sign in sign up
<<
Home , Oligoarthritis

rad review of skeletal imaging and bone densitometry Crystal deposition diseases RAD Magazine, 46, 540, 23-24 Dr Mostafa Ellatif Specialist registrar in clinical radiology Dr Dhiren Shah Consultant musculoskeletal radiologist Department of radiology, Northwick Park Hospital, London

Introduction A B C Crystal deposition diseases are a spectrum of arthritides Figure 1 induced by cellular reaction and inflammatory response in Series of cases. (A) Radiograph of a hand and around joints due to microcrystals. The most common demonstrating multiple punched out erosions of these disorders are gout, calcium pyrophosphate dihydrate (arrowed) with overhanging edges and preserved and calcium hydroxyapatite deposition disease. The differ- joint spaces. (B) Sagittal CT demonstrating cervical ence in the pathophysiology of these diseases means they gout involvement affecting C1 and C2 with well are unique in their clinical presentation and radiological defined erosions (arrowed). (C) Coronal CT image of appearances. Imaging plays a pivotal role in the diagnosis a knee showing extensive involvement with large and subsequent monitoring of treatment response and is a punched out erosions (arrowed) severly deforming cornerstone of management. Conventional radiography the joint (with preserved joint space). remains the primary modality, but there is an increasing role of ultrasound, CT, MRI and dual energy CT. mutilating , mimicking psoriatic and rheumatoid Gout arthritis. Gout is the commonest of the crystal with an Crystal deposition may occur at tendon insertions, such incidence of 0.5%1 and increasing prevalence with age. The as in the calcaneus, olecranon and patella giving the radio- underlying aetiology can broadly be divided into urate over- logical appearance of ‘spiking’. Bilateral olecranon bursitis production (eg myeloproliferative disorders and defects in and swelling at the dorsum of the foot are classic soft tissue 7 purine synthesis) or under-excretion (eg renal failure or use manifestations of gout. of diuretics).2 Elevated levels of urate lead to monosodium The ultrasound features of MSU deposits are the double- urate (MSU) crystal formation when levels reach 6.8g/dl. contour sign, as well as tophi and erosions. The double-con- The definitive diagnosis is made by symptomatic joint aspi- tour line refers to a hyperechoic band over the superficial ration with subsequent analysis identifying needle-like neg- cartilage and is relatively specific for gout. Tophi are usually atively birefringent crystals on microscopy.3 identified as hyperechoic aggregates with a surrounding ane- Clinically, gout presents with recurrent episodes of joint choic rim, while erosions demonstrate focal discontinuity of pain, initially with absence of radiological signs. Peak inci- the bony cortex. In the more acute phase, a joint effusion dence is in males aged 30-60 with a predilection for the first may be identified with evidence of synovitis.8 metatarsophalangeal joint (MTPJ). The first MTPJ is the Dual energy CT (DECT) allows differentiation of crystals symptomatic joint at presentation in 50% of cases, involve- by their x-ray spectra based on their density and atomic ment rising to 90% in patients with untreated gout.3 Other number. Data is acquired at 80kV and 140kV using two x- commonly affected joints are the first interphalangeal and ray tubes. Using a decomposition algorithm, calcium can be tarsometatarsal joints. If untreated, these episodes eventu- distinguished from MSU with reported specificity between ally subside but often recur with polyarticular involvement. 75-100%.9,10 The data is used to produce a colour-coded map, Peri-articular tophi develop in chronic gout due to amor- which is fused with a conventional CT, allowing assessment phous debris containing urate and proteinaceous deposits of the affected sites and disease burden. 4 with surrounding foreign body reaction. Calcium pyrophosphate dihydrate disease (CPPD) Radiography is typically the first imaging modality used in gout to assess joint destruction and rule out differential CPPD results in arthritis, synovitis and tendonitis secondary diagnoses. Small joints are typically affected more with a to localised inflammatory response to the crystals. The predilection for the lower limbs. The overall pattern is usu- pathophysiology is not fully understood but thought to be ally asymmetric with a , and subsequent due to defects in the metabolism of calcium and phosphate.11 oligoarthritis or .5 The ankle, tarsal and knee CPPD is a disease of the elderly population, affecting women usually are affected early in the disease process, with all and men equally. is identified radiologi- compartments of the hand, wrist and elbow being other cally in 5% of the population by the age of 70.12 Associations favourable sites. with primary hyperparathyroidism, haemochromatosis and In early gout, the symptomatic joint is typically normal hereditary spherocytosis have been described.13 or demonstrates soft tissue swelling or peri-articular oedema. The spectrum of clinical presentation of CPPD ranges Once the acute episode has passed, small well-defined ero- from incidental (most common), pseudogout, pseudo- sions may start to develop peripherally at the affected joints , pseudorheumatoid arthritis, or pseudo-neuro- with overhanging margins. More classic findings with tophi pathic arthritis. Pseudogout is a subset of CPPD that mimics and increasing erosions become apparent with chronicity. gout clinically but is due to calcium pyrophosphate rather Importantly, there is preservation of the joint space with than monosodium urate, with aspirated crystals being lack of peri-articular osteopenia. Tophi tend to measure weakly positive under polarising light. between 5-10mm and faint calcification is seen in 50% of Pseudo-osteoarthritis mimics osteoarthritis clinically and cases.6 Erosions are eccentric, round, well circumscribed and radiologically. Patients will demonstrate the typical features juxta-articular. Occasionally, extensive erosions can cause a of joint space loss, subchondral sclerosis and cysts with or rad review of skeletal imaging and bone densitometry

