Rating Lower Extremity Impairments Handout · PDF file1 1 Rating Lower Extremity Impairments...

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Rating Lower Extremity Impairments

2017 DWC Conference

Disability Evaluation Unit

Thirteen Methods For Rating Lower Extremity Impairment

1) Limb Length

2) Amputation

3) Muscle Atrophy

4) Arthritis

5) Range of Motion

6) Ankylosis

7) Peripheral nerve

8) Muscle Strength

9) Gait

10) CRPS

11) Skin Loss

12) Vascular

13) Diagnosed Based

Impairments

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Lower Extremity Methods

• Typically one method will adequately characterize the impairment

• In some cases more than one method will be used to assess all features of the impairment

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Cross-usage chart (Table 17-2, pg. 526)

• Guide for avoiding duplication for the same body part

• Shows which combinations of methods are allowable

• Note that X doesn’t mark the spot!

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Combining Impairments(Table 17-2 Condensed)

Gait Atrophy Muscle

Strength

ROM DJD DBE

Gait X X X X X

Atrophy X X X X X

Muscle

Strength

X X X X X

ROM X X X X X

DJD X X X X

DBE X X X X

Can range of motion and arthritis be combined?

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Combining Lower Extremity Impairments

• Common sense must be applied to Table 17-2

• For example a knee meniscectomy (DBE) may be combined with decreased hip range of motion

• Even though there is an “X” for this combination, these impairments are for different regions

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Regions of the Lower Extremity

• Hip

• Knee

• Ankle

• Foot

17.01 Impairments

• Limb length

• Amputation

• Gait

• Skin loss

• Peripheral nerve

• Vascular

• CRPS7

Lower Extremity Indices

• Lower Extremity Index

– Abbreviation = LE

– Used for all impairments from ankle to hip

– Lower Extremity Index x .4 = Whole Person Index

• Foot Index

– Abbreviation = FT

– Used only for impairments of foot and toes

– Foot index x .7 = Lower Extremity Index8

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Limb Length (Table 17-4, pg. 528)

• Based on limb length difference

• X-rays are the preferred method of measurement

• Interpolate between values

• Minimum ratable difference is 2 cm.

• Use lower extremity (LE) index

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Limb Length Discrepancy Impairment

0-1.9 cm 0

2-2.9 cm 2-3 (5-9)

3-3.9 cm 4-5 (10-14)

4-4.9 cm 6-7 (15-19)

5+ cm 8 (20)

Limb Length (Table 17-4, pg. 528)

• In cases when shortening is due to malalignment or fracture deformities

• Use chart beneath Table 17-4

• Look for accompanying fracture/deformity DBE

impairments

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Limb Length Discrepancy Impairment

0-1.25 cm 5 LE

1.25-2.5 cm 10 LE

2.5-3.75 cm 15 LE

3.75-5 cm 20 LE

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Muscle Atrophy (Table 17-6)

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• If both calf and thigh atrophy for same region injured, combine at LE impairment and run one string of formula.

Muscle Atrophy Example

Grocery clerk, 38 years old fractured right distal tibia when slipped on banana. Fracture healed well after 3 months in cast. At MMI, 3 cm. difference in calf circumference and 2 cm. in thigh circumference.

2 cm. thigh atrophy =

3 cm. calf atrophy =

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Grocery clerk, 38 years old fractured right distal tibia when slipped on banana. Fracture healed well after 3 months in cast. At MMI, 3 cm. difference in calf circumference and 2 cm. in thigh circumference.

2 cm. thigh atrophy = 8 LE

3 cm. calf atrophy = 13 LE

13 C 8 = 20 LE x .4 = 8 WP

17.07.01.00 – 8 – [1.4]11 – 214F – 11 – 11 Final PD

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Ankylosis

• Ankylosis within an optimal range receives a base impairment value

• Use Tables 17-15 to 17-28, pages 538-541 to determine added impairment for ankylosis outside of optimal range

• Combined value for one extremity cannot exceed 100 LE

Ankylosis

• Base Values for Ankylosis

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Lower Extremity Joint Base Ankylosis Value

Hip 50 LE

Knee 67 LE

Ankle 10 LE

Hindfoot 10 LE

Pantalar 25 LE

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Hip Ankylosis Example

Taxi driver, 45 years old

• Optimal range for hip– 25° to 40° flexion, 0° abduction, 0° rotation– Base value = 50 LE

• Ankylosis measurements– Flexion 50°– Abduction 14°– Ext. rotation 19°

Hip Ankylosis Flexion (Table 17-15)

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Ankylosis in Flexion Impairment

0-9 degrees 15 (37)

10-19 degrees 10 (25)

20-24 degrees 5 (12)

25-39 degrees 0 (0)

40-49 degrees 5 (12)

50-59 degrees 10 (25)

60-69 degrees 15 (37)

70+ degrees 20 (50)

The appropriate ankylosis impairment percent is added to the impairment to the

impairment percent given in the text

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Hip Ankylosis Abduction(Table 17-18)

Ankylosis in Abduction Impairment

5-14 degrees 10 (25)

15-24 degrees 15 (37)

25+ degrees 20 (50)

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The appropriate ankylosis impairment percent is added to the impairment to the

impairment percent given in the text

Hip Ankylosis External Rotation (Table 17-17)

Ankylosis in External Rotation Impairment

10-19 degrees 5 (12)

20-29 degrees 10 (25)

30-39 degrees 15 (37)

40+ degrees 20 (50)

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The appropriate ankylosis impairment percent is added to the impairment to the

impairment percent given in the text

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Hip Ankylosis Example

• Ankylosis measurements

• Flexion 50o = 25 LE

• Abduction 14o = 25 LE

• External rotation 19o = 12 LE

• Base Value 50 LE

112 LE

Cannot exceed 100 LE!

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Hip Ankylosis Example

• 100 LE x .4 = 40 WP

• Formula

17.03.02.00 – 40 – [1.4]56 – 250F – 56 – 58 PD

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Amputation (Table 17-32, pg. 545)

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Arthritis (Table 17-31, pg. 544)

• Impairment value based on cartilage interval of the affected joint

• Based on standard x-rays with individual in standing position, if possible.

• The knee joint must be in neutral flexion-extension position (0o) to evaluate x-rays. Except with knee flexion contractures, then ROM should be used.

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Knee Arthritis Example

Plumber, 30 years old

Left knee medial compartment 1 cm cartilage space

Left knee lateral compartment 2 cm cartilage space

Left patellofemoral pain and creptitation with no joint space narrowing

Arthritis (Table 17-31, pg. 544)

Cartilage Interval

Cartilage Interval

Cartilage Interval

Cartilage Interval

Joint 3mm 2 mm 1 mm 0 mm

Sacroiliac (3 mm) --------- 1 (2) 3 (7) 3 (7)

Hip (4 mm) 3 (7) 8 (20) 10 (25) 20 (50)

Knee (4 mm) 3 (7) 8 (20) 10 (25) 20 (50)

Patellofemoral+ --------- 4 (10) 6 (15) 8 (20)

Ankle (4 mm) 2 (5) 6 (15) 8 (20) 12 (30)

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Arthritis (Table 17-31, pg. 544)

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Knee Arthritis Example

• Left Knee DJD 25 LE

• Left patellofemoral DJD 5 LE

• 25 C 5 = 29 LE x .4 = 12 WP

• Formula:

17.05.03.00 – 12 – [1.4]17 – 481I – 23 – 20 PD

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Skin Loss (Table 17-36, pg.550)

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Peripheral Nerve (Table 17-37, pg. 552)

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Peripheral Nerve

• Maximum nerve value from Table 17-37

• Physician grades motor and sensory deficits

• Multiply maximum nerve impairment by percentage deficit

Nerve deficits

• Motor

• Sensory

• Dysesthesia

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Peripheral/Vascular(Table 17-38, pg. 554)

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Peripheral Vascular

Criteria for class placement

• Claudication – cramping due to insufficient blood

• Edema – swelling

• Vascular Damage

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Complex Regional Pain Syndrome

Characterized by

• Pain

• Swelling

• Stiffness

• Discoloration

• Demineralization

CRPS I

• Reflex sympathy dystrophy

CRPS II

• Causalgia

• Originates from injury to peripheral nerve

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Complex Regional Pain Syndrome

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• Use Table 13-15 to rate CRPS

• Should have CRPS diagnosis

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Range of Motion (ROM)

• Measurement principles

– Use active motion

– Take three measurements of each motion

– Use the largest measured range

– Values for same joint are added

– No interpolation of values within tables

– Additional values are given for varus or valgus angulation of knee, ankle or foot

• Applicable tables: 17-9 to 17-14, p. 537

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Range of Motion (ROM)

Varus and Valgus

Varus is the inward angulation of the distal segment of a bone or joint

Valgus is the outward angulation of the distal segment of a bone or joint

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Range of Motion (ROM)

Flexion Contracture

• Loss of extension

• Inability to straighten joint

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• Occupation – pilot Age – 43 • ROM measurements

– Extension loss 12°– Flexion 95°– Abduction 14°– Adduction 5°– Ext. rotation 19°– Int. rotation 13°

Hip ROM Example

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Hip ROM Example (Table 17-9)

Ext -12

Flex 95

Abd 14

Add 5

ER 19

IR 13

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Hip ROM Example

• Occupation – pilot Age – 43 • ROM measurements

– Extension loss 12° 5 LE

– Flexion 95° 5 LE

– Abduction 14° 10 LE

– Adduction 5° 5 LE

– Ext. rotation 19° 10 LE

– Int. rotation 13° 5 LE

40 LE

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• Total = 40 LE x .4 = 16 WP

