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<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Combined Hip Abductor and External Rotator Strengthening and Hip
Internal Rotator Stretching Improves Pain and Function in Patients With
Patellofemoral Pain Syndrome: A Randomized Controlled Trial With Crossover
Design</title>
<author><name sortKey="Jellad, Anis" sort="Jellad, Anis" uniqKey="Jellad A" first="Anis" last="Jellad">Anis Jellad</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Kalai, Amine" sort="Kalai, Amine" uniqKey="Kalai A" first="Amine" last="Kalai">Amine Kalai</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Guedria, Mohamed" sort="Guedria, Mohamed" uniqKey="Guedria M" first="Mohamed" last="Guedria">Mohamed Guedria</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Jguirim, Mahbouba" sort="Jguirim, Mahbouba" uniqKey="Jguirim M" first="Mahbouba" last="Jguirim">Mahbouba Jguirim</name>
<affiliation><nlm:aff id="aff2-2325967121989729">Department of Rheumatology,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Elmhamdi, Sana" sort="Elmhamdi, Sana" uniqKey="Elmhamdi S" first="Sana" last="Elmhamdi">Sana Elmhamdi</name>
<affiliation><nlm:aff id="aff3-2325967121989729">Department of Preventive Medicine,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Salah, Sana" sort="Salah, Sana" uniqKey="Salah S" first="Sana" last="Salah">Sana Salah</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Frih, Zohra Ben Salah" sort="Frih, Zohra Ben Salah" uniqKey="Frih Z" first="Zohra Ben Salah" last="Frih">Zohra Ben Salah Frih</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
</titleStmt>
<publicationStmt><idno type="wicri:source">PMC</idno>
<idno type="pmid">33912615</idno>
<idno type="pmc">8050763</idno>
<idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8050763</idno>
<idno type="RBID">PMC:8050763</idno>
<idno type="doi">10.1177/2325967121989729</idno>
<date when="2021">2021</date>
<idno type="wicri:Area/Pmc/Corpus">000234</idno>
<idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">000234</idno>
</publicationStmt>
<sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">Combined Hip Abductor and External Rotator Strengthening and Hip
Internal Rotator Stretching Improves Pain and Function in Patients With
Patellofemoral Pain Syndrome: A Randomized Controlled Trial With Crossover
Design</title>
<author><name sortKey="Jellad, Anis" sort="Jellad, Anis" uniqKey="Jellad A" first="Anis" last="Jellad">Anis Jellad</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Kalai, Amine" sort="Kalai, Amine" uniqKey="Kalai A" first="Amine" last="Kalai">Amine Kalai</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Guedria, Mohamed" sort="Guedria, Mohamed" uniqKey="Guedria M" first="Mohamed" last="Guedria">Mohamed Guedria</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Jguirim, Mahbouba" sort="Jguirim, Mahbouba" uniqKey="Jguirim M" first="Mahbouba" last="Jguirim">Mahbouba Jguirim</name>
<affiliation><nlm:aff id="aff2-2325967121989729">Department of Rheumatology,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Elmhamdi, Sana" sort="Elmhamdi, Sana" uniqKey="Elmhamdi S" first="Sana" last="Elmhamdi">Sana Elmhamdi</name>
<affiliation><nlm:aff id="aff3-2325967121989729">Department of Preventive Medicine,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Salah, Sana" sort="Salah, Sana" uniqKey="Salah S" first="Sana" last="Salah">Sana Salah</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
<author><name sortKey="Frih, Zohra Ben Salah" sort="Frih, Zohra Ben Salah" uniqKey="Frih Z" first="Zohra Ben Salah" last="Frih">Zohra Ben Salah Frih</name>
<affiliation><nlm:aff id="aff1-2325967121989729">Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</nlm:aff>
</affiliation>
</author>
</analytic>
<series><title level="j">Orthopaedic Journal of Sports Medicine</title>
<idno type="eISSN">2325-9671</idno>
<imprint><date when="2021">2021</date>
</imprint>
</series>
</biblStruct>
</sourceDesc>
</fileDesc>
<profileDesc><textClass></textClass>
</profileDesc>
</teiHeader>
<front><div type="abstract" xml:lang="en"><sec><title>Background:</title>
<p>Active rehabilitation has an important role in the management of
patellofemoral pain syndrome (PFPS). Although some studies have shown the
benefit of hip-muscle strengthening, the effect of combining hip-muscle
stretching with strengthening has not yet been defined.</p>
</sec>
<sec><title>Purpose:</title>
<p>To evaluate the effect of combined strengthening of the hip external rotators
and abductors and stretching of the hip internal rotators on pain and
function in patients with PFPS.</p>
</sec>
<sec><title>Study Design:</title>
<p>Randomized controlled trial; Level of evidence, 2.</p>
</sec>
<sec><title>Methods:</title>
<p>A total of 109 patients with PFPS (75 female and 34 male; mean age, 31.6 ±
10.8 years) were first randomly assigned to protocol A (n = 67) of the A-B
arm (AB group; standard rehabilitation) or protocol B (n = 42) of the B-A
arm (BA group; standard rehabilitation with strengthening of the hip
external rotators and abductors and stretching of the hip internal
rotators). Each protocol consisted of 3 sessions a week for 4 weeks. After a
washout period, corresponding to a symptom-free period, rehabilitation
programs were crossed over. A visual analog scale (VAS) evaluating perceived
pain, the Functional Index Questionnaire (FIQ), and the Kujala score were
administered at baseline, the end of each rehabilitation protocol, and 12
weeks after the completion of the second protocol for each group.</p>
</sec>
<sec><title>Results:</title>
<p>Until the final follow-up, VAS, FIQ, and Kujala scores were significantly
improved in both the A-B and B-A arms (<italic>P</italic>
< .05 for all).
Compared with protocol A, protocol B provided significant improvement in
terms of pain and function in both the BA (VAS and Kujala;
<italic>P</italic>
< .001) and AB (VAS and Kujala; <italic>P</italic>
< .001) groups.</p>
</sec>
<sec><title>Conclusion:</title>
<p>Combined strengthening of the hip abductors and external rotators with
stretching of the hip internal rotators provided better outcomes, which were
maintained for at least 12 weeks, in terms of pain and function in patients
with PFPS.</p>
</sec>
</div>
</front>
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<pmc article-type="research-article"><pmc-dir>properties open_access</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-ta">Orthop J Sports Med</journal-id>
<journal-id journal-id-type="iso-abbrev">Orthop J Sports Med</journal-id>
<journal-id journal-id-type="publisher-id">OJS</journal-id>
<journal-id journal-id-type="hwp">spojs</journal-id>
<journal-title-group><journal-title>Orthopaedic Journal of Sports Medicine</journal-title>
</journal-title-group>
<issn pub-type="epub">2325-9671</issn>
<publisher><publisher-name>SAGE Publications</publisher-name>
<publisher-loc>Sage CA: Los Angeles, CA</publisher-loc>
</publisher>
</journal-meta>
<article-meta><article-id pub-id-type="pmid">33912615</article-id>
<article-id pub-id-type="pmc">8050763</article-id>
<article-id pub-id-type="doi">10.1177/2325967121989729</article-id>
<article-id pub-id-type="publisher-id">10.1177_2325967121989729</article-id>
<article-categories><subj-group subj-group-type="heading"><subject>Article</subject>
</subj-group>
</article-categories>
<title-group><article-title>Combined Hip Abductor and External Rotator Strengthening and Hip
Internal Rotator Stretching Improves Pain and Function in Patients With
Patellofemoral Pain Syndrome: A Randomized Controlled Trial With Crossover
Design</article-title>
</title-group>
<contrib-group><contrib contrib-type="author"><name><surname>Jellad</surname>
<given-names>Anis</given-names>
</name>
<degrees>MD</degrees>
<xref ref-type="corresp" rid="corresp1-2325967121989729">*</xref>
<xref ref-type="aff" rid="aff1-2325967121989729">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Kalai</surname>
<given-names>Amine</given-names>
</name>
<degrees>MD</degrees>
<xref ref-type="aff" rid="aff1-2325967121989729">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Guedria</surname>
<given-names>Mohamed</given-names>
</name>
<degrees>MD</degrees>
<xref ref-type="aff" rid="aff1-2325967121989729">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Jguirim</surname>
<given-names>Mahbouba</given-names>
</name>
<degrees>MD</degrees>
<xref ref-type="aff" rid="aff2-2325967121989729">‡</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Elmhamdi</surname>
<given-names>Sana</given-names>
</name>
<degrees>MD</degrees>
<xref ref-type="aff" rid="aff3-2325967121989729">§</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Salah</surname>
<given-names>Sana</given-names>
</name>
<degrees>MD</degrees>
<xref ref-type="aff" rid="aff1-2325967121989729">†</xref>
</contrib>
<contrib contrib-type="author"><name><surname>Frih</surname>
<given-names>Zohra Ben Salah</given-names>
</name>
<degrees>MD</degrees>
<xref ref-type="aff" rid="aff1-2325967121989729">†</xref>
</contrib>
</contrib-group>
<aff id="aff1-2325967121989729"><label>†</label>
Department of Physical Medicine and Rehabilitation,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</aff>
<aff id="aff2-2325967121989729"><label>‡</label>
Department of Rheumatology,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</aff>
<aff id="aff3-2325967121989729"><label>§</label>
Department of Preventive Medicine,<institution-wrap><institution-id institution-id-type="Ringgold">59073</institution-id>
<institution content-type="university">Faculty of Medicine, University of Monastir</institution>
</institution-wrap>
, Monastir, Tunisia.</aff>
<aff id="aff4-2325967121989729"><italic>Investigation performed at the Department of Physical Medicine and Rehabilitation, Faculty of Medicine, University of Monastir, Monastir, Tunisia</italic>
</aff>
<author-notes><corresp id="corresp1-2325967121989729"><label>*</label>
Anis Jellad, MD, Department of Physical Medicine and
Rehabilitation, Faculty of Medicine, University of Monastir, Rue Avicenne,
Monastir, 5000, Tunisia (email: <email>anisjellad@gmail.com</email>
) (Twitter:
<ext-link ext-link-type="uri" xlink:href="https://twitter.com/anisjellad1">@anisjellad1</ext-link>
).</corresp>
</author-notes>
<pub-date pub-type="epub"><day>14</day>
<month>4</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="collection"><month>4</month>
<year>2021</year>
</pub-date>
<volume>9</volume>
<issue>4</issue>
<elocation-id>2325967121989729</elocation-id>
<history><date date-type="received"><day>22</day>
<month>8</month>
<year>2020</year>
</date>
<date date-type="accepted"><day>30</day>
<month>9</month>
<year>2020</year>
</date>
</history>
<permissions><copyright-statement>© The Author(s) 2021</copyright-statement>
<copyright-year>2021</copyright-year>
