AAOS & ABOS Orthopedic 2026 MCQs (Set 1): Unicameral Bone Cysts & Femoral Stress Fractures | Board Review

Key Takeaway
This high-yield question set for the AAOS/ABOS exams covers critical topics including the diagnosis and management of unicameral bone cysts, especially in pediatric patients, detailing radiographic and histologic features. Additionally, it features questions on femoral neck stress fractures, focusing on diagnosis in elderly patients and characteristic imaging findings like MRI.
Comprehensive 100-Question Exam
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Question 1
A patient with a below-the-knee amputation is being evaluated for a new prosthesis. He wants to improve his ability to walk on uneven surfaces. What modification to the prosthesis can be made to accommodate this request?
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Question 2
A 58-year-old woman is seen in the emergency department after falling at home. History reveals that she underwent right total knee arthroplasty 2 years ago. Radiographs are shown in Figures 56a and 56b. What is the most appropriate treatment?

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Question 3
Figure 9 shows the AP radiograph of a 65-year-old man who has knee pain and swelling. What is the most likely diagnosis?

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Question 4 High Yield
A 68-year-old woman stepped on a needle while walking barefoot 10 days ago. She is not certain but thinks it is imbedded in her foot, and she notes local tenderness at the puncture site and drainage. Her primary care physician has been treating her with oral antibiotics. A plain radiograph is shown in Figure 38. What is the best course of action?

Detailed Explanation
Question 5High Yield
Figures 46a through 46e show the radiographs of a 22-year-old man who injured his wrist in a motorcycle accident. He has no other injuries. What is the best course of action?

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Question 6
Which of the following symptoms are most commonly associated with piriformis syndrome?
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Question 7High Yield
A 24-year-old athlete has a painful right shoulder. Figure 30 shows an intra-articular photograph that was obtained through a posterior portal during arthroscopy; the labrum is indicated by the arrow. Based on these findings, management should consist of

Explanation
Question 8
A 100-lb 9-year-old boy has a closed midshaft transverse femoral fracture. The oblique fracture is shortened by 3 cm with a 10-degree varus angulation. Surgical management consists of intramedullary, retrograde flexible titanium nailing. To optimize fracture stability, the surgeon should
Explanation
Question 9
A 13-year-old boy has a painless "knot" over his left hip. History reveals that he injured his left hip playing soccer 4 months ago. A radiograph and MRI scan obtained at the time of injury are shown in Figures 7a and 7b. He is very active and is currently asymptomatic. A current radiograph is shown in Figure 7c. What is the next most appropriate step in management?

Explanation
Question 10High Yield
A 39-year-old man has had persistent right shoulder pain for the past 6 months. A formal physical therapy program has failed to provide relief, and an injection several months ago provided only short-term relief. Examination reveals a positive Neer and Hawkins test. There is no instability and the neurovascular examination is normal. Arthroscopy reveals a partial rotator cuff tear on the bursal side measuring 60% of the tendon thickness. What is the next most appropriate step in management?

Explanation
Question 11
A 43-year-old woman has an enlarging mass in the left groin. A radiograph, CT scan, and a biopsy specimen are shown in Figures 42a through 42c. Treatment should consist of

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Question 12
Which of the following clinical findings is commonly associated with symptomatic partial-thickness rotator cuff tears?
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Question 13
What is the prognosis for ambulation, from best to worst, for patients with an incomplete spinal cord injury?
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Question 14
A 12-year-old boy with hemophilia A and no known inhibitors sustains a tibia fracture and has pain with passive motion of the deep toe flexors. Appropriate management should consist of
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Question 15
A 25-year-old competitive skier sustains a twisting injury to the right ankle while skiing. She is unable to continue the activity secondary to severe lateral ankle pain. Examination reveals ecchymosis and fullness over the lateral malleolus with pain and weakness on active ankle dorsiflexion and external rotation. There is no medial-sided pain. Neurovascular examination is normal. An AP radiograph and MRI scan are shown in Figures 17a and 17b, respectively. Management should consist of

Explanation
Question 16High Yield
Figures 4a through 4c show the radiographs of a 43-year-old woman who sustained a twisting injury to her right ankle. She has ankle pain and tenderness medially and laterally. To help determine the optimal treatment, an external rotation stress radiograph of the ankle is obtained. This test is designed to evaluate the integrity of what structure?