20 without chondrocalcinosis. Osteophytosis is often absent. of 40-70. Aspirated crystals are needle-like on microscopy 21 Distinguishing features in such cases may be an atypical and stain purple with Wright’s stain. distribution, such as predominantly patellofemoral or Patients are often asymptomatic with only 34-45% of 20 metacarpophalangeal joint involvement.3 CPPD will also be patients presenting with symptoms. Clinically, HADD is more progressive than osteoarthritis causing formation of usually monoarticular and tends to affect the shoulder joint, intra-articular osseous bodies. CPPD favours radiocarpal, but can be polyarticular. Patients present with severe pain metacarpophalangeal and non-weight bearing joints in com- and tenderness with restricted range of motion, mimicking parison to osteoarthritis.10 gout, or CPPD. It may occur in isolation or Pseudorheumatoid arthritis mimics in association with connective tissue disease, renal osteodys- clinically with chronic history of morning stiffness and trophy, trauma, or iatrogenic secondary to steroid injec- 22 restricted range of motion in a symmetrical distribution. tions. HADD can cause bursitis, tendonitis or acute 23 Chondrocalcinosis may be the only distinguishing feature in arthritis. such cases.14 In pseudoneuropathic CPPD there are radio- Radiographic appearances depend on the chronicity of the logical findings of joint destruction and subluxation in the disease. Cloud-like and poorly defined calcific deposits are absence of a neurological abnormality.15 seen, which become denser and more linear with chronicity. The definitive diagnosis is made based on the aspirated HADD most commonly affects the shoulders with capsular, crystals as well as imaging findings of chondrocalcinosis. If tendinous and bursal tissue calcification. Appearances are only one of the two is identified then the diagnosis is pre- bilateral in 50% of cases and often affect the supraspinatus 24 sumed.16 CPPD crystals are deposited in fibrocartilage and tendon, but all rotator cuff tendons may be involved. Bony hyaline cartilage. Fibrocartilage deposition is most common erosions may be present at the insertion sites of tendons in knee menisci and the triangular fibrocartilage of the and ligaments, which may have associated bone marrow wrist.17 Radiologically this is identified as irregular or linear oedema on MRI. Elbow involvement is also common and can calcification within the cartilage. Synovial calcification is affect the collateral ligaments and triceps tendon at its ole- often seen in conjunction, typically in knee, metacarpo- or cranon insertion, where it is occasionally associated with metataro-phalangeal joints. Tendon calcification also occurs rupture. in the Achilles, triceps, quadriceps and supraspinatus ten- Axial skeleton involvement has been described, affecting dons – often thin and linear.18 the longus colli muscle in the neck as well as the inter- Hyaline, fibrocartilage and tendinous calcification can be spinous bursae. In the hips, gluteal tendinous insertion reliably identified sonographically as hyperechoic foci (linear or amorphous) with the affected structures in more chronic cases. Acutely, similar to gout, a degree of hyperaemia and synovitis may be identified.19 Calcium hydroxyapatite deposition disease (HADD) Deposition of calcium hydroxyapatite crystals in joints, peri- articular soft tissues, tendons and bursa are responsible for HADD. The underlying aetiology is not yet understood, with no gender predilection and most patients between the ages

