Surgical plantaris tendon removal for patients with plantaris tendon-related pain only and a normal Achilles tendon: a case series

Abstract

Objectives
Surgical removal of the plantaris tendon can cure plantaris-associated Achilles tendinopathy, a condition in which Achilles and plantaris tendinopathy coexist. However, rare cases with plantaris tendinopathy alone are often misdiagnosed due to a normal Achilles tendon.

Design and setting
Prospective case series study at one centre.

Participants
Ten consecutive patients (9 men and one woman, mean age 35 years, range 19–67) with plantaris tendon-related pain alone in altogether 13 tendons were included. All had had a long duration (median 10 months, range 3 months to 10 years) of pain symptoms on the medial side of the Achilles tendon mid-portion. Preoperative ultrasound showed thickened plantaris tendon but a normal Achilles tendon.

Interventions
Operative treatment consisting of ultrasound-guided excision of the plantaris tendon.

Primary and secondary outcome measures
Scores from Victorian Institute of Sports Assessment-Achilles questionnaire (VISA-A)were taken preoperatively and postoperatively (median duration 10 months). Patient satisfaction and time until full return to sports activity level was asked by a questionnaire.

Results
The VISA-A scores increased from 61 (range 45–81) preoperatively to 97 (range 94–100) postoperatively (p<0.01). Follow-up results at 10 months (range 7–72 months) on 9/10 patients showed full satisfaction and return to their preinjury sports or recreational activity

Conclusion
The plantaris tendon should be kept in mind when evaluating painful conditions in the Achilles tendon region, especially when no Achilles tendinopathy is present. Excision of the plantaris tendon via a minor surgical procedure in local anaesthesia results in a good outcome.

Full text

AlfredsonH, etal. BMJ Open Sport Exerc Med 2018;4:e000462. doi:10.1136/bmjsem-2018-000462 1
Open access Original article
Surgical plantaris tendon removal for
patients with plantaris tendon-related
pain only and a normal Achilles tendon:
a case series
Håkan Alfredson,1,2,3 Lorenzo Masci,3 Christoph Spang4
To cite: AlfredsonH, MasciL,
SpangC. Surgical plantaris
tendon removal for patients
with plantaris tendon-related
pain only and a normal Achilles
tendon: a case series. BMJ
Open Sport & Exercise Medicine
2018;4:e000462. doi:10.1136/
bmjsem-2018-000462
Accepted 12 November 2018
1Sports Medicine Unit,
Department of Community
Medicine and Rehabilitation,
Umeå University, Umeå, Sweden
2ISEH, UCLH, London, UK
3Pure Sports Medicine Clinic,
London, UK
4Anatomy Section, Department
of Integrative Medical Biology,
Umea University, Umeå, Sweden
Correspondence to
Mr Christoph Spang; Christoph.
Spang@ umu. se
© Author(s) (or their
employer(s)) 2018. Re-use
permitted under CC BY-NC. No
commercial re-use. See rights
and permissions. Published by
BMJ.
What are the new ndings?
►Plantaris tendinopathy can occur without Achilles
tendinopathy.
►Plantaris tendinopathy may be misdiagnosed be-
cause ultrasound and MRI examination show a nor-
mal Achilles tendon.
►Excision of the plantaris tendon in patients with
plantaris tendon-related pain (plantaris tendinopa-
thy) results in pain relief and fast return to full sports
activity.
ABSTRACT
Objectives Surgical removal of the plantaris tendon can
cure plantaris-associated Achilles tendinopathy, a condition
in which Achilles and plantaris tendinopathy coexist.
However, rare cases with plantaris tendinopathy alone are
often misdiagnosed due to a normal Achilles tendon.
Design and setting Prospective case series study at
one centre.
Participants Ten consecutive patients (9 men and one
woman, mean age 35 years, range 19–67) with plantaris
tendon-related pain alone in altogether 13 tendons
were included. All had had a long duration (median 10
months, range 3 months to 10 years) of pain symptoms
on the medial side of the Achilles tendon mid-portion.
Preoperative ultrasound showed thickened plantaris
tendon but a normal Achilles tendon.
Interventions Operative treatment consisting of
ultrasound-guided excision of the plantaris tendon.
Primary and secondary outcome measures Scores
from Victorian Institute of Sports Assessment-Achilles
questionnaire (VISA-A)were taken preoperatively and
postoperatively (median duration 10 months). Patient
satisfaction and time until full return to sports activity level
was asked by a questionnaire.
Results The VISA-A scores increased from 61 (range 45–
81) preoperatively to 97 (range 94–100) postoperatively
(p<0.01). Follow-up results at 10 months (range 7–72
months) on 9/10 patients showed full satisfaction and
return to their preinjury sports or recreational activity
Conclusion The plantaris tendon should be kept in
mind when evaluating painful conditions in the Achilles
tendon region, especially when no Achilles tendinopathy
is present. Excision of the plantaris tendon via a minor
surgical procedure in local anaesthesia results in a good
outcome.
INTRODUCTION
Chronic pain in the Achilles tendon mid-por-
tion is a quite common condition among
professional and recreational athletes. Treat-
ment can often be very challenging especially
during the season.1 Despite good clinical
outcomes of conservative measures such
as heavy load eccentric training,2 several
patients still need to be operated for a proper
pain relief.3
In many of those non-responding cases
a coexisting tendinopathy in the neigh-
bouring plantaris tendon has been found,4 5
especially in those where the pain is located
rather medially.6 Surgical explorations have
detected a thickened plantaris tendon in
close vicinity to the medial Achilles tendon7
leading to interference between the two
tendons during certain movements.8 Anatom-
ical studies have found up to nine different
insertional areas of the plantaris tendon
among the population,9 10 some potentially
influencing the Achilles tendon.11 12 Surgical
removal of the plantaris tendon in patients
with plantaris-associated mid-portion Achilles
tendinopathy has resulted in very good
clinical outcomes13–16 including structural
improvement of the medial Achilles tendon
area.15 16
New clinical experiences show that in a few
cases plantaris tendinopathy alone, without
coexisting mid-portion Achilles tendinop-
athy, occurs and causes debilitating pain in
the Achilles tendon region. These patients
are often misdiagnosed because ultrasound
(US) and MRI examinations show a normal
Achilles tendon. This study aimed to describe
typical clinical and US findings in this rare
condition, and also to prospectively follow

2AlfredsonH, etal. BMJ Open Sport Exerc Med 2018;4:e000462. doi:10.1136/bmjsem-2018-000462
Open access
Figure 1 Ultrasound examination of a patient with a normal
Achilles tendon (longitudinal view) (A). Cross view showing a
thickened plantaris tendon (arrow) on the medial/ventral side
of the Achilles (B).
Figure 2 Surgical exploration in local anaesthesia via a
1 cm long skin incision on the medial side of the Achilles
tendon mid-portion in a patient with plantaris tendinopathy.
The plantaris tendon is seen embedded in vascularised fat
tissue on the medial side of the Achilles (A). Extirpation of
5–6 cm of the plantaris tendon and adjacent fat tissue .
the clinical results after surgical treatment with plantaris
tendon removal.
METHODS
Patients
The study includes a case series of 10 consecutive patients
(9 men and one woman, mean age 35 years, range 19–67)
with plantaris tendon-related pain alone in altogether 13
tendons. All patients were sports active, ranging from
national high level in sprint, hurdles, long jump and hand-
ball to recreational jogging. All had had a long duration
(median 15 months, range 3 months to 120 months) of
pain symptoms on the medial side of the Achilles tendon
mid-portion. Typical symptoms and history include occa-
sions with sharp pain on the medial side of the Achilles
tendon mid-portion during explosive ankle joint move-
ments like sprinting. Symptoms often subsided quickly
within 3–4 days, and the traditional eccentric exercises
used for treatment of mid-portion Achilles tendinopathy
often caused a worsening with more pain on the medial
side.
Presurgical examinations
Clinical examination
Clinically all patients showed a non-thickened and
non-tender Achilles tendon mid-portion. Local tender-
ness was only found medially to the Achilles tendon
mid-portion.
US+colour Doppler examination
Examination via US+colour Doppler showed a normal
Achilles tendon (figure 1A). No thickening, no hypoe-
chogenicity and no high blood flow were detected.
Dynamic US examination following the plantaris from
proximal to distal showed a thickened plantaris tendon
(arrow) located close to the medial side of the Achilles
tendon mid-portion (figure 1B).6
Surgical procedure
During surgical treatment under local anaesthesia, the
medial aspect of the Achilles tendon was visualised and
carefully inspected (figure 2). The exact location and
macroscopic appearance of the plantaris tendon was
identified. The surgical treatment consisted of a release
of the plantaris tendon followed by excision distally
from the calcaneal insertion and proximally at a level
slightly above the distal medial soleus muscle insertion.
In contrast to the previously described procedure there
was no need for treatment of the medial aspect of the
(normal) Achilles tendon.6 7
Outcome measures
For evaluation before surgery functional scores (Victo-
rian Institute of Sports Assessment-Achilles questionnaire
(VISA-A); 0–100; 100 is perfect function) were taken. For
follow-up purpose a questionnaire asking about satisfac-
tion with the result of the operation (‘satisfied’ or ‘not
satisfied’) and time to return to preinjury sport or recre-
ational activity was used together with the VISA-A score.
RESULTS
The median follow duration was 10 months (range /7-72
months) after surgery. Before surgery VISA-A scores and
questionnaire info were obtained from 9/10 patients
(12/13 plantaris tendons). The preoperative VISA-A
functional score was 61 (ranging from 45 to 81). After

3
AlfredsonH, etal. BMJ Open Sport Exerc Med 2018;4:e000462. doi:10.1136/bmjsem-2018-000462
Open access
surgery, VISA-A scores were obtained from 7/10 patients
(8/13 plantaris tendons) and questionnaire information
from 7/10 patients. The postoperative VISA-A functional
score was 97 (ranging from 94 to 100). All patients who
sent back the questionnaire (7/10 patients) were satisfied
and had returned to their preinjury sports or recreational
activity. There were no complications in relation to the
surgical procedure.
For the patients where scores and questionnaire are
missing, we know that one athlete had a quick return
to previous activity level, was pain free and competed in
Golden League event within 3 months after surgery and
continued with pain-free high-level sports for another 2
years, before retiring. Another patient gave information
via telephone call and was satisfied and pain free after
surgery but retired from high-level sports due to other
reasons. From one patient we have no information as
he never returned scores or questionnaire, and never
answered telephone calls.
DISCUSSION
Mid-portion Achilles tendinopathy is relatively common
among running athletes and recreationally active individ-
uals. However, there are patients complaining of pain on
the medial side of the Achilles tendon mid-portion where
US and MRI show normal findings. For this subgroup
there is often no diagnosis and there has previously been
no help to offer. However, with the recent knowledge
about the plantaris tendon as a possible source of pain
on the medial side of the Achilles tendon there is now a
new possible diagnosis.
In this study on a group of elite and recreational
athletes suffering from pain on the medial side of the
Achilles we found that all had normal Achilles tendons.
Using dynamic US examination an often relatively thick
plantaris tendon was found to be located close to the
Achilles tendon mid-portion in the region for pain during
loading and tenderness during palpation. After surgical
removal of the plantaris tendon alone, all patients but
one (missing data) in this cohort became pain free and
returned to their preinjury sport or recreational activity
level often within short periods after surgery. These results
clearly indicate that the pain was related to the plantaris
tendon and the soft tissues surrounding the plantaris. In
fact, it has been shown that plantaris tendons exhibit on
average more sensory nerves than previously described
for the Achilles tendons.5 Thus, the plantaris is structur-
ally capable to transmit the pain.
The plantaris tendon is well known to be difficult to
localise/identify, and earlier anatomical studies have
claimed that up to 20% individuals lack this tendon.10
However, recent research on cadavers (following the
plantaris from proximal to distal) has shown that most
likely all individuals have a plantaris tendon, but the
course and insertion of the plantaris tendon varies, and
up to nine different positions in relation to the Achilles
mid-portion have been reported.9 US has been shown to
be useful to identify and follow the course of the plantaris
tendon,9 10 but the method does not pick 100% of the
plantaris tendons, showing that due to the positioning
of the plantaris tendon in certain individuals it is diffi-
cult to separate from the Achilles tendon. This is also our
clinical experience, where we in rare cases find the plan-
taris tendon to be invaginated into the medial side of the
Achilles tendon.
The individuals in our study were all involved in sports
and recreational activity, and 7/10 were track and field
athletes (sprinters, long jump, pool vault), with forceful
explosive full-range ankle joint movements in their
sport. All complained from having sharp pain on the
medial side of the Achilles when pushing off, a type of
pain that was so strong that they could not run through
it. It appears that loading in maximal plantar flexion
might be a risk factor for individuals having a plantaris
tendon located close to the medial side of the Achilles.
In a recent cadaver study, using US and macroscopical
dissection, it was shown that the plantaris tendon had
three different movement planes: superior-inferior, ante-
rior-posterior and medial-lateral.8 With this information
it is likely that depending on the individual positioning of
the plantaris tendon, certain ankle joint movements will
provoke the plantaris and adjacent tissues differently. Of
interest from this patient cohort is that all patients had
felt a worsening from trying treatment with eccentric calf
muscle training. This indicates that going from loaded
maximum plantar flexion to maximal dorsiflexion
provokes plantaris tendon-related pain, and if this also is
found in larger population studies, it can be used as part
of the diagnostic tools for this diagnosis.
This study includes a rather small material, 10 patients
with 13 painful plantaris tendons, and larger materials are
needed for stronger conclusions to be made. However,
our clinical experience is that plantaris tendon-related
pain alone is rare. Most patients complaining from pain
in the Achilles tendon mid-portion have Achilles tend-
inopathy alone, and sometimes together with plantaris
tendon involvement. The group of patients with plantaris
tendon-related pain alone, having a normal Achilles, is
small and it will take time to get large materials. Another
weakness in this study is that we could not get follow-up
details from all patients, and that is unfortunately a
common problem when involving athletes, maybe espe-
cially when they like in this study come from different
countries.
In conclusion, we suggest to keep the plantaris tendon
in mind when evaluating painful conditions in the
Achilles tendon region. Plantaris tendinopathy-related
pain alone and normal Achilles tendon exist. Short-term
results from excision of the plantaris tendon via a minor
surgical procedure in local anaesthesia have been shown
to be good.
Acknowledgements The authors thank all the patients for their willingness to
participate in this study.
Contributors HA performed all surgeries and clinical examinations. CS performed
the data analysis and wrote main parts of the manuscript. LM has contributed

4AlfredsonH, etal. BMJ Open Sport Exerc Med 2018;4:e000462. doi:10.1136/bmjsem-2018-000462
Open access
considerably to patient recruitment and manuscript writing. All authors were
involved in the design of the study, data collection and manuscript writing. The
manuscript was nally approved by all authors.
Funding The authors have not declared a specic grant for this research from any
funding agency in the public, commercial or not-for-prot sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Studies on Achilles and plantaris tendinopathy were approved by
the local ethics committee (Umea University, Sweden).
Provenance and peer review Not commissioned; internally peer reviewed.
Open access This is an open access article distributed in accordance with the
Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which
permits others to distribute, remix, adapt, build upon this work non-commercially,
and license their derivative works on different terms, provided the original work is
properly cited, appropriate credit is given, any changes made indicated, and the
use is non-commercial. See: http:// creativecommons. org/ licenses/ by- nc/ 4.0
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