Explanation
Question 17
Figure 50 shows the radiograph of a 26-year-old man who sustained an isolated open injury to his foot. Examination reveals no gross contamination in the wound. There is a palpable dorsalis pedis pulse and sensation is present on the dorsal and plantar aspects of the foot. Initial treatment should consist of wound debridement, antibiotics, and

Explanation
Question 18High Yield
A 16-year-old girl has had pain and swelling along the medial arch of her left foot for the past 3 months. She also reports pain from shoe wear and while running. Nonsteroidal anti-inflammatory drugs have failed to provide relief. Radiographs are shown in Figures 40a through 40c. What is the next most appropriate step in management?

Explanation
Question 19
A 51-year-old man sustained an open fracture of his tibia in Korea 42 years ago. An infection developed and it was resolved with surgical treatment. For the past 6 months, an ulcer with mild drainage has developed over the medial tibia. The ulcer is small and there is minimal erythema at the ulcer site. A radiograph and MRI scan are shown in Figures 43a and Figure 43b. Initial cultures show Staphylococcus aureus susceptible to the most appropriate antibiotics. Laboratory studies show an erythrocyte sedimentation rate of 70 mm/h. What is the most appropriate surgical treatment at this time?

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Question 20High Yield
A 24-year-old dancer sustains the injury shown in Figure 28. Management should consist of

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Question 21
Figures 3a and 3b show the inversion stress radiographs of a patient's ankle. What is the most likely ligament injury pattern?

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Question 22 High Yield
A patient sustained a sharp laceration to the base of his left, nondominant thumb 4 months ago. Examination reveals no active flexion but full passive motion of the interphalangeal joint. What is the best treatment option?

Detailed Explanation
Question 23High Yield
What is the most significant prognostic factor in nontraumatic osteonecrosis of the humeral head?

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Question 24High Yield
A 28-year-old man has had a 2-year history of progressive lateral ankle pain. History reveals that he underwent a triple arthrodesis at age 13 for a tarsal coalition. The pain has been refractory to braces, custom inserts, and nonsteroidal anti-inflammatory drugs. Weight-bearing radiographs of the ankle and foot are shown in Figures 3a through 3d. Surgical management should include which of the following?

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Question 25
Figures 5a and 5b show axial and coronal MRI images of the left ankle of a patient with lateral ankle pain. What is the most likely diagnosis?

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Question 26
What is the most common donor site complication following a free vascularized fibular graft for osteonecrosis of the femoral head?
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Question 27High Yield
A 58-year-old woman is seen in the emergency department after falling at home. History reveals that she underwent right total knee arthroplasty 2 years ago. Radiographs are shown in Figures 56a and 56b. What is the most appropriate treatment?

Explanation
Question 28 High Yield
In patients who have undergone nonsurgical management for idiopathic adhesive capsulitis, long-term follow-up studies have shown which of the following results?
Detailed Explanation
Question 29
A newborn girl with an isolated unilateral dislocatable hip is placed in a Pavlik harness with the hips flexed 100 degrees and at resting abduction. Figure 23 shows an ultrasound obtained 2 weeks later. What is the next step in management?

Explanation
Question 30
A 55-year-old woman with polyarticular rheumatoid arthritis has had progressively increasing left shoulder pain for the past 2 years despite nonsurgical management. No focal weakness is noted during examination of the shoulder. AP and axillary radiographs are shown in Figures 47a and 47b. Treatment should consist of

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Question 31
The main advantage of surgical repair of an acute Achilles tendon rupture, when compared with nonsurgical management, is reduced

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Question 32 High Yield
A 13-year-old girl who is 2 years postmenarche has been referred for management of scoliosis. She denies any history of back pain. Radiographs show a right thoracic curve of 35 degrees. She has a Risser sign of 4 and a bone age of 15.5 years. Management should consist of
Detailed Explanation
Question 33High Yield
Which of the following findings can cause a dorsal bunion in a patient with neuromuscular disease?

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Question 34
A 19-year-old man has had pain and swelling in his left forearm for the past 8 months. Laboratory studies show a mildly elevated WBC count and erythrocyte sedimentation rate. Radiographs are shown in Figures 58a and 58b, a CT scan is shown in Figure 58c, and T1- and T2-weighted MRI scans are shown in Figures 58d and 58e, respectively. A biopsy specimen is shown in Figure 58f. Immunohistochemistry demonstrates that the lesion is negative for leukocyte common antigen (CD34). What is the most common cytogenetic translocation associated with this lesion?

Explanation
Question 35
A 26-year-old man has had a 2-year history of pain and stiffness after sustaining a comminuted olecranon fracture. Treatment at the time of injury consisted of open reduction and internal fixation with tension band wiring. Examination reveals motion of 45 degrees to 110 degrees and pain throughout the arc of motion. Resisted flexion and extension are painful. Forearm rotation is normal. Radiographs are shown in Figure 51. Treatment should consist of

Explanation
Question 36High Yield
A 20-year-old man reports painless snapping about the lateral aspect of the right hip. He denies any history of trauma. Examination reveals no limp or tenderness. Hip range of motion is full, and there is good strength. Radiographs are normal. What anatomic structure is most likely causing these symptoms?
Explanation
Question 37
A 63-year-old woman who sustained a distal radial fracture 2 months ago now reports that she is unable to achieve active extension of the thumb at the interphalangeal joint. What type of trauma may lead to this clinical finding?
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Question 38High Yield
Figure 11a shows the clinical photograph of a 46-year old woman who reports a 3-week history of pain and a "lump" at the base of her neck. She is otherwise in good health and denies any trauma. A 3-D reconstruction CT is shown in Figure 11b. What is the most likely diagnosis?

Explanation
Question 39
A 70-year-old man underwent primary total knee arthroplasty 3 months ago. Figures 7a and 7b show the radiograph and clinical photograph following incision and drainage of the wound 1 week ago. Aspiration of the joint reveals methicillin-sensitive Staphylococcus aureus. What is the next most appropriate step in management?

Explanation
Question 40High Yield
A 39-year-old woman fell onto her flexed elbow and sustained a comminuted displaced radial head and neck fracture. Radiographs confirm concentric reduction of the ulnohumeral joint. Examination reveals pain with compression of the radius and ulna at the wrist. What is the best treatment for the radial head fracture?
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Question 41High Yield
Degenerative spondylolisthesis of the cervical spine is most commonly seen at which of the following levels?
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Question 42
Figures 3a and 3b show the current radiographs of a 58-year-old man who underwent total knee arthroplasty with a cruciate ligament sparing prosthesis 7 years ago. Examination reveals boggy synovitis and moderate pain, particularly anteriorly. Management should consist of

Explanation
Question 43High Yield
A 32-year-old runner has pain in the medial arch that radiates into the medial three toes. He reports the presence of pain only when running. Examination reveals normal hindfoot alignment. There is a weakly positive Tinel's sign over the posterior tibial nerve. Tenderness is noted with palpation over the plantar medial area in the vicinity of the navicular tuberosity. What is the most likely diagnosis?
Explanation
Question 44High Yield
Figure 1 shows the radiograph of a 68-year-old man who underwent revision hip arthroplasty with impaction grafting of the femur and cementing of a tapered component into the graft 2 years ago. The patient remains symptom-free. Which of the following best describes the most likely histologic appearance of the proximal femur if a biopsy was performed?

