Surgical Management of Chronic
Incomplete Proximal Hamstring
Avulsion Injuries
Babar Kayani,*yz MRCS, MBBS, BSc (HONS), Atif Ayuob,yz MRCS, MBBS,
Fahima Begum,yz MRCS, MBBS, Natalia Khan,yz MBCHB, BSc,
and Fares S. Haddad,yz BSc, MD(Res), FRCS(Tr&Orth)
Investigation performed at Trauma and Orthopaedic Department at University College London
Hospital, London, United Kingdom, and Department of Orthopaedic Surgery, The Princess
Grace Hospital, London, United Kingdom
Background: Chronic incomplete proximal hamstring avulsion injuries are debilitating injuries associated with prolonged periods
of convalescence and poor return to preinjury level of function. This study explores the efficacy of operative intervention for these
injuries on patient satisfaction, muscle strength, range of motion, functional performance, return to preinjury level of sporting
activity, and injury recurrence.
Hypothesis: Surgical intervention of chronic incomplete proximal hamstring avulsion injuries enables return to preinjury level of
sporting function with low risk of clinical recurrence.
Study Design: Case series: Level of evidence, 4.
Methods: This prospective single-surgeon study included 41 patients with incomplete proximal hamstring avulsion injuries refractory to 6 months of nonoperative treatment. All study patients underwent primary operative repair of the avulsed proximal hamstring tendon and received standardized postoperative rehabilitation. Predefined outcomes were recorded at regular intervals
after surgery. Mean follow-up time was 28.2 months (range, 25.0-35.0 months) from date of surgery.
Results: All patients returned to their preinjury level of sporting activity. Mean 6 SD time from surgery to return to full sporting
activity was 22.2 6 6.7 weeks. There were no episodes of clinical recurrence. At 3 months after surgery, 39 patients (95.1%)
were satisfied/very satisfied with the outcomes of their surgery, and as compared with preoperative values, improvements
were recorded in isometric hamstring muscle strength at 0° (84.9% 6 10.9% vs 40.4% 6 8.8%; P \ .001), 15° (89.6% 6
7.6% vs 44.2% 6 11.1%; P \ .001), and 45° (94.1% 6 5.1% vs 66.4% 6 9.0%; P \ .001); mean passive straight leg raise angle
(71.2° 6 13.5° vs 45.4° 6 11.9°; P \ .001); mean lower extremity functional score (70.9 6 5.1 vs 48.4 6 5.2; P \ .001); and mean
Marx activity rating score (5.6 6 2.8 vs 2.7 6 1.0; P \ .001). High patient satisfaction and functional outcome scores were maintained at 1- and 2-year follow-up.
Conclusion: Operative repair of chronic incomplete proximal hamstring avulsion injuries enabled return to preoperative level of
sporting function with no episodes of clinical recurrence at short-term follow-up. Surgical intervention was associated with high
patient satisfaction and improved isometric hamstring muscle strength, range of motion, and functional outcome scores as compared with preoperative values. High patient satisfaction and improved functional outcomes were sustained at 2-year follow-up.
Keywords: hamstrings; chronic avulsion; partial avulsion; surgical repair
The hamstrings are the most commonly injured muscle
group in professional athletes and account for 12% to
26% of all injuries sustained during sporting activities.2,8,13,29 Incomplete proximal hamstring avulsion injuries most commonly occur during explosive movements
that involve combined ipsilateral hip flexion and knee
extension10,11,17 or repetitive low-force trauma that causes
localized proximal hamstring tendon attrition and surrounding tendinopathy.14,18 High-speed running requires
eccentric muscle strength as the hamstrings are lengthened across the hip and knee articulations. Previous hamstring injuries may lead to poor hamstring muscle strength
during the lengthened state and predispose to recurrent
injury.13,25,29 Additional risk factors for hamstring injuries
include reduced flexibility, muscle weakness, poor core stability, muscle fatigue, and poor lumbar posture.2,8,18,25,29
Patients may have a variety of clinical symptoms, ranging
from acute, sharp, sudden-onset gluteal pain during exertional sporting activity to more chronic, generalized
The American Journal of Sports Medicine
1–8
DOI: 10.1177/0363546520908819
Ó 2020 The Author(s)
1
2
Kayani et al
proximal hamstring discomfort with progressive limb
weakness and instability.16,18 Hamstring muscle contractures may also lead to reduced hip flexibility and decreased
straight leg raise as compared with the contralateral
limb.23,27 These injuries often occur in professional athletes and are regarded as career-threatening injuries in
most sporting activities.
Patients with incomplete proximal hamstring avulsion
injuries are often initially managed with nonoperative
treatment, including rest, nonsteroidal anti-inflammatory
drugs, protected range of movement, eccentric muscle
exercises, and ultrasound-guided injections of corticosteroids or plasma-rich protein.5,15-18,21 However, nonoperative treatment of these injuries is associated with poor
return to preinjury level of sporting function, variable
times for convalescence, and high risk of recurrence.15,16,20,21,24 Patients may develop chronic symptoms
owing to delays in presentation, referral for appropriate
imaging, and transfer to suitable treatment centers.
