Ulnar Deviation: Testing, Interpretation, and Causes

How to Test for Ulnar Deviation?

Testing for ulnar deviation involves assessing the range of motion and alignment of the wrist joint, primarily through visual observation, goniometric measurement, and functional movement assessment, to identify potential limitations or abnormalities.

Understanding Ulnar Deviation

Ulnar deviation, also known as wrist adduction, is the movement of the hand towards the ulna (the bone on the pinky finger side of the forearm). This motion occurs at the radiocarpal and midcarpal joints of the wrist. It is one of the fundamental movements of the wrist, along with radial deviation (movement towards the thumb side), flexion (bending forward), and extension (bending backward). Understanding the normal range of motion for ulnar deviation is crucial for identifying dysfunction, injury, or underlying pathological conditions that can restrict or excessively allow this movement.

Why Test for Ulnar Deviation?

Assessing ulnar deviation is a vital component of a comprehensive upper extremity evaluation for several reasons:

• Injury Assessment: To evaluate the extent of injury following trauma to the wrist or forearm, such as fractures, sprains, or dislocations.
• Pain Etiology: To help identify the source of wrist pain, which could be related to restricted or excessive motion.
• Functional Limitation: To determine if limitations in ulnar deviation are impacting daily activities, sports performance, or occupational tasks requiring wrist mobility (e.g., gripping, lifting, typing).
• Pathological Conditions: To screen for systemic conditions that often affect joint mobility, such as rheumatoid arthritis, osteoarthritis, or other inflammatory conditions that can cause joint deformities or stiffness.
• Rehabilitation Progress: To track improvements in range of motion during a rehabilitation program following surgery or injury.

Preparing for Assessment

Before conducting any assessment, ensure the individual is comfortable and understands the procedure. Proper preparation ensures accurate and reliable results.

• Informed Consent: Briefly explain the purpose of the test and what to expect.
• Proper Positioning: The individual should be seated comfortably with their forearm supported on a flat surface.
• Exposure: The wrist and hand should be fully exposed, free from clothing or jewelry that could obstruct movement or landmarks.

Clinical Assessment Methods

Accurate assessment of ulnar deviation typically involves a combination of visual inspection and precise goniometric measurement.

Visual Observation

Begin with a simple visual assessment to get a general idea of the wrist's resting position and gross movement.

• Resting Position: Observe if the hand naturally rests in a neutral position relative to the forearm, or if there's a noticeable deviation (either ulnar or radial) at rest.
• Active Range of Motion (AROM): Ask the individual to actively move their hand as far as possible towards their pinky finger side. Observe the quality and quantity of the movement, noting any pain, compensatory movements, or obvious limitations. Compare both wrists if possible.

Goniometric Measurement

Goniometry is the most common and objective method for measuring joint angles, providing a quantifiable measure of range of motion.

• Equipment: A standard universal goniometer is required.
• Individual Positioning:
  • The individual should be seated.
  • The forearm should be supported on a table, with the elbow flexed to approximately 90 degrees and the forearm pronated (palm down).
  • The wrist should be in a neutral position (0 degrees of flexion/extension) at the start of the measurement.
• Goniometer Placement and Procedure:
  1. Palpate Landmarks: Identify the key bony landmarks for accurate goniometer alignment.
     • Fulcrum (Axis of Rotation): Place the goniometer's fulcrum over the dorsal aspect of the wrist, specifically over the capitate bone (often palpable just proximal to the base of the third metacarpal). This approximates the axis of wrist deviation.
     • Stationary Arm: Align the stationary arm with the midline of the forearm, pointing towards the lateral epicondyle of the humerus.
     • Moving Arm: Align the moving arm with the dorsal midline of the third metacarpal (the middle finger bone).
  2. Initial Reading: Ensure the goniometer is at 0 degrees when the wrist is in neutral.
  3. Perform Movement: Instruct the individual to actively move their hand as far as possible into ulnar deviation, keeping the forearm stable and avoiding any shoulder or elbow compensation.
  4. Final Reading: Read the angle indicated by the goniometer's moving arm. Ensure the moving arm remains aligned with the third metacarpal throughout the movement.
  5. Record: Document the measurement in degrees.

Functional Movement Assessment

While not directly measuring the angle, observing ulnar deviation in functional contexts can provide insights into its impact on daily activities.

• Grip Strength Tests: Observe how ulnar deviation might affect the ability to grasp objects, especially larger ones.
• Specific Task Simulation: Ask the individual to perform tasks that require wrist deviation, such as turning a doorknob, using a screwdriver, or typing. Note any difficulty, pain, or compensatory movements.

Interpreting Results

Normal ranges for wrist ulnar deviation can vary slightly between individuals and sources, but generally:

• Normal Range: Approximately 30-45 degrees of ulnar deviation.
• Limited Ulnar Deviation: A range significantly less than 30 degrees may indicate joint stiffness, arthritis, soft tissue contractures, or fracture healing.
• Excessive Ulnar Deviation: While less common for isolated excessive ulnar deviation, hypermobility or instability could be indicated. However, often a resting ulnar deviation is observed in conditions like rheumatoid arthritis, even if the active range of motion is limited. This resting deviation is a key visual sign.

It is crucial to compare findings to the unaffected side (if applicable), the individual's reported symptoms, and their functional limitations.

Common Causes of Ulnar Deviation

Abnormal ulnar deviation can stem from various causes:

• Rheumatoid Arthritis: A common cause of chronic ulnar deviation at the wrist and metacarpophalangeal (MCP) joints due to joint erosion and ligamentous laxity.
• Post-Traumatic Deformity: Following fractures (e.g., distal radius fracture) or severe sprains that heal with malalignment.
• Ligamentous Instability: Damage or laxity of wrist ligaments.
• Muscle Imbalance: Weakness or tightness in wrist flexors/extensors or radial/ulnar deviators.
• Nerve Compression: Although less direct, some nerve issues can affect muscle function around the wrist.

When to Seek Professional Guidance

While testing for ulnar deviation can be performed by fitness professionals or individuals with basic anatomical knowledge, interpreting the findings and developing a treatment plan requires professional expertise. If you observe significant limitations, pain, or a resting deformity, it is essential to consult with a qualified healthcare professional, such as a physician, physical therapist, or occupational therapist. They can provide an accurate diagnosis and recommend appropriate interventions.