the lower extremities ama g uides chapter … 1 the lower extremities ama g uides chapter 17 tim...

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THE LOWER EXTREMITIES

AMA GUIDES CHAPTER 17

Tim Mussack

Marlene Phillips

Bradford & Barthel, LLP

AMA Analysis and Ratings Division

Bradford & Barthel

AMA Analysis and Ratings Division

• Tim Mussack

(916) 569-0790

[email protected]

• Marlene Phillips

(909) 476-0552

[email protected]

• [email protected]

http://www.bradfordbarthel.com/areas-of-practice/bb-ratings/rating-referral-form/

www.bradfordbarthel.com 2

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Most Frequently Used Chapters• Chapters 1 & 2 --- The ‘Constitution’

– From page 17, in the Introduction to Chapter 2, the Practical Application of the Guides:

“Two physicians, following the methods of the Guides to evaluate the same patient, should report similar results and reach similar conclusions. Moreover, if the clinical findings are fully described, any knowledgeable observer may check the findings with the Guides criteria.”

• The Almaraz Guzman en banc decision of 9/3/2009:

“…by requiring use of the AMA Guides to determine impairment, the Legislature furthered its expressly stated goal of achieving “consistency, uniformity, and objectivity.”

• Chapter 15 --- Spine

• Chapter 16 --- Upper Extremity (UE)

• Chapter 17 --- Lower Extremity (LE)


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The Lower Extremities

• Lower extremity impairment values

• Combining

– Impairment

– PD (after adjustment)

• Methods of Evaluation


Chapter 17 – The Lower Extremitiesthere are errata

• 17.1 Principles of Assessment

(p. 524-525)

• 17.2 Methods of Assessment (p. 525-554)

• 17.3 LE Impairment Evaluation Procedure Summary and Examples (p. 555-560)

• Impairment evaluations are performed after the injured worker attains MMI


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‘Regional’ Impairment

• AMA Guides is not jurisdictionally specific for evaluating Permanent Disability

• The California Schedule for Rating gives additional instructions for rating Permanent Disabilities.

• Section 1 of the rating schedule is Introduction and Instructions.

From page 1-4:

• "The impairment number identifies the body part, organ system and/ or nature of the injury..."

• "Under Section 2 of the Permanent Disability Rating Schedule, an appropriate impairment number can be found for most impairments."

On page 1-5:

• "A single injury can result in multiple impairments of several parts of the body. For example, an injury to the arm could result in limited elbow range of motion and shoulder instability..."

On page 1-11 of the Schedule:

• "...'adjusting' refers to adjusting an AMA impairment rating for diminished future earning capacity, occupation, and age."

• "Impairments of an individual extremity are adjusted and combined at the whole person level with other impairments of the same extremity..."

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Impairment Values

• 100% LE = 40% WPI [LE % x .4 = WPI %]

– Table 17-3 – page 527

• 100% Foot = 70% LE [Foot % x .7 = LE %]


Table 17-3 – page 527

Conversion Table – LE to WPI


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Combine or Add, and CVC

• Numbers that are put together for evaluation of impairment/ PD must be either added or combined.

• When to combine:

• COMBINE – for most situations -- unless specific instructions state to ADD impairment values. The effect/ purpose of combining is that it prevents the combined value from exceeding 100.

A + B(1 – A) [where A and B are decimal equivalents]

• When to add:

• The most notable exception to combining impairments is with the evaluation of range of motion impairment for the same part of the body (for example, right ankle motion) [hand evaluation has unique methodology]


Combine or Add, and CVC

• How to combine:

• Page 1-11 of the 2005 PDRS:

• Multiple impairments such as those involving a single part of an extremity, e.g. two impairment involving a shoulder such as shoulder instability and limited range of motion, are combined at the upper extremity level, then converted to whole person impairment and adjusted before being combined with other parts of the same extremity.

•• Impairments with disability numbers in the 16.01 and 17.01 series are converted

to whole person impairment and adjusted before being combined with any other impairment of the same extremity.

