x
x

A-2 PULLEY RUPTURE (FLEXOR TENDON SHEATH RUPTURE)

Introduction

A-2 pulley ruptures can involve avulsions of the flexor digitorum profundus (FDP) tendon. Rarely these ruptures can also involve the flexor digitorum superficialis (FDS) tendon.1 Cases typically involve the second or fourth digit. Schöffl has developed a grading system of pulley injuries: Grade I is a pulley strain, Grade II could be an A-2 partial rupture, Grade III a complete rupture and Grade IV multiple ruptures with muscle and ligament involvement.2 When the A-2, A-3 and A-4 pulleys rupture at the same time, the patient’s hand will show marked bowstringing and digital swelling.3,4

Pathophysiology

  • A-2 pulley ruptures are caused by overuse or injury.
  • The repetitive FDP tendon pulling against a diseased A-2 pulley can also cause A-2 pulley injuries.
  • Iatrogenic A-2 injury during trigger finger release can cause A-2 dysfunction.

Related Anatomy

  • FDP tendon
  • FDS tendon
  • Proximal interphalangeal (PIP) joint
  • A-3 and A-4 pulleys
  • Flexor tendon vincula

Incidence and Related Conditions

  • Stenosing tenosynovitis (trigger finger)
  • Dupuytren’s disease

Differential Diagnosis

  • Contracture of PIP joint5
  • Avulsion of tendon
  • Dupuytren's contracture

 

ICD-10 Codes

  • A-2 PULLEY RUPTURE

    Diagnostic Guide Name

    A-2 PULLEY RUPTURE

    ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

    DIAGNOSISSINGLE CODE ONLYLEFTRIGHTBILATERAL (If Available)
    A-2 PULLEY RUPTURE    
    - INDEX S66.191_S66.190_ 
    - MIDDLE S66.193_S66.192_ 
    - RING S66.195_S66.194_ 
    - LITTLE S66.197_S66.196_ 

    Instructions (ICD 10 CM 2020, U.S. Version)

    THE APPROPRIATE SEVENTH CHARACTER IS TO BE ADDED TO EACH CODE FROM CATEGORY S66
    A - Initial Encounter
    D - Subsequent Routine Healing
    S - Sequela

    ICD-10 Reference

    Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
A-2 Pulley Ruptures
  • A-2 pulley rupture left fifth finger
    A-2 pulley rupture left fifth finger
  • Chronic A-2 pulley rupture right ring finger with marked displaced flexor tendon (1) and PIP joint flexion contracture (2).
    Chronic A-2 pulley rupture right ring finger with marked displaced flexor tendon (1) and PIP joint flexion contracture (2).
Pathoanatomy Photos and Related Diagrams
Flexor Tendon Sheath
  • This diagram highlights the vascular supply and components of the flexor tendon sheath. The three cruciate pulleys (C1-3), the five annular pulleys (A1-A5) and the palmar aponeurotic pulley (PA) are shown. The A2 and A4 pulleys are the biomechanically the most important pulleys. During flexor tendon surgery, Tang(ref14) has shown that the A2 pulley can be 50% excised or vented and the A4 can be 100% vented if needed for tendon excursion if the other parts of the sheath are intact.
    This diagram highlights the vascular supply and components of the flexor tendon sheath. The three cruciate pulleys (C1-3), the five annular pulleys (A1-A5) and the palmar aponeurotic pulley (PA) are shown. The A2 and A4 pulleys are the biomechanically the most important pulleys. During flexor tendon surgery, Tang(ref14) has shown that the A2 pulley can be 50% excised or vented and the A4 can be 100% vented if needed for tendon excursion if the other parts of the sheath are intact.
Symptoms
Swelling in the area of the palmar proximal phalanx
Palmar tenderness of the affected digit(s)
Flexor tendon Bowstringing
Decreased active range of motion (flexion loss)
Patient may give a history of audible pop while gripping
Typical History

The patient presents with an A-2 pulley rupture, caused by climbing injuries or by lifting heavy items with crimped fingers.2 Rarely trigger finger can also cause A-2 pulley ruptures. Only very rarely does an FDS rupture occur spontaneously.

