Osteoarthritis (OA) is a prevalent and debilitating disease which is characterized by loss of articular cartilage, osteophyte (bony inclusions into cartilage) formation, pain, stiffness, and swelling.

The exact cause of OA is unknown. Many mechanical risk factors are associated with OA, but it is not clear which specific mechanical factors influence its initiation and progression. One such risk factor is varus knee alignment where the medial side of the knee appears to transmit a greater fraction of the joint load than it would normally, causing medial tibiofemoral (TF) OA.

High tibial osteotomy (HTO), which realigns the leg, is one treatment for medial TF OA. Although the clinical results of HTO are mixed, many researchers have reported repair cartilage growth following HTO. This dramatic finding suggests that certain mechanical environments may prevent, delay, or reverse cartilage degeneration. Many authors suggest a range of varus/valgus angular correction, however achieving this correction does not guarantee good results. One explanation for this is that simple alignment may not describe the mechanics of the joint sufficiently well, and that a three-dimensional method may be required.

With the aim of examining the changes caused by HTO, we developed a method for measuring three-dimensional knee kinematics with loading using MR at 3T. We determined that our method successfully measures knee kinematics in subjects with and without hardware, despite the larger metal artifact expected at a field strength of 3T compared to 1.5T.

We also developed a method for measuring cartilage health using MR at 3T, based on the dGEMRIC protocol and determined that our dGEMRIC sequence yields valid results in the presence of titanium surgical hardware. This important development will allow us to evaluate the effect of surgical kinematic changes on cartilage health, specifically in the case of the high tibial osteotomy procedure.

These protocols were tested on three subjects scheduled for high tibial osteotomy. Both kinematic and cartilage GAG concentration results were consistent with values from literature. These newly developed protocols will allow us to study relationships between knee kinematics and cartilage GAG concentration changes as a result of high tibial osteotomy and other surgical procedures.