THE LOWER EXTREMITIES AMA GUIDES CHAPTER 17

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1 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) Marlene Phillips (909)

2 3 Most Frequently Used Chapters Chapters 1 & 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 Spine Chapter Upper Extremity (UE) Chapter Lower Extremity (LE) 4 2

3 The Lower Extremities Lower extremity impairment values Combining Impairment PD (after adjustment) Methods of Evaluation 5 Chapter 17 The Lower Extremities there are errata 17.1 Principles of Assessment (p ) 17.2 Methods of Assessment (p ) 17.3 LE Impairment Evaluation Procedure Summary and Examples (p ) Impairment evaluations are performed after the injured worker attains MMI 6 3

4 7 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..." 8 4

5 Impairment Values 100% LE = 40% WPI [LE % x.4 = WPI %] Table 17-3 page % Foot = 70% LE [Foot % x.7 = LE %] 9 Table 17-3 page 527 Conversion Table LE to WPI

6 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] 11 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 and 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

7 13 Chapter Methods of Assessment

8 Methods Used to Evaluate Impairments of the Lower Extremities 15 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)

9 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)

10 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) 19 Method #1 Limb Length Discrepancy X-rays strongly recommended Repeat 3 times 3 averaged to reduce measurement error P

11 Table 17-4 (p. 528) Impairment Due to Limb Discrepancy 21 Shortening due to: Overriding, Malalignment, or Fracture deformities cm (0-1/2 in.) = 5% LE cm (1/2-1 in.) = 10% LE cm (1-1 ½ in.) = 15% LE cm (1 ½ - 2 in.) = 20% LE combine with other functional sequela (p 528)

12 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 23 Table 17-5, p

13 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 lowback 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

14 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 27 Atrophy Measurements Compare measurement to opposite member Difference in circumference might be: Swelling Varicose veins Opposite member injured

15 Table 17-6 (p. 530) Impairment Due to Unilateral Leg Muscle Atrophy Mild 29 Example Right tibia fracture MMI Pain free walking Right thigh atrophy = 2 cm Right calf atrophy = 1 cm

16 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 31 Method #4 Manual Muscle Testing Use Table 17-7 &17-8 (pages ) Note typo - Hip abduction, Grade 3 = 37% LE

17 Table 17-7 (p. 531) Criteria for Grades of Muscle Function of the Lower Extremity 33 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

18 Table 17-8, p. 532 Combine Example Method #5 Range of Motion (pages )

19 Use ROM only If it is clear restricted [ROM] has an organic basis Obtain 3 measurements; use greatest Add ROM impairments in joint 37 Figure 17-1 (p. 534) Using a Goniometer to Measure Flexion of the Right Hip

20 Figure 17-2 (p. 534) Neutral Position, Abduction, Adduction of the Right Hip 39 Figure 17-3 (p. 535) Measuring Internal and External Hip Rotation

21 Figure 17-4 (p. 535) Measuring Knee Flexion 41 Figure 17-5 (p. 535)

22 Range of Motion (page 537) Table Hip Table Knee Table Ankle Table Hindfoot Table Ankle/Hindfoot Table Toes (see footnote)

23 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) 45 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

24 Range of Motion (continued) Invalid if: Class inconsistency between 2 observers Class inconsistency between exams Pain Fear of pain 47 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 (page 543)

25 Ankylosis (continued) 1. Determine value for optimal position (text) 2. Use Tables (pages ) 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 hip ext rot hip abd hip add knee varus knee valgus knee flex knee int or ext malrotation

26 Body Part Motion Table Page ankle plantar flex or dorsiflexion ankle varus ankle valgus ankle ankle int malrotation ext malrotation ankle tibia-os calcis angle toes ankylosis Method #7 Arthritis

27 Arthritis (cont d) Use x-rays ( standing if possible ) with Table (page 544) ( ) = normal cartilage intervals Compare uninjured opposite member 53 Table 17-31, p

28 Arthritis (cont d) Table 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) 55 Example Right tibia fracture 10 years ago Over years, increase knee pain, occasional swelling Standing x-ray 2 mm cartilage interval

29 Impairment? Cartilage interval (knee) = 2 mm Table? Table (p. 544) Likely amount of cartilage loss? normal = 4 mm WPI? 8% WPI (20% LE) 57 Method #8 Amputations See Table (page 545)

30 Table 17-32, p Method #9 Diagnoses-Based Estimates Table (used in 70-80% of LE cases) Covers 9 regions/conditions 1) 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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32 Hip and Knee Replacements require the use of 2 Tables Hip Replacement: Table and (p. 548, ) Knee Replacement: Table and (p. 549, ) All others: Table (p ) 63 DRE Hip Replacement Add points from Categories a-e (Table 17-34, p. 548) Note that the primary factor is pain Apply to Table (p. 546) (Good, Fair, Poor Results)

33 Table 17-34, p Table 17-35, p

34 Total Hip and/ or Knee Replacement Good Results, pts. 15(37) Fair Results, pts. 20(50) Poor Results, less than 50 pts. 30(75) 67 Method #10 Skin Loss (p. 550)

35 Use Table (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 (p. 550)

36 Method #11 Peripheral Nerve Injuries (p ) Table maximum impairment values Assessed sensory/ motor deficits are applied Combine with other LE methods except: muscle weakness atrophy gait (p. 552) 71 Dysesthesia Impairment of sensitivity, especially to touch. Altered feelings, such as burning, wetness, electric shock, pins and needles, itching (p. 600)

37 Table (p. 552) 73 Method #12 Causalgia & CRPS (p. 553)

38 CRPS I (RSD) CRPS II (causalgia) characterized by pain, swelling, stiffness, discoloration skeletal demineralization may follow a sprain, fracture or nerve or vascular injury 75 CRPS I (RSD) CRPS II (causalgia) Use Chapter 13 ( Central & Peripheral Nervous System ): Section 13.8 (p ) Section 13.5 (p. 336)

39 to rate [causalgia and RSD], diagnosis is key Diagnosis: rely on clinical findings, threephase bone scan, x-rays, laser Doppler flowmetry, sudomotor reflex Table (p. 496) 77 Table (p. 336)

40 Method #13 Vascular Disorders (p ) 79 Table 17-38, p. 554)

41 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 81 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

42 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 83 Tim Mussack (916) Marlene Phillips (909)