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					THE PODIATRIST’S GUIDE TO TRIGGER POINTS AND
        MYOFASCIAL PAIN SYNDROME

   Introduction
   What is Myofascial Pain Syndrome
          1.0 Trigger points
          2.0 Sensory Phenomena
          3.0 Motor Phenomena
          4.0 Autonomic Phenomena
   Aetiology
   Diagnosis
          1.0 History
          2.0 Physical Examination
                  2.1 Palpation Techniques
                  2.2 Physical Responses
          3.0 Guide to Areas of Referred Pain
          4.0 Muscles
                  4.1 Tibialis Anterior
                  4.2 Peroneus Longus, Brevis and Tertius
                  4.3 Gastrocnemius
                  4.4 Soleus
                  4.5 Tibialis Posterior
                  4.6 Extensor Digitorum Longus and Extensor Hallucis Longus
                  4.7 Flexor Digitorum longus and Flexor Hallucis Longus
                  4.8 Abductor Hallucis
                  4.9 Extensor Digitorum Brevis and Extensor Hallucis Brevis
                  4.10 Abductor Digiti Mini and Flexor Digitorum Brevis
                  4.11 Quadratus Plantae
                  4.12 Adductor Hallucis and Flexor Hallucis Brevis
                  4.13 Interossei
          5.0 Criteria for Diagnosis of Myosacial Pain Syndrome
          6.0 Imaging Techniques
   Differential Diagnoses
   Treatment
          1.0 Orthoses
          2.0 Physical Therapy
          3.0 Trigger Point Injection
   Conclusion
   References
INTRODUCTION
_____________________________________________________________________

      Myofascial pain syndrome (MPS) is “a muscular pain disorder involving
      regional pain referred by trigger points (TrPs) within the myofascial structures
      local or distant from the origin of pain” (11). The reported prevalence of MPS
      varies greatly, ranging from between 5% to 93% of the population (6,9,10).
      This variance is due in part to non-uniform diagnostic criteria (6), lack of
      satisfactory laboratory or imaging tests (6) and more simply, because of the
      sheer number and locations that TrPs can manifest in the body.

      A large quantity of published research exists on TrPs and MPS in the upper
      body, with relatively little attention devoted to the lower extremity. Currently,
      no undergraduate training in the diagnosis or management of MPS exists in
      podiatry. Despite this, it remains an important differential diagnosis to
      consider in patients with persistent pain that has defied „appropriate‟
      treatment.

      The main purpose of this project is to give podiatrists a simple and concise
      overview on how to diagnose the more common TrPs in the leg and foot. It
      will also cover in brief the fundamentals of MPS, its aetiology, differential
      diagnoses and treatment options, with special reference on the use of orthoses
      in the management of the condition.



WHAT IS MYOFASCIAL PAIN SYNDROME?
_____________________________________________________________________

      The precise features that define MPS vary in the literature. The condition is
      defined by the presence of TrPs, although certain criteria must also be met
      before a diagnosis of MPS can be made. Travell and Simons, authors of the
      definitive text on the subject, believe the sydrome to be comprised of sensory,
      motor and autonomic phenomena (11).


1.0 TRIGGER POINTS

      The most widely accepted definition of a TrP is “a hyperirritable spot, usually
      within a taut band of skeletal muscle or in a muscle fascia. The spot is painful
      on compression and can give rise to characteristic referred pain, tenderness
      and autonomic phenomena” (11).

      TrPs can be categorised as active, latent or satellite. In brief, an active TrP is a
      source of ongoing pain, a latent TrP is only painful when compressed and a
      satellite TrP develops within the area of referred pain of an active TrP (19).

      There is considerable debate surrounding the pathophysiological mechanism
      in the formation of TrPs. The most generally accepted theory implicates the
      interaction of calcium with adenosine triphosphate (ATP). Following either
    acute or chronic trauma, the sarcoplasmic reticulum in the muscle cell
    becomes damaged, releasing calcium. In the presence of ATP, it binds to
    troponin and results in contraction of the muscle fibre. Because the
    sarcoplasmic reticulum is damaged it cannot facilitate the re-uptake of calcium
    and the muscle fibres remain contracted. The sustained contraction leads to
    localised hypoxia and uncontrolled levels of metabolic activity, resulting in
    the release of serotonin, histamine, kinins and prostoglandins. These
    substances act to sensitise muscle nociceptors which converge with other
    visceral and somatic inputs and lead to the perception of local and referred
    pain (18B).

    The perception of pain stimulates motor units via the central nervous system,
    thereby inducing muscle spasm, which, if left untreated will initiate a muscle
    pain-muscle spasm cycle. There is an associated decrease in local blood flow
    and an overall reduction in ATP and the action of the calcium pumps. Over
    time, noxious metabolites and inflammatory mediators build up in the area
    leading to fibrosis and a worsening of symptomology (18B).


2.0 SENSORY PHENOMENA

    Pain due to MPS can vary from a mild ache to being excuciating or burning
    (10). It can be localised to an area around the TrP or referred to another area of
    the body. The sensation of localised pain can be attributed to damaged muscle
    membranes. The release of seratonin and histamine from elevated platelet
    levels and degranulating mast cells and bradykinin serve to sensitise
    nociceptors and lead to the sensation of pain (17).

    The sensation of referred pain however is not as easily explained. TrPs result
    in specific and predictable patterns of referred pain, yet follow no dermatome,
    myotome or sclerotomal pattern (9). There are many mechanisms that have
    been postulated to explain this phenomenon which result from anatomical
    changes related to neural plasticity or modulations of afferent or sympathetic
    nervous system activity (22).


3.0 MOTOR PHENOMENA

    The presence of taut bands and TrPs can result in a decreased range of motion
    at the joint/s which the muscle crosses, muscle weakness and muscular
    imbalaces (18B).


4.0 AUTONOMIC PHENOMENA

    Travell and Simons (11), report that autonomic changes found in the lower
    extremities include localised vasoconstriction, increased sweating and
    pilomotor activity. Many studies looking at thermographic imaging of TrPs
    have found evidence of sympathetic autonomic changes. There tends to be an
      increase in thermal emissions in the vicinity of a TrP and more diffuse areas of
      hyperaemia along the zones of referred pain (7,8).


AETIOLOGY
_____________________________________________________________________

      The formation of TrPs in the lower extremity can be in response to a single
      inciting event or repetitive microtrauma. They commonly arise as a secondary
      phenomena to lateral ankle sprains and acute knee injuries or following
      overuse pathology and the development of antalgic patterns of gait (5).

      Biomechanical abnormalities such as the compensations for a limb length
      discrepancy, abnormal subtalar joint pronation or a hallux limitus can increase
      stress on the musculoskeletal system and promote the formation and
      perpetuation of TrPs. Increases in the contact phase velocity and degree of
      subtar joint pronation can lead to TrPs in tibialis anterior and tibialis posterior.
      A hallux limitus can cause an unstable medial column during late midstance
      and propulsion and result in TrP formation in peroneus longus and/or the
      intrinsic musculature. Similarly, an ankle equinus could instigate the
      development of TrPs in the superficial deep and anterior compartment
      musculature.

      Other causes or precipitating factors include poor work ergonomics leading to
      muscle overuse, stress and various rheumatological conditions. Metabolic
      disorders related to thyroid, parathyroid, oestrogen, cortisol and adrenal
      abnormalities have also been implicated (18C).


DIAGNOSIS
____________________________________________________________________

1.0 HISTORY

      As in most conditions, a detailed history is imperative for an accurate
      diagnosis. Below are a number of key questions that should be asked when
      attempting to diagnose MPS (12).

      1. What is the quality of the pain?
      Pain associated with MPS is poorly localised and usually presents with a dull
      and aching quality (12,18B) that is contiuous or intermittent (10). Stiffness
      and fatigue is generally reported (18B) and on rare occasions it ma y manifest
      as an excruciating or burning pain (10).

      2. How is the patient sleeping at night?
      A disturbed sleep pattern is another diagnostic feature of MPS. The patient
      will often report difficulty in falling sleeping, restless sleep and waking in the
      morning with feelings of fatigue (12). These findings however, are more
      commonly associated with MPS presenting in the upper body.
     3. What relieves the pain?
     Typically, short periods of rest, slow and passive stretching and short periods
     of light activity will aid in the reduction of symptomology (11). Patient‟s may
     obtain relief by taking a hot bath, the use of moist heat over the TrP, or a cold
     pack over the area of referred pain (10,18B).

     4. What exacerbates the pain?
     Strenuous activity, contracting the affected muscle against a resistance,
     pressure on a TrP and cold, damp or drafty conditions may serve to augment
     the pain (11).


2.0 PHYSICAL EXAMINATION

     The examination of taut bands and trigger points is difficult and fraught with
     issues of inter and intra-tester reliability (we are not alone) (21). Adequate
     training is advised to develop the skills necessary to make valid assessments of
     active TrPs (16A), yet no evidence exists to support this belief (16B).

     Before beginning the assessment, the patient should be comfortable and warm.
     Individuals with MPS may also present with weakness of the affected
     musculature and a decreased range of motion at the joint/s which the muscle
     crosses (18B). It is therefore prudent to assess muscle strength and joint range
     of motion, and compare the findings with the contralateral side.


2.1 PALPATION TECHNIQUES

     When testing for taut bands and TrPs, „flat palpation‟ is the most useful
     diagnostic technique for the majority of muscles in the leg, foot and ankle.
     Below is a description of flat palpation as reported in Travell and Simons (11).



      Figure . Cross sectional schematic drawing showing flat palpation of a taut band.

         ... flat palpation refers to a moving fingertip that employs the
         mobility of the subcutaneous tissue to slide the patient‟s skin across
         the muscle fibres. This movement permits the detection of changes
         in the underlying structures. The skin is pushed to one side of the
         area to be palpated (Fig. A) and the finger slid across the fibres to
         be examined (Fig. B) allowing the skin to bunch on the other side
         (Fig. C). Any ropy structure (taut band) within the muscle is felt as
         it is rolled under the finger. A taut band feels like a cord 1-4 mm in
         diameter. Transverse snapping palpation of a taut band can be
         mentally compared to what plucking a violin string embedded in the
         muscle would feel like.

         When a band is identified, it is explored along its length to locate
         the maximum tenderness in response to minimum pressure; that is
         the TrP.
       Another technique described in Travell and Simons (11) that is indicated when
       palpating the gastrocnemius or soleus muscles is the „pincer palpation‟.



       Figure . Cross-sectional schematic drawing showing pincer palpation of a taut band.

            The technique of pincer palpation is performed by grasping the
            belly of the muscle between thumb and finger (Fig. A) and
            squeezing the fibres between them with a back and forth rolling
            motion to locate taut bands (Fig. B/C).

            When a band is identified, it is explored along its length to locate
            the spot of maximum tenderness in response to minimum pressure;
            that is the TrP.


2.2 PHYSICAL R ESPONSES

Upon palpation of a TrP, a number of responses may be elicited.

       1. Local twitch response: a major diagnostic feature of a TrP in a taut band
       is the local twitch response and is defined as a localised twitch of a muscle
       (11).

       2. Jump sign: as its name suggests, this occurs when enough pressure is
       applied to an active TrP to make the patient jump. The amount of pressure
       required to elicit the jump sign provides an indication as to the irritability of
       the TrP (11).

       3. Induction of referred pain: this is when the palpation of an active TrP
       induces a pattern of referred pain, and usually occurs following sustained and
       firm pressure. It is important to remember that in addition to localised pain,
       the pattern of referred pain may develop immediately, or take up to 10 sec to
       appear (11).


       NOTE: Palpating TrPs can greatly exacerbate the symptoms of referred pain
       for a period of hours to days. As such, it is important to treat the affected area
       with specific myofascial therapy. As podiatrists we have no formal training in
       this area, therefore appropriate referral may be necessary.


3.0 GUIDE TO AREAS OF REFERRED PAIN

       The diagrams below lists designated areas of referred pain. Merely click on a
       designated area to see the muscle/s that commonly refer pain to that specified
       area.
       NOTE: A number of more proximal muscles that refer pain to the leg were
       omitted because they were beyond the scope of this report. Also omitted were
       certain intrinsic muscles due to insufficient information.



         Figure . Designated areas of pain where patients may describe myofascial pain.




ANTERIOR LEG                                        Adductor hallucis
Tibialis anterior                                   Tibialis posterior
                                                    Soleus
POSTERIOR LEG                                       Abductor hallucis
Soleus                                              Interossei
Gastrocnemius
Flexor digitorum longus                             DORSAL FOREFOOT
Tibialis posterior                                  Extensor digitorum brevis             and
                                                    extensor hallucis brevis
LATERAL LEG                                         Extensor digitorum longus
Gastrocne mius                                      Extensor hallucis longus
Peroneus longus and brevis                          Flexor hallucis brevis
                                                    Inte rossei
ANTERIOR ANKLE                                      Tibialis anterior
Tibialis anterior
Peroneus tertius                                    M ETATARSAL H EAD
Extensor digitorum longus                           Flexor hallucis brevis
Extensor hallucis longus                            Flexor digitorum brevis
                                                    Adductor hallucis
POSTERIOR ANKLE                                     Flexor hallucis longus
Soleus                                              Abductor digiti minimi
Tibialis posterior                                  Inte rossei
                                                    Tibialis posterior
M EDIAL ANKLE                                       Flexor digitorum longus
Abductor hallucis
Flexor digitorum longus                             DORSAL HALLUX
                                                    Tibialis anterior
LATERAL ANKLE                                       Extensor hallucis longus
Peroneus longus and brevis                          Flexor hallucis brevis
Peroneus tertius
                                                    PLANTAR HALLUX
H EEL                                               Flexor hallucis longus
Soleus                                              Flexor hallucis brevis
Quadratus plantae                                   Tibialis posterior
Abductor hallucis
Tibialis posterior                                  DORSAL LESSER TOE
                                                    Inte rossei
PLANTAR M IDFOOT                                    Extensor digitorum longus
Gastrocne mius
Flexor digitorum longus
PLANTAR LESSER TOE   Flexor digitorum longus
Tibialis posterior
4.0 MUSCLES

3.1 TIB IALIS ANTERIOR



         Figure . Pain pattern referred fro m a TrP at its usual location in tibialis anterior.

Symptoms
 Pain is usually present around the anteromedial aspect of hallux.
 Weakness of ankle dorsiflexion.
 Usually no complaint of nocturnal pain.

Trigger Point Examination
 Most commonly found in the upper one-third of the muscle.
 Transverse palpation will reveal taut bands.
 Digital pressure applied to an active TrP will elicit the referred pain in the ankle or
   foot.

Associated Trigger Points
 Tibialis anterior and peroneus longus are well- matched antagonists for
   stabilisation and balance of the foot and therefore TrP commonly co-exist.
 Extensor digitorum longus and extensor hallucis longus may also develop TrP.

Differential Diagnoses
 Radiculopathy.
 Anterior compartment syndrome.
 Subcutaneous herniation of tibialis anterior.
3.2 PERONEUS LONGUS , BREVIS AND TERTIUS



  Figure . Pain pattern referred fro m TrPs at common ly observed locations in the peroneal muscles

Symptoms
 Patients may complain of „weak ankles‟, and present with a history of inversion
   ankle sprains.
 Pain and tenderness commonly around the lateral malleolus.
 Foot drop may be present if deep peroneal nerve becomes entrapped.

Trigger Point Examination
 Most common TrP is found in peroneus longus.
 Taut bands and TrPs in the peroneals are easily palpable because of their size and
   proximity to the underlying bone.

Associated Trigger Points
 Secondary TrPs commonly develop in extensor digitorum longus
 TrPs in peroneus longus are associated with TrPs in tibia lis posterior

Differential Diagnoses
 MPS of tibialis anterior and the long and short extensors of the hallux and digits.
 Nerve entrapement syndromes of the common, superficial or deep peroneal
    nerves.
 Lateral compartment syndrome.
 Ankle sprain.
 Rupture of the peroneus longus or brevis tendon.
 Painful os peroneum.
3.3 GASTROCNEMIUS



   Figure . Pain pattern referred fro m TrPs at commonly observed locations in the gastrocnemius
                                               muscle.

Symptoms
 TrP1 and TrP2 are very commonly associated with nocturnal calf cramping,
   whereas the others rarely present with this complaint.
 TrP1 are the most common with latent TrPs manifesting primarily as nocturnal
   calf cramps and active TrPs usually result in the pattern of referred pain seen
   above.
 There is rarely weakness or restricted range of motion with gastrocnemius TrPs.

Trigger Point Examination
 If the subcutaneous tissues are lax and the adipose layer relatively thin, the
   gastrocnemius is best examined by pincer palpation.
 It is important to examine the patient with the ankle in a plantarflexed position.

Associated Trigger Points
 Secondary TrPs may develop in the soleus and hamstring muscles.
 TrPs in the medial head of the gastrocnemius are associated with TrPs in tibialis
   posterior and flexor digitorum and hallucis longus.

Differential diagnoses
 „Tennis leg‟ (partial tear of the medial muscle belly).
 Posterior compartment syndrome
 Phlebitis
 Baker‟s cyst
 Achilles tendonitis
 Retrocalcaneal bursitis
 Intermittent claudication and nocturnal pain of the calf muscles.
3.4 SOLEUS



   Figure . Pain pattern referred fro m TrPs at common ly observed locations in the soleus muscle.

Symptoms
 Active TrPs in the soleus are the most common of all TrPs.
 An active TrP1 may result in unbearable pain during heel weight-bearing and can
   cause nocturnal pain in the area.
 Can lead a restriction of ankle dorsiflexion (sagittal plane block), resulting in
   compensations and the development of lower back pain and pathologies
   associated with abnormal foot pronation.
 Active TrP2 and TrP3 can interfere with the soleal musculovenous pump, leading
   to the formation of oedema in the area.

Trigger Point Examination
 It is important that the knee be flexed to slacken the gastrocnemius.
 The palpation of taut bands / TrPs is very difficult in soleus, due in part to the
   overlying gastrocnemius muscle.
 Tenderness associated with the more distal soleal TrPs is commonly present deep
   to the Achilles tendon aponeurosis.
 To aid in the differential diagnosis between a soleal and gastrocnemius TrP,
   extend the knee while maintaining the same ankle position. A gastrocnemius TrP
   will become more sensitive as the knee is extended whereas a soleal TrP will
   remain relatively constant.

Associated Trigger Points
 Commonly occur in gastrocnemius and tibialis posterior.
 Can also occur in flexor digitorum longus and flexor hallucis longus.

Differential Diagnoses
 Rupture of the plantaris muscle belly
 Achilles tendonitis
 Thrombophlebitis
 Baker‟s cyst
 Exercise induced leg pain
 Deep posterior compartment syndrome
 Intermittent claudication and nocturnal pain of the calf muscles
3.5 TIBIALIS POSTERIOR



        Figure . Pain pattern referred fro m a TrP at its usual location in tibialis posterior.

Symptoms
 Patient will usually complain of pain in the sole of the foot and achilles tendon
   during ambulation.
 Symptoms are exacerbated by walking or running on uneven surfaces.

Trigger Point Examination
 TrPs lie deep to the gastrocnemius and soleus and are only palpable indirectly.
 Fig. A illustrates how to examine for the presence of a TrP using a medial
   approach, with the X seen in Fig. B marking the usual location for palpation.
 A posterior approach as seen in Fig. B can also be attempted, with the examiner
   applying digital pressure in an anteromedial direction.


              Figure . Physical examination of a co mmon TrP in tib ialis posterior.

Associated Trigger Points
 Commonly occur in flexor digitorum and flexor hallucis longus.
 The peroneal muscles should also be examined as they often contain active TrPs
   when tibialis posterior is involved.

Differential Diagnoses
 Deep posterior compartment syndrome
 Tibialis posterior tendonitis
 Achilles tendonitis
3.6 EXTENSOR D IGITORUM LONGUS AND EXTENSOR HALLUCIS LONGUS



  Figure . Pain pattern referred fro m TrPs at commonly observed locations in extensor digitoru m
                               longus and extensor hallucis longus.

Symptoms
 Night cramps are common in the presence of active TrPs in the long extensors.
 Pain tends to be dull and bearable
 Muscle weakness (especially in extensor digitorum longus), can lead to mild foot
   drop.
 TrP mediated compression of the deep peroneal nerve can lead to complete foot
   drop, weakness in anterior compartment musculature and paraesthesia.

Trigger Point Examination
 The most effective method of palpating a TrP in extensor digitorum or extensor
   hallucis longus is to use the flat palpation method.
 Palpation of active TrP‟s in either muscle will usually elicit local tenderness and
   referred pain but rarely will it produce a local twitch response.

Associated Trigger Points
 Usually appear secondary to TrPs in tibialis anterior
 If peroneus tertius is affected, chances are that extensor digitorum also harbours
   TrPs
 Are also associated with TrPs in the peroneus longus and brevis as they all
   perform a similar function.

Differential Diagnoses
 MPS of peroneus longus, brevis and tertius, extensor digitorum brevis, tibialis
    anterior and extensor hallucis brevis.
3.7 FLEXOR D IGITORUM LONGUS AND FLEXOR H ALLUCIS LONGUS




   Figure . Pain pattern referred fro m TrPs in co mmon ly obs erved locations in the long flexo rs.
Symptoms
 Common symptoms are pain when walking or weight-bearing that is consistent
   with that in Fig. .

Trigger Point Examination
 As with tibialis posterior, palpation of TrPs in the long flexors must be made
   through gastrocnemius and sloeus.
 Fig. A indicates how to palpate a TrP in flexor digitorum longus whereas Fig. B
   illustrates the technique for flexor hallucis longus.

Associated Trigger Points
 Tibialis posterior and the short and long extensors have harbour assoc iated TrPs.

Differential Diagnoses
 MPS of tibialis posterior, adductor hallucis and interossei.
 Exercise induced leg pain.
3.8 EXTENSOR D IGITORUM BREVIS AND EXTENSOR HALLUCIS BREVIS



  Figure . Pain pattern referred fro m TrPs at commonly obseved locations in the short extensors.

Symptoms
 Tenderness from TrPs tends to project locally.
 Have been reported to cause cramping in foot.

Trigger Point Examination
 Even though these muscles are located superficially, overlying tendons may
   complicate the palpation of TrPs.
 Palpation will usually result in exquisite local tenderness and a jump response but
   will rarely elicit a local twitch response.

Associated Trigger Points
 Commonly associated with TrPs in extensor digitorum and extensor hallucis
   longus.
3.9 ABDUCTOR HALLUCIS



   Figure . Pain pattern referred fro m TrPs at commonly observed locations in abductor hallucis.

Symptoms
 Patients may complain of unbearably sore feet that have not responded or have
   been aggravated by orthotic therapy.
 A deep and aching pain may also be present during rest.

Trigger Point Examination
 A relatively thick muscle, making access to deeper fibres difficult.
 Palpation will usually result in exquisite local tenderness and a jump response and
   will rarely elicit a local twitch response,

Associated Trigger Points
 Usually involve the surrounding deep intrinsic muscles.
3.10 ABDUCTOR D IGITI M INIMI AND FLEXOR D IGITORUM BREVIS



 Figure . Pain pattern referred fro m TrPs in co mmon ly observed locations in adbuctor digiti minimi
                                     and flexor dig itorum brevis.

Symptoms
 Patients will usually complain of unbearably sore feet that have not responded or
   have been aggravated by orthotic therapy
 A deep and aching pain may be present during rest.

Trigger Point Examination
 Abductor digiti minimi is best palpated via the pincer technique along the lateral
   border of the foot.
 Flexor digitorum brevis lies deep to the plantar aponeurosis, making palpation
   very difficult
 It may benefit to plantarflex the metatarsophalangeal joints to slacken the plantar
   aponeurosis prior to palpation.

Associated Trigger Points
 TrPs in abductor digiti minimi tends to manifest independantly of other muscles
   and are usually believed to be the result of tight footwear.
 TrPs in flexor digitorum brevis are generally associated with TrPs in the long
   flexors.
3.11 Q UADRATUS PLANTAE



        Figure . Pain pattern referred fro m a TrP at its usual location in quadratus plantae.

Symptoms
 Patients may present with sensations of numbness, swelling or fullness and pain
   on in the heel region.

Trigger Point Examination
 Quadratus plantae is a deep intrinsic muscle requiring the need for deep palpation.
 It may be useful to slightly dorsiflex the metatarsophalangeal joints, as illustrated
   in Fig. .
 Focal tenderness is usually present although the presence of a taut band will rarely
   be palpated.

Associated Trigger Points
 Usually, several deep intrinsic muscles are involved simultaneously.
3.12 ADDUCTOR HALLUCIS AND FLEXOR HALLUCIS BREVIS



 Figure . Pain pattern referred fro m TrPs at commonly observed locations in adductor hallucis and
                                       flexo r hallucis brevis.

Symptoms
 Patients may complain of pain in the forefoot when walking as well as numbness
   and a feeling of fullness in the area.

Trigger Point Examination
 To examine adductor hallucis (Fig. A), stretch and gently abduct the first
   metatarsophalangeal joint.
 TrP tenderness is usually palpatable although taut bands are not.
 To examine flexor hallucis brevis (Fig. B), palpate along the medial border of the
   foot, to avoid the thick plantar fascia.
 It is important not to mistake the tendon of abductor hallucis for a taut band.

Associated Trigger Points
 Usually, several deep intrinsic muscles are involved simultaneously.
3.13 INTEROSSEI



         Figure . Pain pattern referred fro m a TrP at its usual location in the interossei.

Symptoms
 Patient may complain of tightness, numbness or pain in the dorsal and/or plantar
   aspect of the second metatarsophalangeal joint and digit.
 Active or latent TrPs commonly occur in the presence of digital deformities.

Trigger Point Examination
 Dorsal and plantar interossei are considered as a functional unit because of the
   impossibility of palpating each one individually.
 Examination of the interossei is recommended via the technique sho wn in Fig. .
 Taut bands may be palpated against the adjacent metatarsal.

Associated Trigger Points
 Usually, several deep intrinsic muscles are involved simultaneously.
5.0 CRITERIA FOR DIAGNOSIS

       In order to accurately diagnose MPS, all five of the major criteria listed below
       must be present (15).
              1. Regional pain complaint.
              2. Taut band palpable in an accessible muscle.
              3. Exquisite spot of tenderness in the taut band.
              4. Pain complaint or altered sensation in the expected distribution of
                   referred pain from the tender spot.
              5. Some restricted range of motion, when measurable.

       In addition, at least one of the following minor criteria must met (15).
               1. Reproduction of clinical pain complaint, or altered sensation, by
                   pressure on the tender spot.
               2. Local twitch response by transverse snapping palpation of, or
                   needle insertion into, the taut band.
               3. Pain alleviation by stretching the involved muscle or injecting the
                   tender spot in it.


6.0 IMAGING TECHNIQUES

       The only modality to have any reported success in the detection of TrPs is
       thermographic imaging. Thermography detects the distribution of body
       surface heat and a high correlation exists between areas of higher thermal
       emission and the location of trigger points as well as their classic zones of
       referred pain (7). TrPs appear as discrete foci of increased thermal emission
       with the zones of referred pain marked by an area of diffuse hyperthermia
       (7,8). These thermal changes are used as evidence to support the presence of
       both local and peripheral, sympathetic autonomic abnormalities (8).


DIFFERENTIAL DIAGNOSES
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Many patients with MPS are living with unnecessary pain and discomfort due to
misdiagnosis of their condition. MPS is often confused with fibromyalgia, and even
though the two can co-exist (19), they each have seperate and distinct clinical
manifestations. The table below, adapted from Adams and Sim (1998) and Schneider
(1995) lists the principle differentiating characteristics of the two conditions (17,20).
TREATMENT
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      As podiatrists, our primary role in the management of MPS is to address any
      biomechanical abnormalities that could have led to the formation and
      perpetuation of TrPs. Although we have no formal training in the area, many
      of the physical therapy modalities listed below could be easily adopted into
      our treatment repertoire. Conversely, we could refer to a physiotherapist or
      myotherapist with more experience in the area of muscle manipulation.


1.0 ORTHOSES

      From a podiatric perspective, many of the aches and pains that are
      successfully treated with orthoses could have a TrP related component. The
      only research uncovered relating to the treatment of MPS with orthoses was
      conducted by Saggini et al in 1996. They examined twelve patients with a
      limb length discrepancy and unilateral TrPs in peroneus longus. The subjects
      were assigned either a heel lift to correct the discrepancy or functional foot
      orthoses. The heel lift intervention group reported a moderate reduction in
      symptomolgy after 7 to 14 days with no further improvement, whereas the
      orthoses group had a significant reduction in pain after 7 days and complete
      resolution of pain and the active TrPs at 30 days (2).

      There is also anecdotal evidence to implicate TrPs in the failure of orthotic
      intervention. For example, an individual suffering from heel pain can develop
      an antalgic gait pattern and as a result of the abnormal muscular activity, form
      a TrP in the soleus muscle. Upon correction of the offending biomechanical
      anomalies with orthoses, symptoms of heel pain may persist due to referred
      pain from the soleal TrP.


2.0 PHYSICAL THERAPY

      Many physical therapy modalities can be used in the treatment of MPS. The
      one most commonly reported in the literature is the spray and stretch
      technique. It involves the use of a vapocoolant spray as a distraction to block
      the reflex spasm and pain while the muscle is passively stretched so that it
      achieves its normal resting length (3,10). The use of an ice-pack over the area
      of referred pain has been shown to be effective in reducing pain.

      Heat therapy via ultrasound or a moist heat-pack is often used to relax the
      surrounding muscles and help reduce tension in a TrP, especially prior to a
      myofascial release of the affected area (10). The use of heat and massage is
      effective on its own or in combination with the spray and stretch technique.


3.0 TRIGGER POINT INJECTION
      Injection therapy can be performed „dry‟ through acupuncture or „wet‟ by
      infiltrating the area with either saline or a local anaesthetic. Needling is
      viewed as the definitive treatment for MPS, and is particularly indicated in the
      20%-30% of cases that are unresponsive to standard treatment (12). „Wet‟
      injections are associated with significantly reduced post injection soreness
      when compared to acupuncture (23).


CONCLUSION
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REFERENCES
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