The Journal of Arthroplasty xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis of Randomized Controlled Trials Tao Li, MD, Lei Zhou, MD, Qianyu Zhuang, MD, Xisheng Weng, MD, Yanyan Bian, MD Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
a r t i c l e
i n f o
Article history: Received 5 October 2013 Accepted 20 January 2014 Available online xxxx Keywords: total knee arthroplasty pain randomized controlled trials meta-analysis
a b s t r a c t The aim of this meta-analysis was to investigate whether patellar denervation with electrocautery (PD) after total knee arthroplasty (TKA) could reduce the postoperative anterior knee pain (AKP). Five randomized controlled trials (RCTs) with 572 patients and 657 knees were eligible for this meta-analysis. Our results showed that PD was associated with less AKP, lower visual analogue scale (VAS), higher patellar scores and better knee function compared with no patellar denervation (NPD). Complications did not differ significantly between the two groups. The existing evidence indicates that PD may be a better approach, as it improves both anterior knee pain and knee function after TKA. Future multi-center randomized controlled studies with large sample sizes are required to verify the current findings. © 2014 Elsevier Inc. All rights reserved.
Total knee arthroplasty (TKA), a major orthopedic procedure, is an established reliable means to correct deformity, relieve pain and restore joint function in arthritic knees [1–3]. However, anterior knee pain (AKP), which decreases patients' satisfaction [4,5], is reported to occur in up to one fourth of all patients following primary TKA [6]. With the yearly increase in the number of TKAs performed and patient demands for higher quality of life, AKP attracts increasing attention from orthopedic surgeons. Although several potential contributors to AKP have been found [7–10], its specific cause is unknown. Recently, patellar denervation with electrocautery (PD) has been used to prevent AKP. PD theoretically can interrupt the patellar peripheral nerves conduction, thereby blocking the pain receptors and providing pain relief. Several studies [11–13] found that PD can reduce AKP compared with no patellar denervation (NPD). However, other studies [14–16] found no significant difference in AKP between PD and NPD. A systematic review [17] regarding this topic compared many variables of PD and NPD, but the study still needs to be improved in four aspects. Firstly, Cochrane methodological quality assessment, used to assess RCTs, was adopted to assess the retrospective study [16]. Secondly, the data of patellar scores were from both the RCTs and the retrospective study. Thirdly, the authors concluded that AKP did not significantly differ between those with PD and NPD only based on the incidence of pain, in spite of the patellar scores being different between in PD and NPD. Therefore, we consider their conclusion
The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.01.024. Reprint requests: Xisheng Weng, MD, Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing 100730, China.
neither accurate nor reliable enough. Fourthly, no subgroup analysis or sensitivity analysis was used to evaluate heterogeneity in AKP. Therefore, we conducted this meta-analysis using only RCTs to assess AKP for those with PD or NPD, to aid surgeons in making a clinical decision to the use of PD.
Materials and Methods Search Methods A comprehensive search of the literature for all studies comparing PD with NPD after primary TKA was conducted through the electronic literature databases of PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure (CNKI), Weipu Bibliographic Database (VIP) and Wangfang Med Online (WANFANG). Retrieval time was from the time when the databases were built to August 2013. A manual search was also performed for relevant trials, reviews and related articles. This process continued iteratively until no additional articles could be identified.
Inclusion Criteria All RCTs comparing PD with NPD after primary TKA were eligible. No language or publication date limits were applied. If there were more than one eligible publication from a trial, the one with either higher-quality data or the most recent publication date was enrolled. Studies of revision of TKA, previous knee surgery, hemophilia arthritis and serious knee deformity (≥ 15° of the varus or valgus) were excluded. All non-randomized trials and quasi-randomized trials were also excluded.
0883-5403/0000-0000$36.00/0 – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2014.01.024
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
2
T. Li et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
Outcomes of Interest The primary outcome of interest was AKP, which includes three indicators (incidence of AKP, VAS score and patella scores [28]). The secondary outcomes include improvement in knee function and complications. Improvement in knee function was measured by the difference in clinically relevant scores (Knee Society Score [KSS] and the Western Ontario and McMaster Universities Arthritis Index [WOMAC]) between preoperative and postoperative status. Complications were stratified into wound infections (including superficial and deep infection) and patella-related complications (such as patella fractures, dislocation, subluxation and osteonecrosis).
senior reviewer and the reasons for exclusion were recorded. When the available data were not adequate, the primary authors of the article were contacted by e-mail for more information. Methodological Quality Assessment Two independent reviewers used the Cochrane Collaboration recommendations [18] to assess the methodological quality of the included trials. The following information was evaluated: random sequence generation, allocation concealment, blinding of outcome assessments, incomplete outcome data, selective reporting and other biases. An independent arbiter was consulted to reconcile any disagreement.