•• Impairments of an individual extremity are adjusted and combined at the whole

person [PD] level with other impairments of the same extremity before being combined with impairments of other body parts. For example, an impairment of the left knee and ankle would be combined before further combination with an impairment of the opposing leg or the back.


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13www.bradfordbarthel.com

Chapter 17

• 13 Methods of Assessment


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Methods Used to Evaluate

Impairments of the Lower Extremities


Table 17-2, page 526

“After all potentially impairing conditions have been identified and correct ratings recorded …select the…most specific…method(s) and record the estimated impairment for each.”

“explain in writing why a particular method(s)…was chosen.”(p. 526)


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Table 17-2

• “Typically, one method will adequately

characterize the impairment…”

• “Avoid combining methods that rate the

same condition.”

• “If more than one method can be used, the

method that provides the higher rating

should be adopted.” (page 527)



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Interpolation

• When a Table gives a range for objective

findings, and a correlating range for

impairment, use interpolation to provide the

appropriate value (as shown in Example 17-

15, with leg shortening)



Method #1

Limb Length Discrepancy

• X-rays strongly recommended

Repeat 3 times

3

“averaged to reduce measurement error”

P. 528

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Table 17-4 (p. 528)Impairment Due to Limb Discrepancy


Shortening due to:

• Overriding,

• Malalignment, or

• Fracture deformities

0-1.25 cm (0-1/2 in.) = 5% LE

1.25-2.5 cm (1/2-1 in.) = 10% LE

2.5-3.75 cm (1-1 ½ in.) = 15% LE

3.75-5.0 cm (1 ½ - 2 in.) = 20% LE

“combine…with other functional sequela…”

(p 528)

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Method #2

Gait Derangement

• Why is it being used?

• Should use more specific method

• Correlating objective findings

• Read Table 17-5 (p. 529) carefully

• No combining


Table 17-5, p. 529

•

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• “Except as otherwise noted…Table 17-5 [is] for

full-time gait derangements of persons who

are dependent on assistive devices.”

• Not for “abnormalities based only on

subjective factors, such as pain or sudden

giving-way, as with…an individual with low-

back discomfort who chooses to use a cane to

assist in walking.”


• “Whenever possible, the evaluator should use a more specific method. When the gait method is used, a written rationale should be included in the report. The lower limb impairment percents shown in Table 17-5 stand alone and are not combined with any other impairment evaluation method.”

• As also expressed in the Comment section for Example 17-1 on page 528 of the AMA Guides,

• “Although the individual has a limp (gait abnormality), gait derangement should be used only when no other method is available to rate the person.”

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Method #3

Muscle Atrophy (Unilateral)

• At thigh 10 cm above patella

• Calf at “max level”

• Must compare measurement to opposite,

uninjured LE

• Combine thigh and calf atrophy


Atrophy Measurements

• Compare measurement to opposite member

• Difference in circumference might be:

– Swelling

– Varicose veins

– Opposite member injured

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Table 17-6 (p. 530)Impairment Due to Unilateral

Leg Muscle Atrophy

Mild


Example

• Right tibia fracture

• MMI

• Pain free walking

• Right thigh atrophy = 2 cm

• Right calf atrophy = 1 cm

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Impairment?

Thigh =

2 cm = 8% LE = 3% WPI

Calf =

1 cm = 3% LE = 1% WPI

Combine: 8% C 3% = 11 LE

Convert: 11% LE = 4% WPI


Method #4

Manual Muscle Testing• Use Table 17-7 &17-8

(pages 531- 532)

• Note typo - Hip abduction,

Grade 3 = 37% LE

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Table 17-7 (p. 531)

Criteria for Grades of Muscle Function

of the Lower Extremity


Manual Muscle Testing (cont’d)Cautions – page 531:

“depends on the examinee’s cooperation”

“should be concordant with other…signs and medical evidence”

– More than one grade between examiners

– More than one grade from exam to exam

– Pain

– Fear of pain

– Attributed to deficit of a peripheral nerve

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Table 17-8, p. 532Combine – Example 17-5


