Introduction Dislocation following THA is a common reason for revision Epidemiology incidence 1-3% 70% occur within first month 75-90% posterior Mechanism anterior extension and external rotation of hip posterior flexion, internal rotation, adduction of hip Risk factors prior hip surgery (greatest risk factor) female sex >70-80 years of age posterior surgical approach repairing capsule and reconstructing external rotators brings dislocation rate close to anterior approach malpositioning of components ideal positioning of acetabular component is 40 degrees of abduction and 15 degrees anteversion in general, excessive anteversion increases risk of anterior hip dislocation; excessive retroversion increases risk of posterior hip dislocation spastic or neuromuscular disease (Parkinson's) drug or alcohol abuse decreased femoral offset (decreases tissue tension and stability) decreased femoral head to neck ratio Presentation History often reports activity that puts patient in a position that provokes dislocation (hip flexion, adduction, internal rotation) shoe tying sitting in low seat or toilet Imaging Radiographs recommended views AP cross-table lateral findings increased acetabular inclination > 60° increased acetabular anteversion > 20° aceabular retroversion look for eccentric position of femoral head as an indication of polyethylene wear and risk for impending dislocation Treatment Nonoperative closed reduction and immobilization indications two-thirds of early dislocations can be treated with closed reduction and immobilization technique immobilize with hip spica cast, hip abduction brace, or knee immobilizer Operative polyethylene exchange indications stable well-aligned implants with extensive polyethylene wear thought to be sole reason for dislocation revision THA indications indicated if 2 or more dislocations with evidence of implant malalignment vertical acetabular component acetabular retroversion implant failure polyethylene wear techniques see below conversion to hemiarthroplasty with larger femoral head indications for soft tissue deficiency or dysfunction contraindicated if acetabular bone is compromised older technique rarely used with development of dual mobility implants resection arthroplasty indications when all options have been exhausted significant bone loss and soft tissue deficiency psychiatric patients who are dislocating for secondary gain Technique Revision THA techniques to prevent future dislocation during THA include realign components indicated if malalignment explains dislocation retroverted acetabulum vertical acetabulum short femoral neck lack of femoral neck offset retroverted femoral component head enlargement optimize head-neck ratio trochanteric osteotomy and advancement places abductor complex under tension which increases hip compression force conversion to a constrained acetabular component indications recurrent instability with a well positioned acetabular component due to soft tissue deficiency or dysfunction conversion to dual mobility implant conversion to tripolar construct
QUESTIONS 1 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ10.15) All of the following are independent risk factors for dislocation after total hip arthroplasty EXCEPT? Review Topic QID: 3103 1 Female gender 10% (195/1915) 2 Osteonecrosis 32% (621/1915) 3 Inflammatory arthritis 10% (183/1915) 4 Post traumatic osteoarthritis 36% (693/1915) 5 Age >70 11% (214/1915) ML 5 Select Answer to see Preferred Response PREFERRED RESPONSE 4 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ08.260) What is the most common complication after revision of a total hip polyethylene liner in a patient with well-fixed femoral and acetabular shell components? Review Topic QID: 646 1 dislocation 84% (1857/2218) 2 failure of the femoral component 0% (8/2218) 3 extensive osteolysis 5% (113/2218) 4 failure of the fixation between the liner and the acetabular shell 9% (200/2218) 5 fracture of the polyethylene 1% (31/2218) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (OBQ09.202) Which of the following situations is appropriate for revision of a total hip arthroplasty to a constrained acetabular liner? Review Topic QID: 3015 1 Periprosthetic acetabular fracture with resulting pelvic discontinuity 1% (12/1533) 2 Chronically infected total hip arthroplasty 0% (6/1533) 3 Recurrent dislocations in a patient whose femoral component is positioned in 15° retroversion 3% (52/1533) 4 Recurrent dislocations in a patient whose cup is positioned in 10° retroversion and 60° abduction 8% (117/1533) 5 Recurrent dislocations in a patient whose cup is positioned in 20° anteversion and 40° abduction 88% (1344/1533) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 5 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ06.18) A 64-year-old healthy female patient underwent right total hip replacement (THR) through a posterior approach 6 months ago. She has now dislocated posteriorly 3 times, each followed by closed reduction under anesthesia in the operating room. A radiograph is provided in Figure A. Treatment should include: Review Topic QID: 29 FIGURES: A 1 Hip spica casting 0% (1/1978) 