Hand and Upper Extremity Injuries – Diagnosis and Treatment
January 18, 2023 - read ≈ 19 min
This chapter on hand trauma will focus on conditions encountered during war including trauma, burns, and infections. Primary discussions will center on diagnosis, triage, and treatment. A primer on hand anatomy is essential before undertaking any diagnostic or treatment discussion. General principles for treatment of hand injuries will be outlined, followed by specific conditions.
A Primer on Applied Hand Anatomy
An understanding of hand anatomy will allow the clinician to arrive at an accurate diagnosis very quickly, relying primarily on the physical examination. In the great majority of cases, examination distal to the injury provides a convincing and definitive diagnosis of the injured structures. Probing or looking inside an open, bleeding wound in the hand will rarely be more accurate.
Topographical anatomy of the hand is important for communication. One typically refers to the dorsum (back) and volar (palm) aspects of the hand. Distal and proximal refer to relative position. Ulnar and radial are preferred to medial and lateral because of forearm rotation.
Phalanges and metacarpals form the skeletal framework of the hand and give it shape. Each of these elements is attached to its neighbor at the intervening joint with soft tissue structures that provide stability, yet allow motion (usually) in one plane. While injury to the skeletal structures is easily diagnosed with a plain radiograph, evaluation of the soft tissue structures of the joint requires a more careful physical examination. A joint can be thought of as a box: on top is the dorsal capsule; on each side are the collateral ligaments; and on bottom (palmar) is the volar plate (Figure 1).
The flexor tendons lie on the palmar side of the hand, originating from muscles in the forearm, entering the hand in the carpal tunnel, traversing through a tight fibro-osseous sheath and pulley system, before arriving at the middle (superficial flexors) or distal phalanges (deep flexors). Extension of the digits is mediated by the interplay of intrinsic and extrinsic muscle-tendon units. These are primarily positional tendons, as such, any small perturbation in their length can cause a surprisingly large range of motion difference.
The superficial flexors are tested by blocking the other digits and asking the patient to flex. The deep flexors are tested by blocking the middle phalanx and asking the patient to flex.
The three main nerves to the hand control motor and sensory function (Figures 2 and 3). The ulnar nerve controls the majority of intrinsic muscles while providing sensation to the small finger and ulnar half of the ring finger, as well as the dorsal and ulnar hand.
The median nerve motors the intrinsic thumb muscles and provides sensation to the thumb, index, middle, and radial half of the ring finger. The radial nerves role is to provide sensation to the dorsal and radial hand.
The moving two point discrimination test is the best way to assess sensory deficits after trauma. The examiner can gently move the two prongs of a paperclip on the radial or ulnar pulp of the finger. Normal is between 3-5 mm and any value above 8 mm is considered abnormal.
Blood inflow to the hand is provided by the radial and ulnar arteries (Figure 3). These two meet in the palm and form the deep and superficial arches. The ulnar artery is usually dominant. Assessing for an arterial injury is often challenging if there is no ongoing bleeding. If one of these vessels is injured, the other will usually provide enough blood supply to the hand through the arches. To test for patency of a vessel, the clinician should block the other vessel at the wrist and assess a doppler signal in the arch or perform a traditional Allen test.
Principles of Hand Surgery
The first principle is already discussed: diagnose injury by examining distal to site of injury. When considering treatment/operation, the two other principles are obtaining adequate anesthesia and using a tourniquet.
Providing complete anesthesia in the hand is possible with 4 injections of local anesthesia. Anesthesia is critical because a patient in pain is likely to move and compromise any repair. Approximately 5 mL of local anesthesia (ideally a 50/50 mix of short and long acting agents) can be injected to block the median, ulnar (main), dorsal ulnar sensory, and dorsal radial sensory nerves. The median nerve is blocked by using a short 25 gauge needle to enter the distal wrist flexion crease, directed radially 45 degrees and palmarly 45 degrees, ulnar to the palmaris longus tendon.
The ulnar nerve is blocked by injecting just dorsal to the flexor carpi ulnaris tendon with the needle directed radially. The ulnar nerve is ulnar to the ulnar artery, a relationship that can be remembered if compared to the orientation of the median nerve to the radial artery (ulnar). The sensory branch of the ulnar nerve is blocked on the dorsum of the wrist by making a skin wheel just distal to the ulnar styloid. The radial sensory nerve is blocked by injecting down to the radius about 3 fingerbreadths proximal to the radial styloid and withdrawing the needle while instilling the anesthesia.
A properly fitted and inflated tourniquet provides a clean operative field and maximum visibility with minimal morbidity. Ideally, the tourniquet should be placed high on the arm and inflated to 250 mmHg. If only an Esmarch bandage is available, it can be used to exsanguinate the arm and then wrapped over itself at the arm level to function as a tourniquet. Ensure that the area of compression is wide (about 6 cm) to avoid significant pressure on a narrow area which can result in nerve injury. If a prolonged tourniquet run is anticipated, the limb should be allowed to perfuse 30 minutes for each 2 hours of tourniquet time. A tourniquet should not be used for more than 30 minutes in an awake patient because it is uncomfortable. Lastly, avoid using a tourniquet (especially a belt) on a bleeding extremity – almost always bleeding can be controlled with direct pressure without causing ischemia to the rest of the limb.
Three factors influence infections:
- host factors
- inoculum size
- infective organism
Host factors include underlying medical conditions such as diabetes, immunosuppression or wounds with necrotic tissue. Inoculum size refers to the amount of tissue contamination with bacteria. The last factor, the organism, indicates that some organisms may be more virulent than others. Considering these three elements helps the practitioner create a definitive plan to treat the patient, whether that means operating, changing antibiotics, or addressing host factors.
Most hand infections are caused by skin flora such as staphylococcus aureus. In war settings, the primary cause is trauma which results in devitalized tissue, a perfect medium for bacterial proliferation. The hand contains multiple mobile structures and spaces. The initial bacterial inoculum may migrate from one site to another where local defenses are weak (e.g. potential space with less blood supply). As an example, a small bacterial seeding of the flexor tendon sheath may develop into a significant pyogenic infection as the immune system cannot easily penetrate this avascular area where bacteria can multiply rampant in a nutrient-rich space. The infection then spreads easily along the finger and palm in this potential space.
The mainstay treatment of pyogenic hand infections is surgical drainage and debridement. Host factors should be optimized (e.g. blood sugar control in diabetics) and antibiotics tailored (based on culture results). The wound should stay open to allow drainage: a wick or penrose drain is adequate for small wounds that drain abscesses.
Paronychia: Pain, swelling and redness of the paronychium is the classic sign of this condition. A small stab incision is usually sufficient to drain the infection. A small wick can be placed in the short term and/or the patient asked to soak the finger in warm water to prevent the open wound from closing. Removal of the nail is usually not necessary. Sometimes the swelling is so substantial that a paronychia can be mistaken as a felon. The key is to focus the treatment on the area that is most affected. Felons do not typically show symptoms around the nail.
Felon: This is a bacterial infection of the fingertip pulp. Patients have severe, throbbing pain on the pad of the finger. A small transverse mid-axial incision is enough to relieve the symptoms. The infection can involve multiple sub-compartments, thus, the septae that span the volar skin and distal phalanx should be divided to ensure the entire area is fully drained. If allowed to fester, the infection can spread to the bone and cause osteomyelitis.
Flexor tenosynovitis: An infection of the flexor tendon sheath can be diagnosed via Kanavel’s signs: finger held in flexion, finger swollen like a sausage, tenderness at A1 pulley, and pain with passive extension. If noted early with mild signs, flexor tenosynovitis can be treated solely with intravenous antibiotics. More advanced cases require surgical drainage. The preferred method is to make tow incisions: one palmar incision at the A1 pulley and another mid-axial incision at the A3 or A5 pulley.
Once the finger is drained and cultures are sent, a small, perforated feeding tube is threaded from proximal to distal within the sheath. The wounds are left open and sterile saline is run through the tube for 24-48 hours. The incisions are left open to heal secondarily. Mid-lateral incisions are superior to zig-zag palmar incisions on the finger as the latter increases the risk of flexor tendon exposure if the skin flaps die.
After a comprehensive assessment of the burn patient, including fluid resuscitation and evaluation of the airway and breathing, the clinician can focus attention on other areas such as the extremities. Prior to treatment the depth of burn should be determined.
- First degree burns are similar to sun burns and heal without intervention.
- Second degree burns involve a portion of the dermis and result in loss of the rete ridges of the skin. Blistering usually occurs soon after second degree burns, but these injuries usually heal with minimal intervention though scarring can be variable.
