The human meniscus: transplantation, characterisation and tissue engineering

The Human Meniscus: Transplantation, Characterization and Tissue Engineering Peter Verdonk, MD, PhD; Ghent University, Belgium Abstract The meniscus plays an important role in the complex biomechanics of the knee joint. Removal of this tissue can result in dysfunction and pain in the involved joint compartment and ultimately osteoarthritis. We report on the surgical technique, the clinical and radiological outcome after substitution of the human meniscus with a viable allograft. The results of this type of surgery are encouraging and long-lasting in a well-selected patient population who suffered a total meniscectomy. Viable meniscus allograft transplantation significantly reduces pain and improves function. This beneficial effect remains present in around 70% of the patients at 10 years after surgery. In light of the higher number of partial meniscectomies in the clinical office, further attention was paid to develop tissue engineering strategies to restore and regenerate meniscus tissue without the intrinsic drawback of the use of allogeneic material. A first study aimed at the characterization of the human meniscus cell associated matrix (CAM) synthesis and turnover in two different culture conditions. The alginate culture conditions appear to favor the fibrochondrocyte meniscus cells with a CAM rich in type I collagen and aggrecan and lower quantities of type II collagen, while monolayer cultured meniscus cells have considerable amounts of type I and II collagen but almost no aggrecan in their CAM. Additional investigations led to the description of a new cell-type within the superficial layer of the normal meniscus; the CD34+ meniscus cell. In a second study, we demonstrated that human bone marrow derived mesenchymal stem cells in combination with a type I collagen scaffold have a fibrochondrogenic differentiation potential. This cell-scaffold combination is implantable and could easily deliver autologous hBMSC with meniscus repair potential to the defect. The ultimate goal of meniscus transplantation and tissue engineering is to prevent the degenerative process induced by a partial or total meniscectomy and inflicted upon the articular cartilage. Therefore, metabolic pathways (IGF-1, IL-1, IL-1RII) were investigated in the articular chondrocyte that could be targeted by specific pharmaceuticals (polysulphated cyclodextrines) in order to upregulate an anabolic effect. The use of these substances could improve the results of meniscus substitution procedures in secondary osteoarthritic knee joints

Effects of total knee arthroplasty on ankle alignment in patients with varus gonarthrosis : do we sacrifice ankle to the knee?

Total knee arthroplasty is one of the most commonly preferred surgical methods in the treatment of patients with varus gonarthrosis. In this study, we aimed to evaluate the radiological changes observed in the ankles after total knee arthroplasty. Between May 2012 and June 2013, 80 knees of 78 patients with varus deformity over 10A degrees underwent total knee arthroplasty. For each patient, full-leg standing radiographs were obtained pre- and post-operatively. Mechanical and anatomical axes (HKA and AA), lateral distal femoral angle, medial proximal tibial angle, lateral distal tibial angle (LDTA), ankle joint line orientation angle (AJOA), tibial plafond talus angle (PTA) and talar shift were measured for each patient both pre- and post-operatively. Pre-operatively, the mean HKA was 16.6A degrees and the mean AA was 10.41A degrees, both in favour of varus alignment. Post-operatively, the mean HKA decreased to 3.6A degrees and the mean AA to -2.1. The mean LDTA was 87.3A degrees. Before the operation, the mean AJOA was -7.6A degrees, opening to the medial aspect of the ankle, and it was 0.04A degrees after the operation and opening to the lateral aspect (p < 0.05). Our study reveals the changes occurring in the ankle after acute correction of long-standing varus deformity of the knee using total knee arthroplasty. In cases undergoing knee arthroplasty, effect of the acute change in the alignment of the knee on the ankle should be taken into consideration and the amount of correction should be calculated carefully in order not to damage the alignment of the ankle

Imaging findings after meniscal repair with degradable polyurethane scaffold: preliminary results.

Purpose / Introduction: To date, there are no satisfactory solutions to the meniscal originated knee pain post meniscal tear repair. In this study a newly developed polyurethane material that has the intended properties of reducing pain and inducing tissue growth in a damaged meniscus is tested. Materials and Methods: All patients will be imaged using conventional and dynamic MR imaging techniques at 1 week and 3, 12 and 24 months after surgery. The influx of gadolinium contrast in a tissue during the first three minutes after injection gives a measure of the vascularisation, capillary permeability, perfusion and composition of the interstitial fluid. It can be measured using dynamic MRI and is represented as a Time Intensity Curve (TIC). This curve permits an evaluation of the healing process after surgery. Discussion / Conclusion: Thus far 11 patients have received meniscal implants. Eight medial and three lateral menisci were operated. All implants covered the posterior horn with 3 reaching halfway into the meniscal body and one extending into the anterior horn. The average length of the scaffold meniscus measured on MR imaging was 45mm. In the first week after surgery, the capsule and suture area display fast and intense enhancement typical for post-operative inflammation and the formation of early scar-tissue. There is no enhancement in the base or the tip of the scaffold meniscus. After three months the speed and intensity of enhancement in the capsule and suture area between the remnants of the native meniscus and the scaffold have decreased indicating maturation of scar-tissue. However, the base of the scaffold meniscus now shows enhancement. This can only be explained by proliferation of blood vessels from the capsule and theresidual meniscus wall into the scaffold meniscus. The tip of the matrix shows limited enhancement in some patients after three months. On anatomical MR images, the signal intensity (SI) of the implanted scaffold is close to that of water on both T1- and T2-weighted spin echo and turbo spin echo sequences in the first week. After three months the SI decreases but is still clearly higher than that of the native meniscus. The implants in the posterior horn all had a normal position and no loosening of the sutures or tears of the scaffold were found. After three months, one of the patients had slight expulsion of body of the scaffold meniscus but this is a common finding in transplanted menisci

Viabilni i smrznuti transplantat meniska. Rana klinička i radiološka evaluacija

Aim: To perform a clinical and imaging short term evaluation of viable and frozen meniscus allografts. Methods and materials: Between 2005 and 2006, 12 meniscal allograft transplantations were performed in our institution. The study population consisted of 5 men and 7 women with a mean age of 36.4 years (range 17.1-42.5). Six patients received a viable allograft and six a deep-frozen one. All allografts were harvested from donors who died after a short disease. All patients were operated with an open surgical technique (medial or lateral arthrotomy) and soft tissue fixation with secure anterior and posterior horn fixation, performed by one senior surgeon. All patients were scored pre-operatively, at 6 weeks, 3 months, 6 months, 1 and 2 years postoperatively. Three questionnaires were used to score the patients clinically (KOOS, modified HSS and SF-36 questionnaire). Every patient received radiographs pre-operatively and at 6 months and 1 year. Results: Clinically, there was no difference in patient self-reported results through questionnaires or in a questionnaire based on clinical examination. There was no significant progress in joint space narrowing on weight bearing and Rosenberg view radiographs. Conclusion: Our results suggest that there are no clinical significant differences between the viable and the deep frozen subgroup after two years.Cilj: Učiniti ranu kliničku i radiološku evaluaciju vijabilnog i smrznutog transplantata meniska. Metoda i materijali: Tijekom 2005. i 2006. godine, u našoj ustanovi izvedeno je 12 alotransplantacija meniska. U studiju je bilo uključeno 5 muškaraca i 7 žena, s prosječnom dobi od 36,4 godina (raspon od 17,1 do 42,5). U šest pacijenata presađen je vijabilni transplantat, u šest duboko smrznuti transplantat. Svi transplantati su dobiveni od davatelja koji su umrli nakon kratke bolesti. Svi pacijenti operirani su otvorenim kirurškim zahvatom (medijalna ili lateralna artrotomija), uz fiksaciju mekih tkiva i fiksaciju prednjeg i stražnjeg roga. Svi pacijenti su evaluirani preoperativno, te 6 tjedana, 3 mjeseca, 6 mjeseci, jednu i dvije godine nakon operacije. Za kliničku evaluaciju bolesnika korištena su tri upitnika (KOOS, adaptirani HSS i SF-36 upitnik). Svakom pacijentu je učinjena rendgenska slika preoperativno, nakon 6 mjeseci i nakon jedne godine. Rezultati: Klinički, nije bilo razlika između rezultata koje su bolesnici samostalno naveli u upitnicima i onih dobivenih temeljem kliničkog pregleda. Rendgenska slika po Rosenbergu nije pokazala značajni pomak u suženju zglobne pukotine pod opterećenjem. Zaključak: Naši rezultati ukazuju na to da nakon dvije godine ne postoje klinički značajne razlike između transplantacije vijabilnog i duboko smrznutog transplantata

Transplantation of viable meniscal allograft : survivorship analysis and clinical outcome of one hundred cases

Background: Few medium-term or long-term reports on meniscal allograft transplantations are available. In this study, we present the results of a survival analysis of the clinical outcomes of our first 100 procedures involving transplantation of viable medial and lateral meniscal allografts performed in ninety-six patients. Methods: Thirty-nine medial and sixty-one lateral meniscal allografts were evaluated after a mean of 7.2 years. Survival analysis was based on specific clinical end points, with failure of the allograft defined as moderate occasional or persistent pain or as poor function. An additional survival analysis was performed to assess the results of the sixty-nine procedures that involved isolated use of a viable allograft (twenty of the thirty-nine medial allograft procedures and forty-nine of the sixty-one lateral allograft procedures) and of the thirteen viable medial meniscal allografts that were implanted in combination with a high tibial osteotomy in patients with initial varus malalignment of the lower limb. Results: Overall, eleven (28%) of the thirty-nine medial allografts and ten (16%) of the sixty-one lateral allografts failed. The mean cumulative survival time (11.6 years) was identical for the medial and lateral allografts. The cumulative survival rates for the medial and lateral allografts at ten years were 74.2% and 69.8%, respectively. The mean cumulative survival time and the cumulative survival rate for the medial allografts used in combination with a high tibial osteotomy were 13.0 years and 83.3% at ten years, respectively. Conclusions: Transplantation of a viable meniscal allograft can significantly relieve pain and improve function of the knee joint. Survival analysis showed that this beneficial effect remained in approximately 70% of the patients at ten years. This study identified the need for a prospective study comparing patients with similar symptoms and clinical findings treated with and without a meniscal allograft and followed for a longer period with use of clinical evaluation as well as more objective documentation tools regarding the actual fate of the allograft itself and the articular cartilage

MR-Imaging of Meniscal Substitution

More than a century ago, the menisci were considered to be the functionless remains of a leg muscle. Gradually the usefulness and function of the meniscus was investigated and proven, and the link between total meniscectomy, radiographic osteoarthritis and reduced knee function was made. Subsequently, partial meniscectomy was introduced in the clinical practice. However, the frequency of symptomatic knee osteoarthritis was not substantially lowered. Therefore, meniscal repair was introduced for younger individuals with traumatic meniscus lesions with a good healing potential. Later on in the development process, the quest for meniscal replacement strategies arose. The introduction of allogenic, xenogenic and artificial materials followed in research and clinical settings. Nowadays, a lot of research is conducted on meniscal substitutes, because meniscal injuries are a very common problem in the general population. The imaging of the meniscus is running parallel to this evolution. With the development of magnetic resonance imaging (MRI), the meniscus could be perfectly visualized. A lot of studies were published on imaging of the normal meniscus, and subsequently meniscal pathology on MRI was investigated. In the current literature, a growing number of papers describe the MRI findings in artificial meniscus replacements