Surgical Treatment of Septic Arthritis 

Septic arthritis is a rather rare but important disease characterized by inflammation of a synovial membrane with purulent effusion into the joint capsule, usually due to bacterial infection.[1, 2] It typically affects monoarticular joints. This disease entity also is referred to in the literature as bacterial, suppurative, purulent, or infectious arthritis. Septic arthritis usually is divided into gonococcal arthritis and nongonococcal arthritis; clinical and treatment regimens for the two types differ.[3]

The age range of those affected is broad, extending from the neonatal period to advanced age.[4, 5, 6, 7, 8, 9, 10]  In adults, septic arthritis most commonly affects the knee; in children, infection into the hip joint predominates.[6, 11, 12, 13]  Septic arthritis in neonates and infants can be especially treacherous as a result of blunted inflammatory signals or confounding infection at a distant site (eg, an ear or an umbilical catheter site).[14]

Despite advances in diagnostic studies, powerful antibiotics, and early drainage, significant joint destruction commonly occurs.[15]  Septic arthritis can also cause many complications, including osteomyelitis, bony erosions, fibrous ankylosis, sepsis, and even death.

Treatment consists of a combined medical and surgical approach.[16, 17, 18, 19, 20, 21, 22]  On a macroscopic level, controversy still abounds as to which surgical drainage procedure serves the patient best. Barriers to successful management include lack of clinical suspicion in the early phase of presentation, delay in definitive diagnostic needle aspiration, and failure to provide adequate drainage of the joint.

For patient education resources, see the Arthritis Center, as well as Knee Pain.

Pathophysiology

Collins et al found that synovial fluid TREM-1 (triggering receptor expressed on myeloid cells-1) expression is increased in septic arthritis and rheumatoid arthritis.[23]  According to the authors, in patients with acute inflammatory arthritis, elevated synovial fluid TREM-1 levels may help point to a diagnosis of septic arthritis or rheumatoid arthritis. Moreover, in patients with rheumatoid arthritis, targeting TREM-1 may provide therapeutic benefit by reducing local proinflammatory cytokine and chemokine release.

Pessler et al, in an analysis of the synovium in patients with chronic pyogenic arthritis, identified extensive neovascularization and cell proliferation, persistent bacterial colonization, and heterogeneous inflammatory infiltrates rich in CD15+ neutrophils.[24]

Future research will focus on targeting bacterial factors and immunologic factors that worsen infection.[25]  For example, aside from the excessive amount of pus (and pressure) created by Staphylococcus, the organism also produces staphylokinase, which helps destroy cartilage further. Targeting this enzyme may prove to be beneficial.

In addition, targeting host cell cytokine responses also may prove to be beneficial. For example, interleukin-1 is known to inhibit glycosaminoglycan production, in addition to producing collagenases and metalloproteinases that overwhelmingly destroy cartilage.

If rapid improvement is not achieved with needle aspiration, open drainage and lavage (arthroscopically or via arthrotomy) is strongly recommended. Considerations related to specific joints are outlined below.

Hip

Whereas sepsis of the native hip joint is uncommon in adults, it is observed with relative frequency in infants and toddlers. In the evaluation of a young child with acute-onset hip or thigh pain, care must be taken to rule out this diagnosis by means of laboratory tests and aspiration. The diagnosis of purulent arthritis of the hip is an absolute indication for surgical drainage; repeat aspiration is arduous for the surgeon and uncomfortable for the patient.

Standard approaches to the hip joint are appropriate for drainage in cases of septic arthritis. In children, the preferred approach for most surgeons is the anterior Smith-Petersen approach. In adults, additional options include the anterolateral Watson-Jones approach and the posterolateral approach, depending on the surgeon’s comfort level.

Knee

Needle aspiration of purulent exudate is the primary method of drainage. Daily joint aspirations are usually required until the joint cultures are negative. The knee joint is probably the joint that is most amenable to repeated aspirations. Most cases of uncomplicated septic arthritis of the knee can be treated satisfactorily by means of repeated closed needle aspirations.

A surgical approach to drainage should be considered in the following situations:

• If signs of local sepsis do not abate and synovial fluid analysis does not return to normal within 2 days after treatment
• If the purulent fluid becomes too thick to aspirate
• If septic arthritis occurs in the setting of rheumatoid arthritis ^[26]  or another underlying joint disease

In selected patients, tidal irrigation might be beneficial.

Shoulder

Glenohumeral sepsis is often diagnosed at a late stage in this debilitated patient population. When the diagnosis is finally confirmed, treatment can be complicated by advanced joint destruction, including synovitis, purulent loculations, osteomyelitis, erosion of the rotator cuff, and extra-articular extension. Therefore, recurrent aspiration may not be the optimal mode of treatment for this joint, especially considering the technical difficulty of shoulder arthrocentesis (in addition to the patient’s discomfort).[27]

The literature regarding optimal treatment algorithms has often been confusing at best, with reports in medical journals championing conservative treatment and those in orthopedic journals claiming superior results with early operative drainage. Furthermore, even among those who recommend surgery, debate continues regarding the efficacy of arthroscopic versus open debridement. Some generalizations, however, can be made, including the following.

If diagnosed early (< 1 week after the onset of symptoms), a septic shoulder may be treated with serial aspirations and intravenous (IV) antibiotics.[28]  The joint should be tapped dry once or twice daily and fluid sent for cell count each time (the first specimen only for culture). By following the synovial white blood cell (WBC) count, which should steadily decline after the first two or three aspirations, along with the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level, the clinician can monitor the efficacy of treatment (see Periprocedural Care).

Some authors report encouraging results with drainage from an indwelling percutaneous catheter placed under fluoroscopic guidance. The high incidence of local joint pathology, including rotator cuff tears, adhesions, and arthritis, may make any attempts at percutaneous evacuation of the joint space quite difficult.

Arthroscopic irrigation and debridement allow for adequate decompression of the glenohumeral joint and subacromial bursa. However, a limited open exploration of the deltopectoral interval may be necessary to eradicate abscesses surrounding the biceps tendon. Patients requiring these procedures should be identified with preoperative imaging (see Periprocedural Care).

A formal arthrotomy should be strongly considered for patients with extensive osteomyelitis, retained hardware, virulent organisms, or postoperative infections.

No formal guidelines define this timeframe, though several studies suggest that patients diagnosed within 1 month of symptoms have a more favorable prognosis.

Elbow

Once the diagnosis of a septic elbow has been established and the appropriate antibiotic regimen started, repeated arthrocentesis should be performed as needed to help reduce the bacterial load and intra-articular pus.

Elbow arthroscopy is necessary when arthrocentesis fails to obtain an appropriate amount of joint aspirate for diagnosis.[29]  The clinical results of repeated needle arthrocentesis are similar to those that accompany arthroscopy and arthrotomy in more accessible joints such as the elbow. However, if the infection fails to improve with antibiotics and repeated arthrocentesis within 5-7 days, arthroscopy or arthrotomy should be performed for drainage and debridement.

The threshold for surgical intervention should be lower in patients with comorbid conditions, such as prosthetic elbow implants, diabetes mellitus, rheumatoid arthritis, immunocompromised states, or other systemic illnesses.

Wrist

Indications for aspiration include the following:

• Thick purulent material that cannot be removed by a needle
• Infection with loculations
• Failure to respond to multiple aspirations and appropriate antibiotics
• Immunosuppression

A retrospective comparison by Sammer and Shin of 36 patients (40 wrists) with septic arthritis of the wrist treated between 1997 and 2007 with either open or arthroscopic irrigation and debridement showed that arthroscopic irrigation and debridement is an effective treatment for patients with isolated septic arthritis of the wrist.[30]

In this study, patients treated arthroscopically had fewer operations and a shorter hospital stay than patients who received open treatment; however, these benefits were not seen in patients with multiple sites of infection.[30]  The 90-day perioperative mortality was 18% in the open-treatment group and 21% in the arthroscopy group.

Generally, few contraindications for arthrocentesis exist. One caveat to consider is that aspirating from an area that has an established overlying soft-tissue infection should be avoided, because it may introduce bacteria into an otherwise uninfected joint.

Patients with bleeding disorders and those who are on anticoagulant medications pose a difficult challenge, and risks must be weighed against benefits on an individual basis.

Even with proper and quick treatment of septic arthritis, the prognosis remains poor. In general, the prognosis is proportional to the following factors:

• Virulence of the offending pathogen - Gonococcal infections have the best treatment outcomes, whereas infections involving Staphylococcus aureus and gram-negative bacilli have the worst
• Duration of infection before diagnosis and treatment
• General premorbid condition of the patient, including systemic diseases or previous arthritis

Of all the joints, the knee is the most likely to experience complete or nearly complete recovery. Patients with a septic ankle joint are less likely to recover completely without any permanent impairment than individuals without infection.

In a prospective 2-year study of 154 patients (adults and children) by Kaandorp et al, 21% of cases resulted in poor patient outcome (death or severe functional deterioration), and 33% of cases resulted in poor joint outcome (amputation, arthrodesis, prosthetic surgery, or severe functional deterioration).[31]

In retrospective review assessments of nongonococcal arthritis by Pioro et al, loss of joint function occurred in 34-50% of the general population without comorbidities. Mortality in this same population ranged from 2% to 14%.[32]

Mortality figures in patients with polyarticular sepsis and rheumatoid arthritis have ranged from 23% to 32% and from 16% to 49%, respectively.

Laboratory studies

Laboratory studies should include the following:

• Complete blood count (CBC) with differential – This often reveals leukocytosis with a left shift
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level – These are helpful in monitoring the course of treatment
• Blood cultures – These may be positive in as many as 50% of  S aureus infections, though they are very poor at detecting  Neisseria gonorrhoeae (~10% of cases prove positive)
• Urethral, cervical, pharyngeal, and rectal cultures – These have a much higher yield for  N gonorrhoeae than blood cultures do
• Synovial fluid analysis ^[33] (see Table 1 below) – This should include Gram stain, culture, cell counts, and crystal analysis

Table 1. Synovial Fluid Classification* (Open Table in a new window)

Imaging studies

Plain radiography may be performed with anteroposterior and lateral views. Findings are often normal. Radiography may be particularly helpful when considering hip involvement in young children.

Look for soft-tissue swelling around the joint, widening of the joint space, and displacement of tissue planes. In later stages of progression, look for bony erosions (see the first image below) and joint-space narrowing (see the second image below).

Ultrasonography (US) is very sensitive in detecting joint effusions generated by septic arthritis.[34]  It can be used to define the extent of septic arthritis and help guide treatment. In addition, US helps differentiate septic arthritis from other conditions (eg, soft-tissue abscesses, tenosynovitis) for which treatment may differ.

Several authors recommend including magnetic resonance imaging (MRI) in the diagnostic evaluation to rule out the presence of periarticular abscess (see the first image below), osteomyelitis (see the second image below), and septic bursitis, all of which may complicate conservative treatment and necessitate operative debridement.

Nuclear scanning may be helpful to differentiate transient synovitis from septic arthritis.

Needle aspiration

In the vast majority of cases, needle aspiration may be the best initial diagnostic and therapeutic procedure. It may allow thorough decompression of the joint, and it can be repeated serially to achieve relief of symptoms, decrease joint effusion, and clear bacteria and synovial white blood cells (WBCs). However, needle aspiration is a poor choice in joints with loculations.

