Correction of excessive intraarticular varus deformities in total knee arthroplasty is associated with deteriorated postoperative ankle function
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The aim of this study was to demonstrate, whether the degree of limb alignment correction in varus knee osteoarthritis correlated with an increase in ankle symptoms and to define a cut-off value concerning the degree of correction above which to expect ankle problems.
Ninety-nine consecutive patients with preoperative intraarticular varus knee deformities who underwent total knee arthroplasty were retrospectively analyzed. Patients were examined clinically (Knee Society Score, Forgotten Joint Score, Foot Function Index, Range of Motion of the knee and ankle joint, pain scales) as well as radiologically. The mean follow-up time was 57 months.
The degree of operative limb alignment correction strongly correlated with the Foot Function Index (R = 0.91, p < 0.05). Given this, higher degrees of knee malalignment corrections were associated with worse postoperative outcomes in the knee and ankle joint—despite postoperative improved joint line orientations. Subsequently, a cut-off value for arthritic varus deformities (14.5°) could be calculated, above which the prevalence of ankle symptoms increased manifold [OR = 15.6 (3.2–77.2 95% CI p < 0.05)]. Furthermore, ROM restrictions in the subtalar joint were associated with a worse outcome in the ankle joint.
When correcting excessive intraarticular varus knee osteoarthritis, surgeons have to be aware of possible postoperative ankle symptoms and should consider ankle deformities or decreased subtalar ROM before operative procedures.
Level of evidence
KeywordsTotal knee arthroplasty Total knee replacement Ankle joint Osteoarthritis knee Interplay knee ankle
Foot Function Index
Forgotten Joint Score
Hip knee angle
Knee Society Score
Range of motion
Total knee arthroplasty
FG: statistical and data analysis, established the study protocol, wrote the manuscript. RF: data analysis, critical revision of the manuscript. ST: data analysis, critical revision of the manuscript. CP: data analysis, established the study protocol, critical revision of the manuscript. RKZ: data analysis, critical revision of the manuscript. HH: data analysis, established the study protocol, critical revision of the manuscript.
Compliance with ethical standards
Conflict of interest
All authors declare that they have no conflict of interest.
This study was performed without external funding.
This study was carried out according to the laws and ethical standards of the local legal representative body and was approved by the local ethics committee of the Brandenburg state of Germany (approval number AS17(bB)/2015).
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