Articular cartilage damage refers to an injury to the cartilage lining the joint surfaces of the bones within in the knee joint. Cartilage damage can develop due to trauma, resulting from chondral or osteochondral defects or simply because of the natural degenerative process due to age (Brittberg et al., 2016), which is referred to as “generalised cartilage damage”. Direct trauma (focal damage) for example may occur when landing on the knee, compressing the patella (kneecap) against the underlying bone and cartilage. Cartilage damage may also develop as a secondary injury, when firstly supporting structures (i.e.: ligaments, menisci) of the knee joints are damaged.
Cartilage is the cushion of the bone surface and in a healthy condition is able to deal with millions of cycles of extreme loading during whichever impact is coming from the performed movement (jumping, kneeling, pivoting etc) (Halloran et al., 2012). Articular cartilage has to deal with significant mechanical loading during a human’s daily activity throughout the day. A healthy cartilage tissue provides the ability of load bearing, regulating of the mechanobiological processes for the tissue, maintenance and, more important, repair of the same (Halloran et al., 2012). Mechanical loading is necessary for general joint health and to “programme” the cartilage for its functional use by forming the collagen (cartilage is formed and built by different types of collagen) fibers architecture.
Cartilage damage can occur not only in existing biomechanical problems (i.e.: leg axis problems), but also when there is a drastic change in biomechanics that may negatively influence the joint.
Articular cartilage damage repair has shown to allow return to sport but rehabilitation time is lengthy in time and need thoroughness of the patient.
Non-conservative treatment is chosen when the joint fails to heal on itself. Surgical treatment is performed in severely damaged areas and established for focal traumatic defects, most frequently in otherwise healthy joints (Brittberg et al., 2016). Normal cartilage repair is according to Brittberg et al. (2016) very depending on the surrounding cartilage; at this point, there is no “gold-standard” repair technique to address all cartilage damages equally well. Fact is, that no matter what kind of intervention is chosen (arthroscopic, marrow tapping techniques, osteochondral auto/allo-grafting, cell based techniques, growth factors etc.), the result is always a fibrous repair tissue (fibrocartilage) which lacks the biomechanical quality of the original tissue (Falah et al., 2010).
Brittberg M. et al., 2016, Cartilage repair in degenerative ageing knee, Acta Orthopaedica, 87 (363), pp: 26-38
Halloran J.P. et al., 2012, Multiscale Mechanics of Articular Cartilage: Potentials and Challenges of Coupling Musculoskeletal, Joint, and Microscale Computational Models, Annals of Biomechanical Engineering, 40(11), pp: 2456-2474
Falah M. et al., 2010, Treatment of articular cartilage lesions of the knee, International Orthopaedics, 34(5), pp: 621-630