165/189 Day A & 164/189 Day B Mastery Training Program

Front 1

Which of the following defines the working distance of a plate in a plate/screw fracture fixation construct?
1. The length of the interfragmentary lag screw
2. The length between the 2 screws closest to the fracture on each end of the fracture
3. The distance from the bone to the plate
4. The length from the screw closest to the fracture to the screw furthest from the fracture on the same end of the plate
5. The length between the 2 screws furthest from the fracture on each end of the plate

Back 1

The working distance is defined as the distance between the 2 screws closest to the fracture. Decreasing the working distance increases the stiffness of the plate fixation construct. An example of the working distance is provided in Illustrations A and B from Hak's review article. Changing the screw position from A to B results in a less rigid construct that is more suitable for secondary bone healing. Stoffel et al review the biomechanics of locking bridge plate constructs. The working distance is the most important determinant of axial stiffness and torsional rigidity. Decreasing the distance from the plate to the bone, using a longer plate, and increasing the number of screws used also increased stiffness. Ans2

Front 2

An adolescent patient is treated with a 6mm solid intramedullary nail. Compared to a 12mm solid nail of the same material, the 6mm nail has: 1. 1/2 the torsional rigidity2. 1/4 the torsional rigidity3. 1/16 the torsional rigidity4. 1/8 the torsional rigidity5. the same torsional rigidity

Back 2

Nail radius affects nail bending and torsional rigidity. For a solid circular nail, the torsional rigidity is proportional to the fourth power of the radius. Thus a nail with 1/2 the diameter (6mm compared to 12mm) and therefore 1/2 the radius (3mm compared to 6mm) would have(1/2)^4 = 1/16 the torsional rigidity (answer 3). Bong et al. performed a great review of the biomechanics and biology of intramedullary nailing of the lower extremity. Ans3

Front 3

Figure A is a radiograph taken after an open reduction and internal fixation of a periprosthetic distal femur fracture. With this type of hybrid locked plate fixation, what is the difference between screw A and screw B? 1. Screw A can assist in fracture reduction while screw B provides a fixed angle support2. Screw A provides improved axial stiffness while screw B provides a fixed angle support3. Screw A can be used to reduce the plate to bone while screw B can be used to lag fracture fragments together4. Screw A provides a fixed angle support while screw B can be used to reduce the plate to the bone5. Screw A can be used to lag fracture fragments together and screw B increases the plate bone frictional stability

Back 3

Locking screws provide a fixed angle support and can improve fixation in osteoporotic bone while nonlocking screws can be used to reduce the plate to the bone, lag fracture fragments together and increase the plate bone frictional stability. "Hybrid" locked plate fixation utilizes both screw types in order to assist with difficult fracture fixation such as when there is a short metaphyseal segment and osteoporotic bone. Ans4

Front 4

Locking plate technology has relative indications for use in all of the following, EXCEPT: 1. As a bridge for severely comminuted fractures2. Osteoporotic metaphyseal fractures3. Short fracture segments4. Oligotrophic diaphyseal nonunions5. Indirect fracture reduction techniques

Back 4

Locked plating technology can be thought of as a stiff construct used as an internal fixator, similar to the fixed angle design of an external fixator (with more of a biomechanical advantage). Locking plates utilize the fixed angle to ensure stability of the construct, whereas conventional plates utilize the plate/bone friction, as well as fracture end contact to ensure stability. A combination of both screw types offers the possibility to achieve a synergy of both internal fixation methods.According to Egol et al's excellent review of locked vs. nonlocked plates, locked plating technology may increasingly be indicated for indirect fracture reduction, diaphyseal/metaphyseal fractures in osteoporotic bone, bridging severely comminuted fractures, and the plating of fractures where anatomical constraints prevent plating on the tension side of the bone. Oligotrophic non unions: these are not hypertrophic, and callus is absent; occur after major displacement of frx, distraction ofAns4

Front 5

The resistance to pullout of a screw in osteoporotic bone is increased by all of the following EXCEPT? 1. Placement parallel to the trabecular pattern2. Purchase in cortical bone3. Use of a fixed angle (locking screw construct)4. Tapping prior to screw placement5. Augmentation with polymethylmethacrylate

Back 5

the quality of the bone is the primary determinant of the holding power of an individual screw. Other factors that increase the pullout strength include fixation in cortical bone (cortical bone has greater mineral density and, therefore, greater resistance to screw pullout than trabecular bone), screws placed parallel to the trabecular pattern, and screw fixation augmented with PMMA. The addition of a locking plate will also increase the resistance to failure by creating a fixed angle construct. Tapping prior to placement of the screw has not been shown to increase resistance to pullout, on the contrary studies have shown this decreases resistance to pullout. Turner et al examined the holding strength of small and large diameter screws in healthy bovine and diseased human bone. They found the screw diameter, trabecular orientation of the bone, and mineral content of the bone all affect the holding strength. A larger diameter screw, parallel placement to the trabecular pattern, Ans

Front 6

Which statement is true regarding standard open plating techniques compared to minimally invasive submuscular plating techniques? 1. standard plating results in greater compromise to both medullary and periosteal bloodflow2. standard plating results in greater compromise to periosteal bloodflow only3. standard plating results in greater compromise to medullary bloodflow only4. standard plating results in less compromise to both medullary and periosteal bloodflow5. there is no difference between the two techniques with respect to periosteal and medullary bloodflow

Back 6

Using silicone arterial dye injection in a cadaveric femur model, Farouk et al. studied the vascular disruption of conventional plate osteosynthesis (CPO) with minimally invasive plate osteosynthesis (MIPO). All MIPO specimens showed intact perforating and nutrient arteries, whereas the CPO specimens had a variable incidence of vessel disruption. The MIPO group demonstrated better periosteal perfusion in each of the cadavers and improved medullary perfusion in 70 percent of the MIPO specimens compared with the CPO specimens. Based on this evidence, they concluded that MIPO may be more advantageous biologically than the traditional method. Ans1

