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The impact of body mass index on the accuracy of the physical examination of the knee

Abstract

Purpose

Obesity is a worldwide pandemic; however, no adaptations were made to the physical examination of obese patient’s knees. The accuracy of the physical examination is critical for correct assessment and selection of treatment. We aimed to assess whether body mass index (BMI) affects the sensitivity and specificity of common provocative knee tests.

Methods

We studied 210 patients who underwent knee arthroscopy to treat anterior cruciate ligament (ACL) and meniscal pathologies. BMI and the knee’s physical examination were documented pre-operatively. Sensitivity, specificity, and accuracy of ACL and meniscal provocative tests in relation to BMI were evaluated using arthroscopy as a gold standard.

Results

The Anterior Drawer, Lachman, and Pivot-Shift tests for ACL tears were significantly less accurate and sensitive, yet more specific, in obese patients when compared to normal and overweight patients. The McMurray, Apley Grind, and Thessaly tests for medial meniscus tears showed greater sensitivity, but lower specificity, in patients with increased BMI. Above normal BMIs, independently of age and gender, were significantly associated with higher odds for positive ACL tests.

Conclusion

Tests for ACL tears are less sensitive in obese patients and alternatives to the classic tests should be considered. Medial meniscus tests tend to be more sensitive and less specific in patients with greater BMIs. Their results should be carefully interpreted due to possible false positives. The physician should take into consideration the impact of patient BMI on the accuracy of their physical examination of the knee to optimize treatment decision-making.

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Data availability

The authors declare data is available per request.

References

  1. WHO (2012) Obesity and overweight. https://www.who.int/en/news-room/fact-sheets/detail/obesity-and-overweight. Accessed 2 Jan 2021

  2. Silk AW (2011) Reexamining the physical examination for obese patients. JAMA 305:193. https://doi.org/10.1001/jama.2010.1950

    CAS  Article  PubMed  Google Scholar 

  3. Elbaz A, Debbi EM, Segal G et al (2011) Sex and body mass index correlate with Western Ontario and McMaster Universities Osteoarthritis Index and quality of life scores in knee osteoarthritis. Arch Phys Med Rehabil 92:1618–1623. https://doi.org/10.1016/j.apmr.2011.05.009

    Article  PubMed  Google Scholar 

  4. Hung A, Sayre EC, Guermazi A et al (2016) Association of body mass index with incidence and progression of knee effusion on magnetic resonance imaging and on knee examination. Arthritis Care Res 68:511–516. https://doi.org/10.1002/acr.22714

    Article  Google Scholar 

  5. Salih S, Sutton P (2013) Obesity, knee osteoarthritis and knee arthroplasty: a review. BMC Sports Sci Med Rehabil 5:1–6

    Article  Google Scholar 

  6. Bojicic KM, Beaulieu ML, Imaizumi Krieger DY et al (2017) Association between lateral posterior tibial slope, body mass index, and ACL injury risk. Orthop J Sport Med 5.https://doi.org/10.1177/2325967116688664

  7. Walker JL, Hosseinzadeh P, White H et al (2019) Idiopathic genu valgum and its association with obesity in children and adolescents. J Pediatr Orthop 39:347–352. https://doi.org/10.1097/BPO.0000000000000971

    Article  PubMed  Google Scholar 

  8. Draper DO (1990) A comparison of stress tests used to evaluate the anterior cruciate ligament. Phys Sportsmed 18:89–96. https://doi.org/10.1080/00913847.1990.11709953

    CAS  Article  PubMed  Google Scholar 

  9. Draper DO, Schulthies SS (1995) Examiner proficiency in performing the Anterior Drawer and Lachman tests. J Orthop Sports Phys Ther 22:263–266. https://doi.org/10.2519/jospt.1995.22.6.263

    CAS  Article  PubMed  Google Scholar 

  10. Achtnich A, Petersen W, Willinger L et al (2018) Medial meniscus extrusion increases with age and BMI and is depending on different loading conditions. Knee Surgery, Sport Traumatol Arthrosc 26:2282–2288. https://doi.org/10.1007/s00167-018-4885-7

    Article  Google Scholar 

  11. Vajapey SP, Miller TL (2021) Clinical tests used to diagnose anterior cruciate ligament tears are less sensitive in obese patients: a retrospective cohort study. Curr Orthop Pract 32:6–10. https://doi.org/10.1097/BCO.0000000000000943

    Article  Google Scholar 

  12. Malanga GA, Andrus S, Nadler SF, McLean J (2003) Physical examination of the knee: a review of the original test description and scientific validity of common orthopedic tests. Arch Phys Med Rehabil 84:592–603. https://doi.org/10.1053/apmr.2003.50026

    Article  PubMed  Google Scholar 

  13. de Oliveira FCL, Roy JS, Pappas E (2020) ACL injury, physical activity, and overweight/obesity: a vicious cycle? Knee Surgery. Sport Traumatol Arthrosc 28:667–669

    Article  Google Scholar 

  14. Anandacoomarasamy A, Caterson I, Sambrook P et al (2008) The impact of obesity on the musculoskeletal system. Int J Obes 32:211–222

    CAS  Article  Google Scholar 

  15. Abate M, Salini V, Andia I (2016) How obesity affects tendons? Advances in Experimental Medicine and Biology. Springer, New York LLC, pp 167–177

    Google Scholar 

  16. Ursini F, Naty S, Grembiale RD (2011) Fibromyalgia and obesity: the hidden link. Rheumatol Int 31:1403–1408

    CAS  Article  Google Scholar 

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Authors and Affiliations

Authors

Contributions

RG conceived the study, designed and coordinated it, received institutional board approval, collected materials, and drafted the manuscript. IM carried out the statistical analysis, drafted the manuscript, reported the results, discussed their interpretation, and designed the tables and illustrations. AM collected data and drafted the original manuscript. AL collected data and drafted the original manuscript. OC carried out the statistical analysis and edited and reviewed the final version. DL assisted in study design and editing and review of the manuscript. YB assisted in study conception and supervision, edited and reviewed the final version. AG assisted in study conception and supervision, edited and reviewed the final version.

Corresponding author

Correspondence to Ron Gilat.

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Ethical approval

Institutional review board approval was obtained prior to study initiation.

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Informed consent was not required for this study as per institutional review board approval.

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Informed consent was not required for this study as per institutional review board approval.

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The authors declare no competing interests.

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Gilat, R., Mitchnik, I.Y., Moriah, A. et al. The impact of body mass index on the accuracy of the physical examination of the knee. International Orthopaedics (SICOT) 46, 831–836 (2022). https://doi.org/10.1007/s00264-021-05277-x

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  • DOI: https://doi.org/10.1007/s00264-021-05277-x

Keywords

  • Overweight
  • Obesity
  • Knee
  • Physical examination
  • BMI
  • ACL tear
  • Meniscal tear