Ryan Fitzgerald, DPM PRESENT RI Associate Editor Hess Orthopedics & Sports Medicine, Harrisonburg, Virginia

We received many great responses regarding the management of this complex patient presented in last week's issue of RI. You can view these responses by following the eTalk thread on this topic. If you missed the first part of this case study, you can follow this link to read it.

Diagnosis: Neglected Lis Franc’s Injury with Hardcastle B2 type fracture dislocation

Treatment Plan: As many of you referenced in your eTalk posts, this patient suffers from a neglected lis franc’s injury which now presents with persistent medial midfoot arthrosis and pain. The patient was given the various surgical and conservative options, however she elected to undergo operative repair of this condition.

As previously presented, radiographic analysis demonstrated a partial incongruity with lateral translocation of the second metatarsal yielding a Hardcastle B2 type fracture dislocation (Fig.1).  Upon dissection through the subcutaneous tissue down to the level of the lis franc’s joint, the 2nd metatarsal was noted to be laterally translocated and obliquely oriented.  Additionally, it appeared as though a portion of the base of the second metatarsal had remained recessed in the tarsometatarsal mortise, and had been sheared off at the time of the injury. (Fig. 2)  This remaining fragment of the base of the 2nd metatarsal was noted to be partially fused to the middle cuneiform in the mortise, and the laterally translocated portion of the second metatarsal was noted to be fixed in its current position lateral to the proximal base fragment (Fig. 3).

Figure 1:  The arrow indicates diastasis of the 1st-2nd metatarsal articulation. There is a small fragment of bone that is visible and is known as the “fleck sign” consistent with lis franc fracture.

Figure 2:  The second metatarsal has sheared off its base and is now laterally translocated and obliquely oriented.

Figure 3:  A sagittal saw was utilized to free up the base of the 2nd metatarsal, visible here, to allow it to be rotated back into position.

Following extensive soft tissue dissection to remove significant scar tissue formation, a capsulotomy of the 2nd tarsometatarsal joint was performed to allow reduction of the deformity. As previously indicated, the 2nd metatarsal was fixed in its lateral position, and a sagittal saw was utilized to “freshen” the proximal edge and to allow for medial translocation and reduction.  Once freed, the 2nd metatarsal was medially rotated back into a reduced position and 4-0 cannulated percutaneous fixation was placed from medial to lateral (Fig. 4). At this point in the procedure, the 3rd tarsometatarsal joint was evaluated for possible arthrodesis, however it was found to be relatively free of arthritic changes.  Clinically it appeared as though the laterally translocated position of the 2nd metatarsal fixed the 3rd in a slightly deviated though stable position, therefore limiting the development of arthritis at this location.  Evaluation under fluoroscopy demonstrated stability of tarsometatarsal joints 3-5, and the decision was made not to fuse any further joints. The repair was reinforced with a dorsally based 1/3 tubular plate and Trel-X™ (Integra Life Sciences, Plainsboro NJ) osteoinductive, demineralized bone matrix (DBM), which was placed at the arthrodesis sites to further promote bone healing (Fig. 5).  There was some difficulty placing the dorsal plate due to the irregular shape of the 2nd metatarsal following the oblique diaphyseal fracture.  Although the patient did heal this fracture, the architecture of the bone was altered such that the shaft of the 2rd metatarsal was triangular (with the base plantar and the point dorsally), which left relatively little surface area for securing screw placement for the 1/3rd tubular plate, even with curving the plate in the transverse plane.

Figure 4:  In this image, the 2nd metatarsal is being reduced prior to placement of percutaneous fixation.

Figure 5:  Here the dorsal 1/3rd tubular plate is visible. Medial to the plate, one can see the DBM packed into the base of the 2nd TMT and in between the 1st and 2nd metatarsals.

Postoperatively the patient was placed into a Jones compression dressing which was replaced with a short leg, non-weight bearing cast at the 1st post operative visit. Non-weight bearing was to be maintained for 8 weeks, and upon radiographic signs of arthrodesis (Figure 6a & 6b), the patient was transitioned into a removable cam-walker (RCW) for another 4 weeks of protected weight bearing.  Physical therapy was initiated at 12 weeks.

Figure 6a

Figure 6b:  Post-operative radiographs demonstrate fixation intact with excellent bone-to-bone contact at the arthrodesis sites.

Discussion: Lis francs injuries are one of the most commonly missed diagnoses in lower extremity trauma—some studies estimate that greater than 20% are overlooked. Commonly, these injuries present following crush Injury, fall from height and MVA. Any mechanism of action that produces forced dorsiflexion of the on a plantarflexed foot can lead to lis francs injury. To classify these injuries, a system was developed by Hardcastle and modified by Myerson:

(Myerson M: Lis Franc Fracture Dislocation, Orthopedic Clinics of North America, Vol. 20. 4:655-663, October 1989)

When considering the management of lis franc’s fracture/dislocations, the literature demonstrates that conservative treatment often yields poor results due to tarsal instability.(1) Philbin et. al. demonstrated that post-traumatic arthritis was commonly found in those missed or neglected lis francs injuries, and in those injuries which were treated conservatively but remained unstable.(2) Indicates for operative treatment include gross instability at the tarsometatarsal joints, >2mm of displacement between the 1st and 2nd metatarsals, and >15° talometatarsal angulations.  When considering operative repair of lis franc’s fracture/dislocations, there are numerous techniques available, including percutaneous pin fixation, ORIF, and external fixation.(3)

Sources:
1.Mehara AK. Bhan S. Isolated fracture-dislocations of the first tarsometatarsal joint. Journal of Trauma. 33(5):683-6, 1992 Nov
2. Philbin T, Rosenberg G, Sferra JJ. Complications of missed or untreated Lisfranc injuries. Foot Ankle Clin. 2003 Mar;8(1):61-71.
3.Teng AL, Pinzur MS, Lomasney L, Mahoney L, Havey R. Functional outcome following anatomic restoration of tarsal-metatarsal fracture dislocation Foot Ankle Int. 2002 Oct;23(10):922-6.

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