Lesions of the articular cartilage affect millions of people worldwide. There are many causes of these lesions, with traumatic damage and osteochondrosis disease being the most common. Treatment is made difficult by the fact that in adult life, the regenerative capacity of hyaline articular cartilage is limited.
Although hyaline cartilage is an elaborately organized tissue, it has no nerve supply and no blood vessels. About 1% by volume consists of chondrocytes, living cells which are embedded in the cartilage matrix that they themselves have created. This matrix consists of collagen fibers and proteoglycans, with Type II-collagen being the predominant constituent (up to 65% of cartilage dry weight).
Although the human body produces fibrocartilage to replace damaged or absent hyaline articular cartilage, this is soft without hyaline's unique biomechanical properties and has a relatively short life. Defects which extend down to the bone plate do not heal of their own accord and ultimately lead to osteoarthrosis. However, if some healthy residual cartilage remains, Grade III or IV lesions can be successfully treated by implantation of autologous chondrocytes. Defects caused by osteochondrosis also can be treated in this way.
Past attempts to treat defects using autologous periosteal or perichondrial grafts have tended to produce a mixture of hyaline cartilage and fibrocartilage. This mixed regeneration tends towards calcification and will be replaced by bone.
Autologous chondrocyte implantation (ACI), as proposed by Verigen Transplantation Service International (Leverkusen, Germany), uses a highly purified porcine collagen I/III membrane to cover the defect, so rendering the excision of a periosteal graft unnecessary.
This not only avoids the need for a second incision for harvesting the periosteal graft, but also saves the time which would otherwise be needed for its dissection. Patient advantages include consistent quality control of the collagen membrane vs. periosteum, no hypertrophic tissue growth, less pain, a shorter hospital stay and rehabilitation time.
With its autologous chonrocyte implantation technique (MACI), Verigen separates chondrocytes from the matrix in a healthy biopsy sample and cultures them over 3 to 4 weeks to obtain an augmented chondrocyte harvest of 15 million to 20 million differentiated cells. These cells are placed on an MACI membrane, with access to the lesion using mini-arthrotomy techniques.
Clinical trials in leading German, British, and Scandinavian institutes have demonstrated an outstanding viability level for the chondrocytes and their capacity to migrate from the membrane and to form a collagen II matrix.
Effective and extended rehabilitation is essential after the implantation procedure, with a planned program of progressive rehabilitation in force. This includes use of a motor splint as soon as possible so that compression and decompression forces can stimulate the chondrocytes to synthesize the correct matrix molecules.
Although the cartilage defect will have filled with hyaline-type cartilage in a few weeks, Verigen advises that weight-bearing activities such as cycling not be attempted for six months and stress activities like tennis are delayed for a full year. The company says that definitive maturation and hardening of new-formed cartilage will not be complete for 11 to 24 months from transplantation.
Computer-assisted 3-D foot model software
"Up to the present time there has been no model available for surgeons, orthopedists or radiologists to help them foresee the evolution of a diseased or malformed foot taking into account a chosen surgical technique." So said Professor Marie-Christine Ho Ba Tho at the Biomechanical and Biomedical Engineering Laboratory of the CNRS (the French equivalent of the U.S. National Institutes of Health) in Compeigne, France, who has identified deformities of the human foot as being particularly difficult to visualize. Because of 3-D considerations and because the complex combination of bones, muscles, and tendons is hard to adapt to a standardized treatment, surgeons have found difficulty in visualizing the effect of some bone and cartilage malformations (e.g. club-foot) and how best to treat them.
Ho Ba Tho has developed, with financial backing from the French Fondation pour la Recherche Medicale research fund, a software program to help visualize a patient's foot in 3-D. Using medical imaging techniques, mechanical measurements, and CAD-CAM software used in the aeronautical industry, she is developing the program so that it will assist the surgeon to decide on the best surgical technique to choose.
Sulzer's growth factor spinal fusion trials
A new growth factor treatment from Sulzer Medica (Winterthur, Switzerland), Ne-Osteo, is being used by orthopedic surgeons in Europe in a multicenter clinical trial to help spinal fusion in patients with back pain.
Ne-Osteo, a mixture of bovine-derived growth factor together with a collagen carrier matrix, will be used initially with fixation devices, but is intended eventually for use alone. The European five-center trial of around 150 patients will aim to achieve fusion of two or more vertebrae as an alternative to conventional autografting techniques, which are expensive, painful and potentially complex.
CT and X-ray scans will assess fusion and patients will be assessed on pain reduction and ease of movement. Sulzer Spine-Tech (Mountain View, California) recently reported positive initial results of a clinical trial using Healos Bone Graft Substitute in combination with its BAK Interbody Fusion cage.
The company has started full clinical trials at the first of 20 potential sites in the U.S. An IDE application to the FDA is planned, combining Ne-Osteo with the BAK Interbody Fusion Cage.
Other companies developing growth factors for spinal and similar applications include Stryker (Kalamazoo, Michigan), Sofamor Danek (Memphis, Tennessee) and Interpore Cross (Irvine, California).
Sulzer Medica hopes to have Ne-Osteo launched commercially in Europe in mid-2002 and shortly thereafter in the U.S.
Dornier Medical in shock wave therapy trials
Dornier Medical (Germering, Germany) has completed enrollment of clinical trials in Germany, the United States, and Canada for its Epos Ultra orthopedic shock wave therapy for painful heel spurs (plantar fasciitis). The company hopes to file a PMA after analysis of trial results in early April.
HealthTronics (Marietta, Georgia) submitted a similar application to the FDA in February.
In a second project, Dornier Medical plans to utilize the trial data in Germany to obtain reversal of a 1998 decision to withdraw reimbursement for shock wave therapy in orthopedic indications. The federal committee which decides on reimbursements complained about a lack of scientific proof of its effectiveness.
Dornier also has a second set of multicenter studies under way in Germany to establish treatment efficiency and economic benefits in plantar fasciitis, tennis elbow, and shoulder calcifications.
McCue gains FDA approval
The CUBAClinical ultrasound bone density measurement device from McCue (Winchester, England) has been approved by the FDA for sale in the United States.
Priced under $20,000, the CUBAClinical unit is marketed in North America, parts of Europe, the Pacific Rim countries, Africa, and the Middle East by Norland Medical Systems (White Plains, New York).