Positive Tests, Exams or Signs
Work-up Options
Images (X-Ray, MRI, etc.)
MRI A-2 Pulley Rupture
  • MRI of an A-2 pulley rupture. Note the marked palmar displacement (arrow) of the flexor tendons (F).
    MRI of an A-2 pulley rupture. Note the marked palmar displacement (arrow) of the flexor tendons (F).
Treatment Options
Treatment Goals
  • Accurately diagnose A-2 pulley rupture
  • Treat acute and chronic A-2 pulley rupture
Conservative
  • Partial acute A-2 pulley injuries only require conservative treatment, using a ring pulley support splint.7
Operative
  • Operative treatment is needed for some Grade II and III and all Grade IV injuries.
  • The most commonly used fully repair method is the Bunnell method or variations of this procedure. With Bunnell’s technique, the A-2 pulley is reconstructed with a tendon graft looped twice around the proximal phalanx at the A-2 level. The tender graft is passed underneath the neurovascular bundles and under the extensor tendon.5,7,8
  • Other pulley reconstruction options include suturing the tendon graft to the intact A-2 pulley rim if it is available, reconstructing the pulley with the flexor digitorum superficialis (FDS), reconstruction of the pulley with a extension retinaculum graft or reconstruction of the pulley with the volar plate.5,7,8
  • Tendon grafting is not recommended for young children. In young children with A-2 pulley injuries, use a conservative approach and delay surgery until age 7 or older so they can cooperate with the post-operative management.5
  • A minimally invasive double-anchor approach can be used. This approach lessens soft tissue trauma, reduces the risk of damage to the neurovascular bundle but the drill holes for the bone anchors may predispose the patient to a proximal phalanx fracture.11
Treatment Photos and Diagrams
A-2 Pulley Reconstruction
  • Left fifth A-2 pulley repair incision plan. Note PIP flexion contracture.
    Left fifth A-2 pulley repair incision plan. Note PIP flexion contracture.
  • Flexor tendons exposed. Note complete lack of flexor tendon sheath (A-2 pulley).
    Flexor tendons exposed. Note complete lack of flexor tendon sheath (A-2 pulley).
  • PIP joint and FDS insertion released (arrow).
    PIP joint and FDS insertion released (arrow).
  • FDS being harvested (arrow) and completed repair (Insert).
    FDS being harvested (arrow) and completed repair (Insert).
  • Right long finger pulley reconstruction. Note joint an FDS release. FDS will be used to construct pulley (no PL available). Some A-3 pulley intact.
    Right long finger pulley reconstruction. Note joint an FDS release. FDS will be used to construct pulley (no PL available). Some A-3 pulley intact.
  • Right long finger pulley reconstruction complete. Graft sutured to itself and any remaining pulley rim.
    Right long finger pulley reconstruction complete. Graft sutured to itself and any remaining pulley rim.
Hand Therapy
Splinting post A-2 Pulley Reconstruction
  • Dynamic extension splint used with a ring splint for A-2 pulley reconstruction rehabilitation.
    Dynamic extension splint used with a ring splint for A-2 pulley reconstruction rehabilitation.
Complications
  • Flexion contracture, due to excessive tightening of the tendon graft, is a common complication during A-2 pulley reconstruction.8,9 Synovitis and re-rupture may also occur.
  • The digital neurovascular bundles are at risk of injury during pulley reconstruction.
Outcomes
  • Patients should be able to return to athletic activities, such as climbing, within one year.
  • Early protected finger motion may be possible, if a double or triple loop pulley reconstruction is used.12,13
Key Educational Points
  • Compare the injured digit(s) with neighbouring digits when palpating to detect swelling and tenderness.7
  • Patients with a pulley rupture will show decreased range of motion.2
  • Check grip strength but be aware that strength may not be affected immediately.7
