Gonarthrosis is also known as a degenerative disease of the knee. The degenerative process begins in the joint cartilage, leading to its gradual destruction, secondary inflammation and destruction of the remaining knee structures. Symptoms of degeneration are pain and swelling in the knee that increases with walking or other activities that overload the joint. There is also a gradual limitation of mobility in the joint and its deformation. In advanced forms of gonarthrosis, gait is significantly more difficult, and knee pain may also be present at rest.

Osteoarthritis of the knee (gonarthrosis) is caused by a number of factors related to:

- reduced quality of joint cartilage (genetic and metabolic factors),
- increased joint overload (overweight, standing work, competitive sports),
- chronic arthritis (rheumatoid diseases),
- disturbance of the joint axis (valgus knees, varus knees),
- disturbance of joint biomechanics (knee instability, condition after menisectomy),
- acute articular cartilage injuries (condition after joint fractures, knee sprains).

Degenerative changes can occur faster when a person with knee instability intends to play a sport that requires full knee function (skiing, contact sports). The ACL ligament reconstruction procedure is recommended for people:

- who underwent a conservative treatment process, but are not satisfied with the results,
- professionally practicing sports,
- with ACL ligament insufficiency found in both knee joints.

Treatment of osteoarthritis of the knee is mainly based on reducing factors accelerating the wear of the articular cartilage. Treatment includes: body weight normalization, avoidance of excessive joint overload, exercises to strengthen the muscles stabilizing the knee joint, physical therapy procedures and biological therapies (plasma with concentrated platelets, Orthokine). Sometimes it is necessary to surgically correct the joint axis (to prevent further progression of the deformity) or arthroscopic cleaning of the joint from pathological productive changes. Advanced degrees of degeneration may require knee arthroplasty, i.e. replacement of the damaged joint with an artificial implant.