Front 7

A young boy is involved in a motor vehicle accident and presents with neck pain. A CT scan is performed and is negative for fractures. Based on the presence of the ossification center shown in Figure A, what is the most likely age bracket of this patient. 1. < 1 years of age2. 1-3 years of age3. 3-6 years of age4. 8-10 years of age5. > 12 years of age

Back 7

The CT scan shows a fused basilar synchondrosis with a C2 secondary ossification center that is not yet fused. Therefore the patient is most likely 8-10 years of age.The axis (C2) develops from five ossification centers. These include the body, two neural arches, the odontoid, and a secondary ossification center. The subdental (basilar) synchondrosis is an initial cartilagenous junction between the dens and vertebral body that does not fuse until ~6 years of age. The secondary ossification center appears around age 3 and fuses with the odontoid at around 12 years of age.Ans4

Front 8

which of the following fracture patterns is at greatest risk for nonunion with nonoperative treatment? Answer 1: Type 2 Odontoid fracture with slight posterior angulation Answer2: Type 2 Odontoid fracture with posterior displacement and angulation.Answer 3: Type 3 Odontoid fracture with slight anterior displacementAnswer 4: Type 3 Odontoid fracture with distraction but no angulation or anterior/posterior displacementAnswer 5: Type 2 Odontoid fracture with anterior displacement

Back 8

Type 2 Odontoid fracture with posterior displacement and angulation. This fracture pattern is at increased risk of nonunion compared with the other fracture patterns shown.Type 2 odontoid fractures are fractures which occur through the waist of the odontoid process. These fractures are at risk for nonunion due to the watershed blood supply at this location. Increased fracture displacement, posterior displacement, and increased angulation are all risk factors for nonunion. Type 1 are tip fractures generally managed with cervical orthosis. Type 2 are waist fractures that can be managed with halo or operative intervention. Type 3 are fractures which extend into the C2 body and can be managed with halo, cervical orthosis, or surgery. nonunion did correlate with a fracture gap (> 1 mm), posterior displacement (> 5 mm), delayed start of treatment (> 4 days) and posterior redisplacement (> 2 mm). Ans2

Front 9

In patients who are neurologically intact, all of the following cervical spine injuries can be appropriately managed with external immobilization in a rigid cervical orthosis EXCEPT 1. C1 posterior arch fractures2. Type 1 odontoid fractures 3. Type 3 odontoid fractures 4. Type 1 Hangman's fractures of C2 5. burst fracture of C1

Back 9

A burst fracture of C1, also known as a Jefferson fracture, with associated transverse ligament disruption is shown in Figure E. Jefferson fractures can be appropriately managed with a cervical orthosis or halo device if the transverse ligament is intact. If there is combined lateral mass displacement >7 mm (8.1 mm with standard x-ray magnification), this indicates an injury to the transverse ligament, and the fracture pattern is unstable. This unstable fracture should be managed with traction followed by a transition to a halo device or C1-C2 fusion. Ans5

Front 10

A 37-year-old male was involved in a motorcycle accident. He is neurologically intact. A coronal and sagittal CT scan is shown in Figure A. What is the most appropriate management? 1. Posterior C1-C2 fusion2. Anterior odontoid screw fixation3. Transoral anterior odontoid resection4. Cervical immobilization for 6-8 week in an external orthosis5. Treatment in a soft cervical orthosis for two weeks followed by range of motion exercises

Back 10

The clinical presentation is consistent with at Type III odontoid fracture. Cervical immobilization in a hard external orthosis is the most appropriate treatment. odontoid fractures into 3 types. Type I is an oblique avulsion fracture of the apical ligament. Type II occurs in the watershed area at the junction with the body of the axis. Type III fractures extend into the cancellous body of C2 and involves a variable portion of the C1-C2 joint. While the management of Type II fractures remains controversial due to high non-union rates, the literature supports that Type III fracture can be treated with immobilization in a hard cervical collar or halo vest. This is due to improved healing potential from a larger surface area of cancellous bone and a better blood supply than Type II fractures.Answers:Answer 1: Posterior C1-C2 fusion is the most commonly performed operation for treatment of Type II odontoid fractures.Answer 2: Anterior odontoid screw fixation Ans4

Front 11

A 34-year-old man sustained a gunshot wound to the knee 18 months ago and was treated with bullet removal and a 10 day course of oral antibiotics. He now complains of 12 months duration of pain in the thigh and recent ulceration and drainage of the skin near the site of his gunshot wound. Physical exam is notable for a draining sinus tract, erythema and tenderness of the mid-thigh. He is afebrile. An MRI image of this patient is shown in Figure A. Which of the following is the most appropriate management? 1. Two week course of oral cephalosporin2. Core needle bone culture followed by intravenous antibiotics3. Surgical debridement, culture, and intravenous antibiotics4. Core needle biopsy, chest CT scan, and bone scan5. Neoadjuvant chemotherapy and wide resection followed by adjuvant chemotherapy

Back 11

chronic osteomyelitis. The MRI shows chronic changes of the distal femur with intraarticular (knee) extension. Chronic osteomyelitis is notable for a sequestrum, which is necrotic bone that has become avascular and no longer connected to the normal bone via the Haversian canal system. Involucrum refers to the new bone forming around the sequestrum. Often the involucrum will form a sinus tract allowing the sequestrum to drain into the soft tissues. Illustration A is a diagram of chronic osteomyelitis depicting the sequestrum (E), Involucrum (C), and sinus tract (D). In contrast to acute osteomyelitis, chronic osteomyelitis is often not eradicated with intravenous antibiotics alone. All necrotic bone (including the sequestrum) must be resected as it serves as a nidus for infection. Antibiotics should be guided off culture sampling of the infection.ans3

