Upper Extremities – Thumb and Fingers

We use these guidelines if you received a work-related injury and are curious about the effect of “Scheduled Loss of Use (SLU) on your thumb and fingers. Then, you could be eligible for a compensation payment determined by the Workers’ Compensation Board’s regulations.

Our SLU report will conclude that you have permanently lost function in the injured body part due to your work-related accident. The determination of impairment is based on New York state Workers’ Compensation guidelines.

Objectives for Determining Impairment for Thumb and Fingers

We will accurately assess permanent residual physical deficit due to injury based on a physical evaluation, possible degree, and appropriate diagnostic testing.

Permanent Impairment Assessment Methods

We determine the degree of permanent residual physical deficit at the time of maximum medical improvement (MMI) without expected further progress based on the clinical treatment outcome, our expertise, and additional treatment options.

We must consider the patient’s contralateral extremity when available and within expected values during the level of permanent residual physical deficit. The MMI duration from the date of injury is usually one year of the injury or surgery, but it varies.

However, the permanent residual physical deficit severity at the time of MMI and not the mechanism of injury may include bone, muscle, cartilage, tendons, nerves, blood vessels, or other tissue damage.

Maximum Rating of Body Part

We must utilize the Guidelines during permanent residual physical deficit evaluation of the thumb and fingers. In addition, we will evaluate single-digit loss or impairment based on the digit and not part of the hand. If multiple joints are affected, the total range of motion value must not exceed the maximum digit value.

As a result, the total impairment must not exceed 100% of the following most prominent major body member when evaluating multiple digit impairments. If the loss of numerous digits results in hand impairment, it must not exceed 100% of the scheduled loss of the hand.

Thumb

The thumb is the highest valued digit and works with the other fingers to reach, pinch, grasp, grip, and manipulate items. Pinching, precision, and power grips require thumb flexion, opposition, and adduction.

The thumb’s functional units are the proximal and distal phalanges, interphalangeal, metacarpal, and carpometacarpal joints. Therefore, you are not eligible for reconstructive surgery if hand function impairment presents with a loss of pinch and a minimized grasping power.

Thumb Range of Motion

We place the hand supine, palm up, and thumb in full extension. Then, fully flex the IP joint of the thumb. The normal range of motion for the IP joint is 80 degrees.

We position the hand supine, palm up, and the thumb in full extension. Then, flex the MCP to the fullest extent to measure the angle between the first metacarpal and the proximal phalanx. The normal range of motion for the MCP joint is 60 degrees.

Most hand activities perform flexion, adduction, and opposition motions, including tip-to-tip pinching contact, prehension, and object manipulation.

We measure by:

Place the hand supine, palm up, and fully flex the thumb across the palm as the thumb rotates. This rotation is noticeable with changing thumbnail position. Additional rotation degrees bring the thumb tip in contact with the MCP and transition from full flexion to the opposition.

• Full opposition occurs when the thumb tip contacts the pinky/little finger’s (4th finger) MCP.

   

• The tip of the thumb contacts the ring finger’s (3rd finger) MCP but not the pinky’s MCP in a mild deficit (1).

   

• The tip of the thumb contacts the middle finger’s (2nd finger) MCP but not the ring finger’s MCP in a moderate deficit (2).

   

• The tip of the thumb contacts the index finger’s (1st finger) MCP but not the middle finger’s MCP in a marked deficit (3).

We place the forearm in a neutral resting position and move the thumb outward to perform maximum movement while the thumb contacts the first finger. Then we measure the angle as the MCP joint abducts to the fullest extent. The normal radial abduction range of motion is 90 degrees.

We place the supine hand palm up, fully extend the thumb joints along the supine plane (radial extension) and position the thumb perpendicular to the palm. Then, we measure the thumb’s capability to touch each fingertip.

Calculating Loss of Use of Thumb

We will assess whether special considerations apply to determine the overall schedule loss of thumb use. If there are no special considerations, we calculate the schedule loss of thumb by measuring each joint and adding deficit values using the table. Use the lower figure if a single motion deficit exists, such as flexion or extension.

