A 16-year-old female high school junior recently faced significant challenges following a patellar dislocation event that left her with persistent knee pain and instability. This incident occurred when she stepped onto a slippery surface, causing her left knee to twist and her patella to dislocate laterally. Although the patella spontaneously reduced, she experienced severe pain, swelling, and instability, which prevented her from walking normally.
Prior to this incident, she had been managing recurrent patellar instability through conservative treatments, including anti-inflammatory medications, crutches, bracing, rest, activity modification, and physical therapy. Importantly, she had not undergone any surgical interventions.
Clinical Evaluation and Imaging
Upon examination, the patient exhibited a notable effusion and tenderness along the medial and lateral retinacula. Her range of motion was significantly restricted, limited to 0° to 20° of flexion due to pain. The patella apprehension test returned positive results, indicating instability. Varus and valgus stress testing confirmed ligamentous stability.
Initial radiographs revealed an osteochondral injury at the median ridge of the patella, with no significant degenerative changes observed in the medial, lateral, and patellofemoral compartments. An MRI further elucidated her condition, showing a large effusion and a substantial chondral defect in the medial facet, as well as a sizable loose body located in the lateral recess. The MRI indicated attenuation of the medial patellofemoral ligament and a normal tibial tubercle to trochlear groove distance of 12.3 mm.
Surgical Intervention
Faced with worsening instability resistant to conservative treatment, surgical options were discussed thoroughly with the patient and her family. They opted for operative management, which included arthroscopy to remove the loose body, possible fixation of the osteochondral fragment, and repair of the medial patellofemoral ligament (MPFL). A cartilage biopsy was also considered as a contingency for a future matrix-induced autologous chondrocyte implantation should the osteochondral fragment prove unsuitable for fixation.
The surgical procedure commenced under general anesthesia with standard preoperative antibiotics. The patient was positioned supine, and a pneumatic tourniquet was applied. Following the establishment of standard anterolateral and anteromedial portals, a comprehensive diagnostic arthroscopy revealed a significant osteochondral defect affecting most of the medial patellar facet. A large loose osteochondral fragment was identified in the lateral gutter and successfully mobilized into the patellofemoral compartment for removal.
Postoperative Recovery and Outcomes
In the weeks following the surgery, the patient attended follow-up appointments at intervals of two weeks, six weeks, three months, and six months. Remarkably, she reported no recurrent instability or complications. She regained full, painless range of motion in her knee and adhered to her rehabilitation protocol, which included consistent participation in physical therapy.
At her six-month follow-up visit, she demonstrated full extension and 140° of flexion. The patellar apprehension test yielded negative results, indicating stability, and radiographs confirmed a congruent patellofemoral joint with stable, well-reduced osteochondral fragments showing signs of reintegration into the patella.
Understanding Patellar Instability
Patellar instability in adolescents can manifest as a spectrum of conditions, ranging from asymptomatic subluxation to overt dislocation accompanied by osteochondral injury. Contributing factors may include traumatic ligament injuries, previous episodes of instability, ligamentous laxity, and anatomical variations such as an increased Q-angle or trochlear dysplasia. Notably, adolescents are particularly vulnerable to such injuries due to their skeletal immaturity.
Timely recognition and advanced imaging are crucial for managing patients with suspected osteochondral injuries, particularly those presenting with significant knee effusions and limited motion. MRI is invaluable for assessing cartilage integrity, loose bodies, and the status of the MPFL, aiding in surgical planning.
The surgical approach often necessitates addressing both bony and soft tissue contributors to instability. In this case, the combined fixation of the osteochondral fragment with MPFL repair not only restored the anatomy of the patellar surface but also preserved the native cartilage, offering potential long-term joint preservation. Rehabilitation focused on progressive range of motion and muscle strengthening is vital for optimizing functional recovery.
As we continue to understand the complexities of patellar instability in adolescents, it is essential to prioritize timely intervention to prevent further complications and enhance recovery outcomes. This case highlights the importance of a comprehensive evaluation and tailored surgical approach in managing such injuries effectively.
For further information or inquiries, healthcare professionals can contact the specialists involved in this case.
