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Knee Sports MCQs

Practice Set 20 of 102

This practice set contains high-yield board review questions covering key concepts in Knee Sports. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 381

Topic: Knee Sports

Which radiographic measurement is used to assess patellar height?

. Q-angle.
. TT-TG distance.
. Dejour classification.
. Insall-Salvati ratio.
. Bisect offset.

Correct Answer & Explanation

. Insall-Salvati ratio.

Explanation

Correct Answer: DThe Insall-Salvati ratio (patellar tendon length to patellar diagonal length on a lateral X-ray) and modified Insall-Salvati ratio are standard measurements for assessing patellar height (patella alta or baja). The Q-angle measures quadriceps alignment, TT-TG measures tibial tubercle lateralization, Dejour classifies trochlear dysplasia, and bisect offset is used for patellar tilt on axial views. Therefore, Insall-Salvati ratio is the correct answer for patellar height.

Question 382

Topic: Knee Sports

A 15-year-old female presents with bilateral recurrent patellar instability. She has generalized joint hypermobility (Beighton score 7/9) and a family history of patellar dislocations. Imaging shows normal trochlear morphology, minimal patella alta, and normal TT-TG distance bilaterally. What is the most appropriate initial management?

. Bilateral MPFL reconstruction.
. Physical therapy focusing on core and quadriceps strengthening, particularly VMO.
. Bilateral tibial tubercle medialization osteotomies.
. Bracing with hinged knee braces for all activities.
. Genetic counseling for a connective tissue disorder.

Correct Answer & Explanation

. Physical therapy focusing on core and quadriceps strengthening, particularly VMO.

Explanation

Correct Answer: BFor patients with generalized ligamentous laxity and recurrent patellar instability, conservative management, specifically targeted physical therapy, is the cornerstone of initial treatment. Surgical intervention is often less successful in this population and should be considered only after extensive failure of conservative measures. Bony procedures are usually not indicated if bony alignment is normal. While genetic counseling may be relevant for severe generalized laxity, it's not the 'initial management' for the instability itself. Bilateral MPFL reconstruction is an aggressive surgical intervention and should not be the first step, especially with normal bony alignment. Bracing can be an adjunct but not the primary management.

Question 383

Topic: Knee Sports

Which of the following factors is considered to be a strong predictor of failure after MPFL reconstruction?

. Isolated patella alta with no other bony risk factors.
. Mild trochlear dysplasia (Dejour Type A).
. Concomitant patellofemoral chondral damage.
. Uncorrected severe bony malalignment (e.g., TT-TG > 20mm, severe trochlear dysplasia).
. Age greater than 40 years at the time of surgery.

Correct Answer & Explanation

. Uncorrected severe bony malalignment (e.g., TT-TG > 20mm, severe trochlear dysplasia).

Explanation

Correct Answer: DMPFL reconstruction primarily addresses the soft tissue medial restraint. If significant bony malalignment (such as a severely increased TT-TG distance, or severe trochlear dysplasia like Dejour Type C or D) remains uncorrected, the biomechanical forces predisposing to instability persist, leading to a high risk of failure (re-dislocation or persistent subluxation) even after a technically adequate MPFL reconstruction. Mild patella alta or Type A dysplasia may not always require concomitant bony procedures. Chondral damage is a complication but not a direct cause of MPFL reconstruction failure in terms of recurrence. Age can influence healing but is not as strong a predictor of failure as uncorrected bony malalignment.

Question 384

Topic: Knee Sports
During reconstruction of the medial patellofemoral ligament (MPFL), identifying the correct femoral attachment is critical to prevent graft anisometry. Based on Schöttle's radiographic landmarks, where is the anatomic femoral origin of the MPFL located?
. Anterior to the posterior femoral cortex and distal to Blumensaat's line
. 1 mm anterior to the posterior cortex line, 2.5 mm distal to the posterior articular border, and proximal to Blumensaat's line
. Anterior to the medial epicondyle and distal to the adductor tubercle
. Posterior to the adductor tubercle and proximal to the medial epicondyle
. Centered exactly on the medial epicondyle

Correct Answer & Explanation

. 1 mm anterior to the posterior cortex line, 2.5 mm distal to the posterior articular border, and proximal to Blumensaat's line

Explanation

The MPFL origin (Schöttle's point) is radiographically defined as 1 mm anterior to the posterior cortex line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to the level of the posterior point of Blumensaat's line. Accurate placement prevents graft overtensioning in flexion.

Question 385

Topic: Knee Sports

A 22-year-old female undergoes a medializing tibial tubercle osteotomy (Fulkerson procedure) for recurrent patellofemoral instability with a TT-TG distance of 24 mm. Postoperatively, what is the most significant risk associated with over-medialization of the tibial tubercle?

. Patella baja
. Medial compartment osteoarthritis
. Recurrent lateral patellar dislocation
. Rupture of the patellar tendon
. Avulsion of the anterior cruciate ligament

Correct Answer & Explanation

. Medial compartment osteoarthritis

Explanation

Over-medialization of the tibial tubercle can significantly increase contact pressures in the medial tibiofemoral compartment, leading to medial compartment overload and early osteoarthritis. Surgeons must carefully titrate medialization to achieve a normal TT-TG distance (10-15 mm).

Question 386

Topic: Knee Sports

When evaluating a patient with patellofemoral instability, the Dejour classification is commonly used to describe trochlear dysplasia on true lateral radiographs. Which of the following radiographic findings defines Dejour Type B dysplasia?

. A shallow trochlear groove with no crossing sign
. A crossing sign with a supratrochlear spur
. A crossing sign with a double contour
. A crossing sign with both a supratrochlear spur and a double contour
. A patella alta with an Insall-Salvati ratio > 1.2

Correct Answer & Explanation

. A crossing sign with a supratrochlear spur

Explanation

In the Dejour classification, Type B dysplasia is characterized by a flat trochlea with a crossing sign and a supratrochlear spur. Type C features a double contour, and Type D features all three (crossing sign, double contour, and supratrochlear spur).

Question 387

Topic: Knee Sports

During medial patellofemoral ligament (MPFL) reconstruction, an improperly positioned femoral tunnel that is placed too proximal and anterior to the anatomic footprint will result in which of the following kinematic abnormalities?

. Graft laxity throughout the entire arc of motion
. Graft tightness in knee flexion
. Graft tightness in knee extension
. Recurrent patellar instability in deep flexion
. Excessive lateral patellar tilt in extension

Correct Answer & Explanation

. Graft tightness in knee flexion

Explanation

A femoral tunnel placed too proximal and anterior causes the distance between the femoral and patellar attachments to increase as the knee flexes. This non-isometric placement results in graft overtightening during knee flexion, potentially leading to stiffness and medial cartilage overload.

Question 388

Topic: Knee Sports

A 12-year-old skeletally immature female complains of recurrent patellar instability. MRI reveals a TT-TG (Tibial Tubercle-Trochlear Groove) distance of 24 mm and an intact MPFL. Which of the following surgical interventions is contraindicated in this patient?

. Medial patellofemoral ligament (MPFL) reconstruction with autograft
. Roux-Goldthwait procedure
. Lateral retinacular release
. Tibial tubercle medialization osteotomy
. Medial retinacular imbrication

Correct Answer & Explanation

. Tibial tubercle medialization osteotomy

Explanation

A tibial tubercle osteotomy is absolutely contraindicated in skeletally immature patients due to the high risk of iatrogenic injury to the proximal tibial physis and the tibial tubercle apophysis, which can cause recurvatum deformity.

Question 389

Topic: Knee Sports

A patient with recurrent patellofemoral dislocations has a true lateral knee radiograph demonstrating a "crossing sign" and a prominent "supratrochlear spur." According to the Dejour classification, what type of trochlear dysplasia does this represent?

. Type A
. Type B
. Type C
. Type D
. Type E

Correct Answer & Explanation

. Type B

Explanation

In the Dejour classification, Type B trochlear dysplasia is characterized by a flat trochlea, a crossing sign, and a supratrochlear spur on a true lateral radiograph. Type A has a shallow trochlea, Type C has a convex trochlea with a double contour, and Type D features a cliff pattern.

Question 390

Topic: Knee Sports

When evaluating the anatomic femoral origin of the MPFL on a true lateral radiograph, Schottle's point is best described by which of the following locations?

. 1 mm anterior to the posterior cortical line and just proximal to Blumensaat's line
. 5 mm anterior to the posterior cortical line and distal to Blumensaat's line
. Directly at the center of the adductor tubercle
. Directly at the medial epicondyle
. 10 mm proximal to the adductor tubercle

Correct Answer & Explanation

. 1 mm anterior to the posterior cortical line and just proximal to Blumensaat's line

Explanation

Schottle's point, identifying the radiographic femoral footprint of the MPFL, is located 1 mm anterior to the extension of the posterior femoral cortical line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to Blumensaat's line.

Question 391

Topic: Knee Sports

A 22-year-old female presents with recurrent patellar instability. An axial MRI reveals a TT-TG (Tibial Tubercle-Trochlear Groove) distance of 13 mm. Her patellar height is normal (Caton-Deschamps index = 1.0). Which of the following isolated procedures is the most appropriate surgical option?

. Tibial tubercle medialization (Fulkerson osteotomy)
. Trochleoplasty
. Isolated MPFL reconstruction
. Lateral retinacular release
. Tibial tubercle distalization

Correct Answer & Explanation

. Isolated MPFL reconstruction

Explanation

A TT-TG distance of less than 15-20 mm is considered within the normal to borderline range, indicating that bony malalignment is not the primary driver of instability. In this scenario, an isolated MPFL reconstruction is indicated to restore the primary medial soft tissue restraint.

Question 392

Topic: Knee Sports

Which of the following correctly describes the anatomical femoral attachment of the medial patellofemoral ligament (MPFL)?

. Distal to the adductor tubercle and proximal to the medial epicondyle
. Proximal to the adductor tubercle and distal to the medial epicondyle
. Anterior to the medial epicondyle and proximal to the adductor tubercle
. Directly over the center of the medial epicondyle
. Directly over the center of the adductor tubercle

Correct Answer & Explanation

. Distal to the adductor tubercle and proximal to the medial epicondyle

Explanation

The MPFL femoral origin is located in a saddle-shaped depression between the medial epicondyle and the adductor tubercle. Specifically, it is distal to the adductor tubercle and proximal to the medial epicondyle.

Question 393

Topic: Knee Sports

A 22-year-old female presents with recurrent lateral patellar dislocation. Imaging demonstrates a tibial tubercle-trochlear groove (TT-TG) distance of 21 mm, a Caton-Deschamps index of 1.0, and a Dejour Type A trochlea. Which of the following is the BEST surgical treatment plan?

. Isolated MPFL reconstruction
. MPFL reconstruction combined with medializing tibial tubercle osteotomy
. Isolated lateral retinacular release
. MPFL reconstruction combined with distalizing tibial tubercle osteotomy
. Sulcus-deepening trochleoplasty

Correct Answer & Explanation

. MPFL reconstruction combined with medializing tibial tubercle osteotomy

Explanation

A TT-TG distance >20 mm is generally considered pathologic and indicates excessive lateralization of the extensor mechanism. In the setting of recurrent patellar instability, this is treated with a medializing tibial tubercle osteotomy (TTO) in conjunction with MPFL reconstruction.

Question 394

Topic: Knee Sports

During medial patellofemoral ligament (MPFL) reconstruction, at what degree of knee flexion should the graft optimally be tensioned and fixed to avoid medial over-constraint?

. Full extension (0 degrees)
. 30 degrees
. 60 degrees
. 90 degrees
. 120 degrees

Correct Answer & Explanation

. 30 degrees

Explanation

The MPFL graft should be tensioned at approximately 30 degrees of knee flexion. At this angle, the patella is fully engaged in the trochlear groove, minimizing the risk of overtensioning and subsequent medial compartment overload.

Question 395

Topic: Knee Sports

On evaluation for recurrent patellofemoral instability, a lateral radiograph demonstrates a "crossing sign" and a "supratrochlear spur" (double contour). Axial MRI reveals a convex trochlear facet. This corresponds to which Dejour classification of trochlear dysplasia?

