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WhatisthePrevalenceofHipIntra-ArticularPathologiesandOsteoarthritisinActiveAthleteswithHipandGroinPain1.pdf
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Sports Medicine (2019) 49:951–972 https://doi.org/10.1007/s40279-019-01092-y
SYSTEMATIC REVIEW
What is the Prevalence of Hip Intra‑Articular Pathologies and Osteoarthritis in Active Athletes with Hip and Groin Pain Compared with Those Without? A Systematic Review and Meta‑Analysis
Joshua J. Heerey1 · Joanne L. Kemp1 · Andrea B. Mosler1 · Denise M. Jones1 · Tania Pizzari1 · Mark J. Scholes1 · Rintje Agricola2 · Kay M. Crossley1
Published online: 10 April 2019 © Springer Nature Switzerland AG 2019, corrected publication 2019
Abstract Background In athletes, hip and groin pain is considered to be associated with hip intra-articular pathologies and hip osteo- arthritis (OA). A greater understanding of the relationship between hip and groin pain and imaging findings is required. Objective Our objective was to undertake a systematic review and meta-analysis to determine the prevalence of hip intra- articular pathologies and hip OA in athletes with and without hip and groin pain. Methods Seven electronic databases were searched on 29 January 2018 for studies investigating the prevalence of hip intra- articular pathologies and hip OA using X-ray, magnetic resonance imaging, magnetic resonance arthrography or computed tomography. The search, study selection, quality appraisal and data extraction were performed by two independent reviewers. When studies were considered homogenous, meta-analysis was undertaken. A strength of evidence was given to pooled results. Results Twenty studies reporting on the prevalence of hip intra-articular pathologies and hip OA in athletes were identi- fied. Included studies were considered moderate to high risk of bias, with only three studies adjudged as low risk of bias. In asymptomatic athletes, limited evidence identified a labral tear prevalence of 54% per person and moderate evidence of 33% per hip. In symptomatic athletes, moderate evidence of a labral tear prevalence of 20% per hip was found. Moderate evidence of a cartilage defect prevalence of 10% per person was reported in asymptomatic athletes. In symptomatic athletes, cartilage defect prevalence was 7–40%. In asymptomatic athletes, the prevalence of hip OA was 0–17%, compared with 2% in symptomatic athletes. Conclusion The prevalence of hip intra-articular pathologies and hip OA in symptomatic and asymptomatic athletes is vari- able. Labral tears and cartilage defects appear to be seen often in athletes with and without pain. Hip OA is rarely seen in athletes either with or without hip and groin pain. Study Registration PROSPERO registration CRD42017082457.
Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s4027 9-019-01092 -y) contains supplementary material, which is available to authorized users.
* Kay M. Crossley [email protected]
1 La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, College of Science, Health and Engineering, La Trobe University, Bundoora, VIC 3068, Australia
2 Department of Orthopaedics, Erasmus University Medical Center, Rotterdam, The Netherlands
Key Points
Hip intra-articular pathologies are seen in athletes with and without pain.
Labral tears were identified in up to one in every two athletes without pain, highlighting a potential discordant relationship between labral tears and pain in athletes.
Cartilage defects, bone marrow lesions, herniation pits, hip joint effusion, labral degeneration and ligamentum teres tears were observed in symptomatic and asympto- matic athletes.
A complex relationship exists between structural hip conditions identified with imaging and pain in athletes.
952 J. J. Heerey et al.
1 Introduction
Hip and groin pain is common in athletes [1–11], particu- larly those participating in football codes [1, 3, 8, 10–12], ice hockey [5] and dancing [9]. Hip and groin pain consti- tutes up to 18% of all time loss injuries in professional foot- ball (soccer) [1, 13]. Moreover, in football 59% of men and 45% of women will experience groin pain/injury during a competitive season [6]. Many athletes will experience long- standing symptoms [3], with one in three sub-elite football players with hip and groin pain having symptoms for greater than 6 weeks. Chronicity of symptoms is associated with greater difficulties in activities of daily living, reduced qual- ity of life and impaired athletic performance [3].
A number of different and often coexisting clinical enti- ties are proposed to cause hip and groin pain in athletes [14–17]. Hip-related groin pain in athletes often results from femoroacetabular impingement (FAI) syndrome and labral tears [15, 18–20]. The bony morphology associated with FAI syndrome is characterised as cam and/or pincer mor- phology [21]. Cam morphology is present in up to 66% of athletes [22–24], with male athletes eight times more likely to have cam morphology than non-athletes [24]. In athletes, the combination of bony morphology with the repetitive end of range hip movements performed during sporting activities may predispose to mechanical abutment and the develop- ment of symptoms and pain [18–20]. Over time, cam mor- phology may result in intra-articular hip conditions, includ- ing hip osteoarthritis (OA). Cam morphology is associated with intra-articular pathology including labral tears in indi- viduals with and without pain [25–27], and increases the odds of developing OA by up to ten times in older adults [28]. However, little is known about the risk of developing hip OA in athletic populations with cam morphology [16, 28].
Imaging is used to evaluate the presence of intra-articular hip conditions in athletes with hip and groin pain [29, 30]. Our recent review of studies evaluating athletes and non-ath- letes highlighted similar prevalence of select intra-articular hip pathologies in individuals with and without pain, regard- less of level of athletic activity [31]. However, our review did not provide a detailed understanding of the prevalence of such pathologies specifically in athletes. Additional reviews on the prevalence of intra-articular hip conditions includ- ing bony morphology, labral tears and cartilage defects in athletes [22, 23] have not described all frequently reported intra-articular pathologies. The prevalence of hip OA in retired athletes is known [32, 33], but the prevalence in ath- letes currently playing sport is not. Therefore, the aim of this review was to determine the prevalence of intra-articular hip pathologies such as labral tears, cartilage defects, ligamen- tum teres tears, bone marrow lesions (BML), synovitis and
hip OA in athletes with and without hip and groin pain who are currently playing sport.
2 Methods
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used in this sys- tematic review. The protocol for this review was registered on the PROSPERO international prospective register of sys- tematic reviews (http://www.crd.york.ac.uk/PROSP ERO) on 11 December 2017 (registration number CRD42017082457).
2.1 Eligibility Criteria
We included studies if they (1) were written in the English language; (2) were cross-sectional, case-control, case series or cohort designs; (3) included current amateur, semi-pro- fessional or elite athletes with and without hip and groin pain; (4) utilised X-ray, magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA) and/or computed tomography (CT) to determine the presence of intra-articular hip pathologies or OA; (5) had a primary aim of report- ing the prevalence intra-articular hip pathologies or OA in athletes; and (6) evaluated the presence of FAI (including bony morphology) or hip dysplasia and the prevalence of intra-articular hip pathologies or OA. We did not place any restrictions on the age of athletes included in the studies. We excluded studies if they (1) reported on the prevalence of intra-articular hip pathologies or OA in athletes but this was not listed as the primary aim of the study; (2) reported on the prevalence of intra-articular hip pathologies or OA in retired athletes; (3) evaluated the prevalence of FAI (including bony morphology) and hip dysplasia but did not report the pres- ence of intra-articular hip pathologies or OA; (4) identified the presence of intra-articular hip pathologies or OA in ath- letes with Legg–Calvé–Perthes disease or slipped capital femoral epiphysis; (5) used ultrasound or isotopic bone scan to determine the prevalence of intra-articular hip patholo- gies or OA; (6) used hip arthroscopy or open hip surgery to determine the prevalence of intra-articular hip pathologies or OA in athletes; (7) included fewer than five athletes; or (8) were unpublished data, abstracts or systematic reviews and/or were studies not published in the English language
2.2 Search Strategy
Two independent authors (JJH and MJS) undertook a comprehensive search using the OVID MEDLINE, Pub- Med, CINAHL, EMBASE, SPORTDiscus, SCOPUS and Cochrane databases from inception to 29 January 2018. Citation tracking using Google Scholar and the screening of reference lists of included articles was undertaken by one
953Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
author (JJH). Database-specific controlled vocabulary and keyword terms were used for each database (Electronic Sup- plementary Material Online Resource 1).
