Use of BMAC With Hip Arthroscopy Treatment of FAI and Labral Tear

Femoro-acetabular impingement is a well known cause of damage to the acetabular labrum and chondrolabral junction. Additionally, it has been proposed that disruption of hip biomechanics resulting from a labral tear causes a faster progression towards osteoarthritis (OA). This progression has been observed to begin with breakdown of the chondrolabral junction with later development of diffuse osteoarthritis. Use of hip arthroscopy has increased dramatically in recent years to treat symptomatic labral tears and potentially avoid the morbidity and cost associated with hip osteoarthritis.

Correction of labral pathology presents a technical challenge and many techniques currently exist. Increased understanding of the structure-functional relationship dictated by labral anatomy has led to the development of methods aimed at restoring functional anatomy by re-establishing the labrum's native position and contour on the rim of the acetabulum. Therefore, akin to repairing a torn meniscus in the knee, restoring the anatomic footprint of a torn labrum will reconstitute normal joint biomechanics.

Despite the advances in techniques for labral repair, strategies for mitigating or repairing damage to the chondrolabral junction do not yet exist. This area has been shown to consist of hyaline and fibro cartilage. Many techniques for cartilage repair exist, although most are not feasible due to technical challenges specific to the hip joint.

The management of articular cartilage defects is one of the most challenging clinical problems for orthopaedic surgeons. Articular cartilage has a limited intrinsic healing capacity, and pathology frequently results in gradual tissue deterioration. Currently, the standard surgical intervention for end-stage degenerative joint pathology is total joint replacement. Early surgical interventions for symptomatic cartilage lesions including cell based therapies such as autologous chondrocyte implantation (ACI), bone marrow aspirate concentrate (BMAC) implantation, or microfracture have been suggested to restore normal joint congruity and minimize further joint deterioration. Techniques such as ACI, which have been successfully used in the knee joint, have limited application in the hip due to the technical difficulties of open procedures.

The acetabular labrum is a wedge shaped fibrocartilage structure attached to the acetabular rim. It is continuous with the transverse acetabular ligament at the inferior aspect of the acetabulum. The medial aspect of the labrum abuts the acetabulum to form the chondrolabral junction.

Anatomic labral refixation aims to preserve healthy tissue and restore native joint anatomy and biomechanics. Labral tears that are caused by Femoro-Acetubular Impingement (FAI) require concomitant correction of bony cam lesions, pincer lesions, or both to prevent reinjury of the labrum. However, repair has not yet been proven to mitigate the osteoarthritic accelerating effects of labral tears. Many patients presenting with hip pain in the third and fourth decade of life already have osteoarthritic changes seen at the time of arthroscopy. Restoring the biomechanics of the joint via labral repair does not reverse this damage and investigating methods to repair early osteoarthritis is important to the future of hip arthroscopy.

Bone marrow aspirate concentrate (BMAC) has been used effectively in many joints for the management of chondral defect repair. As an alternative to the aforementioned chondral treatment modalities, BMAC treatment does not require multiple procedures or additional waiting time for treatment completion.

Within the technical constraints of the hip joint, bone marrow aspirate concentrate is feasible and potentially efficacious option for the treatment of chondral defects. Late stage hip osteoarthritis is a known factor implicated in poor outcomes in both the surgical and non-surgical treatment options available for chondral defect management. Preventing late stage hip osteoarthritis is paramount to decrease these poor outcomes and improve the patient's quality of life. Early and effective intervention with modalities that afford patients little to no drawbacks, like BMAC treatment, are necessary to achieve these goals.

This is a prospective study which will enroll 400 adult subjects with evidence of an acetabular labrum tear and pincer or cam deformity. Labral tears will be diagnosed by clinical exam and positive magnetic resonance arthrogram (MRA) findings. Pincer deformity is diagnosed with standard antero-posterior radiographs of the pelvis, and cam deformity is diagnosed with antero-posterior and lateral radiographs.

Administration of diagnostic modalities is independent of study protocol as they are routine standard of care. Upon diagnosis, eligible potential subjects will be approached for study enrollment. After consent, enrolled subjects will undergo arthroscopic labral repair using a capsular chondrolabral preservation technique with or without BMAC based on intra-operative findings. The decision to use BMAC is made intra-operatively; therefore the patients are consented for the BMAC prior to surgery. If the chondrolabral junction shows advanced arthritis or the absolute absence of wear the BMAC is unnecessary and not used. This surgery in the absence of BMAC is considered routine practice and standard of care. Subjects will follow-up at routine post-operative intervals of 3 months, 6 months, 12 months, and annually thereafter to monitor progress.

Interval Results:

Martin SD, Kucharik MP, Abraham PF, Nazal MR, Meek WM, Varady NH. Functional Outcomes of Arthroscopic Acetabular Labral Repair with and without Bone Marrow Aspirate Concentrate \[published online ahead of print, 2021 Oct 14\]. J Bone Joint Surg Am. 2021;10.2106/JBJS.20.01740. doi:10.2106/JBJS.20.01740

Eligibility Criteria:
Inclusion Criteria and Rationale:

1. Age 18 or older: patients of any age have the capacity to potentially benefit from labral repair
2. Symptoms consistent with a tear of the acetabular labrum (i.e., catching, clicking, popping, pain with sitting, episodic pain, pain with hip flexion, adduction, and/or internal rotation): asymptomatic labral tears do exist in the general population however there is not definitive evidence to suggest treatment of asymptomatic tears is beneficial.
3. Symptoms not due to some other acute process in or around the hip (including septic arthritis, osteonecrosis, hemarthrosis, iliotibial band syndrome, fractures of the femoral neck or head, fractures of the acetabulum, greater trochanteric pain syndrome, sacroiliac joint pain, piriformis syndrome, low back pain associated with hip pain and not knee nor acute low back injury): certain conditions are not treatable by either arthroscopy or physical therapy. Some of these conditions can be managed with physical therapy but not arthroscopy.
4. Availability of hip radiographs and magnetic resonance imaging (MRI and/or MRA): needed to assess eligibility
5. Evidence of labral tear on MRI and/or MRA: documentation of acetabular labrum tear
6. Willingness to participate and ability to understand and sign informed consent document: ability to understand study and consent willingly
7. Returning subjects enrolled in protocol 2017P001391/PHS

Exclusion Criteria and Rationale:

1. Non-English speaking subjects: PROMs are only validated in English.
2. Systemic infection: surgery is generally contraindicated when systemic infection is present.
3. Systemic heparinization: the vascularity of the bone and adjacent tissues is significant, posing a potential problem for bleeding when the patient is anti-coagulated.
4. Pregnant women/fetuses: although surgery can be performed on pregnant women, pregnant women are excluded under federal regulations.