MCQs – Hip Recon 8

Modern Study Review (AI-Generated)

High-Yield Summary

This topic is a staple of the Royal College exam, focusing heavily on surgical decision-making in slipped capital femoral epiphysis (SCFE) osteotomies, uncemented femoral stem fixation, and management of hip sepsis. The single most important clinical trade-off is the patient’s hip range of motion—specifically abduction and adduction deficits—which dictate the choice between varus and valgus osteotomies in SCFE. Another critical threshold is stem stability after insertion, where toggling mandates upsizing and reaming, precluding cemented conversion. While classic teaching emphasizes strict timing for two-stage reimplantation in gram-negative hip sepsis (~1 year), evolving protocols are exploring earlier reimplantation guided by infection markers.

High-Yield Decision Matrix

Active Recall Q&A

SCFE Osteotomy

Q: What range of motion deficits contraindicate a varus osteotomy in a young patient with SCFE?
A: Lack of abduction contraindicates varus osteotomy.
Related Pearl: Abduction is critical for varus osteotomy because it affects soft tissue tension and joint congruency, preventing postoperative instability.

Q: When is a valgus osteotomy contraindicated in SCFE patients?
A: When the patient lacks adduction.
Related Pearl: Valgus osteotomy increases adduction demand; insufficient adduction limits correction and risks joint incongruity and instability.

Q: How do you decide between varus and valgus osteotomy based on joint space changes in SCFE?
A: Increased joint space on abduction and extension suggests varus + flexion osteotomy; increased joint space on adduction suggests valgus osteotomy.
Related Pearl: Joint space widening in a specific position indicates improved joint congruency, guiding osteotomy direction to optimize biomechanics.

Uncemented Stem Fixation

Q: What should be done if an uncemented femoral stem toggles after insertion?
A: Ream the canal and insert a larger stem.
Related Pearl: Stem toggling indicates inadequate press-fit; upsizing improves initial stability and long-term osseointegration.

Q: Why is it difficult to switch to a cemented stem after reaming for an uncemented stem?
A: Because reaming removes cancellous bone needed for cement interdigitation.
Related Pearl: Cement fixation relies on intact cancellous bone for mechanical interlock; reaming compromises this substrate.

Hip Sepsis Management

Q: What is the recommended management for gram-negative hip sepsis?
A: Two-stage implantation with approximately one year before re-implantation.
Related Pearl: Gram-negative organisms have high virulence and biofilm formation, necessitating prolonged eradication before safe reimplantation.

Femoral Offset

Q: What are the biomechanical consequences of decreasing femoral offset?
A: Increased risk of dislocation due to shortened abductor lever arm, increased joint reaction force, and soft tissue de-tensioning.
Related Pearl: Maintaining femoral offset preserves abductor muscle efficiency and joint stability, reducing dislocation and gait energy expenditure.

Classic Clinical Notes

• In a young patient who has a SCFE and you are considering osteotomy on, look at the range of motion to decide what he is lacking – look at flexion/extension, rotation, abduction/adduction.
• Remember that you cannot do a varus osteotomy if they lack abduction, and you cannot do a valgus osteotomy if they lack adduction.
• Then check to see at which position they have an increase in their joint space. If they have increased joint space on abduction and extension of the hip, you can reproduce this position by doing a varus osteotomy and a flexion osteotomy.
• If they have increased joint space on adduction, then consider a valgus osteotomy.

• If doing an uncemented stem and you find that it toggles – ream and insert a bigger stem!
• You often cannot back out of this and put a cemented stem in, because you’ve reamed all the cancellous bone away!

• For gram negative hip sepsis, do a two stage implantation, but probably wait a whole year before re-implanting.

• If you decrease the femoral offset, you increase the risk of dislocation.
• You shorten the lever arm for the abductors, so they have to work harder, and the joint reaction force is increased, and the energy required to walk is increased.
• The major problem is de-tensioning the soft tissue sleeve and thus increasing risk of dislocation.

Last Updated on January 25, 2026 by Christian Veillette