Return to Sport After Surgical Management of Proximal Hamstring Avulsions: A Systematic Review and Meta-analysis

Abstract

Objective:
To assess the rates and timing of return to sport for the surgical management of proximal hamstring avulsions (PHAs).

Methods:
Three databases, PubMed, MEDLINE, and EMBASE, were searched from database inception until October 7, 2017, by 2 reviewers independently and in duplicate. The inclusion criteria were studies reporting return to sport outcomes for surgical management of acute, chronic, complete, and partial PHA. The rate of return to sports was combined in a meta-analysis of proportions using a random-effects model.

Results:
Overall, 21 studies with a total of 846 patients met the inclusion criteria, with a mean age of 41.4 years (range, 14-71 years) and a mean follow-up of 37.8 months (range, 6-76 months). Two studies were of prospective comparative design (level II), 2 were retrospective comparative (level III), 8 were prospective case series (level IV), and 9 were retrospective case series (level IV). The overall mean time to return to sport was 5.8 months (range, 1-36 months). The pooled rate of return to any sport participation was 87% [95% confidence interval (CI), 77%-95%]. The pooled rate of return to preinjury level of sport was 77% (95% CI, 66%-86%).

Conclusions:
Pooled results suggest a high rate of return to sport after surgical management of PHA; however, this was associated with a lower preinjury level of sport. No major differences in return to sport were found between partial versus complete and acute versus chronic PHA.

Full text

General Review
Return to Sport After Surgical Management of
Proximal Hamstring Avulsions: A Systematic
Review and Meta-analysis
Ryan P. Coughlin, MD, FRCSC,* Jeffrey Kay, MD,* Ajaykumar Shanmugaraj, BHSc,† Muzammil Memon, MD,*
Leen Naji, MD,* and Olufemi R. Ayeni, MD, PhD, FRCSC*
Abstract
Objective: To assess the rates and timing of return to sport for the surgical management of proximal hamstring avulsions (PHAs).
Methods: Three databases, PubMed, MEDLINE, and EMBASE, were searched from database inception until October 7, 2017,
by 2 reviewers independently and in duplicate. The inclusion criteria were studies reporting return to sport outcomes for surgical
management of acute, chronic, complete, and partial PHA. The rate of return to sports was combined in a meta-analysis of
proportions using a random-effects model. Results: Overall, 21 studies with a total of 846 patients met the inclusion criteria, with
a mean age of 41.4 years (range, 14-71 years) and a mean follow-up of 37.8 months (range, 6-76 months). Two studies were of
prospective comparative design (level II), 2 were retrospective comparative (level III), 8 were prospective case series (level IV), and 9
were retrospective case series (level IV). The overall mean time to return to sport was 5.8 months (range, 1-36 months). The pooled
rate of return to any sport participation was 87% [95% confidence interval (CI), 77%-95%]. The pooled rate of return to preinjury level
of sport was 77% (95% CI, 66%-86%). Conclusions: Pooled results suggest a high rate of return to sport after surgical
management of PHA; however, this was associated with a lower preinjury level of sport. No major differences in return to sport were
found between partial versus complete and acute versus chronic PHA.
Key Words: proximal hamstring avulsions, return to sport
(Clin J Sport Med 2018;00:1–14)
INTRODUCTION
The hamstring muscle group (biceps femoris, semimembra-
nosus, and semitendinosus muscles) is frequently injured,
accounting for 25% to 30% of all muscle strains.
1,2
Proximal
hamstring avulsions (PHA), which can result in significant
disability, prolonged recovery, and rehabilitation, are preva-
lent among the athletic and middle-age populations.
2–4
Common mechanisms of injury include eccentric lengthening
as a result of hyperflexion of the hip with the knee in extension
and occur during activities involving rapid limb acceleration
and deceleration.
2,5,6
Proponents of nonoperative treatment for PHA suggest that
a single-tendon tear or multitendon tears with less than 2-cm
retraction may not require surgical intervention.
7
The non-
operative treatment can, however, lead to knee flexion
weakness, difficulty with prolonged sitting, and is often
associated with inferior outcomes in comparison with surgical
repair.
8,9
When considering operative management, it is
generally agreed that acute repairs are those that are treated
within 4 weeks after injury, whereas delayed repairs are
treated after 4 weeks.
5,10,11
Injury chronicity is important
because delayed repairs are often difficult to treat because of
increased tendon retraction, poor tissue quality, and the
potential for fibrosis around the sciatic nerve.
11
Previous studies have investigated the outcomes of non-
operative versus operative treatment as well as acute versus
delayed surgical repair of PHA. In a systematic review of 387
participants undergoing PHA repair, van der Made et al
12
reported the postoperative outcomes of PHA repair and
compared the outcomes of acute versus delayed repair using
different surgical techniques. It was found that both acute
and delayed surgical repair of PHA can both lead to
improved patient reported outcomes. Bodendorfer et al
8
systematically assessed the outcomes of nonoperative and
operative treatment of 795 PHAs and concluded a higher
patient satisfaction, return of strength, athletic capacity, and
overall functional recovery in patients with surgery. More-
over, those undergoing acute repair had higher patient
satisfaction, less pain, return of strength, and higher
functional scores when compared with delayed repair.
