1Active Orthopaedics and Sports Medicine, P.A., Westwood, NJ, USA
BACKGROUND: The current treatment of displaced ligamentous injuries of the tarsometatarsal (TMT) joints is open reduction and rigid fixation using transarticular screws. This technique causes further articular surface damage that theoretically may increase the risk of arthritis. Should the screws break, hardware removal is difficult. An alternative method that avoids these potential complications is rigid fixation using dorsal plates.
METHODS: The displacement between the first metatarsal and medial cuneiform, the second metatarsal and intermediate cuneiform, the first and second metatarsal bases, and the medial cuneiform and second metatarsal base were measured in 10 matched pairs of fresh-frozen cadaver lower extremities in the unloaded and loaded condition. After sectioning the Lisfranc and TMT joint ligaments, measurements were repeated in the loaded condition. The first and second TMT joints of the right feet were fixed with transarticular 3.5-mm cortical screws while those of the left feet with were fixed with dorsal 2.7-mm 1/4 tubular plates. Measurements were then repeated in the unloaded and loaded condition.
RESULTS: After ligament sectioning, significantly increased first and second TMT joint subluxation with loading was seen. No significant difference was noted with direct comparison between plates and screws with respect to ability to realign the first and second TMT joints and to maintain TMT joint alignment during loading. The amount of articular surface destruction caused by one 3.5-mm screw was 2.0 +/- 0.7% for the medial cuneiform, 2.6 +/- 0.5% for the first metatarsal, 3.6 +/- 1.2% for the intermediate cuneiform, and 3.6 +/- 1.0% for the second metatarsal.
CONCLUSIONS: The model reliably produced displacement of the first and second TMT joints consistent with a ligamentous Lisfranc injury. Transarticular screws and dorsal plates showed similar ability to reduce the first and second TMT joints after TMT and Lisfranc ligament transection and to resist TMT joint displacement with weightbearing load.
CLINICAL RELEVANCE: Dorsal plating may be an alternative to transarticular screws in the treatment of displaced Lisfranc injuries.