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Orthop J Sports MedOrthop J Sports MedOJSspojsOrthopaedic Journal of Sports Medicine2325-9671SAGE Publications Sage CA: Los Angeles, CA 10.1177/2325967118S0015110.1177_2325967118S00151ArticlePatient-Specific Parameters Associated with Traction Stiffness in
Primary and Revision Hip Arthroscopy Kapron Ashley L. PhD1Karns Michael MD2Aoki Stephen Kenji MD1Adeyemi Temitope F. MPH1Baillargeon Elizabeth A. BS1Hartley Melissa K. BS1Todd Jocelyn N. BS1Maak Travis MD11 University of Utah, Salt Lake City, UT,
USA2 University Hospitals Cleveland Medical
Center, Cleveland, OH, USA27 7 2018 7 2018 6 7 suppl4 2018 AOSSM Annual Meeting Abstracts2325967118S00151© The Author(s) 20182018SAGE PublicationsThis open-access article is published and distributed under the
Creative Commons Attribution - NonCommercial - No Derivatives License
(http://creativecommons.org/licenses/by-nc-nd/4.0/), which
permits the noncommercial use, distribution, and reproduction of the article
in any medium, provided the original author and source are credited. You may
not alter, transform, or build upon this article without the permission of
the Author(s). For article reuse guidelines, please visit SAGE’s website at
http://www.sagepub.com/journals-permissions.Objectives:
To quantify the force of traction required for adequate distraction of the
hip during arthroscopy and explore the relationship between hip joint
stiffness and patient-specific demographics, flexibility, and anatomy.

Methods:
101 primary arthroscopy patients (61 females) and 23 patients undergoing
revision arthroscopy for capsular repair (all female) were prospectively
enrolled. A load cell attached to the traction boot continuously measured
traction force. Fluoroscopy images were obtained before and after traction
to measure joint displacement. The stiffness coefficient was calculated as
the force of traction divided by joint displacement. Primary patients were
analyzed in a univariable regression model and re-analyzed separately by
gender. Variables significant at p<0.05 were included in a multivariable
regression model. Stiffness was compared between female primary and revision
patients using independent t-tests.

Results:
For primary arthroscopy, instantaneous peak force averaged 80 ± 18 kgf, after
which the force required to maintain distraction decreased to 57 ± 13 kgf.
In univariable regression analysis, gender, alpha angle, hamstring
flexibility and Beighton hypermobility score were each correlated to
stiffness. However, gender was the only significant variable in the
multivariable regression model. Intragender analysis demonstrated increased
hamstring flexibility correlated with decreased stiffness in males and
higher Beighton scores correlated with decreased stiffness in females.
Stiffness was significantly less in the revision cases than the primary
cases (p=0.006).

Conclusion:
A substantial force is required to achieve and maintain hip distraction, with
males requiring higher forces. Males with increased hamstring flexibility
and females with higher Beighton scores are less stiff than their same
gender counterparts. Patients indicated for revision capsule repair were
less stiff, supporting the importance of the hip capsule on hip stability.
These data may be used to identify patients with microinstability and
patients where specific focus on capsular repair and/or plication may be
warranted.

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