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 risk factors penetrating posterior tibial cortex with guide pin, placing guide pin medial in periphery, re-drilling for guide pin, and under-sized tibial component Intra-operative fractures associated with forceful impacting of implant 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 Patellofemoral arthroplasty (PFA) has good outcomes for isolated patellofemoral arthritis Previous generation designs (i.e. inlay style) exhibited high rates of patellar instability Newer generation designs (i.e. outlay style) replaces entire anterior trochlear surface and minimizes risk of patellar instability Long term mode of failure remains progression of tibiofemoral arthritis 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 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Previous Next 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 You have 100% on this question. Just skip this one for now. Take This Question Anyway (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 | Tested Concept QID: 2873 FIGURES: A B Type & Select Correct Answer 1 Component failure/ polyethylene failure 7% (156/2155) 2 Infection 1% (17/2155) 3 Pes anserine bursitis 3% (73/2155) 4 Stress fracture 88% (1893/2155) 5 Complex regional pain syndrome 0% (7/2155) L 1 C Select Answer to see Preferred Response SUBMIT RESPONSE 4 You have 100% on this question. Just skip this one for now. Take This Question Anyway (OBQ09.18) All of the following are contraindications to medial unicondylar knee arthroplasty EXCEPT: Review Topic | Tested Concept QID: 2831 Type & Select Correct Answer 1 Flexion contracture greater than 10 degrees 4% (108/3065) 2 Varus deformity greater than 10 degrees not correctable with stress testing 4% (114/3065) 3 Lateral knee joint line pain 12% (374/3065) 4 Rheumatoid arthritis 7% (203/3065) 5 Osteonecrosis of the medial femoral condyle 73% (2249/3065) L 2 C Select Answer to see Preferred Response SUBMIT RESPONSE 5 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK You have 100% on this question. Just skip this one for now. Take This Question Anyway (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 | Tested Concept QID: 641 Type & Select Correct Answer 1 Valgus producing high tibial osteotomy 3% (94/2972) 2 Varus producing distal femoral osteotomy 86% (2556/2972) 3 Total knee replacement 7% (215/2972) 4 Arthroscopic debridement and chondroplasty 3% (81/2972) 5 Tibial tubercle osteotomy with anteromedialization 1% (15/2972) L 2 C Select Answer to see Preferred Response SUBMIT RESPONSE 2 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK You have 100% on this question. Just skip this one for now. Take This Question Anyway 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 Content Settings. (SAE07HK.29) Which of the following is the strongest contraindication to unicompartmental knee arthroplasty (UKA)? Review Topic | Tested Concept QID: 5989 Type & Select Correct Answer 1 Patient age of younger than 60 years 2% (3/187) 2 Patient age of older than 80 years 8% (15/187) 3 Anterior cruciate ligament (ACL) deficiency 78% (145/187) 4 Varus deformity of 5 degrees 3% (5/187) 5 Outerbridge grade II chondromalacia of the patella 9% (16/187) L 2 E Select Answer to see Preferred Response SUBMIT RESPONSE 3 You have 100% on this question. Just skip this one for now. Take This Question Anyway 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 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 | Tested Concept QID: 5987 FIGURES: A Type & Select Correct Answer 1 Obesity 9% (9/101) 2 Fixed varus deformity of more than 15 degrees 75% (76/101) 3 Five degree flexion contracture 2% (2/101) 4 Contralateral knee osteoarthritis 2% (2/101) 5 Joint subluxation of 5 mm 12% (12/101) L 1 E Select Answer to see Preferred Response SUBMIT RESPONSE 2 You have 100% on this question. Just skip this one for now. Take This Question Anyway (OBQ07.20) All of the following are contraindications for a medial unicompartmental knee replacement EXCEPT? Review Topic | Tested Concept QID: 681 Type & Select Correct Answer 1 ACL deficiency 3% (49/1857) 2 Anterior compartment osteophytes and pain beneath the patella 4% (72/1857) 3 Medial sided knee pain with medial and lateral compartment osteophytes and 3 degrees of varus deformity 11% (197/1857) 4 Lateral sided knee pain with degenerative changes isolated to the medial compartment and 7 degrees of varus deformity 10% (181/1857) 5 Flexion contracture of 3 degrees 73% (1353/1857) L 2 C Select Answer to see Preferred Response SUBMIT RESPONSE 5 You have 100% on this question. Just skip this one for now. Take This Question Anyway (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 | Tested Concept QID: 293 Type & Select Correct Answer 1 Better clinical outcomes at one year follow-up. 2% (34/1595) 2 Greater survivorship rate at 10 year follow-up 1% (14/1595) 3 Faster postoperative rehabilitation 94% (1504/1595) 4 Better postoperative knee alignment 1% (22/1595) 5 Reduced risk of secondary surgery within the first year 1% (12/1595) L 1 C Select Answer to see Preferred Response SUBMIT RESPONSE 3 You have 100% on this question. Just skip this one for now. Take This Question Anyway (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 | Tested Concept QID: 63 Type & Select Correct Answer 1 the option to convert to a total knee arthroplasty if needed 1% (12/991) 2 more anatomic positioning of the components 4% (35/991) 3 better ultimate range-of-motion 2% (21/991) 4 increased 10-year implant survival rate 1% (6/991) 5 improved rate of recovery 92% (913/991) L 1 D Select Answer to see Preferred Response SUBMIT RESPONSE 5 You have 100% on this question. Just skip this one for now. Take This Question Anyway (OBQ04.25) With regard to unicompartmental knee arthroplasty, all of the following are true EXCEPT: Review Topic | Tested Concept QID: 136 Type & Select Correct Answer 1 Females have a higher revision rate 14% (183/1286) 2 BMI greater than 32 is not a risk factor for early implant failure 44% (564/1286) 3 Presence of osteopenia contributes to premature implant failure 4% (50/1286) 4 Lateral compartment arthroplasties have higher failure rates than medial compartment arthroplasties 28% (355/1286) 5 Progressive arthritis within the remaining compartments of the knee is low 5 years post-operatively 10% (127/1286) L 5 D Select Answer to see Preferred Response SUBMIT RESPONSE 4 You have 100% on this question. Just skip this one for now. Take This Question Anyway (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 | Tested Concept QID: 1364 FIGURES: A B Type & Select Correct Answer 1 Compared to total knee arthroplasty (TKA), UKA more closely approximates native knee kinematics 87% (2413/2772) 2 Patients undergoing a UKA and TKA have equivalent blood loss and pain medication requirements 1% (39/2772) 3 Compared to their TKA counterparts, UKA patients have a slower return to function 1% (14/2772) 4 There is no difference in range of motion at short or long term follow-up when compared with TKA 9% (243/2772) 5 Postoperative hospital stay is equivalent for UKA and TKA patients 2% (54/2772) L 1 C Select Answer to see Preferred Response SUBMIT RESPONSE 1
All Videos (12) Podcasts (0) Login to View Community Videos Login to View Community Videos 2018 Orthopaedic Summit Evolving Techniques Evolving Technique: Converting The UKA To A Total Knee: When, How - Tips & Tricks - Michael J. Kaplan, MD (OSET 2018) Michael Kaplan Recon - Unicompartmental Knee Replacement 7/25/2019 460 views Login to View Community Videos Login to View Community Videos 2018 Orthopaedic Summit Evolving Techniques Evolving Technique: Lateral UKA Makes The Difference In Young Patients With Return To Sports - Kevin D. Plancher, MD, MPH (OSET 2018) Kevin Plancher Recon - Unicompartmental Knee Replacement 7/25/2019 129 views Login to View Community Videos Login to View Community Videos 2018 HSS Holiday Knee & Hip Course UKA Tips and Tricks - Michael M. Alexiades MD Michael M. Alexiades Recon - Unicompartmental Knee Replacement 6/4/2019 349 views See More See Less
2019 Annual Holiday Knee & Hip Course Knee pain in 79M s/p Unicondylar Knee Replacement (C101294) Michael P. Ast Recon - Unicompartmental Knee Replacement 10/1/2019 9903 32 8 2018 HSS Holiday Knee & Hip Course 57F with Progressive Medial Knee Pain (C101102) Steven B. Haas Recon - Unicompartmental Knee Replacement 8/21/2018 6967 57 21 OA Bilateral Knee joint (C2204) Recon - Unicompartmental Knee Replacement 4/19/2015 427 1 11 See More See Less