Author
Herbert S. Diamond, MD
Adjunct Professor of Medicine
Division of Rheumatology
University of Pittsburgh School of Medicine
Chairman Emeritus
Department of Internal Medicine
Western Pennsylvania Hospital
Pittsburgh, Pennsylvania
Disclosure:
Herbert S. Diamond, MD, has disclosed the following relevant financial relationships:
Owns stocks, stock options, or bonds from: Merck & Co., Inc; GlaxoSmithKline; Zimmer, Inc.
Editor
Lars Grimm, MD, MHS
House Staff
Department of Diagnostic Radiology
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Reviewers
Harris Gellman, MD
Consulting Surgeon
Broward Hand Center
Voluntary Clinical Professor of Orthopaedic Surgery and Plastic Surgery
Departments of Orthopaedic Surgery and General Surgery
University of Miami
Leonard M Miller School of Medicine
Coral Springs, Florida
Disclosure: Harris Gellman, MD, has disclosed no relevant financial relationships.
Reviewers
Thomas M. DeBerardino, MD
Associate Professor
Department of Orthopedic Surgery
Consulting Surgeon
Sports Medicine, Arthroscopy and Reconstruction of the Knee, Hip and Shoulder
Team Physician
Orthopedic Consultant, University of Connecticut Department of Athletics
University of Connecticut Health Center
Farmington, Connecticut
Disclosure:
Thomas M. DeBerardino, MD, has disclosed the following relevant financial relationships:
Grant/research funds from: Arthrex, Inc; Musculoskeletal Transplant Foundation; Histogenics
Consulting fee for speaking and teaching from; Genzyme Biosurgery, Inc.
The etiology of acute monoarticular arthritis of the knee is varied. Although many etiologies can be treated electively, others require rapid diagnosis and initiation of treatment. The following brief case histories will challenge your diagnostic acumen.
A 64-year-old white man presents to the emergency department with a 1-day history of a swollen knee. He has mild chronic knee pain. During the past 5 years, he had 4 episodes of monoarticular or pauciarticular swelling that involved both ankles and both knees but no other joints. Episodes resolved after several weeks with conservative therapy. There is no history of trauma. Currently, his right knee is markedly swollen, tender, and warm. All other joints are normal except for crepitus on motion of both knees. A complete blood count (CBC) and basic metabolic profile are normal. Image courtesy of Wikimedia Commons.
Answer: E. Chondrocalcinosis
Changes consistent with osteoarthritis are present on this film, including osteophytes producing peaking of the tibial tubercles (red arrow), joint space narrowing (blue arrow) and subchondral bone sclerosis (yellow arrow). However, osteoarthritis would be unlikely to cause episodic acute arthritis affecting knees and ankles because inflammatory arthritis of the ankles is rare in osteoarthritis. Calcium pyrophosphate arthritis frequently affects the ankles and knees and is associated with chondrocalcinosis (white arrow). Calcification of the meniscus and cartilage in the knee and wrist are almost diagnostic of chondrocalcinosis.
If calcium pyrophosphate arthritis is suspected, the most helpful joint to image is often the knee because cartilage calcification is more easily appreciated on knee radiographs (arrows). Image courtesy of Wikimedia Commons.
Joint fluid examination in this patient most likely shows:
A. Rhomboid-shaped, positive birefringent crystals
B. Needle-shaped, negative birefringent crystals
C. Needle-shaped, positive birefringent crystals
D. Rhomboid-shaped, negative birefringent crystals
Answer: A. Rhomboid-shaped, positive birefringent crystals
The expected crystal in chondrocalcinosis is calcium pyrophosphate. Calcium pyrophosphate crystals are typically rhomboid in shape. They rotate the plane of polarized light in a weakly positive direction designated as positive birefringence. Crystals can be difficult to see under plain light microscopy, and therefore viewing under polarized light can be critical to establishing the diagnosis.
An 18-year-old soccer player presents with knee pain after receiving a hard tackle in a match yesterday. He reports hearing an audible pop and had sudden-onset knee swelling as shown. On examination you suspect hemarthrosis and are concerned for an anterior cruciate ligament (ACL) injury.
