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== Search Strategy ==
== Definition/Description ==


<u>Search Engines</u>: Pubmed, Web of knowledge.  
[[Image:Os trigonum 1.png|thumb|right|292x246px|Sagittal T1-weighted MR image in plantar flexion showing the “nutcracker-phenomenon”. The os trigonum together with surrounding soft tissues are wedged between talus, calcaneus and tibia.]]


Google Scholar and Google books are also practical.
The Os Trigonum Syndrome refers to pain posterior of the ankle and reduced plantarflexion caused by “the nutcracker-phenomenon”. When an os trigonum is present, this accessory ossicle together with surrounding soft tissues can become wedged between the tibia, talus and calcaneus. This can lead to inflammation of the involved structures. <ref name="p3">Physioroom. Os Trigonum Syndrome in Depth. http://www.physioroom.com/injuries/ankle_and_foot/os_trigonum_full.php (accessed 21 November 2011).</ref><ref name="p0">J. A. Russell, D.W. Kruse, Y.I. Koutedakis, I. M. Mcewan, M. A. Wyon Pathoanatomy of Posterior Ankle Impingement in Ballet Dancers. Clinical Anatomy 2010; 23:613–621</ref><ref name="p8">M. Nyska, G. Mann Unstable Ankle. Leeds: Human Kinetics Publishers, 2002.</ref>


&nbsp;  
The os trigonum syndrome can also be named the symptomatic os trigonum, the talar compression syndrome or posterior tibial talar impingement syndrome.<ref name="p5">D. Karasick, M. E. Schweitzer The OsTrigonum Syndrome: Imaging Features. AJR 1996; 166:125-129</ref>


<u>Key Words</u>: os trigonum syndrome (AND treatment NOT surgery,&nbsp;AND physical therapy), posterior ankle impingement, ballet dancers
== Clinically Relevant Anatomy  ==


== Definition/Description  ==
Embryologically, the body of the talus and the posterior talar process are separate ossification centers. Between the 7th and the 13th year of life, the posterior talar process appears as a separate ossicle: the os trigonum. Normally, within a year of its appearance, it fuses with the talus, but about 7% of the adult population has still this os trigonum. It can be present unilaterally or bilaterally, with smooth or serrated margins. The os trigonum is usually seen as an individual bone, but can also exist of two or more pieces. It is less than 1cm in size, but this can vary. <ref name="p8" /><ref name="p1">J. Zeichen, E. Schratt, U. Bosch, H. Thermann Das Os-trigonum-syndrom. Unfallchirurg 1999; 102:320±323</ref> <ref name="p5" />


add text here <br>
[[Image:Os trigonum 6.png|thumb|left|Superior view of talus]]


== Clinically Relevant Anatomy  ==
The os trigonum is usually triangular with an anterior, inferior and posterior surface. The anterior surface connects with the lateral tubercle by cartilaginous synchondrosis. The inferior side may articulate with the calcaneus. The posterior surface is nonarticular, but is used as a point of attachment for capsuloligamentous structures. The os trigonum may also be round or oval. <ref name="p5" />


The coccyx, also known as the tailbone, is a small triangular bone that is usually formed by fusion of the four rudimentary coccygeal vertebrae, although in some people there may be one less or one more. The coccygeal vertebra 1 (Co1) may remain separate from the fused group, but with increasing age Co1 often fuses with the sacrum and the remaining coccygeal vertebrae usually fuse to form a single bone. (level of evidence D) <br>The forward movement of coccyx is performed actively by the M. levator ani, and the backward movement of coccyx is passively caused by relaxation of these muscles. The coccyx also provides the site of attachment for the M. gluteus maximus as well as the M. levator ani, which is responsible for voluntary control of bladder and bowel. (level of evidence B) The coccyx does not participate with the other vertebrae in support of body weight when standing, however when sitting it may flex anteriorly, indicating that it’s receiving some weight. ( level of evidence D)i
The flexor hallucis longus tendon is situated medial to the os trigonum, in the sulcus between the medial and lateral tubercle.<ref name="p5" /><br>&nbsp;
 
The coccyx is part of the sacrococcygeal joint, an cartilaginous joint with an IV disc. Fibrocartilage and ligaments join the apex of the sacrum to the base of the coccyx. The anterior and posterior sacrococcygeal ligaments are long strands that reinforce the joint. (level of evidence D) <br>The coccyx is also attached with the margin of the anus by the anococcygeal ligament. (level of evidence D)iii<br><br>


