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OlliLeppänen

Deep Hand Infections

Circulation in the upper extremities is good, and simple wounds and contusions usually heal well.
In deep structures and spaces of the hand (tendon sheaths, compartments, joints), inflammation may not respond well to treatment because the innate immune response there is limited.
- Pyogenic flexor tenosynovitis is the most common.
Factors predisposing to inflammation include
- conditions compromising the immune response (such as diabetes, alcoholism, undernutrition)
- stings, bites, other injuries.
Deep hand infections require treatment in the operating room.
Fingers often remain stiff after the healing of any deep hand infection.

This is the most common deep hand infection.
Even if appropriately treated, it may affect hand function significantly.
Inflammation is often preceded by a wound or a prick (by a splinter or plant thorn, for example) at the fingertip, the midline of the volar aspect of the finger, or the palm 1-4 days earlier.
The infective agents are usually bacteria belonging to normal skin flora.

The clinical picture classically shows the four Kanavel signs.
- Fusiform swelling of the whole finger
- Tenderness to palpation particularly at the volar aspect of the finger
- Inflamed finger held in slight flexion
- Pain with passive extension of the finger
All four signs are usually present but even the presence of only three raises significant suspicion of pyogenic flexor tenosynovitis.
Since in most people the flexor tendon sheaths of the thumb and little finger join together in the wrist area, infection in just one of these digits may result in what is called a horseshoe abscess.
The inflammation may progress rapidly and cause systemic symptoms (high fever, sepsis).

Emergency consultation of specialized care is warranted, and any further investigations are usually done at a hospital.
If basic blood count, CRP, blood glucose and blood culture are available rapidly in primary health care, they can be done before transferring the patient to hospital.
In mild or unclear cases, ultrasound examination of the hand can be done in specialized care, if necessary, in order to choose between surgery and conservative treatment.

The primary treatment is irrigation of the tendon sheath in the operating room. An irrigation catheter can be left inside the tendon sheath to continue irrigation on the ward.
A sample for bacterial culture is taken during surgery and, as far as possible, antimicrobial treatment should therefore only be started in association with the surgery.
- Antimicrobial treatment should not be started before consulting specialized care.
Antimicrobial treatment (usually cefuroxime) should be started intravenously; further medication depending on the bacterial culture results is normally oral.
In the case of mild inflammation where the patient seeks treatment before the symptoms have become severe, conservative treatment, i.e. antimicrobials alone, can be considered. The decision should be made in specialized care.
It is essential to begin active occupational therapy or physiotherapy immediately after surgery because, once inflammation has subsided, scar formation and damage to gliding surfaces involve a significant risk of stiff fingers.

The most common differential diagnostic alternatives are finger cellulitis or fingertip abscess (felon).
- In a felon, inflammation is usually restricted to the fingertip and will not proceed along the tendon sheath.
- A finger abscess should be incised in specialized care but recovery is normally less problematic than in the case of tenosynovitis.
Other conditions to consider
- Stenosing tenosynovitis, i.e. trigger finger Trigger Finger
- Gout or other type of arthritis Gout and Pseudogout
- Rheumatic diseases Disease-Specific Signs and Symptoms in Patients with Inflammatory Joint Diseases
- Other deep hand infections
- Tuberculosis (treatment-resistant chronic cases) Diagnosing Tuberculosis

There are several deep compartments in the hands that may be infected and accumulate pus.
- Bite wounds Bite Wounds, sea life injuries Marine Animal-Induced Injuries and Poisoning
Deep space infections are considerably rarer than pyogenic tenosynovitis.
Deep space infections should be distinguished from cellulitis. In unclear cases, ultrasonography is diagnostic.
- In cellulitis, finger movements are usually quite well preserved and erythema is often clearly defined.
- The history of deep infections involves a clearly penetrating injury.
Deep soft tissue infections should be treated by incision and removal of any necrotic tissue in operating room conditions.
Basic blood count, CRP, blood glucose and blood culture should be done before surgery.
As far as possible, antimicrobial treatment should be started in association with surgery after taking a sample for bacterial culture.

The most common cause of osteomyelitis is prolonged paronychia.
- If paronychia is prolonged (with symptoms for more than one month), an x-ray should be done to facilitate the diagnosis of osteomyelitis if it has already caused bone destruction.
In adults, osteomyelitis of the hand is usually treated by bone resection or, if in a finger, by amputation.
Purulent arthritis may be haematogenous or result from a wound situated at a joint.
- The most common cause is a bite injury Bite Wounds.
In differential diagnosis, gout Gout and Pseudogout and rheumatic diseases Disease-Specific Signs and Symptoms in Patients with Inflammatory Joint Diseases should be considered.
The treatment of bacterial arthritis is surgical, with debridement followed by a long course of antimicrobial therapy.

Penetration of the skin by a jet of liquid or gas under high pressure, most often in the tip of the index finger, causes deeper tissue destruction than would be expected on initial assessment.
- Oil-based xenobiotics which spread extensively in the tissue are particularly difficult to treat.
Specialized care should be consulted without hesitation in association with high-pressure injuries because such injuries almost invariably require surgical treatment.

Wolfe SW, Pederson WC, Kozin SH, Cohen MS. Green's operative hand surgery. 8th edition. Elsevier, 2022.
Rekant MS, Tarr R. Hand Abscesses: Volar and Dorsal. Hand Clin 2020;36(3):307-312 [PubMed]
Goyal K, Speeckaert AL. Pyogenic Flexor Tenosynovitis: Evaluation and Management. Hand Clin 2020;36(3):323-329 [PubMed]