Asif M. Ilyas
DEFINITION
Septic arthritis is defined as an infection within the closed space of a joint.
It is usually acute and purulent secondary to a pyogenic bacterial infection.
It causes irreversible damage to articular cartilage and therefore warrants prompt treatment with adequate drainage and an appropriate antibiotic regimen.
Delay in making the diagnosis and initiating treatment has serious implications for prognosis.
ANATOMY
The interphalangeal (IP) and metacarpophalangeal (MP) joints of the hand are hinge joints (FIG 1).
The IP joint space is maximized in slight flexion and the MP joint in extension.
The wrist joint includes the radiocarpal, midcarpal, and radioulnar joints. Septic arthritis may be present in all of these wrist joint spaces, concomitantly or separately, if there are no interosseous ligament perforations, as is the case in younger patients (see Fig 1).
PATHOGENESIS
Septic arthritis may affect any joint of the hand or wrist.
Septic arthritis does not have a gender or race predilection, but it is more common in adults than in children.
FIG 1 • Anatomy of the interphalangeal, metacarpophalangeal, and wrist joints.
The inoculation of the joint is most likely due to a penetrating injury (ie, lacerations, puncture wounds, and bites). Other causes include hematogenous seeding or contiguous spread.10
At the distal IP joint, septic arthritis is common from penetrating trauma as well as contiguous infection from a mucous cyst, felon, paronychia, or suppurative flexor tenosynovitis.
At the proximal IP joint, contiguous infection is most commonly related to a suppurative flexor tenosynovitis.
At the MP joint, septic arthritis is most common after direct inoculation from a clenched fist injury or fight bite.
Hematogenous spread can result from any concomitant or preceding infection of the body, including oral, upper respiratory, gastrointestinal, and genitourinary infections.
The synovium is highly vascular and contains no limiting basement membrane, promoting easy access of blood contents to the synovial space.3
The presence of bacteria within the joint induces a cellular and immunologic response that is detrimental to the joint. Bacteria rapidly replicate, producing toxins. The presence of bacteria stimulates an immunogenic response, resulting in the arrival of leukocytes, which produce proteolytic enzymes. Both the bacterial toxins and leukocytic enzymes destroy the articular cartilage of the joint by degrading proteoglycans and eventually injuring the underlying chondrocytes.
Multiple risk factors can predispose a patient to septic arthritis6 (Table 1).
Any disorder that results in an immunocompromised state can predispose to septic arthritis.
Rheumatoid arthritis, in particular, poses a high risk. This risk is related to a variety of factors including general debilitation, immunosuppressive medication, tumor necrosis factor blockers (eg, infliximab or etanercept) and chronic joint injury.
In patients with rheumatoid arthritis, a diagnosis of septic arthritis may be delayed because of misinterpretation of a rheumatoid flare. A high index of suspicion must be maintained when evaluating for septic arthritis in patients with rheumatoid arthritis.9
Virtually any microbial pathogen is capable of causing pyogenic septic arthritis (Table 2).
Staphylococcus aureus and Streptococcus spp. are the most common offending organisms.
Gram-negative, anaerobic, and polymicrobial infections also are possible, especially in IV drug abusers and immunocompromised patients.
Specific bacterial pathogens are related to certain circumstances, eg, Eikenella corrodens in human bite wounds, Pasteurella multocida after domestic animal bites, Neisseria gonorrhoeae infections in sexually active young patients, and fungal and mycobacterial infections in immunocompromised patients.
NATURAL HISTORY
The combination of the growing bacterial load and the ensuing inflammatory response results in a growing effusion that causes synovial ischemia, pressure necrosis of the cartilage, and infiltration of the bacteria into both the subchondral bone and overlying skin.
Bacterial infiltration out of the joint can result in secondary osteomyelitis, suppurative flexor tenosynovitis, and skin breakdown with spontaneous drainage.
