108 – Do patients undergoing UKA, including patellofemoral joint arthroplasty, have a different VTE risk profile compared to TKA?

108 – Do patients undergoing UKA, including patellofemoral joint arthroplasty, have a different VTE risk profile compared to TKA?

Tad Gerlinger, Ivan Bohacek, David Campbell.

Response/Recommendation: The incidence of symptomatic venous thromboembolism (VTE) is low in both unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) patients, deep venous thrombosis (DVT) and pulmonary embolism (PE) occur in up to 1.6% and 0.13% of UKA patients. Most studies had a trend of decreased VTE risk following UKA compared to TKA but were underpowered, only registry studies were sufficiently powered and showed a VTE risk ratio (RR) of 0.39 (0.27-0.57). There is a paucity of data on patellofemoral joint arthroplasty (PFJA) and VTE risk.

Strength of Recommendation: Moderate.

Rationale: UKA is an alternative option to TKA for the surgical management of symptomatic osteoarthritis and accounted for 2.7% of all primary TKA reported in the American Joint Replacement Register1, 5.6% of the Australian Register2, 8% of the Swedish Register3, and 9.1% of the British Register4.

A vast body of literature has reported comparable or better clinical UKA outcomes compared to TKA5–7, fewer early postoperative complications6,8–12, fewer early reoperations8,10–12, and decreased mortality6,8,13 but a greater revision rate compared to TKA1,2,4,8,13. VTE related to UKA is reported less frequently and symptomatic VTE occurs in 0.41-1.6%14,15 of patients including symptomatic DVT in 0.28 – 1.6%14–17, and PE in 0.13%14. Several large consecutive series report an absence of symptomatic VTE17, or asymptomatic VTE following UKA18. Conversely, Koh et al., reported a consecutive series of 70 patients without VTE symptoms following UKA, but 26% had a VTE lesion identified with multidetector row computer tomography (CT), and all resolved without thromboprophylaxis nor thrombotic treatment19.

There are no randomized controlled trials (RCT) powered to examine uncommon sentinel events such as VTE and mortality following UKA compared to TKA, but every study has reported similar or improved complication rates, VTE incidence, and mortality in UKA patients compared to TKA patients. Systemic review methodologies with meta-analysis remain underpowered to measure these events. Wilson et al., used a systemic review of RCT of more than 50 patients, nationwide databases, joint registries, and large cohort studies to compare UKA to TKA6. In that review and meta-analysis the UKA/TKA VTE RR was 0.39 (0.27 – 0.57, p < 0.001) derived from the British Registry8, and four American national databases10,13,16,20, that include 32,711 UKA and 228,499 TKA patients.

Wilson et al., identified two RCT including 614 patients and four large cohort studies including 574 patients that were underpowered to compare VTE incidence in UKA and TKA6. Additionally, Beard et al.7, conducted a multicenter RCT of 528 patients with 2 VTE events in both cohorts, Schmidt-Braekling et al.17, added a RCT of 112 patents to the literature, and Brown et al.21, examined 605 UKA and 22,235 TKA in an institutional database with a trend toward less VTE related to UKA.

Liddle et al.8, used propensity-matched UKA and TKA patients in the National Joint Registry for England and Wales from 2003-2012 and included 25,334 UKA and 75,996 TKA. The VTE RR was 0.42 (0.34 – 0.52, p<0.001). Mortality risk was significantly decreased for UKR patients (0.23 (0.11–0.50) at 30 days and 0.47 (0.31–0.69) at 90 days). Mortality is multifactorial and may be related to fatal pulmonary embolism and other factors such as myocardial infarction and stroke which were both decreased in the UKA group; odds ratio 0.53 (0.31 – 0.90) and 0.37 (0.16, 0.86) respectively.

Di Martino et al.11, reported on 6,453 UKA and 54,012 TKA from the Italian Registro Implantologia Protesica Ortopedica (RIPO) database from 2000-2017; DVT was reported in 0.03% of UKA and 0.2% of TKA patients.

The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) has been interrogated over three time periods. Duchman et al.16, used propensity-matched UKA and TKA patients in the ACS NSQIP database from 2005 to 2011 and included 1,588 UKA and 1,588 TKA; the VTE RR was 0.32 (0.16 – 0.66, p<0.02). Drager et al.10, examined 36,274 TKA and 1,340 UKA non-matched patients in the ACS NSQIP database from 2011 to 2012; the VTE RR was 0.33 (0.16 – 0.69). Courtney et al.20, examined 49,136 TKA and 1,351 UKA non-matched patients in the ACS NSQIP database from 2014 to 2015; the VTE RR was 0.44 (0.24 – 0.82).

Bolognesi et al.13, examined 65,505 TKA and 3,098 UKA American Medicare patients from 2000 -2009; after multivariable adjustment, UKA patients had no significant risk differential of VTE (adjusted hazard ratio [HR] =0.86; 95% CI = 0.57 to 1.29) or mortality (adjusted HR = 0.75; 95% CI = 0.50 to 1.11). Hansen et al.12, used propensity-matched UKA and TKA patients in the 2002-2011 USA Medicare database and 2004-2012 MarketScan database and report on 4,414 matched UKA Medicare patients and 20,721 MarketScan patients. The VTE RR for TKA patients was 1.67 (1.16-2.38, p 0.006) in the Medicare cohort and 1.69 (1.45-1.96, p<0.001) in the MarketScan cohort, and mortality RR was 2.63 (1.35-5.00), p 0.004) in the Medicare cohort and 2.08 (1.96-2.022, p <0.001) in the MarketScan cohort.

Enhanced recovery after surgery (ERAS) following TKA has potential to decrease VTE risk, potentially approximating the risk to UKA patients who typically have a rapid recovery pathway. UKA patients have similar prothrombotic serum markers following surgery22 and the addition of rapid mobilization, decreased tourniquet use, and multimodal analgesia protocols could diminish the prothrombotic potential of TKA compared to UKA. Petersen et al.14, report a VTE incidence of 0.41% following 3927 UKA which was comparable to 0.39% in fast-tracked TKA patients23 over the same time period.

PFJA are used less frequently and account for 0.36 to 1.2% of knee arthroplasties2,4, and the incidence of VTE related to PFJA is less well described. Tarassoli et al.24, performed a meta-analysis of PFJA outcomes and identified only one study reporting one postoperative DVT in 56 PFJA (1.8%)25. No additional reports of VTE following PFJA were identified.


1.         The AJRR Annual Report. Accessed September 21, 2021. https://www.aaos.org/registries/publications/ajrr-annual-report/

2.         AOANJRR. Hip, Knee & Shoulder Arthroplasty: 2020 Annual Report. Accessed September 21, 2021. https://aoanjrr.sahmri.com/documents/10180/689619/Hip%2C+Knee+%26+Shoulder+Arthroplasty+New/6a07a3b8-8767-06cf-9069-d165dc9baca7

3.         Robertsson O, Lidgren L, Sundberg M, W-Dahl A. The Swedish Knee Arthroplasty Register – Annual Report 2018.; 2018.

4.         Register NJR. National Joint Registry. 17th Annual Report. Reports, Publications and Minutes. Accessed September 21, 2021. https://www.njrcentre.org.uk/njrcentre/Reports-Publications-and-Minutes

5.         Fabre-Aubrespy M, Ollivier M, Pesenti S, Parratte S, Argenson J-N. Unicompartmental Knee Arthroplasty in Patients Older Than 75 Results in Better Clinical Outcomes and Similar Survivorship Compared to Total Knee Arthroplasty. A Matched Controlled Study. J Arthroplasty. 2016;31(12):2668-2671. doi:10.1016/j.arth.2016.06.034

6.         Wilson HA, Middleton R, Abram SGF, et al. Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis. BMJ. 2019;364:l352. doi:10.1136/bmj.l352

7.         Beard DJ, Davies LJ, Cook JA, et al. The clinical and cost-effectiveness of total versus partial knee replacement in patients with medial compartment osteoarthritis (TOPKAT): 5-year outcomes of a randomised controlled trial. Lancet. 2019;394(10200):746-756. doi:10.1016/S0140-6736(19)31281-4

8.         Liddle AD, Judge A, Pandit H, Murray DW. Adverse outcomes after total and unicompartmental knee replacement in 101,330 matched patients: a study of data from the National Joint Registry for England and Wales. Lancet. 2014;384(9952):1437-1445. doi:10.1016/S0140-6736(14)60419-0

9.         Courtney PM, Froimson MI, Meneghini RM, Lee G-C, Della Valle CJ. Should Medicare Remove Total Knee Arthroplasty From Its Inpatient Only List? A Total Knee Arthroplasty Is Not a Partial Knee Arthroplasty. J Arthroplasty. 2018;33(7S):S23-S27. doi:10.1016/j.arth.2017.11.028

10.       Drager J, Hart A, Khalil JA, Zukor DJ, Bergeron SG, Antoniou J. Shorter Hospital Stay and Lower 30-Day Readmission After Unicondylar Knee Arthroplasty Compared to Total Knee Arthroplasty. J Arthroplasty. 2016;31(2):356-361. doi:10.1016/j.arth.2015.09.014

11.       Di Martino A, Bordini B, Barile F, Ancarani C, Digennaro V, Faldini C. Unicompartmental knee arthroplasty has higher revisions than total knee arthroplasty at long term follow-up: a registry study on 6453 prostheses. Knee Surg Sports Traumatol Arthrosc. Published online August 1, 2020. doi:10.1007/s00167-020-06184-1

12.       Hansen EN, Ong KL, Lau E, Kurtz SM, Lonner JH. Unicondylar Knee Arthroplasty Has Fewer Complications but Higher Revision Rates Than Total Knee Arthroplasty in a Study of Large United States Databases. J Arthroplasty. 2019;34(8):1617-1625. doi:10.1016/j.arth.2019.04.004

13.       Bolognesi MP, Greiner MA, Attarian DE, et al. Unicompartmental knee arthroplasty and total knee arthroplasty among Medicare beneficiaries, 2000 to 2009. J Bone Joint Surg Am. 2013;95(22):e174. doi:10.2106/JBJS.L.00652

14.       Petersen PB, Jørgensen CC, Gromov K, Kehlet H, Lundbeck Foundation Centre for Fast-track Hip and Knee Replacement Collaborative Group. Venous thromboembolism after fast-track unicompartmental knee arthroplasty – A prospective multicentre cohort study of 3927 procedures. Thromb Res. 2020;195:81-86. doi:10.1016/j.thromres.2020.07.002

15.       Willis-Owen CA, Sarraf KM, Martin AE, Martin DK. Are current thrombo-embolic prophylaxis guidelines applicable to unicompartmental knee replacement? J Bone Joint Surg Br. 2011;93(12):1617-1620. doi:10.1302/0301-620X.93B12.27650

16.       Duchman KR, Gao Y, Pugely AJ, Martin CT, Callaghan JJ. Differences in short-term complications between unicompartmental and total knee arthroplasty: a propensity score matched analysis. J Bone Joint Surg Am. 2014;96(16):1387-1394. doi:10.2106/JBJS.M.01048

17.       Schmidt-Braekling T, Pearle AD, Mayman DJ, Westrich GH, Waldstein W, Boettner F. Deep Venous Thrombosis Prophylaxis After Unicompartmental Knee Arthroplasty: A Prospective Study on the Safety of Aspirin. J Arthroplasty. 2017;32(3):965-967. doi:10.1016/j.arth.2016.09.018

18.       Lombardi AV, Berend KR, Tucker TL. The incidence and prevention of symptomatic thromboembolic disease following unicompartmental knee arthroplasty. Orthopedics. 2007;30(5 Suppl):46-48.

19.       Koh IJ, Kim JH, Kim MS, Jang SW, Kim C, In Y. Is Routine Thromboprophylaxis Needed in Korean Patients Undergoing Unicompartmental Knee Arthroplasty? J Korean Med Sci. 2016;31(3):443-448. doi:10.3346/jkms.2016.31.3.443

20.       Courtney PM, Froimson MI, Meneghini RM, Lee G-C, Della Valle CJ. Can Total Knee Arthroplasty Be Performed Safely as an Outpatient in the Medicare Population? J Arthroplasty. 2018;33(7S):S28-S31. doi:10.1016/j.arth.2018.01.003

21.       Brown NM, Sheth NP, Davis K, et al. Total knee arthroplasty has higher postoperative morbidity than unicompartmental knee arthroplasty: a multicenter analysis. J Arthroplasty. 2012;27(8 Suppl):86-90. doi:10.1016/j.arth.2012.03.022

22.       Su EP, Mount LE, Nocon AA, Sculco TP, Go G, Sharrock NE. Changes in Markers of Thrombin Generation and Interleukin-6 During Unicondylar Knee and Total Knee Arthroplasty. J Arthroplasty. 2018;33(3):684-687. doi:10.1016/j.arth.2017.10.016

23.       Petersen PB, Lindberg-Larsen M, Jørgensen CC, Kehlet H, Lundbeck Foundation Centre for Fast-track Hip and Knee Arthroplasty collaborating group. Venous thromboembolism after fast-track elective revision hip and knee arthroplasty – A multicentre cohort study of 2814 unselected consecutive procedures. Thromb Res. 2021;199:101-105. doi:10.1016/j.thromres.2021.01.003

24.       Tarassoli P, Punwar S, Khan W, Johnstone D. Patellofemoral arthroplasty: a systematic review of the literature. Open Orthop J. 2012;6:340-347. doi:10.2174/1874325001206010340

25.       Kooijman HJ, Driessen APPM, van Horn JR. Long-term results of patellofemoral arthroplasty. A report of 56 arthroplasties with 17 years of follow-up. J Bone Joint Surg Br. 2003;85(6):836-840.

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