Data Extraction Statistical Analysis We extracted the following data from the included articles: authors, publication date, number of patients and knees, gender percentage, age, body mass index (BMI), diagnosis, depth of electrocautery, indicators of pain, type of tibial plateau, surgical approach, use of cement and follow-up time in both PD and NPD groups. Two reviewers independently extracted the data from all eligible RCTs. Any disagreement was resolved by discussion with the
For each included study, odds ratio (OR) and 95% confidence intervals (CI) were calculated for dichotomous outcomes, while weighted mean differences (WMD) and 95% CI were calculated for continuous outcomes. Statistical heterogeneity was assessed using the I 2 value and the chi-squared test. A P value N0.1 and an I 2 value ≤ 50% were considered to represent no statistical heterogeneity and a fixed-
Fig. 1. PRISMA 2009 flow diagram.
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
24 9–12 21 (12–28) Fixed NA NA
MP MP MP
NA Yes Yes
VAS, KSS score, patellar score Number of patients with knee pain, WOMAC pain score, KSS Number of patients with knee pain VAS and OKS Number of patients with knee pain, WOMAC score, KSS patellar score Yes Yes MV MP NA Fixed
40 185 50 Egypt UK Korea
20 91 50
20 94 50
20 91 50
20 94 50
NA 44 100
NA 55.3 100
NA 69 70.2
NA 60.2 70.2
NA NA NA
NA NA NA
OA OA OA
2–3 mm No more than 1 mm 1 mm within 1 mm within 2–3 mm NA OA NA 29.4 NA 30.1 68 72 68 71 74.3 64.1 74.3 72.5
NPD PD NPD PD NPD PD NPD PD NPD PD Total
No. of Patients
PD, patellar denervation with electrocautery; NPD, no patellar denervation; MP, medial parapatellar approach; MV, midvastus approach; BMI, body mass index; NA, not available; Fixed, fixed-bearing prosthesis; OA, osteoarthritis; VAS, visual analogue scale; KSS, Knee Society Scores; WOMAC score, Western Ontario and McMaster Universities osteoarthritis index; OKS, Oxford knee scores.
Complications Two studies of 302 knees reported the specific complications and showed no significant difference between PD and NPD in infections (OR = 1.00, 95% CI, 0.20, 5.11; P = 1.00) or complications related to the patella (OR = 1.41, 95% CI, 0.27, 7.27; P = 0.68) with no heterogeneity (Table 3).
Table 1 Characteristics of Included Studies.
Improvement in Knee Function Three trials reported the details of preoperative and postoperative KSS. The pooled results showed that PD was related to a greater increase in KSS (WMD = 1.88, 95% CI, 0.41, 3.34; P = 0.01) (Table 3). Two studies reported WOMAC scores before and after surgery. Pooled analysis showed that PD was associated with a greater decrease in WOMAC scores (WMD = 3.79, 95% CI, 1.88, 5.69; P b 0.0001) with no heterogeneity (P = 0.38, I 2 = 0%) (Table 3).
No. of Knees
Patellar Scores Two studies consisting of 170 knees reported the results of postoperative patellar scores. The results showed that PD was associated with better postoperative patellar scores than NPD (WMD = 1.15, 95% CI, 0.74, 1.55; P b 0.00001) (Table 3).
Country
Female (%)
VAS Two trials consisting of 255 knees reported the AKP using VAS. The result showed that PD was associated with lower VAS scores (WMD = − 0.63, 95% CI, − 0.97, − 0.29; P = 0.0002) with no heterogeneity (P = 0.95, I 2 = 0%) (Table 3).
References
Age (Mean)
BMI
Diagnosis
Incidence of AKP Four studies knees reported the AKP incidence after operation. Pooled results showed that PD was associated with lower incidence of AKP compared with NPD (OR = 0.62, 95% CI, 0.43, 0.89; P = 0.010) with moderate heterogeneity (P = 0.18, I 2 = 38%) (Table 3). A sensitivity analysis was conducted after excluding one trial [13] and the pooled results with no heterogeneity (P = 0.37, I 2 = 0%) demonstrated significant difference between the two groups (OR = 0.67, 95% CI, 0.46, 0.99; P = 0.040), a result in line with the previous analysis (Table 3).
35 131
Meta-Analysis Results
35 131
Depth of Electrocautery
The general methodological quality was moderate in bias risk according to Cochrane Collaboration recommendations. The detailed risk of bias in methodological quality of the included studies is elaborated in Table 2.
35 131
Type of Tibial Plateau
Risk of Bias in Included Studies
35 131
Approach
Use of Cement
The results of the literature search and selection are displayed in Fig. 1. We identified five RCTs [11–15] associated with PD versus NPD involving AKP. A total of 572 patients involving 657 knees ranging from 40 to 262 in each trial were included. All selected studies were in English and published between 2004 and 2012. The detailed characteristics of these studies are shown in Table 1.
35 262
Characteristics of Selected Studies
Turkey The Netherlands
Results
Altay et al 2012 [11] van Jonbergen et al 2011 [12] Saoud 2004 [13] Baliga et al 2012 [14] Yim et al 2012 [15]
Indicator of Pain
Follow-Up (Month)
effects model was used to estimate the overall summary effect sizes. For heterogeneous value, a random-effects model was adopted and further subgroup analysis or sensitivity analysis was conducted to explore the potential sources of heterogeneity. All analyses were completed with Review Manager Software (RevMan5.2, Cochrane Collaboration, http://www.cochrane.org/) and P value b 0.05 was considered significant.
