What causes thumb ridges, also known as (thenar) creases or palmar flexion creases?

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From the Guidelines

Thumb ridges, also known as thenar creases or palmar flexion creases, are not directly caused by the factors mentioned in the provided study, which focuses on hand osteoarthritis 1. The formation of thumb ridges is a complex process involving genetic and environmental factors during fetal development.

  • Genetic factors play a significant role in determining the general pattern of the ridges [no direct evidence from (1)].
  • Environmental conditions in the womb, such as amniotic fluid pressure and fetal movement, also influence the formation of these ridges [no direct evidence from (1)]. It is essential to note that the provided study 1 does not directly address the causes of thumb ridges, but rather focuses on the diagnosis and characteristics of hand osteoarthritis.
  • The study discusses risk factors for hand osteoarthritis, such as female sex, increasing age, and occupation-related usage 1, but these factors are not directly related to the formation of thumb ridges.
  • The study also highlights the importance of clinical diagnosis and assessment of functional impairment in hand osteoarthritis 1, which is not relevant to the causes of thumb ridges. In real-life clinical practice, it is crucial to prioritize the patient's overall health and well-being, considering factors that may affect morbidity, mortality, and quality of life 1. However, in the context of thumb ridges, the focus should be on understanding the underlying genetic and environmental factors that influence their formation, rather than relating them to hand osteoarthritis [no direct evidence from (1)].

From the Research

Causes of Thumb Ridges

There are no research papers provided that directly discuss the causes of thumb ridges, also known as thenar creases or palmar flexion creases. The studies available focus on various hand conditions, repetitive strain injuries, and genetic risk factors for musculoskeletal soft tissue injuries, but do not specifically address the topic of thumb ridges.

Related Hand Conditions

Some of the studies provided discuss hand conditions that may be related to thumb ridges, such as:

  • Carpal tunnel syndrome, which can cause numbness and tingling in the thumb and other fingers 2
  • Trigger finger, which can cause abnormal resistance to flexion and extension of the affected finger 2
  • de Quervain tenosynovitis, which can cause swelling of the extensor tendons at the wrist 2
  • Thumb carpometacarpal joint arthritis, which can cause pain and disability in the thumb 2

Repetitive Strain Injuries

Other studies discuss repetitive strain injuries, which can affect the hands and wrists, including:

  • Repetitive strain injuries caused by excessive and repetitious motions of the neck and upper extremity 3, 4
  • Forearm pain caused by tissue responses to repetitive strain 5

Genetic Risk Factors

One study discusses genetic risk factors for musculoskeletal soft tissue injuries, including:

  • Genetic variants associated with chronic Achilles tendinopathy, Achilles tendon ruptures, cruciate ligament ruptures, and shoulder dislocations 6

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Occupational repetitive strain injury.

American family physician, 1992

Research

Repetitive strain injuries.

Lancet (London, England), 1997

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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