Some key principles are relevant when surgically managing infections of the upper limb. The context of the patient’s general health status is always important and a diabetic with renal problems is at high risk of systemic complications from a severe hand infection. There is a high likelihood of ending up with amputation of the affected digit anyway with this severe an infection in this patient group1; therefore, the option of primary amputation should be considered to reduce overall risk to the patient and to reduce the number of procedures required. Even if a primary amputation is completed, the wounds will still need to be left at least partially open to drain and at least one further procedure is likely to be required to check that there is no progression of tissue changes requiring further debridement and to close wounds where appropriate. It is standard practice to use a tourniquet for incision and drainage of an infected upper limb, as this facilitates a clear, blood-free view of structures during debridement. The Esmarch bandage is a rubber band that is used to wrap the hand and forearm for exsanguination before inflation of a tourniquet. Gentle gravity exsanguination is preferred in infected cases to reduce the risk of causing bacteremia. Incisions should be designed to allow adequate access while minimize subsequent wound healing and scar complications. In particular, longitudinal incisions across flexion creases should be avoided, as they are likely to lead to scar contractures. As with all hand surgery explorations, incisions should be designed to place scars within skin creases where possible and facilitate good access. Using larger access incisions is generally recommended in severe soft-tissue infections to facilitate accurate debridement and drainage. Some exceptions include mild flexor sheath infections, which can be irrigated with minimal access incisions if not responding to nonoperative management. One proximal incision in the distal palm, and one distally at the level of the DIP joint can be adequate for irrigation if pus is thin. Bruner’s incisions are commonly used in hand surgery, but in the scenario of a severe hand infection, there is a risk of skin flap necrosis leading to exposure of critical structures and wound healing problems.2 Therefore, a midlateral approach is preferable if the whole finger needs to be opened. This also has the advantage of less pain and swelling during the early healing period which in turn facilitates more effective early mobilization and reduced stiffness. Popular access incisions for draining hand infections are illustrated in Fig. 95.1. Copious Fig. 95.1 Incision placement for access in the hand. irrigation of infected wounds is required, and this is often best done with a large saline bag and an intravenous administration set. Following surgery, early active mobilization is optimal to reduce postoperative edema, stiffness, and loss of joint motion.
2. Osterman M, Draeger R, Stern P. Acute hand infections. J Hand Surg Am 2014;39(8): 1628–1635, quiz 1635 is generally caused by a bacterial infection with Staphylococcus aureus and is associated with nail biting and minor trauma. First-line treatment is oral antibiotics, hand baths, and rest/elevation of the affected digit. In cases unresponsive to conservative management, it is necessary to drain the abscess and/or remove the nail plate. Chronic infections are more likely to be fungal and may require marsupialization or nail ablation in cases resistant to medical management. Pulp space infections are called felons. They can coexist with paronychia but are different entities. They are treated with incision and drainage plus antibiotics.1
The differential diagnosis in this patient is herpetic whitlow or a felon/paronychia. Given the appearance of vesicles, the mild swelling, and the history of prodromal burning provided, herpetic whitlow is the most likely diagnosis. This condition is generally self-limiting and is caused by infection with herpes simplex virus.1 De- roofing a vesicle allows a Tzanck smear to be performed for diagnostic purposes, but debridement and release of fluid is not recommended because this can lead to viral spread. In severe cases, usually in immunocompromised patients, viral spread can result in encephalitis and even death. Herpetic whitlow should be treated with application of a dry dressing to reduce contact with the lesion, unless there is concern regarding superimposed bacterial infection (which is not evident in this case). There is no indication here for either antibiotics or antiviral medications in an otherwise healthy patient. A secondary bacterial infection would require debridement of purulent vesicles and a course of antibiotics.2
This patient displays signs of a horseshoe abscess (Fig. 95.2). Parona’s space is located in the distal forearm between pronator quadratus and the flexor digitorum profundus tendons. An infection of either the little finger or thumb flexor sheaths can spread by a communication through the ulnar and radial bursae into Parona’s space. This explains why a patient can have an injury in the little finger presenting with a thumb flexor sheath infection. Other important spaces in the hand that may become infected are the midvolar, hypothenar, thenar, and interdigital spaces. Midvolar infections present with central palm pain and swelling with loss of concavity between thenar and hypothenar eminences. Thenar space infections present with local swelling and pain, which is worse on thumb opposition. Hypothenar space infections are rare and present with swelling and pain on little finger opposition. Collar button abscesses can form in the interdigital web spaces. They present with loss of web space contour and tenderness within the affected web space. Any suspected infected collections in the hand require urgent surgical drainage, usually supplemented with antibiotics. The normal surgical principles apply.1
Kanavel’s four cardinal signs of a flexor sheath infection are: 1. Severe pain on passive extension of the digit 2. Fusiform swelling of the digit 3. Tenderness over the flexor tendon sheath 4. Partially flexed posture of the digit (added later to the original description) This patient displays all of these signs, as is quite typical for a more advanced infection. Some flexor sheath infections that present early with mild symptoms can be managed adequately with antibiotics, mobilization, and splinting alone.1 This is not usually effective for infections associated with a penetrating wound. This patient requires urgent surgical drainage because there is pus evident and there has been delayed management of the initial penetrating injury. Ideally, minimal access incisions are used for flexor sheath washout, provided the sheath can be irrigated well. This enables a quicker and more comfortable rehabilitation and reduces the likelihood of wound healing problems. At least a degree of palmar wound extension will be required in this case to explore and debride the initial puncture wound. With pus leaking from the palm, there is likely to be thicker pus in the sheath that will require more extensive access than an early infection would in order to irrigate adequately. The most common pathogen in flexor sheath infection is S. aureus alone, rather than a polymicrobial cause. Polymicrobial infections are more common in diabetic and other immunocompromised patients. Treatment is usually with a single penicillin-based antibiotic such as amoxicillin with clavulanic acid or flucloxacillin. This Fig. 95.2 Radial and ulnar bursas communicating with Parona’s space may cause a horseshoe abscess. Conduit for horseshoe abscess Abscess Radial bursa Ulnar bursa patient has two risk factors for a poor outcome following flexor sheath infection: age over 43 years and the presence of subcutaneous pus. Level II evidence has shown a number of other risk factors for poor outcome, which include the presence of diabetes, peripheral vascular or renal disease, and the presence of digital ischemia.1, 2
Primary wound closure should be avoided in a “fight bite” and is definitely contraindicated if there is frank pus. Any tendon repair should be delayed until the wound is clean, and a monofilament suture is preferred to further reduce the risk of bacterial colonization at the repair site. The risk of joint capsule penetration is very high with these injuries; so, the capsule should be carefully inspected throughout the range of motion. Any resting splint should be in the safe position of immobilization and is particularly important when the hand is swollen. The wrist should be slightly extended, MCP joints flexed to approximately 70 degrees, and the IP joints straight.1 The key principles for managing these injuries are: 1. Promptly and thoroughly debride the wound edges and extend the wound to ensure adequate inspection of the tendon and joint capsule throughout the range of MCP joint motion. 2. Send deep specimens for microbiologic analysis. 3. Thoroughly irrigate the wound. Wash out the joint too if capsule is open or infected. 4. Do not primarily repair the joint capsule or tendon if there is frank pus. 5. Leave at least some part of the wound open for drainage. Consider closing the wound extensions using a monofilament nonabsorbable suture. 6. Dress the wound with a wick/pack to encourage drainage, a low-adherent dressing, gauze, wool, and crepe. 7. Apply a splint with the hand placed in the “safe” position. 8. Continue IV antibiotics and hand elevation, then reassess the wound and mobilize/soak in an antiseptic/soapy hand bath at 24 hours.
Dog bites represent 90% of all animal bites in the developed world, whereas cat bites represent just 5%. Despite this massive difference, cat bites represent three quarters of all infected bites. This is probably because their long, thin teeth are more likely to cause narrow, deep puncture wounds prone to infection. Cat bites need early treatment with antibiotics and washout and can still take a prolonged time to settle. In over two-thirds of dog bites, the animal is known to the patient. Children younger than 5 years are at increased risk of dog bites with half of all dog bites occurring in this age group. P. multocida is associated with both cat and dog bites. Therefore, antibiotics must be selected to cover these and staphylococcus, streptococcus, and anaerobe pathogens.1,2
Septic arthritis is infection of a joint space and may be primary or represent hematogenous spread from an infective source elsewhere in the body. For this reason, it is important to exclude other sources of infection, particularly in children. Streptococcus, Staphylococcus, and Haemophilus influenza are the most common pathogens involved in joint infections. Diagnosis involves a good history and clinical assessment complemented by microscopy of a joint fluid sample. Plain radiographs, blood inflammatory markers, and urate levels should also usually be requested. A joint aspirate should ideally be obtained without passing the needle through obviously inflamed or wounded skin in order to avoid seeding of bacteria into a joint which actually is not infected, and to ensure a reliable sample is obtained. Fluid analysis with WBC >50,000 per mm3 (not 10,000 per cm3) is strongly suggestive of joint sepsis. An urgent Gram stain should be requested from the lab. Joint fluid also provides the best evidence for or against a crystal arthropathy, such as gout or pseudogout, and some of the fluid should be sent for crystal analysis. An infected joint requires urgent joint washout and antibiotics. Early mobilization with hand therapy and a resting splint in a safe position is required. Untreated septic arthritis may quickly and irreversibly erode the articular cartilage, resulting in arthritic changes and increasing the risk of progression to osteomyelitis.1
Gas gangrene is uncommon in the upper extremity but is a severe life-threatening infection caused by Clostridium species. There are more than 60 subtypes of Clostridium, but perfringens is most commonly associated with gas gangrene. Clostridia produce multiple toxins which cause local tissue destruction. Management involves rapid has a high mortality rate (approximately 25%). Necrotizing fasciitis is the main differential diagnosis, and this can either be polymicrobial or caused by group A Streptococci. Many soft-tissue infections are caused by S. aureus, including paronychia, flexor sheath infection, and felon. Eikenella is implicated in some human bites as are Streptococcus viridans and Bacteroides.1
part of the distal and middle phalanges of his middle finger following a neglected infection of a mucus cyst. Cierney et al1 developed a classification for osteomyelitis that encourages consideration of both host and disease characteristics that can be useful for planning treatment. Physiologic class (host characteristics) A host: Normal host with good immune system B host: Local or systemic compromise C host: Markedly compromised host. Treatment of disease is more risky than disease itself Anatomic location Type I: Medullary osteomyelitis—limited to endosteum, most common is hematogenous cause or intramedullary fixation Type II: Superficial osteomyelitis—involves surface of bone Type III: Localized infection—both medullary and superficial; full-thickness sequestrum Type IV: Diffuse; bony instability By falling into the group C host, type IV location category of osteomyelitis, assessment of this patient is likely to guide the clinician toward a prompt, simple, low-risk local anesthetic terminalization of the affected digit rather than debridement and prolonged courses of antibiotics.2
Common fungal infections of the upper extremity include sporotrichosis and onychomycosis. Sporotrichosis is a granulomatous fungal infection of the skin or subcutaneous tissue, while onychomycosis is a fungal infection of the nail. The patient in this scenario is most likely to have a soft-tissue fungal infection acquired while gardening. The likely pathogen is Sporothrix schenckii which is typically sustained from a puncture wound during contact with rose thorns, moss, or other plants. For this reason, it is often called “rose handler’s disease.” The classic treatment described is the use of a saturated solution of potassium iodide, but this has now been supplanted by an extended oral course of itraconazole or fluconazole such as 3 to 6 months, or at least 4 weeks after resolution of symptoms. Patients tend to present with a nodule at a puncture site, which later ulcerates. This is followed by nodule formation along lymphatic channels, which then also ulcerate. A definitive diagnosis is made by fungal culture of a nodule aspirate. Onychomycosis is a fungal condition of the nail most often caused by T. rubrum. C. albicans is another common cause, particularly in diabetics. This condition results in an abnormal, thickened, and discolored nail plate. Fungal cultures are required to guide selection of antifungal therapies. For example, T. rubrum responds best to oral terbinafine, while C. albicans may require ketoconazole, itraconazole, or griseofulvin. Removal of the thickened nail plate can be useful, as it can reduce the duration required for oral antifungal therapy. Paronychia is an infection of the soft tissues surrounding the nail and can be acute or chronic. Acute paronychia is normally bacterial, whereas chronic paronychia is normally fungal. Acute paronychia is often best treated with a combination of antibiotics and wound debridement with nail plate removal. Chronic paronychia requires antifungal medication and may need marsupialization of the eponychial fold.
