Thumb Ankylosis C&P Exam Prep

Opposition Gap Measurement (Thumb Pad to Finger Distance)

What it measures: The distance in centimeters between the thumb pad and the fingers when the veteran attempts to oppose the thumb to the fingers. This is the single most critical measurement for determining favorable vs. unfavorable ankylosis.

What to expect: The examiner will ask you to try to bring your thumb tip toward your fingers as if pinching. They will measure the gap between your thumb pad and your fingers using a ruler or tape measure. This is done actively - you try your hardest to close the gap.

Pain considerations: Pain during opposition attempt must be reported to the examiner. Even if the gap is within 5.1 cm, pain with opposition is a significant functional limitation that should be documented. State clearly if you cannot make a full pinch effort due to pain.

Thumb CMC Joint Range of Motion (Active and Passive)

What it measures: Movement at the carpometacarpal joint - the saddle joint at the base of the thumb connecting it to the wrist. Normal abduction is approximately 70 degrees; normal flexion and extension also measured.

What to expect: The examiner will ask you to move your thumb away from your hand (abduction), flex and extend it at the base, and may attempt to move the joint passively. If ankylosed, motion will be absent or severely restricted at this joint.

Pain considerations: Report pain at the CMC joint at rest and with any attempted motion. Pain at rest supports documentation of constant impairment beyond simple ROM limitation.

Thumb IP Joint Range of Motion (Active and Passive)

What it measures: Movement at the interphalangeal joint of the thumb - the only joint between the two thumb bones. Normal flexion is approximately 80 degrees.

What to expect: The examiner will ask you to bend the tip of your thumb (distal phalanx). They will also attempt passive flexion if active motion is limited. Complete absence of motion confirms IP joint ankylosis.

Pain considerations: Report pain at the IP joint with any attempted motion and at rest. Note whether the fixed position of the IP joint causes pain when the thumb contacts objects.

Repetitive Use / DeLuca Factors Assessment

What it measures: Whether your thumb function deteriorates with repeated use - captures pain on use, fatigability, weakness, and incoordination not apparent at initial examination. Required under DeLuca v. Brown.

What to expect: The examiner may ask you to perform repeated grip or pinch motions and assess whether symptoms worsen. They should document DeLuca factors even for ankylosed joints. If they do not ask, volunteer this information.

Pain considerations: Under DeLuca, the examiner must consider pain, fatigue, weakness, and incoordination as functional loss. If the examiner only records static joint position without asking about these factors, respectfully mention them yourself.

Hand Grip Strength Testing

What it measures: Overall grip strength of the affected hand compared to the unaffected hand. Thumb ankylosis typically reduces grip significantly, particularly pinch strength.

What to expect: The examiner may use a dynamometer or manual grip testing. Pinch strength (lateral pinch, tip pinch, tripod pinch) is especially relevant for thumb conditions.

Pain considerations: State clearly if grip testing causes pain that would limit work tasks requiring hand strength.

20%

Unfavorable ankylosis of the thumb. Assigned when: (1) either the CMC or IP joint is ankylosed AND the opposition gap is greater than 5.1 cm (2 inches); OR (2) both the CMC and IP joints are ankylosed regardless of gap; OR (3) amputation at the CMC joint or through proximal phalange. A 20% rating applies to BOTH the dominant and non-dominant thumb.

From 38 CFR: Under DC 5224: Unfavorable ankylosis is rated at 20% for both dominant and non-dominant hands. The VA note under DC 5224 also directs evaluators to consider whether amputation rating is warranted and whether additional evaluation is warranted for limitation of motion of other digits or interference with overall hand function.

10%

Favorable ankylosis of the thumb. Assigned when: (1) either the CMC or IP joint is ankylosed AND the opposition gap is 5.1 cm (2 inches) or less; AND (2) only one of the two thumb joints (CMC or IP) is ankylosed, not both; AND (3) the ankylosed joint is in normal anatomical position (not angulated, rotated, or in extreme flexion or extension). A 10% rating applies to BOTH dominant and non-dominant hands.

From 38 CFR: Under DC 5224: Favorable ankylosis is rated at 10% for both dominant and non-dominant hands. Only joints ankylosed in normal anatomical position as defined in the Note preceding DC 5216 are considered favorably ankylosed. If the fixed position is extreme, the favorable designation is lost.

