​Hand infections are frequently encountered in the primary care setting, where general practitioners (GPs) play a key role in early recognition, diagnosis and treatment. Early detection and management can prevent infections that may lead to prolonged hospitalisation or disability.

INTRODUCTION

Hand infections are common presentations in the acute care setting. The exact incidence of hand infections is difficult to determine as most are self-treated or treated by primary care physicians. However, it is estimated that a major metropolitan hospital can expect 25 to 50 admissions a year for serious hand infections.¹

Why early detection is important

While some hand infections may appear innocuous or mild in the early stages, they can rapidly progress to devastating infections requiring surgical debridement, resulting in prolonged hospital admission. Hence, it is essential to recognise and diagnose these infections early and promptly initiate treatment.

In addition, these hand infections can lead to tissue loss, functional impairment and even permanent disability if left untreated.

1. PARONYCHIA

Paronychia is an infection of the lateral nail fold surrounding the nail. It may be acute (duration of less than six weeks) or chronic (duration of six weeks or more).²

Presentation and diagnosis

This presents with erythema, swelling, tenderness and occasionally spontaneous discharge of purulent material. It occurs after disruption of the seal between the nail fold and nail plate due to penetrating trauma, nail-biting, manicures or hangnails.

Treatment

In the early stages of paronychia, patients can be treated with warm soaks, systemic oral antibiotics and resting the affected digit. The antibiotic regimen should cover Staphylococcus aureus.

If there is a superficial abscess, early drainage is advised by incision of the paronychia fold with a blade directed away from the nail bed and matrix.

In cases with subungual pus, nail avulsion should be performed under a digital block.³ The pus within the perionychium may track volarly to the pulp space presenting with a pulp abscess or felon.

2. FELON

Felon is the second most common hand infection, comprising around 15-20% of cases.⁴ It is defined as a closed-space subcutaneous infection in the pulp space of the distal phalanx of a digit.¹

Presentation and diagnosis

There is typically a history of penetrating injury preceding a felon. Symptoms include a tense and tender pulp with erythema and swelling that usually does not extend proximally past the distal interphalangeal joint (DIPJ) flexion crease.

However in severe cases, felons can rupture the DIPJ, causing septic arthritis, and extend into the distal end of the flexor tendon sheath, causing flexor tenosynovitis.¹ A finger radiograph is essential to rule out osteomyelitis of the distal phalanx.

Treatment

Early felons may be treated with antibiotics, rest and elevation.

The most common microorganism involved is Staphylococcus aureus, but various aerobic and anaerobic organisms can cause felons. Thus, broad-spectrum antibiotic therapy is essential.¹

However, a tense pulp with the presence of subcutaneous collection is an indication for surgical drainage. A longitudinal midline incision over the pulp area of maximal tenderness is usually made to drain the collection. The pulp septae should be surgically released as well to ensure no hidden collection that may be missed.

The wound is then left open and dressed with a sterile dressing. Dressing changes should be performed every 24-48 hours using sterile soaks and Jelonet dressing. The wound may be left to heal by secondary intention.

3. FLEXOR TENOSYNOVITIS

Flexor tenosynovitis is a closed space infection of the digital flexor tendon sheath.

Presentation and diagnosis

This is often accompanied by a history of penetrating injury to the digit, with Staphylococcus aureus being the most common organism.

In 1912, Allen Kanavel described four cardinal signs indicative of flexor tenosynovitis:⁵

• Digit held in partial flexion
• Pain upon passive extension
• Fusiform swelling
• Tenderness along the flexor tendon sheath

Factors that predict poor outcomes include:

• Presence of digital ischaemia
• Subcutaneous purulence
• Age above 43 years
• Polymicrobial infection
• Presence of comorbidities (diabetes mellitus, renal failure or peripheral vascular disease)

The presence of digital ischaemia and subcutaneous purulence increases the risk of amputation to 59%.⁶

Laboratory investigations may reveal raised inflammatory markers, and the patients may be bacteraemic. Infection of the flexor tendon sheath for the thumb and little finger may spread proximally to the space of Parona and form a horseshoe abscess.

Treatment

Early management includes intravenous antibiotics and elevation. In addition, surgical drainage is indicated, especially with suppurative flexor tenosynovitis^.7

Figure 4 shows a closed tendon sheath irrigation using an infant feeding catheter. However, in the presence of severe infection with tendon necrosis, open debridement is preferred.⁸

4. SEPTIC ARTHRITIS AND ANIMAL BITES

Septic arthritis in the hand or wrist results from a puncture wound or an extension of an adjacent tendon sheath infection, subcutaneous abscess or bone infection. These can lead to the destruction of the joint and osteomyelitis of the phalanges or metacarpals.¹

It can occur following a ‘fight bite’ or an animal bite.

Most human bite infections result from a ‘clenched fist injury’ – a laceration over the dorsal metacarpophalangeal joint (MCPJ) from striking teeth with a clenched fist. A tooth can easily penetrate the MCPJ capsule, leading to septic arthritis if left untreated.¹

Dog and cat bites account for more than 90% of all animal bite wounds. Patients with animal bites tend to present late, as these wounds may seem innocuous in the early stages. However, they may have raised inflammatory markers, and plain radiographs may reveal remnant foreign bodies, cortical breaks and bone erosions.