Endnote X7 (Thomson Reuters, Carlsbad, CA, USA) was used for management of the identified articles. Two authors (JJH, MJS) applied the specified inclusion/exclusion crite- ria to the articles identified during the search process. Each author (JJH, MJS) independently selected the articles eligi- ble for final inclusion in the review. At the completion of this process, consensus was achieved between the two authors on the articles to be included in the review. A third reviewer (JLK) was utilised when the two authors could not agree upon the inclusion of an article.
2.3 Risk of Bias
Risk of bias was independently assessed by two authors (JJH, DMJ). A tool designed to determine the risk of bias in prevalence literature was utilised in the review [34]. The external validity (four questions) and internal validity (six questions) of each included article was evaluated. Each of the ten questions is scored as low risk of bias (LR) or high risk of bias (HR). If an article did not provide adequate infor- mation for a question to be scored, a score of HR was given. In relation to question one, an article was scored as LR if it was considered that the athletes were representative of a wider population of athletes playing the selected sport. In line with a recent review [31], question seven was modified, where an article was considered LR if it reported an intra- class correlation coefficient (ICC) greater than 0.40 and/or Cohen’s kappa (κ) greater than 40% for the method used to assess the prevalence of specific intra-articular hip patholo- gies and/or OA. Each included article was provided with an overall risk of bias score, as determined by the number of HR items. Articles were considered LR if they had 0–3 HR items, moderate risk of bias (MR) if they had 4–5 HR items and HR if they had ≥ 6 HR items [35]. In the event of author disagreement, a third author (JLK) was consulted. The inter- rater agreement was evaluated with κ: excellent agreement was achieved with κ values above 80%, substantial agree- ment with 60–80%, moderate agreement with 40–60% and, finally, poor to fair agreement with values below 40% [36].
2.4 Data Extraction
Two authors (JJH, ABM) independently extracted data from all 20 included articles. The data extracted from each article included author, study design, sport, number of ath- letes, number of hips, sex, age, imaging method used and prevalence of intra-articular hip pathologies and/or OA. In the event of disagreement between the authors on the data extracted, a third author (KMC) was consulted to reach consensus. Authors of the included articles were contacted
if additional data were required. Authors from nine of the 20 included articles were contacted and provided additional data upon request.
2.5 Data Synthesis and Analysis
For this review, athletes were defined as individuals who competed and trained in a specific sport [37]. The athletic populations investigated in this review were not representa- tive of community-based populations; hence, the reported prevalence of intra-articular hip pathologies and/or OA is representative of the frequency of such pathologies in ath- letic individuals with and without pain. To determine the prevalence of intra-articular hip pathologies and/or OA, the number of athletes (cases) was divided by the total athlete population included in the article. We used Comprehensive Meta-Analysis software (version 3.0, Biostat Inc., Engle- wood, NJ, USA) to determine overall prevalence and 95% confidence intervals (CIs). The prevalence of intra-articular hip pathologies and OA was either reported as per person or per hip depending on the method used in the included article. Data deemed eligible for pooling were presented in either per person or per hip format. Primary subgrouping was undertaken based on the presence or absence of hip and groin pain. Secondary grouping included the type of mechanical loading placed on the hip by the sport [38, 39] and imaging modality (MRI, MRA or CT) used for each specific intra-articular hip pathology.
In line with our recent review [31], intra-articular hip pathologies were reported as being present or absent. Car- tilage defects were reported in the primary analysis when femoral and acetabular defects were reported together. Stud- ies that reported acetabular and femoral cartilage separately were analysed qualitatively. A Tonnis grade of ≥ 2 or a joint space width (JSW) of ≤ 2.0 mm was used to define the pres- ence of hip OA [40, 41]. A Tonnis grade of 1 was used to define minor or early features of hip OA [42]. Studies report- ing prevalence of intra-articular hip pathologies in fewer than five athletes were not included in secondary analysis. Studies adjudged to be HR were not considered for meta- analysis [43]. LR and MR studies were included in meta- analyses using a random effects model. Where articles were HR or deemed clinically heterogenous, qualitative analysis was undertaken. The statistical heterogeneity present in the pooled analysis was evaluated using Q and I2 statistics [44, 45] and classified in accordance with Higgins et al. [45]. A strength of evidence was assigned to the pooled results, using previously described modified criteria [31, 46, 47] as follows:
• Strong evidence: pooled results derived from three or more studies, including a minimum of two LR studies, which are statistically homogenous (p > 0.05).
954 J. J. Heerey et al.
• Moderate evidence: pooled results derived from multiple studies, including at least one LR study, which are statis- tically heterogeneous (< 0.05); or from multiple MR and HR studies which are statistically homogenous (p > 0.05).
• Limited evidence: pooled results from multiple HR or MR studies which are statistically heterogeneous (p < 0.05).
3 Results
3.1 Search Results
At the completion of database searching, 847 articles were identified (Fig. 1). Removal of duplicates left 470 articles for screening by title and abstract, and 69 full-text articles that were evaluated for eligibility using the listed inclusion cri- teria. In total, six additional articles [48–53] were retrieved and evaluated for inclusion after the completion of refer- ence list searching and citation tracking. Fifty-five articles
were excluded (Electronic Supplementary Material Online Resource 2), with a total of 20 articles [48–67] included in the review for qualitative and quantitative analysis (Tables 1, 2, 3).
3.2 Risk of Bias Within Studies
Agreement between the two authors occurred on 91% of occasions (182/200 items). A κ-value of 0.82 (95% CI 0.74–0.90) was determined, indicating excellent agreement between authors [36]. In total, five of the 20 (25%) included articles were considered HR, 12 were considered MR and three were LR. In summary, all of the 20 included articles had HR for items 1 and 2, outlining that no study included participants that were considered representative of a wider sporting population and that participants were often selected by convenience. Thirteen of the studies (65%) did not report the reliability of the method used to determine the presence of either hip intra-articular pathology or OA [48–51, 53, 55–58, 60–63]. Finally, ten (50%) of the studies reported
Fig. 1 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow chart
955Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
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ls A
ge : N
R Se
x: 1
(8 %
) F /1
2 (9
2% ) M
3 T
M R
I 1.
5 T
M R
I Su
bj ec
ts A
ny a
bn or
m al
h ip
fi nd
in g:
1 5/
22 ; l
ab ra
l t ea
r: 14
/2 2;
ac
et ab
ul ar
ri m
d am
ag e:
3 /2
2; c
ar til
ag e
de fe
ct : 1
/2 2;
To
nn is
g ra
de 0
: 2 2/
22 ; T
on ni
s g ra
de 1
: 0 /2
2; T
on -
ni s g
ra de
2 : 0
/2 2;
T on
ni s g
ra de
3 : 0
/2 2
C on
tro ls
A ny
a bn
or m
al h
ip fi
nd in
g: 1
0/ 26
; l ab
ra l t
ea r:
10 /2
6;
ac et
ab ul
ar ri
m d
am ag
e: 0
/2 6;
c ar
til ag
e de
fe ct
: 1 /2
6
957Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
the prevalence at a per hip level and not a per person level [49–51, 53, 54, 56, 60, 62, 64, 67] (Table 4).
3.3 Heterogeneity of Included Studies
Heterogeneity was considered low for pooled studies inves- tigating the prevalence of labral tears in symptomatic ath- letes, and high in the studies of asymptomatic athletes. For prevalence of cartilage defects, only studies reporting in asymptomatic athletes were combined in meta-analysis. These studies displayed moderate levels of heterogeneity (I2 43%). When categorised by mechanical hip load, the het- erogeneity observed in pooled data evaluating the prevalence of labral tears and cartilage defects ranged from low (I2 0%) to high (I2 96%).
3.4 Deviation from PROSPERO
The categorisation of sports as either linear or multi-planar was included in the original protocol submitted to PROSPERO. During the review process a previously used method to cat- egorise based on the mechanical load placed on the hip joint by the particular sport was identified [38, 39]. This method was used to improve the generalisability of the reviews findings.
