Survey of blood flow restriction therapy for rehabilitation in Sports Medicine patients

‬‬‬Abstract

Background

Blood flow restriction (BFR) therapy has demonstrated benefits across a spectrum of musculoskeletal injuries, including improved strength, endurance, function, and reduction in pain perception. There is, however, no standardized application of BFR therapy among orthopaedic surgeons within the United States (US).

Hypothesis

The indication and protocol for BFR therapy vary significantly across providers in the US.

Methods

An online survey of 21 multiple-choice questions was sent to 3,281 surgeons listed on a large orthopaedic registry. A cross-sectional study was performed on all surgeons who successfully completed the questionnaire. Surgeons were queried on current or planned use of BFR, indications, contraindications, and peri-operative and non-operative management of sports-related injuries.

Results

Overall, 250 physicians completed the survey, with 149 (59.8%) reporting current BFR use and 75.2% initiating use in the last 1–5 years. Most protocols (78.8%) utilize the modality 2–3 times per week while 15.9% use it only once weekly. Anterior cruciate ligament reconstruction (ACLR) rehabilitation was the most reported indication for initiating BFR therapy (95.7%) along with medial patellofemoral ligament reconstruction (70.2%), multiligamentous knee reconstruction (68.8%), meniscus repair (62.4%), collateral ligament reconstruction (50.4%), Achilles tendon repairs (30.5%), and meniscectomy (27%). Only 36.5% reported using BFR after upper extremity procedures, such as distal biceps repair (19.7%), ulnar collateral ligament elbow reconstruction (17%), rotator cuff (16.8%), and shoulder labrum repair (15.3%). For non-operative injuries, 65.8% of surgeons utilized BFR. Of those not currently using BFR therapy, 33.3% intended to implement its use in the future.

Conclusion

BFR therapy has increased in popularity with most physicians implementing its use in the last 5 years. BFR was commonly utilized after ACLR.

Clinical relevance

BFR allows light-load resistance to simulate high-intensity resistance training. This study describes US orthopaedic surgeons’ common practice patterns and patient populations that utilize BFR therapy.

1. Introduction

Blood flow restriction (BFR) therapy has gained popularity in recent years as a tool for rehabilitation of musculoskeletal injuries. BFR therapy utilizes a pneumatic cuff to decrease venous return while maintaining arterial blood flow to targeted muscle groups.¹ In the postoperative or nonoperative injury setting, restriction of blood flow allows light-load resistance to simulate high-intensity resistance training, which induces muscular hypertrophy with similar efficacy.1, 2, 3, 4, 5, 6, 7 This vascular occlusion leads to muscular hypertrophy through a variety of proposed mechanisms, such as increased hormonal concentrations in the presence of decreased venous return, increased muscle protein synthesis via the mTOR pathway, and increased fast-twitch muscle fiber recruitment.⁸

The applications of BFR have demonstrated benefits across a wide spectrum of musculoskeletal injuries, including improved strength, endurance, function and reduction in pain perception in knee osteoarthritis, anterior cruciate ligament (ACL) reconstruction, Achilles tendon rupture, and various arthroscopic knee procedures.^2,9, 10, 11, 12, 13, 14, 15 These outcomes have been well-studied in both adult and elderly populations, suggesting its utility throughout the adult lifespan.^16,17 While the majority of research has documented the efficacy of BFR therapy in the lower limb, there are potential benefits with application of BFR therapy in the upper limbs as well, with improvements in muscle size and strength in muscles located both proximally and distally to the BFR device.¹⁸

Limiting vascular flow to an extremity inherently carries its own set of risks, although reported complications remain low.¹⁹ Rare adverse events include deep vein thrombosis and rhabdomyolysis while more common benign events include acute muscle pain, muscle fatigue, bruising, numbness, fainting, and dizziness.^17,20 However, Minniti et al. systematically reviewed the risks of BFR and found that there were no significant differences in the rate of adverse events between patients undergoing BFR therapy and those exposed to exercise alone, further confirming its safety in practice.²⁰

While the safety and efficacy of BFR therapy have been well studied, there is not yet a standardized application of BFR therapy among orthopaedic surgeons within the United States.¹¹ The purpose of this study is to evaluate practice patterns relating to the use of BFR therapy for rehabilitation of operative and non-operative sports-related injuries across the United States.

2. Methods

Following Institutional Review Board (IRB) approval, a cross-sectional study was conducted via online survey in July 2021. In accordance with previously utilized methodology, the survey was disseminated utilizing a secure online platform (https://docs.google.com/forms) to all physicians listed on a large orthopaedic registry from the American Orthopaedic Society for Sports Medicine (AOSSM).²¹ The survey was disseminated to 3,281 orthopaedic surgeons on July 20, 2021 and two reminders were sent to encourage participation. The survey was made anonymous and no identifiable information was collected. All surgeons who successfully completed the questionnaire in its entirety were included in the final analysis.

The survey was developed by multiple authors (JC, JT, DC) surrounding the practice of BFR therapy for orthopaedic injuries. The questions were reviewed by the aforementioned authors and group consensus narrowed the survey to 21 multiple-choice questions (Appendix 1) relating to BFR therapy. Orthopaedic surgeons were asked about practice demographics including years of practice, patient demographics, and institutional practice setting. Additionally, questions were asked about BFR usage in the pre- and post-operative setting, as well as in non-operative management. A Google forms survey was created and tested before implementation. The survey was then sent to surgeons listed on the American Orthopaedic Society for Sports Medicine (AOSSM) registry.

2.1. Statistical analysis

Categorical variables were presented as counts and column percentages (N(%)) for all responses. All statistical analysis was performed with SAS 9.4 (SAS institute Inc., Cary NC, USA).

3. Results

Overall, 7.7% of orthopaedic surgeons listed on the AOSSM directory (254 of 3,281 surgeons) responded to survey; 152 of them (60.1%) used BFR therapy in their practice. For those not currently utilizing BFR therapy, 33.3% intend to implement the technique in the future. Implementation of when BFR therapy in the providers practice is detailed in Table 1. Of those using BFR therapy, 67.1% use BFR therapy in all patient populations while the remainder use the technique exclusively in athletic populations ranging from recreational to professional.

Table 1.

Demographics of survey respondents.

	<5 Years	5–10 Years	10+ Years
Years in Practicerowhead	27.0% (68/252)	18.0% (46/252)	54.8% (138/252)
	Professional	Collegiate	High School	None
Highest Level of Teams Coveredrowhead	40.5% (102/252)	34.9% (88/252)	15.1% (38/252)	9.5% (24/252)
	Private	Academic
Practice Settingrowhead	61.2% (153/250)	38.8% (97/250)
	Yes	No
BFR Userowhead	60.1% (152/253)	39.9% (101/253)
	<1 Year	1–5 Years	5–10 Years	>10 Years
Length of BFR Use in Practicerowhead	14.5% (22/152)	75% (114/152)	9.2% (14/152)	1.3% (2/152)

The majority of physician protocols (78.8%) utilize the modality 2–3 times per week while 15.9% use it only once weekly. BFR cuff pressure was determined by percent of limb occlusion pressure in 53.3% of surgeons while 13.8% answered that a standard pressure is used. Overall, 57.7% of providers report that their patients specifically request BFR therapy. Additionally, BFR therapy appears to be well tolerated with 77.9% of surgeons reporting that patients have not had to stop BFR secondary to pain intolerance (Table 2).

Table 2.

BFR practice protocols.

	None	Peripheral Vascular Disease	Lymphedema	Neurapraxia or Nerve Injury	History of DVT	Diabetes	Hypertension	Smokers	Other
Contraindications Indicated	11.2% (17/152)	75% (114/152)	72.4% (110/152)	68.4% (104/152)	68.4% (104/152)	17.1% (26/152)	12.5% (19/152)	12.5% (19/152)	4.6% (7/152)
	No	Yes
Patient Diagnosed with DVT after BFR Initiation	99.3% (150/151)	0.7% (1/151)
	Percent of Limb Occlusion Pressure	Standard Pressure	Determined by Physical Therapy	No Set Pressure	Unsure
Determination of BFR Cuff Pressure	53.3% (81/152)	13.8% (21/152)	11.2% (17/152)	3.3% (5/152)	18.4% (28/152)
	2–3 Times per Week	1 Time per Week	4–5 Times per Week	>7 Times per Week
BFR Therapy Frequency	78.80% (119/151)	15.9% (24/151)	2.0% (3/151)	3.3% (5/151)
	No	Yes	Unsure
Ischemic Preconditioning Used prior to BFR Therapy Initiation	42.4% (64/151)	6.6% (10/151)	51.0% (77/151)
	No	Yes
Patient Specifically Request BFR Therapy	58.6% (89/152)	41.4% (63/152)
	No	Yes
Patients Request BFR Therapy Discontinuation due to Pain	77.6% (118/152)	22.4% (34/152)

Other: Recent incisions, arrythmias, old age, sickle cell anemia, open wound, per physical therapy, osteonecrosis.

Of the 152 physicians using BFR in practice, 144 (94.7%) reported using the technique for postoperative rehabilitation (Fig. 1). The time at which this therapy was initiated during the post-operative period is represented in Table 3. The primary cited benefit of BFR was improved limb/muscle strength in 93.1% of respondents while other cited benefits included improved extremity function (48.6%) and quicker return to sport (31.3%) (Table 3). Patients undergoing anterior cruciate ligament reconstruction (ACLR) were most commonly prescribed this therapy (95.8%). Other common lower extremity procedure indications included MPFL reconstruction (70.8%), multi-ligamentous knee reconstruction (69.4%), meniscus repair (63.2%), MCL or LCL reconstruction (51.4%), Achilles tendon repairs (31.9%), and meniscectomy (27.1%).

Fig. 1.

Percent of surgeons who utilize BFR for postoperative rehabilitation in various lower extremity procedures. Data labels indicate total number who responded. Of respondents, >1% responded that BFR was utilized for the following pathologies: hip labrum repair, hip adductor repair, total knee arthroplasty, tibial tubercle osteotomy, osteochondral allograft transfer, cartilage repair, quadriceps tendon repair, ankle fracture open reduction and internal fixation.

Table 3.

Postoperative usage of BFR therapy.

	Yes	No
BFR Therapy Used for Postoperative Rehab	94.7% (144/152)	5.3% (8/152)
	Within 1st Week	1–2 Weeks	2–4 Weeks	1–2 Months	>2 Months
Amount of Time Post-op of BFR Therapy Initiation	8.3% (12/144)	27.1% (39/144)	36.8% (53/144)	22.9% (33/144)	4.9% (7/144)
	< 1 Month	1–3 Months	3–6 Months	6 Months-1 Year	>1 Year
Total Duration of BFR Therapy Post-op	10.4% (15/144)	60.4% (87/144)	22.9% (33/144)	5.6% (8/144)	0.7% (1/144)
	Improved Muscle/Limb Strength	Improved Extremity Function	Quicker Return to Sport	Less Patient Reported Pain	Improved Joint Stability	None	Other
Perceived Benefits of BFR Therapy	93.1% (134/144)	48.6% (70/144)	31.3% (45/144)	16.7% (24/144)	13.9% (20/144)	2.8% (4/144)	7.6% (11/144)

Other: Less fibrosis, decreased atrophy, quicker return of limb function, improved patient satisfaction, increased muscle girth.

Only 37.9% of physicians reported using BFR for upper extremity pathology. For those prescribing BFR for UE procedures, 20.7% utilized the technique after distal biceps repair, 20.0% after UCL elbow reconstruction/repair, 17.9% after rotator cuff repair, and 16.4% after shoulder labrum repair.

The majority of physicians (66.4%) use BFR therapy for non-operative rehab as well. Fig. 2 illustrates the most common non-operative injuries where BFR therapy was utilized.