PATIENT HISTORY AND PHYSICAL FINDINGS
Patients will complain of pain and swelling.
Systemic signs of joint infection may include fevers, chills, malaise, and tachycardia.
The patient should be asked about a history of penetrating trauma; human, animal, or insect bites; recent joint aspirations; recent infections elsewhere; and the presence of an immunocompromising condition.
On examination, patients will manifest a painful swollen joint, with overlying erythema and warmth.
The most important physical examination finding is exquisite pain with motion, in contrast to a noninfectious effusion or overlying cellulitis.
Medical professionals at the triage level may attempt to perform a regional block for pain relief. This must be prevented, because it will mask the condition.
Attempted active digital motion will result in significant guarding, and passive flexion and extension should induce exquisite tenderness.
Physical examination of the wrist often is less dramatic than that of the digits. The joint typically is held in a neutral position.
Active wrist motion also will induce guarding and passive flexion, and extension should induce exquisite tenderness.
Passive pronation and supination may help evaluate involvement of the distal radioulnar joint.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Laboratory studies should include white blood cell count (WBC), erythrocyte sedimentation rate, C-reactive protein, and blood cultures.
The WBC usually is not elevated, but the erythrocyte sedimentation rate and C-reactive protein levels are consistently elevated (unless the patient is immunocompromised).
Diagnosis of a septic arthritis is best accomplished by joint aspiration and analysis.
If infection is present, increased fluid will be present in the joint.
Joint aspirates should be sent for a cell count with differentiation, Gram stain, crystal analysis, glucose, and cultures (aerobic, anaerobic, fungal, and mycobacterial; Table 3).
Diagnosis can be made most reliably with a joint fluid WBC count greater than 50,000 (and a differential of 75% or more segmented neutrophils); a Gram stain confirming the presence of bacteria; or positive cultures.5
A low WBC count with a high percentage of neutrophils (>90%) may indicate an early septic arthritis.11
A joint glucose of 40 mg/dL or less compared with the fasting blood glucose level also suggests a septic process.7
Crystal analysis is necessary to rule out the presence of gout or pseudogout, because they also can present similarly, including an elevated WBC count in the aspirate.
The role of imaging studies early in the course of the septic process is limited. Radiographs may reveal joint distention, presence of foreign bodies, osteomyelitis, air in the soft tissues, and chondrocalcinosis—characteristic of both gout and pseudogout (FIG 2A). Later radiographs will reveal joint destruction.
MRI is effective in diagnosing early septic arthritis and in differentiating it from osteomyelitis or overlying tenosynovitis (FIG 2B).
FIG 2 • A. Radiograph showing chondrocalcinosis of the triangular fibrocartilage complex from chronic pseudogout. B. Coronal T2-weighted MRI of a metacarpophalangeal joint with underlying septic arthritis. Note the normal bone signal but the presence of high signal within the joint from the fluid and surrounding soft tissue inflammation.
DIFFERENTIAL DIAGNOSIS
Rheumatoid arthritis
Crystalline arthropathies: gout, pseudogout
Seronegative arthropathies: systemic lupus erythematosus, psoriatic arthritis, Reiter syndrome, ankylosing spondylitis, rheumatic fever
Lyme disease
Cellulitis
Osteomyelitis
Suppurative flexor tenosynovitis
NONOPERATIVE MANAGEMENT
If septic arthritis is detected or suspected early enough, antibiotics alone have been suggested in the medical literature to be sufficient to eradicate the infection.3
In cases where comorbid conditions contraindicate surgery, serial aspiration of the involved joint can be done to decrease the bacterial load, decompress the joint, and allow medical management with antibiotics to treat the infection.
This technique has been shown to be less effective than open surgical drainage in large joints and, therefore, would be even less reliable in small joints.4
SURGICAL MANAGEMENT
Septic arthritis usually is considered a surgical pathology that warrants prompt treatment.
