Tenderness A-1 Pulley & Triggering

Historical Overview

• A-1 pulley tenderness is a sign indicating that the patient may have a trigger finger or trigger thumb (stenosing tenosynovitis).
• Trigger digits were first described by Notta in 1850.¹

Description

• Tenderness at the A-1 pulley suggests a trigger digit.²
• Applying pressure to a palpable nodule just proximal to the A-1 pulley that causes tenderness³ also suggests a trigger digit.
• If the patient presents with a “locking” or “catching” or “popping” of the proximal interphalangeal (PIP) joint of the affected digit or the interphalangeal (IP) joint of the thumb, the diagnosis of trigger finger is nearly conclusive.^2,4

Pathophysiology

• Stenosing tenosynovitis is a pathologic disproportion between the volume of the retinacular sheath and its contents. This disproportion inhibits gliding as the tendon moves through the A1 pulley.⁵
• It is due to inflammation and hypertrophy of the reticunacular sheath that progressively restricts the motion of the flexor tendon.⁴

Instructions

1. Take patient history.
2. Palpate any nodule near the A-1 pulley.

Variations

• The signs of trigger finger vary depending on how far the condition has progressed:⁴
  • The initial complaint associated with trigger finger may be of a painless clicking sound with digital manipulation.
  • Further development of the condition can cause the catching or popping to become painful with both flexion and extension, and can occur at either a metacarpophalangeal (MP) or PIP joint.
  • Some patients may notice a feeling of stiffness and then progressive loss of full flexion and/or extension of the affected digit without ever developing the catching and locking of a ‘‘typical’’ trigger finger.
  • A painful nodule, a result of intratendinous swelling, may be palpated in the palmar MP area. The patient may complain of MP stiffness or swelling in the morning, or that they awaken with the digit locked and that it loosens throughout the day.
  • With continued deterioration, the patient may present with the finger locked in flexion, which may require passive manipulation to achieve full extension.
  • With time, the patient’s desire to avoid the painful triggering caused by manipulation or use of the involved digit may lead to the development of secondary PIP contractures and digital stiffness.

Related Signs and Tests

• The differential diagnosis of trigger finger includes:³
  • PIP joint pain
  • Pseudoboutonniere
  • Sesamoiditis
  • Dupuytren’s disease
  • Subluxation of the long extensor tendon over the metacarpal head
  • MP joint arthritis
  • Locking of the MP joint

Diagnostic Performance Characteristics

• The classic presentation of popping and locking of a trigger finger is typically all that is needed for a diagnosis of trigger finger; however, with acute onset of symptoms, patients may present with pain and swelling over the involved flexor sheath with avoidance of finger motion. In these cases, the classic popping and triggering are not seen, and the diagnosis of trigger finger must be differentiated from infection or some other traumatic injury.⁴

• Tenderness (pain) at the A-1 pulley area associated with popping, locking and crepiyus associated with a trigger digit

• Lack of tenderness (pain) at the A-1 pulley area associated with popping, locking and crepiyus associated with a trigger digit

• There are many classification systems for trigger finger, but none is commonly accepted.³
• If desired, the diagnosis may be confirmed with an injection of lidocaine into the flexor sheath, which should relieve the pain associated with the triggering and allow the digit to become actively or passively extended.
• There is no role for imaging in diagnosis; X-rays are considered unnecessary in patients without history of inflammatory disease or trauma.⁴

1. Ryzewicz M, Wolf J. Trigger digits: principles, management, and complications. J Hand Surg Am 2006;21(1):135-46. PMID: 16443118
2. Bodor M, Flossman T. Ultrasound-guided first annular pulley injection for trigger finger. J Ultrasound Med 2009;28(6):737-43. PMID: 19470813
3. Hammert  W, et al. ASSH Manual of Hand Surgery. Philadelphia: Lippincott Williams and Wilkins, 2010.
4. Makkouk A, et al. Trigger finger: etiology, evaluation, and treatment. Curr Rev Musculoskelet Med 2008;1(2):92-6. PMID: 19468879
5. Saldana M. Trigger Digits: Diagnosis and Treatment. J Am Acad Orthop Surg 2001;9:246-252. PMID: 11476534