SLR - October 2022 - Michael Radcliffe, DPM
Reference: Nakasa T, Ikuta Y, Sumii J, Nekomoto A, Adachi N. High-stress distribution in the lateral region of the subtalar joint in the patient with chronic lateral ankle instability. Arch Orthop Trauma Surg. 2022 Jul;142(7):1579-1587.Level of Evidence: III
Scientific Literature Review
Reviewed By:
Michael Radcliffe, DPM
Residency Program:
UF College of Medicine - Jacksonville; Jacksonville, FL
Podiatric Relevance:
Chronic lateral ankle instability (CLAI) and its relationship to osteoarthritis (OA) in the ankle is a relevant topic because CLAI can be sequela resulting from inversion ankle sprains, which are very common. This condition may require surgical intervention to avoid progression to ankle OA. Not all patients with CLAI develop OA of the ankle. The authors investigated specific risk factors for OA by comparing pressure distribution maps in the subtalar joint (STJ) and ankle joint. This information is useful to the podiatric surgeon when it comes to discussing treatment outlook and anticipating need for surgery in patients with CLAI. The authors hypothesized that patients with CLAI have a specific stress distribution pattern on the ankle and subtalar joints and that the subchondral bone stresses might differ by multiple factors.
Methods:
A level III comparative study was conducted on a total of 59 ankles in 54 patients where 33 ankles with CLAI were treated surgically and compared to 26 ankles without CLAI as controls. CT scans were obtained on all ankles and Hounsfield Unit (HU) values were measured to create three-dimensional pressure distribution maps of the ankle and subtalar joints. The high HU value areas were compared between CLAI and control groups. Additionally, relationships between HU and ankle activity score (AAS), OA, talar tilting angle (TTA), and cartilage injury were assessed in the CLAI group.
Results:
The anteromedial and medial gutter portions of the ankle had higher pressure distributions in CLAI compared to the control group. The CLAI group had higher pressure distributions in the lateral side of the talus and calcaneal articulations in the STJ. In the CLAI group, those with OA or cartilage injury on the talus also showed higher HU values in the lateral region of the subtalar joint than in those without. Patients with CLAI associated with high activity and CFL deficiency showed significantly higher HU values in the lateral STJ than those with low activity. Significantly higher HU values were noted in the lateral region of the STJ in CLAI patients with an AAS ≧ 6, over 10° of TTA, cartilage injury, and OA changes in the medial ankle compared to those lower AAS and TTA values and no cartilage or OA changes.
Conclusion:
Patients with CLAI demonstrate higher HU values in the lateral STJ than those without CLAI, and of those with CLAI, patients with higher activity, larger TTA values, cartilage injuries and OA changes in the medial ankle have higher HU values in the lateral STJ than those CLAI patients without those factors. Patients with OA changes and cartilage injury had significantly higher ages than those without suggesting that long term CLAI can cause excess stress to the lateral STJ and lead to worsening pathology. The compensatory mechanism of the STJ is disrupted in these higher HU value patients with CLAI, which can lead to increased risk of developing ankle OA. These patients should be treated for CLAI to eliminate instability and prevent OA progression.