Open and arthroscopic techniques are available for surgical drainage of the wrist.
Preoperative Planning
Arrangements for instruments, irrigation fluid, drains, sutures, and assistants should be made in advance of surgery.
Positioning
Approaches to the hand and wrist can be accomplished with the patient supine and the operative extremity extended on a hand table with the surgeon and assistants seated.
The hand table should be stable and well-secured, and should allow adequate space for both the operative limb and the surgeon’s elbow and forearm, to minimize surgeon fatigue and enhance stability.
Tourniquet use is advised to obtain a bloodless field and clear visualization of anatomic structures.
The limb usually is exsanguinated via gravity with elevation before inflating the tourniquet to avoid proximal spread of the bacteria.
A small-joint wrist arthroscopy tower should be used. This will provide positioning and application of traction during arthroscopy and also facilitate conversion to an open procedure if necessary. Additionally, small-joint arthroscopy equipment, including a 30-degree 2.7-mm camera, should be used.
Approach
Multiple approaches to a joint are available. The choice of which approach to use should be based on ease of the approach while still allowing adequate joint exposure for débridement and minimizing contiguous spread of infection.
All surgical approaches of the hand and wrist warrant a sound understanding of surface anatomy, surgical anatomy, internervous planes, and surgical technique.
TECHNIQUES
ASPIRATION OF INTERPHALANGEAL OR METACARPOPHALANGEAL JOINTS
Prepare the skin with an antiseptic wash, but avoid placing local anesthesia before the aspiration, because it may mask the location of the joint space.
As large a needle as possible should be used, preferably 18 or 20-gauge.
A syringe no larger than 3 or 5 mL should be used, because larger syringes cause too great a vacuum aspiration and collapse the joint, making them, therefore, less effective for aspiration.
The joint space can be identified just radial or ulnar to the extensor mechanism on the dorsal surface.
The needle should be inserted in a dorsal-to-volar direction with a 30to 45-degree angle toward the midline.
A palpable “pop” or sensation of entering the joint should be felt, and the joint should be aspirated.
Distraction of the joint can sometimes aid entry.
If there is resistance to aspiration, the needle should be redirected while maintaining suction on the syringe.
SURGICAL DRAINAGE OF INTERPHALANGEAL OR METACARPOPHALANGEAL JOINTS
For the MP joint, a dorsal longitudinal incision is made (TECH FIG 1A). The extensor mechanism is exposed and also incised longitudinally to expose the capsule.
Alternatively, the capsule can be exposed by incising the ulnar sagittal band.
The joint is exposed by incising the capsule dorsal to the collateral ligaments.
For the proximal IP joint, a midaxial incision is preferred to avoid injury to the central slip and creation of a septic boutonniere deformity (TECH FIG 1B).
The neurovascular bundle may be identified and retracted volarly. The dorsal sensory branches are at risk and should be retracted with the dorsal flap.
The extensor mechanism, including the lateral bands, is identified and retracted dorsally, thereby exposing the capsule laterally. The accessory collaterals (volar to the proper collaterals) are released to allow entry into the joint.
The distal IP joint can be approached through a midaxial incision or through a dorsal “H” incision and the terminal tendon retracted laterally, exposing the joint dorsal to the collateral ligaments.
Injury to the terminal tendon can result in a mallet finger and possible late swan-neck deformity.
Obtain cultures and thoroughly irrigate and débride the joint with gravity cystoscopy tubing or a bulb syringe.
In-line traction on the digit will help expose the joint space.
Inspect the joint surfaces for articular damage.
Leave a small wick in the joint to prevent premature closure of the joint capsule, and reapproximate the extensor mechanism using a monofilament suture. Avoid using deep braided sutures in the face of an infection.
Loosely close the skin around the wick with one or two 4-0 nylon sutures.
Place the hand in a volar splint for comfort and emphasize that the patient should keep it elevated.