. Type A
. Type B
. Type C
. Type D
. Type E

Correct Answer & Explanation

. Type C

Explanation

Dejour Type C trochlear dysplasia is characterized by a convex trochlear facet and hypoplasia of the medial condyle. The corresponding lateral radiographic landmarks are the crossing sign and the presence of a double contour (supratrochlear spur).

Question 396

Topic: Knee Sports

A 19-year-old male with recalcitrant patellar instability has failed MPFL reconstruction and TTO. A rotational profile CT is ordered. A threshold of excessive femoral anteversion that often warrants a distal femoral derotational osteotomy in this setting is typically defined as greater than what value?

. 10 degrees
. 15 degrees
. 20 degrees
. 25 degrees
. 40 degrees

Correct Answer & Explanation

. 40 degrees

Explanation

While normal femoral anteversion is around 15 degrees, excessive anteversion greater than 30-40 degrees significantly alters patellofemoral mechanics. In cases of recalcitrant instability with anteversion >40 degrees, a distal femoral derotational osteotomy should be considered.

Question 397

Topic: Knee Sports

Which of the following is considered an appropriate indication for a sulcus-deepening trochleoplasty?

. High-grade (Dejour B or D) trochlear dysplasia with an intact cartilage surface
. Dejour Type A dysplasia with a TT-TG distance of 22 mm
. Dejour Type C dysplasia with advanced patellofemoral osteoarthritis
. Isolated patella alta with a Caton-Deschamps index of 1.5
. First-time patellar dislocation in a skeletally immature patient

Correct Answer & Explanation

. High-grade (Dejour B or D) trochlear dysplasia with an intact cartilage surface

Explanation

Trochleoplasty is indicated for recurrent instability in the setting of severe (Dejour B or D) trochlear dysplasia with a supratrochlear spur. It is strictly contraindicated in patients with open physes or advanced patellofemoral osteoarthritis.

Question 398

Topic: Knee Sports
A 21-year-old female undergoes medial patellofemoral ligament (MPFL) reconstruction for recurrent lateral patellar instability. During surgery, the femoral tunnel is inadvertently placed 10 mm proximal to the anatomic origin (Schöttle's point). What is the expected biomechanical consequence of this malposition?
. The graft will be tight in flexion and loose in extension.
. The graft will be tight in extension and loose in flexion.
. The graft will maintain isometric tension throughout the full arc of motion.
. The graft will cause excessive medial subluxation of the patella in full extension.
. The patellofemoral contact pressures will decrease significantly in deep flexion.

Correct Answer & Explanation

. The graft will be tight in flexion and loose in extension.

Explanation

The anatomic femoral origin of the MPFL is distal to the central axis of femoral rotation. If the graft is placed too proximally, the distance between the attachment points increases as the knee flexes, causing the graft to be tight in flexion and loose in extension.

Question 399

Topic: Knee Sports

A 15-year-old female presents with recurrent patellar dislocations. Radiographs reveal a 'double contour' sign on the true lateral view. According to the Dejour classification, what anatomic abnormality does this specific radiographic finding represent?

. A supratrochlear spur
. A hypoplastic medial trochlear facet
. A convex lateral trochlear facet
. Excessive patella alta
. An abnormally lateralized tibial tubercle

Correct Answer & Explanation

. A hypoplastic medial trochlear facet

Explanation

The 'double contour' sign seen on a true lateral radiograph represents a hypoplastic medial facet of the trochlea. It is a hallmark of Dejour Type C and Type D trochlear dysplasia.

Question 400

Topic: Knee Sports

A 23-year-old female is evaluated for recurrent patellofemoral instability. Axial CT scans are utilized to measure the Tibial Tubercle-Trochlear Groove (TT-TG) distance. Above what threshold is a tibial tubercle medialization osteotomy strongly indicated?

. 10 mm
. 15 mm
. 20 mm
. 25 mm
. 30 mm

Correct Answer & Explanation

. 20 mm

Explanation

A TT-TG distance greater than 20 mm is considered highly abnormal and is a primary indication for a tibial tubercle medialization osteotomy in the setting of recurrent patellar instability.

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