Anterior knee pain is the most common site of chronic knee pain, with a high incidence in the population and a significant impact on the patient’s daily life and quality of life. It usually manifests as soreness and weakness when walking up and down stairs, pain when standing up after squatting, popping and interlocking jamming in front of the knee, accompanied by different degrees of knee swelling and atrophy of the thigh muscles.
The painful swelling is closely related to activity and usually worsens with activity and is relieved or partially relieved by rest, and in some cases is also related to weather changes. Some patients have a significant history of knee sprains or collision injuries, or strenuous activity, or a history of prolonged long-distance walking, mountain climbing, and travel. However, some do not have an obvious cause or predisposing factor.
Some of the onset is related to the occupation in which the patient is employed. In female patients there is also a relationship with changes in the endocrine system. This chronic knee pain is easily diagnosed and treated as rheumatoid arthritis, traumatic arthritis or age-related osteoarthritis, but the treatment is unsatisfactory or even ineffective.
Summarizing our decades of clinical practice in knee treatment, we found that knee pain is mainly anterior knee pain, and its common causes are as follows.
1. Subpatellar fat pad injury;
2. Meniscal injury;
3. Synovial crease syndrome;
4, intra-articular free body;
5, peripatellar bursitis, tendonitis;
6, ligament injury;
7, habitual dislocation of the patella;
8, tibial tuberosity epiphysitis;
9, muscle tendon injury;
10, tumors (hemangiomas, cysts, etc.);
11.Vascular nerve bundle entrapment disease;
12, restless leg syndrome, etc., the respective characteristics are as follows.
(1) Infrapatellar fat pad injury
The infrapatellar fat pad is a filling structure with fat as the main component, located below the patella, deep surface of the patellar ligament, and extending to both sides of the knee eye, belonging to the extra-articular synovial cavity structure. Its main function is to fill the gap between the femoral condyles during joint movement, absorb shock, protect the knee joint, and reduce local stress and pressure. Chronic damage to this structure is caused by long-term repeated sports stimulation, as well as some minor acute trauma that accumulates over time.
In addition to the manifestation of anterior knee pain, there are usually deep sensitive pressure points under the patella, grinding the patella and pushing the patella to trigger or aggravate the pain. For treatment, conservative treatment can be started by braking and resting or reducing activities, local massage and hot compresses, and taking Chinese medicine to activate blood circulation and remove blood stasis. Physiotherapy, such as microwave and infrared rays, can also be used, and some patients can also receive good results from EMS. If the conservative treatment is not satisfactory, hydro-acupuncture can be used to release the injury. In severe cases, arthroscopic surgery to release or partially remove the subpatellar fat pad can be considered if the above treatment is not effective.
(2) Meniscus injury
The meniscus is a fibrocartilage structure within the tibiofemoral joint gap, which has the function of distributing pressure, absorbing shock and stabilizing the joint. It is susceptible to injury during twisting movements of the knee joint, and its pain is characterized as being confined to the medial and lateral joint gaps of the knee, usually in the middle or anterior part of the gap. There may be a history of joint popping or joint interlocking, and the pressure pain is sensitive and limited, sometimes felt as a clicking sound, and a positive McKay’s sign on physical examination.
A physical examination combined with an MRI examination is usually sufficient to confirm the diagnosis and the exact nature of the injury. If the symptoms are severe and the meniscus is ruptured, surgery is usually required.
(3) Synovial crease syndrome
Synovial crease is a relic of incomplete resorption of synovial layer in the joint cavity during development, which usually does not cause symptoms, but can cause pain after injury, compression, or strain and fibrosis hardening, characterized by pain in the infrapatellar pole medial and lateral patellofemoral gap area, local pressure pain can be found on physical examination, grinding patella sometimes has a popping sound, and can be felt in the corresponding parts of the fibrous strips of elasticity.
In the early stage of treatment, conservative treatment is possible, with appropriate braking and rest, knee protection, avoiding strenuous activities, taking anti-inflammatory and analgesic drugs, or local closure and water injection treatment. For patients with severe symptoms and ineffective conservative treatment, synovial lesions can be removed surgically, and arthroscopic surgery is currently the most common option.
(4) Intra-articular free body
Most of them are fine fragments of cartilage that have been ground and wrapped in the joint cavity and gradually grown. It is characterized by interlocking, popping and pain in the knee joint, or restriction of joint extension and flexion, and sometimes the patient can feel a small hard object free and running in the knee joint, and when interlocking occurs, an oval or flat hard object can be directly found. Treatment requires arthroscopic removal of the free body and management of the corresponding intra-articular lesion.
(5) Bursitis
The bursa is an accessory structure that exists where tendons, ligaments, and other soft tissues pass adjacent to or through the bony prominence and serves to relieve stress and reduce friction. There are mainly prepatellar bursa, subpatellar tendon bursa, suprapatellar bursa, femoral epicondyle bursa and goose foot tendon bursa around the knee joint, etc. When excessive movement, excessive friction or extrusion, contusion, can cause bursitis, mainly pain in the corresponding part of the bursa, local swelling, slightly high skin temperature, accompanied by pressure pain, certain activities or posture can cause or aggravate the symptoms.
