Elsevier

Gait & Posture

Volume 37, Issue 2, February 2013, Pages 258-263
Gait & Posture

The effects of cam femoroacetabular impingement corrective surgery on lower-extremity gait biomechanics

https://doi.org/10.1016/j.gaitpost.2012.07.016Get rights and content

Abstract

Surgery to correct cam femoroacetabular impingement (FAI) is increasingly popular. Nevertheless, no known study has analyzed both the three-dimensional lower-extremity joint kinematics and kinetics to quantify FAI surgical outcomes. The purpose of this study was to determine the effects of FAI surgery on the affected lower-extremity joint mechanics during gait by comparing the three-dimensional hip, knee, ankle and pelvic angular displacements, as well as the hip, knee and ankle moments and powers of preoperative and postoperative FAI groups, and a healthy control group. Ten patients with unilateral symptomatic cam FAI, who underwent corrective surgery using an open or combined technique, participated in the biomechanical analysis of level walking preoperatively and postoperatively. Thirteen healthy control subjects provided normative data. Results showed that gait biomechanics of FAI patients did not return to normal after surgery. Postoperatively, patients had reduced hip frontal and sagittal plane ROM, smaller peak hip abduction and internal rotation moments, and decreased peak hip power generation compared to the control group. Despite reductions in hip pain, hip impairments and trends detected preoperatively, perhaps due to modified gait patterns, persisted postoperatively. Additional discrepancies in lower-extremity joint mechanics were observed postoperatively, which are believed to have resulted from partial muscle impairment caused by the surgical approaches. Further research is required to confirm the reasons for which lower-extremity gait mechanics of FAI patients do not return to normal following surgery. Clarifying these causes could help improve surgical techniques and rehabilitation programs for the treatment of FAI, and thus improve surgical outcomes.

Highlights

► We compare gait biomechanics of pre- and post-surgery cam FAI patients, and controls. ► Despite significant hip pain reduction, normal gait is not restored after surgery. ► Post-surgery patients display reduced hip frontal and sagittal plane range of motion. ► Post-surgery patients have reduced peak hip abduction and internal rotation moments. ► Modified gait patterns and muscle impairment may explain post-surgery discrepancies.

Introduction

Cam femoroacetabular impingement (FAI) is a well-documented source of hip pain in young active adults [1], [2]. Usually its symptoms arise during movements that solicit the hip's range of motion (ROM) limits such as squatting [3], [4], but have also been reported during activities requiring normal hip ROM as seen during walking [5], [6]. Since FAI mainly affects young active individuals, conservative treatment plans are usually not favored as they require radical lifestyle changes and restrictions in physical activity. Consequently, FAI is primarily corrected by means of surgery [7]. Surgical correction of FAI can be achieved using an open [8], [9], arthroscopic [7], [10] or combined technique [11], [12], all of which aim to restore a normal femoral head–neck offset.

Several studies have shown reduction or suppression of hip pain after FAI surgery [2], [12], [13] using the Harris Hip Score [14] and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) [15]. Other studies have reported improvements in postoperative hip passive ROM [12], [16]. Few studies have investigated the three-dimensional (3D) lower-extremity joint kinematics and kinetics of individuals with FAI. These investigations demonstrated that FAI patients had restricted hip [17] and pelvic [18] mobility during tasks requiring large lower-extremity joint ROM, and reduced hip and pelvic motion in the frontal plane during level gait [19] compared to control subjects. Recently, two studies have compared the preoperative and postoperative lower-extremity joint kinematics of FAI patients [20], [21]. Specifically, Rylander et al. [21] assessed FAI patients during level gait, within 1 month before arthroscopic surgery and again 1 year postoperatively. Increased postoperative hip sagittal plane ROM of the affected leg was observed, which resulted primarily from increased maximum hip flexion angles.

