Pathology
Open wrist wounds indicate:
- Skin is breached
- The wound is contaminated
- Exposure with potential injury of deeper structures is a possibility
Depending on the mechanism of injury, the wound can be:
- Sharp lacerations from a knife or saw injuries
- A crushing injury
- An avulsion injury
- Any combination of the above types of injuries
All wounds demand immediate assessment and treatment by a specialist to avoid the risk of injection and confirm the exact tissue injured for a treatment plan to be instituted timely. The degree of contamination and the extent and severity of the injury must be documented and addressed promptly in an emergency approach, usually the same day of injury.
Open wounds are classified as superficial when they remain above the level of the deep which covers the tendons, muscles, major nerves and arteries in the wrist. A superficial wound can involve the skin, subcutaneous tissue (fat) and the superficial vessels or nerves.
Treatment
Treatment of superficial wounds requires urgent exploration, debridement (surgical cleaning) that is deeper and more thorough than a regular wash out in the emergency room as well as repairing any major cutaneous nerves running superficially in the subcutaneous tissue. A superficial wound and laceration can be cleaned and sutured after a hand specialist has been made aware of the extent of the injury and an appropriate treatment plan formulated.
Tetanus is updated if it has been longer than 10 years since receiving a tetanus shot or if the wound is dirty and if it has been five years since receiving a tetanus shot. This is to avoid the risk of acquiring deadly gas gangrene. The use of oral antibiotics for one week after a repair is commonly used as a prophylaxis to avoid the risk of infection.
Special splints are applied after the procedure for comfort and protection. The injured extremity must be elevated to at least heart level to avoid swelling. Swelling can cause moderate pain, cut off the blood supply and delay wound healing.
A deep open wound can involve the above mentioned structures as well as a number of deep tendons, muscles, nerves and arteries.
The degree of contamination, the extent and severity of the injury will determine if surgery is done the night of injury or within one week of injury.
Candidates of Immediate Surgery
- Severe contamination
- Uncontrollable bleeding
- Presence of a foreign body:
- Glass, metal fragments, etc.
- A pulseless extremity
- An open fracture or open joint
The key in dealing with injuries involving multiple structures is thorough knowledge of the hand anatomy and microsurgical techniques. An orthopedic surgeon or plastic surgeon that has not done a fellowship in the area of hand surgery is not qualified to repair these complex injuries. These injuries require a specialty trained hand surgeon.
Tendons are the continuation of muscles responsible for joint mobility and strength. When a laceration involves more than 30 -50% of the tendon diameter, there is significant loss of tension resistance and a risk of tendon triggering or a delayed complete rupture. It is important to accurately explore the wound to determine the severity and types of tissues injured.
Tendon repairs take approximately 6 weeks to heal to about 80 % of their original strength and 10 weeks to 95 % of their original strength at final healing.
There are several techniques for tendon repairs using different types of sutures and suturing techniques. The technique used will determine the level of initial strength the repair possesses as well as the amount of safe active or passive motion that can be done while avoiding tendon ruptures during healing time.
Tendons lacerated about the wrist should be repaired with sufficiently strong techniques to permit early mobilization.
When there is tissue loss creating a large defect on the tendon, tendon grafts or tendon transfers will be required to regain pre-injury function. A repaired or reconstructed tendon requires initial protection in a splint for the first four to six weeks.
Hand Therapy Program for Tendon Repair
Focus is on techniques to:
- Control pain
- Decrease swelling/edema
- Initiate and increase protected tendon gliding,
- Advancing to differential tissue plane gliding that avoids scarring which limits motion and decreases the final functional outcome
Nerves injuries are classified on a spectrum according to severity. There are 5 Grades, known as Sunderland Grades I through V.
- Grade I and II are the most benign and can recover function within weeks without surgery.
- Grade III has variable outcomes requiring careful evaluation if surgery is to be performed.
- Grades IV and V represent a severe injury demanding surgical intervention for recovery of functions.
Once a nerve is repaired, the axon must re-grow from the point of injury occurrence to the end organ it innervates.
If the final target organ is a muscle, there are only about six months available for the nerve to reach the muscle and allow it to remain viable. If regrowth does not happen within that time frame, the muscle dies and function will never recover for those muscles.
Sensory nerves can have a more prolonged time frame to re-innervate their sensory end organs, believed to be as long as several years.
Vessels
Vessels are the pipes through which blood flows, supplying oxygen and other nutrients to the multiple tissues in the body. Tissue survival depends directly on sufficient blood supply provided by arteries.
Veins are vessels bringing blood back to the heart. At wrist level, there are two main arteries supplying most of the blood in the hand. Two main venous systems exist, but when injured or occluded, new veins can grow, as long as the hand has at least one sufficient vein for outflow. If either the radial or ulnar artery is injured, the intact artery can maintain sufficient blood supply to keep the hand tissues alive.
When the two main arteries of the wrist and hand have been transected, it is imperative to re-establish blood flow in a timely fashion to prevent tissue death.
Nerve and Vessel (arteries and veins) lacerations about the wrist require microsurgical techniques for repair.
Microsurgical techniques involve the use of magnification (loupes/ microscope), special fine instruments, called jeweler instruments, are needed for the handling of the tissue and very fine sutures not visible to the naked eye.
Microsurgical techniques require specialized training in hand and microsurgery.
A nerve repair takes approximately 2- 4 weeks for the new axons (nerve fibers) to cross the line of repair. New axons advance at a pace of approximately 1 mm per day. Therefore, if a nerve laceration occurred at 10 cm proximal to the final target organ, it will take approximately 100 days plus 30 more days to cross the repair site or 130 days to reach the final target organ.
The outcome for nerve repair is influenced by technical factors depending on surgeon competence, patient age (age less than 35 years has a better prognosis) and general health status.
The average percentage of success in small vessel repair is 95- 97 %.
Patients with a vessel repaired through microsurgical techniques may have to remain in the hospital for 5 days on blood thinners, appropriate temperature control, extremity elevation, fluid maintenance, immobilization, and the avoidance of caffeine products and chocolates to increase the success of the repair.
Therapy geared towards nerve repairs will include various modalities such as:
- Nerve glide exercises
- Desensitization
- Neuromuscular re-education
- Bio-feedback
- Functional electric stimulation
- Sensory re-education
- Strengthening and splinting as indicated