Don's gem's July-August 01

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.

This section has outgrown it's page and been subdivided. Previous sections are linked below.

2001             July August September October November December
2002 Jan Feb March                  

August 31st 2001

1. Chondrosarcoma transformation in primary synovial osteochondromatosis is very rare.

2. Meniscal cysts are reported as being twice as common medially.

3. Meniscal cysts often need open surgery.  If the location is difficult to reach through an open portal then a limited arthroscopic fenestration may suffice.

4. Fibrolipomatous hamartoma is commonest on the median nerve and next commonest on the ulna nerve.  Fatty infiltration is seen in the adjacent soft tissues, and there may be macrodactyly.  There may be a connection with macrodystrophia lipomatosis.

5. Perilabral glenoid cysts are seen in weightlifters.  Gas can occur in ganglion cysts.  They can extend from the suprascapular to the spinoglenoid notch.  Those in the suprascapular notch tend to be associated with compression neuropathy of the supraspinatus muscle, and the spinoglenoid notch ones with infraspinatus.  Teres minor nerve can be compressed in the quadrilateral space, but not superiorly.

6. With the intersection syndrome of the 2nd dorsal compartment the fluid tracts proximally along the ECR and EPL tendons.

7.Morton's neuromas (fibroma) can enhance and can be high signal on T2FS.

8. The superior peroneal retinaculum passes from lateral calcaneus to fibula.  It can avulse in trauma.  Occasionally it can insert on the achilles.  It is part of a continuous posterior retinaculum.

9. Tendon tears;     Type 1 thickening with longitudinal split.

                            Type 2 thinning

                             Type 3 complete

10. If ulna plus variance, check for proximal radial fracture or interosseous ligament injury.

11. Vascular malformations; 4 types

    High flow,     Haemangioma in child - resolves, don't treat.

                        AVM - don't resolve. i.e. Klippel Trenauney Webber, infact grow.

    Low flow,     Venous malformations - slow flow, phleboliths, fluid/fluid levels



    (Check with Jerry)

August 24th 2001 Rheumatology

1. Rarely primary amyloid may mimic RhA.

2. Relapsing polychondritis can cause rapid joint space loss.

3. Severe skin psoriasis can cause gout.

4. Paget's progresses at a set rate along a bone.  Paget's causes a cotton wool skull.


August 24th 2001

1. When a meniscus is displaced there is often bone marrow oedema of the adjacent tibial plateau.

2. Tibial plateau OCD can be seen with ACL tears.

3. Anterolateral rotational instability, is internal rotation and anterior translation of the tibia on the femur, causing ACL tears. The accompanying bone bruises are the midportion of the lateral femoral condyle and the posterolateral tibia.  If there is accompanying fibula oedema then there is likely a posterior lateral corner injury as well.

4. Lateral meniscus tears are more common with ACL tears.

5. O'Donoghue's terrible triad relates to anteromedial instability, with ACL tear, medial meniscus and medial collateral ligament tears.

6. Anterolateral impingement at the ankle is related to XS scar tissue on the injured anterior talofibular ligamnet.

7. Peroneus cordis is an accessary muscle that attaches to the lateral calcaneus.

8. Rarely when the proximal biceps tendon ruptures it retracts to the proximal forearm, this is called a sling shot.


August 23rd 2001

1. Syndesmophytes anteriorly are more prominent in Cx spine when the posterior elements are not fused and viceversa.

2. When there is a zig zag radial and ulna deformity of the wrist and MCPJs, it is necessary to correct the proximal deformity first.

3. Deforming non-erosive arthropathy; SLE, Jacouds, Scleroderma, poly and dermatomyositis, Ehler's Danlos, and hypergammaglobulinaemia.

4. Jacoud's principally involves the 4th and 5th rays.

5. Paget's tends to spare the ribs and fibula.

6. Mets to Paget's are not common.  Lymphoma may go to Paget's.  Lytic Paget's loses fat signal.

7. A notch may be seen superiorly on the ischium with an old ischial avulsion injury.

8. The 'tract' sign of hypertrophic osteoarthropathy is high signal on T2FS adjacent to bone.  HOA can be painful and simulate arthritis.  They may also have synovitis and joint effusion.  TB is the only chronic lung disease not to cause HOA.  CF and lymphoma are the common causes in children.  Primary HOA or pachydermoperiostosis tends to be more exuberant, but this may just be time related and is also seen in congenital heart disease.

9. Muscles which cross two joints are more prone to musculotendinosis indirect injury.

10. Marked oedema can accompany chondroblastoma, and osteoid osteoma..

11. ABC can occur secondarily in GCT, Chondroblastoma, Osteoblastoma, Fibrous dysplasia and Chondromyxoidfibromas.

12. Rapid enlargement of fibrous dysplasia can occur in women on oestrogens due to ABC formation.

13. The more posterior the extent of cervical fusion, the more likely it is congenital.


August 17th 2001

1. A corner defect at the medial tibial plateau on an AP x-ray suggests an inferiorly displaced tear of the medial meniscus.

2. Signs that suggest a discoid meniscus on the plain X-ray are: a hypoplastic femoral condyle, a hypoplastic fibula head, and cupping of the tibial plateau.  On MRI thickening of the ligament of Wrisberg may also occur.

3. A posterior HAGL can be associated with injury to the short head of triceps attachment.

4. Following ACL reconstruction if the tibail tunnel is too steep there may be ligament impingement ,a dn if too shallow the ligament will not give good support.

5. Post op low signal in the anterior fat pad (Hoffa) is known as arthrofibrosis.

6. The ligamentum mucosa is an inferior plica connecting the patella to the posterior intercondylar notch.  It can become thickened post operatively.

7. The accuracy of post operative MRI arthrography for assessing for retear of the meniscus is dependant on the size of the meniscal remnant, with larger remnants having greater accuracy.  The type of contrast, Gd or Iodine is less important.  MRI arthrography is more accurate than conventional arthrography.

8. Parasympyseal insuffiency stress fractures can mimic tumours in their appearance.

9. Posterior superior impingement occurs in the throwing athlete.  It is associted with multidirectional instability. There is undersurface tears of the infraspinatus and adjacent bony pits/cystic change in the greater tuberosity.  Also there are tears of the posterior labrum.

10. TB involves the pedicles of vertebrae more often than pyogenic.

11. Gout of the patella tends to produce superolateral erosions.

August 10th 2001

1. Discoid meniscus occurs in only a small percentage (1-2%) of people laterally and is rare medially.  When present there is often associated prominence of the ligament of Wrisberg, which is also more oblique than usual. The cause is unknown, since the meniscus is never developmentally meniscoid normally.  Central high signal in the discoid meniscus implies a tear, which is often cavitation due to horizontal shearing of the superior and inferior surfaces.

2. With ulna plus variance, there is not just a central attritional tear of the TFC, but also attritional tearing of the lunotriquetral ligament and lunate abuttment. 

3. There are four possible routes from the radiocarpal compartment to the midcarpal compartment, all abnormal. Via scapholunate, lunotriquitral, pisotriquetral and lateral to scaphoid.

4. The major volar radiocarpal ligaments are; Radioscapholunate, radiolunotriquetral and radioscaphocapitate.

5. Kienboch's of the lunate is possibly a stress fracture.

6. A longitudinal split of Peroneus brevis tendon is predisposed to by a flat retromalleolar groove and a low PB muscle insertion on the tendon.

7. Add digiti minimi muscle in the foot is innervated by the first branch of the lateral plantar nerve.

8. On a sagittal view the posterior horn of the medial meniscus should be larger than the anterior horn.

9. Dorsal Triquetral fracture may be an impaction with the ulna styloid or an avulsion by the dorsal radiocarpal ligament.

10. Normal compartment pressure is less than 5mmHg. Definately abnormal when above 30.  Distal pulses are preserved.

11. DOMS, delayed onset of muscle soreness is due to unusual exercise in a muscle group and has high signal on T2FS images.

12. Normal red marrow is still 50% fat.  It has low signal on out of phase images.

13. Bone infarcts occur in areas of fatty, not haemopoietic marrow.


August 7th 2001

1. A pseudotumour of the distal radius can occur following  distal radial fracture in childhood. This occurs when the periosteum is lifted off the bone, but not disrupted, and fat becomes trapped in the fracture line.  This produces a lucency adjacent to the fracture on follow up studies.

2. Multiple hereditary osteochondromas (Hereditary multiple exostoses, Diaphyseal achalasia) is diagnosed when there are greater than 2 or osteochondromas and associated modeling deformities of bone.  It virtually always involves the knee, which is the site to x-ray for confirmation.  Figures of malignant degeration are usually overstated, but approximately 1% f osteochondromas (not patients) become malignant.  At the knee, anterior osteochondromas tend to be sessile and posterior ones pedunculated.  They should stop growing at the time of physeal closure, unless malignant.

3. Gas forming infection of the disc space is extremely rare.  Forced extension of the spine with fluoroscopy may produce a vacuum appearance in a degenerative disc and exclude infection.  Gas is also a good sign during the recovery phase of disc space infection, indicating recovery.

4. Concerning melorrheostosis; bone scan can be hot unlike the other benign sclerosing bone dysplasias of osteopoikilosis and osteopathia striatum. They tend to present with secondary joint problems.  It can be associated with fatty tumours when involving the spine.  This is interesting since fatty tumours can have marked sclerosis, such as LSMFTB.

5. Transient bone marrow oedema (transient osteoporosis) is commoner in men, but in women has a predilection for the left when associated with pregnancy.  There is no left hip predilection in men.  Most just resolve, some can recur in the other hip, rarely it migrates to other areas. Treatment is non-weightbearing for fear of fracture.

6. Hook of hamate fractures can be associated with the Guyon canal syndrome due to pressure on the ulna nerve producing a neuropathy.  Mid carpal row fractures are often transverse; hook, dorsal triquetral, distal pole of scaphoid, trapezoidal ridge fracture on radial side of carpal tunnel retinaculum.


August 3rd 2001

1. Pitt's synovial herniation pits are in an anterolateral location on the femoral neck.  May occur in elite athletes, may be positive on bone scan. Possibly due to iliopsoas tendon friction

2. Segond fractures occur with internal rotation at the time of varus stress.  ACL injury associated. The fracture is an avulsion by a combination of the lateral capsule, the anterior oblique band of the fibular collateral ligament and a posterior portion of the ilio tibial band.  There islittle oedema because it tis an avulsion injury.

3. Resorption of bone may occur at the distal radioulnar joint in scleroderma.

4. There are two processes on the lateral calcaneus; the peroneal tubercle, also known as the trochlear process which passes between peroneus longus and brevis tendons and the site for attachment of the calcaneo fibular ligament.

5. The TMJ disc usually displaces anteromedially when the posterior attachments are lost.

6. There are 3 facets on the patella, the lateral, medial and odd or most medial.

7. Rectus femoris tendon makes up most of the superficial continuous fibres in the grooves on the anterior patella, passing all the way to the tibial tubercle.

8. Spontaneous osteonecrosis of the knee (SONK) is more common in women than men, in an older age group, and is commonest on the medial femoral condyle, then lateral, then medial tibial plateau, and least common in the lateral tibial plateau.

9. Differential diagnosis for os acetabuli includes calcium hydroxyappetite in the reflected head of the rectus femoris. This is where it merges with the ilio femoral ligament at the supra acetabular fossa.


July 27th 2001

1. 70% of distal radial fractures have a soft tissue injury of the carpal region on MRI.

2. The Intersection syndrome is the name given to a De Quervain's type condition affecting the 2nd dorsal compartment, due to the crossing over of the extensor carpi radialis tendons (longus and brevis) and the extensor pollicis longus.

3. The flipped meniscus usually goes from posterior to anterior in the lateral compartment.

4. The Parsonage Turner syndrome of a post viral neuritis affecting the rotator cuff can also affect the ipsilateral phrenic nerve causing a raised hemidiaphragm.

5. Shoulder impingment can be subdivided into internal and external types. 

    External can be due to Sub acromial (classical) or sub coracoid.

    Internal can be anterior at the rotator interval or posterior which occurs during the cocking and early acceleration phases of throwing athletes who may also have multi directional or anterior instability.

6. A periosteal sleeve avulsion injury can be seen at the patella or distal clavicle.

7. Infection should be high on the list of causes for a bursitis of the olecranon or patella bursa due to there superficial position.

8. The ACL can act as a route of tumour spread across the knee.

9 Collagen vascular disease causes proximal migration of the thumb metacarpal.

10. Hyperparathyroid erosions predominate on the ulnar side of the IP joints.

11. fat necrosis can occur in the bone marrow in pancreatic disease/panniculitis.

12. The more atypical features of arthritis suggests sero neg.  i.e. lack of osteoporosis, wrist predominence.

13. Transient osteoporosis is now called transient bone marrow oedema.  Commoner on the left in females, but commoner in males.  Bilateral is unusual.

14. Adult onset Stills causes midcarpal compartment symmetry.