FAI surgery is increasingly popular; nevertheless, no known study has analyzed both the 3D lower-extremity joint kinematics and kinetics to evaluate its outcome. It is important to investigate the effects of FAI on hip function during gait as its symptoms can arise during this common repetitive movement [5], [6]. Likewise, it is important to assess the kinetics during gait as it can provide valuable information about muscle function and impairment, and could affect treatment decisions. Understanding the effects of FAI on hip function, preoperatively and postoperatively, is essential in confirming that surgery effectively restores more normal hip biomechanics.

The purpose of this study was to determine the effects of FAI surgery by means of an open or combined technique on the affected lower-extremity joint mechanics during level walking by comparing the 3D hip, knee, ankle and pelvic angular displacements, as well as the hip, knee and ankle moments and powers of preoperative and postoperative FAI groups, and a healthy control group. We hypothesized that there would be no significant differences between postoperative and control groups with regards to the kinematic and kinetic variables of interest, suggesting that surgery effectively restored normal hip biomechanics of FAI patients.

Section snippets

Participants

Seventeen participants with unilateral symptomatic cam FAI were previously compared to fourteen healthy control subjects matched for age, sex and body mass index [19]. In the current study, ten of the seventeen participants with cam FAI returned for postoperative testing. Seven FAI participants did not return for postoperative testing for the following reasons: four declined to participate, one suffered a spinal disc hernia, one had hip resurfacing and one underwent surgery for severe leg pain,

Results

Postoperatively, WOMAC scores of FAI patients improved significantly with respect to hip pain (p = 0.035), but not to hip stiffness or function (p > 0.05) (Table 1).

No significant differences were noted between groups with regards to spatiotemporal parameters (p > 0.05). Similarly, no significant differences were found between affected and unaffected legs of postoperative patients with respect to spatiotemporal parameters and peak 3D vertical ground reaction forces (affected: 884 ± 153.8 N vs.

Discussion

This study compared the gait kinematics and kinetics of healthy control participants and cam FAI patients before and after surgery using an open or combined technique. Postoperatively, WOMAC pain scores improved significantly by 13.4 points. Despite these subjective improvements and contrarily to our hypotheses, the gait biomechanics of FAI patients did not return to normal following surgery.

Kinematic results revealed that hip frontal plane ROM of FAI patients during gait remained unchanged

Conclusion

The present study demonstrated that the affected lower-extremity joint biomechanics of cam FAI patients during level walking do not return to normal following surgery, despite significant reductions in hip pain. Although cam FAI is considered to be caused mainly by an osseous deformity of the femoral head–neck junction, it seems to be associated with aberrant hip function (i.e. muscle activation patterns, ligament tension and bone-on-bone contact) that has not yet been well identified. The

Conflict of interest statement

The authors have no conflict of interest to disclose.

Acknowledgments

The authors would like to acknowledge the contribution of Anna Fazekas and Kyle Kemp, research coordinators at the adult reconstruction division of the orthopaedic surgery department at the Ottawa Hospital, and Daniel Varin, research coordinator at the Human Movement Biomechanics Laboratory of the University of Ottawa. This research was partially supported by the Canadian Institutes of Health Research (#200334).

References (30)

  • K. Foucher et al.

    Preoperative gait adaptations persist one year after surgery in clinically well-functioning total hip replacement patients

    Journal of Biomechanics

    (2007)
  • M. Perron et al.

    Three-dimensional gait analysis in women with a total hip arthroplasty

    Clinical Biomechanics

    (2000)
  • K.C. Foucher et al.

    Time course and extent of functional recovery during the first postoperative year after minimally invasive total hip arthroplasty with two different surgical approaches—a randomized controlled trial

    Journal of Biomechanics

    (2011)
  • S.J. Wisniewski et al.

    Femoroacetabular impingement. An overlooked cause of hip pain

    American Journal of Physical Medicine & Rehabilitation

    (2006)
  • P.E. Beaulé et al.

    Quality of life following femoral head–neck osteochondroplasty for femoroacetabular impingement

    The Journal of Bone & Joint Surgery

    (2007)
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