  • In cases of trigger finger, be vigilant in using multiple repeat corticosteroid injections; they may precipitate a pulley injury.5
  • In six digital pulley reconstruction studies, Karev’s operative technique was the most mechanically effective. 5,12
  • Prior to 2014, research suggested that it was vital to preserve the integrity of the entire A-2 pulley in reconstructive surgery. Recently, the new treatment of partial pulley excision or “venting” is becoming an option.10 Following surgery, venting compensates for the increased tendon volume. It is possible to vent up to 50% of the pulley while maintaining its usefulness.14,15
  • A tendon graft for pulley reconstruction needs to be approximately 16 cm in length.
  • Adjusting the tension in the reconstructed pulley is important. If the graft is too tight the tender graft will not glide properly underneath the pulley.  However, a loose tendon graft pulley reconstruction will not be corrected bowstringing. Therefore, the tension, tightness and strength of the pulley should be tested during surgery while adjusting the reconstructed pulley’s tightness.
  • A-2 and A-4 pulley reconstructions are often needed during stage one flexor tendon reconstruction procedures.
  • Passing a tendon graft around the proximal families can be technically difficult. Curved clamps, Penrose drains and additional dorsal incisions have all been used to facilitate passing the tendon graft.
  • Bunnell passed his tendon grafts dorsal to the extensor tendon for A-4 pulley reconstruction and under the extensor for A-2 reconstruction. Others go under the extensor tendon for both A-2 and A-4 reconstructions.
References
  1. Johnsen P, O’Shea K, Wolfe SW. Traumatic flexor digitorum superficialis and A2-A3 pulley rupture: case report. J Hand SurgAm 2014;39(3):524-6. PMID: 24559629
  2. Schöffl VR, Schöffl I. Injuries to the finger flexor pulley system in rock climbers: current concepts. J Hand Surg2006;31A:647-54. PMID: 16632061
  3. Gabl M, Rangger C, Lutz M, et al. Disruption of the finger flexor pulley system in elite rock climbers. Am J Sports Med 26:651–655, 1998. PMID: 9784811
  4. Marco RA, Sharkey NA, Smith TS, et al. Pathomechanics of closed rupture of the flexor tendon pulleys in rock climbers. J Bone Joint Surg [Am] 80A:1012–1019, 1998. PMID: 9698006
  5. Green’s Operative Hand Surgery. Wolfe S, ed. Philadelphia: Elsevier, 2011.
  6. Schöffl I, Meisel J, Lutter C, Schoffl V. Feasibility of a new pulley repair: a cadaver study. J Hand Surg Am2018;43(4):380. E1-e7. PMID: 28985979
  7. Bowers WH, Kuzma GR, Bynum DK. Closed traumatic rupture of finger flexor pulleys. J Hand Surg 1994;19A:782-7. PMID: 7806800
  8. Clark TS, Skeete K, Amadio PC. Flexor tendon pulley reconstruction. J Hand Surg 2010;35(10):1685-1689. PMID: 20888506
  9. Mehta V, Phillips CS. Flexor tendon pulley reconstruction. Hand Clin 2005;21:245-251. PMID: 15882602
  10. Zafonte V, Rendulic D, Szabo R. Flexor pulley system: anatomy, injury and management. J Hand Surg2014;39(12):2525-32. PMID: 25459958
  11. Mallo GC, Sless Y, Hurst LC, Serra-Hsu F. Minimally invasive flexor tendon pulley biomechanical comparison with two accepted techniques. Philadelphia: Lippincott, Williams & Wilkins, 2008
  12. Widstrom CJ, Johnson G, Doyle JR, Manske PR, Inhofe P. A mechanical study of six digital pulley reconstruction techniques: part I. Mechanical effectiveness. J Hand Surg 1989;14A:821-5.
  13. Lin GT, Amadio PC, An KN, Cooney WP, Chao EY. Biomechanical analysis of finger flexor pulley reconstruction. J Hand Surg. 1989;14B:278-282. PMID: 2794704
  14. Tang JB. New developments are improving flexor tendon repair. Plast Reconstr Surg 2018;141(6):1427-37. PMID: 29579022
  15. Myer C, Fowler JR. Flexor tendon repair: healing, biomechanics, and suture configurations. Orthop Clin North Am2016;47(1):219. PMID: 26614935
Subscribe to A-2 PULLEY RUPTURE (FLEXOR TENDON SHEATH RUPTURE)
⇡