Adult Recon, Foot & Ankle, Deformity MCQs - Part 262

Question 1

A 65-year-old male presents with groin pain 5 years after a primary total hip arthroplasty (THA). The implant uses a metal-on-polyethylene bearing. Aspiration is negative for infection, but serum Cobalt and Chromium levels are significantly elevated, and MRI demonstrates a large adverse local tissue reaction (ALTR) around the hip. Which of the following component design factors most increases the risk of this specific complication?

Explanation

This patient has trunnionosis, a form of mechanically assisted crevice corrosion occurring at the modular head-neck junction. High horizontal femoral offset increases the lever arm and bending moments at the trunnion, which significantly increases micromotion, fretting, and subsequent corrosion. Large metal heads and increased horizontal offset are known mechanical risk factors for trunnionosis in metal-on-polyethylene THA.

Question 2

A 68-year-old female presents 1 year after a posterior-stabilized (PS) total knee arthroplasty (TKA) with a painful catching sensation in her anterior knee as she actively extends the knee from a flexed position. Which of the following implant design features or surgical techniques is the primary cause of this phenomenon?

Explanation

The patient is experiencing patellar clunk syndrome, which occurs when a fibronodular tissue mass develops on the undersurface of the quadriceps tendon just proximal to the patella. As the knee extends, this nodule catches on the anterior-superior edge of the intercondylar box of a posterior-stabilized femoral component. Modern PS designs have modified (rounded or lowered) the anterior box edge to decrease this complication.

Question 3

A 24-year-old male presents with bilateral progressive cavovarus feet. On examination, a Coleman block test is performed by placing his heel and lateral border of the foot on a block while allowing the first metatarsal to drop off the edge. During the test, his hindfoot varus corrects completely to neutral. What is the primary anatomic driver of his deformity, and what is the most appropriate initial bony surgical intervention?

Explanation

The Coleman block test distinguishes between flexible and rigid hindfoot varus in a cavovarus foot. If the hindfoot corrects to neutral when the plantarflexed first ray is allowed to drop off the block, the hindfoot deformity is flexible and primarily driven by the rigid, plantarflexed first metatarsal. The appropriate bony treatment addresses the forefoot driver with a dorsiflexion osteotomy of the first metatarsal.

Question 4

You are planning a deformity correction for a patient with a tibial malunion. During pre-operative templating, you determine the Center of Rotation of Angulation (CORA). If you perform your closing wedge osteotomy at a level proximal to the CORA and only correct the angular deformity (without any translation at the osteotomy site), what will be the effect on the mechanical axis?

Explanation

According to the rules of osteotomy formulated by Paley: If an osteotomy is performed at the CORA, angulation corrects the deformity fully. If the osteotomy is performed at a level different from the CORA, correcting the angular deformity without concurrent translation at the osteotomy site will result in a secondary translational deformity (the anatomical axis will end up with a zigzag or parallel shift).

Question 5

During a revision total hip arthroplasty, pre-operative radiographs demonstrate superior migration of the hip center by 3.5 cm. Intraoperatively, there is destruction of the teardrop and severe ischial osteolysis. However, Kohler's line remains intact. According to the Paprosky Acetabular Defect Classification, what is the defect type?

Explanation

Paprosky Type 3 defects involve severe bone loss with superior migration > 3 cm. Type 3A defects have an intact Kohler's line (no massive medial migration), though the teardrop and ischium are severely compromised. Type 3B defects are characterized by disruption of Kohler's line indicating massive medial migration (pelvic discontinuity may also be present).

Question 6

A 55-year-old female presents with severe medial ankle pain and a progressively flattening arch. She cannot perform a single-leg heel rise. Radiographs demonstrate advanced flatfoot deformity with talonavicular uncoverage of 45%. The subtalar joint shows no degenerative changes. Based on this Stage IIb Adult Acquired Flatfoot Deformity, what is the most appropriate surgical reconstruction?

Explanation

Stage IIb posterior tibial tendon dysfunction (PTTD) / adult acquired flatfoot deformity is characterized by flexible deformity but with significant forefoot abduction (typically defined as >30-40% talonavicular uncoverage). While an FDL transfer and MDCO address the medial and hindfoot components, the severe forefoot abduction requires a lateral column lengthening (e.g., Evans osteotomy or calcaneocuboid distraction arthrodesis) to adequately restore the foot's shape.

Question 7

A 70-year-old female sustains a complete patellar tendon rupture 2 years following a primary total knee arthroplasty. The diagnosis was delayed, and the patella is significantly retracted. Soft tissue quality is poor. What is the most reliable reconstructive option for this chronic extensor mechanism disruption?

Explanation

Chronic, retracted extensor mechanism ruptures post-TKA have dismal outcomes with primary repair. The gold standard for reconstruction in this setting involves a complete extensor mechanism allograft (using Achilles tendon with calcaneal bone block press-fit into the tibia, or a whole extensor mechanism allograft) or synthetic mesh reconstruction to restore the structural integrity of the extensor apparatus.

Question 8

You are treating a patient with severe hallux valgus (Intermetatarsal Angle = 18 degrees). You opt to perform a proximal crescentic osteotomy of the first metatarsal. Compared to diaphyseal osteotomies like the Scarf or Ludloff, what is a specific, well-known biomechanical risk associated with the proximal crescentic osteotomy?

Explanation

The proximal crescentic osteotomy is powerful for correcting large IM angles but is technically demanding in the sagittal plane. Due to the orientation of the osteotomy and weight-bearing forces, there is a high risk of dorsal malunion (dorsal elevation of the first metatarsal head). This unloads the first ray during the propulsive phase of gait, leading to transfer metatarsalgia under the lesser metatarsal heads.

Question 9

A 35-year-old male is undergoing tibial bone transport with a circular external fixator for a 6 cm segmental defect. The transport segment has successfully reached the docking site. After 8 weeks, radiographs show a persistent lucency at the docking site with no bridging callus. What is the most appropriate next step to stimulate union?

Explanation

In distraction osteogenesis / bone transport, delayed union or nonunion at the docking site is a common complication. The standard of care to achieve union when the transport segment reaches the target but fails to consolidate is preparation of the docking site ends, autologous bone grafting (e.g., from the iliac crest), and applying compression across the docking site.

Question 10

A patient presents with a painful total knee arthroplasty. Serum ESR and CRP are moderately elevated. A synovial aspiration yields 2,500 WBC/uL with 65% neutrophils. Because this fluid profile is equivocal, which of the following synovial fluid biomarkers provides the highest specificity for diagnosing a periprosthetic joint infection (PJI)?

