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KNEE MICROFRACTURE
CLINICAL PRACTICE GUIDELINE
Disclaimer
The following rehabilitation guidelines are specific to patients who have undergone a knee
microfracture surgical procedure. Please refer to the Ohio States Sports Medicine website for
rehabilitation guidelines specific to other procedures and conditions, as appropriate.
Progression is criterion-based and dependent on soft tissue healing, patient demographics, and clinical
evaluation. The time frames identified for each phase of rehabilitation are approximate times for the
average patient and not recommended as guidelines for progression for the individual patient. It is
recommended that progression is based upon the achievement of functional criteria demonstrating
readiness for progression, noted at the end of each phase.
Background
Knee microfracture surgery is an arthroscopic surgical procedure to restore full thickness cartilage
defects of the knee. During the procedure, multiple small holes, or “microfractures”, are made in the
bone exposed by the cartilage defect. This releases stem cells which form a fibrous clot that covers the
area of exposed bone. As this area matures and heals, it will turn into a smooth and durable repair
tissue. The goal during the healing process is to avoid harmful forces to the site of cartilage repair.
Improving tissue mechanical properties and protection of the tissue is done through early and controlled
weight bearing, early and protected range of motion, and gradually progressing forces during different
phases of rehabilitation.
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Summary of Recommendations
General
• It is important to be aware of lesion size and location
•
Please refer to the “post-op plan” section of the operative note for clarification
on post-operative precautions
Weight
Bearing
Guidelines
Weight bearing status is largely dependent on lesion size. Please refer to operative note for post-
operative weight bearing precautions.
Range of
Motion
Progression
• Symmetrical knee extension should be achieved by post-op week 4
• Full ROM should be achieved by post-op week 8
Outcome
Tools
Collect the LEFS at each visit
You may choose to include IKDC, KOOS, ACL-RSI, Tegner or other questionnaires specific to
your patient’s needs.
Strength
Testing
• Isometric testing: 12 weeks
• Isokinetic testing: 4, 6, 9 and 12 months
• Functional hop testing: once 80% LSI is achieved on isokinetic testing
Criteria to
Discharge
Assistive
Device
1. ROM: Full active knee extension; no pain on passive overpressure
2. Strength: Able to perform strong quad isometric with full tetany and superior patellar glide
and able to perform 20 SLR without quad lag
3. Effusion: 1+ or less is preferred (2+ acceptable if all other criteria are met)
4. Weight Bearing: Demonstrates pain-free ambulation without visible gait deviation
Criteria to
Discharge
NMES
<20% quadriceps deficit on isometric or isokinetic testing (can use HHD for isometric testing)
OR- If testing equipment is not available:
1. 20 SLR without quad lag
2. Normal gait
3. 10 heel taps to 60 degrees with good quality
4. 10 rep max on LP and similar effort bilaterally
5. Inability to break quad MMT
Criteria to
Initiate
Running
and
Jumping
1. ROM: full, pain-free knee ROM, symmetrical with the uninvolved limb
2. Strength: Isokinetic testing 80% or greater for hamstring and quad at 60º/sec and 300º/sec
3. Effusion: 1+ or less
4. Weight Bearing: normalized gait and jogging mechanics
5. Neuromuscular Control: Pain-free hopping in place without dynamic knee valgus
Criteria for
Return to
Sport
1. ROM: full, pain-free knee ROM, symmetrical with the uninvolved limb
2. Strength: Isokinetic testing 90% or greater for hamstring and quad at 60º/sec and 300º/sec
3. Effusion: No reactive effusion ≥ 1+ with sport-specific activity
4. Weight Bearing: normalized gait and jogging mechanics
5. Neuromuscular control: appropriate mechanics and force attenuation strategies with high
level agility, plyometrics, and high impact movements
6. Functional Hop Testing: LSI 90% or greater for all tests
7. Physician Clearance
Return to
Sport
Expectation
6-12 months
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RED/YELLOW FLAGS
Red Flags
Require
immediate
referral for re-
evaluation
• Signs of DVT Refer directly to ED
o Localized tenderness along the distribution of deep venous system
o Entire LE swelling
o Calf swelling >3cm compared to asymptomatic limb
o Pitting edema
o Collateral superficial veins
• Lack of full knee extension by 4 weeks post-opRefer to surgeon for re-evaluation
• Mechanical block or clunkRefer to surgeon for re-evaluation
• Reported episode of instabilityRefer to surgeon for re-evaluation
Yellow Flags
Require
modifications to
plan of care
• Persistent reactive effusion or pain following therapy or ADLs
o Decrease intensity of rehab interventions, continue effusion management,
educate patient regarding activity modifications until symptoms resolve
Early Post-Operative Phase (0 – 6 weeks)
Appointments Post-operative evaluation should be performed 3-5 days following surgery. Follow-up PT
appointments 1-2x per week, depending on progression towards goals.
