Aim

To review the results of patients who underwent fixation of complex proximal femur fractures using the Proximal Femur Locking Plates (PFP) and analyse causes of failure of PFP.

Introduction: The management of the acutely locked knee remains controversial. The incidence of ‘benign’ causes for an acutely locked knee that do not require surgical intervention is perhaps greater than is generally appreciated.

Aim: To study the features of the acutely locked knee, identifying which features are predictive of the cause of the locking.

Patients: Consecutive patients presenting with an acutely locked knee for Orthopaedic consultation were included in the study.

Methods: A prospective cross-sectional study was undertaken to observe the management of acutely locked knees.

Results: To date, forty patients presenting with acutely locked knees have been studied. Thirty-eight underwent examination and arthroscopy under general anaesthesia. 85% of patients were found to have distinct pathology causing a mechanical block to full extension. Eight percent were found to have only degenerative change and two patients unlocked without any surgical intervention. In those patients found to have a mechanical block to extension, consistent features of a definitive injury, joint line tenderness and the presence of an effusion were strongly predictive. We are currently evaluating an algorithm for the pre-operative prediction of remediable mechanical causes of locking.

Discussion: We suggest that patients presenting with acutely locked knees due to a non-mechanical cause can be identified consistently based upon the history and examination alone.