Introduction: Articular cartilage injuries are very common, and if untreated can become symptomatic and progressively lead to premature osteoarthritis. It is well known that damaged cartilage has very limited potential to heal itself, and repair and regeneration of hyaline cartilage remain a clinical and scientific challenge. There are no pharmacological methods that can regenerate cartilage, and currently clinical treatments of debridement, chondrocyte transplantation and marrow stimulation have not been shown to restore consistently a durable articular surface. Tissue engineering and gene therapy concepts may improve cartilage repair by introducing cells, scaffolds, growth factors and other potential modulators of cartilage healing process. When analyzing cartilage treatment outcomes, traditionally we use macro- and microscopic assessment, immunohistochemistry, biochemical characterization etc. Recently, it has been postulated that biomechanical properties of newly formed cartilage are just as important, and novel methods of measurements have been proposed.

Materials and methods: 38 defects were created on weight-bearing part of the medial femoral condyle in sheep. The sheep were randomly assigned to one of four groups. In the bone marrow clot (BMC) group, the sheep were implanted with untreated autologous bone marrow clot that was aspirated from iliac crest of respected animal. In the bone marrow transduced with Ad. GFP (GFP) group, the sheep were implanted with autologous bone marrow clots genetically modified to over express green fluorescent protein (GFP). In the bone marrow transduced with Ad. TGF-β1 (TGF) group, the sheep were implanted with autologous bone marrow clots genetically modified to over express transforming growth factor-β1. Untreated sheep served as a control (defect without implant), and native cartilage served as positive control. Specimens were collected after 6 months and analyzed by single-impact micro-indentation (SIMI), atomic force microscope (AFM) and scanning electron microscope (SEM).

Results: SIMI and AFM measurements showed that repair tissue has greater Young’s elastic modulus then native cartilage. There was a statistically significant difference between TGF-β1, GFP and BMC groups. SEM analysis showed presence of structurally organized collagen molecules in TGF-β1, GFP and BMC groups.

Conclusion: The results of this study showed that it is possible to enhance cartilage repair process by means of genetically modified bone marrow. Furthermore, biomechanical data obtained with SIMI, AFM and SEM provided more detailed insight into articular cartilage function and structure, and in future may be of practical importance for a better understanding of both cartilage mechanics and cartilage disease progression.

Background: Bone morphogenetic proteins (BMPs) induce new bone in patients with bone defects and at extraskeletal sites in animals. Standard treatment for symptomatic scaphoid non-unions is bone graft with or without internal fixation by a screw or wires. We tested the ability of human recombinant osteogenic protein-1 (OP-1, BMP-7) with compressed autologous or allogeneic bone graft to accelerate the healing of scaphoid non-union.

Study Design: Randomized and controlled pilot study in 17 patients with a scaphoid nonunion.

Methods: Patients were randomly assigned to one of three groups: (1) Autologous iliac graft (n=6), (2) Autologous iliac graft + OP-1 (n=6) and (3) Allogeneic iliac graft + OP-1 (n=5). Radiographic, scintigraphic and clinical outcomes were assessed throughout the follow-up period of 24 months.

Results: OP-1 improved the performance of both autologous and allogeneic bone implants. Three dimensional helical CT scans and scintigraphy showed that the pre-existing sclerotic bone within proximal scaphoid poles was mainly replaced in OP-1 treated patients with well vascularized new bone. Addition of OP-1 to allogeneic bone implant equalized the clinical outcome with the autologous graft procedure and enabled circumventing the second donor graft harvest procedure resulting in less blood loss, shorter anesthesia and no pain at the donor side.

Conclusion: This is the first evidence that a recombinant human BMP accelerates scaphoid bone non-union repair and resorption of sclerotic bone in this specific microenvironment.

Clinical Relevance: OP-1 might be successfully used in healing of scaphoid non-union.

130 patients with idiopathic thoracic scoliosis were operated on by means of the same anterior instrumentation principle in the period from 1987 through 1998. There were 21 males and 109 females in the age of 16(±4). Patients were randomly chosen in the group with rib hump apical osteotomy added to the anterior instrumentation (group 1) and the group with the anterior instrumentation without rib hump osteotomies (group 2). A prospective study was performed. Preoperative and postoperative gibbometry was performed. Results were as follows: frontal correction: 67% for group 1., and 74% for group 2. Rib hump changed from 23 ± 15 to 6 ± 6.2 (74%) for group 1, and 20 ± 1.5 mm (62%) for group 2. Rib valley changed from 21 ± 11 to 7 ± 4 (63%) (group 1) and 37 ± 2.8 to 16 ± 3.4 (56%) (group 2). There were 4 hematothoraxes in group 2. and no haematothoraxes in group 1. It seems that rib hump osteotomy has no inßuence upon frontal scoliosis correction, and little inßuence upon rib valley correction. Signiþcant inßuence was noted upon rib hump correction. It might be that better spinal release and consecutive smaller corrective forces resulted in absence of haematothoraxes in group 1.

Inßuence of scoliosis surgery on pulmonary changes and even upon thoracic deformity changes are still controversial. The purpose of the study was to determine thoracic volume (TV) changes in patients operated on by means of posterior and anterior surgery because of severe thoracic AIS. 50 patients, operated by þrst author randomly chosen from the period 1993–97 were selected. In 25 patients (21 girls, 4 boys) anterior instrumentation was used (group 1), and posterior instrumentation in other 25 patients (20 girls, 5 boys; group 2). TV calculation was performed basing on preoperative and postoperative plain x-rays, using a well known equation (second and third, independent author). The curves were 73û ± 12.4 pre op, and 19û ± 15 post op (group 1), and 75û ±13 pre op., 37û± 10 post op. (group2). Calculated TV for group 1 increased from 5234 ml to 6043 ml postoperatively (17% ± 16). In group 2, TV increased from 5155 to 5489 to 4,371 (6% ± 7). The correlation between the Cobb angle change and the thoracic volume change was poor (+0.2 for group 1, -0.4 for group 2). To determine the role of frontal, sagital and vertical thoracic diameters in TV increase, further correlation tests were performed. The best correlation was found between the frontal and vertical diameter increase in anterior instrumentation (r=0.62; 0.71), whereas the best correlation was found between TV and sagital parameters in posterior instrumentation (r=0.74). It is concluded that anterior instrumentation can increase TV more than posterior instrumentation.