Don't forget the hip! Hip arthritis masquerading as knee pain.

Background: Hip osteoarthritis typically manifests with groin or thigh pain. Other atypical pain patterns, including knee pain, have been described. Except for 2 case reports, there is no literature on this subject.

Methods: From our institutional database, between 2011 and 2016, we identified 21 patients who were referred for treatment of knee pain but ultimately diagnosed with hip pathology as the cause of their pain. This group was evaluated for duration of symptoms prior to diagnosis, previous interventions, presence of walking aids, and symptom resolution after treatment of the hip pathology.

Results: Fifteen of the 21 patients were referred from musculoskeletal providers (12 from orthopaedic surgeons). Prior to diagnosis of the hip etiology, 16 patients were reduced to major assistive devices including wheelchairs. Twelve of 21 patients had undergone surgical knee interventions, including total knee arthroplasty, with minimal to no relief of their pain. Seventeen of 21 referred patients underwent total hip arthroplasty at our institution. Fourteen patients had complete resolution of knee pain after total hip arthroplasty.

Conclusions: Although knee pain referred from hip disease may be considered a basic and common knowledge, it continues to be an overlooked phenomenon. Most of the cases were misdiagnosed by musculoskeletal providers including orthopaedic surgeons and this highlights the need for continued education and awareness of this clinical scenario.