Fig. 2.

Distribution of injuries in the non-operative setting utilizing BFR therapy. Data labels indicate total number who responded.

Contraindications to initiating BFR therapy were cited by 88.8% of providers. The four most common contraindications were peripheral vascular disease (75.0%), lymphedema (72.4%), neuropraxia or nerve injury (68.4%), and history of deep vein thrombosis (DVT) (68.4%) (Table 2). Despite this, 99.3% of physicians responded that no patients have been diagnosed with a DVT due to initiation of BFR therapy.

4. Discussion

The present study surveyed orthopaedic surgeons and assessed practice patterns relating to the use of BFR therapy. Nearly 60% of surveyed orthopedic surgeons are prescribing BFR therapy, with adoption occurring in the past 1–5 years. The most common indications were for rehabilitation after ACL reconstruction (Fig. 1). Surveyed physicians indicated that BFR therapy was also utilized in the non-operative setting, with patellofemoral instability cited as the most common indication (Fig. 2). Finally, there is emerging interest with 33.3% of those not currently using BFR therapy intending to implement its use in the future.

The wide-ranging application of BFR therapy found in our study has been demonstrated in previous literature, with a predominance of use in ACLR.^3,22 A systematic review by Charles et al. found that BFR, in combination with low intensity training, can lead to statistically significant increases in quadriceps muscle cross sectional area after ACLR.³ Similarly, Ohta et al. found that patients who underwent BFR therapy after ACLR had larger quadriceps cross-sectional area and increased knee extension and flexion strength at 16 weeks post-op compared to those without BFR therapy.²² In contrast, the RCT by Curran et al. found no significant difference in the change from baseline isokinetic quadriceps symmetry in 36 patients utilizing post-op BFR therapy after ACLR.²³ This disparity in findings points to the need for further study on the application of BFR therapy in post-ACL reconstruction patient populations.

While our study found ACLR as the most common application, a variety of other injury indications were reported, many of which have described benefits in the literature. Hughes et al. systematically reviewed BFR therapy and its effect on musculoskeletal rehabilitation across patients undergoing ACLR, with knee osteoarthritis, osteopenia, and sporadic inclusion body myositis.²⁴ Their group found increases in maximal isometric and isokinetic strength, increases in muscle cross sectional area, and improvements in functional testing such as reaction time and timed up and go tests. Tennent et al.‘s RCT also found significant increases in thigh girth, timed stair ascent, and strength with utilization of BFR after knee arthroscopy.¹² Additionally, a recent case report of a 59-year-old male utilizing BFR therapy for quadriceps muscle atrophy six months after total knee arthroplasty found improvements in functional tests, muscle mass, and quadriceps strength.²⁵ Overall, the utilization of BFR therapy provides potential benefits across a diverse range of patient populations.

Notably, while the applications of BFR therapy are wide-ranging, the benefits of BFR therapy as previously documented in the literature are equally multi-faceted. Many physicians in the current investigation cite increases in muscular strength as the main perceived benefit of BFR therapy, but there is growing research suggesting benefits beyond muscular hypertrophy. Ferraz et al. found that the benefits of BFR include increased muscular strength, muscle mass, and functionality.²⁶ Similarly, Alvarez et al. found improvements in strength, quadriceps cross-sectional area, and improved pain perception.⁹ While the majority of studies regarding BFR therapy are in the context of lower extremity pathology, Dankel et al., in a systematic review, found benefits in muscle groups located both proximally (in the chest and shoulders) and distally (biceps and triceps) to the occlusive device in the upper extremity, with increases in isometric contraction as well as hypertrophy.¹⁸ Similarly, Lambert et al. found improvements in proximal shoulder and arm lean mass and strength when utilizing distal BFR in conjunction with low-intensity resistance training.²⁷ BFR has also been shown to improved pain scores in patients suffering from anterior knee pain¹⁴ as well as improve patient reported outcomes following ACL reconstruction.²⁸ As further investigations are performed, new benefits of BFR therapy continue to emerge.

