LECTURE 6 - finished

Question 1

What are some indications for arthroscopy?

Answer 1

• Evaluation of knee meniscus, cartilage or ligament damage
• To aid in providing differential diagnosis of acute and chronic knee disorders
• A safe & convenient alternative to open surgery
• To monitor the progression of joint disease
• To monitor the effectiveness of a particular therapy
• To record visual findings by attaching a camera to the arthroscope

Question 2

What are contraindications for an arthroscope?

Answer 2

• Joint ankylosis: manoeuvring the arthroscope is often impossible
• Local skin or wound infections

Question 3

What are some complications of a joint arthoscope?

Answer 3

SHIT JS

• Swelling
• Haemarthrosis
• Infection
• Thrombophlebitis
• Joint trauma
• Synovial rupture

Question 4

What is arthrography? How is it performed and what is produced in the end?

Answer 4

A contrast medium is injected into the joint using fluoroscopy to guide needle placement.

A series of X-rays/MRIs/CTs are then taken of the joint.

The process results in the production of an arthrogram.

Question 5

What is an arthroscope? How is it performed and what is it done for?

Answer 5

Arthroscopy is a procedure during which the internal structures of a joint are examined.

A small incision is made in the joint, through which an endoscope (arthroscope) is inserted. The joint structures are illuminated and diagnostic images taken.

Arthroscopy can also be used to treat conditions e.g. arthroscopic surgery to repair meniscal tears in the knee, removal of blood in hemarthrosis etc.

Question 6

What is Osteochondritis dessicans? What do patients complain of in this condition? What joints is it commonly seen in?

Answer 6

A loss of blood supply in a section of bone can result in a piece of bone and cartilage separating from the rest of the bone.

It may remain in place or enter the joint space, making the joint unstable.

Patients complain of pain and sensations of the joint locking or giving way

Usually seen in the elbows and knees

Question 7

Indications for arthrography?

Answer 7

Arthrography is mainly used to diagnose the cause of persistent, unexplained knee and shoulder pain

Question 8

Contraindications for arthrography?

Answer 8

Arthrography is contraindicated in patients who:
• are pregnant
• have active arthritis
• have joint infections
• are allergic to contrast media

Question 9

What are the main methods of synovial biopsy?

Answer 9

The main biopsy methods are:
• needle
• surgical (i.e. open)
• arthroscopic

Question 10

Indications for synovial biopsy?

Answer 10

Mainly used to exclude:
• tuberculosis
• sarcoidosis
• villonodular synovitis
• synovial tumours, etc.

Synovial Biopsy may also assist the diagnostician when the clinical presentation, and other diagnostic procedures have failed to yield a diagnosis

Question 11

What are typical synovial biopsy findings in RA?

Answer 11

The typical histological findings in RA are:
• massive lymphoid infiltration
• germinal centres in the deeper layers of the synovium
• hyperplasia of the synoviocytes
• villous formation of the synovium

Question 12

What are the limitations of synovial biopsies?

Answer 12

There is nothing diagnostically specific about chronic inflammation.
Identical appearances may in different inflammatory conditions
E.g. PsA biopsy might look the same as RA

Question 13

What are the 3 methods of diagnosis of osteoporosis?

Answer 13

Radiographic and ultrasound measurements of bone density
Laboratory biochemical biomarkers
Bone biopsy with pathologic assessment

Question 14

What is a DEXA scan? What condition is it the “technique of choice for diagnosis and managment”?

Answer 14

DEXA is a radiographic technique that allows bone mineral density (BMD) to be determined.

It is the technique of choice in the diagnosis & management of osteoporosis

Question 15

What regions are assessed in a DEXA?

Answer 15

Lx spine
Hip
Forearm

** whole body can also be done

Question 16

Indications for DEXA?

Answer 16

• To assess the risk for fracture in the hip, spine, & wrist
• To monitor changes in bone density during osteoporosis treatment

Question 17

What are the advantages of using DEXA scans?

Answer 17

Greater precision, accuracy and sensitivity
Produces high resolution images
Low levels of radiation
Takes <5 minutes
Results are highly reproducible

Question 18

What are the limitations of DEXA?

Answer 18

When assessing BMD in the postero-anterior measurement of the lumbar spine, a number of conditions may artificially increase the bone density reading
These conditions are:
• Osteophytes
• Aortic calcifications
• Degenerative hypertrophy of the facet joints
• IVD space narrowing
• Collapsed vertebrae
• Obesity

Furthermore, DEXA requires experienced and qualified staff to operate the equipment

Question 19

How are DEXA scored?

Answer 19

DEXA results are generally scored by two measures, the T-score and the Z-score.

Z and T scores provide clinically relevant information.

Scores indicate the amount one’s bone mineral density varies from the mean. Negative scores indicate lower bone density, and positive scores indicate higher.

Both measures are based on the statistical unit: Standard Deviation

The Z-score is the comparison to the age-matched normal. It is usually calculated in cases of severe osteoporosis

The Z-score is the number of standard deviations away from the average BMD for a person of the same age, race and gender.

Question 20

What is the clinical significance of the Z score in DEXA?

Answer 20

With DEXA of the hip there is a relative fracture risk of about 2.5 for each standard deviation.
i.e. a person with a z-score of -1 has 2.5 times the chance of a hip fracture compared to a woman with an average bone density.

The actual fracture risk cannot be calculated unless you also know the risk of an average person
This will depend on age, race, gender and other factors

Question 21

What are the limitations of the Z-score?

Answer 21

Because low BMDs are common among older adults, comparisons with the BMD of a typical individual whose age is matched to yours can be misleading

Therefore, the diagnosis of osteoporosis is based on the T-score.

Question 22

In which people is a Z-score indicated? (3)

Answer 22

Because of its limitations, the z score is mainly used in:
• premenopausal women
• men <50
• children

In these individuals, a z < -2SD indicates the possibility of a comorbidity contributing to the development of the osteoporosis e.g.
• glucocorticoid therapy
• hyperparathyroidism
• alcoholism etc.

Question 23

What is a T-score?

Answer 23

The Z score may also be compared with young normals.

This comparison yields a “T-score”, which relates more closely to fracture risk.

The T-score is the number of standard deviations away from the average for a young adult at peak bone density

Question 24

What is the T-score mainly used for?

Answer 24

Screening patients for osteoporosis

Question 25

When determining the reference BMD for a T-score, what must be considered?

Answer 25

The reference BMD depends on:
• The bone densitometer
• Skeletal site (hip, spine etc)
• Race
• Gender
• The population studied

Question 26

What is the clinical significance of the T-score?

Answer 26

The T score is an approximation of what the patient’s BMD should have been at their peak bone density at about age 20
As a general rule, for every SD below normal, the fracture risk doubles.

Thus, a patient with a BMD of 1 SD below normal (T-score is -1) has 2 times the risk of fracture as a person with a normal BMD
If the T-score is -2 the risk of fracture is 4 times normal
A T-score of -3 is 8 times the normal fracture risk etc.

Question 27

What are the advantages of Quantitative US?

Answer 27

• Radiation-free
• Simple & Inexpensive
• Portable
• Non-invasive
• Predicts future fracture risk
• Potential for widespread application (including screening for prevention)

Question 28

What are the disadvantages of Quantitative US?

Answer 28

Screening for osteoporosis with QUS is not regarded as appropriate by most authorities because:
• Relatively poor precision
• Correlation with DEXA is poor