ABOS Part I & OITE MCQs: Patellofemoral Instability

Question 1

A 16-year-old male presents with recurrent lateral patellar dislocations. Clinical examination reveals a positive J-sign, patellar hypermobility, and a positive apprehension test at 20 degrees of knee flexion. Imaging shows significant trochlear dysplasia, a TT-TG distance of 22 mm, and patella alta. The patient has failed conservative management. Which of the following surgical interventions would be MOST appropriate to address the multiple anatomical risk factors in this patient?

Explanation

Correct Answer: C

This patient presents with a severe form of patellar instability characterized by multiple significant anatomical risk factors: severe trochlear dysplasia, markedly increased TT-TG distance (normal < 15-20 mm), and patella alta. Isolated MPFL reconstruction would address the medial restraint but not the underlying bony deformities. VMO advancement and lateral retinacular release are typically insufficient for severe bony dysplasia. Tibial tubercle medialization alone would only address the TT-TG and not the trochlear dysplasia or patella alta. Therefore, a comprehensive approach involving trochleoplasty (for the severe dysplasia), MPFL reconstruction (for the medial restraint), and a tibial tubercle osteotomy for both medialization (for TT-TG) and distalization (for patella alta) is indicated for optimal outcomes and recurrence prevention. This combination addresses all major identified risk factors.

Question 2

Which of the following is considered the MOST significant risk factor for recurrent patellar instability?

Explanation

Correct Answer: D

Severe trochlear dysplasia, especially Dejour Types B, C, or D, is consistently identified as the single most significant anatomical risk factor for recurrent patellar instability. The flattened or convex trochlear groove provides inadequate bony constraint against lateral patellar translation. Generalized ligamentous laxity is a risk factor but less potent than severe dysplasia. Dislocation at a younger age (especially under 15) is associated with higher recurrence rates, not older age. A torn MPFL is characteristic of acute dislocation, but its absence doesn't preclude recurrence if other factors exist; its presence increases recurrence risk if left untreated. A Q-angle less than 10 degrees would typically be protective or normal, not a risk factor; an increased Q-angle is a risk factor.

Question 3

A patient with a history of recurrent patellar instability undergoes an MRI. The report indicates a TTPG (Tibial Tubercle-Trochlear Groove) distance of 20 mm. What is the clinical significance of this finding?

Explanation

Correct Answer: B

A TT-TG distance of 20 mm is considered significantly elevated. Normal values are typically less than 15-20 mm, with values over 20 mm strongly correlating with patellofemoral instability due to a lateralized pull of the patellar tendon and quadriceps mechanism relative to the trochlear groove. It is a key factor indicating bony malalignment. While patella alta can coexist, TT-TG specifically measures the transverse plane relationship, not patellar height. It's a significant risk factor but doesn't necessarily dictate immediate surgery if asymptomatic or if conservative management is successful. Quadriceps imbalance can contribute but isn't directly measured by TT-TG.

Question 4

Which of the following physical examination maneuvers is most specific for diagnosing patellar instability?

Explanation

Correct Answer: C

The patellar apprehension test (or 'Fairbank's test') involves attempting to laterally translate the patella with the knee in varying degrees of flexion while observing for the patient's anxiety, muscle guarding, or resistance, which signifies impending dislocation. This test is highly specific for patellar instability. The other tests are for collateral ligaments (valgus stress), ACL (Lachman), meniscal injury (McMurray), or patellofemoral pain syndrome (patellar grind), not patellar instability directly.

Question 5

A 12-year-old male with open physes experiences his second lateral patellar dislocation. X-rays show no fracture. MRI confirms MPFL rupture and normal trochlear morphology. He has no significant patella alta or increased TT-TG distance. What is the most appropriate surgical approach?

Explanation

Correct Answer: C

For skeletally immature patients with recurrent patellar instability, MPFL reconstruction is the preferred procedure. Given the open physes, techniques that avoid or protect the growth plates are critical, such as an all-epiphyseal (transphyseal without violating growth plates) or transphyseal tunnels placed carefully to minimize growth disturbance. Tibial tubercle osteotomies and trochleoplasty are generally avoided in skeletally immature patients due to the risk of growth arrest, unless there are severe underlying bony deformities that supersede this risk (which are explicitly ruled out in this question). Conservative management has failed after the second dislocation, and lateral release alone is insufficient for MPFL rupture.

