Infections



Infections


Thomas R. Hunt III

Christopher Robert

Michael Makary

Alexander M. Marcus



I. General Principles

Treatment to successfully eradicate hand infections consists of incision and drainage, debridement of devitalized tissues, immobilization and elevation, and antibiotics. Tetanus status should be updated and once cultures are obtained, the patient should be placed on empiric antibiotics chosen based on the expected pathogen causing the disease process. The antibiotics are then adjusted according to the results of the cultures and sensitivities. Soaking the hand following surgical drainage will aid in keeping the wound open and decrease the reaccumulation of purulent exudates.

Patient’s medical issues should be accounted for in the treatment of hand infections. In general, the same organisms that are encountered in the general population cause hand infections seen in immunocompromised patients. However, the course of disease is much more virulent. Patients who are immunosuppressed from transplants or diabetes may require amputations to control the infection and tissue necrosis. Gram-negative and polymicrobial infections are more common in this population. Fluctuations in blood glucose are common and should be treated aggressively.


II. Deep Space Infections

In order to recognize and treat deep space infections, it is essential to understand the anatomy of the potential spaces of the hand and their relationship to each other. Urgent drainage, thorough irrigation, intravenous antibiotics, elevation, and immobilization are the critical components of successful management. The wound should be packed open and 1 to 2 days later soaks and rehabilitation are initiated.


A. Midpalmar Space

A midpalmar space infection usually follows penetrating trauma or contiguous spread from a long, ring, or small finger septic flexor tenosynovitis. As with other deep space infections in the hand, marked dorsal hand swelling may divert the examiner’s attention away from the palm, the true site of the infection. The mid-palm is swollen, with loss of the normal palmar concavity in addition to tenderness and erythema. Passive motion of the involved digits causes pain. Debridement can be performed through transverse or oblique longitudinal incisions.


B. Thenar Space

In addition to erythema, tenderness, and swelling, patients present with palmar abduction of the thumb. Passive thumb adduction and opposition exacerbate the pain. Palmar, dorsal, and combined incisions for drainage have been described. Release of the
thenar space may require both volar and dorsal incisions to completely drain the dumbbell abscess. Incisions parallel to the web commissure should be avoided to prevent web space contracture.


C. Hypothenar Space

The hypothenar space is located ulnar to the midpalmar space, and is composed of the hypothenar muscles surrounded by their enveloping fascia. Hypothenar space infections are less common than other deep space infections in the hand.


D. Parona Space

Parona space is the potential space bounded by pronator quadratus, digital flexors, flexor pollicis longus, and a vertical band of fascia radial to flexor carpi ulnaris and the ulnar neurovascular bundle in the distal forearm. This space becomes infected by spread from either the radial or ulnar bursa and provides the “bridge” for the development of a horseshoe abscess. A tender, erythematous fullness is palpable at the volar wrist crease level. Signs and symptoms of septic flexor tenosynovitis of the thumb or small finger and radial or ulnar bursa infection are likely. Symptoms of median nerve irritation are frequently present. Incisions used for decompression are placed to protect the median nerve and its palmar cutaneous branch and to maintain adequate postoperative soft tissue coverage. (an extensile Carpal Tunnel Release (CTR) incision made across the wrist flexor crease, centered just ulnar to the palmaris longus and radial to the hook of the hamate).


E. Dorsal Subaponeurotic Space

The dorsal subaponeurotic space is contained by the extensor tendons and fascia dorsally and the interosseous muscles and metacarpals palmarly. Infection involving this space is typically secondary to dorsal penetrating injuries of the hand. In contrast to other deep space infections, dorsal subaponeurotic space infections are accompanied by significant soft tissue swelling. Dorsal longitudinal incisions over the second and fourth metacarpals are used for drainage.


III. Bacterial Infections



  • Cellulitis

    Cellulitis is a soft tissue bacterial infection that must be differentiated from an abscess. It presents with the four cardinal signs of inflammation—rubor, calor, dolor, and tumor. It is also important to know that cellulitis in the hand may occur secondary to septic arthritis or osteomyelitis. When aspirating a joint in search of infection, placement of the needle through an area of cellulitis should be avoided as this could potentially seed the joint.



    • Diagnosis is usually made on physical examination. Results of laboratory studies such as sedimentation rate and C-reactive protein level, though not always elevated, can sometimes be used to follow the course of treatment. Most frequently, cellulitis results from trauma to the skin and subcutaneous tissues. Other causes include chronic ulceration, lymphedema, and dermatitis. Group A beta-hemolytic streptococcus is the most common causative organism followed by Staphylococcus aureus.



    • Treatment of primary cellulitis includes antibiotics, elevation, and immobilization. If the organism and its sensitivities are known, antibiotics are directed accordingly. Otherwise, coverage for both Staphylococcus and Streptococcus is needed. For mild, early cases, oral antibiotics are adequate. Oral antibiotics of choice are dicloxacillin and cephalexin. Clindamycin or erythromycin can be used for penicillin-allergic patients. If improvement is not noted within 48 hours or if the infection is more severe, intravenous antibiotics (cefazolin or vancomycin for penicillin-allergic patients) are initiated. If the area of cellulites does not resolve with antibiotics, the treating physician must rule out a localized fluid collection, or abscess. Ultrasound and MRI may be useful adjuncts to clinical examination. The patient is observed closely in the hospital and the possibility of a deeper infection is again considered. Once resolution is noted, oral antibiotics are given for 7 to 10 more days.


  • Subcutaneous abscess

    A subcutaneous abscess typically occurs after a puncture wound or in response to a retained foreign body.



    • Diagnosis—Clinical findings include those described for cellulitis as well as an area of fluctuance.


    • Treatment involves incision and drainage of the localized abscess and removal of any foreign material. Cultures are obtained before antibiotic administration, and the wound is packed open to encourage continued drainage. The hand is immobilized and elevated. The packing is removed 12 to 24 hours after incision and drainage, and whirlpools, soaks, or moist to dry dressing changes are begun. The wound is allowed to close by secondary intention if no vital structures are exposed. Delayed primary closure can be performed once the infection is eradicated. Depending on infection severity, either oral or intravenous antibiotics are initiated. The most common causative organism is S. aureus. A first-generation cephalosporin is the antibiotic of choice. If the puncture wound occurred in a farm setting (or other contaminated environments), penicillin is added to cover clostridia. In diabetic patients and intravenous drug users, the organisms most commonly involved are Streptococcus and Staphylococcus. In addition to the first-generation cephalosporin, Gram-negative coverage (gentamicin) must be provided.


  • Osteomyelitis

    Osteomyelitis in the hand typically results from an open fracture. The frequency ranges from 1% to 11% and is highly dependent on the degree of damage to the soft tissue envelope. Less frequently, bone infections are iatrogenic, caused by procedures such as open or percutaneous stabilization of closed fractures and placement of external fixator pins. On occasion, direct spread from a local soft tissue or joint infection or hematogenous spread from a more distant source can cause a bone infection. Bone infections may occur more commonly in patients with peripheral vascular disease or systemic illnesses such as diabetes, immune compromise, and intravenous drug or alcohol abuse.



    • Diagnosis

      Symptoms include persistent or recurrent swelling, erythema, pain, and sometimes drainage. Erythrocyte sedimentation rate, C-reactive protein level, and white blood cell count may be elevated. C-reactive protein level is more reliable than erythrocyte sedimentation rate for following the response to treatment. Radiographic changes include osteopenia and periosteal reaction.
      These findings are usually not apparent at the initial presentation. They tend to appear 2 to 3 weeks after the development of symptoms. A sequestrum may be seen late. Sequential technetium-gallium scans and labeled white blood cell scans, such as indium-labeled leukocyte scans, are helpful in making the diagnosis. Magnetic resonance imaging may help define the presence and extent of the infection.


    • Treatment



      • Antibiotics are sometimes used alone to treat osteomyelitis in its earliest stages.


      • Most commonly, successful treatment is predicated on effective surgical debridement combined with intravenous antibiotics. If a sequestrum is present, all necrotic bone must be debrided. Antibiotic coverage is aimed initially at the most common organism, S. aureus (or another pathogen if the history indicates). It is then tailored according to culture results and clinical response. Once initial clinical improvement is documented, antibiotics are continued for 4 to 6 weeks on an outpatient basis, usually with a peripheral intravenous catheter. Normalization of the C-reactive protein level, wound status, and type of infecting organism are used to determine the length of antibiotic treatment.


      • In the case of an infection associated with acute fracture with internal fixation in place, the fixation is maintained as long as the construct is stable and the fracture has not yet united. The internal fixation may be exchanged, or alternative fixation such as external fixation may be provided if the implant is not functional.


      • If osteomyelitis develops in a healed fracture, the implant is removed and necrotic bone debrided. The goals of surgical management are to remove all necrotic tissue, eradicate dead space, provide healthy soft tissue coverage, obtain fracture healing, and restore function.


      • After the infection has been eliminated, reconstruction of bone defects may be required. Defects less than 1.5 cm may be treated by cancellous bone grafting. Larger defects and those critical for structural stability may require corticocancellous bone grating after debridement or as a staged procedure. Staged reconstruction uses an antibiotic-impregnated polymethylmethacrylate spacer to fill dead space and provide local antibiotic infiltration. The second-stage reconstruction of the bone defect is considered when there is no evidence or persistent infection, which in general is 4 to 6 weeks after the first stage.


  • Septic arthritis

    As in other joints, septic arthritis in the hand can have permanent, detrimental effects if untreated. Cartilage destruction is mediated by bacterial toxins and enzymes produced primarily by the bacteria as well as the synovial and reticuloendothelial cells. Further damage occurs as the joint pressure increases, impeding synovial blood flow. A joint infection may be caused by direct trauma as well as by local or hematogenous spread. In an adult, hematogenous spread most frequently occurs in an individual already weakened by systemic disease.

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May 23, 2016 | Posted by in Hand surgery | Comments Off on Infections

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