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Sagittal femoral condylar shape varies along a continuum from spherical to ovoid: a systematic review and meta-analysis

  • Knee Arthroplasty
  • Published:
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Abstract

Introduction

Considerable anatomic variations of sagittal femoral condylar shape have been reported, with a continuum between spherical (or single-radius) and ovoid (or multi-radius) condyles. The purpose of this systematic review and meta-analysis was to critically appraise and synthesise the available literature on the sagittal femoral profile. The hypothesis was that studies would reveal considerable variability among individuals, but also in their methodology to quantify sagittal profiles.

Methods

This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. On 10 September 2021 two authors searched for Level I to IV studies that reported on the sagittal curvature of the medial and/or lateral femoral condyles using the MEDLINE®, EMBASE® and Cochrane Library. Results were summarised by tabulating means, standard deviations and/or ranges for the reported radii-of-curvature, or ellipsoidal semi-major and semi-minor lengths of the condyles. To quantify sagittal ‘ovoidicity’ and asymmetry, results were stratified according to coordinate reference frame (posterior condylar axis (PCA), clinical and surgical transepicondylar axis (cTEA and sTEA), unified sagittal plane (USP), or unclear) and summarised in forest plots as standardised mean differences (SMD).

Results

Thirty-eight articles were eligible for full text extraction, quantifying sagittal radii-of-curvature by best-fit circles (BFC), ellipsoids, polynomials, spherical or cylindrical fitting. Studies with clear definition of the measurement plane revealed that both condyles were generally ovoid, with considerably greater ‘ovoidicity’ at the medial condyle (SMD, 4.09) versus the lateral condyle (SMD, 3.33). In addition, distal condylar radii were greater medially when measured normal to the TEA (cTEA: SMD, 0.81; sTEA: SMD, 0.79), but greater laterally when measured in a USP (SMD, − 0.83). Posterior condylar radii were greater laterally when measured in a USP (SMD, − 0.60).

Conclusion

Studies reported considerable variability of sagittal femoral condylar radii-of-curvature, which are not incremental, but rather a continuum that ranges from spherical to ovoid. Although this variation could be accommodated by single-, dual- and multi-radii femoral components, a surgeon typically uses only one or two TKA designs. Hence, there is a risk of mismatch between the native and prosthetic sagittal profile that could result in mid-flexion ligament imbalance unless other parameters are changed. These findings support the drive towards patient-specific implants to potentially achieve accurate sagittal bone–implant fit through implant customisation.

Level of evidence

IV.

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Acknowledgements

The authors are grateful to Gaëtan Jouen for illustration of Figs. 1, 2 and 4.

Funding

The authors are grateful to "GCS Ramsay Santé pour l’Enseignement et la Recherche" for funding the statistical analysis and manuscript preparation for this study.

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Authors and Affiliations

  1. Centre Orthopédique Santy, Hôpital Privé Jean Mermoz, Ramsay Santé, Lyon, France

    Andreas Dobbelaere, Tarik Aït-Si-Selmi, Lampros Gousopoulos & Michel P. Bonnin

  2. ReSurg SA, Rue Saint-Jean 22, 1260, Nyon, Switzerland

    Jacobus H. Müller & Mo Saffarini

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  1. Andreas Dobbelaere
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Correspondence to Mo Saffarini.

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AD, JHM, LG, and MS, declare that they have no conflicts of interest. TASS reports personal fees from DePuy-Synthes and Symbios, outside the submitted work. MPB reports personal fees from Wright Medical, Integra, DePuy Synthesis, and Symbios, outside the submitted work.

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The study was a systematic review and meta-analysis of published literature and therefore ethical approval by the institutional review board was not required.

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Dobbelaere, A., Müller, J.H., Aït-Si-Selmi, T. et al. Sagittal femoral condylar shape varies along a continuum from spherical to ovoid: a systematic review and meta-analysis. Arch Orthop Trauma Surg 143, 3347–3361 (2023). https://doi.org/10.1007/s00402-022-04613-z

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