As a relatively new therapeutic technique, there is no standardized protocol for the application of BFR therapy. A survey study by Patterson et al. found that 43.4% of physicians use a preset occlusion pressure based on previous literature, 19.5% based on limb circumference, 19.5% on the patient's blood pressure, while 11.5% use a percent occlusion in the application of BFR therapy.²⁹ Their group also found that, on average, BFR therapy was applied in 10 min intervals 1–4 times per week. However, Erickson et al. utilized a protocol with 20-min BFR therapy sessions for 4 weeks and occlusion pressure followed manufacturer's guidelines.³⁰ Hughes et al., in a similar RCT of patients who underwent ACL reconstruction, included machines that tailored occlusion pressure to 80% of the participants' arterial blood pressures automatically.²⁸ The participants in this study completed 8 weeks of post-operative resistance training that consisted only of unilateral leg presses. While these studies applied BFR therapy with varying protocols, they both found benefit in muscle hypertrophy, strength, and pain reduction. This heterogeneity of protocols for BFR therapy is reflected in our results with varying durations of BFR therapy in the post-operative period and different start times post-operatively (Table 3). We found that 53.5% of physicians surveyed utilized a set percentage of occlusion pressure when using BFR therapy, while others used a standard pressure or had physical therapists determine the pressure used. As the applications of BFR therapy continue to be explored, more research is warranted to determine the optimal protocol for BFR therapy depending on the surgery performed or injury addressed.

Concerns have been raised about the safety of vascular occlusion, especially in postoperative patients and those with various comorbidities. Our study, however, found that 99.3% of responding physicians denied any incidence of DVT in their practice after initiating BFR therapy. These findings are consistent with previous literature which has demonstrated the safety of BFR therapy. In a systematic review, Minneti et al. studied the safety of BFR training for patients with musculoskeletal disorders and found that 9/13 included studies reported no adverse events.²⁰ Only three studies reported rare adverse events such as deep vein thrombosis and rhabdomyolysis.²⁰ No correlation between BFR therapy and adverse events were found. Similarly, Bowman et al. and Tennent et al. did not report any adverse events in their clinical trials.^1,12 While the theoretical concerns have been proposed about BFR therapy, the current body of literature has consistently demonstrated that this form of therapy can be performed safely.

5. Limitations

The nature of a survey study is inherently limited by response bias. Those who responded may represent a spectrum of orthopaedic surgeons who are more likely to have used BFR therapy or are more interested in its use. Furthermore, while attempts were made to create a concise, quick survey with multiple reminders, the overall response rate of 7.6% was low, and as such this cross-sectional data may not accurately reflect the true prevalence of practice patterns. In addition, the goal of the present study was to survey current practice patterns of BFR therapy. Our study is limited in making conclusions regarding optimal patient selection or protocol design. The survey tool inherently limits the amount of detail a respondent provides. Future studies are required to investigate optimal patient selection and compare therapy protocols in terms of cuff pressures used, timing of therapy, and specific exercises performed.

6. Conclusion

Blood flow restriction therapy has become an increasingly popular rehabilitation technique after common orthopedic sports procedures and injuries. Most surgeons began using BFR in the last 5 years. BFR therapy is most commonly used for lower extremity injuries, especially after ACL reconstruction.

Funding/sponsorship

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Institutional ethical committee approval

This research was approved by the institutional review board.

Author contributions

JC, JT, ET, DC, AM, and MA were involved with study creation and literature review. MG along with all other authors were involved with data acquisition and analysis. AM and MG were responsible for formatting the manuscript for publication. All authors contributed towards detailing the statistical analysis, analysing the results, and synthesizing tables and figures as well as drafting the manuscript. All authors contributed to multiple revisions of the manuscript. All authors read and approved the final manuscript. TL and VM are the attending physicians who approved each step of the study, reviewed the literature cited, statistical analysis, drafting and editing the final manuscript, and provided mentorship throughout the study.

Declaration of competing interest

There are no conflicts of interest to report.

Appendix A. Supplementary data

The following is the Supplementary data to this article: