Blood Flow Restriction Training Using the Delfi System Is Associated With a Cellular Systemic Response

Blood Flow Restriction Enhances Recovery After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating neuromuscular and clinical outcomes of blood flow restriction (BFR) training after anterior cruciate ligament reconstruction (ACLR) compared with non-BFR rehabilitation protocols.

METHODS

A systematic review was performed in accordance with the 2020 Preferred Reporting Items for Systematic reviews and Meta Analyses guidelines by querying PubMed, MEDLINE, Scopus, the Cochrane Database for Systematic Review, and the Cochrane Central Register for Controlled Trials databases from inception through December 2023 to identify Level I and II RCTs evaluating outcomes of BFR training after ACLR compared with non-BFR rehabilitation. A meta-analysis was performed using random-effects models with standardized mean difference (SMD) for pain, muscle strength, and muscle volume, whereas mean difference was calculated for patient-reported outcome measures.

RESULTS

Eight RCTs, consisting of 245 patients, met inclusion criteria, with 115 patients undergoing non-BFR rehabilitation compared with 130 patients undergoing BFR after ACLR. Mean patient age was 27.2 ± 6.7 years, with most patients being male (63.3%, n = 138/218). The length of the BFR rehabilitation protocol was most commonly between 8 and 12 weeks (range, 14 days to 16 weeks). Most studies set the limb/arterial occlusion pressure in the BFR group at 80%. When compared with non-BFR rehabilitation, BFR resulted in significant improvement in isokinetic muscle strength (SMD: 0.77, P = .02, I2: 58%), International Knee Documentation Committee score (mean difference: 10.97, P ≤ .00001, I2: 77%), and pain (SMD: 1.52, P = .04, I2: 87%), but not quadriceps muscle volume (SMD: 0.28, P = .43, I2: 76%).

CONCLUSIONS

The use of BFR after ACLR led to improvements in pain, International Knee Documentation Committee score, and isokinetic muscle strength, with variable outcomes on the basis of quadriceps strength, volume, and thickness when compared with non-BFR rehabilitation.

LEVEL OF EVIDENCE

Level II, systematic review and meta-analysis of Level I and II studies.

Novel Orthobiologic Preparation and Regenerative Rehabilitation of a Complex Shoulder Injury in a Competitive Adolescent Female Athlete

Background

Platelet-rich plasma (PRP) and prolotherapy have resulted in promising outcomes in patients with various types of shoulder injuries. However, there is a lack of preliminary evidence supporting preparation of PRP production, timely application of these therapies and regenerative rehabilitation protocols. The purpose of this case report is to describe the distinct method including orthobiologic preparation, tissue-specific treatment and regenerative rehabilitation of an athlete with a complex shoulder injury.

Case Presentation

A 15y/o competitive female wrestler with a complex shoulder injury presented to the clinic after unsuccessful conservative rehabilitation. Unique methods were incorporated to optimize PRP production, specific tissue healing and regenerative rehabilitation. Multiple injuries required different orthobiologic interventions at different time frames, in order to promote optimal healing and stability of the shoulder.

Outcomes

The described interventions resulted in successful outcomes including pain, disability, full return to sport, and regenerative tissue healing confirmed with diagnostic imaging.

Level of Evidence

5.

Beneath the cuff: Often overlooked and under-reported blood flow restriction device features and their potential impact on practice-A review of the current state of the research

Training with blood flow restriction (BFR) has been shown to be a useful technique to improve muscle hypertrophy, muscle strength and a host of other physiological benefits in both healthy and clinical populations using low intensities [20%-30% 1-repetition maximum (1RM) or <50% maximum oxygen uptake (VO_2max)]. However, as BFR training is gaining popularity in both practice and research, there is a lack of awareness for potentially important design characteristics and features associated with BFR cuff application that may impact the acute and longitudinal responses to training as well as the safety profile of BFR exercise. While cuff width and cuff material have been somewhat addressed in the literature, other cuff design and features have received less attention. This manuscript highlights additional cuff design and features and hypothesizes on their potential to impact the response and safety profile of BFR. Features including the presence of autoregulation during exercise, the type of bladder system used, the shape of the cuff, the set pressure versus the interface pressure, and the bladder length will be addressed as these variables have the potential to alter the responses to BFR training. As more devices enter the marketplace for consumer purchase, investigations specifically looking at their impact is warranted. We propose numerous avenues for future research to help shape the practice of BFR that may ultimately enhance efficacy and safety using a variety of BFR technologies.

