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Comparative study of three different combination surgical methods for recurrent patella dislocation
Journal of Orthopaedic Science xxx (xxxx) xxx
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Original Article
Comparative study of three different combination surgical methods for recurrent patella dislocation Xing-Liang Wang a, 1, Xiao-Long Wang b, 1, Chao Peng b, Jia-Ji Yang a, Guo-Jun Hua a, Yun-Peng Liu a, * a b
Department of Orthopedic Surgery, The No.904 Hospital of Peoples Liberation Army, Wuxi 214000, China Wuxi Clinical College of Anhui Medical University, Wuxi, 214000, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 March 2019 Received in revised form 18 November 2019 Accepted 20 January 2020 Available online xxx
Purpose: The effects of different combination of surgical techniques for recurrent patella dislocation (RPD) remain unclear. Thus, aim of this study was to investigate the surgical outcomes of different combination of surgical techniques for RPD. Methods: The clinical data of 79 patients with RPD from August 2014 to October 2016 were analysed retrospectively. Knee joint was assessed according to measurements of the congruence angle (CA), patellar tilt angle (PTA) and lateral patellofemoral angle (LPFA). Knee function was evaluated by Kujala patellofemoral score, Lysholm knee score and Tegner score. Patients were followed up by out-patient examination and telephone till October 2018. Results: Preoperative clinical characteristics were similar across groups. It was statistically insignificant among three groups in CA, PTA, LPFA and redislocation rate. In term of knee functions, the MPFL reconstruction and LPR release group had the highest score (Lysholm score: 91.82 ± 4.64, Kujala score: 94.22 ± 4.26, Tegner score: 5.80 ± 1.00, respectively) and the LPR release and MPR plication had the lowest score (Lysholm score: 78.10 ± 6.90, Kujala score: 80.91 ± 4.30, Tegner score: 4.98 ± 1.22, respectively). Conclusion: Three combinations of surgical methods were similar in terms of postoperative joint congruence and redislocation rate, but MPFL reconstruction combined with LPR release is worthy to be promoted with the highest knee function scores. © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
1. Introduction The stability of the patellofemoral joint is mainly maintained by the peripheral bone structure with the medial and lateral ligaments and the strength supported by the quadriceps [1]. Patella dislocation can be easily caused by abnormal tensile stress and patellar movements resulting from loss of normal structural integrity of the patellofemoral joint. Patella dislocations account for 3.3% of all knee joint injuries [2]. The incidence of patellar dislocation has increased during the past several decades and young active persons accounted for the very great proportion [3,4]. Recurrent patellar dislocation (RPD), as the most common complication of acute patellar dislocation, usually causes symptoms (e.g. joint pain, instability, interlocking, sense of dislocation and swelling) affecting
* Corresponding author. E-mail address: [email protected] (Y.-P. Liu). 1 Co-first authors.
performance of daily activities and joint development in patients [5]. Conservative treatments to these RPD patients may not be adequate and surgical treatments are required [6,7]. In almost 90% of all cases, RPD commonly occurs to the lateral side resulting in ruptures of the medial patellofemoral ligament (MPFL) [8,9]. In addition, a recent biomechanical study conducted by Tsubosaka et al. showed that MPFL is the most important soft tissue in preventing patella dislocation and maintaining appropriate patellar tracking [10]. Therefore, when it comes to surgical methods for RPD, restoring the function of the MPFL is one of the most important factors. There are three basic surgical procedures including MPFL reconstruction, lateral patellar retinaculum (LPR) release and medial patellar retinaculum (MPR) plication for correcting patellar movement and instability in patients with RPD. However, the standard consensus has not been established. In this study, we compared combinations of above-mentioned surgical procedures on the effect of RPD using three-dimensional image techniques in order to find a most effective surgical method for RPD.
https://doi.org/10.1016/j.jos.2020.01.008 0949-2658/© 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
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X.-L. Wang et al. / Journal of Orthopaedic Science xxx (xxxx) xxx
2. Materials and methods 2.1. Patients This retrospective study was approved by the institutional review board of the author’s affiliated institutions. We retrospectively reviewed 79 patients diagnosed with RPD between August 2014 and October 2016 who underwent combination of surgical procedures. The patients were informed of possible complications of the surgical procedure and respective advantages and limitations of MPFL reconstruction, LPR release and MPR plication. The inclusion criteria were used in the selection of patients: (1) diffuse pain and patellar instability at the knee joint; (2) diagnosed with RPD or first patellar dislocation with joints instability lasting more than three months; (3) lost structures at the patella MPR with positive apprehension; (4) patellar track tests with increased motility (1.5 cm) when extending or flexing knee joints to 30 . The exclusion criteria were as follows: (1) generalized ligament laxity; (2) previous history of diseases or surgeries related to the knee joint; (3) femoral trochlear dysplasia which required osteotomy; (4) abnormal Q angles of the knee joints; (5) patellar dysplasia or patellar alta. In total, 79 patients were included in this study with informed consents. At the end, three combinations of surgical procedures were determined according to theoretical basis and patients’ will: (1) MPFL reconstruction and subsequent MPR plication group (n ¼ 15); (2) LPR release and subsequent MPR plication group (n ¼ 26); (3) LPR release and subsequent MPFL reconstruction group (n ¼ 38). It should be noticed that the combination strategy of every patient depended on the admission time: MPFL reconstruction plus MPR plication for August 2014 to April 2015, LPR release plus MPR plication for May 2015 to January 2016, LPR release plus MPFL reconstruction for February 2016 to October 2016.
reconstruction, autologous semitendinosus tendons were used for graft of which the average length was 120 ± 10 mm with a diameter of 4.0 mm. A longitudinal incision was made at the medial aspect of the tibial tubercle and the sartorius fascia was severed to expose the semitendinosus tendon which was then extracted for graft as abovementioned. As is shown in Fig. 1a, the patella was placed at the midpoint of the trochlear groove of femur and the reconstructed ligament was fixed at the midpoint and upper one-third of the medial patella with 5-mm pins. A bone tunnel was formed and enlarged with a 6-mm drill slightly behind the highest point of the medial tuberosity of femur and the midpoint of the adductor tubercle. A guide pin introduced the graft into the bone tunnel and the reconstructed ligament was subsequently folded onto the surface of the patella. A absorbable screw was used to fix the tendon in the femoral tunnel. The tension of tendon was adjusted under the arthroscope by pulling the braided suture on bilateral sides of the tendon. The joint congruence and motion track of the patella returned to normal. The scheme of LPR release is shown in Fig. 1b. The patients were placed in the supine position under combined spinal and epidural anesthesia. A curved incision was made at the lateral side of the patella. The tense fibrous structure at the lateral aspect of the patella was cut and the LPR was released to the lower and lateral borders of the patella. The vastus lateralis oblique muscle was partially cut simultaneously to avoid adhesion. As is shown in Fig. 1c, the medial joint capsule and retinaculum were completely cut open and partially removed during MPR plication, and then sutured together with overlapping edges in order to increase the medial tension against the lateral tension. The knots were tied below the superficial fascia and easily moved into fatty tissue if skin and superficial fascia were separated. Knots could become loose if fatty tissue was incorporated, and thus single MPR plication provided very limited effect on patients with recurrent patella dislocation.
2.2. Surgical procedure
2.3. Diagnostic techniques and postoperative assessment
All surgery was conducted by well-trained and experienced surgeons who performed at least 20 operations previously. In MPFL
Diagnosis of RPD is based on the measurement of the congruence angle (CA) [11], patellar tilt angle (PTA) [12], and lateral
Fig. 1. Schemes of three surgery options. (a) MPFL reconstruction; (b) LPR release; (c) MPR plication. MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
X.-L. Wang et al. / Journal of Orthopaedic Science xxx (xxxx) xxx
patellofemoral angle (LPFA) [13] using computed tomography (CT) three-dimensional reconstruction techniques which can observe the structure of the patellofemoral joint at different levels. CT scans have the ability to directly measure the CA, PTA, LPFA at the midpatellar level. Knee joint function was evaluated by Kujala patellofemoral score [14], Lysholm knee score [15] and Tegner score [16]. The combination of these three scoring systems can indicate the overall knee function. In addition, postoperative redislocation rate became as an independent factor to assess the reliability of surgical methods in this study. Postoperative follow-ups were performed through out-patient review or telephone interview every three months till October 2018. The follow-up contents included CT measurements and knee function evaluations. 2.4. Statistical analysis All statistical analyses were performed using SPSS version 19.0 (SPSS Inc., Chicago, IL, USA). Results are presented as mean ± SD. One-way analysis of variance (ANOVA) was used for quantitative data among three groups and Chi-squared test or Fisher’s exact test was used for qualitative data. P values that were less than 0.05 were considered statistically significant. It should be noticed that we used bootstrap (10000 bootstrap samples) which can avoid the small sample bias, to evaluate the 95% confidence interval of postoperative redislocation rate. 3. Results
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3.2. Preoperative CT measurement and knee function results It was statistically insignificant among these three groups in terms of preoperative CT measurement and knee function results including congruence angle (P ¼ 0.430), patellar tilt angle (P ¼ 0.331), lateral patellofemoral angle (P ¼ 0.819), Lysholm knee score (P ¼ 0.184), Kujala patellofemoral score (P ¼ 0.900), and Tegner score (P ¼ 0.673), which are shown in Table 2. Therefore, we could think that all preoperative information of these three group patients associated with this clinical study are similar allowing for comparison. 3.3. Postoperative assessment and follow-up All patients were followed up for 24 months postoperatively. Postoperative 6th-month CT measurements (Table 3) returned to a similar range in all groups and were statistically insignificant in congruence angle, patellar tilt angle and lateral patellar tilt angle (P ¼ 0.336, 0.268 and 0.341, respectively). In terms of postoperative 6th-month knee function evaluation (Table 3), there were statistically significant differences among these three groups (Lysholm score: P ¼ 0.000, Kujala score: P ¼ 0.000, Tegner score: P ¼ 0.002, respectively). The highest and lowest scores were all in the MPFL reconstruction and LPR release group and the LPR release and MPR plication group, respectively. Taken three groups together, 15.2% of the patients (12/79) sustained a redislocation and 84.8% (69/79) remained stable after 24 months. As shown in Table 4, there were no statistically significant differences in postoperative redislocation rate among these three groups (P ¼ 0.538).
