Osteochondritis dissecans

　　Osteochondritis dissecans (CP), also known as patellar cartilage osteochondritis and patellar cartilage inflammation, is a common disease of the knee joint, prevalent in young and middle-aged adults, especially common in athletes and sports enthusiasts, with a higher incidence in women than in men. Currently, the medical community普遍认为 the causes of the disease include the following:

　　1. Biomechanical factors

　　(1) Trauma theory

　　Among the pathogenic factors of osteochondritis dissecans, the trauma theory is increasingly recognized, including direct trauma, indirect trauma, and various repeated physical stresses exceeding the physiological range of joint cartilage, leading to the destruction of the 'shell structure' and 'arch structure' of joint cartilage, the necrosis of chondrocytes losing their protection, the reduction of cartilage matrix synthesis, and the progressive destruction of joint cartilage.

　　(2) Patellar instability theory

　　Refers to high patella, low patella, patellar tilt, patellar subluxation or dislocation. Patellar instability can cause increased pressure and abnormal distribution on the patellofemoral joint surface, leading to cartilage injury.

　　(3) Patellofemoral pressure theory

　　The progress of research on the biomechanics of the patellofemoral joint has led to different understandings of the relationship between patellofemoral pressure and osteochondritis dissecans. It emphasizes the impact of high pressure on patellar cartilage osteochondritis dissecans. However, the theory of excessive pressure is difficult to explain the phenomenon that the medial aspect of the patella is a high-incidence area for patellar cartilage osteochondritis dissecans in clinical practice.

　　2. Biochemical factors

　　(1) Autoimmune theory

　　The surface of the joint cartilage can prevent the entry of anti-collagen antibodies into the deep tissue of the cartilage and has a protective effect on it.

　　(2) Cartilage nutritional disorder

　　Various injury factors (especially mechanical stimulation) cause abnormal changes in the secretion and composition of synovial fluid (such as the activity of enzymes, the content of various nutrients, and the osmotic pressure of synovial fluid), affecting the normal nutrition and physiological biochemical processes of patellar cartilage, promoting cartilage degeneration and disease.

　　(3) Cartilage dissolution theory

　　After the synovium of the joint is injured, the osmotic pressure changes, and the number and activity of enzymes in the plasma increase in synovial fluid, leading to the dissolution of cartilage.

　　Osteochondritis dissecans is the result of the combined effects of various factors, with changes in patellofemoral joint pressure caused by various factors being the external cause, and autoimmune reactions and cartilage nutritional disorders being the internal causes of osteochondritis dissecans.

　　The early symptoms of patellar ossification are not serious, and rest or taking general painkillers can alleviate the symptoms. The lesion develops continuously in a 'hidden state' until it develops into patellofemoral arthritis. In severe cases, the extension and flexion of the knee joint is limited, and it is not possible to stand on one leg. In the late stage, when patellofemoral osteoarthritis has formed, there is obvious damage to the cartilage and subchondral bone in the lesion area, and the cartilage has no ability to regenerate and repair. In addition, it is easy to be accompanied by meniscus injury and traumatic arthritis, etc.

　　Direct knee injury can cause patellar cartilage or bone cartilage fracture, or due to repeated injuries, such as sports injuries, leading to degenerative changes in cartilage, rough cartilage surface, losing luster, and in severe cases, cartilage detachment, bone exposure, and the corresponding femoral joint surface is also damaged. The site of injury is mostly in the center of the patella. This disease often occurs in young and middle-aged people, and there is often a clear history of trauma, or chronic cumulative minor injuries. The main symptom is posterior patellar pain in the knee joint, which varies in severity. Generally, the symptoms are not obvious when walking on flat ground, but the pain worsens when squatting, climbing stairs, going up and down slopes, or walking a long distance.

　　The occurrence of patellar ossification has inherent and external factors for middle-aged and elderly people. The inherent factor is the degeneration of the joint cartilage itself, which is related to factors such as age. The external factor is the chronic damage to the joint cartilage caused by mechanical factors. The main prevention of patellar ossification is to reduce the continuous pressure on the patellofemoral joint and improve the nutrition of the cartilage.

