Acquired Upper Limb Injuries

Written by: Fergal Marlborough from Edinburgh University,

Introduction

 

Hand injuries are rarely associated with mortality but are a significant cause of patient morbidity, and therefore it is vital to manage them correctly in order to maintain maximum function and to avoid complaints from unhappy patients. 

 

This article is meant to provide guidance on the initial investigations, management, and surgical referral of the common and serious hand injuries frequently encountered in Accident & Emergency.

 

History

 

When assessing a patient with a hand injury, taking accurate history is vitally important to making a successful diagnosis and guiding one's examination.  Its crucial components are:  

 

  •  Injury itself- mechanism of injury, position of hand during injury, timing of injury, other injuries.
  •  Rest of history - hand dominance, occupation, past medical history and drug history, as per specific presentation.

 

Examination

 

The "Look, Feel, Move" examination technique is easy to remember and simple. A thorough history allows for the examination to be tailored accordingly and will have narrowed down the list of structures that are potentially damaged. Many structures in the hand slide with movement, so it is vital to conduct the examination in the position in which the injury occurred, e.g. with fist clenched if a fight bite has been sustained. 

 

1. Look:    Colour, swelling, deformity, cascade, contamination, soft tissue loss.

2. Feel:    Temperature, sweating, tenderness, crepitus, sensation, pulses.

3. Move:   Active & passive movements.

 

Flexor Tendon Injury

 

Flexor tendon injuries are common, and may result from any insult, often sharp, to the volar aspect of the hand. Each digit has a flexor digitorum superficialis (FDS) and a flexor digitorum profundus (FDP). FDS flexes the proximal interphalangeal joint (PIPJ) and FDP flexes the distal interphalangeal joint (DIPJ). 

 

The wound can appear trivial, but may be deep enough to have divided a tendon.   

 

Figure 1 - Normal Resting Cascade of Hand

Location of injury and assessment of the cascade of the hand [Figure 1] are important initial observations. Lack of the normal flexion cascade of one or more fingers provides the diagnosis of a divided or damaged tendon. Pain and slight weakness when actively flexing a digit may be a sign of partial tendon division that could require repair (2).

 

A deep enough wrist laceration may divide all flexor tendons advancing into the hand. An appropriately placed wrist wound along with complete loss of the flexion cascade reveals this diagnosis.

 

If both flexor tendons to a single digit (FDS and FDP) are divided, then that finger will be extended, standing out from the other fingers normally flexed in the cascade [Figure 2].

 

Figure 2 - Index Finger FDS and FDP division

Flexor Digitorum Superficialis

 

FDS inserts into the middle phalanx to produce PIPJ flexion when contracted. This knowledge helps to diagnose an FDS division when FDP to the same digit remains intact. FDP inserts into the distal phalanx, producing DIPJ flexion when contracted.

 

To test for isolated FDS injury in any of the ulnar three digits, all DIPJs are stabilised in extension except the finger to be examined (1).

 

Figure 3 - FDS testing

This is done by placing the distal phalanges in contact with the underside of a table in supination, [Figure 3]. The patient is asked to flex the digit being examined – if they can, then FDS is intact. If they are unable to, however, then FDS is divided and will require surgical repair.

 

The test is based upon the fact that the FDP tendons to the ulnar three digits share a common origin.  Therefore flexion in any of these digits, whilst blocking action of FDP, has to come from an intact FDS to that digit.

 

N.B. With isolated FDS division, there will be no postural change in the cascade of the hand, as an intact FDP will produce the flexion normally seen in the cascade.

 

Flexor Digitorum Profundus

 

To examine for division of this tendon, the middle phalanx is stabilised, and the patient asked to flex the DIPJ, [Figure 4]. This action is done by an intact FDP tendon. 

 

In the thumb, stabilisation of the proximal phalanx and asking the patient to flex the interphalangeal joint, tests for an intact flexor pollicis longus.

 

Figure 4 - FDP testing

Avulsion

 

In the absence of an open wound, inability to flex one or more digits may result from a tendon rupture or nerve palsy. Application of pressure on the flexor muscle mass in the anterior forearm will lead to passive finger flexion if the tendons are intact.

 

Avulsion of the FDP is a common injury, often occurring in the ring fingers of rugby players. The tendon detaches from the distal phalanx and sometimes avulses a segment of bone with it. The injury results from forced extension whilst the FDP is maximally contracted, as happens with a finger getting caught in a rugby jersey.

 

X ray may show a bony fragment of the distal phalanx [Figure 5] still attached to the ruptured end of the tendon, which may have retracted into the palm.

 

Late presentation some months after injury is common with FDP avulsion. This is because pain and swelling are often absent, and PIPJ and metacarpo-phalangeal joint (MCPJ) flexion is preserved, making the DIPJ flexion deficiency less obvious.

 

Treatment is with prompt surgical repair.

 

Figure 5 (Ref no. 3) - X-Ray Showing Avulsion # of distal phalanx

Extensor Tendon Injuries

 

In a patient with an extensor tendon injury the history is likely to involve some trauma to the dorsum of the hand (such as a fight bite), or forced flexion of an extended digit. 

 

Testing for damage to the long extensor tendons to the fingers involves applying gentle resistance to the proximal phalanx whilst the patient extends the finger. Subsequently, stabilising the middle phalanx whilst simultaneously applying resistance to the nail during extension examines for DIPJ extension and therefore tests for mallet finger [Figure 6].

 

Figure 6 - Mallet Finger Injury Mechanism - Forced Flexion of Extended Digit

Division of the central slip (inserting into middle phalanx) whilst the lateral bands (inserting into distal phalanx) remain intact leaves the patient able to extend DIPJ but unable to extend PIPJ. Examination for this injury is done by placing the palm fat on a table, with the MCPJs flexed to 90 degress over the edge of the table. Asking the patient to extend PIPJ against resistance tests for central slip division. If the central slip is divided, no PIPJ extension is felt, but DIPJ is extended due to intact lateral bands. If this injury is missed, a boutonniere deformity will result.

 

X-ray is important in extensor tendon injuries, because a fragment of bone that may have avulsed with the tendon itself will sometimes be apparent. 

 

If bone has been avulsed, then open pin fixation of the DIPJ is only indicated if the fragment is large and displaced. If the fragment is very small, or undisplaced, splinting can suffice. 

 

Tendon Repair

 

Repair of a lacerated tendon involves opposing the two cut ends together and suturing them with epitendinous (around the edge of the tendon) and core sutures. 

 

Splinting after flexor tendon repair is in a dorsal splint, with wrist neutral, MCPJs flexed to 70 degrees and PIPJs/DIPJs extended. This allows for active extension and passive flexion within 48 hours of repair and prevents PIPJ contracture. Early protected mobilisation is required, under close physiotherapy supervision. 

 

Nerve injuries

 

Injuries to nerves often occur through a sharp cutting injury, although any insult can damage a nerve if deep enough. Such injuries may also be present even with a trivial wound.

The three nerves to the hand are the median, ulnar and radial nerves.  A sound knowledge of the structures and modalities supplied by each helps to diagnose damage to any one of them.  The nerve supply to each digit is by an ulnar and a radial digital nerve, running up each side of the digit and sitting in the volar 1/3 of the digit. 

 

Figure 7 - Nerve Repair Diagram Showing Epineural Sutures Used to Oppose Cut Ends of Divided Nerve

Volar injuries near either edge of a digit are therefore likely to cause digital nerve damage. 

 

Examination of motor and sensory modalities of each nerve reveals if damage has occurred. If nerve damage is suspected, referral to Plastics is necessary for wound washout and exploration in theatre and microsurgical repair [Figure 7]. 

 

Outcome after nerve repair is variable.  If successful, sensation and motor function may return, but can take 6-12 months to do so (5). Nerve fibre re-growth after repair averages around 1mm per day. 

