• Full Name: DUONG BICH HANH
• Affiliation/Institution: Vinmec
• Country: Vietnam

Introduction
Patellar instability is an uncommon condition that leads to significant functional impairment, with a reported prevalence of 0.006% in adults and 0.043% in children. It is classified into four types: traumatic, habitual, recurrent, and congenital. Although patellar realignment surgery aims to restore normal knee joint anatomy, postoperative rehabilitation plays a crucial role in protecting surgical outcomes and optimizing functional recovery.

Case Description
A 12-year-old female patient was diagnosed with bilateral habitual patellar dislocation. She initially underwent right-sided patellar realignment surgery including lateral release, medial plication, and tibial tubercle transfer, followed by a structured rehabilitation program. One year later, due to persistent instability on the contralateral side, the patient underwent the same surgical procedure on the left knee, followed by postoperative rehabilitation using a similar progressive protocol.

Results

Following staged bilateral surgeries and a progressive rehabilitation program, both knees achieved full, pain-free range of motion with stable patellar tracking and no redislocation episodes during follow-up. Functional outcome scores demonstrated substantial recovery, with AKPS scores exceeding 85 bilaterally and KOOS–ADL scores improving to above 85, indicating restoration of daily functional capacity. KOOS Sport and Recreation subscales also improved markedly, reflecting better performance during higher-demand physical activities.Three-dimensional motion analysis conducted in a motion laboratory demonstrated restoration of symmetrical gait patterns, increased knee flexion during stance phase, and improved limb loading symmetry. Dynamic movement analysis revealed normalized lower-limb kinematics, improved hip and knee control, and absence of dynamic valgus during functional tasks such as landing and directional changes.Quadriceps and hamstring muscle strength recovered to more than 90% limb symmetry compared with the contralateral limb as assessed by handheld dynamometry. Functional performance testing demonstrated limb symmetry indices above 90% in single-leg hop, triple hop, crossover hop, and timed hop tests, with stable landing mechanics and no instability symptoms.Balance and neuromuscular control assessments demonstrated marked improvement, with symmetrical performance during single-leg stance, dynamic balance testing, and functional reach tasks. The patient showed good postural stability during single-leg squat and landing assessments without pain, swelling, or instability symptoms during progressive sport-specific drills.Radiological assessment confirmed appropriate patellar alignment and maintenance of surgical correction in both knees. No postoperative complications or recurrence of instability were observed. Based on clinical, functional, and biomechanical criteria, the patient successfully returned to recreational sports participation without limitation.

Conclusion
A staged surgical approach combined with individualized postoperative rehabilitation resulted in substantial functional improvement and restored knee stability in bilateral habitual patellar dislocation, highlighting the essential role of rehabilitation in long-term treatment success.

Keywords: Patellar dislocation; Patellar realignment; Rehabilitation; Bilateral surgery