- Most cell-based cartilage repair techniques have limited application in the hip
- An orthopedic surgeon at Massachusetts General Hospital has developed a method for applying bone marrow aspirate concentrate to the chondrolabral surface of the hip during arthroscopy
- The technique does not prolong labral repair and avoids donor-site morbidity, open procedures and multiple surgeries
- Careful placement of the aspiration needle is paramount
Thanks to technical advances, the use of hip arthroscopy to treat acetabular labral tears has increased substantially, potentially reducing the morbidity of hip osteoarthritis. It has proved much more difficult, though, to minimize or reverse damage to the chondrolabral junction.
The use of bone marrow aspirate concentrate (BMAC) has shown promise for treating chondral damage in the knee, but until recently, no reliable technique had been reported for managing chondrolabral junction breakdown in the hip. In Arthroscopy Techniques, Scott D. Martin, MD, director of the Joint Preservation Service within the Department of Orthopaedics Sports Medicine Center at Massachusetts General Hospital, describes a reproducible method for harvesting, processing and applying BMAC to the chondrolabral surface at a single site during hip arthroscopy that removes the need for open surgery or multiple procedures.
The Surgical Technique
Dr. Martin's paper describes the technique in detail. Briefly, the steps are:
- Centrifuge venous whole blood simultaneously with labral repair to avoid adding time to the procedure
- After labral repair, establish a central anterior portal for the bone marrow aspiration needle, superior to the midanterior portal and directly between the anterior and anterolateral portals. While working through the central anterior portal and viewing through the anterolateral portal, identify the needle insertion site on the ilium, about 1 to 2 cm proximal to the superior suture anchors
- Place a 15-gauge bone marrow aspiration needle 60° to the ilium surface, and verify its location by direct visualization and fluoroscopy before insertion
- Drive the needle through the bone's cortex by tapping its handle with a mallet; confirm its trajectory with fluoroscopy
- Aspirate about 20–25 mL of bone marrow into three separate 60-mL syringes, for a total yield of about 60–75 mL
- Inject the BMAC into a processing centrifuge for separation of stem cells; spin time should be about 15 minutes. Perform this step concurrently with the final stages of surgery to avoid increasing surgical and traction times
- When centrifugation is complete, use aseptic technique to draw about 4 mL of platelet-rich plasma and 16 mL of platelet-poor plasma into a 20-mL syringe and inject it into a sterile cup
- Aseptically draw about 3 mL of BMAC into a syringe and inject it into the sterile cup
- Aseptically draw the contents of the sterile cup into a 30-mL syringe. About 3–5 minutes before the time for applying BMAC to the chondrolabral junction, add about 7 mL of thrombin to the syringe. A clotting cascade will begin, forming a sticky megaclot in the syringe
- Apply the megaclot to the chondrolabral junction and labral repair site while maintaining slight traction. Once traction is released, visualize the megaclot and repair site while flexing the patient's hip from 0 to 45°
After surgery, the patient is followed with standard protocols.
Comparison of the BMAC Technique to Others
Dr. Martin notes that other cell-based cartilage implantation techniques, such as autologous chondrocyte implantation (ACI), matrix-induced ACI and osteochondral autograft transfer, have been successful in the knee. In the hip, however, they have limited application because of the technical difficulties of the joint and the increased morbidity of open procedures. Also, ACI and matrix-induced ACI require multiple procedures that significantly lengthen cartilage repair time.
Furthermore, Dr. Martin explains, these techniques involve only the harvest of hyaline cartilage, whereas the chondrolabral junction of the hip consists of both hyaline cartilage and fibrocartilage. The mesenchymal stem cells in BMAC can differentiate into both types of tissue.
Microfracture is another way to introduce mesenchymal stem cells to chondral defects. In that technique, subcortical bone is disrupted, which allows mesenchymal stem cells to clot along cartilage defects. However, subchondral bone disruption at the weight-bearing portion of the joint can accelerate cartilage degeneration.
Importance of Needle Position
The BMAC technique does have some risks:
- Neurovascular injury
- Pelvic cavity compromise from improper placement of the bone marrow aspiration needle
Dr. Martin emphasizes that careful needle position is crucial for reducing procedural risk and optimizing bone marrow aspiration.
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