3.5 Study Characteristics
In total, the prevalence of intra-articular hip pathologies and OA was evaluated in 1335 participants and 2352 hips. Twelve studies (315 participants, 637 hips) reported the prevalence of intra-articular hip pathologies in asymptomatic athletes using MRI [48, 52, 53, 55–60, 65–67]. Three studies (627 partici- pants, 1237 hips) investigated the prevalence of hip OA in asymptomatic athletes using X-ray [49, 54, 60]. Four studies
(40 hips) [52, 65–67] investigated the prevalence of intra- articular hip pathologies in symptomatic athletes with MRI. One study (18 participants, 18 hips) utilised MRA to deter- mine the presence of intra-articular hip pathologies in symp- tomatic athletes [61]. One study investigated intra-articular pathology in a combined population of ballet dancers with and without pain [50]. Three studies evaluated the prevalence of OA in symptomatic and asymptomatic athletes [51, 63, 64] and one study reported OA prevalence in only symptomatic athletes [62]. No studies evaluated symptomatic or asympto- matic athletes with CT. In total, 375 (28%) of the athletes were women and 960 were men. The included studies investigated different sports, including American football (n = 174) [49, 62], soccer (n = 100) [53, 57], ice hockey (n = 179) [48, 58, 59, 64], ballet (n = 110) [50, 52, 63, 65, 66], rugby (n = 20) [55], golf (n = 55) [67], skiing (n = 27) [58], track and field (n = 22) [56], capoeira (n = 24) [51] and mixed sports (n = 624) [52, 54, 60, 61, 65, 66]. The level of play reported in the included studies included professional [50, 52, 59, 61, 63–65], elite [48, 49, 54–56, 59, 62, 67], semi-professional [57], amateur or rec- reational [52, 57, 61, 65, 66], and youth/high school level [53, 58]. Athletes participated in cutting (n = 6) [52, 53, 57, 58, 65, 66], flexibility (n = 6) [50–52, 63, 65, 66], impingement (n = 4) [48, 58, 59, 64], asymmetrical (n = 5) [52, 56, 65–67] and endurance sports (n = 1) [56] (Table 5).
3.6 Prevalence of Labral Tears
Twelve studies (484 participants, 754 hips) reported the prevalence of labral tears [48, 50, 53, 55–61, 65, 67]. Five studies reported prevalence per person [48, 57–59, 61], with four studies [50, 53, 56, 67] reporting prevalence per hip and the remaining three studies [55, 60, 65] reporting prevalence per person and per hip.
Table 2 Included studies involving symptomatic athletes only
F female, M male, MRA magnetic resonance arthrography, T Tesla a Mean (standard deviation) b Range c Mean (range)
Study Study design Study population Number of participants (hips)
Demographics Imaging modality Findings (intra-articular hip pathology/osteoar- thritis)
Narvani et al. [61] Case series Subjects Individuals play-
ing sport with groin pain
Subjects 18 (18)
Subjects Agea: 30.5 (8.45)
(17–48b) Sex: 5 (28%) F/13 (72%)
M
Subjects 1 T MRA
Subjects Labral tear: 4/18
Nepple et al. [62] Case series Subjects American foot-
ball athletes at scouting combine
Subjects 107 (123)
Subjects Agec: 22.7 (20–25) Sex: 107 (100%) M
Subjects X-ray
Subjects Tonnis grade 0–1:
121/123; Tonnis grade 2: 2/123; Tonnis grade 3: 0/123
958 J. J. Heerey et al.
Ta bl
e 3
In cl
ud ed
st ud
ie s i
nv ol
vi ng
a sy
m pt
om at
ic a
nd sy
m pt
om at
ic a
th le
te s
St ud
y St
ud y
de si
gn St
ud y
po pu
la tio
n N
um be
r o f p
ar tic
i- pa
nt s (
hi ps
) D
em og
ra ph
ic s
Im ag
in g
m od
al ity
Fi nd
in gs
(i nt
ra -a
rti cu
la r h
ip p
at ho
lo gy
/o ste
oa rth
ri- tis
)
D ic
ke ns
on e
t a l.
[6 7]
a C
ro ss
-s ec
tio na
l Su
bj ec
ts M
al e
go lfe
rs w
ith h
ip p
ai n
C on
tro ls
M al
e go
lfe rs
w ith
ou t h
ip p
ai n
Su bj
ec ts
N R
(1 5)
C on
tro ls
N R
(9 5)
Su bj
ec ts
A ge
: N R
Se x:
1 5
(1 00
% ) M
C on
tro ls
A ge
: N R
Se x:
9 5
(1 00
% ) M
1. 5
T M
R I
Su bj
ec ts
La br
al te
ar : 3
/1 5;
in cr
ea se
d la
br al
si gn
al : 3
/1 5;
ac
et ab
ul ar
c ar
til ag
e de
fe ct
4 /1
5; fe
m or
al c
ar til
ag e
de fe
ct : 1
/1 5;
a ce
ta bu
la r s
ub ch
on dr
al o
ed em
a:
3/ 15
; f em
or al
su bc
ho nd
ra l o
ed em
a: 6
/1 5;
h er
ni a-
tio n
pi t:
4/ 15
; j oi
nt e
ffu si
on : 1
/1 5
C on
tro ls
La br
al te
ar : 2
2/ 95
; i nc
re as
ed la
br al
si gn
al : 2
1/ 95
; ac
et ab
ul ar
c ar
til ag
e de
fe ct
: 6 /9
5; fe
m or
al c
ar ti-
la ge
d ef
ec t:
3/ 95
a ce
ta bu
la r s
ub ch
on dr
al o
ed em
a:
10 /9
5; fe
m or
al su
bc ho
nd ra
l o ed
em a:
1 0/
95 ;
he rn
ia tio
n pi
t: 9/
95 ; j
oi nt
e ffu
si on
: 8 /9
5 H
ar ris
e t a
l. [6
3] C
ro ss
-s ec
tio na
l Su
bj ec
ts Sy
m pt
om at
ic /a
sy m
pt om
at ic
ba
lle t d
an ce
rs
Su bj
ec ts
47 (9
4) Su
bj ec
ts A
ge b : 2
3. 8
(5 .4
) ( 18
–3 9c )
Se x:
2 6
(5 5%
) F /2
1 (4
5% ) M
X -r
ay Su
bj ec
ts To
nn is
g ra
de 0
le ft
hi p:
4 0/
47 ; T
on ni
s g ra
de 1
le ft
hi p:
7 /4
7; T
on ni
s g ra
de 2
le ft
hi p:
0 /4
7; T
on ni
s gr
ad e
3 le
ft hi
p: 0
/4 7;
T on
ni s g
ra de
0 ri
gh t h
ip :
42 /4
7; T
on ni
s g ra
de 1
ri gh
t h ip
: 5 /4
7; T
on ni
s gr
ad e
2 rig
ht h
ip : 0
/4 7;
T on
ni s g
ra de
3 ri
gh t
hi p:
0 /4
7; m
ed ia
l j oi
nt sp
ac e
m al
eb : 3 .6
4 [0
.5 4]
; m
ed ia
l j oi
nt sp
ac e
fe m
al eb : 3
.5 1
[0 .6
5] ; m
id dl
e jo
in t s
pa ce
m al
eb : 3 .9
3 [0
.3 7]
; m id
dl e
jo in
t s pa
ce
fe m
al eb : 3
.8 6
[0 .5
7] ; l
at er
al jo
in t s
pa ce
m al
eb : 4.
39 [0
.5 5]
; l at
er al
jo in
t s pa
ce fe
m al
eb : 4 .3
9 [0
.5 9]
; t ot
al jo
in t s
pa ce
m al
eb : 3 .9
8 [0
.3 9]
; t ot
al
jo in
t s pa
ce fe
m al
eb : 3 .9
2 [0
.5 4]
K ol
o et
a l.
[5 0]
C ro
ss -s
ec tio
na l
Su bj
ec ts
S ym
pt om
at ic
/a sy
m pt
o- m
at ic
b al
le t d
an ce
rs Su
bj ec
ts 30
(5 9)
Su bj
ec ts
A ge
d : 2 4.
6 (1
8– 39
) Se
x: 3
0 (1
00 %
) F
1. 5
T M
R I
Su bj
ec ts
La br
al te
ar : 2
8/ 59
; h ip
s ≥ 2
la br
al te
ar s:
1 2/
59 ;
la br
al d
eg en
er at
io n:
2 4/
59 ; h
ip s ≥
2 la
br al
d eg
en -
er at
iv e
te ar
s: 1
1/ 59
; l ab
ra l o
ss ifi
ca tio
n: 2
/5 9;
hi
ps ≥
2 os
si fie
d le
si on
s: 2
/5 9;
a ce
ta bu
la r c
ar ti-
la ge
d ef
ec t ≤
5 m
m : 1
2/ 59
; a ce
ta bu
la r c
ar til
ag e
de fe
ct : ≥
5 m
m : 1
7/ 59
; h er
ni at
io n
pi t:
31 /5
9 La
rs on
e t a
l. [6
4] C
ro ss
-s ec
tio na
l Su
bj ec
ts Sy
m pt
om at
ic /a
sy m
pt om
at ic
ic e
ho ck
ey p
la ye
rs
Su bj
ec ts
59 (1
18 )
Su bj
ec ts
A ge
b : 2 4.
2 (4
.6 )
Se x:
5 9
(1 00
% ) M
X -r
ay Su
bj ec
ts Jo
in t s
pa ce
b : 4 .1
3 (0
.6 2)
M ar
ic on
da e
t a l.
[5 1]
C ro
ss -s
ec tio
na l
Su bj
ec ts
Sy m
pt om
at ic
/a sy
m pt
om at
ic
ca po
ei ra
p la
ye rs
Su bj
ec ts
24 (4
8) Su
bj ec
ts A
ge b : 3
1. 5
(4 .5
) ( 25
–4 2c )
Se x:
1 0
(4 2%
) F /1
4 (5
8% ) M
X -r
ay Su
bj ec
ts To
nn is
g ra
de 3
: 0 /4
8; T
on ni
s g ra
de 2
: 3 /4
8; T
on ni
s gr
ad e
1: 9
/4 8;
T on
ni s g
ra de
0 3
6/ 48
959Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
Ta bl
e 3
(c on
tin ue
d)
St ud
y St
ud y
de si
gn St
ud y
po pu
la tio
n N
um be
r o f p
ar tic
i- pa
nt s (
hi ps
) D
em og
ra ph
ic s
Im ag
in g
m od
al ity
Fi nd
in gs
(i nt
ra -a
rti cu
la r h
ip p
at ho
lo gy
/o ste
oa rth
ri- tis
)
M ay
es e
t a l.
[6 5]
a C
as e-
co nt
ro l
Su bj
ec ts
M ix
ed sp
or tin
g po
pu la
tio n/
ba l-
le t d
an ce
rs w
ith h
ip p
ai n
la st
3 m
on th
se, f
C on
tro ls
M ix
ed sp
or tin
g po
pu la
tio n/
ba l-
le t d
an ce
rs w
ith ou
t h ip
p ai
ne, f
Su bj
ec ts
N R
(2 5)
C on
tro ls
N R
(1 07
)
Su bj
ec ts
A ge
b, e : 2
7. 9
(4 .6
) A
ge b,
f : 2 9
(5 )
Se xe,
f : 1 8
(7 2%
) F /7
(2 8%
) M C
on tro
ls A
ge b,
e : 2 5.
4 (4
.7 )
A ge
b, f : 2
8. 3
(5 .6
) Se
xe, f : 5
4 (5
0% ) F
/5 3
(5 0%
) M
3 T
M R
I Su
bj ec
ts La
br al
te ar
: 5 /2
5 C
on tro
ls La
br al
te ar
: 4 8/
10 7
M ay
es e
t a l.
[5 2]
a C
as e-
co nt
ro l
Su bj
ec ts
M ix
ed sp
or tin
g po
pu la
tio n/
ba l-
le t d
an ce
rs w
ith h
ip p
ai n
la st
3 m
on th
se, f
C on
tro ls
M ix
ed sp
or tin
g po
pu la
tio n/
ba l-
le t d
an ce
rs w
ith ou
t h ip
p ai
ne, f
Su bj
ec ts
N R
(2 5)
C on
tro ls
N R
(1 07
)
Su bj
ec ts
A ge
b, e : 2
7. 9
(4 .6
) A
ge b,
f : 2 9
(5 )
Se xe,
f : 1 8
(7 2%
) F /7
(2 8%
) M C
on tro
ls A
ge b,
e : 2 5.
4 (4
.7 )
A ge
b, f : 2
8. 3
(5 .6
) Se
xe, f : 5
4 (5
0% ) F
/5 3
(5 0%
) M
3 T
M R
I Su
bj ec
ts Li
ga m
en tu
m te
re s t
ea r:
11 /2
5 C
on tro
ls Li
ga m
en tu
m te
re s t
ea r:
22 /1
07
M ay
es e
t a l.
[6 6]
a C
as e-
co nt
ro l
Su bj
ec ts
M ix
ed sp
or tin
g po
pu la
tio n/
ba l-
le t d
an ce
rs w
ith h
ip p
ai n
la st
3 m
on th
se, f
C on
tro ls
M ix
ed sp
or tin
g po
pu la
tio n/
ba l-
le t d
an ce
rs w
ith ou
t h ip
p ai
ne, f
Su bj
ec ts
N R
(2 5)
C on
tro ls
N R
(1 07
)
Su bj
ec ts
A ge
b, e : 2
7. 9
(4 .6
) A
ge b,
f : 2 9
(5 )
Se xe,
f : 1 8
(7 2%
) F /7
(2 8%
) M C
on tro
ls A
ge b,
e : 2 5.
4 (4
.7 )
A ge
b, f : 2
8. 3
(5 .6
) Se
xe, f : 5
4 (5
0% ) F
/5 3
(5 0%
) M
3 T
M R
I Su
bj ec
ts C
ar til
ag e
de fe
ct : 1
0/ 25
C on
tro ls
C ar
til ag
e de
fe ct
: 3 8/
10 7
F fe
m al
e, M
m al
e, M
RI m
ag ne
tic re
so na
nc e
im ag
in g,
N R
no t r
ep or
te d,
T T
es la
a A ut
ho r p
ro vi
de d
ad di
tio na
l r es
ul ts
n ot
p re
se nt
ed in
o rig
in al
a rti
cl e
b M ea
n (s
ta nd
ar d
de vi
at io
n) c R
an ge
d M ea
n (r
an ge
) e M
al e
da nc
er s a
nd m
al e
m ix
ed a
th le
te s
f Fe m
al e
da nc
er s a
nd fe
m al
e m
ix ed
a th
le te
s
960 J. J. Heerey et al.
3.6.1 Symptomatic Participants
One study (MR) [61] reported a labral tear prevalence of 22% per person, while two studies (one LR and one MR) [65, 67] reported labral tear prevalence per hip in sympto- matic athletes. There was moderate evidence of a labral tear prevalence of 20% (95% CI 10–35) per hip from two studies (one LR and one MR) [65, 67] (Fig. 2).
3.6.2 Asymptomatic Participants
Five studies (four MR and one HR) [48, 55, 57–59] reported the prevalence of labral tears per person in asymp- tomatic athletes. Limited evidence from four studies (four MR) [48, 55, 57, 58] identified a labral tear prevalence of 54% (95% CI 22–83) per person (Fig. 3). The remaining study (HR) [59] reported a labral tear prevalence of 56% in ice hockey players competing at professional and col- legiate level.
Five studies (three HR, one MR and one LR) [53, 56, 60, 65, 67] evaluated labral tear prevalence per hip in athletes using MRI. Moderate evidence from two studies [65, 67] identified a labral tear prevalence of 33% (95% CI 16–57) per hip in asymptomatic athletes (Fig. 2). The three HR stud- ies [53, 56, 60] not included in meta-analysis reported labral tear prevalence per hip in high school athletes (50%) [60], Brazilian youth soccer players (9%) [53], and track and field athletes (5%) [56].
3.6.3 Mixed Participants
One study (MR) [50] evaluated symptomatic and asympto- matic ballet dancers and reported a labral tear prevalence per hip of 47%.
