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Dislocation 

Predisposing factors for dislocation Divide these into:

Patient-specific risk factors (female sex, AVN, obesity, increased age, co-morbidities, femoral neck facture)

Variables under the surgeon’s control (surgical approach, component position and orientation, femoral head size, restoration of offset, preservation of soft tissue integrity, leg length and prosthetic impingement)

Surgeon experience (risk of dislocation inversely related to the case volume of the operating surgeon)

Management options

These include

Closed reduction with or without bracing
Greater trochanter advancement.
Dated option as modular implants largely superceeded this choide 
Soft-tissue augmentation
Only used if no component mal-alignment,implant well fixed and a young patient.Even with these strict criteria this is often unsuccessful so more of a historic option than something to seriously consider.There are better more successful options available.
THA component revision
Exchange of modular parts
Tripolar unconstrained acetabular component (dual motion)
Elevated rim liners
Use of a large femoral head
Use of a constrained acetabular liner

The choice depends very much on the aetiology of the problem. Revision arthroplasty for recurrent dislocation is much more likely to be successful when a cause has been identified

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QUESTION 1 OF 19

A 69 year old woman is seen as an emergency add on to the orthopaedic clinic.She underwent cemented total hip replacement two weeks previously. Her wound has been persistently draining since she was discharged from hospital.She is well within herself, apyrexia with minimal hip pain.
The next most appropriate course of action is to

QUESTION ID: 1104

1. A. Aspiration hip
2. B. DAIR hip
3. C. Discontinue anticoagulation treatment
4. D. Start oral antibiotics
5. E. Swab the wound

QUESTION 2 OF 19

A 24 year old male presents to the orthopaedic clinic with a 2 year history of progressively worsening left hip pain.Pain limits his walking distance to around a ¼  of a mile and causes sleep disturbance at night.He is struggling to climb ladders at work as a scaffolder and can no longer play football.Anteroposterior (AP)radiograph hip is shown below(Figure 1 ).
The most appropriate course of action would be to:

oa left hip.png

Figure 1.Anteroposterior(AP)radiograph hip

QUESTION ID: 1106

1. A. Advise he is too young to undergo THA and he should continue with conservative management of his hip arthritis
2. B. List for an uncemented ceramic on HCLPE THA
3. C. List for Hip fusion
4. D. List for steroid local anaesthetic injection hip
5. E. Refer on to hip surgeon who performs MoM resurfacing

QUESTION 3 OF 19

A patient is seen in the outpatient clinic with severe bilateral end stage arthritis.She asks that both hips be operated on at the same time as it would “get them both out of the way in one sitting”
Compared to a two staged bilateral THA procedure a one stage bilateral THA procedure has:

QUESTION ID: 1107

1. A. A lower DVT risk
2. B. Increased cardiovascular complications
3. C. Increased dislocation rate
4. D. Increased risk of death
5. E. Longer operation time

QUESTION 4 OF 19

You see and list a 76 year old female for a left total hip replacement. She has moderate Parkinson’s disease
The most appropriate option to reduce her dislocation risk would be:

QUESTION ID: 1109

1. A. A change from a normal posterior approach to the hip to an anterolateral Hardinge approach.
2. B. Captive cup
3. C. Dual mobility
4. D. Lipped liner
5. E. Use of a large femoral head (36mm if possible)

QUESTION 5 OF 19

A 43-year-old woman presents to clinic with groin pain. She had undergone a right MoM hip resurfacing three years previously

Concerning her MRI scans below(Figure 1):

hip picture.png

Figure 1 .MRI pelvis axial T2.

QUESTION ID: 1168

1. A. Appearance would be consistent with her painful symptoms and lack of function
2. B. Diagnosis can be confirmed with macroscopic inspection
3. C. Is specific for an adverse reaction to metal debris
4. D. Pathogenesis involves a delayed hypersensitive (type IV) response to Co-Cr particles
5. E. There is a spectrum of necrotic and inflammatory changes in response to deposition of cobalt chromium wear particles

QUESTION 6 OF 19

A 76-year-old male attends the arthroplasty follow up clinic. He had a cemented total hip arthroplasty performed 10 years previously using a lateral Hardinge type approach. He complains of anterior thigh and knee pain with walking. Clinical examination reveals an antalgic gait with abductor lurch.
The most likely diagnosis would be

QUESTION ID: 1169

1. A. Infection
2. B. Loose femoral component
3. C. Vastus lateralis muscle herniation
4. D. Abductor muscle atrophy with partial gluteal detachment
5. E. Thoracolumbar discogenic pain

QUESTION 7 OF 19

A 52-year-old male attends clinic with a fused hip. Fusion was performed 30 years previously following an RTA with an acetabular fracture and secondary development of osteonecrosis. He complains of severe low back pain and ipsilateral knee pain. Radiographs show a cobra head plate in place with some concern about his abductor muscle mass

The most appropriate assessment would be:

QUESTION ID: 1171

1. A. CT scan to access abductor status
2. B. Electromyography
3. C. Inspection and palpation abductor muscle mass
4. D. MRI scan to access abductor status
5. E. U/S scan abductor muscle

QUESTION 8 OF 19

 A 78-year-old female is seen in the outpatient clinic with severe bilateral end stage arthritis. She asks that both hips be operated on at the same time as it would “get them both out of the way in one sitting and save time”
Compared to a two staged bilateral THA procedure a one stage bilateral THA procedure has

QUESTION ID: 1173

1. A. A lower DVT risk
2. B. Increased cardiovascular complications
3. C. Increased dislocation rate
4. D. Increased risk of death
5. E. Longer operation time

QUESTION 9 OF 19

You see and list a 76-year-old female for a left total hip arthroplasty. She has moderate Parkinson’s disease

The most appropriate option to reduce her dislocation risk would be

QUESTION ID: 1175

1. A. A change from a normal posterior approach to the hip to an anterolateral Hardinge approach.

QUESTION 10 OF 19

You are performing a hybrid hip replacement in a 62-year-old patient with mild cognitive impairment. There is a pre-operative concern about instability. The bone quality appears very poor at surgery. The definitive cup is a press fit design but is loose when impacted.
The most appropriate action is to

QUESTION ID: 1176

1. A. Insert an uncemented TM revision cup
2. B. Supplementary screw fixation
3. C. Convert to using a cement cup
4. D. Change to a line to line cup with screw fixation
5. E. Insert the next sized larger cup into the acetabulum

QUESTION 11 OF 19

A patient with a large BMI (≥ 40) has been referred to your clinic for a second opinion regarding the need for THA.The first surgeon who she met in clinic turned her down for THA mentioning that risks of complications were too significant with a large BMI
With an increased BMI over 40 there is:

QUESTION ID: 1177

1. Higher risk of revision for aseptic loosening
2. Higher risk of revision for mechanical failure of the implant
3. Increased risk of mortality
4. Poorer functional outcome compared to non obese patients
5. Reduced improvement in pain scores compared to non obese patients

QUESTION 12 OF 19

In theatre you are the main surgeon performing a cemented total hip arthroplasty. As the scrub nurse is mixing the cement, they mention that they had recently been on a “nursing cement training day” organised by one of the implant companies. She was a little unsure about the difference between third and fourth generation cementing techniques
You mention:

QUESTION ID: 1179

1. Fourth generation cementing involves late insertion of an implant into viscous cement
2. Fourth generation cementing involves using serial high pressure pulsed lavage
3. Fourth generation involves using distal and proximal centralizers to ensure an even cement mantle
4. Fourth generation techniques involve improved stem designs
5. Third and fourth generation cementing techniques are essentially the same procedure

QUESTION 13 OF 19

A 72-year-old man returns to arthroplasty follow up clinic 1 year following cemented THA.His AP radiograph is shown below(Figure 1).
Concerning the x-ray appearance:

q19.jpg

Figure 1.Anteroposterior(AP) radiograph pelvis 

QUESTION ID: 1180

1. Early removal is advisable in order to reduce the risk of dislocation
2. It is a rare occurrence (<5%) occurring after THA
3. Pathophysiology is an abnormal differentiation of pluripotent mesenchymal stem cells
4. Risk factor includes posterior approach
5. Very likely to result in lower Harris hip scores

QUESTION 14 OF 19

 

A 76-year-old female dislocates her THA 1 day post-operatively in bed the next morning following surgery. The THA was performed by a trainee orthopaedic surgeon although they were being closely supervised by their consultant  
The most likely reason for the dislocation occurring would be:

 

QUESTION ID: 1182

1. Component mal-alignment
2. Failure to remove osteophytes
3. Large retained piece of cement in the hip joint
4. Non compliance with post operative hip precautions
5. Using a posterior approach to the hip and failing to adequately repair the soft tissues

QUESTION 15 OF 19

A 81-year-old man is admitted from the ED with a dislocated left THA.He underwent the surgery 3 weeks previously.
The strongest independent patient predictor of early THA dislocation (within 40 days) is:

QUESTION ID: 1183

1. Dementia
2. Depression
3. Lung disease
4. Parkinson’s disease
5. Spinal fusion

QUESTION 16 OF 19

A 43-year-old male presents to the orthopaedic clinic with an 8-week history of severe left hip pain His radiographs are shown below (Figure 1)
The most appropriate treatment would be.

Figure 4.8Q. jpg.jpg

Figure 1.Anteroposterior (AP) radiograph hip

QUESTION ID: 1196

1. Bisphosphonates
2. Cemented total hip replacement
3. Core decompression
4. Hip resurfacing
5. Vascularised fibular graft

QUESTION 17 OF 19

A 78-year-old female who underwent right THA via a posterior approach is seen the next morning with a dense painful foot drop.
The most appropriate initial management is:

QUESTION ID: 1197

1. MRI scan
2. Nerve conduction studies
3. Physiotherapy and foot drop splint
4. Radiographs hip
5. Re-exploration of the hip

QUESTION 18 OF 19

 A 78-year-old female is seen in the outpatient clinic with severe bilateral end stage arthritis. She asks that both hips be operated on at the same time as it would “get them both out of the way in one sitting and save time”
Compared to a two staged bilateral THA procedure a one stage bilateral THA procedure has

QUESTION ID: 1240

1. A lower DVT risk
2. Increased cardiovascular complications
3. Increased dislocation rate
4. Increased risk of death
5. Longer operation time

QUESTION 19 OF 19

You are performing a hybrid hip replacement in a 61-year-old patient with mild cognitive impairment. There is a pre-operative concern about instability. The bone quality appears very poor at surgery. The definitive cup is a press fit design but is loose when impacted.
The most appropriate action is to

QUESTION ID: 1242

1. Change to a hydroxyapatite cup with screw fixation
2. Convert to using a cement cup
3. Insert an uncemented TM revision cup
4. Insert the next sized larger cup into the acetabulum
5. Supplementary screw fixation