Comparisons among three approaches—two minimally invasive and one conventional—for total knee arthroplasty: a retrospective cohort study with minimum follow-up of 10 years

DOI: https://doi.org/10.21203/rs.2.19201/v1

Abstract

Background

Few studies have investigated whether the mini-medial parapatellar (MMP) and quadriceps-sparing (QS) approaches have good long-term results compared to the conventional medial parapatellar (MP) approach in terms of clinical evaluations and radiographic assessments for total knee arthroplasty (TKA). The purpose of this study was to perform comparisons among the MMP, QS and MP approaches with a follow-up at 10 to 17 years.

Methods

This is a retrospective comparative study of 93 patients who underwent MMP TKA (32 TKAs), QS TKA (47 TKAs) or MP TKA (31 TKAs) with the same arthroplasty system. The clinical evaluations were performed according to the new American Knee Society score (KSS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the visual analogue scale (VAS), range of motion (ROM), incidence of anterior knee pain (AKP), the Feller patellofemoral score (PFS), the reoperation rate and the complication rates. Radiographic assessments included observation of the mechanical axis of the lower limb and calculations of the lateral distal femoral angle (LDFA), femoral flexion angle (FFA), medial proximal tibial angle (MPTA), tibial slope angle (TSA), lateral patella displacement (LPD), and lateral patella tilt (LPT).

Results

There were no differences in the long-term follow-up results of the new KSS, WOMAC score, ROM, VAS, patellofemoral functions, reoperation rate or complication rates among the groups. In addition, no radiographic differences in terms of lower limb mechanical axis or femoral, tibial or patellar position were observed.

Conclusion

These results provide conclusive evidence that equivalent, long-term clinical results can be obtained using any one of these three approaches.

Background

Total knee arthroplasty (TKA) is a safe and effective treatment for patients with end-stage knee osteoarthritis [1]; with the conventional medial parapatellar (MP) approach for TKA, good visualization of the knee can be obtained, helping to achieve correct osteotomy, proper ligament balance and good prosthesis position, which are all important for good long-term results [24]. To date, various types of minimally invasive approaches for TKA have been developed to improve functional recovery and rehabilitation and accelerate the return to the activities of daily life [5, 6]. Among them, two of the most commonly used minimally invasive procedures are the mini-medial parapatellar (MMP) and quadriceps-sparing (QS) approaches [79]. Some investigators have indicated that minimally invasive approaches may compromise the advantages of correct osteotomy, proper ligament balance and good prosthesis position to achieve potentially rapid rehabilitation [1012], potentially sacrificing the long-term clinical outcomes and survival of the prostheses [1316]. Thus far, to our knowledge, most of the studies of the MMP, QS and MP approaches have evaluated the follow-up of no more than five years, and there is a lack of data demonstrating the long-term results. Thus, we performed this study with a follow-up of 10 to 17 years to evaluate the post-TKA clinical and radiographic outcomes in patients who underwent MMP, QS or MP approaches for TKA. The primary hypothesis of this study is that the minimally invasive approaches would not compromise the clinical outcomes, lower limb mechanical axis or prosthetic positions evaluated by recently developed and validated outcome tools and that the reoperation and complication rates would be similar. A secondary hypothesis is that the two minimally invasive approaches may show superiority of patellofemoral functions in terms of anterior knee pain (AKP), Feller patellofemoral score (PFS), patellar physical examinations and patellar position.

Materials And Methods

This was a retrospective cohort study that was approved by the review board of our Hospital (IRB00006761-2011072), and informed consent was obtained from all patients. The inclusion criteria were patients who underwent primary TKA by one senior surgeon between November 2001 and June 2008 in our hospital. The exclusion criteria were patients with inflammatory arthritis (45 patients), patients with a history of previous knee surgery (67 patients), patients with neurological diseases (5 patients) and patients who received surgery with constrained TKA systems (8 patients). There were ninety-three patients (110 TKAs) enrolled in the final study. Data related to patient demographics, including affected side, gender, age, height, weight, body mass index (BMI), preoperative lower limb mechanical axis, Knee Society score (KSS) [17], range of motion (ROM) and visual analogue scale (VAS), were recorded. At the outpatient clinic, two independent observers performed all evaluations.

Surgical Techniques

All surgeries were performed by one senior surgeon who was experienced in MMP, QS and MP TKAs. For all TKAs, the Nexgen Legacy Posterior Stabilized-flex Prosthesis (Zimmer, Warsaw, Indiana, USA) was implanted in all patients in the three study groups with equal distribution, and a tourniquet was used during the procedure. For the MP and MMP groups, the operation was carried out through a midline incision and medial parapatellar arthrotomy. A quadriceps split approximately 4 centimeters (cm) above the superior pole of patella was used in the MP group, as described by Insall et al. [18], and a division of the quadriceps tendon extending 2 to 4 cm above the superior pole of the patella was used in the MMP group, as described by Tenholder et al. [19]. For the QS approach, a medial curved skin incision extending from the superior pole of the patella to the top of the tibial tubercle was made; the quadriceps tendon was divided no more than 2 cm within the vastus medialis obliquus muscle split if its insertion was attached to the medial edge of the patella, as described by Aglietti et al. [20]. During patellar resurfacing, the patella was dislocated and everted in the MP group and subluxed laterally with no eversion in the MMP or QS groups. The patella was removed at the same thickness as the components, and patellar resurfacing was performed in all patients with a cemented, three-pegged, all-polyethylene patellar component. The patellar tracking was examined by the no-thumb test.

