A CASE REPORT OF NERVE DAMAGE
AND KNEE EXTENSOR WEAKNESS AS A
RESULT OF A TKA
Robert Whittaker, SPT
University of North Dakota
Patient Presentation
• 49 y.o. female with (L) TKA in 2009 who suffered a fibular
nerve palsy as well as having the quads “shut down”
• Patient evaluated on 10/20/13 for posterior knee pain &
discharged on 12/9/13 for a total of 5 visits.
• Patient private pay & had 20 independent visits to clinic gym
• Pt. instructed on home NMES use & to use clinic’s gym to
recumbent bike, leg press/extension/curls with emphasis
on eccentric contraction for duration of rehab.
• Pt. progressed from lacking 50° of AROM (L) knee
extension to lacking ~35° with some improvement in pain.
• Referred to physician for genetic testing for nerve disease & nerve
conduction test of femoral nerve (HNPP?). Pt. stated she was
looking into getting a knee brace.
Clinical Decision Making
Patient Care
• Accept
• Familiar with TKAs and protocols, treatment appropriate for pt. to
regain strength
• Skills to improve quadriceps weakness, seen multiple TKAs in
clinicals
• Direct
• Goals, extent of condition, patients availability, handling techniques
• Indirect
• Private pay, travel in winter, can do HEP, pain, past therapy, PMH,
life
• Refer
• Refer back to MD eventually from little progress
History
• Patient is full time homemaker (military wife?)
• C/O constant (L) posterior knee pain 5/10
• Patient has to lift her leg into car and leg gives out often
• Pain and weakness in left leg cause her to ambulate with SPC
• (R) knee pain secondary to DJD and hasn’t walked well for
•
•
•
•
years
Pt. wore an AFO to ambulate after TKA but no longer wears
Also has neck & low back pain due to bulging discs
Indicated she has diabetes, thyroid trouble, arthritis, sleeping
problems, frequent headaches, & degenerative joint disease for
many years
Many imaging studies (none available)
Pain Drawing
History Cont’d
• Medications: Aspirin (81mg), Inderal (120mg), Janumet
XR-50/100xz), Lipitor (20mg), Lisinopril (40mg),
Omeprazole (20mg), Synthroid (50mcg), Topamax
(100mg), Zyrtec (10mg)
• Allergy Meds: Penicillin, Ampicillin, Bactrim, Celocin,
Feldene, Zomig
• Family history: Her father had a myocardial infarction (MI)
as well as COPD. Her mother has prediabetes. Both her
parents have high blood pressure.
Past Medical History
• Cholecystectomy (1991)
• (L) Carpal Tunnel release
(1998), (R) release (1999)
• 2008
• Cortisone Shots (March & July)
• Arthroscopy & meniscectomy
(June)
• Arthroscopy, chondroplasty, partial
meniscectomy (Dec)
• 2009
• Orthovisc and cortisone shots
(Jan-Sep)
• TKA (Oct) with fibular nerve palsey
 knee manipulation (Dec)
• PT – ionto, e-stim, strength (Nov –
May 2010)
• 2010
• EMG Nerve Study on
Fibular/Femoral Nerve (June)
• LLE Inching study fibular nerve
(Oct)
• 2011
• Fibular nerve release, knee
manipulation (may)
• More PT (14 sessions for IT band
and fibular nerve pain) (Oct)
• 2012
• More PT (12 sessions for fibular
nerve and posterior knee pain)
(Feb)
• EMG nerve study (Nov)
• 2013
• Epidural steroid injection (Jan)
Examination – Systems Review
• Initial Eval (10/20)
• Weight 190lbs, 61.5” (BMI 36)
• Discharge (12/14)
• AROM: -38° left knee ext. PROM (L)
• Mature scaring on anterior knee from
TKA, posterolateral knee from fibular
nerve release, small scars on wrists
from carpal tunnel releases
• AROM: (L) knee ext -50° sitting. (L)
ankle AROM appears to be WFL
• PROM: 110° (L) knee flexion, 0° (L)
knee.
• Strength: 4/5 (L) knee flexion, 2/5 (L)
knee extension
• 11/15
• AROM: -35° left knee ext
•
•
•
•
•
•
ankle DF 7°
Strength: Hip flexion 4/5 (B), (R) ER
3/5 (pain felt in her knee when
resisted), (L) ER 4/5, (R) IR 5/5, (L) IR
3/5 (pain felt on lateral knee), and 4/5
for (L) hip abd/add/ext. (L) ankle
eversion 3/5 (pain in lateral knee), 4/5
DF/PF/INV.