Pain and
Effusion
Goal is ≤ 2+ (using Modified Stroke Test)
Cryotherapy and compression
ROM Extension: Emphasis on achieving full knee extension immediately following surgery. If full
extension is not achieved by 4 weeks, contact surgeon regarding ROM concerns.
Flexion: Progressive flexion ROM, with full flexion achieved by post-op week 8
Please refer to the “post-op plan” section of the operative note for
clarification on post-operative precautions
Weight
Bearing
Refer to operative note for precautions
Suggested
Interventions
• Extension PROM: bag hangs (Appendix A) or prone hangs
• Flexion: wall slides, heel slides, upright bike
• Patellar mobilization: superior, inferior, medial, lateral
• Quad Isometrics
• SLR 4-way
• Prone TKE
• Open Chain Knee Extension:
o Unresisted LAQ: week 4-6
o Modified range SL knee extension machine: week 6-8
• Open chain hamstring : prone hamstring curls, hamstring curl machine
• Shuttle press
o Partial range: week 4
o Full range: week 6
• SL balance (pending WBing status)
• Heel raises (pending WBing status)
• Begin Neuromuscular re-education using electrical stimulation (NMES) - see below for set
up and parameters
•
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NMES
Parameters at
60º
Appendix B
• NMES pads are placed on the proximal and distal quadriceps
● Patient: Seated in long sitting (knees extended) until able to achieve 90° knee flexion.
Progress to seated at 60° knee flexion once they are able to easily obtain 90°
• The patient is instructed to relax while the e-stim generates at least 50% of their max
volitional contraction against a fixed resistance OR maximal tolerable amperage without
knee joint pain
• 10 seconds on/ 50 seconds off x 15 min
Blood Flow
Restriction
training
Appendix D
• Blood Flow Restriction (BFR) training can be initiated as soon as sutures are removed
• Ensure patient has no contraindications (Appendix F) and if patient has any listed
precautions or are at risk for a DVT, clear with physician before initiating BFR
• Use BFR twice weekly for up to 10 weeks; use for 2-5 exercises per session
• Can be used with any exercise that is safe for patient to perform depending on time since
surgery (ex. SLR 4-way, prone TKE). BFR should never be performed during a plyometric
exercise.
• Training Load: 20-40% 1 RM (Estimated, or use OMNI-RES, see Appendix F)
• Limb Occlusion Pressure= 80% (see Appendix F if patient unable to tolerate)
• 4 sets for each exercise with reps of 30-15-15-15 (75 total) with a 30 second rest break
between sets, keeping cuff inflated the entire duration of each exercise. Deflate between
exercises, or every 8 minutes.
Criteria to
Progress to
Middle Phase
of Rehab
ROM: Symmetrical knee extension and flexion > 125°. If full AROM knee extension is not
achieved by 4 weeks, contact surgeon regarding ROM concerns.
Strength: Quadriceps set with normal superior patellar translation, 20x SLR without extensor
lag
Effusion: 1+ or less with Modified stroke test – Appendix C
Middle Phase of Rehabilitation (6-16 weeks)
Appointments Goal to increase lower extremity strength and regain flexion ROM. 1-2 visits per week with
emphasis on patient compliance with resistance and ROM training as part of HEP
Weight
Bearing
• Refer to operative note for WBing precautions.
• Goal: all patients should be FWBing without assistive device by 8 weeks, unless otherwise
outlined in operative note
Criteria to
Discharge
Assistive
Device
• ROM: Full active knee extension; no pain on passive overpressure
• Strength: Able to perform strong quad isometric with full tetany and superior patellar glide
and able to perform 20 SLR without quad lag
• Effusion: 1+ or less is preferred (2+ acceptable if all other criteria are met)
• Weight Bearing: Demonstrates pain-free ambulation without visible gait deviation
Pain and
Effusion
Cryotherapy/compression as needed for effusion – effusion should be 1+ or less
ROM Symmetrical ROM by week 8
Suggested
Interventions
and timelines
• Multi-angle knee isometrics
• Progress gluteal and lumbopelvic strength and stability
• Progress single leg balance and proprioceptive exercises
• Open chain knee extension:
o Modified range SL knee extension machine: week 6-8
o
Full range SL knee extension machine: week 8
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• Leg press machine: week 8
• Single leg dead lifts
• Squats:
o
0-45°: week 6
o
0-90°: week 8
• Heel taps: week 6
• Step ups: week 6
• Lunges: week 10
• Elliptical: week 10
• Early exercises: heel taps, step ups, squats: 0-45 degrees, open chain knee extension
with modified range SL knee extension machine
• Late exercises (8-10 weeks): leg press machine, full range SL knee extension machine,
squats 0-90 degrees; lunges and elliptical (week 10)
• NMES: progress to seated with 60
°
of knee flexion (Appendix B)
• Continue effusion management strategies
• BFR (continue as in early phase, adding appropriate exercises)
Strength
Testing
Isometric testing: 12 weeks
Isokinetic testing: 16 weeks
Criteria to
Discharge
NMES
• <20% quadriceps deficit on isometric testing (can use HHD for isometric testing)
OR- If testing equipment is not available:
1. 20 SLR without quad lag
2. Normal gait
3. 10 heel taps to 60 degrees with good quality
4. 10 rep max on leg press and similar effort bilaterally
5. Inability to break quad MMT
Criteria to
Progress to
Late Phase of
Rehab
1. ROM: Maintain full, pain-free AROM including patellofemoral mobility
2. Effusion: 1+ or less with Modified Stroke Test and no reactive effusion with progressions
3. Strength: Isometric quadriceps and hamstrings strength >/= 80%
4. Weight Bearing: Able to tolerate therapeutic exercise program, including PWB plyometrics,
without increased pain or >1+ effusion
5. Neuromuscular Control: Demonstrates proper lower extremity mechanics with all
therapeutic exercises (bilaterally)
Late Phase of Rehabilitation (weeks 16 - RTS)
Appointments Increased frequency from previous stage to 1-2x per week when appropriate to initiate
plyometric training and return to running program.
Criteria to
initiate
Running and
Jumping
1. ROM: full, pain-free knee ROM, symmetrical with the uninvolved limb
2. Strength: Isokinetic testing 80% or greater for hamstring and quad at 60º/sec and 300º/sec
3. Effusion: 1+ or less
4. Weight Bearing: normalized gait and jogging mechanics
5. Neuromuscular Control: Pain-free hopping in place
Pain and
Effusion
Effusion may increase with increased activity, ensure ≤1+ and/or non-reactive effusion for
progression of plyometrics
ROM Full, symmetrical to contralateral limb, and pain-free with overpressure
Strength
Testing
• Isokinetic testing: 4, 6, 9 and 12 months
• Hop testing (Appropriate after 80% symmetry achieved on isokinetic testing)
o SL hop for distance
o Triple hop
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o Cross over hop
o Timed 6m hop
*Functional strength testing and hop testing should be reserved for patients returning to high
level activity*
•
Suggested
Interventions
• Performance of the quadriceps, hamstrings and trunk dynamic stability
• Initiate walk-jog program once 80% LSI is achieved on isokinetic testing