• Formula

17.03.04.00 – 16 – [1.4]22 – 250F – 22 – 2 PD

Hip ROM Example

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Gait Derangement (Table 17-5)

• Cannot be combined with other lower impairments

• Should be supported by pathologic findings

• Does not apply to subjective factors such as pain

• Whenever possible evaluator should use a more specific method

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AMA Example 17-2

• Right knee DJD: 3 WP

• Use of cane for walking: 20 WP

• Gait derangement used when accurately represents the clinical situation

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Table 17-5 examples

• Requires routine use of short-leg brace – 15 WP

• Requires routine use of cane, crutch, or long-leg brace – 20 WP

• Wheelchair dependent – 80 WP

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Muscle Strength (Table 17-8, pg. 532)

• Typical causes: compartment syndrome, muscle trauma

• Not suitable for neurological losses – use peripheral nerve method instead

• Grades of muscle weakness defined in Table 17-7, page 531

• Impairment rating for gait should not exceed the maximum value level of amputation for a single extremity.

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Muscle Strength Impairment

• Table 17-8

• Graded (0-5 -5 normal)

• Graded for each unit of motion

• Multiple impairments in a joint combined at LE index

• Not used for peripheral nerve injury

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Grading Muscle Function (Table 17-7)

5 – Active movement against gravity with full resistance

4 – Active movement against gravity with some resistance

3 – Active movement against gravity only, without resistance

2 – Active movement with gravity eliminated

1 – Slight contraction and no movement

0 – No contraction

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Muscle Strength Example

Sales clerk, 38 years old• Knee

– Extension grade 4 = 12 LE

– Flexion grade 4 = 12 LE

• 12 C 12 = 23 LE

• 23 LE x .4 = 9 WP

17.05.05.00 – 9 – [1.4]13 – 214F – 13 – 13 PD

Muscle Strength

Ext 12 LE

Flex 12 LE

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Diagnosis-Based Estimate (DBE)

• Primary table is 17-33, page 546-7

• Typical examples– Meniscectomy

– Ligament laxity

– Fractures

– Foot deformities

– Hip and pelvic bursitis

– Lower extremity joint replacements

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Diagnosis-Based Estimate

• Knee and Hip replacements get special treatment

– Replacement score is developed using Table 17-34 (hip) or 17-35 (knee)

– Score based on pain, function, ADL impacts, ROM etc.

– Knee and Hip replacement result

• Good: 15 WP

• Fair: 20 WP

• Poor 30 WP

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Diagnosis-Based Estimate

• Duplication must be avoided

• DBE’s cannot be combined with gait, atrophy, strength or ROM/ankylosis for the same body part per Cross-usage chart (p. 526)

• DBE’s can be combined with each other, e.g. laxity and meniscectomy for same knee

Multiple Impairment Example

Farm laborer, 22 years old, was run over by tractor crushing his lower leg. The leg was amputated at the mid-tibia level. Knee ROM was reduced with flexion to 75o and 20o extension loss. Measurements show two inches of thigh atrophy. A full time use of cane was prescribed.

Amputation at mid-tibia level:

Gait impairment (cane):

Knee ROM:

Thigh atrophy:

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Multiple Impairment Example

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Leg amputated at the mid-tibia level:

Amp 70 LE

Multiple Impairment Example

Full time use of cane was prescribed.

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Gait 20 WP

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Multiple Impairment Example

Knee ROM S: 0-20-75

Ext 20 + Flex 20 = 40 LE = 16 WP

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Flex 20 LE

Ext 20 LE

Multiple Impairment Example

Thigh atrophy of 2 inches (1” = 2.54 cm.)

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11LE

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Multiple Impairment Example

Questions…

1.Can Gait be combined with other impairments?

2.Can Knee ROM be combined with atrophy?

3.Can amputation and Knee ROM be combined?

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Combining Impairments(Table 17-2 Condensed)

Gait Atrophy Muscle

Strength

ROM DJD Amp

Gait X X X X X

Atrophy X X X X X

Muscle

StrengthX X X X X

ROM X X X X

DJD X X X X

Amp X X X

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Multiple Impairment Example

Amputation at mid-tibia:

17.01.02.02 – 28 – [1.4]39- 491H- 45 – 39 PD

Knee ROM:

17.05.04.00 – 16 – [1.4]22- 491H – 27 – 23 PD

39 C 23 = 53 PD

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Multiple Impairment Example

Per PDRS page 1-11, rating cannot exceed value for entire leg amputation.

17.01.02.01 – 40 – [1.4]56 – 491H – 62 – 57 PD

Therefore final rating is 57 PD

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Questions

Where the Pavement Ends

The fun begins

Where the Pavement Ends

Redding California

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