CT-based radiostereometric analysis for assessing midfoot kinematics: precision compared with marker-based radiostereometry.

BACKGROUND AND PURPOSE: 3-dimensional midfoot motion is hard to evaluate in clinical practice. We present a new computed tomography (CT)-based radiostereometric analysis (CT-RSA) technique to examine in vivo midfoot kinematics during single-leg stance and compare it with marker-based radiostereometry (RSA). PATIENTS AND METHODS: 8 patients were examined with bilateral non- and full-weight-bearing CT images of the midfoot. 1st tarsometatarsal motion was analyzed using a surface-registration technique (CT-RSA). As all patients had unilateral tantalum markers in the 1st cuneiform (C1) and 1st metatarsal (M1), comparison of precision with markerbased RSA was performed. CT-RSA precision was evaluated with surface registration of both C1-M1 bone and C1-M1 tantalum markers, while RSA precision was determined with C1-M1 markers only. Additionally, to remove motion bias, we evaluated intrasegmental CT-RSA precision by comparing proximal with distal part of M1. RESULTS: Under physical load, the primary movement for the 1st tarsometatarsal joint was M1 dorsiflexion (mean 1.4°), adduction (mean 1.4°), and dorsal translation (mean 1.1 mm). CT-RSA precision, using surface bone or markers, was in the range of 0.3-0.7 mm for translation and 0.6-1.6° for rotation. In comparison, RSA precision was in the range of 0.4-0.9 mm for translation and 1.0-1.7° for rotation. Finally, intrasegmental CT-RSA precision was in the range of 0.1-0.2 mm for translation and 0.4-0.5° for rotation. CONCLUSION: CT-RSA is a valid and precise, non-invasive method to measure midfoot kinematics when compared with conventional RSA.

Does temporary bridge plate fixation preserve joint motion after an unstable Lisfranc injury?

BACKGROUND: Recently, temporary bridge plate fixation has gained popularity in the treatment of unstable Lisfranc injuries. The technique aims to reduce the risk of posttraumatic osteoarthritis, and after plate removal, the goal is to regain joint mobility. Here we explore marker-based radiostereometric analysis (RSA) to measure motion in the 1st tarsometatarsal (TMT) joint and asses the radiological outcome in patients treated with this surgical technique. METHOD: Ten patients with an unstable Lisfranc injury were included. All were treated with a dorsal bridge plate over the 1st TMT joint and primary arthrodesis of the 2nd and 3rd TMT joints. The plate was removed four months postoperatively. Non- and weight-bearing RSA images were obtained one and five years postinjury to assess joint mobility and signs of osteoarthritis. RESULTS: Detectable 1st TMT joint motion was observed in 2/10 patients after one year, and 6/9 patients after five years. At the final follow-up, mean 1st TMT dorsiflexion was 2.0°. Radiologically, the incidence of posttraumatic osteoarthritis was present in 4/10 patients after one year, and 5/9 patients after five years. All patients had observed TMT joint stability throughout the follow-up period. CONCLUSION: Preservation of joint motion can be achieved with a temporary bridge plate fixation over the 1st TMT joint. TYPE OF STUDY/LEVEL OF EVIDENCE: Prospective cohort study/Therapeutically level IV.

Outcome after nonoperative treatment of stable Lisfranc injuries. A prospective cohort study.

BACKGROUND: The aim of this study was to evaluate the outcome after nondisplaced and stable Lisfranc injuries. METHODS: 26 patients with injuries to the Lisfranc joint complex detected on CT scans, but without displacement were tested to be stable using a fluoroscopic stress test. The patients were immobilized in a non-weightbearing short leg cast for 6 weeks. The final follow-up was 55 (IQR 53-60) months after injury. RESULTS: All the Lisfranc injuries were confirmed to be stable on follow-up weightbearing radiographs at a minimum of 3 months after injury. Median American Foot and Ankle Society (AOFAS) midfoot score at 1-year follow-up was 89 (IQR 84-97) and at final follow-up 100 (IQR 90-100); The AOFAS score continued to improve after 1-year (P=.005). The median visual analog scale (VAS) for pain was 0 (IQR 0-0) at the final follow-up. One patient had radiological signs of osteoarthritis at 1-year follow-up. CONCLUSION: Stable Lisfranc injuries treated nonoperatively had an excellent outcome in this study with a median follow-up of 55 months. The AOFAS score continued to improve after 1 year.

Temporary Bridge Plating vs Primary Arthrodesis of the First Tarsometatarsal Joint in Lisfranc Injuries: Randomized Controlled Trial.

BACKGROUND: Unstable Lisfranc injuries are best treated with anatomic reduction and stable fixation. There are controversies regarding which type of stabilization is best. In the present study, we compared primary arthrodesis of the first tarsometatarsal (TMT) joint to temporary bridge plating in unstable Lisfranc injuries. METHODS: Forty-eight patients with Lisfranc injuries were included and followed for 2 years. Twenty-four patients were randomized to primary arthrodesis (PA) of the medial 3 TMT joints, whereas 24 patients were randomized to temporary bridge plate (BP) over the first TMT joint and primary arthrodesis of the second and third TMT joints. The main outcome parameter was the American Orthopaedic Foot & Ankle Society (AOFAS) midfoot scale and the secondary outcome parameters were the 36-Item Short Form Health Survey (SF-36) and visual analog scale for pain (VAS pain). Computed tomography (CT) scans pre- and postoperatively were obtained. Radiographs were obtained at follow-ups. Pedobarographic examination was performed at the 2-year follow-up. Twenty-two of 24 patients in the PA and 23/24 in the BP group completed the 2-year follow-up. RESULTS: The mean AOFAS midfoot score 2 years postoperatively was 89 (SD 9) in the PA group and 85 (SD 15) in the BP group (P = .32). There were no significant differences between the groups with regard to SF-36 or VAS pain scores. The alignment of the first metatarsal was better in the BP group than in the PA group measured by the anteroposterior Meary angle (P = .04). The PA group had a reduced peak pressure under the fifth metatarsal (P = .047). In the BP group, 11/24 patients had radiologic signs of osteoarthritis in the first TMT joint. CONCLUSION: Both treatment groups had good outcome scores. The first metatarsal was better aligned in the BP group; however, there was a high incidence of radiographic osteoarthritis in this group. LEVEL OF EVIDENCE: Therapeutic level I, prospective randomized controlled study.

Lisfranc injuries: Incidence, mechanisms of injury and predictors of instability.

BACKGROUND: In Lisfranc injuries the stability of the tarsometatarsal joints guides the treatment of the injury. Determining the stability, especially in the subtle Lisfranc injuries, can be challenging. The purpose of this study was to identify incidence, mechanisms of injury and predictors for instability in Lisfranc injuries. METHODS: Eighty-four Lisfranc injuries presenting at Oslo University Hospital between September 2014 and August 2015 were included. The diagnosis was based on radiologically verified injuries to the tarsometatarsal joints. Associations between radiographic findings and stability were examined. RESULTS: The incidence of Lisfranc injuries was 14/100,000 person-years, and only 31% were high-energy injuries. The incidence of unstable injuries was 6/100,000 person-years, and these were more common in women than men (P = 0.016). Intraarticular fractures in the two lateral tarsometatarsal joints increased the risk of instability (P = 0.007). The height of the second tarsometatarsal joint was less in the unstable injuries than in the stable injuries (P = 0.036). CONCLUSION: The incidence of Lisfranc injuries in the present study is higher than previously published. The most common mechanism of injury is low-energy trauma. Intraarticular fractures in the two lateral tarsometatarsal joints, female gender and shorter second tarsometatarsal joint height increase the risk of an unstable injury. LEVEL OF EVIDENCE: Level III, cross-sectional study.