== Epidemiology /Etiology  ==
== Epidemiology /Etiology  ==


Fracture of the coccyx often arise after a fall on the buttock, most prevalent a fall of the stairs on the tailbone, or by an impact directly applied. (level of evidence D) An especially difficult childbirth occasionally injures the mother’s coccyx. ( level of evidence D) <br><br>
There are three mechanisms for the development of an os trigonum:


== Characteristics/Clinical Presentation  ==
#fusion failure of an ossification center
#fracture of the posterior margin of the tibia
#fracture of the posterior process of the talus.<ref name="p9">W. Albisetti, M. Ometti, V. Pascale, O. De Bartolomeo Clinical Evaluation and Treatment of Posterior Impingement in Dancers. American Journal of Physical Medicine and Rehabilitation 2008; 88:349–354.</ref><br>


1. GENERAL SYMPTOMS<br>General symptoms that appear are (level of evidence D)iv,vii,viii&nbsp;:<br>• Pain that increases in severity when sitting or getting up from a chair<br>• Provoked pain over the tailbone<br>• Bruising or swelling in the tailbone area<br>• Bowel movements and straining are often painful<br>• There are no neurological signs
The presence of an os trigonum isn’t sufficient to create the syndrome. It must be combined with a traumatic event. <ref name="p8" />  


The os trigonum syndrome can be caused by overuse or trauma. When it’s due to overuse, it’s mostly found by ballet dancers and runners. The forceful plantar flexion that happens during an “en pointe” or “demi-pointe” position, as well as by running downhill, produces compression on the posterior aspect of the ankle joint. In cause of a trauma, the os trigonum can be displaced by forced plantarflexion. <ref name="p8" />


Soft tissue structures, including the ankle joint capsule and surrounding ligaments, may react by forming a hypertrophic mass. <ref name="p5" /><ref name="p0" />


An important number of people suffer from long lasting pains over the coccyx following trauma (with or without fracture of the coccyx), better known as cocydynia.(level of evidence D)
== Characteristics/Clinical Presentation  ==


<br>2. CLINICAL PRESENTATION IN PATIENTS WITH SPINAL CORD INJURY<br>Patients with SCI, suffering from painful symptoms in the low back, gluteal, hip and thigh region, have coccyx fracture with a frequency of 34,6%. Patients who had coccyx fracture have higher pain scores when compared with those who don’t have any fracture, however the difference is only statistical significant regarding Sensory Pain Index (SPI) and total McGill scores.( level of evidence C)
A load-dependent, persistent pain between the Achilles tendon and the peroneal tendons is the first indicator of the syndrome. Stiffness, weakness and swelling can also be observed in this zone. The second main symptom is a decrease in plantarflexion compared with the unaffected ankle. In some cases the bony prominence may be palpable.<ref name="p1" /><ref name="p9" /><ref name="p3" /><ref name="p7">T. H. Berquist Imaging of the Foot and Ankle. 2010</ref>


<br>
Eversion or inversion movements may cause discomfort. Pain at the posterior aspect of the ankle will be experienced by plantarflexion of the foot or dorsiflexion of the great toe.<ref name="p5" /><ref name="p2">D. R. Tollafield, L. M. Merriman Clinical skills in treating the foot. London: Churchill Livingstone, 1997.</ref>  


== Differential Diagnosis  ==
== Differential Diagnosis  ==


<br>
The following diagnosis must be considered:


<br>
*Tendinitis flexor hallucis longus<ref name="p8" />;*Tarsal tunnel syndrome<ref name="p8" />;*Subtalar pathology<ref name="p8" />;*Achilles tendinopathy<ref name="p1" />;*Peroneal tendinopathy<ref name="p1" />;*Achilles tendon bursitis<ref name="p1" />;*Osteochondritis dissecans of the talus. <ref name="p1" />


== Diagnostic Procedures  ==
== Diagnostic Procedures  ==


1. MEDICAL DIAGNOSIS<br>A plain radiography or MRI is necessary to confirm the diagnose of a coccyx fracture. (level of evidence D)
*Lateral X-ray<ref name="p2" />, possibly weight-bearing, with the foot in full plantarflexion.<ref name="p9" />
*CT-scan<ref name="p2" /><ref name="p1" />
*MRI is the preferable technique<ref name="p5" /> for establishing the presence<ref name="p6">D. B. Thordarson Foot and Ankle. Philadelphia: Lippincott Williams &amp; Wilkins, 2004.</ref> and the size of the ossicle<ref name="p2" />,&nbsp;coexisting pathologies and soft tissue and bone damage.<ref name="p9" /> Flexion/extension MRI gives information about the mobility of the os trigonum.<ref name="p5" />
*Technetium bone scan<ref name="p9" /><ref name="p1" /><ref name="p6" /> shows increased uptake in the region of the os trigonum.


<br>2. CLINICAL DIAGNOSIS<br>The diagnose is made after rectal examination. (level of evidence D)iv By passing the finger up the rectum and then pressing the bone backwards and forward, the unnatural degree of motion will then be felt. Related to the age and sex of the patient must be remembered that in the female this bone naturally possesses more motion than in the male, and that in youth a degree of motion, that does not exist at a later period of life, is present, allowing the ossification being less complete. However the free motion of the bone is taken as a symptom. (level of evidence D)
{|
|-
| [[Image:Os trigonum 4.png|thumb|left|222x299px|lateral x-ray of foot showing os trigonum]]
| [[Image:Os trigonum 3.png|thumb|left|250x252px|Technetium bone scan]]
|}


<br>
== Examination&nbsp;  ==


== Outcome Measures ==
On posterolateral palpation, between the Achilles tendon and peroneal tendons, pain and swelling may be noticed.<ref name="p1" /><ref name="p7" /><ref name="p8" />


add links to outcome measures here (also see [[Outcome Measures|Outcome Measures Database]]) 
The passive forced plantarflexion test: It should be executed with repetitive quick and passive hyperplantarflexion movements in a neutral position, possibly with exo- or endorotation movement on the point of maximal plantarflexion. Thereby grinds the ossicle between tibia and calcaneus.<ref name="p8" /><br>


== Examination  ==
== Medical Management    ==


add text here related to physical examination and assessment<br>  
Nonsteroidal anti-inflammatory medication or corticosteroid injections are used to reduce soft tissue inflammation.<ref name="p2" /><ref name="p3" /><ref name="p8" /><br>In case of fracture, a below-knee cast is used for 4-6weeks.<ref name="p2" />  


== Medical Management <br> ==
If symptoms persist, surgery is applied. (high evidence, all studies mention good results.)<br>This involves the removal of the os trigonum. Postoperatively we apply a plaster cast for 5days. Hereafter physiotherapy is started for 4-8 weeks. Afterwards full sports activities can be resumed. It will take up to 6 months until full recovery.<ref name="p3" /><ref name="p8" /><br>  


1. COCCYGEOPLASTY<br>By applying the novel techniques that are used in vertebroplasty and sacroplasty, coccygeoplasty is introduced as a new percutaneous treatment modality for fractures of the coccyx. This procedure can be helpful for patients with refractory pain resulting from a fracture of the coccyx and can be performed quickly and safely with high-resolution c-arm fluoroscopy. The coccygeal fracture treated with an injection of polymethylmethacrylate cement can provide early symptom relief. Although the promising results, an experience with a larger patient population is warranted. ( level of evidence C)
== Physical Therapy Management    ==


<br>2. COCCYGECTOMY<br>Literature reports suggest that coccygectomy, partial or total removal of the coccyx, has been beneficial with success rates as high as 60-91%. However, coccygectomy is a more invasive procedure, with a common complication rate as high as 22%, and is usually associated with perineal contamination of the wound. Other complications could include persistent bleeding from the hemorrhoidal venous complex of the rectum. (level of evidence C)ix
Rest, ice, massage and ultrasound treatment will reduce inflammation.<ref name="p1" /><ref name="p2" /><ref name="p8" />  


<br>
Isometric and eccentric exercises to strengthen and stretch the lower-leg muscles are used in a physiotherapeutic treatment.<ref name="p9" />  


== Physical Therapy Management <br> ==
Also exercises to improve deep muscle action during plantarflexion are designated. The deep muscles of the lower leg, such as tibialis posterior, flexor digitorum longus, flexor hallucis longus and the peroneals are the opposites of the M.gastrocnemius. By using the deep muscles, the talus is shifted forward during plantarflexion, what will reduce the impact of the os trigonum on the posterior tibia, contrary to using the M.gastrocnemius, which results in lifting the calcaneus and compression of the os trigonum.<ref name="p9" />  


add text here <br>  
<u>[[Image:Os trigonum 5.png|left|800x216px]]</u>  


== Key Research  ==
<u>Fig. 5</u>: Strengthening of the deep muscles. Performing demipointe (2) and en pointe (3) while holding the calcaneus in place with the hands. Knee flexion at 90° to prevent contraction of the M.gastrocnemius.<ref name="p9" />


add links and reviews of high quality evidence here (case studies should be added on new pages using the [[Template:Case Study|case study template]])<br>  
Also, proprioceptive exercises on a tilt board are applied to correct malalignments of the lower limb.<ref name="p9" /><br>All of these exercises were found in only one study of 11 dancers with a posterior ankle impingement including 6 cases with an os trigonum. Nine of them had good results with these exercises, the other two ones underwent surgical excision.<ref name="p9" />  


== Resources <br> ==
According to a recent systematic review, physiotherapeutic interventions have positive effects in several domains, including pain, ROM, and functional status, having a potential role in the treatment of ballet dancers after injuries. However, the small evidence base and methodological limitation of this review calls for a cautious approach while considering the physiotherapy options for managing injuries in a ballet dancer.<ref>Skwiot M, Śliwiński Z, Żurawski A, Śliwiński G. [https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0253437 Effectiveness of physiotherapy interventions for injury in ballet dancers: A systematic review]. PLoS one. 2021 Jun 24;16(6):e0253437.</ref>  


add appropriate resources here <br>
== Clinical Bottom Line  ==
add text here <br>
== Recent Related Research (from [http://www.ncbi.nlm.nih.gov/pubmed/ Pubmed])  ==
see tutorial on [[Adding PubMed Feed|Adding PubMed Feed]]
<div class="researchbox">
<rss>Feed goes here!!|charset=UTF-8|short|max=10</rss>
</div>
== References  ==
== References  ==


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<references />  
<references />  


[[Category:Vrije_Universiteit_Brussel_Project|Template:VUB]]
[[Category:Vrije_Universiteit_Brussel_Project]]
 
[[Category:Primary Contact]]  
MOORE K.L., DALLEY A.F., AGUR A.M.R., Clinically oriented anatomy: chapter 3: Pelvis and perineum, Wolters Kluwer health, sixth edition, 2010, pag. 451-452, level of evidence D<br> YU-TSAI T., LI-WEN T., CHENG-HSIU L., SHIH-WEI C., The influence of human coccyx in body weight shifting, medicine and science in sport and exercise, 2011, Volume 43, Number 5, pag. 494-496, level of evidence B<br> MOORE K.L., DALLEY A.F., AGUR A.M.R., Clinically oriented anatomy: chapter 3: Pelvis and perineum, Wolters Kluwer health, sixth edition, 2010, pag. 332, level of evidence D<br> HAARMAN H.J.Th.M., Klinische traumatologie, Elsevier gezondheidszorg, 2006, pag. 117, level of evidence D<br> MOORE K.L., DALLEY A.F., AGUR A.M.R., Clinically oriented anatomy: chapter 3: Pelvis and perineum, Wolters Kluwer health, sixth edition, 2010, pag. 461, level of evidence D<br> TEKIN L. et al., Coccyx fracture in patients with spinal cord injury, European journal of physical and rehabilitation medicine, March 2010, Volume 46, Number 1, pag. 43-46, level of evidence C<br> RAISSAKI M.T.,Fracture dislocation of the sacro-coccygeal joint: MRI evaluation, Pediatric radiology, March 1999, pag. 642-643, level of evidence D<br> LONSDALE E.F., A practical treatise on fractures, Walton and Mitchell printers, 1838, pag. 269-270, level of evidence D<br> MIYAMOTO K. et al., Exposure to pulsed low intensity ultrasound stimulates extracellular matrix metabolism of bovine intervertebral dosc cells cultured in alginate beads, Spine, November 2005, level of evidence B<br> EBNEZAR J., Essentials of orthopaedics for physiotherapist, Jaypee, 2003, pag. 174, level of evidence D<br> DEAN L.M. et al., Coccygeoplasty : treatment for fractures of the coccyx, J. Vasc. Interv. Radiol, 2006, pag. 909-912, level of evidence C<br> COOPER G., HERRERA J.E., Manual of musculoskeletal medicine, Wolters kluwer, Lippincott Williams &amp; Wilkins, 2008, pag. 144, level of evidence D
[[Category:Syndromes]]
[[Category:Sports Medicine]]

Latest revision as of 18:29, 16 July 2021

Definition/Description[edit | edit source]

Sagittal T1-weighted MR image in plantar flexion showing the “nutcracker-phenomenon”. The os trigonum together with surrounding soft tissues are wedged between talus, calcaneus and tibia.