Which of the following tests is most sensitive for ACL injury in the early postinjury stage?
A. Pivot-shift
B. Jerk
C. Anterior drawer
D. Lachman
Answer: D. Lachman
In the Lachman test, the knee is flexed to 30 degrees and the examiner pulls on the tibia to assess the amount of anterior motion (shown), which will be increased in an ACL tear. The anterior drawer test may be negative in up to 50% of cases because the posterior horn of the medial meniscus can block translation. The pivot-shift and jerk tests assess rotational stability but are limited in the early postinjury stage.
A patient with no significant rheumatologic or orthopedic history presents after tripping the previous day and falling forward onto his left knee. Pain in the knee has progressively increased and he awoke with a swollen knee (shown). On examination, it is found that the swelling is confined to the anterior surface of the knee and is fluctuant on palpation. There is no lateral or popliteal swelling. There is slight warmth and moderate tenderness over the swollen area. The joint is stable. Image courtesy of Wikimedia Commons.
Answer: A. No finding
The joint space and bone density are normal. There is a bipartite patella seen in images 9 and 10. Note the normal soft tissue contour of the synovial border without evidence of a synovial effusion. Incidental note is made of a bipartite patella (arrow), an anatomic variant. Image courtesy of Wikimedia Commons.
The most likely diagnosis in this patient is:
A. Prepatella bursitis
B. Gout
C. Partial ACL tear
D. Ruptured Baker cyst
E. Septic arthritis
Answer: A. Prepatella bursitis
A history of trauma, the normal roentgenogram, and no evidence of a joint effusion in a patient with swelling over the patella indicate a prepatella bursitis. Septic arthritis or gout would be associated with intra-articular swelling, a torn cruciate ligament with joint instability, and a Baker cyst with popliteal fossa swelling. Image courtesy of Wikimedia Commons.
Baker cysts are found in the popliteal fossa. They result from fluid distention of the gastrocnemius-semimembranosus bursa, usually secondary to osteoarthritis or a Charcot joint. They may be identified on radiographs as a soft-tissue mass in the posteromedial knee (arrowhead) with associated degenerative changes in the knee. Ultrasound or MRI is the preferred imaging modality if there is doubt about the diagnosis.
A patient presents with chronic joint pain in both knees for many years. Pain is worsened by activity and is relieved by rest. He has rest stiffness that improves with activity. He has had increased difficulty walking over the past year and some swelling in the right knee. This has acutely worsened in the past 24 hours. On examination, there is a noted deformity of his proximal and distal interphalangeal joints. Image courtesy of Wikimedia Commons.
A knee radiograph is most likely to reveal which findings?
A. Normal knee
B. Chondrocalcinosis
C. Periarticular erosions
D. Bone cysts
E. Joint space narrowing, osteophytes, and bone sclerosis
Answer: E. Joint space narrowing, osteophytes, and bone sclerosis
The findings of osteophytes (blue arrow), joint space narrowing, and subchondral sclerosis (black arrow) are consistent with osteoarthritis. The diagnosis is suggested by the history of gradually worsening joint pain and function, the more gradual onset of swelling, the short duration of rest stiffness, and the distal and proximal interphalangeal joint changes. Chondrocalcinosis is less likely with no history of acute arthritis. Joint erosions are usually associated with inflammation and longer duration of stiffness. The chronic, localized pain makes a normal knee unlikely. Bone cysts are not usually associated with joint effusions. Image courtesy of Wikimedia Commons.
A patient is awoken from sleep by severe pain in his left knee. He also reports a recent abscess over that knee which required incision and drainage and improved treatment with a cephalosporin. The left knee is erythematous, swollen, warm, and very tender. Synovial fluid analysis reveals a white blood cell (WBC) count of 110,000/µL with 99% neutrophils. Image courtesy of Wikimedia Commons.
What is the most likely diagnosis?
A. Gout
B. Calcium pyrophosphate arthritis
C. Septic arthritis
D. Traumatic arthritis
Answer: C. Septic arthritis
Traumatic arthritis is not associated with a markedly elevated synovial WBC count. Whereas gout or, less commonly, calcium pyrophosphate arthritis, can be associated with marked inflammation, a WBC count > 100,000/µL favors acute septic arthritis. The patient's history of a recent skin infection also suggests pyogenic septic arthritis. The most common organism in patients with septic arthritis is Staphylococcus aureus, as illustrated in this Gram stain. Early diagnosis and treatment is critical for a good outcome. Image courtesy of Wikimedia Commons.