Chronic proximal hamstring avulsion injuries are associated with worse patient satisfaction, poorer functional outcomes, and longer time to return to sporting activity as
compared with acute proximal hamstring avulsion injuries.3 Although surgical repair of chronic proximal hamstring avulsion injuries may facilitate restoration to
preinjury level of sporting activity,3,12 the efficacy of surgical treatment for these injuries on muscle strength, range
of motion, functional outcomes, and recurrence remains
unknown.
The primary objective of this study was to assess the
effect of operative repair for chronic incomplete hamstring
avulsion injuries on return to preinjury level of sporting
function and clinical recurrence. The study hypothesis
was that surgical repair of chronic incomplete hamstring
avulsion injuries would enable return to preinjury level
of function with low risk of clinical recurrence at shortterm follow-up. Secondary objectives were to assess the
effect of surgical intervention on patient satisfaction, hamstring muscle strength, range of motion, straight leg raise,
functional performance, and complications.
METHODS
Patient Selection
This prospective study included 41 patients (31 males and 10
females) undergoing operative repair of chronic incomplete
proximal hamstring avulsion injuries. All operative procedures were performed by a single surgeon (F.S.H.) between
September 2014 and September 2016. Of the 41 study
patients, 14 were active or recently retired professional
The American Journal of Sports Medicine
TABLE 1
Baseline Characteristics for All Study Patients
Undergoing Surgical Repair of Chronic Incomplete
Proximal Hamstring Avulsion Injuriesa (N = 41)
Characteristic: Category
Age, y
Female (n = 10)
Male (n = 31)
Sex
Female
Male
Body mass index, kg/m2
ASA score
I
II
III
IV
Laterality
Right
Left
Sporting activity
Amateur
Running
Soccer
Badminton
Tennis
Professional
Soccer
Rugby
Sprinting
Time from onset of symptoms
to surgery, mo
Time from surgery to return
to sporting activity, wk
Mean 6 SD (Range) or No. (%)
38.7 6 7.2
39.4 6 8.3
38.5 6 6.9
10 (24.4)
31 (75.6)
24.7 6 3.2
41
0
0
0
(100)
(0)
(0)
(0)
24 (58.5)
17 (41.5)
19
5
1
2
(46.3)
(12.2)
(2.4)
(4.9)
5
6
3
8.2
(12.2)
(14.6)
(7.3)
6 1.8 (6-14)
22.3 6 6.9 (12-42)
a
ASA, American Society of Anesthesiologists.
athletes: 6 rugby players, 5 soccer players, and 3 sprinters.
A further 27 patients were nonprofessional athletes who
indulged in regular sporting activities, such as running, soccer, badminton, and tennis. Baseline characteristics for study
patients are presented in Table 1.
All patients had a recall of a specific event that led to
the injury but were treated nonoperatively as the first
line of treatment for a minimum 6 months. Mean 6 SD
time from injury to surgery was 8.2 6 1.8 months (range,
6-14 months). Preoperative magnetic resonance imaging
(MRI) was undertaken at the study center to confirm diagnosis, assess for any concurrent injury, and plan operative
intervention (Figure 1).
Inclusion criteria for study participation included the
following: onset of symptoms .6 months before date of surgery, MRI to confirm incomplete proximal hamstring
*Address correspondence to Babar Kayani, MRCS, MBBS, BSc (HONS), Department of Trauma and Orthopaedic Surgery, University College Hospital,
235 Euston Road, Fitzrovia, London, NW1 2BU, UK (email: babar.kayani@gmail.com).
y
Department of Trauma and Orthopaedic Surgery, University College Hospital, Fitzrovia, London, UK.
z
Department of Orthopaedic Surgery, The Princess Grace Hospital, Marylebone, London, UK.
Submitted August 24, 2019; accepted January 2, 2020.
One or more of the authors has declared the following potential conflict of interest or source of funding: F.S.H. is a paid consultant and receives royalties
from Stryker, Smith & Nephew, Corin, and Matortho. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not
conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
AJSM Vol. XX, No. X, XXXX
Figure 1. Coronal section T2-weighted magnetic resonance
imaging slice shows incomplete proximal hamstring avulsion
injury on the right side with increased signal intensity in ischial
tuberosity (bone edema) and at the tendon-bone interface,
suggesting tendinopathy (left arrow). The flailing of the tendon
at the tendon-bone interface with an intratendon inflammatory
signal suggests an incomplete tear (right arrow).
avulsion injury, patient symptomatic despite nonoperative
management, and operative intervention undertaken by
the senior author. Exclusion criteria included the following: complete proximal hamstring avulsion injury (n =
62), partial avulsion injury sustained within 6 months of
date of surgery (n = 2), recurrent injury after previous surgical intervention (n = 2), and patient living abroad or not
available for follow-up (n = 5). Presenting complaint was
gluteal pain (n = 31), muscle weakness (n = 5), reduced
range of motion (n = 2), and paresthesia in the distribution
of the sciatic nerve (n = 3). The study was prospectively
reviewed by the hospital review board, which advised
that further research ethics committee approval was not
required. Informed consent for participation was obtained
from all study patients.
