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Phenotyping of hip–knee–ankle angle in young non-osteoarthritic knees provides better understanding of native alignment variability

  • Michael T. HirschmannEmail author
  • Silvan Hess
  • Henrik Behrend
  • Felix Amsler
  • Vincent Leclercq
  • Lukas B. Moser
KNEE

Abstract

Purpose

There is a lack of knowledge about the native coronal knee alignment in 3D. The currently used classification system (neutral, valgus and varus) oversimplifies the coronal knee alignment. The purpose of this study was therefore (1) to investigate the coronal knee alignment in non-osteoarthritic knees using 3D-reconstructed CT images and (2) to introduce a classification system for the overall knee alignment based on phenotypes.

Methods

The hospital registry was searched for patients younger than 45 years and older than 16, who received a CT according to the Imperial Knee Protocol. Patients with prosthesis, osteoarthritis, fractures or injury of the collateral ligaments were excluded. Finally, 308 non-osteoarthritic knees of 160 patients remained (102 males and 58 females, mean age ± standard deviation (SD) 30 ± 7 years). The overall lower limb alignment was defined as the hip–knee–ankle angle (HKA), which is formed by lines connecting the centers of the femoral head, the knee and the talus. The angle was measured using a commercially planning software (KneePLAN 3D, Symbios, Yverdon les Bains, Switzerland). Descriptive statistics, such as means, ranges, and measures of variance (e.g., standard deviations) are presented. Based on these results, the currently used classification system was evaluated and a new system, based on phenotypes, was introduced. These phenotypes consist of a phenotype-specific mean value (a HKA value) and cover a range of ± 1.5° from this mean (e.g., 183° ± 1.5°). The mean values represent 3° increments of the angle starting from the overall mean value (mean HKA = 180°; 3° increments = 183° and 177°, 186° and 174°). The distribution of these limb phenotypes was assessed.

Results

The overall mean HKA was 179.7° ± 2.9° varus and values ranged from 172.6° varus to 187.1° valgus. The mean HKA values for male and female were 179.2° ± 2.8° and 180.5° ± 2.8°, respectively, which implied a significant gender difference (r2 = 0.23). The most common limb phenotype in males was NEUHKA0° (36.4%), followed by VARHKA3° (29.2%) and VALHKA3° (23.1%). The most common limb phenotype in females was NEUHKA0° (36.4%), followed by VALHKA3° (22.1%) and VARHKA3° (15.0%).

Conclusion

The measurements using 3D-reconstructed CT images confirmed the great variability of the overall lower limb alignment in non-osteoarthritic knees. However, the currently used classification system (neutral, varus, valgus) oversimplifies the coronal alignment and therefore the introduced classification system, based on limb phenotypes, should be used. This will help to better understand individual coronal knee alignment.

Level of evidence

Level III, retrospective cohort study.

Keywords

Knee Native Alignment Classification Phenotype CT Coronal HKA Hip–knee–ankle angle 

Abbreviations

CT

Computed tomography

FMA

Femoral mechanical angle

HKA

Hip–knee–ankle angle

HDP

Hydroxymethane diphosphonate

NEU

Neutral

OA

Osteoarthritis

SD

Standard deviation

SPECT

Single-photon emission computed tomography

TMA

Tibial mechanical angle

TKA

Total knee arthroplasty

VAL

Valgus

VAR

Varus

Notes

Funding

The statistical analysis was funded by Symbios, Yverdon les Bains, Switzerland.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All investigations were conducted in conformity with ethical principles of research and that institutional approval of the human protocol for this investigation was obtained.

Informed consent

Informed consent for participation in the study was obtained.

References

  1. 1.
    Bellemans J, Colyn W, Vandenneucker H, Victor J (2012) The Chitranjan Ranawat award: is neutral mechanical alignment normal for all patients? The concept of constitutional varus. Clin Orthop Relat Res 470:45–53CrossRefGoogle Scholar
  2. 2.
    Cooke D, Scudamore A, Li J, Wyss U, Bryant T et al (1997) Axial lower-limb alignment: comparison of knee geometry in normal volunteers and osteoarthritis patients. Osteoarthr Cartil 5:39–47CrossRefGoogle Scholar
  3. 3.
    Eckhoff DG, Bach JM, Spitzer VM, Reinig KD, Bagur MM et al (2005) Three-dimensional mechanics, kinematics, and morphology of the knee viewed in virtual reality. J Bone Jt Surg Am 87(Suppl 2):71–80Google Scholar
  4. 4.
    Gbejuade HO, White P, Hassaballa M, Porteous AJ, Robinson JR et al (2014) Do long leg supine CT scanograms correlate with weight-bearing full-length radiographs to measure lower limb coronal alignment? Knee 21:549–552CrossRefGoogle Scholar
  5. 5.
    Henckel J, Richards R, Lozhkin K, Harris S, Rodriguez y Baena FM et al (2006) Very low-dose computed tomography for planning and outcome measurement in knee replacement. The imperial knee protocol. J Bone Jt Surg Br 88:1513–1518CrossRefGoogle Scholar
  6. 6.
    Hirschmann A, Buck FM, Fucentese SF, Pfirrmann CWA (2015) Upright CT of the knee: the effect of weight-bearing on joint alignment. Eur Radiol 25:3398–3404CrossRefGoogle Scholar
  7. 7.
    Hirschmann MT, Konala P, Amsler F, Iranpour F, Friederich NF et al (2011) The position and orientation of total knee replacement components: a comparison of conventional radiographs, transverse 2D-CT slices and 3D-CT reconstruction. J Bone Jt Surg Br 93:629–633CrossRefGoogle Scholar
  8. 8.
    Hovinga KR, Lerner AL (2009) Anatomic variations between Japanese and Caucasian populations in the healthy young adult knee joint. J Orthop Res 27:1191–1196CrossRefGoogle Scholar
  9. 9.
    Hsu RWW, Himeno S, Coventry MB, Chao EYS (1990) Normal axial alignment of the lower extremity and load-bearing distribution at the knee. Clin Orthop Relat Res 255:215–227Google Scholar
  10. 10.
    Jabalameli M, Moghimi J, Yeganeh A, Nojomi M (2015) Parameters of lower extremities alignment view in Iranian adult population. Acta Med Iran 4:122–127Google Scholar
  11. 11.
    Jenny J-Y, Boeri C, Ballonzoli L (2005) Coronal alignment of the lower limb. Acta Orthop 76:403–407CrossRefGoogle Scholar
  12. 12.
    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 Arthroplast 24:570–578CrossRefGoogle Scholar
  13. 13.
    Lotke PA, Ecker ML (1977) Influence of positioning of prosthesis in total knee replacement. J Bone Jt Surg Am 59:77–79CrossRefGoogle Scholar
  14. 14.
    Moreland JR, Bassett LW, Hanker GJ (1987) Radiographic analysis of the axial alignment of the lower extremity. J Bone Jt Surg Am 69:745–749CrossRefGoogle Scholar
  15. 15.
    Sailhan F, Jacob L, Hamadouche M (2017) Differences in limb alignment and femoral mechanical-anatomical angles using two dimension versus three dimension radiographic imaging. Int Orthop 41:2009–2016CrossRefGoogle Scholar
  16. 16.
    Shetty GM, Mullaji A, Bhayde S, Nha KW, Oh HK (2014) Factors contributing to inherent varus alignment of lower limb in normal Asian adults: role of tibial plateau inclination. Knee 21:544–548CrossRefGoogle Scholar
  17. 17.
    Song M-H, Yoo S-H, Kang S-W, Kim Y-J, Park G-T et al (2015) Coronal alignment of the lower limb and the incidence of constitutional varus knee in Korean females. Knee Surg Relat Res 27:49–55CrossRefGoogle Scholar
  18. 18.
    Tanaka T, Takayama K, Hashimoto S, Kanzaki N, Hayashi S et al (2017) Radiographic analysis of the lower limbs using the hip–calcaneus line in healthy individuals and in patients with varus knee osteoarthritis. Knee 24:1146–1152CrossRefGoogle Scholar
  19. 19.
    Tang WM, Zhu YH, Chiu KY (2000) Axial Alignment of the lower extremity in Chinese adults. J Bone Jt Surg Am 82:1603–1608CrossRefGoogle Scholar
  20. 20.
    Than P, Szuper K, Somoskeöy S, Warta V, Illés T (2012) Geometrical values of the normal and arthritic hip and knee detected with the EOS imaging system. Int Orthop 36:1291–1297CrossRefGoogle Scholar
  21. 21.
    Thienpont E, Schwab PE, Cornu O, Bellemans J, Victor J (2017) Bone morphotypes of the varus and valgus knee. Arch Orthop Trauma Surg 137:393–400CrossRefGoogle Scholar
  22. 22.
    Moser LB, Hess S, Amsler F, Behrend H, Hirschmann MT (2019) Native non-osteoarthritic knees have a highly variable coronal alignment: a systematic review. Knee Surg Sports Traumatol Arthrosc.  https://doi.org/10.1007/s00167-019-05417-2 Google Scholar

Copyright information

© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2019

Authors and Affiliations

  1. 1.Department of Orthopaedic Surgery and TraumatologyKantonsspital Baselland (Bruderholz, Liestal, Laufen)BruderholzSwitzerland
  2. 2.University of BernBernSwitzerland
  3. 3.University of BaselBaselSwitzerland
  4. 4.Department of Orthopaedic SurgeryKantonsspital St. GallenSt. GallenSwitzerland
  5. 5.Amsler ConsultingBaselSwitzerland
  6. 6.SymbiosYverdon les BainsSwitzerland

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