[Malleolar Fractures - Indication for Nonoperative and Operative Treatment]. / Malleolarfrakturen.

Malleolar Fractures - Indication for Nonoperative and Operative Treatment Abstract. In order to understand the trauma mechanism and the expected pattern of injury, malleolar fractures can be classified according to Lauge-Hansen [1]. For isolated lateral malleolar fractures, the Weber classification is also frequently used [2]. For most Weber A fractures and 80% of Weber B fractures conservative treatment is indicated. In all isolated Weber B fractures a supination-external rotation (SER) injury has to be distinguished from a pronation-abduction (PA) injury according to the Lauge-Hansen classification. In SER fractures, stability should be assessed by a gravity stress and a weightbearing radiograph. If the fracture is stable, it can be treated nonoperatively. We recommend surgical treatment for unstable Weber B SER injuries, Weber B PA injuries, and Weber C fractures.

Ankle Joint Pressure in Supination-External Rotation Injuries: A Biomechanical Study in an Unrestrained Cadaver Model.

BACKGROUND: Previous biomechanical studies simulating supination-external rotation (SER) IV injuries revealed different alterations in contact area and peak pressure. We investigated joint reaction forces and radiographic parameters in an unrestrained, more physiological setup. METHODS: Twelve lower leg specimens were destabilized stepwise by osteotomy of the fibula (SER II) and transection of the superficial (SER IVa) and the deep deltoid ligament (SER IVb) according to the Lauge-Hansen classification. Sensors in the ankle joint recorded tibio-talar pressure changes with axial loading at 700 N in neutral position, 10° of dorsiflexion, and 20° of plantarflexion. Radiographs were taken for each step. RESULTS: Three of 12 specimen collapsed during SER IVb. In the neutral position, the peak pressure and contact area changed insignificantly from 2.6 ± 0.5 mPa (baseline) to 3.0 ± 1.4 mPa (SER IVb) (P = .35) and from 810 ± 42 mm2 to 735 ± 27 mm2 (P = .08), respectively. The corresponding medial clear space (MCS) increased significantly from 2.5 ± 0.4 mm (baseline) to 3.9 ± 1.1 mm (SER IVb) (P = .028).The position of the ankle joint had a decisive effect on contact area (P = .00), center of force (P = .00) and MCS (P = .01). CONCLUSION: Simulated SER IVb injuries demonstrated radiological, but no biomechanical changes. This should be considered for surgical decision making based on MCS width on weightbearing radiographs. LEVELS OF EVIDENCE: Not applicable. Biomechanical study.