Flexor and extensor tendons to the hand and wrist are the structures that attach our muscles of the forearm to the bones and allow our muscles to move the joints. As one can imagine, the tendon structures to the hand, particularly within the fingers, are incredibly elaborate. This sophisticated anatomy of the tendons provides us with the abilities to perform even the finest of skills such as playing a musical instrument. Given the functional importance of our hands for everyday activities of life, it is essential to seek medical evaluation for any suspected tendon injury. If a tendon injury is left untreated or not treated in a timely manner, particularly for the fingers, irreversible damage or significant loss of function may result.
Tendon lacerations are commonly associated with any penetrating trauma, such as glass or knife cuts, to the fingers, hand, or wrist. Cuts to the palm side of the forearm, wrist, hand, or finger involve the flexor tendon system, and cuts to the back-side or top side involve the extensor tendon system. Based on the superficial location of some tendons just under the skin, even a simple or subtle appearing laceration to the hand from a sharp object can result in a partial cut or complete cut of a tendon. Additionally, based on the highly structured anatomy of the hand and wrist, nerves and blood vessels can often be cut as well. Cut tendons typically require surgery for repair since the two ends of the cut tendon are incapable of healing together without surgery.
Tendon injuries can also occur as a rupture or tear. Ruptured tendons are most commonly caused by non-penetrating forceful trauma which pulls the tendon off of bone or tears the tendon away from bone. Although much less common, tendon ruptures can be associated with degenerative or rheumatoid arthritis of the wrist. Bone spurs associated with arthritis of the wrist can cause frictional tearing of flexor or extensor tendons to the fingers like a rope fraying from constantly rubbing against a rough surface. Similarly, flexor or extensor tendons to the fingers and the thumb which pass along the wrist can rupture spontaneously from continual rubbing over metal hardware used to treat fractured bones such as distal radius fractures if the hardware is excessively prominent. More common tendon ruptures of the finger from injury are best known as a "mallet finger" or a "jersey finger." A mallet finger can happen even after a minor jam of the fingertip in which the extensor tendon to the last joint of the finger pops off. A flexor tendon rupture of the finger (most commonly the ring finger) is best known as a "jersey finger" since it is most commonly associated with a football injury during "shirt" tackling when the finger is forcefully extended from an actively flexed position. Other common tendon ruptures, involving the distal biceps tendon or triceps tendon, can occur at the elbow. Typically seen in men over 40 years of age, ruptures of biceps or triceps tendons are often related to an abrupt overload of a degenerated tendon such as trying to lift an excessive amount of weight.
Cut ends of a tendon must be brought back together to allow for healing from cells inside of the tendon and from tissue outside of the tendon. If a gap (even small) persists between the tendon ends, healing of the tendon is not possible. When a tendon ruptures or is cut, the end of the ruptured tendon or the ends of the cut tendon separate and retract like a spring or rubber band under tension. With the exception of a few tendon injuries (e.g. mallet finger), surgery is necessary to retrieve and reattach the ruptured tendon to bone (e.g. distal biceps tendon or flexor tendon rupture) or to repair the separated ends of the cut tendon (e.g. finger flexor or extensor tendon laceration) to promote healing. It should be understood that timing from injury can be of critical importance for successful treatment. Delays of even just a few weeks in seeking medical treatment for some tendon injuries, particularly flexor tendons of the fingers, can significantly compromise the ability to repair the tendon directly, negatively impact results, or can even prevent any direct repair due to excessive scarring and shortening of the muscle and tendon. Consequently, reconstruction, if even possible, with tendon grafting (using an expendable piece of tendon from another site) or tendon transfer (transferring a tendon from one location to another) may be necessary to restore function.
Cuts involving extensor tendons over the finger, hand, or wrist need stitches for repair, unless it is partial and small. A tear or rupture of a finger extensor tendon from a jamming injury is often treated with a splint. Splints for the finger keep the ruptured tendon from pulling away from bone and are worn full time until the tendon is fully healed. If the rupture is left untreated or inadequately splinted, significant finger deformities and contractures can develop. Through the guidance of your physician, most splints are fabricated and fitted by a Certified Hand Therapist. With some exceptions, the surgical repair of the extensor tendon is typically treated with a limited-movement program using specialized splints made by the Hand Therapist for about 4 to 6 weeks (for example see figure). Grip strengthening and progression of range of motion then follow. Expected return to full activities is about 10 to 12 weeks after surgery (see example images below).
Cuts involving flexor tendons of the finger, hand, or wrist need to be surgically repaired. Your physician will advise you on the importance of timing for surgery depending on the location of the flexor tendon laceration or rupture. In the finger, the flexor tendon system is composed of an elaborate assortment of fibrous bands called flexor pulleys. Preservation of certain biomechanically important pulleys is a must which makes surgical repair for both cut and ruptured flexor tendons much more difficult since these tendon repairs are done with very little space between the tendon and pulleys. Additionally, delays in treatment only further complicate the surgery due to early scar formation within the flexor pulleys and shortening of the muscle and tendon. Nearby nerves or blood vessels may also need to be repaired using microsurgical techniques. Depending on the type of injury, the surgical repair of the flexor tendon(s) may either be protected from movement or started on a very specific limited-motion program for 5 to 6 weeks using specialized splints made by a Hand Therapist (for example see figure). If finger and wrist motion after surgery is unprotected, the surgically repaired tendon can pull apart until adequate healing has occurred. A controlled protocol is instructed by your surgeon and Hand Therapist that allows for step-by-step progression of motion while the tendon is healing. The important phases of healing take place during the first three months after repair.
Scarring of the tendon repair, particularly after flexor tendon repairs within the pulley system of the finger (also known as "no man's land" due to problems of scarring) is a normal expectation of the healing process. The degree of scarring, however, significantly affects the outcome of repair. In some cases, the scarring or tendon adhesions can make bending and straightening the finger very difficult. The therapy protocols in coordination with your Hand Therapist are done to minimize the potential complications of scarring and help promote scar remodeling as significant improvements can continue over months and possibly even up to a year. If hand therapy fails to improve motion, surgery to release scar tissue and adhesions (called tenolysis) around the tendon may be required to improve functional motion. Despite excellent results, it should be understood that full and normal movement of the injured area may not return even after surgical repair, especially in most cases of flexor tendon injuries involving the finger.
A specific tendon rehabilitation protocol combining protection and limited motion of joints will be initiated after surgery with a Certified Hand Therapist (CHT), who is a therapist that specializes in therapy for rehabilitation of the hand. Working closely with your Hand Therapist and Hand Surgeon after surgery is of great importance to help maximize your outcome. Hand therapy ensures your understanding of daily home exercises and necessary guidelines during recovery. In addition to regaining motion of the finger after a tendon injury, hand therapy promotes softening of scars and building of grip strength, and if an associated nerve injury occurred, improves sensory re-education.
Based on the complexity of tendon repairs and possible need for microsurgical repairs of associated injuries to the nerves or blood vessels, tendon injuries are best treated by a surgeon with fellowship training in Hand Surgery. Dr. Mark A. Katz has fellowship training in Hand Surgery and has the expertise and experience to care for your tendon injury. Dr. Katz was previously involved in the training of Hand Surgery Fellows, physicians who seek additional training in hand, upper extremity, and microvascular surgery, and has lectured to surgical residents and fellows on the treatment and techniques of flexor and extensor tendon injuries.