This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 4501
Topic: 1. General Principles & Basic Science
Figure 48 shows an MRI scan of the knee. The arrow is pointing to what structure?
Correct Answer & Explanation
. Biceps femoris
Explanation
The arrow points to the biceps femoris, which is inserted onto the fibula. The biceps femoris lies at the posterolateral aspect of the thigh. The semimembranosus and the semitendinous lie at the posterior medial aspect of the thigh. Gray H: Anatomy of the Human Body. Philadelphia, PA, Lea and Febiger, 1918, 2000.
Question 4502
Topic: 1. General Principles & Basic Science
A 13-year-old girl with Down syndrome has bilateral chronic patellar dislocations. She denies knee pain. She is able to straighten her knees and walks with a symmetric but awkward gait. She does not flex her knees in midstance. Examination reveals that the patellae cannot be brought into a reduced position. Management should consist of
Correct Answer & Explanation
. continued observation.
Explanation
Chronic dislocation of the patella is occasionally seen in patients with Down syndrome. In early childhood, patellar realignment may restore stability of the patellae. In later childhood, bony changes in the patellar groove interfere with stability, even if surgical realignment is performed. Realignment can also lead to increased knee pain postoperatively. In asymptomatic patients who are able to extend their knees, continued observation is the management of choice. Dugdale TW, Renshaw TS: Instability of the patellofemoral joint in Down syndrome. J Bone Joint Surg Am 1986;68:405-413.
Question 4503
Topic: 1. General Principles & Basic Science
A 78-year-old woman has had activity-limiting cervical pain and occipital headaches for the past 4 years. Management consisting of injections, analgesics, and part-time collar wear has provided temporary relief. Examination reveals that her neck pain seems to be primarily located immediately below the skull and is aggravated by long periods of sitting and rotation of her head. Plain radiographs are shown in Figures 36a through 36c. What is the best course of action?
Correct Answer & Explanation
. Posterior atlantoaxial arthrodesis
Explanation
Posterior atlantoaxial arthrodesis predictably relieves pain associated with arthrosis of the atlantoaxial joints. Typically, these patients have pain at the base of the occiput and in the most cephalad portion of the posterior aspect of the neck. Associated headache is common and often severe. Pain is aggravated by rotation but usually not by flexion and extension. Diagnostic blocks of the C1-C2 joint and the greater occipital nerve may be helpful to confirm the diagnosis preoperatively. Ghanayem AJ, Leventhal M, Bohlman HH: Osteoarthrosis of the atlanto-axial joints: Long-term follow-up after treatment with arthrodesis. J Bone Joint Surg Am 1996;78:1300-1307.
Question 4504
Topic: Biology, Genetics & Bone Healing
A female cross-country runner has an insidious onset of right groin pain. Radiographs of the right hip reveal a tension-side stress fracture. History reveals that she was treated for a "foot" fracture 1 year ago. In addition to performing internal fixation of the femoral neck, which of the following should be obtained?
Correct Answer & Explanation
. Menstrual history
Explanation
Stress fractures in female long distance runners are frequently associated with the Female Athletic Triad. The triad consists of osteoporosis, amenorrhea, and altered eating habits. A thorough menstrual history, including age of menarche, history of amenorrhea, and use of oral contraceptives, is imperative. Amenorrhea leads to osteoporosis and predisposes the athlete to fractures. An MRI of the hip is not necessary because a fracture is evident on the radiograph. Serum calcium levels are normal in osteoporosis, a family history would be noncontributory, and it is highly unlikely that a contralateral hip radiograph will yield useful information. Bennell KL, Malcolm SA, Thomas SA, et al: Risk factors for stress fractures in track and field athletes: A twelve-month prospective study. Am J Sports Med 1996;24:810-818.
Question 4505
Topic: 1. General Principles & Basic Science
What changes in muscle physiology would be expected in an athlete who begins a rigorous aerobic program for an upcoming marathon?
Correct Answer & Explanation
. Hypertrophy of type I muscle fibers
Explanation
Muscle fibers can be categorized grossly into two types. Type I muscle, also known as slow-twitch muscle, is responsible for aerobic, oxidative muscle metabolism. It has a much lower strength and speed of contraction than fast-twitch type II muscle but is significantly more fatigue resistant. With training for endurance sports, the type I muscle undergoes adaptive changes to the increased stress. Increases in capillary density, oxidative capacity, mitochondrial density, and subsequent fatigue resistance are all observed changes. Hypertrophy of type IIb muscle is seen in strength training. Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 89-125.
Question 4506
Topic: Infection, Pharmacology & VTE
A 52-year-old woman reports mild pain localized to the left sternoclavicular joint. History is notable for chronic renal failure requiring dialysis for the last 5 years. A clinical photograph, chest radiograph, and bone scan are shown in Figures 58a through 58c. What is the most likely diagnosis?
Correct Answer & Explanation
. Chronic osteomyelitis
Explanation
Spontaneous swelling with the appearance of joint subluxation may be associated with an acute, subacute, or chronic bacterial infection of the sternoclavicular joint. Common causes of infection include bacteremia, rheumatoid arthritis, alcoholism, intravenous drug use, and chronic debilitating diseases. Subclavian vein catheterization and renal dialysis can predispose patients to sepsis and osteomyelitis of the sternoclavicular joint. Renoult B, Lataste A, Jonon B, et al: Sternoclavicular joint infection in hemodialysis patients. Nephron 1990;56:212-213.
Question 4507
Topic: Physiology & Rehabilitation
A college football player performs bicep curls as part of his weight lifting routine. During the flexion phase of the curl, what term defines the type of muscle contraction?
Correct Answer & Explanation
. Eccentric
Explanation
Muscle contractions can be classified by tension, length, and velocity. Isometric contractions involve changing tension in the muscle while the muscle stays at a constant length. An example would be pushing against a wall. Isokinetic contractions occur when the muscle maximally contracts at a constant velocity. Isotonic contractions involve constant tension throughout the range of motion. Eccentric contraction is when the muscle lengthens during contraction. Eccentric contractions have the highest risk of injury. Plyometrics are eccentric contractions at a rapid rate. Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 89-125.
Question 4508
Topic: 1. General Principles & Basic Science
Outcome measures should have established psychometric properties of reliability, validity, and responsiveness. Reliability refers to which of the following?
Correct Answer & Explanation
. The reproducibility of the measurements either between repeated tests or between observers
Explanation
The recent JBJS article by Kocher and associates defines the different psychometric properties that are used in outcome measures. Reliability is a measure of how reproducible a test is. This can be interobserver reliability (ie, reliability between people), or intraobserver reliability (ie, reliability for the same person doing the outcome measure at different occasions).
Question 4509
Topic: Biology, Genetics & Bone Healing
Which of the following accurately defines changes in Vitamin D requirements as the result of aging?
Correct Answer & Explanation
. Increase, but calcium requirements remain the same
Explanation
Older individuals ingest less Vitamin D and are unable to generate as much as younger people via the skin in response to ultraviolet exposure; thus, there is a decrease in the levels of serum 25(OH) D. This reduction in 25(OH)D leads to a reduction in calcium absorption. There is also decreased conversion in the kidney of 25(OH)D to 1,25(OH)D. This all leads to an increase in the daily requirements of both calcium and Vitamin D. It also results in a responsive increase in PTH secretion in the elderly, as well as renal function impairment and possible renal resistance to PTH. Dawson-Hughes B, Harris SS, Krall EA, et al: Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age and older. N Engl J Med 1997;337:670-676. Recker RR, Hinders S, Davies M, et al: Correcting calcium nutritional deficiency prevents spine fractures in elderly women. J Bone Miner Res 1996;11:1961-1966.
Question 4510
Topic: 1. General Principles & Basic Science
There is increasing concern about the ethical relationship of orthopaedists to the orthopaedic equipment industry. Which of the following describes the most appropriate relationship?