Question 6

A 28-year-old female presents with persistent anterior knee pain and crepitus following an MPFL reconstruction performed 1 year ago for recurrent patellar dislocations. She reports no further dislocations but finds stairs and squatting painful. Physical exam shows no apprehension, but diffuse tenderness around the patellofemoral joint. Patellar height is normal. What is the most likely cause of her symptoms?

Explanation

Correct Answer: C

Persistent anterior knee pain, particularly with activities like stairs and squatting, after an MPFL reconstruction that successfully prevented recurrence, strongly suggests patellofemoral overload or over-constraining. This is a common complication if the MPFL graft is tensioned too tightly or fixed in an incorrect position, leading to increased patellofemoral contact pressures. Recurrence is ruled out by the history. Infection would typically present with different symptoms (fever, warmth, redness, systemic signs). Insufficient medialization would lead to continued instability, not just pain without apprehension. Graft rupture would lead to recurrence.

Question 7

Which radiographic measurement is used to assess patellar height?

Explanation

Correct Answer: D

The 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 8

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?

Explanation

Correct Answer: B

For 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 9

In the setting of an acute, first-time traumatic patellar dislocation without osteochondral fragments, what is the most appropriate initial treatment regimen?

Explanation

Correct Answer: B

For a first-time acute patellar dislocation without significant osteochondral injury, the standard of care is non-operative management. This includes closed reduction, often followed by a period of protected weight-bearing, use of a knee brace (often set to limit extension and encourage early flexion to engage the trochlea), and a comprehensive physiotherapy program focusing on quadriceps strengthening (especially VMO) and proprioception. Surgical intervention (MPFL reconstruction, LRR, osteotomy) is generally reserved for recurrent instability or specific concomitant injuries. Immobilization in full extension is outdated and can lead to stiffness.

Question 10

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

Explanation

Correct Answer: D

MPFL 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 11

A 55-year-old active male presents with chronic pain and stiffness in his right great toe, particularly during push-off. Physical examination reveals a dorsal exostosis and pain with passive dorsiflexion of the MTP joint, which is limited to 20 degrees. Radiographs show significant dorsal osteophyte formation, joint space narrowing, and subchondral sclerosis affecting approximately 50% of the joint surface. According to the Coughlin and Shurnas classification, what stage of hallux rigidus does this patient most likely have?

Explanation

Correct Answer: C

The Coughlin and Shurnas classification for hallux rigidus is widely used. Stage 1 involves mild flattening of the metatarsal head, minimal osteophytes, and good joint space. Stage 2 presents with moderate osteophytes (dorsal and dorsal-medial), mild-to-moderate joint space narrowing, and flattening of the metatarsal head, with 20-50% cartilage involvement. Stage 3 is characterized by significant osteophytes, moderate-to-severe joint space narrowing, and subchondral sclerosis/cysts, with greater than 50% cartilage involvement and pain at end-range motion. Stage 4 involves ankylosis or severe degenerative changes throughout the entire joint. This patient's presentation of significant dorsal osteophyte formation, joint space narrowing, subchondral sclerosis, and limited dorsiflexion to 20 degrees, affecting approximately 50% of the joint, aligns with Stage 3 hallux rigidus.

Question 12

Which of the following intrinsic foot muscles is primarily responsible for flexion of the great toe MTP joint and contributes significantly to the 'windlass mechanism' that is impaired in hallux rigidus?

Explanation

Correct Answer: B

The flexor hallucis brevis (FHB) is an intrinsic foot muscle with two heads (medial and lateral) that insert into the base of the proximal phalanx, encasing the sesamoids. It is the primary flexor of the great toe MTP joint and plays a critical role in stabilizing the MTP joint during gait, particularly during the push-off phase by facilitating the 'windlass mechanism'. Impairment of this mechanism due to MTP joint stiffness (hallux rigidus) alters normal gait biomechanics. Abductor hallucis abducts and flexes, adductor hallucis adducts and flexes, while lumbricales and flexor digitorum brevis act on lesser toes.

Question 13

A 48-year-old patient with Stage 2 hallux rigidus (Coughlin and Shurnas) continues to experience pain despite activity modification, appropriate footwear, and NSAIDs. Dorsiflexion is limited to 30 degrees, and a prominent dorsal osteophyte is palpable. Which surgical procedure is generally considered the most appropriate initial intervention for this stage, aiming to preserve joint motion?