However, the return to sport and preinjury activity level
rates are poorly reported in systematic reviews, providing
clinicians limited information in regards to the rate and
timing at which patients reach these outcomes postopera-
tively. Hence, the objective of this review was to systemat-
ically assess the timing, and return to sport and preinjury
Submitted for publication March 23, 2018; accepted September 18, 2018.
From the *Divisionof Orthopaedic Surgery, Department of Surgery, McMaster
University, Hamilton, ON, Canada;
†
Department of Health Research
Methods, Evidence, and Impact, McMaster University, Hamilton, ON,
Canada.
The authors report no conflicts of interest.
Corresponding Author: Olufemi R. Ayeni, MD, PhD, FRCSC, McMaster University
Medical Centre, 1200 Main St West, 4E15, Hamilton, ON L8N 3Z5, Canada
(ayenif@mcmaster.ca).
Supplemental digital content is available for this article. Direct URL citations appear
in the printed text and are provided in the HTML and PDF versions of this article on
the journal’s Web site (www.cjsportmed.com).
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http://dx.doi.org/10.1097/JSM.0000000000000688
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rates of patients undergoing surgical management of PHA.
We hypothesized that the surgical treatment of proximal
hamstring injuries would lead to high rates of both return to
sport and preinjury level of sport with most athletes returning
by 6 months after surgery.
METHODS
Search and Screening Process
The PRISMA (Preferred Reporting Items for Systematic
Reviews and Meta-analyses) statement was used for the
reporting of study selection.
13
The online databases PubMed,
EMBASE, and MEDLINE were searched for literature
addressing return to sports after surgical management of
acute, chronic, partial, or complete proximal hamstring
injuries from database inception until October 7, 2017. The
search terms “Hamstring,”“Semitendinosus,”“Semimem-
branosus,”“Biceps Femoris,”“Repair,”“Reconstruction,”
and “Sport”were used (see Appendix 1,Supplemental Digital
Content 1, http://links.lww.com/JSM/A197).
Two reviewers (J.K., M.M.) independently screened the
titles, abstracts, and full-text articles resulting from the
searches. Any disagreements were resolved by consensus
discussion between reviewers and a senior author (O.R.A.)
when necessary. The references of the included studies were
then screened for additional articles that may not have been
captured by the initial search strategy. The research question
and eligibility criteria were determined a priori. The inclusion
criteria included studies written in English, human studies,
and studies investigating return to sport after surgical repair or
reconstruction of proximal hamstring injuries. Studies of all
levels were included. Cadaveric studies, animal studies,
conference papers, book chapters, review articles, and
technical reports were excluded. Two reviewers (J.K., L.N.)
collected data in duplicate and recorded them in a Microsoft
Excel spreadsheet (Version 2007; Microsoft, Redmond,
Washington). Data regarding authors, year of publication,
location of study, study design, level of evidence,
14
sample
size, age, sex, follow-up, rehabilitation protocols, and
complications were recorded.
The primary outcome was the rate at which patients
returned to sport. A meta-analysis of proportions was
conducted to determine the pooled rate of return to sport,
and return to preinjury level of sport. Subgroup analyses were
conducted where possible. To establish the variance of the raw
proportions, a Freeman–Tukey transformation was applied.
15
The transformed proportions were then combined using the
DerSimonian–Laird random-effects model (to incorporate the
anticipated heterogeneity).
16
The proportions were back-
transformed using an equation derived by Miller.
17
The
Chochran Q and I
2
tests were used to assess heterogeneity.
Values of I
2
between 25% and 49% were considered “low,”
50% to 74% “moderate,”and values greater than 75%
considered to be high statistical heterogeneity.
18
For other variables, where results were presented in
a nonuniform nature across studies, the results are presented
in narrative summary fashion. Descriptive statistics including
mean values, proportions, ranges, kappa values, and intra-
class correlation coefficient (ICC) values were calculated using
Figure 1. PRISMA flow diagram of the search
strategy for articles assessing return to sport
after surgical management of PHA.
R.P. Coughlin et al. (2018) Clin J Sport Med
2
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Minitab statistical software (Version 17; Minitab Inc, State
College, PA).
Quality Assessment of Included Studies
The Methodological Index for Non-Randomized Studies
(MINORS), which was designed to assess the methodological
quality of comparative and noncomparative, nonrandomized
surgical studies, was applied to the included studies and was
scored independently by 2 reviewers (J.K., M.M.).
19
The
MINORS checklist assigns a maximum score of 16 for
noncomparative studies and a maximum score of 24 for
comparative studies. A score of 0 to 8 or 0 to 12 was
considered poor quality for noncomparative and comparative
studies, respectively, while a score of 9 to 12 or 13 to 18 was
considered fair quality, and a score of 13 to 16 or 19 to 24 was
considered excellent quality. Any disagreements were resolved
by consensus discussion between reviewers and a senior
author (O.R.A.) when necessary.
Assessment of Agreement
Inter-reviewer agreement was assessed by the kappa (k)
statistic for the title, abstract, and full-text screening stages. An
ICC was calculated for the quality assessment using the
MINORS criteria. Agreement was categorized a priori as
follows: k/ICC of 0.61 or greater was considered substantial
agreement; k/ICC of 0.21 to 0.60, moderate agreement; and
k/ICC of 0.20 or less, slight agreement.