Range of Motion

(pages 533-538)

Method #5

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• Use ROM only “If it is clear…restricted [ROM]

has an organic basis…”

• Obtain 3 measurements; use greatest

• Add ROM impairments in joint


Figure 17-1 (p. 534)Using a Goniometer to Measure Flexion of the Right Hip

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Figure 17-2 (p. 534)Neutral Position, Abduction, Adduction

of the Right Hip


Figure 17-3 (p. 535)Measuring Internal and External Hip Rotation

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Figure 17- 4 (p. 535)Measuring Knee Flexion


Figure 17-5 (p. 535)

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Range of Motion (page 537)

• Table 17-9 - Hip

• Table 17-10 - Knee

• Table 17-11 - Ankle

• Table 17-12 - Hindfoot

• Table 17-13 - Ankle/Hindfoot

• Table 17-14 - Toes (see footnote)


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Example:

Ankle flexion of 6° = ?

= 6% WPI (15% LE) (Table 17-11, p. 537)

Ankle extension of 5° = ?

= 3% WPI (7% LE) (Table 17-11)

1 cm calf atrophy?

= 1% WPI (Table 17-6, p. 530)


Impairment?

Add flexion + extension =

15% LE + 7% LE = 22% LE = 9% WPI

Do not use atrophy (1% WPI)

R: 1) Table 17-2 prohibits combining

2) ROM is more generous

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Range of Motion (continued)

Invalid if:

• Class inconsistency between 2 observers

• Class inconsistency between exams

• Pain

• Fear of pain


Method #6

Ankylosis (joint immobility)

See text for “optimal position” values

Hip = 50% LE = 20% WPI (p. 538)

Knee = 67% LE = 27% WPI (p. 540)

Ankle = 14% Foot = 10% LE = 4% WPI (p. 541)

Foot = 14% Foot = 10% LE = 4% WPI (p. 542)

Toes – see Table 17-30 (page 543)

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Ankylosis (continued)

1. Determine value for “optimal position” (text)

2. Use Tables (pages 538-543) for deviation values

(malposition increases impairment)

3. Add multiple malpositions for same joint

4. Combine ankylosis of different joints

5. “The baseline rating for ankylosis in a neutral

position is used only once for each joint.”


Body Part Motion Table Page

hip internal rot 17-16 539

hip ext rot 17-17 539

hip abd 17-18 539

hip add 17-19 539

knee varus 17-20 540

knee valgus 17-21 540

knee flex 17-22 540

knee int or ext 17-23 540

malrotation

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Body Part Motion Table Page

ankle

plantar flex or dorsiflexion

17-24 541

ankle varus 17-25 541

ankle valgus 17-26 541

ankleint malrotation

17-27 541

ankleext malrotation

17-28 541

ankletibia-os calcis angle

17-29 542

toes ankylosis 17-30 543


Method #7

Arthritis

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Arthritis (cont’d)

• Use x-rays (“standing if possible”) with Table

17-31 (page 544)

• ( ) = normal cartilage intervals

• Compare uninjured opposite member


Table 17-31, p. 544

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Arthritis (cont’d)

Table 17-31 Footnote:

if (i) direct trauma; (ii) patellofemoral pain (between knee cap and thigh bone/femur), and (iii) “crepitation” on physical exam; (iv) no joint space narrowing

- 2% WPI (5% LE)

• The knee has a medial and lateral compartment – only the more significant loss is used

(can be combined with patellofemoral arthritis)


Example

• Right tibia fracture 10 years ago

• Over years, increase knee pain, occasional

swelling

• Standing x-ray – 2 mm cartilage interval

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Impairment?

Cartilage interval (knee) = 2 mm

Table?

Table 17-31 (p. 544)

Likely amount of cartilage loss?

“normal” = 4 mm

WPI?