Adequate drainage of a septic joint is the cornerstone of successful treatment. S aureus is the most prevalent and most virulent organism involved; without drainage, rapid destruction of the joint proceeds quickly. Methicillin-resistant S aureus (MRSA) is a growing cause of septic arthritis, particularly in elderly patients and in healthcare-associated infections.[35, 36]

In many cases, needle aspiration can serve as the initial diagnostic and therapeutic intervention. If rapid improvement is not achieved, however, open drainage and lavage (arthroscopically or via arthrotomy) are strongly recommended. Head-to-head comparisons have not yet provided decisive answers regarding the benefits of one surgical modality over another.[16, 5]

Arthroscopic drainage and lavage can be used either initially or after initial needle decompression fails to provide relief of infection. It is a good procedure for decompression of elbows, knees, and ankles.

A retrospective review of 46 cases of septic arthritis in 46 patients found arthroscopic treatment to be indicated in all patients who have septic arthritis of native joints.[37]  Johns et al found arthroscopic treatment to be preferable to open treatment in both adult and pediatric patients with acute septic arthritis of the knee.[38, 39]  

Arthrotomy is the best procedure for bacteria deeply embedded in a joint and for loculations. It is especially helpful for drainage of shoulders and hips. Böhler et al found open arthrotomy to be superior to arthroscopy for septic arthritis of the shoulder.[40]

In a retrospective 8-year cohort study from a Spanish center (N = 63), Flores-Robles et al compared the functional results of initial medical treatment (ie, arthrocentesis) of native-joint septic arthritis (n = 49) with those of initial surgical treatment (ie, arthroscopy or arthrotomy; n = 14).[41]  Although he authors did not find initial surgical treatment to be superior to initial medical treatment, they noted that about half of the patients with shoulder and hip infections that were initially treated medically required surgery eventually, which suggested that surgery might be the preferred initial approach in such cases.

The anterior Smith-Petersen approach uses the superficial interval between the sartorius and the tensor fasciae latae (TFL) and the deep interval between the rectus femoris and the gluteus medius. In small children, this is the preferred approach because it minimizes the risk of vascular injury to the femoral head and dislocation; in addition, the landmarks in small children are more easily identified anteriorly.

The anterolateral Watson-Jones approach uses the superficial interval between the gluteus medius and the TFL; the deep dissection requires partial release of the abductor mechanism and detachment of the reflected head of the rectus femoris, followed by capsulotomy.

The posterolateral approach splits the fibers of the gluteus maximus and detaches the external rotators to expose the posterior capsule.

With all approaches, the capsule is left open after copious lavage; the muscular interval and the skin are closed over drains. Young children are placed in abduction in a spica cast with a window for dressing changes until the wound is healed. Adults are permitted protected weightbearing as tolerated after the drains are removed.

In a prospective, controlled study comparing open arthrotomy and arthroscopic drainage for the treatment of early septic arthritis of the hip in children, arthroscopic drainage was found to be effective and was associated with fewer days in the hospital than arthrotomy was (3.8 days and 6.4 days, respectively). At follow-up, 70% of the 10 patients in the arthrotomy group had excellent results, and 90% of the 10 patients in the arthroscopy group had excellent results.[42]

Minimally invasive surgery (arthroscopic drainage and arthroscopic irrigation) is helpful in breaking down loculations, draining purulent material, debriding necrotic tissue, and providing irrigation. Arthroscopic staging of the initial joint infection may have prognostic and therapeutic implications. Arthrotomy is reserved for selected cases that fail the arthroscopic approach.

In a study from Switzerland, 76 patients with septic arthritis (78 affected joints) were treated with a combination of arthroscopic irrigation and debridement (I&D) and antibiotic therapy. The joint most commonly treated was the knee (62 instances), followed by the shoulder (10), the ankle (five), and the hip (one). The combination of arthroscopic irrigation and systemic antibiotic treatment resulted in cure in 91% of the affected joints.

In a study from Austria that included 70 patients with septic arthritis of the knee who were treated with either arthrotomy or arthroscopy, Böhler et al reported a significantly lower reinfection rate and a better functional outcome in the arthroscopy group as compared with the arthrotomy group.[43]

 

Needle aspiration of purulent exudates, once or twice a day, is the primary method of ankle drainage. The ankle is a joint amenable to repeated aspirations. However, because it is also prone to excessive swelling, fluctuations may be difficult to locate. As with all joints, if signs of local sepsis do not abate and synovial fluid analysis does not move to normal within 2 days after treatment, open surgical drainage is indicated. If the purulent fluid becomes too thick to aspirate, open surgical drainage is indicated.

