Comparison of different intraoperative reduction monitoring methods in a cadaveric intraarticular calcaneal fracture model: 3D scan vs arthroscopy vs nanoscopy

AIMS: Visualization of the subtalar joint surface in surgical management of calcaneal factures remains a big challenge and anatomic reduction of the articular surface is essential for a good clinical outcome. We hypothesize that video-assistance can provide superior fracture reduction compared to fluoroscopy and that nanoscopy (NSC) achieves more extensive visualization compared to fracturoscopy (FSC).

METHODS: Ten human cadaveric feet with artificially pre-fractured intraarticular calcaneal fractures with involvement of the posterior facet were treated via a minimal invasive subtalar approach. After initial control of reduction by 2D fluoroscopy, the reduction was further analyzed intraoperatively by FSC and NSC. 3D Scan served as gold standard control of reduction. Need of revision of reduction after the different visualization techniques was recorded and the extent of visualization of the subtalar joint surface in the medio-lateral dimension was compared for FSC and NSC. To quantify access and visualization of the medial and posterior facet, a depth gauge was used to measure from laterally at the clinically widest portion of the calcaneus targeted to the sustentaculum tali. The distance in millimetres was referred to the complete medio-lateral distance seen on paracoronal CT at the widest portion of the calcaneus.

RESULTS: Fracture analysis in preoperative CT-scans according to Sanders classification revealed four type IC, two IIA, three IIC and one IIIAC fractures. Mean visualization of the medial and posterior facet was significantly improved with NSC (30.4 ± 3.78 mm) compared to FSC (23.6 ± 6.17 mm) (p = 0.008). An imperfect reduction requiring revision was more often required with NSC compared to FSC. Insufficient reduction using video-assistance was found in two cases.

CONCLUSION: In order to optimize subtalar joint reduction and congruency, video-assisted techniques, especially NSC, provide superior visualization and thus can improve reduction in the surgical treatment of intraarticular calcaneal fractures.