TECH FIG 1 • A. Sample incisions for open dorsal drainage of the interphalangeal, metacarpophalangeal, and radiocarpal joints. B. Sample midaxial incision for open drainage of the interphalangeal joints.
ASPIRATION OF THE WRIST
Prepare the skin with an antiseptic wash but avoid placing local anesthesia pre-aspiration, because it may mask the location of the joint space.
As large a needle as possible should be used, preferably 18-gauge.
A syringe no larger than 5 or 10 mL should be used.
Larger syringes cause too great a vacuum on aspiration and collapse the joint, and are, therefore, less effective for aspiration.
The joint space can be identified just distal to Lister’s tubercle on the dorsum of the wrist. The needle should be angled approximately 10 degrees volar to accommodate for the normal volar tilt of the radius.
Alternatively, the joint may be easily entered through the dorsal ulnocarpal space, just distal to the triangular fibrocartilage complex.
A palpable pop or sensation of entering the joint should be felt and the joint should be aspirated. If there is resistance to aspiration then the needle should be redirected while maintaining suction on the syringe.
ARTHROSCOPIC DÉBRIDEMENT OF THE WRIST
Secure the hand and wrist in a sterile small-joint arthroscopy tower. Apply 5 to 10 pounds of traction.
Identify and mark the dorsal surface anatomy of the wrist. Specifically, palpate the dorsal and distal surface of the radius, ulna, distal radioulnar joint, and Lister’s tubercle. These landmarks will guide safe establishment of portals and maximize visualization (TECH FIG 2).
The 3–4 portal is the main “viewing” portal and should be established first to visualize the radiocarpal joint. Begin by identifying the soft spot just distal to Lister’s tubercle. The portal is bordered by the third and fourth dorsal compartments.
An 18-gauge needle is directed just distal to Lister’s tubercle and should be angled about 10 degrees volar to accommodate for the normal volar tilt of the radius. The joint is then insufflated with 5 to 10 mL of normal saline.
Create the portal with a 3-mm longitudinal skin incision using a no. 11 blade directed superiorly. Spread the soft tissue bluntly with a curved hemostat down to the joint, avoiding inadvertent penetration of the capsule.
Direct a blunt-tipped cannula and trocar into the joint, again angling about 10 degrees volar just distal to Lister’s tubercle. Avoid plunging the cannula uncontrolled into the joint, because this may cause iatrogenic articular cartilage injury.
Replace the trocar with the camera.
TECH FIG 2 • Dorsal surface anatomy of the wrist. The 3–4 and 4–5 portals are marked. The dashed lines represent approximate location of the radial sensory nerve on the radial side and the dorsal ulnar sensory nerve on the ulnar side.
Cultures can be taken through the cannula.
Systematically explore the radioscaphoid, radiolunate, and ulnocarpal joints for turbid fluid.
In addition, evaluate the scapholunate ligament and triangular fibrocartilage complex for tears that may allow the infection to communicate with the midcarpal and distal radioulnar joints, respectively.
Establish a second “working” portal. Arthroscopic equipment such as the shaver and probe will be used through this portal. A 25-gauge needle is directed into the proposed site under direct arthroscopic visualization before making the skin incision.
The 4–5 portal is identified just ulnar to the fourth dorsal compartment and just distal to the distal radioulnar joint (see Tech Fig 2).
Alternatively, a 6-R or 6-U portal can be used and can be identified just radial or ulnar, respectively, to the sixth dorsal compartment. Diligent blunt dissection with a curved hemostat must be performed before inserting the blunt cannula and trocar to avoid inadvertent injury to the dorsal ulnar sensory nerve.
The joint can be both visualized and washed through the camera cannula in the viewing portal and drained through the working portal with a cannula. Drainage can be applied to gravity or suction.
The joint can be further débrided with the aid of a shaver with suction placed through the working cannula.
Devitalized tissues and synovial shavings can be taken through the shaver.