20
RESULTS
Study Characteristics
A total of 3545 studies were identified on initial search of the 3
databases. After systematic screening, 21 full-text articles
were ultimately included for assessment (Figure 1). Substantial
agreement was identified among the reviewers at each of the
title [k50.817; 95% confidence interval (CI), 0.779-0.855],
abstract (k50.884; 95% CI, 0.843-0.925), and full-text (k5
1.00) screening stages. Overall, 846 patients (849 injuries)
were included, with 40.4% (342 of 846) of the patients being
female. The mean age of the included patients was 41.4 years
(range, 14-71 years) (Figure 2), with a mean follow-up time of
37.8 months (range, 6-76 months) (Table 1).
Study Quality
Two of the identified studies were of prospective comparative
design (level II), 2 were retrospective comparative (level III),
Figure 2. Forest plot of the mean ages of patients in-
cluded across the studies.
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8 were prospective case series (level IV), and 9 were
retrospective case series (level IV). The median MINORS score
for the 17 noncomparative studies was 11/16. The median
MINORS score for the 4 comparative studies was 18/24. There
was substantial inter-rater agreement for the MINORS score
with an ICC of 0.811 (95% CI, 0.771-0.851) (Table 1).
Any Patient Characteristics
Seventeen studies reported the preoperative sport or sport that
precipitated the injury to the proximal hamstring in the
included athletes. The sport that precipitated the injury was
not reported in 4 studies. The most commonly reported
TABLE 1. Study Characteristics
Authors, Year
Study Design (Level of
Evidence)
MINORS
Score
No. of
Patients % Female
Follow-Up Time (Range),
mo
Mean Age (Range),
yr
Aldridge et al,
23
2012 Prospective case series (level IV) 11/16 23 56.5 37.2 (24-84) 42 (25-58)
Barnett et al,
24
2015 Prospective comparative study
(level II)
16/24 128 41.7 53.8 (SD 19.5) 42.5 (SD 12.2)
Complete & acute: 53.6
(23.1)
Complete & acute: 44.3
(12.99)
Complete & chronic: 54.9
(22.8)
Complete & chronic: 41.8
(13.3)
Partial & acute: 58.8 (12.2) Partial & acute: 39.5 (11.6)
Partial & chronic: 47.7
(19.8)
Partial & chronic: 44.5 (10.8)
Birmingham et al,
31
2011
Retrospective case series (level IV) 13/16 23 34.8 43.3 (12-108) 46 (19-65)
Blakeney et al,
41
2017
Prospective case series (level IV) 11/16 94 (96
injuries)
52.1 33 (12-58) Median: 50 (16-74)
Bowman et al,
5
2013 Retrospective case series (level IV) 12/16 17 82.4 32 (12-51) 43.3 (19-64)
Brucker et al,
25
2005 Prospective case series (level IV) 9/16 8 25% 33.3 (12-59) 40.0 (23-60)
Chahal et al,
1
2012 Retrospective case series (level IV) 11/16 13 38.4 36.9 (27-63) 44.6 (26-58)
Cohen et al,
6
2012 Retrospective case series (level IV) 12/16 52 50 33 (12-76) 47.7 (17-66)
Cross et al,
42
1998 Retrospective case series (level IV) 8/16 9 11.1 48 (6-156) 34 (21-54)
Folsom et al,
22
2008 Prospective comparative study
(level II)
19/24 25 56 20 (6-44) 44 (16-58)
Klingele et al,
10
2002 Retrospective comparative study
(level III)
18/24 11 36.4 34 (15-63) 41.5 (21-51)
Konan et al,
26
2010 Prospective case series (level IV) 8/16 10 20 NR 29.2 (24-38)
Lefevre et al,
11
2013 Prospective case series (level IV) 10/16 34 26.5 27.2 622.9 39.3 611.4
Lempainen et al,
36
2006
Retrospective case series (level IV) 11/16 47 31.9 36 (6-72) Of professional & competitive:
25
Of recreational: 45
Mansour et al,
32
2013
Retrospective case series (level IV) 8/16 10 0 NR 27.2 (23-30)
Rust et al,
35
2014 Retrospective comparative study
(level III)
19/24 72 Overall:
40.3
45 (6-117) Acute: 49.8 (25-74)
Acute: 37.3 Chronic: 40.7 (14-62)
Chronic:
47.6
Sandmann et al,
2
2016
Prospective case series (level IV) 9/16 15 40 56 (24-112) 47 (21-66)
Sarimo et al,
29
2008 Retrospective case series (level IV) 11/16 41 48.8 37 (12-72) 46 (18-71)
Skaara et al,
28
2013 Retrospective case series (level IV) 12/16 31 48.4 30 (12-66) 51 (27-73)
Subbu et al,
4
2015 Prospective case series (level IV) 11/16 112 Overall:
32.1
NR Overall: 29 (18-52)
Early: 34.6 Early: 29.7 (18-52)
Delayed:
25
Delayed: 28.6 (18-54)
Late: 30 Late: 30.7 (19-40)
Wood et al,
27
2008 Prospective case series (level IV) 11/16 71 (72
injuries)
29.6 24 (6-156) 40.2 (12.9-66.2)
NR, not reported.
