MCQs – Lower Extremity 2

Modern Study Review (AI-Generated)

High-Yield Summary

Pediatric femoral and tibial fractures are a staple of the Royal College exam, focusing heavily on malunion thresholds, growth-related overgrowth, and surgical indications. The critical clinical trade-off is between acceptable deformity based on age-dependent remodeling potential versus the need for surgical correction (e.g., remanipulation or osteoclasis). While classic teaching accepts wider deformities in younger children, modern practice emphasizes early intervention when deformities exceed remodeling capacity to optimize function and prevent long-term sequelae. Tibial eminence fractures and Salter-Harris IV medial malleolar fractures require precise reduction to avoid growth disturbances, with ORIF indicated for displacement beyond specific thresholds.

High-Yield Decision Matrix

Active Recall Q&A

Femoral Malalignment and Osteotomies

Q: What deformities characterize “miserable malalignment” in children, and what surgical approach may be required?
A: Severe femoral anteversion with compensatory external tibial torsion; may require double osteotomies—externally rotating the femur and internally rotating the tibia.
Related Pearl: Patellar tracking issues are common due to combined rotational deformities, increasing risk of anterior knee pain and instability.

Salter-Harris IV Medial Malleolar Fracture

Q: How is a Salter-Harris IV medial malleolar fracture treated surgically?
A: Pin epiphysis to epiphysis; excise the small metaphyseal fragment if needed to achieve perfect reduction and prevent bony bar formation.
Related Pearl: Preventing bony bar formation is critical to avoid growth arrest and ankle valgus deformity.

Tillaux Fracture

Q: What is the typical mechanism and treatment for Tillaux fractures?
A: External rotation injury in 12-15-year-olds during growth plate closure; treat with closed reduction and long leg casting or ORIF if articular incongruity exists.
Related Pearl: The anterolateral distal tibial epiphysis is vulnerable due to ligamentous attachments; displacement risks joint incongruity and arthritis.

Anterior Hip Approach Intervals

Q: What are the superficial and deep intervals for the anterior hip approach?
A: Superficial: sartorius (femoral nerve) vs tensor fascia lata (superior gluteal nerve); deep: gluteus medius (superior gluteal nerve) vs rectus femoris (femoral nerve).
Related Pearl: Precise interval identification minimizes iatrogenic nerve injury, preserving hip abductor and flexor function.

Femoral Fracture Malunion Thresholds (?11 years)

Q: What are acceptable malunion thresholds for femoral fractures in children ?11 years old?
A: Up to 5° varus/valgus, 10° flexion/extension, and 10 mm shortening.
Related Pearl: Reduced remodeling potential near skeletal maturity mandates stricter alignment criteria to avoid functional impairment.

Femoral Fracture Malunion Thresholds (<5 years)

Q: What are acceptable malunion thresholds for femoral fractures in children <5 years old?
A: Up to 15° varus/valgus, 20° flexion/extension, and 15-20 mm shortening.
Related Pearl: Greater remodeling capacity in younger children allows more deformity tolerance without long-term sequelae.

Femoral Fracture 5 Weeks Post-Injury

Q: What are treatment options for a femoral fracture 5 weeks post-injury with unacceptable alignment?
A: Remanipulation in the OR or drill osteoclasis with remanipulation, depending on healing extent.
Related Pearl: Early intervention before complete healing improves correction success and reduces need for osteotomy.

Femoral Fracture 8 Weeks Post-Injury with 30° Valgus

Q: How should an 8-year-old with an 8-week-old femur fracture in 30° valgus be managed?
A: Drill osteoclasis is indicated.
Related Pearl: Valgus deformities beyond remodeling capacity require osteotomy to restore mechanical axis and prevent gait abnormalities.

Femoral Fracture 5 Weeks Post-Injury with 20° Varus

Q: How should a 5-year-old with a 5-week-old femur fracture in 20° varus be managed?
A: Possibly remanipulate; drill osteoclasis may be required depending on healing.
Related Pearl: Varus deformities over 15° in young children may remodel but often need surgical correction to prevent long-term malalignment.

Femoral Fracture Shortening

Q: What is the acceptable shortening in femur fractures, and when is traction required before spica casting?
A: Up to 1-1.5 cm shortening is acceptable; >3 cm shortening requires traction before spica casting.
Related Pearl: Spica casts do not control length; traction prevents further shortening and allows soft tissue accommodation.

Overgrowth Timeline After Femur Fracture

Q: What is the typical timeline and pattern for overgrowth after femur fractures in children?
A: Most rapid in first 2 years, tapering thereafter; some continue increased growth until skeletal maturity.
Related Pearl: Overgrowth partially compensates for initial shortening but is unpredictable; close monitoring is essential.

Leg Length Discrepancy After 18 Months

Q: How should a 2 cm leg length discrepancy after 18 months in an 8-year-old be interpreted?
A: The discrepancy will likely decrease slowly over time.
Related Pearl: Continued observation is critical before surgical intervention; premature surgery risks overcorrection.

90-90 Traction Indications and Contraindications

Q: For which fractures is 90-90 traction indicated, and when is it contraindicated?
A: Indicated for subtrochanteric, supracondylar, and non-compound femur fractures; contraindicated in head-injured patients.
Related Pearl: Knee flexion in supracondylar fractures complicates varus/valgus assessment; traction use must be carefully considered.

Tibial Eminence Fracture Initial Management

Q: What is the initial management for tibial eminence fractures?
A: Attempt closed reduction in extension; if displacement >2 mm remains, proceed to ORIF.
Related Pearl: Stability in slight flexion is necessary before casting; inadequate reduction risks ACL dysfunction.

Tibial Eminence Fracture Classification

Q: What is the classification of tibial eminence fractures?
A: I: Undisplaced; II: Complete fracture hinged posteriorly with possible meniscal block; III: Complete separation and displacement.
Related Pearl: Classification guides treatment from conservative (I) to surgical (III) approaches.

Proximal Tibial Fracture Immobilization

Q: How should proximal tibial fractures be immobilized?
A: Long leg cast in extension.
Related Pearl: Extension immobilization reduces displacement risk and promotes optimal healing alignment.

Causes of Valgus Deformity After Proximal Tibial Fractures

Q: What are potential causes of valgus deformity after proximal tibial fractures?
A: Asymmetric growth plate stimulation, soft tissue interposition (periosteum, pes anserinus, MCL), or fibular tethering.
Related Pearl: Early detection and monitoring are essential to prevent progressive deformity and need for corrective osteotomy.

Classic Clinical Notes

• Kids with “miserable malalignment” can have severe femoral anteversion and a compensatory external tibial torsion in which case you might have to do double osteotomies – to externally rotate the femur and internally rotate the tibia. Patellar tracking can become a major problem in these kids.

• In a Salter 4 medial malleolar fracture of the ankle, you pin the epiphysis to epiphysis. You may have to excise the little metaphyseal part of the fragment to prevent get it reduced perfectly and to prevent bony bar formation to tether the ankle medially.

• Tillaux fractures are external rotation injuries that occur around the time the growth plate is closing (12-15 year olds), and can be treated with closed reduction and casting (long leg) or by ORIF if articular surface incongruent.

• The interval for the anterior approach to the hip is sartorius (fem nerve) vs tensor fascia lata (superior gluteal nerve) superficially, and gluteus medius (superior gluteal nerve) vs rectus femoris (femoral nerve) deep.

• Deciding what to do about femoral fracture malunion can be difficult, starting with deciding what actually constitutes a malunion. Obviously, more can be accepted as a neonate than as a child nearing skeletal maturity. Suffice to say that in a child 11 years old or up, accept 5° of varus/valgus, 10° of flex/ext, and 10 mm of shortening. In a child less than 5, you can probably accept up to 15° of varus/valgus, 20° of flex/ext, and 15 to 20 mm of shortening.

• With the femur fracture that is 5 weeks out with unacceptable alignment, you can try to do a remanipulation in the OR, or you can do drill osteoclasis and remanipulate it. It kinda depends on how much you think it’s healed at 5 weeks.

• 8 y/o with 8 week old femur fracture in 30° of valgus – drill osteoclasis.

• 5 year old with 5 week old femur fracture in 20° of varus – maybe able to remanipulate it. Hard to say; just know that you might have to do drill osteoclasis.

• Shortening is an interesting thing to consider in femur fractures – you can accept up to 1-1.5 cm of shortening and anticipate that overgrowth will look after the rest. If more than 3 cm short initially, then the kid needs traction before going into a spica – the spica will not control length! If the thing has healed short (say, 6 cm) it may be worthwhile to wait for the overgrowth to occur (usually in the first 12 months) then decide what to do after that. Because you cannot be totally sure how much overgrowth will happen, you are better off to wait.

• In general, overgrowth happens most rapidly for the first 2 years, then tapers off, although in some patients the increased growth rate in that bone continues until they are skeletally mature. So if after 18 months there is a two cm difference in length in an 8 year old, you can expect that the discrepancy will probably decrease, albeit slowly.

• 90-90 traction is good for subtrochanteric fractures, supracondylar fractures, and femur fractures that are not compound. Avoid traction in head injured patients. I question the use of traction in the supracondylar fracture – the knee must remain flexed, making it difficult to assess varus/valgus.

• Tibial eminence fractures probably deserve a try at closed reduction in extension – if this doesn’t work (unreduced by 2 mm) then ORIF. If it does reduce, you want to make sure it is stable in a few degrees of flexion, because you will cast them in a few degrees of flexion.

• Remember the classification of tibial eminence fractures –
• I – undisplaced
• II – complete fracture that is hinged at the back – the anterior horn of the medial meniscus may block reduction
• III – complete separation and displacement

• For the proximal tibial fracture – long leg cast in extension.

• For proximal tibial fracture – beware valgus deformity down the road. Numerous theories about why this happens – asymmetric stimulation of the growth plate, soft tissue (periosteal, pes, MCL) interposition, tethering of the fibula.

Last Updated on January 25, 2026 by Christian Veillette