- This study compared two strategies for preserving full-thickness chondral flaps during hip arthroscopy: (1) microfracture, and (2) the use of bone marrow aspirate concentrate to bridge the chondral flap to the subchondral bone
- Both the microfracture and bone marrow aspirate concentrate (BMAC) cohorts experienced significant improvements in International Hip Outcome Tool–33 (iHOT-33) scores from baseline to the 12-month follow-up visit
- However, the BMAC cohort outperformed the microfracture cohort at 12 months, in terms of raw score and improvement at a clinically meaningful level on iHOT-33 scores and other patient-reported outcome measures
- BMAC is a novel treatment strategy for this indication (used by the senior surgeon since December 2018), and long-term follow-up is needed to determine whether improvement is sustained
In some young, active patients with combined femoroacetabular impingement (concomitant cam and pincer lesions), the acetabular cartilage completely ruptures from the underlying subchondral bone. This can progress centrally to form a full-thickness, "outside-in" chondral flap. The optimal arthroscopic treatment is under debate.
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Since December 2016, Scott D. Martin, MD, director of the Joint Preservation Service in the Sports Medicine Center at Massachusetts General Hospital, has used bone marrow aspirate concentrate (BMAC) to bridge the chondral flap to subchondral bone. His previously used treatment strategy, microfracture, has been suggested in some studies to weaken the underlying trabecular bone and increase the risk of later conversion to total hip arthroplasty.
Dr. Martin and colleagues, including several Mass General Sports Medicine fellows, report in The Orthopaedic Journal of Sports Medicine that BMAC shows promise for the treatment of full-thickness acetabular chondral flaps during hip arthroscopy.
The researchers included 81 adults (81 hips): 31 treated with microfracture between June 2014 and November 2016, and 50 treated with BMAC between December 2016 and April 2020. Demographics, preoperative and intraoperative characteristics were similar in the two cohorts, and all patients followed the same postoperative protocol.
Patients were included only if they completed the following patient-reported outcome measures (PROMs) before surgery and at the 12-month follow-up visit:
- International Hip Outcome Tool–33 (iHOT-33)
- Hip Outcome Score–Activities of Daily Living (HOS-ADL)
- Hip Outcome Score–Sports Subscale (HOS-Sport)
- Modified Harris Hip Score (mHHS)
- A visual analog scale (VAS) for pain
At baseline, iHOT-33 and VAS pain scores were similar in the two cohorts. HOS-ADL, HOS-SPORT and mHHS scores were significantly worse in the BMAC group.
Improvement from Baseline
In the BMAC cohort, all PROM scores improved significantly from baseline to the 12-month follow-up. In the microfracture cohort, significant improvements were seen in iHOT-33, mHHS and VAS pain.
Comparison Between Groups
At the 12-month follow-up visit, the BMAC group had better scores on every PROM:
- iHOT-33—65.1 for microfracture vs. 75.6 for BMAC (P=0.025)
- HOS-ADL—83.3 vs. 91.0 (P=0.032)
- HOS-Sport—62.4 vs. 72.3 (P=0.132)
- mHHS—78.3 vs. 87.2 (P=0.003)
- VAS pain—3.6 vs. 2.2 (P=0.012)
Clinically Meaningful Outcomes
Except for VAS pain, significantly greater percentages of the BMAC cohort than the microfracture group had 12-month improvement in PROMs that met thresholds for minimal clinically important difference (P=0.013).
The Results Are Preliminary
BMAC is a novel approach to the treatment of full-thickness chondral flaps. This study introduces it as an alternative to microfracture, which yielded significant improvements of its own. While BMAC was associated with superior 12-month functional outcomes, higher-level studies are needed to examine its long-term utility.
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