Does Surgical Technique Influence Patient Satisfaction after the Triathlontm Knee Replacement?
Corresponding author:Gordon Bannister, Department of Orthopaedics, North Bristol NHS Trust, 19, Cranbrook Road, Redland, Bristol, BS67BL, UK. Tel: 0044 117 9248440; Email: email@example.com
Patient satisfaction varies after primary total knee arthroplasty (TKA), is established within three to six months of surgery and may be better with the TriathlonTM TKA. Early recovery is improved by the subvastus approach and intra-operative, local anaesthetic field block and patient satisfaction by patellar resurfacing. Our hypothesis is that the combination of these techniques improves patient satisfaction with the TriathlonTM further.
A questionnaire including patient satisfaction and the Oxford Knee Score (OKS) was sent to 267 consecutive patients who had received a TriathlonTM TKA by the above standardised technique under the care of one surgeon comparing the results with a contemporanous series of the same TKA from the same centre.
The response rate to the questionnaires was 68.9%. 11.6% of patients were not satisfied. They were significantly more likely to have a lower OKS, higher OKS pain score, less improvement in the OKS pain score, less improvement in walking distance, greater reliance on walking aids, more post-operative complications and less fulfillment of their expectations than those who were satisfied.
The TriathlonTM gives high levels of patient satisfaction but the surgical technique used here does not improve upon results reported elsewhere.
Material and Methods
We explored this hypothesis by recording the patient reported results of the primary TriathlonTM TKAs performed on 261 patients (282 TKAs) at one elective orthopedic center over a four year period. A questionnaire was sent to each patient at a mean 2.5 years (0.6 – 4.5) after TKA. The 20 patients with bilateral TKAs were sent a separate questionnaire for each knee. At follow up 14 patients had died (one with bilateral TKAs) leaving 247 consecutive patients (267 TKAs) for inclusion in the study. The outcome measures were the patient-reported satisfaction , the Oxford knee score (OKS) , pain, walking distance, use of walking aids, rate of recovery, return to work and fulfilment of pre-operative expectations [10,12]. Patient reported satisfaction comprised four categories. The very satisfied and satisfied were combined into one category denoted as ‘Satisfied’ and the unsure and dissatisfied into ‘Not satisfied’ .
Surgery was performed either by or under the direct supervision of the senior author. In all cases, a posterior cruciate-retaining TriathlonTM TKA system (Stryker, Kalamazoo, MI, USA) was implanted under tourniquet with a subvastus approach, patellar resurfacing and intraoperative field block of 40ml 0.25% Bupivacaine with Adrenaline (1 in 200,000). 20ml was infiltrated into the posterior capsule before cementation and a further 20ml to the incised capsule and skin edges while the cement was polymerizing. The tourniquet was released immediately after cementation of the prostheses and field block before wound closure and hemostasis secured. A standardized post-operative rehabilitation regime was used for all patients aimed at mobilization the day after surgery. Thromboprophylaxis with 150mg aspirin was used for 35 days.
Results were compared with a contemporaneous study from the same unit  in which the TriathlonTM TKA was implanted by a variety of techniques by a number of surgeons and the published literature (Table 1)
The study was approved as a service evaluation audit by the institutional clinical audit department and informed, written consent was obtained from all participants included in this study. The nature of this approval for the study required that a single questionnaire be sent once to each patient. No further questionnaires or telephone contact were permitted and non-responders could not be pursued further.
Data were analysed using SPSS version 20.0 (SPSS Inc, Chicago, Illinois). The assumption of normal distribution was tested using a Kolmogorov-Smirnov test. Continuous variables were compared between groups with a two-tailed t-test for normally distributed and a Mann-Whitney U test for non-parametric data. The chi-squared test was used to compare categorical data between groups, however if the expected number was less than five a Fisher’s Exact test was used. Correlation was assessed using Spearman’s rank test. All tests were two-tailed and a p-value of <0.05 was considered statistically significant.
184 questionnaires were returned from 168 patients giving an overall response rate of 68.9%. Not all questionnaires were fully completed therefore response rates for different parts of the questionnaire varied. There was no significant difference in patient demographics between responders and non-responders.
38.6% (n=68) patients reported no knee pain, 56.8% (n=100) minimal or no pain (0-1 out of 10) and 19.9% (n=35) moderate to severe pain (5-10 out of 10). In 8.5% (n=15), pain was unchanged or worse post-operatively. The mean postoperative OKS was 34.9 (n=182, SD 10.6, range 4-48) and median 39 (n=182, IQR 29-43). The mean walking distance increased in 65.9% (n=108) patients and deteriorated in 6.7% (n=11). Overall 42.6% (n=72) could walk more than 1km post-operatively compared with 12.7% (n=21) pre-operatively. 76.2% (n=32) of patients who could walk more than 100m pre-operatively could walk more than 1km post-operatively but 23.1% (n=9) of patients walking less than 10m pre-operatively were still confined to this distance. 56.8% patients reported additional co-morbidities including back pain, hip pain and respiratory or cardiovascular disease that restricted their walking distance. A walking aid was used by 58.0% (n=105) of patients pre-operatively and 48.6% (n=88) post-operatively. Post-operatively, a walking aid was used by 90.0% (n=9) of pre-operative frame users, compared to 58.9% (n=56) of pre-operative stick users and 30.3% (n=23) of patients who had previously used no aids. 70% (n=7) of pre-operative frame users still used a frame post-operatively, compared to 2.1% (n=2) pre-operative stick users and 2.6% (n=2) of patients who had used no aids. Patients using no walking aids pre-operatively were more likely to deteriorate than those using them (30.3% vs. 1.9%, p<0.0001). The median time taken to return to current function was between three and six months. 48.5% (n=83) reached their current level of function within 6 months and 75.4% (n=129) in less than 1 year. 24.6% (n=42) took more than 1 year to return to their current level of function. At the time of questionnaire 50.6% (n=84) were still noticing improvements in their knee. 6.0% (n=47) patients worked pre-operatively of whom 76.6% (n=36) returned post-operatively. 46.4% (n=83) reported that their knee had limited their ability to work pre-operatively. Only 40.5% (n=15) of those who returned to work resumed full time or normal duties and 13.5% (n=5) part time, light duties. No patient not working pre-operatively worked post-operatively. In patients aged under 65 there were 64.6% (n=31) who worked pre-operatively, 83.9% (n=26) of whom returned post-operatively.68.6% (n=120) of all patients reported being unable to do activities or hobbies that they wanted to pre-operatively compared to 45.2% (n=76) post-operatively.
Overall 21.5% (n=38) thought that the operation had not met their expectations almost 45% of whom (n= 17) were not satisfied with their TKA. 79.5% (n=132) expected pain relief and 44.6% (n=74) improvement in mobility or activity. Patients who reported that the operation had met their expectations had a better OKS (38.2 vs. 22.3, p<0.0001) and greater improvement in pain score (6.9 vs. 2.6, p<0.0001) than those whose expectations had not been met. We considered that 10.2% (n=17) aspired to unrealistic expectations given the limitations of TKA. They expected ‘to be normal’, ‘a normal knee’, ‘a normal life’, ‘to walk perfectly normally’, ‘to regain full mobility’, ‘to be as agile as pre-degenerative changes’, ’to be fully functional’, ‘it would be perfect’, ‘to be complete pain free’ and ‘to do anything with it’. Despite this 58.8% (n=10) of these thought that the operation had met their expectations.
47.9% (n=70) patients were very satisfied, 40.4% (n=59) were satisfied, 4.1% (n=6) were unsure and 7.5% (n=11) were dissatisfied. Overall 88.4% (n=129) were satisfied and 11.6% (n=17) were not satisfied. Patients who were satisfied had a higher OKS (p<0.001), lower post-operative pain score (p<0.001), greater improvement in walking distance (p<0.001), used walking aids less frequently (p=0.003), reported fewer post-operative complication (p=0.02), fewer further procedures on their TKA (p=0.004) and continuing improvement in their TKA (p<0.001), felt that their knee was better than before the operation (p<0.001), with hindsight would have the operation again ( p=0.007), would recommend the operation to a friend ( p=0.002) and had more of their expectations met by the operation (p=0.002) (Table 2). There was no significant difference between the pre-operative pain scores, age, gender or operated side between those who would be satisfied and those who would not (Table 2).
Retrieval in the literature varies from 29%  to 94%  with a mean of 77% and was relatively low in this study because of the restriction of the institutional approval to a single postal contact. As in previous work, lack of patient satisfaction was associated with pain and function [2,10,12-14] , complications [2,13,14] and unfulfilled expectation [9,12,14,5,15].
The OKS [2, 6, 17], walking , rate of recovery [9, 10] and return to work  and recreational activity  were comparable to other reports. Scott et al  (2012) from Edinburgh, Scotland, UK and Kim et al  (2015) from Seoul, Korea both stratified respectively 17 and 11 aspirations of patients and the degree to which they were met. Ability to perform acts of daily living and pain relief were common to the first four aspirations of both. The Scottish patients prioritized walking without aids and negotiation of stairs whilst the Koreans favored high flexion activities. Negotiation of stairs and high flexion activity were realised least frequently in both studies. The TriathlonTM TKR does not achieve the higher flexion it was designed to deliver .
Patient satisfaction is one of the main aims of TKR but varies over time  and in different studies of close temporal relationship from the same center. In Edinburgh, Scotland (Table 1), a rate of satisfaction of 83% with the Kinemax Plus and Triathlon in a retrospective review  increased to 93% and 98%  respectively in a controlled trial suggesting that the Hawthorne effect of following up patients carefully to assess outcome improves satisfaction
All patients in this study who were not satisfied failed to have their expectations satisfied even though they were met more frequently in this series than in other studies [15,16]. Many authors suggest that expectations can be managed by appropriate informed consent before surgery but retention of the information from this can be as low as 21% .
The strength of this study is the standardization of prosthesis and surgical technique, the identification of persistent inability to walk distances if surgery is delayed until the preoperative distance is less than 10m and the association of continuing improvement with patient satisfaction. It is the only study to standardize both the prosthesis and surgical technique. The weakness is the retrieval rate and that it is a retrospective Level 4 review.
The standardization of technique and the availability of a contemporary study  from the same institution using the same prosthesis but different operative techniques disprove the hypothesis that a combination of a subvastus approach and perioperative local anesthetic field block with patellar resurfacing improves patient satisfaction after the TriathlonTM TKA.
The implications of this study are that in current practice, 90% of patients should be satisfied after TKA. There is potential to improve this by individually targeted informed consent to clarify patient expectation provided patients retain the information and improving the technical performance of TKA to minimize post-operative complications and further surgery.
- National Joint Registry for England and Wales Knees – All Procedures – Activities.
- Baker PN, van der Meulen JH, Lewsey J, Gregg PJ. The role of pain and function in determining patient satisfaction after total knee replacement. J Bone Joint Surg Br 2007 89(7): 893-900.
- Robertsson O, Dunbar M, Pehrsson T, Knutson K, Lidgren L. Patient satisfaction after knee arthroplasty: A report on 27,372 knees operated on between 1981 and 1995 in Sweden. Acta Orthop Scand 2000 71(3): 262-267.
- Kahlenberg CA, Nwachukwu BU, McLawhorn AS, Cross MB, Cornell CN, et.al. Patient Satisfaction After Total Knee Replacement: A Systematic Review. HSS J 2018 14 (2):192-201.
- Gandhi R, Davey JR, Mahomed NN. Predicting patient dissatisfaction following joint replacement surgery. J Rheumatol. 2008 35(12):2415 -2418.
- Hamilton DF, Burnett R, Patton JT, Howie CR, Moran M, et.al. Implant design influences patient outcome after total knee arthroplasty: a prospective randomised controlled trial. Bone Joint J. 2015 97 (1):64-70.
- Wu Y, Zeng Y, Bao X, Xiong H, Hu Q, et.al. Comparison of mini-subvastus approach versus medial parapatellar approach in primary total knee arthroplasty. Int J Surg 2018 57: 15-21.
