Symptomatic Accessory Ossicles: A Pictorial Review

Transcription

1 Symptomatic Accessory Ossicles: A Pictorial Review Poster No.: C-1827 Congress: ECR 2016 Type: Educational Exhibit Authors: J. Saraiva, C. Bilreiro, L. Silva, C. Carneiro, B. M. Q. Santos, M. O. E. Castro; Portimão/PT Keywords: MR, CT, Conventional radiography, Musculoskeletal system, Musculoskeletal bone, Normal variants, Education and training DOI: /ecr2016/C-1827 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 48

2 Learning objectives To learn how accessory ossicles can become symptomatic and what are their spectrum of appearances and clinical manifestations. Page 2 of 48

3 Background Accessory ossicles are generally regarded as clinically insignificant anatomic variations, when in fact they can become symptomatic. They can suffer traumatic events (e.g. acute fractures, stress fractures, pseudarthrosis). Neoplastic and osteoarthritic disorders are also reported, as well as inflammatory and degenerative conditions. Page 3 of 48

4 Findings and procedure details This presentation reviews the reported symptomatic accessory ossicles and suggests guidelines on their imaging diagnosis while attempting to provide some clinical-radiological correlation. We provide our own examples of the more commonly symptomatic ossicles: 1. os odontoideum; 2. Accessory Navicular; 3. os acromiale; 4. os subfibulare; 5. os trigonum; 6. Carpal Boss; 7. os calcaneus secundarius; 8. os peroneum; 9. os intermetatarseum. Page 4 of 48

5 Fig. 1: Locations of the more common symptomatic ossicles: 1. os odontoideum; 2. Accessory Navicular; 3. os acromiale; 4. os subfibulare; 5. os trigonum; 6. Carpal Boss; 7. os calcaneus secundarius; 8. os peroneum; 9. os intermetatarseum. References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT 1. Os Odontoideum Page 5 of 48

6 Location Unfused dens axis fragment, adjacent to C2 vertebral body. General Incidence Symptoms Atlantoaxial instability (anterior or posterior atlantoaxial subluxation) is common. May lead to substantial spinal canal narrowing and spinal cord compression at the level of C1. Causes / Risk Factors Imaging MRI narrowing... Differential Diagnosis Assymptomatic os odontoideum : well corticated convex of upper margin of atlas body(arrowhead). Hypertrophic and rounded anterior atlas arch(arrow). -Type 2 odontoid Fracture: flattened, sharp, uncorticated upper margin of atlas body(arrowhead). Normal half moonshaped anterior atlas arch. Notes Fig. 12: os odontoideum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 6 of 48

7 Fig. 13: os odontoideum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 7 of 48

8 Fig. 10: os odontoideum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 8 of 48

9 Fig. 11: os odontoideum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT 2. Accessory navicular Location Adjacent to the medial side of the navicular bone. General Incidence ~10% (range 4-21%) of the population Symptoms medial side foot pain (os naviculare syndrome) Causes / Risk Factors Pain is worsened by walking, running and other weight-bearing activities. If large, it can protrude outwards and cause friction against footwear. Imaging Page 9 of 48

10 A medial navicular eminence is best visualised on the lateral-oblique view. Symptomatic accessory navicular bones can appear bright on bone scan and bone marrow oedema is best seen on MRI. Differential Diagnosis Notes Acute pain can be managed with corticosteroid injection and immobilisation. In refractory cases surgical management can be an option. Page 10 of 48

11 Fig. 7: Accessory navicular References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 11 of 48

12 Fig. 9: Accessory navicular References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 12 of 48

13 Fig. 8: Accessory navicular References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT 3. Os Acromiale Location Unfused accessory center of ossification of the acromion of the scapula General Incidence 1-15% Symptoms Shoulder pain Causes / Risk Factors It may cause shoulder impingement, rotator cuff tear or degenerative AC joint disease Imaging On conventional radiography is best seen on axillary views. On MRI it can easily be mistaken for the normal acromioclavicular joint. Differential Diagnosis normal AC joint Page 13 of 48

14 degenerative ossification acromion fracture Notes Fig. 18: os acromiale References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 14 of 48

15 Fig. 17: os acromiale References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT 4. Os Subfibulare Location Ajacent to the tip of the lateral malleolus of the ankle General Incidence very rare Symptoms Can cause painful syndromes or degenerative change in response to Page 15 of 48

16 overuse and trauma. The ossicle itself may fracture. Causes / Risk Factors There are two hypotheses: It's an unfused accessory ossification center. It's an avulsion fracture attributable to pull of the anterior talofibular ligament. Imaging Differential Diagnosis Avulsion fracture of the lateral malleolus Notes 5. Os Trigonum Location Posterior to the talus General Incidence ~7 % Symptoms Posterior syndrome Causes / Risk Factors It origins on a failure of fusion of the lateral tubercle of the talus Imaging Best characterized on MRI, signal characteristics of the affected region include: ankle impingement (PAI) T1: low signal in areas of bony bruising T2/STIR: high signal posterior to ankle in areas of bone bruising PD/PD fat saturated: high signal posterior to the ankle Differential Diagnosis avulsion fracture of lateral tubercle of talus (Shepherd fracture) fracture of Stieda process Notes Page 16 of 48

17 Fig. 15: os trigonum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 17 of 48

18 Fig. 14 References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT 6. Carpal Boss Location os styloideum is located dorsally between the trapezoid, Page 18 of 48

19 capitate and 2nd and 3rd metacarpal base. os trapezium secundarium is located between the trapezium and the base of the first metacarpal, developing as an appendage to the tubercle of the trapezium. General Incidence ~2.0 % (os styloideum) Symptoms Degenerative joint disease Causes / Risk Factors Imaging Differential Diagnosis Notes Page 19 of 48

20 Fig. 3: os trapezoideum secundarium References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 20 of 48

21 Fig. 2: os trapezoideum secundarium References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 21 of 48

22 Fig. 4: os styloideum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT 7. Os Calcaneus secundarius Location anterior calcaneal process General Incidence 5% Symptoms ankle pain Causes / Risk Factors Imaging Differential Diagnosis bifurcated ligament avulsion fracture of the anterior calcaneal process. Notes Page 22 of 48

23 Fig. 16: os calcaneus secundarius References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT 8. Os Peroneum Location lateral plantar aspect of the cuboid General Incidence very common, seen in up to 26% of feet Symptoms Os peroneum syndrome includes fracture, peroneus longus tenosynovitis and peroneus longus tendon tear. Causes / Risk Factors Imaging Differential Diagnosis os vesalianum apophysis of the 5th metatarsal avulsion fracture (pseudojones fracture) Notes Page 23 of 48

24 9. Os Intermetatarseum Location Typically positioned dorsally between the bases of the first and second metatarsals but has been reported to occur near the metatarsal heads or between the fourth and fifth metatarsal bases. General ~4% Incidence (range 1-7%) Symptoms dorsal midfoot pain Causes / Risk Factors Imaging It can have a variety of shapes: round oval beanshaped linear Page 24 of 48

25 resemble a rudimentary metatarsal Differential Diagnosis Notes It can be classified into three basic types: free standing: it is a completely independent ossicle, and it does not show any osseous or articular connection with any structure articulating: it may form a synovial joint with first or second metatarsal Page 25 of 48

26 or the medial cuneiform fused: it forms a spur that is seen as a bony projection in the first and second intermetatarsal space Page 26 of 48

27 Fig. 5: os intermetatarseum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 27 of 48

28 Fig. 6: os intermetatarseum References: Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 28 of 48

29 Images for this section: Fig. 2: os trapezoideum secundarium Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 29 of 48

30 Fig. 3: os trapezoideum secundarium Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 30 of 48

31 Fig. 4: os styloideum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 31 of 48

32 Fig. 5: os intermetatarseum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 32 of 48

33 Fig. 6: os intermetatarseum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 33 of 48

34 Fig. 7: Accessory navicular Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 34 of 48

35 Fig. 8: Accessory navicular Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 35 of 48

36 Fig. 9: Accessory navicular Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 36 of 48

37 Fig. 10: os odontoideum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 37 of 48

38 Fig. 11: os odontoideum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 38 of 48

39 Fig. 1: Locations of the more common symptomatic ossicles: 1. os odontoideum; 2. Accessory Navicular; 3. os acromiale; 4. os subfibulare; 5. os trigonum; 6. Carpal Boss; 7. os calcaneus secundarius; 8. os peroneum; 9. os intermetatarseum. Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 39 of 48

40 Fig. 12: os odontoideum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 40 of 48

41 Fig. 13: os odontoideum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 41 of 48

42 Fig. 14 Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 42 of 48

43 Fig. 15: os trigonum Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Fig. 16: os calcaneus secundarius Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 43 of 48

44 Fig. 17: os acromiale Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 44 of 48

45 Fig. 18: os acromiale Imagiologia / Radiologia, Unidade Hospitalar de Portimão, Centro Hospitalar do Algarve - Portimão/PT Page 45 of 48

46 Conclusion Normal anatomic variations are frequently overlooked as a minor finding, sometimes not being reported when identified, when in fact they can be the source of a patient's symptomatology. Learning the key imaging characteristics of these pathologies is essential for determining whether or not to attribute clinical symptoms to the accessory ossicles. Page 46 of 48

47 Personal information J. Saraiva 1 C. Bilreiro 1 L. Silva C. Carneiro B.M.Q. Santos 1 M.O.E. Castro All authors declare to have no conflits of interest on this publication. 1 Serviço de Radiologia, Centro Hospitalar do Algarve, Unidade Hospitalar de Portimão, Sítio do Poço Seco, 8500 Portimão - PORTUGAL Page 47 of 48

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