General Information

Current scholarly publications conclude that the advantages of the UKA outweigh those of a Total Knee Arthroplasty (TKA) if done for the correct indications using a suitable surgical technique¹.

UKA could be used in at least 49-60% of operations where the TKA was used^2,3.

It is neither warranted nor suitable to do a TKA for every patient that presents with a focal Grade 4 Kellgren and Lawrence4 Osteoarthritis (OA) lesion (bone-on-bone degeneration). This is despite the higher incidence of complications of the UKA attributed to the inexperienced surgeon⁴.

The knee must be evaluated as suitable for a UKA, as treating every knee with a TKA is not acceptable due to the functional deficit created by the loss of the Anterior Cruciate Ligament (ACL) and can be functional for more than 20 years (93% survival over 20 years)5.

The thought of dealing with every knee without identifying the specific problem, and treating it using a TKA as the only solution, equates to the need for a heart transplant when you have a heart attack (a stent and bypass should be considered) with retention of the normal anatomy, especially the ACL⁶.

The result achieved in the long term in the specialised centres where the UKA procedure is often done achieves similar results in survival over 10, 15, and 20 years with better functional results (range of motion and activity level). The obvious advantages are discussed below with the primary goal being the preservation of normal knee anatomy and function. This allows the patient “normal” knee function with the ability to proceed to a TKA with failure of the UKA.

 The TKA should be used for the correct indications and as a salvage procedure of last resort.

UKA specific information

The knee presents in a phase of degeneration with the constitutional alignment causing a specific wear pattern with pain, function-loss and deformity.

The timing and election of the suitable arthroplasty is evaluated with the different options of treatment at the different stages of presentation.

When these lesions are focal areas of degeneration, they can be effectively treated with smaller procedures like the UKA with the various advantages as discussed below.

Advantages of UKA

● Retention of all the ligaments⁷

● Preservation of most of the anatomy (less destruction of bone)⁸

● Minimal knee incision with retention of normal proprioception^9,10

● Effectively resurfacing a single compartment and restoring balance and function to the joint¹¹

● UKA is functionally similar to a normal knee (far superior to a TKA). It is proven that 14-25% of TKA patients are dissatisfied with their prosthesis. The younger the patient, the more dissatisfaction (due to loss of function)¹²

● Less blood loss¹³

● Less immediate cost and overall cost to the health system¹⁴

● Less nursing and rehabilitation required¹⁵

● Improved quality of function e.g. stair-climbing and sports activities¹⁶

● Earlier independent ambulation, driving and earlier return to work¹⁷

● Complications are less grave and easier to deal with e.g. deep vein thrombosis (DVT), catastrophic embolism, death, amputation and infection¹⁸

● This solution allows for further treatment if the patient outlives the implant with e.g. a primary TKA¹⁹

● In the TKA cohort; 15% of the treated knees are painful for at least 2 years and 6% suffer from permanent pain; UKA has a 0.7% incidence of permanent pain²⁰

● The need for a revision of the contralateral Tibiofemoral joint OA is rare if the indications are correct (less than 5% over 20 years). Even with full thickness OA present on the Patellofemoral joint, it is seldom an indication for a TKA²¹

● UKA is currently done in the USA and Europe as a day procedure if the environment and support allows it.

Examples of knee arthroplasty options:

PRE-OP

 

            

 