Correct Answer & Explanation
. Industry-paid travel and hotel for a faculty member at an industry-sponsored meeting that is not CME approved
Explanation
It is appropriate for orthopaedic surgeons to have relationships with industry as long as the relationship is for the good of the patient and no "quid pro quo" intent exists. A grant to cover registration at a CME event is appropriate but travel and hotel for a spouse is not. For orthopaedists who are faculty at a meeting sponsored by industry, it is appropriate for travel and expenses to be covered for that faculty member. Care must be exercised that the faculty member contributes in an amount appropriate for the expenses paid. The faculty member must ensure that information presented is unbiased and based on reasonable data and opinion. Consulting agreements should spell out specifically the duties of the agreement and payment should be appropriate for the time spent. There should be a defined work product for the consulting. Agreements that are thinly veiled payments for use of a company's products must be avoided. In all cases, the agreements must stand up to public scrutiny. Restricted grants for specific industry-sponsored programs aimed at residents are not appropriate. Unrestricted grants intended for attendance at approved CME courses are appropriate. Dinners at which information is presented about topics that can aid in patient care are appropriate as long as the expense is reasonable ($100 or less/person) and the guest list includes individuals who can use the information in a patient case. Clearly a "premium" dinner for office staff to review new surgical instrumentation would not pass this test.
Question 4511
Topic: Biology, Genetics & Bone Healing
Figure 11 shows the radiograph of a 2-year-old child with marked genu varum and tibial bowing. Based on these findings, what is the best initial course of action?
Correct Answer & Explanation
. Obtain serum phosphorous, calcium, and alkaline phosphatase levels.
Explanation
The radiograph shows multiple wide physes, consistent with a diagnosis of rickets. A low serum phosphorous level and an elevated alkaline phosphatase level are the hallmarks in diagnosing familial hypophosphatemic Vitamin D-resistant rickets. Serum calcium is usually normal or low normal. This disease is inherited as an X-linked dominant trait and usually presents at age 18 to 24 months. The disease results from a poorly defined problem with renal phosphate transport in which normal dietary intake of vitamin D is insufficient to achieve normal bone mineralization. Renal tubular dysfunction is associated with urinary phosphate wasting. Treatment involves oral phosphate supplementation, which can cause hypocalcemia and secondary hyperparathyroidism. To prevent associated problems, high doses of Vitamin D are administered. While obtaining a scanogram may be clinically indicated in an associated limb-length discrepancy, and subsequent corrective surgery may be indicated, either of these choices would not be the first course of action. An orthosis may slow the progression of genu varum in this disorder but is less important than establishing the correct diagnosis to begin pharmacologic treatment. This amount of varum and tibial bowing far exceeds the normal limits of physiologic genu varum. Skeletal dysplasias usually are not associated with abnormal laboratory values. Herring JA: Metabolic and endocrine bone diseases, in Tachdjian's Pediatric Orthopaedics, ed 3. New York, NY, WB Saunders, 2002, pp 1685-1743.
Question 4512
Topic: Biomechanics & Biomaterials
Why is tendon considered an anisotropic material?
Correct Answer & Explanation
. Intrinsic mechanical properties vary depending on the direction of loading.
Explanation
Anisotropic materials have mechanical properties that vary based on the direction of loading. The relative values of Young's modulus for tendon, ligament, and bone are not relevant to isotropy. The mechanical properties of tendon do change with preconditioning, but this change is related to viscoelasticity. The intrinsic mechanical properties of tendon do vary with the rate of loading, but this variance is related to viscoelasticity. Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science: Biology and Biomechanics of the Musculoskeletal System, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 134-180.
Question 4513
Topic: 1. General Principles & Basic Science
Examination of a 12-year-old girl with bilateral anterior knee pain reveals excessive femoral anteversion and excessive external tibial torsion. The patient has no patellofemoral instability. Nonsurgical management consisting of muscle strengthening and nonsteroidal medication has failed to relieve the patient's pain. Treatment should now consist of
Correct Answer & Explanation
. corrective osteotomies with internal rotation of the distal part of the tibia and/or external rotation of the femur.
Explanation
Children with symptomatic severe torsional malalignment of the lower extremity and patellofemoral pathology show excessive femoral anteversion and external tibial torsion on physical examination and analysis of gait. The functional effect of this torsional malalignment is centered about the knee joint. If nonsurgical management fails to alleviate patellofemoral pain, definitive surgical treatment should consist of corrective osteotomies, including internal rotation of the distal part of the tibia or external rotation of the femur, or both. Patients with surgical correction by osteotomy show an improved gait pattern and appearance of the extremity and a marked decrease in knee pain. External rotation of the distal part of the tibia or internal rotation of the distal part of the femur worsens the torsional malalignment. No additional soft-tissue realignment procedures, including retinacular release or patellar realignment, are required.
Question 4514
Topic: 1. General Principles & Basic Science
A patient with degenerative osteoarthritis of the sternoclavicular (SC) joint reports constant pain, discomfort, and marked prominence and instability of the SC joint following medial clavicle resection. Which of the following procedures is most likely to produce these signs and symptoms?
Correct Answer & Explanation
. Excision medial to the costoclavicular ligament
Explanation
Medial clavicle excision alone can be associated with postoperative instability of the clavicle. The clavicle should be stabilized to the first rib by reconstructing the costoclavicular ligament if it is torn or if the resection is lateral to its clavicular insertion. Therefore, care must be taken to resect only that part of the clavicle that is medial to the costoclavicular ligament. Adequate protection for vital structures that lie posterior to the medial end of the clavicle must be provided. Bremner RA: Nonarticular noninfected subacute arthritis of the sternoclavicular joint. J Bone Joint Surg Br 1959;41:749-753.
Question 4515
Topic: Surgical Anatomy & Approaches
Injury to which of the following structures has been reported following iliac crest bone graft harvest?
Correct Answer & Explanation
. Lateral femoral cutaneous nerve from an anterior crest harvest
Explanation
Injury to the lateral femoral cutaneous nerve and the ilioinguinal nerve have both been described with an anterior iliac crest bone graft harvest. The lateral femoral cutaneous nerve may be injured from retraction after elevating the iliacus muscle or from direct injury when the nerve actually courses over the crest. A posterior crest harvest can injure the superior gluteal artery if a surgical instrument violates the sciatic notch. Injury to the inferior gluteal artery has not been described; it leaves the pelvis below the piriformis muscle belly and should not be at risk even with a violation of the sciatic notch. Injury to the ilioinguinal nerve has been reported from vigorous retraction of the iliacus muscle after exposing the inner table of the anterior ilium. Cluneal nerve injury may occur with posterior crest harvest, particularly if the skin incision is horizontal or extends more than 8 cm superolateral from the posterior superior iliac spine. Kurz LT, Garfin SR, Booth RE Jr: Iliac bone grafting: Techniques and complications of harvesting, in Garfin SR (ed): Complications of Spine Surgery. Baltimore, MD, Williams and Wilkins, 1989, pp 323-341.
Question 4516
Topic: Infection, Pharmacology & VTE
A 5-year-old girl has had a low-grade fever, right hip and buttock pain, and a right-sided limp for the past 5 days. Examination shows diffuse tenderness and extreme pain on range of motion of the hip. Laboratory studies show a peripheral WBC count of 13,500/mm3 and an erythrocyte sedimentation rate of 55 mm/h. A radiograph is shown in Figure 46a, and an axial postgadolinium T1-weighted MRI scan with fat suppression and an axial T2-weighted fast spin echo MRI scan are shown in Figures 46b and 46c. What is the most likely diagnosis?
Correct Answer & Explanation
. Acute osteomyelitis of the pelvis
Explanation
MRI findings of acute osteomyelitis include a decrease in the normally high signal intensity of bone marrow on T1-weighted imaging; however, a postgadolinium T1-weighted image with fat suppression will show osteomyelitis as a bright marrow signal compared to the surrounding fat. Osteomyelitis is also brighter than normal fat on T2-weighted imaging. There is no rim-enhancing lesion suggesting an abscess, although myositis is seen in the obturator internus and short external rotators. The clinical scenario and imaging studies do not support the diagnosis of septic hip, eosinophilic granuloma, or pelvic fracture. Dormans JP, Drummond DS: Pediatric hematogenous osteomyelitis: New trends in presentation, diagnosis and treatment. J Am Acad Orthop Surg 1994;2:333-341.
