Elbow and Forearm Wounds and Amputations
Normal Elbow and Forearm Anatomy
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
Wounds occurring in the forearm and elbow must be treated as an emergency because the risk of infection if left open increases about 7 hours after an injury has occurred. If a wound presents after this time, closure of the wound is not advised, even if cleaned out because of the higher risk of infection, especially if the wound results from an animal bite. When a wound is evaluated, the type of instrument or weapon making the wound must be inquired about. The depth of the wound and what type of bleeding was witnessed is also important since a partial vessel laceration will continue to bleed in spite of pressurebeing applied and an arterial laceration can spurt across the room indicating an artery has been cut which has higher pressure compared to a vein. When the last tetanus shot was given is important to know so a booster can be applied if necessary. When an open wound presents to an emergency room, the examination of active elbow, forearm and digital motion is evaluated to determine if a muscle, tendon or motor portion of a nerve has been cut. The sensation of the fingers is also checked to see if the nerves have been cut.
An amputation is the severing of a body part. Amputations are classified as partial and complete and if the amputation was a clean cut, a crushing amputation or an avulsion amputation where the amputated limb is pulled right off of the body. The avulsion amputation has the worse prognosis with the zone of injury being very wide. When an amputation occurs from the mid-palm to the level of the shoulder, it is a true emergency and must be replanted no more than 4-6 with warm ischemia but can be extended to 8 hours if it is cold ischemia (when the part is placed in an ice bath) after injury because the oxygen demands and metabolism of the muscles is high causing tissue death or necrosis if the blood supply is not restored within this time period. The necrotic changes that have taken place in the amputated part lacking oxygen will cause a dumping of this necrotic material into the bloodstream and cause a systemic collapse called Disseminated Intravascular Coagulation (DIC) that risks the persons’ life who is undergoing a replantation. If this occurs, the amputated part must be removed.
When amputation occurs, the amputated part must be immediately wrapped in gauze moistened in saline and placed in ice slush made by crushing ice that is placed in zip lock plastic bag and then put in a cooler while transporting it to ROC for replantation. Amputations from mid-palm to fingers have more time to be replanted because less muscle is found in this area. Time to successfully replant fingers can be as long as 15 hours post amputation because no muscle is present, but the sooner the replantation is done, the better.
Treatment
The treatment of an open wound begins with obtaining a clear history to determine the lacerating instrument, the position of the arm and hand during the laceration, the direction and depth of the laceration. The exam will confirm the injured tissue and the history will provide the direction the wound should be extended during surgical exploration. The cleaning of the wound, repair of muscle, artery and tendon is donewith the use of a microscope. The improved magnification allows for accurate approximation of the injured tissue. Tetanus is updated if it has been longer than 10 years and for a dirty wound, the tetanus must be no longer than five years current. This avoids the danger of acquiring gas gangrene, a deadly infection from the organism, Clostridium Perfringens. The use of oral antibiotics that cover skin flora, for one week after a repair is used as a prophylaxis to avoid the risk of infection. If the wound is a farm injury or dirty, Penicillin is also used to cover Clostridium Perfringens. When Wound was caused by a dog bite, the use of antibiotics that cover animal flora like pasturella Multicida, pseudomonas, staphylococcus and streptococcus must be used. Human bites as in a clenched fist injury also require antibiotics that cover Eikenella Corrodens like Augmentin. Special splints are applied after surgery to avoid certain movements that might damage a repair performed. The injured extremity must be elevated to at least heart level to avoid swelling of the limb which causes moderate pain, cuts off the blood supply and delays wound healing if allowed to occur.
The treatment of an amputation starts immediately after the amputation is sustained by placing the amputated part in a cold ice slush and transporting it to a replantation facility like ROC. Upon arriving at ROC’s emergency facility, the patient is prepared for surgery while the amputated part is taken to the operating room, cleaned and dissected out under a microscope, preparing it for replantation. Replantation is typically successful with amputations beginning at the base of the nail and more proximal amputations towards the shoulder. Successful replantations are related to the size of the arteries and veins which become too small to repair if it is beyond the nail base. During a replantation, the bone is fixed first, followed by the repair of the tendons, then the nerve, then whether you fix the arteries or veins after that is the surgeons’ choice since some prefer to fix the vein first to prevent excessive bleeding from the veins and others prefer fixing the arteries first to more easily visualize the veins.
The results of Replantations performed from the level of the forearm to the shoulder are more functional if it occurs in patients younger than 15 years of age (because of nerve regrowth potential), is a clean cut and the part is brought for replantation immediately. Partial amputations with the skin still attached should be left attached since valuable blood supply may provided by the retained tissue. If an amputation is the avulsion type which is a pulling injury, or a severe crush injury, the likelihood of a successful replantation is significantly less. Regardless of the type of amputation, it is advisable to bring in the amputated part immediately for the surgeon to assess the replantation likelihood of success or touse the tissue from the amputated limb as donor tissue to treat the wound base where the amputation occurred.