R.P. Coughlin et al. (2018) Clin J Sport Med
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TABLE 2. Sports Participation and Patient Characteristics
Authors, Year
Sport and No. of
Participants
Preoperative
Sport Level
Mean Delay From Injury to
Surgery (Range), mo Acute/Chronic Tears, n
Partial-Thickness/Full-
Thickness Tear, n
Aldridge et al,
23
2012 Event ppt injury: NR 10.25 (1-192) NR Partial thickness 523
Running: 6
Splits: 5
Water skiing: 4
Other sports: 8
Barnett et al,
24
2015 Event ppt injury: NR In days: Among 96 complete (36
acute and 60 chronic)
Complete 96
Water skiing: 29 Complete and acute: 24.8
(8.6)
Among 36 partial (2 acute
and 34 chronic)
Partial 36
Splits: 24 Complete and chronic: 347.8
(709.5)
Note: acute #6wk
Sprinting: 13 Partial and acute: 31.6 (5.3)
Rugby football: 11 Partial and chronic: 509.8
(568.3)
Fall: 10
Soccer: 7
Tennis: 5
Surfing: 4
Martial arts: 3
Netball: 2
Skiing: 2
Other: 20
Birmingham et al,
31
2011 Event ppt injury: NR 4 (6 d-18 mo) 9 acute All were complete 3
tendon avulsions
Water skiing: 6 12 chronic
Slip and fall: 4 Acute #4wk
Running/sprinting: 3
Soccer: 2
Football: 2
Ice hockey: 2
In-line skating: 1
Dancing: 1
Tennis: 1
Wrestling: 1
Blakeney et al,
41
2017 NR NR NR 49 acute Injury classification:
47 chronic Type 1: 2
Acute is within 3 mo Type 2: 1
Type 3: 29
Type 4: 8
Type 5: 56
Bowman et al,
5
2013 Event ppt injury: Collegiate athletes:
2/17
NR NR Partial 17
Weightlifting: 1 Amateur athletes:
14/17
Bowling: 1 Professional body
builder: 1/17
Water skiing: 2
Sprinting: 3
Softball: 4
Aerobics: 1
Field hockey: 1
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TABLE 2. Sports Participation and Patient Characteristics (Continued)
Authors, Year
Sport and No. of
Participants
Preoperative
Sport Level
Mean Delay From Injury to
Surgery (Range), mo Acute/Chronic Tears, n
Partial-Thickness/Full-
Thickness Tear, n
Weighted lunges: 1
Tennis: 2
Martial arts: 1
Brucker et al,
25
2005 Event ppt injury: Recreational: 7/8 6/8 within 3 weeks of trauma 6/8—dx made within few
days
Complete 8/8
Taekwondo: 1 Elite athlete: 1/8 2/8 more than 2 mo after
trauma (22 and 9 wk)
2/8—dx made after 2 mo
Tennis: 2
Soccer: 2
Motorcycling: 1
Badminton: 1
Forward fall: 1
Chahal et al,
1
2012 Event ppt injury: Recreational: 10 4.49 (0.3-48) 12 acute Complete, 2 or 3 full-
thickness tears: 13/13
Water skiing: 8 Professional:1 1 chronic
Falling: 2 Acute is within 60 d
Baseball: 1
Martial arts: 1
Professional race
walking: 1
Cohen et al,
6
2012 Event ppt injury: Recreational: 23/23 NR 40 acute Complete 38/52
Water skiing: 6 12 chronic Partial 14/52
Running: 6
Downhill skiing: 4 Acute: ,4 wk from injury
Softball: 2
Baseball: 1
Football: 2
Tennis: 2
Cross et al,
42
1998 8/9 engaged in sports 8/9 recreational 36 (2-104) 9/9 chronic Complete 9/9
Folsom et al,
22
2008 Jogging 17 recreational NR 20 acute Complete 25/25
Cycling 6 high-level
recreational
athletes
5 chronic
Weight training 2 elite athletes
Elliptical Acute: within 4 wk
Cross training
Aerobics
Yoga
Rollerblading
Event ppt injury:
Water skiing: 17
Rollerblading: 2
Awkward fall: 2
Rugby: 1
Karate: 1
Softball: 1
Basketball: 1
Dirt bike accident: 1
R.P. Coughlin et al. (2018) Clin J Sport Med
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TABLE 2. Sports Participation and Patient Characteristics (Continued)
Authors, Year
Sport and No. of
Participants
Preoperative
Sport Level
Mean Delay From Injury to
Surgery (Range), mo Acute/Chronic Tears, n
Partial-Thickness/Full-
Thickness Tear, n
Klingele et al,
10
2002 9 athletes NR NR 7 acute Complete 11/11
Event ppt injury: 4 chronic
Sprinting: 3
Water skiing: 2 Acute: Within 4 wk
Fall from height: 1
Horseback riding: 1
Volleyball: 1
Martial arts: 1
Jet skiing: 1
Tennis: 1
Konan et al,
26
2010 Athlete: 3 10/10 professional
or semiprofessional
12 days (6-35) All presented within 5 wk of
injury.
Complete 10/10
Football: 2
Rugby: 3
Skiing: 2
Lefevre et al,
11
2013 NR 3/34 professional
athletes
13.6 days 66.4 34/34 acute Complete 23/34
12/34 competitive
sports
Acute: Within 4 wk Partial 11/34
17/34 recreational
2/34 not athletic
Lempainen et al,
36
2006 Sport: Professional/
competitive
13 professional
athletes
13 (0.5-108) 5/47 acute Partial 47/47
15 competitive
athletes
42/47 chronic
Soccer: 7/5 19 recreational
athletes
Sprinting: -/3 Acute: Within 4 wk
Basketball: 1/1
Ice hockey: 1/1
Aerobics: 1/-
Ballet: -/1
Figure skating: -/1
Finnish baseball: -/1
Judo: 1/-
Karate: 1/-
Middle-distance
running: -/1
Pole vault: 1/-
Powerlifting: -/1
Mansour et al,
32
2013 Football: 10/10 10/10 NFL players 0.23 (0.1-0.33) 10/10 acute Complete 10/10
Rust et al,
35
2014 Water skiing: 37/72 NR Acute: 0.59 (0.17-1.4) 51/72 acute Complete 72/72
Chronic: 14.7 (2.27-112) 21/72 chronic
Acute: Within 6 wk
Sandmann et al,
2
2016 Hiking: 4/15 3/15 competitive or
professional sports
64 (3-191) 9/15 acute Complete 15/15
Bowling: 1/15 5/15 “high-level
recreational”
6/15 chronic
Inline skating: 1/15 7/15 recreational
Jogging: 6/15 Acute: ,54wk
Swimming: 5/15
Downhill skiing: 5/15
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TABLE 2. Sports Participation and Patient Characteristics (Continued)
Authors, Year
Sport and No. of
Participants
Preoperative
Sport Level
Mean Delay From Injury to
Surgery (Range), mo Acute/Chronic Tears, n
Partial-Thickness/Full-
Thickness Tear, n
Cross-country: 3/15
Mountain biking: 3/15
Cycling: 8/15
Tennis: 5/15
Surfing: 1/15
Sailing: 1/15
Climbing: 2/15
Taekwondo: 1/15
Ice hockey: 1/15
Fitness: 3/15
Soccer: 3/15
Sarimo et al,
29
2008 29/41 involved in sports 2/41 competitive
athletes
5 (0.25-71) 14/41 acute Complete 41/41
27/41 recreational 27/41 chronic
Acute: ,54wk
Skaara et al,
28
2013 27/31 exercised
regularly
5/31 competitive NR 28 acute Complete 17/31
26/31 recreational 3 chronic Partial 14/31
Event ppt injury:
Cross-country skiing:
10/31
Acute: ,54wk
Running outdoors: 7/31
Water skiing: 2/31
Other: 12/31
Subbu et al,
4
2015 Soccer: 21 63/112 elite
athletes
Early: 22 days (5-42) 78/112 early Complete 112/112
Rugby: 40 49/112 recreational Delayed: 84 days (43-182) 24/112 delayed
Water skiing: 15 Late: 357 days (183-512) 10/112 late
Skiing: 7
Lacrosse: 3 Early: ,56wk
Martial arts: 4 Delayed: 6 wk–6 mo
Running: 3 Late: .6mo
Netball: 3
Hockey: 3
Gymnastics: 2
Equestrian: 2
Ultimate Frisbee: 2
Cricket: 2
Tennis: 1
Hurdles: 1
Dance: 1
Skydiving: 1
Horse racing: 1
R.P. Coughlin et al. (2018) Clin J Sport Med
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sporting activity leading to proximal hamstring injuries was
water skiing (n 5149), followed by rugby/football (n 575),
soccer (n 551), running/sprinting (n 548), gymnastics/splits
(n 531), downhill skiing (n 523), tennis (n 519), martial
arts (n 513), and baseball/softball (n 59). In those who had
the chronicity of the injury reported, a total of 462 (56%) of
the PHA were considered acute, whereas 360 (44%) were
chronic avulsions. The overall mean time to surgery ranged
between 13 days and 64 months. There were 639 (75%)
complete PHA reported, whereas 210 (25%) of the included
hamstring injuries were considered partial avulsions (Table 2).
Procedures, Rehabilitation Details, and
Secondary Outcomes
All studies had some rehabilitation protocol reported. Thirteen
studies described a period of non–weight-bearing or toe-touch
weight-bearing immediately postoperatively, with time of non–
weight-bearing ranging from 2 weeks (4 studies), to 6 weeks (9
studies). Bracing was reported as part of the rehabilitation
protocol in 15 studies with 12 reporting the use of a hinged knee
brace, and 3 reporting the use of a hip–knee orthosis (Table 3).
All studies used open surgical management involving mobiliza-
tion of the proximal hamstring tendon followed by anatomical
refixation to the ischial tuberosity with suture anchors (ranging
from 2 to 5 anchors per repair) in 18 studies. Two studies
described the use of Achilles tendon allograft augmentation for
reconstruction of chronic and irreparable cases
21,22
(see Appen-
dix 2,Supplemental Digital Content 2, http://links.lww.com/
JSM/A198). Evaluation of tendon healing using magnetic
resonance imaging (MRI) was performed in 2 studies,
1,11
at 6
months, and at a mean of 36 months, respectively. Both studies
identified intact proximal hamstring tendons at the ischial
tuberosity in all patients.
1,11
There were 6 total reruptures
reported, across the 7 studies where this was reported (n 5514)
with 3 complete reruptures requiring revision surgical manage-
ment and 3 partial reruptures managed nonoperatively.
Return to Sports
The time at which patients were permitted to return to sporting
activities was reported in 13 studies with the most common time
after which patients were permitted to return to sports being 6
months postoperatively. The overall mean time to return to sport
was 5.8 months (range, 1-36 months). However, no study
reportedspecificreturntosportcriteriausedtomedicallyclear
patients for sport. The rate at which athletes returned to any sport
participationwasreportedin12studies(n5355), with a pooled
rate of 87.1% (95% CI, 76.5%-95.1%, I
2
581%) (Figure 3).
Sixteen studies (n 5572) reported the rate at which athletes
returned to their preinjury level of sport, with a pooled rate of
76.7% (95% CI, 66.7%-85.3%, I
2
582.6%) (Figure 4). Six
studies (n 538) reported the rate at which competitive
(professional or collegiate) athletes returned to their competitive
level of sport, with a pooled rate of 80.5% (95% CI, 56.7%-
97.5%, I
2
536.6%). A total of 11 studies (n 5393) reported the
rate of return to preinjury level of sport after surgical management
of complete PHA, with a pooled rate of 77.6% (95% CI, 65.1%-
88.2%, I
2
581.7%). Four studies (n 5122) reported the rate of
return to sport at the preinjury level for surgical management for
partial PHA, with a pooled rate of 80.1% (95% CI,
58.1%-95.7%, I
2
584.3%). A subgroup analysis identified 6
studies (n 5129) reporting the rate of return to preinjury level of
sport after acute avulsions, with a pooled rate of 72.2% (95% CI,
56.1%-86.1%, I
2
564.3%). Four studies reported the rate at
which patients returned to their preinjury level of sports after
chronic avulsions, with a pooled rate of 75.7% (95% CI,
57.9%-90.6%, I
2
50%).
DISCUSSION
The results of this systematic review and meta-analysis
supported our hypothesis by demonstrating an overall high
pooled rate of return to sport with most athletes returning to
sport by 6 months postoperatively.
1,2,5,6,22–27
However, the
pooled rates showed a slightly lower return to preinjury level
of sport. Chahal et al
1
showed that, despite having good
functional outcomes, high satisfaction rates, and excellent
healing rates on MRI after surgical repair, 45% did not return
to their previous activity level. Although the determinants of
return to sport are multifactorial, several studies reported
kinesiophobia as a reason for reduced performance after
surgery.
6,22,28
Importantly, none of the studies used dedicated
psychosocial outcome measures, and thus lack of confidence
TABLE 2. Sports Participation and Patient Characteristics (Continued)
Authors, Year
Sport and No. of
Participants
Preoperative
Sport Level
Mean Delay From Injury to
Surgery (Range), mo Acute/Chronic Tears, n
Partial-Thickness/Full-
Thickness Tear, n
Wood et al,
27
2008 Event ppt injury: 2/71 elite athletes 12 (0.3-104) 42 acute 63 complete
Water skiing: 21 3/71 professional
athletes
40 chronic 8 partial
Dancing/ballet: 11 2/71 professional
dancers
Fall: 11 Acute: ,53mo
Soccer: 4
Rugby: 4
Skiing: 3
Surfing: 3
Martial arts: 3
Other sports: 12
dx, diagnosis; NR, not reported; ppt, precipitating.
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TABLE 3. Rehabilitation and Return to Sport Protocol
Authors, Year Rehabilitation and Return to Sport Protocol
Aldridge et al,
23
2012 Partial weight-bearing for 6 wk with avoidance of hip flexion with knee extension.
Graded return to functional activities over a 6-mo period.
Barnett et al,
24
2015 First 6 wk, partial weight-bearing and then full weight-bearing without support.
Stretching and closed-chain strengthening exercises begun at 3 mo.
Graduated return to sports is undertaken by 6 mo.
Birmingham et al,
31
2011 Immediate full weight-bearing with crutches while wearing a brace for 6 wk.
Some chronic repairs may require maintaining the knee in some flexion to minimize tension on
the repair.
Running restricted for a minimum of 12 wk.
Blakeney et al,
41
2017 Partial weight-bearing with crutches for 2-6 wk.
Bracing only used for cases with significant tension on repair (non–weight-bearing for 6 wk.)
Bowman et al,
5
2013 Hinged knee brace locked at 30 degrees of flexion for a period of 6 wk.
Toe-touch weight-bearing with crutch assistance.
Passive hip range of motion initiated at 2 wk, and active hip flexion was allowed at 4 wk.
Isotonic hamstring strengthening started at 6 wk and isokinetic strengthening was added at 8
wk.
Return to unrestricted activity allowed no earlier than 6 mo.
Brucker et al,
25
2005 Hip–knee–ankle orthosis for 6 wk (knee in 90 degrees of flexion).
No rehabilitation for 6 wk.
Return to sports activities was allowed after 6-8 mo.