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. In the setting of PJI, synovial fluid alpha-defensin has been shown to have extremely high sensitivity and specificity (often >95%), making it an excellent adjunctive test, especially in cases where cell counts are borderline or equivocal.

Question 11

Total ankle arthroplasty (TAA) has become a common alternative to arthrodesis for end-stage ankle osteoarthritis. Which of the following conditions is considered an absolute contraindication to performing a TAA?

Explanation

Charcot neuroarthropathy, loss of protective sensation, active infection, and severe uncorrectable malalignment are absolute contraindications for Total Ankle Arthroplasty (TAA). Older age, bilateral disease, minor AVN, and adjacent joint arthritis are often indications rather than contraindications (adjacent joint arthritis actually favors TAA over arthrodesis to preserve motion).

Question 12

A 3-year-old female presents with infantile Blount disease (Langenskiold Stage II). She has been compliant with full-time use of a Knee-Ankle-Foot Orthosis (KAFO) for 1 year, but her clinical and radiographic varus deformity has progressively worsened. What is the most appropriate next step in management?

Explanation

For infantile Blount disease, bracing is generally attempted in children under age 3 with early-stage disease (Langenskiold I-II). If bracing fails and the deformity progresses, surgical intervention is indicated before age 4 to prevent permanent physeal damage. The standard procedure is a proximal tibial and fibular valgus-producing osteotomy (often with slight overcorrection). Physeal bar resection is reserved for older children with confirmed physeal bridging (Stage IV-VI).

Question 13

During pre-operative templating for a total hip arthroplasty, the surgeon plans to place the acetabular component in a more medialized position compared to the native anatomy. What is the primary biomechanical effect of medializing the center of rotation of the hip?

Explanation

The hip joint acts as a class 1 lever. The joint reaction force is determined by the abductor force and body weight. Medializing the acetabular component moves the center of rotation closer to the body's center of gravity. This decreases the body weight lever arm, which effectively decreases the abductor force required to maintain a level pelvis, thereby decreasing the overall joint reaction force on the hip.

Question 14

A 25-year-old male sustains a midfoot injury. Weight-bearing radiographs reveal 2mm of widening between the first and second metatarsal bases. MRI confirms a rupture of the dorsal Lisfranc ligament and a sprain of the plantar Lisfranc ligament. Which statement regarding the biomechanics of the Lisfranc ligament complex is most accurate in guiding treatment?

Explanation

The Lisfranc ligament complex consists of dorsal, interosseous, and plantar components connecting the medial cuneiform to the second metatarsal base. The plantar Lisfranc ligament is the thickest and biomechanically strongest of the three. Disruption of the plantar ligament leads to significant instability requiring operative stabilization. Diastasis > 2mm on weight-bearing films is generally an indication for surgery.

Question 15

A surgeon performs a medial opening wedge high tibial osteotomy (HTO) to correct genu varum. During the procedure, the anterior and posterior cortices of the medial wedge are distracted equally using identical wedges. Given the triangular cross-sectional anatomy of the proximal tibia, what unintended sagittal plane change will occur?

Explanation

The proximal tibia is triangular, being wider posteriorly than anteriorly. If a medial opening wedge is opened equally anteriorly and posteriorly, the anterior opening is proportionally larger relative to the narrow anterior dimension. This effectively flexes the proximal fragment, leading to an unwanted INCREASE in the posterior tibial slope. To maintain the native slope, the osteotomy gap must typically be opened twice as much posteriorly as anteriorly.

Question 16

During a primary total hip arthroplasty using the direct anterior approach (DAA), the femur is prepared by extending, externally rotating, and adducting the leg. If excessive force is applied during femoral elevation using a bone hook without adequate capsular and short external rotator release, what is the most common iatrogenic fracture?

Explanation

In the direct anterior approach, achieving adequate femoral exposure requires displacing the femur anteriorly and laterally. As the femur is externally rotated and elevated, the greater trochanter moves posteriorly towards the ilium/posterior acetabulum. Without adequate release of the superior/posterior capsule and short external rotators (like the piriformis), excessive force with the femoral hook causes the greater trochanter to impinge, leading to a fracture of the greater trochanter.

Question 17

Based on recent large multicenter randomized controlled trials (e.g., Willits et al.) comparing operative versus non-operative management for acute Achilles tendon ruptures utilizing modern early functional rehabilitation protocols, what is the primary conclusion regarding re-rupture rates?

Explanation

Historically, operative treatment of Achilles tendon ruptures was favored due to lower re-rupture rates compared to prolonged cast immobilization. However, modern high-quality RCTs have demonstrated that when early weight-bearing and functional rehabilitation (using an active motion protocol) are employed, there is no statistically significant difference in re-rupture rates between operatively and non-operatively treated patients.

Question 18

A 55-year-old male presents with isolated medial compartment knee pain. Radiographs demonstrate bone-on-bone medial osteoarthritis. Which of the following conditions is considered a classic absolute contraindication for performing a medial Unicompartmental Knee Arthroplasty (UKA)?

Explanation

Inflammatory arthropathies (like Rheumatoid Arthritis) cause global synovial disease and systemic cartilage destruction, making them an absolute contraindication for UKA due to the high risk of rapid progression in the retained compartments. Historical contraindications like younger age (<60) and heavier weight (>90 kg) have been largely abandoned. An intact ACL is a prerequisite for a standard UKA.

Question 19

A 30-year-old male sustains a high-energy Hawkins Type III talar neck fracture. This fracture pattern involves a talar neck fracture with dislocation of the talar body from both the subtalar and tibiotalar joints. Which of the following best describes the disruption of the vascular supply to the talar body in this specific injury?

Explanation

The talus receives blood from 3 main sources: the artery of the tarsal canal (branch of posterior tibial artery, supplies majority of the body), artery of the tarsal sinus, and deltoid branches. A Hawkins Type III fracture implies dislocation of the talar body from both the subtalar and ankle joints, tearing all three major extraosseous blood supplies, which explains the very high rate of avascular necrosis (AVN), historically up to 100%.

Question 20

When planning a multiplanar deformity correction using a 6-axis hexapod circular external fixator (such as a Taylor Spatial Frame), the computer software requires accurate 'mounting parameters' to calculate the strut adjustments. Which of the following correctly defines the mounting parameters?

Explanation

In hexapod circular frame software, 'mounting parameters' define the exact position and orientation of the reference ring in three-dimensional space relative to the corresponding reference bone fragment. This includes AP view translation, lateral view translation, and axial plane rotation relative to the bone's true mechanical/anatomical axis.

Question 21

A 65-year-old female presents with groin pain and swelling three years following a metal-on-metal total hip arthroplasty. Serum cobalt and chromium levels are significantly elevated. Aspiration yields sterile, cloudy fluid. Histological examination of the periprosthetic tissue reveals a dense perivascular lymphocytic infiltrate with macrophages and focal tissue necrosis. This adverse local tissue reaction (ALTR) is primarily mediated by which of the following immunologic mechanisms?

Explanation

Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) is the histological hallmark of an adverse local tissue reaction (ALTR) in metal-on-metal implants. It is characterized by a delayed-type (Type IV) hypersensitivity response mediated by T-lymphocytes reacting to metal ions (typically cobalt or chromium) acting as haptens.

Question 22

A 55-year-old female presents with a progressive flatfoot deformity. Examination shows an inability to perform a single-limb heel rise, 'too many toes' sign, and severe forefoot abduction. Weight-bearing radiographs reveal greater than 40% uncoverage of the talonavicular joint and a talonavicular fault, but flexible hindfoot and midfoot joints. In addition to a flexor digitorum longus (FDL) transfer and medial calcaneal slide osteotomy, which of the following procedures is most strongly indicated to correct her specific multiplanar deformity?

Explanation

This patient has Stage IIb posterior tibial tendon dysfunction (PTTD), differentiated from Stage IIa by significant forefoot abduction (typically >30-40% talonavicular uncoverage). To effectively correct the severe forefoot abduction and restore the arch in a flexible foot, a lateral column lengthening (Evans osteotomy) is indicated in conjunction with soft tissue reconstruction (FDL transfer) and hindfoot alignment (medializing calcaneal osteotomy).

Question 23

According to the principles of deformity correction (Ilizarov/Paley), if an osteotomy is performed at a level different from the center of rotation of angulation (CORA), but the axis of correction of angulation (ACA) is placed exactly at the CORA, what will be the resulting geometric effect on the bone fragments?

Explanation

This relies on Paley's Deformity Rule 2: When the ACA passes through the CORA, but the osteotomy is at a different level, the correction will result in angulation and translation at the osteotomy site, but the proximal and distal mechanical axes will become collinear and the overall alignment is properly restored.

Question 24

A 70-year-old male with severe ankylosing spondylitis and a fused lumbar spine to the sacrum (L1-S1) is undergoing total hip arthroplasty. Spinopelvic assessment reveals that his pelvic tilt does not change when moving from a standing to a seated position. Compared to a patient with normal spinopelvic mobility, how should the acetabular component be positioned to minimize the risk of impingement and dislocation?

Explanation

In a patient with a stiff spino-pelvic junction (stuck standing), the pelvis fails to roll backward (posterior pelvic tilt) when the patient sits. Because the pelvis remains relatively anteriorly tilted in flexion, there is a high risk of anterior femoral neck impingement on the anterior rim of the cup during sitting, leading to posterior dislocation. To compensate for this lack of dynamic functional anteversion, the surgeon must place the acetabular cup in greater anteversion and inclination than the standard safe zone.

Question 25

A 62-year-old male undergoes surgical treatment for severe insertional Achilles tendinopathy with a large retrocalcaneal exostosis. During the extensive debridement of calcific tendinosis and bone, approximately 60% of the Achilles tendon insertion is detached from the calcaneus. What is the most appropriate next step in management?

Explanation

When debridement of insertional Achilles tendinopathy requires detachment of more than 50% of the tendon insertion, the repair is structurally compromised, and the risk of rupture is high. Augmentation is indicated. Flexor hallucis longus (FHL) transfer is the gold standard because it provides a strong, vascularized tendon that fires in phase with the gastrocsoleus complex.

Question 26

A 68-year-old female presents with a painful catching sensation in her knee 18 months after a primary posterior-stabilized (PS) total knee arthroplasty. The catching predictably occurs as the knee extends from 45 degrees to 30 degrees of flexion. Radiographs show well-fixed components with appropriate sizing. What is the most likely etiology of her symptoms?

Explanation

This presentation is classic for Patellar Clunk Syndrome, a well-described complication of older posterior-stabilized (PS) TKA designs. A fibrous nodule forms at the superior pole of the patella. As the knee extends from flexion, the nodule catches within the intercondylar box of the femoral component, then suddenly pops out (clunks) at around 30 to 45 degrees of extension.

Question 27

In the process of manufacturing highly cross-linked polyethylene (HXLPE) for total joint arthroplasty, the material is irradiated to create cross-links. Following irradiation, the polyethylene undergoes a thermal treatment known as 'remelting' (heating above the melting point of 135°C). What is the primary mechanical or chemical trade-off of the remelting process compared to 'annealing' (heating below the melting point)?

Explanation

Irradiation of polyethylene generates free radicals that cause long-term oxidative degradation. Remelting (heating above the melting point) effectively extinguishes all free radicals, yielding excellent oxidation resistance. However, it decreases the crystallinity of the polymer, which reduces its yield strength, ultimate tensile strength, and fatigue crack propagation resistance. Annealing (below melting point) preserves crystallinity and mechanical strength but leaves some free radicals, risking future oxidation.

Question 28

A 28-year-old male sustains a closed, isolated, completely displaced fracture of the talar neck (Hawkins Type III). He undergoes urgent open reduction and internal fixation. At 8 weeks postoperatively, a distinct subchondral radiolucent band is visible across the talar dome on the mortise radiograph. What does this radiographic finding indicate?

Explanation

The finding described is the Hawkins sign. It is a subchondral radiolucency in the talar dome that typically appears 6 to 8 weeks after injury. It represents subchondral osteopenia secondary to disuse and active hyperemia, which requires intact vascularity. Thus, a positive Hawkins sign is a highly reliable indicator that the talar body is viable and that widespread avascular necrosis (AVN) will not occur.

Question 29

Which of the following clinical scenarios is widely accepted as an absolute contraindication to resection of a physeal bar and interposition grafting in a pediatric patient with a post-traumatic growth arrest?