　　1. Actively fully move the joint

　　Perform the exercises without bearing weight. For example, lie on the bed and actively extend and flex the knee joints. Do this twice a day, in the morning and evening, for 10 minutes each time. Fully moving the joint can stimulate all parts of the patellofemoral joint surface, allowing the nutrient components of synovial fluid to evenly penetrate the cartilage tissue, and can enhance the lubricating effect of the joint.

　　2. Prevent the continuous pressure on the patellofemoral joint surface

　　The pressure on the patella is greater in the flexed knee position, which is easy to damage the joint surface. It is necessary to avoid the continuous pressure on the patellofemoral joint surface caused by prolonged squatting.

　　3. Casting fixation or lower limb traction treatment

　　Actively exercise the quadriceps femoris muscles, as the contraction and relaxation of the quadriceps femoris can move the patella up and down, which is beneficial for the nutrition penetration of the cartilage and the reduction of continuous pressure on the patellofemoral joint surface.

　　4. Uncomfortable or non-localized pain in the knee joint

　　Early patellar ossification should be considered, and timely rest and treatment should be taken to prevent the progression of joint cartilage degeneration.

　　Patellar ossification (CP), also known as patellar cartilage ossification or patellar cartilage inflammation, the auxiliary examination methods for this disease are mainly physical examination, X-ray examination, and radionuclide examination:

　　1. Patellar pressure and friction test

　　During the examination, the patella is pressed and rubbed against the corresponding femoral condyle joint surface, or it slides up and down or left and right, with a rough friction sensation, friction sound, and discomfort or pain; or the examiner can cause pain by pushing the patella to one side with one hand while pressing the edge behind the patella with the thumb of the other hand. The floating patella test may be positive when there is joint effusion.

　　2. Single-leg squatting test

　　When the patient supports their weight on one leg and gradually squats to 90°～135°, pain and weakness occur, and they cannot stand up on one leg after squatting.

　　3. X-ray examination

　　X-ray films of the knee joint in anteroposterior and lateral positions, and the patella tangential position show no abnormalities in the early stage, while in the late stage, due to the extensive wear of cartilage, the space between the patella and the femoral condyle can become narrow, and there may be bone hyperplasia at the edges of the patella and the femoral condyle.

　　4. Radioisotope examination

　　During bone scanning, the lateral view shows localized radioactive accumulation of the patella, which has early diagnostic significance.

　　There is no need to avoid certain foods in the diet of patients with patellar chondromalacia, just strengthen nutrition. They can eat more calcium-rich foods such as milk and dairy products, beans, shrimp shells, kelp, etc. The patient's diet should be light, easy to digest, with more fruits and vegetables, a reasonable diet, and attention to adequate nutrition. In addition, patients should also avoid spicy, greasy, and cold foods.

　　Patellar chondromalacia (CP), also known as patellar cartilage chondromalacia or patellar cartilage inflammation, patients with severe symptoms should seek surgery in a timely manner. Below, I will introduce the patellar cartilage cutting operation, which includes superficial cartilage cutting, cutting cartilage to bone, and bone drilling.

　　1. Superficial cartilage cutting

　　Use a sharp knife to cut away the degenerated cartilage until it reaches the normal part of the cartilage. Although the cartilage's ability to repair itself is weak after shallow cutting, after the excision of the necrotic cartilage, through several months of shaping, the surface becomes smooth and is covered with several layers of flat cells, making the operation achieve a relatively satisfactory result.

　　2. Cartilage cutting to bone

　　If the cartilage damage has reached the bone, the entire layer of cartilage can be cut, and the edges of the wound can be trimmed to form an inclined plane, without processing the exposed bone. A full-thickness cartilage defect that does not reach the medullary cavity can be repaired by slow endogenous regeneration, and the regenerating cartilage is hyaline cartilage.

　　3. Cartilage cutting to bone and drilling

　　The operation involves cutting away the entire layer of damaged cartilage, making several holes in the exposed bone with Kirschner wires to cause bleeding in the bone bed, resulting in a full-thickness defect of the joint cartilage deep into the medullary cavity, which can be repaired exogenously with mesenchymal tissue from the medullary cavity. This operation can be performed through arthroscopy, using a rasp to cut, or by direct vision arthroplasty.