Forearm Compartment Syndrome
Normal Elbow and Forearm Anatomy
The elbow and forearm form a functional unit whose primary role is to accurately position the hand in space. The elbow has a long lever arm and moves the forearm and hand 130 degrees covering much of the functional space used in our activities of daily living and in this sense the elbow is considered the most important single joint of the upper limb, second only to the thumb carpometacarpal joint. The functional space is defined as the space directly in front of a person’s body that lies below eye level and above the belly button. Because the elbow joint covers the entire functional space by virtue of its arc of motion, there has never been a satisfactory position to fuse an elbow joint if it were ever destroyed by injury or disease.
The elbow anatomy is best understood by thinking of it in three layers. The first layer is the bony layer, the second layer is the ligament layer and the third layer is the muscular layer within which the arteries and nerves travel.
Elbow & Forearm Elbow Joint Front View & Side View
The first layer is comprised of three bones that unite to form the elbow joint. The elbow joint is located at the lower end of the arm bone (humerus), and the proximal end (towards the shoulder) of the radius and ulna which are the two forearm bones. These three bones allow the elbow to bend (Flex) and straighten (Extend) in a hinged type motion and the forearm to rotate the hand in a palm up (supination) and palm down position (pronation). The joint surfaces of the elbow are covered by hyaline cartilage which forms a cushioned layer that allows for smooth gliding and painless elbow motion.
Elbow & Forearm Ligament LayerElbow Joint Ligament Layer
Lateral Elbow Ligament View Medial Elbow Ligament View
The second layer in the elbow and forearm is the capsular ligament layer made up of collagen tissue. The ligament layer in the forearm is called the interosseous membrane. The collagen tissue forming the elbow joint capsule is normally very thin except on the inside (medial) and outside (Lateral) sides of the elbow where thickenings in the collagen substance form the ligaments of the elbow. These ligaments provide passive stability to the elbow joint keeping the humerus, radius and ulna together, allowing them to function as a unit.
Foerarm Flexor CompartmentForearm Flexor & Mobile Wad Compartments
Elbow Flexor Muscles Elbow Extensor Muscles
The third layer of the elbow and forearm is the muscle layer and is formed by the various muscle groups that pass through the elbow and forearm either originating (beginning) or ending in the elbow and forearm. The muscles of the arm that pass through the elbow include the triceps muscle in the back of the arm and the brachialis and biceps muscles in the front of the arm. The forearm muscles that cross the elbow joint are divided into three compartments with each compartment containing several muscles that work to move the elbow, forearm, wrist and hand in specific directions. The three compartments are: 1. the extensor compartment 2. the flexor compartment and 3. the mobile wad of Henry compartment. The median, ulnar, and radial nerves pass through the elbow and forearm within the muscle layers and innervate the muscles within these compartments as well as, the muscles of the hand.
Pathology
Compartment syndrome in all extremities is an orthopedic emergency. Forearm compartment syndrome occurs as a result of a major crushing injury, burn or injection injury to the forearm causing the pressure within the three forearm compartmentsto exceed the ability of the blood pressure generated by the heart’s pumping action to supply sufficient blood flow to the elbow and forearm. When this occurs, the muscles and nerves within the compartment are at risk of dying with little or no chance of recovery. A fracture may or may not accompany a forearm compartment syndrome and in most cases a wound is not present which potentially can indirectly decompress the forearm compartments preventing the pressure buildup.
Patients with compartment syndrome complain of increasing pain that is out of proportion to the injury and continues to increase requiring an increase in the demand for pain medication. This isa dangerous situation which ignores the increasing pressure in the compartments which if ignored will result in tissue death and potential loss of the limb. Other symptoms of compartment syndrome include numbness, tingling, or no symptoms at all if the compartment syndrome has gone too long and the nerves’ protective functions have been suppressed. Tissue death then follows. Signs of compartment syndrome include a tense forearm, pain with straightening the fingers or there may be a loss of sensation in the forearm and hand accompanied by a cool sensation of the skin, changes in skin color, with final loss of pulses in the wrist, which is a final sign that precedes tissue death. Because the signs and symptoms can be variable, physicians must have a high index of suspicion of this condition recognizing that more pain medication is not the answer. This is why increasing pain after an injury requires direct clinical evaluation by your doctor and is not addressed over the phone.
Treatment
If an elbow, forearm and hand compartment syndrome is diagnosed, it must be treated within 6 hours of occurrence. Diagnosis is done clinically, and with the use of compartment pressure measurement instruments. If there is conflicting findings between the clinical presentation and the measurement obtained, it is prudent to follow the clinical findings to avoid the catastrophe of tissue death if the measuring device is wrong. The treatment of a compartment syndrome consists of releasing the connective tissue (fascia) that surrounds and separates each compartment. The release relieves the pressure within the compartment and allows the muscles and nerves within the compartment to receive their required blood supply. The surgical wounds are often not sutured back immediately to allow for the skin and soft tissue to accommodate any swelling that has occurred. The wound either undergoes a delayed closure or is skin grafted to accommodate the increased swelling. If the wounds cannot be closed because of skin tightness, another technique is the use of a vacuum-assisted wound closure device.