Which Criteria Can Be Used to Determine a “Good Candidate” for UKA?
There are probably more patients in your practice who are good candidates for unicompartmental knee arthroplasty (UKA) that you think. The key is to redefine who you consider to be a “good candidate.”
At the recent 9th Annual ICJR South Hip & Knee Course, Keith R. Berend, MD, said that the generally accepted 1989 definition of patient criteria for UKA  is problematic for many reasons, one of which is that applying the narrow criteria typically results in fewer than 10% of knee patients being candidates for the procedure. [2,3] Unless you have a very large knee replacement practice, you won’t be performing enough UKAs annually to become proficient in the technique, he said.
So, you have a choice: Don’t offer UKA at all, or expand your indications by considering the findings of a 1991 study from Neuffield Orthopaedic Centre in Oxford, UK.  The study authors concluded that criteria for UKA in patients with anteromedial osteoarthritis (OA) should be based solely on analysis of 3 radiographs: anteroposterior (AP), lateral, and AP stress view (Figure 1). 
Figure 1. Radiographic findings indicative of anteromedial osteoarthritis: An AP view showing bone-on-bone, full-thickness cartilage loss in the medial compartment (left). A lateral view showing a sclerotic defect in the bone anteromedially only; posterior bone stock is preserved (center). An AP stress view showing that the medial compartment opens partially while the lateral compartment remains normal (right).
The Neuffield Orthopaedic Centre’s criteria, Dr. Berend said, could increase the number of candidates for UKA in your practice to about 30% of those who present with knee pain and dysfunction. In his practice, patients with the radiographic findings described in Figure 1 are offered a UKA regardless of any other factors such as age, weight, activity level, or status of the patellofemoral joint. [5-8]
One concern surgeons may have is the reputation UKAs have for failing. But not all UKAs fail, Dr. Berend said, making that reputation unwarranted. He cited not only research from his own practice, but also research from Price et al , who found 91% UKA survivorship at 20 years, which is comparable to survivorship in total knee arthroplasty (TKA). In many cases, UKA was the definitive knee replacement.
Dr. Benend and his colleagues have found that compared with TKA patients, UKA patients have better early range of motion, shorter hospital stays, and improved functional scores, with no differences in return to work, return to sport, or Oxford score.  A multi-center study that included 2235 TKA patients and 605 UKA patients found a significantly lower overall complication rate for UKAs: 11% for TKA patients and 4.3% for UKA patients (P<0.001).  In addition, there were fewer manipulations under anesthesia, transfusions, and infections in the UKA patients. 
The bottom line, Dr. Berend said, is that UKA “is a great operation” that can be the definitive arthroplasty in more than 90% of patients; that results in better function and fewer residual symptoms than TKA; and that is suitable for young, active, and obese patients with anteromedial OA.
Click the image above to watch Dr. Berend’s presentation and learn more about UKAs.
Keith R. Berend, MD, is from JIS Orthopedics, New Albany, Ohio.
Disclosures: Dr. Berend has disclosed that he is a paid consultant for Engage Surgical and that he receives royalties and research support from and is a paid consultant for Zimmer Biomet.
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- White SH, Ludkowski PF, Goodfellow JW. Anteromedial osteoarthritis of the knee. J Bone Joint Surg Br. 1991 Jul;73(4):582-6. doi: 10.1302/0301-620X.73B4.2071640.
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- Berend KR, Lombardi AV Jr, Morris MJ, Hurst JM, Kavolus JJ. Does preoperative patellofemoral joint state affect medial unicompartmental arthroplasty survival? Orthopedics. 2011 Sep 9;34(9):e494-6. doi: 10.3928/01477447-20110714-39.
- Price AJ, Svard UA second decade lifetable survival analysis of the Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res . 2011 Jan;469(1):174-9. doi: 10.1007/s11999-010-1506-2.
- 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. doi: 10.1007/s11999-009-0731-z. Epub 2009 Feb 19.
- 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 Sep;27(8 Suppl):86-90. doi: 10.1016/j.arth.2012.03.022. Epub 2012 May 4.