Stability and Outcomes of Non-displaced Lisfranc Injuries

In this multicenter cohort study, the stability of non-displaced Lisfranc injuries as well as their outcomes will be evaluated.

Injuries to the tarsometatarsal joints ("Lisfranc injuries") that are non-displaced on non-weightbearing radiographs and CT are common injuries. To refer these injuries to the right treatment, evaluating their stability is essential. For this purpose, both weightbearing radiographs and stress fluoroscopy have been proposed. However, there is no consensus concerning both the use and interpretation of weightbearing radiographs and no standardized technique and interpretation of stress fluoroscopy in non-displaced Lisfranc injuries. In the current study, participants will be assigned to non-operative or operative treatment based on Lisfranc joint stability evaluation by weightbearing radiographs. All Patients with negative weightbearing radiographs will be treated conservatively. In addition, their injured feet will be evaluated by manual stress fluoroscopy. Depending on the result of the stress fluoroscopy (positive/negative), the conservatively treated patients will be assigned to 2 cohorts, whose outcomes will be compared. Patients with positive weightbearing radiographs will be treated operatively by minimally invasive stabilization of the midfoot (eg. isolated "homerun screw"). The operatively treated patients will be followed up as an independent cohort.

Participants are evaluated by weightbearing radiographs. Patients with no signs of dislocation on the weightbearing radiographs will undergo stress fluoroscopy. Patients with negative stress fluoroscopy are allocated to Cohort 1, patients with positive stress fluoroscopy are allocated to Cohort 2. The study design is a non-inferiority study, proving to show that the outcomes of Cohort 2 are non-inferior compared to Cohort 1. Patients with positive weightbearing radiographs (interval between medial cuneiform and base of second metatarsal increased by > 2 mm compared to the contralateral side) will be operated with minimally invasive stabilization (eg. isolated "homerun screw") and followed up prospectively as a single cohort (Cohort 3).

Cohort 1 Negative weight bearing radiographs: Interval between medial cuneiform and base of the second metatarsal (C1-M2) are less than 2mm increased compared to the uninjured side. Negative stress fluoroscopy: the midfoot is tested stable

Cohort 2 Negative weight bearing radiographs: Interval between medial cuneiform and base of the second metatarsal (C1-M2) are less than 2mm increased compared to the uninjured side. Positive stress fluoroscopy: manual testing reveals midfoot instability

Patients with positive weightbearing radiographs will be operated on with minimally invasive technique and followed up as an independent cohort.

Patients with positive weightbearing radiographs will be operated by minimally invasive stabilization (eg, isolated homerun screw)

The presence of osteoarthritis of the tarsometatarsal joints is graded based on the Brodén radiographs taken at 1 year, 2 year and 5 year follow-up using the Kellgren & Lawrence classification system.

Yes/no for deep or superficial infection, nerve or tendon injury, deep venous thrombosis, hardware complaints and secondary surgery. Regards the patients that have undergone surgical treatment.

Inclusion Criteria: Acute Lisfranc injuries that are non-displaced (< 2mm) on non-weightbearing radiographs and CT Patients between 18 and 70 years of age Acute presentation at one of our departments, enabling evaluating the stability of the injuries within 4 weeks Exclusion Criteria: Fractures with an intraarticular step of > 2mm on the initial non weight-bearing radiographs and/or CT Delayed presentation (weight-bearing radiographs taken > 4 weeks after injury) Bilateral injuries Concomitant major injuries of the foot, ankle or leg that affect the rehabilitation process Multitraumized patients Previous injury or surgery of the mid foot Charcot foot Noncompliant patients Insufficient Norwegian or English language skills Patients not available for follow-up Inability to conduct the rehabilitation protocol