traumatic reruptures. We evaluated 11 patients: in 6 patients the Lachman test showed a translation of more than 3 mm, but all patients had a firm endpoint and there was no subjective instability. Early signs of radiological degeneration were seen in 3 patients. The value for the Lysholm knee scoring scale was 83, on average, ranging from 57 to 100. Regarding the International Knee Documentation Committee score, 2 patients had a final evaluation of normal, 7 patients nearly normal, and 2 patients abnormal. CONCLUSION The graft can be retained during treatment of septic arthritis after anterior cruciate ligament reconstruction.Background Septic arthritis after arthroscopic anterior cruciate ligament reconstruction is a rare complication. In the literature, several different managements are proposed. Hypothesis The graft can be retained during treatment of a septic arthritis after anterior cruciate ligament reconstruction. Study Design Case series; Level of evidence, 4. Methods A retrospective analysis of knee joint infections occurring after arthroscopically assisted anterior cruciate ligament reconstructions was conducted. Fifteen patients were treated for postoperative septic arthritis of the knee after anterior cruciate ligament reconstruction between 1996 and 2005. All patients underwent an urgent extensive arthroscopic debridement (washout and synovectomy) and parenteral antibiotics and oral antibiotics subsequently. Repetitive wash-outs were performed if necessary. The average time at follow-up for our series was 58 months (range, 9-99 months). Results Only 1 graft was removed during debridement because it was nonfunctional. All other patients retained their anterior cruciate ligament reconstruction. There was no reinfection. There were 2 traumatic reruptures. We evaluated 11 patients: in 6 patients the Lachman test showed a translation of more than 3 mm, but all patients had a firm endpoint and there was no subjective instability. Early signs of radiological degeneration were seen in 3 patients. The value for the Lysholm knee scoring scale was 83, on average, ranging from 57 to 100. Regarding the International Knee Documentation Committee score, 2 patients had a final evaluation of normal, 7 patients nearly normal, and 2 patients abnormal. Conclusion The graft can be retained during treatment of septic arthritis after anterior cruciate ligament reconstruction.

Is there a biomechanical explanation for anterior knee pain in patients with patella alta?: INFLUENCE OF PATELLAR HEIGHT ON PATELLOFEMORAL CONTACT FORCE, CONTACT AREA AND CONTACT PRESSURE

The purpose of this study was to test the hypothesis that patella alta leads to a less favourable situation in terms of patellofemoral contact force, contact area and contact pressure than the normal patellar position, and thereby gives rise to anterior knee pain. A dynamic knee simulator system based on the Oxford rig and allowing six degrees of freedom was adapted in order to simulate and record the dynamic loads during a knee squat from 30 degrees to 120 degrees flexion under physiological conditions. Five different configurations were studied, with variable predetermined patellar heights. The patellofemoral contact force increased with increasing knee flexion until contact occurred between the quadriceps tendon and the femoral trochlea, inducing load sharing. Patella alta caused a delay of this contact until deeper flexion. As a consequence, the maximal patellofemoral contact force and contact pressure increased significantly with increasing patellar height (p < 0.01). Patella alta was associated with the highest maximal patellofemoral contact force and contact pressure. When averaged across all flexion angles, a normal patellar position was associated with the lowest contact pressures. Our results indicate that there is a biomechanical reason for anterior knee pain in patients with patella alta.

The John Insall Award: Both Morphotype and Gender Influence the Shape of the Knee in Patients Undergoing TKA

