Methods for bone fixation using an intramedullary fixation implant

#This invention relates to the field of implant devices for bone fixation, and more particularly, to an intramedullary fixation implant used for the fixation of bones and the correction of deformities in the foot or the hand, such as a hammertoe deformity.

#Digital deformities are among the most common forefoot pathologies encountered by podiatrists and orthopedic surgeons. Digital deformities may occur in the form of hammertoes, claw toes, mallet toes, bone spurs, overlapping and underlapping toes, mallet fingers, jersey fingers, and coach's fingers, among others. The deformities typically affect the interphalangeal joints of the hand or the foot, metatarsophalangeal joints of the foot, or metacarpophalangeal joint of the hand. Digital deformities in the fingers or toes result from imbalance of the tendons, causing them to stretch or tighten abnormally. These deformities may be either congenial or acquired. For example, the deformities may be cause by neuromuscular and arthritic disorders, systemic diseases, flat or high-arched feet, or traumatic injuries to the joints. Toe deformities can also be aggravated by poorly fitting footwear.

#Hammertoe, for example, results in a bend in the middle joint of the toe into a claw-like deformity. While at first the patient may be able to move and straighten the toe, overtime the hammertoe may become fixed. In this contracted position, the inside of the shoe rubs against the contracted joints, causing corns to form on the top of the toe and calluses to form on the sole of the foot. In certain patients these corns and calluses may open or ulcerate and form wounds. This causes pain and discomfort in walking or wearing shoes. FIG. 1A depicts a human foot 100 afflicted with hammertoe deformity. Distal phalanx 101, middle phalanx 103, proximal phalanx 105, and metatarsal 107 bones are depicted in foot 100. The distal interphalangeal joint 104 is formed between the distal 101 and middle 103 phalanges, proximal interphalangeal joint 106 is formed between the middle 103 and proximal 105 phalanges, and the metatarsophalangeal joint 108 is formed between the proximal phalanx 105 and the metatarsal 107. The hammertoe deformity in the foot is apparent in the proximal interphalangeal joint 106.

#A further understanding of the invention can be obtained by reference to a preferred embodiment set forth in the illustrations of the accompanying drawings. Although the illustrated embodiment is merely exemplary of systems, methods, and apparati for carrying out the invention, both the organization and method of operation of the invention, in general, together with further objectives and advantages thereof, may be more easily understood by reference to the drawings and the following description. The drawings are not intended to limit the scope of this invention, which is set forth with particularity in the claims as appended hereto or as subsequently amended, but merely to clarify and exemplify the invention.

#FIG. 1A depicts a human foot afflicted with hammertoe deformity;

#FIG. 1B depicts a human hand afflicted with mallet finger deformity.

#The invention may be understood more readily by reference to the following detailed description of a preferred embodiment of the invention. However, techniques, systems, and operating structures in accordance with the invention may be embodied in a wide variety of forms and modes, some of which may be quite different from those in the disclosed embodiment. Consequently, the specific structural and functional details disclosed herein are merely representative, yet in that regard, they are deemed to afford the best embodiment for purposes of disclosure and to provide a basis for the claims herein, which define the scope of the invention. It must be noted that, as used in the specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly indicates otherwise.

#The intramedullary fixation implant of present invention is described with reference to the treatment of a hammertoe deformity illustrated in FIG. 1A. However, it should be appreciated that the present invention may be used to treat any other digital deformities, including, but not limited to claw toes, mallet toes, bone spurs, overlapping and underlapping toes, mallet fingers, jersey fingers, coach's fingers, and the like. As such, the present invention may be utilized for the fixation of the following bones in the foot shown in FIG. 1A: distal phalanx 101 to the middle phalanx 103 in the distal interphalangeal joint 104, middle phalanx 103 to the proximal phalanx 105 in the proximal interphalangeal joint 106, or the proximal phalanx 105 to the metatarsal 107 in the metatarsophalangeal joint 108. Similarly, the present invention may be utilized for the fixation of the following bones in the hand shown in FIG. 1B: distal phalanx 111 to the middle phalanx 113 in the distal interphalangeal joint 114, middle phalanx 113 to the proximal phalanx 115 in the proximal interphalangeal joint 116, or proximal phalanx 115 to the metacarpal 117 in the metacarpophalangeal joint 118.

#Referring now to FIG. 2, there is shown an intramedullary fixation implant 200 that may be used in the practice of the present invention. As shown in FIG. 2, intramedullary fixation implant 200 may be used to join the middle phalanx 103 to the proximal phalanx 105 in the proximal interphalangeal joint 106 of foot 100. Intramedullary fixation implant 200 is used to translate compression between the middle phalanx 103 and the proximal phalanx 105 as will be further apparent below. Intramedullary fixation implant 200 may be made of PEEK (polyetheretherketone) material. The intramedullary fixation implant 200 is preferably made of radiolucent material, allowing for clear visualization of the fusion site. In other embodiments, intramedullary fixation implant 200 may be made of other materials known in the art, including other PAEK (polyaryletherketone) plastics, SST, titanium, NiTi, Cobalt chrome, polylactic acid, or other similar types of materials. Also, intramedullary fixation implant 200 may be coated with an osteoconductive material, such as, for example, plasma spray or other similar types of porous materials, that are capable of supporting or encouraging bone ingrowth into the material.