- Wylde V, Lenguerrand E, Gooberman-Hill R, Beswick AD, Marques E, et.al. Effect of local anaesthetic infiltration on chronic postoperative pain after total hip and knee replacement: The APEX randomised controlled trials. Pain. 2015 156(6):1161-1170.
- Williams DP, O’Brien S, Doran E, Price AJ, Beard DJ, et.al. Early postoperative predictors of satisfaction following total knee arthroplasty. Knee. 2013 20(6):442-446.
- Scott CEH, Howie CR, MacDonald D, Biant LC. Predicting dissatisfaction following total knee replacement: A prospective study of 1217 patients. J Bone Joint Surg Br 2010 92: 1253-1258.
- Dawson J, Fitzpatrick R, Murray D, Carr A. Questionnaire on the perceptions of patients about total knee replacement. J Bone Joint Surg Br 80: 63-69.
- Noble PC, Conditt MA, Cook KF, Mathis KB. The John Insall Award: Patient expectations affect satisfaction with total knee arthroplasty. Clin Orthop Relat Res. 2006 452:35-43
- Wylde V, Trela-Larsen L, Whitehouse MR, Blom AW. Preoperative psychosocial risk factors for poor outcomes at 1 and 5 years after total knee replacement. Acta Orthop 2017 88(5):530-536.
- Jacobs CA, Christensen CP. Factors influencing patient satisfaction 2 – 5 years after primary total knee arthroplasty. J Arthroplasty. 2014 29(6):1189-1191.
- Nilsdotter AK, Toksvig-Larsen S, Roos EM. Knee arthroplasty: are patients’ expectations fulfilled? A prospective study of pain and function in 102 patients with 5-year follow-up. Acta Orthop 2009 80: 55-61.
- Scott CE, Clement ND, MacDonald DJ, Hamilton DF, Gaston P, et.al. Five-year survivorship and patient-reported outcome of the Triathlon single-radius total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2015 23: 1676 -1683.
- Foote JA, Smith HK, Jonas SC, Greenwood R, Weale AE. Return to work following knee arthroplasty. Knee. 2010 17(1):19-22.
- Scott CE, Bugler KE, Clement ND, MacDonald D, Howie CR, et.al. Patient expectations of arthroplasty of the hip and knee. J Bone Joint Surg Br 2012 94:974 -981.
- Kim SJ, Bamne A, Song YD, Kang YG, Kim TK. Patients still wish for key improvements after total knee arthroplasty. Knee Surg Relat Res 2015 27: 24-33.
- Mehin R, Burnett RS, Brasher PMA. Does the new generation of high-flex knee prostheses improve the post-operative range of movement? A meta-analysis. J Bone Joint Surg Br 2010 92: 1429-1434.
- Clement ND, Bardgett M, Weir D, Holland J, Gerrand C, et.al. Three groups of dissatisfied patients exist after total knee arthroplasty: early, persistent, and late. J Bone Joint Surg Br 2018 100:161-169.
- Sherlock A, Brownie S. Patients’ recollection and understanding of informed consent: a literature review. ANZ J Surg. 2014 84: 207- 210.
- Anderson JG, Wixson RL, Tsai D, Stulberg SD, Chang RW. Functional outcome and patient satisfaction in total knee patients over the age of 75. J Arthroplasty. 1996 11(7): 831-840.
- Hawker G, Wright J, Coyte P, Paul J, Dittus R, et.al. Health-related quality of life after knee replacement. J Bone Joint Surg Am. 1998 80(2):163-173.
- Bullens PH, van Loon CJ, de Waal Malefijt MC, Laan RF, Veth RP. Patient satisfaction after total knee arthroplasty: a comparison between subjective and objective outcome assessments. J Arthroplasty. 2001 16(6):740-747.
- Wylde V, Learmonth I, Potter A, Bettinson K, Lingard E. Patient-reported outcomes after fixed- versus mobile-bearing total knee replacement: a multi-centre randomised controlled trial using the Kinemax total knee. J Bone Joint Surg Br. 2008 90(9):1172-1179
- Kim TK, Chang CB, Kang YG, Kim SJ, Seong SC. Causes and predictors of patient’s dissatisfaction after uncomplicated total knee arthroplasty. J Arthroplasty. 2009 24(2):263-71.