Alvin S. Chen, Harvard Medical School Year III Gillian Lieberman, MD Radiology Core Clerkship

Transcription

1 Alvin S. Chen, Harvard Medical School Year III Gillian Lieberman, MD Radiology Core Clerkship

2 Overview Wrist: Normal Anatomy & Biomechanics Approach to Wrist Imaging: Menu of Tests & Efficacious Use Index Patient SLAC Wrist: Clinical Implications & Radiographic Diagnosis SLAC Wrist: Treatment 2

3 Normal Anatomy of the Wrist: PA Source: 3

4 Normal Anatomy of the Wrist: PA Note: Pisiform and Triquetrum overlap The other carpal bones partly overlap Source: 4

5 Normal Anatomy of the Wrist: Lateral Source: 5

6 Normal Anatomy of the Wrist: Lateral Note: The scaphoid is difficult to see clearly on this view This view is essential to check for alignment of the radius, lunate and capitate Source: 6

7 Normal Anatomy of the Wrist: Ligaments Source: Netter s Atlas of Anatomy, 4e 7

8 Normal Anatomy of the Wrist: Ligaments Source: Netter s Atlas of Anatomy, 4e 8

9 Normal Anatomy of the Wrist: Ligaments Coronal T-1 weighted MRI showing normal SL ligament (arrow) (S, scaphoid; L, lunate; T, triquetrum) Source: 9

10 Wrist Biomechanics Three distinct biomechanical concepts have been proposed, but the intercalated row concept is most widely accepted The wrist is comprised of radius/ulna, proximal and distal rows Scaphoid serves as a bridge between rows The proximal carpal row has no tendinous attachments so its position is determined by the position of the radius and distal carpal row Disruption (fracture or ligamentous injury) leads to instability in wrist motion 10

11 Wrist Biomechanics Source: 11

12 Wrist Biomechanics Scaphoid Axis True axis of scaphoid is the line through the mid-points of its proximal and distal pole A parallel line bordering the ventral points of the proximal and distal poles of the bone can be used as a good proxy Source: 12

13 Wrist Biomechanics Lunate Axis Lunate axis runs through midpoints of the convex proximal and concave distal joint surfaces Best approximated by tracing the perpendicular line to a line joining the distal palmar and dorsal borders Normal SL angle: 30-60⁰ Borderline: 60-80⁰ Abnormal: >80⁰ (indicates wrist instability) Source: 13

14 Wrist Biomechanics Capitate Axis Capitate axis joins the midportion of the proximal convexity of the third metacarpal and that of the proximal surface of the capitate Normal CL angle: <30⁰ Abnormal: >30⁰ (indicates wrist instability) Source: 14

15 Overview Wrist: Normal Anatomy & Biomechanics Approach to Wrist Imaging: Menu of Tests & Efficacious Use Index Patient SLAC Wrist: Clinical Implications & Radiographic Diagnosis SLAC Wrist: Treatment 15

16 Menu of Tests & Efficacious Use Plain film (X-ray) Wrist Series Standard: AP, Lateral, and Oblique Obtain scaphoid view (semipronated oblique) if there is suspicion for scaphoid fracture Obtain clenched fist view if there is suspicion for ligamentous injury, especially SL ligament MRI: if suspicion for fracture or ligamentous injury but radiographs negative More sensitive than plain film for detecting fracture, ligament tears, edema and arthritis Allows for early detection of AVN MR Arthrography can be used in suspected intercarpal ligament or TFCC tears 16

17 Menu of Tests & Efficacious Use Less commonly used tests: Conventional CT Scan Allows for 3-D visualization of carpal bones, soft tissue detail Can assess nonunion of fractures, usually scaphoid waist fx Utilized to better define a previously detected fracture or assess the distal radial ulnar joint Fluoroscopy Useful for dynamic detection of abnormal bony motion and ligamentous/capsular injury Bone Scintigraphy Can be used to work-up occult fractures; high sensitivity, low specificity Ultrasound Limited use in trauma setting, may allow for evaluation of extensor or flexor tendons to exclude rupture Can visualize foreign bodies, cysts or effusions Arthroscopy Allows for direct visualization of wrist structures, gold-standard, invasive 17

18 Overview Wrist: Normal Anatomy & Biomechanics Approach to Wrist Imaging: Menu of Tests & Efficacious Use Index Patient SLAC Wrist: Clinical Implications & Radiographic Diagnosis SLAC Wrist: Treatment 18

19 Index Patient: History of Present Illness 49 yo AA man w/pmhx ulcerative colitis and ankylosing spondylitis presenting with 9 months of insidious onset right wrist pain Reports swelling and erythema of the right wrist over the dorsal surface Worse with palpation and flexion/extension Has tried Tylenol with minimal relief Does not remember specific trauma that may have caused this, but has had a few falls over the past year SocHx: works as a secretary at a local hospital ROS, FMHx non-contributory 19

20 Index Patient: Physical Examination Vital signs within normal limits General: obese man in NAD HEENT/Neck: no malar rash, no lymphadenopathy Cardiopulmonary exam: normal Joint exam: right-sided 2+ edema in medial dorsal aspect of wrist, tender to palpation, significantly decreased ROM, positive Watson scaphoid shift test 20

21 Watson Scaphoid Shift Test With firm pressure over the palmar tuberosity of the scaphoid, the wrist is moved from ulnar to radial deviation Dorsal wrist pain or a clunk during this maneuver may indicate instability of SL ligament Sens: 86%, Spec: 57% Source: 21

22 Index Patient: Differential Diagnosis Scapholunate Advanced Collapse (SLAC) Scaphoid Non-Union Advanced Collapse (SNAC) Carpal fracture (scaphoid, lunate, triquetral, etc.) Carpal arthritis (OA vs. RA) Wrist tendonitis Carpal tunnel syndrome Chronic osteomyelitis De Quervain tenosynovitis Kienbock s disease Scaphotrapezoid-trapezial (STT) joint arthritis Ulnar nerve entrapment 22

23 Index Patient: Plain Films Please pause to evaluate, continue to view findings Source: PACS, BIDMC 23

24 Index Patient: Plain Films Please pause to evaluate, continue to view findings Source: PACS, BIDMC 24

25 Index Patient: Plain Film Interpretation Abnormal sclerosis of scaphoid Degenerative changes in the radiocarpal joint involving the scaphoid fossa with subchondral sclerosis and marginal osteophytes Widening of the scapholunate interval with proximal displacement of the capitate No acute fracture or dislocation seen Appearance of scaphoid reflects degenerative change vs. AVN Appearance consistent with possible SLAC wrist To better characterize underlying cause of degenerative arthritis and possible ligamentous injury, an MRI was ordered 25

26 Index Patient: Coronal T1-weighted MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 1 Source: PACS, BIDMC 26

27 Index Patient: Coronal T1-weighted MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 2 Source: PACS, BIDMC 27

28 Index Patient: Coronal T1-weighted MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 3 Source: PACS, BIDMC 28

29 Index Patient: Coronal T1-weighted MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 4 Source: PACS, BIDMC 29

30 Index Patient: Coronal T1-weighted MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 5 Source: PACS, BIDMC 30

31 Index Patient: Coronal T2-weighted FS MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 1 Source: PACS, BIDMC 31

32 Index Patient: Coronal T2-weighted FS MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 2 Source: PACS, BIDMC 32

33 Index Patient: Coronal T2-weighted FS MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 3 Source: PACS, BIDMC 33

34 Index Patient: Coronal T2-weighted FS MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 4 Source: PACS, BIDMC 34

35 Index Patient: Coronal T2-weighted FS MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 5 Source: PACS, BIDMC 35

36 Index Patient: Coronal T2-weighted FS MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Slice 6 Source: PACS, BIDMC 36

37 Index Patient: Sagittal T1-weighted MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Source: PACS, BIDMC 37

38 Index Patient: Sagittal T1-weighted MRI Please scroll through sequences to evaluate, findings will be provided on summary slide following these images Widened CL angle!! Source: PACS, BIDMC 38

39 Index Patient: MRI Interpretation Widening of SL interval consistent with SL ligament tear Severe radio-scaphoid osteoarthritis, but no definite thinning of capitate cartilage and proximal migration of the capitate, consistent with stage II SLAC wrist Peripheral low signal intensity associated with T2 hyperintense signal within subchondral aspects of the scpahoid, lunate, trapezoid, capitate, and hamate consistent with subchondral cysts vs. erosions vs. synovitis Dorsal intercalated segment instability (DISI) deformity (CL angle > 30⁰) noted on sagittal view, dorsiflexion of lunate with posterior subluxation of distal carpal row 39

40 Overview Wrist: Normal Anatomy & Biomechanics Approach to Wrist Imaging: Menu of Tests & Efficacious Use Index Patient SLAC Wrist: Clinical Implications & Radiographic Diagnosis SLAC Wrist: Treatment 40

41 SLAC Wrist: Etiology A condition of progressive wrist instability causing advanced arthritis of radiocarpal and midcarpal joints Describes the specific pattern of degenerative arthritis seen in chronic dissociation between the scaphoid and lunate Chronic SL ligament injury creates a DISI deformity scaphoid becomes flexed volarly and lunate is extended dorsally Leads to aberrant force distribution across midcarpal and radiocarpal joints and malalignment of concentric joint surfaces Initially presents as arthritis of radioscaphoid joint, then progressing to arthritis of capitolunate joint 41

