Introduction Abnormal patellar tracking is the most common complication of TKA. the most important variable in proper patellar tracking is preservation of a normal Q angle. Abnormal Q angle an increase in the Q angle will lead to an increased lateral subluxation forces on the patella relative to the trochlear groove possible pain, mechanical symptoms, accelerated wear, and even dislocation. it is critical to avoid techniques that lead to increase Q angle. Common errors include internal rotation of the femoral prosthesis medialization of the femoral component internal rotation or medialization of the tibial prosthesis placing the patellar prosthesis lateral on the patella Anatomy Q Angle the Q angle is defined as angle between axis of extensor mechanism (ASIS to center of patella) axis of patellar tendon (center of patella to tibial tuberosity) Imaging CT scan malrotation of components is best diagnosed with CT scan of the knee Femoral Prosthesis There are three reference axis that one may use: anteroposterior axis defined as a line running from the center of the trochlear groove to the top of the intercondylar notch a line perpendicular to this defines the neutral rotational axis transepicondylar axis defined as a line running from the medial and lateral epicondyles the epicondylar axis is parallel to the cut tibial surface a posterior femoral cut parallel to the epicondylar axis will create the appropriate rectangular flexion gap posterior condylar axis defined as a line running across the tips of the two posterior condyles this line is in ~ 3 degrees of internal rotation from the transepicondylar axis, the femoral prosthesis should be externally rotated 3 degrees from this axis to produce a rectangular flexion gap if the lateral femoral condyle is hypoplastic, use of the posterior condylar axis may lead to internal rotation of the femoral component WARNING: the average posterior condylar twist angle is 3º but the range is 1-10º. Therefore vary angle of femoral rotation based on variances in femoral anatomy. Internal Rotation of Femoral Prosthesis will Increase Q angle by internally rotating the femoral prosthesis, you are effectively bringing the groove and the patella medially. This will increase the Q angle to the tibial tubercle will also make the medial compartment tight in flexion with subsequent TKA stiffness Medialization of the Femoral Prosthesis will Increase Q angle a medialized femoral prosthesis will bring the trochlear groove to a more medial position, and thus bring the patella medial with it, thus increasing the Q angle therefore, you want the femoral component to be slighly lateral if anything Tibial Prosthesis The preferred rotation of the tibial component is neutral, with no internal or external rotation. the best way to obtain this is to have the tibial component centered over the medial third of the tibial tubercle this may leave a portion of the posteromedial tibia uncovered and some overhang of the prosthesis over the tibia on the posterolateral tibia. Internal Rotation of Tibial Prosthesis will increase Q angle internal rotation of the tibial component effectively results in relative external rotation of the tibial tubercle and an increase in the Q angle Medialization of tibia will increase Q angle Patellar Prosthesis The preferred position of the patellar prosthesis is to be either centered over the patella or medialized medializing the patellar component is one strategy to decrease the Q angle. results in uncoverage of lateral facet. Consider removing to lessen risk of lateral facet syndrome. another alternative is use of an oval shaped patella with the apex medialized. Lateralization of the patellar prosthesis will increase the Q angle and increase maltracking Intraoperative lateral subluxation of the patella if patella laterally subluxes intraoperatively during trialing, deflate tourniquet and recheck before performing a lateral release Indications for resurfacing absolute inflammatory arthritis patella maltracking patellofemoral arthritis as the main indication for TKA Options for resurfacing during TKA always resurface never resurface option to perform patelloplasty excision of marginal osteophytes, reshaping of patella selective resurfacing Patella resurfacing vs. Non-resurfacing less anterior knee pain with resurfacing less revision rates with resurfacing inferior results with secondary resurfacing similar patient satisfaction rates trochlear design important: “patellar friendly” thinner anterior flange anatomic trochlear groove
Technique Guide Technique guides are not considered high yield topics for orthopaedic standardized exams including ABOS, EBOT and RC. TKA - Parapatellar Approach Derek T. Bernstein Stephen Incavo Recon - TKA Templating Technique Guide Technique guides are not considered high yield topics for orthopaedic standardized exams including ABOS, EBOT and RC. TKA - Varus Knee with Anterior Referencing and Gap Balancing Technique Derek T. Bernstein Stephen Incavo Recon - TKA Axial Alignment Technique Guide Technique guides are not considered high yield topics for orthopaedic standardized exams including ABOS, EBOT and RC. TKA with Computer Navigation & Sensor-Guided Assessment for Soft Tissue Balancing - Dr. William Gall William Gallivan Recon - TKA in Patella Baja (Prior HTO)
QUESTIONS 1 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ18.17) Which of the following will decrease the Q-angle when performing a total knee arthroplasty? QID: 212913 Type & Select Correct Answer 1 Medialization of the femoral component 7% (172/2610) 2 Medialization of the tibial component 6% (169/2610) 3 Medialization of the patellar component 75% (1964/2610) 4 Internal rotation of the femoral component 6% (150/2610) 5 Internal rotation of the tibial component 5% (137/2610) L 2 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ13.108) When performing a total knee arthroplasty on a 60-year-old female patient, a surgeon chooses not to resurface the patella. Instead, he performs a patelloplasty by excising the marginal osteophytes and reshaping the patella. All of the following statements comparing the results of patelloplasty to patella resurfacing are true EXCEPT: QID: 4743 Type & Select Correct Answer 1 There is no difference in relative risk of anterior knee pain. 44% (2718/6160) 2 There is no difference in relative risk for revision surgery involving the tibial and femoral components. 5% (313/6160) 3 There is an increased risk that she will need secondary resurfacing. 25% (1536/6160) 4 No difference in rates of patellar avascular necrosis or patellar tendon injury. 20% (1223/6160) 5 Total knee arthroplasty improved function regardless of whether the patella was resurfaced. 6% (340/6160) L 4 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic (OBQ13.105) Which of the following intra-operative errors most commonly leads to patellar maltracking during a total knee arthroplasty? QID: 4740 Type & Select Correct Answer 1 Using the gap balancing technique instead of measured resection technique 1% (33/5496) 2 Internal rotation of the femoral component 89% (4917/5496) 3 External rotation of the tibial component 5% (298/5496) 4 Lateralization of the femoral prosthesis 3% (148/5496) 5 Overresection of the patella 1% (68/5496) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ12.187) Which of the following intra-operative steps would put a patient at risk for lateral patellar maltracking during total knee arthroplasty (TKA)? QID: 4547 Type & Select Correct Answer 1 External rotation of the femoral component 8% (392/5185) 2 Medial placement of the patellar component 4% (195/5185) 3 Internal rotation of the tibial component 81% (4188/5185) 4 Lateral translation of the femoral component 3% (175/5185) 5 Superior placement of the patellar component 4% (186/5185) L 2 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ10.181) Internal rotation of the femoral component in primary total knee arthroplasty may lead to which of the following? QID: 3274 Type & Select Correct Answer 1 A net lateral patellar tilt and increased lateral subluxation 92% (5383/5843) 2 A decreased Q angle 4% (217/5843) 3 Patella baja 0% (28/5843) 4 A loose medial compartment and tight lateral compartment 3% (173/5843) 5 Balanced medial and lateral flexion gaps 0% (24/5843) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ09.89) Following a left total knee arthroplasty, all of the following can cause the condition seen in Figure A EXCEPT: QID: 2902 FIGURES: A Type & Select Correct Answer 1 Internal rotation of the femoral prosthesis 3% (96/3400) 2 Internal rotation of the tibial prosthesis 5% (161/3400) 3 Lateralization of the femoral prosthesis 79% (2691/3400) 4 Medialization of the tibial prosthesis 8% (262/3400) 5 Lateralization of the patellar prosthesis 5% (174/3400) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ09.242) A 66-year-old woman with genu valgum osteoarthritis undergoes total knee replacement. What technical error could lead to post-operative lateral patellar instability? QID: 3055 Type & Select Correct Answer 1 External rotation of the tibial component 2% (89/4085) 2 External rotation of the femoral component 5% (197/4085) 3 Internal rotation of the femoral component 90% (3694/4085) 4 Lateralization of the femoral component 1% (44/4085) 5 Medialization of the patellar component 1% (52/4085) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ08.185) A standard total knee is performed on a 56 year-old female using spinal anesthesia and a tourniquet. After cementation of all the components, the patella is noted to sublux laterally during range of motion. The alignment and rotation of the femoral, tibial, and patellar components all appear perfect. The surgeon should now: QID: 571 Type & Select Correct Answer 1 Perform a lateral release 10% (343/3585) 2 Revise tibial component into more external rotation 1% (18/3585) 3 Revise the femoral component into more external rotation 1% (30/3585) 4 Revise the patellar component to a more medial position on the native patella 2% (67/3585) 5 Reevaluate patellar tracking after deflation of the tourniquet 87% (3113/3585) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07HK.43) Which of the following aids in correction of patellar tracking after total knee arthroplasty (TKA)? QID: 6003 Type & Select Correct Answer 1 Internal rotation of the femoral component 5% (41/780) 2 Internal rotation of the tibial component 7% (56/780) 3 Increasing size of the tibial component 3% (21/780) 4 Medialization of the patellar component 83% (646/780) 5 Joint line elevation 2% (14/780) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ07.137) The posterior condylar axis may be used to determine the rotation of the femoral component in total knee arthroplasty. Which of the following describes the normal relation of the posterior condylar axis? QID: 798 Type & Select Correct Answer 1 Parallel to the transepicondylar axis 4% (152/4225) 2 Perpendicular to the anteroposterior axis (Whiteside's line) 4% (171/4225) 3 3 degrees externally rotated to the transepicondylar axis 33% (1390/4225) 4 3 degrees internally rotated to the transepicondylar axis 56% (2380/4225) 5 7 degrees externally rotated to the transepicondylar axis 3% (113/4225) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ06.162) Failure to identify a hypoplastic lateral condyle in a valgus knee will result in which of the following errors if a posterior condylar referencing guide is used for total knee arthroplasty? QID: 348 Type & Select Correct Answer 1 External rotation of the femoral component 10% (329/3312) 2 External rotation of the tibial component 1% (48/3312) 3 Internal rotation of the femoral component 86% (2848/3312) 4 Internal rotation of the tibial component 1% (49/3312) 5 Internal rotation of the tibial and femoral components 1% (19/3312) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ05.242) Internal rotation of the femoral component during total knee arthroplasty can result in which of the following? QID: 1128 Type & Select Correct Answer 1 Increased need for lateral release 87% (2503/2878) 2 Decreased post-operative pain 0% (7/2878) 3 Increased polyethylene thickness 1% (35/2878) 4 Decreased post-operative Q angle 9% (273/2878) 5 Elevation of the native joint line 2% (48/2878) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic (OBQ05.45) Malrotation of total knee components leading to patellar tracking problems is best diagnosed by what radiographic modality? QID: 81 Type & Select Correct Answer 1 3-joint standing x-rays 5% (185/3459) 2 dynamic examination under anesthesia with fluoroscopy 10% (350/3459) 3 CT scan of the knee 76% (2619/3459) 4 45 degree flexed PA x-rays of the knee 8% (280/3459) 5 magnetic resonance arthrogram of the knee 0% (6/3459) L 2 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ04.15) Which of the following factors MOST places the knee at risk of patellar maltracking in total knee arthroplasty? QID: 126 Type & Select Correct Answer 1 Thickness of patellar resection 2% (34/2214) 2 Cruciate retaining component 0% (9/2214) 3 Medial placement of patellar component 9% (192/2214) 4 Preoperative patellar tilt 9% (195/2214) 5 Lateral placement of patellar component 80% (1773/2214) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (OBQ04.155) Which of the following intra-operative techniques during total knee arthroplasty (TKA) decreases the need for lateral retinacular release? QID: 1260 Type & Select Correct Answer 1 Internal rotation of femoral component 5% (156/3133) 2 External rotation of femoral component 85% (2651/3133) 3 Internal rotation of tibial component 4% (110/3133) 4 Lateralization of patellar component 5% (157/3133) 5 Insertion of a posterior cruciate retaining device 2% (50/3133) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic
All Videos (8) Podcasts (1) 2020 Annual Holiday Knee & Hip Course New Implant Designs Have They Moved the Ball Forward - Michael D. Ries, MD Michael D. Ries Recon - TKA Patellofemoral Alignment B 5/3/2021 838 views 4.0 (1) Login to View Community Videos Login to View Community Videos ISTA: New Early-Career Webinar Series 2020 Variation of Lower Limb Alignment Between Static and Dynamic Measurements: A Comparative Study of Imaging Modalities in Medial UKR - Etienne Deroche Recon - TKA Patellofemoral Alignment B 3/3/2021 29 views 0.0 (0) Login to View Community Videos Login to View Community Videos ISTA: New Early-Career Webinar Series 2020 Total Knee Arthroplasty Functional Alignment Performed Under Robotic Assistance - Andrea Illuminati Recon - TKA Patellofemoral Alignment B 3/3/2021 55 views 5.0 (1) Recon | TKA Patellofemoral Alignment Recon - TKA Patellofemoral Alignment Listen Now 12:37 min 10/16/2019 646 plays 5.0 (2) See More See Less