MRI showing a tear in the Anterior Cruciate Ligament (ACL)
of the Knee. The ACL runs in a horizontal curve between
the femur and tibia bones
MRI scan showing a complete tear of
the Quardiceps tendon
Ligaments and Tendons, Sprains and Strains
Firstly, let’s make a simple distinction between ligaments and tendons and also between sprains and strains; in both cases many people tend to confuse the two or speak of them as if they are interchangeable. There are similarities in that both ligaments and tendons are made up of chains of fibrous cells called ‘collagens’ (or connective tissue) that are produced by proteins stored in the body. Ligaments and tendons have very different functions:-
Ligaments: Attach bone to bone and are made up of connective tissue, in this case the collagen fibres consist of interlocking or criss-cross bands. Ligaments serve to stabilise, strengthen and support the bone joints. A sprain is an injury, ranging from a simple stretch to a complete tear, of a ligament. (Image 1).
Tendons: Attach muscle to bone and occasionally structures such as the eyeball. Tendons are made up of parallel collagen fibres which provide more elasticity because a tendon allows movement of the muscle or structure. A strain is an injury, ranging from a simple stretch to a complete tear, in a tendon or in the muscle-tendon anatomy. (Image 2).
Ligament Injuries (Sprains)
Firstly, we will discuss ligament tears. There are four main ligaments that connect and stabilize the structure of the knee joint. These are as follows:-
- Anterior Cruciate Liagament (ACL). This is the major ligament of the knee and it has a very important stablilizing function. This ligament connects the femur to the tibia at the front or anterior of the knee and prevents the tibia from rotating or sliding forward during exercise.
- The posterior Cruciate ligament (PCL). This is the second major ligament of the knee and is situated directly behind the Anterior Cruciate Ligament (ACL) and connects the femur to the tibia at the back or posterior of the knee. This ligament serves to prevent the tibia rotating or sliding backwards during movement or exercise.
- The Medial Collateral Ligament (MCL). This is located on the inner side of the knee joint or medially and connects the femur to the fibula, the smaller bone of the lower leg. This ligament aids with side to side stability of the knee joint.
- The Lateral Collateral Ligament (LCL). This ligament also connects the femur to the fibula and is located on the outer side of the knee joint, or laterally.&
MRI scans have enabled ligament and tendon injuries to be much more easily diagnosed and treated. There is a general grading system for ligament damage as evaluated by MRI scan:-
- Grade I: A Mild sprain sometimes with a microscopic tear or minimal damage, such as stretching of the ligament fibres and no instability of the knee joint.
- Grade II: A Moderate Sprain with a partial tear of the ligament and some looseness or instability of the joint.
- Grade III: A Severe Sprain with a complete tear or rupture of the ligament and significant instability or buckling of the knee.
MRI scan of the knee showing
Anterior Cruciate Liagament (ACL) tear Grade II
MRI scan of the knee showing
Anterior Cruciate Liagament (ACL) tear Grade III
Tendon Injuries (Strains)
The two large muscle groups involved in the movement of the knee joint are the quadriceps, which are the muscles at the front of the thigh, and the hamstrings, the muscles at the back. These groups of muscle cross the kneecap (or patella) and are attached to the tibia by tendons. The two major tendons in the knee are:-
- The quadriceps tendon connects the quadriceps muscles to the patella or kneecap.
- The patellar tendon Confusingly the patellar ligament connects the patella to the tibia which makes it a ligament.The classifications of injury to the tendons are the same grading system as seen above for ligaments.
Treatment for Ligament and tendon injuries of the knee
In the case of soft tissue injuries such as sprains, strains and bruises the classic advice has always been, and often still is, R.I.C.E. This is an acronym to explain immediate action to take after an injury to a joint. (1) .
Rest: Take all weight off the damaged knee and rest
Ice: Apply an ice pack or bag of frozen peas to reduce inflammation
Compression: Gentle compression applied to the painful area.
Elevation: Lift the leg and place on a pillow or chair.
However, there is evidence supported by Dr. Mirkins, who invented the acronym R.I.C.E, that this recommended treatment for sports injuries may not be beneficial to healing(2)
In more serious injuries a splint or brace may be necessary to stabilise the joint whilst the ligaments or tendons heal. In the most severe cases surgery may be advisable.
- 1. ‘Sports Medicine Book’ by Dr. Gabes Mirkin 1978
- 2. http://drmirkin.com/fitness/why-ice-delays-recovery.html