Explanation
Question 45High Yield
Figures 9a and 9b show the spinal radiographs of a 3-year-old child with short limb dwarfism. The lateral radiograph is obtained with maximal lumbar extension. Management should consist of

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Question 46High Yield
Figures 32a and 32b show the radiographs of an active 13-year-old boy who has persistent left thigh pain and a limp despite a trial of protected weight bearing. Management should consist of

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Question 47High Yield
A knock-out mouse for the Vitamin D receptor has which of the following phenotypes?
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Question 48
What is the most significant factor affecting long-term survival for a patient with bone sarcoma?

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Question 49
Figures 35a and 35b show the radiographs of a 7-year-old patient who has progressive deformity of the right thigh accompanied by a dull persistent pain radiating to the knee. Examination reveals an obvious bulge in the right thigh, with flexion of the hip beyond 50 degrees only if the hip is allowed to externally rotate. Management should consist of

Explanation
Question 50
Figure 39 shows the sagittal T1-weighted MRI scan of a 27-year-old man who twisted his knee 2 weeks ago. The arrow is pointing to

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Question 51High Yield
A 16-year-old girl has had pain and swelling along the medial arch of her left foot for the past 3 months. She also reports pain from shoe wear and while running. Nonsteroidal anti-inflammatory drugs have failed to provide relief. Radiographs are shown in Figures 40a through 40c. What is the next most appropriate step in management?

Explanation
Question 52
The use of radiation therapy is most effective in metastatic bone disease from which of the following tumors?
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Question 53High Yield
A 12-year-old boy falls from a bicycle. A radiograph of his injured shoulder is shown in Figure 41. What is the optimal method of treatment?

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Question 54High Yield
Which of the following mechanisms of inhibition has been linked to cigarette smoking and lumbar spinal fusion?
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Question 55
In the anterior forearm approach to the distal radius (Henry approach), the radial artery is located between what two structures?

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Question 56High Yield
What is the main function of collagen found within articular cartilage?

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Question 57High Yield
A 20-year-old man sustains the injury shown in Figures 1a and 1b in a motorcycle accident. In addition to a prompt closed reduction, his outcome might be optimized by

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Question 58High Yield
The dorsal (Thompson) approach to the proximal forearm uses which of the following intermuscular intervals?

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Question 59
A 29-year-old woman reports dysesthesias and burning after undergoing bunion surgery that consisted of a proximal crescentic first metatarsal osteotomy 6 months ago. Examination reveals a positive Tinel's sign at the proximal aspect of the healed incision. What injured nerve is responsible for her continued symptoms?
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Question 60 High Yield
Ganglion cysts about the wrist most commonly arise from what structure?
Detailed Explanation
Question 61High Yield
A 66-year-old man has a high-grade angiosarcoma of the right tibia. A radiograph is shown in Figure 43. Treatment should consist of

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Question 62 High Yield
A 30-year-old man caught his dominant little finger on the straps of his windsurfing board 10 days ago. He reports swelling about the distal phalanx and has difficulty completely extending the distal interphalangeal joint. A radiograph is shown in Figure 47. What is the most appropriate treatment for this injury?

Detailed Explanation
Question 63
Figure 30 shows the radiograph of a 38-year-old man who reports persistent pain laterally and plantarly about the fifth metatarsal head. Examination reveals calluses dorsolaterally and plantarly about the fifth metatarsal head. Nonsurgical management has failed to provide relief. Surgical treatment should include

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Question 64
A 16-year-old girl has had anterior leg pain and a mass for the past 8 months. Figures 2a and 2b show a radiograph and an H & E histologic specimen. Which of the following disorders is believed to be a precursor of this lesion?

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Question 65High Yield
Which of the following structures runs through the site indicated by the arrow in Figure 11?

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Question 66High Yield
Which of the following properties primarily provides the excellent corrosion resistance of metallic alloys such as stainless steel and cobalt-chromium-molybdenum?
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Question 67
When planning scoliosis surgery for a patient with a 50-degree thoracolumbar curve and spinal muscular atrophy, it is most important to include

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Question 68High Yield
A 24-year-old woman has a spleen laceration and hypotension. Radiographs reveal a pulmonary contusion and a displaced mid-diaphyseal fracture of the femur. The trauma surgeon clears her for stabilization of the femoral fracture. What technique will offer the least potential for initial complications?

