Knee Surg Sports Traumatol Arthrosc
DOI 10.1007/s00167-014-3465-8

ELBOW

Single injection of platelet‑rich plasma (PRP) for the treatmentof refractory distal biceps tendonitis: long‑term results of aprospective multicenter cohort study
Ilknur Sanli · Barnes Morgan · Fiek van Tilborg ·Lennard Funk · Taco Gosens

Received: 3 February 2014 / Accepted: 10 November 2014
© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2014

Abstract
Purpose There is a lack of evidence regarding the use of
PRP in the treatment of distal biceps tendonitis. The purpose of this study was to assess the effectiveness of ultrasound (US)-guided injection of PRP in relieving pain andfunctional impairment in the treatment of refractory distal
biceps tendonitis.
Methods Twelve patients from two large tertiary referral hospitals were recruited over a period of 20 months.
Clinical diagnosis of distal biceps tendonitis was confirmed
using magnetic resonance imaging. All patients had a single US-guided injection of PRP carried out by the two senior authors. Patients were objectively assessed for clinicaland functional improvement using visual analogue (VAS)
rest and activity pain scores, subjective satisfaction scale,elbow functional assessment (EFA) and isometric muscular(biceps) strength. Symptom severity and subsequent functional outcome were measured pre-injection and at final
follow-up.

This study was conducted according to current GCP and ISO
14155 guidelines.
I. Sanli · T. Gosens (*)
Department of Orthopaedic Surgery and Traumatology, St.
Elisabeth Hospital Tilburg, Hilvarenbeekseweg 60,
P.O. Box 90151, 5000 LC Tilburg, The Netherlands
e-mail: t.gosens@elisabeth.nl
B. Morgan · L. Funk
Department of Orthopaedic Surgery and Traumatology,
Wrightington Hospital, Wigan, UK
F. van Tilborg
Department of Radiology, St. Elisabeth Hospital Tilburg,
Hilvarenbeekseweg 60, P.O. Box 90151, 5000 LC Tilburg,
The Netherlands

Results At a median follow-up of 47 months (36–52 months), all patients showed significant improvementin pain (p < 0.002) and functional outcome (p < 0.004).
Median resting VAS score improved from 6 (3–8) to 0.5(0–2) and the activity VAS score improved from 8 (6–9)
to 2.5 (0–4). EFA improved from 63 to 90. In the English
cases, isometric muscular strength also showed significant
improvement. All patients were satisfied with the clinicaland functional outcomes at final follow-up.
Conclusion US-guided PRP injection seems to be aneffective treatment modality for symptomatic refractory
distal biceps tendonitis.
Level of evidence III.
Keywords PRP · Distal biceps tendonitis · VAS ·Functional outcome · Isometric muscular (biceps) strength

Introduction
Acute and chronic musculoskeletal injuries in sports arecommon and problematic for both athletes and clinicians.
These injuries are often difficult to treat, and many patients
suffer from decreased performance with persistent painand discomfort [3, 21, 24]. Although injuries of the distal
biceps tendon are rare, this clinical entity is increasingly
reported in the medical literature. Injuries are the result ofrepetitive intrinsic or extrinsic overload, resulting in microrupture of the tendon. Distal biceps tendonitis can be considered part of the continuum of the same disease process,the spectrum which includes partial tearing of the distal
biceps tendon [12].
To date, conservative treatment options are offered withthe assumption that it is a self-limiting condition, like othertendinosis. In our experience distal biceps tendonitis is13