- Third degree burns comprise the entire thickness of the dermis: the skin is pale or white and insensate.
- Fourth degree burns extend beyond the skin. Diagnosing an acute burn is difficult but after a few days usually the tissue demarcate and the depth of injury is revealed.
The treatment of extremity burns can take place once basic life resuscitation measures have been instituted and the patient is stable. First and second degree burns are treated with topical antibiotic ointments (e.g. bacitracin). Avoid silver sulfadiazine in the hand because of potential systemic absorption, especially in children.
While most third degree burns of the dorsal hand heal well without functional sequelae, the same cannot be said for volar hand burns. Even small burns in this area can cause severe flexion contractures, especially if they cross flexion creases. When a clear diagnosis of a deep burn is made, these eschars should be excised and resurfaced with full thickness skin grafts. Full thickness skin grafts are preferred to split thickness ones as they are far less likely to contract secondarily.
War-related upper extremity trauma includes ballistic and blast injuries, and sharp injuries from combat and shrapnel. Ballistic injuries can cause significant trauma due to direct and zone injury. Blast injuries are the most destructive as they cause mangling injuries for which, unfortunately, treatment is usually amputation. Vascular injuries are the most threatening as they can cause significant blood loss with distal ischemia. For all of these injuries, the initial treatment should be stabilization of the patient followed by debridement of devitalized tissue, and then formal repair.
Sharp injuries: After examination and delineation of injured structures, many of these can be treated temporarily with washout and closure of the skin – deferring formal repair for another time. Prior to definitive repair, the clinician should gather all necessary equipment (tourniquet, sterile instruments, sutures), and appropriately prepare the extremity before executing the procedure.
Extensor tendon injuries can be repaired with minimal equipment. A z-shaped extension of the incision is necessary usually to gain enough exposure. Tendon ends should be debrided gently and apposed with 3-0 or 4-0 braided sutures such as mersilene or vicryl. Proximal lacerations can be repaired with a modified Kessler suture, whereas, more distal injuries can be repaired a figure-of-eight technique. Immobilization in an extended posture is necessary for 3 weeks at which point gentle range of motion exercises can begin. Full activities can be resumed after about 8 weeks.
In contrast to extensor tendons, repair of flexor tendons is usually more difficult. Flexor tendons can retract, making retrieval challenging. The intersection of the deep and superficial tendons as well as the tight flexor tendon sheath potentiate these challenges. When extending an incision on the hand, it should not cross a flexion crease perpendicularly.
Brunner’s (zig-zag) incisions or mid0lateral incisions are best to avoid flexion contractures. Once the ends are identified, they should be secured with small gauge needles to the local soft tissues. The repair can then be done with a variety of different techniques, but the simplest and easiest to learn is the modified-Kessler method. A 4-core technique using a 3-0 or 4-0 suture followed by an epitendinous stitch using a 6-0 running suture yields satisfactory results (Figure 4).
It is best to minimize the bulk of the tendon repair and to test for gliding intraoperatively. If the tendon repair dos not glide adequately, digital pulleys can be sacrificed. Only the A4 and half of the A2 pulleys are considered necessary for good function without bow-stringing. It is usually best to repair both the superficial and deep tendons; however, if repair of both will limit excursion, repairing only the deep tendon will be better. After skin closure, an extension-blocking splint is applied and the motion protocol can start around 1 week postoperatively.
Vascular injuries can cause bleeding and/or distal ischemia. The first step to stop bleeding is direct pressure. The great majority of bleeding, even from major vessels, can be stopped with pressure. In a healthy subject, a transected artery will usually stop bleeding because the muscular media of the artery contracts and closes the open end. Use of a tourniquet is strongly discouraged because it may cause more bleeding (venous engorgement) and distal ischemia. Any ongoing hemorrhage that does not respond to pressure is usually because the artery is partially lacerated (very rare). Also discouraged is the indiscriminate suturing/clamping of a vessel. Clamping and suturing can render the vessel difficult to repair and can cause damage to adjacent nerves.
Nerve repairs are not urgent and can be delayed. In ideal circumstances, nerves should be repaired in an epineural fashion (just repairing the outer sheath of the nerve) with fine sutures under magnification (Figure 5). A tension free repair is critical for optimal function. If there is too much tension, a nerve graft should be used.