Chahal et al,
1
2012 Knee brace with the knee locked in 30 degrees of flexion and non–weight-bearing for 6 wk.
Strengthening after 12 wk.
Return to sports was allowed at 6 mo.
Cohen et al,
6
2012 Hip orthosis that restricted hip flexion to a range of 30 degrees to 40 degrees and toe-touch
weight-bearing for the first 2 wk.
The brace was removed between 6 and 8 wk postoperatively.
Isotonic (6 wk) and isokinetic (8 wk) strengthening.
Return to full sports participation between 5 and 8 mo.
Cross et al,
42
1998 For 8 wk after surgery, the knee was flexed at 90 degrees in a hinged brace.
Physical therapy was not commenced until after the 8-week period.
Folsom et al,
22
2008 Hinged knee brace with the knee in 60 degrees to 90 degrees of flexion. The brace was
gradually opened to full extension during 4-6 wk based on the degree of intraoperative tension
at the repair site.
Strengthening exercises delayed until 2-3 mo after surgery.
Most patients able to resume at least a portion of their desired athletics by 6 mo.
Klingele et al,
10
2002 Patients fitted with a harness suspension device with knee in flexion for 3 to 4 wk.
Range of motion exercises and gait training initiated with the goal of attaining normal gait by 6
wk.
Return to sport and activity was allowed as early as 3 mo.
Konan et al,
26
2010 Weeks 1 and 2: the knee immobilized at 90 degrees in brace with gradual unlocking to 30
degrees by 6 wk
Weeks 7-10: a brace discontinued. Progression to full weight-bearing is permitted. Passive
and active range of movement is encouraged while avoiding extremes of motion. Closed-chain
exercises are started.
Weeks 15-16: isokinetic testing may be considered. Heavy weight training may be
undertaken, and running is permitted.
Weeks 24-38: full return to sport usually allowed in most patients.
R.P. Coughlin et al. (2018) Clin J Sport Med
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and fear of reinjury was likely under-reported. Well-designed
randomized controlled studies that are sufficiently powered
may determine the true influence of injury chronicity, patient
psychology, copathology, surgical techniques, and rehabilita-
tion on measures of postoperative success.
In a systematic review, the return to sport for nonoper-
atively treated (n 517), operatively treated partial repairs
(n 5107), and operatively treated complete repairs (n 5474)
were 70.59, 73.83, and 81.43%, respectively.
8
Functionally,
the partial repair group demonstrated significantly (P,
0.001) better scores on strength and endurance testing,
whereas the complete repair group demonstrated higher
patient satisfaction (P,0.001) and lower pain scores (P,
0.001). However, the ability to return to preinjury level of
TABLE 3. Rehabilitation and Return to Sport Protocol (Continued)
Authors, Year Rehabilitation and Return to Sport Protocol
Lefevre et al,
11
2013 Knee immobilized by a simple splint flexed at 30 degrees. Weight-bearing was partial and on
crutches.
2-6 wk, hinged knee brace allowing free knee flexion but limited extension at 30 degrees.
Isometric quadriceps and hamstring exercises, with the knee flexed at 30 degrees. Full
weight-bearing and sitting were allowed if there was no pain.
.6 wk, the knee was released. Active rehabilitation included progressive dynamic hamstring
exercises and closed kinetic chain exercises for the quadriceps.
Between wk 12-16, the patient began light jogging. Concentric then eccentric isokinetic
hamstring muscle strengthening was performed. Regular sports activities between 16 and 32
wk.
Lempainen et al,
36
2006 No immobilization, casts, or orthoses were used. The patients were allowed to begin partial
weight-bearing within 2 wk of the operation, and full weight-bearing was allowed 2-4 wk after
surgery.
Isometric muscle exercises and cycling begun after 4-6 wk.
Running 2-4 mo after the operation.
Rust et al,
35
2014 Hinged knee brace was applied either a 90 degrees or 60 degrees extension stop depending
on tension on the repair construct (90 degrees for chronic). The extension stop was gradually
brought out to full extension over 4-6 wk.
Non–weight-bearing with crutches was allowed until the period of bracing was complete (4-6
wk),
Resisted hamstring strengthening at 2.5 mo for primary repair and 3 mo for Achilles allograft
reconstruction.
Sandmann et al,
2
2016 Hip–knee–ankle orthosis allowing knee flexion at least from 90 to 130 degrees flexion for 6 wk
in an extended hip position.
After 6 wk, intensive stretching and strengthening of the hamstrings to regain full range of
motion.
Return to sports to intermittent sporting activities was allowed, but not before 6 mo after
surgery.
Sarimo et al,
29
2008 No casts or orthoses were used.
The patients used crutches for 2-3 wk during which only light-touch weight-bearing was
allowed.
4-6 wk cycling was allowed and isometric muscle exercises. Range of motion exercises were
started 5 wk after surgery.
Running and more active muscle training were allowed 2 to 4 mo from the operation.
Skaara et al,
28
2013 No brace but restriction in flexing the hip with a straight knee, avoidance of deep sitting for 2
wk postoperatively.
Crutches were advocated for 6 to 12 wk, and gradually, full weight-bearing was allowed from
4 to 6 wk.
Strengthening exercises, running, and jumping could be started after 12 wk.
