Septic Arthritis of the Elbow

The Problem

The elbow is the third most commonly infected joint, after the knee and hip, representing 10 – 15% of septic joint cases. Predisposing risk factors for septic arthritis include rheumatoid arthritis, diabetes, systemic lupus erythematosus, IV drug use, steroid administration, HIV, malignancy, and advanced age. Bacterial seeding of the joint may occur through a hematogenous route (e.g., IV drug use), direct inoculation (e.g., trauma), or contiguous spread from an adjacent infection (e.g., cellulitis, abscess, septic bursitis). A myriad of microorganisms have been implicated in septic arthritis (See Table I).

The host’s inflammatory response to the infection, through the release of proteolytic enzymes and IL-1, is primarily responsible for the destructive cartilage changes seen in septic arthritis. Injury to the cartilage may occur within 8 hours, so prompt diagnosis and treatment is crucial for joint preservation.

Clinical Presentation

Pain is an essential component of the constellation of symptoms associated with septic arthritis of the elbow. It may be described as a deep, poorly-localized pain within the elbow, often acutely exacerbated by attempted range of motion. Septic arthritis can also manifest as an inability to bear weight on the affected upper extremity. Fevers may accompany septic arthritis, indicating a systemic source or spread. The patient may appear toxic, especially in more advanced stages of the infection.

Diagnostic Workup

On physical examination, the affected elbow will often appear warm, erythematous, and tender to palpation. An overlying cellulitis or abscess may be present and should be noted. Swelling about the elbow with a concomitant joint effusion are seen. Flexion and extension of the elbow, and perhaps supination-pronation, will be limited secondary to extreme pain.

Imaging Workup:

Radiographs: AP, lateral, and oblique views of the elbow should be obtained. These may demonstrate joint space widening or effusion. Anterior and/or posterior (more sensitive for inflammation) fat pad signs may be evident.

Ultrasound: Although not routinely utilized, ultrasound may help guide joint aspiration and confirm an effusion.

MRI: This modality may detect non-specific synovial thickening and enhancement, effusion, peri-articular myositis, or bone marrow edema from adjacent bone involvement (e.g., osteomyelitis).

Laboratory Workup:

Peripheral Blood: Reveals elevated WBC (> 10,000), ESR (> 30), and CRP (> 5). Blood cultures should also be obtained. [Note that actual threshold values may vary depending on the laboratory standards.]

• WBC: Will also have a left shift.

• ESR: Rises after 2 days of infection, normalizes 3 – 4 weeks after the initiation of appropriate treatment.

• CRP: Rises within hours after infection, normalizes after 1 week. CRP is the more sensitive indicator.

Elbow Joint Aspiration:

The gold standard for diagnosing joint infection. Aspirate should be sent for WBC count with differential, gram stain, culture (aerobic and anaerobic), crystal analysis, and acid-fast staining.

Findings: Aspirate is purulent or cloudy. WBC > 50,000 – 80,000, PMNs > 75% in a native elbow. In the setting of an elbow prosthesis, WBC > 1,100, PMNs > 65% suggestive of an infection. Be sure to check crystal results to assess for gout (monosodium urate) and pseudogout (calcium pyrophosphate), as gouty attacks present similarly to a septic joint.

Aspiration Technique: Access to the elbow is achieved through a lateral approach.

1. Place patient supine with elbow at 45 degrees of flexion and hand in neutral position.

2. Prep skin along lateral aspect of elbow with alcohol and povidone-iodine.

3. Using a 20-gauge needle with a 5 – 10 mL syringe, penetrate the region of the elbow in the middle of a triangle formed by the lateral epicondyle (proximally), radial head (distally), and olecranon process (posteriorly).

4. Aiming needle towards the medial epicondyle, advance slowly until intra-articular.

5. Aspirate synovial fluid and dispense into sterile collection tubes for analysis.

6. Clean skin and apply dry dressing to the puncture site.

Non-Operative Management

Non-operative treatment alone for septic arthritis of the elbow is rarely indicated as the sequelae, such as destruction of the joint and progressive osteomyelitis, can lead to significant pain and functional deficits. Reserved for patients with substantial co-morbidities that preclude an operative intervention. Entails the administration of intravenous antibiotics. Empiric antibiotics should be initiated immediately after joint aspiration, with the patient ultimately transitioned to pathogen-specific antibiotics based upon culture and sensitivity results from the aspirate. The duration of antibiotic therapy is typically 2 – 6 weeks. (See Table II)

Indications for Surgery

Given its destructive nature, septic arthritis of the elbow is considered an orthopaedic emergency and should be managed surgically. Options include open or arthroscopic irrigation and debridement of the elbow. In the setting of an infected elbow replacement, consideration should be made towards removal of the prosthesis with placement of an antibiotic spacer. Following surgery, antibiotic therapy should proceed as outlined in “Non-Operative Management.”

Surgical Technique

Open Irrigation and Debridement

An anterolateral approach to the elbow is typically performed. The intermuscular plane is between the brachialis and brachioradialis (proximally) and the pronator teres and brachioradialis (distally).

Specific steps for technique:

1. Place patient supine with upper extremity on radiolucent arm board.

2. Prep elbow/upper extremity in usual sterile fashion.

3. Make a curved incision 5 cm proximal to flexion crease along lateral border of biceps and extend distally along medial border of the brachioradialis.

