The external rotation fracture of the fibular malleolus

Indications and Interpretation of Stress Radiographs in Supination External Rotation Ankle Fractures

Introduction In supination external rotation (SER) ankle fractures with an intact medial malleolus, stability hinges upon the competence of the deltoid ligament. The purpose of this study is to define the indications and establish criteria for a positive stress radiograph. Methods This is a prospective study of 27 isolated SER lateral malleolar fractures with a reduced ankle mortise. Pain and swelling were noted about the medial ankle, followed by an ultrasound to evaluate the integrity of the deltoid ligament. Static and stress radiographs were performed on both the fractured and contralateral ankles. Results Fourteen patients were normal on ultrasound examination, eight had partial tears, and five had full-thickness tears. The difference in the level of pain to palpation postero-medially between the complete tear (7 +/- 1) and the partial tear (1.3 +/- 2.4) group was significant (p < .001). The negative predictive values for medial swelling and tenderness were 93% and 100%, respectively. Sensitivity and specificity for medial clear space on stress radiograph (fracture (fx)) > 5.0 mm were both 100% while a 2.5 mm or greater change to the contralateral side yielded a sensitivity of 100% and specificity of 95%. Conclusion The lack of significant medial pain, as well as swelling, implies the absence of a complete ligament tear and eliminates the need for stress examination. Conversely, the presence of medial signs of injury is suggestive, but not pathognomonic for a complete deltoid tear. Medial clear space (MCS) variability prompts to recommend a minimum of 2.5 mm on stress radiographs compared to the contralateral side as indirect evidence for a complete tear of the deltoid ligament.

The concept of ring of injuries: evaluation in ankle trauma

OBJECTIVE

Radiographs are first-line imaging in ankle trauma but lack sensitivity to detect ligamentous injuries and undisplaced fractures. Our hypothesis was that ankle injuries occur in predefined sequences along two osteoligamentous rings, so that occult injuries non-visible on initial radiographs can be predicted. We, therefore, aimed to validate a ring model of progressive damages in the interpretation of ankle trauma radiographs.

METHODS

This study retrospectively enrolled 277 adult patients that presented an acute fibular fracture on ankle radiographs between May and November 2019. Four different types of fibula fracture were differentiated, each being considered to correspond to a different mechanism of injury. Patients were classified into four groups, upon the appearance of their fibular fracture. Then, injuries to the distal tibiofibular syndesmosis, medial malleolus, and deltoid ligament (medial clear space) were assessed in each patient radiographs. Traumatic injuries were independently evaluated by a resident and an experienced MSK radiologist. For each patient, observed features were compared to those predicted by the ring concept. Inter- and intraobserver agreements were calculated.

RESULTS

Injuries were observed according to the predictable sequence in 266 of the 277 patients (96%). In the 11 remaining patients, discordances were presumably due to undisplaced injuries to the syndesmosis or deltoid ligament. Agreements were considered very good for each evaluated item.

CONCLUSION

The Lauge-Hansen ring concept was found to be highly accurate and reproducible for radiographic assessment of ankle injuries. Discordances to the predicted sequence might reflect occult injuries, especially of the syndesmosis or deltoid ligament.

Which ankle fractures require syndesmotic stabilization?

Syndesmotic ruptures associated with ankle fractures are most commonly caused by external rotation of the foot, eversion of the talus within the ankle mortise, and excessive dorsiflexion. The distal tibiofibular syndesmosis consists of the anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament, and interosseous ligament, and it is essential for stability of the ankle mortise. Despite the numerous biomechanical and clinical studies pertaining to ankle fractures, there are no uniform recommendations regarding the use of the syndesmotic screw for specific injury patterns and fracture types. The objective of this review was to formulate recommendations for clinical practice related to the use of syndesmotic screw placement.

Transfibular osteotomy in the correction of ankle joint incongruity

The mechanics involved in Danis-Weber-types B and C ankle fractures may allow the fibula to seek a shortened and externally rotated position following injury. Residual talar instability secondary to fibular malalignment may ensue if proper anatomic restoration is not achieved at the time of reduction. Evaluation of ankle incongruity may take the form of clinical, radiographic, and diagnostic techniques. Three case studies are presented in which fibular osteotomies were utilized to restore proper anatomic alignment and function to the ankle mortise.

Thirty-year follow-up of ankle fractures

The natural course of ankle fractures was studied in 143 patients treated by closed methods. The average time elapsing from fracture to follow-up was 29 years. Eighty-two per cent had no radiographic signs of arthrosis; 83 per cent were free of symptoms. The most common fracture, supination eversion Stage II (49 cases), gave rise to minimal signs of arthrosis in only one patient, who had moderate symptoms. The suggestion that all ankle fractures must be perfectly reduced is not supported by the findings of the present study.

The orthotic treatment of stable ankle fractures

Fifteen limbs with stable lateral malleolar fractures treated with an adjustable, functional orthosis were compared to 12 limbs managed with short leg walking casts. The limbs managed with the adjustable orthosis were clinically healed at an average of 3.3 weeks with no fracture tenderness and with the ability to bear full weight without pain. Range of motion in the orthotic group at the end of treatment was significantly better than the casted group. Patient compliance was excellent. The advantages of the orthotic treatment include a more physiologic gait pattern due to the rocker bottom sole, ease of application, lighter weight, removability for range of motion exercises and bathing, and adjustability to maintain a good fit as posttraumatic swelling resolves.

Classification and treatment of ankle fractures

Treatment of ankle fractures should restore normal ankle joint anatomy. The systematic approach in analysis based on understanding of the anatomy, the roentgenograms and the mechanism of injury allow one to determine the elements of the lesion. The Lauge-Hansen classification is most helpful because it takes into account the ligamentous damage that may have occurred, therefore, giving one a better appreciation of the extent of the injury. Open reduction that accurately restores the joint anatomy produces the best and most enduring end-results. Early mobilization of the ankle is possible when internal fixation has produced stability that withstands the dynamic activity of controlled use. A "cook book" approach should not be used; rather, the fundamental principles should be understood, and then the methods of treatment will be self-evident.