title: Fabella Syndrome as an Uncommon Cause of Posterolateral Knee Pain after Total Knee Arthroplasty: A Case Report and Review of the Literature.
abstract: The fabella is a sesamoid bone that is located in the lateral head of the gastrocnemius muscle and has been identified on magnetic resonance imaging in 31% of Japanese people. In the present case, a 65-year-old woman experienced posterolateral knee pain, accompanied by a clicking "sound" during active knee flexion, after undergoing total knee arthroplasty for knee osteoarthritis. Eight months of conservative therapy failed to produce an improvement, with progressive osteoarthritic change of the fabella identified on plain radiography. Based on this evidence, a diagnosis of fabella syndrome was made and the patient underwent a fabellectomy. Fabellectomy provided immediate resolution of posterolateral knee pain and the clicking sound with knee flexion, with the patient remaining symptom-free 18 months after fabellectomy and with no limitations in knee function. Fabellectomy eliminated symptoms in all of five case reports that have been previously published and is regarded as an effective first choice for treating fabella syndrome after total knee arthroplasty.
authors.affiliation: Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Okano
authors.affiliation: Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan; Division of Regenerative Medicine for Musculoskeletal System, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Tomokazu
authors.identifier: 0000-0001-8687-4582
authors.initials: T
authors.lastname: Yoshioka
authors.affiliation: Department of Orthopaedic Surgery, Kikkoman General Hospital, 100 Miyazaki, Noda, Chiba 278-0005, Japan.
authors.forename: Takaji
authors.initials: T
authors.lastname: Yanai
authors.affiliation: Department of Orthopaedic Surgery, Kikkoman General Hospital, 100 Miyazaki, Noda, Chiba 278-0005, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Kohyama
authors.affiliation: Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kanamori
authors.affiliation: Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Yamazaki
authors.affiliation: Department of Orthopaedic Surgery, Kikkoman General Hospital, 100 Miyazaki, Noda, Chiba 278-0005, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Tanaka