Review Question - QID 3830

Figure A shows a low posterior plate with a prominent screw head in the most distal hole of the plate. This fixation technique is correlated with peroneal pathology, which usually presents months after fixation when the patient increases their activity level.

The two most common fixation techniques of lateral malleolus fractures are (1) lag screw plus lateral neutralizing plating and (2) posterolateral antiglide plating. The disadvantages of the lateral plating includes the risk of intraarticular screws distally, prominent lateral hardware, and poor distal screw fixation. To overcome these complications, posterolateral antiglide plating allows for bicortical distal fixation with no articular perforation. However, low placement of the plate with a prominent screw head in the most distal hole is associated with symptomatic peroneal pathology. If the most distal screw is not prominent, or absent, this is less likely to cause peroneal complications.

Weber et al. examined the effect of antiglide plate and screw positioning on peroneal tendon pathology. They showed that low posterior plating and large screw heads caused significant retromalleolar pain in most patients. To decrease peroneal pathology, they state that the distal end of the plate should stay proximal to the osteosynovial peroneal groove. Radiologically this level corresponds to the junction of the proximal and middle thirds of the lateral malleolus.

Figure A shows a posterior positioned 5 hole 1/3 tubular plate. There is no articular screw penetration and the fracture is healed in an anatomical position. The distal aspect of the plate is is the distal third of the lateral malleolus.

Incorrect Answers:
Answer 1: The most distal screws rarely penetrates the joint with the use of fibular antiglide plates. In addition, there is no evidence of screw penetration in this patient.
Answer 3: A missed syndesmosis disruption would usually show some radiographic findings. The tibiofibular clear space is usually most sensitive, which is measured radiographically by the distance from the lateral border of the posterior malleolus in the distal tibia to the medial border of the fibula. As a general rule, it is considered normal if the measurement is less than approximately 6 mm on both AP and mortise views.
Answer 4: The fracture reduction looks anatomic. The talocrural angle, 'dime' sign and “Shenton's line” of the ankle all normal.
Answer 5: The construct used to fix this isolated lateral trans-syndesmotic fracture is acceptable. The one-third tubular plate, which is placed posterolaterally on the fibula as an antiglide plate, indirectly reduces the fracture and acts as a buttress to resist the posterior and proximal displacement of the distal fragment. Insertion of a lag screw through the plate is a described technique.