Summary

This is a narrative review of the biomechanical factors that contribute to the onset and progression of osteochondral injuries (OLT) of the talus, synthesising existing hypotheses and evidence on how aspects of bone density, cartilage thickness, trauma, gait dynamics, and joint stability influence intra-articular load distribution and ankle joint stress, and visions for future research.

Abstract

Background

Osteochondral lesions of the talus (OLTs) are common ankle injuries, often caused by a sprain in the ankle joint and potentially leading to ankle osteoarthritis. While biomechanics plays an important role in joint motion and health, the literature on the role that biomechanical factors play in the development of OLTs is fragmented.
Objectives: The aim of this narrative review is to synthesize the current knowledge on the biomechanical factors that contribute to the development of OLTs.

Methods

Three databases PubMed, EMBASE (OVID) and Sportdiscus (Ebsco) were searched from their inception to March 26th, 2024, for studies about biomechanical factors in OLTs or biomechanical considerations in the development of OLTs.

Results

A total of 1946 studies were retrieved from the databases, and 21 studies were included in this literature. Results from the reviewed studies showed that 1) Significant differences in bone density and penetration strength as well as cartilage thickness and stiffness affect load distribution and stress concentration within the joint, especially at the medial and lateral edges of the talus, indicating that these areas are most susceptible to lesions due to greater loading and reduced regenerative potential; 2) Traumatic injury is the main cause of OLTs, particularly ankle inversion sprains. This may lead to acute and chronic osteochondral damage as well as repetitive microtrauma. Cartilage cracks that extend into the subchondral bone following trauma can lead an inadequate repair response, synovial fluid is squeezed into the cracks under load, eventually forming cysts and causing osteochondral damage; 3）Biomechanical movements and internal and external rotational transitions during the gait cycle produce significant stresses in the ankle joint, altering the loading pattern, and the repetitive nature of these movements may increase cartilage wear and lead to the development of OLTs; 4) Load distribution within the ankle joint has an important impact on the development of OLTs. Stress is usually concentrated around the defect area, and larger defects lead to reduced intra-articular contact area and increased stress, further aggravating lesion progression; 5) Ligament instability and muscle weakness can cause changes in the location of peak stress in the ankle joint, resulting in suboptimal loading patterns and cartilage wear.

Conclusions

After trauma, the progression of OLTs is greatly influenced by the structural integrity of the subchondral bone plate and the distribution of thickness and stiffness of the ankle cartilage. Uneven talus bone density and cartilage thickness make the medial and lateral aspects of the ankle cartilage more susceptible for injury. In addition, high stress and repetitive motion from internal and external rotational transitions in the gait cycle, ankle sprains, ligament instability, and muscle weakness may alter the mechanical loading pattern of the ankle joint. Suboptimal load distribution may increase the size of the defect and concentrate pressure on its edges, potentially raising pressure in that area and accelerating the progression of OLTs. Future studies could explore how gait dynamics affect OLTs development, leading to a better understanding of its biomechanics and improving prevention and rehabilitation strategies.