Arthrosis of the knee (gonarthrosis) involves consumption of the knee’s articular cartilage. This is a gradual degenerative disease characterized by increasing pain and rigidity that limits joint movement.
Arthrosis may be primitive, ie. without a definite cause, or secondary, ie. caused by deviation from the axis (varus or valgus knee*), outcome of fractures, osteonecrosis, inveterate lesions of the anterior cruciate ligament, outcome of meniscectomy (removal of the meniscal cartilage) with open surgery (as practised till the end of the ‘80s), prior articular infections or other pathologies.
Knee arthrosis may affect the entire joint, only the medial or lateral femoral-tibial compartment (mono-compartmental arthrosis) or only the femoral-patellar articulation (femoral-patellar arthrosis)
Typical onset of gonarthrosis involves pain, initially following prolonged effort and later also on resuming activity after a rest (getting out of bed or out of a chair). Production of excess synovial liquid by the inflamed capsule causes swelling. Pain may gradually become more frequent and lead to limited joint movement and limping. Being woken at night through pain is associated with severe arthrosis. Articular degeneration and the growth of osteophytes are associated with increased flexion-extension noise (creaky joints). As the disease worsens, the ligaments are also damaged, leading to sensations of the knee giving out and serious knee instability.
Standard radiography (anterior-posterior and lateral) of the symptomatic knee is sufficient for diagnosing gonarthrosis. Typical X-ray evidence of arthrosis of the knee includes:
- depletion of the articular rim (caused by consumption of the cartilage, which is radiotransparent, ie. it appears as empty space inside the joint);
- presence of osteophytes (small bone spurs near the articulation);
- presence of geodes (areas of bone loss);
la presence of bone sclerosis (areas of bone thickening underneath the worn or suffering cartilage).
* Varus: said of a segment of a limb that turns inward toward the midline of the body.
Valgus: the opposite of varus, referring to an abnormal bending of a segment of limb outward from the midline of the body, eg. varus or valgus foot or knee.
1. Knoop J, Steultjens MP, van der Leeden M, van der Esch M, Thorstensson CA, Roorda LD, Lems WF, Dekker J. Proprioception in knee osteoarthritis: a narrative review. Osteoarthritis Cartilage. 2011 Apr;19(4):381-8.
2. Vaquero J, Calvo JA, Chana F, Perez-Mañanes R The patellar thinning osteotomy in patellofemoral arthritis: four to 18 years’ follow-up. J Bone Joint Surg Br. 2010 Oct;92(10):1385-91.
3. Feeley BT, Gallo RA, Sherman S, Williams RJ. Management of osteoarthritis of the knee in the active patient. J Am Acad Orthop Surg. 2010 Jul;18(7):406-16.
4. Delfino G, Lanciotti E, Liguri G, Stefani M, Dizionario Enciclopedico di scienze mediche e biotecnologiche e di biotecnologie, 2° edizione. Zanichelli. 2003.