• Muscle power generation and absorption via plyometrics
• Sport- and position-specific activities
Therapeutic Exercise/Neuromuscular Re-education
• Squats, leg extension, leg curl, leg press, deadlifts, lunges (multi-direction), rotational
trunk exercises on static and dynamic surfaces, resisted side steps, monster walks
• Single-leg squats on BOSU, Single-leg BOSU balance with manual perturbation to trunk
or ball, single-leg BOSU Romanian deadlift
Agility – begin at 50-75% effort initially
• Side shuffling, carioca, figure 8, zig-zags, resisted jogging (Sport Cord) in straight
planes, backpedaling, ladder drills
Plyometrics
• PWB to FWB jumping, DL to SL, progressing by altering surfaces, external and internal
perturbations
• Single-leg hop downs from increasing height (up to 12” box), Single-leg hop-holds,
Double and single-leg hopping onto unstable surface, Double and single-leg jump-turns,
Repeated tuck jumps
Criteria for
Return to
Sport
1. ROM: full, pain free knee ROM, symmetrical with the uninvolved limb
2. Strength: Isokinetic testing 90% or greater for hamstring and quad at 60º/sec and 300º/sec
3. Effusion: No reactive effusion and ≤ 1+ with sport-specific activity
4. Weight Bearing: normalized gait and jogging mechanics
5. Neuromuscular control: appropriate mechanics and force attenuation strategies with high
level agility, plyometrics, and high impact movements
6. Functional Hop Testing: LSI 90% or greater for all tests
7. Physician Clearance
Activities that generate high compression, shear and rotational loads are to be avoided until 4-6
months, or as directed by orthopaedic surgeon
Full RTS expected between 6-12 months postoperatively depending on location and size of lesion
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Appendix A: Bag Hang
Emphasis on low load, long duration stretching
o Goal: 60 minutes of bag hang time total per day.
o Ideally: 4x15 minutes (or greater) per day
Appendix B: NMES Set Up
2 or 4 pad set-up is appropriate
o NMES pads are placed on the proximal and distal quadriceps
o Patient: Seated with the knee in at least 60º flexion, shank secured with strap and back support with
thigh strap preferred. The ankle pad/belt should be two finger widths superior to the lateral malleoli
o The patient is instructed to relax while the e-stim generates at least 50% of their max volitional
contraction against a fixed resistance OR maximal tolerable amperage without knee joint pain
o 10-20 seconds on/ 50 seconds off x 15 min
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Appendix C: Stoke Test / Swelling Assessment
The Stroke Test
The stroke test is a great way to assess your swelling independently. The results of this assessment will help you
decide what exercises are appropriate.
Grading System
(Table adapted from Sturgill L et al, Journal of Orthopaedic & Sports Physical Therapy, 2009)
Grade
Zero
Trace
1+
2+
3+
Indications for Activity
3+ or 2+
1+
Trace or Zero
Red Light Yellow Light Green Light
•
No running, jumping or cutting
or heavy lifting until swelling
decreases to 1+ or less
•
Do not progress program until
you speak with your therapist
•
Utilize swelling management
strategies (ice, compression,
elevation, NSAIDs)
•
Proceed with caution
•
You may participate in running,
jumping and normal lifting
routine.
•
Check effusion before and after
workouts
•
Utilize swelling management
strategies (ice, compression,
elevation, NSAIDs)
•
May participate in running,
jumping and normal lifting
routine without restriction
•
Continue to monitor swelling
after activity
A. Using one hand, gently sweep the inside
portion of your knee 2-3 times (pushing
toward the hip joint).
B. On the outside portion of the knee,
immediately sweep downward (toward
the ankle). Watch the inside portion of
the knee (indicated by hashed circle in
photo) for a wave of fluid to appear
during the downstroke.