Knee Surg Sports Traumatol Arthrosc

difficult to manage with conservative treatment proving frequently non-responsive to rest, activity modification, bracing, physical exercise programmes. Despite the fact thatanti-inflammatory agents are frequently used in the treatment of distal biceps tendonitis, the available human histology studies suggest no significant inflammatory role at
4 months. Several animal models indicate that an inflammatory reaction is present in acute situations (first 2 weeks)
but a degenerative process soon supersedes [2, 7, 16, 17,
26, 27]. Second-line treatments such as corticosteroid
injections give possible concerns relating to tendon integrity post-injection. In (chronic) tendon lesions, there is lackof good evidence to advocate the use of local corticosteroid
injections [8, 13, 23]. Surgical treatment is used arbitrarily in few small retrospective cases. Complete detachmentof the distal biceps tendon with debridement and re-attachment of the tendon have been successful in alleviating pain.
However, with the results of these studies, it is impossible
to distinguish between pathologic tendons that will resolvewith time or respond to non-surgical treatment and thosethat require surgical treatment.
Platelet-rich plasma (PRP) is increasingly used in adiverse range of tendinosis [10, 15, 20, 22]. PRP is a bioactive component of whole blood. Upon platelet activation, different bioactive factors are released, which may
influence tissue healing through processes including proliferation and differentiation, cellular chemotaxis, angiogenesis, eradication of tissue debris and the laying downof extracellular matrix [1]. According to Mos et al. [6], invivo application of PRP in tendon injuries promotes angiogenesis and generation of fibrovascular callus and might
promote the catabolic demarcation of traumatized tendon
matrices. The possible beneficial effect for tendinosis,
which are degenerative in nature, remains unanswered.
To date, there is lack of evidence to recommend the use of
PRP in a diverse range of tendinosis, because trials remain
scarce with methodological problems and inconsistent
results.
This study evaluated the clinical and functional outcome
for US-guided single-shot PRP injection in patients withrefractory distal biceps tendonitis from two large tertiaryreferral hospitals. A prospective study design was used toprovide evidence for PRP in the treatment of this rare clinical entity on the long-term.

Materials and methods
A prospective multicenter cohort study of US-guided PRP
injection was performed for all patients diagnosed withrefractory distal biceps tendonitis. Patients were included
in a time-period of 20 months. Eligible for the study were
all patients >18-year old with pain unresponsive to one of

13three conventional therapy programmes (physical exercise therapy, non-steroidal anti-inflammatory medications
and local steroid injections). The exclusion criteria wereas follows: pregnancy, systemic diseases such as diabetes,
rheumatoid arthritis, hepatitis, coagulation disorders, previous surgery for elbow tendinosis, neurologic disorders,
uncooperative patients, steroid injection within the preceding 3 months and complete tendon ruptures (grade 4). This
study was conducted according to current GCP and ISO
14155 guidelines. All patients underwent informed consent
prior to the participation in this study. Patient selection was
conducted in the Wrightington Hospital in the UK and theSt. Elisabeth Hospital Tilburg in the Netherlands. The predominant symptom was pain at the insertion of the distal
biceps tendon in the radius unrelated to an acute traumatic
event. The clinical diagnosis of distal biceps tendonitis was
confirmed using magnetic resonance imaging (MRI), which
was a valuable tool in differentiating cases where there wassufficient tendinosis or partial tearing of the tendon, usuallynear or at its attachment site. A classification system wasused for grading the severity of tendinosis on MRI. The
4-point classification system can be described as follows:
0; normal tendon, 1; tendinosis of the distal biceps, withhigh signal and fluid in the tendon sheath, 2; partial tear at
the insertion site, 3; partial tear at the musculoskeletal junction, 4; complete rupture. MR imaging of the distal biceps
tendon was performed in the axial plane, with the patient’s
arm extended or with the arm overhead, the elbow flexed
to 90°, and the forearm supinated, so that the thumb points
superiorly. The acronym FABS, flexed elbow, abductedshoulder, forearm supinated, has been used to describe thisimaging technique [4].
The aim of this study was to evaluate the outcomes
after a single PRP injection, and additional injections
were defined as treatment failure. In the study period, 12
patients were recruited. Two were female, and ten weremale patients. The median age at onset of symptoms was
41 years. The median duration of symptoms was 8 months.
Table 1  Baseline demographic data
Baseline characteristics
Age years
Median (range)n = 1241 (28–65)

Gender n (%)
Male
FemaleHistory of repetitive heavy use of the elbow

10 (83)2 (17)

Sport n (%)

8 (67)

Occupation n (%)
Symptom duration (pre-intervention)

4 (33)Median months (range)

8 (0.8–36.5)

Knee Surg Sports Traumatol Arthrosc

All patients had a history of repetitive heavy use of theaffected elbow either through sport or occupation (Table 1).
US‑guided PRP injection
In ten patients, the GPS® Recover System (Biomet Biologics, Warsaw, Indiana) was used. This device uses a small
centrifuge and disposable cylinders to isolate the plateletand leucocyte-rich fraction from 27 mL of the patients’blood. Three microlitres of L-PRP was collected for eachpatient. PRP was buffered to physiological pH with 8.4 %sodium bicarbonate, which yielded an eightfold concentrate platelets of patients own blood. No activating agentswere used. Total time from blood aspiration to re-injectionof PRP was approximately 30 min. All procedures werecarried out in a standard day-case operating theatre in aseptic conditions. In the remaining two patients, different PRP
preparation systems were used, in one patient the Caption
system™ and in the other patient the Arthrex ACP™ wasused.
Ultrasound (US)-guided injection was performed withthe patient in supine position. At right angles, the probe
was placed into the distal biceps tendon, and the needle
was inserted parallel to the transducer. Continuous andreal-time US images were used to observe the advancementof the needle into the distal tendon. All patients had USguided PRP injections carried out by the two senior authors(LF & FvB).
Clinical and functional outcome assessment
Data analysis was performed by retrieving data frommedical records regarding patient demographics, duration of symptoms, details of previous therapies, type of
PRP preparation, complications, recurrences and lengthof follow-up. Clinical and functional outcome scores
were used pre-intervention, and at final follow-up at
which times the following were recorded: Visual Analogue Scale (VAS) rest and activity pain scores, subjective satisfaction measured on a scale of 0–100 and elbow
functional assessment (EFA) scores. In the English cases,
isometric muscular (biceps) strength was assessed using
the MICROFET2 hand-held dynamometer (Hoggan
Health Industries, Cooper IL.). This device records datain pounds and has been shown to be a valid and reliable measure of isometric strength [5, 9]. Post-treatment
regime included eccentric exercises to strengthen thebiceps and its tendon.
The Local Medical Ethical Committee and the Nationaland Institutional Review Board approved the study as anamendment to a randomised controlled trial in lateral epicondylitis. This trial is registered with identifier number
2007-004947-31 at http://www.clinicaltrials.gov.

Table 2  Pre-operative and post-operative MRI grading the severityof tendinopathy
Study no.

Pre-operative MRI

Post-operative MRI

1
2
3
4

3
1
3
2

n/a
n/a
n/a
n/a

5
6
7
8
9
10
11

1
2
2
1
2
3
1

2
0
1
1
0
1
0

12

3

2

Four-point classification system: 0; normal tendon, 1; tendinopathy ofthe distal biceps, with high signal and fluid in the tendon sheath, 2;partial tear at the insertion site, 3; partial tear at the musculoskeletal
junction, 4; complete rupture

Statistical analysis
This cohort study in two centres should be seen as a pilot
study focusing on feasibility and safety of this treatment.
A post hoc power analysis with the program G*Powerrevealed that on the basis of an n of 12, the mean and standard deviation of all measures of the pre- and post-scores,
the power was higher than the recommended 0.80 level.
A descriptive data analysis is presented for the demographics of the included patients. Data analysis of pre- andpost-injection outcome scores was performed using the
Wilcoxon Signed-rank test. Statistical analysis was performed by David Nuttall, Medical Statistician, Upper Limb
Unit, Wrightington using Statistical Package for the Social
Sciences (SPSS, Chicago, Illinois). The level of significance was set at p < 0.05.

Results
A total of 12 patients (two female and ten male patients)
with refractory distal biceps tendonitis with a median ageof 41 years and a median clinical follow-up of 47 months
were eligible for final assessment.
On the pre-operative MR imaging, six patients had apartial rupture and two patients had a grade III tear of the
distal biceps tendon. In the follow-up period, MRI was only
performed in the Dutch cases where two patients had a partial rupture, whereas the other patients showed only signsof tendinosis or had a normal tendon (Table 2). Wilcoxon
Signed-rank tests indicated significant improvement in13Knee Surg Sports Traumatol Arthrosc
Table 3  Data analysis of pre- and post-injection outcome scores(Wilcoxon Signed-rank test.)

VAS-r
VAS-a
EFA
Biceps strength

Pre-intervention

Final follow-up

p value

6 (3–8)8 (6–9)63 (54–94)

0.5 (0–2)
2.5 (0–4)
90 (70–100)<0.002<0.002<0.00414.5 (8–18)

22 (18–24)

VAS-scores both in rest and during activity and for the EFA.
The resting VAS (VAS-r) pain score showed an improvement in median from six pre-treatment to 0.75 post-treatment (Z = −3.07, p = 0.002). The activity VAS (VAS-a)score improved from a median of eight pre-treatment to a
median of 2.5 post-treatment (Z = −3.08, p = 0.002). The
functional assessment score EFA improved from a medianof 62.50–90.00 at final follow-up (Z = −2.85, p = 0.004).
In the English cases, isometric muscular strength improved
significantly with a 56 % increase (Table 3). There wereno adverse events of the interventional procedure and nopatients required more than one injection. There were nopatients with recurrence of symptoms.

Discussion
Most of the scientific publications involving the use of PRP
on human tendons are studies with poor methodologicalquality [10, 15, 20, 22]. To date, level I evidence only exists
for the use of PRP in lateral elbow tendinosis [11, 18, 19].
The present study is the first study to provide evidence
for the use of US-guided PRP injection in the treatmentof symptomatic refractory distal biceps tendonitis. Major
strengths of this study are the long-term follow-up in which
we included different grades of tendinosis with overall
good results for this method of treatment. Within a prospective study design, the clinical and functional outcome
scores are presented from two large tertiary hospitals. At amedian follow-up of 47 months (range 36–52 months), allpatients showed significant improvement in pain and functional outcome (p < 0.0001). All patients were satisfied
with the clinical outcomes at final follow-up. No adverse
events of PRP injection were reported, nor did any patientreport recurrence of symptoms.
Injuries to the tendons of the elbow occur frequently inthe overhead athlete, creating a significant loss of function
and a challenging dilemma to medical professionals. Distal biceps tendon injuries are uncommon, as illustrated by
the small cohort of patients recruited from two large tertiary referral hospitals in our study. There is a paucity of
the literature regarding the natural history and treatment
of distal biceps tendonitis. Conservative treatment options

13

are offered with the assumption that, like other tendinosis, it is a self-limiting condition. In our experience, distal
biceps tendonitis is difficult to manage with conservative
treatment proving frequently non-responsive to rest, splinting, NSAID’s and physical exercise programmes, whichis reflected by the duration of symptoms before injection
with PRP. Distal biceps tendonitis and tendinosis can beconsidered part of a continuous spectrum of disease withfrequently associated partial tearing of the distal biceps tendon [12]. Studies by Kelly et al. and Vardakas et al. [14,25] showed improvement in elbow function after surgicalrepair for symptomatic refractory distal biceps tendon tears
in small case series. In the analysis of these studies, however, it is impossible to distinguish between pathologic tendons that will resolve with time or respond to non-surgicaltreatment and those that require surgical treatment. The aimof this study was to provide evidence for the use of PRP
in refractory distal biceps tendonitis. Refractory tendonitis
was defined as cases in which symptoms were unresponsive
to 1 of 3 conventional therapy programmes (physical exercise therapy, non-steroidal anti-inflammatory medications
and local steroid injections). The median onset of symptoms was 8 months in our study. Distal biceps tendon disorders may be challenging to identify because of their diverse
clinical presentations. In our study, all patients diagnosis
was confirmed using a supplementary MRI, where a classification system was used for grading severity of lesion of
the distal biceps tendon. US-guided injection was used for
PRP injection in our study. An injection of the distal biceps
brachii tendon can be more accurately performed using US
guidance, because of the inherent difficulty in targeting the
distal biceps tendon deep within the antecubital fossa.
In the published medical literature, there is a paucity ofevidence for use of PRP in the management of distal biceps
tendonitis. Whilst the results of this study are promising,
there are some limitations, which warrant consideration.
The small number of patients can confound the clinicalresults; however, the rarity of distal biceps tendinitis as aclinical entity makes it almost impossible to conduct a
study with a larger patient cohort. Another weakness of thestudy is that the study population was not randomised witha control group, thereby failing to exclude a possible placebo effect. A further shortcoming of the study is that theeffectiveness of this method of treatment was not evaluatedat different time intervals. This would be favourable froma clinical point of view to evaluate the natural history of
the condition and the prognosis. The aim of this study wasto evaluate the outcomes after a single PRP injection, andadditional injections were defined as treatment failure. This
also can be a factor, which can influence the outcome. A
randomized controlled trial comparing outcomes for PRP
and surgical debridement and reattachment would also be
desirable. Whilst it is accepted that complete ruptures ofKnee Surg Sports Traumatol Arthrosc

the distal biceps in selected patients does well with anatomic repair, the literature is scarce regarding treatment ofpartial tears [14, 25].

Conclusion
This is the first study in a prospective multicenter design
to provide evidence for the use of PRP in refractory distal biceps tendonitis. All patients showed a significant
improvement in VAS rest and activity scores with subsequent improvements in EFA and high subjective satisfaction at final follow-up. US-guided PRP injection seems to
be an effective treatment modality for symptomatic refractory distal biceps tendonitis.

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