Pain

How to describe it: Describe pain at the ankylosed joint at rest, with light use, and with forceful use. Specify the character (sharp, aching, throbbing), location (base of thumb, tip joint, radiating into hand), and frequency. Distinguish between constant pain and pain triggered by activity.

Example: On my worst days, the base of my thumb aches constantly even when I am not using it. Any attempt to pinch - like opening a jar, turning a key, or holding a pen - causes a sharp, burning pain that makes me stop what I am doing. I cannot grip anything with my thumb for more than two or three minutes before the pain forces me to stop.

Examiner listens for: Localized joint pain consistent with ankylosis, pain with opposition attempts, pain that limits functional tasks, pain that is present at rest indicating more than simple motion limitation, pain that worsens with repetitive use (DeLuca)

Avoid: Do not say 'it is manageable' or 'I just work around it.' This underrepresents your actual limitation. Describe your worst day symptoms, not your coping mechanisms.

Functional Loss from Ankylosis

How to describe it: Explain exactly which daily tasks the fused thumb prevents or limits. Be specific: pinching, key turning, buttoning, gripping, writing, opening containers, shaking hands. Quantify how much time you can perform a task before stopping.

Example: Because my thumb is locked in position, I cannot pinch my fingers together to pick up small objects. I drop items constantly. I cannot button my shirt without help, cannot open pill bottles, cannot turn a key in a lock, and cannot grip a steering wheel normally. I have had to switch to adaptive tools for cooking and writing.

Examiner listens for: Specific task limitations consistent with thumb opposition loss, adaptive behavior indicating compensation, impact on occupational and daily living activities, quantified limitations (time, distance, repetitions)

Avoid: Do not describe tasks you have adapted around without noting you needed to adapt. Do not omit tasks you have simply stopped attempting entirely.

Favorable vs. Unfavorable Position

How to describe it: Describe whether your thumb's fixed position allows any functional use. If fixed in a poor position, explain how it interferes with hand function. If it creates a gap when you try to oppose fingers, estimate or demonstrate that gap.

Example: My thumb is frozen pointing slightly away from my hand. When I try to bring it toward my fingers to pinch something, there is a large gap - more than two inches - between my thumb and fingers. I cannot close that gap no matter how hard I try. The position makes it impossible to grip pens, coins, or buttons.

Examiner listens for: Description of fixed joint position, functional consequences of that position, inability to close the opposition gap, whether the position causes contact issues or pressure points

Avoid: Do not say 'the doctor said it healed in a good position' if in reality you have significant functional loss. Position alone does not determine functional adequacy.

Fatigability and Weakness (DeLuca Factors)

How to describe it: Describe how quickly your hand fatigues when performing tasks requiring thumb use. State your baseline grip strength versus after 5-10 minutes of use. Describe weakness that is present even on initial attempts.

Example: Even on a mild day, my grip is noticeably weaker on my affected hand. After just a few minutes of typing or holding a tool, my hand becomes exhausted and the weakness increases. I sometimes drop objects I thought I had a firm grip on. By the end of the day, I have almost no useful pinch strength left.

Examiner listens for: Quantified weakness compared to other hand, rapid fatigability with repetitive tasks, weakness present at baseline not just after use, incoordination affecting fine motor tasks

Avoid: Do not omit fatigue because you think it is not important for a joint that is already fused. Fatigability of surrounding muscles and tendons is a legitimate functional loss documented under DeLuca.

Flare-Ups

How to describe it: Describe frequency, duration, and severity of flare-ups if you experience them. State triggers (weather, overuse, cold), how symptoms worsen during flares, and how long recovery takes. Connect flare-up symptoms to specific functional limitations.

Example: About three to four times a month, my thumb and the surrounding area swells noticeably and the pain intensifies to the point where I cannot use my hand at all. These flares last two to three days. During a flare, the gap when I attempt to oppose my thumb is noticeably larger because the swelling restricts any movement even more. I cannot perform any fine motor tasks during these periods.

Examiner listens for: Frequency and duration of flares, symptom intensity during flares versus baseline, whether flares cause additional functional loss beyond the ankylosed joint, triggers and recovery pattern

Avoid: Do not describe only your average day. The DBQ specifically asks for flare-up description - ensure you provide this even if the examiner does not ask directly.