Explanation

Physeal bar resection and interposition (e.g., with fat or cranioplast) is indicated to restore longitudinal growth and correct angular deformity. Generally accepted contraindications include when the physeal bar involves greater than 50% of the cross-sectional area of the physis, or when the patient has less than 2 years of remaining skeletal growth, as the procedure will not yield clinically meaningful correction in these cases.

Question 30

A 24-year-old elite athlete sustains a purely ligamentous Lisfranc injury with 3 mm of widening between the medial cuneiform and the base of the second metatarsal. Based on prospective randomized data comparing open reduction internal fixation (ORIF) to primary arthrodesis for this specific injury pattern, primary arthrodesis is associated with which of the following?

Explanation

In purely ligamentous Lisfranc injuries (without associated large bony fractures), primary arthrodesis of the medial column (TMT 1-3) has been shown to yield superior functional outcomes and lower rates of secondary surgeries (such as hardware removal or conversion to fusion due to post-traumatic arthritis) compared to ORIF. This was classically demonstrated in the prospective randomized study by Ly and Coetzee (JBJS 2006).

Question 31

A 52-year-old male with long-standing, poorly controlled type 2 diabetes presents with a red, hot, and severely swollen left foot. He is afebrile and has normal white blood cell counts. Radiographs show extensive bone fragmentation, subluxation of the tarsometatarsal joints, and osseous debris, with no distinct fracture lines. According to the Eichenholtz classification, what is the stage of this Charcot arthropathy and what is the most appropriate initial management?

Explanation

The patient is in Eichenholtz Stage I (Developmental/Fragmentation phase) of Charcot neuroarthropathy, characterized clinically by a red, hot, swollen foot and radiographically by bone fragmentation, joint subluxation/dislocation, and debris. The gold standard initial management to halt progression and prevent further deformity is immobilization with a total contact cast (TCC) and restricted weight-bearing until the acute inflammatory phase resolves and the bones begin to coalesce (Stage II).

Question 32

Synovial fluid analysis is performed to evaluate a painful total knee arthroplasty for periprosthetic joint infection (PJI). An alpha-defensin test is ordered. Alpha-defensin is a highly accurate biomarker for PJI because it is an antimicrobial peptide secreted primarily by which of the following cells in response to pathogens?

Explanation

Alpha-defensin is an antimicrobial peptide released predominantly by human neutrophils (polymorphonuclear leukocytes) into the synovial fluid when encountering invading pathogens. Its concentration remains high in infected joints regardless of prior antibiotic administration, making it a highly sensitive and specific biomarker for diagnosing periprosthetic joint infection (PJI).

Question 33

A 45-year-old female presents with hallux rigidus. She complains of dorsal impingement pain at the first metatarsophalangeal (MTP) joint, specifically with forced dorsiflexion. Clinical exam shows she has 40 degrees of dorsiflexion. Radiographs reveal dorsal osteophytes, but the joint space is generally preserved and there are no large cystic changes. According to the Coughlin and Shurnas classification, what is her grade and most appropriate surgical treatment if conservative measures fail?

Explanation

The patient has Coughlin and Shurnas Grade 2 hallux rigidus (mild-to-moderate joint space narrowing, dorsal osteophytes, dorsiflexion >30 degrees but pain at the end of range). The treatment of choice for symptomatic Grade 1 and 2 hallux rigidus that fails conservative management is a dorsal cheilectomy (excision of the dorsal osteophytes and the dorsal one-third of the metatarsal head).

Question 34

A 15-year-old male with Charcot-Marie-Tooth disease presents with a rigid cavovarus foot deformity. During the Coleman block test, placing the lateral heel on a block and allowing the first metatarsal to drop off significantly corrects the hindfoot varus to neutral. This finding indicates that the primary deforming force driving the hindfoot varus is the plantarflexed first ray. Which muscle imbalance is directly responsible for this plantarflexed first ray?

Explanation

In a classic cavovarus foot (frequently seen in CMT), the hallmark early muscle imbalance is the overactivity of the peroneus longus muscle relative to a weak tibialis anterior. The strong peroneus longus forcefully plantarflexes the first ray. When the foot hits the ground, this rigid plantarflexed first ray acts as a kickstand, driving the hindfoot into compensatory varus. The Coleman block test confirms if the hindfoot varus is driven by this forefoot pathology.

Question 35

During deep flexion of a healthy, native human knee, distinct kinematic patterns are observed between the medial and lateral compartments. Which of the following best describes the normal kinematics of the femorotibial joint as the knee moves from extension into deep flexion?

Explanation

In the native knee during flexion, the medial femoral condyle moves very little in the anteroposterior plane (often termed a 'medial pivot'), while the lateral femoral condyle undergoes significant posterior translation (rollback). Because the lateral side rolls back much more than the medial side, this relative movement causes the tibia to internally rotate relative to the femur during flexion.

Question 36

A 55-year-old male undergoes a primary total hip arthroplasty using a ceramic-on-ceramic bearing surface. Three years postoperatively, he presents complaining of an audible 'squeaking' sound coming from the hip with normal walking. Radiographs and imaging are obtained. Squeaking in a ceramic-on-ceramic THA is most strongly associated with which of the following mechanical phenomena?

Explanation

Squeaking is a specific complication of ceramic-on-ceramic total hip arthroplasties. It is strongly correlated with edge loading and 'stripe wear' on the retrieved components. Edge loading typically occurs due to suboptimal acetabular component positioning (e.g., excessive cup anteversion or high inclination angle), which shifts the joint contact forces to the very edge of the liner, disrupting the fluid film lubrication and causing the components to vibrate and squeak.

Question 37

A 22-year-old collegiate basketball player sustains a fracture of the proximal fifth metatarsal. Radiographs show a transverse fracture line located 1.5 cm distal to the tuberosity, extending into the fourth-fifth intermetatarsal articulation (Zone 2, Jones fracture). The high risk of nonunion in this specific fracture pattern is primarily attributed to the vascular anatomy of the fifth metatarsal. Which of the following accurately describes the blood supply rendering this area vulnerable?

Explanation

A true Jones fracture (Zone 2) occurs at the metaphyseal-diaphyseal junction of the fifth metatarsal. This specific region is a vascular watershed area. The tuberosity (Zone 1) is richly supplied by metaphyseal arteries, and the diaphysis (Zone 3) is supplied by the nutrient artery (which enters medially and branches proximally and distally). Zone 2 lies at the tenuous junction of these two blood supplies, making it highly susceptible to delayed union or nonunion.

