Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights. REVIEWS AND COMMENTARY Radiographic Evaluation of Arthritis: Degenerative Joint Disease 1 and Variations Ⅲ REVIEW FOR RESIDENTS Jon A. Jacobson, MD In the presence of joint space narrowing, it is important to Gandikota Girish, MD differentiate inflammatory from degenerative conditions. Yebin Jiang, MD, PhD The presence of osteophytes, bone sclerosis, and subchon- Brian J. Sabb, DO dral cysts and the absence of inflammatory features such as erosions suggest osteoarthritis. Typical osteoarthritis involves specific joints at a particular patient age. When osteoarthritis involves an atypical joint, occurs at an early age, or has an unusual radiographic appearance, then other causes for cartilage destruction should be consid- ered, such as trauma, crystal deposition, neuropathic joint, and hemophilia. There are several types of arthritis, such as juvenile chronic arthritis and gouty arthritis, that may have a variable appearance compared with that of other common inflammatory arthritides. ௠ RSNA, 2008 1 From the Department of Radiology, University of Michi- gan Medical Center, 1500 E Medical Center Dr, TC-2910L, Ann Arbor, MI 48109-0326. Received Decem- ber 11, 2006; revision requested February 7, 2007; revi- sion received July 25; accepted September 12; final ver- sion accepted November 7; final review by J.A.J. April 20, 2008. Address correspondence to J.A.J. (e-mail: [email protected] ). ஽ RSNA, 2008 Radiology: Volume 248: Number 3—September 2008 737 REVIEW FOR RESIDENTS: Radiographic Evaluation of Arthritis Jacobson et al adiography is commonly used in In part 1 of this review (1), common level of physical activity. For example, the evaluation for arthritis. A ba- inflammatory arthritides were dis- one of the first joints that may demon- Rsic algorithm based on radio- cussed. The present review will first fo- strate osteoarthritis is the acromiocla- graphic findings can be followed to cus on degenerative joint diseases, vicular joint, where minimal osteophyte reach a final and usually correct diagno- which include typical osteoarthritis as formation may be seen in the 4th de- sis (Fig 1). While it is impossible to well as less typical forms of osteoarthri- cade of life and beyond, owing to the include all forms of arthritis with their tis, as may be seen with trauma, crystal stresses that occur at this joint (Fig 4). variations into one scheme, this algo- deposition disease, and hemophilia. Fi- Another site of typical osteoarthritis is rithm can be used as a framework for nally, variations from the algorithm will the first carpometacarpal joint, often evaluation, as it encompasses the most be discussed, including conditions such beginning after the 5th decade of life, frequent radiographic features of com- as juvenile chronic arthritis, inflamma- owing in part to stresses related to con- mon arthritides. tory osteoarthritis, and gouty arthritis. stant use of opposing thumbs or joint The starting point for the algorithm laxity (Fig 5a) (3). Osteoarthritis also is joint space narrowing. The next step characteristically involves the interpha- is to determine if the joint process is Degenerative Joint Disease langeal joints of the hands after the 4th inflammatory or degenerative. While an A degenerative process is suspected or 5th decades of life; this is related in inflammatory condition is suggested by when joint space narrowing, osteophyte part to degree of use and overuse (Fig osteopenia and soft-tissue swelling, it is formation, bone sclerosis, and subchon- 5b) (4). the presence of bone erosions that is the dral cysts are seen in the absence of Involvement of the metacarpopha- characteristic finding of inflammation. inflammatory changes (Fig 3). When langeal joints is not infrequently associ- Early erosions will appear as disconti- degenerative joint disease involves a sy- ated with osteoarthritis of the interpha- nuities of the thin, white, subchondral novial articulation, the term osteoar- langeal joints, although this type of in- bone plate, commonly involving the thritis or osteoarthrosis is used. Com- volvement is usually of lesser severity. joint margins (Fig 2). Uniform joint monly, joint space narrowing from osteoar- Unlike in larger joints, joint space nar- space narrowing may also be present. In thritis is associated with osteophyte rowing of the interphalangeal and meta- contrast, a degenerative cause of joint formation, especially in the knee (2). carpophalangeal joints in osteoarthritis space narrowing is characterized by os- With the hips and knees, a weight- may be symmetric. Osteoarthritis of the teophytes; bone sclerosis; subchondral bearing radiograph will improve detec- first metatarsophalangeal