Surgical drainage of the ankle joint is most safely and successfully accomplished via the posterolateral approach. With the foot in dorsiflexion, an incision is made 5 cm proximal to the tip of the lateral malleolus just lateral to the Achilles tendon. This incision is extended distally and curves along the superior border of the calcaneus for 2.5 cm. Care must be taken to protect the sural nerve and the small saphenous vein.

The anterolateral approach to draining the ankle involves making longitudinal incisions 5-7.5 cm over the joint and 1.3-2.5 cm anterior to the lateral malleolus. If purulent material persists in the medial aspect of the ankle joint, an anteromedial or posteromedial approach may be taken as well.

Arthroscopic debridement and lavage are becoming more common in the treatment of the septic ankle.[44] The ankle is flushed with 8-10 L of saline, and the drainage tubes are left in place for 36-48 hours.

Postoperative treatment includes closing the wound loosely over drains. Because of the narrow confines of the ankle joint, closed suction irrigation is not employed. Arthrotomy for prosthesis removal with meticulous debridement of all cement, abscesses, and devitalized tissues may be necessary, which is then followed by prolonged antibiotics. For chronic persistent infections, excision arthroplasty, which may or may not include fusion, may be indicated. The appropriateness of arthrodesis depends on the extent of infection and the quality of remaining bone stock.

An arthroscopic irrigation and debridement procedure is performed in either the beach chair or the lateral decubitus position, depending on the surgeon’s comfort level. In either position, standard anterior and posterior portals are used.

The posterior portal is accessed first. The skin is entered at a point 2 cm inferior and medial to the posterolateral corner of the acromion. A spinal needle, followed by the cannula, is passed through the palpable interval between the teres minor and the infraspinatus and is directed toward the coracoid. Once the joint has been entered, the inflow is connected and the camera inserted.

The anterior portal then is established under direct visualization by means of either the inside-out technique (using a Wissinger rod) or the outside-in technique (using a spinal needle). This portal is established percutaneously at a point midway between the coracoid and the anterolateral corner of the acromion.

The instruments should enter the capsule in the triangle bordered by the intra-articular biceps tendon, the superior border of the subscapularis, and the anterior rim of the glenoid.

The joint is then irrigated with several liters of fluid, and a complete diagnostic arthroscopy is performed. If an adequate specimen has not been sent already for culture, fluid and tissue samples should be obtained for the laboratory before irrigation and administration of antibiotics. A thorough synovectomy and meticulous debridement of necrotic tissue follow. The posterior cannula can then be removed and placed with the trocar into the subacromial space for further irrigation and debridement.

Arthroscopic treatment of the septic shoulder may have to be supplemented with open exploration of the biceps tendon anteriorly. A limited deltopectoral approach allows drainage of any purulence that has escaped the joint along the biceps sheath.

For surgeons who are uncomfortable with arthroscopic irrigation and debridement and for patients who have periarticular abscesses, osteomyelitis, virulent organisms, postoperative infections, or retained hardware, open arthrotomy with aggressive debridement is the treatment of choice. Most surgeons prefer the standard deltopectoral approach, followed by opening of the rotator interval. It should be noted that the rotator cuff is likely to be torn, degenerated, or scarred, resulting in abnormal anatomy. A systematic review by Memon et al did not find either arthroscopic surgery or open arthrotomy to be superior to the other for the management of shoulder septic arthritis.[45]

After synovectomy and thorough irrigation with several liters of fluid, the joint is closed over a drain with a monofilament absorbable suture. Many recommend antibiotic-impregnated polymethylmethacrylate (PMMA) cement and other antibiotic delivery systems, though such approaches have not been proved to be necessary.

