Skip to main content
 
Blood flow restriction (BFR) therapy application. (A) Delfi Personalized Tourniquet System for BFR with pneumatic cuff (third-generation tourniquet). (B) Application of BFR during quadriceps activation exercise after arthroscopic knee surgery. In: DePhillipo NN, Kennedy MI, Aman ZS, et al. Blood flow restriction therapy after knee surgery: indications, safety considerations, and postoperative protocol. Arthroscopy Techniques. Oct 2018; 7(10):e1037-43. DOI: doi.org/10.1016/j.eats.2018.06.010.

by Emma Shirley, SPT

Background

My first encounter with blood flow restriction (BFR) was an informal brush during my undergraduate years at East Carolina University. While working out at my local CrossFit gym, a guy next to me on the squat racks whipped out two thick elastic bands. He wrapped them extremely tightly around his proximal thighs, then proceeded to un-rack his weight and squat. An exercise physiology student at the time, I was perplexed. I asked him about it, and he told me about blood flow occlusion, which he claimed helped maximize “gains.” As a CrossFit coach and athlete, and a dabbler in the power and Olympic weightlifting sports, I have seen BFR implemented in many different forms, from elastic bands haphazardly wrapped around an exercising limb in a sweaty weight room, to a more nuanced and measured application in the clinic.

While the APTA endorses BFR training as part of physical therapy’s professional scope, is not taught formally in NC physical therapy school curriculum.1,2 However, through independent reading of research publications, and exploring the physical therapy and sports medicine social media community, I learned independently about BFR. True, medical applications of BFR, unlike my friend at the CrossFit gym, use formal tourniquet devices to occlude venous return while decreasing arterial flow.2 I found it very interesting not only because of its prevalence in my hobbies and sports, but also due to its rising popularity in many facets of physical therapy, from orthopedics and sports, to geriatrics and pelvic floor.2-4 It seemed like something useful to pursue a certification in, as an aspiring orthopedics physical therapist.

My favorite unit in our musculoskeletal courses was the knee, but particularly ACL reconstruction rehabilitation; in class, we learned that ACL reconstruction rehabilitation is widely varied and there is a lot of controversy over the most appropriate protocol or approach. I had seen BFR discussed with ACL reconstruction rehabilitation on popular physical therapy social media accounts. I noticed a large body of research asserting that BFR creates positive clinical outcomes in patients at risk for sarcopenia.21 It seemed like a very interesting to question to pursue the efficacy of BFR, if any, in rehabilitation following ACL reconstruction.


Statement of Need/Purpose

Anterior cruciate ligament (ACL) rupture is a common occurrence in both recreational and professional athletes.7-10,12-16 It is estimated that approximately 200,000 ACL reconstruction surgeries are performed annually in the United States.9 Despite ACL reconstruction and current best practice rehabilitation, only 60% of amateur and 83% percent of elite athletes return to sport.7,13,15,16,23 Furthermore, of those whom return to sport, there is a prominent persistence of quadriceps strength deficits and limb strength asymmetry that results in decreased sports performance compared to before injury.7-10,12,14-16 These strength and participation impairments may persist for as long as 20 years following ACL reconstruction.9 Quadriceps strength deficits and limb strength asymmetry after ACL reconstruction has been linked to long-term consequences, such as early-onset knee osteoarthritis, despite prioritization of quadriceps strength during rehabilitation.9,12,13,14-16,23

Strength training is typically implemented in post-ACL reconstruction rehabilitation by progressive overload using at least 70% of an individual’s 1-repetition maximum in order to trigger physiological strengthening responses.5,6,18,21 Greater magnitudes of loading require a greater number of motor units, thus maximizing strength adaptations via higher rates of motor unit recruitment.6 However, this magnitude of heavy loading is not practical or safe during early rehabilitation after ACL reconstruction due to high mechanical stressors placed on healing tissues.5,18 This combination of factors has created a need for safe but effective methods of muscular strengthening after ACL reconstruction.

