EM@3AM: Pyogenic Flexor Tenosynovitis

Author: David Ediger, MD (@dsediger, EM Resident Physician, MAMC / Tacoma, WA), Rachel Bridwell, MD (@rebridwell, EM Resident Physician, SAUSHEC / San Antonio, TX) // Reviewed by: Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX) and Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital)

Welcome to EM@3AM, an emDOCs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 40-year-old female presents to your Emergency Department with three days of pain and swelling in her right index finger. Several days prior, her dog bit her right hand. She went to an urgent care that day and was given a course of amoxicillin-clavulanate, but her symptoms have worsened. She is now unable to use her right hand secondary to pain. She has hypertension and diabetes and is right hand dominant. She denies fevers, chills, or malaise.

Vital signs are normal. On exam, her right index finger is diffusely swollen, erythematous, and held in flexion. There is a punctate wound on the dorsal finger distal to the  DIP. She has significant tenderness to palpation of the flexor compartment of the finger and pain on extension.

What is your next step in evaluation and treatment?

Answer: Pyogenic Flexor Tenosynovitis (PFT)1-22

Pyogenic flexor tenosynovitis is an infection of the flexor tendon synovial sheath in the palmar hand.



  • Hand infections are more common in men (71%), median age 40 years old1
  • Pyogenic flexor tenosynovitis makes up 2.5-9.4% of hand infections2
  • Incidence rate around 1 per 100,000 person-years3
    • Much higher after surgery; 1% incidence after trigger finger release4
  • IV drug use, diabetes, or human bite more likely to have polymicrobial infection5
  • Most commonly isolated organism is aureus, more often MRSA (53%) than MSSA (23%)5
  • Extensor tenosynovitis is a rarer, related entity, usually seen in the nondominant hand of IV drug users, disseminated gonococcal infection, or immunocompromised patients6,7
    • Diagnosis and management is similar to flexor tenosynovitis



  • Flexor tendon sheaths of the fingers form a sealed space filled with synovium to reduce friction and supply nutrition to the tendons6
  • Typically, the small finger tendon sheath communicates with ulnar bursae and common flexor tendon sheath in the palm, and the thumb sheath communicates with radial bursae6,8 (Figure 1)
  • The index, middle, and ring finger flexor sheaths terminate at the metacarpals6


Pathophysiology and microbiology

  • Pyogenic flexor tenosynovitis results from introduction of bacteria via direct or hematogenous spread into the tendon sheath
    • Poor vascular supply and synovial fluid promote bacterial growth9
    • Infection can spread throughout the sheath, or to surrounding structures10
    • Increased pressure in the sheath due to inflammation can result in tendon necrosis10
  • Most commonly, PFT occurs after penetrating trauma to the hand11
    • Skin flora are common: Staph and Strep account for 60-70% of PFT infections
      • 13-29% of PFT grew MRSA6,12
    • Less common: Gram negatives, Mycobacterium, Cryptococcus6
      • Consider Mycobacterium marinum if injury occurred in marine setting
      • M. tuberculosis, Candida if immunocompromised
      • Eikenella, Pasteurella in human or animal bites
    • Polymicrobial infection occurs in the majority of cases12
  • N. gonorrhea can spread hematogenously from a genitourinary infection6,11
  • Non-infectious, inflammatory flexor tenosynovitis can indicate autoimmune arthropathy or calcium pyrophosphate disease13
    • Rarely presents acutely



  • Typical history is a bite or puncture wound to the hand 2-5 days prior6,11 (Figure 2)
    • Wound can go unnoticed by the patient, resulting in delayed presentation to care14
    • May also have been seen previously, and failed trial of antibiotics6,14
    • Most commonly occurs in the ‘pinching’ digits: index, middle finger, thumb of dominant hand14
  • Typical symptoms include pain on the dorsal aspect of the finger (or diffusely), swelling, and limited range of motion
    • Other symptoms: paresthesias, fever, chills, anorexia, malaise, proximal spread6
  • Other important history to obtain:
    • Sexual history (especially if presenting without a known injury to the hand)
    • Handedness
    • Occupation
    • IV drug use
  • Risk factors associated with poor outcome (amputation):2,11
    • Increasing age (over 43 years)3
    • Diabetes mellitus
    • Peripheral vascular disease/digital ischemia
    • Renal failure
    • Subcutaneous purulence
    • History of methicillin-resistant S. aureus infection6



  • Fever is frequently absent (present in 17% of confirmed cases)2
  • Kanavel’s cardinal signs (in descending frequency):6,10,15
    1. Fusiform swelling of the involved digit
    2. Pain with passive extension, most marked at the proximal end
    3. Extend the finger by grasping it medially and laterally, so pressure is not applied directly to the flexor tendon sheath
    4. Finger held in semi-flexion
    5. Exquisite tenderness over flexor tendon sheath
      • Conflicting evidence as to diagnostic utility of Kanavel signs
        • In one study, only half of surgically proven PFT had all four signs3
          • All patients did have tenderness along the sheath and pain with passive extension
        • Signs may be less evident in thumb, small finger, and in children6
        • A retrospective review of 74 patients with finger infections found high sensitivity (91-97%) for each Kanavel sign, but recommended against using them in isolation as a decision rule to diagnose PFT16
          • Specificity of each sign ranged from 51-69%16
          • They did find that patients who had pain with extension, flexor tendon sheath tenderness, and symptoms for <5 days had an 87.9% likelihood of having PFT
        • First sign may be pain with passive extension; tenderness along tendon sheath may indicate delayed presentation/proximal extension2,3
      • Maximal point of tenderness is over the proximal end of the tendon sheath near MCP joint6
      • Examine for puncture wound(s), lacerations/incisions, scaling/cracked skin, and presence and distribution of erythema17
        • Use unaffected hand as a comparison
      • Evaluate for fluctuance, crepitus, and lymphadenopathy
      • Document range of motion and neurovascular status


Labs and imaging

  • WBC, ESR, and/or CRP may be elevated in PFT6,17
    • A retrospective review of 71 patients found all patients with surgically confirmed PFT had an elevation of WBC, ESR, or CRP
    • However, these labs have low sensitivity for PFT (sensitivity 39-76%, NPV 4-13%), and do not distinguish it from other infections of the hand (cellulitis, abscess, felon)6
  • Plain films: only if concern for fracture or retained foreign body6
  • MRI not required; may help rule out other conditions (abscess), but cannot diagnose PFT18
  • Ultrasound6,11
    • May see hypoechoic/anechoic fluid, thickened tendon sheath19
    • No evidence to suggest ultrasound is more accurate than physical exam or clinical intuition; in isolation, it cannot rule out PFT


Differential diagnosis11

  • Superficial infection (cellulitis, abscess, felon, paronychia)
  • Inflammatory tenosynovitis (rheumatoid arthritis, psoriatic arthritis, gout, pseudogout)
  • Stenosing tenosynovitis (“trigger finger”)
  • Septic arthritis
  • Necrotizing fasciitis
  • Herpetic whitlow



  • Infectious flexor tenosynovitis is a surgical emergency – consult orthopedics or hand surgery early6
    • Typical approach involves either closed-sheath irrigation or open debridement and irrigation6
    • If recognized early (<48 hours) and without fluctuance, it may respond to IV antibiotics alone, though surgical debridement/irrigation is usually still necessary6,12
  • Initiate IV antibiotics early, prior to surgery
    • Empiric coverage against Staph aureus (including MRSA) and Streptococcus6,20
      • In all patients, vancomycin against MRSA21
      • If animal bite, third-generation cephalosporin against multocida12
      • If immunocompromised, add coverage against Gram negative rods and anaerobes7
      • If disseminated gonococcal infection suspected, add ceftriaxone 1g IM/IV q24 hours11
    • Elevate and splint the affected limb6



  • Admit for operative management, or serial exams and IV antibiotics11
  • Risk of significant hand dysfunction if improperly treated8
    • Tendon adhesions, reduced grip strength, stiffness/reduced range of motion, tendon rupture, and/or proximal spread of infection2,3,20
    • Overall amputation rate 4.5%6
      • 41% of amputations had a delay in treatment >3 days22
    • Risk of complications increases with presence of subcutaneous purulence and/or digital ischemia22
  • Inflammatory tenosynovitis without signs of infection can be managed as an outpatient



  • Pyogenic flexor tenosynovitis is a clinical diagnosis requiring a high index of suspicion, especially when patients return after a course of antibiotics
  • Patients who have acute (<5 days) onset of painful extension and flexor sheath tenderness have a high likelihood of having PFT
  • The cornerstones of management are surgical consultation and early empiric antibiotics against MRSA and Streptococcus
  • Consider gonococcal tenosynovitis in sexually active patients with symptoms without antecedent hand injury

Further Reading:




  1.         Houshian S, Seyedipour S, Wedderkopp N. Epidemiology of bacterial hand infections. International Journal of Infectious Diseases. 2006;10(4):315-319. doi:10.1016/j.ijid.2005.06.009
  2.         Pang HN, Teoh LC, Yam AKT, Lee JYL, Puhaindran ME, Tan ABH. Factors affecting the prognosis of pyogenic flexor tenosynovitis. Journal of Bone and Joint Surgery. 2007;89(8):1742-1748. doi:10.2106/JBJS.F.01356
  3.         Dailiana ZH, Rigopoulos N, Varitimidis S, Hantes M, Bargiotas K, Malizos KN. Purulent flexor tenosynovitis: Factors influencing the functional outcome. Journal of Hand Surgery: European Volume. 2008;33(3):280-285. doi:10.1177/1753193408087071
  4.         Stewart CN, Ward CM. Infectious Flexor Tenosynovitis Following Trigger Finger Release : Incidence and Risk Factors. 2020. doi:10.1177/1558944720930298
  5.         Fowler JR, Ilyas AM. Epidemiology of adult acute hand infections at an urban medical center. Journal of Hand Surgery. 2013;38(6):1189-1193. doi:10.1016/j.jhsa.2013.03.013
  6.         Hyatt BT, Bagg MR. Flexor Tenosynovitis. Orthop Clin N Am. 2017;48:217-227. doi:10.1016/j.ocl.2016.12.010
  7.         Lebowitz C, Matzon JL. Isolated Gonococcal Extensor Tenosynovitis. Journal of Hand Surgery Global Online. 2019;1(1):43-44. doi:10.1016/j.jhsg.2018.11.001
  8.         Patel DB, Emmanuel NB, Stevanovic M v., et al. Hand infections: Anatomy, types and spread of infection, imaging findings, and treatment options. Radiographics. 2014;34(7):1968-1986. doi:10.1148/rg.347130101
  9.         Rerucha CM, Ewing JT, Oppenlander KE, Cowan WC. Acute hand infections. American Family Physician. 2019;99(4):228-236. doi:10.5005/jp/books/12510_11
  10.        Osterman M, Draeger R, Stern P. Acute hand infections. Journal of Hand Surgery. 2014;39(8):1628-1635. doi:10.1016/j.jhsa.2014.03.031
  11.        Thornton DJA, Lindau T. Hand infections. In: Orthopaedics and Trauma. Vol 24. Elsevier Ltd; 2010:186-196. doi:10.1016/j.mporth.2010.03.016
  12.        Chapman T, Ilyas AM. Pyogenic Flexor Tenosynovitis: Evaluation and Treatment Strategies. Journal of Hand Surgery. 2019;44(11):981-985. doi:10.1016/j.jhsa.2019.04.011
  13.        Naredo E, Agostino MAD, Wake RJ, et al. Reliability of a consensus-based ultrasound score for tenosynovitis in rheumatoid arthritis. Ann Rheum Dis. 2013;72:1328-1334. doi:10.1136/annrheumdis-2012-202092
  14.        Patel DB, Emmanuel NB, Stevanovic M v., et al. Pyogenic flexor tenosynovitis: one year’s experience at a UK hand unit and a review of the current literature. Journal of Hand Surgery. 2012;89(6):186-196. doi:10.1148/rg.347130101
  15.        Kennedy CD, Huang JI, Hanel DP. In Brief: Kanavel’s Signs and Pyogenic Flexor Tenosynovitis. Clinical Orthopaedics and Related Research. 2016;474(1):280-284. doi:10.1007/s11999-015-4367-x
  16.        Kennedy CD, Lauder AS, Pribaz JR, Kennedy SA. Differentiation Between Pyogenic Flexor Tenosynovitis and Other Finger Infections. Hand. 2017;12(6):585-590. doi:10.1177/1558944717692089
  17.        Bishop GB, Born T, Kakar S, Jawa A. The diagnostic accuracy of inflammatory blood markers for purulent flexor tenosynovitis. Journal of Hand Surgery. 2013;38(11):2208-2211. doi:10.1016/j.jhsa.2013.08.094
  18.        Padrez K, Bress J, Johnson B, Nagdev A. Bedside ultrasound identification of infectious flexor tenosynovitis in the emergency department. Western Journal of Emergency Medicine. 2015;16(2):260-262. doi:10.5811/westjem.2015.1.24474
  19.        Hubbard D, Joing S, Smith S. Pyogenic Flexor Tenosynovitis by Point-of-care Ultrasound in the Emergency Department. Clinical Practice and Cases in Emergency Medicine. 2018;2(3):235-240. doi:10.5811/cpcem.2018.3.37415
  20.        Giladi AM, Malay S, Chung KC. Management of acute pyogenic flexor tenosynovitis: Literature review and current trends. J Hand Surg Eur Vol. 2015;40(7):720-728. doi:10.1177/1753193415570248
  21.        Brusalis C, Thibaudeau S, Carrigan R, Lin I, Chang B, Shah A. Clinical Characteristics of Pyogenic Flexor Tenosynovitis in Pediatric Patients. The Journal of Hand Surgery. 2017;42(5):338.E1-338.E5.
  22.        Draeger RW, Bynum DK. Flexor Tendon Sheath Infections of the Hand Abstract. J Am Acad Orthop Surg. 2012;20(6):373-382.

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