ORTHOPEDICS HYPERGUIDE MCQ 151-200

151. (1708) Q1-2104: Cyclooxygenase (Cox-1) is found:

1) Only in the gastrointestinal tract

3) Only in the platelets

2) Only in the kidneys

5) Widely expressed throughout the body

4) Only in the articular cartilage

Cox-1 is the ubiquitous form of the cyclooxygenase enzyme that is widely expressed throughout the body. Cox-1 is not found in only one specifiCorgan

■Correct Answer: Widely expressed throughout the body

152. (1709) Q1-2105:

Steroid injections work in osteoarthritiCjoints by the following mechanism:

1) Increasing phagocytes

3) Increasing synthesis of inflammatory mediators

2) Inhibiting lysosomal enzyme release

5) Stabilizing synthesis of inflammatory mediators

4) Stabilizing phagocytes

Steroids work by inhibiting lysosomal enzyme release, decreasing phagocytes, and decreasing the synthesis of inflammatory mediators

■Correct Answer: Inhibiting lysosomal enzyme release

153. (1710) Q1-2106:

Intra-articular steroids decrease the synthesis of prostaglandin and interleukin-1 by:

1) 90%

3) 30%

2) 20%

5) 70%

4) 50%

Intra-articular steroids decrease the synthesis of prostaglandin and interleukin-1 by as much as 50%

■Correct Answer: 50%

154. (1711) Q1-2107:

Intra-articular steroids change synovial fluid characteristincs by:

1) Stabilizing phagocytes

3) Increasing the hyaluroniCacid concentration in a joint

2) Stabilizing synthesis of inflammatory mediators

5) Intra-articular steroids do not change synovial fluid characteristics

4) Decreasing the hyaluroniCacid concentration in a joint

Intra-articular steroids change synovial fluid characteristics by increasing hyaluroniCacid concentration

■Correct Answer: Increasing the hyaluroniCacid concentration in a joint

155. (1712) Q1-2108:

To reduce the chance of irritation when injecting a knee with hyaluroniCacid, which of the following approaches is recommended:

1) A medial approach in a partially bent knee

3) A direct lateral injection

2) A direct straight injection

5) A direct injection through the patellar tendon

4) A medial approach in an extended knee

The chance of an injection site irritation is 5.2% with a medial approach in a partially bent knee, 2.4% with a straight injection, and 1.5% with a direct lateral approach. There is also an increased chance of irritation with a direct patellar tendon injection

■Correct Answer: A direct lateral injection

156. (1713) Q1-2109:

Indications for high tibial osteotomy include all of the following except:

1) 10° to 15° of varus deformity on weight-bearing radiographs

3) Flexion contracture less than 15°

2) 90° preoperative range of motion

5) Age younger than 60 years

4) 60° preoperative range of motion

Indications for a high tibial osteotomy include age younger than 60 years, 10° to 15° varus deformity, 90° preoperative arCrange of motion, and flexion contracture less than 15°

■Correct Answer: 60° preoperative range of motion

157. (1714) Q1-2110:

Contraindications to high tibial osteotomy include:

1) Lateral compartment narrowing

3) Medial compartment bone loss of more than 3 mm

2) Lateral tibial subluxation more than 1 cm

5) All of the above

4) Ligament instability

Lateral compartment narrowing, lateral tibial subluxation of more than 1 cm, medial compartment bone loss of more than 3 mm, and ligament instability are contraindications to high tibial osteotomy

■Correct Answer: All of the above

158. (1715) Q1-2111:

The incidence of lateral gonarthrosis in women is:

1) Lower than men

3) Two times higher in women

2) Same as men

5) Five times higher in women

4) Three times higher in women

The incidence of primary lateral gonarthrosis in women is five times higher than in men, and the average age of patients is 55 to

60 years. The body habitus of women tend to align more weight on the lateral compartment when compared to men.Correct

Answer: Five times higher in women

159. (1716) Q1-2112:

The majority of patients with lateral compartment arthritis have:

1) Rheumatoid arthritis

3) Collagen vascular disease

2) NeurologiCcondition (e.g., Polio)

5) Trauma

4) Osteoarthritis

Rheumatoid arthritis usually involves the lateral compartment because it is a bicompartmental disease. Although most patients with osteoarthritis have medial compartment arthritis, they still have a significant higher incidence of lateral arthritis than any other disease. The incidence of lateral compartment arthritis is lower in trauma, collagen vascular disease, or patients with neurologiCconditions like polio

