Introduction: Rheumatoid arthritis and osteoarthritis as well as other diseases can cause severely destruction of the finger joints. The treatment is surgical replacement with joint prosthesis manufactured from flexible silicone or other materials. Silicon prostheses (Swanson’s prostheses) are used worldwide already since 1974. However, the material used may not be strong enough on long term and several reports from breakdown of the prostheses have been published. The long-term results have also shown that bony resorption around the implant may occur. The known weaknesses of the current endoprostheses have lead researchers to look for new materials.
Material: In the beginning of 1994 a fibrous cushion made of commercially available biodegradable fibres (Vicryl® and Ethisorb®) was introduced by the group of researchers from Tampere University Hospital in Finland. It was intended to act as the tendon in Vainio arthroplasty and the aim was to find a material that could work as a scaffold for the collagenous proliferation of connective tissue or fibrocartilage. However the resorption time on the material was too short, which led to the premature collapse of the joint space.
Novel scaffolds were developed using a well-known poly-L/D-lactide copolymer with L/D-monomer ratio 96/4 (PLDLA) in collaboration with the Institute of Biomaterials at Tampere University of Technology and Tampere University Hospital. The PLDLA scaffolds are fibrous, porous cylinders enabling the in-growth of fibrous tissue, which then ideally forms a new, functional joint for the patient. Meltspun PLDLA scaffolds retain 50% of their strength at least 13 weeks in vitro. This enables to retain the shape and size of the scaffolds in situ long enough for tissue ingrowth. The scaffold will bioabsorb and be replaced with fibrous tissue in approximately 2–3 years.
Method: Since January 2003 we take part in a prospective randomised international multicenter study, that is supported by the European Commission. The new bioreplaceable devices are implanted in hands (CMC, MCP, PIP und DIP) as well as feet (MTP I–V toe joints) and will be compared to the standard treatments (Swanson Prostheses, Arthrodeses). The study is surveyed by an Ethical Committee.
Results: Up to now we implanted the bioreplaceable scaffolds in several joints of hands with good results. In future we will also use them for metatarso-phalangeal joints in feet. We will present in the meeting our experiences and outcomes so far.
