Study Shows Low Nonunion Rate For Arthrodesis

By Brian McCurdy, Associate Editor

A new study on Lapidus arthrodesis presents some encouraging results. In a retrospective study of over 200 patients who underwent the Lapidus arthrodesis procedure, the researchers found only a 5.3 percent nonunion rate. The study, which was recently published in The Journal of Foot And Ankle Surgery (JFAS), assessed the results of a modified procedure, which emphasized joint curettage with subchondral plate preservation and screw fixation. The low nonunion rate is the most significant finding in the study, according to study co-author Lawrence Ford, DPM. “A lot of people believe that removing the subchondral plate is necessary to increase likelihood of union,” says Dr. Ford, a Fellow of the American College of Foot and Ankle Surgeons. "Our study shows that preserving the subchondral plate not only limits the amount of shortening of the first ray, but may facilitate union." Postoperatively, Dr. Ford and his co-authors used a standard nonweightbearing protocol of six to eight weeks and tracked the patients for at least six months. Out of the 227 feet (in 211 patients) treated for forefoot pathology, only 12 feet had nonunion. Dr. Ford notes the JFAS study concurs with a cadaveric study by Ronald Ray, DPM. He says Dr. Ray’s study concluded that fixation across the subchondral plate may increase the fusion site’s stability. How one prepares joint surfaces for fusion “may be a significant factor” in shaping the outcome of the Lapidus arthrodesis, according to the study. The authors note their curettage procedure preserved the subchondral plate. They say this results in increased stability. Even in the 12 cases of nonunion, Dr. Ford and his co-authors note that only two of these feet “lost correction of the first ray.” The study also notes that appropriate screw placement can optimize the dispersion of force through the length of the screws and help facilitate union. Emphasizing Appropriate Patient Education And Patient Selection The authors of the study emphasized the importance of educating patients about nonweightbearing, noting that noncompliance with the nonweightbearing instructions contributed to four of the 12 nonunions. Dr. Ford also points out that they considered smoking a contraindication for Lapidus arthrodesis. He says this may also explain the low rate of nonunion. Despite the findings of the study, Dr. Ford cautions that one must still weigh the risk of nonunion when considering the Lapidus arthrodesis. “It is important to understand that nonunion is inherent to the procedure,” he notes. “Although the rate of 5.3 percent compares favorably to the literature, it is still a real potential complication of the Lapidus.” New Study Sheds Light On Detecting Peroneus Brevis Tendon Tears By Brian McCurdy, Associate Editor Diagnosing peroneus brevis tendon tears can be difficult. In a new retrospective study on the subject, researchers have found that these tears rarely present as isolated injuries. The study, which was recently published in the JFAS, reviewed preoperative MRIs and intraoperative findings for 32 patients who underwent surgery for longstanding peroneus brevis tendon pathology. The authors found an array of coexistent conditions with peroneus brevis tendon tears. These conditions included: • low-lying muscle belly/peroneus quartus in 44 percent of the cases; • anterior talofibular ligament rupture in 50 percent of the cases; • a flattened/hypertrophic peroneus longus tendon in 53 percent of the cases; and • a flat/convex fibular groove in 78 percent of the patients. “(Peroneus brevis tendon tears) are part of a constellation of pathologies that coexist when patients suffer from lateral ankle pain and instability,” says study co-author Alan Catanzariti, DPM, a Fellow of the American College of Foot and Ankle Surgeons. The authors of the study also noted that magnetic resonance imaging (MRI) successfully diagnosed peroneus brevis tendon tears in 26 of the 32 patients. “In conjunction with a careful physical examination, (MRI) plays a valuable role in the preoperative assessment of the peroneal tendons and the entire lateral ankle complex,” the researchers note in the study. However, even with the MRI, the peroneus brevis tendon tears remain difficult to detect according to the study authors, who note that there were four false positives and two false negatives.

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