Wouter Huysse

Tissue Ingrowth After Implantation of a Novel, Biodegradable Polyurethane Scaffold for Treatment of Partial Meniscal Lesions

Background: A novel, biodegradable, aliphatic polyurethane scaffold was designed to fulfill an unmet clinical need in the treatment of patients with irreparable partial meniscal lesions. Hypothesis: Treatment of irreparable partial meniscal lesions with an acellular polyurethane scaffold supports new tissue ingrowth. Study Design: Case series; Level of evidence, 4. Methods: Fifty-two patients (with 34 medial and 18 lateral lesions) were recruited into a prospective, single-arm, multicenter, proof-of-principle study and treated with the polyurethane scaffold. The scaffold was implanted after partial meniscectomy using standard surgeon-preferred techniques for suturing. Tissue ingrowth was assessed at 3 months by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and at 12 months by gross examination during second-look arthroscopy, in the course of which a biopsy sample from the inner free edge of the scaffold meniscus was taken for qualitative histologic analysis. Results: Tissue ingrowth at 3 months was demonstrated on DCE-MRI in 35 of 43 (81.4%) patients. All but one 12-month second-look (43 of 44 [97.7%]) showed integration of the scaffold with the native meniscus and all biopsy specimens (44) showed fully vital material, with no signs of cell death or necrosis. Three distinct layers were observed based on morphologic structure, vessel structure presence or absence, and extracellular matrix composition. Conclusion: The DCE-MRI demonstrated successful early tissue ingrowth into the scaffold. The biopsy findings demonstrated the biocompatibility of the scaffold and ingrowth of tissue with particular histologic characteristics suggestive of meniscus-like tissue. In conclusion, these data show for the first time consistent regeneration of tissue when using an acellular polyurethane scaffold to treat irreparable partial meniscus tissue lesions.

Successful Treatment of Painful Irreparable Partial Meniscal Defects With a Polyurethane Scaffold Two-Year Safety and Clinical Outcomes

Background: A novel, biodegradable, polyurethane scaffold was designed to fulfill an unmet clinical need in the treatment of patients with painful irreparable partial meniscal defects. Hypothesis: The use of an acellular polyurethane scaffold for new tissue generation in irreparable partial meniscal defects provides both pain relief and improved functionality. Study Design: Case series; Level of evidence, 4. Methods: Fifty-two patients with irreparable partial meniscal defects (34 medial and 18 lateral, 88% with 1-3 previous surgeries on the index meniscus) were implanted with a polyurethane scaffold in a prospective, single-arm, multicenter, proof-of-principle study. Safety was assessed by the rate of scaffold-related serious adverse events (SAEs) and the International Cartilage Repair Society articular cartilage scoring system comparing magnetic resonance imaging (MRI) at 24 months to MRI at baseline (1 week). Kaplan-Meier time to treatment failure distributions were performed. Clinical outcomes were measured comparing visual analog scale, International Knee Documentation Committee, Knee Injury and Osteoarthritis Outcome Score (KOOS), and Lysholm scores at 24 months from baseline (entry into study). Results: Clinically and statistically significant improvements (P < .0001) compared with baseline were reported in all clinical outcome scores (baseline/24 months): visual analog scale (45.7/20.3), International Knee Documentation Committee (45.4/70.1), KOOS symptoms (64.6/78.3), KOOS pain (57.5/78.6), KOOS activities of daily living (68.8/84.2), KOOS sports (30.5/59.0), KOOS quality of life (33.9/56.6), and Lysholm (60.1/80.7), demonstrating improvements in both pain and function. The incidence of treatment failure was 9 (17.3%) patients, of which 3 patients (8.8%) had medial meniscal defects and 6 patients (33.3%) had lateral meniscal defects. There were 9 SAEs requiring reoperation. Stable or improved International Cartilage Repair Society cartilage grades were observed in 92.5% of patients between baseline and 24 months. Conclusion: At 2 years after implantation, safety and clinical outcome data from this study support the use of the polyurethane scaffold for the treatment of irreparable, painful, partial meniscal defects.