Explanation

Correct Answer: C

For Stage 2 hallux rigidus, where there is moderate joint space narrowing and moderate osteophyte formation, but still reasonable cartilage (50-75% intact), a dorsal cheilectomy is typically the first-line joint-preserving surgical option. It involves removing the dorsal osteophytes and often a portion of the dorsal metatarsal head to decompress the joint and improve dorsiflexion. Moberg osteotomy is often performed in conjunction with a cheilectomy, or for more advanced cases, to improve dorsiflexion via a plantarflexion osteotomy of the proximal phalanx. Arthrodesis and arthroplasty are generally reserved for more advanced stages (Stage 3 and 4) or failed conservative/joint-sparing procedures. Metatarsal head resection arthroplasty (Keller arthroplasty) is largely historical due to associated complications like transfer metatarsalgia and instability.

Question 14

What is the primary biomechanical advantage of performing a Moberg osteotomy (dorsal closing wedge osteotomy of the proximal phalanx) in conjunction with a cheilectomy for hallux rigidus?

Explanation

Correct Answer: C

A Moberg osteotomy, a dorsal closing wedge osteotomy of the proximal phalanx, effectively plantarflexes the proximal phalanx relative to its articular surface. This maneuver indirectly increases functional dorsiflexion at the MTP joint by changing the resting position of the proximal phalanx, thereby reducing impingement and improving the toe-off phase of gait. It is typically performed in conjunction with a cheilectomy for Stage 2 or early Stage 3 hallux rigidus, or when isolated cheilectomy is insufficient to restore adequate dorsiflexion. It does not primarily offload the metatarsal head, correct hallux valgus (though some subtle correction might occur), or directly enhance intrinsic muscle function.

Question 15

A 60-year-old sedentary patient with Stage 4 hallux rigidus presents with severe, constant pain in the first MTP joint, significantly affecting daily activities. Radiographs show complete obliteration of the joint space and subchondral bone erosions. Considering the patient's age and activity level, which surgical option is generally considered the gold standard for pain relief and functional improvement in this scenario?

Explanation

Correct Answer: C

For Stage 4 hallux rigidus, characterized by severe degenerative changes or ankylosis, joint-preserving procedures like cheilectomy or Moberg osteotomy are inappropriate as they cannot address the diffuse damage. First MTP joint arthrodesis (fusion) is considered the gold standard for severe hallux rigidus, especially in active patients, or when other procedures have failed. It provides reliable pain relief and a stable, pain-free platform for push-off, though it sacrifices MTP joint motion. While interpositional arthroplasty or MTP joint implants might be considered for less active patients or those unwilling to sacrifice motion, arthrodesis typically offers the most predictable and durable pain relief for severe end-stage disease. A sedentary patient might be a candidate for arthroplasty, but for reliable pain relief and functional improvement, especially with complete obliteration, arthrodesis is still considered the gold standard for overall success.

Question 16

What is the most common radiographic finding in early stages of hallux rigidus?

Explanation

Correct Answer: C

In the early stages of hallux rigidus, the most common and often first radiographic sign is the formation of a dorsal osteophyte on the first metatarsal head. This osteophyte impinges on the base of the proximal phalanx during dorsiflexion, leading to restricted motion and pain. Complete ankylosis is a late-stage finding. Subchondral cysts and significant valgus deformity are less specific or later findings. Bone marrow edema is an MRI finding, not typically a primary radiographic finding for early diagnosis.

Question 17

Which of the following is considered a relative contraindication to first MTP joint arthroplasty with an implant for hallux rigidus?

Explanation

Correct Answer: C

Previous infection in the surgical field is a strong contraindication for any joint replacement procedure, including MTP joint arthroplasty with an implant, due to the high risk of recurrent infection and subsequent implant failure. Older, less active patients are often considered good candidates for arthroplasty as motion preservation is prioritized over the robust stability of an arthrodesis. Rheumatoid arthritis can be an indication for arthroplasty, especially with polyarticular involvement. Failed cheilectomy is a common indication for salvage procedures like arthroplasty or arthrodesis. Moderate hallux valgus may need concomitant correction but isn't a direct contraindication to implant arthroplasty itself, though some implants may not be suitable.

Question 18

When performing a cheilectomy for hallux rigidus, what is the recommended amount of bone to resect from the dorsal aspect of the first metatarsal head to achieve adequate decompression and improve dorsiflexion?