Palpation: (L) vastus lateralis, lateral
gastrocnemius head, and distal biceps
femoris were tender to palpation
RHR 60 BPM, BP 124/76, SaO2 98%.
Dermatomes L1-L3 feel same (B), L4-S2
diminished sensation to touch on (L)
compared to (R)
Reflexes: (R) L3 & S1 normal, (L) L3 &
S1 diminished
Special Test: (+) varus stress test
Trigger Points13
Rigor – Assessment8
• Varus Stress Test18
• 20-30° Flexion: LCL, posterolateral capsule, arcuate-poplitus
complex, ITB, biceps femoris tendon
• Extension: fibular or lateral collateral ligament, arcuate-popliteus
complex, biceps femoris tendon, PCL, ACL, lateral gastrocnemius
muscle, ITB
• Article: investigated reliability of multiple knee clinical
tests in CE, EUA, and by comparing to arthroscopic
techniques
• 6 (+) in CE, 10 (+) EUA (p=0.0277, Wilcoxon)
• Limited to collateral ligament tear: 4 subjects, 1 instability found in
CE and 3 EUA
• Sensitivity = 25%, Specificity not reported
ICF Model
ICF Model Cont’d
• Health Condition
• (L) Dysfunctional Quadriceps, (L) fibular nerve dysfunction, (R) knee DJD
• Body Structures/Function (impairments)
• ROM: (L) knee ext -50° sitting. PROM: 110° (L) knee flexion, 0° (L) knee. (L)
ankle AROM appears to be WFL. *(L) ankle DF PROM 7°
• Strength: 4/5 (L) knee flexion, 2/5 (L) knee extension. *Hip flexion 4/5 (B), (R)
ER 3/5 (pain felt in her knee when resisted), (L) ER 4/5, (R) IR 5/5, (L) IR 3/5
(pain felt on lateral knee), and 4/5 for (L) hip abd/add/ext. (L) ankle eversion
3/5 (pain in lateral knee), 4/5 DF/PF/INV.
• *Dermatomes L1-L3 feel same (B), but L4-S2 diminished sensation to touch on
(L) compared to right
• *Reflexes: (R) L3 & S1 normal, (L) L3 & S1 diminished
• Posterior (R) knee pain (5/10)
• *Vastus lateralis, lateral gastrocnemius head, and distal biceps femoris were
tender to palpation – guarding/trigger points?
• *Laxity in lateral knee
• Excessive BMI
• Scars
ICF Model Cont’d
• Activities
• Ambulates independently with SPC
• Can transfer into/out of car with difficulty
• Participation
• No mention of being able to not participate in what she desires
• If health condition not addressed may possibly lead to further
deterioration in QOL  need for assistive equipment, TKA
revision/other knee, amputation from diabetes?
• Contextual
• Personal Factors (internal)
• motivated to get better, pessimistic, pain in other knee/neck/back
• Environmental Factor (external)
• Husband/family?, home, weather
Evaluation
• Initial Evaluation
• The patient presents with (L) knee weakness with decreased
PROM/AROM with increased pain with motion. The patient’s
functional mobility is decreased and will be instructed on a gym
program and how to operate a home NMES unit to improve
quadriceps activation and knee functionality.
• Reevaluation
• The patient has not gained quadriceps strength like expected.
Patient has laxity with varus stress test and is being referred back
to MD.
Diagnosis5
• Pattern 5F: impaired peripheral nerve integrity and muscle
performance associate with peripheral nerve injury
• She was diagnosed with left weakness and dysfunctions
S/P a left TKA with DJD in her right knee.
• ICD-9-CM Codes
• 728.87 - muscle weakness-general
• 719.4 - joint pain-lower leg
Prognosis & POC
• STG
• To be independent with HEP
• To have EMG/NCV results by next visit
• LTG
• Independent with gym exercise program in 4 weeks
• To improve knee extension to be -20° in 4-6 weeks
• Patient Goals
• Walk without use of assistive device
• Be completely pain free
• POC
• Patient will be seen once/week for 6 weeks and be independent in a
gym exercise program ASAP due to being Private Pay
• Prognosis5
• Patient will demonstrate optimal peripheral nerve integrity and muscle
performance over the course of 4-8 months
• Expected range of visits 12-56
Rigor – Intervention14
• Article: Review of 4 recent RCTs since 2009
• Initiation: 2 days post-op, sooner the better!
• Volume: 30 minutes to 4 hours per day
• Intensity: The higher the better, methods to make pt. comfortable!
• Adjust to supervised PT: combined modalities may possibly
increase improvements
• Home unit available to decrease costs of PT
• Home exercises and free gym access while a patient.
