JUNE 2020
KNEE SIG NEWSLETTER
June Newsletter Topic: Regaining Quadriceps Strength Early after ACL Reconstruction (Part 1 of 2)
Courtesy of SIG Education Committee Member Elanna Arhos
JOSPT Asks Facebook Live: Dr. Lynn Snyder-Mackler
Clinical Takeaways for Early Phase of Rehabilitation:
· NMES to get quads going again: helps athletes volitionally activate quads again, start day 1 and continue to use stim until quad LSI is at least 80%
- The threshold is about 50% of maximal voluntary isometric contraction for dosage using an electromechanical dynamometer
- If no electromechanical dynamometer (Fitzgerald 2003, JOSPT), strongest tolerable contraction with the knee in full extension on the treatment table
· Best way to measure quadriceps strength: In OKC, either using isokinetic dynamometer or handheld dynamometer. Use caution when testing strength with a 1 repetition maximum as patients can cheat
· OKC vs. CKC Training: No reason to avoid OKC knee extension in early phase rehabilitation- kill the sacred cow! If you’re letting them walk, you should be doing OKC leg exercises
· RTS Criteria: Quad Strength Limb Symmetry Index (LSI) >90%, hop testing (single hop, triple hop for distance, crossover hop, 6-meter timed hop) all >90%, global rating of knee function >90%, KOS-ADL >90%
- Patients must pass testing criteria, and then start with on-field training, gradually progressing to 1 on 1
· Psychological Readiness: TSK-11 helpful early on in rehabilitation, ACL-RSI is more helpful during later rehabilitation to determine barriers for RTS
Related Research:
- Kim, Kyung-Min, et al. "Effects of neuromuscular electrical stimulation after anterior cruciate ligament reconstruction on quadriceps strength, function, and patient-oriented outcomes: a systematic review." journal of orthopedic & sports physical therapy 40.7 (2010): 383-391.
- Adams, Douglas, et al. "Current concepts for anterior cruciate ligament reconstruction: a criterion-based rehabilitation progression." journal of orthopedic & sports physical therapy 42.7 (2012): 601-614.
Clinical Takeaways:
· Quadriceps are affected by atherogenic muscle inhibition after ACL reconstruction
· NMES should be used to augment quadriceps strengthening through directly recruiting motor neurons to improve strength gains and functional outcomes
· Best evidence suggests 4 weeks of NMES in conjunction with exercise therapy is recommended for inclusion into postop rehab: moderate effect on self-reported outcomes at 12-16 weeks postoperatively
· Apply with the patient in sitting and knee in 60° of flexion (can vary the angle of flexion based on pain and comorbidities)
- Parameters: 2500 Hz; 75 bursts; 2-second ramp; 12 seconds on, 50 seconds rest; intensity to maximum tolerable (at least 50% MVIC); 10 contractions per session. 3 sessions/week until quadriceps strength MVIC is 80% of uninvolved
· Should be achieving quadriceps strength >50% LSI by week 4, and quadriceps strength LSI >80% by weeks 6 to 8
Eccentric Cross Training Knee Neuromuscular Control Mechanisms after ACL-Reconstruction
Courtesy of SIG Education Committee Member Meredith Chaput
Quadriceps atherogenic muscle inhibition (AMI) is a key driver in mediating prolonged neuromuscular deficits seen following anterior cruciate ligament (ACL) injury.1,2 Appropriate quadriceps strength is required for force absorption and joint loading during daily functional tasks and sports activity. Despite an emphasis on strength recovery in rehabilitation, restoring quadriceps neuromuscular control is a prolonged battle throughout rehabilitation following ACL reconstruction.2
Typical rehabilitation programs following ACL reconstruction employ strengthening interventions that are primarily isometric and concentric in nature. Concentric muscle contractions rely on spinal reflex circuitry whereas eccentric muscle contractions utilize more motor cortex drive. Lepley et al.,3 suggest that the neural mechanisms involved in typical rehabilitation strength programs may provide evidence as to why traditional approaches are unsuccessful at restoring neuromuscular control in patients following ACL reconstruction.
The acute stages of quadriceps inhibition, secondary to AMI, result in decreased spinal reflex excitability. Overtime (intermediate to end stages of rehabilitation), the motor cortex requires an increased cortical drive to produce quadriceps muscle activation. Neuromuscular electrical stimulation (NMES) is a tool that can safely be implemented and helps to address both the peripheral muscle and central nervous system adaptions seen following ACL reconstruction.
Lepley et al, 20134 randomly assigned patients to one of four treatment groups: NMES and eccentric training, NMES only, eccentric only, and standard rehabilitation without NMES or eccentric training in the first 12 weeks. They completed quadriceps strength assessments using an isokinetic dynamometer pre-operatively, at 12 weeks post-surgery, and at the time of return to play clearance. Participants who received NMES and eccentrics and NMES only began 6 weeks of NMES training at the initial rehabilitation visit (2x a week for 6 weeks). At 6 weeks post-surgery eccentric training began for the NMES and eccentric group as well as the eccentric only participants (2x week for 6 weeks). Their results demonstrated that the combined NMES and eccentric training group had improved quadriceps strength recovery better than NMES alone and standard therapy. Eccentric training in their participants was superior to standard therapy alone. The authors concluded that eccentric exercise was the driver behind quadriceps improvement, and incorporation with NMES training enhances quadriceps strength recovery in their cohort.4
Clinical Take-Aways:
· NMES can play an important role in both peripheral and central neuromuscular recovery following ACL reconstruction
· Eccentric exercise emphasis (2x week for 6 weeks) may have an additive benefit for quadriceps muscle strength recovery than standard therapy.
1. Hart JM, Pietrosimone B, Hertel J, Ingersoll CD. Quadriceps Activation Following Knee Injuries: A Systematic Review. J Athl Train. 2010;45(1):87-97. doi:10.4085/1062-6050-45.1.87
2. Lepley AS, Grooms DR, Burland JP, Davi SM, Kinsella-Shaw JM, Lepley LK. Quadriceps muscle function following anterior cruciate ligament reconstruction: systemic differences in neural and morphological characteristics. Exp Brain Res. 2019;237(5):1267-1278. doi:10.1007/s00221-019-05499-x
3. Lepley LK, Lepley AS, Onate JA, Grooms DR. Eccentric Exercise to Enhance Neuromuscular Control. Sports Health. 2017;9(4):333-340. doi:10.1177/1941738117710913
4. Lepley LK, Wojtys EM, Palmieri-Smith RM. Combination of eccentric exercise and neuromuscular electrical stimulation to improve quadriceps function post-ACL reconstruction. The Knee. 2015;22(3):270-277. doi:10.1016/j.knee.2014.11.013
"Picture From: - Lepley LK, Wojtys EM, Palmieri-Smith RM. Doi: 10.1016/j.knee.2014.11.013 - Figure 3
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