When properly diagnosed and appropriately treated, ankle instability surgery is one of the most successful procedures in foot and ankle surgery. Patient reports of trepidation with walking on uneven surfaces, or constantly rolling an ankle, especially after repeated inversion sprains, is an indication of chronic instability pattern. Careful examination of the lateral and medial collateral ligament complexes, as well as the subtalar joint reveal just where that instability is occurring, and how we approach fixing it.
The lateral collateral complex is made up of the ATFL, CFL and PTFL. The ATFL is probably one of the most commonly injured ligaments in the human body, due to the relative weak nature of the ligament and anatomic position on the outside of the ankle joint. Along with the CFL they are poor resistors of inversion since the torque of the body over these small structures can easily overwhelm their ability to contain movement beyond a certain point. Consider this an 'evolutionary weak point.'
When inversion injuries occur, a square bone is turned or rotated inside of a square recess - not a good scenario. The shoulders of the ankle bone wedge the fibula outward, causing tension on the ligaments which will ultimately tear. In addition the cartilage and surrounding structures (capsule, tendons, and muscles) also sustain damage.
Surgical repair involves inventory of all of these structures, including the syndesmosis that holds the tibia and fibula together. In this episode I focused on the direct repair or augmentation of the most common situations. In the next episode I will dive into more detail on osteochondral defects, and later on the high ankle sprain and more occult injuries that are commonly missed even by astute practitioners.