<copyright-holder content-type="sage">SAGE Publications</copyright-holder>
<license><ali:license_ref specific-use="textmining" content-type="ccbyncndlicense">https://creativecommons.org/licenses/by-nc-nd/4.0/</ali:license_ref>
<license-p>This article is distributed under the terms of the Creative Commons
Attribution-NonCommercial-NoDerivs 4.0 License (<ext-link ext-link-type="uri" xlink:href="https://creativecommons.org/licenses/by-nc-nd/4.0/">https://creativecommons.org/licenses/by-nc-nd/4.0/</ext-link>
) which
permits non-commercial use, reproduction and distribution of the work as
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).</license-p>
</license>
</permissions>
<abstract><sec><title>Background:</title>
<p>Active rehabilitation has an important role in the management of
patellofemoral pain syndrome (PFPS). Although some studies have shown the
benefit of hip-muscle strengthening, the effect of combining hip-muscle
stretching with strengthening has not yet been defined.</p>
</sec>
<sec><title>Purpose:</title>
<p>To evaluate the effect of combined strengthening of the hip external rotators
and abductors and stretching of the hip internal rotators on pain and
function in patients with PFPS.</p>
</sec>
<sec><title>Study Design:</title>
<p>Randomized controlled trial; Level of evidence, 2.</p>
</sec>
<sec><title>Methods:</title>
<p>A total of 109 patients with PFPS (75 female and 34 male; mean age, 31.6 ±
10.8 years) were first randomly assigned to protocol A (n = 67) of the A-B
arm (AB group; standard rehabilitation) or protocol B (n = 42) of the B-A
arm (BA group; standard rehabilitation with strengthening of the hip
external rotators and abductors and stretching of the hip internal
rotators). Each protocol consisted of 3 sessions a week for 4 weeks. After a
washout period, corresponding to a symptom-free period, rehabilitation
programs were crossed over. A visual analog scale (VAS) evaluating perceived
pain, the Functional Index Questionnaire (FIQ), and the Kujala score were
administered at baseline, the end of each rehabilitation protocol, and 12
weeks after the completion of the second protocol for each group.</p>
</sec>
<sec><title>Results:</title>
<p>Until the final follow-up, VAS, FIQ, and Kujala scores were significantly
improved in both the A-B and B-A arms (<italic>P</italic>
< .05 for all).
Compared with protocol A, protocol B provided significant improvement in
terms of pain and function in both the BA (VAS and Kujala;
<italic>P</italic>
< .001) and AB (VAS and Kujala; <italic>P</italic>
< .001) groups.</p>
</sec>
<sec><title>Conclusion:</title>
<p>Combined strengthening of the hip abductors and external rotators with
stretching of the hip internal rotators provided better outcomes, which were
maintained for at least 12 weeks, in terms of pain and function in patients
with PFPS.</p>
</sec>
</abstract>
<kwd-group><kwd>patellofemoral pain syndrome</kwd>
<kwd>rehabilitation</kwd>
<kwd>hip</kwd>
<kwd>muscle</kwd>
</kwd-group>
<custom-meta-group><custom-meta><meta-name>typesetter</meta-name>
<meta-value>ts3</meta-value>
</custom-meta>
</custom-meta-group>
</article-meta>
</front>
<body><p>Patellofemoral pain syndrome (PFPS) is defined as retropatellar or peripatellar pain
resulting from physical and biochemical changes in the patellofemoral joint, typically
occurring with activity and often worsening when descending steps or hills or after
prolonged sitting.<sup><xref rid="bibr11-2325967121989729" ref-type="bibr">11</xref>
</sup>
It is one of the most common lower limb disorders.<sup><xref rid="bibr2-2325967121989729" ref-type="bibr">2</xref>
</sup>
In fact, approximately 1 of 4 people experience 1 episode of PFPS during their lifetime.<sup><xref rid="bibr23-2325967121989729" ref-type="bibr">23</xref>
</sup>
</p>
<p>Advances in the pathophysiological understanding of PFPS have resulted in multiple
approaches in the treatment of this condition. For example, excessive femoral internal
rotation may increase patellofemoral joint stress and predispose people to PFPS through
relative lateral displacement of the patella.<sup><xref rid="bibr18-2325967121989729" ref-type="bibr">18</xref>
,<xref rid="bibr21-2325967121989729" ref-type="bibr">21</xref>
</sup>
Excessive hip internal rotation during running, stepping, and landing from a jump
has been noted in young, active female patients with PFPS.<sup><xref rid="bibr22-2325967121989729" ref-type="bibr">22</xref>
</sup>
Furthermore, an association between hip internal rotation during running and PFPS
has been identified in a recent systematic review and meta-analysis.<sup><xref rid="bibr17-2325967121989729" ref-type="bibr">17</xref>
</sup>
These findings were highlighted by dynamic magnetic resonance imaging studies in
female patients.<sup><xref rid="bibr21-2325967121989729" ref-type="bibr">21</xref>
</sup>
Additionally, excessive hip internal rotation has been advanced as a predictor of
self-reported pain and function during a stepdown task<sup><xref rid="bibr16-2325967121989729" ref-type="bibr">16</xref>
</sup>