For further information:
1. Ackroyd CE. Medial compartment arthroplasty of the knee. J Bone Joint Surg BR. 2003 Sep;85(7):937-42.
2. Cobb JP. Patient safety after partial and total knee replacement. Lancet. 2014 Oct 18;384(9952):1405-7.
3. Willis-Owen CA, Brust K, Alsop H, Miraldo M, Cobb JP. Unicondylar knee arthroplasty in the UK National Health Service: an analysis of candidacy, outcome and cost efficacy. Knee. 2009 Dec;16(6):473-8.
4. Braun HJ, Gold GE. Diagnosis of osteoarthritis: imaging. Bone. 2012 Aug;51(2):278-88.
5. Murray DW, Parkinson RW. Usage of unicompartmental knee arthroplasty. Bone Joint J. 2018 Apr 1;100-B(4):432-435.
6. Cobb JP. Resisting register’s pressure. The Partial Knee Meeting 2018, 25-26 January 2018, Bruges, Belgium.
7. Bruni D, Iacono F, Akkawi I, Gagliardi M, Zaffagnini S, Marcacci M. Unicompartmental knee replacement: a historical overview. Joints. 2013 Oct 24;1(2):45-7.
8. Pandit H, Jenkins C, Gill HS, Barker K, Dodd CA, Murray DW. Minimally invasive Oxford phase 3 unicompartmental knee replacement: results of 1000 cases. J Bone Joint Surg Br. 2011 Feb;93(2):198-204.
9. Emerson RH, Alnachoukati O, Barrington J, Ennin K. The results of Oxford unicompartmental knee arthroplasty in the United States: a mean ten-year survival analysis. Bone Joint J. 2016 Oct;98-B(10 Supple B):34-40.
10. Isaac SM, Barker KL, Danial IN, Beard DJ, Dodd CA, Murray DW. Does arthroplasty type influence knee joint proprioception? A longitudinal prospective study comparing total and unicompartmental arthroplasty. Knee. 2007 Jun;14(3):212-7.
11. Murray DW, Liddle AD, Dodd CA, Pandit H. Unicompartmental knee arthroplasty: is the glass half full or half empty? Bone Joint J. 2015 Oct;97-B(10 Suppl A):3-8. doi: 10.1302/0301-620X.97B10.36542. Erratum in: Bone Joint J. 2015 Dec;97-B(12):1732. Liddle, A [corrected to Liddle, A D].
12. Scott CE, Oliver WM, MacDonald D, Wade FA, Moran M, Breusch SJ. Predicting dissatisfaction following total knee arthroplasty in patients under 55 years of age. Bone Joint J. 2016 Dec;98-B(12):1625-1634.
13. Lombardi AV Jr, Berend KR, Walter CA, Aziz-Jacobo J, Cheney NA. Is recovery faster for mobile-bearing unicompartmental than total knee arthroplasty? Clin Orthop Relat Res. 2009 Jun;467(6):1450-7.
14. Slover J, Espehaug B, Havelin LI, Engesaeter LB, Furnes O, Tomek I, Tosteson A. Cost-effectiveness of unicompartmental and total knee arthroplasty in elderly low-demand patients. A Markov decision analysis. J Bone Joint Surg Am. 2006 Nov;88(11):2348-55.
15. Lygre SH, Espehaug B, Havelin LI, Furnes O, Vollset SE. Pain and function in patients after primary unicompartmental and total knee arthroplasty. J Bone Joint Surg Am. 2010 Dec 15;92(18):2890-7.
16. Sueyoshi T, Lackey WG, Malinzak RA, Meding JB, Farris A, Davis KE, Ritter MA. Predicting Pain in Total and Partial Knee Arthroplasty. OJO. 2015 June;Vol.05:No.06, Paper ID:57232.
17. Witjes S, Gouttebarge V, Kuijer PP, van Geenen RC, Poolman RW, Kerkhoffs GM. Return to Sports and Physical Activity After Total and Unicondylar Knee Arthroplasty: A Systematic Review and Meta-Analysis. Sports Med. 2016 Feb;46(2):269-92.
18. Wiik AV, Manning V, Strachan RK, Amis AA, Cobb JP. Unicompartmental knee arthroplasty enables near normal gait at higher speeds, unlike total knee arthroplasty. J Arthroplasty. 2013 Oct;28(9 Suppl):176-8.
19. Siman H, Kamath AF, Carrillo N, Harmsen WS, Pagnano MW, Sierra RJ. Unicompartmental Knee Arthroplasty vs Total Knee Arthroplasty for Medial Compartment Arthritis in Patients Older Than 75 Years: Comparable Reoperation, Revision, and Complication Rates. J Arthroplasty. 2017 Jun;32(6):1792-1797.
20. Santoso MB, Wu L. Unicompartmental knee arthroplasty, is it superior to high tibial osteotomy in treating unicompartmental osteoarthritis? A meta-analysis and systematic review. J Orthop Surg Res. 2017 Mar 28;12(1):50.
21. Tuncay İ, Bilsel K, Elmadağ M, Erkoçak ÖF, Aşçı M, Şen C. Evaluation of mobile bearing unicompartmental knee arthroplasty, opening wedge, and dome-type high tibial osteotomies for knee arthritis. Acta Orthop Traumatol Turc. 2015;49(3):280-7.