3 36 (24–60) 12
T. Li et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
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T. Li et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
Table 2 Quality Assessment of Risk of Bias in Included Studies.
References
Random Sequence Generation
Allocation Concealment
Blinding
Complete Outcome Data
Free of Selective Reporting
Free of Other Bias
Altay et al 2012 [11] van Jonbergen et al 2011 [12] Saoud 2004 [13] Baliga et al 2012 [14] Yim et al 2012 [15]
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Unclear Unclear Unclear Unclear Unclear
Low, low risk of bias; Unclear, unclear risk of bias; High, high risk of bias.
Discussion A number of surgeons have adopted patellar resurfacing to relieve AKP and achieve better knee function, but many trials found similar clinical outcomes with resurfaced and non-resurfaced patella in TKA [19–21]. What is more, patellas of Chinese patients, comparing with those of Westerners, are relatively smaller in length, width and thickness, making it unsuitable for resurfacing [26]. Consequently, an increasing number of orthopedic surgeons have adopted PD without patellar resurfacing to reduce AKP and improve knee function. Several studies [11–13] have shown that PD can reduce AKP and achieve better postoperative knee function. Fifty-six percent of Dutch orthopedic surgeons performing TKA use PD to relieve AKP [25]. Nevertheless, other surgeons [14–16] found no difference in AKP and knee function between PD and NPD. So far, no consensus has been reached on the use of PD in TKA without patellar resurfacing. The patella is innervated by the medial patellar nerve and the lateral patellar nerve [23,27] and studies have demonstrated the presence of substance-P nociceptive afferent fibers in the peripatellar soft tissues [22]. Theoretically, PD can block the pain receptors and interrupt the pain pathways, to in turn reduce AKP after TKA [12,23,24]. However, the previous meta-analysis, which used AKP incidence and patellar scores to estimate the effectiveness of PD, showed no significant difference between PD and NPD. But it is remarkable that two underlying factors may bring out relevant deviation. Firstly, the study did not use subgroup analysis or sensitivity analysis to further investigate the high heterogeneity in incidence of AKP. Secondly, it is inappropriate to pool patellar scores from RCTs and non-RCTs. In our meta-analysis, we adopted three indicators of AKP to assess PD following TKA, which are more accurate and comprehensive than the previous meta-analysis [17]. Firstly, our results showed that PD was associated with a significantly decreased incidence of AKP (P = 0.010) with low heterogeneity (P = 0.18, I 2 = 38%). The further sensitivity analysis without heterogeneity (P = 0.37, I 2 = 0%) showed that PD is associated with significantly reduced AKP, which is consistent with our previous analysis. Secondly, the mean postoperative VAS ranged from 1.18 to 2.2 in the PD group and from 1.82 to 2.82 in the NPD group. The pooled result with no
heterogeneity found lower VAS with PD, which is different from the previous meta-analysis. Thirdly, two trials [11,15] reported preoperative and postoperative patellar scores and the pooled result showed that PD was associated with higher patellar scores compared with NPD. Although Cheng et al [17] showed that PD posted significantly higher scores compared with NPD, the study combined data from RCTs and non-RCTs, which we thought that a subgroup analysis may be a more reasonable choice. Postoperative function of the knee is another important criterion to evaluate the effectiveness of TKA. The previous meta-analysis which adopted postoperative KSS and WOMAC to estimate the function of the knee showed no significant difference for those with and without PD. In our meta-analysis, we adopted the change in postoperative KSS and WOMAC scores to assess the actual improvement in knee function. Our pooled results showed that PD was associated with greater improvement in knee function. Moreover, van Jonbergen et al [12] showed a statistically significantly better mean WOMAC functional subscale for the NP group (P = 0.02). As for complications, disruption of the surrounding soft tissue theoretically may lead to a reduced blood supply to the patella, which may induce patellar osteonecrosis. However, no osteonecrosis of the patella was reported. What is more, our pooled results showed no significant difference in infections or complications related to patella between PD and NPD, a finding that was in accord with the previous meta-analysis. Compared with the previous meta-analysis [17], our study has several strengths. Firstly, our meta-analysis adopted stricter inclusion criteria. Retrospective trials and non-RCTs were strictly excluded in this study for the reliability of results. Secondly, a greater number of AKP indicators were adopted and pooled appropriately in our metaanalysis. Thirdly, the variable “postoperative KSS and WOMAC change” adopted in our meta-analysis is more accurate than the “postoperative KSS and WOMAC level.” Fourthly, we used a fixedeffects model and conducted a sensitivity analysis to explore the potential source of heterogeneity, which make the results more accurate and stable. Even so, the current meta-analysis also had several limitations. Firstly, the number of studies included in the meta-analysis was still relatively small, rendering it difficult to conduct funnel plots to assess
Table 3 Meta-Analysis Results of Outcomes. Outcomes 1. AKP Incidence of AKP Sensitivity of incidence of AKP VAS Patella scores 2. Improvement of knee function KSS WOMAC score 3. Complications Infections Complications related to patella
No. of Studies
No. of Knees
Statistical Method
Effect Size
4 3 2 2
587 547 255 170
Odds ratio (M-H, fixed, 95% CI) Odds ratio (M-H, fixed, 95% CI) Mean difference (IV, fixed, 95% CI) Mean difference (IV, fixed, 95% CI)
0.62 [0.43, 0.89] 0.67 [0.46, 0.99] −0.63 [−0.97, −0.29] 1.15 [0.74, 1.55]
3 2
432 362
Mean difference (IV, fixed, 95% CI) Mean difference (IV, fixed, 95% CI)
1.88 [0.41, 3.34] 3.79 [1.88, 5.69]
2 2
302 302
Odds ratio (M-H, fixed, 95% CI) Odds ratio (M-H, fixed, 95% CI)
1.00 [0.20, 5.11] 1.41 [0.27, 7.27]
AKP, anterior knee pain; VAS, visual analogue scale; KSS, Knee Society Scores; WOMAC score, Western Ontario and McMaster Universities osteoarthritis index.
