Principles of surgery

PART II
Specific Considerations

CHAPTER 43
Orthopedic Surgery

BASIC SCIENCE QUESTIONS

1. The location marked (see Fig. 43-1) is which segment of a long bone?

A. Growth plate

B. Epiphysis

C. Metaphysis

D. Diaphysis

Answer: D

Much of an orthopedic surgeon’s practice concerns treatment of the “long bones.” Long bones generally consist of an epiphysis (the portion of the bone on either end which usually contains an articular surface). The epiphysis is formed from an epiphyseal ossification center at either end of most long bones separated from the metaphysis of the long bone by the growth plate (Fig. 43-1). After skeletal maturity, the ends of bones continue to be referred to as the epiphyseal region. The metaphysis of a long bone is the region immediately below the growth plate or its remnant. The metaphysis tapers to become the shaft or diaphysis of the long bone. (See Schwartz 9th ed., p 1559.)

Image

FIG. 43-1. Long bones have three sections. The end is the epiphysis or secondary ossification center, the adjacent area is the metaphysis, and the middle of the bone is the diaphysis. The metaphysis is broader than the diaphysis, has a thin cortex, and is composed of primarily cancellous bone.

2. Turn over of cortical bone is

A. 2 times faster than trabecular bone

B. 8 times faster than trabecular bone

C. 2 times slower than trabecular bone

D. 8 times slower than trabecular bone

Answer: D

It is important to know that all bone is subject to turnover with resorption and new bone formation, occurring in both the trabecular bone and the cortex. Cortical bone does turn over considerably slower than trabecular bone, however, by a factor of approximately seven or eight (Fig. 43-2). (See Schwartz 9th ed., p 1559, 60.)

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FIG. 43-2. The cellular and structural organization of bone.

3. Which of the following bone tumors is characterized by a 11:22 translocation?

A. Giant cell tumor of the bone

B. Chordoma

C. Chondroblastoma

D. Ewing’s sarcoma

Answer: D

Ewing’s sarcoma of bone, or Ewing’s tumor, is a small, round cell sarcoma most common in children and younger adults. Ewing’s sarcoma is most common in the long bones, especially the metaphyseal regions of the femur, tibia, and humerus. Patients present with complaints of local pain, interestingly, often accompanied by fever. Ewing’s sarcoma is an undifferentiated tumor occurring in children and primarily involves the diaphysis of long bones…. These tumors have a characteristic 11:22 translocation that can be very helpful in making the correct diagnosis. (See Schwartz 9th ed., p 1559.)

4. Which of the following is NOT one of the three stages of fracture repair?

A. Hormonal

B. Circulatory

C. Metabolic

D. Mechanical

Answer: A

The biologic and histologic events in fracture repair can be divided into three general stages. The duration and classification of each stage is variable based on age, general health, and other factors. Additionally, these stages can overlap, as there are no definitive features to suggest progression of one stage to another. The three stages are (a) circulatory, which includes closure of any wound and primary callus formation, (b) metabolic, the stage where the primary callus is reinforced leading to clinical union, and (c) mechanical, the stage in which the united bone is remodeled along the lines of stress. (See Schwartz 9th ed., p 1561.)

5. Which of the following stimulates differentiation of mesenchymal cells into osteoblasts in response to a fracture?

A. Bone morphogenic protein

B. Platelet-derived growth factor

C. Insulin-like growth factor

D. Transforming growth factor beta

Answer: A

Bone morphogenic protein is a low molecular weight protein that can influence the differentiation of mesenchymal cells into mature osteoblasts. Other protein factors that can affect fracture healing include insulin-like growth factor, transforming growth factor beta, and platelet-derived growth factor (PDGF). Insulin-like growth factor stimulates bone cell proliferation and the production of cartilage matrix. Transforming growth factor beta induces the synthesis of cartilage, proteoglycans, and type II collagen. PDGF stimulates proliferation of osteoblasts and increases the rate of synthesis of type I collagen. PDGF is also known to be a chemotactic agent and induces the migration of inflammatory cells into the callus. (See Schwartz 9th ed., p 1562.)