Explanation

Correct Answer: B

When performing a dorsal cheilectomy, the goal is to remove the dorsal osteophytes and approximately 10-15% of the dorsal articular cartilage of the metatarsal head. This amount is generally considered sufficient to decompress the joint, improve dorsiflexion, and prevent impingement without excessively shortening the metatarsal or destabilizing the joint. Removing only the visible osteophyte might be insufficient if impingement persists. Resecting 30-40% or the entire dorsal third is excessive and can lead to instability, transfer metatarsalgia, or shortening.

Question 19

A 30-year-old professional athlete develops severe, painful hallux rigidus (Coughlin and Shurnas Stage 3-4). He requires a stable, pain-free foot for continued high-impact activities. Which surgical option would you most strongly recommend for this patient?

Explanation

Correct Answer: C

For a young, active professional athlete with severe hallux rigidus (Stage 3-4), a first MTP joint arthrodesis is the most appropriate and recommended option. While it sacrifices motion, it provides a highly stable, pain-free, and durable platform capable of withstanding high-impact activities required by athletes. Cheilectomy with Moberg is generally for earlier stages (Stage 2-3). Keller arthroplasty (resection of proximal phalanx base) is largely abandoned due to high rates of complications like transfer metatarsalgia and instability. Silicone implants have a high failure rate in active patients and are prone to synovitis and osteolysis. Interpositional arthroplasty may be considered for less active patients but does not provide the same level of stability and predictable outcomes for high-demand individuals.

Question 20

What is the typical alignment of the great toe MTP joint following a successful first MTP joint arthrodesis, for optimal function?

Explanation

Correct Answer: A

The optimal position for first MTP joint arthrodesis is crucial for gait and footwear. While there is some debate, generally, the joint should be fused in 10-15 degrees of dorsiflexion (relative to the weight-bearing surface) and 10-15 degrees of valgus. This position accommodates normal toe-off during gait, allows for comfortable shoe wear, and helps prevent transfer metatarsalgia to the lesser toes. Fusing in too much dorsiflexion can lead to dorsal impingement in shoes, while too much plantarflexion impairs push-off and can cause shoe fitting issues. Excessive valgus or varus can also cause problems. The options often vary, but 10-15 degrees dorsiflexion and valgus is a good range.

Question 21

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?

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 22

A 55-year-old male presents with advanced hallux rigidus (Coughlin and Shurnas Grade 4). He elects to undergo a first metatarsophalangeal (MTP) joint arthrodesis. To optimize postoperative gait and patient satisfaction, what is the ideal position for the arthrodesis?

Explanation

The ideal position for 1st MTP arthrodesis is 10-15 degrees of dorsiflexion relative to the floor, 10-15 degrees of valgus, and neutral rotation. Excessive dorsiflexion causes IP joint arthritis, while inadequate dorsiflexion leads to altered gait and vaulting.

Question 23

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?

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 24

A 45-year-old runner presents with pain and stiffness in the right great toe. Radiographs demonstrate dorsal osteophytes and mild joint space narrowing, consistent with Coughlin and Shurnas Grade 2 hallux rigidus. Which of the following conservative management strategies is most appropriate?

Explanation

Conservative management of early to moderate hallux rigidus focuses on limiting first MTP joint motion. A stiff-soled shoe with a rocker bottom and a rigid Morton's extension effectively reduces dorsiflexion during the terminal stance phase of gait.

Question 25

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?

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 26

A 19-year-old athlete undergoes an isolated medial patellofemoral ligament (MPFL) reconstruction for recurrent lateral patellar instability. During graft fixation on the femoral side, at what knee flexion angle should the graft be tensioned, and what is the consequence of over-tensioning?

Explanation

The MPFL is most taut in full extension and becomes lax as the patella engages the trochlea. The graft should be fixed at 30 degrees of flexion with only enough tension to restore normal lateral translation; over-tensioning risks medial patellofemoral cartilage overload and pain.

Question 27

A patient with Coughlin and Shurnas Grade 1 hallux rigidus is scheduled for a cheilectomy. To optimize postoperative dorsiflexion while preventing joint instability, what is the maximum recommended amount of the dorsal metatarsal head that should be resected?

Explanation

During a cheilectomy, approximately 20% to 30% of the dorsal aspect of the first metatarsal head should be resected along with dorsal osteophytes. Resecting more than 30% to 40% risks compromising the articulation and destabilizing the joint.

Question 28

Following an acute lateral patellar dislocation, magnetic resonance imaging (MRI) is most likely to reveal a specific pattern of bone bruising. Which two anatomic locations classically demonstrate bone contusions in this scenario?

