Pathology and joint replacement Flashcards
Can the cruciate ligaments repair themselves and if so why
Yes to a certain degree
Due to their relatively good blood supply
Why is it important to restore normal biomechanics to an injured knee
Failure to do so will likely result in secondary degenerative changes due to abnormal distribution of forces and stress
How are cruciate ligaments replaced
Via autologous tendon graft- usually gracilis, semitendinosus or part of patellar tendon
What are the disadvantages to synthetic prostheses for cruciate ligament repair
They cannot withstand the high forces at the knee and often break
Can induce foreign body changes such as fibrosis
What are the advantages of using an autologous tendon graft
Minimises foreign body change
Can preserve blood supply to enhance healing
What are the downsides of autologous tendon graft repair
Still not as strong as the original cruciate and so rupture may still (rarely) occur
Why is replacement of a damaged menisci important
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
What can happen as a result of loss of shock absorbing capacity of the menisci
Back pain and headaches
What type of meniscectomy is preferred and why
Partial as it leaves a vascularized rim which can allow regeneration to occur and maintains some stability
What is the success of meniscus regeneration dependent on
Age
Is more successful in the young
What else can be done for meniscus tear and when may this be preferred
Suturing of the tear may be an option for athletes who want an early return to competitive sport
What are some indications for total knee replacement
Severe and unremitting degenerative bone disease such as OA or inflammatory arthritis which has been unresponsive to medical treatment
Why are simple hinge prostheses unsuitable for knee joint replacement
Do not allow the normal rotatory movements of the knee so have a high rate of loosening
May have some role in sedentary patients
What range of motion is allowed with a knee joint replacement
110degrees
What happens to the PCL during knee joint replacement
It is most commonly removed
some debate as to whether it should be left
Is total knee joint replacement recommended for younger patients? Justify
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
What is the range of motion like after total ankle joint replacement
Usually within normal limits but different patterns
If joint fusion is to occur at the ankle what position should it be in and why
In a neutral position to allow effective heel strike to occur
Why is total ankle joint replacement limited to those with very severe disease
Will not sustain activity of even a sedentary lifestyle and will eventually need conversion to arthrodesis
Describe pes cavus
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
Describe pes planus
Flat foot
Medial border of the foot drops and becomes filled in looking on footprint
Are pes cavus and pes planus always pathological
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
What is hallux valgus
Lateral displacement of the great toe, usually due to confinement of a wide splayed foot within a tight shoe
How may hallux valgus progress?
If not corrected may become permanent due to shortening of the capsular ligaments
What happens if the blood supply to the femoral head is disrupted
Part of the femoral head will necrose and the surrounding areas will be forced into bearing excessive load leading to stress and eventually collapse
What male/ female consideration is clinically important regarding the hip joint
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
What is a prerequisite for hemiarthroplasty of the shoulder i.e. replacement of the humeral head
An intact rotator cuff and normal glenoid fossa
Why might arthroplasty of the shoulder be ineffective
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
Why have reverse shoulder arthroplasty shown promise
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
How do the superior and inferior radioulnar joints relate to forearm pathology
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
A fall on an outstretched hand will result in what kind of fracture?
Colles fracture (dinner fork deformity due to dorsal displacement of the distal radius)
If the radioulnar joints/ forearm are to be fused in what position will this be
With the palm facing medially i.e. semi-prone
If the wrist is fused in what position will it be and why
Slightly extended to preserve grip power
What is the terrible triad of injury at the knee
MCL, meniscus and ACL tear
