Manufacture of the prosthesis

The custom implants used by the Inside The Hip team are the result of a close collaboration with Symbios (Yverdon, Switzerland), a historic pioneer and leader in the design and creation of this medical device. Created over 25 years ago by the University Hospital of Marseille (Professor Aubagniac and Professor Argenson), the Custom stem design was later modified in 2014 following studies conducted by our team.

Technical Foundations

A hip prosthesis replaces the failing joint with two components that are firmly attached to the bone but movable relative to each other. The metallic femoral stem is anchored in the femoral canal and extended by a removable ball. The acetabular cup, with a hemispherical surface, is fixed in the pelvis and articulates with the femoral ball. Often, the bone attachment is direct through biological osseointegration, but cement may be required when the bone is fragile (in elderly patients). Dual mobility prostheses have two sliding surfaces thanks to an intermediate core, offering great stability in elderly subjects.

Materials Used in Hip Prosthesis

The specifications for a modern hip prosthesis meet two requirements: durable bone anchorage of implants and low wear over time of the sliding pair. The materials used depend on the type of bone anchorage: titanium coated with hydroxyapatite for direct osseointegration, polished stainless steel sealed with acrylic cement. For the sliding pair, choices depend on the patient’s age: ceramic-on-ceramic sliding in young and athletic patients, metal-on-polyethylene sliding in older patients. Dual mobility prostheses consist of metal-polyethylene-metal sliding with the option of a ceramic head as well. Polyethylene shows more wear over time and is not chosen for young subjects. Fourth-generation ceramic (Biolox Delta ceramic) is manufactured by Ceramtec and has excellent clinical track records, including in young athletes (resistance to impact and wear, almost no fracture risk when implants are well-positioned). Metal-on-metal sliding was used but carries risks of metallosis and increased concentrations of metal ions in plasma; for this reason, they are not used in our team.