Surgical Technique
All operative procedures were performed with the patient
in the prone position under general anesthesia. The
affected hip was flexed and the gluteal skin crease marked.
In patients without neurological symptoms (n = 38),
a transverse incision measuring 8 to 10 cm was performed
through this skin crease. In patients with sciatic nerve
impingement symptoms (n = 3), a longitudinal incision
measuring 7 to 8 cm was performed distal to the skin
crease instead of the transverse incision. The underlying
subcutaneous tissue and gluteal fascia were divided by
electrocautery, exposing the inferior border of the gluteus
maximus muscle. The posterior cutaneous nerve of the
thigh was identified and protected. The gluteus maximus
was then retracted superiorly to expose the underlying fascia over the hamstrings. Caution was taken not to place
Chronic Incomplete Proximal Hamstring Avulsion Injuries
3
the retractor too deep on the ischium to minimize risk of
inferior gluteal nerve injury.
A longitudinal incision was performed through the hamstring fascia, and the hamstrings tendons were traced
proximally to the ischial tuberosity. The hamstring tendons were identified and the sciatic nerve palpated to confirm its position deep and lateral relative to the hamstring
complex and ischial tuberosity. The hamstring tendons
were explored and the bare area from the avulsed ischial
tuberosity identified. Blunt finger dissection and electrocautery were used to carefully dissect any scar tissue,
and the fibrotic end of the retracted proximal tendon was
excised. The sciatic nerve was palpated to ensure that it
was tension-free. Six patients had adhesions to the adjacent sciatic nerve that were dissected with blunt finger dissection and electrocautery. Two TWINFIX 5.0-mm suture
anchors (Smith & Nephew Limited) were inserted into
the ischial tuberosity under direct vision. Each suture
anchor had 2 nonabsorbable ultrahigh molecular weight
polyethylene fiber sutures, which were stitched into the
free end of the partially avulsed tendons with a modified
Kessler technique. The knee was flexed to 30°, and the
avulsed tendon was parachuted down to the tendon bed
under direct vision. The knee was then fully extended to
ensure satisfactory tension in the repair throughout the
arc of motion. The wound was copiously irrigated with normal saline. The overlying fascia, subcutaneous tissue, and
skin were closed in layers with absorbable sutures and
a pressure dressing applied to the wound. All patients
wore a hinged knee brace.
Postoperative Rehabilitation
All patients received a standardized milestone-based rehabilitation program, which was supervised by an experienced sports physiotherapist. The rehabilitation program
was divided into 4 distinct phases:
Phase 1: RICE (rest, ice, compression, and elevation), aspirin (75 mg once daily), limit excessive combined hip flexion and knee extension, knee range of motion restricted
from 60° to 120°.
Phase 2: Regain full pain-free hip and knee range of
motion, full weightbearing, concentric and eccentric
training, core strengthening.
Phase 3: Muscle strengthening with resistance exercises,
double- and single-leg squats, quadriceps extension,
and hamstring curls. Aerobic conditioning with light
jogging, cycling, and swimming. Sport-specific training.
Phase 4: Return to full sporting activity with full pain-free
range of motion, muscle strength 90% of uninjured limb,
and no concerns with sport-specific training.
Outcome Measures
All study patients were clinically reviewed by the operating surgeon at regular intervals until return to play. Study
outcomes were recorded by a specialist nurse practitioner
preoperatively and at predefined intervals after surgery.
4
Kayani et al
All outcomes at 3 months and 1 year after surgery were collected during clinical consultation, and outcomes at 2-year
follow-up were collated by telephone conversation, given
the wide geographic location of study patients.
Patient Satisfaction. Patient satisfaction was recorded
at 3 months, 1 year, and 2 years after surgery via the Musculoskeletal Outcomes Data Evaluation and Management
System, which scores patient satisfaction on a scale of 1
to 5 (1, very unsatisfied; 2, unsatisfied; 3, neutral; 4, satisfied; 5, very satisfied).13
Hamstring Strength. Isometric hamstring strength was
tested pre- and postoperatively at 3 months and 1 year.
The patient was placed in the prone position and a handheld dynamometer (Hoggan Scientific LLC) positioned
over the ipsilateral calcaneus. Maximum resisted knee
flexion force (newtons) was recorded at 0°, 15°, 45°, and
90°. This technique was repeated 3 times and the mean
flexion force at each angle in the injured limb calculated.
All values were compared with those of the contralateral
uninjured limb to calculate the percentage of normal hamstring muscle strength.
