Intra-articular delivery of chondroitin sulfate for the treatment of joint defects in rabbit model

Chondroitin sulfate (CS) is considered as a possible candidate for the treatment of joint defect. This study is to evaluate the efficacy of intra-articular injection of CS carried by hydrogel in the treatment of chondral defects in adult rabbit models. Inclusion of CS (0-50 microg/ml) in in vitro chondrocyte culture exerts a dose-dependent increase in cell proliferation. To select for optimal carrier for in vivo study, the release kinetic of CS embedded in five types of hydrogel was studied using fluorescence technique and their biocompatibilities in vivo were investigated by injecting the CS-hydrogel into rabbit knees. alpha-CD-EG 4400 hydrogel was chosen as the carrier based on progressively released CS from the hydrogel, with 80% released by in one week while the remaining 20% was retained for 30 days. In vivo studies showed high biocompatibility of CS-hydrogel. To evaluate the efficacy of CS in the treatment of cartilage injury, chondral defects were created in femoral medial condyle (punch diameter 2.7 mm) or trochlea (punch diameter 3.5 mm) of the rabbits without damaging subchondral bone. CS (100 mg/ml) in 0.5 ml alpha-CD-EG 4400 hydrogel was then injected into the knee joint. Hydrogel and saline served as controls. On day 50 the chondral defect in the saline group showed no signs of healing and defect treated with hydrogel alone was covered with a thin and slightly irregular layer of fibrous tissue. The CS-hydrogel group showed a thicker layer composed of both hyaline and fibrocartilage. The modulus of elasticity was the highest in the CS-hydrogel group and lowest in the group injected with saline only. Our results suggest that intra-articular delivery of CS by alpha-CD-EG 4400 improved the biomechanical and histological properties of the repaired cartilage. It may be an effective treatment for cartilage injury.

Osteochondral fracture of the fourth metatarsal head treated by open reduction and internal fixation

Fracture of the metatarsal head is uncommon, and reports of isolated osteochondral fracture of the metatarsal head are rare. Because of the distal location of the fracture, it is difficult to achieve and maintain reduction, and potential complications include avascular necrosis and subchondral fatigue fracture. The authors present a case of an osteochondral fracture in a 40-year-old man, which was treated by open reduction and internal fixation with a single twist-off screw, with good results 12 months postoperatively.

Tracheal cartilage regeneration by slow release of basic fibroblast growth factor from a gelatin sponge

OBJECTIVE

We investigated whether implantation of a gelatin sponge, releasing basic fibroblast growth factor slowly (b-FGF) into a tracheal cartilage defect, would induce regeneration of autologous tracheal cartilage.

METHODS

We created a 1-cm defect in the midventral portion of each of 10 consecutive cervical tracheal cartilage rings in 12 experimental dogs. In the control group (n = 4), the resulting defects were left untreated. In the gelatin group (n = 4), empty gelatin sponges were implanted in the defects. In the basic fibroblast growth factor group (n = 4), gelatin sponges incorporating 100 microg of b-FGF solution were implanted in the defects. We killed the 4 dogs in each group at 1, 3, 6, and 12 months after implantation, respectively, and examined the implant sites macro- and microscopically.

RESULTS

In the control and gelatin groups, no regenerated cartilage was observed in the tracheal cartilage defects, and the width of the gap between the host cartilage stumps had shrunk. In the b-FGF group, regenerated cartilage was observed in all dogs. The proportion of the defect in the host cartilage occupied by regenerated cartilage was 13%, 84%, 75%, and 69% at 1, 3, 6, and 12 months, respectively. The regenerated cartilage was fibrous cartilage covered with perichondrium, which grew from the host perichondrium and showed continuity with the host cartilage stumps.

CONCLUSIONS

Implantation of a gelatin sponge slowly releasing basic fibroblast growth factor induces tracheal cartilage regeneration, which subsequently fills a large proportion of experimentally created tracheal cartilage defects within 12 months after implantation.

