Effect of Platelet-Rich Plasma, Platelet-Poor Plasma, & Bone Marrow Aspirate Concentrate Application on Functional Outcomes Following Hip Arthroscopy for Acetabular Labral Pathologies: A Prospective Randomized Controlled Trial

1. Background Surgical management of labral pathology has evolved to reflect our current understanding of mechanism of injury and resulting hip dysfunction. Correction of labral pathology presents a technical challenge, and many techniques currently exist. Initial management of labral tears included complete resection or debridement to the bony acetabular surface of the affected region. This had the advantage of acutely reducing hip pain but was later shown by seminal biomechanical studies to compromise the mechanical integrity of the hip. With the exception of cases found to have profound degenerative changes to the labral and adjacent articular cartilage, labral resection/debridement has largely been replaced by techniques that emphasize labral tissue and blood flow preservation (i.e., repair, augmentation, reconstruction) due to a growing body of evidence reporting improved functional outcomes.

Repair techniques focus on restoring functional anatomy by re-establishing the labrum's native position and contour on the rim of the acetabulum. Similar to repairing a torn meniscus in the knee, restoring the anatomic footprint of a torn labrum will reconstitute normal joint biomechanics. Labral injuries are often seen in the setting of femoroacetabular impingement and are a common source of early symptomatology. Therefore, during labral repair, concomitant correction of bony cam lesions, pincer lesions, or both may be necessary to prevent reinjury of the labrum. Correction of cam and pincer lesions requires femoral neck osteoplasty (trimming of femoral neck) and acetabuloplasty (trimming of the bony acetabular rim), respectively.

Articular cartilage has limited intrinsic healing capacity and pathology frequently results in gradual and progressive tissue deterioration. Moreover, many patients presenting with hip pain in the third and fourth decade of life already have osteoarthritic changes observed at the time of arthroscopy. It has been proposed that altered biomechanics of the hip resulting from a labral tear can increase the stresses through the hip causing faster progression of cartilage wear. Moreover, previous literature has illustrated the significant association between patients with moderate to severe osteoarthritis undergoing hip arthroscopy and inferior postoperative outcomes when compared to similar patients with less osteoarthritis. Thus, while there have been notable advances in acetabular labral repair techniques, there continues to be demand for an innovation that can preserve the acetabular cartilage and chondrolabral junction in order to improve outcomes in these patients.

Recently, given the properties of the isolated components, bone marrow aspirate concentrate (BMAC) has gained attention for its theoretical potential to treat OA and slow the progression of cartilage deterioration. BMAC contains marrow elements including mesenchymal stromal cells (MSCs), platelets, red and white blood cells, and hematopoietic precursors. Bone-marrow derived platelets contain growth factors, cytokines, and chemokines, which can promote wound healing, collagen synthesis, suppression of pro-inflammatory cytokines, production of extracellular matrix, and chondrocyte proliferation. MSCs are multipotent, non-hematopoietic stromal cells with the capacity to self-renew, proliferate, and differentiate into cartilage, bone, or fat. Numerous tissue sources can be used to isolate MSC cells, including bone marrow, adipose tissue, synovial membrane, bursa, umbilical cord blood, and periosteum. Within orthopaedic procedures, bone marrow derived MSCs (BMSCs) have been reported to be an excellent source of MSCs and are often harvested from the iliac crest, distal femur, proximal humerus, and vertebrae.

Currently, the PI has adopted the use of a combined mixture of platelet-rich plasma (PRP), platelet-poor plasma (PPP), and BMAC that are harvested, processed, and applied during arthroscopic acetabular labral repair as his standard of care when encountering mild to moderate cartilage damage, chondrolabral junction breakdown, and isolated chondral lesions/flaps. Previous studies performed by the PI have demonstrated that harvesting bone marrow aspirate from the body of the ilium is not only a safe procedure, but also provides a concentration of connective tissue progenitor cells that is comparable to other harvest sites in the body. Furthermore, harvesting bone marrow aspirate from the body of the ilium concomitantly with arthroscopic acetabular labral repair is efficient, limits the harvesting and repair of the labrum to one procedure, and limits the procedure to only one procedural site. Regarding clinical outcomes, the PI recently published a foundational study that demonstrated that augmenting the acetabular labral repair site with bone marrow aspirate concentrate harvested from the body of the ilium resulted in significantly greater functional improvements in patients with moderate osteoarthritis compared to similar patients without BMAC application. Additionally, Kucharik et al. reported that patients with full-thickness chondral flaps treated with BMAC at the time of arthroscopic labral repair, compared to microfracture, experienced significantly greater improvements in functional outcomes at 12 months follow-up. Thus, demonstrating the possible benefits and potential of BMAC application during arthroscopic labral repair in the first randomized controlled trial (RCT) is necessary.