Intraoperative torsion control using the cortical step sign and diameter difference in tibial mid-shaft fractures

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

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.

Intraoperative Measurement of Tibial Rotation With Lateral Axis Views Using C-arm for Tibial Fractures

Malrotation of tibial fractures after intramedullary nailing remains an unsolved problem. The incidence of malrotation >10° on computer tomography (CT) measurements has been high in cases of tibial shaft fractures. We aimed to assess the accuracy of a novel method for the measurement of tibial rotation using lateral axis views of the C-arm, to prevent postoperative malrotation. Consecutive patients with fresh tibial fractures treated by intramedullary nailing between January 2021 and December 2022 were included prospectively. Baseline tibial external rotation (TER) was measured preoperatively on the non-injured normal side with CT. After proximal or distal screw fixation, the C-arm TER was measured based on lateral axis views (tibial posterior condylar axis and bimalleolar axis views). The C-arm TER was compared with the normal-side CT TER; when the difference was ≤5°, the procedure progressed, and screw fixation was carried out. The fractured-side CT TER was measured one week post-operatively. Twenty patients (13 males and seven females) were included. The mean age was 52.4 years. The Orthopaedic Trauma Association (OTA) classification was 42A in five patients, 42B in twelve patients, and 42C in three patients. The mean difference between C-arm TER and fractured-side CT TER was 2.3°±1.7°, with Pearson correlation coefficient r=0.968. The mean difference between normal-side CT TER and fractured-side CT TER was 4.8°±2.8°, and there was no incidence of malrotation >10°. The C-arm method was highly accurate in estimating CT measurements and preventing tibial malrotation.

Clinical assessment of tibial torsion differences. Do we always need a computed tomography?

Background

Tibial torsional malalignment presents a well-known complication of intramedullary nailing for tibial shaft fractures.

Purpose

Objective of this study was to investigate the ability to clinically assess tibial torsion differences. Computed Tomography (CT) was used here as the gold standard. Further, intra- and inter-observer reliability of the clinical examination, and radiological measurements were calculated.

Methods

Fifty-one patients with torsion-difference CTs, obtained for various reasons, were asked to kneel on an examination couch with free hanging feet. All patients are positioned with 90° flexed knee and neutral ankle. A picture of the lower extremities was obtained from the back of the patient. Two blinded orthopedic surgeons were asked to look at the pictures and measure the tibial torsion with a digital goniometer, based on the axis of the femur in relation to the second ray of the foot. To determine the intra-observer variation, the torsional angles were calculated again after 4 weeks. To be able to compare values, two blinded radiologists calculated torsional differences based on computed tomography.

Results

All patients were able to be positioned for clinical assessment (n = 51). Clinical assessment of torsional difference revealed 4.55° ± 6.85 for the first, respectively, 4.55° ± 7.41 for the second investigator. The second measurement of the first investigator revealed a value of 4.57° ± 6.9. There was a good intra-observer agreement for clinical assessment (ICC 0.993, p < 0.001). Also, the inter-observer agreement showed a good inter-observer agreement (ICC 0.949, p < 0.001). Evaluation of radiological inter-observer assessment could also show a good inter-observer agreement (ICC 0.922, p < 0.001). The clinical method showed a good correlation to the CT method (0.839, p < 0.001). Additionally, the Bland–Altman plot was used to compare graphically both measurement techniques, which proved the agreement.

Conclusion

In summary, computed tomography-assisted measurement of tibial torsion and clinical assessment correlated significantly good. In addition to that, clinical measurement has a good intra- and inter-observer reliability. Clinical examination is a reliable and cost-effective tool to detect mal-torsion and should be part of the repertoire of every surgeon.

Radiographic cortical thickness parameters as predictors of rotational alignment in proximal tibial shaft fractures: a cadaveric study

AIM

The treatment of tibial fractures with an intramedullary nail is an established procedure. However, torsional control remains challenging using intraoperatively diagnostic tools. Radiographic tools such as the Cortical Step Sign (CSS) and the Diameter Difference Sign (DDS) may serve as tools for diagnosing a relevant malrotation. The aim of this study was to investigate the effect of torsional malalignment on CSS and DDS parameters and to construct a prognostic model to detect malalignment.

METHODS

A proximal tibial shaft fracture was set in human tibiae. Torsion was set stepwise from 0° to 30° in external and internal torsion. Images were obtained with a C-arm and transferred to a PC for measuring the medical cortical thickness (MCT), lateral cortical thickness (LCT), tibial diameter (TD) in AP and the anterior cortical thickness (ACT) as well as the posterior cortical thickness (PCT) and the transverse diameter (TD) of the proximal and the distal main fragment.

RESULTS

There were significant differences between the various degrees of torsion for each of the absolute values of the examined variables. The parameters with the highest correlation were TD, LCT and ACT. A model combining ACT, LCT, PCT and TD lateral was most suitable model in identifying torsional malalignment. The best prediction of clinically relevant torsional malalignment, namely 15°, was obtained with the TD and the ACT.

CONCLUSION

This study shows that the CSS and DDS are useful tools for the intraoperative detection of torsional malalignment in proximal tibial shaft fractures and should be used to prevent maltorsion.