■Correct Answer: Osteoarthritis

160. (1717) Q1-2113:

Which of the following is not a good indication for a varus-producing supracondylar femoral osteotomy (SFO):

1) Valgus deformity less than 15°

3) 90° arCof range of motion

2) Valgus joint-line tilt more than 10°

5) Young patients

4) Old patients

Varus producing supracondylar femoral osteotomy is indicated for a valgus deformity less than 15°, valgus joint line tilt more than 10° in a patient with at least a 90° arCof motion. The procedure is also best indicated in stout, young patients who are involved in heavy labor jobs

■Correct Answer: Old patients

161. (1718) Q1-2114:

When performing a supracondylar femoral osteotomy, it is recommended to correct the tibiofemoral angle:

1) 2°

3) 4° to 6°

2) 2° to 4°

5) More than 8°

4) 6° to 8°

Correcting the tibiofemoral angle between 4° to 6° transfers 80% of the weight to the medial angle

■Correct Answer: 4° to 6°

162. (1719) Q1-2115:

The most common problem encountered with total knee arthroplasty (TKA) after high tibial osteotomy is:

1) Offset of tibial plateau from tibial shaft

3) Dealing with skin incision

2) Patella infera

5) High riding patella

4) Tracking of patella

Patella infera is encountered 80% of the time after a high tibial osteotomy. Patella infera makes it difficult for a surgeon to visualize and dislocate the patella laterally, and it also makes for a difficult salvage for a total knee replacement

■Correct Answer: Patella infera

163. (1720) Q1-2116:

When careful evaluation after primary total knee arthroplasty (TKA) is performed, the results of TKA after previous high tibial osteotomy (HTO) have a Knee Society good-to-excellent score what percentage of the time:

1) 20%

3) 60%

2) 40%

5) 90%

4) 80%

Primary TKA with respect to Knee Society scores and operative complications shows that a primary TKA group scored 88% good to excellent results compared to 63% for the post-HTO group

■Correct Answer: 60%

164. (1721) Q1-2117:

Subchondral drilling for cartilage defects is effective for:

1) Varus alignment

3) Subchondral sclerosis

2) Valgus alignment

5) Rheumatoid arthritis

4) Fibrocartilage formation

Subchondral drilling allows the blood supply to form clot-containing stem cells from which fibrocartilage forms. It is not indicated in patients with systemiCdisease like rheumatoid arthritis. It is ineffective for varus or valgus alignment or subchondral sclerosis

■Correct Answer: Fibrocartilage formation

165. (1722) Q1-2118:

When performing a mosaicplasty for cartilage defects, the defects must be:

1) Less than 1 cm

3) Less than 2 cm

2) Less than 1.5 cm

5) Less than 3 cm

4) Less than 2.5 cm

When performing a mosaicplasty for cartilage defects, the best results are obtained with defects less than 2 cm. The plugs should measure 2.5 mm in length. Mosaicplasty results for defects larger than 2 cm have not been as gratifying

■Correct Answer: Less than 2 cm

166. (1723) Q1-2119:

Mobile-bearing total knee replacement (TKR) implants are designed to have how many articulations:

1) 0

3) 2

2) 1

5) 4

4) 3

Mobile-bearing TKR implants are designed to have two articulations, one between the femoral and tibial component and the other between the tibial component and base plate on the tibia

■Correct Answer: 2

167. (1724) Q1-2120:

After 5 years, cemented all-polyethylene components in total knee replacement have a loosening rate of:

1) 10%

3) 30%

2) 20%

5) 50%

4) 40%

At 5 years, cemented all-polyethylene tibial components in total knee replacement have a loosening rate of 20%. A loosening rate of 20% is unacceptable, therefore, cemented all-polyethylene tibial components are no longer used in total knee replacements. New all poly tibial components are presently being investigated, but not for general use presently

■Correct Answer: 20%

168. (1725) Q1-2121:

When performing a total knee replacement (TKR) on a patient with previous skin incisions on the knee, if a different skin incision is to be made it is recommended that the distance between the incisions should be:

1) 2 cm

3) 4 cm

2) 3 cm

5) 7 cm

4) 5 cm

Most authors recommend a 7-cm distance between skin incisions. If the distance between the incisions is less than 7 cm, then the chance of skin slough increases

■Correct Answer: 7 cm

169. (1726) Q1-2122:

The medial parapatellar skin incision for total knee replacement (TKR):

1) Limits lateral side exposure and interferes with the blood supply of the lateral skin flap