Explanation

The classic MRI bone bruising pattern after an acute lateral patellar dislocation involves the anterolateral aspect of the lateral femoral condyle and the inferomedial aspect of the patella. This occurs as the patella impacts the condyle during dislocation or relocation.

Question 29

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?

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 30

A 45-year-old active male presents with dorsal midfoot pain and limited hallux dorsiflexion. Radiographs show a preserved first MTP joint space with a large dorsal osteophyte (Coughlin and Shurnas Grade 2). He fails nonoperative management. If a cheilectomy is performed, what is the recommended extent of dorsal metatarsal head resection?

Explanation

During a cheilectomy for hallux rigidus, approximately 25-30% (up to one-third) of the dorsal metatarsal head should be resected. Resecting more than this can compromise the joint articulation and destabilize the MTP joint.

Question 31

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?

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 32

A 65-year-old woman undergoes a first MTP arthrodesis for end-stage hallux rigidus. To optimize normal gait kinematics and prevent transfer metatarsalgia, what is the ideal position for fusion of the first MTP joint?

Explanation

The ideal position for first MTP arthrodesis is 10 to 15 degrees of valgus and 10 to 15 degrees of dorsiflexion relative to the floor. This allows for normal toe-off during gait and accommodates most footwear.

Question 33

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?

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 34

A 55-year-old runner presents with severe first MTP joint pain. Radiographs reveal less than 25% joint space remaining, severe flattening of the metatarsal head, and multiple large osteophytes. Examination reveals pain at both extremes of motion. Which of the following is the most reliable surgical treatment?

Explanation

For advanced hallux rigidus (Coughlin and Shurnas Grade 3 or 4) with pain throughout the arc of motion and severe joint space narrowing, first MTP arthrodesis is the gold standard and most reliable procedure for pain relief and functional restoration.

Question 35

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?

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 36

In the surgical management of hallux rigidus, a Moberg osteotomy (a dorsal closing wedge osteotomy of the proximal phalanx) is most appropriately utilized as an adjunct procedure to achieve which of the following goals?

Explanation

A Moberg osteotomy does not increase the true range of motion of the first MTP joint. Instead, it shifts the existing arc of motion into more dorsiflexion, improving apparent dorsiflexion and reducing impingement during the toe-off phase of gait.

Question 37

A positive J-sign observed during physical examination of a patient with patellofemoral instability represents which of the following kinematic events?

Explanation

The J-sign describes the sudden lateral deviation (or tracking) of the patella in terminal extension. This occurs because the patella loses the bony restraint of the trochlear groove as it translates proximally and is pulled laterally by an imbalance in soft tissues.

Question 38

Which of the following shoe modifications is considered the most appropriate first-line conservative management for symptomatic hallux rigidus?

Explanation

A rigid Morton extension prevents painful dorsiflexion of the first MTP joint, while a rocker-bottom sole compensates for the lost motion by facilitating a smooth roll-through during the toe-off phase of gait.

Question 39

A 14-year-old female presents after her first episode of acute lateral patellar dislocation, which spontaneously reduced. MRI shows an intact articular surface without osteochondral loose bodies and a tear of the MPFL at the femoral attachment. What is the most appropriate initial management?

Explanation

First-time lateral patellar dislocations without evidence of a massive osteochondral fracture or intra-articular loose bodies are best managed non-operatively with brief immobilization and a rigorous physical therapy program focusing on VMO and core strengthening.

Question 40

A 50-year-old male undergoes a dorsal cheilectomy for Grade 2 hallux rigidus. Postoperatively, he complains of persistent numbness along the dorsomedial aspect of the great toe. Which nerve was most likely injured during the surgical approach?

Explanation

The medial dorsal cutaneous nerve, a branch of the superficial peroneal nerve, supplies sensation to the dorsomedial aspect of the hallux. It is highly susceptible to injury during the standard dorsal or dorsomedial surgical approach to the first MTP joint.

Question 41

When evaluating a patient for patella alta, the Caton-Deschamps index is measured using which of the following radiographic landmarks on a true lateral radiograph?

Explanation

The Caton-Deschamps index relies on articular margins, making it useful even if the patellar poles are morphologically abnormal. It is the ratio of the distance from the inferior articular margin of the patella to the anterior angle of the tibial plateau, divided by the patellar articular length.

Question 42

A 70-year-old patient with severe hallux rigidus underwent a silastic interposition arthroplasty of the first MTP joint 7 years ago. She now presents with progressive midfoot pain and swelling. Radiographs show significant osteolysis and cystic changes around the first metatarsal head and proximal phalanx. What is the most likely diagnosis?