According to the standard protocol, all patients received antibiotic prophylaxis for 48 hours (starting half an hour before skin incision) and thromboembolic prophylaxis for 20 days (starting on the first postoperative day). Meanwhile, the patients in our study underwent the same rehabilitation protocol. Ankle pump movement was initiated on the day of surgery, full weight-bearing under the supervision of a therapist was initiated on the first postoperative day, and ROM exercises were initiated on the fourth postoperative day, with increasing complexity according to the condition of the patients.

Clinical Evaluations

In each postoperative evaluation, the new KSS [21] was used to assess the knee score, satisfaction score, expectation score and functional activity score. The WOMAC and VAS scores were also used as patient-reported outcomes. Furthermore, ROM was also evaluated. During the ROM measurements, a goniometer was centered on the lateral femoral condyle with one arm placed along the long axis of the femur pointing to the greater trochanter and the other arm placed along the long axis of the tibia pointing to the lateral malleolus; thus, the ROM was obtained [22]. Meanwhile, the patellofemoral functions were evaluated and recorded. A standardized questionnaire including questions regarding the presence of AKP when climbing stairs, rising from a chair or exiting an automobile were also asked of all patients as a means of identifying symptoms related to the patellofemoral joint. In addition, a physician-rated Feller PFS and several physical examinations, including a patellar glide test (medial and lateral translations), a grind test (isometric quadriceps contraction with the patella immobilized and the knee in extension, thus forcing the patella into the trochlear groove) and patellar edge tenderness (isometric quadriceps contraction with the patella immobilized and the knee in extension while pressing sites around the patella), of every patient were measured and recorded, as well as measurement of thigh circumferences (15 cm above the proximal patella). Additionally, complications and revisions were determined based on both the inpatient and outpatient medical records of each patient.

Radiographic Assessments

Preoperative and postoperative long-standing films were obtained with subjects standing barefoot with the patella oriented forward according to Paley’s criteria [23]. Routine anteroposterior, lateral and standard skyline views were obtained thereafter. All of the following radiographic measurements are shown in Fig. 1. The hip-knee-ankle angle (HKA) was defined as the angle formed by the intersection of a line from the center of the head of the femur to the knee center landmark and a second line from the center of the ankle talus to the knee center landmark as described by McDaniel et al. [24]. The lateral distal femoral angle (LDFA) and the medial proximal tibial angle (MPTA) were measured as reported by Cip et al. and Chen et al. [25, 26], and the femoral flexion angle (FFA) and tibial slope were measured as described by Frederick et al. [27]. The lateral patellar tilt (LPT) and lateral patellar displacement (LPD) were evaluated as presented by Meftah et al. [28] and Laurin et al. [29]. The patellar height was determined by the Insall-Salvati ratio (IS). Aseptic loosening was indicated by the presence of radiolucent lines beyond 2 mm and gross shifting of components that caused subsidence or tilting [27]. HKA, LPT and LPD were measured before and after surgery. Evaluation of the radiographic assessments was performed using the picture Archiving and Communication System (PACS). The accepted values used in our study for the normal lower limb mechanical axis were (1) 0° ± 3° for HKA [26]; (2) 90° ± 3° for LDFA and MPTA [26]; (3) < 10° for LPT [30, 31]; (4) ≥ -5 mm and < 4 mm for LPD [30, 31]; and (5) ≥ 0.8 and ≤ 1.2 for IS. Two orthopedic surgeons skilled in TKA who were blinded to the surgical method performed the measurements, which were recorded with an accuracy of 0.1° and 0.1 mm. To test the reliability of these measurements, all variables were measured twice at 1-week intervals. For all measurements, the intraclass correlation coefficient of intraobserver reliability was > 0.92, whereas the intraclass correlation coefficient of interobserver reliability was > 0.86.

Statistical Analysis

The descriptive statistics are summarized as the mean and standard deviation (SD). Analysis of variance with a post hoc test (Tukey’s method) was used to compare the continuous variances. The Chi-Square test was used to compare the nominal variables, including gender, affected side and outliers. The follow-up time was evaluated as a predisposing factor affecting the clinical outcomes using multiple regression analysis. Statistical analysis was performed using SPSS software (version 22.0; SPSS, Inc., Chicago, IL), and the normal distribution was assessed by the Kolmogorov-Smirnov test. P < 0.05 was considered statistically significant.

Results

Overall, 93 patients (110 TKAs) were included for analysis of the clinical results at a follow-up of 10 to 17 years, which consisted of 28 patients (32 TKAs) in the MMP group, 39 patients (47 TKAs) in the QS group, and 26 patients (31 TKAs) in the MP group. Our follow-up rate was 73% for the MMP group, 78% for the QS group and 69% for the MP group. The mean follow-up for the MMP TKA group was 150.8 months (range, 124-171 months), 135.3 months (range, 120-151) for the QS TKA group, and 175.4 months (range, 150-203 months) for the MP TKA group; the differences among the three groups were statistically significant (P < 0.01). There were no significant differences among the three groups in terms of affected side, gender, age (at the time points of operation and follow-up), height, weight, BMI, or preoperative measurements, including HKA, LPT, LPD, KSS, ROM or VAS (Table 1).

Clinical outcomes

Clinical evaluations showed that there were no statistically significant differences among the three approaches for TKA (adjusted P >0.216) (Table 2). There were no differences in any section or in the total scores of the new KSS or WOMAC. The ROM, VAS and thigh circumference also did not differ among the three groups. Regarding the patellofemoral functions, including AKP, Feller PFS, and patellar physical examinations, no statistically significant differences were found based on the scores or records.

Complications and revisions

In the MP group, one patient developed deep vein thrombosis after surgery, which was suspected based on the swelling of the calf and was confirmed by venous ultrasound. In the QS group, one patient had a deep infection three months after the operation, which was successfully treated after surgical debridement and oral antibiotic therapy. No other intraoperative or postoperative complications were observed during follow-up in the MMP group. For the revision, one patient in the QS group had a revision of patella resurfacing due to patellar component loosening three years after her primary TKA, and one patient in the MMP group underwent a total revised TKA owing to aseptic loosening after 11 years, which was found at the follow-up. No revisions were required in the MP group. No significant differences among the three groups were found regarding complications and reoperation rate (P > 0.05).

Radiographic Results

The postoperative radiographic results are summarized in Table 3, and no statistically significant differences were detected among the three groups in the values of angles or the outliers with regard to lower limb mechanical axis, femoral or tibial component positions in the coronal or sagittal planes, or in patellar position.

Discussion

Regarding the two hypotheses, relevant results showed that minimally invasive approaches would not yield better patellofemoral functions and no significant differences were found among the three groups in terms of clinical outcomes, radiographic evaluations, suggesting that no approach is superior to the other two regarding these results.

Compared with the MP approach, the MMP and QS approaches for TKA have two main differences in the present study. First, the arthrotomy extended into the quadriceps tendon less than 4 cm above the upper pole of the patella in the MMP and QS groups but extended 6-8 cm in the MP group; second, the patella was everted from the beginning of the femoral resection to the end when patella resurfacing was performed in the MP group, whereas in the MMP and QS groups, the patella was not everted during the surgery. Many comparative studies of the MMP, QS and MP approaches have reported good clinical results but inferior lower limb mechanical axis and malposition at the short-term follow-up for MMP [32, 33] and QS [8, 34-36] because of the limited working space compared with the MP approach. In addition, some studies indicated that the MP approach may affect patellar tracking, AKP and the patellar position [8, 34-36]. Therefore, we performed a comprehensive evaluation of patellofemoral function in addition to the overall knee score in the clinical investigations.

There are a number of studies that have compared the clinical and radiographic differences among the MMP, QS and MP approaches [34, 37, 41-44], but few of them had a follow-up of at least 10 years. In a retrospective study with a mean follow-up of 5 years, Huang et al.[37] reported that the MMP and QS approaches led to more appropriate LPT and LPD than the conventional MP approach did. Chiang et al.[8] conducted a prospective and randomized study with a mean follow-up of 2 years and reported that patients undergoing QS and MP TKA had comparable clinical outcomes, and that the QS TKA was more time consuming surgically and resulted in a less accurate prosthesis position. In a retrospective study with a mean follow-up of 2 years, Lin et al.[45] showed that the QS approach provided inferior radiographic results with similar clinical outcomes when compared with the MP approach. In 2018, Kazarian et al. [46] conducted a meta-analysis of randomized controlled trials (RCTs) of the QS approach and MP approach, in which all the studies were no more than 2 years long ,and reported that the QS approach to TKA failed to demonstrate clinically significant advantages but showed increased lower limb mechanical axis and femoral and tibial prothesis frontal position. Our study is a more than 10-year study aimed at the long-term results, showing no statistically significant differences among the three approaches for TKA in terms of clinical outcomes, radiographic outcomes and prothesis survival rate.

Some studies have shown that the MP approach affects patellar tracking, AKP and the position of the patella [37-40] because the MMP and QS approaches preserve the majority of the extensor mechanism. Some studies have indicated that the position of the femoral and patellar protheses, especially when poor rotational alignment occurs, can lead to AKP [47]. AKP is a common reason for reoperation or revision [40]. Therefore, we conducted the current study and included the AKP questionnaire, Feller PFS, and patella physical examinations. Nevertheless, we did not find a statistically significant difference among them, which was consistent with the radiographic assessments. Furthermore, weakness of the quadriceps muscle is associated with patellofemoral function [48]. When patients are discharged from the hospital and reexamined in outpatient clinics, we always advise them to exercise the quadriceps muscle, usually by squatting. There is a rough estimate that the amount of quadriceps atrophy is indicative of the amount of weakness present [49], so we measured the thigh circumference of every patient, and no statistically significant difference was noticed, which was consistent with the results of patellofemoral function.

Longevity is one of the concerns in TKA, and the survivorship of implants is dependent on the patient demographics, the surgical technique and implant-related factors [50, 51]. Incorrect positioning of the implant and improper mechanical axis of the lower limb can lead to accelerated implant wear and loosening, as well as suboptimal function. Aseptic loosening, instability, and malalignment were the most common reasons for late revision [52-55]. In this study, no differences were found in the value of or in the outliers of the radiographic assessment angles. We believe that the MMP and QS approaches not only do not increase the risk of malalignment and malposition of the components but also do not increase the reoperation rate of TKA. Our results are consistent with those from other studies [34, 56], indicating that radiographic outcomes were not compromised with the MMP and QS approaches. King et al. [44] demonstrated that a substantial learning curve (fifteen procedures) may be required for surgeons before reaching steady results using the QS approach, so we recommend that surgeons gradually decrease quadriceps exposure in order for patients to gain advantages of the TKA procedure.

In the present study, we conducted long-term follow-ups for a minimum of 10 years in which detailed evaluations of the postoperative clinical outcomes and radiographic assessments were measured. The new KSS system [21] has been recognized as a more efficient method to primarily differentiate the activities contributing to the function score compared with the old KSS system. In addition, some studies have demonstrated that the knee function score declines gradually [21] and that the alignment and prothesis position worsen during the long-term postoperative period [38], so we performed a multiple regression analysis, and the results were the same.

This study has several limitations. First, this study was limited by its retrospective design. Second, although we conducted a multiple linear regression, the significant difference in the follow-up time among groups could still introduce some degree of bias. Third, the small cohort sizes led to insufficient observations to determine the level of statistical significance. Fourth, only approximately 65% of the patients were able to directly be evaluated at the long-term follow-up. However, this follow-up rate is typical of the follow-up rate for TKA performed in elderly people [58, 59] due to a high number of patients faced with nonrelated TKA, including back pain, hip and ankle disease.

This study also has several strengths. This study is one of the few studies to report long-term postoperative clinical and radiographic outcomes for these three approaches to TKA. All surgeries were performed at a single center by the same surgical team using only one type of TKA, which allowed for better consistency among these three groups. Our study used the new KSS to assess the clinical outcomes, which provides sufficient detail to evaluate the functional capabilities of the knee [21].

Conclusions

In conclusion, our study demonstrated that no one approach for TKA was superior to another. Successful survival for these three clinical approaches was achieved. The choice of approach depended on the status of patient and the surgeon’s preference.

Abbreviations

MMP: mini-medial parapatellar; QS: quadriceps-sparing; MP: medial parapatellar; TKA: total knee arthroplasty; KSS: new American Knee Society score; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; VAS: visual analogue scale; ROM: range of motion; AKP: anterior knee pain; PFS: patellofemoral score; LDFA: lateral distal femoral angle; FFA: femoral flexion angle; MPTA: medial proximal tibial angle; LPD: lateral patella displacement; LPT: lateral patella tilt; BMI: body mass index; HKA: hip-knee-ankle angle; TSA: tibial slope angle; PACS: picture Archiving and Communication System; SD: standard deviation; RCTs: randomized controlled trials; IS: Insall-Salvati   

Declarations

Ethical Approval and Consent to participate

This retrospective study was approved by the Ethics Committee of the Peking University Third Hospital (IRB00006761-2011072). Written informed consent was obtained by all participants.

Consent for publication

Not applicable.

Availability of data and materials

The datasets analyzed during the current study are available from the corresponding author upon reasonable request.

Competing interests

The authors declare that they have no competing interests.

Funding

Not applicable.

Authors’ contributions

Conception and design: YFZ, YJK. Analysis and interpretation of the data: YFZ, SZW, FBS. Drafting of the article: YFZ, SZW, ZJY. Critical revision of the article for important intellectual content: YJK, JD. Final approval of the article: YFZ, SZW, YJK. All authors read and approved the final manuscript.

Acknowledgments

This study was funded by the National Key R&D Program of China (2017YFB1303000).

