Pyogenic Flexor Tenosynovitis: Evaluation and Treatment Strategies

Abstract

Pyogenic flexor tenosynovitis (PFT) is a common closed-space infection of the flexor tendon sheaths of the hand, which remains one of the most challenging problems facing hand surgeons. PFT goes by several names including septic or suppurative flexor tenosynovitis. Adequate treatment requires timely diagnosis and often prompt surgical treatment. However, despite prompt treatment, and regardless of the protocol used, complication rates as high as 38% have been reported in the literature. Moreover, even with successful eradication of the infection, a significant proportion of patients will suffer from continuing pain, swelling, stiffness, loss of composite flexion, weakness, and recurrence potentially requiring amputation. This review will focus on current evidence-based antimicrobial and surgical treatment strategies to maximize treatment outcomes.

Introduction

Pyogenic flexor tenosynovitis (PFT), also known as septic or suppurative flexor tenosynovitis, is a closed-space infection of the flexor tendon sheath of the hand and remains a challenging problem within the realm of hand surgery. PFT remains a common problem and has been shown to make up 2.5 to 9.4% of all hand infections. 1 2

PFT can be caused by hematogenous spread, however, local inoculation via lacerations, puncture wounds, and bites are far more common causes. 3 4 5 Sheath interconnections in the palm and Parona’s space in the forearm may allow for rapid spread proximally. Additionally, the closed nature of the sheath limits the host’s ability to fight the infection. 3

Despite timely treatment, patients may develop significant morbidity from this infection including pain, swelling, stiffness, and ultimately compromised function of the hand. Moreover, in severe cases with delayed or inadequate treatment, PFT can result in tendon rupture, soft tissue necrosis, and possibly amputation ( Fig. 1 ). 3 4 Comorbidities such as diabetes, peripheral vascular disease, and renal failure are associated with a significantly higher risk of amputations in patients with PFT. 6

Fig. 1.

(A, B) A case of advanced pyogenic flexor tenosynovitis. Despite multiple operative debridements and prolonged antibiotics ultimately requiring ray amputation.

Historical Perspective

In 1912, Kanavel initially described four cardinal signs that characterize infection of the flexor tendon sheath. 7 These signs include symmetric swelling of the entire digit, exquisite tenderness along the course of the tendon sheath, a digit with a semiflexed posture, and pain with attempted passive extension of the digit. During Kanavel’s time, antibiotic treatment was not established; therefore, the natural history of PFT was more severe and included systemic infection and even death. 8

In 1974, Michon developed a three-tiered staging system for PFT based on intraoperative findings. 9 In the first stage, there is increased serous, exudative fluid in the tendon sheath. In the second stage, purulent fluid causes progressive distension of the tendon sheath; however, the tendon is still viable. In the third stage, there is septic necrosis of the tendon and the pulleys. Michon proposed that stages 1 and 2 could be treated with limited incision with drainage and irrigation of the sheath, whereas stage 3 should be treated with open debridement.

With the advent of antibiotic treatment, the incidence of catastrophic sequela associated with PFT has decreased dramatically. 6 Currently, antibiotics in combination with surgical intervention are the mainstay of treatment. There is, however, no consensus regarding the timing or type of operative treatment in PFT.

Microbiology of Pyogenic Flexor Tenosynovitis

As PFT is most commonly caused by penetrating trauma to the digit, the most common culprit causing PFT is skin flora. In numerous studies, Staphylococcus aureus was found in up to 75% of positive cultures. 1 5 10 11 Methicillin-resistant S. aureus (MRSA) is another common cause and has been found in up to 29% of cases and the incidence continues to grow. 12 13 Other prevalent but less common causative organisms include Staphylococcus epidermidis, β-hemolytic Streptococcus species, and Pseudomonas aeruginosa . 5 14 Polymicrobial infection is also fairly prevalent. In one study with 62 patients, only 38% had infections with a single organism, while 62% grew two or more microorganisms with 26% of cultures growing mixed anaerobic and aerobic organisms. 10

Rarely, PFT can be caused by Eikenella corrodens from a human bite or Pasteurella multocida from an animal bite. 15 Other less common causes of PFT that have been reported include Listeria monocytogenes , Clostridium difficile , Neisseria gonorrhoeae , Mycobacterium species, and even fungal infections. 16 17 Conversely, culture-negative PFT can also occur and studies have shown that in 20 to 68% of the time, no bacteria are ever isolated. 4 18

Regardless of the pathogen, management of PFT includes prompt administration of empiric intravenous antibiotics. Prior to obtaining culture results, antibiotic selection should include coverage against gram-positive organisms, including Staphylococcus (especially MRSA) and Streptococcus species. Empiric antibiotics should also cover gram-negative rods and anaerobes especially in immunocompromised patients. 3 Once the precise organism is isolated, the antibiotic regimen should be narrowed to target the specific bacteria identified.

Treatment

Nonoperative treatment may be appropriate for PFT patients who present early, typically within 48 hours after penetrating trauma to the hand. During nonoperative treatment, the affected hand should be frequently examined. If this treatment is going to be successful, clinical symptoms should improve within 24 to 48 hours. 19 If symptoms do not improve, surgical intervention would be indicated ( Fig. 2 ).

Fig. 2.

The authors’ preferred surgical incision for pyogenic flexor tenosynovitis.

One group evaluated the sensitivity and specificity of the Kanavel signs to help guide treatment, and they found the different Kanavel signs had between 91.4 and 97.1% sensitivity for detection of PFT and had specificity ranging from 51.3 to 69.2%. Additionally, they found three independent predictors of PFT: (1) tenderness along the flexor tendon sheath; (2) pain with passive extension; and (3) duration of symptoms less than 5 days. A patient with all three factors present was 87.9% likely to have PFT, whereas a patient with no factors present was 0% likely to have PFT. 20 These guidelines can help support the feasibility of early nonoperative treatment.

Several surgical methods have been developed to decompress and irrigate the flexor tendon sheath. However, there is currently no consensus regarding optimal timing of the surgical intervention, whether open surgery or closed catheter irrigation alone can be performed, and the optimal type of irrigation fluid.

Open Irrigation and Debridement

Open irrigation and debridement procedures were originally described for surgical management of PFT. 7 Midaxial or volar Brunner-type incisions can be utilized to expose and open the entire flexor tendon sheath for thorough debridement. Open irrigation and debridement may be utilized for more advanced cases of infection and in cases of atypical or chronic tenosynovial infections. 4 21

Closed Tendon Sheath Irrigation

Dickson-Wright first described a method of catheter irrigation of tendon sheath infections in 1944; however, Neviaser expanded on the technique in a series of 20 patients in 1978. Zigzag incisions are made over the metacarpal neck and at the level of the distal interphalangeal joint. The tendon sheath is cut transversely at the proximal edge of the A1 pulley. A 16-gauge angiocatheter is inserted into the flexor tendon sheath proximally. The distal edge of the flexor sheath is exposed and incised at the level of the A5 pulley. A small drain can be threaded into the tendon sheath beneath the A4 pulley to keep the wound open and allow for drainage of the fluid. The sheath is then flushed gently in the operating room. 4 Neviaser reported excellent initial results with this technique: 18 out of 20 patients regained complete active and passive motion by 1 week after the operation. 4

Recent studies have reported good outcomes using this technique. One group conducted a retrospective review of 27 patients (28 fingers) with acute PFT, who were treated by a limited, open-tendon-sheath, intermittent-irrigation method that utilized a small pediatric feeding catheter. The cases were subcategorized into three stages, based on the intraoperative appearance of the wound. They found 100% excellent results in stage 1; and 88.4% excellent, 5.8% good, and 5.8% fair in stage 2. 18

Studies have also compared closed irrigation with open irrigation techniques. Gutowski et al reviewed 47 cases of PFT to determine whether a difference in outcomes exists between acute PFT treated with open irrigation and debridement compared with closed catheter irrigation. They found no significant differences between the groups in terms of early postoperative outcomes, including resolution of infection, need for additional surgery, and length of hospital stay. 21

A meta-analysis reviewed 28 retrospective case series of PFT and showed that catheter irrigation resulted in superior outcomes compared with an open technique. They found that 57 of 218 cases (26%) resulted in excellent range of motion when an open technique was used compared with 245 of 343 cases (74%) excellent results when a closed irrigation technique was used. 6

Continuous Closed Irrigation and Postoperative Irrigation

A continuous closed irrigation system with inlet and outlet tubes has also been described with positive results. 11 The continuous irrigation system consists of two fenestrated tubes placed within the infected sheath. The tip of the smaller caliber inlet tube is positioned just inside the larger outlet tube. Theoretical advantages of these systems include the patient’s ability to participate in hand therapy with the system in place and avoidance of pain caused by high pressures associated with intermittent closed irrigation. However, it is unclear whether the timing of the initiation of hand therapy during the irrigation period or during the early postoperative period has significant impact on outcomes. 6

Postoperative irrigation is a controversial practice because leaving a foreign body within the tendon sheath may result in additional complications including stiffness, decreasing the patient’s ability to participate in therapy, or additional injury and irritation to the sheath. One study compared intraoperative closed tendon sheath irrigation alone with intraoperative and postoperative closed tendon sheath irrigation. 10 They found no significant differences in terms of mean length of hospital stay, follow-up complication rates, or postoperative range of motion suggesting that postoperative intermittent or continuous irrigation is not necessary.

There are many differing opinions regarding the best solution to use for irrigation. Most assert that normal saline is sufficient. 4 5 21 A systematic review reported that the use of antibiotics in the irrigation fluid had no clear benefit. 6 Another group reported promising results with local injection of antibiotics into the tendon sheath and the addition of locally administered corticosteroids in the treatment of PFT in an animal model. 22 They found that corticosteroids decreased digit stiffness associated with PFT. However, more research is needed to elucidate the role of corticosteroids in PFT.

Future Treatment Directions

Recently, there has been work trying to elucidate the role of local antibiotics and corticosteroids in the treatment of PFT. 23 In a cadaveric model of PFT, the authors used confocal laser scanning microscopy and scanning electron microscopy to evaluate biofilm formation on the flexor tendon. Additionally, they found that bacterial load by direct colony counting decreased by 18.5% with saline irrigation alone, 42.6% with irrigation and local steroids, 54.4% with irrigation and local antibiotics, and 77.3% with irrigation and both local antibiotics and steroids. The authors therefore suggest rethinking the current treatment of PFT and recommend considering a strategy more analogous to periprosthetic joint infection management with the adjunctive use of local antibiotics and corticosteroids to limit bacterial count and biofilm formation to better eradicate the infection.

Authors’ Preferred Technique

Nonsurgical treatment with antibiotics alone is reserved for patients presenting early and without fluctuance and/or fewer than three Kanavel signs; however, clinical evaluation is always necessary to determine if nonsurgical or surgical intervention can initially be prescribed. Regardless, the patient is still admitted and observed with the potential for imminent surgical decompression. Empiric antibiotics are tailored to cover skin flora and community-acquired MRSA, which is endemic in most urban settings. 13 Laboratory studies can be obtained; however, we are not aware of any serum markers pathopneumonic for PFT or that would indicate immediate surgery. In cases of advanced or delayed presentation, three or more Kanavel signs, and/or failure to respond to antibiotics after 24 to 48 hours, surgery is indicated.

We prefer a volar approach to the finger that begins with outlining a Bruner zigzag incision along the entire finger ( Fig. 3 ). If there are any wounds or lacerations, they should be incorporated into the incision. Initially, only the distal-most and proximal-most incision lines are opened, thereby exposing the A5 and A1 pulleys, respectively ( Fig. 4 ). The A1 pulley is released longitudinally, exposing the flexor tendons. A blush of seropurulent fluid is typical. Similarly, the A5 pulley is released in a limited fashion. A 16-gauge angiocatheter needle is inserted antegrade at the level of the A1 pulley. The flexor sheath is then repeatedly irrigated with antibiotic-impregnated irrigation, until satisfied that the purulent fluid has been cleared away. The finger is passively flexed and extended throughout the irrigation to maximize tendon irrigation. Any enveloping tenosynovitis or biofilm of the flexor tendons is debrided. If the exposure or the extent of irrigation is too limited to adequately clear the infection, the entire marked incision can be opened to connect the initial two incisions. However, care should be taken to avoid incising all the pulleys, particularly A2 and A4. After the irrigation, the tendons are bathed with 25 to 50 mL of vancomycin 20 µg/mL and the incisions are loosely closed. Postoperative irrigation is not performed. Repeat operative irrigation can be performed 2 days later, if necessary. Immediately after the infection is under control, the patient should start supervised therapy to minimize stiffness and adhesion formation. Oral antibiotics should ultimately be tailored to the intraoperative cultures, and should be continued for 2 to 6 weeks after surgery until clinically satisfied that the infection has fully resolved.

Fig. 3.

Management protocol flow chart. PFT, pyogenic flexor tenosynovitis.

Fig. 4.

Case example of a small finger PFT. (A) Note the erythema and swelling around the small finger base and altered cascade of the hand. (B) Preliminary release of the A1 pulley results in release of seropurulent fluid from the flexor sheath. Next, the distal incision will be placed followed by release of the A5 pulley and irrigation catheter irrigation. PFT, pyogenic flexor tenosynovitis.

Conclusion

Ultimately, PFT is a difficult problem and can cause significant morbidity in the population despite adequate treatment. Prompt diagnosis of PFT can be challenging, but early recognition and initiation of treatment are essential to avoid poor outcomes and preserve hand function. Early treatment is crucial with broad-spectrum intravenous antibiotics and surgical irrigation and debridement when appropriate. However, despite timely and thorough treatment, severe infection can nevertheless lead to impaired function or even amputation of the affected digit. Further research is needed to improve preoperative diagnosis of PFT, clarify the role of systemic antibiotics alone without surgical intervention in cases of early infection, and investigate the role for local antibiotics and corticosteroids.