Patient Education
• Content: Demonstrated, 1 on 1, pamphlet (NMES), flow sheet,
written instructions
• Pt. instructed on NMES by demonstrating to pt. how to set it
up, having the pt. repeat it, and providing written instructions &
the pamphlet. Pt’s. concerned addressed at additional visits.
• Pt. instructed on setting up recumbent bike & using clinic’s
equipment with appropriate settings with demonstration &
return demo (pt. able to ask available PT if confusion arises)
• Pt. needed additional help 1 time with knee flexion machine.
• General anatomy/physiology of condition
• POC and to maintain the lowest cost
• Barriers
• Pt. wears glasses
• Somewhat quiet (pessimistic?)
Patient Education
• Learning type: did not address patients type (maybe reflective
observation?)
• SPT learning style: Accommodator
• Cognitive Domain (facts) – recall exercise prescription from
flow sheet, where to place electrodes (parameters on HEP),
setting up equipment, comparing past PT, establish why
exercises were prescribed, plan
• Affective (attitude) – listening to instruction,
participating/informed consent, going through HEP
independently, resolve confusing equipment
• Psychomotor (skills) – observing our demonstration, return
demonstrating, practice HEP independently after learning and
perfecting it
• Documentation: use of NMES on location setting and duration
and time/day, exercises with times on pt. flow sheet
• No weight/duration in computer documentation for resistance
Strengths & Limitations to Pt. Education
• Strengths: available to help if confused with equipment,
provided instructions to HEP with demo/return demo
• Weaknesses: Small hand writing (make more legible!),
was all of pt’s. concerns addressed?, no written
instructions for D/C?
Evaluating Clinical Change
• Goals
• STG: Pt. to be independent with HEP at next visit (C, EF)
• Following PT intervention, the pt. will be independent with a HEP and
familiar with clinic gym equipment as pt. is private pay and would like to
minimize cost.
• LTG: To improve (R) knee extension AROM to -20° in 4-6 weeks (A,
C, EF)
• Following PT intervention, the pt. will improve (R) knee extension AROM
in sitting to -20° to be able to transfer into a car more efficiently.
• Functional Assessment
• Not performed but would have wanted to use The Knee Outcome
Survey Activities of Daily Living
• Estimated evaluation score – 27/70 = 38.6%
• Estimated discharge score – 28/70 = 40%
Knee Outcome Survey ADLs1
• 2 Parts to Questionnaire – 14 total questions (also 11
question sport questionnaire)
• Symptoms (6 Questions) – Pain, stiffness, swelling, giving
way/buckling/shifting of knee, weakness, limping
• No symptoms (5), symptoms but: does not effect activity (4), slightly
affects (3), moderately affects (2), severely effects (1), unable (0)
• Function – walk, ascending stairs, descending stairs, stand, kneel
on front of your knee, squat, sit with knee bent, rise from chair
• Activity not difficult (5), minimally difficult (4), somewhat difficult (3), fairly
difficult (2), very difficult (1), unable to do (0)
• 𝑇𝑒𝑠𝑡 𝑆𝑐𝑜𝑟𝑒 =
𝑖𝑡𝑒𝑚 𝑠𝑐𝑜𝑟𝑒𝑠
70
∗ 100
Knee Outcome Survey ADLs10
• Low SEM (but not the lowest)
• 73% of subjects score above MDC
• Large ES and ESSEM (4-5x SEM – indicative of sensitivity)
• Smaller ceiling effect compared to other functional
assessments
• Missing data? – bad translation
Instrument
OKS
WOMAC pain
WOMAC stiffness
WOMAC function
KOS symptoms
KOS function
KOS total
SF-12 PC
SF-12 MC
Pre Test (SD)
32.5 (7.1)
43.5 (20.5)
47.4 (23.4)
39.8 (21.4)
17.7 (6.1)
20 (6.7)
53.5 (15.2)
32.7 (7.9)
55.2 (10.7)
Post Test (SD)
26.1 (9.3)
20.4 (18.7)
23.5 (21.7)
20.2 (18.7)
23.4 (5.1)
28.5 (7)
74 (15.9)
42.1 (9.4)
53.1 (9.3)
SEM (%mean)
2.2 (7.2)
6.8 (15.2
9.8 (28.3)
4.8 (18.5)
1.9 (19)
1.9 (18.9)
4.1 (8.6)
3.5 (10.5)
2.9 (6.6)
MDC (%>MDC*)
6.1 (60)
18.8 (61)
27.1 (51)
13.3 (61)
5.3 (60)
5.3 (51)
11.4 (73)
9.7 (55)
8.0 (56)
ICC
0.91
0.91
0.84
0.96
0.86
0.93
0.93
0.81
0.9
Values
Patient Values
• Motivation/determinati
on
• Done right quick
• Hesitant
• Open to new
experiences, revisiting
old ones
• Punctual
• Social support
• Cost
Personal
• Ambitious
• Thorough/complete all
tasks
• Reliable/pleasing
everyone
• Living up to
expectations
• Respect honest
• Fair
• Slowing down
• Humor
• Understanding
Quickly
• Black & white
PT – Professional
• Goal oriented
• Efficient
• Equal tx/professional
behavior
• Being right or
confident (knowing
all)
• Teachable
• Organized
• Responsible
• Passion
• Full effort
• Flexibility
• Realistic
Little treatment time as possible
Johari Window
Arena
•
•
Blind Spot
Has general idea of diagnosis, both •
familiar with functional limitations
Exercise program & parameters 
written instructions
•
PT knows much more on anatomy
of knee, differential dx, expected
prognosis, how modalities/exercise
affects
Share the knowledge!