A patient presents with a mild ache in his right knee in the evening which worsened overnight to severe pain, swelling, and erythema. His medical history is negative except for 10 years of hypertension treated with a diuretic and an episode of foot pain 5 years earlier in his big toe that resolved after 2 weeks without treatment. Image courtesy of Wikimedia Commons.
The diagnostic test most likely to establish a diagnosis is:
A. Joint fluid Gram stain and culture
B. Serum rheumatoid factor
C. Joint fluid crystal analysis
D. Roentgenogram of the knee
E. MRI of the knee
Answer: C. Joint fluid crystal analysis
The acute severe arthritis with no history of trauma is most consistent with gout or septic arthritis, with the past history of first metatarsal joint pain favoring gout. Culture and Gram stain should still be performed. The diagnosis is confirmed by the needle-shaped uric acid crystals. The crystals demonstrate the strong yellow-blue color change depending on orientation that is strongly negatively birefringent. Image courtesy of Wikimedia Commons.
What is the most appropriate treatment at this time?
A. Prednisone 30-40 mg/day
B. Allopurinol 300 mg/day
C. Prednisone 40 mg/day + allopurinol 300 mg/day
D. Colchicine 0.6 mg every hour until improvement or toxicity
E. NSAIDs + low-dose colchicine + prednisone 40 mg/day to taper
Answer: E. NSAIDs + low-dose colchicine + prednisone 40 mg/day to taper
The preferred treatment for acute gout is first-line therapy with NSAIDs or with system steroids such as prednisone to taper over 7-10 days. Traditional dosing of oral colchicine has a high frequency of side effects; low-dose therapy is now recommended. Uric acid-lowering drugs, such as allopurinol, during an acute attack may provoke an arthritis flare. Image courtesy of Wikimedia Commons.
The opposite knee had a firm raised nodule anteriorly, just below the patella (shown). Aspiration of this lesion revealed thick whitish fluid which most likely contained:
A. Polymorphonuclear leucocytes
B. Uric acid crystals
C. Bacteria
D. Leucocytes and crystals
E. Fatty tissue
Author
Herbert S. Diamond, MD
Adjunct Professor of Medicine
Division of Rheumatology
University of Pittsburgh School of Medicine
Chairman Emeritus
Department of Internal Medicine
Western Pennsylvania Hospital
Pittsburgh, Pennsylvania
Disclosure:
Herbert S. Diamond, MD, has disclosed the following relevant financial relationships:
Owns stocks, stock options, or bonds from: Merck & Co., Inc; GlaxoSmithKline; Zimmer, Inc.
Editor
Lars Grimm, MD, MHS
House Staff
Department of Diagnostic Radiology
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Reviewers
Harris Gellman, MD
Consulting Surgeon
Broward Hand Center
Voluntary Clinical Professor of Orthopaedic Surgery and Plastic Surgery
Departments of Orthopaedic Surgery and General Surgery
University of Miami
Leonard M Miller School of Medicine
Coral Springs, Florida
Disclosure: Harris Gellman, MD, has disclosed no relevant financial relationships.
Reviewers
Thomas M. DeBerardino, MD
Associate Professor
Department of Orthopedic Surgery
Consulting Surgeon
Sports Medicine, Arthroscopy and Reconstruction of the Knee, Hip and Shoulder
Team Physician
Orthopedic Consultant, University of Connecticut Department of Athletics
University of Connecticut Health Center
Farmington, Connecticut
Disclosure:
Thomas M. DeBerardino, MD, has disclosed the following relevant financial relationships:
Grant/research funds from: Arthrex, Inc; Musculoskeletal Transplant Foundation; Histogenics
Consulting fee for speaking and teaching from; Genzyme Biosurgery, Inc.
Critical Manifestations of Lupus
Distinguishing Rheumatologic Diseases on Plain Radiography
Fibromyalgia
Osteoporosis
