CLS™ Stem - Design Rationale and Product Information
Product Information
Lorenzo Spotorno, MD, introduced the CLS hip in 1983 with the goals of avoiding bone cement, conserving bone, eliminating thigh pain and avoiding proximal stress shielding. The tri-tapered design and proximal fins allow the CLS stem to achieve primary proximal fixation. Once this primary fixation is achieved, secondary fixation can then occur, which is facilitated by the grit-blasted titanium alloy. One of the main issues that exist with long-term implant survivorship is the proximal stress-shielding or bone resorption that occurs when implants are too stiff or achieve most or all of their fixation distally. The design of the CLS stem can help to minimize the long-term problems that are associated with stiff implant design and distal fixation.
The CLS Hip is a straight stem design that is available in 13 sizes and two different neck angles, 135º and 145º, to accommodate a wide variety of patient anatomies.
Grit-Blasted Titanium Composition
The CLS prosthesis is manufactured from a titanium alloy (Ti6Al7Nb) that has a proven grit-blasted surface finish (4-6µm) with over seventeen years of proven clinical experience.
Proximal Geometry
The proximal geometry of the CLS stem features a collarless, tri-tapered design with a rectangular cross-section. The rectangular cross-section provides rotational stability while the proximal lateral-to-medial taper provides an additional medial locking effect for added primary implant stability. Proximal fins taper both proximal to distal and lateral to medial and are designed to optimize proximal primary fixation in cancellous bone. In addition, the blunt fins of the CLS stem are designed to help prevent subsidence and avoid proximal femur fractures. The CLS stem features a Zimmer 12/14 taper that is compatible with ceramic, Metasul®, and CoCr heads.
Distal Geometry
The distal geometry of the CLS stem tapers 2º in the lateral-medial view and 6º in the anterior-posterior view. The tapered distal design acts mainly to centralize the implant within the femoral canal. The high degree of distal taper results in an extremely low incidence of thigh pain.
Surgical Technique
The surgical technique for the CLS hip prosthesis is a simple broach-only system that is surgeon-friendly and bone conserving, resulting in minimal disturbance to the endosteal blood supply.
