Abstract
Purpose
The femoral component should be implanted parallel to the mechanical axis in unicompartmental knee arthroplasty. It was hypothesised that a line between medial femoral condyle centres and medial border of femoral head will be parallel to the mechanical axis; this study set out to examine this hypothesis.
Methods
One hundred X-rays in fifty patients were included for this study. Long-leg standing X-rays including hip and ankle with patellae facing forwards were obtained. On these films, we measured the angle, α, between mechanical axis and the line between the femoral head centre and knee centre (medial mechanical axis), and the angle, β, between the medial mechanical axis and a line between medial femoral condyle and femoral head centre.
Results
The average value of α was 0.1 ± 0.5° and the average value of β 3.0° ± 0.3°. These data indicate that mechanical axis and medial mechanical axis are virtually parallel to each other.
Conclusion
As medial femoral head border is easily identified fluoroscopically, it is a reliable landmark for orientating the femoral component of medial UKA.
Level of evidence
Case series with no comparison group, Level IV.
References
Bonner TJ, Eardley WGP, Patterson P, Gregg PJ (2011) The effect of post-operative mechanical axis alignment on the survival of primary total knee replacements after a follow-up of 15 years. J Bone Joint Surg Br 93:1217–1222
Bonutti PM, Dethmers D, Ulrich SD, Seyler TM, Mont MA (2008) Computer navigation assisted versus minimally invasive TKA: benefits and drawbacks. Clin Orthop Relat Res 466:2756–2762
Carr A, Keyes G, Miller R, O’Connor J, Goodfellow J (1993) Medial unicompartmental arthroplasty. A survival study of the Oxford meniscal knee. Clin Orthop Relat Res 295:205–213
Choong PF, Dowsey MM, Stoney JD (2009) Does accurate anatomical alignment result in better function and quality of life? A prospective randomized controlled trial comparing conventional and computer-assisted total knee arthroplasty. J Arthroplasty 24:560–569
Gulati A, Chau R, Simpson DJ, Dodd CA, Gill HS, Murray DW (2009) Influence of component alignment on outcome for unicompartmental knee replacement. Knee 16:196–199
Gulati A, Chau R, Pandit HG, Gray H, Price AJ, Dodd CA, Murray DW (2009) The incidence of physiological radiolucency following Oxford unicompartmental knee replacement and its relationship to outcome. J Bone Joint Surg Br 91:896–902
Jenny JY, Boeri C (2002) Accuracy of implantation of a unicompartmental total knee arthroplasty with 2 different instrumentations: a case-controlled comparative study. J Arthroplasty 17:1016–1020
Kennedy WR, White RP (1987) Unicompartmental arthroplasty of the knee. Postoperative alignment and its influence on overall results. Clin Orthop Relat Res 221:278–285
Kort NP, van Raay JJAM, Thomassen BJW (2007) Alignment of the femoral component in a mobile-bearing unicompartmental knee arthroplasty: a study in 10 cadaver femora. Int Orthop 31:315–319
Landis JR, Koch GG (1977) The measurement of observer agreement for categorical data. Biometrics 33:159–174
Longstaff LM, Sloan K, Stamp N, Scaddan M, Beaver R (2009) Good alignment after total knee arthroplasty leads to faster rehabilitation and better function. J Arthroplasty 24:570–578
Moreland JR, Bassett LW, Hanker GJ (1987) Radiographic analysis of the axial alignment of the lower extremity. J Bone Joint Surg Am 69:745–749
Sikorski JM (2008) Alignment in total knee replacement. J Bone Joint Surg Br 90:1121–1127
Whiteside LA, McCarthy DS (1992) Laboratory evaluation of alignment and kinematics in a unicompartmental knee arthroplasty inserted with intramedullary instrumentation. Clin Orthop Relat Res 274:238–247
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Hiranaka, T., Pandit, H., Gill, H.S. et al. Medial femoral head border is a reliable and reproducible reference for axis determination for femoral component of unicompartmental knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 21, 2442–2446 (2013). https://doi.org/10.1007/s00167-012-2227-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00167-012-2227-8