Ligament tears and Elbow Fractures
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
Fractures about the elbow are the result of high energy injuries. When an injury involves a joint, either the bone breaks, the ligament tears, the joint dislocates or all three things occur. The exact injury pattern is dependent on the amount of the force, the direction of the force and the position of the upper limb at the point of impact.
Ligament tears occur when the elbow is excessively bent outward (varus) which tears the outside ligaments called the lateral collateral ligament complex or if the elbow is excessively bent inward (valgus) tearing the medial collateral ligament complex. Elbow ligament tears usually occur when someone slips and falls forward with the body weight and the momentum being sustained by the elbow. Usually the ligaments on the outside of the elbow tear first followed by the force traveling inward on the front and back of the elbow until complete ligament tearing occurs culminating in an elbow dislocation. When sufficient ligament tearing occurs, and the elbow does not completely dislocate, the elbow experiences signs of instability or slipping out of the joint which includes a clicking feeling, apprehension or fear of an imminent dislocation and a locking sensation when the bone edges wedge on each other.
A simple dislocation without an associated fracture is reduced (put back in place), rested for a couple of weeks and controlled early motion is then begun with a removable splint placed about 30 degrees of elbow flexion, which provides protection from a recurrent dislocation. This treatment works well unless a high performance athlete like a baseball player that must throw a baseball or other aggressive overhead activity that places excessive stress on the elbow inside ligaments. In this instance, a ligament reconstruction may be required.
Normal Elbow Supracondylar Supracondylar Low Transcondylar
Intercondylar Fracture Fracture Fracture
Elbow Fracture Malunion(Healed poor position)Elbow Fracture Nonunion(Not healed)
A fall can also create an elbow fracture, alone or accompany an elbow ligament injury. The worst of these combined ligament and elbow bone injuries is called the terrible triad when the all elbow ligaments are all torn, the radial head is broken and part of the ulnar bone called the coronoid process is broken resulting in the elbow losing all of the supporting structures keepingthe elbow in place. The reconstruction of this fracture pattern requires an experienced elbow surgeon that can address the combination of injuries. Elbow fractures can also affect the bones individually. A fracture of the elbow joint can involve the lower end of the arm bone (humerus) or proximal part of the forearm bones named the radius and ulna.
Fracture types are classified according to the skin being breached called an open fracture, which is treatedas an emergency to avoid infection. Other considerations in making treatment decisions include the bone quality, pattern of the fracture, separation and angulation of the fracture fragments, extension into the joint surface and the amount of fragmentation called comminution that has occurred. Fractures that extend into the joint thatare not fixed properly will develop post-traumatic arthritis. Fractures about the elbow that are not treated timely will result in a stiff elbow, lack of fracture healing called a nonunion or healing of the fracture in the wrong position called a malunion.
Treatment
The treatment of an elbow fracture when displaced, angulated,fragmented or one having poor bone quality making it unstable is always with surgery in an adult. Children are treated without surgery in most cases because their bones heal quicker, have less probability of developing stiffjoints after immobilization, and have a thicker surrounding layer of perisosteum (lines the bone surface and produces bone) which allows for the manipulation reducing the fragments back in place, easier to accomplish. The only time that surgery is required for a child is when the fracture is an open injury, there is extension into the joint with displacement present that cannot be put back by closed manipulation or when there is a vascular (Blood supply) compromise. The best options for treating elbow fractures are through the use of plates and screws. There are different types of plate and screw configurations and the evolution of these plate implants include pre-contoured plates simulating the normal anatomic curvature of the bone, special screws that not only capture the bone but also lock to the plate thereby enhancing the fixation stability. When the fracture is a very low supracondylar fracture (shown above) and the quality of the bone is poor or when there is severe fragmentation in an elderly patient with poor bone quality, an immediate elbow replacement is oftentimes the best option instead of an open reduction and internal fixation (ORIF) with plates and screws.