The Wizard's potion
These are some of Don's interesting comments from the Friday morning case conferences. Any errors in this section are solely the poor recording of otherwise accurate comments, due to the pressure of the quantity of interesting comments. This section is updated weekly.
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This page last updated on 05/06/2003 09:56:57 PM
Scripps conference 4/10/03: from Christine Lamoureux
1) Case of a 90 year old female with osteoarthritis (OA) of the hand characterized by interphalangeal joint space loss, osteophyte formation, and a wavy appearance of the digits. For the diagnosis of erosive (inflammatory) osteoarthritis, erosions and subchondral collapse should be present. Periarticular calcifications can be seen in cases of OA with secondary crystal deposition. With gout, nodules or tophi may be present. With CPPD, linear calcifications may be seen within the capsule. Calcium oxalate deposition is also possible, as is hydroxyapatite deposition (HADD). HADD is seen in about 20 % of cases of OA, and is characterized by "cloud-like" calcification at the joint, possible capsular distension, masses, and inflammatory symptoms. Scleroderma may mimic it. Many such cases with HADD may show evidence of CPPD at the wrist and these two entities may be present at the same time.
2) Calcified bodies in the suprapatellar pouch of the knee on plain film: differential includes neuropathic joint, OA, CPPD, etc. Pieces of cartilage are broken off and float in the joint or may be resorbed into the synovial membrane. In idiopathic synovial osteochondromatosis, there is metaplasia of the synovial lining into cartilage nodules. These are usually in the presence of a "ggod" joint, and the pieces are of uniform size and are spherical. If they are exclusively in the suprapatellar pouch, this may be due to the presence of a plica with or without a porta; compartmentalization can then occur, promoting their formation.
3) Lipoma arborescens: in the joint where this occurs, fluid tends to predominate over fat in many cases. Interestingly, in some cases at the knee, if there is a popliteal cyst, this may be devoid of fatty involvement. Lipoma arborescens may be primary or secondary. If primary, it is common in the young, and the joint is good. If secondary, it is due to RA or OA. With this entity, it is rare to get bone erosion, and there is no malignant potential. Treatment at present is open synovectomy.
4) Low or intermediate signal intensity mass on all sequences adjacent to the dorsal aspect of the talus with erosive change of the dorsal talus: consistent with localized nodular synovitis. This process may be associated with a joint or tendon sheath and is related to PVNS. It may not have hemosiderin associated with it; it is benign and fibrous. More commonly found in the knee where it involves the Hoffa's fat pad or cruciate ligaments. ??Possible alternate etiology for these findings in the ankle such as impingement and related scar tissue deposition (Dr Pathria).
5) Ankylosing spondylitis in the spine characterized by anterior syndesmophytes: a distinguishing feature is the absence of lucency between the syndesmophyte and the vertebral body which can be seen in DISH. Facet arthropathy is present on AS. If traumatic fracture occurs which can go on to pseudarthrosis, it is most commonly at the disk level where the syndesmophytes are thinner. A mimic of fracture here can be due to incomplete syndesmophyte formation at one level. Bone scan was a method used to diagnose fracture in the past; MRI is useful now for evaluation of the presence of marrow edema. Fractures at the cervical spine have the worst prognosis.
6) Case of anterior cervical spine bone formation with OPLL, and indistinct diskovertebral joints. Differential includes unusual ankylosing spondylitis, DISH or sternoclavicular joint hyperostosis (SCCH). SCCH occurs in older people and is characterized by ossification at the sternoclavicular joints on CXR which can sometimes mimic lymphoma. There may be pustules on the hands and feet as well. This entity is a subgroup of SAPHO.
7) Fusion of the upper and lower cervical spine vertebral bodies with ossification of the facet joints and fusion of the spinous processes: differential is Klippel-Feil vs JRA. When fusion of the spinous processes is present, it excludes an acquired process.
8) Paget's disease on MRI: may have the same signal intensity as muscle on the fluid-sensitive sequences. Early descriptions of Paget's stressed the importance of looking for preservation of the fat background within the affected bone to exclude malignant transformation. However, fat can be obscured in the early osteolytic phase of Paget's and in the chronic phase (cyst formation). Bottom line is, if there is a fat background, sarcomatous degeration is unlikely; if there is no fat, all bets are off.
9) CPPD in the hand: involves classically the second and third MCP joints which may have ulnar deviation. Mechanical erosions of the DRUJ may occur. Destructive changes in the lower c-spine may be seen and can have a "neuropathic look."
10) Soft tissue calcification adjacent to the ischium bilaterally can be seen in CPPD. Tendon deposition is most commonly seen in the tendons of the rotator cuff, quadriceps, gastrocnemius, and Acilles, but is likely much more widespread as seen in cadaveris studies. May predispose to tendon rupture--effects in ligaments not well known.
11) Hydroxyapatite deposition in the soft tissues anterior to the humerus, proximal shaft: may occur within the pectoralis, latissimus, teres or biceps tendons. Biceps is most common. Bone erosions can be seen. Differential includes migration of bodies into the region.
12) Wrist case: CPPD vs gout (mass in soft tissues adjacent to the ulnar styloid): erosions favor gout. On MRI, low signal in the wrist joints, carpal bone involvement. Polyarticular involvement--tophaceous gout is favored.
13) Muscle edema involving the coracobrachialis, teres minor, infraspinatous, short head of biceps. Differential is neurologic (entrapment) vs idiopathic) or Parsonnage-Turner. The coracobrachialis is supplied by a musculocutaneous brach of C7, not the axillary nerve; in Parsonnage-Turner, multiple nerves are affected, namely suprascapular and axillary. Etiology of the pattern of edema in this case is uncertain.
14) RSD in the midfoot: resembles septic arthritis, but with preservation of the joint spaces is more likely a partial form of RSD. The partial forms of RSD are : ray-like, involving 0ne or two toes or fingers, and zonal (hip, knee), involving 1/2 of the joint. Patial involvement can occur in the foot, as in this case. Few reports exist re MRI distinguishing features.
April 4, 2003: from Christine Lamoureux
1) SONK (spontaneous osteonecrosis of the knee) was first reported by Scandinavian reports in the 1960's. Characterized by abrupt onset of pain, often pinpointed to a certain specific time the patient could recall. Involves the medial femoral condyle, eventually with flattening, and was described as an impotant cause of osteoarthritis. Mainly diagnosed on bone scan back then. Currently, the process is felt to be osteonecrosis/insufficiency fracture involving elderly women. Associated with cartilage loss and secondary insufficiency fracture. Involves most commonly the weight-bearing surface of the medial femoral condyle. Can less commonly involve the lateral femoral condyle, medial tibial plateau, and lateral tibial plateau (in order of decreasing frequency). Reports from Belgium have identified three major prognostic indicatores for the liklihood for progression to further collapse: persistent low signal on T1WI (involving an area at least 7mm x 17 mm), insufficiency fracture about 1 cm from the end of the bone, and flattening of the condyle. The same rules are similarly applied to transient edema of the femoral head.
2) Chronic PHAGL (posterior humeral avulsion glenohumeral ligament): usually seen with recent acute injury, associated muscle edema (teres minor). May be confused with iatrogenic leaking of contrast into the pec after arthrogram, or may be due to age-related degeneration of the inferior band of the inferior glenohumeral ligament (Mini Pathria).
3) Bennett lesion: enthesopathy at the scapular atachment of the posterior band of the Inferior glenohumeral ligament, capsule or triceps tendon attachment. If it is due to the posterior band of IGHL, it is due to chronic subluxations. New bone formation at the scapula may also be due to an axillary pouch tear, due to chronic irritation by synovial fluid possibly.
4) Anterior shoulder dislocations: subcoracoid and subglenoid. Subcoracoid is the most likely mechanism and the type most likely to recur. There are differences in the types of associated fractures and labral pathology.
5) Shoulder arthrography tips: use less on older patients (no more that 122 cc on anyone, use a 20 gauge needle, do NOT exercise the patient before the MRI, do the ABER view last to decrease extravasation. Exercise is OK with knee arthrography.
With shoulder arthrography, the subcoracoid bursa may be entered with the needle, resulting in a bursagram, as it communicated with the SASDB 20 % of the time.
6) Subcoracoid external impingement: less than 6 mm from the humeral head to the coracoid process. First described on CT--may be due to deltoid muscle pulling humeral head forward; Dr Pathria questions whether this may be due to a subscaularis tear.
7) Bankart lesions, bony or not, can scar down, and if they are not displaced, can mimic chronic ALPSA lesions.
8) Suprascapular nerve innervates the suprispinatous, infraspinatous and teres minor muscles. Compression by a ganglion cyst may affect the supraspinatous muscle when in the suprascapular notch, and the infraspinatous muscle when in the spinoglenoid notch. Vessels are often dilated near these regions in the presence of a ganglion and this may be due to their compression. Treatment for these ganglions are steroid injections which can improve symptoms without actually shrinking their size.
9) TB vs transient osteoporosis of the hip: in TB, the joint space can be preserved. Pannus grows across the cartilage or can be subchondral, with "mushrooming" through the cartilage, piercing the subchondral bone plate. Transient osteoporosis can also result in a normal joint space, but the subchondral bone plate is intact.