State of the mineralized tissue comprising the femoral ACL enthesis in young women with an ACL failure

Patton, Daniella M.; Ochocki, Danielle N.; Martin, Colin T.; Casden, Michael; Jepsen, Karl J.; Ashton-Miller, James A.; Wojtys, Edward M.; Schlecht, Stephen H.

Affiliations

¹Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, USA

²Department of Biomedical Engineering, Ann Arbor, Michigan, USA

³Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA

⁴Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA

⁵School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA

⁶Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, USA

Abstract and keywords

Despite poor graft integration among some patients that undergo an anterior cruciate ligament (ACL) reconstruction, there has been little consideration of the bone quality into which the ACL femoral tunnel is drilled and the graft is placed. Bone mineral density of the knee decreases following ACL injury. However, trabecular and cortical architecture differences between injured and non-injured femoral ACL entheses have not been reported. We hypothesize that injured femoral ACL entheses will show significantly less cortical and trabecular mass compared with non-injured controls. Femoral ACL enthesis explants from 54 female patients (13–25 years) were collected during ACL reconstructive surgery. Control explants (n = 12) were collected from seven donors (18−36 years). Injured (I) femoral explants differed from those of non-injured (NI) controls with significantly less (p ≤ 0.001) cortical volumetric bone mineral density (vBMD) (NI: 736.1–867.6 mg/cm3; I: 451.2–891.9 mg/cm3), relative bone volume (BV/TV) (NI: 0.674–0.867; I: 0.401–0.792) and porosity (Ct.Po) (NI: 0.133–0.326; I: 0.209–0.600). Injured explants showed significantly less trabecular vBMD (p = 0.013) but not trabecular BV/TV (p = 0.314), thickness (p = 0.412), or separation (p = 0.828). We found significantly less cortical bone within injured femoral entheses compared to NI controls. Lower cortical and trabecular bone mass within patient femoral ACL entheses may help explain poor ACL graft osseointegration outcomes in the young and may be a contributor to the osteolytic phenomenon that often occurs within the graft tunnel following ACL reconstruction.

Keywords: ACL injury; Bone; femoral ACL enthesis; time-from-injury

Links

DOI: 10.1002/jor.25130

PubMed: 34191360

WoS: 000671743700001

History

Received: 2019-09-26

Revised: 2021-01-14

Accepted: 2021-06-09

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