2 Revision of the femoral component to a modular stem with retention of the acetabular component 1% (12/1978) 3 Revision of the acetabular component 97% (1912/1978) 4 Hip abduction bracing 1% (19/1978) 5 Revision to a constrained liner with retention of the acetabular and femoral prostheses 1% (26/1978) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ10.236) A 65-year-old male with chronic right hip pain undergoes the procedure seen in Figure A utilizing a posterior approach. Which of the following hip positions would put the patient at the greatest risk for dislocation? Review Topic QID: 3335 FIGURES: A 1 Abduction and external rotation 1% (15/2301) 2 Flexion and external rotation 3% (60/2301) 3 Flexion and internal rotation 95% (2188/2301) 4 Extension and internal rotation 1% (24/2301) 5 Extension and external rotation 0% (10/2301) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ09.269) All of the following are acceptable indications for use of a constrained acetabular component EXCEPT: Review Topic QID: 3082 1 Recurrent dislocations due to abductor insufficiency 4% (64/1609) 2 Recurrent dislocations due to unsalvageable capsular attenuation 1% (15/1609) 3 Recurrent dislocations due to severe polyethylene wear 84% (1356/1609) 4 Recurrent late dislocations without component loosening or malposition 7% (108/1609) 5 Recurrent dislocations due to cognitive or neuromuscular disease 4% (65/1609) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ10.98) A 68-year-old male 2 weeks status post left total hip arthroplasty experiences a painful clunk getting out of bed in the morning. He is unable to bear any weight on the left leg. A radiograph is provided in figure A. Following closed reduction under sedation, the hip continues to dislocate with flexion up to 90 degrees. Each of the following operative interventions will increase the stability of the hip EXCEPT: Review Topic QID: 3192 FIGURES: A 1 Revising the acetabular component to a more medialized position 81% (1962/2423) 2 Advancing the trochanter distal on the femur 9% (227/2423) 3 Converting to a femoral component with extended offset 3% (73/2423) 4 Replacing the acetabular polyethylene with a constrained liner 4% (108/2423) 5 Replacing the femoral head with a larger size 2% (47/2423) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (OBQ09.126) A 60-year-old male had a total hip replacement 8 years ago. There is evidence of eccentric polyethylene wear and some retroacetbular osteolysis. You discuss treatment options of acetabular revision if the component is found to be loose intra-operatively versus isolated polyethylene exchange if the acetabular component is stable intra-operatively with the patient. What is the most common complication of isolated polyethylene exchange with bone grafting that should be disclosed? Review Topic QID: 2939 1 Sciatic nerve injury 2% (30/1473) 2 Intraoperative acetabular fracture 10% (144/1473) 3 Postoperative hip instability 66% (968/1473) 4 Infection 11% (157/1473) 5 Catastrophic implant failure 11% (163/1473) ML 3 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ04.64) A 62-year-old woman presents for her 1-year follow-up after a revision right total hip arthroplasty. She has no complaints of pain and has returned to all her activities of daily living. An AP radiograph is shown in Figure A. The black arrow in the radiograph indicates she is at higher risk for which of the following? Review Topic QID: 1169 FIGURES: A 1 Aseptic loosening 22% (258/1157) 2 Aseptic lymphocytic vasculitis-associated lesions (ALVAL) 1% (10/1157) 3 Dislocation 56% (643/1157) 4 Third body wear 16% (186/1157) 5 Catastrophic ceramic bearing failure 4% (51/1157) ML 4 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ11.26) A 73-year-old female undergoes a total hip arthroplasty (THA) using a cemented stem design shown in Figure A. She returns to clinic 3 years post-operatively with signifcant thigh pain. Current radiographs, shown in Figure B, demonstrate femoral subsidence. What affect does this have on the biomechanics of her THA? Review Topic QID: 3449 FIGURES: A B 1 Excursion distance is decreased 4% (132/3489) 2 Primary arc range is increased 2% (61/3489) 3 Abductor complex tension is decreased 88% (3063/3489) 4 Joint reactive forces are decreased 3% (120/3489) 5 Femoral offset is increased 3% (88/3489) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ09.5) A 70-year-old man underwent total hip arthroplasty 4 months ago and has experienced 3 dislocations. Radiographs reveal no failure of the hardware and an acetabular component that has an abduction angle of 40 degrees and a version of 10 degrees retroverted. What is the most appropriate treatment for the recurrent dislocations? Review Topic QID: 2818 1 hip abduction brace 1% (21/2001) 2 revision of the acetabular liner to a constrained type 7% (134/2001) 3 revision of the entire acetabular component 89% (1777/2001) 4 revision of the femoral head to a larger size 2% (39/2001) 5 revision to an extended offset prosthesis 1% (17/2001) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 3 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK