The interosseous cuneometatarsal ligaments are short, stout bands connecting the medial and lateral surfaces of adjacent cuneiform and metatarsal bones within the Lisfranc joint complex. The most important is the Lisfranc ligament proper (C1-M2, which exists as a separate entry), but the C2-M3 and C3-M4 interosseous ligaments are also clinically significant in determining injury stability. Together these ligaments bind the central tarsometatarsal complex into a rigid Keystone arch.
Bind adjacent cuneiform-metatarsal articulations, resist transverse diastasis of the Lisfranc joint complex, and maintain the transverse arch of the foot at the metatarsal bases.
In complete Lisfranc injuries, the interosseous cuneometatarsal ligaments from C2-M3 and C3-M4 are disrupted in addition to the primary Lisfranc ligament (C1-M2). Identifying all disrupted ligaments on MRI determines the degree of instability and guides the extent of surgical fixation required. Isolated injury to the secondary interosseous ligaments with an intact Lisfranc ligament proper produces a subtle Lisfranc sprain that may be missed on non-stressed radiographs.
Disruption of the primary Lisfranc ligament and the secondary interosseous cuneometatarsal ligaments produces complete Lisfranc instability with diastasis between the medial and middle columns, requiring open reduction and fixation or primary arthrodesis in athletic patients.
Partial tear of the secondary interosseous cuneometatarsal ligaments without complete diastasis produces midfoot pain and swelling that may be missed on routine radiographs, requiring weight-bearing stress views or MRI for diagnosis and managed with protected weight-bearing for 8-12 weeks.
