title: Acquired permanent dislocation of the patella in a patient with rheumatoid genu valgum.
abstract: A case of acquired permanent dislocation of the patella associated with severe genu valgum in a patient with rheumatoid arthritis (RA) is herein reported. The pain and genu valgum progressed because of poor RA control. The patient had no history of major trauma of the knee before or after the onset of RA. The most reasonable hypothesis to explain this patient's pathology is that occult patellar dislocation developed after a minor trauma and progressed to permanent dislocation; poor RA control then worsened both the patellar dislocation and genu valgum. Total knee arthroplasty (TKA) with patella reduction was successfully performed with release of the lateral retinaculum and extension of the extensor mechanism by partial snipping of the rectus femoris tendon. Two years after the operation, the patient exhibited improvement in her Knee Society Knee and Function Scores from preoperative scores of 18 and 20 to postoperative scores of 94 and 80, respectively. Acquired permanent dislocation of the patella associated with severe genu valgum in patients with RA is rare. Excellent results were obtained with TKA, and the proximal realignment method was a useful procedure for patella reduction.
authors.affiliation: Department of Orthopaedic Surgery, Japan Community Healthcare Organization Osaka Hospital, 4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka 553-0003, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Nishikawa
authors.affiliation: Department of Orthopaedic Surgery, Japan Community Healthcare Organization Osaka Hospital, 4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka 553-0003, Japan ; Department of Rheumatology, Japan Community Healthcare Organization Osaka Hospital, 4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka 553-0003, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Owaki
authors.affiliation: Department of Orthopaedic Surgery, Japan Community Healthcare Organization Osaka Hospital, 4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka 553-0003, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Kaneshiro
authors.affiliation: Department of Orthopaedic Surgery, Japan Community Healthcare Organization Osaka Hospital, 4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka 553-0003, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fuji
authors.affiliation: Department of Orthopaedics, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita City, Osaka 565-0871, Japan.
authors.forename: Kenrin
authors.initials: K
authors.lastname: Shi
keywords: Genu valgum; Permanent dislocation of the patella; Rheumatoid arthritis; Total knee arthroplasty