Passive Straight Leg Raise. Maximum angle of passive
straight leg raise (PSLR) was tested pre- and postoperatively at 3 months and 1 year. With the patient in the
supine position, the uninjured limb was passively elevated, inducing flexion at the hip while maintaining
extension at the knee joint to the point of failure secondary to pain or elastic limit of the limb. The maximum
attainable PSLR (degrees) was measured with a standard
goniometer and compared with the maximum PSLR in the
contralateral injured limb. The deficit in PSLR between
the limbs was recorded.
Functional Progress and Return to Function. All study
patients completed the Lower Extremity Functional
Scale (LEFS) and Marx Activity Rating Scale (MARS)
preoperatively and at 3 months, 1 year, and 2 years after
surgery.4,19 The LEFS is a validated and effective questionnaire for assessing specific lower limb function. It is
an 80-point scale with 20 questions (4 points per question)
and a minimum clinical difference of 9 points.4 The MARS
measures patient activity level and knee function independent of age, sex, and type of sporting activity. Scores of 0 to
4 are assigned to 4 activities—running, changing direction,
decelerating, and pivoting—with a total score of 16.19 Time
from surgical intervention to full return to sporting activity was collected in all study patients.
Complications. All complications within 2 years of the
primary surgery were recorded.
All patients recruited into this study completed followup. Mean follow-up time was 28.2 months (range, 25.035.0 months) from date of surgery.
The American Journal of Sports Medicine
TABLE 2
Patient Satisfaction Scores at Predefined Study
Intervals After Surgical Repair of Chronic Incomplete
Hamstring Avulsion Injuries
Patients, No. (%)
Very unsatisfied: 1
Unsatisfied: 2
Neutral: 3
Satisfied: 4
Very satisfied: 5
3 mo
1y
2y
1 (2.4)
1 (2.4)
0
19 (46.3)
20 (48.8)
0
0
1 (2.4)
7 (17.1)
33 (80.5)
0
0
0
3 (7.3)
38 (92.7)
for all analyses, and all statistical analysis was performed
with SPSS software (v 24; IBM Corp).
RESULTS
Return to Function and Clinical Recurrence
All study patients returned to their preinjury level of sporting activity. Mean time from surgical intervention to
return to sporting activity was 22.3 6 6.9 weeks. The overall range for time from surgical intervention to return to
sporting activity was 12 to 42 weeks. At 1- and 2-year
follow-up, all study patients were still participating at
their preinjury level of sporting activity. No study patients
had clinical recurrence of their primary injury.
Patient Satisfaction
Operative repair of chronic incomplete proximal hamstring
avulsion injuries was associated with high levels of patient
satisfaction. At 3 months after surgery, 39 patients (95.1%)
were satisfied/very satisfied with the outcomes of their surgery, and 2 patients were unsatisfied (Table 2). Of the 2
unsatisfied patients, 1 was disappointed with the speed
of postoperative recovery. He was a professional soccer
player who returned to preinjury level of sporting activity
at 34 weeks after surgery. The second patient was a professional rugby player who developed postoperative complex
regional pain syndrome around the operated limb. He
was successfully treated with analgesia and physiotherapy
and made a return to full sporting activity at 42 weeks. At
2 years after surgery, 38 patients (92.7%) were very satisfied and 3 (7.3%) were satisfied with the outcomes of their
surgery.
Statistical Analysis
Hamstring Strength
Paired t tests were used to compare study outcomes found
to be normally distributed, while the Mann-Whitney U test
was used for continuous outcomes found not to be normally
distributed. Categorical outcomes were compared with the
Fisher exact test. Statistical significance was set at P \ .05
Surgical intervention was associated with improved hamstring muscle strength at 3 months after surgery as compared with presurgery (Table 3, Figure 2). At 1-year
follow-up, all patients had restored hamstring muscle
strength to .90% of the contralateral side.
AJSM Vol. XX, No. X, XXXX
Chronic Incomplete Proximal Hamstring Avulsion Injuries
5
TABLE 3
Hamstring Muscle Strength vs Contralateral Limb in Patients Undergoing Surgical Repair
of Chronic Incomplete Proximal Hamstring Avulsion Injuriesa (N = 41)
Strength, %, Mean 6 SD
Angle
Preoperative
0°
15°
45°
90°
40.4
44.2
66.4
86.2
6
6
6
6
8.8
11.1
9.0
6.2
3 mo
84.9
89.6
94.1
97.1
Preoperative
0°
15°
45°
90°
40.4
44.2
66.4
86.2
6
6
6
6
8.8
11.1
9.0
6.2
84.9
89.6
94.1
97.1
6
6
6
6
10.9
7.6
5.1
3.5
P Value
10.9
7.6
5.1
3.5
44.5
45.3
27.7
10.9
6
6
6
6
9.8 (41.5 to 47.6)
11.9 (41.6 to 49.1)
8.1 (25.1 to 30.2)
6.1 (9.0 to 12.8)
\.001
\.001
\.001
\.001
5.5
4.6
3.4
3.8
53.1
53.3
32.2
11.9
6
6
6
6
6.3
9.1
7.4
5.3
(50.2 to 56.8)
(50.4 to 56.7)
(29.8 to 34.8)
(9.0 to 14.8)
\.001
\.001
\.001
\.001
5.5
4.6
3.4
3.8
8.3
8.0
4.6
1.0
6
6
6
6
11.2 (4.8 to 11.8)
8.1 (5.4 to 10.5)
5.7 (2.8 to 6.3)
4.4 (–0.4 to 2.3)
\.001
\.001
\.001
.18
1y
93.2
97.5
98.6
98.1
3 mo
0°
15°
45°
90°
6
6
6
6
Improvement, %, MD (95% CI)
6
6
6
6
1y
93.2
97.5
98.6
98.1
6
6
6
6
a
MD, mean difference.