A B

A B

C D Figure 3 C Series of HADD cases. (A) Lateral radiograph of the cervical spine demonstrating calcification along the Figure 2 longus colli muscle (arrowed) – highly suggestive of Series of CPPD cases. (A) Radiograph of a knee HADD. (B) Sagittal MRI STIR image demonstrating demonstrates chondrocalcinosis (arrowed) of the a HADD deposit posterior to the fibular head lateral meniscus. (B) Radiograph of a wrist shows (arrowed) with surrounding inflammatory response. calcification within the triangular fibrocartilage. (C) Radiograph of a shoulder with the subsequent (C) Axial CT image demonstrating calcification of coronal MRI STIR image (D). These demonstrate the transverse ligament around the dens – ‘crowned amorphous calcification within the supraspinatus dens syndrome’. tendon in keeping with calcific tendinitis. rad review of skeletal imaging and bone densitometry involvement, extending to the greater trochanter and sur- 4, Hench P S. The diagnosis of gout and gouty arthritis. J Lab Clin Med rounding bursae, is frequently identified.25 Quadriceps, patel- 1936;220:48. 5, Resnick D, Niwayama G. Diagnosis of bone and joint disorders with lar and Achilles tendon involvement is often seen. emphasis on articular abnormalities. Philadelphia: W B Saunders; 1981. Crystal deposition can occur within the synovium or car- 6, Tallbott J H. Gout. New York: Grune & Stratton; 1967. tilage involving the shoulder, knee, hip and small joints of 7, Wright J T. Unusual manifestations of gout. Australas Radiol 1966;10:365. the hands/feet. Destructive HADD of the shoul- 8, Omoumi P, Zufferey P, Malghem J, So A. Imaging in gout and other crys- tal-related arthropathies. Rheum Dis Clin N Am 2016;42:621-44. der is termed Milwaukee shoulder syndrome with features 9, Choi H K, Burns L C, Shojania K et al. Dual energy CT in gout: a prospec- of joint space loss, subchondral sclerosis, joint disorganisa- tive validation study. Ann Rheum Dis 2012;9(71):1466-71. tion and deformity.3 There is often an associated joint effu- 10, Omoumi P, Becce F, Racine D et al. Dual-energy CT: basic principles, sion with superior migration of the humeral head due to technical approaches, and applications in musculoskeletal imaging (part 1). Semin Musculoskelet Radiol 2015;5(19):431-37. disruption of the rotator cuff. 11, Bjelle A. Pyrophosphate arthropathy. Scand J Rheumatol 1979;8:145. Ultrasound in HADD is primarily used to identify the 12, McCarty D J. Arthritis associated with crystals containing calcium. Med deposits, which will be hyperechoic with posterior acoustic Clin North Am 1986;70:437. shadowing. Doppler activity around a deposit and presence 13, Dymock I W, Hamilton E B, Laws J W et al. Arthropathy of haemochro- of an effusion suggest and may correlate with matosis. Clinical and radiological analysis of 63 patients with iron over- 26 load. Ann Rheum Dis 1970;29:469. pain. 14, Resnick D, Williams G, Weisman M H et al. Rheumatoid arthritis and pseudo-rheumatoid arthritis in calcium pyrophosphate dihydrate crystal Conclusion deposition disease. Radiology 1981;140:615. Crystal deposition diseases are a common cause of inflam- 15, Helms C A, Chapman G S, Wild J H. Charcot-like joints in calcium pyrophosphate dihydrate deposition disease. Skeletal Radiol 1981;7:55. matory arthropathy, especially with an increasing ageing 16, McCarty D J. Pseudogout, articular chondrocalcinosis. 8th edition. population. The three most common crystal arthropathies Philadelphia: Lea & Febiger; 1972. are gout, CPPD and HADD. Conventional radiography 17, Resnick D, Niwayama G, Goergen T G et al. Clinical, radiographic and remains the mainstay of diagnosis. Ultrasound is playing pathologic abnormalities in calcium pyrophosphate dihydrate deposition disease (CPPD): pseudogout. Radiology 1977;122:1. an increasingly important role in early diagnosis and per- 18, Resnik C S, Resnick D. Crystal deposition disease. Semin Arthritis Rheum cutaneous intervention. Dual energy CT use in crystal depo- 1983;12:390. sition disease is in its infancy but has great potential in 19, Taljanovic M S, Melville D M, Gimber L H et al. High-resolution US of aiding with diagnosis and assessing disease burden. The dis- rheumatologic diseases. Radiographics 2015;7(35):2026-48. cussed multimodality imaging features of the different con- 20, Amor B, Cherot A, Delbarre F et al. Hydroxyapatite rheumatism and HLA markers. J Rheumatol Suppl 1977;3:101. ditions allow their differentiation. Clinicians, reporting 21, Faure G, Daculsi G. Calcified tendinitis: a review. Ann Rheum Dis radiographers and radiologists should be aware of these fea- 1983;42(Suppl 1):49. tures to ensure patients are diagnosed promptly and treated 22, Dalinka M K, Stewart V, Bomalaski J S et al. Periarticular calcifications appropriately to prevent debilitating chronic disease. in association with intraarticular corticosteroid injections. Radiology 1984;153:615. 23, Schumacher H R, Cherian P V, Reginato A J et al. Intra-articular apatite References crystal deposition. Ann Rheum Dis 1983;42(Suppl 1):54. 1, Agudelo C A, Wise C M. Gout: diagnosis, pathogenesis, and clinical man- 24, Winn R S, Melhorn J M, De Smet A A. Layering of calcifications in syn- ifestations. Curr Opin Rheumatol 2001;13:234. ovial effusions. J Can Assoc Radiol 1981;32:66. 2, German D C, Holmes E W. Hyperuricemia and gout. Med Clin North Am 25, Wepfer J F, Reed J G, Cullen G M et al. Calcific tendinitis of the gluteus 1986;70:419. maximus tendon (gluteus maximus tendinitis). Skeletal Radiol 1983;9:198. 3, Choi M H, MacKenzie J D, Dalinka M K. Imaging features of crystal- 26, Zufferey P, So A. A pilot study of IL-1 inhibition in acute calcific peri- induced arthropathy. Rheum Dis Clin N Am 2006;32:427-46. arthritis of the shoulder. Ann Rheum Dis 2013;3(72):465-67.