When a tendon moves, it transmits force from a muscle to a bone, enabling joint movement. However, if a tendon moves out of place, a condition called subluxation can occur.
Here's a breakdown of what happens during normal tendon movement and what can happen when it's abnormal:
Normal Tendon Movement:
- Force Transmission: Tendons, strong cords of connective tissue, primarily facilitate movement by transmitting the force generated by muscles to the bones.
- Joint Articulation: This force pulls on the bone, causing it to move at the joint. The precise movement depends on the muscle, the tendon's attachment point, and the joint's structure.
- Smooth Gliding: Tendons often glide smoothly within tendon sheaths, which are structures that help guide the tendon and reduce friction during movement.
Abnormal Tendon Movement (Subluxation):
- Definition: Tendon subluxation happens when a tendon slips out of its normal position or groove.
- Causes: This can occur due to:
- Trauma (e.g., a sudden injury or dislocation)
- Anatomical abnormalities (e.g., shallow grooves in the bone where the tendon sits)
- Inflammation or swelling around the tendon, making it more likely to slip
- Symptoms: Symptoms can vary depending on the affected tendon, but commonly include:
- A popping or snapping sensation at the joint when the tendon moves out of place.
- Pain in the affected joint. The pain can be sharp and immediate or a dull ache.
- Weakness in the affected joint or muscle, making it difficult to perform certain movements.
- The sensation of the tendon "catching" or "locking" during movement.
- Sometimes, the pain and instability are intermittent.
- Example: A common example is peroneal tendon subluxation at the ankle. This occurs when the peroneal tendons, which run along the outside of the ankle, slip out of their groove behind the lateral malleolus (the bony bump on the outside of your ankle).
In summary, while tendons are meant to move in a controlled manner to facilitate joint motion, a displaced tendon (subluxation) can lead to pain, instability, and compromised function.
