Introduction Surgical option for knee arthritis when only one compartment of the knee is involved Epidemiology 5% of surgeries where knee arthroplasty is indicated are unicompartmental knee replacements location medial compartment is most common Types of implants fixed-bearing historical standard of care mobile-bearing pros weightbearing through the meniscus increases conformity and contact without increasing constraint decrease in wear pattern excellent survivorship out to the second decade cons technically demanding bearings can dislocate Advantages compared to TKA faster rehabilitation and quicker recovery less blood loss less morbidity less expensive preservation of normal kinematics theory is that retaining ACL, PCL and other compartments leads to more normal knee kinematics smaller incision less post-operative pain leading to shorter hospital stays compared to osteotomy faster rehabilitation and quicker recovery improved cosmesis higher initial success rate fewer short-term complications lasts longer easier to convert to a TKA Indications Indications controversial and vary widely as an alternative to total knee arthroplasty or osteotomy for unicompartmental disease classicaly reserved for older (>60), lower-demand, and thin (<82 kg) patients 6% of patient's meet the above criteria with no contraindications new effort to expand indications to include younger patients and patients with more moderate arthrosis Contraindications inflammatory arthritis ACL deficiency absolute contraindication for mobile-bearing UKA and lateral UKA controversial for medial fixed-bearing fixed varus deformity > 10 degrees fixed valgus deformity >5 degrees restricted motion arc of motion < 90° flexion contracture of > 5-10° previous meniscectomy in other compartment tricompartmental arthritis (diffuse or global pain) younger high activity patients and heavy laborers overweight patients (> 82 kg) grade IV patellofemoral chondrosis (anterior knee pain) Technique Procedural tips avoid overcorrections undercorrect the mechanical axis by 2-3 degrees overcorrection places excess load on unresurfaced compartment remove osteophytes (peripheral and notch) resect minimal bone avoid extensive releases avoid edge loading prevent tibial spine impingement with proper mediolateral placement avoid making a varus tibial cut which increases the chance for loosening use caution when placing the proximal tibial guide pins to avoid stress fractures correct varus deformity to 1-5 degrees of valgus Complications Stress fractures always involve tibia associated with high activity and patient weight clinically there will be a pain free interval followed by spontaneous pain with activity blood commonly found on joint aspiration Tibial component collapse poor mechanical properties of bone Outcomes Fixed-bearing 1st decade results 10-year survivorship from studies done in 1980s and 1990s ranges from 87.4% to 96% the standard faliure rate in the first decade is 1% 2nd decade results rapid decline in survivorship ranging from 79% to 90% Mobile-bearing excellent clinical results with 15-year survivorship reported at 93% Long-term results lateral compartment arthroplasties have equivalent results to medial revision rates are worse than total knee revision rates causes of late failure other compartment degeneration (idiopathic, over-correction, more common with mobile-bearing) component failure (overload due to under-correction) component loosening (common in fixed-bearing) patella impingement on femoral component (patella pain) polyethylene wear
QUESTIONS 1 of 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Previous Next This is an AAOS Self assessment question. Orthobullets was not involved into the editorial process, and does not have the ability to alter. If you prefer to hide SAE questions on topics simply turn them off in your Content Settings (SAE07HK.87) Figure 53a shows the AP radiograph of a 70-year-old patient who is scheduled to undergo unicompartmental knee arthroplasty. Figure 53b shows the immediate postoperative radiograph, and the radiograph shown in Figure 53c, obtained 6 months after surgery, shows a medial tibial plateau fracture. The etiology of the fracture is best related to Review Topic QID: 6047 FIGURES: A B C 1 marked osteoporosis. 