Intraoperative fluoroscopic protocol to avoid rotational malalignment after nailing of tibia shaft fractures: introduction of the 'C-Arm Rotational View (CARV)'

Abstract

Purpose: Rotational malalignment (≥ 10°) is a frequent pitfall of intramedullary-nailing of tibial shaft fractures. This study aimed to develop an intraoperative fluoroscopy protocol, coined 'C-Arm Rotational View (CARV)', to significantly reduce the risk for rotational malalignment and to test its clinical feasibility.

Methods: A cadaver and clinical feasibility study was conducted to develop the CARV-technique, that included a standardized intraoperative fluoroscopy sequence of predefined landmarks on the uninjured and injured leg in which the rotation of the C-arm was used to verify for rotational alignment. A mid-shaft tibia fracture was simulated in a cadaver and an unlocked intramedullary-nail was inserted. Random degrees of rotational malalignment were applied using a hand-held goniometer via reference wires at the fracture site. Ten surgeons, blinded for the applied rotation, performed rotational corrections according to (1) current clinical practice after single-leg and dual-leg draping, and (2) according to the CARV-protocol. The primary outcome measure was the accuracy of the corrections relative to neutral tibial alignment. The CARV-protocol was tested in a small clinical cohort.

Results: In total, 180 rotational corrections were performed by 10 surgeons. Correction according to clinical practice using single-leg and dual-leg draping resulted in a median difference of, respectively, 10.0° (IQR 5.0°) and 10.0° (IQR 5.0°) relative to neutral alignment. Single-leg and dual-leg draping resulted in malalignment (≥10°) in, respectively, 67% and 58% of the corrections. Standardized correction using the CARV resulted in a median difference of 5.0° (IQR 5.0°) relative to neutral alignment, with only 12% categorized as malalignment (≥10°). The incidence of rotational malalignment after application of the CARV decreased from 67% and 58% to 12% (p = <0.001). Both consultants and residents successfully applied the CARV-protocol. Finally, three clinical patients with a tibial shaft fracture were treated according to the CARV-protocol, resulting all in acceptable alignment (<10°) based on postoperative CT-measurements.

Conclusion: This study introduces an easy-to-use and clinically feasible standardized intraoperative fluoroscopy protocol coined 'C-arm rotational view (CARV)' to minimize the risk for rotational malalignment following intramedullary-nailing of tibial shaft fractures.

Keywords: Intramedullary-nailing; Rotational malalignment; Tibia shaft fractures; ‘C-Arm Rotational View (CARV)’.

Fig. 1

Schematic overview of the “C-arm Rotational View (CARV)”. The CARV is an intraoperative fluoroscopy sequence comparing the uninjured and injured leg in which the degree of rotation of the C-arm itself is used to correct for rotational malalignment of the tibia. At the uninjured leg, a perfect mortise-view is taken with the knee in AP-position by rotating the C-arm between 20 and 30°. At the injured leg, the C-arm is rotated to the same extent in the opposite direction while the knee is in AP-position and subsequently the distal part of the lower leg is rotated until a perfect mortise-view is achieved, indicating symmetrical tibial alignment.

Fig. 2

Schematic overview of alterations of the proximal and distal landmarks of the CARV-protocol after applying different degrees of both internal and external rotations. a After application of internal rotation, the proximal fibula head is more exposed while the medial clear space of the ankle joint minimizes. b After application of external rotation, there was an increased superimposement of the proximal fibula head by the lateral tibia plateau with lesser distance of the lateral clear space of the ankle joint.