title: Navigated open-wedge high tibial osteotomy: advantages and disadvantages compared to the conventional technique in a cadaver study.
abstract: High tibial osteotomy (HTO) is an established therapy for the treatment of symptomatic varus malaligned knees. A main reason for disappointing clinical results after HTO is the under- and overcorrection of the mechanical axis due to insufficient intraoperative visualisation. Twenty legs of fresh human cadaver were randomly assigned to navigated open-wedge HTO (n=10) or conventional HTO using the cable method (n=10). Regardless of the pre-existing alignment, the aim of all operations was to align the mechanical axis to pass through 80% of the tibial plateau (beginning with 0% at the medial edge of the tibial plateau and ending with 100% at the lateral edge). This overcorrection was chosen to ensure a sufficient amount of correction. Thus, the medial proximal tibia angle (MPTA) increased by 9.1+/-2.9 degrees (range 5.2 degrees -12.3 degrees ) on the average after navigated HTO and by 8.9+/-2.9 degrees (range 4.7 degrees -12.6 degrees ) after conventional HTO. After stabilization with a fixed angle implant, the alignment was measured by CT. After navigated HTO, the mechanical axis passed the tibial plateau through 79.7% (range 75.5-85.8%). In contrast, after conventional HTO, the average intersection of the mechanical axis was at 72.1% (range 60.4-82.4%) (P=0.020). Additionally, the variability of the mean corrections was significantly lower in the navigated group (3.3% vs. 7.2%, P=0.012). Total fluoroscopic radiation time was significantly lower in the navigated group (P=0.038) whereas the mean dose area product was not significantly different (P=0.231). The time of the operative procedure was 23 min shorter after conventional HTO (P<0.001). Navigation systems provide intraoperative 3-dimensional real time control of the frontal, sagittal, and transverse axis and may increase the accuracy of open-wedge HTO. Future studies have to analyse the clinical effects of navigation on corrective osteotomies.
authors.affiliation: Trauma Department of Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany. s.hankemeier@t-online.de
authors.forename: S
authors.initials: S
authors.lastname: Hankemeier
authors.forename: T
authors.initials: T
authors.lastname: Hufner
authors.forename: G
authors.initials: G
authors.lastname: Wang
authors.forename: D
authors.initials: D
authors.lastname: Kendoff
authors.forename: J
authors.initials: J
authors.lastname: Zeichen
authors.forename: G
authors.initials: G
authors.lastname: Zheng
authors.forename: C
authors.initials: C
authors.lastname: Krettek
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D011897:Random Allocation; D016059:Range of Motion, Articular; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed