Injury of the tibiofibular syndesmosis: value of MR imaging for diagnosis

Arthroscopic assessment of the syndesmosis following ankle fracture

A Maisonneuve ankle fracture without convincing evidence of syndesmotic injury on plain radiographs is described. Stress views and computerised tomography (CT) were also negative. A high index of suspicion led to ankle arthroscopy, which revealed a diastasis, and also an osteochondral fragment. This was treated with two percutaneous diastasis screws and removal of the osteochondral fragment. This case suggests that ankle arthroscopy should be considered as part of the management of syndesmotic injury where conventional imaging techniques fail to show syndesmotic disruption.

MRI findings associated with distal tibiofibular syndesmosis injury

OBJECTIVE

Our objective was to describe the MRI findings associated with acute and chronic distal tibiofibular syndesmosis injury.

MATERIALS AND METHODS

Ninety-four 1.5-T MRIs of ankles of 90 individuals with histories of severe sprain were assessed by two musculoskeletal radiologists for syndesmosis injury (acute, edema of the syndesmosis; chronic, disruption or thickening of the syndesmosis without edema). We examined associated MRI findings, including anterior talofibular ligament injury (scar, chronic injury; edema, acute injury), bone bruise, osteochondral lesion, tibiofibular joint congruity, tibiofibular recess height, and osteoarthritis. The Fisher's exact test and analysis of variance test were used to evaluate the significance of the associations.

RESULTS

In 94 ankles, syndesmosis injury was seen in 63% (n = 59; 23 acute; 36 chronic). Anterior talofibular ligament injury (acute or chronic) was seen on MRIs in 74% (n = 70; 49 with syndesmosis injury; 21 without; p = 0.03). Bone bruises were present in 24% (n = 23; 18/23 acute; 4/36 chronic; 4/35 no injury; p < 0.0001). Of these, talar dome osteochondral lesions were present in 28% (n = 26; 11/23 acute; 14/36 chronic; 1/35 no injury; p = 0.0001; 13 medial; 13 lateral). The tibiofibular joint was incongruent in 33% (n = 31; 6/23 acute; 21/36 chronic; 4/35 no injury; p < 0.0001). The tibiofibular recess (mean +/- SD) was 1.2 +/- 0.92 cm in acute cases, 1.4 +/- 0.57 cm in chronic cases, and 0.54 +/- 0.68 cm in cases with no syndesmosis injury (p < 0.0001). Osteoarthritis was present in 10% (n = 9; 1/23 acute; 7/36 chronic; 1/35 no injury; p = 0.06).

CONCLUSION

Injury to the distal tibiofibular syndesmosis has a significant association with a number of secondary findings on MRI, including anterior talofibular ligament injury, bone bruises, osteochondral lesions, tibiofibular joint congruity, and height of the tibiofibular recess.

Correlation of interosseous membrane tears to the level of the fibular fracture

OBJECTIVES

To correlate interosseous membrane (IOM) tears of the ankle to the height of fibular fractures in operative ankle fractures.

DESIGN

Prospective clinical trial.

SETTING

University Level 1 trauma center.

PATIENTS

All patients admitted with a closed operative ankle fracture were included. Of 93 patients originally evaluated, 73 patients had adequate MRI for evaluation.

INTERVENTION

Open reduction and internal fixation of each ankle fracture was performed after preoperative MRI evaluation of the IOM. Transsyndesmotic screw fixation was performed when evidence of syndesmotic instability was shown by intraoperative stress testing.

MAIN OUTCOME MEASUREMENTS

Radiographs were analyzed for fracture classification and prediction of ligamentous injuries about the ankle. MRI evaluated the IOM integrity, correlating it to the height of the fibular fracture.

RESULTS

Of the 73 ankle fractures with adequate MRI evaluation, 30 had identifiable complete IOM tears on MRI. Ten of the 30 IOM tears did not correlate with the level of the fractured fibula. Seven cases had IOM tears proximal to the fibular fracture as detected by MRI. Five of these cases were Weber B type fractures, and two were Weber C type fracture patterns. Conversely, three cases of Weber C type fractures had IOM tears that remained distal to the level of the fibular fracture.

CONCLUSIONS

The level of the fibular fracture does not correlate reliably with the integrity or extent of the interosseous membrane tears identified on MRI in operative ankle fractures. One cannot consistently estimate the integrity of the IOM and subsequent need for transsyndesmotic fixation based solely on the level of the fibular fracture. An intraoperative syndesmotic stress test is recommended to establish the presence or absence of syndesmotic instability.