Front 12

A 45-year-old homeless hemophiliac male presents with chronic tibial osteomyelitis. Which of the following factors has been shown to predict a better prognosis? 1. Polymicrobial infection2. Use of external fixation3. Infection with Methicillin-resistant Staphylococcus aureus4. Metaphyseal infection5. Contralateral lower extremity amputation

Back 12

Success in the treatment of chronic tibial osteomyelitis is dependant on various factors including patient factors (immunocompetency of patient, nutritional status), injury factors (severity of injury as demonstrated by segmental bone loss), and infection factors (the extent and location of infection – metaphyseal infections heal better than mid-diaphyseal infections). The second referenced article by Cierny reviews the significant increase in success over the last 20 years in treating infected tibial nonunions, due to pharmacological and technological advances. He reports an increase in limb salvage from 78% to 93% with modern protocols.Incorrect Answers:Answer 1: Polymicrobial infection portends a worse prognosis than a single organism.Answer 2: External fixation has not been shown to improve outcomes in chronic osteomyelitis.Answer 3: MRSA infections are a risk factor for poor outcomes.Answer 5: Contralateral extremity amputation increases the risk of poor outcomes. Ans4

Front 13

A 21-year-old male reports right ankle pain after sustaining an inversion ankle injury 2 years ago. He complains of mechanical symptoms with ankle movement that continue to be symptomatic with everyday activities. During his workup, an MRI shows a 1x1 cm lateral talar osteochondral defect (OCD). When compared to medial talar OCDs, which of the following statements is true regarding lateral talar OCDs? 1. Increased incidence of traumatic etiology2. Lesions are usually deeper3. Better chance of spontaneous resolution4. Usually more posterior5. Are more common

Back 13

Lateral talar OCDs have an increased history of a traumatic etiology in comparision to medial talar OCDs. Lateral talar OCDs are also usually less common, smaller and more shallow than medial talar OCDS. Lateral talar OCDs are usually anterior in comparison to medial based OCDs, and are harder to treat with conservative treatment due to a lower incidence of spontaneous healing. Incorrect answers:Answer 2- Lateral talar OCDs are usually more shallow in depth than medial talar OCDs.Answer 3- Lateral talar OCDs are harder to treat with conservative treatment due to a lower incidence of spontaneous healing.Answer 4- Medial talar OCDs are usually more posteriorly located than lateral talar OCDs. Answer 5- Medial talar OCDs are more common than lateral talar OCDs.Ans1

Front 14

A 30-year-old professional ballet dancer presents with persistant ankle pain after an ankle sprain 6 months ago. Physical therapy and NSAID's have not alleviated the symptoms. Physical exam reveals some joint swelling but no ligamentous instability. Radiographs are unremarkable. What is the next appropriate step in the management of this patient? 1. Continue physical therapy2. Avoidance of dancing with CAM walker boot for 2 weeks3. MRI of the ankle4. Ankle steroid injection5. Diagnostic ankle arthroscopy

Back 14

The vast majority of ankle sprains heal well with time, rest, therapy, and temporary immobilization. In those approximate 10% that do not improve, an osteochondral lesion of the talus and persistent instability must be considered. The question stem states that there is no ligamentous instability so the next step should be an MRI to evaluate for an osteochondral lesion of the talus (OLT). Surgery is indicated for OLTs if conservative therapy fails after 6 months. Tol et al performed a systematic review of 32 articles and showed that excision, curettage, and drilling had the highest success rate (85%), followed by excision and curettage (78%). Nonoperative (45%) and excision only (38%) were less successful and not recommended. Ans3

Front 15

woman in 3rd trimester of pregnancy, insidious onset of pain, pain with stairs, inclines, and impact
pain common in anterior hip. PE=local tenderness
reduced ROM in hip.
1-KIF(key image finding) -->Dx
1.1 other sx & PE
1.2 other images->dx
1.3 other labs->dx
2-indications Tx
2.1 first line of treatment
3-(DDx) 4

Back 15

1-xray=fem head and neck lag behind clinical signs by 4-8wks, subchondral cortical loss diffuse osteopenia of femoral head and neck, joint effusion, joint space is always preserveddx-Idiopathic Transient Osteoporosis of the Hip (ITOH)1.1-Acute pain, improves with PWB, PE=Preserved except at extremes of ROM1.2MRI-imaging modality of choice, shows marrow edema of femoral head and neckT1=decreased signal, loss of fatty marrow T2=high signal of marrow edema joint effusionBone scan=increased uptake in femoral head preceeds Xray changes1.3-Elevated ESR2.1-protected weightbearing to avoid stress fx,resolves spontaneously in 6-8mths3-femoral neck stress fx, infection, malignancyAVN

Front 16

mn for etiology of AVN

Back 16

(AVN): MCC-STARS & PLASTIC RAGS & ASEPTIC
S - steriods
T - trauma (i.e. femoral neck fracture, hip dislocation, scaphoid fracture, etc.)
A - alcohol abuse
R - radiation osteonecrosis
S - sickle cell disease
PLASTIC RAGS
P - pancreatitis
L - lupus
A - alcohol
S - steroids
T - trauma
I - idiopathic, infection
C - caisson disease, collagen vascular disease
R - radiation, rheumatoid arthritis
A - amyloid
G - Gaucher disease
S - sickle cell disease
ASEPTIC
A - alcohol
S - sickle cell disease/ SLE
E - exogenous steroid
P - pancreatitis
T - trauma
I - infection
C- caisson disease

