Elsevier

Injury

Volume 31, Issue 7, 1 September 2000, Pages 543-545
Injury

Case report
Superior dislocation of the patella — a rare but important differential diagnosis of acute knee pain — a case report and review of the literature

https://doi.org/10.1016/S0020-1383(00)00023-1Get rights and content

Introduction

Superior dislocation of the patella is a rare, but important, differential diagnosis of acute knee pain, which is important to recognise early to avoid unnecessary pain for the patient and incorrect management. We present a case report and review of the literature.

Section snippets

Case report

A 55 year old bus driver, presented with severe left knee pain. Whilst on a step ladder he felt the left knee ‘give way’, and was unable to move it. He had multiple excisions and bone grafting of a recurrent giant cell tumour of the left medial proximal tibia 12 years previously, and was awaiting a total knee replacement. The patella appeared superiorly displaced and tilted, leaving a hollowing in the infra-patellar region (Fig. 1).

He would not allow the knee to be flexed. A-P and lateral plain

Comment

By far the most common dislocation of the patella is in a lateral direction. This is recognized by a lateral lying patella and haemarthrosis [1], confirmed by X-ray, including a tangential view to exclude any large osteochondral fractures.

However, there are other types of patellar dislocation which are important to recognise. Intra-articular [2], inferior [3], and superior [1] dislocations have all been described.

Intra-articular dislocations usually occur in adolescent boys, and involve the

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