Patient satisfaction after primary total and unicompartmental knee
arthroplasty: An age-dependent analysis
A Von Keudell
⁎
, S Sodha, J Collins, T Minas, W Fitz, AH Gomoll
Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, United States
Orthopedic and Arthritis Center for Outcomes Research, Brigham and Women's Hospital, Harvard Medical School, Boston, United States
a b s t r a c t
a r t i c l e i n f o
Article history: Received 21 March 2013
Received in revised form 2 June 2013 Accepted 5 August 2013
Keywords:
Total knee arthroplasty
Unicompartmental knee arthroplasty Satisfaction
Age
Background:Patient-related outcomes have become the focus of increased attention when assessing knee arthroplasty.
Methods:We retrieved questionnaires from 485 (584 knees) patients at a minimum of 3 years after undergoing primary knee arthroplasty. We excluded bilateral knee arthroplasty, leaving 141 UKA and 245 TKA who rated their satisfaction and expectation regarding pain, range of motion (ROM), daily living function (DLF), return to recreational activity (RRA) and ability to kneel (ATK) on a scale of 0 (worst) to 10 (best). We further collected data on pain level and the modified Cincinnati rating scale. Range of motion was documented pre- and postop-eratively at a minimum of six months. The cohort was subdivided into three age groups and compared with each other (Group 1:b55, n = 113; Group 2: 55–64, n = 117; Group 3: 65+, n = 155).
Results:Average satisfaction with pain, ROM and ATK for patients under 55 was higher for UKA than for TKA. PatientsN65 with TKA were on average more satisfied than patients with UKA in these three items. However, patients under 55 with UKA were up to 2.9 times more likely to have their expectations met when compared to patients receiving TKA. Patients with UKA under 55 rated their joint as good/excellent in 96.0% versus patients in the same age group with TKA in 81.0%.
Conclusions:We found that overall, younger patients who were treated with UKA demonstrated higher satisfac-tion scores in most subsets when compared with the patients of the same age group who received TKA.
© 2013 Elsevier B.V. All rights reserved.
1. Introduction
There still remains controversy regarding the best treatment options for patients with knee osteoarthritis[1]. Some authors suggest that the long-term survival rate of unicompartmental knee arthroplasty (UKA) is not comparable with total knee arthroplasty (TKA) and revision surgery after UKA has a similar complexity to revision procedures after primary TKA[2]. Although recent studies have shown excellent long-term results using a minimally invasive technique for UKA implantation [3], many orthopedic surgeons favor primary TKA for its easier surgical technique and alleged similar outcome.
Most studies use revision surgery as an endpoint or evaluate the functional outcome whereas the subjective component of patients is usually neglected[4–8]. Literature has demonstrated a discrepancy between clinician and patient ratings of quality of life[9]. Subjective patient satisfaction is the ultimate goal of each orthopedic surgeon performing a procedure for osteoarthritis in the knee.
Studies have documented a patient satisfaction rate with pain relief between 72% and 86% after primary TKA with a recent implant design,
pertinent patient selection and surgical technique[10–12]. Conversely, it has been reported that up to 93% of patients receiving a UKA were satisfied with their outcome [13–15]. However, there is scarce data comparing the two procedures that investigated subjective pain and function, especially when subdivided into different age groups. Patient satisfaction and revision surgery appear to be among the most important key factors for successful management of patients with osteoarthritis in the knee.
This study tries to compare comprehensive subjective and functional outcomes of patients who underwent knee arthroplasties in our institu-tion at different age groups after a minimum of 3 years. We hypothe-sized that there was no age dependent satisfaction rates in patients undergoing UKA or TKA.
2. Material and methods
2.1. Participants
We reviewed all 735 patients (779 knees) who underwent medial UKA or TKA at our institution for the treatment of symptomatic knee osteoarthritis between January 2002 and January 2007 by two of the authors (T.M., W.F.). The study was approved by the Institutional Review Board.
⁎ Corresponding author at: Brigham and Women's Hospital, 75 Francis Street, 02115 Boston, United States. Tel.: +1 617 732 9812.
