OAR 436-035-0011
Determining Percent of Impairment


(1)

The total impairment rating for a body part cannot be more than 100% of the body part.

(2)

When rating disability the movement in a joint is measured in active degrees of motion. Impairment findings describing lost ranges of motion are converted to retained ranges of motion by subtracting the measured loss from the normal of full ranges established in these rules.

(a)

Range of motion values for each direction in a single joint are first added, then combined with other impairment findings. [Example not included. See ED. NOTE.]

(b)

Range of motion values for multiple joints in a single body part (e.g., of a finger) are determined by finding the range of motion values for each joint (e.g., MCP, PIP, DIP) and combining those values for an overall loss of range of motion value for that body part. This value is then combined with other impairment values.

(3)

The range of motion or laxity (instability) of an injured joint is compared to and valued proportionately to the contralateral joint except when the contralateral joint has a history of injury or disease or when either joint’s range of motion is zero degrees or is ankylosed. The strength of an injured extremity, shoulder, or hip may be compared to and valued proportionately to the contralateral body part except when the contralateral body part has a history of injury or disease.
Instability example:
The injured knee is reported to have severe instability of the anterior cruciate ligament. The standards grant an impairment value of 15% for severe instability of the anterior cruciate ligament.
The contralateral knee is reported to have mild instability of the anterior cruciate ligament. The standards grant an impairment value of 5% for mild instability of the anterior cruciate ligament.
A proportion is established by subtracting the contralateral instability of 5% from the 15% for the injured joint which = 10% impairment for the instability.
Strength example:
The injured deltoid muscle is reported to have 35 strength. The standards note 35 strength = 50%.
The contralateral deltoid muscle is reported to have 4+/5 strength. The standards note 4+/5 strength = 10%.
A proportion is established by subtracting the contralateral strength of 10% from the 50% for the injured arm which = 40%. This percentage is then used to determine the loss of strength for the injured deltoid.
Range of motion examples:
Flexion (knee): 80° retained on injured side, the contralateral joint flexes to 140°.
A proportion is established to determine the expected degrees of flexion since 140° has been established as normal for this worker.
One method of determining this proportion is: 80140 = X/150.
X = expected retained range of motion compared to the established norm of 150° upon which flexion is determined under these rules. X, in this case, equals 86°.
86° of retained flexion of the knee is calculated under these rules, after rounding, to 23% impairment.
Extension (knee): 35° retained on injured side, the contralateral joint extends to 15°. First, find the complement, i.e., 150 - 15 =135 (uninjured) and 150 - 35 = 115 (injured). Next, using the same method as for flexion, 115135 = X/150, or, X = 127.77. Then, revert back, so, 150 - 127.77 = 22.23 rounded to 22° for an impairment value of 9%.

(a)

If the motion of the injured or contralateral joint exceeds the values for ranges of motion established under these rules, the values established under these rules are maximums used to establish impairment.

(b)

When the contralateral joint has a history of injury or disease, the findings of the injured joint are valued based upon the values established under these rules.

(4)

Specific impairment findings (e.g., weakness, reduced range of motion, etc.) are awarded in whole number increments. This may require rounding non-whole number percentages and contralateral comparison degrees of motion for given impairment findings before combining with any other applicable impairment value.

(a)

Except for subsection (b) of this section, before combining, the sum of the impairment values is rounded to the nearest whole number. For the decimal portion of the number, point 5 and above is rounded up, below point 5 is rounded down. [Example not included. See ED. NOTE.]

(b)

When the sum of impairment values is greater than zero and less than 0.5, a value of 1% will be granted. [Example not included. See ED. NOTE.]

(5)

If there are impairment findings in two or more body parts in an extremity, the total impairment findings in the distal body part are converted to a value in the most proximal body part under the applicable conversion chart in these rules. This conversion is done prior to combining impairment values for the most proximal body part. [Example not included. See ED. NOTE.]

(6)

Except as otherwise noted in these rules, impairment values to a given body part, area, or system are combined as follows:

(a)

The combined value is obtained by inserting the values for A and B into the formula A + B(1.0 - A). The larger of the two numbers is A and the smaller is B. The whole number percentages of impairment are converted to their decimal equivalents (e.g., 12% converts to .12; 3% converts to .03). The resulting percentage is rounded to a whole number as determined in section (1) of this rule. Upon combining the largest two percentages, the resulting percentage is combined with any lesser percentage(s) in descending order using the same formula until all percentages have been combined prior to performing further computations. After the calculations are completed, the decimal result is then converted back to a percentage equivalent. Example: .12 + .03(1.0 - .12) =.12 + .03(.88) =.12 + .0264 =.1464 = 14.6 = 15. [Example not included. See ED. NOTE.]

(b)

Impairment values for a given body part, area, or system must be combined before combining with other impairment values. If the given body part is an upper or lower extremity, ear(s), or eye(s) then the impairment value is to be converted to a whole person value before combining with other impairment values, except when the date of injury for the claim is prior to Jan. 1, 2005. [Example not included. See ED. NOTE.]