with chronic back pain. In both patients, PSLR improved
to 80° at 1-year follow-up after surgery.
Functional Progress and Return to Function
Figure 2. Boxplots show hamstring muscle strength (vs the
contralateral limb) in study patients undergoing surgical repair
of chronic incomplete proximal hamstring avulsion injuries.
Values are presented as mean (3), median (line), interquartile
range (box), range (error bars), and outliers more than 1.5
times the interquartile range width from the lower or upper
quartiles (circles).
Passive Straight Leg Raise
Operative repair of chronic incomplete proximal hamstring
avulsion injuries was associated with improved PSLR and
decreased PSLR deficit at 3-month follow-up as compared
with preoperative values (Table 4, Figure 3). Further
improvements in PSLR were observed at 1 year after surgery as compared with 3 months. Two patients had maximum PSLR \50° at 3-month follow-up, which included 1
patient with chronic regional pain syndrome and 1 patient
At 3 months after surgery, mean LEFS score markedly
improved as compared with the preoperative value. At 3month follow-up, 12 patients (29.2%) had an LEFS score
of 80 (out of 80), and 24 (58.5%) had a score .75. Further
incremental improvements in LEFS scores were observed
at 1 and 2 years after surgery (Table 5, Figure 4). At 2year follow-up, 16 patients (39.0%) had an LEFS score of
80, and 21 (51.2%) had a score .75. MARS scores followed
a similar tend with statistically improved scores at each
follow-up interval after surgery. At 2-year follow-up, 35
patients (85.3%) had a minimum MARS score of 12 (out
of 16), which included 9 (22.0%) with a score of 16.
Complications
There were no intraoperative complications. In addition to
the 1 patient who developed chronic regional pain syndrome described earlier, 4 patients had extensive bruising
distal to the operative site, all of which was managed nonoperatively. One patient developed a superficial wound
infection that was successfully treated with a 1-week
course of oral antibiotics. No other complications occurred
within 2 years of surgery.
DISCUSSION
This study found that surgical repair of chronic incomplete
proximal hamstring avulsion injuries enabled return to preoperative level of sporting function with no episodes of clinical
6
Kayani et al
The American Journal of Sports Medicine
TABLE 4
PSLR in Study Patients Undergoing Surgical Repair of Chronic Incomplete Proximal
Hamstring Avulsion Injuriesa (N = 41)
PSLR, Mean 6 SD
Outcome
Preoperative
3 mo
Improvement in PSLR, MD (95% CI)
P Value
PSLR, deg
PSLR deficit, degb
45.4 6 11.9
38.5 6 9.6
71.2 6 13.5
12.7 6 10.5
25.9 6 10.0 (22.7 to 29.0)
–25.9 6 10.0 (222.7 to 229.0)
\.001
\.001
Preoperative
1y
45.4 6 11.9
38.5 6 9.6
77.8 6 7.9
6.1 6 6.7
32.2 6 9.8 (29.7 to 34.7)
–32.2 6 9.8 (229.7 to 234.7)
\.001
\.001
3 mo
1y
71.2 6 13.5
12.7 6 10.5
77.8 6 7.9
6.1 6 6.7
6.6 6 11.3 (3.1 to 10.1)
–6.6 6 11.3 (23.1 to 210.1)
\.001
\.001
PSLR, deg
PSLR deficit, degb
PSLR, deg
PSLR deficit, degb
a
MD, mean difference; PSLR, passive straight leg raise.
Compared with contralateral limb.
b
Figure 3. Boxplots show passive straight leg raise (PSLR)
angle (degrees) in study patients undergoing surgical repair
of chronic incomplete proximal hamstring avulsion injuries.
The normal passive straight leg raise (on the contralateral
uninjured side) is shown in the left-hand box plot. Values
are presented as mean (3), interquartile range (box), range
(error bars), and outliers more than 1.5 times the interquartile
range width from the lower or upper quartiles (circles).
recurrence at short-term follow-up. Operative intervention
was associated with high patient satisfaction and improved
isometric hamstring muscle strength, range of motion, and
functional outcome scores as compared with preoperative values. High patient satisfaction and improved functional outcomes were sustained at 2 years after surgery.