Explanation

Silicone synovitis is a well-documented long-term complication of silastic implants in the first MTP joint. It results from a foreign-body macrophage response to silicone wear debris, leading to progressive osteolysis and cystic bone changes.

Question 43

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?

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 44

Metatarsus primus elevatus has been debated as a potential predisposing factor for the development of hallux rigidus. Which radiographic finding best defines metatarsus primus elevatus?

Explanation

Metatarsus primus elevatus is defined radiographically by the dorsal elevation of the first metatarsal shaft relative to the second metatarsal shaft on a weight-bearing lateral foot radiograph. This theoretically limits the functional dorsiflexion of the first MTP joint.

Question 45

A 45-year-old male presents with a painful, stiff great toe. Radiographs reveal a dorsal osteophyte on the first metatarsal head and mild joint space narrowing, but the plantar cartilage space is maintained. He has failed conservative management. Which of the following surgical interventions is MOST appropriate for this patient?

Explanation

Cheilectomy is the treatment of choice for early to mid-stage (Grade 1 and 2) hallux rigidus with dorsal impingement and preserved plantar articular cartilage. First MTP arthrodesis is typically reserved for end-stage (Grade 3 and 4) disease.

Question 46

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

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 47

When performing a first metatarsophalangeal (MTP) joint arthrodesis for end-stage hallux rigidus, what is the optimal position for the fusion to ensure normal gait mechanics?

Explanation

The ideal position for a first MTP arthrodesis is 10-15 degrees of valgus and 10-15 degrees of dorsiflexion relative to the floor. This positioning allows for proper weight transfer during the toe-off phase of normal gait and accommodates standard shoe wear.

Question 48

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?

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 49

What characteristic physical examination finding is most commonly associated with symptomatic hallux rigidus?

Explanation

Hallux rigidus typically presents with dorsal joint pain and restricted dorsiflexion. This pain is most pronounced during the terminal stance (toe-off) phase of gait when maximum dorsiflexion is required.

Question 50

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?

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 51

A 55-year-old female with moderate hallux rigidus requests non-operative management. Which of the following orthotic modifications is MOST effective in alleviating her symptoms?

Explanation

A stiff-soled shoe combined with a Morton's extension limits motion across the first MTP joint. By restricting dorsiflexion, this modification significantly reduces the impingement pain associated with hallux rigidus.

Question 52

Which radiographic index for evaluating patella alta is calculated by dividing the distance from the lower articular margin of the patella to the upper tibial articular margin by the articular length of the patella?

Explanation

The Caton-Deschamps index relies entirely on articular margins to measure patellar height. This makes it particularly useful because it is not affected by alterations to the tibial tubercle, such as previous osteotomies or Osgood-Schlatter disease.

Question 53

Which of the following factors is most strongly associated with an increased risk of nonunion following a first MTP joint arthrodesis?

Explanation

Smoking is a highly significant, modifiable risk factor for nonunion in foot and ankle arthrodesis, including first MTP fusions. Patients are strongly advised to adhere to strict smoking cessation perioperatively.

Question 54

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?

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 55

A 68-year-old female undergoes a Keller resection arthroplasty for severe hallux rigidus. Postoperatively, she develops a characteristic deformity due to the alteration of local biomechanics. Which of the following is the most common deformity associated with this procedure?

Explanation

Keller arthroplasty involves resecting the base of the proximal phalanx, which can inadvertently compromise the attachment of the flexor hallucis brevis. This leads to a loss of plantarflexion power at the MTP joint, resulting in a "cock-up" deformity.

Question 56

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?

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 57

A 35-year-old female with Grade 1 hallux rigidus is scheduled for a cheilectomy. To further improve her functional dorsiflexion and shoe wear tolerance, an adjunctive procedure is planned. Which of the following osteotomies is most appropriate?

Explanation

A Moberg osteotomy is a dorsal closing wedge osteotomy of the proximal phalanx. It effectively shifts the functional arc of motion towards dorsiflexion, making it a valuable adjunct to cheilectomy for improving toe clearance.

Question 58

What is the most common clinical consequence of overtensioning the graft during a medial patellofemoral ligament (MPFL) reconstruction?

Explanation

Overtensioning the MPFL graft is a frequent and severe technical error. It pulls the patella too tightly against the medial facet, leading to medial patellar overconstraint, increased contact pressures, pain, and iatrogenic medial subluxation.