The Os Trigonum Syndrome refers to pain posterior of the ankle and reduced plantarflexion caused by “the nutcracker-phenomenon”. When an os trigonum is present, this accessory ossicle together with surrounding soft tissues can become wedged between the tibia, talus and calcaneus. This can lead to inflammation of the involved structures. [1][2][3]

The os trigonum syndrome can also be named the symptomatic os trigonum, the talar compression syndrome or posterior tibial talar impingement syndrome.[4]

Clinically Relevant Anatomy[edit | edit source]

Embryologically, the body of the talus and the posterior talar process are separate ossification centers. Between the 7th and the 13th year of life, the posterior talar process appears as a separate ossicle: the os trigonum. Normally, within a year of its appearance, it fuses with the talus, but about 7% of the adult population has still this os trigonum. It can be present unilaterally or bilaterally, with smooth or serrated margins. The os trigonum is usually seen as an individual bone, but can also exist of two or more pieces. It is less than 1cm in size, but this can vary. [3][5] [4]

Superior view of talus

The os trigonum is usually triangular with an anterior, inferior and posterior surface. The anterior surface connects with the lateral tubercle by cartilaginous synchondrosis. The inferior side may articulate with the calcaneus. The posterior surface is nonarticular, but is used as a point of attachment for capsuloligamentous structures. The os trigonum may also be round or oval. [4]

The flexor hallucis longus tendon is situated medial to the os trigonum, in the sulcus between the medial and lateral tubercle.[4]
 

Epidemiology /Etiology[edit | edit source]

There are three mechanisms for the development of an os trigonum:

  1. fusion failure of an ossification center
  2. fracture of the posterior margin of the tibia
  3. fracture of the posterior process of the talus.[6]

The presence of an os trigonum isn’t sufficient to create the syndrome. It must be combined with a traumatic event. [3]

The os trigonum syndrome can be caused by overuse or trauma. When it’s due to overuse, it’s mostly found by ballet dancers and runners. The forceful plantar flexion that happens during an “en pointe” or “demi-pointe” position, as well as by running downhill, produces compression on the posterior aspect of the ankle joint. In cause of a trauma, the os trigonum can be displaced by forced plantarflexion. [3]

Soft tissue structures, including the ankle joint capsule and surrounding ligaments, may react by forming a hypertrophic mass. [4][2]

Characteristics/Clinical Presentation[edit | edit source]

A load-dependent, persistent pain between the Achilles tendon and the peroneal tendons is the first indicator of the syndrome. Stiffness, weakness and swelling can also be observed in this zone. The second main symptom is a decrease in plantarflexion compared with the unaffected ankle. In some cases the bony prominence may be palpable.[5][6][1][7]

Eversion or inversion movements may cause discomfort. Pain at the posterior aspect of the ankle will be experienced by plantarflexion of the foot or dorsiflexion of the great toe.[4][8]

Differential Diagnosis[edit | edit source]

The following diagnosis must be considered:

  • Tendinitis flexor hallucis longus[3];*Tarsal tunnel syndrome[3];*Subtalar pathology[3];*Achilles tendinopathy[5];*Peroneal tendinopathy[5];*Achilles tendon bursitis[5];*Osteochondritis dissecans of the talus. [5]

Diagnostic Procedures[edit | edit source]

  • Lateral X-ray[8], possibly weight-bearing, with the foot in full plantarflexion.[6]
  • CT-scan[8][5]
  • MRI is the preferable technique[4] for establishing the presence[9] and the size of the ossicle[8], coexisting pathologies and soft tissue and bone damage.[6] Flexion/extension MRI gives information about the mobility of the os trigonum.[4]
  • Technetium bone scan[6][5][9] shows increased uptake in the region of the os trigonum.
lateral x-ray of foot showing os trigonum
Technetium bone scan

Examination [edit | edit source]