6. The cell of origin of a chordoma is

A. Notochordal

B. Synovial

C. Periosteal

D. Plasma cell

Answer: A

Chordomas are slow-growing malignancies derived from embryonic notochord cells. Chordomas nearly always arise in the axial skeleton and most commonly involve the occiput or the sacrum. They can be found in the vertebrae. Chordomas are not found in the extremities. About one third of these tumors arise intracranially (skull base), and about half are found in the sacrum, with the rest in the spine. (See Schwartz 9th ed., p 1595.)

7. Lateral stability of the ankle is provided by

A. The tarsal navicular

B. The medial meniscus

C. The deltoid ligament

D. The fibula

Answer: C

The ankle joint is comprised of the talus, tibia, and fibula. The talus normally fits immediately beneath the distal tibia and is restrained medially by the buttress that the medial malleolus provides. Laterally, the talus is restrained by the articular surface of the fibula which, in precise alignment with the distal tibia, allows for flexion and extension of the ankle. Ligamentous stability of the medial ankle is provided by the ‘deltoid’ ligament that attaches to the medial malleolus of the tibia and talus. Stability of the talofibular joint is provided by the anterior talofibular ligament (a common site for sprains of the ankle), the calcaneal-fibular ligament, and the posterior talofibular ligaments. (See Schwartz 9th ed., p 1565.)

CLINICAL QUESTIONS

1. Which of the following orthopedic screws are most commonly used to secure a distal bone fragment to a more proximal fragment?

A. Cortical screws

B. Cancellous screws

C. Lag screws

D. Thompson screws

Answer: C

cortical screw is a screw with a large inner diameter and shallow screw threads. This screw is designed to have a high breaking strength for its total diameter, and the screws threads are intended to engage cortical bone. Purchase of shallow screw threads in cortical bone can be excellent. Cancellous screws have a deeper thread pattern and a smaller inner shaft diameter. They are designed to obtain fixation in less dense cancellous bone. Lag screws also are commonly used. These are screws in which only the distal portion of the screw length is threaded. These screws penetrate one bone fragment without thread fixation. When a second fracture fragment is engaged by the threaded portion of the screw, turning the screw head tight down to the cortex of the first bony fragment will pull or ‘lag’ the distal fragment toward the screw head. Compression of the fractured bones is the result. (See Schwartz 9th ed., p 1563.)

2. The most appropriate treatment for posterior dislocation of the medial clavicle (at the sternoclavicular joint) is

A. Analgesics only

B. Ipsilateral sling to immobilize the shoulder

C. Closed reduction

D. Open reduction and internal fixation

Answer: C

Fractures of the medial third of the clavicle are rare. Often what appears to be a fracture of the medial clavicle is actually a dislocation of the sternoclavicular joint. When anteriorly displaced, this injury, while painful, requires only symptomatic treatment. In contrast, posterior dislocation of the sternoclavicular joint can impinge the great vessels and may be managed by closed reduction. With general anesthesia, the arm is abducted and a lateral force is applied, and a towel, clip, or bone holding clamp can be used to apply anterior forces on the clavicle that can relocate this joint. These maneuvers should be undertaken only when a surgeon is available for any associated great vessel injury. Fortunately, such injuries are rare. (See Schwartz 9th ed., p 1574.)

3. Which of the following statements is true about pilon fractures?

A. Closed reduction and casting is successful in the majority of patients

B. Skin complications are rare

C. Delayed open reduction and internal fixation is the treatment of choice

D. Posttraumatic arthritis is rare

Answer: C

High-energy fractures of the distal tibia and fibula that involve both the distal shaft of the tibia and the weightbearing surface are called tibial plafond fractures or, more commonly, pilon fractures. Due to the subcutaneous nature of these high energy fractures, skin complications, compartment syndromes, wound healing problems, and nonunions frequently complicate the care of patients with pilon fractures, which represent one of the most difficult challenges in the entire field of orthopedic trauma (Fig. 43-3). Pilon fractures almost always are displaced and are almost universally associated with significant soft tissue damage. Treatment nearly always involves open reduction and internal fixation of the bone fragments with as meticulous reconstruction of the ankle joint as possible. Immediate reconstructive surgery rarely is undertaken, however, because of the extremely high incidence of soft tissue complications. In most cases, the lower limb is stabilized by external fixation often with limited open reduction and internal fixation of the fibula to help establish and maintain anatomic length. A definitive reconstruction procedure on the tibia often is postponed until the acute swelling has resolved. This approach has been shown to lessen the incidence of soft tissue complications. With or without appropriate stabilization and timing, wound complications are common. Wound breakdown is seen in >10% of such injuries. The incidence of wound infection is high as are nonunion of the distal fragments. Posttraumatic arthritic joints are distressingly common. (See Schwartz 9th ed., p 1567.)

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FIG. 43-3. Radiographs of a severe fracture of the distal tibia and fibula, before and after open reduction and internal fixation. High-energy trauma to the distal leg can frequently lead to neurovascular injury, compartment syndrome, and wound healing problems.

4. The most common bone malignancy in children is

A. Periosteal sarcoma

B. Ewing’s sarcoma

C. Osteosarcoma

D. Rhabdomyosarcoma

Answer: C

High-grade osteogenic sarcomas generally take origin from within the medullary cavity of the bone and are the most common type of osteogenic sarcoma. It is the most common bone malignancy in children and is especially common in the distal femur, proximal tibia, and proximal humerus. (See Schwartz 9th ed., p 1592.)

5. Pubic ramus fractures are most often associated with

A. Injuries to the urethra

B. Injuries to a hollow viscus

C. Sacral fractures

D. Acetabular fractures

Answer: C

Pubic ramus fractures are frequently associated with concurrent sacral fractures. Vertical fractures through the sacral ala often involving multiple sacral foramina frequently occur with this injury. Interestingly, the sacral fractures are often quite nondisplaced and may be difficult or impossible to see on plain x-ray images. Nondisplaced fractures of the sacrum and minimally displaced fractures of the pelvic rami usually are managed with analgesics and mobilization. These injuries are compatible with full weightbearing. (See Schwartz 9th ed., p 1572.)

6. A 6-year-old presents with a tibial fracture of the metaphysis extending across the growth plate. This would be a

A. Salter-Harris type 1 fracture

B. Salter-Harris type 2 fracture

C. Salter-Harris type 3 fracture

D. Salter-Harris type 4 fracture

Answer: B

Classification of growth plate injuries has important implications as doctors communicate about the treatment of a patient. The exact type of physeal injury is important for the prognosis and treatment of the fracture. Salter and Harris described a very useful classification of growth plate injuries. A type I injury is a simple transverse failure of the physis without involvement of the ossified epiphysis or metaphysis. A Salter-Harris type II fracture contains a component of fracture through the growth plate in continuity with a fracture of the metaphysis. Salter-Harris type III fracture occurs partially through the epiphysis and partially through the growth plate. These fractures are essentially always intra-articular. A Salter-Harris type IV injury is one which has a fracture line extending through the physis extending from the metaphysis through into the epiphysis. Finally, a Salter-Harris type V injury is a subtle injury where the physis itself is injured but not displaced. (See Schwartz 9th ed., p 1602.)

7. Which of the following is most diagnostic for a compartment syndrome?

A. Compartment pressure >25 mmHg

B. Compartment pressure 20 mmHg higher than diastolic pressure

C. Tense extremity on palpation

D. Disproportionate pain and painful passive stretch of the compartment muscles

Answer: D

The diagnosis of a compartment syndrome is a clinical one, based on complaints of local pain out of proportion to the apparent injury, in association with pain, on passive stretch of the involved muscles. This situation can arise after a period of ischemia, after local blunt trauma, and, frequently, in the presence of an acute fracture. Measurement of compartment pressures, using one of a number of commercially available devices, involves inserting a needle into the suspected muscle compartments to measure pressure. Pressure measurements alone are not reliable to absolutely rule in or rule out the diagnosis, but they can be a useful adjunct to clinical assessment, particularly valuable in obtunded or unconscious patients. Pressure measurements that are greater than 30 mmHg or within 30 mmHg of the diastolic blood pressure are consistent, but not absolutely diagnostic with the presence of a compartment syndrome. The diagnosis is a clinical one. (See Schwartz 9th ed., p 1563.)