and the development of PFPS in Naval Academy cadets.<sup><xref rid="bibr3-2325967121989729" ref-type="bibr">3</xref>
</sup>
Thus, special attention should be given to hip rotators in the rehabilitation of
this syndrome.</p>
<p>Global stretching of anterior hip structures was found to be beneficial when associated
with aerobic exercises in the management of PFPS,<sup><xref rid="bibr14-2325967121989729" ref-type="bibr">14</xref>
</sup>
but the effect of including stretching of the hip internal rotators has not yet
been studied. Furthermore, weakness of the hip abductors and external rotators has
commonly been found in patients with PFPS, and strengthening of these muscle groups is
beneficial when associated with knee-focused rehabilitation programs.<sup><xref rid="bibr7-2325967121989729" ref-type="bibr">7</xref>
,<xref rid="bibr20-2325967121989729" ref-type="bibr">20</xref>
</sup>
</p>
<p>The aim of our study was to evaluate the effect of combining strengthening of the hip
external rotators and abductors with stretching of the hip internal rotators on pain and
function in patients with PFPS. We hypothesized that combining strengthening of the hip
abductors and external rotators with stretching of the hip internal rotators would lead
to better outcomes.</p>
<sec sec-type="methods" id="section1-2325967121989729"><title>Methods</title>
<sec id="section2-2325967121989729"><title>Study Design</title>
<p>A randomized, controlled, single-blinded crossover study was carried out. This
type of design was chosen to reduce variability between participants and allow
for a smaller sample size. All eligible patients were informed about the study
and gave consent (consent for patients younger than 18 was given by a parent or
guardian). We obtained approval from the hospital ethical committee before
beginning patient recruitment.</p>
</sec>
<sec id="section3-2325967121989729" sec-type="subjects"><title>Patients</title>
<p>Patients between 14 and 50 years of age referred to a single institution for PFPS
were eligible for this trial. This large age range is justified by the
significant incidence of PFPS in not only young patients but also middle-aged
ones as well as the wide patient recruitment in our daily clinical practice.
Patient enrollment began in January 2015 and ended in May 2016.</p>
</sec>
<sec id="section4-2325967121989729"><title>Inclusion and Exclusion Criteria</title>
<p>Included patients were those diagnosed with PFPS, regardless of their activity
level. The diagnosis was established by the referring physician and confirmed in
all cases by a physiatrist with 14 years of experience in the management of
musculoskeletal disorders (A.J.). The diagnosis was retained when symptoms were
located in the peripatellar and/or retropatellar area and reproduced with at
least 1 of the following activities: stair descent, squatting, kneeling, and
prolonged sitting. Symptoms had to be present for at least 3 months, and other
anterior knee pain such as referred pain caused by hip and spine disorders was
ruled out through a thorough clinical examination and, if needed, radiological
investigations such as computed tomography and magnetic resonance imaging.
Patients with a history of knee osteoarthritis, injury or surgery, neurological
disorders impairing the lower limbs, or systemic inflammatory disorders were
excluded from the study.</p>
</sec>
<sec id="section5-2325967121989729"><title>Randomization</title>
<p>Patients were assigned to 1 of the 2 intervention arms using a
computer-generated, random number table.</p>
</sec>
<sec id="section6-2325967121989729"><title>Interventions and Assessment Rate</title>
<p>Participants were evaluated at baseline and randomly assigned to receive protocol
A of the A-B arm (AB group) or protocol B of the B-A arm (BA group). Protocol A
is considered to be the standard protocol for treating PFPS. It consisted of
transcutaneous electrical nerve stimulation (2 minutes); patellar mobilization
(2 minutes); hamstring, quadriceps, and tensor fasciae latae muscle stretching;
open kinetic chain strengthening of the quadriceps (concentric exercises); and
proprioceptive exercises. Muscle strengthening was performed using weightbearing
pulley systems with an intensity of 60% of the patient’s 1-repetition maximum.
Protocol B supplemented protocol A with concentric strengthening of the hip
external rotators and abductors using weightbearing pulley systems as well as
stretching of the hip internal rotators. In each session, 4 repetitions of
static stretching were performed manually by the physical therapist. Each
repetition was maintained for 30 seconds at a point of mild discomfort but not
pain. A resting interval of 20 seconds was observed between stretching
repetitions.</p>
<p>Both protocols lasted for 4 weeks and included 12 rehabilitation sessions.
Functional status, pain intensity, and knee and hip range of motion were
assessed by the same physiatrist, who was unaware of patient allocation, at the
end of the first protocol. Patients were instructed to return after a washout
period so they could be assigned to the other protocol (crossover of programs).
