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Published on: January 7, 2019
Significant Chondrocyte Viability Is Present in Acetabular Chondral Flaps Associated With Femoroacetabular
Vonda J Wright1, Christopher Laurence McCrum2, Hongshuai Li1
1Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
Insights
Acetabular chondral flaps from hip impingement patients show high viability, with 87% of cells alive immediately after biopsy. This finding supports using these flaps for innovative cartilage repair techniques.
Area of Science:
- Orthopedics
- Biomedical Engineering
- Cartilage Biology
Background:
- Femoroacetabular impingement (FAI) causes cartilage damage in the hip joint.
- Chondral delamination injuries are common in FAI patients undergoing hip arthroscopy.
- Conflicting data exists on chondrocyte viability in traumatic cartilage injuries.
Purpose of the Study:
- To determine the in vivo tissue viability of acetabular chondral flaps in FAI patients.
- To assess chondrocyte viability immediately after biopsy in the joint microenvironment.
- To hypothesize that acetabular chondral flaps contain a majority of viable chondrocytes.
Main Methods:
- Biopsy of partially detached cartilage flaps from 10 FAI patients during arthroscopic surgery.
- Minimally traumatic biopsy technique prior to chondroplasty and microfracture.
- Live/dead staining and confocal microscopy to quantify percentage of live cells.
Main Results:
- The overall proportion of live cells in acetabular chondral flaps was 85.8%.
- The average proportion of live cells per patient was 87% ± 10%.
- 6 out of 10 patients exhibited over 90% live cell viability.
Conclusions:
- Acetabular chondral flaps contain a high percentage of viable chondrocytes (approximately 87%) when analyzed immediately post-biopsy.
- These findings highlight the importance of laboratory techniques in assessing cell viability.
- High chondrocyte viability supports the use of these flaps for novel cartilage repair and replacement strategies.
Background:
Patients presenting with cam deformity of the femoral head and neck sustain repeated trauma to the articular cartilage of the superior acetabulum, with chondral delamination injuries found during hip arthroscopy. Two previous studies reveal conflicting chondrocyte viability data in these traumatic cartilage injuries. The full-thickness nature of flaps may suggest that chondrocytes residing in the cartilage flap matrix in the joint environment would remain viable despite shear trauma. Hypothesis/Purpose: The purpose of this study is to determine the in vivo tissue viability of acetabular chondral flaps in patients with femoroacetabular impingement (FAI) when samples are analyzed immediately after biopsy. We hypothesize that the majority of the tissue in acetabular chondral flaps is viable in the joint microenvironment.
Study Design:
Descriptive laboratory study.
Methods:
Partially detached cartilage flaps from 10 patients undergoing arthroscopic hip surgery for FAI were biopsied in a minimally traumatic manner before chondroplasty and microfracture. Samples were placed in cold Hank's Balanced Salt Solution without phenol red solution and immediately transported on ice to our laboratory. The edge of the samples was trimmed and further cut into 3 separate, 1-mm-thick sections. Sections were stained using a live/dead staining kit. Images were obtained with confocal microscopy, and the percentage of live cells was quantified.
Results:
Patients averaged 36 ± 11 years (range, 18-48 years), and 2 patients were female. The mean body mass index was 28.9 ± 5.6 kg/m2. The total proportion of live cells from all sections analyzed was 85.8%. The proportion of live cells per patient was 87% ± 10%.
Conclusion:
We determined that acetabular chondral flaps are approximately 87% live cells when analyzed immediately after biopsy, with 6 of 10 patients having greater than 90% live cells. These data point to the importance of laboratory techniques in making viability judgments in biologic systems.
Clinical Relevance:
Full-thickness cartilage loss is a difficult problem for all active people but particularly in the young population in whom joint preservation is key. We describe the viability of chondrocytes present in full-thickness acetabular-based chondral flaps encountered during hip arthroscopy. Identification of greater than 85% chondrocyte viability supports a foundation for evaluation and creation of novel clinical innovations for repair and replacement techniques using the flap as donor tissue, as alternatives to chondroplasty and microfracture.