14% (15/107) 2 reduced contact area of a unicompartmental knee arthroplasty for load transmission. 24% (26/107) 3 excessive medial placement of the tibial component of the unicompartmental knee arthroplasty. 17% (18/107) 4 multiple drill holes that violate the medial cortex. 34% (36/107) 5 osteonecrosis of the medial tibial plateau. 5% (5/107) N/A Select Answer to see Preferred Response PREFERRED RESPONSE 4 This is an AAOS Self assessment question. Orthobullets was not involved into the editorial process, and does not have the ability to alter. If you prefer to hide SAE questions on topics simply turn them off in your Content Settings (SAE07HK.29) Which of the following is the strongest contraindication to unicompartmental knee arthroplasty (UKA)? Review Topic QID: 5989 1 Patient age of younger than 60 years 1% (1/96) 2 Patient age of older than 80 years 7% (7/96) 3 Anterior cruciate ligament (ACL) deficiency 80% (77/96) 4 Varus deformity of 5 degrees 1% (1/96) 5 Outerbridge grade II chondromalacia of the patella 7% (7/96) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 3 This is an AAOS Self assessment question. Orthobullets was not involved into the editorial process, and does not have the ability to alter. If you prefer to hide SAE questions on topics simply turn them off in your Content Settings (SAE07HK.27) Figure 15 shows the radiograph of an active 60-year-old woman. Which of the following variables is considered the strongest contraindication to a unicompartmental knee arthroplasty in this patient? Review Topic QID: 5987 FIGURES: A 1 Obesity 6% (2/33) 2 Fixed varus deformity of more than 15 degrees 85% (28/33) 3 Five degree flexion contracture 6% (2/33) 4 Contralateral knee osteoarthritis 0% (0/33) 5 Joint subluxation of 5 mm 3% (1/33) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 2 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 (OBQ06.107) Which of the following benefits can be expected from unicompartmental knee arthroplasty compared to total knee arthroplasty for medial compartment knee arthritis? Review Topic QID: 293 1 Better clinical outcomes at one year follow-up. 2% (29/1393) 2 Greater survivorship rate at 10 year follow-up 1% (12/1393) 3 Faster postoperative rehabilitation 94% (1316/1393) 4 Better postoperative knee alignment 1% (19/1393) 5 Reduced risk of secondary surgery within the first year 1% (10/1393) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ07.20) All of the following are contraindications for a medial unicompartmental knee replacement EXCEPT? Review Topic QID: 681 1 ACL deficiency 3% (45/1711) 2 Anterior compartment osteophytes and pain beneath the patella 4% (69/1711) 3 Medial sided knee pain with medial and lateral compartment osteophytes and 3 degrees of varus deformity 11% (182/1711) 4 Lateral sided knee pain with degenerative changes isolated to the medial compartment and 7 degrees of varus deformity 10% (165/1711) 5 Flexion contracture of 3 degrees 73% (1246/1711) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 5 (OBQ09.60) A 61-year-old male had a minimally-invasive unicompartmental knee replacement 8 months ago. He did well until recently when he developed persistent right knee pain that is worse with weight bearing. He denies any fevers or recent trauma. He does report that he had been exercising more over the past few months in an attempt to lose weight. WBC, ESR and C-reactive protein levels are normal. An AP radiograph and bone scan are shown in Figure A and B. What is the most likely cause of his symptoms? Review Topic QID: 2873 FIGURES: A B 1 Component failure/ polyethylene failure 7% (142/2008) 2 Infection 1% (17/2008) 3 Pes anserine bursitis 3% (68/2008) 4 Stress fracture 88% (1766/2008) 5 Complex regional pain syndrome 0% (7/2008) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ04.25) With regards to unicompartmental knee arthroplasty, all of the following are true EXCEPT: Review Topic QID: 136 1 Females have a higher revision rate 14% (160/1117) 2 BMI greater than 32 is not a risk factor for early implant failure 45% (498/1117) 3 Presence of osteopenia contributes to premature implant failure 4% (40/1117) 4 Lateral compartment arthroplasties have higher failure rates than medial compartment arthroplasties 27% (297/1117) 5 Progressive arthritis within the remaining compartments of the knee is low 5 years post-operatively 10% (117/1117) ML 5 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ09.18) All of the following are contraindications to medial unicondylar knee arthroplasty EXCEPT: Review Topic QID: 2831 1 Flexion contracture greater than 10 degrees 4% (103/2861) 2 Varus deformity greater than 10 degrees not correctable with stress testing 4% (105/2861) 3 Lateral knee joint line pain 12% (345/2861) 4 Rheumatoid arthritis 6% (182/2861) 5 Osteonecrosis of the medial femoral condyle 74% (2113/2861) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 5 (OBQ08.255) A 40-year-old man has moderate lateral compartment arthritis several years after undergoing a partial lateral meniscectomy. He has a correctable 5 degree valgus knee deformity compared to his other limb. His patellofemoral and medial compartments do not show any radiographic signs of degenerative changes. His knee has full range of motion and is stable on exam. After failing nonoperative treatments, which surgical option is most likely to give him the best outcome? Review Topic QID: 641 1 Valgus producing high tibial osteotomy 3% (79/2736) 2 Varus producing distal femoral osteotomy 86% (2365/2736) 3 Total knee replacement 7% (200/2736) 4 Arthroscopic debridement and chondroplasty 3% (70/2736) 5 Tibial tubercle osteotomy with anteromedialization 0% (13/2736) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 2 (OBQ04.259) A 60-year-old male tennis player undergoes a unicompartmental knee arthroplasty (UKA) shown in Figures A and B. Which of the following statements regarding this procedure is true? Review Topic QID: 1364 FIGURES: A B 1 Compared to total knee arthroplasty (TKA), UKA more closely approximates native knee kinematics 87% (2266/2600) 2 Patients undergoing a UKA and TKA have equivalent blood loss and pain medication requirements 1% (32/2600) 3 Compared to their TKA counterparts, UKA patients have a slower return to function 0% (10/2600) 4 There is no difference in range of motion at short or long term follow-up when compared with TKA 9% (232/2600) 5 Postoperative hospital stay is equivalent for UKA and TKA patients 2% (51/2600) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (OBQ05.26) When performing a unicondylar knee replacement, a smaller incision without dislocation of the patella offers what advantage over a standard, patella-everting approach? Review Topic QID: 63 1 the option to convert to a total knee arthroplasty if needed 1% (8/823) 2 more anatomic positioning of the components 3% (28/823) 3 better ultimate range-of-motion 2% (16/823) 4 increased 10-year implant survival rate 1% (6/823) 5 improved rate of recovery 93% (762/823) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 5 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK
Login to View Community Videos Login to View Community Videos 2018 Winter SKS Meeting: Shoulder, Knee, & Sports Medicine Outpatient Knee Arthroplasty - Thomas M. Debarardino, MD (3.23, 2018 Winter SKS) Recon - Unicompartmental Knee Replacement 8/8/2018 207 views Login to View Community Videos Login to View Community Videos 2018 Winter SKS Meeting: Shoulder, Knee, & Sports Medicine Video Spotlight: Unicompartmental Knee Arthroplasty - Thomas Carter, MD (3.22, 2018 Winter SKS) Thomas Carter Recon - Unicompartmental Knee Replacement 8/8/2018 246 views Login to View Community Videos Login to View Community Videos 2017 Orthopaedic Summit Evolving Techniques Pro: Put in the Uni Knee: Are You Kidding?!?! - Adolph V. Lombardi Jr, MD Recon - Unicompartmental Knee Replacement 4/30/2018 171 views See More See Less
2018 HSS Holiday Knee & Hip Course 57F with Progressive Medial Knee Pain (C101102) Steven B. Haas Recon - Unicompartmental Knee Replacement 8/21/2018 6870 57 21 OA Bilateral Knee joint (C2204) Sanjiv Goel Recon - Unicompartmental Knee Replacement 4/19/2015 423 0 11 BILATERAL UKA (C1347) Surendra Shetty Recon - Unicompartmental Knee Replacement 12/7/2012 78 1 5