8. Which of the following is associated with fractures of the calcaneus?

A. Ligamentous injury to the knee

B. Dislocation of the hip

C. Fracture of the femur

D. Spinal fracture

Answer: D

Fractures of the calcaneus are common and frequently are associated with falls from a height. In assessing patients presenting with a fractured calcaneus, the orthopedist should always consider a possible concurrent fracture of the spine, as these injuries frequently occur together. (See Schwartz 9th ed., p 1563.)

9. Which of the following is the preferred treatment for a Monteggia fracture dislocation of the proximal forearm?

A. Closed reduction of both ulna and radius

B. Closed reduction of ulna, open reduction and fixation of radius

C. Open reduction and fixation of the ulna, closed reduction of the radius

D. Open reduction and fixation of the ulna and radius

Answer: C

This particular injury pattern is relatively common, and unfortunately, the dislocation of the radial head sometimes is unrecognized. In almost every case, an internal fixation of the ulna is indicated with closed reduction of the radial head. The treating surgeon must be alert to possible neurovascular injury and compartment syndrome. Late complications to this injury can include heterotopic ossification and redislocation of the radial head. (See Schwartz 9th ed., p 1576.)

10. Which of the following is the first radiographic finding of osteomyelitis?

A. Localized osteoporosis

B. Periosteal thickening

C. Patchy sclerosis

D. Lytic area

Answer: A

In patients with acute osteomyelitis, the radiologic features do not appear until 1 to 14 days after the onset of symptoms. The initial x-ray appearance is a vague, localized osteoporosis as a result of the removal of the dead trabecular bone and initial stages of endosteal resorption. This transforms to a mottled appearance on the plain film as more bone is resorbed, with the end result of a lytic area with or without a sequestrum. As the infection progresses, the radiologic and morphologic features transform as the inflammation becomes chronic. The marrow gradually is replaced by fibrous tissue, and the inflammatory cells are composed of mononuclear cells (i.e., lymphocytes and plasma cells). Radiologically, this appears as patchy sclerosis in the intramedullary space. A sinus tract may be appreciated especially on CT and magnetic resonance imaging (MRI). The periosteal reaction becomes more compact and often can appear lamellated. (See Schwartz 9th ed., p 1577.)

11. A 4-year-old presents with a fracture of the femur (mid shaft) with 20% of anterior angulation. Which of the following is the best treatment for this child?

A. Traction and bed rest

B. Closed reduction and application of a spica cast

C. Open reduction and internal fixation (plate)

D. Open reduction and intramedullary fixation

Answer: B

In children, femur fractures are usually low-energy injuries in contrast to adult femur fractures. Fractures of the femoral shaft in pediatric patients 6 years old may be managed with a spica cast. Minor degrees of angular deformity are acceptable and will remodel. More major degrees of angular deformities (up to 30° in the sagittal plane) may be acceptable because of the growth potential in these very young patients. Fractures in patients >6 years of age can be managed by limited internal fixation. Flexible intramedullary nails are popular in the treatment of this injury. A patient who is approaching skeletal maturity (14 years or older) may be managed by a rigid intramedullary reamed nail, much as would be used in an adult. (See Schwartz 9th ed., p 1602.)

12. Which of the following injuries is associated with forced dorsiflexion of the foot?

A. Fracture of the talus

B. Fracture of the navicular

C. Fracture of the cuneiform

D. Fracture of the cuboid

Answer: A

Fractures of the talus are common and frequently the result of forced dorsal flexion of the foot and ankle.

The tarsal bones (the navicular, the cuboid, and the three cuneiform bones) link the hind foot to the metatarsals. The precise arrangements of these bones provide mechanical stability to the arch of the foot. The large articular surfaces of these bones, however, also make avascular necrosis a potential complication with any fracture. Isolated fractures of the tarsal bones are uncommon. The force needed to fracture these bones is usually quite high. Such injuries are associated with trauma to adjacent structures, frequently including dislocations of the tarsometatarsal joints. (See Schwartz 9th ed., p 1564.)

13. Which of the following femur fractures is rarely associated with significant blood loss?

A. Femoral neck fracture

B. Intertrochanteric fracture

C. Distal femoral metaphysis fracture

D. Femoral shaft fracture

Answer: A

Fractures of the femoral neck comprise approximately one half of all fractures of the proximal femur. They are most common in elderly patients. The anatomy of the hip joint is an important consideration in the management of this fracture. The hip joint capsule extends from the rim of the acetabulum to the base of the neck of the femur. Fractures of the femoral neck are, therefore, entirely intrascapular. (See Schwartz 9th ed., p 1570.)