Morphologic, experimental–comparative investigation as an identification of the injuring instrument method

Aiming to identify the injuring tool characteristics and the tool itself morphologic, experimental-comparative investigations of the skin wound, rib and cartilage injuries taken during the autopsy are performed. During 1995-2004, 489 investigations were performed for this purpose. In 418 cases, knives were submitted for identification of the specific injuring tool (in total-835 knives). In 205 cases the investigation included not only skin wounds, but also the injured rib cartilages. Identification investigations were performed by investigating both the skin wounds morphologic characteristics and dynamic traces-trails in the rib cartilage tissue left by the micro relief of the knife blade edge. In the case of the investigated and experimental skin wounds characteristics coincidence the experimental and comparative dynamic traces investigation was performed when the traces were suitable for the tool identification purposes. In the case of the investigated and experimental skin wounds, dynamic traces coincidence, the totality of the coincided characteristics was considered individual. In those cases, the conclusion included the fact that the injury had been made by a particular knife. According to our data during 1995-2004 in 23 cases-15.9% (5.5% out of the total investigated cases), the knife identification was based on the skin wound characteristics and dynamic traces in the rib cartilage tissue. In our opinion, the dynamic traces in the rib cartilage tissue investigations supplement the identification field and are valuable in the tool identification. In 11 (2.6% out of the total investigated cases) cases knives were identified only by the skin wounds morphologic characteristics, the ribs being not injured or dynamic traces being not suitable for the tool identification.

The response of costal cartilage to mechanical injury in mice

BACKGROUND

The healing potential of articular cartilage in response to injury is poor, because articular cartilage lacks blood vessels or perichondrium. Costal cartilage is covered with a vascularized perichondrium, which is known to have chondrogenic potential. The purpose of this study was to determine whether costal cartilage can heal in response to mechanical injury.

METHODS

Sixty-five ICR mice were used. Under anesthesia, the left tenth costal cartilage was dissected using microscissors. At 1 day and at 1, 2, 3, and 12 weeks after injury, the mice were killed and paraffin sections were prepared. Safranin O staining, in situ hybridization of type II collagen, and immunostaining for CD44 were performed. Localization of cell proliferation was performed using immunohistochemistry with bromodeoxyuridine monoclonal antibody. In situ detection of apoptosis (deoxynucleotidyl transferase-mediated dUTP nick end labeling) was performed using an Apop Tag Kit.

RESULTS

From 1 to 2 weeks after costal cartilage injury, bromodeoxyuridine-positive cells were observed in the perichondrium. Two weeks after injury, the dissected cartilage fragments had combined with newly formed safranin O-positive tissue. Type II collagen mRNA was strongly expressed in the cells of the newly formed tissue. Apoptosis was detected in newly formed cartilaginous tissue at 1 and 2 weeks after injury. The cartilage fragments failed to unite at 12 weeks after injury. CD44 immunoreactivity was detected on the surface of the cavity between the cartilage fragments.

CONCLUSION

Although the dissected fragments of costal cartilage can combine with newly formed cartilaginous tissue temporarily, they fail to unite ultimately.

Cyclic compression loaded on cartilage explants enhances the production of reactive oxygen species

OBJECTIVE

Although mechanical forces are an essential factor in the regulation of cartilage metabolism, the precise mechanisms involved have not yet been determined. We previously demonstrated that mechanical forces on chondrocytes inhibited proteoglycan (PG) synthesis. We also demonstrated the induction of reactive oxygen species (ROS) is loaded on the chondrocytes. Our purpose was to determine the ROS induction with mechanical compression and its involvement in PG synthesis of cartilage slices.

METHODS

Bovine articular cartilage slices were subjected to cyclic compression loading. Synthesis of PG and ROS was measured using Na2[35S]-SO4 and a chemiluminescent probe, respectively. The induction of nitrotyrosine was determined using immunohistochemistry.

RESULTS

The synthesis of PG was significantly inhibited with 2.0 MPa of compression stress; 1 h of compression was sufficient to inhibit PG synthesis. The ROS inhibitor ebselen reversed the compression-inhibited synthesis of PG. Compression on the cartilage induced synthesis of ROS and the expression of nitrotyrosine.

CONCLUSION

Mechanical compression at 2.0 MPa inhibited PG synthesis by cartilage explants. ROS were involved in this action.

Engineering cartilage with human nasal chondrocytes and a silanized hydroxypropyl methylcellulose hydrogel

Tissue engineering strategies, based on developing three-dimensional scaffolds capable of transferring autologous chondrogenic cells, holds promise for the restoration of damaged cartilage. In this study, the authors aimed at determining whether a recently developed silanized hydroxypropyl methylcellulose (Si-HPMC) hydrogel can be a suitable scaffold for human nasal chondrocytes (HNC)-based cartilage engineering. Methyltetrazolium salt assay and cell counting experiments first revealed that Si-HPMC enabled the proliferation of HNC. Cell tracker green staining further demonstrated that HNC were able to form nodular structures in this three-dimensional scaffold. HNC phenotype was then assessed by RT-PCR analysis of type II collagen and aggrecan expression as well as alcian blue staining of extracellular matrix. Our data indicated that Si-HPMC allowed the maintenance and the recovery of a chondrocytic phenotype. The ability of constructs HNC/Si-HPMC to form a cartilaginous tissue in vivo was finally investigated after 3 weeks of implantation in subcutaneous pockets of nude mice. Histological examination of the engineered constructs revealed the formation of a cartilage-like tissue with an extracellular matrix containing glycosaminoglycans and type II collagen. The whole of these results demonstrate that Si-HPMC hydrogel associated to HNC is a convenient approach for cartilage tissue engineering.

Medial patellofemoral ligament reconstruction: a novel technique using the patellar ligament

In patients with chronic patellofemoral instability, more than 2 episodes of dislocation, and an anterior tuberosity trochlear groove of less than 20 mm as measured on computed tomography or nuclear magnetic resonance imaging, we have developed a technique for medial patellofemoral ligament reconstruction that uses a medial strip of the patellar ligament (PL). The incision started proximally at the level of the superior margin of the patella, centrally between the patellar medial margin and the medial epicondyle. A descending incision was then made, directed toward the superomedial margin of the tibial tubercle. We performed a plane-by-plane dissection up to the peritenon of the PL. With an osteotome, we could remove a 2-cm bone fragment concerning the medial third of the distal insertion of the PL or keep the distal end free. Using a No. 11 scalpel blade, we carefully detached the PL from the patella up to the transition between the proximal third and medial third of the patella. We placed the stitches between the periosteum and the ligament using FiberWire absorbable threads (Arthrex, Naples, FL) to safely rotate the graft. After that, we dissected the medial capsule and approached the femoral medial epicondyle. Then we placed a Krackow suture in the free tendon end using absorbable threads or anchored the threads into 2 holes that were previously drilled, and we secured the end with an absorbable interference screw or anchors. The fixation should be performed with the knee at 15 degrees to 30 degrees of flexion. Then we sutured the distal edge of the vastus medialis muscle to the graft, which bestows a dynamic component upon the reconstruction, and we immobilized the knee with a removable brace.

Prediction of the optimal mechanical properties for a scaffold used in osteochondral defect repair

The optimal mechanical properties of a scaffold to promote cartilage generation in osteochondral defects in vivo are not known. During normal daily activities cartilage is subjected to large cyclic loads that not only facilitate nutrient transport and waste removal through the dense tissue but also act as a stimulus to the chondrocytes. In contrast, cartilage tissue is commonly engineered in vitro in a static culture; hence, in many cases, the properties of scaffolds have been tailored to suit this in vitro environment. In this study, a mechanoregulation algorithm for tissue differentiation was used to determine the influence of scaffold material properties on chondrogenesis in a finite element model of an osteochondral defect. It is predicted that increasing the stiffness of the scaffold increases the amount of cartilage formation and reduces the amount of fibrous tissue formation in the defect, but this only holds true up to a certain threshold stiffness above which the amount of cartilage formed is reduced. Reducing the permeability of the scaffold was also predicted to be beneficial. Considering a nonhomogeneous scaffold, an optimal design was determined by parametrically varying the mechanical properties of the scaffold through its depth. The Young's modulus reduced nonlinearly from the superficial region through the depth of the scaffold, while the permeability of the scaffold was lowest in the superficial region. As tissue engineering moves from a science toward a product, engineering design becomes more relevant, and predictive models such as that presented here can provide a scientific basis for design choices.

Deformation and failure of cartilage in the tensile mode

The aim of this study was to visualize, at the ultrastructural level, the deformation and failure mechanism of cartilage matrix in the tensile mode. Full-thickness dumbbell-shaped specimens were prepared from adult bovines. There were two specimen groups; in the 'parallel' group the specimen axis was parallel to the split lines defining the preferential orientation of the collagen in the articular surface, and in the 'perpendicular' group the specimen axis was perpendicular to the split lines. Specimens were placed with the articular surface uppermost and subjected to a graded series of strain within individual mini-tension devices, while observed with stereomicroscopy and confocal laser scanning microscopy. Thereafter, the changes in the ultrastructure were observed with both scanning and transmission electron microscopy. The mechanism of cartilage failure in the tensile mode comprised the following stages, whether the strain was applied parallel or perpendicular to the split line. (1) At 0% strain a fibrillar meshwork within the articular surface was predominantly orientated in the direction of the split line. (2) As strain increased, the fibrillar meshwork became more orientated in the parallel group and reorientated in the perpendicular group in the direction of the applied strain. (3) After complete reorientation of the fibrillar meshwork in the direction of the applied strain, the initial sign of failure was rupture of the fibrillar meshwork within the articular surface. (4) Subsequently, the rupture rapidly propagated into the deeper layers. Greater strains were required for fibrillar reorientation and complete rupture in the 'perpendicular group' than in the parallel group.

Differential cell viability of chondrocytes and progenitor cells in tissue-engineered constructs following implantation into osteochondral defects

Animal studies in cartilage tissue engineering usually include the transfer of cultured cells into chondral or osteochondral defects. Immediately at implantation, the cells are exposed to a dramatically changed environment. The aim of this study was to determine the viability of two cell types currently considered for cellular therapies of cartilage defects-chondrocytes and progenitor cells-shortly after exposure to an osteochondral defect in rabbit knees. To that end, autogenic chondrocytes and periosteal cells were labeled with CM-DiI fluorochrome, seeded or cultured in PEGT/PBT scaffolds for periods up to 2 weeks, transferred into osteochondral defects, harvested 5 days postimplantation, and analyzed for cell viability. In order to further elucidate factors effecting cell viability within our model system, we investigated the effect of serum, 2) extracellular matrix surrounding implanted cells, 3) scaffold interconnectivity, and 4) hyaluronan, as a known cell protectant. Controls included scaffolds with devitalized cells and scaffolds analyzed at implantation. We found that the viability of periosteum cells (14%), but not of chondrocytes (65-95%), was significantly decreased after implantation. The addition of hyaluronan increased periostium cell viability to 44% (p < 0.05). Surprisingly, cell viability in less interconnected compression-molded scaffolds was higher compared to that of fully interconnected scaffolds produced by rapid prototyping. All other factors tested did not affect viability significantly. Our data suggest chondrocytes as a suitable cell source for cartilage repair in line with clinical data on several chondrocyte-based therapies. Although we did not test progenitor cells other the periosteum cells, tissue-engineering approaches using such cell types should take cell viability aspects into consideration.

A novel ex vivo culture system for studying bone repair

Repair of large bony defects still remains a challenge for surgeons. Hydroxyapatite (HA) is well known for its biocompatibility and osseoconduction properties in the osseous environment. In this study the biofunctionality of a newly developed scaffold comprising of collagen and HA, with variable macropores was examined. The biological response was evaluated using primary human osteoblast cells (HOBs). Cell infiltration, proliferation and differentiation were assessed. The results showed that HOBs were able to migrate from the collagen into the HA pores with greater cell migration and infiltration observed in those scaffolds with larger pores. Furthermore, it was shown that Alkaline Phosphatase, a differentiation marker for HOBs was enhanced as the average macropore size increased. This in vitro model provides a more relevant method of testing the biofunctionality and migration ability of cells at a trauma site following implantation in bone and cartilage.

