Abstract
There are several areas of pelvis/acetabulum that candidates need to be familiar with and other areas that are within a subspecialty interest.
Acetabular/pelvic radiology is usually discussed at the beginning of a viva and should be slickly and quickly answered so as to move on and to get onto the main testing area of the viva.
A basic appreciation of the various surgical approaches to fix an acetabular fracture is reasonable, but it is unlikely candidates will need to know this in great detail. Management of the open-book pelvis and the resuscitation around this is an A-list topic.
Introduction
There are several areas of pelvis/acetabulum that candidates need to be familiar with and other areas that are within a subspecialty interest.
Acetabular/pelvic radiology is usually discussed at the beginning of a viva and should be slickly and quickly answered so as to move on and to get onto the main testing area of the viva.
A basic appreciation of the various surgical approaches to fix an acetabular fracture is reasonable, but it is unlikely candidates will need to know this in great detail. Management of the open-book pelvis and the resuscitation around this is an A-list topic.
Familiarize and pattern-recognize various acetabular/pelvic fractures from either a large trauma book or website (usually radiology based) and be able to effortlessly describe out loud the pertinent/salient features.
Know the various classification systems, as although there is less emphasis on them these days, the viva invariably ends up at some point with the opportunity for a candidate to discuss them.
Structured oral examination question 1
EXAMINER: A 25-year-old professional motorbike racer came off his bike at more than 60 miles/hour speed. His only area of pain is his left hip. This is an X-ray of his pelvis. What does it show (Figure 14.1a)?
CANDIDATE: Anteroposterior pelvis radiograph of a skeletally mature adult marking out the iliopectineal and ilioischial lines (representing landmarks of the anterior and posterior columns) … [Silence]
COMMENT: Keep talking about the acetabular lines. The candidate has stopped too soon. They should have continued on and mentioned that the iliopectineal line represents the anterior column and the ilioischial line the posterior column. The medial aspect of the acetabulum is represented by the teardrop and the weight-bearing dome by the sourcil.
EXAMINER: [Candidate prompt] Tell me about pelvic anatomy. What acetabular lines do you know and are any disrupted?
COMMENT: Practise out loud describing disrupted acetabular lines on pelvic radiographs until it all comes together. Big-volume trauma books or internet image searches are the best sources. The aim is to get through this info in the first minute rather than getting bogged down and stuck as a candidate is losing scoring opportunities in not getting to the next stage of the viva.
CANDIDATE: The posterior wall is larger, more lateral and more easily visualized than the smaller, more medial anterior wall. The acetabular dome appears intact; Shenton’s line is intact. My concern is a possible posterior wall injury. The right sacroiliac joint appears wider than the left. There is a small bony avulsion in the pubic symphysis area. Both hip joints appear concentric.
EXAMINER: What will you do next?
CANDIDATE: This is a high-energy injury and the patient should be assessed according to ATLS protocols so that life-threatening injuries are not missed. As per ATLS protocols I will reassess the patient, performing primary and secondary surveys to identify any other injuries than the left hip. I will assess the range of movements in the left hip joint, distal neurovascular status and examine the left knee and left ankle. I will check the pulse rate, blood pressure and respiratory rate trend.
COMMENT: In the initial lead in question the examiner has implied that the injury is an isolated closed injury and doesn’t want the ALTS talk. However, the candidate isn’t assuming anything as the examiner hasn’t made this point absolutely crystal clear.
If, however the ATLS talk has already been done in the previous viva question then a candidate should default to ‘Assuming the injury is an isolated closed injury and ATLS protocols have been performed I will assess range of movements in the left hip joint … etc.’
If exam tactics are really not your strong point, then if all things fail at least you should avoid mentioning the ‘ATLS talk’ for all six of the trauma viva topics – now that will really annoy the examiners who are looking for an excuse to moan!
EXAMINER: Left hip movements are limited to a jog of movements by pain; the rest of the examination is unremarkable. What is the next step?
CANDIDATE: I will ensure the patient has adequate analgesia and frequent neurovascular assessment of the left leg. I will request a CT scan of the pelvis and both hips.
CANDIDATE: The timing of the CT scan would depend on the timing of the injury, the admitting hospital’s facilities and any associated injuries. If the injury occurred during the day it should be fairly straightforward in most hospitals to obtain an urgent CT scan that day. If the injury presents in the middle of the night, say 2 a.m., it could wait until the following morning, as the scan does not need to be performed immediately. If a CT scan is required for some other area of concern such as to exclude an abdominal injury, then it may be reasonable to also include the pelvis and both hips rather than have to rescan again in the next day or so.
COMMENT: This question tests real-life decisions and the rationale (and evidence) behind your choice – what you will do in an actual situation with a real patient in front of you. The question is examining higher-order judgement in the real world and not facts from a book. This is the highest level of knowledge the examination sets out to test. This is the score 7 and 8 opportunity that if a viva gets stuck down on competency questions the candidate will never get to.
EXAMINER: These are axial CT scans of both hips and SI joints. Describe the injury (Figures 14.1c and 14.1d).
CANDIDATE: The axial section of the left hip shows an intra-articular fragment, marginal impaction of the posterior wall, and loss of concentricity of the hip joint. There is no subluxation of hip or evidence of femoral head/neck injury. There is also a cystic lesion in the femoral head that looks benign.
Both SI joints appear symmetric and there are no other injuries that I can identify.
EXAMINER: What is the definitive management of this injury?
CANDIDATE: Non-operative management is not recommended due to the intra-articular fragment. This will result in early degenerative changes and post-traumatic osteoarthritis. The aims of operative management are to remove intra-articular fragments, reduce the marginal impaction, bone graft the bony defect if needed, then buttress plate fixation of the posterior wall. The amount of comminution could make fracture reduction difficult.
EXAMINER: When will you operate?
CANDIDATE: The surgery should be performed by an orthopaedic surgeon with interest in pelvic and acetabular fracture fixation. Surgery should be performed ideally within 5 days as per BOAST guidelines.
COMMENT: It is much better if a candidate avoids pure recitation of the BOAST text and actually thinks about the problem they have in front of them.
CANDIDATE: British Orthopaedic Association Standards of Trauma guidelines.
Pelvic fractures
First line of management is control of haemorrhage – pelvic binder, blood transfusion, pelvic packing or embolization.
Look for genitourinary tract injury and open fractures – wounds in perineum, rectum or vagina.
Surgical treatment of these injuries as soon as possible.
Early CT scan of pelvis.
Transfer images to local referral unit within 24 hours.
Once haemodynamic and skeletal stabilizations are achieved, the patient should be transferred to a specialist unit for surgery within 5 days if possible.
Figure 14.1a Anteroposterior (AP) radiograph of pelvis.
Figure 14.1b Iliopectineal line (red); ilioischial line (light green); sacral arcuate lines (yellow); Shenton arc (light blue); line of Klein (white); gluteal fat stripe (purple); acetabular roof (pink); medial acetabular wall (dark green); anterior acetabular wall (orange); posterior acetabular wall (dark blue); femoral head line (black).
Figure 14.1c and 14.1d CT scan of pelvis and SI joints.
Acetabular fractures
Urgent reduction of dislocated hips, skeletal traction should be applied. CT scan within 24 hours and images should be transferred to the specialist unit.
Surgery if needed should be performed within 5 days, ideally.
EXAMINER: What approach will you use? What are the significant risks and complications of the approach?
CANDIDATE: Posterior Kocher–Langenbeck approach. This allows access to the posterior wall and posterior column of the acetabulum.
EXAMINER: Take me through this approach.
CANDIDATE: This is a proximal extension of the posterior approach to the hip, which allows access to the posterior column, posterior wall and dome of the acetabulum. The patient is positioned either prone or in the lateral decubitus position.
Bony landmarks include: (1) posterior superior iliac spine, (2) greater trochanter, (3) shaft of femur.
The skin incision begins 5 cm anterior to the PSIS, curves over the greater trochanter and runs parallel to the shaft of the femur for 15–20 cm.
The superficial dissection involves incision of the fascia lata and gluteus maximus muscle.
The deep dissection involves exposing the insertion of the piriformis tendon, the gemelli and the internal obturator muscle. These muscles may have been damaged at the time of injury and their identification may be difficult.
The piriformis is divided through its tendon 1–2 cm from its femoral insertion after a stay suture has been passed through it. The tendons of obturator internus, superior and inferior gemelli muscles are tagged, divided 2–3 cm from their femoral insertion and then retracted. Subperiosteal dissection along the retroacetabular surface is performed. The lesser sciatic notch is exposed.
It is important to leave a cuff of tissue around the external rotators and avoid dissecting into quadratus femoris in order to preserve the ascending branch of the medial femoral circumflex artery.
The gluteus maximus insertion into the femur is released which aids retraction and reduces the stretch on the sciatic nerve.
EXAMINER: Would you prefer to position the patient in the lateral position or prone?
COMMENT: This question is testing higher-order thinking about what a surgeon would do in real life and what are his/her justifications for a particular decision.
CANDIDATE: Higher rates of infection and revision surgery are reported in the prone group. Lateral positioning is more common with most surgeons because it allows easier manoeuverability of the limb and avoids the unfamiliarity of operating in the prone position.
The main disadvantages of the lateral position are:
Difficulty applying manual traction.
Potential for sciatic nerve injury.
Difficulties achieving reduction due to persistent posterior column displacement as the result of gravity that cannot be eliminated in this position.
Access through the greater sciatic notch for palpation or clamp placement is impaired.
The prone position is particularly indicated for transverse or T-type fractures. It offers the main advantage of gravity elimination and aids in the reduction of the posterior column. The leg can be held flexed at the knee and extended at the hip to avoid traction on the sciatic nerve, greatly reducing the chance of nerve injury. Controlled lateral traction can also be applied to help visualize the joint surface through the window of the posterior wall fracture after the posterior column has been reduced.
The posterior column should be fixed first as it provides a stable surface to reduce the posterior wall fracture.
EXAMINER: What are the significant risks and complications of the approach?
CANDIDATE: Important blood supply to the femoral head is from medial femoral circumflex artery that passes close to the insertions of short external rotators of the hip. During surgery the short external rotators should be divided at least 1 cm from their insertions to protect this artery and avoid avascular necrosis of femoral head.
The sciatic nerve should be identified and protected.
The superior gluteal nerve and vessels are vulnerable during dissection of the superior border of the greater sciatic notch.
It is important to make sure no screws are penetrating the joint using II or intraoperative radiographs.
Other risks include infection, DVT, PE, loss of fixation, heterotropic ossification and secondary osteoarthritis.
EXAMINER: Can you think of any technical difficulties that you may encounter when fixing the fracture?
CANDIDATE: It is important to use a specialized pelvic traction table that allows controlled traction to be applied. Traction is very important in allowing fracture reduction. Traction unloads the joint allowing better joint visualization and assists direct manipulation of the fracture fragments. Manual methods of applying traction are unpredictable and usually difficult.
Bone graft may be needed to fill in any fracture gaps.
EXAMINER: Does this injury have a good or a bad prognosis, historically?
CANDIDATE: Posterior wall fractures have in general poor prognosis due to the damage to articular surface, impaction and difficulty in achieving anatomic reduction.
EXAMINER: What will be your postoperative rehabilitation protocol?
Structured oral examination question 2
EXAMINER: A 23-year-old professional dancer is involved in a road traffic accident at 5 pm (motorbike rider vs. car). The patient is brought to casualty with GCS of 15, BP 110/70 mmHg, PR 90/min. The patient is complaining of pain around the right buttock area.
Fifteen minutes after arrival the patient’s BP dropped to 70 mmHg systolic. What will you do?
CANDIDATE: As per ATLS protocols I will perform primary and secondary survey making sure two large-bore cannulae are introduced and blood taken for FBC, U&E, cross-match 6 units of blood. I will apply a pelvic binder and reassess the chest, abdomen, long bones and look for any open wounds that are bleeding.
EXAMINER: The patient’s blood pressure stabilized at 110/70 mmHg and 2 units of blood are being transfused.
X-ray of pelvis was performed. Describe the injury (Figure 14.2a).
CANDIDATE: This is a vertical shear-type pelvic fracture involving the right hemipelvis with fractures through both superior and inferior pubic rami and through right sacral alae and possibly neural foraminae.
CANDIDATE: No, I can’t see one.
COMMENT: The ‘spur’ sign represents the edge of intact ilium adjacent to the fracture, and is pathognomonic of a both-column fracture.
EXAMINER: Is there any obturator ring disruption?
CANDIDATE: No.
CANDIDATE: I didn’t see one.
EXAMINER: Why is this important?
CANDIDATE: A fracture of the transverse process of L5 in the presence of a pelvic fracture is associated with an increased risk of instability of the pelvic fracture.
EXAMINER: You mentioned vertical shear, how can you classify pelvic injuries?
CANDIDATE 1: [Silence …]
CANDIDATE 2: Judet and Letournel classification.
EXAMINER: I think you are mixing up acetabular and pelvic classification system names.
EXAMINER: Do you know a name?
CANDIDATE: Young and Burgess (Table 14.1).
EXAMINER: How does this classification guide your management?
CANDIDATE: This classification is based on the mechanism of injury and the severity of pelvic trauma. Fractures are divided into one of four categories based on the mechanism of injury, two of which are further subdivided according to the severity of injury.
EXAMINER: What is the typical mechanism of injury for a lateral compression fracture?
CANDIDATE: [Long silence … ]
EXAMINER: What are the radiological landmarks/lines you assess for a pelvic fracture? Show them on the normal side.
CANDIDATE: For pelvic fractures I start looking at the pubic symphysis, pubic rami, iliac wing, sacroiliac joints, sacral alae, neural foraminae, sacral bodies, transverse processes of lower lumbar vertebrae, sacral spinous processes. I will also look for associated acetabular fracture by looking at ilioinguinal, ilioischial lines, acetabular dome, anterior and posterior walls, obturator foramen and teardrop.
EXAMINER: What is this view?
CANDIDATE: This is a Judet view. An iliac oblique view. It demonstrates the anterior rim of the acetabulum and the posterior ilioischial column.
EXAMINER: Can you identify the lines for me?
EXAMINER: Have a try.
CANDIDATE: Line one is ilioischial line, line 4 is the iliac crest.
EXAMINER: How is this radiograph taken?
CANDIDATE: This is obtained on a supine patient with the injured side of pelvis rotated anteriorly at 45°. The X-ray beam is directed vertically toward the affected hip.
EXAMINER: That is the other Judet view, the obturator view.
COMMENT: The obturator oblique view is obtained on a supine patient with the injured side of pelvis rotated anteriorly at 45°. The X-ray beam is directed vertically toward the affected hip. It is useful to assess the obturator ring, anterior column (iliopectineal line) and posterior wall of the acetabulum.
The iliac oblique view is obtained on a supined patient with the unaffected side of the pelvis rotated anteriorly at 45°. The X-ray beam is directed vertically toward the affected hip. It is useful to assess the posterior ilioischial column and anterior wall. The iliac wing ‘flatten’ out on the image should be well demonstrated.
EXAMINER: How will you manage the patient now?
CANDIDATE: I will assess both lower limbs and distal neurovascular status followed by assessment of both upper limbs. I will also look for any open wounds around the perineum, groin, buttocks, vagina, rectum to rule out an open fracture. Until the spine is assessed the patient will have to be logrolled and the neck should be triple immobilized.
EXAMINER: The patient has altered sensation in the S1 nerve root area of the right foot, but no motor deficit was noted. What do you do?
CANDIDATE: I will obtain CT scan of cervical spine, chest, abdomen and pelvis to assess for associated injuries and look specifically for any evidence of S1 nerve root injury due to the pelvic fracture.
Then, I will perform distal femoral pin traction once I have ruled out any femoral fracture.
EXAMINER: CT scan does not show any other visceral or vascular injuries. No urethral or perineal injuries were identified. What will be the definitive management and the timing?
CANDIDATE: The images and patient details should be sent to the local specialist unit for a decision on transfer of the patient. Definitive management principles include reduction of the vertical shear, usually by skeletal traction, sacral fixation with sacroiliac screws, pubic ramus fixation with percutaneous ramus screw fixation or open reduction and plate fixation. If the fixation is still tenuous then external fixation could be used to augment the fixation.
EXAMINER: What are the specific risks involved?
CANDIDATE: Closed reduction of vertical shear may not be possible. If so, then open reduction of the sacral fractures can be performed with patient prone and stabilization with sacroiliac screws followed by pubic ramus stabilization. The L5 nerve root is at risk during sacroiliac screw insertion.
Other risks include infection, DVT, PE, failure of fixation and persistent low back pain.
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