Cartilage Integrity: A Review of Mechanical and Frictional Properties and Repair Approaches in Osteoarthritis

Abstract

Osteoarthritis (OA) is one of the most common causes of disability around the globe, especially in aging populations. The main symptoms of OA are pain and loss of motion and function of the affected joint. Hyaline cartilage has limited ability for regeneration due to its avascularity, lack of nerve endings, and very slow metabolism. Total joint replacement (TJR) has to date been used as the treatment of end-stage disease. Various joint-sparing alternatives, including conservative and surgical treatment, have been proposed in the literature; however, no treatment to date has been fully successful in restoring hyaline cartilage. The mechanical and frictional properties of the cartilage are of paramount importance in terms of cartilage resistance to continuous loading. OA causes numerous changes in the macro- and microstructure of cartilage, affecting its mechanical properties. Increased friction and reduced load-bearing capability of the cartilage accelerate further degradation of tissue by exerting increased loads on the healthy surrounding tissues. Cartilage repair techniques aim to restore function and reduce pain in the affected joint. Numerous studies have investigated the biological aspects of OA progression and cartilage repair techniques. However, the mechanical properties of cartilage repair techniques are of vital importance and must be addressed too. This review, therefore, addresses the mechanical and frictional properties of articular cartilage and its changes during OA, and it summarizes the mechanical outcomes of cartilage repair techniques.

Keywords: cartilage; cartilage biomechanics; cartilage friction; friction; osteoarthritis; wear.

Figure 1

Cartilage layers illustrating differences in collagen mesh structure and chondrocyte arrangement.

Figure 2

Cross-sectional view of ECM, with a division into pericellular, territorial, and interterritorial cartilage sections.

Figure 3

Arthroscopic view of healthy cartilage on the medial femoral condyle (asterisk) and grade I lesion on the medial tibial condyle with visible superficial layer fibrillation (arrow).

Figure 4

Arthroscopic view of grade II lesion on the femoral trochlear groove with visible longitudinal fissures (arrow).

Figure 5

Arthroscopic view of grade III lesion with a visible cartilage deficit of less than 50% (arrow) in the femoral trochlear groove.

Figure 6

Arthroscopic view of grade IV lesion with subchondral bone exposure and complete cartilage loss, with only islands of cartilage visible on the medial femoral condyle.

Figure 7

Arthroscopic view of microfractures on the medial femoral condyle. One can appreciate extravagation of bone marrow from the MFX site.

Figure 8

Intraoperative view of donor site preparation for osteochondral blocks implantation on the lateral femoral condyle.

Figure 9

Intraoperative view of the final result with complete cartilage loss area coverage.

Figure 10

Dry arthroscopy view of a biodegradable non-woven hyaluronic acid scaffold covering a cartilage defect on the medial femoral condyle.

Figure 11

Dry arthroscopy view of a full-thickness cartilage injury in the femoral trochlea after debridement and preparation for matrix implantation.

Figure 12

Dry arthroscopy view of the same defect filled with cell-free matrix gel.