We may need to use a reduction to the sum of two significant values when using the range of motion to determine schedule loss of use. Still, the total can not exceed the ankylosis value.

Thumb

*We use the lower figure if a single motion deficit exists, such as flexion or extension. However, we use the higher figure if both flexion and extension apply.

NOTE: Without other existing deficits:

• Mild impairment of thumb adduction equals a 71⁄2% loss of use of the thumb.

   

• Mild impairment of thumb opposition equals a 10% loss of use of the thumb.

   

• Mild impairment of the radial abduction is equal to a 10% loss of use of the thumb.

   

• A higher schedule may be appropriate for more significant adduction, opposition, or abduction.

Thumb Special Considerations

Special considerations in the final adjustment of the fingers include the following:

1. Active flexion loss or ankylosis at the CMC joint creates a 100% use of the thumb loss, typically associated with wrist deficits, becoming a hand schedule.

    

2. A hand schedule may produce a mild, moderate, or marked pinch or grasping hand power impairment resulting from thumb abduction and opposition on the CMC joint with possible MCP and IP joint deficits.

Fingers

The metacarpophalangeal (MCP joint), proximal interphalangeal (PIP), and distal interphalangeal (DIP) comprise the index through the small finger (fingers 1-4, according to WCB). The MCP joint allows finger flexion and extension and is associated with grip and pinch activities.

1. Distal Interphalangeal (DIP) Joint Measurement Position
(The normal DIP range of motion is 90 degrees)

Flexion: We position the hand prone, extend the fingers, and measure the angle between the middle phalanx and distal phalanx while flexing/stabilizing the DIP joint toward the palm. During this maneuver, we block PIP flexion.

Extension: We place the hand prone, fully flex the DIP joints, and measure the angle between the middle phalanx and distal phalanx joint during extension away from the palm.

(The normal PIP range of motion is 100 degrees)

Flexion: We extend the fingers in a horizontal position with the palm and wrist and measure the angle between the middle and proximal phalanx while flexing the PIP joint toward the palm. During this maneuver, we block MCP flexion.

Extension: We fully flex the PIP joints and measure the angle of the horizontally extended PIP joint toward the finger position.

(The normal MCP range of motion is 90 degrees)

Flexion: We extend the fingers and measure the angle between the metacarpal bone and the proximal phalanx while flexing the MCP joint toward the palm.

Extension: We fully flex the MCP joints and measure the angle as extending the MCP joint to the maximum.

Calculating Loss of Use of Finger

We will begin to assess if any special considerations apply to determine the overall schedule loss of finger use.

If there are no special considerations, we calculate the scheduled loss of use of the finger by measuring each joint and adding any deficit values using the table. We use the lower figure if a single motion deficit exists, such as flexion or extension. However, we use the higher figure if both flexion and extension apply.

We may need to use a reduction to the sum of two significant values when using the range of motion to determine schedule loss of use. Still, the total can not exceed the ankylosis value.

Table: Finger

Finger Special Considerations

We utilize the special considerations when evaluating enumerated schedule loss of use values and add other deficits when specified. However, the maximum schedule loss of use value must not exceed the ankylosis value except when applying special consideration number five.

1. Mallet deformity: Depending on the degree, upwards of 331⁄3% loss of a finger.

    

2. Trigger finger: Upwards of 331⁄3% loss of a finger. If the thumb or index finger, use the maximum value (331⁄3%).

    

3. Flail DIP joint: 50% loss of the finger.

    

4. 50% or more distal phalanx loss equals 50% loss of use of the finger.

    

5. Dupuytren’s Contracture: Requires an ODNCR or ANCR for Dupuytren’s Contracture before the scheduled evaluation, and the injury or occupational disease must limit the scheduled loss. If only one finger is involved, hand impairment equals 5% to 71⁄2% loss of use of the hand. If two or three fingers compromise hand function, such as grasping power, we evaluate a more extensive schedule as recognized by a value exceeding ankylosis of the affected finger.

Loading

When multiple digits become affected, loading is the added schedule amount allowing for grasping weakness or significant function loss. Therefore, we convert multiple digit losses to the overall hand schedule. However, schedules less than 50% in one or two digits will remain in the digits, not within a hand schedule.