E-mail address:[email protected](A. Von Keudell). 0968-0160/$–see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.knee.2013.08.004
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We excluded patients with less than a 3 year follow-up, with lan-guage barriers, and non-primary TKA/UKA, as well as patients who had a cerebrovascular event, Alzheimer's or were deceased. Further ex-clusion criteria, such as bilateral (simultaneously or staged) procedures, and TKA and contralateral UKA were applied to establish a homogenous group. The group was then divided into TKA and UKA patients (Fig. 1). The two surgeons (T.M., W.F.) implanted 141 UKA, (52 Miller Galante unicompartmental knee replacement (Zimmer, Warsaw, IN), 72 Oxford Knee Phase III (Biomet Ltd., Bridgend, UK), and 14 Sigma HP Replacement Knee System (DePuy, Leeds, UK)) and 245 received TKA (PFC Sigma, DePuy, Leeds, UK). All unicompartmental knee replace-ments were PCL retaining implants using either measured resection, gap balancing technique or both together.
2.2. Questionnaire
Every patient was contacted either by phone or mail to complete a questionnaire consisting of a Visual Analogue Pain scale, the modified Cincinnati score[16], as well as questions regarding their satisfaction in respect to pain, motion, daily living function, return to sport activities and ability to kneel on a scale from 0 to 10 (0 = not satisfied, 10 = very satisfied). Furthermore, patients were asked to comment on the current status of their affected joint in comparison to before the surgery, whether they would choose to have the surgery again and how they rated the result of the surgery. Lastly, the participants responded with a binary answer option (yes/no) whether their expectations had been met in regards to pain, motion, daily living function, return to rec-reational activities and their ability to kneel on the operated knee.
Data was retrieved from the medical record regarding their pre- and postoperative range of motion (ROM) at a minimum of 3 years after the index surgery.
2.3. Statistics
We investigated the association between each outcome and proce-dure (UKA vs. TKA)first in an unadjusted analysis. For continuous out-comes (satisfaction, pain in joint, modified Cincinnati Health Survey, difference in ROM) we calculated the mean in each group and conducted
an independent samplest-test to test for a difference between groups. For categorical outcomes (expectation and satisfaction cut-offs) we calcu-lated percentages for each group and performed chi-square tests of inde-pendence. A p-value ofb0.05 was accepted as statistically significant.
We then used multivariable regression to adjust for potential founding of the relationship between procedure and outcome. For con-tinuous outcomes we used linear regression and for dichotomous outcomes we used logistic regression. We adjusted for age group, sex, surgeon, and time since surgery. We formally tested whether the rela-tionship between outcome and procedure depended on age group with an interaction term using a significance cut-off of p = 0.1 for inter-action. For outcomes without statistically significant interaction we re-ran the multivariable model removing the interaction term. Statistics were performed using SPSS version 15.0 (SPSS Science Inc., Chicago, Illinois).
2.4. Source of funding
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this arti-cle. This research was supported by the Brigham and Women's Hospital, Department of Orthopedic Surgery Program for Research Incubation and Development.
3. Results
Out of the total of 609 UKA and TKA patients, 485 questionnaires (79.6%) were re-trieved. We excluded 99 patients who had a bilateral procedure, leaving 245 TKA and 141 UKA for analysis (Fig. 1). The mean age at surgery was 61.8 years (SD = 11.2); 65% of the population was female and 35% was male. Baseline covariates by procedure are given inTable 1.
3.1. Satisfaction
Overall, 94.7% of TKA patients rated their joints as much or somewhat better, whereas 96.4% of the UKA group reported this. Of all TKA patients, 91.4% would choose to undergo the surgery again in comparison to 95.0% in the UKA group. Furthermore, 88.1% of TKA pa-tients rated their results as good/excellent in contrast to 94.3% of papa-tients who underwent UKA (p = 0.046).
For patients with a TKA under the age of 55, 81.0% rated their joints as good/excellent versus 96.0% of patients with a UKA in the same age group. Between 55 and 64 years, 89.0% of TKA patients rated their joint as good/excellent versus 93.3% of patients with a UKA. Beyond 65, 91.0% of TKA patients rated their joint as good/excellent in comparison to 93.6% of UKA patients (Table 2).
3.2. Satisfaction scores
The general unadjusted comparison between TKA and UKA did not yield any statisti-cally significant differences in the satisfaction scores.
