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Lisfranc deformity: a case study.

Slip-and-fall injuries are one of the most common types of accidental injury. Among the elderly, they also are one of the most damaging types of injury. The aging process itself usually plays a role in slip-and-fall accidents among the elderly, a result of changes in vision, hearing, mobility and dexterity.

The patient described in this case study is a 70-year-old woman who injured her right foot after slipping on a patch of ice. The physician who performed the patient's preoperative examination had treated her previously for an ankle injury, which resulted in the implantation of internal fixation hardware.

During the examination, the physician noted that preliminary radiographs indicated a deformity of the foot suggestive of a tarsometatarsal fracture-dislocation.[1] A computed tomography scan demonstrated and confirmed the physician's impression of the preliminary radiographs. The metatarsal bases of the patient's right foot were subluxed, or incompletely dislocated toward the lateral aspect of the foot, indicating a Lisfranc deformity. (See Figs. 1 and 2.) There also were small, bony densities demonstrated in the joint spaces that could represent small chip fractures. A deformity involving the base of the fourth metatarsal bone was noted, but was unrelated to this injury. The radiographs also revealed a mild subluxation of the first and second cuneiform and evidence of interphalangeal joint space degeneration and cuboidal spurs. (See Figs. 1, 2 and 3.) These degenerative changes no doubt played a role in the extent of the patient's injury, especially the fracture-dislocation.

[Figure 1-3 ILLUSTRATION OMITTED]

Fractures have two primary causes: traumatic or pathological. Traumatic fractures can be caused during twisting or bending of the bone or may be the result of an impact of some kind on the bone. Pathological fractures are due to the demineralization of bone due to osteoporosis and the aging process.[2] In this case, the patient's age, degenerative changes and the trauma suffered during her accident all were factors in her fracture-dislocation and Lisfranc deformity.

A Lisfranc deformity is a tarsometatarsal fracture-dislocation that manifests itself as two types. In both types, the forefoot is displaced dorsally and laterally, with associated multiple fractures and subluxations of the cuneiforms, cuboid and possibly the navicular.[3] Mild subluxation of the metatarsals was apparent in the lateral view of the patient's foot (see Fig. 2), and lateral displacement of the metatarsals can be seen in the anteroposterior view (see Fig. 1). In both, small densities representing chip fractures can be seen.

The distinguishing factor between the two types of Lisfranc deformities is the position of the second metatarsal base in relation to the second (intermediate) cuneiform. The first type of Lisfranc deformity is associated with metatarsal subluxation, usually due to trauma on the lateral side of the foot. In the second type, the first and sometimes the second metatarsal is displaced medially, while the remaining metatarsals are displaced laterally.[3]

In this case study, the metatarsal bases were all subluxed dorsally and displaced laterally. In addition, the lateral surface of the second metatarsal base was aligned to the midpoint of the intermediate cuneiform. (See Fig. 1.) This evidence indicated that the patient's Lisfranc deformity was of the first type rather than the second.

A Lisfranc deformity must be diagnosed quickly and corrected immediately. Failure to do so can give rise to significant long-term foot problems.

A physician may take one of two paths of action for correcting a tarsometatarsal fracture-dislocation -- open or closed reduction accompanied by casting, or internal or external fixation. The goal of either method is to create a "solid union of bone in perfect alignment, to return joints and muscles to normal position, to prevent [further] trauma, and to rehabilitate the patient as early as possible."[2]

Closed reduction involves maneuvering the fractured bones manually, without surgery. Open reduction, on the other hand, is invasive. The physician gains entry via an incision in the affected region, and the bones are maneuvered under direct supervision. The foot then is cast in a solid dressing of plaster of Paris to keep the extremity immobilized.

In external fixation, fragments of a fractured bone are held together through a combination of percutaneous pins and compression devices attached to those pins. These pins are removed once the fracture has healed. In internal fixation, screws, nails, wires and plates are used to correct the fracture, and these devices remain inside the patient's body as long as no contraindications surface.

Internal fixation was the corrective method chosen for the patient described in this case study. Prior to surgery, the physician discussed the risks of the operation as well as the benefits that could improve the patient's quality of life. The patient understood the risks and opted to undergo the surgery.

An anesthetic was administered to the patient, along with intravenous antibiotics. She was placed in the supine position, and her right lower leg was prepped in the usual fashion. An Esmarch bandage was used at the ankle to force blood out of the foot.

The physician made a longitudinal incision over the second metatarsal joint, then another incision was made over the area of the fourth and fifth tarsometatarsal joints. All of the metatarsal dorsal subluxations were reduced back into their normal position (pushed toward the planter surface) in preparation for repair by internal fixation. The first, second and third tarsometatarsal articulations were stripped of articular cartilage and subchondral, and then allograft was packed in these joints. This process is called arthrodesis -- the removal of articular surfaces and the insertion of some sort of fixation that impedes movement at the site.

Five screws were placed in the arthrodesis region into the tarsals and metatarsals, securing them in place. The first screw was placed from the first metatarsal into the medial cuneiform, and the second screw was countersunk from the metatarsal into the medial cuneiform. The third screw was placed from the first metatarsal laterally through the second and third metatarsals, while a fourth was placed from the medial cuneiform through the first and into the second metatarsal. The last screw was placed from the base of the fifth metatarsal into the fourth metatarsal and into the cuboid. Further bone graft was packed around the arthrodesis site. During the operation the position of the hardware was checked with image intensification, and all surgically implanted fixation devices were determined to be in good position. The incisions were closed and there were no intraoperative complications.

Recovering from this type of operation takes approximately 3 to 6 weeks,[4,5] with healing time dependent on the age of the patient, extent of the injury to the surrounding tissues, blood supply to the bone, amount of displacement, bone loss and method of realignment.[2] Healing seems to occur at a faster rate following an open reduction than a closed reduction.

In many ways, tarsometatarsal surgery is like assembling the pieces of a puzzle. Sometimes the pieces fit together perfectly, conforming to the contours of each roughly cut cardboard edge, and sometimes you have to twist and push the pieces into position, trying to make them fit with the pieces that have already been assembled.

In treating a patient with a tarsometatarsal fracture, the radiologic technologist, radiologist and surgeon must work together to determine which pieces of the patient's "puzzle" are damaged and then repair or replace them. It is only through a combination of knowledge, skills and compassion that health care providers can deliver the most appropriate and effective patient care. The highest accolade is due to those who uphold these standards.

References

[1.] Sutton D, Young J. A Textbook of Radiology and Imaging. 5th ed. New York, NY: Churchill-Livingstone; 1993;1:284.

[2.] Atkinson L, Fortunato N. Operating Room Technique. 8th ed. St. Louis, Mo: Mosby-Year Book; 1996:659-671.

[3.] Norman A, Taveras J, Farrucci J. Radiology -- Imaging -- Intervention. Philadelphia, Pa: JB Lippincott Co; 1994;5:3-5.

[4.] Kyle J, Smith JAR, Johnston DH, Duckworth T. Pye's Surgical Handicraft. 22nd ed. Boston, Mass: Butterworth Heinemann Ltd; 1992:173-175.

[5.] Schwartz S, Shires G, Spencer F, Rosier R. Principles of Surgery. 6th ed. New York, NY: McGraw-Hill Inc; 1994:1929-1930.

Bryan Verhelle is a second-year student in the radio logic technology program at William Beaumont Hospital in Royal Oak, Mich.

Cynthia Daniels, B.S., R.T. (R), is editor of this section of the Journal, dedicated to publishing the written works of students in radiologic science educational programs. Ms. Daniels is chairman of the ASRT Committee on Student Membership. She is coordinator of the radiography program at Barnes Jewish Hospital in St. Louis, Mo.

Articles published in the "Student Scope" column are eligible to compete for the Mallinckrodt-Radiologic Technology Writing Award. Writing guidelines may be obtained by contacting Christine Morrison, c/o the American Society of Radio logic Technologists, 15000 Central Ave. SE, Albuquerque, NM 87123-3917
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Author:Verhelle, Bryan; Daniels, Cynthia
Publication:Radiologic Technology
Date:Sep 1, 1997
Words:1461
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