Sat., 10/18/08 Foot & Ankle/Pediatrics, Paper #62, 12:00 pm OTA-2008
Displacement of the Sustentacular Fragment in Intra-Articular Calcaneus Fractures
Frank A. Liporace, MD (e-Stryker); Wayne S. Berberian, MD (n); Robert G. Najarian, MD (n);
Sheldon S. Lin, MD (a-Biomimetic, DePuy, A Johnson & Johnson Company; b,e-Tornier);
UMDNJ-New Jersey Medical School, Newark, New Jersey, USA
Introduction: The sustentacular fragment in displaced intra-articular calcaneus fractures has historically been portrayed as a “constant fragment,” tightly bound to the talus by the interosseous ligament. Operative treatment of these fractures typically takes place through a lateral approach, and the remainder of the calcaneus is built back to the sustentaculum, which acts as a foundation. This study will quantify displacement of the sustentacular fragment with respect to the talus, and identify any predictors of this displacement.
Purpose: The sustentacular fragment in displaced intra-articular calcaneus fractures does not maintain its relationship to the talus in a significant number of cases. The purpose of this study is to characterize the frequency, magnitude, and mode of displacement of the sustentacular fragment in these fractures.
Methods: CT scans of 88 patients with 100 displaced intra-articular calcaneus fractures admitted to our Level 1 trauma center over a 5-year period were retrospectively reviewed. Basic demographics, including age, sex, and mechanisms of injury, were recorded. CT scans were graded according to the Sanders classification, and any other displaced fractures of the ankle and hindfoot were noted. Angulation and translation of the sustentacular fragment in relation to the talus was measured on coronal reconstructions in the plane of the subtalar joint. Displaced intra-articular fractures of the middle facet and gapping of the joint surfaces were also documented. Angulation of greater than 10° and coronal translation of greater than 3 mm were considered diagnostic. Results were analyzed using the Pearson χ2 test and Fisher exact test.
Results: Overall, the sustentacular fragment was displaced in 42% of fractures. 25% of calcanei had angulation of the sustentacular fragment that was greater than 10°, 24% had translation greater than 3 mm, 20% had gapping of the middle facet, and 21% had a displaced intra-articular fracture of the calcaneal side of the middle facet. Fractures involving greater than 50% of the posterior facet (consistent with B and C fracture lines) demonstrated a significant increase in relative risk for angulation, translation, gapping, and fracture of the sustentacular fragment. In addition, 3- and 4-part fractures showed a significant association with overall displacement of the sustentaculum.
Conclusion: Previous studies have emphasized displacement of posterior facet fragments in the evaluation of intra-articular calcaneus fractures. Surgical repair is usually performed through a lateral incision, and hinges upon the reduction of articular and tuberosity fragments to a purportedly “constant” sustentacular fragment. To our knowledge, this study is the first to quantify typical displacement of the sustentacular fragment in a detailed manner. Further study is necessary to evaluate possible changes in overall reduction quality and patient outcome resulting from sustentacular displacement and middle facet incongruity.
Significance: This study quantifies sustentacular displacement occurring with calcaneus fractures. This displacement, previously undescribed, may alter reduction quality and patient outcome. A combined medial and lateral approach may be indicated for the treatment of certain calcaneal fracture patterns with sustentacular displacement .
If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.
• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.