Cellular events leading to chondrocyte death after cartilage impact injury

OBJECTIVE

We undertook this study to test our postulate that leukocytes extend the zone of injury in cartilage after acute mechanical trauma.

METHODS

Fresh cadaveric canine femoral condyles were subjected to 20-25-MPa impact injury. Condyle explants or dispersed chondrocytes were cultured with autologous blood mononuclear leukocytes (MNLs). Viability of chondrocytes at varying distances from the impact site was assessed by trypan blue exclusion.

RESULTS

Mechanical injury caused a significant loss of viable chondrocytes over 7 days, even in cartilage >10 mm from the impact site. After biomechanical stress, death of cells within 10 mm of the impact could be largely prevented by addition of N(G)-monomethyl-L-arginine to inhibit nitric oxide (NO) generation. Chondrocytes within 10 mm of the impact were also susceptible to killing by living MNLs, but not by incubation with the supernatants of endotoxin-activated MNLs. Chondrocytes in this vulnerable zone expressed intercellular adhesion molecule 1 (ICAM-1) (CD54), facilitating attachment of MNLs that localized adjacent to the chondrocytes. Leukocytes killed dispersed chondrocytes harvested from the impact zone by generation of reactive oxygen species. Leukocyte-mediated killing could be blocked by desferoxamine or by antibodies to CD18, which prevent attachment of leukocytes to ICAM-1-expressing chondrocytes.

CONCLUSION

Our data suggest that after mechanical injury, chondrocytes distant from the site may be killed through the generation of NO. Inflammatory leukocytes further extend the zone of chondrocyte death by adhering to chondrocytes expressing ICAM-1 and by inducing the accumulation of free oxygen radicals in the chondrocyte cytoplasm. Patients may benefit from therapies that reduce infiltration of inflammatory leukocytes into acutely injured cartilage.

The hip joint: arthroscopic procedures and postoperative rehabilitation

Recent technological improvements have resulted in a greater number of surgical options available for individuals with hip joint pathology. These options are particularly pertinent to the relatively younger and more active population. The diagnosis and treatment of acetabular labral tears have become topics of particular interest. Improvements in diagnostic capability and surgical technology have resulted in an increased number of arthroscopic procedures being performed to address acetabular labral tears and associated pathology. Associated conditions include capsular laxity, femoral-acetabular impingement, and chondral lesions. Arthroscopic techniques include labral tear resection, labral repair, capsular modification, osteoplasty, and microfracture procedures. Postoperative rehabilitation following arthroscopic procedures of the hip joint carries particular concerns regarding range of motion, weight-bearing precautions, and initiation of strength activities. Postoperative rehabilitation protocols that have been typically used for surgeries such as total hip arthroplasty are often not sufficient for the population of patients undergoing arthroscopic procedures of the hip joint. Postoperative rehabilitation should be based upon the principles of tissue healing as well as individual patient characteristics. As arthroscopic procedures to address acetabular labral tears and associated pathology evolve, physical therapists have the opportunity to play a significant role through the development of corresponding rehabilitation protocols.

[Typical injuries seen in football players]

Injuries seen in football players mainly affect the knee and ankle joints and muscles. The causes include chronic overstrain and traumatization usually resulting from physical contact between opponent players. Torsional trauma of the joints results in excessive stressing of the capsular ligaments, potentially leading to rupture of the structures involved. Therapeutic options range from conservative measures to reconstructive or prosthetic surgery. While muscular injuries have a good prognosis with regard to the chances of continuing sports activities, injuries to ligaments often enforce a lengthy pause from sports. Extensive injuries to cartilages can terminate a player's sporting career. However, new procedures that take account of physiological biomechanics, together with the further development of surgical technologies now often allow players to regain their pre-injury level of fitness. Specific rehabilitation is a major therapeutic means of preventing further injury.

