Patellar chondromalacia is a degenerative change of the articular cartilage of the patella caused by injury, including swelling, fragmentation, detachment and erosion of the cartilage surface of the patella. The same changes occur in the femoral condyle and the corresponding part of the patella, resulting in osteoarthritis of the patellofemoral joint.
Chondromalacia patellae occurs in younger adults, but there are many cases in middle-aged and older adults. The disease is characterized by pain in the knee joint, which affects the patient’s life and work. In recent years, the disease has attracted the attention of the medical community and is undergoing extensive research.
1. Pathogenesis
The patella is located in the front of the knee joint and is an important part of the knee joint. The patella is a daughter bone of the quadriceps tendon, which is fixed to the front of the knee by the quadriceps tendon and patellar ligament, and forms the patellofemoral joint with the femoral condyles. The back of the patella is covered by articular cartilage. The patella plays an important role in the function of the knee joint. It acts as a lever fulcrum, making the knee joint flexible and strong during extension and flexion. At the same time, the patella is also under great pressure during knee extension and flexion, so the articular cartilage surface is easily damaged. People with knee deformities, such as high patella, low patella, inversion and valgus of the knee, are prone to this disease. However, most patients do not have joint deformities and their onset is associated with chronic injuries to the knee. The cartilage surface of the patella is easily damaged by violent knee movements, such as cyclists. The onset of the disease in middle-aged and elderly people is often associated with continuous pressure on the patella, such as long-term squatting labor, where the patella is under the most pressure. Long-term cast fixation also tends to compress the patella. Clinical observation shows that chondromalacia of the patella can also be induced during traction treatment of the lower extremity after fracture.
Articular cartilage is a tissue without blood flow, and its nutrition depends on the extrusion of joint activities to make the nutrients in the synovial fluid penetrate the cartilage. When the patella is subjected to continuous tremendous pressure during long-term squatting work, the articular cartilage can be mechanically damaged and the nutrition of the cartilage can be affected. The joint cannot move during long-term cast fixation and traction, which restricts the penetration of synovial fluid into the cartilage and finally leads to chondromalacia of the patella.
The occurrence of chondromalacia patellae in middle-aged and elderly people is an intrinsic factor in the occurrence of chondromalacia patellae, in addition to the above-mentioned injury factors, due to aging, changes in the composition of the articular cartilage itself.
The articular cartilage is gradually fragmented, detached or eroded and dissolved after injury. The subchondral bone is exposed and bone spurs form at the edges of the cartilage. At this time, the smooth articular cartilage surface becomes rough and uneven, and friction occurs when the joint moves. As the articular cartilage is destroyed and the joint surface is not smooth, the damage to the joint will be further accelerated.
2.Clinical manifestations
The onset of disease is slow. Initially, the knee is uncomfortable and the pain is poorly localized. Later the pain behind the patella is obvious, and the pain increases during and after activities, especially when going up stairs. When the disease is severe, there is frictional sensation in the knee joint activities. On examination, squeezing the patella can induce pain and a friction sound. X-rays, early on, may not show any difference. With the development of the disease, narrowing of the patellofemoral joint space, subchondral bone sclerosis and osteophytes at the edge of the patella can be seen.
3.Treatment
Treatment emphasizes early treatment. Treatment in the early stage of cartilage injury is likely to control the development of the disease and achieve good results. Once the articular cartilage is destroyed and the joint surface is not smooth, the disease will develop rapidly, which is not only difficult to treat, but also difficult to achieve good results.
①Conservative treatment
Early stage of articular cartilage degeneration, when the joint surface is still intact and smooth, regular treatment can often achieve satisfactory results. Conservative treatment is suitable for patients with early joint discomfort or pain and no significant changes in the joint space. The most important point at this time is to limit the movement of the knee joint to reduce the pressure on the patellofemoral joint surface, thus blocking the role of mechanical factors causing cartilage damage, which is conducive to the healing of injured tissue. The specific method is: minimize squatting action, avoid long squatting work. The patella is under the most pressure when squatting. The pressure on the patella when going up the stairs and riding a bicycle is also very large and should be noted. At the same time, pay attention to the combination of movement and static. The quadriceps atrophy will occur when the joint is completely rested, which is not conducive to the nutrition of the articular cartilage.
A reasonable approach is to actively and slowly extend and flex the knee joint in bed to maintain lubrication and nutrition of the joint surface, enhance quadriceps muscle strength, and also reduce the pressure on the patellofemoral joint surface.
Necessary medication may be administered. Oral anti-inflammatory and analgesic drugs, such as ibuprofen and anti-inflammatory pain, can control the symptoms.
Physiotherapy can relieve pain, among which iontophoresis is more effective.
Intra-articular injection of hyaluronic acid can increase the lubricating effect of the joint surface, which is a new method that has emerged in recent years.
Intra-articular hormone injection is not recommended because hormone itself can damage joint cartilage.
②Surgical treatment
Surgery can be considered for patients with severe disease who have failed conservative treatment. Surgery is an invasive treatment method. Therefore, conservative treatment should be adopted as much as possible. However, there is some significance in surgical treatment for patients whose conservative treatment is ineffective. In recent years, surgical methods have been improved and developed, but they are far from ideal. Therefore, the choice of surgical treatment for middle-aged and elderly people should be carefully considered.
For patients with more limited lesions, surgery is performed to chip away the diseased cartilage down to the subchondral bone. It is possible to repair the lesion by autogenesis of the subchondral granulation. This approach is less invasive.
Patients with extensive cartilage destruction can have the diseased cartilage removed and covered with autologous periosteum or fascia, which can be expected to regenerate to form a new cartilage surface. This procedure is currently in clinical use.
If the patella and femoral articular surface are severely damaged, artificial patella replacement or removal of the patella is feasible.
4.Prevention
The occurrence of chondromalacia patella has both intrinsic and extrinsic factors for middle-aged and elderly people. The intrinsic factor is the degeneration of the articular cartilage itself, which is related to age and other factors. The extrinsic factor is the chronic damage to the articular cartilage caused by mechanical factors. Prevention of chondromalacia patellae is mainly based on reducing the constant pressure on the patellofemoral joint and improving the nutrition of the cartilage. The following measures can be referred to;
① Active and adequate movement of the joint. This should be done under non-weight-bearing conditions. For example, active extension and flexion of the knee joint while lying flat on the bed. Insist on 10 minutes once a day in the morning and once in the evening. Adequate movement of the joint can make all parts of the patellofemoral joint surface are stimulated, synovial fluid nutrients can evenly penetrate into the cartilage tissue, and can enhance the lubrication of the joint.
②Prevent continuous pressure on the patellofemoral articular surface. The patella is under greater pressure in the flexed knee position, which can easily damage the articular surface. To avoid continuous squatting pressure on the patellofemoral articular surface.
③When the cast is fixed or the lower extremity is traction treated, the quadriceps muscle should be actively exercised, which can drive the patella up and down when the quadriceps muscle is relaxed and contracted, which is conducive to the nutrient penetration of the cartilage and reduces the continuous pressure on the patellofemoral articular surface.
④ When discomfort or indolent pain occurs in the knee joint, the possibility of early patellar chondromalacia should be considered, and timely rest and treatment should be provided to prevent aggravation of articular cartilage degeneration.