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
T. Li et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
publication bias. Secondly, different circumpatellar electrocautery depths used in PD may result in performance bias. Thirdly, the followup time in the included trials may affect conclusions about the association between PD and AKP. Conclusion Although the methodological quality of included studies is moderate, we believe that this meta-analysis is an objective study of the benefits and risks of PD as currently known. Our meta-analysis suggests that PD can reduce AKP and achieve better improvement in knee function with no increased complications compared with NPD. This finding encourages the use of PD in TKA, but high-quality randomized controlled studies are required to confirm these results. References 1. Scott WN, Rubinstein M, Scuderi G. Results after knee replacement with a posterior cruciate-substituting prosthesis. J Bone Joint Surg Am 1988;70:1163. 2. Riley LH, Hungerford DS. Geometric total knee replacement for treatment of the rheumatoid knee. J Bone Joint Surg Am 1978;60:523. 3. Laskin RS. Modular total knee replacement arthroplasty. A review of eighty-nine patients. J Bone Joint Surg Am 1976;58:766. 4. Scott CE, Howie CR, MacDonald D, et al. Predicting dissatisfaction following total knee replacement: a prospective study of 1217 patients. J Bone Joint Surg Br 2010;92:1253. 5. Bonnin MP, Basiglini L, Archbold HA. What are the factors of residual pain after uncomplicated TKA? Knee Surg Sports Traumatol Arthrosc 2011;19:1411. 6. Fu Y, Wang G, Fu Q. Patellar resurfacing in total knee arthroplasty for osteoarthritis: a meta-analysis. Knee Surg Sports Traumatol Arthrosc 2011;19:1460. 7. Barrack RL, Bertot AJ, Wolfe MW, et al. Patellar resurfacing in total knee arthroplasty. A prospective, randomized, double-blind study with five to seven years of follow-up. J Bone Joint Surg Am 2001;83:1376. 8. Breugem SJ, Sierevelt IN, Schafroth MU, et al. Less anterior knee pain with a mobilebearing prosthesis compared with a fixed-bearing prosthesis. Clin Orthop Relat Res 2008;466:1959. 9. Kong CG, Cho HM, Suhl KH, et al. Patellar tracking after total knee arthroplasty performed without lateral release. Knee 2012;19:692. 10. Pierson JL, Ritter MA, Keating EM, et al. The effect of stuffing the patellofemoral compartment on the outcome of total knee arthroplasty. J Bone Joint Surg Am 2007;89:2195.
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11. Altay MA, Erturk C, Altay N, et al. Patellar denervation in total knee arthroplasty without patellar resurfacing: a prospective, randomized controlled study. Orthop Traumatol Surg Res 2012;98:421. 12. van Jonbergen HP, Scholtes VA, van Kampen A, et al. A randomised, controlled trial of circumpatellar electrocautery in total knee replacement without patellar resurfacing. J Bone Joint Surg Br 2011;93:1054. 13. Saoud AMF. Patellar denervation in non-patellar resurfacing total knee arthroplasty. Pan Arab J Orth Trauma 2004;8:25. 14. Baliga S, McNair CJ, Barnett KJ, et al. Does circumpatellar electrocautery improve the outcome after total knee replacement? A prospective, randomised, blinded controlled trial. J Bone Joint Surg Br 2012;94:1228. 15. Yim SJ, Jang MS, Kim WJ, et al. The effect of electrocautery around the patellar rim in patellar non-resurfacing total knee arthroplasty. Knee Surg Relat Res 2012;24:104. 16. Gupta S, Augustine A, Horey L, et al. Electrocautery of the patellar rim in primary total knee replacement: beneficial or unnecessary? J Bone Joint Surg Br 2010;92: 1259. 17. Cheng T, Zhu C, Gao Y, et al. Patellar denervation with electrocautery in total knee arthroplasty without patellar resurfacing: a meta-analysis. Knee Surg Sports Traumatol Arthrosc 2013. http://dx.doi.org/10.1007/s00167-013-2533-9. 18. Higgins JPT, Altman DG. Assessing risk of bias in included studies. In: Higgins JPT, Green S, editors. Wiley; 2008. p. 187. 19. Keblish PA, Varma AK, Greenwald AS. Patellar resurfacing or retention in total knee arthroplasty. A prospective study of patients with bilateral replacements. J Bone Joint Surg Br 1994;76:930. 20. Burnett RS, Boone JL, Rosenzweig SD, et al. Patellar resurfacing compared with nonresurfacing in total knee arthroplasty. A concise follow-up of a randomized trial. J Bone Joint Surg Am 2009;91:2562. 21. Calvisi V, Camillieri G, Lupparelli S. Resurfacing versus non-resurfacing the patella in total knee arthroplasty: a critical appraisal of the available evidence. Arch Orthop Trauma Surg 2009;129:1261. 22. Wojtys EM, Beaman DN, Glover RA, et al. Innervation of the human knee joint by substance-P fibers. Arthroscopy 1990;6:254. 23. Maralcan G, Kuru I, Issi S, et al. The innervation of patella: anatomical and clinical study. Surg Radiol Anat 2005;27:331. 24. McPherson EJ. Patellar tracking in primary total knee arthroplasty. Instr Course Lect 2006;55:439. 25. van Jonbergen HP, Barnaart AF, Verheyen CC. A Dutch survey on circumpatellar electrocautery in total knee arthroplasty. Open Orthop J 2010;4:201. 26. Guo S, Zhou Y, Shao H, et al. CT study of normal patellar anatomical morphology. Chinese Journal of Orthopaedics 2013;33:273. 27. Moller BN, Helmig O. Patellar pain treated by neurotomy. Arch Orthop Trauma Surg 1984;103:137. 28. Feller JA, Bartlett RJ, Lang DM. Patellar resurfacing versus retention in total knee arthroplasty. J Bone Joint Surg Br 1996;78:226.