Some medicolegally important aspects of symphyseal injuries due to trauma

A total of 58 cases of fatal trauma (forensic autopsies) were investigated for lesions of the pelvic girdle, the pubic symphysis, and for injuries distant from the pelvis. Traumata of the pubic symphysis were present in 30% (n = 17) of the cases. The symphyses were examined by x-ray and macroscopically related to the main violence (Abbreviated Injury Scale [AIS]). A correlation between the latter and the severity of the resulting injuries could be deducted. Characteristic patterns of symphyseal injuries included small hemorrhages, partial and complete ruptures, and also ruptures of the ligamentary insertions, which have not yet been described. The kind and severity of these lesions related to the intensity/direction of the violence are demonstrated and discussed.

Can CT determine the site of traumatic osteochondral defects in the paediatric knee?

Currently the ability of pre-operative CT imaging to determine the origin of traumatic osteochondral lesions (OCL) in the knee in children is yet to be established. The surgical approach to the knee will to some extent be determined by the origin of the lesion. It is important to directly determine the site of the lesion from pre-operative scanning both to facilitate surgery, to have a better cosmetic result for the patient and have a quicker rehabilitation period. In a tertiary referral centre, from May 2004 to April 2005, eight patients were diagnosed as having an OCL. The initial reporting was done by either a senior registrar or consultant paediatric radiologist. Those children that had an OCL underwent an arthroscopy or definitive open surgery. The exact site of the lesion was then determined and recorded in the operative notes. All the original pre-operative CT scans were given to a senior paediatric radiologist. The consultant on this occasion had no access to operative findings, or original CT reports. CTs reported by the paediatric radiology department are only able to correctly identify the site of origin of the OCL 50% of the time. Recent MR scanning techniques have improved the visualization of OCL. We authors therefore feel that in the future MRI should be used to assess the paediatric knee when an acute OCL is suspected.

[Imaging of cartilage]

The motivation for cartilage repair is the preservation of adequate joint motion. Repairing joint surface congruity and providing balanced load bearing are crucial for this. MRI can contribute to this goal by describing number, depth, size, and distribution of cartilage lesions throughout the different joint compartments. Essential to such a contribution are adequate spatial resolution at a reasonable SNR together with good contrast between both cartilage and the subchondral bone as well as the joint space. For TSE sequences, this is achieved using TEs between 30 and 50 ms. Diagnostic accuracy is optimal when a lesion is depicted in more than one plane. Short TE, high bandwidth, and the appropriate orientation of the frequency encoding direction contribute to minimizing metal artifacts. Besides internal alterations of the cartilage's matrix, moderately T2-weighted TSE sequences sensitively depict bone marrow edema such as signal alterations and joint effusion, both contributing to highlight even subtle cartilage lesions. T1-weighted FS/WE 3D GE sequences profit from their high spatial resolution to appreciate gradual erosion of the cartilage. In OD the interface to the surrounding bone, the integrity of the overlying cartilage, and associated cysts are used to determine stability. The presence of two or more findings increases diagnostic accuracy. Prognosis is associated with the size of the affected area.

Fresh bone marrow and periosteum transplantation for cartilage defects of the knee

The aim of work was to analyze clinical effectiveness of fresh bone marrow and periosteum transplantation in the treatment of traumatic or degenerative cartilage defects. The 14 patients in this study had a mean age of 37 years. Bone marrow aspirated from the iliac crest was implanted under the periosteum sutured over the defect. Three, 6, and 12 months postoperatively, the patients were evaluated with the analogue pain scale, modified Cincinnati score, and IKDC questionnaires. All patients were evaluated with magnetic resonance imaging (MRI) at 3 and 12 months postoperatively. After 3 and 6 months significant improvement was observed in eight patients. After 12 months, 12 patients were classified as normal or nearly normal in the IKDC examination form, and two as abnormal. Mean IKDC Subjective Knee Score was 86.57. MRI findings revealed surfaces with correct contours and continuity, without changes in subchondral bone in all but one patient. There was a correlation between a large size of defect or an osteoarthritic nature of the changes and poor results.