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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 116 of 326

This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 2301

Topic: 3. Adult Reconstruction (Hip & Knee)

Figure 44 shows the radiograph of a 65-year-old man who underwent a revision arthroplasty to remove a loose, cemented femoral stem. When planning the postoperative restrictions, the surgeon should be aware that

Hip & Knee Reconstruction 2007 Practice Questions: Set 3 (Solved) - Figure 19

. the approach used reduces the torque-to-failure (fracture) of the construct to less than 50% of the intact femur.
. the technique of repair can return the reconstructed prosthesis/bone composite to nearly the strength of the intact femur.
. there is no relationship between the density of the native bone and the strength of the prosthesis/bone composite.
. the addition of bone graft substitute or autograft has been shown to lessen the time to complete healing.
. there is a one in five chance of fracture with this technique; therefore, the surgeon must carefully weigh the potential benefits versus this risk.

Correct Answer & Explanation

. the approach used reduces the torque-to-failure (fracture) of the construct to less than 50% of the intact femur.

Explanation

The transfemoral approach, also known as the extended trochanteric osteotomy, is an important technique to master for revision hip surgery. When performed correctly, it allows excellent exposure of the femoral canal and aids in exposure of the acetabulum. As demonstrated in the study cited, however, it markedly reduces the torque that the composite can withstand without failure. This type of basic science study is important to guide postoperative rehabilitation.

Question 2302

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man with no significant medical history underwent a total knee arthroplasty 4 years ago. A radiograph is shown in Figure 55. He reports that he had no problems with the knee until 6 weeks ago when he noted the gradual onset of pain following a colonoscopy. Examination reveals a painful, swollen knee. Knee aspiration reveals a WBC count of 40,000/mm3. Management should consist of

Hip & Knee Reconstruction Board Review 2007: High-Yield MCQs (Set 4) - Figure 14

. suppressive antibiotics.
. open irrigation and debridement with polyethylene exchange.
. one-stage resection arthroplasty and reimplantation.
. two-stage resection arthroplasty and reimplantation.
. arthroscopic irrigation and debridement.

Correct Answer & Explanation

. two-stage resection arthroplasty and reimplantation.

Explanation

The treatment of choice for a late hematogenous infection is two-stage resection arthroplasty and reimplantation, with parenteral antibiotics prior to reimplantation. This is particularly true when septic loosening has occurred as in this patient. Open irrigation and debridement with polyethylene exchange has been used successfully when the duration of symptoms is 3 weeks or less. Long-term suppressive antibiotics are most commonly used when the patient's medical condition precludes further surgery. Delayed reimplantation has been shown to be superior to immediate reimplantation in multiple studies. Little data support the use of arthroscopic irrigation and debridement. Swanson KC, Windsor RE: Diagnosis of infection after total knee arthroplasty, in Callaghan JJ, Rosenberg AG, Rubash HE, et al (eds): The Adult Knee. Philadelphia, PA, JB Lippincott, 2003, vol 2, pp 1485-1491.

Question 2303

Topic: 3. Adult Reconstruction (Hip & Knee)

A 59-year-old woman who underwent a total hip arthroplasty 5 years ago now has recurrent dislocation following bariatric surgery and a weight loss of 200 lb. An attempt at converting to a larger head size and trochanteric advancement has failed. Her components are well aligned. What is the best course of action?

Hip & Knee Reconstruction Board Review 2007: High-Yield MCQs (Set 2) - Figure 1

. Resection arthroplasty
. Hip abduction brace
. Constrained acetabular liner
. Thermal ablation of the posterior capsule
. Conversion to a bipolar prosthesis

Correct Answer & Explanation

. Constrained acetabular liner

Explanation

When a patient has well-aligned components and soft-tissue tensioning with a larger femoral head and trochanteric advancement has failed, options are limited. The use of a constrained acetabular liner is the best option in this situation. Goetz and associates and Shrader and associates have demonstrated good results with these implants. Shrader used this device on 109 patients with recurrent instability with a successful outcome in all but 2 patients. Resection arthroplasty is a salvage situation and is not the best option at the present time. A hip abduction brace does not address the soft-tissue laxity. Conversion to a bipolar arthroplasty, although possibly minimizing the incidence of dislocation, will lead to groin pain and migration of the component with diminished functional results. Goetz DD, Capello WN, Callaghan JJ, et al: Salvage of recurrently dislocating hip prosthesis with use of a constrained acetabular component: A retrospective analysis of fifty-six cases. J Bone Joint Surg Am 1998;80:502-509. Shrader MW, Parvizi J, Lewallen DG: The use of constrained acetabular component to treat instability after total hip arthroplasty. J Bone Joint Surg Am 2003;85:2179-2183.