The washout period corresponded to a symptom-free period. It was measured for
each patient and lasted from the end of the first protocol to the next
consultation based on the patient’s request after symptom recurrence. Patients
were evaluated at the end of the second protocol and a third time at 3 months
after they had finished the second protocol (<xref ref-type="fig" rid="fig1-2325967121989729">Figure 1</xref>
).</p>
<fig id="fig1-2325967121989729" orientation="portrait" position="float"><label>Figure 1.</label>
<caption><p>Flowchart of the study. PFPS, patellofemoral pain syndrome.</p>
</caption>
<graphic xlink:href="10.1177_2325967121989729-fig1"></graphic>
</fig>
</sec>
<sec id="section7-2325967121989729"><title>Outcome Measures</title>
<p>The main outcome measures were pain and function. Pain was assessed using a
visual analog scale with a range from 0 (no pain) to 100 (worst pain
imaginable). Function was evaluated using 2 measures: the Kujala score and the
Functional Index Questionnaire (FIQ). The Kujala score or “anterior knee pain
scale,” which is a self-administered questionnaire for patients with PFPS,
ranging from 0 to 100, with a lower score reflecting poorer functional capacity,
is one of the commonly used assessment tools that has been developed for the
evaluation of patients with patellofemoral disorders. It consists of 13
questions that relate to specified activities and pain severity and addresses
clinical symptoms.<sup><xref rid="bibr13-2325967121989729" ref-type="bibr">13</xref>
</sup>
The Kujala score is a valid and reliable measure of anterior knee pain.<sup><xref rid="bibr10-2325967121989729" ref-type="bibr">10</xref>
</sup>
The FIQ is composed of 8 questions regarding aggravating activities for
PFPS and was found to be a good discriminator for measuring clinical changes in
these patients.<sup><xref rid="bibr4-2325967121989729" ref-type="bibr">4</xref>
</sup>
The score for this questionnaire ranges from 0 to 16, with a lower score
reflecting poorer functional capacity. Although the FIQ exhibited poor
day-to-day reliability, it has been shown to be a valid measure for the
detection of clinical changes.<sup><xref rid="bibr4-2325967121989729" ref-type="bibr">4</xref>
</sup>
</p>
</sec>
<sec id="section8-2325967121989729"><title>Statistical Analysis</title>
<p>Statistical analyses were performed using SPSS Version 21.0 software for Windows
(IBM). We compared the means for quantitative variables before and after
treatment using analysis of variance. The Student <italic>t</italic>
test for
paired samples was used to compare quantitative variables between treatment
protocols. <italic>P</italic>
< .05 was considered significant. The effect
size for comparisons was determined using the Cohen <italic>d</italic>
.</p>
</sec>
</sec>
<sec sec-type="results" id="section9-2325967121989729"><title>Results</title>
<p>A total of 149 patients with PFPS were recruited. Of these patients, 40 did not meet
the inclusion criteria (<xref ref-type="fig" rid="fig1-2325967121989729">Figure
1</xref>
). We enrolled 109 patients, including 75 female patients, with a mean
age of 31.6 ± 10.8 years. There were no significant differences in demographics or
clinical scores between the groups at baseline (<xref rid="table1-2325967121989729" ref-type="table">Table 1</xref>
).</p>
<table-wrap id="table1-2325967121989729" orientation="portrait" position="float"><label>Table 1</label>
<caption><p>Baseline Characteristics<italic><sup>a</sup>
</italic>
</p>
</caption>
<alternatives><graphic xlink:href="10.1177_2325967121989729-table1"></graphic>
<table frame="hsides" rules="groups"><thead><tr><th rowspan="1" colspan="1"></th>
<th rowspan="1" colspan="1">AB Group</th>
<th rowspan="1" colspan="1">BA Group</th>
<th rowspan="1" colspan="1">All</th>
<th rowspan="1" colspan="1"><italic>P</italic>
Value</th>
</tr>
</thead>
<tbody><tr><td colspan="5" rowspan="1">Demographic characteristics</td>
</tr>
<tr><td rowspan="1" colspan="1"> Age, y</td>
<td rowspan="1" colspan="1">32.0 ± 10.9</td>
<td rowspan="1" colspan="1">31.1 ± 10.9</td>
<td rowspan="1" colspan="1">31.6 ± 10.8</td>
<td rowspan="1" colspan="1">.97</td>
</tr>
<tr><td rowspan="1" colspan="1"> Female sex, %</td>
<td rowspan="1" colspan="1">73.1</td>
<td rowspan="1" colspan="1">61.9</td>
<td rowspan="1" colspan="1">68.8</td>
<td rowspan="1" colspan="1">.28</td>
</tr>
<tr><td rowspan="1" colspan="1"> Body mass index, kg/m<sup>2</sup>
</td>
<td rowspan="1" colspan="1">24.5 ± 4.6</td>
<td rowspan="1" colspan="1">25.4 ± 4.6</td>
<td rowspan="1" colspan="1">24.9 ± 4.3</td>
<td rowspan="1" colspan="1">.22</td>
</tr>
<tr><td colspan="5" rowspan="1">Clinical characteristics</td>
</tr>
<tr><td rowspan="1" colspan="1"> VAS score (0-100)</td>
<td rowspan="1" colspan="1">58.0 ± 17.1</td>
<td rowspan="1" colspan="1">55.0 ± 20.6</td>
<td rowspan="1" colspan="1">56.8 ± 18.5</td>
<td rowspan="1" colspan="1">.42</td>
</tr>
<tr><td rowspan="1" colspan="1"> Kujala score (0-100)</td>
