Friday February 23, 1996

Augmented plate fixation used to treat ankle fractures

A new technique which uses augmented plate fixation for treating complex ankle fractures in elderly patients was presented Thursday in scientific paper 84.

Between January 1991 and August 1994, 151 fractures were operatively treated at the Hospital for Joint Diseases in New York City. Twenty of the patients, ages 50 to 89 years, had ankle fractures which were comminuted (broken in small fragments) or osteopenic (resulting from a decrease in bone density). The fractures were corrected with plate fixation that included augmented intramedullary wires for increased stabilization.

Two to three wires were inserted and placed across the bone, stabilizing the fracture that first had been reduced through manual manipulation. A plate was positioned on the surface of the bone and screws that hold it in place were interdigitated with the wires. The wires that are exposed were cut, bent over, and impacted into the fibula, providing extra strength.

Postoperatively, patients were placed in a short leg cast for six weeks and allowed partial weightbearing. After cast removal, patients were referred to a physical therapist for gait training, range of motion ankle exercises, and strengthening. The ankles also were radiographed to assess the results of the surgical treatment.

Nineteen of the patients were followed for an average of 15.4 months. All fractures united without loss of reduction. Results were: three excellent; six good; nine fair; and one poor. Eighty-nine percent of the patients had no pain or slight or mild pain.

"Displaced ankle fractures usually are treated by open reduction and internal fixation, however, older patients with osteopenia or comminuted ankle fractures sometimes carry an unacceptably high risk for this treatment," said Kenneth J. Koval, MD, chief of the fracture service, department of orthopaedics, Hospital for Joint Diseases Orthopaedic Institute.

"This is the first study to use a composite of plate and intramedullary wires to stabilize comminuted and osteopenic ankle fractures in the elderly," said Dr. Koval. "This treatment method provides provisional fracture stabilization and enhanced plate and screw fixation which may help to prevent loss of fixation of these difficult fractures."

In addition to this clinical study, a biomechanical evaluation was performed on eight pairs of cadaveric lower extremities which were simulated into mildly osteopenic fractures. Eight fibulas had fixation using the technique of augmentation with intramedullary wires compared to eight which had plate and screws alone.

The fibulas were first tested nondestructively by bending, and then destructively with torsion to determine stability and ultimate strength of the fixation. The resistance to bending of the fibulas augmented with wires was 81 percent greater than the fibulas stabilized with only a plate and screws. In torsional testing, the wire augmented specimens had twice the resistance to motion than the group that had plate and screws alone.

Co-authors of the paper with Dr. Koval from the Hospital for Joint Diseases Orthopaedic Institute are Douglas M. Petraco, MD, and Srino Bharam, MD orthopaedic residents; and Frederick J. Kummer, PhD, associate director, department of bioengineering.

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