Osteoarthritis is the most common form of arthritis and involves damage to the protective cartilage that cushions the ends of bones. Osteoarthritis can damage any joint, however, it commonly affects the knees.
Anatomy and Pathophysiology
The knee joint includes the distal end of the femur (thigh bone), proximal end of the tibia (shin bone) and the patella (kneecap). The end surfaces of the three bones are covered with articular cartilage, which is a smooth surface that protects the joint. In between the femur and the tibia the medial and lateral meniscus can be found. The menisi are the “shock absorbers” and help keep the joint stable.
Osteoarthritis is a wear and tear type of arthritis that occurs over time. The cartilage gradually wears, frays and becomes roughened. The space between the bones reduces and the meniscus also wear done and tear in time. Patients often report stiffness, pain and swelling. Motion can be limited, particularly in the morning. Vigorous activity may cause pain to flare up, while more moderate activity may help symptoms.
Physical Examination and Work-up
On examination, swelling and tenderness to palpation is often present. Range of motion may be restricted at the end ranges of bending or extended. A grinding sensation (crepitus) often exists, as does gait abnormalities.
X-rays generally reveal narrowing of the joint space, bony spurring and, if present, mal alignment. MRI is not needed to make the diagnosis of osteoarthritis but may be indicated for other reasons.
Treatment of Knee Osteoarthritis
Treatment begins with non-operative interventions including activity modification, physical therapy, bracing and injections. Physical therapy focuses on strengthen the muscles in the leg.
NSAIDs, such as ibuprofen and naproxen, may be suggested dependent on medical history.
In the setting of failed non-operative management, surgery may be indicated. Arthroscopic procedures may be employed to remove large loose bodies or to debride a degenerative meniscal tear. If malalignment is present, a knee osteotomy is recommended to alleviate pressure on the knee joint. Knee osteotomy is indicated in early stage, uni-compartmental osteoarthritis. Total or partial knee replacement (arthroplasty) is performed for end stage osteoarthritis, when a new joint surface is implanted to restore knee function.
After any type of surgery for knee osteoarthritis of the knee, physical therapy is essential to optimal recovery. An individualized program will be prescribed and coordinated with a recommended physical therapist.