3.6.4 Mechanical Hip Load of the Various Sports
3.6.4.1 Symptomatic Participants One study (LR) [65] reported a labral tear prevalence of 33% in symptomatic athletes participating in flexibility sports. Two studies (one MR and one LR) [66, 67] reported on the prevalence of labral tears in symptomatic athletes participating in asym- metrical sports. One study (MR) [67] of golfers identified a labral tear prevalence of 20%. The remaining study (LR) [66] included fewer than five symptomatic hips and was not included in analysis. In symptomatic basketball players (cutting sport), a labral tear prevalence of 0% was identi- fied (LR) [65]. No studies investigated the prevalence of labral tears in symptomatic athletes participating in con- tact, endurance or impingement sports.
3.6.4.2 Asymptomatic Participants One study (MR) [55] reported a labral tear prevalence of 85% in athletes partici- pating in a contact sport. Three studies (one HR and two MR) reported the prevalence of labral tears in impingement sports. Two studies (two MR) [48, 58] found moderate evi- dence of a labral tear prevalence of 67% (95% CI 56–76) in asymptomatic ice hockey players (Fig. 4). The remaining study (HR) [59] identified labral tears in 56% of ice hockey players without pain. One study (LR) [65] reported a labral tear prevalence of 43% in asymptomatic ballet dancers (flex- ibility sport). Limited evidence from two studies (two MR) [57, 58] found a labral tear prevalence of 33% (95% CI 2–92) per person in athletes participating in cutting sports (Fig. 4). The remaining two studies (one HR and one LR) [53, 65] investigating asymptomatic athletes reported a labral tear prevalence per hip of 9% and 45%, respectively. Three stud- ies (one HR, one MR and one LR) [56, 65, 67] evaluated athletes competing in sports that place asymmetrical loads on the hip joint. Moderate evidence from two studies (one MR and one LR) [65, 67] identified a labral tear prevalence of 33% (95% CI 13–61) in asymptomatic athletes (Fig. 4). The remaining study (HR) [56] in track and field athletes did not provide sufficient information to determine the labral tear prevalence in athletes performing asymmetrical sports, nor in endurance athletes.
3.6.4.3 Mixed Participants One study (MR) [50] reported a labral tear prevalence of 47% in ballet dancers (flexibility sport) with and without pain.
3.7 Prevalence of Cartilage Defects
Eleven studies (466 participants, 736 hips) evaluated the prevalence of cartilage defects [48, 50, 53, 55–60, 66, 67]. In total, four studies analysed prevalence per person [48, 57–59] and five studies reported prevalence per hip [50, 53, 56, 60, 67]. Finally, cartilage defect prevalence was reported per person and per hip in two studies [55, 66].
3.7.1 Symptomatic Participants
Cartilage defect prevalence was not reported per person but reported per hip by two studies (one MR and one LR) [66, 67] in symptomatic athletes. Acetabular (27%) and femoral cartilage defects (7%) were reported independently in golfers (MR) [67], while hip cartilage defects were reported in ballet dancers and mixed sports athletes (40%) (LR) [66].
3.7.2 Asymptomatic Participants
Five studies (one HR and five MR) [48, 55, 57–59] reported cartilage defect prevalence per person in asymptomatic
961Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
athletes. Moderate evidence from three studies (three MR) [55, 57, 58] identified a cartilage defect prevalence of 10% (95% CI 5–19) (Fig. 5). The two remaining studies (one HR and one MR) [48, 59] reported acetabular (0%), femoral (10%) and a combined cartilage defect prevalence of 18% in ice hockey players.
Five studies (three HR, one MR and one LR) [53, 56, 60, 66, 67] evaluated cartilage defect prevalence per hip. One study (LR) [66] reported a cartilage defect prevalence of 36% in professional ballet dancers and mixed sport ath- letes. Two studies (two HR) [53, 60] reported on athletes
competing in high school sport (4%) and youth soccer play- ers (3%). The remaining two studies (one HR and one MR) [56, 67] evaluated acetabular and femoral cartilage defects independently in elite track and field athletes [56] (2% and 2%, respectively) and asymptomatic golfers [67] (6% and 3%, respectively).
3.7.3 Mixed Participants
One study (MR) [50] reported a cartilage defect prevalence of 49% in ballet dancers with and without pain.
Table 4 Included studies’ risk of bias
HR high risk of bias, MR moderate risk of bias, LR low risk of bias Risk of bias items: 1. Was the study’s target population a close representation of the national sporting population in relation to relevant variables, e.g. age, sex, com- petition level? 2. Was the sample frame a true or close representation of the target population? 3. Was some form of random selection used to select the sample OR was a census taken? 4. Was the likelihood of non-response bias minimal? 5. Were data collected directly from the subjects (as opposed to a proxy)? 6. Was an acceptable case definition used in the study? 7. Was the study instrument that measured the parameter of interest (e.g. prevalence of low back pain) shown to have reliability and validity (if necessary)? 8. Was the same mode of data collection used for all subjects? 9. Was the length of the shortest prevalence period for the parameter of interest appropriate? 10. Were the numerator(s) and denominator(s) for the parameter of interest appropriate?
Study External validity Internal validity Overall risk of bias for studyItem 1 Item 2 Item 3 Item 4 Item 5 Item 6 Item 7 Item 8 Item 9 Item 10
Anderson et al. [54] HR HR HR LR LR LR LR LR LR HR MR Ayeni et al. [48] HR HR HR LR LR HR HR LR LR LR MR Dickenson et al. [67] HR HR HR LR LR HR LR LR LR HR MR Farrell et al. [55] HR HR HR LR LR HR HR LR LR LR MR Harris et al. [63] HR HR HR LR LR LR HR LR LR LR MR Kapron et al. [49] HR HR HR HR LR LR HR LR LR HR HR Kolo et al. [50] HR HR HR LR LR LR HR LR LR HR MR Lahner et al. [56] HR HR HR LR LR HR HR LR LR LR MR Lahner et al. [57] HR HR HR LR LR HR HR LR LR HR HR Larson et al. [64] HR HR HR LR LR HR LR LR LR HR MR Mariconda et al. [51] HR HR HR LR LR LR HR LR LR HR MR Mayes et al. [65] HR HR HR LR LR LR LR LR LR LR LR Mayes et al. [52] HR HR HR LR LR LR LR LR LR LR LR Mayes et al. [66] HR HR HR LR LR LR LR LR LR LR LR Narvani et al. [61] HR HR HR LR LR HR HR LR LR LR MR Nepple et al. [62] HR HR HR LR LR LR HR LR LR HR MR Philippon et al. [58] HR HR HR LR LR HR HR LR LR LR MR Silvis et al. [59] HR HR HR HR LR HR HR LR LR LR HR Yépez et al. [53] HR HR HR LR LR HR HR LR LR HR HR Yuan et al. [60] HR HR HR HR LR HR HR HR LR HR HR Overall risk of bias for item 20 HR