joint is com- cysts, or geodes; asymmetric joint space tion of early joint space narrowing. The mon beginning in the 5th decade of life narrowing; and lack of inflammatory finding of marginal osteophytes is typi- (Fig 6) and may be associated with hal- features such as bone erosions (Fig 3). cally used to detect osteoarthritis, while lux valgus deformity. the findings of joint space narrowing, As a person ages, osteoarthritis is bone sclerosis, and subchondral cysts identified involving the knee joints and are used to assess severity (2). As the hip joints, beginning after the 4th or 5th Essentials joint space narrows, the osteophytes decade of life (4). With regard to the Ⅲ With joint space narrowing, it is become larger, bone sclerosis in- knee joints, joint space narrowing is important to differentiate inflam- creases, and subchondral cyst, or ge- typically asymmetric and most com- matory from degenerative causes. ode, formation may be seen. When os- monly involves the medial femorotibial Ⅲ Typical osteoarthritis involves teoarthritis is identified at radiography, compartment, possibly with the patel- specific joints at a particular pa- it is important to consider the joint in- lofemoral compartment (Fig 7) (5). tient age. volved, the age of the patient, and the Similarly, hip joint space narrowing is Ⅲ Osteoarthritis of an atypical joint, radiographic appearance as the next asymmetric, with superior migration of at an early age, or with an atypi- step in the algorithm. the femoral head more common than cal appearance suggests other less medial migration (Fig 8) (6). Underlying common causes for cartilage de- Typical Osteoarthritis acetabular dysplasia is associated with struction. Osteoarthritis is typically the result of superolateral migration. With early hip Ⅲ An atypical appearance of osteo- articular cartilage damage and wear and osteoarthrosis, a frog leg view will often arthritis can be due to trauma, tear from repetitive microtrauma that crystal deposition disease, neuro- occurs throughout life, although ge- pathic joint, and hemophilia. netic, hereditary, nutritional, meta- Published online Ⅲ Juvenile chronic arthritis and bolic, preexisting articular disease, and 10.1148/radiol.2483062112 gouty arthritis are two types of body habitus factors may contribute in Radiology 2008; 248:737–747 arthritis that have an appearance some cases. This process tends to in- that is different from that of other volve specific joints during specific de- Abbreviation: CPPD ϭ calcium pyrophosphate dihydrate common inflammatory arthrit- cades of a person’s life and depends in ides. part on the patient’s body habitus and Authors stated no financial relationship to disclose. 738 Radiology: Volume 248: Number 3—September 2008 REVIEW FOR RESIDENTS: Radiographic Evaluation of Arthritis Jacobson et al reveal a rim or collar of osteophytes arthropathy that can appear as atypical cally involves the radiocarpal joint of that may be more difficult to visualize on osteoarthritis. Although radiographic the wrist and the second and third an anteroposterior radiograph. findings of CPPD appear somewhat sim- metacarpophalangeal joints of the The sequence of osteoarthritis de- ilar to those of osteoarthritis, they are hands (Fig 10) (6). Chondrocalcinosis scribed above can be somewhat vari- atypical because of joint distribution, of the triangular fibrocartilage is com- able. Regardless, when osteoarthritis is extensive subchondral cyst formation, mon, although calcium deposition in the identified, it is important to consider and associated calcium deposition, in- intrinsic carpal ligaments (in particular which joint is involved, the severity of cluding chondrocalcinosis. For exam- the lunotriquetral ligament) and joint the radiographic changes, the distribu- ple, CPPD arthropathy characteristi- capsules is also seen (7). In the knee, tion of osteoarthritis, and the age of the patient to make the distinction between typical and atypical osteoarthritis. Figure 1 Atypical Osteoarthritis If radiographic findings of osteoarthritis are identified but the involved joint is not one commonly affected by osteoar- thritis, the severity of the findings are excessive or unusual, or the age of the patient is unusual, then other less com- mon causes for cartilage damage and osteoarthritis should be considered. Possible causes for this atypical appear- ance of osteoarthritis include trauma, crystal deposition disease, neuropathic joint, and hemophilia. Other possible causes include congenital and develop- mental anomalies, such as dysplasia, that disrupt normal biomechanics. Trauma is the most common cause for atypical osteoarthritis. This may be a sequela of (a) a prior traumatic event that causes cartilage