Monolithic orthopedic implant with an articular finished surface

#This disclosure relates to orthopedic implants and in particular to orthopedic implants for repair of focal articular cartilage and osteochondral defects.

#As the population of an active society ages, medical advancements are developed to improve the health of individuals. One of the most active and successful medical treatments is joint reconstruction, also known as arthroplasty, to resolve activity limiting pain caused by arthritis. Current technology supports various forms of arthroplasty, including hemi-arthroplasty, partial joint arthroplasty and total joint arthroplasty. These successful procedures reconstruct a new continuous, low friction articular surface for pain free function of the skeletal joint. A remaining challenge in arthroplasty deals with resolving activity limiting pain in patients with smaller focal cartilage lesions. These lesions represent earlier stages of arthritis and if left untreated potentially progress to later stages of arthritis requiring a more invasive procedure such as partial or total joint replacement. The current challenge in treating arthritis lies in developing a more versatile implant for focal, regional or global resurfacing that successfully interacts with mating articular cartilage, surrounding articular cartilage and the underlying bone bed.

#Diarthrodial joints in the human skeleton provide the nearly frictionless pain free movement supporting locomotion, spatial positioning relative to the environment and active manipulation of the surroundings. These skeletal joints have a strong fibrous capsule enclosing bone ends encapsulated by smooth continuous cartilage surfaces to accomplish this function. This biologic configuration represents the majority of skeletal joints in the human body.

#FIG. 1A shows an implant that can be used for hemi-arthroplasty joint repair in accordance with the prior art;

#FIG. 1B shows an implant for fusing spinal vertebrae in accordance with the prior art;

#FIG. 1C shows an implant for repairing bone defects in accordance with the prior art;

#In the following description, numerous specific details are set forth to clearly describe various specific embodiments disclosed herein. One skilled in the art, however, will understand that the presently claimed invention may be practiced without all of the specific details discussed below. In other instances, well known features have not been described so as not to obscure the invention.

#Referring now to FIG. 2A, a cross section of a monolithic orthopedic implant 50 is shown which is adapted for articulating with articular cartilage in accordance with the present disclosure. In one embodiment the monolithic orthopedic implant may have a porous region 52, integrally joined to a substantially dense region 54. In order to promote skeletal fixation by bone ingrowth, the porous region 52 has a form of interconnected porosity adapted to be similar to cancellous or trabecular bone. The surface 60 of the substantially dense region 54 preferably has a finish adapted for articulation of the surface 60 against native articular cartilage on an opposing joint. The substantially dense region 54 may have a thickness that is adapted to the thickness of the native articular cartilage at the implantation site of the monolithic orthopedic implant.

#In another embodiment a transition region 58 may be between a porous region 56, which as shown in FIG. 2A may be a portion of the porous region 52, and the substantially dense region 54. The porous region 56 may be adapted to have a form of interconnected porosity similar to cancellous bone. The transition region 58 may be adapted to have a form of interconnected porosity similar to subchondral bone. Thus, the monolithic orthopedic implant 50 has a porous region 56 adapted for ingrowth of cancellous bone to ensure that the monolithic orthopedic implant is securely implanted, a transition region 58 adapted to have a form of porosity similar to subchondral bone to facilitate fluid transfer similar to fluid transfer through subchondral bone, a substantially dense region 54 for bearing loads imposed by an opposing joint end, and a surface 60 on the substantially dense region 54 with a finish adapted for articulation against native articular cartilage. The thicknesses of the transition region 58 and the substantially dense region 54 may be adapted to be similar to the thicknesses of the subchondral bone and the native articular cartilage, respectively, at the implantation site for the monolithic orthopedic implant.