We used multivariable regression models to estimate the relative contribution of de-mographic and clinical factors to patient reported outcomes. We included procedure (TKA vs UKA), age group, sex, surgeon, and time since surgery and the interaction between pro-cedure and age group. We found a significant interaction between age group and proce-dure for satisfaction with pain (p = 0.10), motion (p = 0.10) and ability to kneel (p = 0.04), indicating that the relationship between procedure and outcome depends on age group. For all three measures satisfaction was higher for UKA vs TKA in patients b55 and lower in UKA vs TKA for patients 65+ (Table 3).
Fig. 1.Description of the selection procedure.
Table 1
Patient demographics for UKA and TKA patients.
TKA UKA p-Value
Age (mean (sd)) 62.6 (11.1) 60.2 (11.2) 0.042 Age group 0.128 b55 64 (56.6%) 49 (43.4%) 55–64 72 (61.5%) 45 (38.5%) 65+ 108 (69.7%) 47 (30.3%) Sex 0.162 Males 80 (58.8%) 56 (41.2%) Females 165 (66.0%) 85 (34.0%)
Specifically, higher satisfaction scores were found for UKA than for TKA (8.4 vs. 7.8) in the patient group under the age of 55 years in the domain of“pain”, whereas in patients be-tween 55 and 64 and above 65 years, satisfaction scores were higher for TKA (p = 0.10) (Fig. 2). The average satisfaction score for“motion”for patients under the age of 55 years and 55–64 years was higher for UKA than for TKA (8.4 vs. 7.6 and 8.5 vs. 7.8), while for pa-tients above 65 years, satisfaction was slightly higher for TKA (p = 0.10). Similar trends continued in the domain of“ability to kneel”for patients under 55, in which they scored higher in the UKA group than in the TKA group (5.8 vs. 4.2). The difference was less pro-nounced for those aged 55–64 years (5.9 vs. 5.3), and for patients above 65 years, satisfac-tion was lower for UKA compared to TKA (4.7 vs. 5.4) (p = 0.04).
For the remaining outcomes we re-ran the models removing the interaction term and assessed whether there was an association between outcome and procedure.
3.3. Expectations met
In unadjusted analysis expectations were more likely to be met for UKA patients in the domains“motion”(94% of UKA patients reported that expectations were met vs. 78% of TKA patients, pb0.0001)“daily living function”(94% vs. 87%, p = 0.03) and“return to recreational activities”(89% vs. 79%, p = 0.01) (Table 4).
In multivariable models, we found significant interaction between age group and pro-cedure for the outcome“expectations met—kneeling”(p = 0.01). For those under 55, pa-tients with a UKA had 2.9 times the odds of having expectations met relative to those with a TKA (95% CI: (1.3–6.5)); for patients 55–64 those with a UKA had 1.5 times the odds of having expectations met relative to those with a TKA (95% CI: (0.6–3.3)),finally for pa-tients 65+ those with a UKA had lower odds of having expectations met relative to those with a TKA (OR 0.5, 95% CI (0.3–1.1)). Patients under 55 had higher odds of having expectations met for UKA vs. TKA for pain, daily living function, and return to recreational activities compared to the other age groups, however these interactions did not reach sta-tistical significance.
After removing the interaction term we found that those with UKA had 5.3 times the odds of having expectations met with regards to motion (pb0.001), 2.0 times for pain (p = 0.095), 2.5 times for daily living function (p = 0.03) and 2.4 times for return to rec-reational activities (p = 0.006) compared to patients with TKA when adjusted for age, sex, surgeon and time since surgery.
As a secondary analysis we assessed the association between outcome and age, ad-justed for procedure (UKA vs. TKA), sex, surgeon, and time since surgery. We found that younger patients were, on average, less satisfied with regards to daily living and return to recreational activities. Similarly, younger patients were also less likely to have their ex-pectations met with regards to return to recreational activities (p = 0.001) in comparison to older patients. Those in the 65+ age group had 3.4 times the odds of having expecta-tions met compared to those in theb55 group and had similar odds of having expectaexpecta-tions met compared to those in the 55–64 age group (OR = 1.1).
3.4. Range of motion
The mean postoperativeflexion of UKA compared to TKA among all patients in our study was different and averaged at 123° vs. 114° (pb0.001). Within each of the two co-horts (UKA and TKA), the youngest patient groups (b55 years) had lower postoperative range of motion than the overall average (122.8° vs 123.3° for UKA and 110° versus 114° for TKA) (Table 5).
