Ankle CT scan allows better management of posterior malleolus fractures than X-rays

Historic indications for fixation of posterior malleolus fractures- where did they come from and where are we now?

INTRODUCTION

The indications for reduction and fixation of the posterior malleolus component of rotational ankle fractures have been controversial for nearly a century. This study aims to identify the historical basis for surgical intervention and trace trends in management strategies over time.

METHODS

In March 2023, a systematic review of full-text, English-language articles providing indications for surgical fixation of the posterior malleolus component of rotational ankle fractures was performed. Articles underwent title and abstract screening before undergoing full-text review.

RESULTS

Historical indications for surgical fixation were size-dependent, with fractures comprising 25 % to 33 % of the plafond recommended for internal fixation. Modern studies suggest that nonoperative management of posterior malleolus fractures below this threshold results in residual malreduction of the articular surface, syndesmotic instability, and an increased need for independent fixation of the syndesmosis.

CONCLUSIONS

Size-based indications for posterior malleolus fracture fixation are based on Level V evidence from small retrospective case series published nearly one century ago and should be retired. While the size of the posterior malleolus component cannot be ignored, additional factors like fracture morphology and location within the plafond should guide modern surgical indications. Contemporary studies indicate that reduction and fixation of small posterior malleolus fractures (comprising less than 25 % of the articular surface) are associated with improved articular reductions, tibiotalar contact pressures, syndesmotic stability with decreased need for independent fixation of the syndesmosis, and superior postoperative outcomes.

Computed Tomography Scans and Fixation Rates for Trimalleolar Ankle Fractures Over 10 Years at a Level 1 Trauma Center

Background

The posterior malleolus component of the trimalleolar ankle fracture has posed a controversial topic for diagnostic imaging and surgical management. Preoperative computed tomography (CT) scans are used to better appreciate fracture morphology and may affect management techniques. No prior study has investigated the trend in preoperative CT scan use and the rates of posterior and syndesmotic fixation for trimalleolar injuries.

Methods

This retrospective cohort study evaluated the use of preoperative CT scans and the rates of posterior and syndesmotic fixation for trimalleolar ankle fractures over a 10-year period at an adult level 1 trauma center. Patients surgically managed for ankle fractures with OTA/AO classifications of 44B3, 44C3.3, 44C1.3, 44C2.3, and 44A3 were identified and included using Current Procedural Terminology codes and a prospectively collected fracture registry. Demographic information, comorbidities, fixation methods, and use of preoperative CT scan were recorded. Comparative analyses were performed to assess for yearly differences in demographic characteristics along with changes in trends of preoperative CT scans and posterior and syndesmotic fixation.

Results

A total of 1191 patients were included in the analyses. OTA/AO 44B3.2 fractures were the most common injuries (yearly range of 59.4%-80.1%). The rate of posterior fixation did not significantly increase during the study interval (1.4% growth per year [95% CI -0.27, 3.07]). However, the rate of preoperative CT scan use significantly increased by 2.76% (95% CI 1.99, 3.52) per year and the rate of syndesmotic fixation increased by 2.58% (95% CI 1.17, 3.99) per year. Fixation methods for both the syndesmosis and posterior malleolus changed during the study timeline.

Conclusion

Despite a relatively stable rate of posterior fixation, the frequency of preoperative CT scans and use of syndesmotic fixation increased significantly over a 10-year study period.

Level of Evidence

Level IV, descriptive pilot study.

Importance of computed tomography in posterior malleolar fractures: Added information to preoperative X-ray studies

BACKGROUND

Ankle fractures are common lesions of the lower limbs. Approximately 40% of ankle fractures affect the posterior malleolus (PM). Historically, PM osteosynthesis was recommended when PM size in X-ray images was greater than 25% of the joint. Currently, computed tomography (CT) has been gaining traction in the preoperative evaluation of ankle fractures.

AIM

To elucidate the similarity in dimensions and to correlate PM size in X-ray images with the articular surface of the affected tibial plafond in the axial view on CT (AXCT) of a PM fracture.

METHODS

Eighty-one patients (mean age: 39.4 ± 13.5 years) were evaluated (54.3% were male). Two independent examiners measured PM size in profile X-ray images (PMXR) and sagittal CT (SAGCT) slices. The correlation of the measurements between the examiners and the difference in the PM fragment sizes between the two images were compared. Next, the PM size in PMXR was compared with the surface of the tibial plafond involved in the fracture in AXCT according to the Haraguchi classification.

RESULTS

The correlation rates between the examiners were 0.93 and 0.94 for PMXR and SAGCT, respectively (P < 0.001). Fragments were 2.12% larger in SAGCT than in PMXR (P = 0.018). In PMXR, there were 56 cases < 25% and 25 cases ≥ 25%. When PMXR was < 25%, AXCT corresponded to 10.13% of the tibial plafond. When PMXR was ≥ 25%, AXCT was 24.52% (P < 0.001). According to the Haraguchi classification, fracture types I and II had similar PMXR measurements that were greater than those of type III. When analyzing AXCT, a significant difference was found between the three types, with II > I > III (P < 0.001).

CONCLUSION

PM fractures show different sizes using X-ray or CT images. CT showed a larger PM in the sagittal plane and allowed the visualization of the real dimensions of the tibial plafond surface.

Plain X-ray is insufficient for correct diagnosis of tibial shaft spiral fractures: a prospective trial

PURPOSE

Tibial shaft spiral fractures and fractures of the distal third of the tibia (AO:42A/B/C and 43A) frequently occur with non-displaced posterior malleolus fractures (PM). This study investigated the hypothesis that plain X-ray is not sufficient for a reliable diagnosis of associated non-displaced PM fractures in tibial shaft spiral fractures.

METHODS

50 X-rays showing 42A/B/C and 43A fractures were evaluated by two groups of physicians, each group was comprised of a resident and a fellowship-trained traumatologist or radiologist. Each group was tasked to make a diagnosis and/or suggest if further imaging was needed. One group was primed with the incidence of PM fractures and asked to explicitly assess the PM.

RESULTS

Overall, 9.13/25 (SD ± 5.77) PM fractures were diagnosed on X-ray. If the posterior malleolus fracture was named or a CT was requested, the fracture was considered "detected". With this in mind, 14.8 ± 5.95 posterior malleolus fractures were detected. Significantly more fractures were diagnosed/detected (14 vs. 4.25/25; p < 0.001/14.8 vs. 10.5/25; p < 0.001) in the group with awareness. However, there were significantly more false positives in the awareness group (2.5 vs. 0.5; p = 0.024). Senior physicians recognized slightly more fractures than residents (residents: 13.0 ± 7.79; senior physicians: 16.5 ± 3.70; p = 0.040). No significant differences were demonstrated between radiologists and trauma surgeons. The inner-rater reliability was high with 91.2% agreement. Inter-rater reliability showed fair agreement (Fleiss-Kappa 0.274, p < 0.001) across all examiners and moderate agreement (Fleiss-Kappa 0.561, p < 0.001) in group 2.

CONCLUSION

Only 17% of PM fractures were identified on plain X-ray and awareness of PM only improved diagnosis by 39%. While experiencing improved accuracy, CT imaging should be included in a comprehensive examination of tibial shaft spiral fractures.

LEVEL OF EVIDENCE

II. Diagnostic prospective cohort study.

TRAIL REGISTRATION NUMBER

DRKS00030075.