Question 4517
Topic: 1. General Principles & Basic Science
Etanercept is a recombinant genetically engineered fusion protein used to treat rheumatoid arthritis. What is its mode of action?
Correct Answer & Explanation
. Soluble receptor that binds TNF-a
Explanation
Etanercept is a molecule consisting of the Fc portion of IgG fused to the extracellular domain of the p76 human THF-a receptor. It is soluble and binds TNF-a. Infliximab is the monoclonal antibody that binds TNF-a. IL-1 receptor antagonists are still in development. Leflunomide is a drug that inhibits pyrimidine synthesis and is similar to methotrexate as an antimetabolite.
Question 4518
Topic: Infection, Pharmacology & VTE
A 10-year-old boy who has had progressive low back and right buttock pain for the past 3 days is now unable to bear weight on the right side secondary to pain. He has a temperature of 101.3 degrees F (38.5 degrees C). Examination reveals full hip range of motion; but he reports pain on the right side with external rotation. Pain is elicited with compression of the iliac wings and with direct palpation of the right sacroiliac (SI) joint. An MRI scan of the pelvis shows no abscess, but there is inflammation of the SI joint. Management should consist of
Correct Answer & Explanation
. bed rest, blood cultures, and IV antibiotics.
Explanation
The clinical presentation and MRI findings are consistent with an acute infection of the SI joint. Bed rest and nonsteroidal anti-inflammatory drugs alone are insufficient to treat the problem. Staphylococcus aureus is the causative organism in most of these infections; therefore, unless there is an unusual factor in the history such as IV drug use, immune system compromise, or unusual travel, SI joint aspiration is unnecessary. It is often difficult to enter the SI joint, even under radiographic guidance. Management should consist of hospital admission and IV antibiotics. Blood cultures may be positive and should be obtained prior to starting antibiotics. Surgical fusion of the SI joint is not indicated. Morrissey RT: Bone and Joint Sepsis in Pediatric Orthopaedics. Philadelphia, PA, JB Lippincott, 1990. Beaupre A, Carroll N: The three syndromes of iliac osteomyelitis in children. J Bone Joint Surg Am 1979;61:1087-1092.
Question 4519
Topic: 1. General Principles & Basic Science
Figure 53 shows the pedigree of a family with an unusual type of muscular dystrophy. This pedigree is most consistent with what type of inheritance pattern?
Correct Answer & Explanation
. X-linked recessive
Explanation
The pedigree documents involvement of male offspring only, and it also shows transmission through an uninvolved female carrier. This inheritance pattern is most consistent with a x-linked recessive inheritance. It would be inconsistent with a dominant inheritance pattern unless there was incomplete penetrance. Autosomal-recessive inheritance would be possible only if the family member labeled II.F was also a carrier of the same gene; however, this is unlikely. Mitochondrial inheritance is possible, but as with autosomal patterns, mitochondrial inheritance normally affects both male and female offspring. It is transmitted only through the maternal line.
Question 4520
Topic: Biomechanics & Biomaterials
A 45-year-old man has severe pain in both feet after his boots become wet while hunting. Examination 3 hours after the onset of symptoms reveals that his feet are cold to touch and the skin appears blanched. Management should consist of
Correct Answer & Explanation
. rapid rewarming in a footbath at 104.0 degrees F to 107.6 degrees F (40 degrees C to 42 degrees C).
Explanation
The patient has frostbite involving both feet. Rapid rewarming in a protected environment is the initial treatment. A footbath with water at 104.0 degrees F to 107.6 degrees F (40 degrees C to 42 degrees C) is ideal. This facilitates a uniform rewarming of the involved tissue. The other choices are less than ideal. Appliances such as heating pads provide uneven heating and may actually burn the skin. Pinzur MS: Frostbite: Prevention and treatment. Biomechanics 1997;4:14-21.
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