14. A large acute tear in the medial meniscus in a young athlete is best treated by

A. Immobilization and anti-inflammatory agents

B. Repair of the meniscus

C. Resection of the meniscus

D. Resection of the meniscus and replacement with allograft

Answer: B

Options for treatment of a meniscal tear include resection and reshaping of the torn area, generally preferred for small tears (Fig. 43-4). Very large tears in young active patients usually are treated by primary meniscal repair, generally using arthroscopic technique (Fig. 43-5). Complete excision of a torn meniscus, once quite popular, is now recommended only rarely because of loss of the meniscal load distributing function that can accelerate osteoarthritic change in the knee. On some occasions, badly injured menisci in young active patients can be successfully treated by allograft replacement of the meniscus from a cadaver source. The long-term results of this approach are not yet clear. (See Schwartz 9th ed., p 1579, 80, 81.)

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FIG. 43-4. Arthroscopic images of a tear of the medial meniscus of the knee before (top) and after (bottom) arthroscopic débridement. (Courtesy of Dr. David Green.)

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FIG. 43-5. Arthroscopic images of a vertical tear of the medial meniscus. The tear is repaired using a buried suture” technique. (Courtesy of Dr. David Green.)

15. A 15-year-old athlete with knee pain and severe point tenderness at the tibial tubercle most likely has

A. Osgood-Schlatter disease

B. Legg-Calvé-Perthes disease

C. Slipped capital femoral epiphysis (SCFE)

D. Tibial torsion

Answer: A

Osgood-Schlatter disease is a very common problem most often seen in athletically active adolescents. This disorder is characterized by ossification in the distal patellar tendon at the point of its insertion onto the tibial apophysis. This disorder is thought to result from mechanical stress on the tendinous insertional area. X-ray views of the involved knee show a characteristic irregularity in the insertional area and often show separately discrete ossicles within the tendon itself. The disease will present with severe local pain and exquisite tenderness in the area of the tibial tubercle. Effective treatment for the disease can be obtained by activity restriction, which is generally quite unwelcomed by the patient. If the symptoms are improved, athletic participation can be reasonable. In almost every case, symptoms do regress after skeletal maturity or the discontinuance of active athletic participation. In rare cases, persistive symptoms into adulthood can occur. Moderate success can be obtained by surgical excision of ossicles within the tendon of adults.

Legg-Calvé-Perthes disease, also known as coxa plana, is a condition of the pediatric hip characterized by a flattened, misshapen femoral head. The etiology of the problem is related to osteonecrosis of the proximal femoral epiphysis and is thought to result from vascular compromise. Legg-Calvé-Perthes disease generally presents in children, usually males, between the ages of 4 and 8 years old. Presenting symptoms generally include groin or knee pain, decreased hip range of motion, and a limp.

slipped capital femoral epiphysis (SCFE) is an acquired disorder of the epiphysis thought to be associated with weakness in the perichondrial ring of the growth plate. Children within the ages of 10 to 16 years old are noted to have the displacement of the epiphysis on the femoral neck. In most cases, there is no identifiable trauma history. It is not known whether this is acquired insidiously or acutely. It is associated with African American heritage and obesity and is somewhat more common in boys than in girls. Twenty-five percent of cases are bilateral.

Tibial torsion is the most common cause of an intoeing gait. This is most frequently noted in 1- and 2-year-old children. This is often bilateral. Although occasionally intoeing can be marked, pediatric tibial torsion will completely resolve without treatment in almost every case. (See Schwartz 9th ed., p 1606.)

16. Which of the following is the most common cervical fracture seen after a diving accident?

A. Dens (odontoid) fracture (C1)

B. Hangman fracture (C2)

C. Compression fracture (C3-7)

D. Burst fracture (C3-6)

Answer: D

Burst fractures of the cervical spine arise as a result of failure under axial loads. Unrestrained motor vehicle occupants striking a windshield and diving accidents are common injury mechanisms. The burst fracture is distinct from the compression fracture, however, in that the posterior cortex of the vertebral body is fractured. This frequently results in displacement (retropulsion) of bony fragments into the canal, which can cause neurologic injury and dysfunction.