Question 59

A patient exhibits constant pain with ROM of the first MTP joint. Radiographs show significant dorsal osteophytes, subchondral sclerosis, and less than 50% joint space preservation. No loose bodies are visualized, and pain is absent in the midrange of motion. According to Coughlin and Shurnas, what is the grade of hallux rigidus?

Explanation

Coughlin and Shurnas Grade 3 is defined by severe radiographic changes (<50% joint space) and constant pain near the extremes of motion. Grade 4 shares the same radiographic findings but is distinguished by pain throughout the entire range of motion, including the midrange.

Question 60

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

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 61

During a first MTP joint arthrodesis, a surgeon chooses to add an interfragmentary lag screw to a dorsal locking plate construct. What is the primary biomechanical advantage of this technique?

Explanation

Adding an interfragmentary lag screw (either independently or through the plate) provides dynamic compression across the arthrodesis site. This increased compression enhances construct stability and significantly improves the rate of successful fusion compared to a dorsal plate alone.

Question 62

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?

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 63

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?

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 64

A 55-year-old male runner complains of dorsal foot pain localized to the first metatarsophalangeal (MTP) joint. Radiographs show dorsal osteophytes and joint space narrowing. Examination demonstrates pain throughout the entire mid-range of MTP motion. Based on the Coughlin and Shurnas classification, what is the most appropriate surgical intervention?

Explanation

Pain throughout the mid-range of motion indicates Coughlin and Shurnas Grade 4 hallux rigidus. Cheilectomy is contraindicated because the articular cartilage is globally degenerated; therefore, first MTP arthrodesis is the gold standard treatment.

Question 65

A 19-year-old male athlete sustained a primary lateral patellar dislocation. MRI reveals a full-thickness osteochondral defect of the lateral femoral condyle with an intra-articular 15-mm loose body, as well as a complete tear of the MPFL at its femoral origin. What is the most appropriate management?

Explanation

While conservative management is standard for uncomplicated first-time dislocations, the presence of a sizable osteochondral loose body is a surgical indication. It requires excision or fixation, often combined with MPFL repair or reconstruction.

Question 66

A surgeon is planning a first MTP arthrodesis for a patient with end-stage hallux rigidus. To ensure optimal functional outcome and proper push-off during gait, in what position should the MTP joint be fused?

Explanation

Optimal position for 1st MTP fusion is 10-15 degrees of valgus, 15 degrees of dorsiflexion relative to the floor (or roughly 15-20 degrees relative to the first metatarsal), and neutral rotation. This allows for clearance during the swing phase and proper roll-over during stance.

Question 67

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?

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.

Question 68

A 48-year-old female with moderate hallux rigidus is treated conservatively with a custom orthosis. Which orthotic modification is most effective for decreasing symptoms associated with this condition?

Explanation

A rigid Morton extension or a stiff carbon fiber footplate limits dorsiflexion at the first MTP joint during the terminal stance phase of gait, effectively reducing pain in patients with hallux rigidus.

Question 69

Which of the following measurements is the most reliable method for assessing patella alta in a patient who has previously undergone an Osgood-Schlatter procedure?

Explanation

The Caton-Deschamps index relies on the articular surface of the patella and the anterior-superior angle of the tibial plateau, making it independent of the tibial tubercle position. This makes it ideal for patients with prior tubercle surgery or pathology like Osgood-Schlatter disease.

Question 70

A 13-year-old male with wide-open physes presents with recurrent patellar dislocations. Imaging confirms normal TT-TG distance but a torn MPFL. Surgical intervention is selected. Which of the following procedures is most appropriate while minimizing the risk of growth arrest?

Explanation

In skeletally immature patients with open physes, bony procedures like tibial tubercle osteotomies carry a high risk of physeal arrest (e.g., recurvatum deformity). Soft-tissue MPFL reconstruction utilizing physeal-sparing techniques (avoiding the distal femoral physis) is the treatment of choice.

Question 71

During a dorsal cheilectomy for hallux rigidus, a surgeon uses a standard dorsomedial approach to the first MTP joint. Which superficial nerve is at the greatest risk of iatrogenic injury during this exposure?

Explanation

The dorsomedial cutaneous nerve (a terminal branch of the superficial peroneal nerve) crosses over the extensor hallucis longus tendon and is highly vulnerable during the standard dorsomedial approach to the first MTP joint.