<td rowspan="1" colspan="1">56.7 ± 9.5</td>
<td rowspan="1" colspan="1">58.0 ± 10.4</td>
<td rowspan="1" colspan="1">57.2 ± 9.8</td>
<td rowspan="1" colspan="1">.89</td>
</tr>
<tr><td rowspan="1" colspan="1"> FIQ score (0-16)</td>
<td rowspan="1" colspan="1">8.3 ± 1.9</td>
<td rowspan="1" colspan="1">8.6 ± 1.9</td>
<td rowspan="1" colspan="1">8.4 ± 1.9</td>
<td rowspan="1" colspan="1">.69</td>
</tr>
</tbody>
</table>
</alternatives>
<table-wrap-foot><fn id="table-fn1-2325967121989729"><p><italic><sup>a</sup>
</italic>
Data are reported as mean ± SD unless otherwise indicated. FIQ,
Functional Index Questionnaire; VAS, visual analog scale.</p>
</fn>
</table-wrap-foot>
</table-wrap>
<p>The mean washout period was longer for patients in the BA group than in the AB group
(28.0 ± 14.3 vs 21.4 ± 11.2 weeks, respectively; <italic>P</italic>
= .009). In both
the AB and BA groups, pain and functional status were statistically significantly
improved after protocol A and protocol B. These improvements were maintained to the
end of the study protocol (<xref rid="table2-2325967121989729" ref-type="table">Table 2</xref>
). Overall, protocol B provided a more significant improvement
compared with protocol A in terms of pain and function (<italic>P</italic>
< .001
for all) (<xref rid="table3-2325967121989729" ref-type="table">Table 3</xref>
).</p>
<table-wrap id="table2-2325967121989729" orientation="portrait" position="float"><label>Table 2</label>
<caption><p>Changes in Pain and Functional Scores<italic><sup>a</sup>
</italic>
</p>
</caption>
<alternatives><graphic xlink:href="10.1177_2325967121989729-table2"></graphic>
<table frame="hsides" rules="groups"><thead><tr><th rowspan="1" colspan="1"></th>
<th rowspan="1" colspan="1">Baseline</th>
<th rowspan="1" colspan="1">End of First Protocol</th>
<th rowspan="1" colspan="1"><italic>P</italic>
<sub>1</sub>
Value (ES)</th>
<th rowspan="1" colspan="1">End of Second Protocol</th>
<th rowspan="1" colspan="1"><italic>P</italic>
<sub>2</sub>
Value (ES)</th>
<th rowspan="1" colspan="1">3 mo After End of Second Protocol</th>
<th rowspan="1" colspan="1"><italic>P</italic>
<sub>3</sub>
Value (ES)</th>
</tr>
</thead>
<tbody><tr><td rowspan="1" colspan="1">AB group</td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1"> VAS score</td>
<td rowspan="1" colspan="1">58.0 ± 17.1</td>
<td rowspan="1" colspan="1">41.7 ± 17.0</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.523)</td>
<td rowspan="1" colspan="1">17.9 ± 12.1</td>
<td rowspan="1" colspan="1">.01 <break></break>
(0.856)</td>
<td rowspan="1" colspan="1">9.4 ± 7.2</td>
<td rowspan="1" colspan="1">.02 <break></break>
(0.900)</td>
</tr>
<tr><td rowspan="1" colspan="1"> Kujala score</td>
<td rowspan="1" colspan="1">56.7 ± 9.5</td>
<td rowspan="1" colspan="1">62.8 ± 8.6</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.729)</td>
<td rowspan="1" colspan="1">75.8 ± 7.1</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.893)</td>
<td rowspan="1" colspan="1">84.0 ± 6.6</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.958)</td>
</tr>
<tr><td rowspan="1" colspan="1"> FIQ score</td>
<td rowspan="1" colspan="1">8.3 ± 1.9</td>
<td rowspan="1" colspan="1">9.6 ± 1.8</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.460)</td>
<td rowspan="1" colspan="1">11.9 ± 1.3</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.830)</td>
<td rowspan="1" colspan="1">13.1 ± 1.2</td>
<td rowspan="1" colspan="1">.03 <break></break>
(0.855)</td>
</tr>
<tr><td rowspan="1" colspan="1">BA group</td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1"> VAS score</td>
<td rowspan="1" colspan="1">55.0 ± 20.6</td>
<td rowspan="1" colspan="1">22.4 ± 19.5</td>
<td rowspan="1" colspan="1">.006 <break></break>
(0.720)</td>
<td rowspan="1" colspan="1">13.6 ± 11.8</td>
<td rowspan="1" colspan="1">.01 <break></break>
(0.867)</td>
<td rowspan="1" colspan="1">8.2 ± 9.3</td>
<td rowspan="1" colspan="1">.046 <break></break>
(0.873)</td>
</tr>
<tr><td rowspan="1" colspan="1"> Kujala score</td>
<td rowspan="1" colspan="1">58.0 ± 10.4</td>
<td rowspan="1" colspan="1">62.8 ± 8.6</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.784)</td>
<td rowspan="1" colspan="1">77.9 ± 8.2</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.895)</td>
<td rowspan="1" colspan="1">84.8 ± 6.6</td>
<td rowspan="1" colspan="1">.01 <break></break>
(0.919)</td>
</tr>
<tr><td rowspan="1" colspan="1"> FIQ score</td>
<td rowspan="1" colspan="1">8.6 ± 1.9</td>
<td rowspan="1" colspan="1">10.8 ± 1.9</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.804)</td>
<td rowspan="1" colspan="1">12.1 ± 1.8</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.827)</td>
<td rowspan="1" colspan="1">13.1 ± 1.2</td>
<td rowspan="1" colspan="1"><.001 <break></break>
(0.874)</td>
</tr>
</tbody>
</table>
</alternatives>
<table-wrap-foot><fn id="table-fn2-2325967121989729"><p><italic><sup>a</sup>
</italic>
Data are reported as mean ± SD. <italic>P</italic>
<sub>1</sub>
: baseline vs end of first protocol; <italic>P</italic>
