Stability of Lisfranc injury fixation in Thiel Cadavers: Is routine fixation of the 1st and 3rd tarsometatarsal joint necessary?

BACKGROUND

There is debate as to whether a home run screw (medial cuneiform to 2nd metatarsal base) combined with k-wire fixation of the 4th & 5th tarsometatarsal joints is sufficient to stabilise Lisfranc injuries or if fixation of the 1st and 3rd tarsometatarsal joints is also required. Unlike the 2nd, 4th and 5th tarsometatarsal joints, stabilisation of the 1st and 3rd requires either intra-articular screw or an extra-articular plate which risk causing chondrolysis and/or osteoarthritis. The aims of this cadaveric study were to determine if routine fixation of the 1st and 3rd tarsometatarsal joints is necessary and to determine if a distal to proximal home run screw is adequate.

METHODS

Using 8 Theil-embalmed specimens, measurements of tarsometatarsal joint dorsal displacement at each ray (1st-5th) and 1st-2nd metatarsal gaping were made during simulated weight bearing with sequential ligamentous injury and stabilisation to determine the contribution of anatomical structures and fixation to stability.

RESULTS

At baseline, mean dorsal tarsometatarsal joint displacement of the intact specimens during simulated weight bearing (mm) was: 1st: 0.14, 2nd: 0.1, 3rd:0, 4th: 0, 5th: 0.14. The 1st-2nd intermetatarsal gap was 0mm. After transection of the Lisfranc ligament only, there was 1st-2nd intermetatarsal gaping (mean 4.5mm), but no increased dorsal displacement. After additional transection of all the tarsometatarsal joint ligaments, dorsal displacement increased at all joints (1st: 4.5, 2nd: 5.1, 3rd: 3.6, 4th: 2, 5th: 1.3). Stabilisation with the home run screw and 4th and 5th ray k-wires virtually eliminated all displacement. Further transection of the inter-metatarsal ligaments increased mean dorsal displacement of the 3rd ray to 2.5mm. K-wire fixation of the 3rd ray completely eliminated dorsal displacement.

CONCLUSIONS

The results of this cadaveric study suggest that stabilising the medial cuneiform to the 2nd metatarsal base combined with stabilisation of the 4th and 5th tarsometatarsal joints with K-wires will stabilise the 1st and 3rd tarsometatarsal joints if the inter-metatarsal ligaments are intact. Thus 3rd TMTJ stability should be checked after stabilising the 2nd and 4/5th. Provided the intermetatarsal ligaments (3rd-4th) are intact, the 3rd ray does not need to be routinely stabilised.