Question 2304

Topic: 3. Adult Reconstruction (Hip & Knee)

A 9-year-old girl has pain over the fifth toe that is aggravated by shoe wear. Clinical photographs are shown in Figures 28a and 28b. Treatment of this deformity should consist of

. extensor digitorum longus tenotomy.
. extensor digitorum longus tenotomy with dorsal fifth metatarsophalangeal (MTP) joint capsulotomy.
. dorsal V-Y plasty for skin contracture, combined with extensor digitorum longus tenotomy and dorsal fifth MTP capsulotomy.
. a dorsal and plantar racquet-shaped incision around the fifth toe, combined with extensor digitorum longus tenotomy and circumferential fifth MTP joint release (Butler procedure).
. plantar proximal phalangeal resection.

Correct Answer & Explanation

. a dorsal and plantar racquet-shaped incision around the fifth toe, combined with extensor digitorum longus tenotomy and circumferential fifth MTP joint release (Butler procedure).

Explanation

The major obstacle to overcome in the surgical treatment of this cock-up deformity is recurrence. Dorsal releases can be performed; however, chronic dislocation of the fifth MTP joint usually needs to be addressed with plantar release as well. Chronic dorsal soft-tissue contractures may be overcome with translation of the toe into a plantar-based incision, as described originally by Cockin and accredited to Butler. This is the treatment of choice. Resection of the proximal phalanx improves symptoms but induces a secondary deformity; this procedure is usually reserved for skeletally mature individuals. Black GB, Grogan DP, Bobechko WP: Butler arthroplasty for correction of adducted fifth toe: A retrospective study of 36 operations between 1968 and 1982. J Pediatr Orthop 1985;5:439-441. Paton RW: V-Y plasty for correction of varus fifth toe. J Pediatr Orthop 1990;10:248-249.

Question 2305

Topic: Total Hip Arthroplasty (THA)

Which of the following factors is most closely associated with early postoperative migration of "stand-alone" lumbar interbody fusion cages?

Spine Surgery 2006 Practice Questions: Set 1 (Solved) - Figure 29

. Pseudarthrosis
. Placement of the cage through a posterior approach
. Placement of the cage laparoscopically through an anterior approach
. Use of tapered rather than cylindrical cages
. Use of BMP-2 rather than autograft in the cage

Correct Answer & Explanation

. Placement of the cage through a posterior approach

Explanation

Postoperative migration of lumbar interbody fusion cages is a rare complication. It is most commonly seen after placement of the cages through a posterior approach, with instability of the final construct. It is not associated with the design of the cage, the type of graft used, or a resultant pseudarthrosis. McAfee PC: Interbody fusion cages in reconstructive operations on the spine. J Bone Joint Surg Am 1999;81:859-880.

Question 2306

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with a documented allergy to nickel requires a total knee arthroplasty. Which of the following prostheses is most likely to provide long-term success in this individual?

. All-polyethylene tibial component and pure titanium femoral component
. All-polyethylene tibial component and cobalt-chromium alloy femoral component
. Cobalt-chromium alloy tibial component and cobalt-chromium alloy femoral component
. Modular titanium tibial component and pure titanium femoral component
. Modular titanium tibial component and oxidized zirconium femoral component

Correct Answer & Explanation

. Modular titanium tibial component and oxidized zirconium femoral component

Explanation

Nickel allergy is not an infrequent preoperative finding. The ramifications of such allergies in arthroplasty patients are poorly understood at this time. Stainless steel and cobalt-chromium alloys contain relatively high concentrations of nickel. Titanium, oxidized zirconium, and polyethylene do not contain significant amounts of nickel. Titanium is not a good surface for the articulating portion of the femoral component because of its propensity for metallosis. Oxidized zirconium is the only suitable femoral component for patients allergic to nickel. A modular titanium tibial component or an all-polyethylene tibial component would be satisfactory for these patients. Laskin RS: An oxidized Zr ceramic surfaced femoral component for total knee arthroplasty. Clin Orthop 2003;416:191-196.

Question 2307

Topic: 3. Adult Reconstruction (Hip & Knee)

A healthy 70-year-old man has a swollen knee after undergoing a knee replacement 10 years ago. Aspiration of the knee reveals cloudy, viscous synovial fluid. Laboratory studies show an erythrocyte sedimentation rate of 10 mm/h and a C-reactive protein level of less than 0.5. What is the most likely diagnosis?

. Infected total knee arthroplasty
. Polyethylene wear-related synovitis
. Rheumatoid arthritis synovitis
. Gout
. Tibial component loosening

Correct Answer & Explanation

. Polyethylene wear-related synovitis

Explanation

Polyethylene wear debris can result in significant synovitis and subsequent cloudy appearing synovial fluid. Typically, laboratory studies show a WBC of less than 30,000/mm3 no left shift. Cytologic examination can reveal intra-articular polyethylene particles. Infected total knee arthroplasty is extremely uncommon in a healthy, immune-competent patient who has a normal preoperative erythrocyte sedimentation rate and C-reactive protein level.

Question 2308

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old woman has had progressive right shoulder pain for the past 6 months. She notes that the pain disrupts her sleep, she has pain at rest that requires the use of narcotic analgesics, and she has limited use of her left shoulder for most activities of daily living. History reveals the use of corticosteroids for systemic lupus erythematosus. Examination shows diminished range of motion. Radiographs of the right shoulder are shown in Figures 4a and 4b. Treatment should consist of

. core decompression of the humeral head.
. humeral arthroplasty.
. total shoulder arthroplasty.
. glenohumeral arthrodesis.
. vascularized fibular allograft.

Correct Answer & Explanation

. humeral arthroplasty.

Explanation

Humeral arthroplasty provides excellent pain relief and function for stage IV osteonecrosis with humeral collapse. In late disease with glenoid involvement (stage V), total shoulder arthroplasty is preferred. Some authors have reported satisfactory results with core decompression of the humeral head for early stages of osteonecrosis, but results for stage IV osteonecrosis are less satisfactory when compared with those for humeral arthroplasty. Cruess RL: Steroid-induced avascular necrosis of the head of the humerus: Natural history and management. J Bone Joint Surg Br 1976;58:313-317. LePorte DM, Mont MA, Mohan V, Pierre-Jacques H, Jones LC, Hungerford DS: Osteonecrosis of the humeral head treated by core decompression. Clin Orthop 1998;355:254-260.

Question 2309

Topic: 3. Adult Reconstruction (Hip & Knee)

Figure 38 shows the radiograph of a 40-year-old woman who reports severe groin pain and lack of motion of the right hip. History reveals that the patient underwent a femoral osteotomy for hip dysplasia approximately 30 years ago. Treatment should include

Hip Board Review 2001: High-Yield MCQs (Set 4) - Figure 17

. femoral osteotomy.
. periacetabular osteotomy.
. arthroscopic debridement.
. total hip arthroplasty.
. hip arthrodesis.

Correct Answer & Explanation

. total hip arthroplasty.

Explanation

Although the patient is young, a total hip arthroplasty will provide pain relief and improve her range of motion. The arthritis is too advanced for the patient to benefit from an osteotomy. In addition, periacetabular osteotomy and hip arthrodesis do not improve range of motion of the hip. It has not been established that patients with severe osteoarthritis will benefit from arthroscopic debridement of the hip.

Question 2310

Topic: 3. Adult Reconstruction (Hip & Knee)

Compared with wear rates of metal-on-standard polyethylene bearings (75 to 250 um/y), the wear rate of metal-on-metal bearings for hip arthroplasty is approximately how many micrometers per year?

. Less than 0.5
. 2 to 5
. 5 to 20
. 20 to 50
. 50 to 150

Correct Answer & Explanation

. 2 to 5

Explanation

Studies on older systems, as well as newer designs, have confirmed that metal-on-metal bearing surfaces undergo linear wear of 2 to 5 um per year. Ceramic bearing surfaces produced with recent technology perform even better, with a wear rate of 0.5 to 2.5 um per year. Clinical wear rates of metal-on-crosslinked polyethylene have not yet been determined. McKellop H, Park SH, Chiesa R, et al: In vivo wear of three types of metal on metal hip prostheses during two decades of use. Clin Orthop 1996;329:S128-S140.

Question 2311

Topic: 3. Adult Reconstruction (Hip & Knee)

A 48-year-old woman with rheumatoid arthritis reports increasing elbow pain for the past 6 months. History reveals that she underwent total elbow arthroplasty 7 years ago. A peripheral WBC count, erythrocyte sedimentation rate, and C-reactive protein studies are normal. An AP radiograph is shown in Figure 5. What is the next most appropriate step in management?

Upper Extremity 2005 Practice Questions: Set 1 (Solved) - Figure 14

. Continued observation
. Synovectomy and bushing replacement
. Reimplantation of both the humeral and ulnar components
. Conversion to a resection arthroplasty
. Conversion to elbow arthrodesis

Correct Answer & Explanation

. Synovectomy and bushing replacement

Explanation

Pain relief is excellent after total elbow arthroplasty and is comparable to the results found with hip and knee arthroplasty. The failure of total elbow arthroplasty in the treatment of rheumatoid arthritis can be the result of infection, aseptic loosening, instability, and bearing surface wear. The radiographic findings shown here are consistent with bushing wear in a linked device. The bushings can be changed before continued wear results in osteolysis and implant loosening. If the implants become loose, then reimplantation is necessary. Resection arthroplasty is not indicated if the components are well fixed. Elbow arthrodesis is not indicated in patients with rheumatoid arthritis. Gill DR, Morrey BF: The Coonrad-Morrey total elbow arthroplasty in patients who have rheumatoid arthritis: A ten to fifteen-year follow-up study. J Bone Joint Surg Am 1998;80:1327-1335.

Question 2312

Topic: 3. Adult Reconstruction (Hip & Knee)
A 58-year-old patient who underwent bilateral hip arthroplasty 12 years ago now reports pain in his hips and difficulty with ambulation to the point where he now uses crutches. A radiograph of the hip and pelvis is shown in Figure 26. What is the best treatment option for this patient?
. Revision hip arthroplasty with a bipolar implant
. Revision hip arthroplasty with impaction grafting on the femoral and acetabular side
. Revision hip arthroplasty with a cemented jumbo acetabular component
. Revision hip arthroplasty with a cementless acetabular component
. Acetabular component revision with a tri-flange protrusio ring

Correct Answer & Explanation

. Revision hip arthroplasty with a cementless acetabular component

Explanation

The radiographs reveal acetabular component failure with bone loss. There are several treatment options available. The best option for survivorship is a cementless porous-coated acetabular component. This patient may or may not require structural bone graft, which may need to be determined at the time of surgery. Bipolar implants and cemented acetabular components for revision surgery have not demonstrated long-term success. The use of a protrusio ring is reserved primarily for massive bone loss such as a Paprosky type III bone loss with significant superior migration of the acetabular component. The best clinical results for acetabular component revision have been achieved with cementless porous-coated implants.

Question 2313

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old woman reports anterior knee pain after undergoing an uncomplicated total knee arthroplasty 6 months ago. Examination reveals prepatellar tenderness, with no extensor lag. The radiographs shown in Figures 25a through 25c reveal a well-fixed patellar component. Management should consist of

. closed treatment with early motion.
. a cylindrical cast and restricted weight bearing.
. open reduction and internal fixation.
. patellar revision.
. patellectomy.

Correct Answer & Explanation

. a cylindrical cast and restricted weight bearing.

Explanation

Patellar fractures that occur after a total knee arthroplasty are usually stress fractures. Integrity of the extensor mechanism precludes the need for surgical repair or internal fixation, while stability and fixation of the patellar component determine whether revision is indicated. A cylindrical cast and full weight bearing for 6 weeks is recommended for transverse fractures with an intact extensor mechanism and a stable component. A similar fracture, if vertical, may be treated with earlier motion. Rorabeck CH, Angliss RD, Lewis PL: Fractures of the femur, tibia, and patella after total knee arthroplasty: Decision making and principles of management, in Cannon WD Jr (ed): Instructional Course Lectures 47. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1998, pp 449-458. Hozack WJ, Goll SR, Lotke PA, Rothman RH, Booth RE Jr: The treatment of patellar fractures after total knee arthroplasty. Clin Orthop 1988;236:123-127.

Question 2314

Topic: 3. Adult Reconstruction (Hip & Knee)

Figure 28 shows an AP radiograph of a 54-year-old woman who underwent lumbar laminectomy and fusion at the L4 and L5 levels with placement of a bone stimulator 8 years ago. She also underwent a left total hip arthroplasty 2 years ago; aspiration of that joint now reveals that it is infected with a gram-positive cocci organism. History is also significant for IV drug use and human immunodeficiency virus (HIV). The patient reports fever, chills, and left flank and abdominal pain. Examination reveals significant pain with resisted left hip flexion and passive hip extension. She also has lumbar hyperlordosis. Which of the following studies would best identify the underlying cause of her infection?

Anatomy 2002 Practice Questions: Set 3 (Solved) - Figure 5

. Abdominal and pelvic ultrasound
. CT of the abdomen and pelvis
. Technetium Tc 99m three-phase bone scan
. Abdominal radiographic series
. Gallium-67 citrate scan

Correct Answer & Explanation

. CT of the abdomen and pelvis

Explanation

The patient's clinical signs (fever and flank, hip, and abdominal pain) suggest a primary iliopsoas abscess. With an increased patient population who abuse drugs and/or who are HIV-positive, iliopsoas abscess may be more prevalent because of systemic bacterial seeding and may be potentially unrecognized. Diagnostic imaging studies provide a better understanding of the anatomic magnitude of the infection, give concrete confirmation of the diagnosis, and may suggest an underlying cause. Neither standard abdominal radiographs nor ultrasound studies are sensitive enough to be diagnostic of this disease process. CT has been established as the standard study for identifying the underlying cause of this abscess. The hip infection has most likely developed as a result of hematogenous spread from an infected skin lesion from the patient's IV drug use. Santaella RO, Fishman EK, Lipsett PA: Primary vs secondary iliopsoas abscess: Presentation, microbiology, and treatment. Arch Surg 1995;130:1309-1313.

Question 2315

Topic: 3. Adult Reconstruction (Hip & Knee)

During impaction of a cementless acetabular component, the posterior column was fractured and found to be displaced. Which of the following is considered the most appropriate surgical option?

. Exchange of the cementless cup to a larger component
. Retention of the component and bone grafting of the fracture
. Retention of the component and postoperative weight protection until the posterior column heals
. Removal of the cup, fixation of the posterior column, and application of an antiprotrusio cage
. Removal of the cup and cementing of an all-polyethylene liner

Correct Answer & Explanation

. Removal of the cup, fixation of the posterior column, and application of an antiprotrusio cage

Explanation

Acetabular bone loss presents a challenge during reconstruction. A cementless hemispherical cup can be used in most patients provided that the acetabular rim, particularly the posterior column, is intact. When the posterior column is disrupted, fixation with a reconstruction plate and/or the use of an antiprotrusio cage is recommended. The latter is particularly important when the posterior column is fractured and displaced, such as in this patient. Under these circumstances, reduction of the fracture and application of an antiprotrusio cage is recommended. In this particular type of case, some surgeons may elect to retain the hemispherical cup and apply an antiprotrusio cage over the cup ("cage over cup" technique). Berry DJ: Antiprotrusio cages for acetabular revision. Clin Orthop 2004;420:106-112.

Question 2316

Topic: Total Hip Arthroplasty (THA)

One of the serious potential complications of repair of distal biceps tendon ruptures is limited pronation and supination as a result of synostosis. What surgical approach and technique presents the highest risk for development of this complication?

Upper Extremity 2005 Practice Questions: Set 1 (Solved) - Figure 8

. Single incision, anterior approach with fixation through drill holes in the radius
. Single incision, anterior approach with suture anchor fixation to the radius
. Single incision, anterior approach through a drill hole in the radius with sutures tied over bolster or button on the posterior forearm
. Dual incision, limited anterior and posterior approach along the ulna with attachment through drill holes
. Dual incision, limited anterior and posterior muscle-splitting approach (supinator and extensor muscles) with attachment through drill holes

Correct Answer & Explanation

. Dual incision, limited anterior and posterior muscle-splitting approach (supinator and extensor muscles) with attachment through drill holes

Explanation

The risk of synostosis is imminent with any technique for repairing a distal biceps tendon rupture. However, the risk is quite low for all approaches that avoid exposure of the ulna, including the muscle-splitting two-incision technique.

Question 2317

Topic: 3. Adult Reconstruction (Hip & Knee)

A follow-up examination of a patient 6 weeks after knee surgery reveals a range of motion from 5 degrees to 55 degrees of flexion. Which of the following statements best summarizes the role of manipulation under anesthesia for this patient?

. Manipulation under anesthesia offers the best chance of improving and maintaining the patient's range of motion.
. The gains from manipulation under anesthesia are only temporary and rarely last more than 6 months.
. Increasing the frequency and intensity of physical therapy over the next 2 months will have the same effect as manipulation under anesthesia.
. The risks of fracture are so great from manipulating a knee that the patient should be advised to live with a limited range of motion.
. The patient's final result will be poor with or without manipulation.

Correct Answer & Explanation

. Manipulation under anesthesia offers the best chance of improving and maintaining the patient's range of motion.