<sub>2</sub>
: baseline vs end of second protocol; and <italic>P</italic>
<sub>3</sub>
: baseline vs 3 months after end of second protocol. ES,
effect size; FIQ, Functional Index Questionnaire; VAS, visual analog
scale.</p>
</fn>
</table-wrap-foot>
</table-wrap>
<table-wrap id="table3-2325967121989729" orientation="portrait" position="float"><label>Table 3</label>
<caption><p>Improvement in Pain and Function<italic><sup>a</sup>
</italic>
</p>
</caption>
<alternatives><graphic xlink:href="10.1177_2325967121989729-table3"></graphic>
<table frame="hsides" rules="groups"><thead><tr><th rowspan="1" colspan="1"></th>
<th rowspan="1" colspan="1">Baseline to End of First Protocol</th>
<th rowspan="1" colspan="1">End of First Protocol to End of Second Protocol</th>
<th rowspan="1" colspan="1">Baseline to 3 mo After End of Second Protocol</th>
</tr>
</thead>
<tbody><tr><td rowspan="1" colspan="1">Protocol A</td>
<td rowspan="1" colspan="1">AB Group (n = 67)</td>
<td rowspan="1" colspan="1">BA Group (n = 42)</td>
<td rowspan="1" colspan="1">All (N = 109)</td>
</tr>
<tr><td rowspan="1" colspan="1"> VAS score</td>
<td rowspan="1" colspan="1">16.2 ± 13.0</td>
<td rowspan="1" colspan="1">8.9 ± 14.7</td>
<td rowspan="1" colspan="1">13.4 ± 14.1</td>
</tr>
<tr><td rowspan="1" colspan="1"> Kujala score</td>
<td rowspan="1" colspan="1">6.3 ± 4.5</td>
<td rowspan="1" colspan="1">7.3 ± 4.0</td>
<td rowspan="1" colspan="1">6.7 ± 4.3</td>
</tr>
<tr><td rowspan="1" colspan="1"> FIQ score</td>
<td rowspan="1" colspan="1">1.4 ± 0.9</td>
<td rowspan="1" colspan="1">1.4 ± 0.9</td>
<td rowspan="1" colspan="1">1.4 ± 0.9</td>
</tr>
<tr><td rowspan="1" colspan="1">Protocol B</td>
<td rowspan="1" colspan="1">BA Group (n = 42)</td>
<td rowspan="1" colspan="1">AB Group (n = 67)</td>
<td rowspan="1" colspan="1">All (N = 109)</td>
</tr>
<tr><td rowspan="1" colspan="1"> VAS score</td>
<td rowspan="1" colspan="1">34.3 ± 18.3</td>
<td rowspan="1" colspan="1">24.3 ± 14.9</td>
<td rowspan="1" colspan="1">27.4 ± 15.7</td>
</tr>
<tr><td rowspan="1" colspan="1"> Kujala score</td>
<td rowspan="1" colspan="1">12.6 ± 6.7</td>
<td rowspan="1" colspan="1">13.0 ± 5.6</td>
<td rowspan="1" colspan="1">12.9 ± 6.0</td>
</tr>
<tr><td rowspan="1" colspan="1"> FIQ score</td>
<td rowspan="1" colspan="1">2.3 ± 1.1</td>
<td rowspan="1" colspan="1">2.3 ± 1.0</td>
<td rowspan="1" colspan="1">2.3 ± 1.1</td>
</tr>
<tr><td rowspan="1" colspan="1"><italic>P</italic>
Value (ES)</td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
<td rowspan="1" colspan="1"></td>
</tr>
<tr><td rowspan="1" colspan="1"> VAS score</td>
<td rowspan="1" colspan="1"><.001 (1.140)</td>
<td rowspan="1" colspan="1"><.001 (1.040)</td>
<td rowspan="1" colspan="1"><.001 (0.938)</td>
</tr>
<tr><td rowspan="1" colspan="1"> Kujala score</td>
<td rowspan="1" colspan="1"><.001 (1.103)</td>
<td rowspan="1" colspan="1"><.001 (1.171)</td>
<td rowspan="1" colspan="1"><.001 (1.187)</td>
</tr>
<tr><td rowspan="1" colspan="1"> FIQ score</td>
<td rowspan="1" colspan="1"><.001 (0.895)</td>
<td rowspan="1" colspan="1"><.001 (0.969)</td>
<td rowspan="1" colspan="1"><.001 (0.895)</td>
</tr>
</tbody>
</table>
</alternatives>
<table-wrap-foot><fn id="table-fn3-2325967121989729"><p><italic><sup>a</sup>
</italic>
Data are reported as mean ± SD. ES, effect size; FIQ,
Functional Index Questionnaire; VAS, visual analog scale.</p>
</fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec sec-type="discussion" id="section10-2325967121989729"><title>Discussion</title>
<p>Our randomized crossover study demonstrated that combining strengthening of the hip
external rotators and abductors with stretching of the hip internal rotators in
association with a standard rehabilitation program provided significantly better
improvement in terms of pain and function in patients with PFPS than a standard
rehabilitation program alone.</p>
<p>Our results are concordant with those reported by Fukuda et al,<sup><xref rid="bibr7-2325967121989729" ref-type="bibr">7</xref>
</sup>
who conducted a randomized controlled trial to investigate the influence of
strengthening the hip abductors and lateral rotators on pain and function in female
patients with PFPS. They reported that rehabilitation programs focusing on
knee-strengthening exercises and knee-strengthening exercises supplemented by
hip-strengthening exercises were both effective in improving function and reducing
pain in sedentary women with PFPS. Furthermore, improvements in pain and function
were greater for the group that performed the hip-strengthening exercises.</p>
<p>The beneficial effects of hip-muscle strengthening have been reported by several
authors. Dolak et al<sup><xref rid="bibr5-2325967121989729" ref-type="bibr">5</xref>
</sup>
found that compared with quadriceps strengthening, hip strengthening provided
better outcomes in terms of pain and function in women with PFPS. They added that
hip strengthening may initially be more efficient, facilitating muscle training