The patient in this scenario has developed an atypical mycobacterial infection, also known as fish tank granuloma. It is caused by Mycobacterium marinum. Typical and atypical mycobacterial infections are rare and have a broad range of subtypes. These include tuberculous infections and leprosy. The diagnosis should be suspected where there is a chronic skin nodule (as in this case), a draining sinus tract, or another infection that fails to heal within a typical timeframe. A biopsy will show granulomas with negative fungal staining. Cultures can take an extended time to process due to the slow replication of mycobacteria and empiric antibiotic selection may be indicated while these are awaited. Treatment is likely to require surgical debridement followed by an extended course of antibiotics.1,2 T. rubrum represents a fungal infection that causes onychomycosis. This is treated with oral terbinafine. P. multocida is seen most commonly in cases of infected cat bites. These should be treated with debridement and irrigation in conjunction with amoxicillin and clavulanic acid or clindamycin. Group A Streptococcus spp. can cause an aggressive, rapidly progressing soft-tissue infection in previously fit individuals. Early recognition is required alongside prompt treatment with high-dose penicillin antibiotics in the first instance. E. corrodens is a common pathogen in human bite injuries and is generally responsive to combined amoxicillin and clavulanic acid.3
Biofilms can be a problem in plastic surgery, most commonly affecting implanted devices and chronic wounds. Biofilms are implicated in a variety of clinical infections, as well as in breast implant capsular contracture. Biofilms are particularly difficult to treat because they are strongly adherent to implanted devices and less healthy/nonviable tissue. Here, they form multiorganism colonies protected beneath an exopolysaccharide matrix. This isolates them from surrounding tissues and protects them from host defense mechanisms and antibiotics. The biofilm is often inactive for extended periods of time with no evidence of infection present. It can subsequently become activated to release certain free bacteria from beneath the polysaccharide matrix which are described as being in a planktonic state. When a wound is swabbed, it is only these planktonic bacteria that can be detected rather than the true polymicrobial activity going on beneath the matrix. As a result, antibiotic concentrations 1,000 times higher than normal may be required to penetrate a biofilm. Surgical debridement of chronic wounds and removal of nonviable tissue help reduce a biofilm, and prosthetic devices are generally exchanged or removed where a biofilm is present and causing infection. Bacterial biofilms do not usually coexist with fungal spores where the genetics of the bacteria are otherwise normal. MRSA has become increasingly common in recent years as a result of antibacterial resistance; however, this is not the main reason why biofilms are difficult to treat.1
High-pressure injection injuries are a surgical emergency and can cause significant tissue damage through a small entry wound. Material is inadvertently injected into the digit at high pressure (often as high as 7000 psi). The most commonly involved digit is the nondominant index finger as the offending tool tends to be held in the dominant hand with the nondominant hand supporting the target object. These injuries need urgent surgical management with wound extension, irrigation, and tissue debridement. Both oil-based and water-based solvents can cause significant damage, but oil-based injuries tend to be worse and generate greater irritation of the soft tissues. Risk of amputation is high (up to 50%) after an oil-based, high-pressure injury such as paint injection. The entry wound does not provide much information with regard to the zone of tissue damage, so it is easy to underestimate its severity. Debridement often fails to remove all traces of injection material satisfactorily. If the fingertip is the entry point, material can frequently be identified in the forearm where it has been forced under pressure along the tendon sheath. This is in addition to the pressure insult to the soft tissues surrounding the entry point, for example, the fat of the pulp may be completely nonviable due to both barotrauma and foreign material contamination.1,2