Question 38

A surgeon performs a primary total hip arthroplasty via a direct lateral (Hardinge) approach, which involves splitting the gluteus medius and minimus muscles. Postoperatively, the patient has a severe, unresolving Trendelenburg lurch. Assuming the repair is intact, the surgeon most likely injured a major nerve during the proximal split of the abductor muscles. To avoid this injury, the proximal dissection must stay within what safe distance from the tip of the greater trochanter?

Explanation

The superior gluteal nerve innervates the gluteus medius, gluteus minimus, and tensor fasciae latae. During the direct lateral approach to the hip, splitting the gluteus medius too far proximally risks transecting the inferior branch of the superior gluteal nerve, leading to abductor paralysis and a permanent Trendelenburg gait. The standard safe zone limits the proximal split to 3 to 5 cm (typically quoted as up to 5 cm) proximal to the tip of the greater trochanter.

Question 39

A 40-year-old male is undergoing tibial lengthening via distraction osteogenesis using a circular Ilizarov external fixator. Following the corticotomy, there is a required waiting period before the commencement of distraction. What is the optimal 'latent period' in adults, and what is its primary biological purpose?

Explanation

The latent period is the time between the corticotomy/osteotomy and the initiation of distraction. In an adult undergoing tibial lengthening, the optimal latent period is typically 7 to 10 days. This allows the initial inflammatory phase to subside and permits the ingrowth of delicate capillaries and primitive mesenchymal tissue (early soft callus). If distraction begins too early (e.g., 0-3 days), the tissue is torn, leading to poor regenerate (hypotrophic). If it is too long, premature consolidation occurs.

Question 40

An 82-year-old osteoporotic female sustains a periprosthetic fracture of the femur around a cemented, polished, tapered total hip stem. Radiographs show a fracture at the tip of the stem with extension proximally, resulting in severe comminution and complete loss of proximal femoral bone stock. The femoral stem is grossly loose. The patient is limited to household ambulation. What is the most reliable surgical treatment option for this Vancouver B3 fracture?

Explanation

This is a Vancouver B3 periprosthetic fracture (fracture around a loose stem with severely deficient proximal bone stock). In an elderly, low-demand patient with severe osteoporosis and comminution, attempting a complex reconstruction (like impaction grafting or extensively coated stems that rely on poor bone for fixation) carries a high risk of failure and prolonged non-weight-bearing. Proximal femoral replacement (megaprosthesis) provides immediate stability, allows early full weight-bearing, and is the most reliable option.

Question 41

According to Paley's rules of deformity correction, if the axis of correction (hinge) is placed at the Center of Rotation of Angulation (CORA) but the osteotomy is performed at a different level, which of the following describes the resulting geometric alignment?

Explanation

Paley's Rule 2 states that if the hinge (axis of correction) is placed at the CORA but the osteotomy is performed at a different level, the mechanical axis will be perfectly realigned, but the bony ends at the osteotomy site will undergo translation. Rule 1 (hinge and osteotomy at CORA) results in pure angulation. Rule 3 (hinge away from CORA) results in mechanical axis deviation.

Question 42

An 82-year-old female presents with a periprosthetic femur fracture around a cemented femoral stem inserted 15 years ago. Radiographs demonstrate a fracture involving the proximal third of the femur, subsidence of the stem, and severe proximal femoral osteolysis with complete loss of the medial calcar. Which of the following is the most appropriate surgical management?

Explanation

This is a Vancouver B3 periprosthetic femur fracture, characterized by a fracture around a loose stem in the setting of poor proximal bone stock. In elderly, low-demand patients with severe proximal bone loss, a proximal femoral replacement (megaprosthesis) allows for immediate weight-bearing and provides a more reliable construct than attempting complex allograft reconstructions.

Question 43

Which of the following conditions is generally considered an absolute contraindication for a Total Ankle Arthroplasty (TAA)?

Explanation

Charcot neuroarthropathy or severe peripheral neuropathy with loss of protective sensation is an absolute contraindication for Total Ankle Arthroplasty due to the unacceptably high risk of implant failure, aseptic loosening, and progressive joint destruction. Advanced age, prior trauma, subtalar arthritis (which can be fused concurrently), and mild-to-moderate obesity are not absolute contraindications.

Question 44

A 68-year-old male is undergoing primary Total Hip Arthroplasty (THA). He has a history of a multilevel lumbar spinal fusion from L2 to the sacrum. Standing and sitting lateral radiographs reveal that his pelvic tilt changes by less than 5 degrees between the two positions. To minimize the risk of posterior dislocation when sitting, how should the surgeon adjust the acetabular cup positioning compared to a patient with normal spinopelvic mobility?

Explanation

Patients with a stiff lumbopelvic junction (e.g., from multilevel fusion) lack normal posterior pelvic rollback when transitioning from standing to sitting. Because the pelvis does not tilt posteriorly to naturally increase functional acetabular anteversion, the anterior femur may impinge on the anterior pelvis/cup, leading to a posterior dislocation. The surgeon must compensate by increasing the structural anteversion and inclination of the acetabular cup.

Question 45

Patellar clunk syndrome is a known complication following Total Knee Arthroplasty (TKA). It is most frequently associated with which of the following implant designs?

Explanation

Patellar clunk syndrome occurs when a fibrous nodule forms at the superior pole of the patella and catches within the intercondylar notch of the femoral component as the knee extends from a flexed position. It is almost exclusively associated with posterior-stabilized (PS) TKA designs, particularly those with a sharp or high, narrow intercondylar box that irritates the quadriceps tendon.

Question 46

A 45-year-old male requires surgical reconstruction for a chronic Achilles tendon rupture with a 6-cm defect. A flexor hallucis longus (FHL) tendon transfer is planned. Which of the following represents a biomechanical advantage of the FHL transfer over a flexor digitorum longus (FDL) transfer for this indication?

Explanation

The FHL is the preferred transfer for chronic Achilles tendon defects because it is the second strongest plantarflexor of the foot (behind the triceps surae), possessing a physiologic cross-sectional area nearly twice that of the FDL. Furthermore, its anatomical position allows for an axis of pull that is highly coaxial with the Achilles tendon, and it fires in phase with the gastrosoleus complex.

Question 47

When utilizing a Taylor Spatial Frame (hexapod external fixator) for complex deformity correction, accurate data entry into the software is critical. What do the 'mounting parameters' specifically describe?

