Subchondral Bone Cyst Development in Osteoarthritis: From Pathophysiology to Bone Microarchitecture Changes and Clinical Implementations

Abstract

Osteoarthritis is a degenerative joint disease affecting middle-aged and elderly patients. It mainly involves weight-bearing joints such as the hip, knee and spine as well as the basilar joint of the thumb, causing dysfunction and painful symptoms. Often, joint arthritis is accompanied by cartilage defects, joint space narrowing, osteophytes, bone sclerosis and subchondral bone cysts (SBC). The aim of the present study was to explore the pathophysiology responsible for the development of SBCs as well as the association between SBCs and disease progress, the level of clinical symptoms and their impact on postoperative outcomes and risk of possible complications following joint replacements if left untreated. A literature review on PubMed articles was conducted to retrieve and evaluate all available evidence related to the main objective mentioned above. A few theories have been put forth to explain the formation process of SBCs. These involve MMPs secretion, angiogenesis, and enhanced bone turnover as a biological response to abnormal mechanical loads causing repeated injuries on cartilage and subchondral tissue during the development of arthritis. However, the application of novel therapeutics, celecoxib-coated microspheres, local administration of IGF-1 and activated chondrocytes following surgical debridement of SBCs hinders the expansion of SBCs and prevents the progression of osteoarthritis.

Keywords: angiogenesis; bone turnover; cartilage; osteoarthritis; subchondral cyst.

Figure 1

PRISMA flow chart.

Figure 2

Representative immunohistological photomicrographs of subchondral bone cysts (SBCs) in sections of osteoarthritis patients. Note the thin layer of fibrous connective tissue covered by lining cells and osteoblasts. (A) Small-sized SBCs (red arrows) in the section of a patient with Mankin score 3 (original magnification × 10). (B) Large SBCs containing fibrous tissue surrounded by osteoblasts in the section of a patient with a Mankin score of 8 (original magnification × 10). (C) SBCs in a slice from a patient with a Mankin score of 7 (original magnification × 10). (D) Bone lining cells covering the cavity of a large SBC in a patient with a Mankin score of 8 (original magnification × 20).

Figure 3

Intraoperative image during total knee arthroplasty demonstrating the gross appearance of a large subchondral bone cyst (yellow arrow). The remaining holes are the result of the femur and tibia preparation before implantation.

Figure 4

(A) Pre-operative anteroposterior radiograph of an osteoarthritic knee displaying the characteristic appearance of a subchondral bone cyst (red arrows). Note the sclerotic osseous margins (B): Postoperative lateral X-ray. After subchondral cyst excision, the gap was filled with cement.