Blood flow restriction (BFR) training is an alternate strengthening approach to the progressive overload principle and may be appropriate during early recovery. BFR involves the application of an inflatable cuff, wrap, band, or tourniquet during therapeutic activity or exercise, in order to occlude venous return from an active muscle while still allowing arterial blood flow.5,11 BFR training has been shown to positively affect muscle strength and hypertrophy with lower amounts of external loading, and has been successfully applied in sports training and musculoskeletal rehabilitation, the latter particularly with older adults.5,11,17,18,20-22  BFR interventions with older adults, paired with lower loading, have resulted in strength gains comparable to those elicited with heavy loading.5,21 It is, however, unclear if BFR is any more effective in eliciting changes in strength than usual care following ACL reconstruction. BFR interventions may be appropriate for use before, or after, ACL reconstruction for application of stimulus mimicking heavy loading in rehabilitation while maintaining post-surgical precautions to avoid excessive stress on healing tissues. However, at the time of this writing, there have been no published systematic reviews examining the efficacy of BFR intervention with ACL reconstruction rehabilitation.

The purpose of this systematic review was to examine the effects of BFR intervention before or after ACL reconstruction on strength, pain, range of motion (ROM), and function. Pain, ROM, and function will be addressed in addition to strength due to their intricate relationship with patient rehabilitation participation and overall outcomes.


Overview

The systematic review was performed on February 5, 2020 in CINAHL, Embase, PEDRo, ProQuest Health Administration Database, PubMed, Scopus, SportDiscus, and Web of Science. Three hundred and eleven studies were included for screening; eleven articles were included for final review. Two articles addressed the same study and cohort, so a total of 10 distinct studies were included. The average PEDro score for randomized studies was 5/10, indicating a moderate risk of bias. Eight studies included measures of strength, two included measures of pain, two addressed range of motion, and three involved self-reported or performance measures of function. There were inconsistent results all of the aforementioned examined outcomes. At this time, it cannot be said that BFR intervention yields superior results to usual care on strength, pain, ROM, and functional outcomes following ACL reconstruction. This is consistent for BFR intervention before surgery, and during early, middle, and late recovery after ACL reconstruction. This review had a number of limitations, including included studies’ risk of bias, differing post-operative rehabilitation protocols, variation in equipment and parameters of the BFR interventions, differing comparison groups, and lack of reporting of raw data. A greater number of higher-quality studies is needed to draw definitive conclusions on the application of BFR intervention before or after ACL reconstruction.


Products

I conducted a systematic review on February 5, 2020 and created my primary product, a manuscript based on my findings intended for physical therapists and health care professionals. I created two layman-targeted deliverables- a layman’s summary and an infographic.


Evaluation

The manuscript went through multiple peer and advisor reviews prior to finalization. These included after the writing of the introduction, methods and results, and the full draft. At each stage, a peer (Tanner Holden, SPT or Gabe Dimock, SPT) and Dr. Thoma performed independent reviews. Dr. Thoma also provided feedback for the infographic and layman’s summary prior to finalization. At midterm, committee members Dr. Jon Hacke and Dr. Jibran Qayumi were provided the introduction, methods, and results section with opportunities to provide feedback at needed. At final, they provided feedback on the final full manuscript as well as the layman’s summary and infographic.


Self-Reflection

This has been a long process spanning over the length of two semesters. I have learned about the intricate process that goes into the conduction of a systematic review; it is much more involved than I initially thought. Additionally, I have learned how to look more closely at research, including weighing factors like comparison groups, risk of bias, and clarity of data reporting. This project has provided me with the tools to more confidently appraise and draw conclusions from research, even in new and emerging topics in which studies may be scarce. At the beginning of physical therapy school, I could not have imagined being able to accomplish a project of this scope. It was exciting to compile my knowledge over the past 3 years to produce a product that I find interesting and take pride in.


