Original research
Effects of a hip brace on biomechanics and pain in people with femoroacetabular impingement

https://doi.org/10.1016/j.jsams.2017.09.185Get rights and content

Abstract

Objectives

This study evaluates whether hip bracing in patients with femoroacetabular impingement (FAI) (a) immediately reduces range of hip internal rotation, flexion, adduction, and pain during functional tasks; and (b) improves patient-reported outcomes when worn daily over 4 weeks.

Design

Within-participant design followed by a case series.

Methods

Twenty-five adults with symptomatic FAI underwent 3D kinematic assessment with and without a hip brace during single-leg squat, double-leg squat, stair ascent, and stair descent. A subset of this population (n = 17) continued to wear the brace daily for 4-weeks. A linear mixed statistical model was used to assess pain and kinematic differences between the braced and unbraced conditions at baseline testing. Patient-reported outcomes (NRS pain, iHot-33 and HAGOS questionnaires) at 4-weeks were compared to baseline using paired t-tests.

Results

Bracing resulted in significant but small reductions in peak hip flexion ranging between 5.3° (95% CI 0.8°–9.7°) and 5.6° (95% CI 1.1°–10.0°), internal rotation ranging between 2.5° (95% CI 0.6°–4.4°) and 6.4° (95% CI 4.5°–8.2°), and adduction ranging between 2.2° (95% CI 0.5°–3.8°) and 3.3° (95% CI 1.6°–5.0°) during all tasks, except flexion during single-leg squat, compared with the unbraced condition; pain was not significantly improved with the brace. Bracing over four weeks did not significantly change patient-reported outcomes.

Conclusions

Bracing subtly limited impinging hip movements during functional tasks, but did not immediately reduce pain or improve patient-reported clinical outcomes after 4 weeks in a young adult cohort with long-standing FAI.

Introduction

Femoroacetabular impingement (FAI) is a common cause of groin pain and functional limitation, especially in athletes involved in acceleration-type sports.1, 2 Specific morphologies of the femoral head (cam) and acetabulum (pincer), or frequently a combination of the two, predispose the patient to symptomatic impingement of the femoral head and neck against the acetabular rim. This can eventually lead to chondral damage and hip osteoarthritis.3, 4

The symptoms of FAI include hip stiffness and varying degrees of sudden sharp or slow onset anterior groin pain, which are commonly provoked by activities involving hip flexion, adduction and/or internal rotation placing the hip into an impinging position.5, 6, 7 Although the repetitive hip overloading common in acceleration sports frequently aggravates FAI-related pain and functional limitation, symptoms outside of sport are also common; in particular, during protracted periods of sitting, climbing stairs, and squatting.8, 9, 10

The goals of treatment for FAI are to relieve pain, improve function and allow return to usual activity. Operative treatment, either open or arthroscopic, aims to improve hip morphology and repair damaged tissue, and has progressed steadily in sophistication and volume over the past decade.11, 12 Conservative treatments such as medication, rehabilitation focused on strength, neuromuscular control and range of motion, and activity modification also play a role in FAI management, but are under-researched, despite being a prerequisite for surgical intervention.11, 12, 13 An orthotic device to limit impinging hip movements during provocative activities may be a useful self-administered adjunctive treatment for FAI.

There has been limited research investigating hip bracing as a conservative treatment for FAI prior to surgery. Although large motion-limiting braces are available for post-surgical use, these are designed to restrict abduction and generally stabilize the hip, rather than restrict impingement movements.14 While no known brace has specifically been designed for conservative management of FAI, it is plausible that a hip brace which restricts impinging movements could mitigate symptoms in patients with the condition.

A single case study demonstrated that a light-weight strap, which was originally designed to prevent internal rotation in people with patellofemoral pain,15 immediately reduced pain, hip internal rotation, and hip adduction during running, step-down, and drop jump tasks in an FAI patient.16 Another study using the same strap and involving 8 FAI patients, but reported in abstract form only, evaluated kinematic change during walking, jogging and stair-climb tasks. Results revealed small, immediate task-dependent reductions in adduction, flexion and internal rotation during brace-wear.17 While these preliminary results are promising, further research is needed to confirm the role of hip bracing for patients with FAI.

The primary aim of this study was to evaluate the immediate effects of a hip brace on hip kinematics and pain in young adult patients with FAI. We hypothesized that the brace would immediately reduce hip pain and peak hip internal rotation, adduction and flexion angles compared to an unbraced condition during several tasks likely to provoke symptoms. A secondary exploratory aim was to investigate the effects of daily brace-wear on hip pain and other patient-reported outcomes over four weeks.

Section snippets

Methods

To investigate immediate bracing effects, a within-participant design was used. To investigate effects of daily brace use in a subgroup of participants, an observational study design was used.

Twenty-five young adult participants aged 18–35 years old were recruited via a sports physician and an orthopedic surgeon (JO). Participants were eligible if they had been diagnosed with FAI based on clinical and radiological findings. These included a history of groin/hip pain or stiffness in daily and/or

Results

Demographic characteristics and baseline symptoms of the full study sample (n = 25) are presented in Table 1. Participants were young adults, predominantly men with relatively moderate to severe levels of pain and disability, and were generally recreationally physically active, although three participants engaged in elite-level sports, while another three were sedentary. Most participants had a history of protracted FAI symptoms, and all but one had been referred for surgical consultation or were

Discussion

Our results showed that the brace modified the kinematics of patients with FAI as hypothesized by subtly limiting impinging hip movements during a variety of functional tasks commonly thought capable of eliciting symptoms in this population.8, 9 For participants who wore the brace for four weeks, the brace was generally well-tolerated, but not particularly comfortable. Minor adverse events were common. Adherence was excellent with a self-reported average daily use of nearly six hours. However,

Conclusion

Hip bracing significantly but subtly reduced hip impinging movements during functional tasks in a cohort of young adults with persistent FAI symptoms. These movement limitations did not translate to clinical benefits, either immediately or with daily brace use over four weeks. These results question the value of hip bracing in the management of patients with long-standing FAI symptoms resistant to conservative management.

Practical implications

  • The tested brace can be used to reduce maximum hip impingement (internal rotation, flexion and adduction) in FAI patients.

  • This form of bracing in patients with long-standing symptomatic FAI does not appear to improve clinically relevant outcomes either immediately or after a month of consistent, prolonged wear.

  • Some FAI sub-populations might benefit from bracing, but the findings of this study do not support the broad application of bracing as a conservative therapy for FAI.

Acknowledgements

We wish to thank Dr. Peter Braun for assistance with recruitment of participants. This study was supported by a program grant from the National Health and Medical Research Council (#631717). KLB is supported by a National Health and Medical Research Council Fellowship (#1058440). RSH is supported by an Australian Research Council Future Fellowship (FT130100175). NN is supported by a Swiss National Science Foundation Doctoral Fellowship (P1ZHP3_151647). Sources of funding did not in any way

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