['The pathogenesis of osteoarthritis (OA) is not fully understood, but bone changes are suggested to be important. Bone turnover and bone volume (BV) in human hip OA were investigated in relation to the overlying cartilage degeneration using design-based stereological estimators.', 'Femoral heads were obtained from 25 end-stage OA patients and 24 controls (CTL). Design-based stereological methods were used for sampling and quantification to obtain absolute estimates of volume and surface in the central trabecular and the subarticular bone region. The subarticular bone was further subdivided into regions according to the OARSI-score of the overlying articular cartilage in which erosion and osteoid surfaces were estimated.', 'In the subarticular region, bone volume (BV/TV) was 15.0% higher in OA patients compared to CTL; The fraction of erosive (ES/BS) and osteoid surfaces (OS/BS) were 56.2% and 72.8% higher in OA compared to CTL. In subarticular regions with none to mild cartilage degeneration (OARSI grade 0-2), ES/BS and OS/BS were 48.6% and 59.9% higher in OA compared to CTL, whereas BV/TV did not differ between OA and CTL.'] Is subchondral bone turnover , but not bone volume , increased in early stage osteoarthritic lesions in the human hip joint?