Anatomy of the Collateral Ligaments of the Fingers
The distal, middle and proximal joints of the fingers each have two collateral ligaments holding them together. The one on the medial side is called the medial (or ulnar) collateral ligament and the one on the lateral side is called the lateral (or radial) collateral ligament. Their primary function is to limit lateral and medial motion and keep the joint in alignment so that it functions as a hinge joint, which only moves in flexion and extension.
These ligaments function similarly to the collateral ligaments of the knee. When ligaments in the body are loose and there is too much play in the joint, injury to that joint and its ligaments are more probable. Luckily, the collateral ligaments of the proximal joints of the fingers are less often injured. Unfortunately, however, when they are injured, they are more difficult to treat with hands-on techniques because they are less accessible.
Collateral Ligament Sprains
When the collateral ligaments are sprained, the pain is often found or felt on either the varus or valgus stress test. The ligament is right near the surface and easy to palpate, and damage or injury may cause the joint to swell once the collateral ligament sprain is properly treated, the swelling will dissipate. No injection therapy is needed unless the swelling persists after the collateral ligament heals.
Following are tests that will help you assess each collateral ligament of the finger.
1.Passive Side Flexion of Each Finger Joint (Valgus and Varus)
Begin by testing the medial and lateral collateral ligaments of the two distal joints of the fingers with valgus and varus stresses. Starting in the anatomical position, the lateral collateral ligaments of the index finger are the ones closest to the thumb. The medial collateral ligaments are the ones closest to the middle finger. Check all finger ligaments the same way, and consider practicing on your own index finger as needed. The ligaments that get injured with some frequency are the ones at the distal and middle joints of the fingers—the Distal Interphalangeal (DIP) joints and Proximal Interphalangeal (PIP) joints.
2.Distal Interphalangeal Ligament Valgus Stress Start by testing the medial collateral ligament of the most distal joint of the index finger, the one closest to your middle finger. Place your index finger on the medial tip of the index finger and place the tip of your thumb on the lateral aspect of the distal joint. Now apply pressure with the thumb pushing the joint toward the middle finger while applying pressure in the opposite direction with your index finger, which will place stress on the medial collateral ligament of the distal joint of the index finger.
3.Distal Interphalangeal Ligament Varus Stress To stress the lateral collateral ligament of the distal joint simply reverse your hand position and exert pressure in the opposite direction. If the test was painful, palpate the ligament on either the medial or lateral side and then palpate the same ligament on the client’s other hand, or on their other fingers provided they are healthy. The healthy ligaments will just feel pressure, while the injured ligament will be painful or uncomfortable.
4.Proximal Interphalangeal or Middle Ligament Valgus Stress Then, test the medial collateral ligament of the middle or PIP joint of the index finger. Place your thumb on the lateral aspect of the middle joint of the index finger and your index finger on the medial aspect of the distal joint. Now apply pressure with both fingers in opposite directions. This will place stress on the medial collateral ligament of the middle joint of the index finger. If the test is painful, palpate the ligament on medial or thumb-side and then palpate the same ligament on the client’s other hand, or on their other fingers provided they are healthy.
5.Proximal Interphalangeal or Middle Ligament Varus Stress To stress the lateral collateral ligament of the middle or PIP joint just reverse your hand position and exert pressure in the opposite direction. If the test is painful, palpate the ligament on lateral side and then palpate the same ligament on the client’s other hand, or on their other fingers provided they are healthy. The healthy ligaments will just feel pressure, while the injured ligament is painful or at least uncomfortable.
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