 

Bone Injuries (Fractures)

 

High impact trauma to the hand can result in fractures. 4th and 5th metacarpals commonly break as a result of throwing a punch (surprisingly often the target is a wall!).

 

Phalangeal fractures [Figure 8] can occur when one or more digits get trapped in a door or crushed by a similar impact.

 

Figure 8 (Ref no. 6) - Proximal Phalanx Displaced # Little Finger

 

A thorough history of the mechanism of injury and a simple examination, as detailed below, should provide a useful indication as to whether a fracture is likely before an X-ray is even performed.

 

Look:     Swelling, deformity, open fracture.

Feel:      Tenderness, crepitus, neurovascular status.

Move:   Restricted motion, abnormal motion, pain on movement, instability.

X-Ray:   Fracture, dislocation, bone loss, foreign body.

Management:   Analgesia, reduce, splint (volar slab), antibiotics for open fracture (co-amoxiclav), discuss with hand surgeon.

 

Soft Tissue Injuries

 

Degloving of tissue results from large shearing forces that pull skin and soft tissue off the hand [Figure 9]. Almost all patients with soft tissue loss over the hand will require a surgical referral.

 

On examination colour of any skin flaps, and evidence of dark, necrotic tissue should be noted. The degree of wound contamination, neurovascular status, and observation of any structures that are exposed are also important parts of the initial assessment.

Figure 9 (Ref no. 7) - Degloving Injury to Multiple Digits

Treatment is with clean, moist jelonet dressings, and referral to surgeons for prompt debridement and reconstruction of wounds. 

 

Burns

 

When presented with any hand burn [Figure 10] crucial parts to the history include – type of burn, length of contact time, and burns elsewhere other than the hand. 

 

Life threatening injuries should be assessed and treated before hand burns.  Burns resuscitation is necessary for children with >10% burns or adults with >15% burns. The standard fluid resuscitation is 3-4ml/Kg/% burn. 

 

Early management in A&E should be to photograph the hand for later reference and wrap in clingfilm/jelonet/polythene bag. 

 

Figure 10 (8) - Burned Hand

Burns are classified according to the depth of the injury. Erythema is the most superficial depth of burn, followed by partial thickness, and then full thickness. 

 

Erythema appears red and is painful to touch. It will heal without any intervention.

 

Partial thickness burns are further split into 2 categories – superficial partial thickness (SPT) and deep dermal. SPT burns show blistering and erythema and are very sensitive to touch. These will heal without surgical intervention (8). Deep dermal burns show less blistering and less sensitivity to touch. The skin over the hand is usually pale, and these burns require surgical treatment. 

 

Full thickness burns appear white and feel leathery. The skin has no capillary refill and sensation is absent. Such burns require referral to Plastics for debridement and grafting. 

 

Escharotomy should be considered to reduce compression from circumferential limb burns, and fasciotomy may also be done simultaneously to avoid the compartment syndrome. 

 

In summary, all full thickness and deep dermal burns require referral to specialist burn services. In reality, experts often find defining burn thickness difficult and therefore specialist opinion should be sought where any doubt exists. 

 

High Pressure Injection Injuries

 

Extensive mechanical and chemical deep soft tissue injury can occur in the presence of only a very small trivial surface entry wound. Such injuries are rare, but when they do occur, are often the result of an industrial accident.

 

Careful history of the mechanism of injury, and a thorough examination of the function and neurovascular status of the hand will reveal such an injury. X-ray may reveal metal or paint within the hand (9). Early referral to Plastics will almost certainly be required for exploration in theatre. 

 

Compartment Syndrome

 

This is defined as “an increase in interstitial fluid pressure within an osseofascial compartment of sufficient magnitude to cause a compromise of the microcirculation leading to myoneural necrosis”.

 

The most common compartment in the upper limb to be effected by compartment syndrome is the anterior compartment of the forearm.

