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Clinical Orthopaedics and Related Research®

, Volume 470, Issue 1, pp 45–53 | Cite as

The Chitranjan Ranawat Award: Is Neutral Mechanical Alignment Normal for All Patients?: The Concept of Constitutional Varus

  • Johan Bellemans
  • William Colyn
  • Hilde Vandenneucker
  • Jan Victor
Symposium: Papers Presented at the Annual Meetings of The Knee Society

Abstract

Background

Most knee surgeons have believed during TKA neutral mechanical alignment should be restored. A number of patients may exist, however, for whom neutral mechanical alignment is abnormal. Patients with so-called “constitutional varus” knees have had varus alignment since they reached skeletal maturity. Restoring neutral alignment in these cases may in fact be abnormal and undesirable and would likely require some degree of medial soft tissue release to achieve neutral alignment.

Questions/purposes

We investigated what percentage of the normal population has constitutional varus knees and what are the contributing factors.

Subjects and Methods

We recruited a cohort of 250 asymptomatic adult volunteers between 20 and 27 years old for this cross-sectional study. All volunteers had full-leg standing digital radiographs on which 19 alignment parameters were analyzed. The incidence of constitutional varus alignment was determined and contributing factors were analyzed using multivariate prediction models.

Results

Thirty-two percent of men and 17% of women had constitutional varus knees with a natural mechanical alignment of 3° varus or more. Constitutional varus was associated with increased sports activity during growth, increased femoral varus bowing, an increased varus femoral neck-shaft angle, and an increased femoral anatomic mechanical angle.

Conclusions

An important fraction of the normal population has a natural alignment at the end of growth of 3° varus or more. This might be a consequence of Hueter-Volkmann’s law. Restoration of mechanical alignment to neutral in these cases may not be desirable and would be unnatural for them.

Level of Evidence

Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Keywords

Mechanical Alignment Varus Alignment Cortical Width Neutral Alignment Medial Proximal Tibial Angle 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

The authors thank Myrthe Boymans for her illustrations included in this manuscript. The statistical analysis was performed by the Biostatistical Centre of the School of Public Health of the Catholic University Leuven.

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Copyright information

© The Association of Bone and Joint Surgeons® 2011

Authors and Affiliations

  • Johan Bellemans
    • 1
    • 2
  • William Colyn
    • 2
  • Hilde Vandenneucker
    • 2
  • Jan Victor
    • 2
  1. 1.Department of Orthopaedic SurgeryUniversity Hospital PellenbergPellenbergBelgium
  2. 2.Department of Orthopaedic SurgeryUniversity Hospitals of the Catholic University LeuvenLeuvenBelgium

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