Front 17

A 45-year-old with a history of sickle cell anemia reports hip pain for the past 6 months. A radiograph of the affected hip is shown in Figure A. Which of the following interventions has been shown to have the best outcomes in this patient population?
1. Observation
2. Bisphosphonates
3. Hemi-arthroplasty
4. Uncemented metal on polyethylene total hip arthroplasty
5. Cemented metal on polyethylene total hip arthroplasty

Back 17

uncemented metal on polyethylene THA. AVN of the hip may be idiopathic in nature or assoc w/ alcoholism, steroid use, SCA. The Ficat staging system is used to classify AVN of the hip. Changes in treatment are driven by development of sx as well as the develop of subchondral bone collapse (Ficat Stage 3). In those with with femoral head flattening (Ficat Stage 4) and acetabular degenerative changes (Ficat Stage 5), THR has good to excellent outcomes.
Incorrect
1: Conservative measures in this patient would not improve this patient’s outcome give the degree of the femoral head collapse and presence of acetabular degeneration.
2: Bisphosphonates can be used in patients with avascular necrosis of the hip prior to collapse. Current data is conflicting as to whether they prevent collapse or not.
3: Outcomes for pts undergoing hemiarthroplasty for AVN of the hip in the young patient are poor; and as a result, this has been largely abandoned.
Answer 5: Higher failure, cemetedAns4

Front 18

A 47-year-old man presents with 1 week of left leg pain. 6 months prior he underwent a vascularized free-fibula bone graft from his left leg to his right hip for avascular necrosis. The pain is located at the level of his donor site and is worse with weight-bearing and relieved by rest. Physical exam shows focal tenderness over his tibia. A lateral radiograph from the day of presentation is shown in Figure A. WBC, ESR, and CRP are all within normal limits. What is the next best step in management to confirm the diagnosis?1. Compartment pressure measurements2. CT scan3. MRI scan4. Ultrasound to rule out deep abscess5. Bone biopsy

Back 18

The clinical presentation is suspicious for a stress fracture of the tibia following free-fibula bone grafting. If plain radiographs are negative, more sensitive imaging such as a MRI or bone scan should be performed.Ans3

Front 19

Which of the following is the most common cause of early revision surgery (<20 weeks) following a hip resurfacing arthroplasty? 1. Periprosthetic fracture2. Rupture of abductors3. Dislocation4. Heterotopic ossification5. Post-operative stiffness

Back 19

Periprosthetic fracture, specifically femoral neck fracture, is the most common cause of early revision less than 20 weeks following surgery. Anss

Front 20

When discussing metal on metal hip resurfacing versus metal on polyethylene total hip replacement, the surgeon should inform the patient that all of the following are disadvantages of hip resurfacing EXCEPT? 1. Higher dislocation rate2. Higher periprosthetic fracture rate3. Increased serum metal ion levels4. Higher rates of osteonecrosis5. Larger incision and surgical dissection

Back 20

Hip resurfacing is associated with higher rates (compared to conventional THA) of AVN, higher serum levels of metal ions, and higher rates of early postoperative fractures, specifically femoral neck fractures. However, the dislocation rate is significantly lower with hip resurfacing due to the larger size of the femoral component and more accurate restoration of anatomic hip biomechanics. Shimmin et al report on hip resurfacing complications, and published dislocation rates are 0.75% at a mean of 3 years’ follow-up. Also, in order to prepare the acetabulum while preserving the femoral head, a more extensive surgical approach and soft tissues releases are required for a resurfacing procedure. Ans1

Front 21

The zona orbicularis is the arthroscopic landmark for access to which of the following structures? 1. Iliopsoas2. Pectineus3. Sartorius4. Adductor brevis5. Rectus femoris

Back 21

The zona orbicularis is the arthroscopic landmark for access to the iliopsoas. Arthroscopic release of the iliopsoas can be performed for treatment of an internal snapping hip, which is usually caused by the iliopsoas snapping over the iliopectineal eminence or the femoral head. Ans1

Front 22

During hip arthroscopy, the sciatic nerve is most at risk with which of the following portal techniques? 1. Anterior peritrochanteric portal with limb in internal rotation2. Anterior peritrochanteric portal with limb in flexion3. Posterior peritrochanteric portal with limb in internal rotation4. Posterior peritrochanteric portal with limb in external rotation5. Distal lateral portal with limb in neutral rotation

Back 22

The posterolateral portal is made 2-3cm posterior to the tip of the greater trochanter. The hip should never be externally rotated during this portal entry as this brings the sciatic nerve closer to the portal. Internal rotation would move the portal farther away from the sciatic nerve- this concept is similar to internally rotating during a posterior approach to the hip for a total hip arthroplasty.
Ans4

Front 23

A 3-year-old boy was referred to you for evaluation of a bowing deformity of his leg and a persistent limp. Radiograph is shown. What is the most likely diagnosis? 1. Fibrous dysplasia2. Unicameral bone cyst3. Aneurysmal bone cyst4. Osteofibrous dysplasia5. Non-ossifying fibroma

Back 23

The figure shows a lucent lesion of the proximal tibial diaphysis, which is expanding the anterior cortex, leading to procurvatum deformity. This lesion is characteristic of osteofibrous dysplasia. Osteofibrous dysplasia is a rare, benign, fibrous tumor that usually presents in children <10 years, with peak incidence at 1-5 years. ans4

Front 24

A 9-year-old male presents with a mass on his lower leg. He denies any history of trauma, and is otherwise healthy. A current radiograph of the affected leg is shown in Figure A. A biopsy of the lesion is obtained, and is shown in Figures B and C. What is the most likely diagnosis in this patient? 1. Osteofibrous dysplasia2. Nonossifying fibroma3. Osteoblastoma4. Chondroblastoma5. Ewing's sarcoma

Back 24

This patient's presentation, histology, and radiograph are consistent with a diagnosis of osteofibrous dysplasia(OFD). These lesions are most commonly found in the tibia of children within the first decade of life. Radiographs typically show a lytic lesion in the anterior cortex of the diaphysis or metaphysis of the tibia which often causes anterior-posterior bowing. The tumor has a multi-loculated appearance and causes distortion of the thin cortex. Histologically, OFD consists of irregular spicules of trabecular bone lined by osteoblasts. These osteoblasts produce a rim of lamellar bone around centers of woven bone.Most et al discuss the differences between OFD and adamantinoma(AD), work-up, and treatment of these fibro-osseous lesions in their JAAOS review article. Ans1

Front 25

A 9-year-old male is brought in for initial evaluation of persistent painless limping favoring the left leg. His symptoms began 6 months ago, and have been progressively worsening. He has nearly full abduction. Radiographs and an MRI are shown in Figures A, B, and C. What is the next most appropriate step in treatment? 1. Left hip aspiration and culture under fluoroscopic guidance2. Continued activity limitation and bracing3. Femoral or pelvic osteotomy4. Core decompression of the femoral head5. Work-up for underlying metabolic bone disease

Back 25

late stage Legg-Calve-Perthes (LCP)disease. The radiographs and MRI scan demonstrate density changes and collapse of the femoral head consistent with lateral pillar group B. Herring et al evaluated the effect of LCP treatment on outcome. They found that patients >8 y.o. at the time of onset, with a hip in the lateral pillar B group or B/C border group had a better outcome with surgical treatment including either a femoral or pelvic osteotomy. Group-B hips in children <8 y.o. at the time of onset had favorable outcomes unrelated to treatment, whereas group-C hips in children of all ages frequently have poor outcomes regardless of treatment. Ans3

Front 26

For children with Legg-Calve-Perthes(LCP) disease, all of the following factors are associated with femoral head incongruity and worse clinical outcome EXCEPT: 1. Maintenance of less than 50% of lateral pillar height2. Presentation at 5 years of age3. Lateral subluxation of the femoral head4. Calcification lateral to the epiphysis5. Presence of a radiolucency in the shape of a V in the lateral portion of the epiphysis (Gage sign)

Back 26

LCP is a disease of children in which the vascular supply to the femoral head is compromised leading to avascular necrosis of the femoral head and can subsequently result in resorption, collapse and repair. Children who present at an age < 6 years have an improved prognosis. Catterall described five "at-risk" signs, which indicate a more severe disease course including: 1) Gage sign as shown in Illustration A (radiolucency in the shape of a V in the lateral portion of the epiphysis), 2) calcification lateral to the epiphysis, 3) lateral subluxation of the femoral head 4) a horizontal physis and 5) metaphyseal cysts.Ans2

Front 27

Figure A represents a free body diagram of the hip of a patient standing on the right leg. The forces and distances are labeled on the diagram and the resulting hip joint force (J) = 1800N. What is the resultant value for J when the acetabular component is medialized given the new distances shown in Figure B? 1. 1000N2. 1200N3. 1800N4. 2200N5. 3600N

Back 27

The new joint force (J) calculated is 1200N as shown in Illustration A. The joint force decreases as the acetabular component is moved medial. This is a result of decreasing abductor tension as the acetabular component is medialized (Distance B is 50mm instead of the initial 100mm). Mechanical equilibrium is when the sums of all forces and moments equal zero [(AT x A) - (5/6BW)x B)) = 0]. Free body diagrams show the locations and directions of all forces and moments acting on a body. The body and the left leg weigh 5/6 x total body weight (BW) in a right-sided single leg stance as given in this example. Ans2

Front 28

A cane held in the contralateral hand reduces joint reactive forces through the affected hip approximately 50% by which of the following mechanisms? 1. Reducing hip abductor muscle pull2. Increasing hip flexor muscle pull3. Moving the center of rotation for the femoroacetabular joint4. Increasing joint congruence at the femoroacetabular joint5. Moving the center of gravity posterior to the second sacral vertebra

Back 28

A cane held in the contralateral hand reduces joint reactive forces through the affected hip up to 50% by reducing abductor muscle pull.A cane create an additional force that keeps the pelvis level in the face of gravity's tendency to adduct the hip during unilateral stance. The cane's force must substitute for the hip abductors of the affected hip and creates a moment arm that is relatively long and originates on the side opposite the hip whose abductor muscles are weak. Additionally, the person needs adequate strength in the muscles of the wrist, elbow, shoulder girdle, and trunk.Ans1

Front 29

how do structural characteristics differ from strength characteristics

Back 29

structural characteristics not on only depending on the material but also on the structural configuration of the object whether to cylinder rectangle as an example

Front 30

1. structural properties can be demonstrated on the stress versus strain curve which is the x-axis and which is the Y axis
2. what is the example seen on the x-axis

 

Back 30

1. x-axis is a strain which is a relative measure of the deformation of an object, 

Y-axis is the stress, intensity of an internal force/area

1. elastic zone- the material will return to its original shape for given amount of stress. I last think rubber band
2.  plastics zone- zone where the material will NOTreturn to its original shape for given amount of stress. plastic equals permanent deformation

 

 

Front 31

1. what kind of screw Is this
2. how to tell what kind of screw this is
3. Describe the design of the screw and terms of pullout strength

Back 31

1. cancellus screw
2. sharp tip and large outer diameter and this is sharp
3. Maximal pullout strength because the large inner outer diameter difference and fine picked

Front 32

1. what kind of screw as this
2. How how to tell
3. What is its application

Back 32

1. a locking screw
2. 4 different diameters with 2 different anterior diameters that allow the screw to lock into the plate
3. .  For osteoporotic bone  where there is a diaphyseal/metaphyseal fracture because it's less angulation and the comminuted metaphyseal fracture

Front 33

1. what kind of screw is this
2. How to tell
3. What is the clinical application of the screw

Back 33

1. cortical screw
2.  dull-tipped and  minimal pullout strength because the inner and outer diameters good working screw distance
3. used in compression plating with the screw placed essentially in the oval hole to generate compression at the fracture site

Front 34

1. in talking by the screw what is the pitch
2. What is the lead
3. What is the screw working distance 

Back 34

1. the pitch is the distance between threads 
2. The lead is a distance advanced with 1 revolution
3. The screw working distance equals length and the bone traversed by the screw

Front 35

1. what kind of property does a plate have as relates to  being a device
2. When placing a plate and in the body wears it most affected
3. defined plate working distance

Back 35

1. a plate is considered a loadbearing device
2. A plate and most effective on the tension side of her fracture
3. Working distance = length from the fracture to the closest screw on either side of the fracture

Front 36

1. in a plate how does one increased stiffness of the fixation construct

Back 36

1. by decreasing the working distance that is the closer the screw is to the fracture site the more stiff it is

Front 37

bending rigidity of the plate is proportional to what

Back 37

bending rigidity = thickness to the 3rd  power

Front 38

1. absolute stability allows what kind of healing to take place
2. wound we create absolute stability

Back 38

1. primary Haversion canal healing there is no micro motion = local strain at the fracture site + fixation stiffness
2. compression plating technique

Front 39

1. relative stability allows what kind healing to take place
2. what muscular strain rate be an order for relative stability to dominate

Back 39

1. enchondral healing
2. strain rate  <15% = and enchondral healing or >15% =fibrous union will predominate

Front 40

when R concave plates useful when treating a fracture

Back 40

when treating a transverse fracture to ensure compression forces occur on both on the far and near cortices of the fracture

Front 41

what of the indications to use locking plate technology 

Back 41

1. indirect fracture reduction
2. Diaphyseal metaphyseal fractures and osteoporotic bone
3. Severely comminuted fractures that need bridging
4. Plating fractures were anatomic constraints prevent locking on the tension side of the bone that is a short segment fixation

Front 42

when choosing between unicortical or bicortical screws for locking plate which one is better

Back 42

bi cortical locking screws have significantly more resistance to all applied forces with resistance to torsion increased the most

 

Front 43

advantages and disadvantages or percutaneous locking plates

Back 43

advantage – less soft tissue stripping but disadvantage –  a chance of malunion

Front 44

what of the indications for  a hybrid locking plate be used

Back 44

nonlocking screws assistant fracture reduction and locking screws provide fixed angle construct

Front 45

4 ways to increase locking plate construct stability

Back 45

1. bicortical locking screws
2. Increased number of screws
3. Screw divergence from hole less than 5°
4. Longer plate

Front 46

what kind of device is intramedullary nail

Back 46

IM nail equal load sharing device

Front 47

1. what is a torsional rigidity of an IM nail
2. what is at depend on
3. what factors increase and decrease the torsional rigidity

Back 47

1. torsional rigidity = radius to the 4th power 
2. it depends on shear modulation and polar moment inertia
3. increased by reaming and decrease by slotting of a nail

Front 48

1. what is the bending rigidity of an IM nail
2. what does it depend on

Back 48

1. bending rigidity = radius of the 4th power
2. The material properties that is young modular of elasticity of the material

Front 49

what designed property of an IM nail puts it at risk for perforating the femur

Back 49

IM nail radius of curvature is greater that is straighter than the radius curvature of the femur

Front 50

Re: Interlocking of the nail what is the purpose of

1. Dynamic locking
2. Static locking
3. secondary dynamization

Back 50

1. axially and rotationally stable fractures
2. Axially and rotationally unstable fractures
3. Dynamization for nonunion removing the proximal interlocking screw or move the proximal interlocking screw from the static to the dynamic slot

Front 51

what is the most important factor significant increased stability and EX fix

Back 51

larger diameter pins

Front 52

what technique can be implemented to slightly decrease the moment arm when inserting at the femoral component

Back 52

slight valgus to decrease the moment arm and decrease the stress on the cement

Front 53

common methodor technique to increase strength and stability of an ex-fix construct

Back 53

1. decrease the distance between the bone and the construct
2. Good bone to bone fracture and opposition
3. increasing number pain
4. Using larger pins
5. Small distance from the near pins to fracture site smaller working distance
6. Increased space between the near and far pins
7. by cortical pin fixation

 

Front 54

Which of the following techniques increases strength and stability to an external fixation construct? 

1.  Unicortical pin fixation

2.  Decreasing total pin separation distance

3.  Increased working distance from the pin to fracture site

4.  Decreasing the distance between the bone and the construct

5.  Using smaller diameter pins

Back 54

There are several methods that can be used to increase the strength of an external fixation construct. Decreasing the distance from the bar to the bone increases stability and strengthens the construct. Some other methods to increase stability include: good bone-to-bone fracture end apposition, using an increased number of pins, using larger pins, small distance from the near pins to the fracture site (smaller working distance), increased spacing between the near and far pins, and bicortical pin fixation.ans4

Front 55

A 27-year-old male undergoes intramedullary nailing of a midshaft tibia fracture with static locking proximally and distally. There is minimal healing noted 3 months postoperatively and the decision is made to dynamize the nail. For intramedullary nail dynamization, an interlocking screw should be placed in which of the holes shown in Figure A?

