Ligaments connect bone to bone, and tendons connect muscle to bone.
Tendons
Tendons connect muscle to bone. They transmit force to move joints. Example: the Achilles tendon.
Ligaments
Ligaments connect bone to bone and stabilize joints. Example: the anterior cruciate ligament (ACL).
Both
Made of collagen, they have limited blood supply, so they heal slowly.
Injuries
- Sprain: ligament injury.
- Strain: muscle or tendon injury.
- Tendinitis: inflammation of a tendon.
Treatment
Rest, ice, compression, elevation, physical therapy and sometimes surgery.
Strength
Tendons can handle loads of several times body weight.
Remember
Ligament = bone to bone (both have an L and B).
Tendons in more detail
Tendons connect muscle to bone. They are made of tough, parallel collagen fibers and can carry large loads. The Achilles tendon, the thickest in the body, can handle forces up to about 8 times body weight when running. Tendons have a poor blood supply, so they heal slowly.
Ligaments in more detail
Ligaments connect bone to bone and stabilize joints. They are made of collagen and some elastic fibers, and are slightly more elastic than tendons. Key ligaments include the anterior cruciate ligament (ACL) in the knee, the medial collateral ligament, and the ankle ligaments that are most often sprained. Ligaments limit joint movement to stay in a safe range.
Key differences
- Tendon: muscle to bone. Ligament: bone to bone.
- Tendons transmit force to move the joint. Ligaments hold the joint stable.
- Tendon injuries are called strains or tendinopathy. Ligament injuries are called sprains.
Injuries
- Tendinitis or tendinopathy: overuse, common in the Achilles, rotator cuff, elbow (tennis or golfer’s elbow) and knee (jumper’s knee).
- Tendon rupture: sudden and often with a pop, such as an Achilles rupture.
- Ligament sprain: graded I (stretched), II (partial tear) and III (complete tear).
- ACL tear: common in sports with pivoting. About 200,000 ACL injuries occur in the US each year.
Treatment
Treatment for mild injuries follows rest, ice, compression and elevation, and then gradual loading. Physical therapy builds strength and movement. NSAIDs help with pain. Complete tears, such as the ACL or an Achilles rupture, often need surgery, though some are treated without it. Injections of steroids can weaken tendons, so they are used with care.
Recovery time
Mild sprains heal in 2 to 6 weeks. A grade III ligament tear may take 6 to 12 months after surgery. Tendon repairs usually need 3 to 6 months, and tendinopathy can take 3 to 6 months of exercises.
Prevention
- Warm up before exercise.
- Build strength around joints.
- Increase training gradually, no more than about 10% a week.
- Use good footwear and technique.
Memory tip
Tendons attach muscle to bone, and ligaments attach bone to bone. The “L” in ligament can stand for “link” between bones.
Injury statistics and recovery windows
ACL tears, a ligament injury, affect an estimated 200,000 Americans a year, and surgery reconstructs the ligament with a graft taken from the patient’s own tendon in many cases. Recovery from an ACL reconstruction takes 6 to 12 months before return to sport. Achilles tendon ruptures often need 6 months or more of rehabilitation. Ankle sprains are ligament injuries, graded 1 to 3, and Grade 1 sprains heal in 1 to 3 weeks. Tendons connect muscle to bone and ligaments connect bone to bone. Both have limited blood supply, so they heal more slowly than muscle. Eccentric strengthening is a standard approach in tendinopathy rehabilitation.
Based on data from the American Academy of Orthopaedic Surgeons