References

  1. Ethgen O, Bruyere O, Richy F, Dardennes C, Reginster JY. Health-related quality of life in total hip and total knee arthroplasty. A qualitative and systematic review of the literature. J Bone Joint Surg Am. 2004; 86-A(5):963-974.
  2. Lizaur-Utrilla A, Martinez-Mendez D, Miralles-Munoz FA, Marco-Gomez L, Lopez-Prats FA. Comparable outcomes after total knee arthroplasty in patients under 55 years than in older patients: a matched prospective study with minimum follow-up of 10 years. Knee Surg Sports Traumatol Arthrosc. 2017; 25(11):3396-3402.
  3. Ishii Y, Noguchi H, Sato J, Sakurai T, Toyabe SI. Comparison of long-term clinical outcomes after bilateral mobile-bearing total knee arthroplasties using PCL-retaining and PCL-substituting implants in the same patients. Knee Surg Sports Traumatol Arthrosc. 2017; 25(12):3711-3717.
  4. D'Amato M, Ensini A, Leardini A, Barbadoro P, Illuminati A, Belvedere C. Conventional versus computer-assisted surgery in total knee arthroplasty: comparison at ten years follow-up. Int Orthop. 2018.
  5. Unwin O, Hassaballa M, Murray J, Harries W, Porteous A. Minimally invasive surgery (MIS) for total knee replacement; medium term results with minimum five year follow-up. Knee. 2017; 24(2):454-459.
  6. Wu Y, Zeng Y, Bao X, Xiong H, Hu Q, Li M, et al. Comparison of mini-subvastus approach versus medial parapatellar approach in primary total knee arthroplasty. Int J Surg. 2018; 57:15-21.
  7. Lin SY, Chen CH, Fu YC, Huang PJ, Lu CC, Su JY, et al. Comparison of the clinical and radiological outcomes of three minimally invasive techniques for total knee replacement at two years. Bone and Joint Journal. 2013; 95 B(7):906-910.
  8. Chiang H, Lee CC, Lin WP, Jiang CC. Comparison of quadriceps-sparing minimally invasive and medial parapatellar total knee arthroplasty: a 2-year follow-up study. J Formos Med Assoc. 2012; 111(12):698-704.
  9. Yang JH, Yoon JR, Pandher DS, Oh KJ. Clinical and radiologic outcomes of contemporary 3 techniques of TKA. Orthopedics. 2010; 33(10 Suppl):76-81.
  10. Karpman RR, Smith HL. Comparison of the early results of minimally invasive vs standard approaches to total knee arthroplasty: a prospective, randomized study. J Arthroplasty. 2009; 24(5):681-688.
  11. Lin WP, Lin J, Horng LC, Chang SM, Jiang CC. Quadriceps-sparing, minimal-incision total knee arthroplasty: a comparative study. J Arthroplasty. 2009; 24(7):1024-1032.
  12. Huang AB, Wang HJ, Yu JK, Yang B, Ma D, Zhang JY. Optimal patellar alignment with minimally invasive approaches in total knee arthroplasty after a minimum five year follow-up. Int Orthop. 2016; 40(3):487-492.
  13. Ritter MA, Faris PM, Keating EM, Meding JB. Postoperative alignment of total knee replacement. Its effect on survival. Clin Orthop Relat Res. 1994(299):153-156.
  14. Ritter MA, Davis KE, Davis P, Farris A, Malinzak RA, Berend ME, et al. Preoperative malalignment increases risk of failure after total knee arthroplasty. J Bone Joint Surg Am. 2013; 95(2):126-131.
  15. Parratte S, Pagnano MW, Trousdale RT, Berry DJ. Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements. J Bone Joint Surg Am. 2010; 92(12):2143-2149.
  16. Kim YH, Park JW, Kim JS, Park SD. The relationship between the survival of total knee arthroplasty and postoperative coronal, sagittal and rotational alignment of knee prosthesis. Int Orthop. 2014; 38(2):379-385.
  17. Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res. 1989(248):13-14.
  18. Insall J. A midline approach to the knee. J Bone Joint Surg Am. 1971; 53(8):1584-1586.
  19. Tenholder M, Clarke HD, Scuderi GR. Minimal-incision total knee arthroplasty: the early clinical experience. Clin Orthop Relat Res. 2005; 440:67-76.
  20. Aglietti P, Baldini A, Sensi L. Quadriceps-sparing versus mini-subvastus approach in total knee arthroplasty. Clin Orthop Relat Res. 2006; 452:106-111.
  21. Scuderi GR, Bourne RB, Noble PC, Benjamin JB, Lonner JH, Scott WN. The new Knee Society Knee Scoring System. Clin Orthop Relat R. 2012; 470(1):3-19.
  22. Brosseau L, Balmer S, Tousignant M, O'Sullivan JP, Goudreault C, Goudreault M, et al. Intra- and intertester reliability and criterion validity of the parallelogram and universal goniometers for measuring maximum active knee flexion and extension of patients with knee restrictions. Arch Phys Med Rehabil. 2001; 82(3):396-402.
  23. Cooke TD, Sled EA, Scudamore RA. Frontal plane knee alignment: a call for standardized measurement. J Rheumatol. 2007; 34(9):1796-1801.
  24. McDaniel G, Mitchell KL, Charles C, Kraus VB. A comparison of five approaches to measurement of anatomic knee alignment from radiographs. Osteoarthr Cartilage. 2010; 18(2):273-277.
  25. Cip J, Obwegeser F, Benesch T, Bach C, Ruckenstuhl P, Martin A. Twelve-Year Follow-Up of Navigated Computer-Assisted Versus Conventional Total Knee Arthroplasty: A Prospective Randomized Comparative Trial. J Arthroplasty. 2018; 33(5):1404-1411.
  26. Chen JY, Yeo SJ, Yew AK, Tay DK, Chia SL, Lo NN, et al. The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2014; 22(3):630-635.
  27. Ewald FC. The Knee Society total knee arthroplasty roentgenographic evaluation and scoring system. Clin Orthop Relat Res. 1989(248):9-12.
  28. Meftah M, Jhurani A, Bhat JA, Ranawat AS, Ranawat CS. The effect of patellar replacement technique on patellofemoral complications and anterior knee pain. J Arthroplasty. 2012; 27(6):1075-1080.
  29. Laurin CA, Dussault R, Levesque HP. The tangential x-ray investigation of the patellofemoral joint: x-ray technique, diagnostic criteria and their interpretation. Clin Orthop Relat Res. 1979(144):16-26.
  30. Wilson T. The measurement of patellar alignment in patellofemoral pain syndrome: are we confusing assumptions with evidence? J Orthop Sports Phys Ther. 2007; 37(6):330-341.
  31. Heesterbeek PJ, Beumers MP, Jacobs WC, Havinga ME, Wymenga AB. A comparison of reproducibility of measurement techniques for patella position on axial radiographs after total knee arthroplasty. Knee. 2007; 14(5):411-416.
  32. Stevens-Lapsley JE, Bade MJ, Shulman BC, Kohrt WM, Dayton MR. Minimally invasive total knee arthroplasty improves early knee strength but not functional performance: a randomized controlled trial. J Arthroplasty. 2012; 27(10):1812-1819.
  33. Li C, Zeng Y, Shen B, Kang P, Yang J, Zhou Z, et al. A meta-analysis of minimally invasive and conventional medial parapatella approaches for primary total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2015; 23(7):1971-1985.
  34. Karpman RR, Smith HL. Comparison of the early results of minimally invasive vs standard approaches to total knee arthroplasty: a prospective, randomized study. J Arthroplasty. 2009; 24(5):681-688.
  35. Chin PL, Foo LS, Yang KY, Yeo SJ, Lo NN. Randomized controlled trial comparing the radiologic outcomes of conventional and minimally invasive techniques for total knee arthroplasty. J Arthroplasty. 2007; 22(6):800-806.
  36. Huang HT, Su JY, Chang JK, Chen CH, Wang GJ. The early clinical outcome of minimally invasive quadriceps-sparing total knee arthroplasty: report of a 2-year follow-up. J Arthroplasty. 2007; 22(7):1007-1012.
  37. Huang AB, Wang HJ, Yu JK, Yang B, Ma D, Zhang JY. Optimal patellar alignment with minimally invasive approaches in total knee arthroplasty after a minimum five year follow-up. Int Orthop. 2016; 40(3):487-492.
  38. Ozkoc G, Hersekli MA, Akpinar S, Ozalay M, Uysal M, Cesur N, et al. Time dependent changes in patellar tracking with medial parapatellar and midvastus approaches. Knee Surg Sports Traumatol Arthrosc. 2005; 13(8):654-657.
  39. Miyagi T, Matsuda S, Miura H, Nagamine R, Urabe K, Inoue S, et al. Changes in patellar tracking after total knee arthroplasty: 10-year follow-up of Miller-Galante I knees. Orthopedics. 2002; 25(8):811-813.
  40. Duan G, Liu C, Lin W, Shao J, Fu K, Niu Y, et al. Different Factors Conduct Anterior Knee Pain Following Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis. J Arthroplasty. 2018; 33(6):1962-1971.
  41. Lin WP, Lin J, Horng LC, Chang SM, Jiang CC. Quadriceps-sparing, minimal-incision total knee arthroplasty: a comparative study. J Arthroplasty. 2009; 24(7):1024-1032.
  42. Yu JK, Yu CL, Ao YF, Gong X, Wang YJ, Wang S, et al. Comparative study on early period of recovery between minimally invasive surgery total knee arthroplasty and minimally invasive surgery-quadriceps sparing total knee arthroplasty in Chinese patients. Chin Med J (Engl). 2008; 121(15):1353-1357.
  43. Matsumoto T, Muratsu H, Kubo S, Mizuno K, Kinoshita K, Ishida K, et al. Soft tissue balance measurement in minimal incision surgery compared to conventional total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2011; 19(6):880-886.
  44. King J, Stamper DL, Schaad DC, Leopold SS. Minimally invasive total knee arthroplasty compared with traditional total knee arthroplasty. Assessment of the learning curve and the postoperative recuperative period. J Bone Joint Surg Am. 2007; 89(7):1497-1503.
  45. Lin SY, Chen CH, Fu YC, Huang PJ, Lu CC, Su JY, et al. Comparison of the clinical and radiological outcomes of three minimally invasive techniques for total knee replacement at two years. Bone Joint J. 2013; 95-B(7):906-910.
  46. Kazarian GS, Siow MY, Chen AF, Deirmengian CA. Comparison of Quadriceps-Sparing and Medial Parapatellar Approaches in Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials. J Arthroplasty. 2018; 33(1):277-283.
  47. Bell SW, Young P, Drury C, Smith J, Anthony I, Jones B, et al. Component rotational alignment in unexplained painful primary total knee arthroplasty. Knee. 2014; 21(1):272-277.
  48. Werner S. Anterior knee pain: an update of physical therapy. Knee Surg Sports Traumatol Arthrosc. 2014; 22(10):2286-2294.
  49. Kilinc BE, Kara A, Camur S, Oc Y, Celik H. Isokinetic dynamometer evaluation of the effects of early thigh diameter difference on thigh muscle strength in patients undergoing anterior cruciate ligament reconstruction with hamstring tendon graft. J Exerc Rehabil. 2015; 11(2):95-100.
  50. Sisko ZW, Vasarhelyi EM, Somerville LE, Naudie DD, MacDonald SJ, McCalden RW. Morbid Obesity in Revision Total Knee Arthroplasty: A Significant Risk Factor for Re-Operation. J Arthroplasty. 2019.
  51. Jasper LL, Jones CA, Mollins J, Pohar SL, Beaupre LA. Risk factors for revision of total knee arthroplasty: a scoping review. BMC Musculoskelet Disord. 2016; 17:182.
  52. Khan M, Osman K, Green G, Haddad FS. The epidemiology of failure in total knee arthroplasty: avoiding your next revision. Bone Joint J. 2016; 98-B(1 Suppl A):105-112.
  53. Thiele K, Perka C, Matziolis G, Mayr HO, Sostheim M, Hube R. Current failure mechanisms after knee arthroplasty have changed: polyethylene wear is less common in revision surgery. J Bone Joint Surg Am. 2015; 97(9):715-720.
  54. Sharkey PF, Lichstein PM, Shen C, Tokarski AT, Parvizi J. Why are total knee arthroplasties failing today--has anything changed after 10 years? J Arthroplasty. 2014; 29(9):1774-1778.
  55. Postler A, Lutzner C, Beyer F, Tille E, Lutzner J. Analysis of Total Knee Arthroplasty revision causes. BMC Musculoskelet Disord. 2018; 19(1):55.
  56. Dayton MR, Bade MJ, Muratore T, Shulman BC, Kohrt WM, Stevens-Lapsley JE. Minimally invasive total knee arthroplasty: surgical implications for recovery. J Knee Surg. 2013; 26(3):195-201.
  57. Serna-Berna R, Lizaur-Utrilla A, Vizcaya-Moreno MF, Miralles MF, Gonzalez-Navarro B, Lopez-Prats FA. Cruciate-Retaining vs Posterior-Stabilized Primary Total Arthroplasty. Clinical Outcome Comparison With a Minimum Follow-Up of 10 Years. J Arthroplasty. 2018; 33(8):2491-2495.
  58. Ishii Y, Noguchi H, Sato J, Sakurai T, Toyabe SI. Comparison of long-term clinical outcomes after bilateral mobile-bearing total knee arthroplasties using PCL-retaining and PCL-substituting implants in the same patients. Knee Surg Sports Traumatol Arthrosc. 2017; 25(12):3711-3717.
  59. Callaghan JJ, Beckert MW, Hennessy DW, Goetz DD, Kelley SS. Durability of a cruciate-retaining TKA with modular tibial trays at 20 years. Clin Orthop Relat Res. 2013; 471(1):109-117.