Façade
Unknown
•
•
•
•
Pt. may not be sharing all possible
information as there is so much
history, pt. may assume we ask all
that is required
Home life, kids, environment?
Ask all appropriate history
questions!
•
What is truly going on and what
potential is there for rehabilitation
Refer to another specialist who can
shed light on situation
Force Field Analysis – Improved ROM
• Driving Forces
• Motivated to be normal
• Doesn’t want to use SPC
• Free gym use
• Not a busy schedule/free
time?
• Improve function for
family?
• Therapy
instructions/help
• Restraining Forces
• Weakness
• Pain
• $$$
• Weather (winter)
• Slow progress  Doubt
• Comorbidities (diabetes,
back/neck pain bulge)
• Anatomical/Physiological
knowledge
LTG: To improve (R) knee extension AROM to -20° in 4-6 weeks – not met
Ethical Issues
• Private pay – distress
• Solutions – expensive vs. least expensive
• Least expensive as pt. does not have the financial resources for
extensive PT
• Pain through exercise – issue
• Solutions – modalities vs. informed consent vs. referral
• Informed consent as pt. would have to pay additional for modalities,
eventual referral
• Code of ethics 1, 2, 3, 5, 6
• Respect, trustworthy, accountable for judgment, legal/professional
obligation, enhance expertise
• RIPS
Evidence Based Practice20
• Functional exercises/outpatient rehabilitation better
results compared to traditional/home therapy
• Benefits did not persist to 12 months
• Short term rehabilitation focusing on functional exercises!
Meta-Analysis
3-4 mo (95%CI)
12 mo (95%CI)
Function (ES)
0.33 (0.7 – 0.58)
-0.07 (-0.28 – 0.14)
Walking (ES)
0.27 (-0.13 – 0.67)
0.03 (-0.24 – 0.31)
ROM (WM)
2.9° (0.61° – 5.2°)
0.96° (-1.1° – 3°)
QoL (ES/WM)
1.7 (-1 – 4.3)
0.03 (-0.2 – 0.25)
Strength
N/A
N/A
Cost/benefit analysis
• Patient Private Pay Out of Pocket
• PTC charges $25/unit (code 00050)
• Gym free to use during business hours
for current patients - $20/mo 1 month
after D/C
• Potential Costs?
• Commuting
• TKA revision/other knee?
• Conduction/genetic testing
• MD visits
• Role in society – pt. homemaker
and has been living with this
condition, overall unchanged
• Fair service – I believe I would
have been satisfied as I’ve seen 2
units cost ~$100 instead
Date
Cost
10/22/13
$50
10/25/13
$50
11/1/13
$50
11/15/13
$50
12/4/13
$50
Total
$250
Outcome
• So far the patient has gained about 15° of knee extension since
•
•
•
•
•
initial visit and feels she has improved since starting.
She has been discharged for now until she gets further testing
done on her femoral nerve function to see if she has potential
for more rehabilitation.
She mentioned she is talking with her physician about doing
just a bicompartmental partial knee replacement in her right
knee to help with pain, but is very hesitant in doing so after her
current TKA dysfunction.
Patient working with MD to get genetic testing for HNPP
May return to therapy if potential for further gains
Looking into brace to provide knee stability preventing joint
stress
Reflection
• Examination
• Did a full evaluation right away
• Provided functional assessment to evaluate how the patient
perceives change
• Mapped out dermatones – diabetic education?
• Gathered postop reports
• Biofeedback?
• POC
• Provided more functional exercises & adjust NMES volume
• Use pain modalities – Pro bono?
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