Knee Surgery, Sports Traumatology, Arthroscopy

KNEE ARTHROPLASTY

Data beats dogma—Valgus knees are not associated with a hypoplastic lateral femoral condyle: A CT-based analysis from a high-volume institution

Corresponding Author

Fabio Mancino

[email protected]

orcid.org/0000-0003-3080-0052

Sydney Orthopaedic Research Institute (SORI), The Knee Institute, St. Leonards, New South Wales, Australia

Correspondence Fabio Mancino, Sydney Orthopaedic Research Institute (SORI), Landmark Orthopaedics, Level 2/500 Pacific Hwy, St. Leonards, NSW, Australia.

Email: [email protected]

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Joshua G. Twiggs,

Joshua G. Twiggs

Enovis the Company—Enovis, Austin, Texas, USA

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Ishaan Jagota,

Ishaan Jagota

Flinders University, Adelaide, South Australia, Australia

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Brett A. Fritsch,

Brett A. Fritsch

Sydney Orthopaedic Research Institute (SORI), The Knee Institute, St. Leonards, New South Wales, Australia

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Fabio Mancino,

Corresponding Author

Fabio Mancino

[email protected]

orcid.org/0000-0003-3080-0052

Sydney Orthopaedic Research Institute (SORI), The Knee Institute, St. Leonards, New South Wales, Australia

Correspondence Fabio Mancino, Sydney Orthopaedic Research Institute (SORI), Landmark Orthopaedics, Level 2/500 Pacific Hwy, St. Leonards, NSW, Australia.

Email: [email protected]

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Joshua G. Twiggs,

Joshua G. Twiggs

Enovis the Company—Enovis, Austin, Texas, USA

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Ishaan Jagota,

Ishaan Jagota

Flinders University, Adelaide, South Australia, Australia

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Brett A. Fritsch,

Brett A. Fritsch

Sydney Orthopaedic Research Institute (SORI), The Knee Institute, St. Leonards, New South Wales, Australia

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First published: 07 May 2025

https://doi.org/10.1002/ksa.12688

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Abstract

Purpose

Observations following the mechanical alignment principle have led to the concept that the lateral femoral condyle (LFC) is hypoplastic in valgus knee. This study aimed to investigate if this assumption is correct—the hypothesis was that there is no relationship between the radius of curvature of the LFC and coronal alignment.

Methods

This is a retrospective study of prospectively collected patients who underwent primary robotic TKA between 2021 and 2023. Segmentation of the preoperative computerised tomography scan was performed to obtain a three-dimensional model of the knee. A semi-automated algorithm was used to create a circle of best fit to obtain the radius of each femoral condyle. The size of the condyles was expressed as the lateral-to-medial (L2M) condylar radii ratio. Patients were stratified based on hip–knee–ankle (HKA) angle and L2M ratio, and the association with the alignment was analysed. Distal and posterior offset were investigated and analysed. Significance was for p values < 0.05.

Results

Overall, 498 consecutive knees were investigated. The mean HKA was 4.1 ± 5.4° varus. The mean L2M condylar ratio was 0.95 in patients with neutral alignment, 0.98 in varus alignment and 0.96 in valgus alignment. The L2M ratio was <1 in all alignment groups, with no significant differences between varus and valgus. The knees with a hypoplastic LFC (L2M ratio <0.9) showed a similar HKA distribution to those with L2M > 0.9. No differences in posterior offset of the LFC were noted between valgus, neutral and varus knees. The lateral distal offset was greater in valgus than neutral knees (27.1 ± 2.7 mm vs. 25.9 ± 2.9 mm).

Conclusion

The LFC is on average smaller than the MFC regardless of the coronal alignment, with no correlation with the HKA. These findings add evidence against the concept of a hypoplastic LFC in valgus knees.

Level of Evidence

Level III, retrospective cohort study.

CONFLICT OF INTEREST STATEMENT

Brett A. Fritsch holds shares in Personalised Surgery, Jointly, and 360 Knee systems; received royalties from ExacTech and Corin; done consulting work for Arthrex, DePuy, ExacTech, Corin; given paid presentations for Arthrex, Global, DePuy, Corin, Smith & Nephew; received institutional support from Smith & Nephew, Zimmer Biomet, Corin, Arthrex, Surgical Specialities. Ishaan Jagota is paid employee of Enovis ANZ, Mathys Orthopaedics (subsidiary of Enovis), 360 Med Care (subsidiary of Enovis). Joshua G. Twiggs is paid employee of Enovis. Fabio Mancino declares no conflict of interest.

Open Research

DATA AVAILABILITY STATEMENT

Data are available under reasonable request.

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Data beats dogma—Valgus knees are not associated with a hypoplastic lateral femoral condyle: A CT-based analysis from a high-volume institution

Abstract

Purpose

Methods

Results

Conclusion

Level of Evidence

CONFLICT OF INTEREST STATEMENT

Open Research

DATA AVAILABILITY STATEMENT

REFERENCES

References

Information

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Data beats dogma—Valgus knees are not associated with a hypoplastic lateral femoral condyle: A CT-based analysis from a high-volume institution

Abstract

Purpose

Methods

Results

Conclusion

Level of Evidence

CONFLICT OF INTEREST STATEMENT

Open Research

DATA AVAILABILITY STATEMENT

REFERENCES

References

Related

Information