 

Figure 11 - The Most Reliable Sign is Severe Pain on Passive Flexion of Affected Compartment

Causes can be divided into those in which there is a reduced compartmental volume and those in which there is an increased compartmental content:

 

  1. Reduced compartmental volume – crush / burns / tight bandages / cast / tourniquet / lying on limb / excessive traction.
  2. Increased compartmental content - Bleeding / Major vascular injury / Reperfusion / Trauma (esp: high pressure injection) / Intensive use of muscles / Venous obstruction / Low serum osmolarity / Nephrotic syndrome.

 

Diagnosis is on clinical grounds, but can be confirmed by measuring an intra-compartmental pressure of greater than 30mmHg.

 

Pain is the cardinal symptom. Patients complain of excessive pain, often out of proportion to the appearance of the limb, or worsening pain despite splinting of an arm with a fracture (10). As the syndrome progresses, signs may include swelling of the limb, reduced radial pulse, pallor of the fingers, and increased capillary return time, however these are late signs!

 

The most accurate diagnostic sign is that severe pain is caused on passive stretching of the muscles in the culpable compartment, [Figure 11]. 

 

ABCD principles of acute management apply. Removal of tight bandages or casts is necessary. Definitive treatment is by prompt surgical fasciotomy, releasing pressure on muscles and nerves, and debridement of necrotic  tissue. Leaving the wound open will prevent progression of tissue damage, as swelling will continue for 48 hours after reperfusion. Loose skin coverage over nerves and vessels, leaving the fascia open is ideal. Splinting is with the wrist in extension, and early mobilisation and limb elevation prevents joint stiffening and reduces oedema.

 

Diagnosis and treatment must be established urgently as irreversible tissue damage occurs in 6 hours. 

 

Amputations

 

After a quick and accurate history, early management is by wrapping the amputated part in clean moist gauze, placing in a plastic bag, and storing it in iced water or a fridge at 4 degrees Celsius. 

 

It is important NOT to put the amputated part in direct contact with ice, as this may damage it. 

 

Figure 12 (11) - Traumatic Amputation

Digits can be replanted successfully up to 24 hours after the amputation provided they are stored correctly (11). Ideally repair within 4-6 hours is required for optimal prognosis. This involves microsurgical techniques to re-attach veins, arteries and nerves, as well as bone and tendon. Clean cuts have more successful outcome than crush/avulsion injuries, because the ends of the severed structures can be easily opposed allowing repair. 

 

As with any open injury, infection and bleeding can be a problem. For this reason it is also necessary to provide tetanus prophylaxis, start IV broad spectrum antibiotics and to minimise haemorrhage from the wound as with any trauma scenario. 

 

Not all patients are suitable for replantation after amputation.  Contra-indicaications fall under absolute and relative:

 

Absolute contraindications to replantation are multiple injuries within the amputated part, severe traumatic injuries elsewhere, and severe systemic illness. 

 

Relative contraindications to replantation are patient age, severe avulsion injuries, prolonged warm ishaemia time and massive contamination.

 

Bites

 

Bites are troublesome to patients for two main reasons. 

 

The first is that wound infection is common due to the fact that both human and animal teeth carry a large number of micro-organisms. The second reason is that bites can also cause damage to deep structures beneath the skin, particularly in the hand. 

 

Figure 13 - Showing Common Human Fight Bite Mechanism

Human Bites

 

Human “fight bites” occur as a result of a punch connecting with the recipient’s tooth and usually effect the MCPJs over the 4th and 5th fingers and are extremely common in Accident & Emergency [Figure 13]. Deliberate bites from humans also happen, and the management principles for both types are the same.   

 

IV antibiotics (co-amoxiclav) should be prescribed as the wound is presumed to be infected. Surgical exploration is mandatory, with the fingers in the same position as the bite occurred in. This is because tendons and other structures slide when the hand moves and so damaged structures may disappear from the wound when not examined in the position of injury. 

 

Careful assessment is carried out to check if tendon injury (often extensor) or joint involvement has occurred as a result of the bite.  Repair of damaged structures and thorough wound washout in theatre is then perfromed. 

 

Animal bites

 

The two most common encountered in the UK are dog and cat bites. 