Acknowledgments

First and foremost, my rockstar advisor, Dr. Louise Thoma, deserves endless praise. I worked with her for the past academic year, both during this capstone elective and the research credit I did with her in the spring. Conducting a systematic review is no walk in the park, but she patiently helped and enabled me to confidently complete this project and create a product I am proud of.

Secondly, I owe a big thank-you to my systematic review teammates and classmates, Tanner Holden and Gabe Dimock. I could not have gotten through endless hours of title and abstract screening full text review without you guys. Their reviews and feedback throughout the process were invaluable.

Thirdly, thank you my committee members, Dr. Jon Hacke and Dr. Jibran Qayumi, for providing desperately needed input and feedback. I especially appreciate that you took time out of your busy days during such a difficult time. Your expert opinions were key to perfecting this project.

Thank you to my mom Wendy, grandma Marilyn, and my dog, Kaylee, for the love and support throughout these three years of physical therapy school. I would not have been able to even have a chance to go to graduate school without you guys by my side. I am endlessly appreciative.

Finally, thank you to my classmates! I’m so grateful to have had such a great group to grow and learn with. I am excited to see where each of goes and the things we achieve during our careers.


References:

  1. Q&A. News from North Carolina Board of Physical Therapy Examiners. Nov 2019; 51:7.
  2. Blood-Flow Restriction Training (BFRT). APTA American Physical Therapy Association. https://www.apta.org/PatientCare/BloodFlowRestrictionTraining/. Last updated May 24, 2019. Accessed Apr 15, 2020.
  3. Carr K. Identifying how low intensity exercise with blood flow restriction is clinically relevant to the older adult. GeriNotes. Jan 2018; 25(1): 18-21.
  4. Kennedy-Guess S, Johnson AJ, Jacobs PG. Blood flow restriction and its potential use in women with pelvic organ prolapse and stress incontinence: a case report. Journal of Women’s Health Physical Therapy. Oct/Dec 2019. 43(4):194-201. DOI: 10.1097/JWH.0000000000000145.
  5. Slysz J, Stultz J, Burr JF. The efficacy of blood flow restricted exercise: A systematic review & meta-analysis. J. Sci. Med. Sport2016;19(8):669-675. doi:10.1016/j.jsams.2015.09.005.
  6. Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and Hypertrophy Adaptations Between Low- vs. High-Load Resistance Training: A Systematic Review and Meta-analysis. J. Strength Cond. Res.2017;31(12):3508-3523. doi:10.1519/JSC.0000000000002200.
  7. Lai CCH, Ardern CL, Feller JA, Webster KE. Eighty-three per cent of elite athletes return to preinjury sport after anterior cruciate ligament reconstruction: a systematic review with meta-analysis of return to sport rates, graft rupture rates and performance outcomes. Br. J. Sports Med.2018;52(2):128-138. doi:10.1136/bjsports-2016-096836.
  8. Tourville TW, Jarrell KM, Naud S, Slauterbeck JR, Johnson RJ, Beynnon BD. Relationship between isokinetic strength and tibiofemoral joint space width changes after anterior cruciate ligament reconstruction. Am. J. Sports Med.2014;42(2):302-311. doi:10.1177/0363546513510672.
  9. Tengman E, Brax Olofsson L, Stensdotter AK, Nilsson KG, Häger CK. Anterior cruciate ligament injury after more than 20 years. II. Concentric and eccentric knee muscle strength. Scand. J. Med. Sci. Sports2014;24(6):e501-509. doi:10.1111/sms.12215.
  10. Palmieri-Smith RM, Lepley LK. Quadriceps strength asymmetry after anterior cruciate ligament reconstruction alters knee joint biomechanics and functional performance at time of return to activity. Am. J. Sports Med.2015;43(7):1662-1669. doi:10.1177/0363546515578252.