All study patients were able to return to preinjury level
of sporting function at a mean 22.3 6 6.9 weeks after surgery. These findings are consistent with those of Lempainen et al,16 who performed operative repair of 47 partial
proximal hamstring avulsion injuries with bone suture
anchors and found that 41 patients (87.2%) were able to
return to sporting activity at a mean 5 months after surgery. The authors reported that 41 patients (87.2%)
reported their outcomes as good or excellent, which is consistent with the findings of the current study at 1-year
follow-up. Similarly, Wood et al28 described the outcomes
of operative intervention in 71 proximal hamstring injuries, which included 7 proximal partial avulsion injuries
treated with bone anchors. All patients made a full return
to sporting activity with high patient satisfaction at 6month follow-up. Barnett et al3 performed operative repair
on 34 patients with chronic partial hamstring avulsion
injuries and found that only 60% of patients were able to
return to their preinjury level of function and 26% labeled
their surgical outcomes as moderate. The mean time from
initial injury to operative intervention was 510 days (2.5
times the mean time from injury to surgical intervention
in our study), and patients did not have standardized postoperative rehabilitation, which may have contributed to
the less favorable outcomes as compared with those
observed in the current study.
Delays in operative treatment may lead to muscle weakness and fibrosis of scar tissue to the sciatic nerve and then
to neurological complications, such as foot drop or paresthesia of the lower limb.9,18,22,24 In the current study, 3
patients had paresthesia in the distribution of the sciatic
nerve, which resolved after operative intervention. In
these patients, the proximal avulsed portion of the
retracted hamstring was scarred and adhered to the adjacent sciatic nerve. The scar tissue was dissected and the
sciatic nerve freed to minimize any tension. Bowman
et al6 reported outcomes in 17 patients undergoing surgical
repair of partial proximal hamstring injuries refractory to
6 months of nonoperative treatment and found that 5 of
these patients developed postoperative paresthesia. Sarimo et al24 reviewed the outcomes of surgical treatment
in 41 patients with acute or chronic complete proximal
hamstring avulsion injuries and found that chronic cases
were associated with the torn muscle having a macroscopically abnormal appearance with a hardened fibrotic texture. The authors reported that time from injury to
operative intervention was 2.4 months in patients reporting good and excellent results but 11.7 months in patients
with poor or moderate outcomes (P \ .001).
Operative repair of chronic proximal incomplete hamstring avulsion injuries enabled improvements in isometric
AJSM Vol. XX, No. X, XXXX
Chronic Incomplete Proximal Hamstring Avulsion Injuries
7
TABLE 5
LEFS and MARS in Study Patients Undergoing
Surgical Repair of Chronic Incomplete Proximal
Hamstring Avulsion Injuries (N = 41)a
Outcome: Time
LEFS
Preoperative
3 mo
1y
2y
MARS
Preoperative
3 mo
1y
2y
Mean 6 SD
Improvement in
Scores, MD (95% CI)
P Value
48.4
70.9
75.2
77.0
6
6
6
6
5.2
5.1
2.7
3.0
22.4 6 6.5 (20.4-24.4)
4.3 6 3.8 (3.1-5.5)
1.9 6 3.0 (0.9-2.8)
\.001
\.001
\.001
2.7
5.6
9.4
12.4
6
6
6
6
1.0
2.8
1.5
2.4
3.1 6 2.1 (2.2-4.0)
3.8 6 3.3 (2.8-4.9)
3.0 6 2.5 (2.2-3.8)
\.001
\.001
\.001
a
LEFS, lower extremity function scale; MARS, Marx Activity
Rating Scale; MD, mean difference.
hamstring muscle strength through the arc of flexion.
Maximum hamstring strength deficit was seen in the
range of 0° to 45° of flexion with the least strength deficit
at 90° of flexion. These findings are consistent with those
of Young et al,30 who assessed hamstring muscle strength
in 41 of 47 patients using a subjective measure of clinical
weakness of hamstrings. The authors found that proximal
hamstring insults resulted in maximum hamstring strength
deficit in the first 45° of knee flexion. Improvements in isometric muscle hamstring strength observed in our study are
consistent with those reported by Barnett et al.3 In their
study, surgical repair of partial hamstring avulsion injuries
resulted in improvements in hamstring muscle strength
from 53.6% preoperatively to 84.1% postoperatively as compared with the contralateral side. Aldridge et al1 reported
outcomes in 23 consecutive patients with chronic partial
hamstring avulsion injuries who were undergoing surgical
repair via reattachment with bone anchors. The authors
found that mean isometric strength improved from 64% to
88% of the contralateral side at 6-month follow-up.
Operative intervention for chronic incomplete proximal
hamstring avulsion injuries in our study was associated
with improvements in functional outcomes. Although preinjury scores were not available for comparison, 12
patients (29.2%) from this study had an LEFS score of 80
(out of 80), and 24 patients (58.5%) had a score .75 at 3
months after surgery. Statistically significant incremental
improvements in LEFS and MARS scores were observed
over 2 years after surgery, which suggests progressive
improvements in confidence with sporting activity and
daily functional activities over this period. In this study,
observed improvements in objective functional outcome
scores after surgical repair are consistent with existing literature on surgical repair of acute and chronic hamstring
injuries.7,25,26 Sonnery-Cottet et al26 found that surgical
repair of proximal or distal hamstring injuries in 10 professional athletes was associated with return to preinjury
level of sporting activity at 3.4 months (range, 2-5 months).
Cohen et al7 followed 52 patients undergoing suture
anchor repair of proximal hamstring avulsion injuries
Figure 4. Boxplots show Lower Extremity Functional Scale
(LEFS) score in study patients undergoing surgical repair of
chronic incomplete proximal hamstring avulsion injuries. Values are presented as mean (3), median (line), interquartile
range (box), range (error bars), and outliers more than 1.5
times the interquartile range width from the lower or upper
quartiles (circles).
and found a mean LEFS score of 75 (range, 50-80) at a
follow-up of 33 months (range, 12-76 months).
The main clinical significance of this study is that it provides important prognostic information on muscle
strength, range of motion, functional progress, and time
to return to preinjury level of function after operative
repair of chronic incomplete proximal hamstring avulsion
injuries. The findings will facilitate postoperative rehabilitation and planning for return to sporting activity. This
study supports existing literature showing that chronic
proximal hamstring avulsion injuries may lead to fibrosis
of the avulsed tendon and tethering to the adjacent sciatic
nerve. These fibrotic adhesions may require intraoperative
division to release the sciatic nerve and improve any distal
neurological compromise. Operative intervention also
enabled all study patients to return to preinjury level of
sporting function. Although it remains unclear how the
time to return to sporting function compares with a standardized nonoperative rehabilitation program, there was no clinical recurrence of the primary symptoms at short-term
follow-up. This information should be included in any discussion between medical professionals and patients when deciding between nonoperative and operative intervention.
There are several limitations of this study that need to
be considered when interpreting the findings. There was
no control group of patients undergoing nonoperative management; therefore, it is difficult to ascertain the effect of
8
Kayani et al
surgical repair as compared with nonoperative treatment
with the standardized rehabilitation program. Patient recruitment with prospective randomization to operative treatment
or further nonoperative treatment is challenging in highly
active patients who have already failed a minimum 6 months
of nonoperative management. Furthermore, although all
patients received a minimum 6 months of nonoperative treatment, the overall time from injury to surgical intervention
was not correlated with study outcomes. Stratification of
patients based on duration of nonoperative management
may help to provide more detailed information about optimal
time for surgical repair and prognostic outcomes. Repeat
imaging with MRI was not used to assess healing at the operative site; therefore, asymptomatic recurrent injuries may not
have been detected. Finally, study outcomes were not correlated with preoperative clinical findings or radiological grade
of injury, and follow-up was limited to 2 years after surgery.
CONCLUSION
Operative repair of chronic incomplete proximal hamstring
avulsion injuries enabled return to preoperative level of
sporting function with no episodes of clinical recurrence
at short-term follow-up. Surgical intervention was associated with high patient satisfaction and improved isometric
hamstring muscle strength, range of motion, and functional outcome scores as compared with preoperative values. High patient satisfaction and improved functional
outcomes were maintained at 2 years after surgery.
REFERENCES
1. Aldridge SE, Heilpern GN, Carmichael JR, Sprowson AP, Wood DG.
Incomplete avulsion of the proximal insertion of the hamstring: outcome two years following surgical repair. J Bone Joint Surg Br.
2012;94(5):660-662.
2. Arnason A, Gudmundsson A, Dahl HA, Johannsson E. Soccer injuries
in Iceland. Scand J Med Sci Sports. 1996;6:40-45.
3. Barnett AJ, Negus JJ, Barton T, Wood DG. Reattachment of the proximal hamstring origin: outcome in patients with partial and complete
tears. Knee Surg Sports Traumatol Arthrosc. 2015;23(7):2130-2135.
4. Binkley JM, Stratford PW, Lott SA, Riddle DL; North American Orthopaedic Rehabilitation Research Network. The Lower Extremity Functional Scale (LEFS): scale development, measurement properties,
and clinical application. Phys Ther. 1999;79(4):371-383.
5. Bodendorfer BM, Curley AJ, Kotler JA, et al. Outcomes after operative and nonoperative treatment of proximal hamstring avulsions—a
systematic review and meta-analysis. Am J Sports Med. 2018;
46(11):2798-2808.
6. Bowman KF Jr, Cohen SB, Bradley JP. Operative management of
partial-thickness tears of the proximal hamstring muscles in athletes.
Am J Sports Med. 2013;41(6):1363-1371.