The Jefferson fracture is a fracture of the C1 ring. The C1 vertebra does not have a true anterior body as do all of the rest of the vertebrae. The rather thin anterior and posterior rings are subject to fracture, particularly with axial load injuries. The Jefferson fracture results in a lateral spread of the lateral masses of C1, which are visible on an AP (through the mouth) x-ray image of the upper cervical spine. This injury actually results in an increase in the size of the spinal canal, and thus, rarely is associated with neurologic injury.

Hangman’s fractures or traumatic spondylolisthesis of C2 are fractures that occur through the pars interarticularis of C2 (the segment of the posterior elements between the superior and inferior facets of C2). This fracture results from sudden extension forces on the neck causing a fracture through this area of C2, which is one of the thinner portions of the posterior elements of this vertebra.

Compression fractures of the cervical spine refer to an axial load injury with failure of the end plate, but preservation of the posterior cortex of the vertebral body. This will occur in the vertebrae of C3 to C7 and may or may not be associated with a fracture of the anterior cortex. In either case, with the posterior cortex of the vertebral body intact, no compromise of the neural elements results. (See Schwartz 9th ed., p 1583, 85 and Fig. 43-6.)

Image

FIG. 43-6. The spine can be thought of as three columns. Two of three can maintain stability.

17. Following attempts at closed reduction, a lateral malleolus fracture has a 2-mm displacement. Which of the following is the best treatment?

A. No weight bearing for 2 weeks

B. Splinting

C. Casting

D. Open reduction and internal fixation

Answer: D

An isolated distal fibula fracture, often referred to as a lateral malleolus fracture, should be anatomically reduced whenever possible. This often can be accomplished by closed reduction and casting (Figs. 43-7 and 43-8). If closed reduction maneuvers do not result in an anatomic or near-anatomic restoration of the anatomy of the ankle, precise open reduction and internal fixation is indicated. Even a disruption of as little as 1 mm in the position of the lateral malleolus can result in a lateral shift of the talus and a decreased contact area between the tibia and talus of almost 50% and can markedly accelerate degenerative arthritis. Surgical exposure of the distal fibula is by a lateral incision. Fracture fragments are precisely aligned and fixed in place generally using a screw and plate device. With accurate reduction and internal fixation, excellent function can result. (See Schwartz 9th ed., p 1566.)

Image

FIG. 43-7. Anteroposterior radiograph of a patient with a bimalleolar fracture.

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FIG. 43-8. Anteroposterior radiograph of a patient who has an open reduction and internal fixation of the bimalleolar ankle fracture.

18. The most appropriate initial treatment for a symptomatic osteoid osteoma of the distal tibia is

A. Oral anti-inflammatory medication (aspirin or NSAID)

B. Radiofrequency ablation

C. Local resection

D. Amputation

Answer: A

Osteoid osteoma is a benign bone-forming lesion of uncertain etiology that presents with a central radiolucent nidus (1.5 cm) and dense surrounding sclerosis. This lesion occurs in patients under the age of 20 years old (usually under the age of 12) but can occasionally occur in older patients. They are predominantly intracortical in location except when they occur in the small bones of the hands and feet where they are intramedullary. Radiologically, they are noted to be a dense cortical sclerosis on plain film. The nidus can be difficult to observe, and CT often is helpful in this regard. Histologically, the nidus is a dense fibrovascular proliferation with abundant new bone formation and active osteoblastic and osteoclastic activity. The surrounding sclerosis is very dense and approaches that seen in the normal cortex. The pain produced by this tumor can be quite intense. Interestingly, this pain is predictably dramatically responsive to aspirin or NSAID medication. Indeed, regular medication with anti-inflammatories often can present definitive treatment for these lesions which in a significant proportion of cases spontaneously regress, usually after a period of 1 to 7 years. Should more aggressive treatment be contemplated, an accessible lesion can be treated by percutaneous radiofrequency ablation (heat administered through high frequency alternating currents). On other occasions, it can be treated by surgical excision. (See Schwartz 9th ed., p 1590.)



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