while reducing the exacerbation of patellofemoral symptoms. The benefit of
hip-strengthening exercises has been confirmed, regardless of whether the method of
muscle strengthening was open kinetic chain exercises<sup><xref rid="bibr5-2325967121989729" ref-type="bibr">5</xref>
</sup>
or closed kinetic chain exercises.<sup><xref rid="bibr9-2325967121989729" ref-type="bibr">9</xref>
</sup>
</p>
<p>Based on their trial comparing isolated hip abductor and external rotator
strengthening to no exercise, Khayambashi et al<sup><xref rid="bibr12-2325967121989729" ref-type="bibr">12</xref>
</sup>
concluded that the incorporation of hip strengthening exercises should be
considered when designing a rehabilitation program for female patients with PFPS. A
6-week supplementation of strengthening of the hip abductor and lateral rotator
muscles in a quadriceps exercise program provided additional benefits in patients
with PFPS.<sup><xref rid="bibr15-2325967121989729" ref-type="bibr">15</xref>
,<xref rid="bibr19-2325967121989729" ref-type="bibr">19</xref>
</sup>
However, these results contrast with the findings of Avraham et al,<sup><xref rid="bibr1-2325967121989729" ref-type="bibr">1</xref>
</sup>
who found no difference between hip external rotator and quadriceps
strengthening compared with quadriceps strengthening alone. This could be explained
by the relatively small sample size and the short follow-up period in their
study.</p>
<p>The role of hip- and core-focused rehabilitation in PFPS has been reported. Ferber et al<sup><xref rid="bibr6-2325967121989729" ref-type="bibr">6</xref>
</sup>
conducted a single-blinded, multicenter randomized controlled trial in which
they compared patients with PFPS assigned to either a hip- and core-focused or a
knee-focused 6-week rehabilitation protocol. They found that the hip- and
core-focused rehabilitation protocol provided an earlier resolution of PFPS and
greater overall gains in muscle strength and core endurance than did a knee-focused protocol.<sup><xref rid="bibr6-2325967121989729" ref-type="bibr">6</xref>
</sup>
</p>
<p>We could not find any studies evaluating the effect of a rehabilitation program
combining hip rotator muscle strengthening and stretching in patients with PFPS;
however, generalized stretching protocols including the quadriceps, iliotibial band,
gastrocnemius, and hamstring were reported to have benefits when combined with a
strengthening program, as demonstrated by Moyano et al.<sup><xref rid="bibr14-2325967121989729" ref-type="bibr">14</xref>
</sup>
Halabchi et al<sup><xref rid="bibr8-2325967121989729" ref-type="bibr">8</xref>
</sup>
demonstrated that significantly greater improvements in pain and function
could be obtained with an individualized rehabilitation program incorporating
specific stretching for hip muscles in patients with PFPS who demonstrated
inflexibility on examination.</p>
<p>The washout period served as an indicator of the efficacy of the first administered
protocol. The crossover design allowed us to evaluate both interventions in the same
population, thus reducing recruitment bias and increasing the number of treated
patients.</p>
<sec id="section11-2325967121989729"><title>Limitations</title>
<p>The major limitation of our study was the fact that the washout period remained
subjective and dependent on the patient’s perception of pain. In addition,
participants were not blinded, possibly creating a bias in recording these
subjective complaints. Another limitation was the fact that we recruited
patients from third-line therapy. The lack of a power analysis to estimate the
number of patients needed during the planning stage of the study is certainly
another limitation, but our sample size remains among the largest in the PFPS
literature.</p>
</sec>
</sec>
<sec sec-type="conclusions" id="section12-2325967121989729"><title>Conclusion</title>
<p>Findings from this study confirm the interest in strengthening hip external rotators
and abductors in patients with PFPS. A program of 3 sessions a week for 4 weeks
improved pain and function with maintained benefits for at least 12 weeks beyond the
intervention period. These results suggest the usefulness of adding hip internal
rotator stretching exercises in a rehabilitation program, but their specific benefit
remains unclear. As such, further high-quality clinical trials are needed.</p>
</sec>
</body>
<back><fn-group><fn fn-type="other" id="fn1-2325967121989729"><p>Final revision submitted August 22, 2020; accepted September 30, 2020.</p>
</fn>
<fn fn-type="COI-statement" id="fn2-2325967121989729"><p>The authors declared that there are no conflicts of interest in the authorship
and publication of this contribution. AOSSM checks author disclosures against
the Open Payments Database (OPD). AOSSM has not conducted an independent
investigation on the OPD and disclaims any liability or responsibility relating
thereto.</p>
</fn>
</fn-group>
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