A 17-year-old male with a remote past medical history of three prior right patellar dislocations presented to our emergency department (ED) with a first-time locked left lateral patellar dislocation after pivoting on his left foot during a football game. He underwent a failed attempt at a reduction at the time of the injury by the on-field attending orthopedic physician. The patient was transported to the ED in an ambulance due to the inability to transport him off the field because of his high BMI (body mass index). En route to the ED, he was given nebulized ketamine and temporarily splinted in situ by emergency medical services. In the ED, the splint was removed, radiographs were obtained, and the patient underwent two further failed closed reduction attempts by the ED physician after being given IV fentanyl and nebulized ketamine. At this time, orthopedics was consulted for further management. On examination, the patient had an immobile left knee fixed at 10 degrees of flexion, was neurovascularly intact with no other injuries, and had a patella that remained rigidly fixed in a dislocated position with gentle manipulation. His height and weight were 165 cm and 140.6 kg, respectively (a BMI of 51.6). Radiographs demonstrated a laterally displaced left patellar dislocation (Figures 1, 2).
At this time, a modified sunrise view of the left patella and a sunrise view of the right patella (for comparison) were obtained. Careful evaluation of the sunrise views demonstrated a medial avulsion fracture of the patella with hinging of the patella on the lateral trochlear ridge via an acute impacted medial patellar defect (Figures 3-5).
The patient was then consciously sedated with IV ketamine to assure adequate relaxation of the musculature and a further closed reduction attempt in the ED. Under conscious sedation, the patella remained rigidly fixed against the initial anteromedial relocation force with the knee fully extended. This maneuver would have normally reduced a typical patella dislocation but was unsuccessful. Therefore, this novel technique was employed: with the application of a firm superolateral force with the knee extended, the patella readily unlocked, and a subsequent superomedial force reduced the injury. Subsequent post-reduction exam under sedation was improved and displayed a ligamentously stable knee that had regained full mobility; although it displayed lateral tilt, it was found to track within the trochlea with knee flexion under sedation and was confirmed on the intra-sedation sunrise view with mini-c-arm fluoroscopy (Figure 6).
The patient was placed in a hinged knee brace locked in extension. Subsequent post-reduction treatment included computed tomography (patient or guardian declined acute MRI for soft tissue evaluation, due to ER wait times), which confirmed reduction, the lack of unrecognized fractures or intra-articular osseous bodies, the lack of previously unrecognized soft tissue injury, and better characterized the previously appreciated medial avulsion fracture and impaction defect of the patella (Figure 7).
Based on patient and family preference, no other acute treatments were conducted, and he was discharged to follow-up in the clinic for further treatment; clinic follow-up had not occurred at the time of manuscript submission, and therefore concomitant acute soft tissue injuries are currently not known.