Presentation and diagnosis

Patients with septic arthritis typically present with a swollen, erythematous and painful joint. Needle aspiration of the joint helps establish the diagnosis and identify the causative microorganism.

Eikenella corrodens is most associated with human bite infections. The most common pathogens cultured from the dog mouth are Staphylococcus aureus, Streptococcus viridans, Bacteroides and Pasteurella multocida. Pasteurella multocida is especially common in cat saliva.

Treatment

The initial treatment for animal bites should encompass an update of tetanus immunisation and identifying the rabies immunisation status of the animal.

Prompt and thorough irrigation of the wound should be performed after obtaining wound cultures, in addition to broad-spectrum empirical antibiotics cover.

Bite wounds over the hand and wrist joints should be treated as septic arthritis until proven otherwise. Early surgical debridement and joint irrigation are advised.

Figure 5 shows a technique of catheter irrigation of a septic joint of the hand. We routinely perform continuous catheter irrigation for at least five days from the initial debridement. In some cases, open debridement and eventual amputation may be necessary.

The antibiotic duration varies from ten days to six weeks, depending on the organism involved and the clinical improvement of the infection.⁹

REFERENCES

1. Brown, D. M. & Young, V. (1993). Hand infections. Southern Medical Journal, 86(1), 56–66. https://doi.org/10.1097/00007611-199301000-00013
2. Wolfe, S. W., Pederson, W. C., Hotchkiss, R. N., Kozin, S. H., Cohen, M. S., & Stevanovic, M. V. (2016). Acute Hand Infections. In Green’s operative Hand Surgery E-Book (pp. 22–23). Essay, Elsevier.
3. Shafritz, A. B., & Coppage, J. M. (2014). Acute and Chronic Paronychia of the hand. Journal of the American Academy of Orthopaedic Surgeons, 22(3), 165–174. https://doi.org/10.5435/jaaos-22-03-165
4. Linscheid, R. L., & Dobyns, J. H. (1975). Common and uncommon infections of the hand. Orthopedic Clinics of North America, 6(4), 1063–1104. https://doi.org/10.1016/s0030-5898(20)30967-6
5. Book review: Infections of the Hand: A Guide to the Surgical Treatment of Acute and Chronic Suppurative Processes in the Fingers, Hand, and Forearm. By Allen B. Kanavel, M.D. illustrated with 133 engravings. Philadelphia and New York: Lea & Febiger. 1912. (1912). The Boston Medical and Surgical Journal, 166(20), 743–743. https://doi.org/10.1056/nejm191205161662011
6. Pang, H.-N., Teoh, L.-C., Yam, A. K. T., Lee, J. Y.-L., Puhaindran, M. E., & Tan, A. B.-H. (2007). Factors affecting the prognosis of pyogenic flexor tenosynovitis. The Journal of Bone & Joint Surgery, 89(8), 1742–1748. https://doi.org/10.2106/jbjs.f.01356
7. Novacheck, T. F. (1998). Instructional course lectures, The American Academy of Orthopaedic Surgeons - Running Injuries. The Journal of Bone & Joint Surgery, 80(8), 1220–33. https://doi.org/10.2106/00004623-199808000-00017
8. Flynn, J. E. (1955). Modern Considerations of Major Hand Infections. New England Journal of Medicine, 252(15), 605–612. https://doi.org/10.1056/nejm195504142521501
9. Murray, P. M. (1998). Septic Arthritis of the Hand and Wrist. Hand Clinics, 14(4), 579–587. https://doi.org/10.1016/s0749- 0712(21)00419-4

 

Dr Chung Sze-Ryn is an Associate Consultant in the Department of Hand & Reconstructive Microsurgery at Singapore General Hospital (SGH). She graduated from the Royal College of Surgeons, Ireland in 2011 and achieved her MRCS (Edinburgh) and MMed (Surgery) in 2013 and 2016 respectively. Dr Chung completed her Hand Surgery Residency in 2020 and received the Outstanding Resident award in her final year. She is currently a clinical instructor at Duke-NUS Medical School and a clinical physician faculty member for the SingHealth Hand Surgery Residency Programme.

She has also been published in many distinguished peer-reviewed journals and was actively involved in the grant collaboration between the SGH Hand & Reconstructive Microsurgery Department and Nanyang Technology University (NTU-SACP grant). She recently won a grant of 150,000 SGD from the SingHealth Duke-NUS Academic Medical Centre to do animal research on the process of adhesion formation and its impact on clinical outcomes. Dr Chung has a special interest in reconstructive microsurgery of the extremities as well as wrist disorders.

Dr Farah Syahera binti Khairi is a Medical Officer in the Department of Hand & Microsurgery at Singapore General Hospital. She graduated from the National University of Ireland, Galway in 2016. Throughout her journey as a junior doctor, she has done predominantly surgical postings. She has a special interest in hand surgery and is a hopeful candidate for the Residency Programme this year.

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