On posterolateral palpation, between the Achilles tendon and peroneal tendons, pain and swelling may be noticed.[5][7][3]

The passive forced plantarflexion test: It should be executed with repetitive quick and passive hyperplantarflexion movements in a neutral position, possibly with exo- or endorotation movement on the point of maximal plantarflexion. Thereby grinds the ossicle between tibia and calcaneus.[3]

Medical Management[edit | edit source]

Nonsteroidal anti-inflammatory medication or corticosteroid injections are used to reduce soft tissue inflammation.[8][1][3]
In case of fracture, a below-knee cast is used for 4-6weeks.[8]

If symptoms persist, surgery is applied. (high evidence, all studies mention good results.)
This involves the removal of the os trigonum. Postoperatively we apply a plaster cast for 5days. Hereafter physiotherapy is started for 4-8 weeks. Afterwards full sports activities can be resumed. It will take up to 6 months until full recovery.[1][3]

Physical Therapy Management[edit | edit source]

Rest, ice, massage and ultrasound treatment will reduce inflammation.[5][8][3]

Isometric and eccentric exercises to strengthen and stretch the lower-leg muscles are used in a physiotherapeutic treatment.[6]

Also exercises to improve deep muscle action during plantarflexion are designated. The deep muscles of the lower leg, such as tibialis posterior, flexor digitorum longus, flexor hallucis longus and the peroneals are the opposites of the M.gastrocnemius. By using the deep muscles, the talus is shifted forward during plantarflexion, what will reduce the impact of the os trigonum on the posterior tibia, contrary to using the M.gastrocnemius, which results in lifting the calcaneus and compression of the os trigonum.[6]

Os trigonum 5.png

Fig. 5: Strengthening of the deep muscles. Performing demipointe (2) and en pointe (3) while holding the calcaneus in place with the hands. Knee flexion at 90° to prevent contraction of the M.gastrocnemius.[6]

Also, proprioceptive exercises on a tilt board are applied to correct malalignments of the lower limb.[6]
All of these exercises were found in only one study of 11 dancers with a posterior ankle impingement including 6 cases with an os trigonum. Nine of them had good results with these exercises, the other two ones underwent surgical excision.[6]

According to a recent systematic review, physiotherapeutic interventions have positive effects in several domains, including pain, ROM, and functional status, having a potential role in the treatment of ballet dancers after injuries. However, the small evidence base and methodological limitation of this review calls for a cautious approach while considering the physiotherapy options for managing injuries in a ballet dancer.[10]

References[edit | edit source]

see adding references tutorial.

  1. 1.0 1.1 1.2 1.3 Physioroom. Os Trigonum Syndrome in Depth. http://www.physioroom.com/injuries/ankle_and_foot/os_trigonum_full.php (accessed 21 November 2011).
  2. 2.0 2.1 J. A. Russell, D.W. Kruse, Y.I. Koutedakis, I. M. Mcewan, M. A. Wyon Pathoanatomy of Posterior Ankle Impingement in Ballet Dancers. Clinical Anatomy 2010; 23:613–621
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 M. Nyska, G. Mann Unstable Ankle. Leeds: Human Kinetics Publishers, 2002.
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 D. Karasick, M. E. Schweitzer The OsTrigonum Syndrome: Imaging Features. AJR 1996; 166:125-129
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 J. Zeichen, E. Schratt, U. Bosch, H. Thermann Das Os-trigonum-syndrom. Unfallchirurg 1999; 102:320±323
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 W. Albisetti, M. Ometti, V. Pascale, O. De Bartolomeo Clinical Evaluation and Treatment of Posterior Impingement in Dancers. American Journal of Physical Medicine and Rehabilitation 2008; 88:349–354.
  7. 7.0 7.1 T. H. Berquist Imaging of the Foot and Ankle. 2010
  8. 8.0 8.1 8.2 8.3 8.4 8.5 8.6 D. R. Tollafield, L. M. Merriman Clinical skills in treating the foot. London: Churchill Livingstone, 1997.
  9. 9.0 9.1 D. B. Thordarson Foot and Ankle. Philadelphia: Lippincott Williams & Wilkins, 2004.
  10. Skwiot M, Śliwiński Z, Żurawski A, Śliwiński G. Effectiveness of physiotherapy interventions for injury in ballet dancers: A systematic review. PLoS one. 2021 Jun 24;16(6):e0253437.