Abnormal Joint Moment Distributions and Functional Performance During Sit-to-Stand in Femoroacetabular Impingement Patients

Michael A. Samaan, Benedikt J. Schwaiger, Matthew C. Gallo, Thomas M. Link, Alan L. Zhang, Sharmila Majumdar, Richard B. Souza

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Background Femoroacetabular impingement (FAI) is a morphological abnormality of the hip joint that causes pain when performing a mechanically demanding activity of daily living such as the sit-to-stand (STS) task. Previous studies have assessed lower extremity joint mechanics during an STS task in various pathologies, yet the STS task has not been studied in FAI patients. Objective The objective of this study was to identify differences in joint kinetics and performance between FAI patients and healthy controls during a STS task. It was hypothesized that FAI patients would exhibit altered time needed to complete the STS task, as well as altered lower extremity biomechanics, when compared to healthy controls. Design This was a cross-sectional cohort study. Setting The study took place at a motion capture laboratory at an institutional orthopedic facility. Participants Biomechanical analysis was performed in 17 FAI patients and 31 age- and body mass index (BMI)−matched healthy controls during the STS task. Methods Sagittal plane joint moments, total support moment (TSM), joint contributions to the TSM, and functional measures during the STS task were compared between groups. Main Outcome Measurements Peak joint moments, TSM and joint contributions to the TSM were assessed during the STS task. In addition, the time to and value of the peak vertical ground reaction force (vGRF), limb symmetry index at peak vGRF, loading rate, and total time needed to perform the STS task were determined. Results Compared to the control participants, the FAI patients exhibited worse Hip Disability and Osteoarthritis Outcome Score (HOOS) pain and function subscores. No group differences were observed in peak sagittal joint moments during the STS task. However, when compared to controls, the FAI patients demonstrated reduced knee joint contributions to the TSM. In addition, the FAI patients exhibited increased time needed to perform the STS task, increased time to reach peak vGRF, and reduced lower extremity loading rate during the STS task. Conclusions FAI patients demonstrated abnormal joint contributions to TSM and altered functional performance during the STS task. These altered movement patterns during the STS task may be compensatory mechanisms used by the FAI patients to reduce pain and to improve function. Level of Evidence Not applicable.

Original languageEnglish
Pages (from-to)563-570
Number of pages8
JournalPM and R
Issue number6
StatePublished - Jun 2017

Bibliographical note

Publisher Copyright:
© 2017 American Academy of Physical Medicine and Rehabilitation

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation
  • Rehabilitation
  • Neurology
  • Clinical Neurology


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