2/14/2024 0 Comments Midfoot fractureIn more severe injuries, bone bruises or fractures are also observed in various other tarsal bones and metatarsal bases. A very common association is bone bruise or fracture of the inferior aspect of the middle cuneiform or second metatarsal base ( Fig. In the setting of injury, any edema in or around the ligament should be considered suspicious for a significant injury. First, small avulsions can be very hard to detect on MRI second, the ligament may be stretched and insufficient without appearing discontinuous. Still, CT serves a complementary role, since small fracture fragments may not be visible on MRI.Īn important concept in interpreting an MRI of suspected Lisfranc ligament injury is that a ligament with a mechanically significant injury may still appear intact on MRI. MRI is the test of choice for evaluation of the ligament itself as well as bone bruises and muscle tears indicative of a more severe injury. However, a significant Lisfranc injury may exist in the absence of fracture. CT is also useful for identifying additional fractures. CT is very useful for confirming a fracture suspected clinically, especially if radiographs are negative. Therefore, fracture of the second metatarsal base or disruption of the Lisfranc ligament creates instability of the entire tarsometatarsal axis, destabilizes the midfoot, and results in collapse of the longitudinal arch.įigure 14-11 Lisfranc injury on CT. There is no intermetatarsal ligament between the first and second metatarsals. 14-9), is the main structure keeping the midfoot congruent-it is the cement of the Roman arch. 14-7 and 14-8) however, the Lisfranc ligament, running obliquely from the medial cuneiform to the second metatarsal base ( Fig. Intercuneiform and intermetarsal ligaments exist in the midfoot ( Figs. This can create a rocker-bottom deformity with reversal of the longitudinal arch curvature ( Fig. In either case, there is usually superior migration of the metatarsal bases and inferior excursion of the tarsal bones. Lisfranc disruption may be seen after acute injury or in the setting of neuropathic disease. The Lisfranc joint is shaped like a Roman arch, which is well known for its stability. The second metatarsal base is inset compared with the other tarsometatarsal joints, and this and the middle cuneiform are shaped like a keystone in the coronal plane ( Fig. The Lisfranc joint is very important in stabilization of the midfoot and longitudinal arch. This effect has been likened to a windlass, which is a rope or chain extending over a drum used to raise and lower sails and anchors on a ship. The plantar fascia, which inserts distal to the metatarsophalangeal (MTP) joints, tightens as the toes are dorsiflexed, which pulls the tarsal bones together and “locks” them into a rigid column. During the push-off phase of gait, this flexibility would be detrimental. When the foot is at rest, there is some mobility between the bones of the midfoot, allowing flexibility. Figure 14-4 The windlass mechanism and function of the plantar fascia.
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