Tables

Table 1 Baseline characteristics and preoperative comparisons [mean (SD/range)]

Variables

MMP

(n = 32)

QS

(n = 47)

MP

(n = 31)

P

Right/Left

16/16

16/31

12/19

0.359

Male/Female

9/23

7/40

4/27

0.218

Age at operation

63.2 (4.9)

64.4 (6.0)

63.1 (5.2)

0.501

Age at follow-up

75.5 (5.5)

75.5 (6.0)

77.0 (4.9)

0.430

Height (cm)

160.2 (8.6)

160.4 (6.7)

162.9 (7.1)

0.271

Weight (kg)

72.4 (12.2)

70.7 (11.5) 

69.0 (12.9)

0.549

BMI

28.2 (4.1)

27.5 (4.3)

29.9 (3.9)

0.088

Preoperative HKA

7.7 (7.5)

9.4 (7.1)

10.3 (7.1)

0.354

Preoperative HKA outliers

31 

44 

30 

0.864

Patellar position

 

 

 

 

Preoperative LPT

2.2 (3.7) 

3.0 (2.9)

3.0 (3.0)

0.455

Preoperative LPT outliers

0 (0%)

1 (2.1%)

1 (3.2%)

0.618

Preoperative LPD 

1.2 (3.6)

0.0 (2.7)

0.1 (3.5)

0.447

Preoperative LPD outliers

1 (3.1%)

2 (4.3%)

1 (3.2%)

0.956

Preoperative KSS 

 

 

 

 

Knee score

49.1 (11.2)

52.1 (9.3)

50.5 (9.5)

0.377

Function score

53.1 (6.8)

55.3 (11.2)

52.4 (10.4)

0.399

Total

104.2 (14.7)

106.8 (15.3)

105.9 (12.6)

0.692

Preoperative ROM

102.3 (9.0)

101.2 (8.2)

101.9 (9.6)

0.855

Preoperative VAS

6.6 (1.0)

6.6 (0.9)

6.5 (0.9)

0.775

Follow-up time (months) 

150.8 (124 172)

135.3 (120 151)

175.4 (150 203)

< 0.01

 

Table 2 Postoperative clinical data [mean (SD/range)]

Variables

Group MMP

(n = 32)

Group QS

(n = 47)

Group MP

(n = 31)

P*

New KSS

 

 

 

 

Pain score (25)

23.7 (3.0)

22.7 (2.8)

22.2 (4.1)

0.172

Satisfaction score (40)

36.8 (4.5)

35.0 (5.6)

33.6 (7.7)

0.122

Expectation score (15)

13.9 (1.7)

13.0 (1.9)

12.8 (3.5)

0.179

Walking/Standing score (30)

22.2 (7.4)

21.2 (7.9)

19.5 (6.5)

0.146

Standard activities score (30)

24.5 (4.7)

23.3 (3.8)

21.9 (7.1)

0.131

Advanced activities score (25)

15.7 (6.7)

13.9 (6.0)

13.3 (7.7)

0.326

Discretionary activities score (15)

6.4 (3.4)

5.7 (2.7)

5.5 (2.1)

0.416

Total

148.2 (18.4)

150.7 (19.1)

144.2 (16.9)

0.524

WOMAC

 

 

 

 

Pain

1.4 (3.7)

0.8 (1.8)

3.0 (7.0)

0.100

Stiffness

1.1 (1.6)

0.4 (1.2)

1.7 (4.6)

0.128

Function

15.7 (11.5)

17.9 (15.4)

22.5 (20.2)

0.229

Total

19.3 (2.7)

18.6 (4.5)

21.2 (3.7)

0.408

Range of motion

119.7 (5.9)

118.3 (7.7)

115.5 (9.5)

0.103

Visual analogue scale

0.6 (1.2)

1.1 (1.2)

1.3 (1.6)

0.122

Thigh circumference

49.0 (3.8)

48.8 (3.7)

47.7 (4.1)

0.518

Patellofemoral functions

 

 

 

 

Anterior knee pain

 

 

 

 

Are you aware of your anterior knee pain when

Climbing stairs? 

3 (9.4%)

8 (17.0%)

4 (12.9%)

0.644

Rising from a chair?

4 (12.5%)

8 (17.0%)

44 (12.9%)

0.892

Exiting an automobile?

4 (12.5%)

8 (17.0%)

44 (12.9%)

0.892

Feller PFS

 

 

 

 

Anterior knee pain (15)

13.7 (2.5)

12.9 (3.1)

13.0 (2.6)

0.793

Quadriceps strength (5)

3.9 (1.0)

3.7 (1.2)

3.6 (0.9)

0.436

Ability to rise from chair (5)

4.3 (1.6)

4.2 (1.7)

4.1 (1.5)

0.624

Stair climbing (5)

4.3 (1.4)

4.5 (1.8)

4.3 (1.4)

0.557

Total

32.7 (4.6)

32.1 (4.1)

31.8 (4.0)

0.625

Patellar glide test pain

2 (6.3%)

3 (6.4%)

0 (0%)

0.513

Patellar grind test pain

2 (6.3%)

3 (6.4%)

0 (0%)

0.513

Patellar edge tenderness

1 (3.1%)

3 (6.4%)

4 (12.9%)

0.172

 

Table 3 Postoperative radiographic data [mean (SD/range)]

Variables

MMP

(n = 32)

QS

(n = 47)

MP

(n = 31)

P*

Lower limb mechanical axis

 

 

 

 

Hip-knee-ankle angle

2.4 (3.0)

3.5 (3.2)

3.0 (1.9)

0.425

Hip-knee-ankle angle outliers

14 (43.8%)

16 (34.0)

11 (35.5%)

0.662

Femoral position

 

 

 

 

Lateral distal femoral angle

90.2 (1.6)

89.7 (1.8)

90.5 (2.0)

0.147

Lateral distal femoral angle outliers

1 (3.1%)

3 (6.4%)

3 (9.7%)

0.480

Femoral component flexion angle

88.6 (1.6)

89.4 (2.0)

88.9 (1.9)

0.076

Tibial position

 

 

 

 

Medial proximal tibial angle

88.3 (3.0)

89.0 (3.5)

88.0 (2.2)

0.347

Medial proximal tibial angle outliers

9 (28.1%)

12 (25.5%)

7 (22.6%)

0.880

Tibial component slope angle

84.5 (1.9)

84.5 (2.8)

84.7 (2.0)

0.942

Patellar position

 

 

 

 

Lateral patellar tilt

2.6 (3.6)

3.2 (3.6)

3.0 (3.3)

0.724

Lateral patellar tilt outliers

1 (3.1%)

1 (2.1%)

1 (3.2%)

1.000

Lateral patellar displacement

0.9 (4.2)

-0.8 (3.7)

-0.1 (3.6)

0.159

Lateral patellar displacement outliers

8 (25.0%)

7 (14.9%)

4 (12.9%)

0.113

Insall-Salvati ratio

1.08 (0.12)

1.05 (0.14)

0.93 (0.17)

0.771

Insall-Salvati ratio outliers

6 (18.8%)

13 (27.7%)

10 (32.3%)

0.460