  11. Scott BR, Loenneke JP, Slattery KM, Dascombe BJ. Exercise with blood flow restriction: an updated evidence-based approach for enhanced muscular development. Sports Med.2015;45(3):313-325. doi:10.1007/s40279-014-0288-1.
  12. Paterno MV, Ford KR, Myer GD, Heyl R, Hewett TE. Limb asymmetries in landing and jumping 2 years following anterior cruciate ligament reconstruction. Clin. J. Sport Med.2007;17(4):258-262. doi:10.1097/JSM.0b013e31804c77ea.
  13. Cavanaugh JT, Powers M. ACL rehabilitation progression: where are we now? Curr. Rev. Musculoskelet. Med.2017;10(3):289-296. doi:10.1007/s12178-017-9426-3.
  14. Pamukoff DN, Pietrosimone BG, Ryan ED, Lee DR, Blackburn JT. Quadriceps Function and Hamstrings Co-Activation After Anterior Cruciate Ligament Reconstruction. J. Athl. Train.2017;52(5):422-428. doi:10.4085/1062-6050-52.3.05.
  15. Lentz TA, Zeppieri G, Tillman SM, Indelicato PA, Moser MW, George SZ, Chmielewski TL. Return to preinjury sports participation following anterior cruciate ligament reconstruction: contributions of demographic, knee impairment, and self-report measures. J. Orthop. Sports Phys. Ther.2012;42(11):893-901. doi:10.2519/jospt.2012.4077.
  16. Lentz TA, Tillman SM, Indelicato PA, Moser MW, George SZ, Chmielewski TL. Factors associated with function after anterior cruciate ligament reconstruction. Sports Health2009;1(1):47-53. doi:10.1177/1941738108326700.
  17. Baker BS, Stannard MS, Duren DL, Cook JL, Stannard JP. Does blood flow restriction therapy in patients older than age 50 result in muscle hypertrophy, increased strength, or greater physical function? A systematic review. Clin. Orthop. Relat. Res.2019. doi:10.1097/CORR.0000000000001090.
  18. Hwang PS, Willoughby DS. Mechanisms Behind Blood Flow-Restricted Training and its Effect Toward Muscle Growth. J. Strength Cond. Res.2019;33 Suppl 1:S167-S179. doi:10.1519/JSC.0000000000002384.
  19. Lixandrão ME, Ugrinowitsch C, Berton R, Vechin FC, Conceição MS, Damas F, Libardi CA, Roschel H. Magnitude of Muscle Strength and Mass Adaptations Between High-Load Resistance Training Versus Low-Load Resistance Training Associated with Blood-Flow Restriction: A Systematic Review and Meta-Analysis. Sports Med.2018;48(2):361-378. doi:10.1007/s40279-017-0795-y.
  20. Day B. Personalized blood flow restriction therapy: how, when and where can it accelerate rehabilitation after surgery? Arthroscopy2018;34(8):2511-2513. doi:10.1016/j.arthro.2018.06.022.
  21. Hughes L, Paton B, Rosenblatt B, Gissane C, Patterson SD. Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis. Br. J. Sports Med.2017;51(13):1003-1011. doi:10.1136/bjsports-2016-097071.
  22. Minniti MC, Statkevich AP, Kelly RL, Rigsby VP, Exline MM, Rhon DI, Clewley D. The safety of blood flow restriction training as a therapeutic intervention for patients with musculoskeletal disorders: A systematic review. Am. J. Sports Med.2019:363546519882652. doi:10.1177/0363546519882652.
  23. Wilk KE, Macrina LC, Cain EL, Dugas JR, Andrews JR. Recent advances in the rehabilitation of anterior cruciate ligament injuries. J. Orthop. Sports Phys. Ther.2012;42(3):153-171. doi:10.2519/jospt.2012.3741.
  24. Blood flow restriction (BFR) therapy application. (A) Delfi Personalized Tourniquet System for BFR with pneumatic cuff (third-generation tourniquet). (B) Application of BFR during quadriceps activation exercise after arthroscopic knee surgery. In: DePhillipo NN, Kennedy MI, Aman ZS, et al. Blood flow restriction therapy after knee surgery: indications, safety considerations, and postoperative protocol. Arthroscopy Techniques. Oct 2018;; 7(10):e1037-43. DOI: doi.org/10.1016/j.eats.2018.06.010.

 

10 Responses to “Blood flow restriction interventions before and after anterior cruciate ligament reconstruction: A systematic review”

  1. Emma Shirley

    Kristen,
    Thank you for reading and for your commentary! I’m really glad you got a lot of the review. I really appreciate you taking the time to read it through! Thank you again for your feedback.

    Reply
  2. Emma Shirley

    Matt,
    Whoops, totally overlooked your question at the end there! I think that, theoretically, BFR does mimick heavy loads and should effect change comparable to interventions that use heavy loading. Theoretically, it should! However, the jury is still out on definitively saying that is so when it comes to ACL injury and reconstruction.

    Reply
  3. Emma Shirley

    Matt,
    Thank you for reading and for your comments as well! I discussed in the above comment briefly with Hannah about why BFR may not show the same great results after ACL reconstruction/injury as it has shown in other populations. However, this doesn’t mean that BFR is not effective for those with ACL injury or for ACL reconstruction rehabilitation – the literature is just too heterogenous, and study quality is not high enough, to draw any definitive conclusons at this point. Also, this is just one application of many for BFR! I’m interested to see additional research for BFR in different applications as the body of literature continues to grow.
    Thanks again for reading!

    Reply
  4. Emma Shirley

    Hannah,

    Thank you for reading, and for your thoughtful commentry and questions! Higher quality studies may or may not show more significant effects – either way, having higher quality and lower risk of bias would enable us to more confidently draw conclusions from whatever the gathered data reveals. The greatest body of research for physical therapy applications of BFR appears to exist in regards to use for older adults with sarcopenia. My preliminary reviews of the literature also revealed a growing body of evidence applying BFR to individuals with knee OA, which seems to have a greater effect on pain. If higher quality and lower risk of bias literature continues to reveal no greater outcomes with BFR after ACL rehabilitation compared to usual care, my (very, very surface theory) would be because of the same (still theorized and mostly unknown) underlying reasons as to why usual care is currently inadequate. BFR simply may not trump usual care and does not exceed whatever factors, pathophysiologically, in rehabilitation, or otherwise, are preventing full and long-term recoveries after ACL reconstruction currently. However, until the literature is of higher quality and lower risk of bias, and with the adjustments I mentioned in my discussion, there can be no definitive decision either way about the effectiveness of BFR implementation in rehabilitation following ACL injury or reconstruction.

    I hope this answers your questions! Thanks again for reading!

    Reply
  5. Emma Shirley

    Debbie & stromain,

    Thank you both for your kind words. This project has definitely been an incredible learning experiene and a labor of love. I would definitely like to push forward for publication, but it may be dependent how things unfold over the next few months between NPTE, clinical internship, and pandemic! However, this is a very hot topic and literature has already been added since the date of the literature search for this review, so it would definitely be valuable and add to the dialogue surrounding the evidence.

    Thank you for your time and comments!

    Reply
  6. Kristen Shumaker

    Emma,

    Great job on your capstone! BFR is honestly one topic I have never given a lot of time to researching/studying, so I found your project so informative and interesting. It was also refreshing as to how well I could appreciate your level of interest and passion for this subject, given all the hard work that is clearly demonstrated in your final product. I was unaware of the persistence of quadricep strength impairments (20 years) that are seen in those following ACL reconstruction, thus making the information surrounding the potential benefits of BFR critical to assess as an additional/alternative intervention. With the results of the studies included in your review are yielding inconsistent significant results with the use of BFR after ACL reconstruction, I think you make a valid point in suggesting that future randomized controlled trials should work to produce more conclusive evidence supporting the benefits of BFR both before and after ACL reconstruction.
    I also agree with Hannah’s comment about the Layman’s summary. Your review was so informative and easy to follow, but the summary is certainly a very nice touch that guides you through the use of BFR and primary findings. The infographic is another great additional source that simplifies the information even more and provides a condensed introduction to the intervention. Overall, I want to applaud you on completing such an impressive capstone project. You have consistently displayed an amazing work ethic throughout these 3 years, and I am proud of all the hard work you have clearly put into this throughout third year!

    Best,

    Kristen

    Reply
  7. Matt chaus

    Hi Emma,

    First of all, I am extremely impressed with all the work that went into the development of this capstone presentation. As you mentioned conducting a systematic review is no easy feat and you should be proud of your accomplishment. I find this topic extremely interesting as BFR training is gaining significant notoriety in the field. I am planning on taking a BFR training continuing education course this summer to learn more about the potential benefits and clinical usefulness of this intervention. I think that your systematic review was well put together, well organized, and provided good information into the evidence surrounding ACL rehabilitation and the use of BFR. I believe that you touched on a very important aspect of research. That being because of how new BFR training is there, to my knowledge, is not a set protocol especially when rehabbing a patient post-op. As you eluded to this makes comparing results between studies difficult. I also really appreciated you highlighting some of the limitations with these studies as I feel like often research is subject to some form of publication bias. I found it interesting that there were minimal significant results that came from your review of the literature. With all the popularity surrounding this intervention, I would have expected more positive results. Overall, I thought you did an excellent job and believe that the knowledge gained on how to systematically review the literature will most certainly help you as a future clinician. Best of luck with all your future endeavors!

    Question:
    Based on your research do you think that with stricter and more consistent protocols that blood flow restriction be a beneficial intervention for those who unable to tolerate heavy loads?

    Reply
  8. Hannah Ryan

    Hi Emma,

    I was excited to read your work, as I admittedly knew very little about blood flow restriction before reading your review. First, I want to commend you for your hard work completing this large undertaking. I am sure it was a valuable experience to go through the process of writing a systematic review, and I am so proud of your final result! I really like that your review not only looks at changes in strength but also changes in function, pain, and range of motion. If your review is published (which I hope it will be!), your recommendations for future directions will hopefully lead higher quality studies with more consistent use of parameters and lower bias. Do you think that higher quality studies might lead to more promising results? If not, why do you think blood flow restriction might not be effective for these outcomes in individuals pre- or post-ACL? During your search, did you happen to find what conditions BFR is most effective for?

    I also really like your Layman’s summary and infographic. The infographic is easy to follow and provides very important information to patients in an understandable way! Great work on your capstone! I hope you are very proud of all that you have accomplished!

    Best,

    Hannah

    Reply
  9. stromain

    Emma,

    I commend you on this undertaking of synthesizing and analyzing the quality of evidence on such an important topic. I work in out-patient orthopedics and see many people whipping out BFR units for ACLR patients – greatest invention since window screens, it seems. However, few are consuming the literature critically and are quick to jump on new trends in treatment. This review is very helpful to understand where things stand and clearly more well-designed and controlled trials are needed. The info for layman is important as well so that our patients can be informed consumers of interventions.
    Thank you for your efforts. Will you plan to publish your work? I think this information is well summarized. One point you may get dinged on if trying to publish is whether or not 2 of your reviewed abstracts, titles, full text, and scored risk of bias blinded from one another, which is an important feature of a SR. If not, you could submit it as an excellent narrative review.

    Thank you again for your excellent work! All the best to you in your therapy career!

    Reply
  10. Debbie Thorpe

    Emma
    Very nice systematic review on BFR after ACL reconstruction! I was not aware of this intervention and learned a lot by reading your review! Your infographic was very informative and will be useful in the clinic. I cant wait to see this manuscript published! You should be very proud of this project!
    Best Wishes

    Reply

Leave a Reply