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis of Randomized Controlled Trials Tao Li, MD, Lei Zhou, MD, Qianyu Zhuang, MD, Xisheng Weng, MD, Yanyan Bian, MD Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
a r t i c l e
i n f o
Article history: Received 5 October 2013 Accepted 20 January 2014 Available online xxxx Keywords: total knee arthroplasty pain randomized controlled trials meta-analysis
a b s t r a c t The aim of this meta-analysis was to investigate whether patellar denervation with electrocautery (PD) after total knee arthroplasty (TKA) could reduce the postoperative anterior knee pain (AKP). Five randomized controlled trials (RCTs) with 572 patients and 657 knees were eligible for this meta-analysis. Our results showed that PD was associated with less AKP, lower visual analogue scale (VAS), higher patellar scores and better knee function compared with no patellar denervation (NPD). Complications did not differ significantly between the two groups. The existing evidence indicates that PD may be a better approach, as it improves both anterior knee pain and knee function after TKA. Future multi-center randomized controlled studies with large sample sizes are required to verify the current findings. © 2014 Elsevier Inc. All rights reserved.
Total knee arthroplasty (TKA), a major orthopedic procedure, is an established reliable means to correct deformity, relieve pain and restore joint function in arthritic knees [1–3]. However, anterior knee pain (AKP), which decreases patients' satisfaction [4,5], is reported to occur in up to one fourth of all patients following primary TKA [6]. With the yearly increase in the number of TKAs performed and patient demands for higher quality of life, AKP attracts increasing attention from orthopedic surgeons. Although several potential contributors to AKP have been found [7–10], its specific cause is unknown. Recently, patellar denervation with electrocautery (PD) has been used to prevent AKP. PD theoretically can interrupt the patellar peripheral nerves conduction, thereby blocking the pain receptors and providing pain relief. Several studies [11–13] found that PD can reduce AKP compared with no patellar denervation (NPD). However, other studies [14–16] found no significant difference in AKP between PD and NPD. A systematic review [17] regarding this topic compared many variables of PD and NPD, but the study still needs to be improved in four aspects. Firstly, Cochrane methodological quality assessment, used to assess RCTs, was adopted to assess the retrospective study [16]. Secondly, the data of patellar scores were from both the RCTs and the retrospective study. Thirdly, the authors concluded that AKP did not significantly differ between those with PD and NPD only based on the incidence of pain, in spite of the patellar scores being different between in PD and NPD. Therefore, we consider their conclusion
The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.01.024. Reprint requests: Xisheng Weng, MD, Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing 100730, China.
neither accurate nor reliable enough. Fourthly, no subgroup analysis or sensitivity analysis was used to evaluate heterogeneity in AKP. Therefore, we conducted this meta-analysis using only RCTs to assess AKP for those with PD or NPD, to aid surgeons in making a clinical decision to the use of PD.
Materials and Methods Search Methods A comprehensive search of the literature for all studies comparing PD with NPD after primary TKA was conducted through the electronic literature databases of PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure (CNKI), Weipu Bibliographic Database (VIP) and Wangfang Med Online (WANFANG). Retrieval time was from the time when the databases were built to August 2013. A manual search was also performed for relevant trials, reviews and related articles. This process continued iteratively until no additional articles could be identified.
Inclusion Criteria All RCTs comparing PD with NPD after primary TKA were eligible. No language or publication date limits were applied. If there were more than one eligible publication from a trial, the one with either higher-quality data or the most recent publication date was enrolled. Studies of revision of TKA, previous knee surgery, hemophilia arthritis and serious knee deformity (≥ 15° of the varus or valgus) were excluded. All non-randomized trials and quasi-randomized trials were also excluded.
0883-5403/0000-0000$36.00/0 – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.arth.2014.01.024
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
2
T. Li et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
Outcomes of Interest The primary outcome of interest was AKP, which includes three indicators (incidence of AKP, VAS score and patella scores [28]). The secondary outcomes include improvement in knee function and complications. Improvement in knee function was measured by the difference in clinically relevant scores (Knee Society Score [KSS] and the Western Ontario and McMaster Universities Arthritis Index [WOMAC]) between preoperative and postoperative status. Complications were stratified into wound infections (including superficial and deep infection) and patella-related complications (such as patella fractures, dislocation, subluxation and osteonecrosis).
senior reviewer and the reasons for exclusion were recorded. When the available data were not adequate, the primary authors of the article were contacted by e-mail for more information. Methodological Quality Assessment Two independent reviewers used the Cochrane Collaboration recommendations [18] to assess the methodological quality of the included trials. The following information was evaluated: random sequence generation, allocation concealment, blinding of outcome assessments, incomplete outcome data, selective reporting and other biases. An independent arbiter was consulted to reconcile any disagreement.
Data Extraction Statistical Analysis We extracted the following data from the included articles: authors, publication date, number of patients and knees, gender percentage, age, body mass index (BMI), diagnosis, depth of electrocautery, indicators of pain, type of tibial plateau, surgical approach, use of cement and follow-up time in both PD and NPD groups. Two reviewers independently extracted the data from all eligible RCTs. Any disagreement was resolved by discussion with the
For each included study, odds ratio (OR) and 95% confidence intervals (CI) were calculated for dichotomous outcomes, while weighted mean differences (WMD) and 95% CI were calculated for continuous outcomes. Statistical heterogeneity was assessed using the I 2 value and the chi-squared test. A P value N0.1 and an I 2 value ≤ 50% were considered to represent no statistical heterogeneity and a fixed-
Fig. 1. PRISMA 2009 flow diagram.
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
24 9–12 21 (12–28) Fixed NA NA
MP MP MP
NA Yes Yes
VAS, KSS score, patellar score Number of patients with knee pain, WOMAC pain score, KSS Number of patients with knee pain VAS and OKS Number of patients with knee pain, WOMAC score, KSS patellar score Yes Yes MV MP NA Fixed
40 185 50 Egypt UK Korea
20 91 50
20 94 50
20 91 50
20 94 50
NA 44 100
NA 55.3 100
NA 69 70.2
NA 60.2 70.2
NA NA NA
NA NA NA
OA OA OA
2–3 mm No more than 1 mm 1 mm within 1 mm within 2–3 mm NA OA NA 29.4 NA 30.1 68 72 68 71 74.3 64.1 74.3 72.5
NPD PD NPD PD NPD PD NPD PD NPD PD Total
No. of Patients
PD, patellar denervation with electrocautery; NPD, no patellar denervation; MP, medial parapatellar approach; MV, midvastus approach; BMI, body mass index; NA, not available; Fixed, fixed-bearing prosthesis; OA, osteoarthritis; VAS, visual analogue scale; KSS, Knee Society Scores; WOMAC score, Western Ontario and McMaster Universities osteoarthritis index; OKS, Oxford knee scores.
Complications Two studies of 302 knees reported the specific complications and showed no significant difference between PD and NPD in infections (OR = 1.00, 95% CI, 0.20, 5.11; P = 1.00) or complications related to the patella (OR = 1.41, 95% CI, 0.27, 7.27; P = 0.68) with no heterogeneity (Table 3).
Table 1 Characteristics of Included Studies.
Improvement in Knee Function Three trials reported the details of preoperative and postoperative KSS. The pooled results showed that PD was related to a greater increase in KSS (WMD = 1.88, 95% CI, 0.41, 3.34; P = 0.01) (Table 3). Two studies reported WOMAC scores before and after surgery. Pooled analysis showed that PD was associated with a greater decrease in WOMAC scores (WMD = 3.79, 95% CI, 1.88, 5.69; P b 0.0001) with no heterogeneity (P = 0.38, I 2 = 0%) (Table 3).
No. of Knees
Patellar Scores Two studies consisting of 170 knees reported the results of postoperative patellar scores. The results showed that PD was associated with better postoperative patellar scores than NPD (WMD = 1.15, 95% CI, 0.74, 1.55; P b 0.00001) (Table 3).
Country
Female (%)
VAS Two trials consisting of 255 knees reported the AKP using VAS. The result showed that PD was associated with lower VAS scores (WMD = − 0.63, 95% CI, − 0.97, − 0.29; P = 0.0002) with no heterogeneity (P = 0.95, I 2 = 0%) (Table 3).
References
Age (Mean)
BMI
Diagnosis
Incidence of AKP Four studies knees reported the AKP incidence after operation. Pooled results showed that PD was associated with lower incidence of AKP compared with NPD (OR = 0.62, 95% CI, 0.43, 0.89; P = 0.010) with moderate heterogeneity (P = 0.18, I 2 = 38%) (Table 3). A sensitivity analysis was conducted after excluding one trial [13] and the pooled results with no heterogeneity (P = 0.37, I 2 = 0%) demonstrated significant difference between the two groups (OR = 0.67, 95% CI, 0.46, 0.99; P = 0.040), a result in line with the previous analysis (Table 3).
