Bone Remodeling in Osteoarthritis-Biological and Radiological Aspects

Abstract

Among available papers published on the given subject over the last century, various terms have been used as synonyms for one, now generally accepted-osteoarthritis, in some countries called "wear and tear" or "overload arthritis". The opsolent terms-hypertrophic arthritis, degenerative arthritis, arthritis deformans and osteoarthrosis-sought to highlight the dominant clinical signs of this ubiquitous, polymorph disease of the whole osteochondral unit, which by incidence and prevalence represents one of the leading chronic conditions that cause long-term pain and incapacity for work. Numerous in vitro and in vivo research resulted in broadened acknowledgments about osteoarthritis pathophysiology and pathology on both histological and cellular levels. However, the cause of osteoarthritis is still unknown and is currently the subject of a hypothesis. In this paper, we provide a review of recent findings on biological phenomena taking place in bone tissue during osteoarthritis to the extent useful for clinical practice. Choosing a proper radiological approach is a conditio sine qua non to the early diagnosis of this entity.

Keywords: bone remodeling; osteoarthritis; osteophyte.

Figure 1

Sagittal X-ray of the pelvis and computerized tomography of the right hip (same patient). Severe right-sided coxarthrosis deformans. Grossly reduced joint space. Dense, sclerotic subchondral bone tissue of the deformed articular bodies interspersed with cyst-like transparencies of bone. Abundant marginal osteophytes of the articular surfaces and femoral head subluxation with consequent higher position of the right half of the pelvis. L—left side.

Figure 2

Mild deforming gonarthrosis visualized by MRI (proton-density fat saturated sequences in sagittal and coronal plane) and by CT (multiplanar reconstruction, coronal plane). Patchy areas of subchondral bone edema of femoral and tibial articulations with numerous marginal osteophytes. Articular cartilage is denuded in medial compartment, while in lateral compartment I-II degree hondromalacic changes are seen. Narrowed articular spaces with reactive effusion propagating to suprapatellar bursa are seen. High signal intensity of menisci and cruciate ligaments suggestive of degenerative changes. Ruptured medial meniscus. Reactive edema of periarticular and subcutaneous soft tissues.

Figure 3

(A–D) Ultrasound of the knee joint in exacerbation of osteoarthritis (high-frequency linear probe: B-mode and Power Doppler). Irregular echoes from the femoral (F) and tibial (T) articular surfaces corresponding to marginal osteophytes (A,B). Hyperemia (red color in white rectangle) and edema of the thickened, hypertrophic synovial membrane (yellow bidirectional arrows) with effusion (+) in the suprapatellar bursa are signs of reactive inflammation. Loss of tension and fine linear echostructure of the medial collateral ligament (M). Absence of linear echostructure and decreased echogenicity (yellow ellipse) in the distal part of the quadriceps muscle tendon. Enthesophyte (yellow rectangle) at the base of the patella (P) (C,D).

Figure 4

Ultrasound of the medial part of a healthy knee. Regular echoes from the femoral (F) and tibial (T) articular surfaces. The peripheral part of the medial meniscus (yellow dotted line) without a visible boundary continues into the posterior (oblique) fibers of the medial collateral ligament (M) that insert into it. The other (anterior) fibers of the medial collateral ligament continue vertically toward their insertion on the proximal tibia. Normal distance between the articular bodies indicates preserved thickness of the articular cartilages (yellow bidirectional line).

Figure 5

Sonographic image of a Baker’s cyst in the medial part of the popliteal fossa. Punctiform internal echoes from the cyst lumen which communicate with the joint space of the knee joint (yellow bidirectional arrow). Fluid within the cyst enhances the ultrasound beam posteriorly.