MCQs – Hip Recon 6

Modern Study Review (AI-Generated)

High-Yield Summary

This topic is a staple of the Royal College exam, focusing heavily on hip arthroplasty biomechanics, osteotomy indications, and avascular necrosis (AVN) staging. The single most important clinical trade-off is the choice between cemented and uncemented femoral stems, primarily dictated by patient factors and risk of thigh pain versus cement mantle failure. While exams emphasize classic Ficat staging for AVN, modern imaging and treatment increasingly rely on MRI and joint-preserving procedures. Understanding acetabular osteotomy types and their biomechanical effects remains critical for surgical planning.

High-Yield Decision Matrix

Active Recall Q&A

Hip Stem Type

Q: Which type of femoral stem has a higher incidence of thigh pain, cemented or uncemented?
A: Uncemented stems have a higher incidence of thigh pain.
Related Pearl: Thigh pain in uncemented stems often relates to micromotion and stress transfer differences compared to cemented stems.

Acetabular Osteotomies

Q: Which acetabular osteotomies redirect the acetabulum and move the teardrop?
A: Salter, Steel, and Ganz osteotomies redirect the acetabulum and move the teardrop.
Related Pearl: Moving the teardrop indicates medial wall displacement, which affects joint biomechanics and load distribution.

Q: Does the Chiari osteotomy move or redirect the acetabulum?
A: No, the Chiari osteotomy neither moves the teardrop nor redirects the acetabulum.
Related Pearl: Chiari osteotomy is an extra-articular procedure that medializes the acetabulum without altering its orientation.

Q: Which osteotomies redirect the acetabulum but do not move the teardrop?
A: Dial or spherical osteotomies redirect the acetabulum but leave the medial wall (teardrop) in its original position; these are intra-articular osteotomies.
Related Pearl: Preserving the medial wall maintains pelvic anatomy, potentially reducing complications related to medial wall disruption.

AVN Classification (Ficat)

Q: What are the radiographic features of Ficat Stage I AVN?
A: X-rays are normal; MRI is positive for AVN.
Related Pearl: MRI is the most sensitive modality for early AVN detection before radiographic changes appear.

Q: What characterizes Ficat Stage II AVN on imaging?
A: Sclerosis of the femoral head with possible fragmentation or cystic lesions.
Related Pearl: Sclerosis indicates reparative bone response; cystic changes suggest early bone resorption.

Q: What is the hallmark of Ficat Stage III AVN?
A: Sub-sclerotic lucency (crescent sign) with some collapse of the femoral head.
Related Pearl: The crescent sign represents subchondral fracture and is a predictor of impending collapse.

Q: What defines Ficat Stage IV AVN?
A: Arthritis on both the femoral and acetabular sides of the joint.
Related Pearl: This stage indicates secondary degenerative joint disease due to chronic AVN.

Elevated Rim Liners

Q: What complications are associated with elevated rim liners in hip arthroplasty?
A: Elevated rim liners are associated with impingement and possible earlier loosening.
Related Pearl: Impingement can cause edge loading and accelerated polyethylene wear.

Cement Failure

Q: What is the primary cause of cement failure in hip arthroplasty?
A: Microfracture and fragmentation, especially near sharp stem corners, cement voids, and inadequate cement mantle.
Related Pearl: Proper cementing technique and stem design minimize stress risers that cause cement failure.

Varus Osteotomy Indication

Q: What should be assessed on the abduction view before performing a varus femoral osteotomy?
A: Check if the femoral head reduces (Shenton’s line, inferior head-teardrop relation), if it is congruent (weight-bearing area), and if it is covered (center edge angle).
Related Pearl: These parameters predict the likelihood of successful joint realignment and load distribution post-osteotomy.

Cartilage Tangential Zone

Q: Describe the collagen fiber orientation in the tangential zone of normal adult cartilage.
A: High concentration of collagen fibers running at 90 degrees to each other but parallel to the joint surface, with minimal proteoglycan matrix.
Related Pearl: This “skin-like” layer resists shear forces and protects deeper cartilage zones.

Valgus Osteotomy Contraindication

Q: What is a contraindication to valgus intertrochanteric osteotomy?
A: Limited adduction (abduction contracture) because the leg will be abducted post-op and cannot return to neutral.
Related Pearl: Preoperative range of motion must accommodate the expected post-op limb position to avoid permanent deformity.

Varus Osteotomy Contraindication

Q: What is a contraindication to varus osteotomy?
A: Limited abduction (adduction contracture) because the leg will be adducted post-op but can spread beyond neutral.
Related Pearl: Understanding contracture direction guides osteotomy choice to optimize functional outcomes.

Rapidly Destructive Osteoarthritis

Q: What is “rapidly destructive osteoarthritis”?
A: A rapidly progressive femoral head destruction mimicking septic arthritis, rheumatoid arthritis, seronegative arthritis, osteonecrosis, or neuropathic arthropathy, but without infection signs.
Related Pearl: Early recognition prevents misdiagnosis and inappropriate treatment; infection must be ruled out.

Cemented Femoral Component

Q: What is important about the medial border of cemented femoral components?
A: It should be broad and rounded to avoid stress concentration in the cement.
Related Pearl: Stress risers increase risk of cement mantle failure and subsequent loosening.

Rheumatoid Arthroplasty

Q: In rheumatoid patients, which joint should be replaced first: hip or knee?
A: Hip replacement should be done before knee replacement.
Related Pearl: Hip replacement improves rehabilitation and reduces risk of knee fracture during hip surgery.

Cement Porosity

Q: How does reducing cement porosity affect cement properties?
A: It improves the compressive modulus of the cement.
Related Pearl: Denser cement has better mechanical strength and longevity.

THR after Arthrodesis

Q: What is the failure rate difference for total hip replacement after arthrodesis?
A: There is a 40% higher rate of mechanical failure and loosening.
Related Pearl: Arthrodesis alters biomechanics and soft tissue envelope, increasing THR complexity and risk.

Osteonecrosis MRI

Q: How does osteonecrosis appear on T1 MRI?
A: The necrotic segment appears dark (low intensity) on T1 because fatty marrow is replaced.
Related Pearl: Fatty marrow normally appears bright on T1; loss of this signal is a key diagnostic feature.

Uncemented Cup Reaming

Q: What is the recommended reaming technique for uncemented acetabular cups?
A: Under-ream by 1-3 mm to avoid excessive acetabular lucency; under-reaming by 4 mm or more increases fracture risk.
Related Pearl: Proper rim fit optimizes initial stability while minimizing bone damage.

Uncemented Cup Stress Shielding

Q: Where does stress shielding commonly occur with uncemented cups?
A: In DeLee zone 2 (the central zone) due to rim fit bonding at zones 1 and 3.
Related Pearl: Stress shielding can lead to bone resorption and implant loosening over time.

Classic Clinical Notes

• Between uncemented and cemented stems – the uncemented have a higher incidence of thigh pain.

• For acetabular osteotomies – the Salter, Steel, and Ganz all redirect the acetabulum and move the teardrop. The Chiari does not move the teardrop, but it does not redirect the acetabulum either. The only ones to redirect the acetabulum but not move the teardrop (leave the medial wall in its original position) are the dial or spherical osteotomy. These are intra-articular osteotomies.

• Ficat I AVN – x-rays normal, MRI positive.

• Ficat II – sclerosis of head, maybe some fragmentation/cystic lesions.

• Ficat III – subsclerotic lucency (crescent sign) with some collapse of the head.

• Ficat IV – arthritis on both femoral and acetabular sides.

• Elevated rim liners are associated with impingement and possible earlier loosening.

• Cement failure often due to microfracture and fragmentation (more so than osteolysis). This is found particularly around sharp corners of the stem, near cement voids, and in areas of inadequate cement mantle. Hence, the importance of good cementing technique.

• When looking to do a varus osteotomy of the femur, look at the abduction view. Ask: does the head reduce? (look at the Shenton’s line, look at the relationship between the inferior head and the teardrop). Then ask, is it congruent? (look at the weight-bearing area of the acetabulum and the femoral head). Then ask, is it covered? (Tilt the x-ray so that the femur is pointing down to the floor, and measure the center edge angle).

• In normal adult cartilage, the tangential zone consists of a high concentration of collagen fibers – the tangential zone is like the “skin” of the cartilage. There are fibers running at 90 degrees to one another, but parallel to the joint surface. There is little intervening proteoglycan matrix in this layer.

• A contraindication to performing a valgus intertrochanteric osteotomy is limited adduction (ie. an abduction contracture); when performing the osteotomy, the leg will be abducted – if the patient has limited adduction preop, he/she will never get their leg back to neutral.

• Conversely, a contraindication to performing a varus osteotomy is limited abduction (an adduction contracture); when performing the osteotomy, the leg will be adducted – if the patient has limited abduction, they will be able to spread their legs beyond neutral.

• “Rapidly destructive osteoarthritis” is a concept more known in the European literature – it consists of rapid progressive destruction of the femoral head with such severe flattening as to look like it had been “sheared off”. It mimics septic arthritis, rheumatoid, seronegative, osteonecrosis, and neuropathic. The tip off is that there are no signs of infection – but rule this out!

• For cemented femoral components, it is important that the medial border be broad and rounded in order to avoid stress concentration in the cement.

• In rheumatoids, do their hip replacement before knee – rehab is easier, you eliminate their referred pain, and you place a lot of stress on the total knee during a total hip replacement and risk fracturing it.

• Reducing cement porosity improves the compressive modulus of cement.

• Total hip replacement after arthrodesis is associated with higher rate of mechanical failure and loosening (40% higher).

• Osteonecrosis is dark on T1 – I think. The marrow is fatty and normally fat is bright on T1 – this is replaced by low intensity of the necrotic segment.

• Line to line reaming and dome contact can result in greater acetabular lucency with uncemented cups – better to under-ream by 1-3 mm (if you under-ream by 4 mm, there is an increased chance of fracture).

• For uncemented cups, there may be some stress shielding in DeLee zone 2 (the central zone) because the cups are generally put in to achieve RIM FIT and hence the bonding would be more at the rim (zones 1 and 3) than in the center.

Last Updated on January 25, 2026 by Christian Veillette