35 131
Meta-Analysis Results
35 131
Depth of Electrocautery
The general methodological quality was moderate in bias risk according to Cochrane Collaboration recommendations. The detailed risk of bias in methodological quality of the included studies is elaborated in Table 2.
35 131
Type of Tibial Plateau
Risk of Bias in Included Studies
35 131
Approach
Use of Cement
The results of the literature search and selection are displayed in Fig. 1. We identified five RCTs [11–15] associated with PD versus NPD involving AKP. A total of 572 patients involving 657 knees ranging from 40 to 262 in each trial were included. All selected studies were in English and published between 2004 and 2012. The detailed characteristics of these studies are shown in Table 1.
35 262
Characteristics of Selected Studies
Turkey The Netherlands
Results
Altay et al 2012 [11] van Jonbergen et al 2011 [12] Saoud 2004 [13] Baliga et al 2012 [14] Yim et al 2012 [15]
Indicator of Pain
Follow-Up (Month)
effects model was used to estimate the overall summary effect sizes. For heterogeneous value, a random-effects model was adopted and further subgroup analysis or sensitivity analysis was conducted to explore the potential sources of heterogeneity. All analyses were completed with Review Manager Software (RevMan5.2, Cochrane Collaboration, http://www.cochrane.org/) and P value b 0.05 was considered significant.
3 36 (24–60) 12
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Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
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Table 2 Quality Assessment of Risk of Bias in Included Studies.
References
Random Sequence Generation
Allocation Concealment
Blinding
Complete Outcome Data
Free of Selective Reporting
Free of Other Bias
Altay et al 2012 [11] van Jonbergen et al 2011 [12] Saoud 2004 [13] Baliga et al 2012 [14] Yim et al 2012 [15]
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Low Low Unclear Low Unclear
Unclear Unclear Unclear Unclear Unclear
Low, low risk of bias; Unclear, unclear risk of bias; High, high risk of bias.
Discussion A number of surgeons have adopted patellar resurfacing to relieve AKP and achieve better knee function, but many trials found similar clinical outcomes with resurfaced and non-resurfaced patella in TKA [19–21]. What is more, patellas of Chinese patients, comparing with those of Westerners, are relatively smaller in length, width and thickness, making it unsuitable for resurfacing [26]. Consequently, an increasing number of orthopedic surgeons have adopted PD without patellar resurfacing to reduce AKP and improve knee function. Several studies [11–13] have shown that PD can reduce AKP and achieve better postoperative knee function. Fifty-six percent of Dutch orthopedic surgeons performing TKA use PD to relieve AKP [25]. Nevertheless, other surgeons [14–16] found no difference in AKP and knee function between PD and NPD. So far, no consensus has been reached on the use of PD in TKA without patellar resurfacing. The patella is innervated by the medial patellar nerve and the lateral patellar nerve [23,27] and studies have demonstrated the presence of substance-P nociceptive afferent fibers in the peripatellar soft tissues [22]. Theoretically, PD can block the pain receptors and interrupt the pain pathways, to in turn reduce AKP after TKA [12,23,24]. However, the previous meta-analysis, which used AKP incidence and patellar scores to estimate the effectiveness of PD, showed no significant difference between PD and NPD. But it is remarkable that two underlying factors may bring out relevant deviation. Firstly, the study did not use subgroup analysis or sensitivity analysis to further investigate the high heterogeneity in incidence of AKP. Secondly, it is inappropriate to pool patellar scores from RCTs and non-RCTs. In our meta-analysis, we adopted three indicators of AKP to assess PD following TKA, which are more accurate and comprehensive than the previous meta-analysis [17]. Firstly, our results showed that PD was associated with a significantly decreased incidence of AKP (P = 0.010) with low heterogeneity (P = 0.18, I 2 = 38%). The further sensitivity analysis without heterogeneity (P = 0.37, I 2 = 0%) showed that PD is associated with significantly reduced AKP, which is consistent with our previous analysis. Secondly, the mean postoperative VAS ranged from 1.18 to 2.2 in the PD group and from 1.82 to 2.82 in the NPD group. The pooled result with no
heterogeneity found lower VAS with PD, which is different from the previous meta-analysis. Thirdly, two trials [11,15] reported preoperative and postoperative patellar scores and the pooled result showed that PD was associated with higher patellar scores compared with NPD. Although Cheng et al [17] showed that PD posted significantly higher scores compared with NPD, the study combined data from RCTs and non-RCTs, which we thought that a subgroup analysis may be a more reasonable choice. Postoperative function of the knee is another important criterion to evaluate the effectiveness of TKA. The previous meta-analysis which adopted postoperative KSS and WOMAC to estimate the function of the knee showed no significant difference for those with and without PD. In our meta-analysis, we adopted the