4. Discussion
We compared self-reported satisfaction and expectation rates com-bined with pre- and postoperative range of motion of UKA with TKA and stratifiedfindings according to their age, sex and time since surgery. General comparison between the two procedures did not yield any sig-nificant differences in satisfaction scores, however when subdivided into age groups we found higher satisfaction scores for patients under 55 years in the domains of “pain”,“motion”,“ability to kneel” and mean satisfaction scores. Further, we found that younger patients with UKA had consistently higher odds of having their expectations met than TKA patients in all analyzed domains. Additionally, subjective rating of the surgery, VAS score and modified Cincinnati score complemented the comparison with a minimum of 3 years follow-up. Although no statistically significant differences were found in the VAS and modified Cincinnati scores between different age groups, a consis-tently higher percentage of patients that underwent UKA rated their new joints as good to excellent, much better than before and would choose to have the surgery in comparison to patients with TKA.
4.1. High versus low volume center, community versus university setting
Data was retrieved from one single specialized high-volume institu-tion and two experienced arthroplasty surgeons. This might have biased our results towards better outcomes and higher satisfaction rates. Several studies have shown that high volume centers have fewer complications,
Table 2
Patient satisfaction in patients with a TKA versus UKA given in numbers and percentages.
UKA TKA
Age groups Excellent/good Fair/poor Total Excellent/good Fair/poor Total b55 47 96.0% 2 4.1% 49 51 81.0% 12 19.0% 63 55–64 42 93.3% 3 6.7% 45 64 89.0% 8 11.1% 72 65+ 44 93.6% 3 6.4% 47 99 91.7% 9 8.3% 108 Total 133 8 141 214 29 243 Table 3
Adjusted mean satisfaction scores of different age and procedure groups, adjusted for age, sex, surgeon, time since surgery, and interaction between age and procedure.
Variable Label b55 TKA b55 UKA 55–64 TKA 55–64 UKA 65+ TKA 65+ UKA p-Value for interaction
Satisfaction—pain (0–10, 10 best) 7.8 (7.3, 8.4) 8.4 (7.8, 9.0) 8.7 (8.2, 9.2) 8.3 (7.7, 8.9) 9.1 (8.7, 9.5) 8.6 (8.0, 9.2) 0.0999 Satisfaction—motion (0–10, 10 best) 7.6 (7.1, 8.1) 8.4 (7.8, 9.0) 7.8 (7.3, 8.3) 8.5 (7.9, 9.1) 8.9 (8.5, 9.3) 8.6 (7.9, 9.2) 0.0976 Satisfaction—daily living (0–10, 10 best) 8.3 (7.8, 8.7) 8.4 (7.9, 8.9) 8.7 (8.2, 9.1) 8.4 (7.9, 9.0) 9.1 (8.8, 9.5) 8.7 (8.2, 9.2) 0.3755 Satisfaction—sport (0–10, 10 best) 7.1 (6.4, 7.7) 7.7 (7.0, 8.5) 8.0 (7.3, 8.6) 8.1 (7.3, 8.9) 8.3 (7.7, 8.8) 8.0 (7.2, 8.7) 0.3496 Satisfaction—kneeling (0–10, 10 best) 4.2 (3.3, 5.1) 5.8 (4.8, 6.7) 5.3 (4.4, 6.1) 5.9 (4.8, 6.9) 5.4 (4.7, 6.2) 4.7 (3.7, 5.7) 0.0377 Mean of satisfaction items 7.1 (6.6, 7.6) 7.7 (7.2, 8.3) 7.7 (7.3, 8.2) 7.9 (7.3, 8.4) 8.3 (7.8, 8.7) 7.7 (7.1, 8.2) 0.0509 Pain in joint (0–10, 10 worst) 1.9 (1.4, 2.4) 1.7 (1.1, 2.2) 1.3 (0.8, 1.8) 1.6 (1.0, 2.3) 1.4 (1.0, 1.8) 1.1 (0.5, 1.7) 0.4823 Modified Cincinnati Health Survey (1–10, 10 best) 7.3 (6.7, 7.8) 7.6 (7.0, 8.2) 7.8 (7.3, 8.3) 7.6 (7.0, 8.2) 8.0 (7.6, 8.5) 7.4 (6.8, 8.0) 0.2076
interaction p=0.0999
Satisfaction - Pain: mean and 95% CI
Procedure TKA UKA
Sat is fac ti on Pai n 0 1 2 3 4 5 6 7 8 9 10 <55 55-64 65+
TKA UKA TKA UKA TKA UKA
8.68 9.11
7.85 8.41 8.33 8.61
less revision rates, lower rates of venous thromboembolism, lower mor-tality rates and shorter stays in the hospital in comparison to low volume centers[16–18]. Improved outcomes of high volume centers, such as ours, might translate into higher satisfaction scores in the patient popula-tion, even though more complex cases, such as younger patients or patients with more comorbidities can counteract that bias.
