title: A comparison of radiological and computer navigation measurements of lower limb coronal alignment before and after total knee replacement.
abstract: We compared lower limb coronal alignment measurements   obtained pre- and post-operatively with long-leg radiographs and   computer navigation in patients undergoing primary total knee replacement   (TKR). A series of 185 patients had their pre- and post-implant   radiological and computer-navigation system measurements of coronal alignment   compared using the Bland-Altman method. The study included 81 men   and 104 women with a mean age of 68.5 years (32 to 87) and a mean   body mass index of 31.7 kg/m(2) (19 to 49). Pre-implant   Bland-Altman limits of agreement were -9.4° to 8.6° with a repeatability   coefficient of 9.0°. The Bland-Altman plot showed a tendency for the   radiological measurement to indicate a higher level of pre-operative   deformity than the corresponding navigation measurement. Post-implant   limits of agreement were -5.0° to 5.4° with a repeatability coefficient   of 5.2°. The tendency for valgus knees to have greater deformity   on the radiograph was still seen, but was weaker for varus knees.  The alignment seen or measured intra-operatively during TKR is   not necessarily the same as the deformity seen on a standing long-leg   radiograph either pre- or post-operatively. Further investigation   into the effect of weight-bearing and surgical exposure of the joint   on the mechanical femorotibial angle is required to enable the most appropriate   intra-operative alignment to be selected.
authors.affiliation: Clinique la Compassion, 8 Rue de la Charite, 52200 Langres, France.
authors.forename: N M J
authors.initials: NM
authors.lastname: Willcox
authors.forename: J V
authors.initials: JV
authors.lastname: Clarke
authors.forename: B R K
authors.initials: BR
authors.lastname: Smith
authors.forename: A H
authors.initials: AH
authors.lastname: Deakin
authors.forename: K
authors.initials: K
authors.lastname: Deep
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging*; D007867:Leg Bones / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009929:Organ Size; D011184:Postoperative Period; D011187:Posture; D011859:Radiography; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted