Tissue fixation device

#The present invention relates to new and improved suture anchor and more specifically to a suture anchor which is capable of expanding in a patient's body to enable the anchor to withstand relatively large pull-out forces.

#Anchors are commonly utilized to retain sutures in a patient's body. The anchors have previously been formed of metal, such as stainless steel or titanium. In addition, anchors have been formed of biodegradable materials. These known anchors have relied upon mechanical interlocks between the body tissue and the anchor to retain the anchor in place against the influence of force transmitted through the suture to the anchor. It has previously been suggested to construct anchors in the manner disclosed in U.S. Pat. Nos. 5,405,359; 5,403,348; 5,203,787; 5,046,513; and 5,041,129. In addition, an anchor formed of body tissue is disclosed in co-pending application Ser. No. 08/626,393 filed Mar. 29, 1996 filed by Peter M. Bonutti and entitled “Suture Anchor”.

#The present invention relates to a new and improved suture anchor which absorbs body liquid. A suture extends from the anchor. The anchor and the suture are inserted into a patient's body. When the anchor is disposed in the patient's body, the anchor expands. The anchor expands by absorbing body liquid and/or by its own natural resilience. As the anchor expands, an improved interlock is obtained between the anchor and the body tissue to enable the anchor to resist relatively large tension forces transmitted through the suture.

#The foregoing and other features of the invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings, wherein:

#FIG. 1 is a schematic illustration depicting the manner in which an anchor is inserted into a patient's body with a suture extending into the anchor;

#FIG. 2 is a schematic illustration depicting the manner in which the anchor of FIG. 1 is pivoted in the patient's body;

#Suture anchors have previously been utilized to retain sutures in either hard or soft tissue in a human patient's body. The suture anchors have previously been formed of metal, biodegradable materials, and other materials. These known suture anchors have been retained in the patient's body by changing the orientation of the anchor relative to the patient's body once it has been inserted into the patient's body. Alternatively, known anchors have been retained in the patient's body by a mechanical interlock formed with the material of the patient's body by barbs or other projections.

#In accordance with one of the features of the present invention, sutures may be retained in a patient's body by anchors which are at least partially formed of material which absorbs body liquid when exposed to the body liquid. The material expands as it absorbs the liquid in the patient's body. As the anchor expands, an improved interlock is formed between the anchor and body tissue of the patient's body. The improved interlock enables relatively large forces to be transmitted through a suture to the anchor.

#In accordance with another of the features of the present invention, sutures may be retained in a patient's body by anchors which are formed of material which expands under the influence of its own natural resilience. As the material expands, cells are expanded from a collapsed condition. As the cells expand, the anchor absorbs body liquid by at least partially filling the cells with body liquid. As the anchor expands, an improved interlock is formed between the anchor and tissue of the patient's body. If desired, the material which forms the cells could also absorb body liquid.