42 SLAC Wrist: Etiology Causes can be traumatic or atraumatic Scaphoid fracture (SNAC wrist) Scapholunate ligament tear Kienbock s disease (avascular necrosis of lunate) Calcium pyrophosphate dehydrate deposition disease Rheumatoid arthritis Neuropathic diseases β2-microglobulin associated amyloid deposition disease Extra-intestinal manifestation of IBD 42

43 SLAC Wrist: Presentation Symptoms Difficulty bearing weight across wrist Pain over dorsal surface of wrist, specifically in region of SL interval Progressive hand weakness Wrist stiffness Physical Exam Tenderness to palpation over dorsal aspect of wrist Significantly decreased ROM Weakened grip strength Positive Watson scaphoid shift test 43

44 SLAC Wrist: Radiographic Diagnosis Stage I SLAC Wrist: arthritis between scaphoid and radial styloid >3 mm diastasis between scaphoid and lunate ( Terry Thomas sign ) PA radiograph shows radial styloid beaking, sclerosis and joint space narrowing between scaphoid and radial styloid Source: 44

45 SLAC Wrist: Radiographic Diagnosis Stage II SLAC Wrist: arthritis between scaphoid and entire scaphoid facet of the radius >3 mm diastasis between scaphoid and lunate ( Terry Thomas sign ) PA radiograph shows sclerosis and joint space narrowing between the scaphoid and the entire scaphoid fossa of distal radius Source: 45

46 SLAC Wrist: Radiographic Diagnosis Stage III SLAC Wrist: arthritis between capitate and lunate >3 mm diastasis between scaphoid and lunate ( Terry Thomas sign ) PA radiograph shows sclerosis and joint space narrowing between the lunate and capitate with subchondral cyst formation Eventually, the capitate will migrate into the void created by the SL dissociation Source: 46

47 SLAC Wrist: Radiographic Diagnosis Stage III SLAC Wrist: arthritis between capitate and lunate >3 mm diastasis between scaphoid and lunate ( Terry Thomas sign ) PA radiograph shows sclerosis and joint space narrowing between the lunate and capitate with subchondral cyst formation Eventually, the capitate will migrate into the void created by the SL dissociation Source: 47

48 SLAC Wrist: Radiographic Diagnosis In scapholunate ligament injury, can also see cortical ring sign caused by scaphoid malalignment May be present in any of the three stages of SLAC wrist Source: 48

49 SLAC Wrist: Radiographic Diagnosis Dorsal intercalated segmental instability (DISI) is easily diagnosed on lateral plain film DISI is caused by disruption of the SL articulation Lunate becomes angulated dorsally Radiographs are consistent with DISI pattern when scapholunate angle > 80⁰ or capitolunate angle > 30⁰ Normal Carpal Alignment Source: DISI 49

50 SLAC Wrist: Radiographic Diagnosis MRI is unnecessary for staging but would show: Thinning of articular surfaces of the proximal scaphoid Synovitis of the scaphoid facet of distal radius and capitolunate joint Complete or partial rupture of the SL ligament Source: PACS, BIDMC 50

51 Overview Wrist: Normal Anatomy & Biomechanics Approach to Wrist Imaging: Menu of Tests & Efficacious Use Index Patient SLAC Wrist: Clinical Implications & Radiographic Diagnosis SLAC Wrist: Treatment 51

52 SLAC Wrist: Treatment Non-operative: Address underlying cause (e.g. treatment of rheumatologic disease) NSAIDs Wrist immobilization with splints Corticosteroid injections Operative Radial styloidectomy Anterior and posterior interosseous nerve denervation Distal scaphoid pole excision Proximal row carpectomy Four-corner arthrodesis Capitolunate arthrodesis 52

53 SLAC Wrist: Radial styloidectomy Indicated for Stage I disease Excision of radial styloid Prevents impingement between proximal scaphoid and radial styloid May be performed open or arthroscopically via 1,2 portal Can be combined with other procedures for maximal relief in symptoms Source: 53

54 SLAC Wrist: Proximal Row Carpectomy Indicated for Stage II disease Excision of entire proximal row of carpal bones while preserving radioscaphocapitate (RSC) ligament (to prevent ulnar subluxation) Contraindicated if RSC ligament is incompetent Results in capitate articulating with lunate fossa of radius Provides relative preservation of strength and motion Source: Strauch, RJ. SLAC and SNAC Arthritis Update on Evaluation and Treatment. J Hand Surg. 2011; 36A:

55 SLAC Wrist: Four-corner arthrodesis Indicated for Stage II & III disease After removal of cartilagenous structures, the capitate, lunate, hamate and triquetrum are fused using cancellous bone graft from either the radius or iliac crest Can also be fixed using circular plates Preserved articulation between lunate and distal radius Also provides relative preservation of strength and motion Similar long-term results between PRC and four-corner fusion Source: Dacho et al. Long-Term Results of Midcarpal Arthrodesis in the Treatment of SNAC- Wrist and SLAC-Wrist. Annals of Plastic Surgery. 56(2); Feb

56 SLAC Wrist: Four-corner arthrodesis AP film showing circular plate fixation for 4-corner fusion for SLAC wrist Source: Strauch, RJ. SLAC and SNAC Arthritis Update on Evaluation and Treatment. J Hand Surg. 2011; 36A:

57 SLAC Wrist: Capitolunate arthrodesis AP film showing solid capitolunate fusion using cannulated screws for SLAC wrist Source: Strauch, RJ. SLAC and SNAC Arthritis Update on Evaluation and Treatment. J Hand Surg. 2011; 36A:

58 Back to our patient Upon consultation with his rheumatologist, his symptoms were thought to be extra-intestinal manifestations of his ulcerative colitis His colitis had been dormant for several years, and he had been off treatment during this same time period He was restarted on Sulfasalazine 500 mg QID On one month follow-up, his symptoms had decreased significantly and his right wrist ROM was back to normal 58

59 Summary Scapholunate dissociation or ligament injury can lead to DISI deformity and eventually SLAC wrist Plain films (PA, lateral, oblique) are the study of choice for diagnosing and staging of SLAC wrist MRI can be used to elucidate the etiology of SLAC wrist, but is usually not necessary Several surgical techniques, including radial styloidectomy, denervation, proximal row carpectomy, and 4-corner fusion, have been shown to have positive outcomes in patients with SLAC wrist 59

60 References Watson HK, Ballet FL. The SLAC wrist: scapholunate advance collapse pattern of degenerative arthritis. J Hand Surg [Am]. 1984;9A: Watson HK, Ryu J. Evolution of arthritis of the wrist. Clin Orthop Relat Res. 1986;202:57:67. Dacho A, Grundel J, Holle G, Germann G, et al. Long-term results of midcarpal arthrodesis in the treatment of scaphoid nonunion advanced collapse (SNAC-wrist) and scapholunate advanced collapse (SLAC-wrist). Ann Plast Surg. 2006;56(2): Shah CM, Stern PJ. Scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) wrist arthritis. Curr Rev Musculoskelet Med (2013). 6:9-17 Strauch, RJ. Scapholunate Advanced Collapse and Scaphoid Nonunion Advanced Collapse Arthritis Update on Evaluation and Treatment. J Hand Surg. 2011; 36A:

61 References Dacho A, Baumeister S, Germann G, Sauerbier M. Comparison or proximal row carpectomy and midcarpal arthrodesis for the treatment of scaphoid nonunion advanced collapse (SNAC-wrist) and scapholunate advanced collapse (SLAC-wrist) in stage II. J Plastic, Recon & Anes Surg. (2008) 61, Cha SM, Shin HD, Kim KC. Clinical and Radiological Outcomes of Scaphoidectomy and 4-Corner Fusion in Scapholunate Advanced Collapse at 5 and 10 years. Ann Plastic Surg. (2013). 71(2); Wyrick JD, Stern PJ, Kiefhaber TR. Motion-preserving procedures in the treatment of scapholunate advanced collapse wrist: proximal row carpectomy versus four-corner arthrodesis. J Hand Surg Am. 1995; 20:965:970. Jebson PJ, Hayes EP, Engber WD. Proximal row carpectomy: a minimum 10-year follow-up study. J Hand Surg Am. 2003:28:561:

62 Image & Web References Vitale M. SLAC (Scaphoid Lunate Advanced Collapse). Orthobullets. Accessed 4/17/14. Gilula L, Chesaru I. Wrist Carpal Instability. Radiology Assistant. Accessed 4/17/14. /p42a29ec06b 9e8/wrist-carpalinstability.html#i430347c DISI and VISI Deformities. Wiki Radiography. Accessed 4/18/14. Wheeless CR. Scapholunate Advanced Collapse (SLAC). Wheeless Textbook of Orthopaedics. Accessed 4/17/14. Trauma X-ray Upper Limb. Radiology Masterclass. Accessed 4/19/14. Imbriglia, JE. Proximal Row Carpectomy. Hand Surgery 1 st Edition. Accessed 4/21/14. Netter, F. Atlas of Human Anatomy. 4 th Edition

63 Acknowledgements Dr. Justin Kung Dr. Omer Awan Dr. Gunjan Senapati Dr. Jawad Hussain Dr. Gillian Lieberman Megan Garber 63