A study of the relationship between meniscal injury and bone microarchitecture in ACL reconstructed knees.

Background: Anterior cruciate ligament (ACL) tears increase the risk of developing knee osteoarthritis. This risk increases further with concurrent meniscus injury. The role of bone changes during knee osteoarthritis development are not well-understood, but may be important to its etiology.

Purpose: To explore the effects of ACL tears on bone mineral density (BMD) and bone microarchitecture at five years post-op and their relationship to meniscal pathology, using high-resolution peripheral quantitative computed tomography (HR-pQCT).

Methods: Twenty-eight participants with unilateral ACL reconstructions five years prior and no evidence of clinical or radiographic osteoarthritis were recruited. All participants represented one of three meniscus statuses: meniscus intact, meniscus repair, or meniscectomy. BMD and bone microarchitecture of the subchondral bone plate and adjacent trabecular bone were assessed using HR-pQCT, and percent-differences between the injured and contralateral knee were determined.

Results: Subchondral bone plate thickness in the lateral femoral condyle was higher in the reconstructed knee (9.0%, p = 0.002), driven by the meniscus repair and meniscectomy groups (15.2% to 15.4%, p < 0.05). Trabecular BMD was lower in the reconstructed knee in the medial femoral condyle (-4.8% to -7.6%, p < 0.05), driven by all meniscus statuses. In the lateral compartments, few differences in trabecular bone were found. However, accounting for meniscus status, the meniscus intact group had lower trabecular BMD throughout both femur and tibia.

Conclusions: Five years post-op, reconstructed knees demonstrated detectable differences in BMD and bone microarchitecture, despite having normal radiographs. Meniscus damage affected primarily the lateral compartment, warranting further investigation to determine if these changes relate to osteoarthritis development.