It is more common in children, with females being more affected than males. Traumatic patella dislocation combined with femoral lateral condyle fracture is often caused by improper management. Most cases involve abnormal local structural development in the patient's knee joint, triggered by minor trauma. Those with abnormal local structural development may exhibit contracture of the lateral soft tissues of the knee, an attachment point of the patellar ligament that is laterally deviated, abnormal insertion of the vastus lateralis muscle, a small and flat patella, a shallow femoral intercondylar groove with hypoplasia of the lateral condyle, genu valgum deformity, and other conditions.

bubble_chart Clinical Manifestations

Subtle trauma to the knee joint or strong contraction of the quadriceps can cause dislocation. Most patients experience frequent dislocations, where the patella dislocates to the lateral side of the femoral condyle when the knee is flexed and naturally reduces when the knee is extended. Quadriceps atrophy and weak knee extension lead to a tendency to fall, but there is no significant pain.

bubble_chart Treatment Measures

The treatment of habitual patella dislocation yields better results at younger ages. It not only resolves the dislocation issue but also prevents secondary deformities. If treatment is delayed, secondary deformities such as hip and knee joint flexion and increased lumbar lordosis may occur. In severe cases, knee osteoarthritis can develop, affecting work and daily life.

Clinical practice has proven that surgical treatment can achieve significant outcomes. There are numerous surgical methods, which can be summarized as follows.

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1. Tightening and suturing of the medial knee retinaculum, joint capsule, and quadriceps expansion.

2. Retinaculum displacement (Campbell) and medial retinaculum/muscle pedicle displacement (Krougius).

3. Tendon displacement, where the medial hamstring is relocated to strengthen the medial pull of the quadriceps.

(2) Distal femoral surgeries: For cases involving internal rotation of the distal femur, genu varum, or hypoplasia of the lateral femoral condyle, procedures such as supracondylar femoral osteotomy or lateral femoral condyle elevation (Albee) are performed.

(3) Patellar ligament displacement (Houser), with partial patellar ligament displacement (Goldthwait) used in children.

(4) Patellofemoral joint arthroplasty: Reshaping the patella, deepening the femoral condylar groove, and interposing surrounding soft tissues.

Meng Jima proposed that habitual patella dislocation involves varying degrees of local structural developmental deformities, which cannot be resolved by a single surgical method. Comprehensive surgical treatment should be tailored to the specific deformities. He advocated for medial femoral muscle displacement to enhance medial pulling force. The surgical approach includes: 1. Releasing the contracted soft tissues on the lateral side of the knee joint.

2. Tightening and suturing the medial joint capsule and relocating the insertion point of the medial femoral muscle to the lateral side of the patella.

3. Performing the Houser or Goldthwait procedure as needed based on individual conditions.