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Question 69
What structure is marked Q in the diagram of the brachial plexus shown in Figure 22?

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Question 70
During anterior surgery on the cervical spine, at what level would the lateral dissection of the longus coli muscle most likely cause Horner's syndrome?

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Question 71
A 45-year-old man who underwent an open capsulolabral stabilization procedure 15 years ago now reports pain and has no external rotation on the affected side. Nonsurgical management has failed to provide relief. Examination reveals external rotation to -5 degrees compared with 50 degrees of external rotation on the contralateral side. Radiographs show a small inferior osteophyte and minimal posterior glenoid wear. Which of the following procedures will offer the best chance of restoring motion, decreasing pain, and preserving the native joint?

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Question 72 High Yield
What clinical parameter will most likely decrease the need for blood transfusion after total joint arthroplasty?
Detailed Explanation
Question 73High Yield
What is the most common secondary malignancy arising in pagetic bone?

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Question 74High Yield
Figure 38 shows the radiograph of a 75-year-old woman who has had right shoulder pain, difficulty sleeping on the affected arm, and difficulties performing activities of daily living for the past 6 weeks. Initial nonsurgical management includes analgesics, a subacromial cortisone injection, and gentle range-of-motion exercises. However, these modalities have failed to provide relief, and the patient reports that she is unable to elevate her arm. Her pain is worse and she would like the most reliable treatment method for pain relief and functional improvement. What is the best surgical treatment?

Explanation
Question 75High Yield
Figure 38 shows the radiograph of a 5-year-old child who sustained a type III supracondylar fracture. Examination reveals the absence of a radial pulse, but an otherwise well-perfused hand. Following closed reduction and percutaneous pinning, the radial pulse remains absent; however, the hand is pink and well perfused. Management should now include

Explanation
Question 76
Figures 29a and 29b show the AP and lateral radiographs of a 30-year-old man who has increasingly worse back pain and stiffness. Examination shows painful, limited spinal range of motion. There is no neurologic deficit. What laboratory study would be most helpful in confirming the diagnosis?

Explanation
Question 77
A pediatric orthopaedic surgeon refers a child to a neurologist. The neurologist's office requests the office records of the pediatric orthopaedic surgeon. To maintain Health Insurance Portability and Accountability Act (HIPAA) compliance, what must the surgeon obtain from the parent(s) prior to sending records?

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Question 78High Yield
The medial collateral ligament complex of the elbow originates on what portion of the medial epicondyle?
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Question 79
A 7-year-old boy has had low back pain for the past 3 weeks. Radiographs reveal apparent disk space narrowing at L4-5. The patient is afebrile. Laboratory studies show a WBC count of 9,000/mm3 and a C-reactive protein level of 10 mg/L. A lumbar MRI scan confirms the loss of disk height at L4-5 and reveals a small perivertebral abscess at that level. To achieve the most rapid improvement and to lessen the chances of recurrence, management should consist of
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Question 80High Yield
What is the most common bacteria cultured from dog and cat bites to the upper extremity?
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Question 81High Yield
Which of the following tumors is most likely to present with a pathologic fracture in a child?

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Question 82High Yield
Acetaminophen is an antipyretic medication. It exerts its pharmacologic effects by inhibiting which of the following enzymes?
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Question 83High Yield
An otherwise healthy 57-year-old man has persistent, severe hip pain after undergoing total hip arthroplasty 3 months ago. What is the next most appropriate step in management?

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Question 84
A 6-year-old child has a fixed flexion deformity of the interphalangeal (IP) joint of the right thumb. The thumb is morphologically normal, with a nontender palpable nodule at the base of the metacarpophalangeal joint. Clinical photographs are shown in Figures 42a and 42b. Based on these findings, what is the treatment of choice?

