Fate of a chimeric joint construct in an ectopic site in SCID mice.

This study examines the use of a devitalized biological knee as a scaffold for repopulation with chondrocytes and tests the hypothesis that the devitalized scaffold would become repopulated with the foreign chondrocytes when placed in a suitable environment. Chimeric knee constructs were engineered in vitro and their ectopic in vivo fate was examined in SCID mice. The constructs were made by applying porous collagen sponges that contained viable bovine articular chondrocytes to shaved articular surfaces of devitalized embryonic chick knees.

Cell-based therapy for meniscal repair: a large animal study.

Background: The avascular portion of the meniscus cartilage in the knee does not have the ability to repair spontaneously.

Hypothesis: Cell-based therapy is able to repair a lesion in the swine meniscus.

Study Design: Controlled laboratory study.

Engineering a joint: a chimeric construct with bovine chondrocytes in a devitalized chick knee.

This study assessed the feasibility of a devitalized knee as a scaffold for an engineered chimeric joint. Embryonic chick knees (19 days old), devitalized by lyophilization or multiple freeze-thaw cycles, were tested as scaffolds for repopulation with bovine articular chondrocytes (bACs). bACs were seeded into porous three-dimensional collagen sponges and were cultured for 1 day before fabrication of chimeric constructs.

Heterotopic ossification around the elbow following burns in children: results after excision.

Background: Major burn injuries close to joints alter the function of the musculoskeletal system through tissue loss and limitation of joint motion. In children with involvement of the hand, wrist, and forearm, restriction of elbow motion secondary to heterotopic ossification following a burn injury severely limits the function of the upper extremity. The purpose of this study was to review elbow function following excision of heterotopic ossification around the elbow in children.

Primary treatment of chondroblastoma with percutaneous radio-frequency heat ablation: report of three cases.

Chondroblastomas are benign cartilaginous lesions; however, intervention is necessary to stop progression and alleviate pain. The authors evaluated three patients in whom minimally invasive percutaneous radio-frequency heat ablation was used to treat pathologically proven chondroblastoma to determine whether this treatment demonstrated long-term success. The authors found that this approach may be an effective alternative to surgical intervention in some cases.

Effects of hyaluronan on engineered articular cartilage extracellular matrix gene expression in 3-dimensional collagen scaffolds.

Hyaluronan (HA) is a component of cartilage matrix with known effects on chondrocytes. We tested the effects of adding HA to 3-dimensional (3-D) collagen. sponges on chondrocyte function in vitro.

Meniscal repair using engineered tissue.

In this study, devitalized meniscal tissue pre-seeded with viable cultured chondrocytes was used to repair a bucket-handle incision in meniscal tissue transplanted to nude mice. Lamb knee menisci were devitalized by cyclic freezing and thawing. Chips measuring four by two by one-half millimeters were cut from this devitalized tissue to serve as scaffolds.

Biomechanical analysis of a chondrocyte-based repair model of articular cartilage.

The objective of this study was to evaluate the biomechanical properties of newly formed cartilaginous tissue synthesized from isolated chondrocytes. Cartilage from articular joints of lambs was either digested in collagenase to isolated chondrocytes or cut into discs that were devitalized by multiple freeze-thaw cycles. Isolated cells were incubated in suspension culture in the presence of devitalized cartilage matrix for 3 weeks.

Long-term patient-oriented outcome study of a modified Evans procedure.

More than 50 surgical procedures have been described for treatment of chronic lateral ankle instability. Anatomic repairs have come into favor in the recent literature based on short-term studies, which have used objective measures for outcome. A long-term (range, 7-20 years; average, 12.

Recapitulation of signals regulating embryonic bone formation during postnatal growth and in fracture repair.

A number of proteins have recently been identified which play roles in regulating bone development. One important example is Indian hedgehog (Ihh) which is secreted by the prehyprtrophic chondrocytes. Ihh acts as an activator of a second secreted factor, parathyroid hormone-related protein (PTHrP), which, in turn, negatively regulates the rate of chondrocyte differentiation.

Bonding of cartilage matrices with cultured chondrocytes: an experimental model.

The capacity of isolated chondrocytes to join separate masses of cartilage matrix was investigated with composites implanted in subcutaneous pouches in nude mice. Slices of articular cartilage were harvested from lambs and were devitalized by cyclic freezing and thawing. The slices were then either co-cultured with viable allogeneic lamb chondrocytes (experimental) or cultured without such chondrocytes (control).

Response of physeal cartilage to low-level compression and tension in organ culture.

The clinical response of growth plate to exogenous forces is well recognized, although the organ-level mechanisms are poorly understood. Physeal cartilage from 5- to 7-day-old bovine distal radii was subjected to 245 N of tension or 245 N of compression (0.012 MPa) in organ culture over a 24-h period.

Extremity lawn-mower injuries in children: report by the Research Committee of the Pediatric Orthopaedic Society of North America.

In a multicenter study of pediatric lawn-mower injuries (push or riding gas-powered machines), we reviewed 144 children at an average age of injury of 7.0 years; 77% were boys. Most injuries (92 of 104) occurred in the afternoon.

Repopulation of laser-perforated chondroepiphyseal matrix with xenogeneic chondrocytes. An experimental model.

Growth of chondrocytes into a xenogeneic chondroepiphyseal matrix was investigated in an in vitro experimental model by combining viable calf chondrocytes with chick epiphyseal matrix devoid of viable chondrocytes. The chondrocytes were harvested from the wrist joints of newborn calves and cultured for 2 days. The epiphyses were harvested from the distal femurs and the proximal tibias of fetal chicks after development was arrested at 17 days by freezing.

Familial aspects of Caffey's disease.

Caffey's disease is a cortical hyperostosis, which presents during infancy. Etiology remains unclear. Familial occurrence has been documented in the literature.

Epiphyseal replacement in a murine model.

Epiphyseal replacement was performed via knee transplantation using donor tissue of different developmental times in a murine model. The performance of syngeneic donor tissue in a resection defect in 4-day-old mice of the same inbred strain was assessed over 2 weeks for cell viability, tritiated thymidine incorporation, and ability to attract a host blood supply, and at 2 months, with the existence of a joint and growth. Although there was variability within experimental groups, the syngeneic transplant was able to survive pending vascular invasion from the host.

A complex bilateral polysyndactyly disease locus maps to chromosome 7q36.

We demonstrated that the gene responsible for a congenital limb deformity (polysyndactyly) maps to chromosome 7q36 in a large family. Pre- and postaxial anomalies of the extremities are inherited in this family as an autosomal dominant trait. The disease locus is closely linked to D7S550 (maximum lod score = 6.

Indirect trauma to the growth plate: results of MR imaging after epiphyseal and metaphyseal injury in rabbits.

Abnormalities of the growth plate secondary to epiphyseal and metaphyseal injury were studied with magnetic resonance (MR) imaging, radiography, and histologic examination in 20 rabbits. Epiphyseal injury resulted in either the formation of a bony bridge across the growth plate or focal curving of the growth plate caused by a decrease in longitudinal growth. Metaphyseal injury resulted in interference with endochondral ossification, thickening of the growth plate, and extension of cartilage into the metaphysis.

Physeal replacement with cultured chondrocytes of varying developmental time: failure to reconstruct a functional or structural physis.

Reconstruction of physeal regions excised from the distal femoral chondroepiphysis was attempted in a murine model. Cultured chondrocytes of varying developmental time from the same inbred strain of mice were used for replacement. Vascularity, matrix formation, and cell division, as well as growth, were assessed.

Magnetic resonance imaging of the epiphysis: an experimental study.

The purpose of this study was to determine if metabolically altered cartilage could be distinguished from normal cartilage in the epiphysis by magnetic resonance imaging. Epiphysis from ten New Zealand White rabbits and five newborn lambs were imaged before and after heat-killing. The physiological change produced was documented with tritiated thymidine and radioactive sulfate autoradiography.