Saturday, February 15, 1997
Medial malleolar ankle fractures can be safely and efficiently internally fixated with a single screw, according to a study which evaluated single vs. double screw fixation of medial malleolar fragments in 60 ankle fractures. The preliminary results were presented Thursday in scientific paper 144.
"Single screw fixation reduces the risk of iatrogenic fragment comminution and does not increase the risk of fragment rotation," said Clifford B. Jones, MD, resident in orthopaedic surgery, San Francisco Orthopaedic Residency Program at St. Mary's Medical Center, San Francisco. "The second screw, in most cases, is superfluous."
The single screw fixation had similar results to double screw fixation with overall less operative time-61 minutes vs. 65 minutes, respectively. The implant cost savings is $24 to $40, Dr. Jones said.
From February 1993 to July 1994 at Highland General Hospital, Oakland, Calif., 60 consecutive operative ankle fractures that had medial malleolus fractures at the level of the mortise were randomly placed into one of two groups. Group 1 (30 patients) had single screw fixation (4 millimeter cancellous screw); Group 2 (30 patients), double screw fixation (two, 4 millimeter cancellous screws). The populations were similar in fracture types (SAD I-II, SER I-IV, PAB I-III, PER I-IV); age (average: 39 years); and etiology (twisting, fall, or motor vehicle accident).
Results of the study shows that the single screw maintained the medial malleolar fracture fragment reduction as well as the double screw fixation, Dr. Jones said. The clinical, anatomical, and arthritic results were similar in both groups at average follow-up of 2.5 years (range: 1.3 to 2.8 years). A total of 47 patients were available for follow-up.
According to the study, the average Phillips' score for these patients was 133; Group 1 (single screw fixation) average was 135; Group 2 (double screw fixation) average, 131.
"We have found no difference in using one vs. two screws for medial malleolar fragments in ankle fractures," said Dr. Jones, noting that several advantages exist for using a single one.
First, the single screw avoids over-packing the fragment with additional metal that two screws create when they are too close-to each other or to the fragment edge.
Second, single screws save time and money. Placement of a single screw is quicker than implanting two screws; shorter operative time reduces operative costs. When the $24 to $40 savings on implant cost per ankle is multiplied by the thousands of ankle fractures treated each year, the potential savings to the health care system is enormous, Dr. Jones said.
"Perioperatively, no significant complications occurred; and no infections or neurovascular injuries were noted," Dr. Jones said. One malunion occurred in each group intraoperatively and did not change postoperatively. All patients received identical postoperative treatment based on the fracture type.
"All incisions and open fracture wounds healed without dehiscence or drainage," Dr. Jones said. "No delayed or nonunions occurred."
In this study, most medial malleolar fracture fragments were reduced with less than 2 millimeters of displacement. Two patients had displacement of approximately 2 millimeters, which healed without any further displacement and did not show signs of arthritic changes at follow-up.
Ankle fractures are common injuries that occur in the general population. Since the ankle is a major weightbearing joint, disruption of the normal anatomy redirects the usual forces across the joint, Dr. Jones said, which can generate post-traumatic arthritic changes. "Therefore, the goal of ankle fracture treatment is to restore the anatomical relationships," he said.
Many ankle fractures can be treated nonoperatively, Dr. Jones said. However, in unstable fractures, the best results occur with open reduction and internal fixation to maintain the reduction and begin early weightbearing or range of motion. Most unstable ankle fractures which entail a fibular fracture with a deltoid ligamentous injury, a bimalleolar ankle fracture, or an ankle fracture with a syndesmotic injury are treated with ORIF.
Future studies should evaluate the single vs. double screw fixation of medial malleolar fractures at physiologic loads, Dr. Jones said.
Co-author of the study with Dr. Jones is Peter Slabaugh, MD, associate clinical professor of orthopaedic surgery, University of California, San Francisco, and chief of orthopaedics, Highland General Hospital, Oakland, Calif.
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Last modified 27/January/1997