Abstract
Introduction: Anterior knee pain is a commonly encountered orthopaedic symptom. Textbooks list a number of clinical symptoms and physical signs that are specific for the PF joint in the assessment of the patient with knee pain. Radiological evaluation of the PF joint is rarely helpful. The authors have investigated the value of these symptoms and signs in predicting the presence of PF pathology.
Patients and Methods: All patients presenting for diagnostic knee arthroscopy were enrolled prospectively. A detailed proforma was completed with each patient pre-operatively recording the presence or absence of specific PF symptoms and clinical signs. A blinded independent observer recorded the operative findings of the PF joint, the presence / absence of a plica and / or anterior synovitis. Chondromalacia (CM) was graded using the Outerbridge classification and grade 2 or greater was considered a positive finding.
Pre-operative symptoms and signs were correlated with arthroscopic findings and their positive predictive value (PPV) was determined.
Results: Thirty patients were enrolled over a 2-month period. Pure anterior knee pain was present in 10 patients. The remainder had medial (15), lateral (2) or generalised pain (3). 20 of the thirty patients had degenerative changes in the PF joint. One patient had a plica and no patients had significant anterior synovitis. 20 of the 30 patients had pathological findings elsewhere in their joint.
In the prediction of PF degenerative changes, the PPV of symptoms exacerbated by squatting was 0.53; stairs – 0.55; kneeling – 0.57; rising from low chair – 0.6 and night pain – 0.5.
Analysis of specific signs in predicting PF changes showed that the PPV of PF crepitus was 0.5; pain exacerbated by patellar compression 0.6; and patellar facet compression was 0.62.
Conclusion: Degenerative changes of the PF joint are common in our patient population. The value of knee arthroscopy in patients with isolated PF symptoms is questionable. Our assessment of these patients with specific questions and physical signs has been shown to have a low PPV in predicting ultimate arthroscopic findings in the PF joint.
The abstracts were prepared by Emer Agnew. Correspondence should be addressed to Irish Orthopaedic Association, Secretariat, c/o Cappagh National Orthopaedic Hospital, Finglas, Dublin 11, Ireland.