4. Incise deep fascia along the medial brachioradialis.

5. Develop interval between pronator teres and brachioradialis distally.

6. Incise elbow joint capsule between the brachialis and radial nerve.

7. Obtain intra-operative fluid and tissue cultures.

8. Debride any necrotic tissue.

9. Copiously irrigate the joint with 6 – 9 liters of sterile normal saline.

10. May place drain if concerned for continued purulence/drainage.

11. Close capsule, skin.

Arthroscopic Irrigation and Debridement

Surgeon preference determines whether the arthroscopy begins at the medial or lateral aspect of the elbow.

Specific steps for technique:

1. Place patient supine-suspended (shoulder abducted 90 degrees, elbow flexed 90 degrees, forearm/wrist/hand in traction), prone (stabilize arm with holder), or in the lateral decubitus (shoulder flexed to 90 degrees over a bolster) position.

2. Apply tourniquet (sterile or non-sterile) set to 250 mmHg, and prep upper extremity in usual sterile fashion.

3. Gravity exsanguinate the limb, inflate tourniquet, and then insufflate elbow joint with 20 – 30 mL of saline through the lateral elbow (same site as described for aspiration in “Diagnostic Workup”).

4. Establish anterolateral portal over the radiocapitellar joint 1 – 2 cm proximal to the lateral epicondyle and one finger-breadth anterior to distal humerus.

5. Create anteromedial portal 2 cm proximal to medial epicondyle and one finger-breadth anterior to intermuscular septum under direct visualization using an inside-out technique.

6. Using a 4.0 mm 30 degree arthroscope and a 4.8 mm motorized shaver, debride purulent/necrotic synovium and loose cartilage.

7. Obtain intra-operative fluid and tissue cultures.

8. Copiously irrigate the anterior joint with 6 – 9 liters of sterile normal saline.

9. Establish posterolateral portal for the arthroscope 3 cm proximal to the tip of the olecranon.

10. Create direct posterior portal for shaver also 3 cm proximal to the tip of the olecranon but medial to the posterolateral portal.

11. Debride posterior aspect of elbow joint.

12. Close portal sites.

Pearls and Pitfalls of Techniques

Pearls

For open procedures, ligate the recurrent branches of the radial artery and branches to the brachialis below the elbow to permit improved retraction.

For arthroscopic procedures, insufflate the joint to facilitate distention for safe entry of instruments.

Assess the stability of the ulnar nerve prior to making medial portals. Subluxation increases risk of injury.

Pitfalls

Do not forget to obtain intra-operative fluid and tissue cultures. While antibiotic therapy may have already been initiated by the time of surgery, which could obscure cultures, the results can be highly valuable in guiding treatment.

Avoid aggressive suctioning that could lead to neurovascular injury.

Carefully monitor fluid pressures during arthroscopic surgery to minimize fluid extravasation and compartment syndrome.

Potential Complications

• Persistent elbow joint infection (possibly leading to osteomyelitis) due to inadequate irrigation and debridement or inappropriate antibiotics.

• Neurovascular injury during surgical treatment (e.g., radial nerve, PIN, recurrent branch of the radial artery).

• Elbow stiffness.

• Articular cartilage injury.

• Synovial fistula formation.

• Breakage of instruments.

Post-operative Rehabilitation

Patient may be placed in a long-arm posterior slab splint for post-operative comfort. Initiate passive and active range of motion of the elbow (flexion, extension, supination, pronation) with weight-bearing as tolerated promptly to avoid stiffness. After irrigation and debridement with initiation of antibiotics, monitor WBC count, ESR, and CRP levels to assess the response to therapy.

Outcomes/Evidence in the Literature

Sharff, K, Richards, E, Townes, J. “Clinical management of septic arthritis”. Curr Rheumatol Rep. vol. 15. 2013. pp. 332(Initial empiric antibiotic therapy should be based upon patient presentation and gram stain results since there is no overall clinical or outcomes advantage of one regimen over another.)

van den Ende, K, Steinmann, S. “Arthroscopic treatment of septic arthritis of the elbow”. J Shoulder Elbow Surg. vol. 21. 2012. pp. 1001-1005. (Arthroscopic irrigation and debridement of a septic elbow results in generally favorable outcomes.)

van den Ende, K, Steinmann, S. “Arthroscopic treatment of septic arthritis of the elbow”. J Shoulder Elbow Surg. vol. 21. 2012. pp. 1001-1005. (In this small series, maximum outcome scores were achieved when arthroscopy was performed within 2 days after the onset of symptoms. Note: "OES" refers to "Oxford Elbow Score" and "MES"denotes "Mayo Elbow Score.)

Summary

Septic arthritis of the elbow can be caused by a variety of pathogens, most commonly S. aureus. Given the potential for cartilage degradation and joint destruction, a septic elbow is considered an orthopaedic emergency requiring prompt diagnosis and treatment. Elbow joint aspiration and fluid analysis is the gold standard for diagnosis. Surgical options include open or arthroscopic irrigation and debridement of the joint. Appropriate intravenous antibiotic therapy should be promptly initiated and tailored to cultures obtained from joint aspiration and surgery. An infectious disease specialist should be consulted.

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