Explanation
Question 85 High Yield
A 35-year-old man has numbness and tingling in the index, middle, and ring fingers. History reveals that he also has had vague wrist pain and stiffness since being injured in a motorcycle accident 1 year ago. Radiographs are shown in Figures 47a through 47c. Management should consist of

Detailed Explanation
Question 86
A biopsy of the involved physis in a patient with slipped capital femoral epiphysis (SCFE) would most likely reveal
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Question 87High Yield
Which of the following anatomic structures is labeled 6 in Figure 27?

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Question 88
A previously healthy 14-year-old boy now reports fatigue, and has a bilateral Trendelenburg gait, right hip pain, and bilateral knee and foot pain. Biopsy of a right sacral mass reveals intermediate grade osteosarcoma. There are no metastases. Laboratory studies reveal a serum calcium level of 7.7 mg/dL (normal 8.5 to 10.5), a phosphate level of 2.0 mg/dL (normal 2.7 to 4.5), a 1,25-dihydroxyvitamin D level of less than 10 pg/mL (normal 18 to 62), a parathyroid hormone level of 19 pg/mL (normal 10 to 60), and an alkaline phosphatase level of 428 U/L (normal 15 to 351). What is the most likely cause of the patient's symptoms?
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Question 89
A patient has had a locked posterior dislocation of the shoulder for the past 6 months. After undergoing total shoulder arthroplasty that includes adequate anterior releases and posterior capsulorrhaphy, the patient still exhibits posterior instability intraoperatively. The postoperative rehabilitation regimen should include

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Question 90High Yield
A patient notes pain under the first metatarsophalangeal joint following a soccer injury. The MRI scans shown in Figures 27a and 27b reveal what pathologic finding?

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Question 91
A 50-year-old woman who underwent a joint replacement of the hallux metatarsophalangeal joint 6 months ago now has pain and swelling about the great toe. Radiographs are shown in Figures 39a and 39b. What is the next most appropriate step in management?

Explanation
Scientific References
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Question 92
In the arthroscopic photograph shown in Figure 5, the structure labeled "A" functions primarily as a restraint to translation of the humeral head in what direction?

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Question 93 High Yield
Figures 11a and 11b show the T2-weighted MRI scans of the lumbar spine of a 53-year-old woman who has low back and right lower extremity pain. What structure is the arrow pointing to in Figure 11a?

Detailed Explanation
Question 94
Which of the following tumors is most likely to present with a pathologic fracture in a child?

Explanation
Question 95High Yield
A 35-year-old woman reports an 8-week history of neck pain radiating to her right upper extremity. She denies any history of trauma or provocative event. Examination reveals decreased pinprick sensation in her right middle finger, otherwise sensation is intact bilaterally. Finger flexors and interossei demonstrate 5/5 motor strength bilaterally. Finger extensors are 4/5 on the right and 5/5 on the left. The triceps reflex is 1+ on the right and 2+ on the left. The most likely diagnosis is a herniated nucleus pulposus at what level?
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Question 96
What is the most likely primary cause of decreased success rates of bony fusion in smokers undergoing lumbar arthrodesis?

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Question 97
A 42-year-old man undergoes right total hip arthroplasty for hip dysplasia. Postoperatively, he has a significant limb-length increase with a foot drop. A preoperative radiograph is shown in Figure 19. Which of the following should have been considered preoperatively to avoid this complication?

Explanation
Question 98High Yield
A 30-year-old man underwent an open Bankart repair with capsulorrhaphy for recurrent anterior instability 6 months ago. In a recent fall, he described a hyperabduction and external rotation mechanism of injury. He denies dislocating his shoulder. He now has anterior shoulder pain, weakness, and the sensation of instability. Examination reveals tenderness just lateral to the coracoid and bicipital groove. An MRI scan is shown in Figure 31. Management should now consist of

Explanation
Question 99High Yield
A 24-year-old athlete has a painful right shoulder. Figure 30 shows an intra-articular photograph that was obtained through a posterior portal during arthroscopy; the labrum is indicated by the arrow. Based on these findings, management should consist of

Explanation
Question 100High Yield
What structure is located immediately posterior to the capsule at the posterior cruciate ligament tibial insertion?
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