Partial joint resurfacing implant, instrumentation and method

Abstract

A partial resurfacing implant for use in repairing an articular cartilage defect site that includes a top articulating portion having a top surface that is configured with at least one radius of curvature to approximate the surface contour of the articular cartilage surrounding the defect site. The implant also includes a supporting plate that has a top surface and a bottom surface. The top surface is attached to the top articulating portion by a locking mechanism. The bottom surface of the supporting plate is constructed to facilitate the insertion of the implant into the defect site. Extending from the bottom surface of the supporting plate is at least one implant fixation portion. The at least one implant fixation portion is integrally connected to and is oriented about normal relative to the bottom surface. A method of repairing an articular cartilage defect with the partial joint resurfacing implant is also disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a national stage filing under section 371 of International Application No. PCT / US2009 / 034826 filed on Feb. 23, 2009 and published in English as WO 2009 / 108591 on Sep. 3, 2009 and claims priority to U.S. Provisional Application No. 61 / 032,141 filed Feb. 28, 2008, the entire disclosure of these application being hereby incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates generally to surgical devices for use in partial resurfacing of damaged or diseased articular cartilage of the joints and to surgical methods using such devices.BACKGROUND OF THE INVENTION[0003]Articular cartilage, or hyaline type cartilage, is a unique tissue providing a smooth, lubricious, hydrophilic, load bearing covering on the ends of bones in diarthroidal joints, in particular the knee, hip, shoulder, to name a few. This tissue is susceptible to damage or deterioration caused by excessive loading resulting in inflamma...

AI Technical Summary

Benefits of technology

[0014]Advancement of the state of surgical repair of damaged or diseased articular cartilage of joints is desirable. The present invention satisfies the need for improvements to implants and corresponding surgical instruments used to insert such implants in patients who have either diseased or damaged articular cartilage by providing a partial resurfacing implant and instrument system that allows the operating surgeon to accurately insert, with accuracy, an implant that maximizes defect coverage while minimizing host bone and cartilage removal.

[0017]The present invention provides in yet another aspect, a surgical method for repairing an articular cartilage defect site. The method generally includes the step of surgically creating an opening in the articular cartilage defect site. The method may include the step of using a partial resurfacing implant in the defect site. The implant includes a top articulating portion and supporting plate. The supporting plate generally includes a top surface and a bottom surface. The top surface of the supporting plate is attached in some manner to the top articulating portion with the bottom surface of the supporting plate being constructed to assist in the insertion of the implant into the articular cartilage defect site. The method may also include the step of implanting the partial resurfacing implant into the defect site opening. Usually, when upon inserting the implant into the defect site, the top articulating portion and adjacent articular cartilage will be positioned tangential to each other which allows for unrestricted motion over the defect site.

Problems solved by technology

This tissue is susceptible to damage or deterioration caused by excessive loading resulting in inflammation, pain, swelling, and joint dysfunction.

This tissue is susceptible to damage or deterioration caused by excessive loading resulting in inflammation, pain, swelling, and joint dysfunction.

Unfortunately the biomechanical properties of this tissue is not equivalent to the original hyaline cartilage, and over time the repair tissue is prone to wear, many times resulting in osteoarthritis.

This procedure is technically difficult as the cored bone / cartilage plugs must be accurately placed to create the new contiguous articulating surface.

Leaving the surface of the plugs too high or low can significantly compromise the surgical outcome.

While clinical outcomes are reported to be similar to the above described techniques this procedure is extremely expensive, requires two surgeries (one of which is a challenging open procedure), and similar long rehabilitation schedule.

Unfortunately they have not shown clinical outcomes advantageous to the above described techniques.

These prosthetic devices require an invasive, technically demanding implantation procedure and a long, involved, and painful rehabilitation period.

Further, these devices are often larger than the defective tissue that needs to be replaced, so healthy bone and cartilage are sacrificed to accommodate the implants.

Albeit that modern UKR and TKR devices are much improved from early hinged knee prostheses, there is still a loss of joint kinematics as this normal tissue is removed.

Additionally, the lifetime of TKRs is limited by a variety of implant and patient-related factors resulting in many patients outliving their primary prosthetic device, thus requiring a more difficult revision TKR surgery.

This device has operative advantages over traditional knee prostheses; however, the opposing articular cartilage is prone to damage due to the large differences in material properties and is further exacerbated by any contour mismatching.

These metal implants have exhibited adverse effects on the cartilage against which they articulate causing erosion of the facing cartilage in several clinical studies.

Thus, merely matching the anatomical shape of the cartilage that is resurfaced is not enough to prevent damage of the facing cartilage by a metallic counterface.

These implants also caused erosion of the facing cartilage in vivo likely due to a mismatch in surface chemistry properties, (i.e. UHMWPE is hydrophobic and cartilage is hydrophilic).

Thus, lower modulus implants alone are not enough to prevent damage of the facing cartilage.

Images