Superior‐lateral patella dislocation with rotation along its vertical axis

Abstract

Background

Patellar dislocations are common, but superior‐lateral dislocation with vertical axis rotation is rare and challenging to reduce.

Case Presentation

A woman in her 20s presented with left knee pain and deformity after minor trauma. Traditional reduction attempts failed due to a vertical rotational component. Reduction was achieved using a technique involving hip flexion, a modified varus–valgus force, and knee extension.

Conclusion

Emergency clinicians must recognize complex patellar dislocations and consider early orthopedic consultation to minimize complications.

A modified reduction technique is essential for successful alignment in superior‐lateral patellar dislocations with vertical rotation. Flexion of the hip, knee extension, and targeted valgus–varus forces facilitate realignment and clear the lateral femoral condyle.

BACKGROUND

Acute lateral patellar dislocations are a common musculoskeletal injury presenting to the emergency department. ¹ Most occur in adolescent females during sporting events or dance and are easily reduced with gentle valgus force and knee extension. ² , ³ However, patellar dislocation treatment becomes more complex with the rotation of the patella along its horizontal or vertical axis. ⁴ Emergency clinicians must be aware of the rotational complexities of patellar dislocations to limit the number of reduction attempts in these cases to reduce morbidity.

CASE PRESENTATION

A young woman with a history of multiple previous patellar instability events in her knees since her teenage years presented to the emergency department with left knee pain. She injured her knee an hour prior to arrival after a friend excitedly jumped into her arms, causing her to fall to the ground. Experienced with previous episodes of patellar instability, the patient attempted to self‐reduce the suspected patella dislocation with passive knee extension but was unsuccessful. On arrival to the emergency department, her left knee was flexed at 45 degrees with the patella dislocated superior‐laterally with skin tenting. She was in obvious discomfort and unable to perform any range of motion due to severe pain. She had preserved distal pulses and intact sensation throughout the extremity. Given the skin tenting and patient distress, the decision was made to perform closed reduction at bedside. One hundred micrograms of fentanyl was given for analgesia and the first attempt at reduction was unsuccessful. After a second attempt failed, knee radiographs were obtained (Figure 1), and the orthopedics team was consulted for reduction assistance.

FIGURE 1.

Sunrise radiograph of the left knee showing superior‐lateral patellar dislocation with outward‐facing articular surface. The measurements shown—40.6° and 139.4°—reflect radiographic distance and angle approximations between anatomical landmarks of the patella and femoral condyle, intended to highlight the severity of malalignment. The patella is positioned lateral to the lateral femoral condyle and has rotated medially approximately 40.6° when viewed in the axial projection. There is an associated avulsion fracture from the inferior aspect of the patella, as well as moderate knee joint effusion.

TREATMENT

The articular surface of the patella faced laterally along with a vertical patella orientation. The orthopedics team was able to successfully reduce the dislocation with a moderate degree of difficulty using hip flexion to relax the quadriceps muscle followed by applying an anteromedial force and providing inversion to the lateral patella to allow it to clear the femoral condyle all while extending the knee.

While open reduction could have been considered earlier, the team proceeded with closed reduction due to the clinical stability of the patient, preserved neurovascular function, and the absence of gross fracture displacement on initial physical exam. The decision was made in collaboration with the orthopedic team, who remained present during the third and ultimately successful attempt. Although radiographs later revealed an inferior patellar avulsion fracture, it was believed that the vertical axis rotation and engagement with the lateral femoral condyle primarily impeded reduction.

CONCLUSION

Post reduction films and physical exam confirmed improved anatomical alignment (Figure 2), although now with a better visualized presence of an associated inferior patellar avulsion fracture. A knee immobilizer was placed, and the patient was sent home with crutches and instructed to remain non‐weight bearing with the plan to follow up with orthopedic surgery in a week for definitive surgical intervention. It is possible the fragment hindered reduction attempts, but after discussing the case with the orthopedic team, the rotational aspect and lateral femoral condyle edge likely obstructed initial reduction attempts. Bony fragments were removed during surgery a month after the injury, and medial patellofemoral ligament reconstruction and a tibial tubercle osteotomy were performed by the orthopedic team. Six months post‐surgery, our patient reports doing well without further left knee complications. At her post‐surgery visit, she demonstrated active knee flexion over 130 degrees, normal patellar tracking, and was without a J sign. She could also perform a straight leg raise without extensor lag. She had no significant tenderness to palpation, and she had no apprehension with lateral patellar translation. Post‐operative x‐rays showed interval placement of tibial screws without hardware complication and improved alignment of patella with bony bridging and callus formation at the patellar fracture fragment (Figure 3).

FIGURE 2.

Post‐reduction sunrise radiograph of the left knee reveals improved alignment after a superior‐lateral patellar dislocation. Arrow indicates inferior patellar avulsion fracture.

FIGURE 3.

Post‐op AP radiograph of the left knee reveals proper placement of tibial screws without any complications related to the hardware.

DISCUSSION

This is a rare case of a young woman with a patellar dislocation rotated along its vertical axis with an inferiorly avulsed comminuted fracture. Our patient had a history of recurrent patellar instability and a physical exam showing lateral skin tenting with patellar malalignment, which allowed for early clinical recognition of this patellar dislocation. Like the few other cases in the literature, our case required multiple attempts of closed reduction before successful patellar alignment was established. ⁵ A literature review by Grewal et al. for irreducible lateral patellar dislocations discussed the rarity of this condition. ⁵ Vertically rotated and locked patellar dislocations are particularly rare, as described in previous case reports and orthopedic case series. ⁶ Pre‐reduction images for lateral patella dislocations are not routinely recommended for laterally displaced patella dislocations. ⁷ In fact, some argue that obtaining pre‐reduction films in pediatric patients with lateral patellar dislocations only prolongs the time to reduction and does not change management, even in the face of concomitant fractures. ³ , ⁸ However, in our case, pre‐reduction films could have decreased the number of reduction attempts. Some studies recommend obtaining a CT scan prior to performing multiple reduction attempts to identify bony loose bodies or other anatomical obstructions to minimize osteochondral damage. ⁵ , ⁸ Our patient had a successful closed reduction on the third attempt despite having a complex patella dislocation involving vertical axis rotation with an inferiorly avulsed comminuted fracture. Overall, this case represents a rare subset type of acute patellar dislocation in which the patella is oriented vertically. This presentation must be recognized by emergency medicine providers because of the increased risk of knee morbidity with multiple unsuccessful closed reductions. When clinicians have concerns for complex patellar dislocations as seen on physical exam as skin tenting or superior‐lateral patella alignment, clinicians should first obtain pre‐reduction x‐rays and second obtain early consultation to orthopedics for definitive management.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflicts of interest.

ETHICS STATEMENT

Approval of the research protocol: N/A.

Informed consent: Obtained from the patient.

Registry and registration no. of the study/trial: N/A.

Animal studies: N/A.

McNeal P, Winton EB, Bartman MT. Superior‐lateral patella dislocation with rotation along its vertical axis. Acute Med Surg. 2025;12:e70078. 10.1002/ams2.70078

DATA AVAILABILITY STATEMENT

Data sharing is not applicable to this article as no new data were created or analyzed in this study.