4.2. Patient satisfaction and expectation
Patient satisfaction in regards to the surgical intervention and overall outcome was higher in the UKA compared to the TKA group, especially in the age group under 55 years (81.0% in TKA vs. 96.0% in UKA). Our study confirms the lower end of outcomes of other studies that have reported that 11% to 19% of primary TKA patients are not sat-isfied[11,12,19–23]. It remains unclear why such a high percentage of patients are not content with their outcome; Lopez et al.[24]suggested
a correlation with the preoperative condition of the patient and his or her psychosocial function.
Preoperative expectations are an area of renewed research interest, as it is believed to be the best predictor for patient satisfaction. Possibly we are not including important preoperative measurements that would allow us to quantify the postoperative satisfaction ratings better, such as unachievable expectations, i.e. running a marathon.
Mahomed et al.[25]assessed patient expectations preoperatively in 103 THA and 89 TKA primary procedures. Seventy-six percent of pa-tients expected to have no pain after recovery from surgery, but only 40% expected to have no functional limitations. This could mean that older patients have lower expectations in regards to functional capacity in comparison to younger active patients. This is in line with our results as older patients were generally more satisfied than younger patients regardless of the procedure.
National registries have not found significant differences in the satis-faction and functional scores[2,22]. The study performed by Robertsson et al.[2,22]found no difference in satisfaction scores between primary UKA and TKA, however revised UKA patients appeared to be more satisfied than revised TKA patients. We have not gathered data on this and further research is needed in this area as more revisions are predicted over the next decade[26]. In European countries it is antici-pated that UKA surgeries will diminish although there is an increased need due to probable comparable outcomes between TKA and UKA. Lack of experience and volume might lead to a negative shift in out-comes that is hidden in the published data[22,27].
In our study we found subtle subjective differences in favor of UKA between various age groups in the comparison to TKA regarding satisfaction and expectation outcome scores. Thisfinding was most pro-nounced in the young patient population requiring a knee arthroplasty and expectations were more likely to be met in UKA.
It might account for the fact that young high-demand patients with less severe symptoms pre-operatively have higher expectations of returning to high impact recreational activities in comparison to the older patient group. This could be a reason for the low satisfaction scores among all young patients receiving knee arthroplasty in comparison to the older age group. This might also stem from the fact that older pa-tients have lower expectations towards recreational activities, i.e. playing golf versus playing tennis. In line with these assumptions is the fact that the oldest patient population receiving a TKA was among the most satisfied of all.
4.3. Range of motion
The mean postoperativeflexion of UKA compared to TKA among all patients in our study was significantly higher in the UKA patient group in all age groups. Thisfinding is comparable to other studies that report-ed on TKA outcomes[28–30].
4.4. Return to recreational activities
In a study by Hopper and Leach[31], it was found that a bigger pro-portion of patients with UKA did return to the same level of sports activ-ity in comparison to TKA. Furthermore, 42.9% of patients in the TKA group and 24.1% of patients in the UKA group reported pain during sports after surgery; 80.3% of the patients in the TKA group and 88.2% of the patients in the UKA group felt that surgery had increased or maintained their sporting ability; however, no difference was found be-tween the two procedures in the Oxford knee scores. This is comparable to our study as UKA patients were more likely to have their expectations met in regards to return to recreational activities. This effect was more pronounced when subdivided into the different age groups. Similar
findings have been confirmed in other studies in regards to return to sports and recreational activity after UKA[31–35].
Table 4
Patient response rates, n (%) in respect to expectations and satisfaction with their current result.
