Manual Therapy 18 (2013) 611e614
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Manual Therapy
journal homepage: www.elsevier.com/math
Case report
The anterior recurrent peroneal nerve entrapment syndrome: A
patellar tendinopathy differential diagnosis case report
Eric Rousseau*,1
Physiotek, 10075 de la Farinière, Quebec, QC, Canada G2K1P7
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 June 2012
Received in revised form
1 October 2012
Accepted 5 October 2012
Patellar tendinopathy which is a cause of pain in the inferior patellar region is a relatively common
pathology among sports enthusiasts. This paper describes a new pain syndrome identified from clinical
observations which is a differential diagnosis to patellar tendinopathy. The pattern is specific and
recognizable among many individuals, and it should be considered as its own entity. The new syndrome
is discussed in terms of the pain experienced, the diagnostic criteria, treatment and the rationale to
explain it. As it is a differential diagnosis to patellar tendinopathy, many sports enthusiasts might benefit
from this diagnosis. If identified correctly, treatment might be directed to the correct structures and with
the appropriate modalities, ensuring the patients a fast return to their past occupations without pain and
without unwarranted treatments.
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Patellar tendinopathy
Jumper’s knee
Knee pain
Manual therapy
1. Introduction
The syndrome under discussion is derived mainly from clinical
observations. The author has noticed this clinical presentation
many times over the years but despite a search of the medical
literature, nothing similar was found. Since the overall presentation
pattern is specific and recognizable among many individuals, the
author proposes that it should be considered as its own entity. The
goal of this article is to acquaint the reader to this pain syndrome as
a specific differential diagnosis apart from patellar tendinopathy,
the latter being a common condition in sports. Its prevalence may
reach 50% in sports involving jumping and landing (Ramos et al.,
2009).
2. Case presentation
A 28 year old male carpenter came for consultation about
a patellar tendon pain. He was not referred by a physician. The pain,
while not severe enough to prohibit work, sports, or daily activities,
was very annoying to the patient as it began without any trauma
a year ago and he felt it every step when walking upstairs. In this
specific case, no other pain was felt. Tenderness was located on the
lateral border of the proximal patellar tendon. Upon examination,
* Tel.: þ1 418 262 3987.
E-mail address: [email protected].
1
I am the owner of a private physical therapy clinic. I have no competing
interests otherwise.
1356-689X/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.math.2012.10.003
increased peroneus muscles tone was noted as well as peroneal
nerve neurodynamic restriction (Butler, 2005) and a dorsal cuboid
subluxation as described by Mooney and Maffey-Ward (1994). The
lower quadrant scan was otherwise normal.
Initial treatment consisted of a plantar cuboid manipulation. No
hypomobility or hypermobility was felt after the manipulation. The
neurodynamics were now symmetrical on both legs. But there was
still a slightly increased tone in the peroneus muscles. Therefore,
the patient was taught to stretch the peroneus muscles. Immediately after the treatment, the patient did not experience any pain on
stairs. A telephone conversation with the patient 3 months later
revealed that he had remained pain free thereafter.
When there is pain typically associated with a provisional
diagnosis of patellar tendinopathy, immediate and maintained
improvement after the manipulation makes a narrower, more
definitive, diagnosis of patellar tendinopathy less likely. In contrast,
anterior recurrent peroneal nerve entrapment syndrome as presented in this case is more likely.
3. Typical patient presentation
When referred by a physician, the patient usually presents with
a diagnosis of patellar tendinitis, tendinosis, or tendinopathy. The
pain is usually a burning sensation located over the lateral patellar
tendon, sometimes radiating into the peroneus muscles. The
symptoms are usually intermittent and aggravated by physical
activities, mainly running and sometimes walking upstairs or
downstairs. Stretching in plantar flexion with inversion may also
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E. Rousseau / Manual Therapy 18 (2013) 611e614
exacerbate the symptoms. The patient may have tried other treatment regimens, including non-steroidal anti-inflammatory drugs,
eccentric strengthening exercises, ultrasound therapy and transverse friction massage but they mention only a temporary
improvement of a limited extent. Finally, there is no reported
sensation loss or paresthesia.
The pain associated with this syndrome is always reproducible
precisely on the lateral border of the proximal insertion of the
patellar tendon by palpation. This appears to be the most salient
feature. By contrast, in the case of patellar tendinopathy, the pain is
not specifically triggered by palpation at the lateral aspect of the
tendon. While some pain may be reproduced by palpation elsewhere around this specific area on occasion, the most tender spot is
always precisely the lateral border of the proximal insertion of the
patellar tendon, whereupon the clinician will note a consistent
increased muscular tone in the lateral compartment of the leg.
Usually there is altered neurodynamics (Butler, 2000) of the peroneal nerve. There is no sensation or motor loss, osteotendinous
reflexes are normal, ligamentous and meniscus tests are also
normal, resisted eversion and plantar flexion overpressure are
sometimes painful, and finally, the accessory movement findings
will reveal one of the following: superior tibiofibular subluxation or
inferior tibiofibular subluxation or cuboid subluxation with no
preferred direction of subluxation. Overall, the inferior tibiofibular
joint seems to be less frequently affected. This is a triad syndrome,
consisting of an exact painful spot, peroneus muscular hypertonicity, and some degree of varied subluxation.
4. Anatomy
The sciatic nerve splits into the common peroneal nerve and the
tibial nerve at the popliteal fossa or slightly above. After this division, the common peroneal nerve lies between the tendon of the
biceps femoris and lateral head of the gastrocnemius muscle,
where it might be occasionally compressed by a fabella (Boon and
Dib, 2009), an accessory sesamoid bone near the attachment of the
lateral gastrocnemius found in 8.5% of individuals (Zipple et al.,
2003). The common peroneal nerve then winds around the neck
of the fibula, entering the lateral compartment of the leg by
piercing the posterior intermuscular septum of the leg (Aigner
et al., 2004) and then entering the fibular tunnel between the
two heads of the peroneus longus (Dellon et al., 2002; El Gharbawy
et al., 2009), more precisely a superficial portion attaching to the
head of the fibula, and a deep portion which is attached to the
proximal to middle third of the fibula (Aigner et al., 2004). This
location is usually perceived to be the main culprit for common
peroneal nerve entrapments. The fibular tunnel is also where the
common peroneal nerve usually divides (Gray et al., 1977; Donovan
et al., 2010) and where the anterior recurrent branch nerve takes
origin and travels with the anterior tibial recurrent artery up to the
front of the knee (Gray et al., 1977) (Fig. 1).
5. Rationale
The rationale behind proposing this syndrome relates to the
increased tone in the peroneus muscles. Any orthopedic articular
subluxation capable of increasing muscular tone in the peroneus
muscles might be causal for this syndrome. The suspected underlying
pain mechanism is entrapment of the anterior recurrent branch of
the peroneal nerve in the fibular tunnel secondary to the increased
peroneus muscles tone. It is relatively easy to imagine a superior
tibiofibular or inferior tibiofibular subluxation increasing the tone of
the peroneus muscles, possibly via muscle guarding. But if the cuboid
bone subluxation increasing the peroneus muscle’s tone might be
more abstract for some, it is related to the pulley role of the cuboid
Fig. 1. Drawing shows the common peroneal nerve and its branches at the knee. The
common peroneal nerve wraps around the fibular neck and under the peroneus longus
muscle to trifurcate into the recurrent articular branch to the knee capsule, the
superficial peroneal nerve, and the deep peroneal nerve. Image reproduced with
permission from Donovan et al. (2010).
bone in relation to the peroneus longus muscle since the peroneus
longus tendon runs through the peroneal groove on the plantar
aspect of the cuboid (Roney, 2010). The increased muscle tone is
shortening the muscle, which cause some compressive force in the
fibular tunnel, as it removes some slack. Moreover, muscle fibers can
swell up to 20 times their resting size (Fronek et al., 1987), thus
possibly contributing to reduction of space available in the tunnel.
The presence of subluxation is based on the assessment of
accessory joint glides and passive physiological tests described by
Maitland (Hengeveld and Banks, 2005) and Kaltenborn et al.
(2002). The cuboid bone assessment was described more specifically by Mooney and Maffey-Ward (1994) and Patterson (2006).
Sijbrandij (1978) described the passive play of the proximal tibiofibular joint. Although not frequently evaluated, proximal tibiofibular joint subluxation is not a rare pathology (Semonian et al.,
1995) and the diagnosis is easily missed (Gillham and Villar,
1989). Finally, Beazell et al. (2009) described the passive testing
of the inferior tibiofibular joint.
In this paper subluxation is used to describe a joint which seems
malpositioned and very stiff in the opposite direction, but not
necessarily out of range, secondary to neurophysiological and/or
mechanical constraints. Some therapists prefer to use gentle
mobilization or neurophysiological techniques instead of manipulations and this seems to have similar results (Lederman, 2010).
Stretching the peroneus muscles probably also increases the
pressure over the anterior recurrent branch of the peroneal nerve.
The peroneal nerves are also themself stretched by the same
movement, increasing the tethering in the fibular tunnel area.
Repetitive exercises involving inversion, stretches the common
peroneal nerve against the fibrous arch of the fibular tunnel and is
thought to be a cause for common peroneal nerve entrapment
syndrome (McCrory et al., 2002). The reason why resisted eversion
is painful is probably also because it momentarily increases the
tone of the peroneus muscles, also compressing the nerves in the
fibular tunnel. The author has not witnessed similar cases with
E. Rousseau / Manual Therapy 18 (2013) 611e614
increased tone in the extensor digitorium longus or the anterior
tibialis, but believes the possibility exists, since the anterior
recurrent branch of the peroneal nerve is traveling under the
tendon of both muscles.
6. Treatment
The initial treatment consists of a high velocity low amplitude
thrust of the subluxated joint with joint mobility re-assessed post
manipulation. The peroneus muscular tone is always lesser after
a successful manipulation. If pain was felt while walking or going
upstairs or downstairs, most of the time the effect is immediate,
and the activity is now painless or subjectively much better. The
cuboid thrust is described in the cuboid syndrome literature
(Huang et al., 1999). Beazell et al. (2009) described a superior
tibiofibular joint manipulation, while Broome (2000) wrote about
both the anterior and posterior thrust of both the distal and proximal tibiofibular joints. Loudon and Bell (1996) also described
mobilization techniques of both tibiofibular joints.
If the motion exceeds the normal anatomic limits post manipulation, then supportive taping will be applied. If no excessive
motion is felt then taping is not applied, but upon recurrence,
taping will be used. Taping has two possible mechanisms: First, it
limits the motion to a smaller range so gradually fibrous tissue
restricts the actual range of motion. Second, it probably has
a proprioceptive role, retraining the central nervous system to learn
the new imposed boundaries of range of motion. Neurodynamics
exercises are also taught, if still restricted after the thrust, to ensure
freely moving neural structure (Shacklock, 2005).
The focus over the next few treatment sessions is to restore
normal joint mobility, normal peroneus muscle tone, normal neurodynamics, and eliminate any residual pain at the patellar tendon.
Usually, everything is already normalized on the second visit. Joint
mobilization, muscle stretching and neurodynamic exercises if
appropriate may be needed. Strangely, locally symptomatic
subluxation in this specific syndrome has not been seen. Usually,
the treatment is highly effective but if there is persistent pain even
after the described treatment then there is possibility of a real
tendinopathy. The treatment regimen must then be modified
accordingly, eccentric strengthening of the quadriceps being key
(Peers and Lysens, 2005).
613
to let a specific nerve glide and stretch. Reasons may include
sensitization of neural connective tissue nociceptors, central
sensitization (Woolf, 2011), or presence of an abnormal impulse
generating site (AIGS) (Nee and Butler, 2006). In all the cases where
the actual syndrome was identified, any evidence of central sensitization was not seen by the author. However, the possibility of
a mechanically sensitive AIGS is probable in some cases, where
a segment of the nerve develops the capacity of generating
impulses. Orthodromic impulses traveling in the direction of the
spinal cord possibly mime a nociceptive input while antidromic
impulses in the nerve ending’s territory make C fiber endings act
like a gland (Sann and Pierau, 1998), releasing Substance P and
Calcitonin Gene Related Peptide which are vasoactive peptides
(Butler, 1991), causing plasma extravasation and thus swelling. In
this neurogenic inflammation condition, treating strictly the
inflammation will not address the real problem and eccentric
exercises typically taught for patellar tendinopathy might in fact
increase the pain since it may trigger an AIGS. Moreover, in the
literature, it seems pretty accepted that there isn’t much
prostaglandin-mediated inflammation in patellar tendinopathy but
there are some neurogenic inflammatory markers, such as neuropeptides (Kountouris and Cook, 2007). Thus, it is possible that in
some cases of patellar tendinopathy, an anterior recurrent branch
of the peroneal nerve syndrome might have contributed to a real
tendinopathy.
8. Conclusion
A new pain syndrome has been described as well as a treatment proposal plus the rationale behind it. As a differential
diagnosis to patellar tendinopathy, many sports enthusiasts might
benefit from this diagnosis. If identified correctly, treatment
might be directed to the correct structures with the appropriate
modalities ensuring patients a fast return to their past occupations without pain, and without unwarranted treatments. Future
research should involve other therapists testing the proposed
triad within a group of patients diagnosed with a patellar tendinopathy in order to identify which percentage of these patients
answer the criteria presented in this paper. The relative effectiveness of the treatment proposal in comparison with a control
group would make it possible to confirm the existence of the
suggested syndrome.
7. Discussion
References
7.1. Pain localization
In the new syndrome the patellar tendon pain is located over the
lateral border of the proximal attachment, while in the case of
tendinopathy it is described in the literature as only proximal. In
fact there are very few descriptions in the literature of the precise
area of tenderness of the patellar tendon. Cook et al. (2001) in
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The same study comes to the conclusion that patellar tendon
palpation is not specific. Rath et al. (2010) reported the pain as in
the middle of the proximal tendon. Consequently, lateral tenderness does not mean there is entrapment of the anterior recurrent
branch of the peroneal nerve, but if there is also increased peroneus
muscles tone and a tibiofibular or cuboid subluxation, the specificity is possibly increased considerably.
7.2. Pathophysiology
Without compression, a nerve may test reactive to neurodynamic testing, which assesses the disposition of the whole body
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