The purpose of this study is to discuss the mechanical function of subchondral bone cysts and its relationship with Wolff's law.
One hundred forty symptomatic knees (120 patients) with osteoarthritis were subjected to MRI before high tibial osteotomy (HTO). Subchondral bone cysts (SBCs) were detected on 72 knees of these 140 knees. SBCs, bone marrow lesion (BML), and hip-knee-ankle (HKA) axis were measured by using validated methods. After HTO, the evolution of cysts was evaluated on MRI performed with a five year follow-up on the 72 knees with pre-operative cysts.
At baseline, 70 (97%) of these 72 knees had a BML surrounding the SBCs; the maximum cyst volume was 874 mm
Regression of subchondral bone cysts may be related to restoration of an appropriate load at the subchondral bone. With applying poroelasticity to bone mechaincs, this finding may suggest that SBCs and BMLs may be a physiological adaptation to mechanic overload. More basic research is needed to prove this matter.