change in postoperative KSS and WOMAC scores to assess the actual improvement in knee function. Our pooled results showed that PD was associated with greater improvement in knee function. Moreover, van Jonbergen et al [12] showed a statistically significantly better mean WOMAC functional subscale for the NP group (P = 0.02). As for complications, disruption of the surrounding soft tissue theoretically may lead to a reduced blood supply to the patella, which may induce patellar osteonecrosis. However, no osteonecrosis of the patella was reported. What is more, our pooled results showed no significant difference in infections or complications related to patella between PD and NPD, a finding that was in accord with the previous meta-analysis. Compared with the previous meta-analysis [17], our study has several strengths. Firstly, our meta-analysis adopted stricter inclusion criteria. Retrospective trials and non-RCTs were strictly excluded in this study for the reliability of results. Secondly, a greater number of AKP indicators were adopted and pooled appropriately in our metaanalysis. Thirdly, the variable “postoperative KSS and WOMAC change” adopted in our meta-analysis is more accurate than the “postoperative KSS and WOMAC level.” Fourthly, we used a fixedeffects model and conducted a sensitivity analysis to explore the potential source of heterogeneity, which make the results more accurate and stable. Even so, the current meta-analysis also had several limitations. Firstly, the number of studies included in the meta-analysis was still relatively small, rendering it difficult to conduct funnel plots to assess
Table 3 Meta-Analysis Results of Outcomes. Outcomes 1. AKP Incidence of AKP Sensitivity of incidence of AKP VAS Patella scores 2. Improvement of knee function KSS WOMAC score 3. Complications Infections Complications related to patella
No. of Studies
No. of Knees
Statistical Method
Effect Size
4 3 2 2
587 547 255 170
Odds ratio (M-H, fixed, 95% CI) Odds ratio (M-H, fixed, 95% CI) Mean difference (IV, fixed, 95% CI) Mean difference (IV, fixed, 95% CI)
0.62 [0.43, 0.89] 0.67 [0.46, 0.99] −0.63 [−0.97, −0.29] 1.15 [0.74, 1.55]
3 2
432 362
Mean difference (IV, fixed, 95% CI) Mean difference (IV, fixed, 95% CI)
1.88 [0.41, 3.34] 3.79 [1.88, 5.69]
2 2
302 302
Odds ratio (M-H, fixed, 95% CI) Odds ratio (M-H, fixed, 95% CI)
1.00 [0.20, 5.11] 1.41 [0.27, 7.27]
AKP, anterior knee pain; VAS, visual analogue scale; KSS, Knee Society Scores; WOMAC score, Western Ontario and McMaster Universities osteoarthritis index.
Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
T. Li et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
publication bias. Secondly, different circumpatellar electrocautery depths used in PD may result in performance bias. Thirdly, the followup time in the included trials may affect conclusions about the association between PD and AKP. Conclusion Although the methodological quality of included studies is moderate, we believe that this meta-analysis is an objective study of the benefits and risks of PD as currently known. Our meta-analysis suggests that PD can reduce AKP and achieve better improvement in knee function with no increased complications compared with NPD. This finding encourages the use of PD in TKA, but high-quality randomized controlled studies are required to confirm these results. References 1. Scott WN, Rubinstein M, Scuderi G. Results after knee replacement with a posterior cruciate-substituting prosthesis. J Bone Joint Surg Am 1988;70:1163. 2. Riley LH, Hungerford DS. Geometric total knee replacement for treatment of the rheumatoid knee. J Bone Joint Surg Am 1978;60:523. 3. Laskin RS. Modular total knee replacement arthroplasty. A review of eighty-nine patients. J Bone Joint Surg Am 1976;58:766. 4. Scott CE, Howie CR, MacDonald D, et al. Predicting dissatisfaction following total knee replacement: a prospective study of 1217 patients. J Bone Joint Surg Br 2010;92:1253. 5. Bonnin MP, Basiglini L, Archbold HA. What are the factors of residual pain after uncomplicated TKA? Knee Surg Sports Traumatol Arthrosc 2011;19:1411. 6. Fu Y, Wang G, Fu Q. Patellar resurfacing in total knee arthroplasty for osteoarthritis: a meta-analysis. Knee Surg Sports Traumatol Arthrosc 2011;19:1460. 7. Barrack RL, Bertot AJ, Wolfe MW, et al. Patellar resurfacing in total knee arthroplasty. A prospective, randomized, double-blind study with five to seven years of follow-up. J Bone Joint Surg Am 2001;83:1376. 8. Breugem SJ, Sierevelt IN, Schafroth MU, et al. Less anterior knee pain with a mobilebearing prosthesis compared with a fixed-bearing prosthesis. Clin Orthop Relat Res 2008;466:1959. 9. Kong CG, Cho HM, Suhl KH, et al. Patellar tracking after total knee arthroplasty performed without lateral release. Knee 2012;19:692. 10. Pierson JL, Ritter MA, Keating EM, et al. The effect of stuffing the patellofemoral compartment on the outcome of total knee arthroplasty. J Bone Joint Surg Am 2007;89:2195.
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Please cite this article as: Li T, et al, Patellar Denervation in Total Knee Arthroplasty Without Patellar Resurfacing and Postoperative Anterior Knee Pain: A Meta-Analysis..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.01.024