Laceration of the ulnar artery, ulnar nerve proper, and dorsal sensory branch of the ulnar nerve (5.1). Microsurgical repair of each of the injured structures was performed (5.2). Nylon microsutures were used to repair the nerves (grouped fascicular repair does not provide improved recovery). Note the green suture was used to tag the flexor carpi ulnaris tendon, which was repaired after the other structures.
Closed fractures can be splinted and treated within 7-10 days. Open fractures require washout with immediate definitive repair or skin closure and splinting, and repair within a day or two. The urgent care of most fractures requires closed reduction to improve alignment. The principle involves traction, re-creating the deformity, and manipulation to reduce the fracture into better alignment. The fracture can then be immobilized with a splint. Many hand fractures, once reduced, will hold their position allowing primary healing – these are called stable fractures.
If a fracture is displaced by deforming forces (e.g. tendons) or cannot be appropriately reduced (these are called unstable fractures), it should be repaired operatively.
For unstable fractures, the quickest and easiest treatment is percutaneous pin fixation. Pins can be placed with minimal equipment. It is best to avoid opening fractures if possible. Open repair strips the periosteum and causes adhesions. Plates, in particular, can be quite problematic in the hand and should be avoided if possible.
Fractures, whether formally repaired or conservatively treated, should be immobilized until pain-free and some radiological signs of bridging bone are seen, usually about 3-4 weeks. Host factors such as smoking, vascular disease, immunosuppression, and diabetes impede bone healing. Shaft fractures have more cortical bone and heal slower than metaphyseal fractures.
Compartment syndrome favors systemic errors of commission rather than omission. The primary key with this condition is early diagnosis and treatment. Treatment is simple with minimal morbidity, but if undetected, compartment syndrome can cause devastating complication such as ischemia, muscle death, contractions, and long-term functional loss. At a cellular level, compartment syndrome occurs when the pressure in a closed compartment exceeds end-capillary perfusion pressure. This may occur due to bleeding, ischemia/reperfusion, infiltration, bites, burns, or tight dressings.
It is critical to discern compartment syndrome from ischemia. An extremity deprived of blood flow (e.g. vascular injury) becomes ischemic – releasing the compartments does not improve ischemia. However, an ischemic extremity to which blood flow is restored is at risk of developing compartment syndrome due to swelling of the muscles in tight compartments.
Diagnosis of compartment syndrome is clinical. Pain on passive extension is the primary heralding sign. Other cardinal signs include pallor, paresthesia, pulselessness, and paralysis typically occur later. In an obtunded patient, compartment pressures can be measured directly. Pressures greater than 30mmHg suggest compartment syndrome. Treatment is emergent fasciotomy. In the forearm, the classic teaching recommends a lazy S incision extending from the dorsal forearm to the volar wrist. However, with enough swelling, this can result in exposure and desiccation of the median nerve.
Another approach is via an ulnar incision which gives easy access to all compartments. The carpal tunnel should be released via a separate incision. In the hand, release is done via two dorsal incisions over the 2nd and 4th metacarpals which allow access to the interosseous muscles and adductor pollicis. In addition, separate thenar and hypothenar muscles allow release of the remaining intrinsic muscles of the hand.
In war situations, amputations may be the preferred method for treating complex injuries because they gives the patient a rapid functional result sooner with less risk than complicated reconstructions. Where facilities are limited, the indications for more distal amputations, such as digits, are expanded. Whenever possible, however, the thumb and hand should be preserved.
The primary principle of amputation is maximizing function, which usually translates to maximizing length. In the immediate term, the clinician should do everything possible to keep bone as long as possible and bring new soft tissue to cover if possible. If the length turns out to be unnecessary or functionally problematic, it can always be shortened in the future. For many open wounds of the fingertip, it is best to allow the wound to heal by secondary intention. This ensures excellent sensation and minimal morbidity. More problematic wounds require skin grafting or flap coverage (Figure 6).
Fingertip injury with exposed bone. A volar V-Y flap is planned (6.1) for closure. The skin is incised and the flap is undermined at the level of the bone. Gentle teasing of the soft tissue (without dividing) allows the flap to translate distally. It is then sutured loosely (6.2). Final result (6.3).
Perform amputations by first finding nerve ends and performing traction neurectomy to bury the nerve ends. Shorten the bone as necessary (minimal) to allow skin closure. Avoid suturing the flexor tendon to the extensor tendon as this may cause quadriga effect which weakens grip.