What is the cause of limited Interphalangeal (IP) thumb flexion?

From the Guidelines

Limited IP thumb flexion is most commonly caused by joint stiffness, tendon adhesions, or arthritis affecting the flexor pollicis longus tendon, and the best approach to address this issue is through a combination of physical therapy, exercises, and possibly medical interventions, as recommended by the most recent guidelines 1. The primary goal of treatment should be to improve range of motion, reduce pain, and enhance functional ability.

• Key considerations include:
  • Gentle stretching and strengthening exercises to improve flexibility and strength of the thumb
  • Pain management using over-the-counter NSAIDs like ibuprofen or naproxen, as well as heat and cold therapy to reduce inflammation and improve tissue elasticity
  • Consultation with a hand specialist if symptoms persist, for potential recommendations on corticosteroid injections, splinting, or further evaluation for underlying conditions
• The most recent evidence suggests that surgery may be considered for patients with structural abnormalities when other treatment modalities have not been sufficiently effective in relieving pain 1.
• It is essential to note that the management of hand osteoarthritis, which may be a contributing factor to limited IP thumb flexion, should be individualized according to the patient's specific needs and circumstances, taking into account factors such as the localization of OA, risk factors, and the presence of inflammation 1.
• In terms of specific interventions, splints for thumb base OA and orthoses to prevent or correct lateral angulation and flexion deformity are recommended, although the evidence for this is based on expert opinion and small head-to-head RCTs 1.
• Overall, a comprehensive approach that incorporates physical therapy, pain management, and potentially medical interventions, with consideration of the most recent guidelines and evidence, is crucial for addressing limited IP thumb flexion and improving patient outcomes.

From the Research

Causes of Limited Interphalangeal (IP) Thumb Flexion

• Limited IP thumb flexion can be caused by various factors, including:
  • Trauma or injury to the flexor pollicis longus (FPL) tendon, such as lacerations or ruptures 2
  • Flexor pollicis longus dysfunction after volar plate fixation of distal radius fractures 3
  • Trigger thumb, which can cause IP joint flexion contractures or limited flexion 4, 5
  • Tenosynovitis or inflammation of the tendons in the hand or wrist, including the FPL tendon 5
• Other potential causes of limited IP thumb flexion include:
  • Adhesion formation or re-rupture after FPL repair 2
  • Partial stripping of the FPL muscle from investing fascia and bone, and retraction of soft tissues 3
  • Insufficiency of the FPL tendon channel or impairment of the superficial or deep flexor tendon of the ring finger 6

Associated Factors and Complications

• Factors associated with limited IP thumb flexion include:
  • Solitary injury to the thumb, which can affect IP joint motion 2
  • Use of epitendinous suture, which can improve active IP joint flexion 2
  • Multiple digits injured accompanying a Zone II FPL laceration, which can result in inferior IP joint motion 2
• Complications that can occur in association with limited IP thumb flexion include:
  • Reoperation, which may be necessary in cases of adhesion formation or re-rupture 2
  • Contracture of the proximal thumb joint or PIP joint of the ring finger 6
  • Reduced grip force, lateral grip, or pinch grip 6