Open MRI assessment of anterior femoroacetabular clearance in active and passive impingement-provoking postures

Maryam Mohtajeb; Jolanda Cibere; Michelle Mony; Honglin Zhang; Emily Sullivan; Michael A Hunt; David R Wilson

doi:10.1302/2633-1462.211.BJO-2021-0143

Open MRI assessment of anterior femoroacetabular clearance in active and passive impingement-provoking postures

Bone Jt Open. 2021 Nov;2(11):988-996. doi: 10.1302/2633-1462.211.BJO-2021-0143.

Authors

Maryam Mohtajeb^{1

2}, Jolanda Cibere^{3

4}, Michelle Mony³, Honglin Zhang², Emily Sullivan², Michael A Hunt^{5

6}, David R Wilson^{2

7}

Affiliations

¹ School of Biomedical Engineering, University of British Columbia, Vancouver, British Columbia, Canada.
² Center for Hip Health and Mobility, University of British Columbia, Vancouver, British Columbia, Canada.
³ Arthritis Research Centre of Canada, Richmond, British Columbia, Canada.
⁴ Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
⁵ Motion Analysis and Biofeedback Laboratory, University of British Columbia, Vancouver, British Columbia, Canada.
⁶ Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada.
⁷ Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada.

PMID: 34825828
PMCID: PMC8636292
DOI: 10.1302/2633-1462.211.BJO-2021-0143

Abstract

Aims: Cam and pincer morphologies are potential precursors to hip osteoarthritis and important contributors to non-arthritic hip pain. However, only some hips with these pathomorphologies develop symptoms and joint degeneration, and it is not clear why. Anterior impingement between the femoral head-neck contour and acetabular rim in positions of hip flexion combined with rotation is a proposed pathomechanism in these hips, but this has not been studied in active postures. Our aim was to assess the anterior impingement pathomechanism in both active and passive postures with high hip flexion that are thought to provoke impingement.

Methods: We recruited nine participants with cam and/or pincer morphologies and with pain, 13 participants with cam and/or pincer morphologies and without pain, and 11 controls from a population-based cohort. We scanned hips in active squatting and passive sitting flexion, adduction, and internal rotation using open MRI and quantified anterior femoroacetabular clearance using the β angle.

Results: In squatting, we found significantly decreased anterior femoroacetabular clearance in painful hips with cam and/or pincer morphologies (mean -11.3° (SD 19.2°)) compared to pain-free hips with cam and/or pincer morphologies (mean 8.5° (SD 14.6°); p = 0.022) and controls (mean 18.6° (SD 8.5°); p < 0.001). In sitting flexion, adduction, and internal rotation, we found significantly decreased anterior clearance in both painful (mean -15.2° (SD 15.3°); p = 0.002) and painfree hips (mean -4.7° (SD 13°); p = 0.010) with cam and/pincer morphologies compared to the controls (mean 7.1° (SD 5.9°)).

Conclusion: Our results support the anterior femoroacetabular impingement pathomechanism in hips with cam and/or pincer morphologies and highlight the effect of posture on this pathomechanism. Cite this article: Bone Jt Open 2021;2(11):988-996.

Keywords: Biomechanics; Femoroacetabular Impingement; Femoroacetabular impingement syndrome; Hip; MRI; acetabular rim; adduction; anterior impingement; arthritic hip; femoral head; flexion; hip osteoarthritis (OA); hips.