1.  A only

2.  C only

3.  B only

4.  A and C

5.  C and B

 

Back 55

The portion of the long slot hole labeled A is the dynamic interlocking site because it allows the proximal tibia to collapse with weight bearing. Placement of an interlocking screw in holes B or C would lead to static locking of the nail. an1
 

Front 56

(OBQ10.33) A surgeon chooses a periarticular locking plate with unicortical proximal locking screws for an extra-articular distal femur fracture as seen in Figure A. Compared to a fixed-angle blade plate construct with bicortical unlocked proximal screw fixation, the periarticular locking plate with unicortical locking screws has which biomechanical properties?

1.  Greater torsional and axial fixation strength

2.  Less torsional but greater axial fixation strength

3.  Equal torsional and axial fixation strength

4.  Greater torsional but less axial fixation strength

5.  Less torsional and axial fixation strength

Back 56

Unicortical locking plates have characteristically less torsional strength than bicortical locking plates and bicortical non-locking plates. Axial strength is improved with locking plate fixation. ans2

Front 57

A 24-year-old female presents with a transverse midshaft humerus fracture. Which of the following implants would create the most compression on both the far and near cortices?

1.  Compression plate with concave bend (ends bowed towards bone)

2.  Large fragment locking plate with 3 bicortical locking screws proximal and distal to the fracture

3.  Intramedullary nail

4.  Compression plate with convex bend (ends bowed away from the bone)

5.  Sarmiento style fracture brace

Back 57

Placing a concave bend in the plate during compressive plating results in compressive forces at both the near and far cortices (Illustration A). As described in the AO manual of fracture fixation, this technical pearl helps to ensure that osteosynthetic forces occur on both sides of the fracture. This technique is most useful in transverse fractures and can be used in any transverse fracture, not just humeral shaft fracture.ans1

Front 58

Which of the following is true regarding rigid locking plate constructs in fracture fixation?

1.  Locking plates always enhance fracture healing more than conventional plating

2.  Locking plates reduce interfragmentary strain more than conventional plating

3.  Locking plates are best utilized in diaphyseal fractures

4.  Locking plates are contraindicated in patients with osteoporosis

5.  Fractures treated with anatomic reduction and locked plate fixation demonstrate more strain than fractures treated with intramedullary fixation

 

Back 58

Locking plate technology functions through the threaded locking of the screw heads into the plate to create a fixed angle construct. Illustrations A and B show the locking threads of a locking screw and locking plate. This results in less screw toggle and resistance to screws backing out. Locked plates provide stiffer constructs than conventional plates and intramedullary nails and thus reduce interfragmentary strain. 
ans2

Front 59

Which of the following defines the working distance of a plate in a plate/screw fracture fixation construct?

1.  The length of the interfragmentary lag screw

2.  The length between the 2 screws closest to the fracture on each end of the fracture

3.  The distance from the bone to the plate

4.  The length from the screw closest to the fracture to the screw furthest from the fracture on the same end of the plate

5.  The length between the 2 screws furthest from the fracture on each end of the plate

Back 59

working distance is defined as the distance between the 2 screws closest to the fracture. Decreasing the working distance increases the stiffness of the plate fixation construct. An example of the working distance is provided in Illustrations A and B from Hak's review article. Changing the screw position from A to B results in a less rigid construct that is more suitable for secondary bone healing. ans2
 

Front 60

An adolescent patient is treated with a 6mm solid intramedullary nail. Compared to a 12mm solid nail of the same material, the 6mm nail has:

1.  1/2 the torsional rigidity

2.  1/4 the torsional rigidity

3.  1/16 the torsional rigidity

4.  1/8 the torsional rigidity

5.  the same torsional rigidity

Back 60

Nail radius affects nail bending and torsional rigidity. For a solid circular nail, the torsional rigidity is proportional to the fourth power of the radius. Thus a nail with 1/2 the diameter (6mm compared to 12mm) and therefore 1/2 the radius (3mm compared to 6mm) would have(1/2)^4 = 1/16 the torsional rigidity (answer 3). Bong et al. performed a great review of the biomechanics and biology of intramedullary nailing of the lower extremity. ans3

Front 61

A 25-year-old male sustained the fracture seen in Figure A and undergoes open reduction internal fixation of the injury. What type of plating technique is used for the ulna?

1.  Neutralization

2.  Locking

3.  Compression

4.  Bridging

5.  Antiglide

Back 61

This is bridge plating as the fracture site is bridged by the plate and fixation is achieved proximal and distal to the zone of the fracture and thus provides relative stability, relative length and alignment. Bridge plating preserves the blood supply to the fracture fragments as the fracture site is undisturbed during the operative procedure. This theoretically makes less dead bone fragments and lets the whole thing heal by secondary bone healing. ans4

Front 62

The resistance to pullout of a screw in osteoporotic bone is increased by all of the following EXCEPT?

1.  Placement parallel to the trabecular pattern

2.  Purchase in cortical bone

3.  Use of a fixed angle (locking screw construct)

4.  Tapping prior to screw placement

5.  Augmentation with polymethylmethacrylate

Back 62

Of the options listed, tapping prior to screw placement is the only variable that does not increase the pullout strength of a screw in osteoporotic bone.ans4

Front 63

A long oblique diaphyseal fracture is internally fixed with 2 lag screws. There is 2 mm of residual fracture fragment gap following screw fixation. This construct has which of the following compared to a comminuted diaphyseal fracture internally fixed with a long bridge plating technique?

1.  Greater interfragmental strain

2.  Greater ductility

3.  Greater primary Haversian remodeling

4.  Greater union rate

5.  Greater callus volume formation

Back 63

A long oblique diaphyseal fracture with 2 mm of residual displacement after being internally fixed with lag screws has greater interfragmental strain than comminuted fractures treated with bridge plating or fractures that are anatomically reduced and internally fixed.ans1
 

Front 64

Which statement is true regarding standard open plating techniques compared to minimally invasive submuscular plating techniques?

