☆ Why does patellar dislocation occur? Patellar dislocation is one of the more common knee injury lesions, the causes of patellar dislocation can be divided into external and internal causes, external causes are often traumatic violence or sprains, while internal causes are mostly seen in patients with high patella; development of knee valgus, femoral condyle dysplasia, weak medial patellar support band, lateral contracture and other pathological factors. ☆ What is the classification of patellar dislocation? It can be broadly classified into acute traumatic patellar dislocation and chronic recurrent patellar dislocation as well as habitual patellar dislocation in children. ☆ Do all patellar dislocations require surgical treatment? In the case of first acute traumatic patellar dislocation, conservative treatment can be considered if there are no high-risk pathological factors for patellar dislocation, whereas in the case of acute dislocation combined with intra-articular fracture, or chronic recurrent dislocation and habitual dislocation, surgical treatment is definitely effective. Surgical treatment should be preferred. ☆ What is acute traumatic patellar dislocation and how should it be treated? Acute traumatic patellar dislocation can be caused by a fall and sprain, direct violent impact, etc. After the injury, patients often have localized swelling and pain in the knee joint, limited movement, and blood accumulation in the knee joint. These patients may also have congenital pathological bases such as high patella; lateral patellar subluxation; knee valgus deformity and other congenital pathologies and experience patellar dislocation after trauma, which should be highly valued in such patients. In addition, acute traumatic patellar dislocation, due to the instant impact between the patella and the femur, often occurs fracture or cartilage injury and exfoliation of the articular surface of the patella or femur, leaving joint free body formation and knee patella and femur cartilage surface injury after the acute phase swelling subsides. Treatment principles: For patients with initial patellar dislocation, knee X-ray should be improved. If intra-articular cartilage fractures and ligament injuries are suspected, additional knee CT and MRI examinations are recommended. For general patients, if intra-articular fracture and congenital pathological factors are excluded, conservative treatment can be tried first, with the knee joint fixed in plaster or brace in the straight position for 4 weeks, together with local swelling and pain relief medication or physical therapy. After that, knee mobility rehabilitation can be started gradually. For professional athletes or very active sportsmen, a one-stage surgical repair of the torn medial patellofemoral support band may also be considered. For patients with a preoperative diagnosis of intra-articular fracture free body formation, arthroscopic removal of the free body and repair of the medial patellar ligament is recommended. ☆ What is recurrent patellar dislocation and how should it be treated? Some patients with acute patellar dislocation will progress to recurrent patellar dislocation because of the above mentioned reasons, such as congenital high patella, knee valgus, femoral condyle dysplasia, patellar tilt or lateral subluxation and other congenital pathologies, or the initial conservative treatment of the medial patellar support band and ligament healing laxity, such patients are more and more prone to patellar dislocation because the medial-lateral balance of the patella is broken and the medial support structure is relaxed. Dislocation of the patella commonly occurs when the foot is fixed to the ground, the body turns medially, the lower leg is externally rotated, the patella feels unstable and usually falls easily. After repeated occurrences, the patient often does not dare to do rapid stop-and-go movements of the knee joint. Treatment principles: For patients with recurrent patellar dislocation, surgical treatment should be considered because conservative treatment is unable to repair the medial support structure, and patients often have to give up their favorite sports and reduce their sports level. With the current development of arthroscopic surgery in sports medicine, these patients can actually obtain very good results and restore their original knee function and level of motion to the greatest extent possible. The vast majority of patients with recurrent patellar dislocation are mild, and patellofemoral stability can be restored through surgery to strengthen the medial support structures, such as medial patellofemoral ligament (MPFL) reconstruction surgery. In contrast, patients with severe knee valgus, excessive Q-angle, and severe hypoplasia of the femoral condyle need to be treated with orthopedic osteotomy; internal or inferior displacement of the patellar tuberosity; and osseous surgery such as femoral condyloplasty. The treatment results are still relatively satisfactory. The vast majority of patients do not recur. After surgery, patients need systematic rehabilitation to restore knee mobility flexibility and adapt to the new patellofemoral relationship as soon as possible. ☆ What is habitual patellar dislocation and how should it be treated? Habitual patellar dislocation often occurs in children and adolescents between the ages of 6 and 14. This dislocation is associated with abnormal development of the knee joint, often due to extreme laxity of the medial patellar support band and thickening and contracture of the lateral soft tissues of the knee joint, and the patella can be repositioned when the knee is straightened, but the patella is fixedly dislocated to the outside when the knee is flexed. The patella can be repositioned when the knee is straightened, but is fixedly dislocated laterally when the knee is flexed. Because the patella is not in its normal position for a long time, it also leads to developmental abnormalities such as femoral condyles dysplasia and knee force line valgus, and such changes lead to a vicious circle in which the patella is more prone to dislocation. Therefore, habitual patellar dislocation in children is best treated with surgery. The younger the age, the better the results. It not only solves the dislocation problem, but also prevents secondary deformities. Treatment principle: preoperative full-length X-ray of the lower limb force lines, CT examination, and MR examination should be taken. The specific location and degree of abnormalities of the bony and soft tissue structures should be carefully analyzed. For patients with particularly severe knee valgus, femoral osteotomy or epiphyseal block should be performed, together with a combination of surgical modalities such as lateral release, medial tightening, quadriceps force line rearrangement, and inward displacement of some patellar tendon stops. The satisfaction rate of children with surgery is about 90%, and the lower extremity force line and patellofemoral cartilage development will be further improved as the patient grows and develops. ☆ If I am diagnosed with surgery, can I still use massage, hot compresses, cupping and other methods? Generally, it is not necessary before the surgery, but after the surgery, systematic knee rehabilitation exercises will be provided according to the specific situation. ☆ What are the risks if I don’t have surgery when I should? Recurrent patellar dislocation, if left untreated, will cause the injured patellofemoral joint to become more and more relaxed, making it easier for the patient to fall and get injured, which will aggravate the original injury, and habitual patellar dislocation in children, if left untreated, will cause the child to fall and get injured, and will easily lead to lower limb force line and knee joint dysplasia, which will aggravate the patellar dislocation. Acute patellar dislocation combined with intra-articular fracture is likely to produce intra-articular free body, wear out the knee joint and aggravate the cartilage damage in the knee joint. ☆ Is it true that the earlier the surgery, the better the result? Early treatment of recurrent and childhood habitual patellar dislocation is preferable. Combining other intra-articular structural injuries will complicate the treatment and affect the outcome. ☆ What conditions are contraindications to surgery? Patients with recent systemic or local infections, patients with severe organ and limb injuries, and patients with severe cardiopulmonary disorders that are not suitable for surgery are not suitable for surgical treatment. ☆ When do patients need second-stage surgery? Patients with severe knee dysplasia, femoral condylar dysplasia and other bony abnormalities may need to have their bony abnormalities corrected first, followed by other soft tissue surgery such as ligament reconstruction and local release. ☆ Do I need to remove the surgically implanted implants? Which ones can be removed and for how long? Usually, surgical implants do not need to be removed. The implants should be removed if the initial surgery fails and affects the revision surgery.