8% WPI (20% LE)


Method #8

Amputations

• See Table 17-32 (page 545)

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Table 17-32, p. 545


Method #9

Diagnoses-Based Estimates – Table 17-33(used in 70-80% of LE cases)

Covers 9 regions/conditions1) Pelvis

2) Hip

3) Femoral Shaft Fracture

4) Knee

5) Malalignment of Tibial Shaft Fracture

6) Ankle

7) Hindfoot

8) Midfoot Deformity

9) Forefoot Deformity

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Hip and Knee Replacements require

the use of 2 TablesHip Replacement:

Table 17-34 and 17-33 (p. 548, 546-547)

Knee Replacement:

Table 17-35 and 17-33 (p. 549, 546-547)

All others:

Table 17-33 (p. 546-547)


DRE Hip Replacement

• Add points from Categories a-e (Table 17-34,

p. 548)

– Note that the primary factor is pain

• Apply to Table 17-33 (p. 546)

(Good, Fair, Poor Results)

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Table 17-34, p. 548


Table 17-35, p. 549

•

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Total Hip and/ or Knee Replacement

• Good Results, 85-100 pts. 15(37)

• Fair Results, 50-84 pts. 20(50)

• Poor Results, less than 50 pts. 30(75)


Method #10

Skin Loss(p. 550)

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Use Table 17-36 (p. 550)

Full-thickness skin loss: impairment “even when the areas are successfully covered with [a]…skin graft.”

Chronic osteomyelitis (bone infection*) too

* Usually a bacterial infection of bone/marrow. Resulting inflammation can lead to reduction of blood supply to bone.


Table 17-36 (p. 550)

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Method #11

Peripheral Nerve Injuries(p. 550-552)

Table 17-37 - maximum impairment values

Assessed sensory/ motor deficits are applied

Combine with other LE methods except:muscle weaknessatrophygait (p. 552)


Dysesthesia

• Impairment of sensitivity, especially to touch.

Altered feelings, such as burning, wetness,

electric shock, pins and needles, itching

(p. 600)

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Table 17-37 (p. 552)


Method #12

Causalgia & CRPS(p. 553)

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CRPS I (RSD)

CRPS II (causalgia)

“characterized by pain, swelling, stiffness,

discoloration…skeletal demineralization”

“may follow a sprain, fracture or nerve or

vascular injury”


CRPS I (RSD)

CRPS II (causalgia)

Use Chapter 13 (“Central & Peripheral Nervous

System”):

Section 13.8 (p. 343-344)

Section 13.5 (p. 336)

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“to rate [causalgia and RSD]…, diagnosis is

key…”

• Diagnosis: rely on clinical findings, three-

phase bone scan, x-rays, laser Doppler

flowmetry, sudomotor reflex

• Table 16-16 (p. 496)


Table 13-15 (p. 336)

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Method #13

Vascular Disorders(p. 553-554)


Table 17-38, p. 554)

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• Intermittent claudication: cramping or aching in the calves (sometimes the thighs or buttocks) caused by walking; relieved by rest; a manifestation of atherosclerosis (blockage of an artery). It is called “intermittent” because of the pattern of pain only with walking.

• Edema: abnormal buildup of fluid in the ankles, feet and legs.

• Common causes:

– Prolonged standing

– Long airplane flights or automobile rides

– Menstrual periods (for some women)

– Pregnancy

– Being overweight

– Increased age

– Injury or trauma

Summary

• Multiple potential methods for impairment

evaluation

• Some can be combined; others cannot

• Combine impairments at the LE impairment

level before converting to WPI

• Cautions regarding the use of Gait

Derangement; Strength evaluation


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Almaraz/ Guzman

• Almaraz/ Guzman rating not automatic

• Must be substantial evidence

• Within four corners of AMA Guides

• Physician rationale required

2015 DWC Educational Conference

Evidence and reasoning


Tim Mussack

(916) 569-0790 [email protected]

Marlene Phillips

(909) [email protected]


the lower extremities ama g uides chapter … 1 the lower extremities ama g uides chapter 17 tim...

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