Variable TKA UKA p-Value
Expectations met—daily living 0.0306
No 31 (12.7%) 8 (5.8%)
Yes 213 (87.3%) 131 (94.2%)
Expectations met—kneeling 0.1726
No 103 (44.8%) 51 (37.5%)
Yes 127 (55.2%) 85 (62.5%)
Expectations met—motion b.0001
No 54 (22.1%) 8 (5.7%)
Yes 190 (77.9%) 133 (94.3%)
Expectations met—pain 0.1158
No 28 (11.5%) 9 (6.5%)
Yes 216 (88.5%) 129 (93.5%)
Expectations met—sport 0.0139
No 51 (21.4%) 16 (11.4%)
Yes 187 (78.6%) 124 (88.6%)
Rate joint now 0.7741
Much better 196 (80.7%) 120 (85.1%)
Somewhat better 34 (14.0%) 16 (11.3%)
About the same 6 (2.5%) 2 (1.4%)
Somewhat worse 3 (1.2%) 2 (1.4%)
Much Worse 4 (1.6%) 1 (0.7%)
Choose to have surgery again 0.6373
Definitely yes 206 (84.8%) 121 (85.8%) Probably yes 16 (6.6%) 13 (9.2%) Completely unsure 7 (2.9%) 2 (1.4%) Probably not 8 (3.3%) 3 (2.1%) Definitely not 6 (2.5%) 2 (1.4%) Rate result 0.1666 Excellent 171 (70.1%) 107 (75.9%) Good 44 (18.0%) 26 (18.4%) Fair 19 (7.8%) 7 (5.0%) Poor 10 (4.1%) 1 (0.7%) Table 5
Range of motion in degrees of different age groups and procedures (mean, stdev, p-values are only given for the comparison of pre- and post-operativeflexion).
Age & procedure group Pre ROM extension Post ROM extension Pre ROM flexion Post ROM flexion p-Value TKA all 2.8 (8.0) 0.6 (2.9) 114.8 (14.2) 113.8 (14.3) 0.299 TKAb55 5.6 (15.0) 1.3 (5.2) 112.5 (22.2) 110.1 (19.8) 0.412 TKA 55–64 1.6 (3.2) 0.5 (2.0) 114.1 (10.4) 114.3 (10.8) 0.991 TKAN65 2.1 (3.5) 0.4 (1.4) 116.4 (10.5) 115.4 (12.4) 0.408 UKA all 0.1 (0.6) 0.2 (0.9) 121.3 (9.6) 123.3 (5.8) 0.061 UKAb55 0.1 (0.3) 0.2 (1.1) 119.2 (9.6) 122.8 (5.9) 0.044 UKA 55–64 0.0 (0.0) 0.1 (0.3) 122.7 (10.2) 124.1 (5.5) 0.462 UKAN65 0.3 (1.0) 0.3 (1.0) 121.9 (9.0) 123.0 (5.9) 0.594
4.5. Limitations
We were not able to differentiate between unicompartmental ver-sus tricompartmental disease patterns in the selection of the patient population. This might have biased our results as our selection criteria diverged but has been previously addressed in the literature. Rougraff et al.[30]compared UKA to TKA and found no difference in survivorship between the two groups. In line with ourfinding was that UKA demon-strated better range of motion and ambulatory motion in comparison to TKA. Similarfindings were reported by Newman et al.[34], who com-pleted a prospective randomized study with UKA versus TKA. Up to 15 years the UKA group had significantly higher outcome scores than TKA patients with similar failure rates. It was not our intention to repeat this study in a prospective randomized fashion in patients with unicompartmental OA receiving either UKA or TKA, specifically since we would not get this study approved in our institution nor would we have been able to recruit enough patients to study the influence of age groups for this trial. We are a known center for UKA and patients are referred to us for this procedure. Therefore, we decided to retrospec-tively compare patients who underwent UKA or TKA and prospecretrospec-tively collect satisfaction outcome measures. Another limitation is a signifi -cant age difference between the two groups. Inherent to the study design, there might be recall bias since patients were asked to answer several subjective scores retrospectively.
5. Conclusion
Overall, we report high patient satisfaction with both procedures. Younger patients undergoing UKA had better satisfaction and a higher likelihood of having their expectations met than TKA patients of the same age group. The older the patient group was, the less significant the differences. In fact, the oldest patient group was more satisfied when undergoing TKA, possibly owing to the greater likelihood of subclinical osteoarthritis in the other compartments that might lead to residual symptoms when treated with UKA. Therefore, the major role for UKA would be in younger patients with higher expectations.
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