Treatment is generally conservative, with proper rest and avoidance of excessive activities, local application of topical ointment, taking anti-inflammatory and analgesic drugs, and local closure treatment. In recent years, dispersive extracorporeal shock wave therapy has also been widely used, and has achieved good results. For conservative treatment is ineffective, you can choose surgery to remove the lesion bursa.
(6) Ligament injury
Ligaments are the static structures that maintain the stability of the knee joint, mainly the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments. The anterior cruciate ligament injury mostly appears in the front of the knee deep pain; posterior cruciate ligament injury mostly in the femoral attachment site that is the posterior pain, sometimes also manifested as the front of the knee deep surface pain. Of course, after ligament injury, there are also symptoms such as joint swelling, joint misalignment, and insecurity in going down stairs, etc. The examination may include positive floating patella test, positive drawer test, positive axial shift test, etc.
MRI examination can clarify the diagnosis and the extent of the injury. Early treatment requires braking, pressure bandaging and aspiration of blood in the joint. Surgical reconstruction of the ligament can be considered in the late stage of joint instability. In recent years, arthroscopic cruciate ligament reconstruction techniques have developed rapidly, and patients have a good prognosis. For diagnosed anterior and posterior cruciate ligament injuries, early surgical treatment is strongly recommended to protect the joint function and avoid aggravating the damage to the articular cartilage as well as the meniscus.
Lateral collateral ligament injuries are painful in the area between the medial and lateral femoral condyles to the slightly distal end of the medial and lateral tibial plateau, and can have local swelling, skin bruising, and pressure pain with a positive lateral stress test. Treatment is early braking with bracing or cast protection. It is supplemented with ice and swelling reduction, etc., and timely and active functional exercises in the later stage. If there is obvious lateral instability, surgery should be performed to restore ligament tension and joint function.
(7) Habitual dislocation of the patella
The patella is the largest seed bone in the body and is the fulcrum of the knee extension device, which can significantly enhance the knee extension force. Most people with patellar subluxation have a history of trauma, as evidenced by a history of significant outward patellar prolapse during knee trauma, which can occur repeatedly. On examination, the peripatellar rim is painful, and the provocation test and fear test can be positive. x-rays can show the outward deviation of the patella. Early treatment can be protected by plaster for 4-6 weeks. Repeated dislocation, i.e. habitual dislocation, should be treated by surgical reconstruction of the knee extension device.
(8) Tibial tuberosity epiphysitis
It is the result of ischemic changes in the tibial tuberosity epiphysis as a result of long-term injury and distraction stress. It is characterized by pain during jumping movements or strenuous activities, and in severe cases, when walking. On examination, the tibial tuberosity may be swollen, red and hot, with significant pressure pain and a positive resistance test, and the tibial tuberosity epiphysis may be separated, fragmented or hyperdense on X-ray.
The treatment should be adequate rest, avoid strenuous activities such as running and jumping, and apply topical medications and hot compresses locally. EMS treatment can achieve significant results.
(9) Muscle tendon injury
The quadriceps muscle ends at the patella and is continued by the patellar ligament, which is easily injured in this area during exercise. The quadriceps tendon ends slightly below the anterior medial aspect of the tibial plateau, and the retractor tendon ends at the femur, with localized tenderness and hematoma formation. A positive resistance test is performed.
Ultrasound or MRI can clarify the presence or absence of injury, hematoma, location and extent of injury. For treatment, early braking, aspiration of the hematoma, and compression bandaging are required. If the tear is obvious, emergency surgery is needed to repair it. In the chronic stage, physical therapy such as massage and massage, microwave, ultrashort wave and EMS therapy, hydro-acupuncture, and anti-inflammatory and analgesic drugs can be given.
(10) Tumor
Tumors of the knee include bone tumors and soft tissue tumors. The former commonly includes bone cyst, osteosarcoma, osteochondroma, bone giant cell tumor, etc. The latter includes hemangioma, tendon sheath cyst, meniscal cyst, pigmented villous nodular synovitis, etc. The clinical manifestations are local pain, local palpation, and localized pain. The clinical manifestations are local pain, localized masses, and localized occupying images on imaging. The main treatment is early surgery and some other necessary treatment.
(11) Vascular nerve bundle entrapment
It is a symptom caused by the compression of small vascular nerve bundles by scars or fibrous strips or other lesions. It is mostly seen above the patella and may have a history of local contusion, mainly manifesting as local pain. The painful area is not precisely localized during the examination, and the painful symptoms can be triggered or aggravated by touch or pressure. For treatment, physical therapy, including massage, can be used first, and EMS treatment has excellent results. In severe cases, hydroacupuncture can be used to release the pain, and if the effect is not obvious, surgery can be considered.
(12) Restless leg syndrome
It is an unbearable discomfort in the lower limbs, especially around the knee joint, at rest. The pain and other discomfort in both lower limbs at rest, especially at night during sleep. In mild cases, the symptoms are not serious; in severe cases, the patient may be unable to sleep, and in long cases, mental symptoms such as anxiety and depression may occur.
The symptoms are mostly bilateral and symmetrical, and many patients are unable to accurately describe their discomfort. Clinical examination, tests, CT or MRI do not show any abnormal findings. The treatment is to control the symptoms with methyldopa, which can be supplemented with physical therapy and psychiatric treatment.