For lateral drainage of the elbow, the approach is as follows:

• An incision is made over the lateral epicondyle and extended 5 cm proximally and 2.5 cm distally
• The triceps is separated from the extensor carpi radialis longus anteriorly, and the joint capsule is exposed
• The capsule is incised carefully, and the pus is evacuated
• The joint is irrigated with saline, and the skin is closed loosely over drains
• The posterior compartment can be drained through the same incision by dissecting posteriorly on the humerus and elevating the attachment of the triceps from the lateral surface of the bone
• Injury to the radial nerve should be avoided

For posterior drainage, the approach is as follows:

• Parallel longitudinal incisions are made on each side of the olecranon and continued proximally for 7.5 cm
• The incisions are deepened through the medial lateral border of the triceps aponeurosis into the posterior compartment of the joint
• Injury to the ulnar nerve should be avoided
• After treatment, the elbow is splinted at 90° and the forearm is kept in neutral rotation; active range-of-motion (AROM) exercises are started after wound healing

For lateral wrist drainage, the approach is as follows:

• A 5-cm incision is made between the abductor pollicis longus and extensor pollicis brevis tendon volarly and the extensor pollicis longus tendon dorsally
• The incision is deepened into the anatomic snuffbox, avoiding injury to the radial nerve
• The radial collateral ligament and the synovium are incised to evacuate the pus
• The joint is irrigated, and the skin is closed loosely over drains

For medial drainage, the approach is as follows:

• A 5-cm incision is made over the ulnar head between the tendons of the flexor and the extensor carpi ulnaris
• The ulnar collateral ligament and the synovium are exposed and incised distal to the ulnar styloid

For dorsal drainage, the approach is as follows:

• A dorsal longitudinal incision is made either between the extensor pollicis longus and the extensor indicis proprius tendon or between the extensor carpi ulnaris and the extensor digiti quinti proprius tendon
• The dorsal carpal ligament is incised, and the joint is entered
• After treatment, the wrist is splinted in the position of function; AROM exercises are started after wound healing

Generally, nonweightbearing status should be maintained postoperatively, with splinting in a position of function. Once signs of infection diminish, frequent passive range-of-motion (PROM) exercises should commence. As soon as infection clears, patients should gradually advance from functional splinting to isometric muscle strengthening and, finally, to AROM exercises.

Knee

When local signs of inflammation have subsided, the knee can begin to be mobilized. Continuous passive motion (CPM) devices are often employed. This approach has been shown to decrease adhesion formation, improve cartilage nutrition, and enhance clearance of purulent exudates.

Rehabilitation exercises (eg, isometric, AROM, and PROM exercises) should begin as soon as possible to prevent muscle atrophy. When the patient has achieved good range of motion, isotonic and isokinetic exercises can be initiated. Weightbearing on the joint should not be attempted until the joint has been rehabilitated fully.

Ankle

When local signs of inflammation have subsided, the ankle can begin to be mobilized. After surgical drainage, the foot is stabilized in a posterior splint in the neutral position with the ankle at 90°. The ankle is kept immobilized until the wound is healed, with progression to weightbearing and AROM exercises.

Shoulder

Antibiotics are chosen on the basis of the organism or organisms cultured from samples in consultation with an infectious disease specialist. Although there is no evidence to support a standardized duration or mode of antibiotic delivery, it is usual to give a combination of intravenous (IV) and oral antibiotics for a total of 4-6 weeks. Response to treatment should be assessed with serial physical examinations and assessment of C-reactive protein (CRP) values.

PROM exercises should begin as soon as the patient is comfortable and able to tolerate them.

The most common complication of the septic joint is failure to resolve the infection and progression of articular cartilage damage, severe degenerative changes, and profound functional loss. These changes often result in arthroplasty[46] or arthrodesis[47] and, in the worst case, amputation. Irreversible destruction of the joint occurs in a large percentage of patients despite proper treatment.

Secondary infection in open wounds is the most common complication for open drainage techniques. In patients with compromised immune systems or debilitating diseases, infections from open wounds may spread into soft tissues and tissue planes.