Abstract
PURPOSE: Knee pain is a common reason for consulting an orthopaedic surgeon. It has a wide variety of aetiology, of which one is hip pathology. This phenomenon is called referred knee pain. While it is well-known, it has not been thoroughly described from the perspective of the knee surgeon. With this observational study, the importance of routinely including clinical examination of the hip during knee examination is highlighted. METHODS: A retrospective analysis was performed of all patients with knee pain who consulted the orthopaedic service for the first time during a period of 1 year. Both self-referred patients and those referred by other physicians were included. A full anamnesis and physical examination of the knee and hip were conducted. If hip pathology was suspected, a referral was made to a hip surgeon. Treatment was provided accordingly. A subjective improvement in pain or, when available, a ≥50% reduction in visual analogue scale score was considered a positive diagnosis of 'referred knee pain'. RESULTS: Of the 1000 patients presenting for first-time consultation, 185 (18.5%) were referred to hip specialists for further assessment. Among the referred patients, 157 (84.9%) were found to have hip pathology, while 27 (14.6%) exhibited a combined hip and knee pathology. The most prevalent diagnoses included femoroacetabular impingement (22.9%) and osteoarthritis (58%). The predominant treatment modalities consisted of total hip arthroplasty (7.8%), physiotherapy (29.9%), and corticosteroid injections (54.1%). Referred knee pain was diagnosed in 137 (13.7%) of the cohort, with a higher prevalence in females (15.2% vs. 11.8% in males; p = 0.03). CONCLUSION: With 13.7% of knee pain patients presenting with an underlying hip pathology, referred knee pain is a common and often overlooked phenomenon in the daily practice of a full-time knee surgeon. A complete history and physical examination including the hip is obligatory for every knee exam. LEVEL OF EVIDENCE: Level III, retrospective observational cohort study.