Explanation

In the software of a hexapod circular fixator like the Taylor Spatial Frame, 'mounting parameters' dictate exactly where the hardware (specifically the reference ring) is located in 3D space relative to the reference bone fragment (origin). The other parameters include deformity parameters (describing the bone segments relative to each other) and frame parameters (size of rings and struts).

Question 48

A 55-year-old male presents with groin pain three years after a primary metal-on-polyethylene Total Hip Arthroplasty utilizing a standard titanium stem and a 36-mm cobalt-chrome head. Radiographs show a well-fixed implant without osteolysis. A MARS MRI reveals a large cystic pseudotumor around the hip joint. Laboratory analysis is most likely to show which of the following metal ion profiles?

Explanation

This clinical picture describes mechanically assisted crevice corrosion (MACC), or trunnionosis, occurring at the modular head-neck junction of a THA. In metal-on-polyethylene bearings, corrosion at a CoCr head/Titanium neck trunnion typically releases significantly more cobalt than chromium into the serum. In contrast, metal-on-metal articular wear typically produces equally elevated levels of both cobalt and chromium.

Question 49

A 12-year-old boy undergoes resection of a symptomatic calcaneonavicular coalition. To minimize the risk of coalition recurrence, the surgeon plans to interpose tissue into the resection gap. Which of the following is the most commonly utilized autogenous tissue for this specific interposition?

Explanation

Following resection of a calcaneonavicular coalition, interposition of the extensor digitorum brevis (EDB) muscle belly or a free fat graft into the resection defect is the gold standard technique to prevent postoperative hematoma organization and recurrent ossification (re-coalition).

Question 50

The synovial fluid alpha-defensin test is highly accurate in diagnosing periprosthetic joint infection. Alpha-defensin is an antimicrobial peptide primarily secreted by which of the following cells in response to an infectious pathogen?

Explanation

Alpha-defensin is a biomarker utilized for the diagnosis of periprosthetic joint infection (PJI). It is an antimicrobial peptide that is released primarily by activated neutrophils in the presence of pathogens. It integrates into microbial membranes, causing cell death, and its levels remain elevated in synovial fluid even in the presence of concurrent antibiotic therapy.

Question 51

A 2-year-old obese child presents with bilateral genu varum. Standing radiographs reveal an irregular metaphyseal beak on the medial proximal tibia. Which of the following radiographic measurements, if greater than 16 degrees, most strongly predicts the progression of this condition to infantile Blount's disease rather than physiologic bowing?

Explanation

The metaphyseal-diaphyseal angle, also known as the Drennan angle, is measured on an AP radiograph of the tibia. An angle greater than 16 degrees is highly predictive of progressive infantile Blount's disease. Angles less than 10 degrees are typical of physiologic bowing and tend to resolve spontaneously.

Question 52

During a revision Total Knee Arthroplasty for aseptic loosening, the surgeon utilizes a highly constrained implant. Extensive distal femoral bone loss requires the use of distal femoral augments; however, the surgeon inadvertently undersizes the augments and compensates by inserting a significantly thicker tibial polyethylene insert to balance the extension gap. Which of the following postoperative complications is the direct geometric consequence of this technical error?

Explanation

By not restoring the distal femoral joint line with adequate augments and instead using a thick tibial poly, the joint line is elevated proximally. Because the length of the patellar tendon remains unchanged, the patella is drawn closer to the new, elevated joint line. This creates the radiographic and clinical appearance of a low patella relative to the joint line, known as pseudo-patella baja. True patella baja involves actual shortening of the patellar tendon.

Question 53

A 55-year-old female with Stage IIb Adult Acquired Flatfoot Deformity (AAFD) is planned for reconstruction. The surgeon intends to perform a medializing calcaneal osteotomy and a flexor digitorum longus (FDL) transfer to the navicular. What specific radiographic finding is the primary indication to add a lateral column lengthening (Evans osteotomy) to this surgical construct?

Explanation

Stage IIb AAFD denotes a flexible flatfoot with significant forefoot abduction. Forefoot abduction is assessed radiographically on the AP view of the foot via talonavicular uncoverage. When talonavicular uncoverage exceeds 40%, a lateral column lengthening (Evans calcaneal osteotomy) is indicated to restore the length of the lateral column and swing the forefoot out of abduction, pivoting around the intact plantar medial calcaneonavicular (spring) ligament complex.

Question 54

A newborn is diagnosed with congenital fibular hemimelia. While the absent lateral rays and leg length discrepancy are prominent, which of the following is the most common concurrent intra-articular anomaly of the knee in these patients?

Explanation

Fibular hemimelia is frequently associated with several other anomalies, including shortening of the femur, ball-and-socket ankle joint, tarsal coalitions, and absence of the lateral rays of the foot. In the knee, the most common intra-articular anomaly is hypoplasia or complete absence of the anterior cruciate ligament (ACL).

Question 55

In the setting of a revision Total Hip Arthroplasty, pelvic discontinuity represents a severe challenge. Which of the following anatomically defines a pelvic discontinuity?

Explanation

Pelvic discontinuity is defined as a complete transverse separation of the superior hemipelvis (ilium) from the inferior hemipelvis (ischium and pubis) resulting from an ununited fracture or severe bone loss directly through the acetabulum. Treatment usually requires complex reconstruction such as custom triflange implants, cup-cage constructs, or distraction osteogenesis to bridge the defect.

Question 56

During the physical examination of a patient with a cavovarus foot deformity, the Coleman block test is performed. The patient stands with the heel and lateral border of the foot on a 1-inch block, allowing the first metatarsal to drop freely off the medial edge. If the hindfoot varus corrects to neutral during this test, what is the primary driver of the hindfoot deformity?

Explanation

The Coleman block test evaluates the flexibility of the hindfoot and differentiates forefoot-driven from hindfoot-driven varus. If placing the foot on a lateral block (which eliminates the effect of the plantarflexed first ray by allowing it to drop) causes the hindfoot varus to correct, the deformity is flexible and is driven by the rigid plantarflexed first ray. A dorsiflexion osteotomy of the 1st metatarsal is generally required.

Question 57

A patient suffers an extensor mechanism disruption three years after a Total Knee Arthroplasty. Reconstruction utilizing a synthetic mesh (e.g., Marlex) is planned. To optimize the chance of a successful clinical outcome and active extension, what is the critical step during the intraoperative tensioning of the graft?

Explanation

When performing an extensor mechanism reconstruction post-TKA using a synthetic Marlex mesh (or allograft), it is universally recommended to suture the construct under maximal tension with the knee in full extension (0 degrees). Given that these grafts universally stretch out over time, any initial laxity or tensioning in flexion will result in a clinically significant persistent extensor lag.

Question 58

A 14-year-old girl with a 4 cm leg length discrepancy is being evaluated for an intramedullary motorized magnetic lengthening nail. Which of the following is an absolute contraindication to utilizing this specific device technology?

Explanation

Motorized magnetic lengthening nails (such as the PRECICE nail) contain complex internal magnetic driving mechanisms. Placing a patient with this device into a Magnetic Resonance Imaging (MRI) scanner can lead to implant demagnetization, spontaneous lengthening or shortening, and implant heating/failure. Thus, an absolute requirement for ongoing MRI studies (e.g., for tumor surveillance) is an absolute contraindication for a magnetic lengthening nail.

Question 59

A 58-year-old diabetic patient presents with a swollen, erythematous, and warm foot without an open ulcer. Laboratory markers (WBC, ESR, CRP) are within normal limits. Radiographs demonstrate periarticular debris, subluxation of the tarsometatarsal joints, and early fragmentation. According to the Eichenholtz classification, what stage is this, and what is the standard initial treatment?

Explanation

The clinical picture represents Eichenholtz Stage I (Development/Fragmentation) of Charcot neuroarthropathy, characterized clinically by the 'red, hot, swollen' foot and radiographically by fragmentation, debris, and subluxation. Infection must be ruled out (which is likely here given normal labs and no ulcer). The gold standard of care during the active Stage I phase is immobilization and offloading, typically utilizing a total contact cast (TCC), to prevent progressive deformity.

Question 60

In a metal-on-polyethylene Total Hip Arthroplasty, what specific design factor significantly increases the risk of mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction?

Explanation

Mechanically assisted crevice corrosion (MACC), or trunnionosis, is mediated by micromotion and fretting at the taper junction between the stem and the modular head. The use of larger diameter femoral heads (e.g., >36 mm) increases the frictional torque and lever arm acting on the head-neck junction during gait, significantly increasing the risk of trunnionosis. Ceramic heads are essentially inert and reduce the risk of corrosion.

Question 61

A 72-year-old female presents with recurrent posterior dislocations following a revision total hip arthroplasty (THA). Intraoperative exploration reveals a severely deficient abductor mechanism but well-fixed acetabular and femoral components in acceptable alignment. Which of the following bearing surface options is most appropriate to maximize stability and minimize the risk of mechanical failure in this patient?

Explanation

Dual mobility articulations provide high jump distance and excellent stability, making them ideal for patients with abductor deficiency and recurrent instability. Constrained liners have a high risk of mechanical failure and loosening in the setting of absent abductors.

Question 62

A 55-year-old female presents with progressive foot pain and flattening of her medial longitudinal arch. On examination, she is unable to perform a single-limb heel rise. Weight-bearing radiographs demonstrate >50% uncovering of the talonavicular joint. Examination confirms the hindfoot deformity remains flexible. What is the most appropriate surgical intervention?

Explanation

This patient has a Stage IIB adult-acquired flatfoot deformity (flexible, >50% TN uncovering/forefoot abduction). Treatment requires soft tissue reconstruction (FDL transfer) combined with both a medial displacement calcaneal osteotomy and lateral column lengthening to correct the severe forefoot abduction.

Question 63

In the preoperative planning for a high tibial osteotomy to correct a varus deformity, the surgeon applies Osteotomy Rule 1. According to this principle, what is the expected geometric outcome if both the osteotomy cut and the mechanical hinge are located exactly at the center of rotation of angulation (CORA)?

Explanation

Osteotomy Rule 1 states that if the osteotomy and the mechanical hinge are both placed at the CORA, the bone ends will angulate purely without any translational deformity.

Question 64

A 65-year-old female undergoes a primary total knee arthroplasty (TKA). Postoperatively, she develops lateral patellar subluxation. Radiographic and CT evaluation reveals that the tibial component was inadvertently placed in excessive internal rotation. How does this specific malrotation alter the biomechanics of the extensor mechanism?

Explanation

Internal rotation of the tibial component effectively lateralizes the tibial tubercle relative to the femoral trochlea. This increases the Q angle, directly causing lateral patellar maltracking and subluxation.

Question 65

A 25-year-old male sustains a purely ligamentous Lisfranc injury. Based on high-level randomized controlled trials comparing open reduction internal fixation (ORIF) to primary partial midfoot arthrodesis for this specific injury pattern, which of the following is true regarding primary arthrodesis?

Explanation

Randomized controlled trials have demonstrated that primary arthrodesis for purely ligamentous Lisfranc injuries leads to lower reoperation rates (primarily avoiding hardware removal) and equal or superior functional outcomes compared to ORIF.

Question 66

An 11-year-old female presents with a 3 cm leg length discrepancy due to a congenital short femur. Her skeletal age matches her chronological age. Using the Menelaus method for growth prediction, how much remaining growth is typically expected from the distal femoral physis per year until skeletal maturity?

Explanation

The Menelaus method estimates growth from the distal femur at approximately 10 mm (3/8 inch) per year and from the proximal tibia at 6 mm (1/4 inch) per year until growth ceases (typically at age 14 for girls).

Question 67

An 82-year-old male presents with acute thigh pain and inability to bear weight after a mechanical fall. Radiographs demonstrate a fracture around the stem of his cementless total hip arthroplasty, with obvious subsidence of the femoral component. The fracture extends just distal to the lesser trochanter. What is the most appropriate surgical management?

Explanation

This is a Vancouver B2 periprosthetic fracture (fracture around a loose stem with adequate proximal bone stock). The standard of care is revision to a longer, distally engaging stem that bypasses the most distal fracture line by at least two cortical diameters.

Question 68

A 52-year-old male with long-standing poorly controlled diabetes presents with a unilaterally swollen, erythematous, and warm foot. He denies recent trauma or pain. Pulses are bounding. Radiographs demonstrate periarticular debris, fragmentation, and subluxation at the tarsometatarsal joints. What is the most appropriate initial treatment?

Explanation

The patient is presenting with acute Eichenholtz Stage I (fragmentation stage) Charcot neuroarthropathy. The gold standard for initial management of the acute, active phase is offloading and immobilization using a total contact cast to prevent further deformity.

Question 69

A 62-year-old male presents with groin pain 7 years after a primary metal-on-polyethylene total hip arthroplasty. Aspiration is negative for infection, but serum metal ions show an elevated Cobalt level with a relatively normal Chromium level. MRI demonstrates a large pseudotumor. What is the primary pathophysiologic mechanism for this failure?

Explanation

Elevated Cobalt out of proportion to Chromium in a metal-on-polyethylene THA strongly indicates trunnionosis. This is caused by mechanically assisted crevice corrosion (MACC) at the modular head-neck taper junction.

Question 70

A 45-year-old recreational runner fails 6 months of conservative management for severe insertional Achilles tendinopathy and a large Haglund's deformity. Surgical intervention is planned, involving detachment of the Achilles tendon, resection of the bursa and prominent bone, and reattachment. What is the generally accepted maximum percentage of the Achilles insertion that can be detached before a flexor hallucis longus (FHL) transfer is required for augmentation?

Explanation

During debridement for insertional Achilles tendinopathy, up to 50% of the tendon insertion can be detached and primarily repaired using suture anchors. If >50% is compromised, augmentation with an FHL transfer is generally recommended.

Question 71

When utilizing a high-offset femoral stem in primary total hip arthroplasty, which of the following describes the resulting biomechanical effect compared to a standard-offset stem, assuming vertical height remains unchanged?

Explanation

Increasing femoral offset lateralizes the femur, which directly increases the abductor moment arm. A longer abductor lever arm requires less abductor muscle force to maintain pelvic stability, thereby decreasing the overall joint reactive forces across the hip.

Question 72

A 58-year-old male with end-stage post-traumatic ankle osteoarthritis is scheduled for an open ankle arthrodesis. To optimize postoperative gait mechanics and minimize adjacent joint arthritis, what is the most appropriate target position for the fusion?

Explanation

The optimal position for ankle arthrodesis is neutral dorsiflexion (0 degrees), 0 to 5 degrees of hindfoot valgus, and external rotation matching the contralateral side (typically 5 to 10 degrees) to facilitate normal rollover during gait.

Question 73

During a primary total knee arthroplasty, using a measured resection technique, the surgeon evaluates the trial components. The knee is found to be perfectly balanced in full extension but excessively tight in 90 degrees of flexion. Which of the following adjustments is the most appropriate next step to balance the knee?

Explanation

A tight flexion gap with a balanced extension gap requires increasing the flexion gap volume exclusively. This can be achieved by downsizing the femoral component (to decrease the posterior condylar offset), releasing the PCL (in a CR knee), or increasing the posterior slope of the tibia.

Question 74

A 65-year-old female presents with severe pain and stiffness in her first metatarsophalangeal (MTP) joint. Examination reveals less than 10 degrees of total dorsiflexion and severe pain in the mid-arc of motion. Radiographs demonstrate diffuse joint space narrowing, large dorsal osteophytes, and subchondral sclerosis. What is the most reliable, gold-standard surgical treatment for this condition?

Explanation

This patient has Grade 3/4 hallux rigidus (diffuse arthritis, severe restriction of motion, pain in mid-arc). The gold standard treatment providing the most reliable pain relief and functional improvement is a first MTP arthrodesis.

Question 75

A 54-year-old male who underwent a ceramic-on-ceramic total hip arthroplasty 3 years ago reports a loud, audible squeaking sound from his hip when walking or bending. What acetabular component orientation is most strongly associated with the onset of this specific phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading of the components. Edge loading most frequently occurs when the acetabular cup is placed in excessive inclination (steep angle) and excessive anteversion.

Question 76

When utilizing a Taylor Spatial Frame (TSF) for complex limb deformity correction, the computer software requires the definition of a 'Reference Ring'. Which of the following best defines the reference ring in the planning process?

Explanation

In the TSF system, the Reference Ring is defined as the ring that is mounted orthogonally to the reference bone fragment. Deformity parameters and strut calculations are all based relative to this ring's position.

Question 77

A 32-year-old female with Charcot-Marie-Tooth disease presents with severe, progressive bilateral cavovarus foot deformities. On examination, a Coleman block test is performed; the hindfoot varus does not correct when the first metatarsal is allowed to drop off the block. Which of the following procedures is absolutely required as part of her surgical reconstruction?

Explanation

A positive Coleman block test (hindfoot remains in varus) indicates a rigid, structural hindfoot deformity. While soft tissue releases and forefoot osteotomies may be adjuncts, a rigid hindfoot varus requires a bony fusion (subtalar or triple arthrodesis) for adequate correction.

Question 78

A 68-year-old male presents with recurrent knee effusions and a sensation of the knee 'giving way' when descending stairs, 18 months after a primary posterior-stabilized TKA. Ligamentous examination demonstrates excessive anterior-posterior translation in 90 degrees of flexion, but the knee is perfectly stable in full extension. Radiographs show no loosening. What technical error during the index procedure is the most likely cause of this instability?

Explanation

Flexion instability (stable in extension, unstable in flexion) in TKA is typically caused by a loose flexion gap. The most common technical error leading to this is excessive resection of the posterior femoral condyles or undersizing the femoral component in the AP plane.

Question 79

During external fixator application using the Ilizarov method, fine wires (1.8 mm) are tensioned to increase the stiffness of the frame. Which of the following wire configurations and tensioning parameters provides the highest construct rigidity and minimizes the risk of wire breakage in a tibial frame?

Explanation

To maximize frame rigidity and minimize micromotion and wire breakage in ring fixators, wires should ideally cross at or near 90 degrees (maximizing the crossing angle) and be tensioned to approximately 130 kg in the adult tibia.

Question 80

A 72-year-old female with a previous L2-to-pelvis fusion undergoes a primary total hip arthroplasty (THA). Because of her lumbopelvic stiffness, her pelvis fails to retrovert when transitioning from a standing to a sitting position. To minimize the risk of anterior impingement and subsequent posterior dislocation during sitting, how should the acetabular component positioning be adjusted?

Explanation

A stiff lumbopelvic spine fails to retrovert during sitting, meaning the acetabular cup does not functionally open (antevert) to accommodate hip flexion. This increases the risk of anterior impingement and posterior dislocation, necessitating greater component anteversion during surgery.

Orthopedic Surgery Board Review MCQs: Arthroplasty, Trauma & Spine Part 255

Orthopedic Board Review MCQs: Adult Reconstruction, Foot & Ankle, & Deformity | Part 262

Key Takeaway

Orthopedic Board Review MCQs: Adult Reconstruction, Foot & Ankle, & Deformity | Part 262

Chapter Index