Shoulder joint replacement Flashcards

(39 cards)

1
Q

prior to upper limb joint replacement what will most patients have been diagnosed with?

A
RA
OA
osteonecrosis
post traumatic arthritis 
fractures
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2
Q

what will be given priority in RA sufferers, over upper limb joint replacement

A

spine or lower limb problems will be prioritised

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3
Q

why should spine / lower limb joint replacement be prioritised over upper limb arthroplasty?

A
  • RA of c-spine may cause instability & can be assoc with significant/progressive neuro symptoms&raquo_space; must prevent damage to spinal nerves or cord
  • lower limb joint replacement may eliminate/lessen the need for upper limb support of body weight&raquo_space; if this isn’t addressed first it could compromise the success of an upper limb replacement
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4
Q

If more than one upper limb joint is affected, how is it decided which will take priority

A

firstly pain is the determining factor

secondly, if all are equally painful, replacement is generally performed distally to proximally i.e. fingers first

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5
Q

why are distal joints replaced before proximal joints, if equally painful

A

primary aim of upper limb joint replacement is restoration of hand function
distal joint impairment may compromise the important early physio to a more proximal joint in the early period following replacement
arguably more functional improvement is gained the more distal the joint

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6
Q

why do some surgeons prefer to replace the shoulder before other upper limb joints

A
  • shoulder pain more troublesome at night & may radiate to elbow
  • immobilised shoulder may cause abnormal loadings at the elbow which may lead to early failure of an elbow prosthesis
  • rehab of other upper limb joints can be simplified with pain-free (or at least less painful) shoulder
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7
Q

what has been shown to provide better pain relief - total or hemi-arthroplasty

A

total

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8
Q

apart from small dimensions and complexity, what added difficulty does a shoulder replacement have?

A

balancing soft-tissue and inadequate scapula bone stock

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9
Q

how are shoulder prostheses divided into subcategories

A

according to constraint

  • unconstrained
  • semiconstrained
  • constrained
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10
Q

how are shoulder prosthesis described if they don’t conform to the normal joint

A

reversed or inverted anatomy designs

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11
Q

primary indication for elective replacement of shoulder joint

A

pain relief

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12
Q

how much abduction can an unconstrained shoulder replacement generally achieve

A

90 - 135

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13
Q

what will largely influence the type of shoulder design chosen for a particular patient

A

pre op assessment of the quality of the soft tissues surrounding the shoulder joint

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14
Q

if the rotator cuff is intact and functioning, what type of shoulder prosthesis would be chosen?

A

unconstrained

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15
Q

what is the primary function of the shoulder

A

to allow the hand to be positioned in space

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16
Q

name the 3 synovial joints of the shoulder and the other important articulation

A

glenohumeral
acromioclavicular
sternoclavicular

scapulothoracic articulation

17
Q

how high can the forces reach at the glenohumeral joint

A

up to several times body weight

18
Q

what compensates for the inherent instability of the glenohumeral joint

A

rotator cuff

  • supraspinatous
  • infraspinatous
  • subscapularis
  • teres minor
19
Q

what condition in particular is likely to involve some soft tissue pathology at the shoulder

20
Q

what is a significant problem with shoulder replacements due to little bone stock
especially with which type of designs?

A

loosening of the glenoid component, especially with constrained designs

21
Q

what is an unconstrained shoulder prosthesis dependent upon

A

intact, functioning rotator cuff

22
Q

what has been found to be superior - shoulder replacement with glenoid component or without

A

with glenoid component replacement

- increased patient satisfaction, ROM and pain relief

23
Q

in which age group may total shoulder arthroplasty be more risky than partial

A

younger patients because total carries the risk of loosing of the glenoid component and revision operations are difficult

24
Q

what is the advantage of a hooded glenoid

A

it prevents upwards subluxation of the humeral component due to rotator cuff weakness

25
what tendon will tear if there is upwards subluxation of the humerus
supraspinatous
26
what is the disadvantage of semiconstrained designs as opposed to unconstrained designs
motion is limited leading to greater forces transmitted to the glenoid component bone-cement junction >> more frequent loosening
27
what do the vertically acting forces on the hood of a shoulder prosthesis tend to cause?
compressive stresses superiorly | tensile stresses inferiorly
28
what is unusual about the Stanmore shoulder prosthesis
it is a metal-on-metal design
29
in the Stanmore prosthesis how is the glenoid socket fixed
three pegs and an abundance of bone cement
30
give 3 complications of the Stanmore prosthesis
unsnapping of the 2 components instability glenoid component loosening
31
What is the Michael Reese replacement made of?
cobalt-chrome humeral head, polyethylene socket and metal glenoid cup
32
does the Reese replacement allow dislocation?
if a specified torque is reached, the humeral head will dislocate. this prevents scapular fracture
33
describe the trispherical prosthesis
it has 3 balls - both the humeral and glenoid components have a metal ball, both of which are contained within a third larger polyethylene ball
34
what provides extra strength to the polyethylene ball in the trispherical prosthesis
the ball is encapsulated in a Vitallium shell
35
advantage of the trispherical prosthesis
greater ROM and avoids impingement
36
what limitations does the trispherical design overcome?
``` usually the ROM is limited by: - the size of the joint space - ensuring the socket is thick enough - ensuring the ball doesn't dislocate the trispherical design overcomes these by basically doubling the ROM ```
37
which have a higher frequency of loosening - unconstrained or constrained designs? and which are more prone to dislocation?
constrained for both!!! | when dislocations occur they generally have to be treated surgically
38
what problem partly explains why hemiarthroplasty of the shoulder is popular
the problem of glenoid component loosening being much more common than humeral component loosening
39
why do constrained replacements tend to have more elaborate glenoid fixation
they are more prone to loosening bc subjected to larger loads