(7)

Loss of strength is determined using the modified 0 to 5 international grading system described below. The grade of strength is reported by the physician and assigned a percentage value from the table in subsection (a) of this section. The impairment value of the involved nerve, which supplies (innervates) the weakened muscle, is multiplied by this value. Grades identified as ”++” or ”--” are considered either a ”+” or ”-”, respectively.

(a)

The grading is valued as follows: [Example not included. See ED. NOTE.]

(b)

When a physician reports a loss of strength with muscle action (e.g., flexion, extension, etc.) or when only the affected muscle(s) is identified, anatomy texts or the AMA Guides to the Evaluation of Permanent Impairment may be referenced to identify the specific muscle(s), peripheral nerve(s) or spinal nerve root(s) involved. A copy of the standards referenced in this rule is available for review during regular business hours at the Workers’ Compensation Division, 350 Winter Street NE, Salem OR 97301, 503-947-7810.

(8)

For muscles supplied (innervated) by the same nerve, the loss of strength is determined by averaging the percentages of impairment for each involved muscle to arrive at a single percentage of impairment for the involved nerve. [Example not included. See ED. NOTE.]

(9)

When multiple nerves have impairment findings found under these rules, these impairment values are first combined for an overall loss of strength value for the body part before combining with other impairment values.

(10)

When a joint is ankylosed in more than one direction or plane, the largest ankylosis value is used for rating the loss or only one of the values is used if they are identical. This value is granted in lieu of all other range of motion or ankylosis values for that joint.
[Publications: Publications referenced are available from the agency.]
[ED. NOTE: Examples referenced are available from the agency.]
[ED. NOTE: To view attachments referenced in rule text, click here to view rule.]

Source: Rule 436-035-0011 — Determining Percent of Impairment, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=436-035-0011.

436‑035‑0001
Authority for Rules
436‑035‑0002
Purpose of Rules
436‑035‑0003
Applicability of Rules
436‑035‑0005
Definitions
436‑035‑0006
Determination of Benefits for Disability Caused by the Compensable Injury
436‑035‑0007
General Principles
436‑035‑0008
Calculating Disability Benefits (Dates of Injury prior to 1/1/2005)
436‑035‑0009
Calculating Disability Benefits (Date of Injury on or after 1/1/2005)
436‑035‑0011
Determining Percent of Impairment
436‑035‑0012
Social-Vocational Factors (Age/Education/Adaptability) and the Calculation of Work Disability
436‑035‑0013
Findings of Impairment
436‑035‑0014
Worsened Pre-existing Conditions and Combined Conditions
436‑035‑0015
Offsetting Prior Awards
436‑035‑0016
Reopened Claim for Aggravation/Worsening
436‑035‑0017
Authorized Training Program (ATP)
436‑035‑0018
Death
436‑035‑0019
Chronic Condition
436‑035‑0020
Parts of the Upper Extremities
436‑035‑0030
Amputations in the Upper Extremities
436‑035‑0040
Loss of Opposition in Thumb/Finger Amputations
436‑035‑0050
Thumb
436‑035‑0060
Finger
436‑035‑0070
Conversion of Thumb/Finger Values to Hand Value
436‑035‑0075
Hand
436‑035‑0080
Wrist
436‑035‑0090
Conversion of Hand/Forearm Values to Arm Value
436‑035‑0100
Arm
436‑035‑0110
Other Upper Extremity Findings
436‑035‑0115
Conversion of Upper Extremity Values to Whole Person Values
436‑035‑0130
Parts of the Lower Extremities
436‑035‑0140
Amputations in the Lower Extremities
436‑035‑0150
Great Toe
436‑035‑0160
Second through Fifth Toes
436‑035‑0180
Conversion of Toe Values to Foot Value
436‑035‑0190
Foot
436‑035‑0210
Conversion of Foot Value to Leg Value
436‑035‑0220
Leg
436‑035‑0230
Other Lower Extremity Findings
436‑035‑0235
Conversion of Lower Extremity Values to Whole Person Values
436‑035‑0250
Hearing Loss
436‑035‑0255
Conversion of Hearing Loss Values to Whole Person Values
436‑035‑0260
Visual Loss
436‑035‑0265
Conversion of Vision Loss Values to Whole Person Values
436‑035‑0330
Shoulder Joint
436‑035‑0340
Hip
436‑035‑0350
General Spinal Findings
436‑035‑0360
Spinal Ranges of Motion
436‑035‑0370
Pelvis
436‑035‑0375
Abdomen
436‑035‑0380
Cardiovascular System
436‑035‑0385
Respiratory System
436‑035‑0390
Cranial Nerves/Brain
436‑035‑0395
Spinal Cord
436‑035‑0400
Mental Illness
436‑035‑0410
Hematopoietic System
436‑035‑0420
Gastrointestinal and Genitourinary Systems
436‑035‑0430
Endocrine System
436‑035‑0440
Integument and Lacrimal System
436‑035‑0450
Immune System
436‑035‑0500
Rating Standard for Individual Claims
Last Updated

Jun. 8, 2021

Rule 436-035-0011’s source at or​.us