Thorough arthroscopic débridement of the wrist should include visualization and irrigation of the midcarpal joint as well.
Palpate a soft spot about 1 cm distal to the 3–4 portal.
Place a 25-gauge needle first, and insufflate the joint with 5 mL of normal saline.
Direct a blunt cannula and trocar into the midcarpal joint just radial to the base of the capitate.
After thorough visualization, irrigation, and débridement of the wrist, insert a small Hemovac drain through the working portal cannula.
Remove the arthroscopic equipment. Close the portals with 4-0 nylon stitches.
Place the wrist in a volar splint for comfort, and encourage limb elevation and active finger motion.
OPEN SURGICAL DRAINAGE OF THE WRIST
A dorsal longitudinal incision should be placed just ulnar to Lister’s tubercle (TECH FIG 3A). The incision should be approximately 4 cm in length, with about two thirds distal to the tubercle.
Alternatively, a transverse incision may be used. Although more cosmetic, it may not provide adequate exposure.
Once the extensor retinaculum is exposed with blunt dissection, the distal third is released perpendicular to the fibers and ulnar to the third dorsal compartment.
The interval between the third and fourth extensor compartments is bluntly dissected, and the joint capsule is exposed (TECH FIG 3B).
The joint capsule is incised longitudinally, and limited flaps are raised subperiosteally off the dorsal distal radius, like an inverted T (TECH FIG 3C).
Cultures are taken, and synovial tissue should be sent for culture and histology.
The joint should be thoroughly débrided and irrigated with gravity cystoscopy tubing or a bulb syringe.
Pulse lavage should be avoided due to its potential to cause additional soft tissue injury.
The joint should be ranged during irrigation to maximize the effect of the lavage.
The joint surfaces are inspected for articular damage.
Leave a small wick or drain in the joint and loosely close the skin around the wick.
Primary closure of the joint risks reaccumulation of pus.
Typically, two to three loosely placed 4-0 nylon sutures will be sufficient.
Place the wrist in a volar splint for comfort and encourage limb elevation.
TECH FIG 3 • A. Incision for open drainage of the wrist. B. The distal third of the extensor retinaculum is released and the interval between the third and fourth dorsal compartment developed. C. The capsule is arthrotomized with an inverted T.
POSTOPERATIVE CARE
Empiric IV antibiotics are initiated immediately after obtaining cultures and then later tailored to the results of laboratory cultures and sensitivities.
IV antibiotics should be continued for 2 weeks or at least through symptom resolution, followed by oral antibiotics.8
The duration of antibiotics is the subject of some controversy. This should be determined on a case-by-case basis, with consideration of surgical findings, virulence of the offending bacterial pathogen, and the response to treatment.
Early range of motion (active and active-assisted) in diluted povidone-iodine soaks is initiated three times daily to provide mechanical lavage of the joint and to prevent premature wound closure.
The wick or drain is removed 1 or 2 days postoperatively.
As symptoms resolve, the soaks are discontinued to allow the wound to heal, and progressive range of motion exercises are initiated.
If symptoms do not improve within 2 days, then a repeat surgical drainage should be considered.
OUTCOMES
The results of surgical treatment of septic arthritis are not well-documented in the literature, and it is difficult to predict the outcome even during the course of treatment.
Functional outcome is most closely correlated to the duration of symptoms before treatment is initiated.10
Some loss of motion and joint stiffness are expected, even in cases treated with early surgical drainage and rehabilitation.1,10,12–14
Some joint space narrowing usually is seen following treatment, and significant arthrosis and ankylosis may occur in severe cases or when treatment has been delayed.
COMPLICATIONS
Joint stiffness, arthrosis, osteomyelitis, and secondary tendon adhesions
Salvage options for postseptic arthritis include arthrodesis, resection arthroplasty, or amputation.
Implant arthroplasty is controversial and is not generally recommended for a previously infected joint.
REFERENCES
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