- medial malleolar frx result from direct impact of talus or from tension as talus rotates or moves laterally following fibula;
- in children medial malleolus frx may represent supination inversion frx;
Most fractures of the medial malleolus occur as a component part of an injury pattern involving either the lateral malleolus and/or the posterior malleolus to varying degrees. However, a fracture of the medial malleolus can appear to occur in isolation. It is important to make sure that the energy imparted to the medial malleolus to create a fracture has not travelled through the distal tibia-fibular syndesmosis, the interosseous membrane and exited more proximally in the fibula as in the classic Maisonneuve injury. If this has been excluded, then the relatively uncommon injury of an isolated medial malleolar fracture can occur.
Using the Lauge-Hansen classification, these isolated medial malleolar fractures can occur with the foot either in supination or pronation with either a external rotational moment applied across the ankle or with the foot adducted or abducted. The pronation-abduction injury pattern is probably the most common mechanism for generating an isolated fracture. Herscovici described a 4-part fracture classification specifically for the medial malleolus which can offer guidance on how best to fix the varying fracture patterns. The relatively uncommon Type D injuries occur with supination and adduction creating a shearing force to the medial malleolus and leaving a more vertically oriented fracture line. In my opinion, these are unstable fractures that need internal fixation with an anti-glide buttress plate. Alternatively, multiple partially threaded screws can stabilise these fractures as long as they are placed perpendicular to the reduced fracture line. However, most isolated medial malleolar fractures exhibit a transverse fracture line either at the level of the tibio-talar joint line or immediately distal to it. Therefore, the common methods of fracture fixation are to apply compression either with two part-threaded cancellous screws or application of a tension band wiring technique. In this example, the former technique is employed using two Stryker partially threaded 4mm ASNIS screws.
OrthOracle readers will find the following instructional techniques also of interest:
This overview is brought to you by Orthoracle - the online e-learning Orthopeadic Surgery Atlas
- injury patterns:
- deep deltoid ligament may be torn, leaving malleolus intact;
- anterior colliculus may be avulsed by superficial deltoid, leaving deep deltoid ligament either intact or ruptured;
- frx above level of the ligamentous attachment leaves deltoid ligament attached to the distal malleolar fragment;
- associated injuries: (w/ "isolated" medial malleolar fractures)
- maisonneuve fracture;
- talus neck fracture;
- cuboid fracture;
- deltoid ligament injuries arising from ankle frx
- Radiographic Studies
- usually distal frag of medial malleolus is displaced anteriorly & distally;
- eval for osteochondral;
- r/o frx of talar neck;
- Non Operative Treatment:
- Conservative treatment of isolated fractures of the medial malleolus.
- Nonoperative treatment of the medial malleolus in bimalleolar and trimalleolar ankle fractures: a randomized controlled trial.
- Surgical Treatment:
- screw fixation: vertical malleolar frx
- screw fixation: horizontal-oblique frx
- if medial malleolus is fractured in coronal plane or is comminuted, screw purchase may be difficult;
- small, one third tubular plate can be contoured to run along anterior, distal, & posterior edges of malleolus;
- individual fragments can also be reduced & fixed with a single K wire;
- series of figure of 8 wires can then be placed around these K wires to secure the fragments;
- impaction of articlar surface should be elevated during reduction;
- bone grafting may be needed;
- avulsion fractures:
- avulsion frx of medial malleolus may be treated closed if isloated, minimally displaced, & involve distal portion of malleolus;
- reduced after exposing both the anterior and medial aspects of frx by sharply turning back the periosteum and attached fascia;
- short screw theory:
- better fixation with shorter 30 mm partially threaded cancellous screws which engage the physeal scrar;
- ref: Screw fixation of medial malleolar fracture. A cadaveric biomechanical study challenging the current AO philosophy
- bicortical fixation screws:
- Lag screw fixation of medial malleolar fractures: a biomechanical, radiographic, and clinical comparison of unicortical partially threaded lag screws and bicortical fully threaded lag screws.
- Comparison of pullout strength between 3.5-mm fully threaded, bicortical screws and 4.0-mm partially threaded, cancellous screws in the fixation of medial malleolar fractures.
- Medial malleolar fractures: a biomechanical study of fixation techniques.
- Bicortical fixation of medial malleolar fractures: a review of 23 cases at risk for complicated bone healing.
- tension band technique:
- Ostrum and Litsky, tension band wiring has better mechanical properties than 2 cancellous screws (4 times stiffer than two screws);
- bone fragment is held in reduced position w/ tenaculum clamp;
- two 0.45 K wires are driven thru deltoid ligament and tip of medial malleolus and across frx site, but not into proximal tibial cortex;
- tension band figure of 8 wire (20 gauge) can be anchored proximally thru an anterior to posterior drill hole in metaphysis (or
by wrapping wire around head of the screw placed oblique in metaphysis);
- 20 gauge wire is then passed around the K wires and tightened in a figure of 8 fashion (double twist technique is more reliable);
- K wires are cut and turned medially and then tapped into the bone;
- Technical Tip: Fixation of Medial Malleolar Fractures Using a Suture Anchor
- Tension band fixation of medial malleolus fractures.
- Modified tension band wiring of medial malleolar ankle fractures
- Comparison of tension band wire and cancellous bone screw fixation for medial malleolar fractures
Hardware in the medial malleolus: is it intra-articular?