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 1321
Topic: 3. Adult Reconstruction (Hip & Knee)
A 59-year-old man underwent interposition arthroplasty for osteoarthritis of the elbow 9 years ago. Over the past year the patient has had increasing pain and elbow instability. There is no clinical evidence of infection, and radiographs show no new bony process. What is the best option for this patient?
Correct Answer & Explanation
. Conversion to total elbow arthroplasty
Explanation
In a series reported by Blaine and associates, 12 patients were converted from interposition to total elbow arthroplasty. This procedure was successful in 10 out of 12 patients.
Question 1322
Topic: 3. Adult Reconstruction (Hip & Knee)
A healthy 72-year-old woman is seen 14 days after cemented total knee arthroplasty. She reports increasing pain and swelling for the last 4 days accompanied by 4 days of wound drainage. Examination reveals that she is afebrile, and has erythema and moderate serosanguinous drainage from the wound. The knee is moderately swollen. Aspiration of the knee reveals no organisms on Gram stain. Culture results are expected back in 48 hours. Optimal management should consist of
Correct Answer & Explanation
. Surgical debridement of the knee before culture results are available
Explanation
Increased pain, swelling, erythema, and drainage 2 weeks removed from the primary arthroplasty are all signs of a probable infection. Erythrocyte sedimentation rate and C-reactive protein may not be helpful as they are elevated postoperatively even in the absence of infection. Even in the absence of infection, persistent wound drainage is an indication for surgical debridement to prevent subsequent infection. When a postoperative infection is easily recognized by clinical examination, there is no need to wait for a positive culture before proceeding with debridement.
Question 1323
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 50 shows the AP radiograph of an asymptomatic 82-year-old woman who underwent total hip arthroplasty 16 years ago. What is the most likely diagnosis?
Correct Answer & Explanation
. Wear-induced osteolysis
Explanation
Pelvic osteolysis in the presence of a well-fixed porous-coated socket is a recognized complication in total hip arthroplasty. The radiograph shows large lytic lesions superiorly adjacent to an acetabular screw and inferiorly extending into the ischium. It also reveals eccentricity of the femoral head with respect to the acetabular component, consistent with polyethylene wear.
Question 1324
Topic: 3. Adult Reconstruction (Hip & Knee)
Hip pain of 1-month duration has developed in a 72-year-old man with a previous total hip arthroplasty. He underwent dental work 6 weeks ago. Aspiration shows a white blood cell count of more than 6,000 cells/μL (reference range 4,500 to 11,000 cells/μL) and the presence of gram-positive cocci in clusters on Gram stain. The orthopaedic surgeon recommends urgent debridement and irrigation. Fixation of the components is judged to be stable, and the surgeon elects to retain the implants. What is this patient's prognosis for infection resolution?
Correct Answer & Explanation
. Poor because it is a late infection
Explanation
DISCUSSION: The patient has a late infection of at least 4 weeks symptomatic duration that most likely is hematogenous in etiology. This infection is not an acute hematogenous infection that can successfully be treated with irrigation and debridement. Retention of the implants with debridement and irrigation alone has been associated with a poor prognosis. In a recent study, the success rate was only 44% in a series of 104 patients at a mean 5.7-year follow-up. In one study of 50 infections attributable to MRSA or methicillin-resistant Staphylococcus epidermidis organisms treated with a two-stage protocol, the failure rate was 21%.
Question 1325
Topic: 3. Adult Reconstruction (Hip & Knee)
A 37-year-old laborer sustained a fracture of the posterior acetabular wall. Two years following operative management, the patient reports severely limited hip motion and back pain. Radiographs reveal extensive mature heterotopic ossification with preservation of the hip joint space. Management should now consist of
Correct Answer & Explanation
. Excision of heterotopic bone and local radiation
Explanation
Heterotopic ossification is very common after acetabular fracture surgery. It is most common with the extensive exposures, rates up to 45-100%. The HO is most extensive when these approaches are utilized and no prophylaxis is provided. The ilio-inguinal approach has the least common incidence of HO. Routine prophylaxis consists of either 1) Indomethacin 25 mg tid for 4-6 weeks, beginning POD #1 or 2) Low dose irradiation 1000 rads in divided doses or 700 rads single dose, begun before POD #4. Surgical excision is only considered when the HO severely reduces hip mobility. It is recommended to have a preop CT scan for your surgical plan, utilize the initial incision and to use great caution around the (unreadable).
Question 1326
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?
Correct Answer & Explanation
. Constrained acetabular liner
Explanation
DISCUSSION: 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.
Question 1327
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following articulation couplings shows the lowest coefficient of friction as tested in the laboratory?
Correct Answer & Explanation
. Ceramic-on-ceramic
Explanation
DISCUSSION: Alumina ceramic is highly biocompatible when used as a biomaterial for joint arthroplasty implants. It has been shown to have good hardness, low roughness, and excellent wettability, therefore resulting in very low friction. However, it is expensive and limited reports have shown the problem of fracture on impact. The exact role for ceramic articulations is unknown at present. REFERENCES: Cuckler JM, Bearcroft J, Asgian CM: Femoral head technologies to reduce polyethylene wear in total hip arthroplasty. Clin Orthop 1995;317:57-63. Sharkey PF, Hozack WJ, Dorr LD, Maloney WJ, Berry D: The bearing surface in total hip arthroplasty: Evolution or revolution, in Price CT (ed): Instructional Course Lectures 49. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 41-56.
Question 1328
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following statements best describes results that have been reported with roentgen stereophotogrammetric analysis (RSA)?
Correct Answer & Explanation
. Migration greater than 1 mm to 2 mm in the first year is associated with a higher risk of loosening.
Explanation
DISCUSSION: Migration of total hip femoral components has been measured by RSA, a technique that affords accuracy of 2 degrees and 0.5 mm. Several published studies on total hip arthroplasty femoral components have established the importance of this technique. Both cemented and cementless components migrate, with the rate of migration suggesting the adequacy of fixation of a component. Migration of 1 mm to 2 mm (occurring in either the varus-coronal plane and retroversion-transverse plane, or both) has been associated with a higher risk of loosening of the component. REFERENCE: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, p 100.
Question 1329
Topic: 3. Adult Reconstruction (Hip & Knee)
An elderly obese woman has left knee pain. She had surgery 5 years ago for a patellar nonunion after total knee arthroplasty that was complicated by infection, which was treated with implant removal and patellectomy. She has not been ambulatory since then. She states she is no longer on antibiotics. She has moderate pain, but her primary problem is instability of the knee. She has a 40° extensor lag. Darkening of the skin is present distal to the incision consistent with venous stasis changes. The erythrocyte sedimentation rate is 12 mm/h (reference range 0 to 20 mm/h) and her C-reactive protein level is 0 mg/L (reference range 0 to 1 mg/L). Left knee aspiration shows a white blood cell count of 800 and 20% neutrophils. What is the best next step?
Correct Answer & Explanation
. Hinged knee arthroplasty with full extensor mechanism allograft
Explanation
DISCUSSION: This patient is elderly, obese, and nonambulatory and has a chronic quadriceps tendon rupture after infected total knee arthroplasty. Her potential for ambulation after revision total knee arthroplasty is very low. Primary repair of the tendon is unlikely to be successful, even with augmentation, so revision total knee arthroplasty with primary quadriceps tendon repair and two-stage revision knee arthroplasty and quadriceps repair with Achilles allograft are not the best management techniques. Extensor mechanism allograft could be done but would have a high failure rate in a patient of this size. No sign of infection is seen, based on laboratory studies, so a two-stage procedure is not necessary. The best management, although not optimal, would be treatment in a drop-lock brace. Arthrodesis is also an option, but would have a high complication rate, and in a patient that is nonambulatory, a fused knee would be increasingly difficult with activities of daily living and mobility.
Question 1330
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 1 is the radiograph of an otherwise healthy 68-year-old man with a 4-year history of increasing global left knee pain. He has noticed stiffness, and despite physical therapy, bracing and nonsteroidal anti-inflammatory drugs, he has continued to develop worsening symptoms and progression in his deformity. Physical examination demonstrates 80°of flexion and a 10° flexion contracture. What is the best next step?
Correct Answer & Explanation
. Left total knee arthroplasty (TKA)
Explanation
Figures 1 and 2 are the radiographs of a 70-year-old man who underwent knee explantation with antibiotic spacer placement. At the time of second- stage surgery for reimplantation of a total knee arthroplasty, a medial parapatellar arthrotomy is used to access the knee. An extensive synovectomy is performed and the gutters are recreated. Medial and lateral joint line releases are done, and scar tissue is removed from around the patella. The cement spacer is removed and the nail is cut and extracted. However, despite this, the knee only flexes 45° and lateral exposure is compromised. What is the best next step?
Question 1331
Topic: 3. Adult Reconstruction (Hip & Knee)
An otherwise healthy 76-year-old woman has pain 2 years after total hip arthroplasty. The clinical photograph in the figures below demonstrates her skin envelope and associated radiograph. Her C-reactive protein level is normal, and her erythrocyte sedimentation rate is mildly elevated. The white blood cell count is normal. Hip aspiration attempted under fluoroscopy generates no fluid. What is the best definitive treatment?
Correct Answer & Explanation
. Debridement of the wound, explant of the total hip, placement of a spacer, and administration of intravenous antibiotics
Explanation
DISCUSSION: This patient clearly has a chronically infected total hip arthroplasty, indicated by the open, draining sinus, as well as trochanteric bone resorption on radiographs, and two years of pain. Recently, specific guidelines have been published to better help the clinician define infection. Repeating the hip aspiration is unnecessary, because infection is already evident. Initiating a wound care consult would not address the underlying infection. The determination whether to retain the components or perform a two-stage exchange is based more on the acuity of infection. In this particular case, the patient is chronically infected. Irrigation and debridement with a liner exchange and retention of the components are reserved for the acute setting.
Question 1332
Topic: Total Knee Arthroplasty (TKA)
A 70-year-old woman has a 3-year history of gradually increasing diffuse and global right knee pain. Her main issues are difficulty with stairs, stiffness with prolonged sitting, and swelling. She has taken NSAIDs and has received intra-articular steroid injections, all with decreasing efficacy. Her right knee examination reveals a range of motion of 15° to 80° with a fixed deformity to varus and valgus stress. Her symptoms are no longer manageable nonsurgically. Radiographs reveal a 30-degree mechanical axis deformity. When using the measured resection technique during total knee arthroplasty (TKA), the best way to avoid femoral malrotation is to reference the
Correct Answer & Explanation
. anteroposterior axis.
Explanation
DISCUSSION: In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point, can lead to internal rotation of the femoral component. This malrotation in turn leads to patellofemoral maltracking or instability, which is a common complication associated with primary TKA.
Question 1333
Topic: 3. Adult Reconstruction (Hip & Knee)
Figures 1 through 3 show the clinical photographs obtained from a 45-year-old woman who is right-hand dominant. She has pain in the left ring proximal interphalangeal (PIP) joint that gets worse during lifting or gripping activities. On examination, she has PIP range of motion of 15° to 50° with laxity of the radial collateral ligament and tenderness around the joint. The flexor and extensor tendons are intact. She has rotational malalignment when making a composite fist. Radiographs reveal end-stage arthritis at the PIP joint. She elects to move forward with surgery and undergoes arthroplasty. What component of the examination is essential to determine which implant arthroplasty—silicone or surface replacement—is best?
Correct Answer & Explanation
. Collateral ligament stability
Explanation
EXPLANATION: This patient has end-stage arthritis in conjunction with ligament insufficiency. The treatment for arthritis is arthroplasty or fusion. Given that her ring finger is affected, arthroplasty is recommended to preserve motion and grip. Two types of arthroplasties are available: silicone and surface replacement. The prerequisites are the same for both and include good bone stock, good sensibility of the joint, adequate soft-tissue coverage, and normally functioning tendons. Adequate collateral ligaments are required for surface replacement arthroplasty. This patient has a deficiency of the radial collateral ligament, evidenced by her clinical examination. Thus, silicone arthroplasty is the recommended option for joint replacement in this patient.
Question 1334
Topic: 3. Adult Reconstruction (Hip & Knee)
A woman experiences pain 1 year after total knee arthroplasty (TKA). She reports sharp anterior pain and a painful catching sensation that is aggravated by rising from a chair or climbing stairs. Physical examination reveals a mild effusion and a range of motion of 2° to 130°, with patellar crepitus. The symptoms are reproduced by resisted knee extension. Radiographs show a well-aligned posterior-stabilized TKA without evidence of component loosening. What is the most likely cause of this patient's pain?
Correct Answer & Explanation
. Patellar clunk syndrome
Explanation
DISCUSSION: Patellar clunk syndrome is caused by the development of a fibrous nodule on the posterior aspect of the quadriceps tendon at its insertion into the patella. It causes a painful catching sensation when the extensor mechanism traverses over the trochlear notch as the knee extends from 45° of flexion to 30° from full extension. It characteristically occurs in posterior stabilized total knee arthroplasties and appears to be related to femoral component design. The syndrome can usually be prevented by excising the residual synovial fold just proximal to the patella. Flexion gap instability can also cause a painful total knee arthroplasty but is less common in posterior stabilized implants. Femoral component malrotation can cause pain attributable to a flexion gap imbalance or patellar tracking problems. Polyethylene wear would be unlikely after just 1 year. Patellar clunk syndrome can usually be addressed successfully with arthroscopic synovectomy. Recurrence is uncommon. Physical therapy may help to strengthen the quadriceps following synovectomy but would not resolve the clunk syndrome symptoms. Femoral or tibial insert revision is not indicated if patellar clunk syndrome is the only problem resulting in a painful total knee arthroplasty.
Question 1335
Topic: 3. Adult Reconstruction (Hip & Knee)
Analysis of primary total hip arthroplasty using press-fit acetabular components without supplementary screw fixation reveals that screw fixation
Correct Answer & Explanation
. increases backside polyethylene wear.
Explanation
Using mechanical failure of fixation as the end point, Udomkiat and associates demonstrated a 12-year survivorship of 99.1% for titanium press-fit acetabular components without supplementary screw fixation. This study suggests that it is unlikely that the use of supplementary screws would lead to improved results. In addition, polyethylene wear debris tends to migrate through screw holes and along the course of screws. Screw holes also decrease the available surface for bone ingrowth. Screws that back up may be a source of backside polyethylene wear. This suggests that screw holes and the use of screws should be avoided when they are unnecessary for cup fixation.
Question 1336
Topic: 3. Adult Reconstruction (Hip & Knee)
Figures below demonstrate the radiographs obtained from a 63-year-old man who had right total hip arthroplasty (THA) 4 months ago. Progressive stiffness began 2 months after surgery, and he now reports pain only after prolonged physical activity. His examination reveals a normal gait and painless range of motion with flexion of 70°, extension of 0°, internal rotation of 20°, external rotation of 20°, abduction of 10°, and adduction of 10°. His erythrocyte sedimentation rate and C-reactive protein level are within defined limits. Physical therapy has produced no benefit. What is the most appropriate next step?
Correct Answer & Explanation
. 25 mg of indomethacin 3 times daily for 6 weeks
Explanation
This patient presents with HO 4 months after undergoing THA. Symptomatic HO may complicate nearly 7% of primary THA cases. Improvement in pain is expected within 6 months, and most patients will not need surgical treatment. Surgical excision may be warranted for symptomatic patients after full maturation of the HO, usually 6 to 18 months after the surgery. Patients can be followed with repeated serum alkaline phosphatase levels, which are elevated initially and should return to normal upon maturation of the HO. Alternatively, a bone scan can show decreased activity after the HO has matured. Twenty-five milligrams of indomethacin 3 times daily for 6 weeks or 1 dose of irradiation at 700 to 800 Gy is effective in the prevention of HO but not for the treatment of established HO.
Question 1337
Topic: 3. Adult Reconstruction (Hip & Knee)
Figures below show the radiographs obtained from a 68-year-old man with progressively worsening right side hip pain over the last 8 months. He is 6 feet tall, with a BMI of 51 kg/m2 and reports that his index total hip arthroplasty was performed 8 years ago. The preoperative work-up includes negative infectious laboratory results. What is the most appropriate surgical plan for revision of the femoral component in this patient?
Correct Answer & Explanation
. Posterolateral approach with an extended trochanteric osteotomy
Explanation
The patient’s radiographs demonstrate varus femoral remodeling around a broken cylindrical, distally fixed femoral stem. Proximal femoral remodeling around loose or fractured stems occurs in 21% to 42% of femoral revisions. Based on the templating or drawing a line from the isthmus proximally along the lateral cortex, implantation of a straight stem would perforate the cortex proximally, indicating varus femoral remodeling. An extended trochanteric osteotomy would aid in the removal of the well-fixed distal segment and enable the safe insertion of the new femoral component. The approach is not the concern in this case, because extended trochanteric osteotomies have been described from the posterior and direct lateral approaches with excellent outcomes and union rates. The key is that the extended osteotomy is necessary and not a trochanteric slide or standard (shorter or incomplete trochanteric) osteotomy.
Question 1338
Topic: 3. Adult Reconstruction (Hip & Knee)
1 and 2 demonstrate the radiographs obtained from a year-old woman with end-stage debilitating osteoarthritis of the right hip. She is contemplating total hip arthroplasty (THA). She has a history of right hip dysplasia and underwent hip osteotomy as an adolescent. Over the years, nonsurgical treatment, including weight loss, activity modifications, and intra-articular injections, has failed. Her infection work-up reveals laboratory findings within defined limits.The patient undergoes successful primary THA with a metal-on-metal bearing. At year follow-up, she reports no pain and is highly satisfied with the procedure. However, 3 years after the index procedure, she reports atraumatic right hip pain that worsens with activities. Radiographs reveal the implants in good position with no sign of loosening or lysis. An initial laboratory evaluation reveals a normal sedimentation rate and C-reactive protein (CRP) level. The most appropriate next diagnostic step is
Correct Answer & Explanation
. MRI with metal artifact reduction sequence (MARS) only. B. serum cobalt only.
Explanation
DISCUSSION:THA has proven to be durable and reliable for pain relief and improvement of function in patients with end-stage arthritis. Appropriate bearing selection is critical to minimize wear and hip complications. Ametal-on-metal articulation is associated with excellent wear rates in vitro. Because it offers a low wear rate with large femoral heads, it is an attractive bearing choice for THA. However, local soft-tissue reactions, pseudotumors, and potential systemic reactions—including renal failure, cardiomyopathy, carcinogenesis, and potential teratogenesis after the possible transfer of metal ions across the placental barrier—make metal-on-metal bearings less desirable and relatively contraindicated for younger women of child-bearing age.The work-up of a painful metal-on-metal hip arthroplasty necessitates a systematic approach. Several algorithms have been proposed. Routine laboratory studies including the erythrocyte sedimentation rate, C-reactive protein (CRP) level, and serum cobalt and chromium ion levels should be obtained for all patients with pain. Advanced imaging, including MRI with MARS, should be performed to evaluate for the presence of fluid collections, pseudotumors, and abductor mechanism destruction. Infection can coexist with metal-on-metal reactions, so when indicated (if the CRP level is elevated), a hip arthrocentesis should be obtained. However, in this setting, a manual cell count and differential should be obtained because an automated cell counter may provide falsely elevated cell counts. The results of revision surgery for a failed metal-on-metal hip prosthesis can be variable. The amount of local tissue destruction and the integrity of the hip abductor mechanism can greatly influence outcomes. Instability is the most common complication following a revision of failed metal-on-metal hip replacements.
Question 1339
Topic: 3. Adult Reconstruction (Hip & Knee)
Risk of fat embolism is greatest during what step of total hip arthroplasty?
Correct Answer & Explanation
. Osteotomy of the femoral neck
Explanation
DISCUSSION: Embolization of fat and bone marrow elements during total hip arthroplasty has been studied intraoperatively using transesophageal echocardiography. These studies showed the occurrence of a large number of embolic events during the insertion of a cemented femoral stem. Embolic events were rare during insertion of a cementless stem. Femoral broaching caused some embolic events, but they were not nearly as significant as those that occurred following insertion of a cemented stem. Additionally, relocation of the cemented hip was accompanied by significant embolic events. This may be related to the untwisting of blood vessels, with the subsequent release of emboli that were most likely generated during insertion of a cemented femoral stem.REFERENCES: Pitto RP, Koessler M, Kuehle JW: Comparison of fixation of the femoral component without cement and fixation with use of a bone-vacuum cementing technique for the prevention of fat embolism during total hip arthroplasty. J Bone Joint Surg Am1999;81:831-843.Christie J, Burnett R, Potts HR, Pell AC: Echocardiography of transatrial embolism during cemented and uncemented hemiarthroplasty of the hip. J Bone Joint Surg Br 1994;76:409-412.
Question 1340
Topic: 3. Adult Reconstruction (Hip & Knee)
In patients undergoing elective hip or knee arthroplasty who are not at elevated risk (beyond the risk associated with the surgery) for venous thromboembolism or bleeding, using pharmacologic agents and/or mechanical compressive devices for the prevention of venous thromboembolism was assigned what grade of recommendation by the 2011 AAOS Clinical Practice Guideline, Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Hip and Knee Arthroplasty?
Correct Answer & Explanation
. Moderate
Explanation
DISCUSSION: Using pharmacologic agents and/or mechanical compressive devices for the prevention of venous thromboembolism in patients undergoing elective hip or knee arthroplasty who are not at elevated risk beyond that of the surgery itself for venous thromboembolism or bleeding was given a moderate grade of recommendation in the 2011 AAOS Clinical Practice Guideline referenced above.
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