TECHNICAL FIELD

The present disclosure relates generally to a device for use with orthopedic surgical fixation device. The present disclosure also relates to a method of measuring a translation distance between a first bone member and a center point of a first support member.

BACKGROUND

Field of the Invention

The inventive concepts disclosed and claimed herein relate generally to a device for use with orthopedic surgical fixation devices, and more particularly, to an alignment gauge for use with an external fixation system comprising one or more support members (rings, plates, etc.) connected to one or more bone members wherein a plurality of struts of adjustable length support and/or connect the one or more support members. The alignment gauge indicating to a user, such as a surgeon, the degree of translational offset between one bone member and a center point of at least one of the support members in at least one of an anterior-posterior or medial-lateral plane.

General Background of the Invention

It is often necessary to realign, reposition and/or securely hold two elements relative to one another. For example, in the practice of medicine, bone members (e.g., bone fragments or segments of a broken bone) and the like must sometimes be aligned or realigned and repositioned to restore boney continuity and skeletal function. After realignment and repositioning, skeletal stabilization with a cast, plate and screws, intramedullary devices, or external skeletal fixators can occur.

Certain boney skeletal injuries or conditions are sometimes treated with an external frame that is attached to the boney skeleton with threaded and/or smooth pins and/or threaded and/or smooth and/or beaded wires. Such constructs are commonly referred to as orthopedic external fixators or external skeletal fixators. External fixators may be utilized to treat acute fractures of the skeleton, soft tissue injuries, delayed union of the skeleton when bones are slow to heal, nonunion of the skeleton when bones have not healed, malunion whereby broken or fractured bones have healed in a malposition, congenital deformities whereby bones develop a malposition, and bone lengthening, widening, or twisting.

External fixator frames vary considerably in design and capabilities, and may include multiple or single bars or rods, and a plurality of clamps for adjustably securing the bars to pins or wires which are, in turn, joined to the boney skeleton. The pins or wires may extend completely through the boney skeleton extending out each side of the limb or may extend through the boney skeleton and out one side of the limb. Pins that extend completely through the boney skeleton and out both sides of the limb are commonly referred to as “transfixation pins.” Pins that extend through the boney skeleton and out only one side of the limb are commonly referred to as “half pins.” Such external fixator frames may be circumferential for encircling a patient's body member (e.g., a patient's tibia), or may be semi-circumferential or even unilateral and thereby extending solely along one side of a patient's body member. Materials for the components comprising the frames also vary, including metals, alloys, plastics, composites, and ceramics.

A circumferential external fixator system, for example, but not by way of limitation, was disclosed by G. A. Ilizarov during the early 1950s. The Ilizarov system included at least two rings or “halos” that encircle a patient's body member (e.g., a patient's leg), connecting rods extending between the two rings, transfixion pins that extend through the patient's bone structure, and connectors for connecting the transfixion pins to the rings. Use of the Ilizarov system to deal with angulation, translation, and rotation is disclosed in “Basic Ilizarov Techniques,” Techniques in Orthopaedics®, Vol. 5, No. 4, December 1990, pages 55-59, for example, the entire contents of which are hereby incorporated by reference in their entirety.

A circumferential external fixator system was disclosed by Austin et al. in U.S. Pat. No. 6,129,727 (the entire contents of which are hereby incorporated by reference in their entirety) as providing an update to the Ilizarov system. In particular, Austin et al. disclosed a spatial frame fixation apparatus that utilized a plurality of support struts of equal length to support a pair of frame members such as circular rings affixed to respective bone parts with pins. More particularly, Austin et al. disclosed a dynamic external fixation system whereby the elongated support struts had a position adjusting member that changed the distance between an end of a strut and the adjacent ring or like support member. Through such adjustment, the bone parts were incrementally moved into proper alignment according to a “prescription” or set of instructions that could be implemented by a medical technician and/or the patient.

International Publication Number WO 03/086212 (the entire contents of which are hereby incorporated by reference in their entirety) disclosed another external fixator system and methods of using same for aligning fragments of a fractured bone or, alternatively, for positioning bones. The system disclosed in the '212 publication includes the use of a computer in aiding the positioning of the external fixator system with respect to the bones as well as for calculating the “prescription” for incrementally aligning the bones. Through operations on a computer model, desired placement, movement, and final alignment of the bones is determined. The computer model requires certain inputs relating to the placement and orientation of the bones to one another, placement of the rings of the external fixation device, the lengths of the struts extending between these rings, and the position of at least one of the bones with respect to at least one of the circular rings. The computer model takes these inputs and, by using certain mathematical algorithms, provides the “prescription” for adjusting the length of each individual strut over time to thereby incrementally move the bone fragments into a desired alignment with respect to one another.

Despite the algorithmic precision claimed in the '212 publication, it is well known drawback of the current external fixation systems utilizing adjustable struts and computer alignment that the surgeon is required to approximate some of the numerical inputs required to complete the computer aided alignment. For example, but not by way of limitation, the surgeon is required to approximate the amount of translation between the center point of at least one of a proximal or distal circular fixation ring and its corresponding bone member. The amount of translation is determined in an anterior-posterior plane as well as in a medial-lateral plane. To date, surgeons have approximated these values by laying measuring tools on radiographs and/or drawing intersecting rays on the radiograph and thereafter calculating the degree of translation between the bone members. Such inexact estimates as to the degree of translation oftentimes lead to inaccurate computer aided alignment “prescriptions” Thereby extending the time period in which the external fixation system is attached to the patient.

SUMMARY

The presently claimed and disclosed inventive concept(s) provides an external fixation alignment gauge that is used with support members (e.g., rings or plates) that are held in spaced apart relationship with a plurality of adjustable length struts. Support members of this type are used, for example, in Ilizarov procedures wherein bone pins supported by the support members extend to the bone tissue. The alignment gauge has a body member having a first end, a second end, a front face, a back face, a top face, and a bottom face. At least the front face has a plurality of markings serving as indicia of distance.

In one embodiment, the alignment gauge is used with an external fixator system having at least a first and second support member each connected to a first and second bone member, respectively. This external fixator system also includes a plurality of struts with each strut having one end pivotally connected to the first support member, another end pivotally connected to the second support member, and each strut having an adjustable length. This external fixator system may, in some embodiments, further include an elongate member having a first portion that is alignable with the first bone member (for example, but by way of limitation, a longitudinal axis extending through the center of the first bone member) and a second portion alignable with the plurality of markings on the front face of the alignment gauge. In operation, when the second portion of the elongate member is aligned with the plurality of markings on the front face of the alignment gauge, the operator or surgeon can determine the amount of translation (in mm) between the first bone member and a longitudinal axis running through the center of the first support member by measuring the amount of translation in an anterior-posterior plane, medial-lateral plane, for example.

