Long-term periarticular bone adaptation in a feline knee injury model for post-traumatic experimental osteoarthritis

Summary

Objectives

This study investigates the long-term changes of the periarticular bone, including cancellous bone and the subchondral plate, in an anterior cruciate ligament (ACL)-transected cat for post-traumatic osteoarthritis (OA). These periarticular bone changes are related to the health of all knee tissues including articular cartilage degeneration and may be a key component of osteoarthritic development.

Methods

Thirteen cats (mean mass 4.9 ± 1.9 kg) were divided into three experimental groups: (1) normal controls, (2) 16 week, and (3) 5 year post unilateral ACL-transection (ACLT). Micro-computed tomography was used to scan the three-dimensional (3D) bone architecture of the proximal tibia, and analysis was performed on the subchondral plate and cancellous bone in the epiphyseal and metaphyseal regions of each bone.

Results

A decrease in cancellous bone mass (BV/TV) and subchondral plate thickness (Ct.Th) was observed 16 week post-ACLT, and the trend was statistically significant for the long-term animals (>5 year post-ACLT: BV/TV decreased 16.8%, P < 0.003; Ct.Th decreased 36.8%, P < 0.03). A decrease in bone mass was also observed as a function of animal age by comparing the young and aged normal control animals, however ACLT intensified those changes, particularly Ct.Th (P < 0.009) and anisotropy (P < 0.045). It was speculated that decreased internal joint loading despite normal kinematics may play an important role in the long-term reduction of cancellous bone volume and subchondral plate thinning.

Conclusions

The periarticular bone changes measured in this study were concurrent with articular cartilage degeneration, and suggest that bone may be a contributing factor in the aetiology of post-traumatic OA development.