1. 1983-1984 Carlos Pineda Roger Kerr

2. Roger Kerr, Los Angeles, CA 49 year old male with 6 month history of wrist pain and swelling. Past medical history is negative. PE: exquisite tenderness over distal ulna with loss of extension of 4 th and 5 th fingers. Routine laboratory studies are negative.

3. PA view of wrist: Enlargement of ulnar styloid with lytic/erosive change and soft tissue swelling. 49 year old male with 6 month history of wrist pain and swelling.

4. Coronal T1- weighted image: intermediate signal intensity mass surrounds and engulfs ECU tendon with erosion of distal ulna. 49 year old male with 6 month history of wrist pain and swelling.

5. Sagittal T1-weighted image: intermediate signal intensity mass surrounds and infiltrates ECU tendon. 49 year old male with 6 month history of wrist pain and swelling.

6. Consecutive axial T1-weighted images at level of ulnar styloid: ECU tendon is replaced by predominantly intermediate signal intensity mass that erodes distal ulna. 49 year old male with 6 month history of wrist pain and swelling.

7. Axial T1-weighted and axial T2-weighted images, respectively, at level of tip of ulnar styloid: mass of predominantly intermediate signal intensity has replaced ECU tendon and erodes ulna. 49 year old male with 6 month history of wrist pain and swelling.

8. Bone scan revealed increased uptake of radionuclide at both 1 st MTP joints, ankles and knees and at left midfoot and left shoulder. 49 year old male with 6 month history of wrist pain and swelling.

9. Differential diagnosis Tophaceous gout Tendon sheath lesions: giant cell tumor, fibroma, xanthoma Tuberculous tenosynovitis Rheumatoid arthritis with fibrous pannus Amyloidosis Clear cell sarcoma

10. Dx: Tophaceous gout of tendon At surgery ECU and EDC (4 th,5 th ) tendons were debrided of chalky material and crystalline deposits. Histology: crystals with strong negative birefringence, dense fibrous connective tissue and mild chronic synovitis.

11. Gout of tendon: usually in patient with established diagnosis of gout. Tendon infiltration, tenosynovitis, tendon rupture, entrapment neuropathy. Often mis-diagnosed clinically as tumor or tumor-like lesion. Gout: usually heterogeneous intermediate to low signal intensity on T2-weighted images related to fibrous tissue and urate crystals. Intense gadolinium enhancement. Dx: Tophaceous gout of tendon

12. Roger Kerr, Los Angeles, CA 5 year old male presents with a 2 day history of pain and swelling of left knee. Vague history of knee pain 4 weeks ago treated with NSAIDS. No history of trauma or recent infection. No other joint problems. WBC=9.4; ESR=44; Febrile (up to 102)

13. Lateral radiograph of the knee 5 year old male presents with a 2 day history of pain and swelling of left knee.

14. AP radiograph of the knee 5 year old male presents with a 2 day history of pain and swelling of left knee.

15. Immediate (A) and delayed (B) 99mTc MDP images were interpreted as consistent with septic arthritis with no evidence of osteomyelitis. AB 5 year old male presents with a 2 day history of pain and swelling of left knee.

16. Joint aspiration yielded cloudy fluid with 80,000 WBC/mm 3 (99% PMNs) and 100,000 RBC/mm 3. Arthroscopic drainage and debridement of the joint was performed on the third hospital day. Patient was treated with IV antibiotic (Ceftazidine, then Vancomycin) but knee swelling and pain and fever persisted. On day 10, an MRI was obtained. 5 year old male presents with a 2 day history of pain and swelling of left knee.

17. A sagittal T2- weighted image reveals a large joint effusion, synovial hypertrophy, intra- articular debris and a large high signal intensity lesion of the patella c/w septic arthritis and osteomyelitis/bone abscess. 5 year old male presents with a 2 day history of pain and swelling of left knee.

18. A B B C Successive axial intermediate-weighted images reveal extension of this lesion through the anterior cortex of the patella.

19. Diagnosis: septic arthritis of the knee and osteomyelitis/bone abscess of the patella Incision and drainage of the patella was performed and purulent fluid was removed. Histology revealed acute and chronic inflammation and Staph aureus was cultured. The patient recovered following a course of IV, followed by oral, antibiotics.

20. Osteomyelitis of the patella Rare – usually due to direct implantation from a break in the skin, puncture wound, septic bursitis or septic arthritis. Hematogenous spread to patella is exceedingly rare; rich blood supply and no physeal plate with its sluggish hemodynamics. Acute or insidious onset. Local signs or symptoms vs. systemic illness. Diagnosis is often delayed or overlooked as clinician assumes patient only has joint, bursal or soft tissue infection.

21. Osteomyelitis of the patella Clue to diagnosis: pt. not responding to standard management of septic arthritis. Surgical debridement indicted for subperiosteal/bone abscess or chronic osteomyelitis. In this patient, radiographs and bone scan were negative for osteomyelitis due to immaturity of patellar development. MRI was definitive. Roy DR et al: Osteomyelitis of the patella in children. J Ped Orthop 1991;11:364-366.