Appropriate sagittal femoral component alignment cannot be ensured by intramedullary alignment rods

Knee Surg Sports Traumatol Arthrosc (2016) 24:24532460 DOI 10.1007/s00167-015-3541-8

KNEE

http://crossmark.crossref.org/dialog/?doi=10.1007/s00167-015-3541-8&domain=pdf

Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00167-015-3541-8&domain=pdf

Web End = Appropriate sagittal femoral component alignment cannot be ensured by intramedullary alignment rods

Gnther Maderbacher Jens Schaumburger Clemens Baier Florian Zeman HansRobert Springorum AnneMaria Birkenbach

Joachim Grifka Armin Keshmiri

Abstract

Purpose The intraoperative sagittal cutting block alignment when intramedullary alignment rods are used was investigated. Its absolute orthogonal orientation in relation to the mechanical femoral axis should be analysed. It was hypothesized that (1) alignment rods do not ensure a desired deviation within a range between 0 and 3 exion as it has been shown to be favourable for clinical and functional outcome. Further, the degree of exion cannot be (2) foreseen by the surgeon or (3) estimated by clinical or radiological parameters.

Methods Forty knees allocated to total knee arthroplasty were included. The distal femoral cutting block was aligned using an intramedullary rod. By means of a navigation device, the sagittal alignment of the cutting block in degrees of exion was measured.

Results The mean measured exion of the cutting block was 4.4 (3.6 SD). Twenty-ve per cent (10/40) of the values were within a corridor between 0 and 3 of exion. The mean difference between expected and measured exion was 1.5 (7.6 to 4.7 95 % limits of agreement).

The dorsoventral diameter of the distal femur showed a signicant inuence on measured exion (R2 = 0.112,

p = 0.035).

Conclusion Intramedullary alignment rods used in the present study do not ensure a distal cutting block alignment

G. Maderbacher (*) J. Schaumburger C. Baier H.-R. Springorum A.-M. Birkenbach J. Grifka A. Keshmiri Department of Orthopaedic Surgery, University of Regensburg, Regensburg, Germanye-mail: [email protected]

F. Zeman

Center of Clinical Studies, University of Regensburg, Regensburg, Germany

Received: 28 September 2014 / Accepted: 9 February 2015 / Published online: 15 February 2015 European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2015

between 0 and 3 of exion in relation to the femoral mechanical axis. The extent of exion could not be foreseen either by the surgeon. The dorsoventral diameter of the distal femur correlated with measured exion. However, only limited data is available on inuence of femoral component exion on implant failure or clinical and functional outcome.

Level of evidence...