1.  standard plating results in greater compromise to both medullary and periosteal bloodflow

2.  standard plating results in greater compromise to periosteal bloodflow only

3.  standard plating results in greater compromise to medullary bloodflow only

4.  standard plating results in less compromise to both medullary and periosteal bloodflow

5.  there is no difference between the two techniques with respect to periosteal and medullary bloodflow

Back 64

Using silicone arterial dye injection in a cadaveric femur model, Farouk et al. studied the vascular disruption of conventional plate osteosynthesis (CPO) with minimally invasive plate osteosynthesis (MIPO). All MIPO specimens showed intact perforating and nutrient arteries, whereas the CPO specimens had a variable incidence of vessel disruption. The MIPO group demonstrated better periosteal perfusion in each of the cadavers and improved medullary perfusion in 70 percent of the MIPO specimens compared with the CPO specimens. Based on this evidence, they concluded that MIPO may be more advantageous biologically than the traditional method. 
an1

Front 65

was the most common benign bone tumor

Back 65

osteochondroma

Front 66

most common location for an osteoch ondroma

Back 66

on the surface of the bone especially the sites of tendon insertions , and locations include knee, in the proximal femur, proximal humerus ,subungal exostosis occurs most often at the hallux

Front 67

this was the most common location for osteochondroma in the foot

Back 67

subungal exostosis in the hallux

Front 68

1. what are the genetic osteochondroma
2. What gene is mutate with osteochondroma

Back 68

1. osteochondroma is on autosomal dominant
2. JEAN mutation EXT JEANE which causes loss of regulation of the Indian hedgehog protein6 which affects pre-hypertrophic chondrocytes of the growth plate

Front 69

the patient presents osteochondroma of the pelvis and now suddenly starts complaining of pain what is the diagnosis

Back 69

secondary chondrosarcoma occurs in an older patients

Front 70

patient presents to the office with a painless mass but is having mechanical symptoms secondary to the mass, it is the most common benign bone tumor

1. What is the diagnosis, what you see at histology
2. What is the treatment
3. Other other conditions associated with this diagnosis in older patients, What is the treatment

Back 70

1. osteochondroma, there may be a cartilaginous cap over the lesion 2-3 mm thick, normal primary trabeculated well defined perichondrium
2. observe and asymptomatic patient's however this patient complained of mechanical symptoms discussed the treatment is marginal excision at the base of the stalk including the cartilaginous Try to delay until skeletally mature
3. multiple hereditary exostosis MHE – chondrosarcoma treatment  excision

Front 71

what are the genetics for multiple hereditary exostosis 

Back 71

autosomal dominant mutations in the gene EXT 1 EXT 2 &  EXT3

Front 72

A 19-year-old male has a heritable condition represented by the radiograph in Figure A. He visits a geneticist and genetic screening reveals he has the EXT 1 gene. Counseling for the patient would include telling the patient that he is more likely to have all of the following compared to a patient carrying the EXT 2 gene EXCEPT:

1.  More exostoses

2.  More limb malalignment

3.  Lower functional knee and elbow range of motion

4.  Lower rate of sarcomatous transformation

5.  Higher rate of pelvic and flatbone involvement

Back 72

This patient has hereditary multiple exostoses (HME) which is an autosomal dominant condition that leads to the development of multiple osteochondromas. The EXT 1 and EXT 2 genes are two different genes, found on different chromosomes, that lead to HME. ans4

Front 73

A 22-year-old female with hereditary osteochondromas has difficulty supinating and pronating her forearm. Radiographs are shown in Figure A. Which of the following procedures would most effectively improve forearm rotation in this patient?

1.  Combined radius and ulna corrective osteotomy

2.  Radial shaft osteotomy

3.  Radial head resection

4.  Ulnar osteotomy and lengthening

5.  Osteochondroma excision

 

Back 73

Osteochondroma excision is one of the most effective ways to improve motion in patient with limited supination and pronation due to MHE. ans5 

Front 74

A 50-year-old man with known Multiple Hereditary Exostoses complains of new onset right hip pain and an enlarging mass. Radiographs are shown in Figure A. Which of the following pathology specimens (Figure B-F) most likely represents the pathologic lesion in this patient? 

1.  metastatic carcinoma.

2.  Multiple Myeloma.

3.  osteochondroma

4.  MHE

5.  osteosarcoma. 

Back 74

The clinical presentation and imaging studies are most consistent for a patient with MHE that has had malignant transformation to a chondrosarcoma. They report that MHE is an autosomal dominant disorder. Linkage analysis has implicated mutations in the EXT gene family, resulting in an error in the regulation of normal chondrocyte proliferation and maturation that leads to abnormal bone growth. ans4

Front 75

 All of the following statements regarding hereditary multiple exostosis (HME) are correct EXCEPT?

1.  It is inherited in an autosomal dominant fashion

2.  Mutations in HME affect the prehypertrophic chondrocytes of the growth plate

3.  It is caused by mutations in either EXT1, EXT2, or EXT3 genes

4.  Radiographically, the exostoses are in direct connection to the medullary cavity

5.  Radiographically, the exostoses grow towards the physis

 

Back 75

Hereditary multiple exostosis (HME) is an autosomal dominant disorder associated with mutations in either EXT1, EXT2, or EXT3. 

The EXT proteins are tumor suppressor genes that function to glycosylate indian hedge-hog, a key cell-signaling molecules produced by the prehypertrophic chondrocytes. Mutation allows unregulated growth resulting in the characteristic exostoses. Patients with mutations in EXT1 have higher rates of sarcomatous change when compared to those with a defect in EXT2 or EXT3. 

Radiographically, the exostoses are in direct connection to the medullary cavity of the bone from which they originate and they grow away from the physis (not towards as described in Answer 5). Theses radiographic features are helpful in making the radiographic diagnosis of HME.ans5