Subbu et al,
4
2015 Decision to apply a brace made intraoperatively depending on amount of tension placed on the
surgical repair.
The brace was set with the knee flexed at 90 degrees for up to 6 wk.
Wood et al,
27
2008 Hinged knee brace at 90 degrees flexion for 8 wk (only for repairs of significant tension).
Partial weight-bearing on crutches for first 6 wk.
Stretching and closed-chain strengthening exercises started at 3 mo.
Graduated return to sports activity by 6 mo.
NR, not reported.
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competition was not reported. Our systematic review and
meta-analysis showed similar pooled rates of return to
preinjury level of sport for partial and complete repairs.
However, return to sport rates was as low as 58% in some
studies assessing partial repairs. Because partial avulsions
often undergo surgery after failed nonoperative treatment,
injury chronicity and tendinopathy may influence the out-
comes of this group. Unfortunately, only one of the studies
stratified mean delay from injury to surgery by rupture type
and demonstrated similar results across all groups.
24
There are conflicting results reported when comparing the
outcomes of acute and chronic repairs of PHA. Van der Made
et al
12
found no significant differences between groups in
hamstring muscle strength, unless there was a significant degree
of retraction. Bodendofer et al
8
found that acutely repaired
PHA had significantly better patient satisfaction (P,0.001),
strength testing (P50.001), and less sitting pain (P50.036),
when compared with the chronic repair group. Although our
meta-analysis showed similar pooled rates of return to sport
after acute and chronic repairs, the definition of injury
chronicity varied between studies (ranged from 4 weeks to 3
months after injury), which may have influenced the outcomes
of this group. For example, Barnett et al
24
showed only 60% of
patients returned to preinjury after a significant average delay in
repair time of 18 months. Three other studies showed that,
when chronicity was stratified into delayed and late repairs, the
latter group displayed worse outcomes, increased need for
bracing, and longer return to sport.
4,27,29
Colosimo et al have recommended both isokinetic and
functional testing before return to sport. They recommended
the injured hamstring strength to be at least 85% of the uninjured
leg at both slow and fast isokinetic velocities, and that the
quadriceps/hamstring ratio should be between 50% and 60%
for the injured leg before returning to sport.
30
Although some
studies used isokinetic testing
1,2,5,6,10,11,22,25,26,28,31,32
and
single-hop testing,
28,31
to gauge postoperative recovery, these
parameters were not used as criteria to determine readiness to
resume athletic activities. Rather, studies provided arbitrary
postoperative time points at which patients were cleared for
sport.
1,2,5,6,10,11,22–27
Criteria and determinants of return to play
similar to those used in anterior cruciate ligament reconstruction
(ACLR) are needed.
33
Athletes tend to place higher importance
on their ability to return to sport than surrogate outcome
measures of impairments such as muscle strength and range of
motion.
34
The methods to determine return to preinjury level of
sport were variable and most depended on subjective
questionnaires.
5,6,10,22–24,27,28,31,35,36
These types of self-
reported outcome measures have been used in other studies on
ACLR
37,38
and Bankart repair.
39,40
However, because of
different definitions of return to sport, data on this subject are
often confusing. Agreed upon performance metrics, such as in-
game statistics, could provide meaningful information to
clinicians as they set patient expectations.
This was a systematic review and meta-analysis on a novel
topic that addressed previous gaps in knowledge for pooled
rates of return to sport and preinjury level of sport for various
subgroups (eg, acute, chronic, partial, and complete) of PHA.
This was possible due to recent interest on this subject,
reflected by a surge of new literature. The expansive search
strategy used across multiple databases and broad inclusion
criteria ensured that all relevant articles were included.
Finally, the excellent agreement among the 2 reviewers at all
screening stages and quality assessment suggests that a thor-
ough methodology was used in the preparation of this review.
Figure 3. Forest plot of the pooled rates of return to any
sporting activities.
R.P. Coughlin et al. (2018) Clin J Sport Med
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Limitations
The studies included were observational by design with mostly
level III or IV evidence, supported by low MINORS scores. This
review is at risk for recall bias because 4 studies assessed return to
preinjury level of sport retrospectively.
6,22,24,31
The mix of injury
chronicity, tear pattern, and heterogeneity of patients (spectrum of
ages and level of competition) are confounders, which may be
more accurately assessed using subgroup analysis in high-powered
studies. Few of the studies were stratified by rehabilitation
protocol and postoperative bracing. Thus, our ability to explain
any differences in timing and rate of return to sport for these
groups was limited. One of the more concerning limitations is that
the return to “any sports”was reported only in 12 of the included
21 studies (Figure 2) and the return to sports to “preinjury level”
was reported in only 16 of the 21 included studies (Figure 3). This
reflects the variability of return to sport definitions in the literature
and stresses the need for more consistent reporting of this outcome
in future studies. There was significant heterogeneity across
studies, measured using the I
2
statistic, which gives less confidence
in the pooled results. However, the results were combined using
a random-effects model in a meta-analysis of proportions to
account for these differences.
CONCLUSIONS
Pooled results suggest a high rate of return to sport after
surgical management of PHA; however, this was associated
with a lower preinjury level of sport. No major differences in
return to sport were found between partial versus complete
and acute versus chronic PHA.
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