0 LR 20 HR 0 LR
20 HR 0 LR
3 HR 17 LR
0 HR 20 LR
11 HR 9 LR
14 HR 6 LR
1 HR 19 LR
0 HR 20 LR
10 HR 10 LR
962 J. J. Heerey et al.
3.7.4 Mechanical Hip Load of the Various Sports
3.7.4.1 Symptomatic Participants One study (LR) [66] reported a cartilage defect prevalence of 53% in symp- tomatic athletes participating in a flexibility sport. Two studies (one MR and one LR) [65, 67] evaluated the preva- lence of cartilage defects in sports that cause asymmetrical hip loading. One study (MR) [67] in symptomatic golfers
reported the prevalence of cartilage defects on the acetabu- lum (27%) and femur (7%) separately. The final study (LR) [66] included fewer than five symptomatic hips and was not included in the final analysis. One study (LR) [66] reported a cartilage defect prevalence of 17% per hip in basketball athletes (cutting sport) with hip pain. None of the included studies reported the prevalence of cartilage defects in symp-
Table 5 Mechanical load placed on hip joint by sport
Athlete sports category [39] Study
Cutting (soccer, basketball, lacrosse, field hockey, downhill skiing, snowboarding) Lahner et al. [57] Mayes et al. [52, 65, 66] Philippon et al. [58] Yepez et al. [53]
Flexibility (dancing, gymnastics, yoga, cheerleading, figure skating, synchronised swimming, martial arts, rock climbing)
Harris et al. [63] Kolo et al. [50] Mariconda et al. [51] Mayes et al. [52, 65, 66]
Contact (football, rugby, wrestling) Farrell et al. [55] Kapron et al. [49] Nepple et al. [62]
Impingement (ice hockey, crew/rowing, baseball catching, water polo, equestrian polo, breaststroke swimming, weight lifting, bobsled, CrossFit, horseback riding)
Ayeni et al. [48] Philippon et al. [58] Silvis et al. [59] Larson et al. [64]
Asymmetric/overhead (baseball, softball, tennis, golf, volleyball, athletic field events, fencing, badminton, cricket, squash, racquetball, handball)
Lahner et al. [56] Dickenson et al. [67] Mayes et al. [52, 65, 66]
Endurance (track, cross-country, other running, cycling, swimming [not breaststroke], cross-country skiing, biathlon, aerobics)
Lahner et al. [56]
Not reported Anderson et al. [54] Yuan et al. [60] Narvani et al. [61]
Fig. 2 Prevalence and 95% confidence interval (CI) of labral tears per hip in symptomatic and asymptomatic athletes
963Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
tomatic athletes participating in contact, impingement or endurance sports.
3.7.4.2 Asymptomatic Participants Three studies (one HR, one MR and one LR) [56, 66, 67] reported the prevalence of cartilage defects in athletes participating in sports that place an asymmetrical load on the hip joint. One study (LR) [66] reported a cartilage defect prevalence per hip of 50% in ten- nis players without pain. One (MR) [67] of the remaining two studies evaluated acetabular (6%) and femoral cartilage defects (3%) independently in golfers without hip pain. The remaining study (HR) [56] was not included in analysis as it
combined information on athletes performing asymmetrical and endurance sports. One study (LR) [66] in ballet dancers (flexibility sport) reported a cartilage defect prevalence of 33%. In contact athletes, one study (MR) [55] identified a cartilage defect prevalence of 20%. In asymptomatic cutting athletes, moderate evidence from two studies (two MR) [57, 58] identified a cartilage defect prevalence of 5.8% (95% CI 2–15) (Fig. 6). Two additional studies (one HR and one LR) [53, 66] reported a cartilage defect prevalence per hip in asymptomatic cutting athletes of 34% (basketball play- ers) and 3% (youth soccer players). Three studies (one HR and two MR) [48, 58, 59] evaluated the prevalence of carti-
Fig. 3 Prevalence and 95% confidence interval (CI) of labral tears per person in asymptomatic athletes
Fig. 4 Prevalence and 95% confidence interval (CI) of labral tears per person and per hip in asymptomatic athletes in cutting, impingement and asymmetrical sports
964 J. J. Heerey et al.
lage defects in athletes participating in impingement sports (ice hockey players). Two of the three studies (one HR and one MR) [58, 59] identified a cartilage defect prevalence of 8% and 18%, respectively. The remaining study reported acetabular (0%) and femoral cartilage defects (10%) inde- pendently. One study (HR) [56] reported the prevalence of cartilage defects in a combined population of endurance and asymmetrical/overhead athletes, which resulted in the study not being included in analysis.
3.7.4.3 Mixed Participants One study (MR) [50] found a cartilage defect prevalence of 49% per hip in a population of ballet dancers (flexibility sport) with and without pain.
3.8 Prevalence of Hip Osteoarthritis
Seven studies (877 participants, 1646 hips) reported the prevalence of hip OA [49, 51, 54, 60, 62–64]. Five stud- ies (804 participants, 1504 hips) reported prevalence per hip [49, 51, 54, 62, 64], with two studies reporting hip OA prevalence per person and per hip [60, 63].
3.8.1 Symptomatic Participants
One study (MR) [62] reported the prevalence of hip OA per hip in symptomatic athletes. A hip OA (Tonnis grade ≥ 2/ JSW of ≤ 2.0 mm) prevalence of 2% was reported in National Football League (NFL) athletes attending the NFL scouting combined with a history of pain or injury around the hip [62].
3.8.2 Asymptomatic Participants
Three studies (two HR and one MR) evaluated asymptomatic athletes for hip OA using X-ray [49, 54, 60]. One study (HR) [60] reported hip OA prevalence per person in high school athletes (0%). Two studies (one HR and one MR) [49, 54] reported early hip OA (Tonnis grade 1) and hip OA per hip. In a group of mixed senior athletes [54] the prevalence of early hip OA and hip OA was 32% and 17%, respectively. The remaining study [49] reported a prevalence of early hip OA of 16%, with no collegiate NFL players having hip OA.
Fig. 5 Prevalence and 95% confidence interval (CI) of cartilage defects per person in asymptomatic athletes
Fig. 6 Prevalence and 95% confidence interval (CI) of cartilage defects per person in asymptomatic athletes in cutting sports
965Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
3.8.3 Mixed Participants
Three studies (three MR) reported early hip OA and hip OA prevalence in athletes with and without pain [51, 63, 64]. One study [63] reported prevalence per person and per hip in professional ballet dancers. Hip OA was not found in any ballet dancer using Tonnis grade and mean joint space. However, early hip OA was present in 13% of ballet dancers hips [63]. Two studies (two MR) [51, 64] reported hip OA per hip. One study [51] evaluating capoeira players reported hip OA (6%) and early hip OA (19%) using Tonnis grade, with the remaining study [64] reporting a mean minimum joint space of 4.1 mm in ice hockey players.
3.9 Other Pathologies
3.9.1 Symptomatic Participants
3.9.1.1 Bone Marrow Lesions One study (MR) [67] iden- tified the presence of acetabular (20%) and femoral head BML (40%) in golfers with hip pain.
3.9.1.2 Herniation Pits One study (MR) [67] evaluated the prevalence of herniation pits in golfers with hip pain (27%).
3.9.1.3 Hip Joint Effusion One study (MR) [67] reported a prevalence of hip joint effusion per hip of 7% in golfers with hip pain.
3.9.1.4 Labral Degeneration One study [67] reported a prevalence of labral degeneration per hip of 20% in golfers with hip pain.
3.9.1.5 Ligamentum Teres Tears One study (LR) [52] reported the prevalence of ligamentum teres tears per hip (44%) in symptomatic ballet dancers and mixed athletes.
3.9.2 Asymptomatic Participants
3.9.2.1 Bone Marrow Lesions Two studies (one HR and one MR) [53, 67] reported the prevalence of BML per hip in asymptomatic athletes. One study [53] evaluated youth soc- cer players (21%), with the remaining study [67] reporting acetabular (11%) and femoral BML (11%) independently in asymptomatic golfers.
3.9.2.2 Herniation Pits Four studies (two HR and two MR) [48, 53, 56, 67] evaluated the prevalence of herniation pits in asymptomatic athletes. One study (MR) [48] reported a herniation pit prevalence per person in ice hockey athletes of 10%. The remaining three studies (two HR and one MR)
[53, 56, 67] reported prevalence per hip in track and field athletes (7%), youth soccer players (4%) and golfers (9%).
3.9.2.3 Hip Joint Effusion Two studies (one HR and one MR) [59, 67] identified the prevalence of hip joint effusion in asymptomatic athletes. One study (MR) [67] reported a prevalence of 8% in asymptomatic golfers. The remaining study (HR) [59] in ice hockey players identified a prevalence of 0%.
3.9.2.4 Labral Degeneration Two studies (one HR and one MR) [53, 67] reported a labral degeneration prevalence of 2% and 22% in asymptomatic youth soccer players and golf- ers, respectively.
3.9.2.5 Ligamentum Teres Tears One study (LR) [52] reported a prevalence of ligamentum teres tears per hip of 21% in a mixed population of athletes.
3.10 Other Pathologies Reported in Fewer than Two Studies
Intra-articular hip pathologies that were reported in less than one symptomatic and one asymptomatic study are presented in Electronic Supplementary Material Online Resource 3.
4 Discussion
This systematic review highlights that imaging defined intra- articular hip pathologies are observed in athletes with and without pain. Across the included studies, considerable het- erogeneity existed in regard to the methods used to evaluate the presence of intra-articular hip pathologies. Moreover, athletes participated in a wide range of sports and competi- tion levels, resulting in limited comparability between the included studies. Hence, caution should be taken when com- paring differences in prevalence of intra-articular patholo- gies between studies and in athletes with and without pain. In particular, we identified that labral tears on MRI are observed in up to 54% of athletes without pain and 22% of athletes with pain. Cartilage defects were identified in symptomatic (7–40%) and asymptomatic athletes (0–36%). Qualitative analysis identified that bone marrow lesions, herniation pits, labral degeneration, ligamentum teres tears and joint effusion appear to be prevalent in athletes with and without pain. Our review identified that features associ- ated with early radiographic hip OA (Tonnis grade 1) appear more frequently than radiographic hip OA (Tonnis grade ≥ 2/ JSW of ≤ 2.0 mm) in athletes currently playing sport regard- less of pain.
966 J. J. Heerey et al.
4.1 Review Findings
Labral tears have long been considered a cause of hip and groin pain in athletes [68–70]. A combination of the dynamic movements performed in sport and the high prevalence of bony hip morphology, in particular cam morphology, is believed to place athletes at greater risk of labral tears. In athletes without pain, we identified moderate evidence of a labral tear prevalence per hip of 33%, while in athletes with pain there was moderate evidence of a labral tear prevalence per hip of 20%. These findings provide further evidence of the complex relationship between labral tears and experi- ence of pain [27, 31, 71, 72]. Furthermore, it appears that athletes do not have a higher prevalence of labral tears than non-athletic individuals, regardless of pain status [22, 23, 31]. Debate exists around the optimal management of labral tears [73–75]. It is proposed that the integrity of the labrum is important for joint function and maintenance of tissue homeostasis [73, 74]. Restoration of labral tissue integrity might be achieved with surgical approaches, and this may result in improved patient function and pain [73–75]. How- ever, such approaches are supported by low levels of evi- dence [73–75], and may result in varied return to sport and/ or performance rates in athletes [76]. Our findings highlight that up to one in every two asymptomatic athletes can be active in sport with a labral tear, ultimately questioning the clinical significance of labral tears in some athletes with pain. Moreover, it highlights the importance of considering ‘non-structural’ factors in an athlete with hip and groin pain [77]. Future work should focus on gaining a greater under- standing of the long-term implications for symptomatic and asymptomatic athletes with labral tears, in order to provide appropriate management of these athletes.
Cartilage defects were seen in symptomatic and asympto- matic athletes. The prevalence of cartilage defects in symp- tomatic athletes ranged from 7% to 40%, with three of the four studies reporting a prevalence greater than 25%. Our pooled data identified moderate evidence of a prevalence of 10% in asymptomatic athletes with a mean age of less than 25 years. In addition, five of the remaining studies not included in the meta-analysis reported a cartilage defect prevalence of less than 10%. The high prevalence of carti- lage defects seen in symptomatic athletes in this review is similar to that seen in older individuals with and without pain [71, 78], but lower than in our previous review [31]. Injury to the articular cartilage affects joint homeostasis, in addition to biomechanical and neuromuscular function [79]. This alteration in joint function combined with athletic activity may accelerate hip joint degenerative change, which is known to occur more frequently in retired athletes [33, 80]. However, longitudinal studies confirming this causa- tion are currently lacking and should be a focus of future work. Importantly, articular cartilage is deficient of neural
and vascular supply, rendering it unable to produce pain [81]. This understanding is reflected in the variable rela- tionship seen between cartilage defects and pain [71, 72, 78, 82]. In relation to our findings, it is likely that the presence of cartilage defects in symptomatic athletes indicates the involvement of inflammatory mediators, subchondral bone and peri-articular tissues, which are all capable of causing nociception [81]. This suggests that cartilage defects are likely to be a precursor to OA in susceptible individuals.
Our review highlights that hip OA is not commonly seen in athletes who are currently competing at an elite or pro- fessional level, even if they have hip and groin pain. This finding is of particular interest, as elite male athletes have a greater prevalence of OA [33] and likelihood of undergo- ing hip arthroplasty (odds ratio = 2.5) after they have retired from sport than age-matched controls [80]. The prevalence of hip OA in asymptomatic senior athletes appears similar to that of older non-athletic populations (17% vs. 15%) [54, 83]. In addition, our review indicates that radiographic fea- tures associated with early hip OA are seen in younger ath- letes regardless of the presence or absence of pain [49, 51, 63]. Our findings highlight a discordant relationship between radiographic features associated with early hip OA and pain in athletes currently playing sport, which is consistent with pre- vious work in older populations [84]. In the included studies, OA was measured using X-ray, whilst other pathologies were measured using MRI or MRA. Since radiographic measures are insensitive to early changes in articular cartilage integrity [85], our findings may underestimate the true disease preva- lence in athletes. The use of imaging methods with greater sensitivity to early features of OA may be important for iden- tifying athletes at risk of progression to hip OA.
Bone marrow lesions, herniation pits, labral degeneration, ligamentum teres tears and hip joint effusions were seen in symptomatic and asymptomatic athletes. These findings are congruent with our recent review [31]. Bone marrow lesions were reported in up to 40% of athletes with pain. This rela- tionship between pain and BML has been demonstrated pre- viously, albeit in older non-athletic populations [71, 72]. The prevalence of BML identified in this review is lower than in our previous review [31]. However, BML are known to be seen more frequently in individuals with OA [71, 78, 86], which was seen in very few athletes included in this review. In relation to ligamentum teres tears, debate currently exists regarding its role in both joint stability and pain generation [87–91]. The only study that reported on the prevalence of ligamentum teres tears in ballet dancers and mixed sport athletes described a high prevalence in those with hip pain (44%) [52]. The high prevalence of ligamentum teres tears observed in athletes may reflect the demands placed on this ligament during sporting activity, particularly those sports requiring large ranges of hip motion. Hip joint effusion was present in athletes with and without pain. Hip joint effusion
967Prevalence of Intra-Articular Hip Pathologies in Athletes With and Without Pain
is often considered a surrogate marker of synovitis when evaluated by MRI without contrast [92]. However, optimal evaluation of synovitis requires contrast-enhanced MRI [78, 92], which was not used in the two studies reporting hip joint effusion in our review. The prevalence rates identified appear similar to older populations with and without pain [72], but lower than individuals with radiographic hip OA or MRI-defined cartilage defects [78, 93]. The association between pain, symptoms and effusion appears variable [72, 78] and requires greater understanding in athletic individuals to enable appropriate intervention.
Athletes competing in sports that place contact, impinge- ment and flexibility loads on the hip joint appear to have a high prevalence of labral tears. In relation to cartilage defects, there appears to be less variation between sports when categorised by mechanical hip load. However, ath- letes performing flexibility, cutting and asymmetrical sports appear to have a high prevalence of cartilage defects. None of the included studies in our review reported the preva- lence of labral tears in symptomatic athletes competing in impingement or contact sports. However, existing work not included in our review highlights that labral tears appear in similar rates in athletes with and without pain competing in impingement (67% vs. 69%) [48, 58, 70] and contact sports (85% vs. 89%) [55, 94]. In athletes participating in flexibility sports, labral tears (33% and 43%) and cartilage defects (53% and 33%) are commonly seen in symptomatic and asympto- matic athletes, respectively. This review has highlighted the large variation in the prevalence of labral tears and cartilage defects in athletes with and without pain, particularly when sports are categorised by mechanical load placed on the hip joint. As such, a combination of bony morphology, which is seen in a high percentage of athletes [22, 23, 95, 96], and specific hip load may be related to the development of spe- cific intra-articular hip pathologies in athletes.