 

Dog bites tend to crush structures, whereas cat’s teeth insert deep onto tissues and often introduce deep infection. Nonetheless, this is not a rule, and dog bites can commonly cause infection, and cat bites can damage structures. 

 

Dog bites can result in infection fron Staphylococcus spp, Streptococcus spp, Moraxella spp and many others. Pasteurella is common after cat bites, but many other organisms can also cause infection after such a bite (12). 

 

Again careful assessment of associated injuries to deep structures in the hand is necessary, and surgical debridement and washout should be performed. Wounds are left to heal by secondary intention. IV co-amoxiclav should be administered as with human bites, and in all bite wounds tetanus status should be sought. 

 

Summary

 

Hand injuries occur extremely commonly and accurate history, initial assessment and appropriate management assists in maintaining as much hand function as possible. As with any branch of medicine hand trauma diagnoses are made most accurately from the history and confirmed by examination. 

 

The hand is a complex anatomical structure that allows exquisitely refined skills to be performed on a daily basis. As important as the initial medical or surgical management of a hand injury is the physiotherapy afterwards, which aides in reducing stiffness and facilitating return of hand function.   

 

Increasingly complex and exciting new surgical interventions are being performed on the hand, and this is a rapidly growing field. Hand function is vitally important to most patients and optimal initial management improves morbidity significantly. 

 

References

 

  1. Lister's The Hand: Diagnosis and Indications. 4th edition. Paul Smith.
  2. Grabb & Smith's Plastic Surgery. 6th Edition. Charles H. Thorne, Scott P. Bartlett, Robert W. Beasley, Sherrell J. Aston, Geoffrey C. Gurtner, Scott L. Spear.
  3. Singapore Society for Hand Surgery. "Inability to flex distal interphalangeal joint after a fall."  
  4. Mallet Fracture. Author: Michael E Robinson, MD, Consulting Staff, Department of Orthopedics, Division of Primary Care Sports Medicine, Permanente Medical Group and Kaiser Hospital.
  5. American Society for Surgery of the Hand (ASSH).
  6. BoneAndSpine.com.  Fracture of Proximal Phalanx Of Little Finger -Anteroposterior and Oblique Views.  Dr Arun Pal Singh, Dr Ajay Pal Singh.
  7. ehand.com The Electronic Textbook of Hand Surgery.  Clinical Example: Multiple finger degloving treated with medial cross arm flap and temporary syndactyly.
  8. Initial Evaluation and Management of the Burn Patient.  Author: Robert L Sheridan, MD, Assistant Chief of Staff, Chief of Burn Surgery, Shriners Burns Hospital; Associate Professor of Surgery, Department of Surgery, Division of Trauma and Burns, Massachusetts General Hospital and Harvard Medical School.
  9. Hand, Injection Injuries.  Author: Ramotsumi M Makhene, MD, Consultant Hand Surgeon, Detroit Medical Center.
  10.  Compartment Syndrome, Upper Extremity: Treatment.  Author: Stephen Wallace, MD, Staff, Department of Emergency Medicine, Eastern Idaho Regional Medical Center.  Coauthor(s): Douglas G Smith, MD, Associate Professor, Department of Orthopedic Surgery, University of Washington, Harborview Medical Center.
  11.  Replantation. Author: Mark I Langdorf, MD, MHPE, FAAEM, FACEP, RDMS, Professor of Clinical Emergency Medicine, Department Chair, Associate Residency Director, Department of Emergency Medicine, University of California at Irvine.  Coauthor(s): J Akiva Kahn, MA, University of California, Irvine, School of Medicine.
  12.  Animal Bites in Emergency Medicine. Author: Alisha Perkins Garth, MD.  Coauthor(s): N Stuart Harris, MD, MFA, FACEP, Clifford S Spanierman, MD.

 

Further Reading:

 

* British Society for Surgery of the Hand (BSSH).

* Lister's The Hand: Diagnosis and Indications. 4th edition. Paul Smith.