title: The correct rotation of the femoral component in patellofemoral replacement: a laboratory assessment of a surgical technique.
abstract: Ensuring correct rotation of the femoral component   is a challenging aspect of patellofemoral replacement surgery. Rotation   equal to the epicondylar axis or marginally more external rotation   is acceptable. Internal rotation is associated with poor outcomes.   This paper comprises two studies evaluating the use of the medial   malleolus as a landmark to guide rotation. We used 100 lower-leg anteroposterior radiographs to evaluate   the reliability of the medial malleolus as a landmark. Assessment   was made of the angle between the tibial shaft and a line from the   intramedullary rod entry site to the medial malleolus. The femoral   cut was made in ten cadaver knees using the inferior tip of the   medial malleolus as a landmark for rotation. Rotation of the cut   relative to the anatomical epicondylar axis was assessed using CT.   The study of radiographs found the position of the medial malleolus   relative to the tibial axis is consistent. Using the inferior tip   of the medial malleolus in the cadaver study produced a mean external   rotation of 1.6° (0.1° to 3.7°) from the anatomical epicondylar   axis. Using the inferior tip of the medial malleolus to guide the   femoral cutting jig avoids internal rotation and introduces an acceptable   amount of external rotation of the femoral component.
authors.affiliation: Bristol Royal Infirmary, Orthopaedic Department, Queen's Building, Marlborough Street, Bristol BS2 8HY, UK. clarkdamian@hotmail.com
authors.forename: D A
authors.initials: DA
authors.lastname: Clark
authors.forename: N
authors.initials: N
authors.lastname: Upadhyay
authors.forename: G
authors.initials: G
authors.lastname: Gillespie
authors.forename: C
authors.initials: C
authors.lastname: Wakeley
authors.forename: J D
authors.initials: JD
authors.lastname: Eldridge
mesh_terms: D000843:Ankle Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D002102:Cadaver; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D057071:Patellofemoral Joint / Q000601:surgery*; D015203:Reproducibility of Results; D012399:Rotation; D013977:Tibia / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed