It is more common in children, with females being affected more frequently 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 abnormally lateral attachment of the patellar ligament, abnormal insertion of the vastus lateralis muscle, a small and flat patella, a shallow femoral intercondylar groove with hypoplasia of the lateral condyle, and genu valgum deformity.

bubble_chart Diagnosis

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

bubble_chart Treatment Measures

The treatment for 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, and even knee osteoarthritis, affecting work and daily life.

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

(1) Soft tissue surgery

Includes:

1. Tightening and suturing of the medial knee retinaculum, joint capsule, and quadriceps expansion.
2. Retinaculum transfer (Campbell): Medial retinaculum and muscle pedicle transfer (Krougius).
3. Tendon transfer: Transferring the medial hamstring to strengthen the medial pull of the quadriceps.

(2) Distal femoral surgery

For cases of femoral internal rotation, genu varum, or femoral lateral condyle dysplasia, femoral supracondylar osteotomy or femoral lateral condyle elevation (Albee) is performed accordingly.

(3) Patellar ligament transfer (Houser)

In children, a partial patellar ligament transfer (Goldthwait) is performed.

(4) Patellofemoral arthroplasty

Reshaping the patella, deepening the femoral trochlear groove, and interposing surrounding soft tissues.

Meng Jizhen proposed that habitual patella dislocation involves varying degrees of local structural developmental deformities, and no single surgical method can address all cases. Comprehensive surgical treatment should be tailored to the specific deformities, with an emphasis on medial pull reinforcement via medial quadriceps transfer. The surgical approach includes:

1. Releasing the contracted lateral soft tissues of the knee joint.
2. Tightening and suturing the medial joint capsule and relocating the insertion of the medial quadriceps to the lateral side of the patella.
3. Performing Houser or Goldthwait surgery as needed based on the specific condition.