The diagnostic accuracy of the imaging techniques used to evaluate the presence of intra-articular pathology may have influenced the findings of this review. Magnetic resonance imaging without contrast has known limitations in relation to the identification of labral tears [97–99]. In particular, the moderate sensitivity and specificity of MRI with 1.5 (1.5 T) and 3 Tesla (3 T) field strengths may result in the over- and/ or underestimation of the prevalence of labral tears. Since only one of the included studies used contrast-enhanced MRI, the prevalence of labral tears reported in this review may have been underestimated [97–99]. Similarly, the diag- nostic accuracy of MRI without contrast for chondral defects has been shown to be variable across two reviews [99, 100]. We identified a higher prevalence of cartilage defects in ath- letes with pain than in those without pain in studies using MRI without contrast. Five of the 11 studies used 3 T MRI to evaluate cartilage defects [55, 58–60, 66]. The evaluation of cartilage defects with 3 T MRI has shown superiority for
the recognition of cartilage defects compared with lower field strength approaches [101, 102]. Importantly, six of the remaining 11 studies used 1.5 T MRI, which provides only limited sensitivity for the identification of cartilage defects [99, 100]; this may have resulted in the under-reporting of cartilage defects in some athletes included in our review.
Seventeen of the 20 included studies were considered to be MR to HR. In particular, the included studies evaluated athletes that were selected by convenience or from specific competitions or organisations, and not deemed representa- tive of wider athletic populations. Future work should focus on evaluating athletes from a larger range of clubs/organi- sations to improve generalisability. Of the included studies, only six (30%) reported the reliability or extent of agree- ment for the methods used to determine each of the imaging- defined pathologies. This finding should be considered when interpreting the prevalence of intra-articular pathologies in this review. Our decision to exclude HR studies from our meta-analyses is in line with recent recommendations [43].
Moderate to high levels of heterogeneity were observed in most pooled analyses performed in this review, which may be related to the observed variability across studies in relation to sport and competition level. In addition, athlete sex, age, variation in the imaging type and specific imaging parameters should be considered. Interestingly, when data were pooled based on the mechanical hip load, two of the four pooled analyses demonstrated low levels of heterogene- ity, indicating that intra-articular hip pathology prevalence may be influenced by the specific physical requirements of a sport.
4.2 Limitations
A number of limitations need to be considered when inter- preting the findings of our review. First, a number of clini- cal entities may be associated with hip and groin pain in athletes [14–17]. In this review, we evaluated athletes based on the subjective presence or absence of pain, rather than with more objective measures [14]. In light of this, many of the imaging-defined intra-articular hip pathologies may indeed be incidental findings and unrelated to an athlete’s hip and groin pain. Second, careful consideration is needed when generalising the findings of our review. The included studies investigated athletes from a broad range of sports and competition levels, meaning that our findings can only be extrapolated to athletes competing at similar levels of competition and sport. The exclusion of studies investigat- ing athletes with other hip conditions, including slipped capital femoral epiphysis and Legg–Calvé–Perthes disease, reduces the generalisability of our findings to athletes with such conditions. Importantly, none of the athletes had their intra-articular pathologies or hip OA confirmed by open or arthroscopic hip surgery. The authors acknowledge that
968 J. J. Heerey et al.
surgery is considered the gold standard for the identification of intra-articular hip conditions. However, such an approach is not considered reasonable for athletes without hip pain. Finally, not including studies published in languages other than English may have resulted in some relevant studies not being included in this review.
4.3 Future Directions/Research Priorities
Future work should establish a greater understanding of the prevalence of intra-articular hip pathologies in both symp- tomatic and asymptomatic athletes. To correctly select athletes for surgical interventions it would seem prudent that we understand the relevance of imaging-defined intra- articular hip pathologies in athletes with hip and groin pain. Future studies may choose to compare intra-articular find- ings between athletes of varying ages and/or competition levels in order to understand the impact of age and level of play on the prevalence of findings in athletes. Using recom- mended clinical entities [14] to categorise an athlete with hip and groin pain may allow a greater understanding of prevalence of intra-articular hip conditions in athletes with specific clinical presentations. Finally, longitudinal studies are required to provide evidence supporting the relationship between intra-articular pathologies and OA development or progression in athletes [103].
5 Conclusion
Our systematic review identified that imaging-defined intra- articular hip pathologies are seen in athletes with and with- out pain. In particular, labral tears were identified in one in every two athletes without pain, highlighting a complex, poorly understood and potentially arbitrary (at least in some cases) relationship between labral tears and pain in athletes. Cartilage defects are seen in athletes with and without pain. Importantly, hip OA was rarely seen in athletes, regard- less of whether they had pain or not. Bone marrow lesions, herniation pits, hip joint effusion, labral degeneration and ligamentum teres tears were observed in symptomatic and asymptomatic athletes. Two out of three asymptomatic ath- letes competing in impingement sports had imaging-defined labral tears. In summary, our findings highlight the complex relationship between structural hip conditions identified with imaging and pain in athletes.
Author contributions JJH, JLK, ABM, DMJ, TP, MJS, RA and KMC were responsible for the creation and planning of the review. JJH and JLK were responsible for the search strategy utilised. JJH, JLK and DMJ developed the strategy to evaluate study quality. JJH, ABM and KMC were involved in the data extraction process. JJH wrote the final manuscript, with all authors assisting in revising content.
Compliance with Ethical Standards
Conflict of interest Joshua J. Heerey, Joanne L. Kemp, Andrea B. Mosler, Denise M. Jones, Tania Pizzari, Mark J. Scholes and Rintje Agricola declare they have no competing interests. Kay Crossley is a recipient of an NHMRC (National Health and Medical Research Coun- cil; Australia) Project Grant (GNT1088683), which provided funding to support this research.
Funding No financial support was received for the conduct of this study or preparation of this manuscript.
Provenance and peer review This review was not commissioned; the article was externally peer reviewed.
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- What is the Prevalence of Hip Intra-Articular Pathologies and Osteoarthritis in Active Athletes with Hip and Groin Pain Compared with Those Without? A Systematic Review and Meta-Analysis
- Abstract
- Background
- Objective
- Methods
- Results
- Conclusion
- Study Registration
- 1 Introduction
- 2 Methods
- 2.1 Eligibility Criteria
- 2.2 Search Strategy
- 2.3 Risk of Bias
- 2.4 Data Extraction
- 2.5 Data Synthesis and Analysis
- 3 Results
- 3.1 Search Results
- 3.2 Risk of Bias Within Studies
- 3.3 Heterogeneity of Included Studies
- 3.4 Deviation from PROSPERO
- 3.5 Study Characteristics
- 3.6 Prevalence of Labral Tears
- 3.6.1 Symptomatic Participants
- 3.6.2 Asymptomatic Participants
- 3.6.3 Mixed Participants
- 3.6.4 Mechanical Hip Load of the Various Sports
- 3.6.4.1 Symptomatic Participants
- 3.6.4.2 Asymptomatic Participants
- 3.6.4.3 Mixed Participants
- 3.7 Prevalence of Cartilage Defects
- 3.7.1 Symptomatic Participants
- 3.7.2 Asymptomatic Participants
- 3.7.3 Mixed Participants
- 3.7.4 Mechanical Hip Load of the Various Sports
- 3.7.4.1 Symptomatic Participants
- 3.7.4.2 Asymptomatic Participants
- 3.7.4.3 Mixed Participants
- 3.8 Prevalence of Hip Osteoarthritis
- 3.8.1 Symptomatic Participants
- 3.8.2 Asymptomatic Participants
- 3.8.3 Mixed Participants
- 3.9 Other Pathologies
- 3.9.1 Symptomatic Participants
- 3.9.1.1 Bone Marrow Lesions
- 3.9.1.2 Herniation Pits
- 3.9.1.3 Hip Joint Effusion
- 3.9.1.4 Labral Degeneration
- 3.9.1.5 Ligamentum Teres Tears
- 3.9.2 Asymptomatic Participants
- 3.9.2.1 Bone Marrow Lesions
- 3.9.2.2 Herniation Pits
- 3.9.2.3 Hip Joint Effusion
- 3.9.2.4 Labral Degeneration
- 3.9.2.5 Ligamentum Teres Tears
- 3.10 Other Pathologies Reported in Fewer than Two Studies
- 4 Discussion
- 4.1 Review Findings
- 4.2 Limitations
- 4.3 Future DirectionsResearch Priorities
- 5 Conclusion
- References