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Appendix D: Blood Flow Restriction Training
Precautions (must get permission from MD)
Contraindications
Patients with poor circulatory systems
(Indicators: shining or scaly skin, brittle
dry nails, extremity hair loss, increased
capillary filling time, and presence of
varicose veins)
Patients who are obese or with limb
tissue that is loose
Arterial claudification
Abnormal clotting times
Diabetes
Sickle cell trait
Tumor
General infection
Hypertension
Cardiopulmonary conditions
Renal compromise
Clinically significant acid-base
imbalance
Atherosclerotic vessels
Taking anti-hypertensive medications
Venous thromboembolism
Impaired circulation or peripheral vascular
compromise
Previous revascularization of the extremity
Extremities with dialysis access
Acidosis
Sickle cell anemia
Extremity infection
Tumor distal to the tourniquet
Medications/supplements known to ↑ clotting risk
Open fracture
Increased intracranial pressure
Open soft tissue injuries
Post-traumatic hand reconstructions
Severe crushing injuries
Severe hypertension
Elbow surgery with excessive swelling
Skin grafts in which all bleeding points distinguished
Secondary or delayed procedures after immobilization
Vascular grafting lymphectomies
Cancer
Training Intensity: 20-40% 1RM or use the Omnibus Resistance Exercise Scale (below). Patient chooses
weight/resistance that corresponds to 2-3
Exercise Prescription:
If Patient achieves:
75 repetitions: continue with training, re-assess intensity within 1-3 sessions and change as
strength improves
60-74 repetitions: continue with training, but extend rest period between sets 3 and 4 to 45
seconds until 75 repetitions is completed
45-59 repetitions: continue with training, but extend rest period between all sets to 45-60 seconds
<44 repetitions: reduce load by approximately 10% until repetitions are achieved
If patient is forced to stop before 75 repetitions due to undue pain, soreness, or general
uncomfortable feeling underneath the cuff reduce tourniquet pressure by 10mmHg at each
training session until cuff tolerance is achieved. Ramp cuff pressure back up by 10 mmHg to target
limb occlusion pressure if patient can tolerate.
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Appendix E: Isokinetic Data Interpretation
Definition
Clinical Impact
What to do
A
Peak Torque (ft-
lbs)
Peak torque during
repetitions
Symmetry criteria (see
‘E’- this is the data
represented in pie
charts)
If <80%; continue
unilateral, high
resistance strength
training
B
Coefficient of
Variance (%)
Between repetition
variability
Goal: < 15%
If >15%, consider retest
C
Total Work (ft-lbs)
Torque over all
repetitions
Possible indicator of
fatigue
If >10%; consider high
volume training
D
Agonist/Antagonist
Ratio (%)
Hamstring/Quadriceps
Ratio
Goal: >60%
<60%; ensure 1:1
quadriceps:hamstring
exercise ratio
E
Limb Symmetry Pie
Charts
Strength relative to
involved limb
Goal: <10%
asymmetry (either
direction- deficit OR
stronger on involved
limb)
If <80%, continue
NMES in addition to
strength training
If <90%, continue
unilateral > bilateral
strength training
emphasis
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Appendix F: Isokinetic Testing and Appropriate Alternatives
Sinacore, J. A., Evans, A. M., Lynch, B. N., Joreitz, R. E., Irrgang, J. J., & Lynch, A. D. (2017). Diagnostic
accuracy of handheld dynamometry and 1-repetition-maximum tests for identifying meaningful quadriceps
strength asymmetries. Journal of orthopaedic & sports physical therapy, 47(2), 97-107.
Isokinetic
Dynamometry
• Considered the “gold standard”
• 60°/sec for strength and power
assessment
• 300°/second for speed and endurance
assessment
Hand Held
Dynamometry with
Static Fixation at 90°
• Appropriate alternative
• Results may overestimate quadriceps
strength symmetry: be cautious
with data interpretation
SL 1RM Knee
Extension Machine:
90°- 45°
• Appropriate alternative
• Recommended to decrease stress on
PF joint and limit strain on
reconstructed ACL for up to 6
months
• Results may overestimate quadriceps
strength symmetry: be cautious
with data interpretation
SL 1RM Leg Press
• Fair alternative
• Results in significant overestimation of
quadriceps strength symmetry due
to compensation from other LE
muscle groups
SL 1RM Knee
Extension Machine:
90°- 0°
• Fair alternative
• May be uncomfortable and/or
inappropriate due to PF stress
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Appendix G: Single Leg Hop Series
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Authors: Tiffany Marulli, PT, DPT, OCS and Sarah Depp, PT, DPT, OCS
Revision Date: April 2023
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