Superior dislocation of the patella: a pathognomonic finding and review of literature

Superior Patellar Dislocation Reduced by Intra-articular Injection: A Case Report and Review of Literature

CASE

A 53-year-old woman presented with a locked knee after an atraumatic hyperextension episode. Imaging showed an anterior tilt of the patella hinging over the superior trochlear margin, consistent with a superior patellar dislocation. The patella spontaneously reduced on an intra-articular injection with 15 mL of lidocaine in normal saline, after which she was able to actively range her knee.

CONCLUSION

Superior patellar dislocations are rare and usually result from a sudden forced contraction of the quadriceps, trapping the patella over superior trochlear osteophytes. Reduction is possible through an intra-articular local anesthetic injection, without manipulation of the patella.

[A rare cause of an acutely locked knee joint: superior patellar dislocation]

The case of a 56-year-old male patient with locking of the knee in extension without trauma is presented. Patient history, clinical examination and radiographs confirmed a superior dislocation of the patella. Closed reduction led to full weight bearing with free range of motion without further complaints. Knowledge of this uncommon cause of a locked knee joint leads to immediate treatment avoiding complex imaging modalities, such as computed tomography (CT) or magnetic resonance imaging (MRI). No further treatment was necessary in the majority of the cases published in the literature.

Superior Dislocation of the Patella in a Young Patient without Osteophytes: A Case Report with Discussion about Differential Diagnosis

We report a case of superior dislocation of the patella in a young woman without degenerative changes. We retrospectively analyzed the clinical and imaging data obtained from the patient. This article describes a rare case of patellar dislocation following a bicycle fall in a 19-year-old woman without any history of patellofemoral complaints. Our literature search yielded 28 case reports; however, most reports describe older individuals with osteoarthritis. Only two reports have previously described this lesion in young patients without osteophytes, but some features, like an increase of the patella tilt, may raise doubts about whether it would be better to classify them as a vertical dislocation of the patella, another quite rare lesion, or just as a variant of a superior dislocation.