7. Cohen SB, Rangavajjula A, Vyas D, Bradley JP. Functional results
and outcomes after repair of proximal hamstring avulsions. Am J
Sports Med. 2012;40(9):2092-2098.
8. Croisier JL. Factors associated with recurrent hamstring injuries.
Sports Med. 2004;34(10):681-695.
The American Journal of Sports Medicine
9. Dierckman BD, Guanche CA. Endoscopic proximal hamstring repair
and ischial bursectomy. Arthrosc Tech. 2012;1(2):e201-e207.
10. Drezner J, Ulager J, Sennett B. Hamstring muscle injuries in track
and field athletes: a 3-year study at the Penn Relay Carnival. Scand
J Med Sci Sports. 2014;24(4):e254-e259.
11. Feucht MJ, Plath JE, Seppel G, Hinterwimmer S, Imhoff AB, Brucker
PU. Gross anatomical and dimensional characteristics of the proximal hamstring origin. Knee Surg Sports Traumatol Arthrosc. 2015;
23(9):2576-2582.
12. Folsom GJ, Larson CM. Surgical treatment of acute versus chronic
complete proximal hamstring ruptures: results of a new allograft
technique for chronic reconstructions. Am J Sports Med. 2008;
36(1):104-109.
13. Graham B, Green A, James M, Katz J, Swiontkowski M. Measuring
patient satisfaction in orthopaedic surgery. J Bone Joint Surg Am.
2015;97(1):80-84.
14. Hawkins RD, Hulse MA, Wilkinson C, Hodson A, Gibson M. The
association football medical research programme: an audit of injuries
in professional football. Br J Sports Med. 2001;35:43-47.
15. Koulouris G, Connell D. Evaluation of the hamstring muscle complex
following acute injury. Skeletal Radiol. 2003;32(10):582-589.
16. Lempainen L, Sarimo J, Heikkila J, Mattila K, Orava S. Surgical treatment of partial tears of the proximal origin of the hamstring muscles.
Br J Sports Med. 2006;40(8):688-691.
17. Lempainen L, Sarimo J, Mattila K, et al. Proximal hamstring tendinopathy: results of surgical management and histopathological findings.
Am J Sports Med. 2009;37(4):727-734.
18. Lempainen L, Sarimo J, Mattila K, Orava S. Proximal hamstring tendinopathy: overview of the problem with emphasis on the surgical
treatment. Oper Tech Sports Med. 2009;17:225-228
19. Marx RG, Stump TJ, Jones EC, Wickiewicz TL, Warren RF. Development and evaluation of an activity rating scale for disorders of the
knee. Am J Sports Med. 2001;29(2):213-218.
20. Matsuda DK. Proximal hamstring syndrome: another pain in the buttock. Arthroscopy. 2018;34(1):122-125.
21. Miller SL, Gill J, Webb GR. The proximal origin of the hamstrings and
surrounding anatomy encountered during repair: a cadaveric study. J
Bone Joint Surg Am. 2007;89(1):44-48.
22. Puranen J, Orava S. The hamstring syndrome: a new diagnosis of
gluteal sciatic pain. Am J Sports Med. 1988;16(5):517-521.
23. Sallay PI, Friedman RL, Coogan PG, Garrett WE. Hamstring muscle
injuries among water skiers: functional outcome and prevention.
Am J Sports Med. 1996;24(2):130-136.
24. Sarimo J, Lempainen L, Mattila K, Orava S. Complete proximal hamstring avulsions: a series of 41 patients with operative treatment. Am
J Sports Med. 2008;36(6):1110-1115.
25. Schmitt B, Tim T, McHugh M. Hamstring injury rehabilitation and prevention of reinjury using lengthened state eccentric training: a new
concept. Int J Sports Phys Ther. 2012;7(3):333-341.
26. Sonnery-Cottet B, Daggett M, Gardon R, Pupim B, Clechet J, Thaunat M. Surgical management of recurrent musculotendinous hamstring injury in professional athletes. Orthop J Sports Med.
2015;3(10):2325967115606393.
27. Storey RN, Meikle GR, Stringer MD, Woodley SJ. Proximal hamstring
morphology and morphometry in men: an anatomic and MRI investigation. Scand J Med Sci Sports. 2016;26(12):1480-1489.
28. Wood DG, Packham I, Trikha SP, Linklater J. Avulsion of the proximal
hamstring origin. J Bone Joint Surg Am. 2008;90(11):2365-2374.
29. Woods C, Hawkins RD, Maltby S, Hulse M, Thomas A, Hodson A.
The football association medical research programme: an audit of
injuries in professional football—analysis of hamstring injuries. Br J
Sports Med. 2004;38(1):36-41.
30. Young IJ, van Riet RP, Bell SN. Surgical release for proximal hamstring syndrome. Am J Sports Med. 2008;36(12):2372-2378.
For reprints and permission queries, please visit SAGE’s Web site at http://www.sagepub.com/journalsPermissions.nav.