Arthroscopy may help detect occult pathology in open treatment of ankle fractures

John G. Kennedy, MD, MCh, MMSc, FFSEM, FRCS (Orth)

Ankle fractures are the leading cause of posttraumatic arthritis in the ankle joint. Since the 1970s, orthopedic surgeons have been using the data of Paul L. Ramsey, MD, and William Hamilton, MD, that we must be within a millimeter of articular congruence to prevent arthritis when treating fractures with open reduction and internal fixation. Despite this excellence in achieving radiographic alignment, ankle fractures still progress to posttraumatic arthritis and are a leading cause of disability in this cohort of patients. Even with advances in ankle replacement, the long-term consequences and treatment of ankle posttraumatic arthritis are not as predictable as with other joints including the hip and knee. Because of this, attention has been directed at looking at cartilage of the talus and tibial plafond at the time of ankle fractures.

Cartilage of the ankle joint has different mechanical and biological characteristics than cartilage of other joints. It is just 1 mm to 2 mm thick so when the energy of an ankle fracture is transmitted to the articular surface, cartilage damage is inevitable. In common with all articular cartilage, ankle cartilage has little or no potential to heal and fills in gaps with scar or fibrocartilage, which has inferior long-term tribologic qualities than hyaline cartilage and degrades over time leading to posttraumatic arthritis.

Much attention has been directed at biologic materials to help restore hyaline cartilage and, while small focal defects have the potential to heal, large-scale loss of hyaline cartilage of the ankle joint has eluded repair or replacement with biologic intervention to date. Biologic augmentation, such as platelet-rich plasma, concentrated bone marrow aspirate and marrow adipose tissue fat cell treatments, all provide a biologic milieu that act as immune modulators slowing down the catabolic destruction of native cartilage and provide some, if limited, chondrogenic potential. Thus, there is reason to consider these at the time of open reduction and internal fixation as a biologic supplement to slow down the onset of posttraumatic arthritis. More data is needed to substantiate this potential, but the basic science evidence exists and small level 4 studies are encouraging.

The only way to substantiate the level of injury to the entre articulating surface is with arthroscopic evaluation of the joint. Despite open reduction helping visual inspection of the joint, this is neither complete nor reliable. Arthroscopy at the time of ankle fracture reduction has been shown to improve outcome scores in a single study from a Japanese population. In other studies, the evidence has been inconclusive in part because posttraumatic arthritis takes many years to develop and the follow-up in most studies has been short. In a large systematic review of all ankle fractures recorded on a national database, an interesting finding was that second surgeries were reduced in those that had concomitant open reduction and internal fixation and arthroscopy. In those cases that did need a second surgery, that procedure was a smaller intervention than that required in the patients treated with open reduction and internal fixation alone. The study also pointed out that less than 2% of all ankle fractures in the United States are treated with arthroscopy and open reduction and internal fixation. Most busy trauma services have found that setting up a traction system to gain access to the joint adds time, equipment and cost to a relatively facile procedure, and so the number of centers including arthroscopy has not been gaining as would be expected. Recently, the introduction of a 1.9-mm disposable scope with chip-on-tip technology has increased the potential for ankle arthroscopy at the time of open reduction and internal fixation. Nanoscope does not require ankle joint distraction and can be performed to confirm articular alignment post-open reduction and internal fixation while delivering a biologic to augment cartilage health. At the very least, it will provide a visual metric that can be used to guide patients’ expectations, that, despite the best skeletal open reduction and internal fixation, the quality of ankle cartilage is the ultimate harbinger of ankle fracture outcomes.

Reference:

Takao M, et al. J Trauma. 2004;doi:10.1097/01.ta.0000114062.42369.88.

Yasui Y, et al. J Foot Ankle Surg. 2019;doi:10.1053/j.jfas.2018.03.030.