Question 72

A patient undergoes a tibial tubercle medialization osteotomy for a TT-TG distance of 24 mm. If the surgeon over-medializes the tubercle excessively, what is the most likely postoperative complication?

Explanation

Excessive medialization of the tibial tubercle alters the Q-angle to a varus alignment, unnaturally increasing the contact pressures in the medial tibiofemoral compartment and predisposing the patient to medial unicompartmental osteoarthritis.

Question 73

A 50-year-old female undergoes a cheilectomy for Coughlin and Shurnas Grade 2 hallux rigidus. To achieve adequate decompression and restore functional dorsiflexion, what percentage of the dorsal metatarsal head is typically resected?

Explanation

A standard cheilectomy involves the removal of the dorsal osteophyte along with approximately 20-30% of the dorsal articular surface of the first metatarsal head to effectively decompress the joint and improve dorsiflexion.

Question 74

The medial patellofemoral ligament (MPFL) serves as the primary restraint to lateral patellar translation at which of the following degrees of knee flexion?

Explanation

The MPFL provides approximately 50-60% of the restraining force against lateral patellar displacement during early knee flexion (0 to 30 degrees). Beyond 30 degrees, the patella engages the trochlear groove, which then becomes the primary osseous stabilizer.

Question 75

A patient with hallux rigidus undergoes a first MTP arthrodesis. Six months postoperatively, the patient complains of pain at the plantar aspect of the interphalangeal (IP) joint of the great toe, particularly during the toe-off phase of gait. Radiographs show solid fusion of the MTP joint. What surgical technical error most likely caused this complication?

Explanation

Fusing the first MTP joint in excessive plantarflexion prevents the patient from rolling over the toe properly during gait. The patient compensates by forcefully hyperextending the IP joint, leading to rapid IP joint arthritis and plantar IP pain.

Question 76

A 28-year-old female presents with patellar instability. MRI demonstrates isolated lateralization of the tibial tubercle. Her TT-TG distance is 22 mm, but her Tibial Tubercle-Posterior Cruciate Ligament (TT-PCL) distance is measured at 26 mm (Normal < 24 mm). What does an elevated TT-PCL distance primarily indicate in this context?

Explanation

The TT-PCL distance isolates true lateralization of the tibial tubercle relative to the proximal tibia. An elevated TT-TG with a normal TT-PCL suggests the lateralization is due to knee rotation, whereas an elevated TT-PCL confirms true structural lateralization of the tubercle itself.

Question 77

A 40-year-old physically active male presents with mild hallux rigidus (Coughlin Grade 1). He has preserved joint space but restricted functional dorsiflexion, causing pain when running. Conservative measures have failed. A Moberg procedure is planned. What does this specific procedure entail?

Explanation

The Moberg osteotomy is a dorsal closing-wedge osteotomy of the base of the proximal phalanx. It effectively shifts the available arc of motion dorsally to improve functional clearance during gait without altering the MTP joint mechanics.

Question 78

In evaluating a patient for hallux rigidus, what pathomechanical first-ray abnormality is most classically associated with the development of dorsal impingement and subsequent joint degeneration?

Explanation

Metatarsus primus elevatus (an abnormally elevated first metatarsal) alters the kinematics of the first MTP joint, causing the base of the proximal phalanx to impinge on the dorsal metatarsal head during terminal stance, predisposing the patient to hallux rigidus.

Question 79

Which anatomic landmark safely directs the femoral placement of the medial patellofemoral ligament (MPFL) graft on lateral fluoroscopy (Schöttle's point)?

Explanation

Schöttle's point is located 1 mm anterior to the posterior cortical line of the femur, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to Blumensaat's line.

Question 80

A 65-year-old female presents with significant first MTP joint pain and seeks a motion-preserving alternative to arthrodesis. She is offered a silicone implant arthroplasty. What is the most significant, specific long-term complication associated with this specific type of implant?

Explanation

Silicone implant arthroplasties in the first MTP joint have historically high rates of failure due to particulate wear debris, which provokes a massive foreign-body macrophage response, leading to silicone synovitis and severe cystic bone osteolysis.

ABOS Part I Orthopaedic Deformity Correction, Limb Reconstruction & Gait Analysis Review | Part 21914

ABOS Part I & AAOS OITE Orthopaedic Review: Patellofemoral Instability & Hallux Rigidus MCQs | Part 22225

Key Takeaway

ABOS Part I & AAOS OITE Orthopaedic Review: Patellofemoral Instability & Hallux Rigidus MCQs | Part 22225

Chapter Index