Pathology and joint replacement

Question 1

Can the cruciate ligaments repair themselves and if so why

Answer 1

Yes to a certain degree

Due to their relatively good blood supply

Question 2

Why is it important to restore normal biomechanics to an injured knee

Answer 2

Failure to do so will likely result in secondary degenerative changes due to abnormal distribution of forces and stress

Question 3

How are cruciate ligaments replaced

Answer 3

Via autologous tendon graft- usually gracilis, semitendinosus or part of patellar tendon

Question 4

What are the disadvantages to synthetic prostheses for cruciate ligament repair

Answer 4

They cannot withstand the high forces at the knee and often break
Can induce foreign body changes such as fibrosis

Question 5

What are the advantages of using an autologous tendon graft

Answer 5

Minimises foreign body change

Can preserve blood supply to enhance healing

Question 6

What are the downsides of autologous tendon graft repair

Answer 6

Still not as strong as the original cruciate and so rupture may still (rarely) occur

Question 7

Why is replacement of a damaged menisci important

Answer 7

Are poorly vascularised structures which do not easily heal on their own
Can cause locking of the joint
Removal of one reduces the knees shock absorbing capacity by 20% and can cause degenerative early changes in the contralateral compartment

Question 8

What can happen as a result of loss of shock absorbing capacity of the menisci

Answer 8

Back pain and headaches

Question 9

What type of meniscectomy is preferred and why

Answer 9

Partial as it leaves a vascularized rim which can allow regeneration to occur and maintains some stability

Question 10

What is the success of meniscus regeneration dependent on

Answer 10

Age

Is more successful in the young

Question 11

What else can be done for meniscus tear and when may this be preferred

Answer 11

Suturing of the tear may be an option for athletes who want an early return to competitive sport

Question 12

What are some indications for total knee replacement

Answer 12

Severe and unremitting degenerative bone disease such as OA or inflammatory arthritis which has been unresponsive to medical treatment

Question 13

Why are simple hinge prostheses unsuitable for knee joint replacement

Answer 13

Do not allow the normal rotatory movements of the knee so have a high rate of loosening
May have some role in sedentary patients

Question 14

What range of motion is allowed with a knee joint replacement

Answer 14

110degrees

Question 15

What happens to the PCL during knee joint replacement

Answer 15

It is most commonly removed

some debate as to whether it should be left

Question 16

Is total knee joint replacement recommended for younger patients? Justify

Answer 16

No as even though may be clinically successful with reduction of pain has a relatively high failure rate and may still be abnormalities of gait and difficulty negotiating stairs

Question 17

What is the range of motion like after total ankle joint replacement

Answer 17

Usually within normal limits but different patterns

Question 18

If joint fusion is to occur at the ankle what position should it be in and why

Answer 18

In a neutral position to allow effective heel strike to occur

Question 19

Why is total ankle joint replacement limited to those with very severe disease

Answer 19

Will not sustain activity of even a sedentary lifestyle and will eventually need conversion to arthrodesis

Question 20

Describe pes cavus

Answer 20

Claw foot
Deepening of medial longitudinal arch and projection on to lateral side of foot
In the late stages the toe prints may disappear due to secondary claw toe deformity

Question 21

Describe pes planus

Answer 21

Flat foot

Medial border of the foot drops and becomes filled in looking on footprint

Question 22

Are pes cavus and pes planus always pathological

Answer 22

No, a relatively high degree of the population will have them to some degree, as long as it is not sore or rigid is usually fine

Question 23

What is hallux valgus

Answer 23

Lateral displacement of the great toe, usually due to confinement of a wide splayed foot within a tight shoe

Question 24

How may hallux valgus progress?

Answer 24

If not corrected may become permanent due to shortening of the capsular ligaments

Question 25

What happens if the blood supply to the femoral head is disrupted

Answer 25

Part of the femoral head will necrose and the surrounding areas will be forced into bearing excessive load leading to stress and eventually collapse

Question 26

What male/ female consideration is clinically important regarding the hip joint

Answer 26

Female femoral heads are smaller in relation to pelvic dimensions compared to men, centre of gravity is also further from centre of hip joints due to wider pelvis
May result in increased stress levels in hips of females

Question 27

What is a prerequisite for hemiarthroplasty of the shoulder i.e. replacement of the humeral head

Answer 27

An intact rotator cuff and normal glenoid fossa

Question 28

Why might arthroplasty of the shoulder be ineffective

Answer 28

Often have rotator cuff pathology so never get full restoration of function
Is also a very mobile joint and superior migration and subluxation of the humeral head is a common problem

Question 29

Why have reverse shoulder arthroplasty shown promise

Answer 29

Replace glenoid fossa with a glenoid sphere which a proximal humeral head cup replacement moves around

Prevents superior migration of the humeral head
Allows deltoid to rest in its anatomical position and hence compensate for rotator cuff pathology

Question 30

How do the superior and inferior radioulnar joints relate to forearm pathology

Answer 30

Form a circle from the bones of the forarm, much like the pelvis, very hard to break in one place only, fracture usually accompanied by dislocation or another fracture somewhere else

Question 31

A fall on an outstretched hand will result in what kind of fracture?

Answer 31

Colles fracture
(dinner fork deformity due to dorsal displacement of the distal radius)

Question 32

If the radioulnar joints/ forearm are to be fused in what position will this be

Answer 32

With the palm facing medially i.e. semi-prone

Question 33

If the wrist is fused in what position will it be and why

Answer 33

Slightly extended to preserve grip power

Question 34

What is the terrible triad of injury at the knee

Answer 34

MCL, meniscus and ACL tear