Meniscal allografts: Indications and outcomes

Meniscal allograft transplantation was introduced into clinical practice now over 20 years ago for the treatment of the symptomatic postmeniscectomy patient who has not yet developed osteoarthritis. Over the years, the indications have been fine-tuned and certain risk factors for failure have been identified. As the number of publications increases steadily, we now know that meniscal allografting significantly reduces pain and improves function. Recent data also suggest a potential chondroprotective effect in a subpopulation of patients. However, the major drawback in all meniscus allograft studies is the general lack of a control population. To improve our knowledge, future prospective studies should include objective outcome tools to evaluate the status of the allograft in addition to the clinical scoring systems. Future research should focus to elucidate the biologic and cellular processes involved in graft repopulation and remodelation.

Open versus arthroscopic meniscus allograft transplantation: magnetic resonance imaging study of meniscal radial displacement

PURPOSE In this imaging study, the radial displacement of meniscal allograft transplants (MATs), inserted with 2 different techniques, namely open soft-tissue fixation and arthroscopic bone tunnel fixation, was compared 1 year postoperatively. METHODS In this study, 37 patients received MATs: 16 MATs (10 lateral and 6 medial) were inserted by an open soft-tissue technique (open MATs), whereas 21 MATs (14 lateral and 7 medial) were implanted by an arthroscopic bone tunnel procedure (arthroscopic MATs). Radial displacement, in millimeters, was evaluated 1 year postoperatively on 1.5-T magnetic resonance images. The number of MATs with radial displacement larger or smaller than 3 mm was determined. To compare radial displacement of open versus arthroscopic MATs, the Mann-Whitney U test was used. RESULTS The radial displacement of open lateral and medial MATs was significantly larger (all reported P < .02) than that of arthros-copic MATs. In all cases, both open and arthroscopic, the radial displacement of MATs was significantly larger (all reported P < .007) than that of normal menisci. Radial displacement of less than 3 mm was found in 0 of 6 patients with open medial MATs versus 6 of 7 patients with arthroscopic MATs and was found in 1 of 10 patients with open lateral MATs versus 4 of 14 patients with arthroscopic MATs. CONCLUSIONS The radial displacement of MATs arthroscopically inserted with bone tunnel fixation is significantly less than the radial displacement of MATs inserted with open soft-tissue fixation. In addition, normal menisci displace significantly less than meniscal allografts. The clinical importance of radial displacement remains to be determined. LEVEL OF EVIDENCE Level III, retrospective comparative study.

Two-Year Follow-up Study on Clinical and Radiological Outcomes of Polyurethane Meniscal Scaffolds

Background: Little is known about radial displacement (RD) of polyurethane (PU) scaffolds, intended for partial meniscus defect substitution; no data are available on whether rim thickness influences RD and whether RD correlates with clinical outcome scores. Hypotheses: The meniscus is not extruded preoperatively, but RD occurs after scaffold implantation. A thicker rim will limit RD, and there is no correlation between RD and clinical outcome. Study Design: Case series; Level of evidence, 4. Methods: Twenty-six patients were implanted with a PU scaffold (8 lateral, 18 medial). Radial displacement (mm) was evaluated on magnetic resonance images preoperatively and at 3 months, 1 year, and 2 years postoperatively. At each time point, it was determined whether a correlation existed between the rim and RD. Clinical outcome was determined using a visual analog scale (VAS) for pain as well as the Lysholm knee scoring scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) score. Results: Radial displacement of lateral scaffolds was not significantly different (P = .178) either preoperatively (mean ± SD, 3.42 ± 0.99 mm) or at 3 months (4.82 ± 0.59 mm), 1 year (4.55 ± 0.87 mm), or 2 years postoperatively (4.10 ± 0.93 mm). No correlation was observed between the rim and lateral RD at all time points. Medial scaffold RD increased significantly (P < .001) from preoperative values (2.17 ± 0.84 mm) to those at 3 months (4.25 ± 0.89 mm), 1 year (4.43 ± 1.01 mm), and 2 years postoperatively (4.41 ± 0.96 mm). A strong negative correlation between medial RD and the rim was observed at all time points. There was no significant correlation between clinical outcome scores and RD, either preoperatively or postoperatively. Conclusion: This study demonstrated that limited medial meniscal RD was present preoperatively but increased by 2 mm after scaffold implantation. Lateral RD was also present preoperatively but did not increase after scaffold implantation. Importantly, a strong negative correlation was found between the rim and postoperative medial RD; a thicker rim limited RD. However, in the lateral compartment, rim thickness did not correlate with RD because RD was already strongly present preoperatively. Finally, no correlations were observed between scaffold RD and clinical outcome scores, either preoperatively or postoperatively.

MRI evaluation of a new scaffold-based allogenic chondrocyte implantation for cartilage repair

AIM The present study was designed to evaluate the implantation of alginate beads containing human mature allogenic chondrocytes for the treatment of symptomatic cartilage defects of the knee. MRI was used for the morphological analysis of cartilage repair. The correlation between MRI findings and clinical outcome was also studied. METHODS A biodegradable, alginate-based biocompatible scaffold containing human mature allogenic chondrocytes was used for the treatment of symptomatic chondral and osteochondral lesions in the knee. Twenty-one patients were prospectively evaluated with use of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Visual Analogue Scale (VAS) for pain preoperatively and at 3, 6, 9 and 12 months of follow-up. Of the 21 patients, 12 had consented to follow the postoperative MRI evaluation protocol. MRI data were analyzed based on the original MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) and modified MOCART scoring system. The correlation between the clinical outcome and MRI findings was evaluated. RESULTS A statistically significant clinical improvement became apparent after 6 months and patients continued to improve during the 12 months of follow-up. One of the two MRI scoring systems that were used, showed a statistically significant deterioration of the repair tissue at 1 year of follow-up. Twelve months after the operation complete filling or hypertrophy was found in 41.6%. Bone-marrow edema and effusion were seen in 41.7% and 25% of the study patients, respectively. We did not find a consistent correlation between the MRI criteria and the clinical results. DISCUSSION The present study confirmed the primary role of MRI in the evaluation of cartilage repair. Two MOCART-based scoring systems were used in a longitudinal fashion and allowed a practical and morphological evaluation of the repair tissue. However, the correlation between clinical outcome and MRI findings was poor. Further validation of these scoring systems is mandatory. The promising short-term clinical outcome of the allogenic chondrocytes/alginate beads implantation was not confirmed by the short-term MRI findings.

MRI of the SI joints commonly shows non-inflammatory disease in patients clinically suspected of sacroiliitis.

PURPOSE To determine the prevalence of clinically relevant non-inflammatory disease on MRI of the sacroiliac (SI) joints in patients suspected of sacroiliitis. To assess the added value of axial imaging of the pelvis in these patients. METHODS In a retrospective study of 691 patients undergoing MRI of the SI joints from January 2006 to December 2012 for inflammatory back pain the prevalence of sacroiliitis and non-inflammatory disease was recorded. RESULTS In 285 (41%) patients MRI did not show any abnormal findings. In 36% of patients MRI features of sacroiliitis were present. Spinal degenerative changes were the most common non-inflammatory finding in 305 patients (44.1%) and consisted of disc degeneration in 222 (32%) patients, facet joint arthrosis in 58 (8.4%) patients and disc herniation in 25 (3.6%) patients. Hip joint disease in 44 (6.4%) patients, lumbosacral transitional anomaly in 41 (5.9%) patients, SI joint degenerative changes in 25 (3.6%) patients and diffuse idiopathic skeletal hyperostosis in 24 (3.5%) patients were also common. Osteitis condensans ilii in 17 (2.5%) patients, tumour in 11 (1.6%) patients, fracture in 8 (1.2%) patients, infection in 4 (0.6%) patients and acute spondylolysis in 2 patients (0.3%) were less frequently seen. CONCLUSION Our study shows that non-inflammatory disease is more common than true sacroiliitis on MRI of the SI joints in patients with inflammatory type back pain. Axial pulse sequences may demonstrate unexpected findings that remain undetected if only coronal images are obtained. Clinical relevance statement:, MRI of the SI joints may demonstrate conditions that clinically mimic sacroiliitis. Axial imaging of the pelvis may help detect these unexpected findings.

Prevalence of Radiographic Parameters Predisposing to Femoroacetabular Impingement in Young Asymptomatic Chinese and White Subjects

BACKGROUND Osteoarthritis of the hip is five to ten times more common in white people than in Chinese people. Little is known about the true prevalence of femoroacetabular impingement or its role in the development of osteoarthritis in the Chinese population. A cross-sectional study of both white and Chinese asymptomatic individuals was conducted to compare the prevalences of radiographic features posing a risk for femoroacetabular impingement in the two groups. It was hypothesized that that there would be proportional differences in hip anatomy between the white and Asian populations. METHODS Pelvic computed tomography scans of 201 subjects (ninety-nine white Belgians and 102 Chinese; 105 men and ninety-six women) without hip pain who were eighteen to forty years of age were assessed. The original axial images were reformatted to three-dimensional pelvic models simulating standardized radiographic views. Ten radiographic parameters predisposing to femoroacetabular impingement were measured: alpha angle, anterior offset ratio, and caput-collum-diaphyseal angle on the femoral side and crossover sign, ischial spine projection, acetabular anteversion angle, center-edge angle, acetabular angle of Sharp, Tönnis angle, and anterior acetabular head index on the acetabular side. RESULTS The white subjects had a less spherical femoral head than the Chinese subjects (average alpha angle, 56° compared with 50°; p<0.001). The Chinese subjects had less lateral acetabular coverage than the white subjects, with average center-edge angles of 35° and 39° (p<0.001) and acetabular angles of Sharp of 38° and 36° (p<0.001), respectively. A shallower acetabular configuration was predominantly present in Chinese women. CONCLUSIONS Significant differences in hip anatomy were demonstrated between young asymptomatic Chinese and white subjects. However, the absolute size of the observed differences appears to contrast with the reported low prevalence of femoroacetabular impingement in Chinese individuals compared with the high prevalence in white populations.

Ossification variants of the femoral condyles are not associated with osteochondritis dissecans

PURPOSE To determine if ossification variants of the femoral condyles involving the subchondral bone plate are associated with osteochondritis dissecans (OCD). MATERIALS AND METHODS The prevalence of ossification variants of the unaffected femoral condyle in 116 patients (aged 9-14 years) with unicondylar OCD on MRI (magnetic resonance imaging) of the knee was compared to a control group of 579 patients (aged 9-14 years) without OCD. The evolution of the ossification variants in both groups was studied by reviewing follow-up MR imaging side by side with the baseline study. RESULTS The prevalence of ossification variants in the unaffected condyle in patients with OCD (12.9%) and in the control group of patients without OCD (12.6%) was similar (p=0.88). Evolution of ossification variants to OCD was not seen on follow-up MRI examinations. All variants had decreased in size or were no longer visible. CONCLUSION Ossification variants of the femoral condyle that involve the subchondral bone plate are not associated with OCD. CLINICAL RELEVANCE STATEMENT: Ossification variants are not associated with OCD, indicating that routine MRI follow-up in affected children is not mandatory.

In-vivo evaluation of the kinematic behavior of an artificial medial meniscus implant: A pilot study using open-MRI.

BACKGROUND In this pilot study we wanted to evaluate the kinematics of a knee implanted with an artificial polycarbonate-urethane meniscus device, designed for medial meniscus replacement. The static kinematic behavior of the implant was compared to the natural medial meniscus of the non-operated knee. A second goal was to evaluate the motion pattern, the radial displacement and the deformation of the meniscal implant. METHODS Three patients with a polycarbonate-urethane implant were included in this prospective study. An open-MRI was used to track the location of the implant during static weight-bearing conditions, within a range of motion of 0° to 120° knee flexion. Knee kinematics were evaluated by measuring the tibiofemoral contact points and femoral roll-back. Meniscus measurements (both natural and artificial) included anterior-posterior meniscal movement, radial displacement, and meniscal height. FINDINGS No difference (P>0.05) was demonstrated in femoral roll-back and tibiofemoral contact points during knee flexion between the implanted and the non-operated knees. Meniscal measurements showed no significant difference in radial displacement and meniscal height (P>0.05) at all flexion angles, in both the implanted and non-operated knees. A significant difference (P ≤ 0.05) in anterior-posterior movement during flexion was observed between the two groups. INTERPRETATION In this pilot study, the artificial polycarbonate-urethane implant, indicated for medial meniscus replacement, had no influence on femoral roll-back and tibiofemoral contact points, thus suggesting that the joint maintains its static kinematic properties after implantation. Radial displacement and meniscal height were not different, but anterior-posterior movement was slightly different between the implant and the normal meniscus.