J Korean Orthop Assoc.  2021 Apr;56(2):134-141. 10.4055/jkoa.2021.56.2.134.

Results of Surgical Treatment of Patella Dislocation

• Kim HT
• Cho YJ

• KMID: 2514859
• DOI: http://doi.org/10.4055/jkoa.2021.56.2.134

Abstract

Purpose
Patellar dislocations have a range of causes. This study examined the results of treatment aimed at balancing soft tissues around the patella.
Materials and Methods
Thirty-two patellar dislocations in 28 patients (21 females and seven males) were examined. The mean patient age at the time of surgery was 11.5 years, and the mean follow-up period was 4.6 years. Dislocations were 19 chronic, six habitual, six congenital, and one acute. Soft tissue balancing surgery included lateral capsular release, medial capsular plication, and inferolateral transfer of the vastus medialis obliquus. Medial transfer of the patellar tendon, partial strip of the rectus femoris and patella tendon, and distal femoral osteotomy were also performed selectively. The preoperative Q angle, femoral anteversion angle, tibial external rotation angle, tibial tubercle-trochlear groove distance (TT-TG distance), mechanical femoral-tibial angle, and femoral trochlear dysplasia according to Dejour were measured, and the pre- and postoperative Lysholm–Tegner scores were used to analyze the clinical results.
Results
The mean preoperative Q angle, TT-TG distance, femoral anteversion angle, tibial external rotation angle, mechanical femoraltibia angle, and Lysholm–Tegner score were 9.3°, 15.5 mm, 25.6°, 30.4°, 3.0°, and 75.8, respectively. Eleven patients had systemic ligament laxity with a Beighton score of five or more. Twenty-two patients had femoral trochlear dysplasia: four type A (3 patients), 16 type B (15 patients), one type C (1 patient), and four type D (3 patients). Of the 32 cases, 28 were corrected successfully by the first operation. Of four cases of postoperative subluxation, three were corrected by the second operation, and one of them was corrected after a third operation. The last patient is currently being followed-up. The mean Lysholm–Tegner score improved to 85.6 after the operation.
Conclusion
Correcting all the causes of patella dislocation simultaneously is difficult. Nevertheless, satisfactory outcomes were obtained with soft tissue balancing surgery around the patella and a corrective osteotomy for an abnormal mechanical axis of the femur-tibia and torsion.

Keyword

patellar dislocation; treatment outcome