Case Study: ACL Rehab, 5 Month Testing

ACL Rehab Knee Test

Post OP ACL-5 Month Testing Session

By: Zach Baker, PT, DPT, SCS | Program Director-R2P Sports Residency


I am currently working with a patient who underwent ACL reconstruction with a quad tendon graft surgery on 5/2/23.  We recently performed a progress note on her and performed a round of functional testing with her.  She is a local 10th grade high school basketball player who has aspirations of playing collegiately. While  she will not play in the high school season this Winter, we are hopeful that she will be able to participate in the AAU and tournament circuit in late Spring or Summertime. She will be roughly 1 year post op at that timeframe. 


She has had a consistent and uneventful rehab to date without any major setbacks or unforeseen circumstances to complicate her recovery. Her symptom profile was mild to begin with and has been insignificant following the first month. Her range of motion returned to levels symmetrical with the other limb at roughly 6 week post op and she was willing and able to begin weight bearing activities since the week of her surgery, with restoration of regular gait within the first month. The first two months of rehab involved utilization of Bloodflow Restriction Therapy for mitigation of atrophy and maintenance of strength during the early and more restricted phase of ACL.

In the second month, we began integrating various foundational and functional movements patterns involving squatting, hinging, stepping and lunging variations with modifications to range of motion and volume as able and tolerated. In the third month (and continuing to do so), we began progressively adding resistance to already established movement patterns that they demonstrated competency with in the preceding month. We also introduced pre-running plyometrics progressions.  At four months we initiated running and progressed through linear and nonlinear variations with changes to tempo/speed, distance, stride length, direction and volume. Submaximal multidirectional locomotive movements have been performed in controlled and often constrained environments. 


On 9/27/23, just shy of 5 months, we performed a round of testing on her and the results are below. Prior to these testing results, she already demonstrated competence with Anterior step down testing and Y Balance Testing, both with greater than 90% symmetry between limbs.


Circumference Measurements (in cm)

Mid thigh 

  • R-42
  • L-43.5

Mid Calf 

  • R-31.5
  • L-32.85


  • R-1 degree hyper extension and 150 flexion
  • L-10 degree hyper extension and 150 flexion


  • L – Quad: 53.0, Hamstring: 32.5 
  • R – Quad: 48.6, Hamstring: 25.7 
  • LSI – Quad: 91.7%, Hamstring: 79.5%

VALD Force Plate Testing

  • Repeated Jump: RSI=1.64 (30.3% Increase from last month and 44th percentile for age and gender)

Countermovement Jump (No arm swing allowed, hands on hips)

  • Jump Height: 9.5 inches (39.6% increase from last month and 35th percentile for age and gender)

Single Leg Jump  (No arm swing allowed, hands on hips)

  •  R=12.8 cm  L=11.1 cm  (39.6% Increase from last month and 30th percentile for age and gender)



Her LEFS demonstrates general self reported functionality and is trending in a positive direction with most limitations in her responses related to items she is not cleared to perform yet. Her range of motion is good, but we are still working on gaining as much symmetry with hyper extension as possible. The surgeon is aware of the asymmetry and was fine with progressing through protocol, but advised to continue working on further improvements as tolerated. Her isometric knee extension and flexion measurements have progressively gotten better with regards to maximal force output every month since we began testing.

The LSI is improving as well as we are over 90% with extension and roughly 80% with flexion.  This was mildly surprising given that she had a quad tendon graft. We were excited to see the extension output, but this prompted us to include more hamstring based strength work into her programming to try to reduce the current deficit.


We initiated a vertical hop testing profile at 4 months post op, with the intent of getting submaximal effort baseline numbers. This round of testing was the second round of vertical hop testing in her rehab journey. Confidence and performance was markedly improved since the last round of testing. Part of this can be attributed to familiarity with the testing protocol, but also having an additional month of strength training and plyometric programming performed in the clinic. The countermovement jump is utilized to gauge improvement with serial testing and is an easy metric to compare to her pre-injury status and also others her age and gender for normative standards. It’s also a sport specific task that translates well to her performance on the court. 

The single leg vertical hop is chosen to identify any asymmetries in performance between the surgical and non surgical limb. A vertical jump  has been shown in research to be influenced by the knee extension mechanism more so than a horizontal jump. Any strength or plyometric deficits are often more readily picked up with the vertical jumping tasks, whereas they can be masked by a hip dominant strategy with horizontal jumping and landing. While she was not symmetrical, she is improving symmetry and overall jump height compared to last month.


Lastly, the repeated hop looks at her Reactive Strength Index. This is her ability to utilize the plyometric capabilities of her tissues and tap into the stretch shortening cycle for power production. This number is trending up in comparison to last month. If an athlete struggles here, you can look at differentiating their performances with countermovement versus non countermovement tasks, their overall strength metrics and also any fear avoidance tendencies to determine the rate limiting factor. 


Overall, she is trending in a very positive direction. Moving forward, we will continue to increase her overall strength and conditioning levels with a mix of aerobic and anaerobic tasks in the weight room and with locomotive based tasks. Strength will be a mixture of basic and isolated movements with minimal movement complexity to optimize force output and specificity of tissue loading, in addition to more functional and advanced movements looking at the integration of mobility and stability demands.

We will progress into more complex plyometrics with variations in stances and directions of force output. Plyometrics will have an emphasis and be broken down into propulsive and absorptive tasks. Through all of this, we will monitor fatigue levels, maintenance/progression of range of motion, symptoms levels and movement strategy. As we progress further and verify improvement with our next round of testing at the 6 month mark, we will begin to integrate sport specific tasks and movements. 

Stay tuned for more Case Studies from Dr. Baker and the staff.

Ready 2 Master the ACL Rehab Process?  Learn more from Dr. Baker and the R2P Academy Team with the ACL Rehab Accelerator Online Course.  Approved for 6 Hours of CEUs for Physical Therapists in all 50 States.  Learn more and get started HERE


ACL Rehab Recovery

Dr. Baker, ACL, physical therapists, ACL Rehab

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