3) Makes the lateral skin flap smaller

2) Necessitates a lateral release

5) Provides excellent exposure for a TKR

4) Increases the blood supply to the patella

The medial parapatellar skin incision limits exposure of the lateral compartment and interferes with the blood supply of the lateral skin flap

■Correct Answer: Limits lateral side exposure and interferes with the blood supply of the lateral skin flap

170. (1727) Q1-2123:

Which of the following is not true regarding a subvastus arthrotomy for total knee replacement (TKR):

1) A lift of the entire quadriceps mechanism

3) A danger of causing injury to the femoral artery

2) A poor exposure of the lateral aspect of the knee joint

5) Provides good visualization in an obese patient

4) Provides fair exposure in a thin patient

All of the answers are associated with the subvastus arthrotomy. A subvastus arthrotomy is a particularly difficult approach in obtaining visualization in an obese patient

■Correct Answer: Provides good visualization in an obese patient

171. (1728) Q1-2124:

Which of the following is a true statement concerning the quadriceps snip technique:

1) The quadriceps snip technique involves lengthening the tendon in a

3) The quadriceps snip technique significantly weakens the extensor tendon.

2) The quadriceps snip technique enters the quadriceps tendon with a

5) The quadriceps snip technique involves a horizontal cut in the extensor tendon.

4) The quadriceps snip technique permits extended exposure.

The quadriceps snip technique entails dividing the tendon proximally in an oblique fashion to permit extended exposure.Correct

Answer: The quadriceps snip technique permits extended exposure.

172. (1729) Q1-2125:

Which of the following is a true statement regarding intramedullary instrumentation when performing bone cuts in total knee replacement (TKR):

1) Intramedullary instrumentation is equally as accurate as extramedullary devices in all knees.

3) Intramedullary instrumentation is less accurate than extramedullary devices in valgus knees.

2) Intramedullary instrumentation is less accurate than extramedullary devices in varus knees.

5) Intramedullary instrumentation is more accurate than extramedullary devices in valgus knees.

4) Intramedullary instrumentation is more accurate than extramedullary devices in varus knees.

Valgus in the tibia shaft may be up to 70%, and intramedullary rods cannot be fully placed into the tibia. Extramedullary techniques are recommended

■Correct Answer: Intramedullary instrumentation is less accurate than extramedullary devices in valgus knees.

173. (1730) Q1-2126:

When total knee replacement surgery is complete, the alignment of the knee must be:

1) Neutral

3) 5° of valgus in the femur

2) 2° of valgus in the tibia

5) 7° of valgus in the femur

4) 7° of valgus in the tibia

The tibial cut is perpendicular to the tibial axis, the femoral cut is made in 4° to 6° valgus, and the knee aligned in 4° to 6° of valgus provided the ligaments are balanced

■Correct Answer: 5° of valgus in the femur

174. (1731) Q1-2127:

Overall objectives in total knee replacement (TKR) should include all of the following except:

1) Valgus aligned knee

3) Midline tracking patella

2) Range of motion 0° to 125°

5) Neutral aligned knee

4) Collateral ligament balance at full extension and 90°

To have a satisfactory alignment one should have a valgus aligned knee, not a neutral aligned knee. Range of motion should be

0° to 125° with midline tracking patella. The collateral ligament should be balanced at full extension an 90°

■Correct Answer: Neutral aligned knee

175. (1732) Q1-2128:

What is the measured resection technique when performing a total knee replacement:

1) Removes 20% more bone than cut

3) Entails ligament balancing in extension

2) Removes an exact amount of bone to fit in the prosthetiCdevice

5) Incorporates ligament balancing in flexion and extension

4) Entails ligament balancing in flexion

The measured resection technique is a philosophy that removes the exact amount of bone necessary to fit in the prosthetiCdevice for the femur and tibia, and does not detail ligament balancing. The flexion-extension gap technique incorporates ligament balancing with the bony cuts that give equal flexion and extension gaps

■Correct Answer: Removes an exact amount of bone to fit in the prosthetiCdevice

176. (1733) Q1-2129:

When performing a total knee replacement, if you discover that the gap in flexion is larger than the gap in full extension, you should:

1) Remove more bone from the tibia

3) Remove more bone from the femur in extension

2) Remove more bone from the femur in flexion

5) Put in a posterior stabilized prosthesis

4) Remove more bone from the posterior femur

By removing more bone from the femur in extension and using a higher polyethylene component, the flexion and extension gaps can be equalized. If this does not correct the problem, then one should proceed to a posterior stabilized prosthesis

■Correct Answer: Remove more bone from the femur in extension

177. (1734) Q1-2130:

When performing a total knee replacement, if you discover that the gap in flexion is smaller than the gap in extension:

1) More bone should be removed from the femur in extension

3) More bone should be removed from the posterior femur

2) A larger polyehtylene component should be used

5) A smaller polyethylene component should be used

4) The femoral component should be upsized

If the flexion gap is smaller than the extension gap, the knee should be balanced by removing more posterior bone from the femur or downsizing the femoral component

■Correct Answer: More bone should be removed from the posterior femur

178. (1735) Q1-2131:

Which of the following can lead to patellar dislocation in total knee replacement:

1) Internal rotation of femoral component

3) Too large a femoral component

2) External rotation of femoral component

5) Too large a tibial component

4) External rotation of tibial component

Internal rotation of either the femoral or tibial component may lead to patellar dislocation. External rotation of the femoral or tibial component does not usually lead to dislocation, and increased size of the femoral or tibial component will not predispose to patella dislocation

■Correct Answer: Internal rotation of femoral component

179. (1736) Q1-2132:

Epidural analgesia in the postoperative period after total joint replacement is widely used and is associated with all of the following complications except:

1) Nausea

3) Peroneal nerve palsy

2) Respiratory depression

5) Hypotension

4) Femoral nerve palsy

Nausea, hypotension, respiratory depression, and peroneal nerve palsy are associated with epidural analgesia. Be aware of an epidural bleed secondary to anticoagulation efforts for deep venous thrombosis prophylaxis

■Correct Answer: Femoral nerve palsy

180. (1737) Q1-2133:

Painful "clunking" sensations upon active extension from 60° to 30° in patients with total knee replacements are:

1) Fibrous nodules under patellar tendon

3) Fibrous nodule under distal quadriceps tendon

2) Seen only in posterior-stabilized total knee replacement because of fibrous build up in the nodule

5) Oversized tibial components

4) Seen only in posterior cruciate retaining total knee replacements

This painful clunking sensation from 60° to 30° is caused by a fibrous nodule under the distal quadriceps tendon. Contributing factors include a large patellar component with proximal overhang and an abrupt change in the radius of curvature of the femoral component that irritates the quadriceps tendon

■Correct Answer: Fibrous nodule under distal quadriceps tendon

181. (1738) Q1-2134:

All of the following are reported advantages of metal-backed patella components except:

1) Metal-backed patella components minimize deformity of overlying polyethylene.

3) Metal-backed patella components allow for cementless fixation.

2) Metal-backed patella components permit more evenly distribution of load transmissions.

5) Metal-backed patella components reduce the polyethylene thickness at the periphery of the implant.

4) Metal-backed patella components increase deformity of the overlying polyethylene.

Metal-backed patella components minimize deformity of the overlying polyethylene and do not increase deformity. These components enable an even distribution of load transmissions and reduce the polyethylene thickness at the periphery of the implant. Metal-backed patella components also allow for cementless fixation of the patellae component

■Correct Answer: Metal- backed patella components increase deformity of the overlying polyethylene.

182. (1739) Q1-2135:

Failure modes of metal-backed patella designs include all of the following except:

1) Dissociation of polyethylene and metal plate

3) Femoral component exposed to the metal of the patella component

2) Component fractures

5) MetalliCsynovitis

4) Increased risk of patella dislocation

The polyethylene wear exposing the metal to wear against the femoral component is the ultimate result of all of the above failure modes except increased patella dislocation

■Correct Answer: Increased risk of patella dislocation

183. (1740) Q1-2136:

The incidence of patella component loosening is:

1) 4%

3) 2%

2) 10%

5) 15%

4) 8%

The incidence of patella component loosening is less than 2%. Factors predisposing to loosening include cementation into deficient bone, component malposition, patellar subluxation or fracture, patellar avascular necrosis, asymmetriCpatellar bone resection, and loosening of other components. Treatment options include observation, component revision, patellectomy or component removal, and patellar arthroplasty if bone stock is sufficient

■Correct Answer: 2%

184. (1741) Q1-2137:

The preferred means for fixation of patellar components is:

1) Large, central patellar lugs

3) Three large patellar-fixation lugs

2) Two parallel patellar lugs

5) One central and two peripheral-fixation lugs

4) Three small peripheral-fixation lugs

Large, central patellar-fixation lugs remove a significant amount of bone, which contributes to patellar fractures. Three small peripheral-fixation lugs are preferred in most designs

■Correct Answer: Three small peripheral-fixation lugs

185. (1742) Q1-2138:

The majority of patellofemoral instability cases are secondary to:

1) Trauma

3) Surgical technique

2) Failure to perform a lateral release

5) Patient related

4) ProsthetiCdesign

Trauma, failure to perform a lateral release, and prosthetiCdesign are associated with patellofemoral instability, but the majority

of patellofemoral instability cases are secondary to errors in surgical judgement and technique

■Correct Answer: Surgical technique

186. (1743) Q1-2139:

Which of the following conditions related to the femur does not influence patellofemoral mechanics and stability:

1) Selecting an oversized femoral component

3) Medial positioning of the femoral component

2) Improper femoral component rotation

5) Excessive flexion gap

4) Excessive axial valgus alignment

The femoral component size, rotation, position, and alignment influence patellofemoral mechanics. For instance, an oversized femoral component leads to "overstuffing" that results in decreased flexion of the knee. Excessive flexion gap does not influence patellofemoral mechanics

■Correct Answer: Excessive flexion gap

187. (1744) Q1-2140:

The position of the tibial component influences patellar biomechanics. The best position to place the component is:

1) Internal rotation of the tibial component

3) Medialization of tibial component

2) External rotation of the tibial component

5) External rotation and lateralization

4) Lateralization of tibial component

The tibial component must be positioned in external rotation and lateralized when possible. Internal rotation or medialization predispose to patellar subluxation

■Correct Answer: External rotation and lateralization

188. (1745) Q1-2141:

Which of the following is not a risk factor for fracture of the distal femur proximal to total knee replacement (TKR):

1) Rheumatoid arthritis and osteopenia

3) Osteoarthritis

2) Anterior femoral notching

5) Revision arthroplasty

4) Steroid use

The risk factors associated with fracture of the distal femur proximal to TKR are anterior femoral notching (especially if more than

3 mm in depth), rheumatoid arthritis, steroid use, osteopenia, revision arthroplasty, neuromuscular disorders, stiff knee, or poor flexion of the TKR

■Correct Answer: Osteoarthritis

189. (1746) Q1-2142:

Risk factors for peroneal nerve palsy after total knee replacement (TKR) include all of the following except:

1) Severe valgus deformity

3) Epidural anethesia

2) Flexion contracture

5) Increased flexion gap

4) Previous lumbar laminectomy and valgus osteotomy

Severe valgus deformity, flexion contracture, and epidural anesthesia are risk factors associated with peroneal nerve palsy following TKR. Previous lumbar laminectomy and previous valgus osteotomy of the tibia also increase a patientâs chance of peroneal nerve palsy

■Correct Answer: Increased flexion gap

190. (1747) Q1-2144:

The most common cause of stiffness after total knee replacement (TKR) is:

1) Implant selection

3) Flexion contracture of the contralateral extremity

2) Poor preoperative range of motion

5) Tight posterior cruciate ligament (PCL) after implanting a PCL-retaining knee

4) A large spacer

Poor preoperative range of motion is the main cause of stiffness after TKR

■Correct Answer: Poor preoperative range of motion

191. (1748) Q1-2145:

The femoral component can be malaligned in how many different directions:

1) 1

3) 4

2) 2

5) 8

4) 6

The femoral component can be malaligned in one of eight different directions

■Correct Answer: 8

192. (1749) Q1-2146:

What size tibial insert is associated with easy failure and accelerated osteolysis:

1) 6 mm

3) 10 mm

2) 8 mm

5) 15 mm

4) 12 mm

Inserts thinner than 6 mm are associated with easy failure and osteolysis, caused by fracture and wear of the polyethylene

■Correct Answer: 6 mm

193. (1750) Q1-2147:

Which of the following tests helps in the diagnosis of reflex sympathetiCdystrophy:

1) MagnetiCresonance imaging

3) Bone scanning

2) Computerized tomography scanning

5) Tomography

4) Ultrasonography

Usually, reflex sympathetiCdystrophy is a diagnosis of exclusion characterized by a syndrome of pain out of proportion to the clinical findings; a bone scan may demonstrate increased uptake in the affected area

■Correct Answer: Bone scanning

194. (1751) Q1-2148:

Erythema, warmth, stiffness, and cutaneous hypersensitivity after total knee replacement associated with pain is usually caused by:

1) Infection

3) Gout

2) Reflex sympathetiCdystrophy

5) Vascular insufficiency

4) Patellar malalignment

These symptoms, in addition to pain out of proportion to clinical findings, characterize a slow postoperative course. Poor function after total knee replacement is usually secondary to reflex sympathetiCdystrophy

■Correct Answer: Reflex sympathetiCdystrophy

195. (1752) Q1-2149:

Aspirating synovial fluid prior to total knee replacement revision surgery after ensuring that a patient is not concurrently on antibiotiCtherapy has a sensitivity, specificity, and accuracy of:

1) 20% to 40%

3) Less than 20%

2) 60% to 80%

5) 90% to 100%

4) 40% to 60%

Providing the patient is off antibiotics, the sensitivity, specificity, and accuracy of snynovial fluid aspiration is 100%. AntibiotiCadministration before or during the aspiration will mask the analysis

■Correct Answer: 90% to 100%

196. (4048) Q1-2187:

The principal thrombogeniCstimulus that leads to the production of venous thromboemboliCdisease during total hip arthroplasty occurs:

1) During the induction of anesthesia

3) 12 hours postoperative

2) During the preparation of the femoral canal

5) 7 days postoperative

4) 24 hours postoperative

The process of thrombosis starts during the preparation of the femoral canal. Elevation in thrombogeniCfactors is most pronounced during preparation of the femoral canal, especially with insertion of a cemented femoral component. Mechanical manipulation of the limb (dislocation of the femoral head) may also cause intimal damage or occlusion of the femoral vein

■Correct Answer: During the preparation of the femoral canal

197. (1789) Q1-2188:

Place the following in the correct order of increasing modulus of elasticity (least to greatest):

1) Cobalt-chrome, titanium, compact bone, stainless steel

3) Compact bone, titanium, cobalt-chrome, stainless steel

2) Titanium, compact bone, cobalt-chrome, stainless steel

5) Titanium, compact bone, stainless steel, cobalt-chrome

4) Compact bone, titanium, stainless steel, cobalt-chrome

Modulus of elasticities are as follows in Gpa (psi 3 106 ): Compact bone: 21 (3)

Titanium: 96 (14) Stainless steel: 193 (28) Cobalt-chrome: 235 (34)

Correct Answer: Compact bone, titanium, stainless steel, cobalt-chrome

198. (1790) Q1-2189:

Which of the following precautionary measures should be taken to prevent a periprosthetiCfracture when removing components from a patient with a previous compression hip screw:

1) Cemented femoral component with cement augmentation of the screw holes and full weight bearing

3) Toe touch weight bearing for 6 weeks

2) Plate augmentation with circlage wires and protected weight bearing

5) Bypass the last screw hole with a cemented femoral component by two cortical diameters and protected weight bearing

4) Cortical strut allograft and protected weight bearing

Stress risers are generated when a screw is removed from the femur, weakening the bone for at least 4 weeks. Larger defects (50%) of the cortical width can reduce torsional strength up to 44%. Bypassing the defect by two cortical diameters with a cemented stem doubles the boneâs strength

■Correct Answer: Bypass the last screw hole with a cemented femoral component by two cortical diameters and protected weight bearing

199. (1791) Q1-2190:

Which of the following radiographiCchanges is apparent after placement of a fully porous-coated, cobalt-chrome femoral stem:

1) Proximal-femoral osteopenia

3) Radiolucency around the acetabular cup

2) Distal-femoral osteopenia

5) Osteopenia adjacent to the entire femoral component

4) Increased mineralization proximally

The most severe stress shielding occurs with an extensively porous-coated chrome-cobalt stem. Stress shielding occurs as the load is transferred from the hip joint to the proximal femur. The load that was previously carried by the hip joint is now shared with the implant. This change leads to remodeling of the proximal femur, resulting in a decreased density and thinning of the proximal portion of the femur. In a group of patients characterized as having severe stress-shielding based on plain radiographs, no adverse effects were noted in terms of hip scores, presence of osteolysis, or need for revision

■Correct Answer: Proximal- femoral osteopenia

200. (1792) Q1-2191:

Noncircumferential-porous  coating leads to which of the following adverse effects:

1) Increased rates of infection

3) Increased rates of distal osteolysis and late femoral loosening

2) Increased rates of stress shielding

5) Increase rates of thigh pain

4) Increase rates of thigh pain

Noncircumferential-porous  coating allows a pathway for particulate debris (polywear) to the distal part of the stem, promoting osteolysis. The polyethylene wear debris migrates through the pathway promoting osteolysis and, ultimately, failure

■Correct Answer: Increased rates of distal osteolysis and late femoral loosening