Femoral Head Chondrocyte Viability at the Cam Deformity in Patients With Femoroacetabular Impingement Syndrome

Background: Patients with hip pathology, such as femoroacetabular impingement (FAI) or hip dysplasia, are known to sustain chondral delamination injuries identifiable during hip arthroscopy, with an incidence of 44% to 75%. There are studies focused on understanding acetabular chondral flap viability, but there is a dearth of research regarding the viability of femoral head cartilage overlying the cam deformity in FAI.

Purpose: To describe the viability and immunohistochemistry staining patterns of femoral head cartilage in the setting of FAI.

Study design: Descriptive laboratory study.

Methods: Between September 2018 and August 2019, a single surgeon prospectively collected full-thickness femoral cartilage from cam deformities in 14 patients with FAI undergoing osteoplasty. Samples were assessed for viability and underwent immunohistochemistry staining for collagen type I, collagen type II, and aggrecan.

Results: The data set included 14 patients. Twelve samples were assessed for viability and 14 for immunohistochemistry straining. The mean patient age was 34.1 years, and the mean body mass index was 24.69. Mean ± SD chondrocyte viability per patient was 52% ± 11%. At the time of cell isolation, 8 of the 12 patients had viability >50%, with a maximum of 68.2%. This viability increased after a primary culture period, varying from 9 to 13 days, with 10 of 12 samples having viability >90%. The viability mean after the culture period was 94.54% ± 4.89%. Harvested cartilage showed expressions of type I cartilage, type II collagen, and aggrecan in a pattern that is predictable for native cartilage.

Conclusion: These data reveal that the cartilage in femoral head cartilage overlying cam deformity-much like that from acetabular chondral flaps-not only has baseline viability >50% (51.99% ± 10.83%) but the ability to increase in viability >90% after a culture period. There may be a role for use of femoral head cartilage as autograft to repair full-thickness cartilage defects of the acetabulum and femoral head, either at the time of osteochondroplasty or after a period of cell culture to improve cell viability.

Clinical relevance: A dearth of information is available regarding the viability of femoral head cartilage. This study provides insight into the cartilage viability and response to culture.

Keywords: cam deformity; femoral head cartilage; femoral head cartilage viability; femoral head chondral flap; femoroacetabular impingement.