The Current Role of Biologics for Meniscus Injury and Treatment

PURPOSE OF REVIEW

There is little doubt that the consensus has changed to favor preservation of meniscal function where possible. Accordingly, the indications for meniscal repair strategies have been refocused on the long-term interest of knee joint health. The development and refinements in surgical technique have been complemented by biological augmentation strategies to address intrinsic challenges in healing capacity of meniscal tissue, with variable effects.

RECENT FINDINGS

A contemporary approach to meniscal healing includes adequate surgical fixation, meniscal and synovial tissue stimulation, and management of the intraarticular milieu. Overall, evidence supporting the use of autogenous or allogeneic cell sources remains limited. The use of FDA-approved medications to effect biologically favorable mechanisms during meniscal healing holds promise. Development and characterization of biologics continue to advance with translational research focused on specific growth factors, cell and tissue behaviors in meniscal healing, and joint homeostasis. Although significant strides have been made in laboratory and pre-clinical studies, translation to clinical application remains challenging. Finally, expert consensus and standardization of nomenclature related to orthobiologics for meniscal preservation will be important for the advancement of this field.

Blood Flow Restriction Training for Subacromial Pain: Two Case Reports

BACKGROUND

Blood flow restriction training (BFRT) appears to promote the strengthening of shoulder muscles, but primary clinical applications are limited to the lower extremity.

CASE PRESENTATION

Two female recreational athletes (Case A: 27 years old; Case B: 28 years old) with subacromial pain were treated with BFRT (50% occlusion) during 3 isotonic strengthening exercises of the upper extremity against 20% of the maximal isometric strength. At the beginning of each treatment week, we measured strength with a handheld dynamometer to ensure appropriate load progression.

OUTCOME AND FOLLOW-UP

Case A completed 16 visits and Case B completed 22 visits of BFRT with no adverse events. At discharge, we found meaningful improvement for patient-reported function, clinical measures of shoulder flexion and external-rotation range of motion and isometric strength, supraspinatus and infraspinatus cross-sectional area, and upper extremity performance.

DISCUSSION

BFRT may be a valuable adjunct to standard rehabilitation for the conservative management of subacromial pain. Despite the inherent limitations of our design, we believe these preliminary findings are compelling to warrant future investigations.

Elevation of Peripheral Blood CD34+ and Platelet Levels After Exercise With Cooling and Compression

Purpose

To analyze the cellular response and chemokine profiles following exercise using cooling and blood flow restriction on the Vasper system.

Methods

Healthy male patients between the ages of 20 and 39 years were recruited. Testing was performed on the Vasper system, a NuStep cross-trainer with concomitant 4-limb venous compression with proximal arm cuffs at 40 mm Hg and proximal leg cuffs at 65 mm Hg. A cooling vest and cooling mat (8.3°C) were used. A 7-minute warm-up followed by alternating 30- and 60-second sprints with 1.5 and 2 minutes of active recovery, respectively, between each sprint. Peripheral blood was drawn before exercise, immediately following exercise (T20), 10 minutes after the first post-exercise blood draw (T30), and then every 30 minutes (T60, T90, T120, T150, T180). A blood draw occurred at 24 hours’ postexercise. Complete blood count, monoclonal flow cytometry for CD34+, and enzyme-linked immunosorbent assay were used to analyze the samples.

Results

Sixteen healthy male patients (29.5 ± 4.5years, 1.78 ± 0.05m, 83.7 ± 11.4 kg) were enrolled. There was an immediate, temporary increase in white blood cell counts, marked by an increase in lymphocyte differential (38.3 ± 6.5 to 44.3 ± 9.0%, P = .001), decrease in neutrophil differential (47.8 ± 6.6 to 42.0 ± 9.1%, P < .001), and platelets (239.5 ± 57.2 to 268.6 ± 86.3 K⋅μL^–1, P = .01). Monocytes significantly decreased from PRE to T90 (9.8 ± 1.1 to 8.9 ± 1.1K/μL, P < .001) and T120 (8.9 ± 1.1 K/μL, P < .0001). There was a significant increase in CD34+ cells (3.9 ± 2.0 to 5.3 ± 2.8 cells⋅μL^–1, P < .001). No detectable differences in measured cytokine levels of interleukin (IL)-10, IL-6, granulocyte-macrophage colony-stimulating factor , IL-1ra, tumor necrosis factor-α, or IL-2 were observed.

Conclusions

A significant elevation of peripheral blood CD34+ and platelet levels immediately following the exercise session was observed; however, there was no effect on peripheral circulation of IL-10, IL-6, IL-1ra, tumor necrosis factor-α, or IL-2.

Clinical Relevance

Exercise can be considered as a way to manipulate point-of-care blood products like platelet-rich plasma and may increase product yield.