Introduction: We studied the extracellular matrix (ECM) of 19 ruptured human Achilles tendons, comparing the tissue composition of specimens taken from area close to the rupture with specimens harvested from an apparently healthy area in the same tendon. The hypothesis was that the metabolism of these molecules is altered in patients with Achilles tendon rupture.

Materials and Methods: We compared the gene expression and the protein localization of the main ECM molecules (collagen type I, decorin and versican) including enzymes involved in their metabolism as matrix metallo-proteases (MMP2 and 9) and tissue inhibitory of metal-loproteinase (TIMP 1 and 2) using a Real Time PCR, zymography and FACE analysis.

Results: The gene expression of proteoglycans core protein, collagen type I, MMPs and TIMPs is more represented in the area close to the tendon rupture (p< 0.05). The expression of MMPs was confirmed by zymography analysis, showing a marked increase of gelatinolytic activity in area close to the tendon rupture (p< 0.05). The chemical composition of tendon changes showing that in the healthy area the carbohydrate content is higher than the ruptured area (p< 0.05).

Discussion/Conclusions: In the ruptured area, the tenocytes tried to restore the normal proteoglycan pattern increasing the core protein synthesis but without the normal glycosaminoglycan production. Our data support the hypothesis that, in human tendons, the tissue in the area of rupture undergoes marked rearrangement at molecular levels based on the MMP2 activity, and support the role of MMPs in the tendon pathology.

Aim of this study is the investigation of lower limbs biomechanics before and after meniscectomy.

Materials and methods: Ten volunteers candidate to partial medial meniscectomy underwent motion analysis before surgery, six months and one year after. Ten healthy volunteers acted as a control group

Data were acquired by means of Vicon motion analysis system

Results: In gait patterns investigation, joint kinematics does not show significant modifications before and 6 months after surgery, 12 months after surgery hip and knee show a greater flexion.

The dynamic analysis stresses alterations in knee sagittal moment. Before surgery the knee flexion moment is reduced. After partial meniscectomy the knee flexion moment increases in both the limbs. In squatting investigation, main focus was on repeatability. Before surgery high inter subjects variability affects knee joint angle; while after surgery high variability affects also hip and ankle.

Conclusions: After meniscectomy, gait and squatting patterns are still altered. Before surgery, the joint mechanical structure is not highly altered and modifications are mainly due to pain avoidance schemas; after partial meniscectomy, pain disappears and the new joint behaviours are probably caused by the new mechanical asset and/or proprioceptive mechanisms.

Biomaterial porosity is considered one of most important proprieties required to obtain fixation of bone ingrowth and ongrowth in prostheses.

Since 1998 in the USA and from in Europe a new highly porous biomaterial, Trabecular Metal Technology (TMT, ©Zimmer, USA) has been used in orthopaedic surgery.

This study evaluates the short-term morphological findings of porous tantalum screws implanted in three patients with osteonecrosis of a femoral head. Tantalum trabecular metal offers several advantages over conventional materials. Its regular porosity is considered one of most important properties in bone ingrowth and ongrowth and high biocompatibility and osteoconductivity. The biomechanical properties of tantalum are sufficient to withstand physiological load.

Our study disclosed a good integration. The bone penetrated the porous metal completely and many characteristics of good bio-integration were evident such as new formation of lamellae, presence of calcium and phosphorus elements, absence of fracture and signs of implant metallosis. The presence of peri-implant medullary cisternae confirmed the functional sites of new bone formation.

We conclude that the porous tantalum material is an optimal osteoinductor and osteoconductor even in critical conditions.

Matrix-induced autologous chondrocyte implantation (MACI) is a tissue engineering technique which requires the use of a collagen membrane on which the cultured chondrocytes are seeded. We report on the arthroscopic MACI technique for the treatment of chondral defects in the lateral tibial plate of the knee.

The implantation procedure was performed on two male patients affected by traumatic chondral lesions, 2.5 and 2 cm² in size, respectively. The procedures were performed through traditional artrhoscopic portals and the seeded membrane was fixed with fibrin glue. Clinical-functional evaluation was performed according to ICRS score, modified Cincinnati knee score, IKDC, Lysholm II and Tegner scales. MRIs were taken 6, 12 and 24 months postoperatively.

After 2 years all the clinical scores were improved in both patients. MRI showed filling of the defects with hyaline-like tissue with reduction of subchondral bone oedema and restoration of a regular articular surface.

Even though the MACI technique is mostly performed with an open procedure, the site of these lesions could not be reached without sacrifying tendinous and ligamentous structures of the knee. With the arthroscopic approach an optimal view of the lesion could be achieved and appeared to be the best solution for these patients. The size of these defects was too large for bone marrow stimulation techniques and/or osteochondral grafts to be successful. By using fibrin glue for fixating the seeded membrane the procedure could be performed arthroscopically in a simple and safe way. No specifically designed instruments were used in these cases.

We report the clinical results and MRI findings observed in 50 patients who underwent collagen meniscus implant (CMI) between March 2001 and October 2003. Fifty patients affected by irreparable meniscal lesions or who had previously undergone partial medial meniscectomy were arthroscopically treated with CMI, a tissue engineering technique designed to promote meniscal regeneration. Average age at the time of surgery was 38.4 years. The average size of the lesion/defect was 4.3 cm. Additional procedures included 16 ACL reconstructions, eight high tibial osteotomies and two autologous chondrocyte implantations. All knees were evaluated according to the Lysholm II and Tegner activity scales. MRI was performed 6, 12 and 24 months postoperatively. Six arthroscopic examinations of the implant were performed at different times (6 to 16 months postoperatively).

Postoperative complications included saphenus neuroapraxia in three patients and CMI rupture in one patient who presented with persistent knee swelling. Follow-up averaged 16.5 months, with a minimum of 6 months. At the most recent evaluation, 46 patients showed an improvement in the clinical scores. A progressive, uniform signal was evident by MRI. At the second arthroscopic study, free fragments of the implant were observed in cases of CMI rupture. In another patient, partial resorption of CMI was observed at the posterior horn. The remaining four arthroscopic examinations demonstrated regeneration of meniscal-like tissue.

Clinical results achieved with CMI are promising. MRI proved to be an effective tool for monitoring the evolution of the implant and showed good correlation with clinical outcomes and arthroscopic findings at follow-up.

Collagen meniscus implant (CMI) is a tissue engineering technique for the management of irreparable meniscal lesions. In this study we evaluate morphological and biochemical changes occurring in CMI after implantation. Gene expression technique was also adopted to characterise the phenotype of the invading cells.

Light microscopy, immunohistochemistry (type I and II collagen), SEM and TEM analysis were performed on five biopsy specimens harvested from five different patients (range, 6 to 16 months after surgery). Fluorophore-assisted carbohydrate electrophoresis (FACE) and real-time PCR evaluation were carried out on two biopsy specimens harvested 6 and 16 months, respectively, after implantation. All these investigations were also applied on non-implanted scaffolds for comparison.

Scaffold sections appeared to be composed of parallel connective laminae, connected by smaller connective bundles surrounding elongated lacunae. In the biopsy specimens, the lacunae were filled by connective tissue with newly formed vessels and fibroblast-like cells. Immunohistochemistry revealed exclusively type I collagen in the scaffold, while type II collagen appeared in the biopsy specimens. FACE analysis carried out in the scaffold did not detect any GAG disaccharides. Conversely, disaccharides were detected in the implants. Real-time PCR showed a signal only for collagen type I. In the scaffolds no gene expression was recorded.

The morphological findings demonstrate that CMI is a biocompatible scaffold available for colonisation by connective cells and vessels. Biochemical data show a specific production of extracellular matrix after implantation. The absence of signal for type II collagen gene can be attributed to different maturation stages of the in-growing tissue.

We prospectively evaluate clinical results and MRI findings on a series of 47 patients, with an average age of 31.7 years, treated by matrix-induced autologous chondrocyte implantation (MACI) for knee and ankle chondral defects.

As isolated lesions, the joints affected were 37 knees and five ankles. As combined lesions, there were four knees and one kissing lesion in the ankle. The average size of the defects was 3.5 cm². Clinical-functional evaluation was carried out according to ICRS, modified Cincinnati knee, Lysholm II and Tegner scales. The AOFAS score was used for the evaluation of the ankle. MRIs were taken before the operation as well as at 6, 12 and 24 months postoperatively. Among 10 second arthroscopic studies (four knees, six ankles), two biopsies were carried out after 2 years, from the medial femoral condyle and the patella, respectively. These specimens were evaluated by light microscopy, immunohistochemistry (type I and II collagen), SEM and TEM analysis.

Follow-up averaged 25.6 months. At the latest follow-up, knee scores improved after surgery. AOFAS did not improve in the patient with the kissing lesion. MRIs showed hyaline-like cartilage at the site of implantation in all treated joints with exception of the kissing lesion; four knees showed recurrence of subchondral bone oedema 1 year after surgery. Histological analysis on the biopsies revealed good definition of the tidemark and presence of type II collagen.

Clinical results and MRI findings support the efficacy of the MACI technique. Morphological findings are indicative for hyaline-like tissue formation in the implant site.

Aim: Collagen meniscus implant (CMI) is a tissue engineering technique for the management of irreparable meniscal lesions. In this study we evaluate morphological and biochemical changes occurring in CMI after implantation, in order to better define tissue ingrowth inside the scaffold. Gene expression technique was also adopted to characterize the phenotype of the invading cells. Methods and materials: Morphological analysis was performed by light microscopy, immunohistochemistry (type I and II collagen), SEM and TEM on 5 biopsy specimens, harvested from 5 different patients (range, 6 to 16 months after surgery). Biochemical evaluation was carried out using Flurophore Assisted Carbohydrate Electrophoresis (FACE): this assay allowed to measure glycosaminoglycans (GAG) production in extracellular matrix of 2 biopsy specimens, harvested respectively 6 and 16 months after implantation. Real Time PCR was performed on the same 2 biopsy samples for detecting tissue-specific gene expression (collagen); RNAaseP gene expression was used as housekeeping gene. All these investigations were also applied on non implanted scaffolds for comparison.

Results: Scaffold sections appeared composed by parallel connective laminae of 10-30B5m, connected by smaller (5-10B5m) connective bundles, surrounding elongated lacunae of 40-60B5m in diameter. In the biopsies specimens, the lacunae were filled by connective tissue with newly formed vessels and fibroblast-like cells. In the extracellular matrix, the collagen fibrils showed uniform diameters. The original structure of CMI was still recognizable and no inflammatory cells were detected inside the implant. A more organized architecture of the fibrillar network was evident in specimens with longer follow-up. Immunohistochemistry revealed exclusively type I collagen in the scaffold, while type II collagen appeared and was predominant in the biopsies specimens. FACE analysis carried out in the scaffold did not detect any GAG disaccharides. Conversely, high amount of disaccharides (unsulphated chondroitin, 4 and 6 sulphated chondroitin) were detected, together with hyaluronan, in the implants. Real Time PCR showed signal for Collagen type I alpha 1 and no signal for Collagen type II alpha 1. In the scaffolds used for comparison, no gene expression was recorded.

Conclusions: The morphological findings of this study demonstrate that CMI acts as a biocompatible scaffold which provide a three-dimensional structure available for colonization by connective cells and vessels. Biochemical data are consistent with an active and specific production of extracellular matrix in the scaffold after implantation. The absence of signal for type II collagen gene in biopsies specimens can be attributed to different maturation stages of the ingrowing tissue.

Aims: Collagen meniscus implant (CMI) is a tissue engineering technique for the management of irreparable meniscal lesions. We report early clinical results achieved on 30 patients. The implant was also investigated by ultrastructural and biochemical analysis. Methods: Thirty patients, affected by irreparable meniscal lesions, were arthroscopically treated. Average age at the time of surgery was 38.6 years. Additional procedures included 8 ACL reconstruction, 2 high tibial osteotomy and 1 autologous chondrocyte implantation. All knees were evaluated according to the Lysholm II and Tegner activity scales. MRI was performed 6 and 12 months postoperatively. A biopsy of the implant was performed in occasion of a second arthroscopic look in two patients 6 months after surgery. The specimens, as well as the scaffold before implantation, were studied by light microscopy, TEM, SEM, EDAX microanalysis, HPLC and FACE analysis. Results: Follow up averaged 9.3 months. At 3 months, 27 patients showed an increase in the clinical scores. A progressive uniform signal was evident by MRI. Morphological analysis of the speciments showed hyaline tissue inþltrated by cells and vessels, surrounded by the scaffold þbers. At EDAX microanalysis no calciþcations were detected inside the speciments. Biochemical assays demonstrated the presence of GAG molecules of hyaluronic acid and chondroitinsulphate, that were not present in the scaffold before implantation. Conclusions: Early CMI results are promising and are supported by morphological and biochemical þndings, that indicate enhancement of new meniscal tissue by the scaffold.

Methods: The implantation procedure was performed on two male patients affected by traumatic chondral lesions, sized respectly 2.5 and 2 cm². The operations were performed through traditional artrhoscopic portals and the seeded membrane was þxed with þbrin glue. Clinical-functional evaluation was performed acc. Aims: Matrix-induced autologous chondrocyte implantation (MACÏ) is a tissue engineering technique which requires the use of a collagen membrane on which the cultured chondrocytes are seeded. We report the arthroscopic MACÏ technique for the treatment of chondral defects interesting the lateral tibial ording to ICRS score, modiþed Cincinnati knee score, IKDC, Lysholm II and Tegner scales. MRIs were taken 6 and 12 months postoperatively. Results: After one year all the clinical scores were improved in both patients. MRI showed þlling of the defects with hyaline-like tissue with reduction of subchondral bone edema. Conclusions: Even though the MACÏ technique is mostly performed with an open procedure, the site of these lesions could not be reached without sacrifying tendinous and ligamentous structures of the knee. The arthroscopic approach allowed to achieve an optimal view of the lesion and appeared the best solution for these patients. The size of these defects was too large for bone marrow stimulation techniques and/or osteochondral grafts to be successful. The development of dedicated instruments for arthroscopic MACÏ will allow to improve and simplify the surgical procedure.