Explanation

Esler and associates evaluated the use of manipulation under anesthesia in 47 knees. Manipulation was considered when intensive physical therapy failed to increase flexion to more than 80 degrees. The mean time from arthroplasty to manipulation was 11.3 weeks, and the mean active flexion before manipulation was 62 degrees. One year later, the mean gain was 33 degrees. Definite sustained gains in flexion were achieved even when manipulation was performed 4 or more months after arthroplasty. An additional 21 patients who met the criteria for manipulation declined the procedure, and despite continued physical therapy, they showed no significant increase in knee flexion.

Question 2318

Topic: 3. Adult Reconstruction (Hip & Knee)

The insurance carrier of a patient who underwent total knee arthroplasty 4 days ago is now demanding that the patient be discharged from the hospital. However, examination reveals that the patient has a range of motion of only 10 degrees to 55 degrees, and the patient is concerned whether she will ever move her knee normally. The insurance company representative should be advised that

. discharge at this time may result in loss of motion and the necessity of manipulation under anesthesia.
. the insurance company has no right to make such demands on the surgeon or the patient.
. if the patient is discharged and fails to regain full motion, she will most likely file a suit against the insurance company.
. the patient will require a follow-up examination in 6 weeks to evaluate her progress.
. the patient will be given an extra set of exercises to perform at home.

Correct Answer & Explanation

. discharge at this time may result in loss of motion and the necessity of manipulation under anesthesia.

Explanation

Examination findings that show flexion of only 55 degrees at discharge should alert the surgeon that the patient will require close scrutiny and follow-up. Mauerhan and associates examined the records of 745 patients who had a primary total knee arthroplasty from 1993 to 1996. At their institution, development and implementation of clinical pathways resulted in a significant decrease in the average length of stay, beginning in 1993 with 6.4 days +/- 1.8 days and progressively decreasing to 4.4 days +/- 1.0 days in 1996. The rate of manipulation (patients manipulated at 6 weeks/total number of patients receiving total knee arthroplasty) was 6.0% in 1993, 11.3% in 1994, 13.5% in 1995, and 12.0% in 1996. In the period of 1993 to 1996, patients requiring manipulation consistently had a lower range of motion of 69.0 degrees +/- 10 degrees at the time of discharge compared with patients not requiring manipulation who had a range of motion of 80.7 degrees +/- 10.6 degrees. In this era of outpatient services, however, another solution would be to arrange for outpatient physical therapy on a more frequent basis and to see the patient more frequently in the office until an acceptable range of motion is established.

Question 2319

Topic: 3. Adult Reconstruction (Hip & Knee)

A 52-year-old man has had groin and deep buttock pain for the past 2 months. Examination reveals that hip range of motion is mildly restricted, and he has pain with both weight bearing and at rest. An MRI scan is shown in Figure 28. Management should consist of

Hip Board Review 2004: High-Yield MCQs (Set 4) - Figure 10

. protected weight bearing and anti-inflammatory drugs.
. core decompression of the femoral head.
. vascularized free fibular grafting to the femoral head.
. bipolar hemiarthroplasty of the hip.
. total hip arthroplasty.

Correct Answer & Explanation

. protected weight bearing and anti-inflammatory drugs.

Explanation

The MRI findings show highly increased signal through the entire femoral head and neck that is diagnostic of transient osteoporosis of the femoral head. This recently described entity is often seen in middle-aged men and should be treated nonsurgically with protected weight bearing and anti-inflammatory drugs. The natural history is that of self-resolution. Guerra JJ, Steinberg ME: Distinguishing transient osteoporosis from avascular necrosis of the hip. J Bone Joint Surg Am 1995;77:616-624.

Question 2320

Topic: 3. Adult Reconstruction (Hip & Knee)

In designing a cementless femoral stem for a total hip arthroplasty, the manufacturer utilizes a porous coating. What pore size range is optimal for reliable biological bone ingrowth?

. 10-50 micrometers
. 50-400 micrometers
. 400-800 micrometers
. 800-1200 micrometers
. >1200 micrometers

Correct Answer & Explanation

. 50-400 micrometers

Explanation

The optimal pore size for biological bone ingrowth in cementless arthroplasty implants is generally between 50 and 400 micrometers. Pores smaller than 50 ยตm are too small for osteons and lead predominantly to fibrous tissue ingrowth, whereas pores larger than 400 ยตm decrease the structural integrity of the coating and increase the risk of micromotion.

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