Calculating the overall loading value:

1. We determine the number of weeks per digit by multiplying the percentage loss of use per digit by the maximum allowable weeks per digit.

    

2. We determine the “total digit weeks” by adding the number of weeks per digit.

    

3. We determine the overall number of “loading weeks” by multiplying the “total digit weeks” by the loading percentage and adding it to the “total digit weeks.”

    

4. We divide the value by the hand’s maximum statutory weeks value. Then, we convert to a loss of hand percentage by multiplying the quotient by 100.

Example:

We utilize a 50% loss of use of the index finger, and a 60% loss of use of the thumb is given a 60% load and converted to a hand schedule (Scenario C below).

1. (A) 50% Loss of Index 23 weeks (50% of 46 weeks)

   (B) 60% Loss of Thumb 45 weeks (60% of 75 weeks)

    

2. Total Digit Weeks (A plus B) 68 weeks (23 + 45)

    

3. Total Weeks including 60% load 108.8 weeks ((68 x 60%)+68)

    

4. Converted to Hand Schedule 44.6% ((108.8/244) x 100)

Table: Loading of two affected digits

• Scenario A – No loading if one digit has a 50% loss of use and another has less than 50%. We provide each finger with a different percentage.

   

• Scenario B – The load equals 60%. It becomes converted to a hand schedule if one digit has a 100% loss of use and another has 50%.

   

• Scenario C – We load at 60% and convert to a hand schedule for schedules with at least 50% in two digits.

   

• Scenario D – We load at 60% and convert to a hand schedule for schedules with 100% bone loss in the thumb or index finger and less than 50% loss of use in a second digit.

Table: Loading of at least three affected digits

• Scenario A – We load at 30% and convert to a hand schedule with 50% finger loss of use in each finger.

   

• Scenario B – We load at 60% and convert to a hand schedule with at least 50% loss of use in two or more digits.

Table: Amputations Loading

• Scenario A – We load at 60% and convert to a hand scheduled for amputation of half of the distal phalanges of at least two digits or DIP joint ankylosis of at least two digits.

   

• Scenario B – We load at 60% and convert to a hand schedule for amputation through the middle phalanges of at least two digits.

   

• Scenario C – We load at 120% and convert to a hand schedule for amputations through the proximal phalanges of at least two digits.

   

• Scenario D – We load at 120% and convert to a hand schedule for amputations of the first metacarpal of the thumb.

Amputation

The amputation level depends on the residual impairment and functional loss evaluation. Operative amputations typically occur higher than the level of injury to obtain adequate closure or proper functioning, resulting in misleading initial x-ray imaging reports.

Therefore, we will obtain new post-operative x-ray images to determine the bone loss degree and the final level of amputation required for schedule loss calculation.

1. We use a 100% loss of use of the hand for the loss of all fingers at the proximal phalanges.

    

2. A 15-20% loss of use of the finger equals the loss of the tip of the tuft with bone loss of the distal phalanx. Then, if present, we add the mobility deficit percentage at the DIP joint.

    

3. We utilize a 33 1⁄3% loss of use of the finger with a loss through the bass of the tuft.

    

4. 50% loss of the use of a finger equals the loss of half or all of the distal phalanx. Therefore, we do not add values for mobility impairment at the DIP joint.

    

5. We use a 50% loss of use of the finger for amputation through the DIP joint.

    

6. We utilize a 100% loss of use of the finger with a loss of any portion of the middle phalanx.

    

7. We use a 100% loss of use of the finger for losses affecting the proximal phalanx.

    

8. We evaluate a 100% loss of use of the thumb within 75 weeks and use a 120% load converted to a hand schedule if the amputation is proximal to the MCP joint.

    

9. Entire finger losses involving any portion of the metacarpal ray equate to a 100% digit use loss, loaded to 120%, and converted to a hand schedule.

    

10. We provide additional schedules in cases when evaluating 100% for a body member under special circumstances, such as a 100% loss of arm for an above-the-elbow amputation.

Please refer to your state’s Workers’ Compensation Board website or speak with your Workers’ Compensation attorney for more information.