AbstractThere is an ongoing debate whether gender differences in the dimensions of the knee should influence the design of TKA components. We hypothesized that not only gender but also the patient’s morphotype determined the shape of the distal femur and proximal tibia and that this factor should be taken into account when designing gender-specific TKA implants. We reviewed all 1000 European white patients undergoing TKA between April 2003 and June 2007 and stratified each into one of three groups based on their anatomic constitution: endomorph, ectomorph, or mesomorph. Of the 250 smallest knees, 98% were female, whereas 81% of the 250 largest knees were male. In the group with intermediate-sized knees, female knees were narrower than male knees. Patients with smaller knees (predominantly female) demonstrated large variability between narrow and wide mediolateral dimensions irrespective of gender. The same was true for larger knees (predominantly male). This variability within gender could partially be explained by morphotypic variation. Patients with short and wide morphotype (endomorph) had, irrespective of gender, wider knees, whereas patients with long and narrow morphotype (ectomorph) had narrower knees. The shape of the knee is therefore not only dependent on gender, but also on the morphotype of the patient. Level of Evidence: Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

A new surgical technique for medial collateral ligament balancing: multiple needle puncturing

In this article, we present our experience with a new technique for medial soft tissue balancing, where we make multiple punctures in the medial collateral ligament (MCL) using a 19-gauge needle, to progressively stretch the MCL until a correct ligament balance is achieved. Ligament status was evaluated both before and after the procedure using computer navigation and mediolateral stress testing. The procedure was considered successful when 2 to 4-mm mediolateral joint line opening was obtained in extension and 2 to 6 mm in flexion. In 34 of 35 cases, a progressive correction of medial tightness was achieved according to the above described criteria. One case was considered overreleased in extension. Needle puncturing is a new, effective, and safe technique for progressive correction of MCL tightness in the varus knee.

Robot-assisted total knee arthroplasty

Increasing evidence suggests performing total knee arthroplasty using computer navigation can lead to more accurate surgical positioning of the components and knee alignment compared to a conventional operating technique without computer assistance. The use of robotic technology could theoretically take this accuracy one level further because it uses navigation in combination with ultimate mechanical precision, which could eliminate or reduce the inevitable margin of error during mechanical preparation of the bony cuts of total knee arthroplasty by the surgeon. We prospectively followed 25 consecutive cases using an active surgical robot. The minimum followup was 5.1 years (mean, 5.5 years; range, 5.1-5.8 years). Our results demonstrate excellent implant positioning and alignment was achieved within the 1° error of neutral alignment in all three planes in all cases. Despite this technical precision, the excessive operating time required for the robotic implantation, the technical complexity of the system, and the extremely high operational costs have led us to abandon this procedure and direct our interest more toward smart semiactive robotic systems.Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The influence of malrotation of the femoral component in total knee replacement on the mechanics of patellofemoral contact during gait. An in vitro biomechanical study

Malrotation of the femoral component is a cause of patellofemoral maltracking after total knee arthroplasty. Its precise effect on the patellofemoral mechanics has not been well quantified. We have developed an in vitro method to measure the influence of patellar maltracking on contact. Maltracking was induced by progressively rotating the femoral component either internally or externally. The contact mechanics were analysed using Tekscan. The results showed that excessive malrotation of the femoral component, both internally and externally, had a significant influence on the mechanics of contact. The contact area decreased with progressive maltracking, with a concomitant increase in contact pressure. The amount of contact area that carries more than the yield stress of ultra-high molecular weight polyethylene significantly increases with progressive maltracking. It is likely that the elevated pressures noted in malrotation could cause accelerated and excessive wear of the patellar button.

Soft tissue balance in total knee arthroplasty : does stress relaxation occur perioperatively?

The restoration of correct soft tissue tension is key to achieving a successful total knee arthroplasty. However, it remains unclear whether the status achieved immediately after the operation will persist over time. Some surgeons believe soft tissue stress relaxation occurs and therefore the knee loosens somewhat after the procedure. It was the aim of this study to investigate this hypothesis. We analyzed 25 in vivo total knee implantations using contemporary computer navigation technology to assess and quantify perioperative soft tissue relaxation. Mediolateral joint laxity and maximal passive extension were analyzed immediately intraoperatively and 30 minutes later under the same conditions. Stress relaxation occurred in all cases, leading to increased mediolateral laxity by an average of 1 mm on the medial and lateral sides. Maximal passive extension increased by an average of 3°. This data confirms the hypothesis the knee becomes looser in the early phase after total knee arthroplasty.