3.1. Baseline characteristics 4. Discussion The three group patients’ data of baseline characteristics (i.e. age, gender, Body mass index (BMI), left or right side of dislocation, duration of dislocation and the number of dislocations) are summarized in Table 1. The number of patients in MPFL reconstruction and MPR plication group, LPR release and MPR plication group and MPFL reconstruction and LPR release group, was 15, 26 and 38, respectively. There were no statistically significant differences among the three groups in the baseline characteristics (P>0.05).
There are numerous predisposing factors for patellar dislocation or instability and single surgical option cannot balance the tension of peripatella joints and soft tissues. Numerous techniques have been developed to treat this problem, but the optimal surgical treatment remains controversial. MPFL reconstruction, LPR release and MPR plication are the primary surgical methods for mild patellar joint lesions. In allusion to serious recurrent patellar
Table 1 Baseline characteristics of the study population of three groups. Variables
MPFL reconstruction and MPR plication group (n ¼ 15)
LPR release and MPR plication group (n ¼ 26)
MPFL reconstruction and LPR release group (n ¼ 38)
P value
Age (years) Males/females BMI Left side/right side Duration of dislocation (months) Number of dislocations
23.0 ± 8.3 5/10 24.3 ± 4.4 6/9 17.3 ± 8.4 4.8 ± 2.9
24.9 ± 6.6 11/15 23.0 ± 5.9 10/16 16.9 ± 7.6 3.6 ± 2.2
26.2 ± 6.6 13/25 23.7 ± 4.7 16/22 19.4 ± 5.9 4.3 ± 2.1
0.312 0.769 0.738 0.957 0.315 0.255
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Table 2 Comparison of preoperative patella associated measurements and knee function among three groups.
Congruence angle Patellar tilt angle Lateral patellofemoral angle Lysholm knee score Kujala patellofemoral score Tegner score
MPFL reconstruction and MPR plication group (n ¼ 15)
LPR release and MPR plication group (n ¼ 26)
MPFL reconstruction and LPR release group (n ¼ 38)
P value
32.06 ± 6.40 12.59 ± 3.51 3.44 ± 3.86 56.22 ± 5.94 52.63 ± 5.83 3.16 ± 0.46
31.45 ± 5.52 13.81 ± 2.73 3.03 ± 6.07 54.99 ± 6.39 53.46 ± 5.64 3.24 ± 0.45
33.06 ± 3.72 13.54 ± 2.25 2.59 ± 3.56 57.67 ± 5.09 53.04 ± 5.61 3.27 ± 0.32
0.430 0.331 0.819 0.184 0.900 0.673
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
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Table 3 Comparison of postoperative 6th-month patella associated measurements and knee function among three groups.
Congruence angle Patellar tilt angle Lateral patellofemoral angle Lysholm knee score Kujala patellofemoral score Tegner score
MPFL reconstruction and MPR plication group (n ¼ 15)
LPR release and MPR plication group (n ¼ 26)
MPFL reconstruction and LPR release group (n ¼ 38)
P value
13.38 ± 7.40 8.03 ± 1.30 9.63 ± 4.54 86.76 ± 4.89 88.00 ± 5.99 4.74 ± 1.10
16.20 ± 6.60 7.29 ± 1.42 8.10 ± 2.65 78.10 ± 6.90 80.91 ± 4.30 4.98 ± 1.22
14.96 ± 4.60 7.48 ± 1.44 8.93 ± 3.11 91.82 ± 4.64 94.22 ± 4.26 5.80 ± 1.00
0.336 0.268 0.341 0.000 0.000 0.002
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Table 4 Comparison of postoperative 24th-month redislocation rate among three groups.
MPFL reconstruction and MPR plication (n ¼ 15) LPR release and MPR plication (n ¼ 26) MPFL reconstruction and LPR release (n ¼ 38) P value
Number of redislocation
Bootstrap 95% C.l.
Postoperative redislocation rate
3 5 4
0e19.23% 3.85e34.62% 0e19.23%
20.0% 19.23% 10.53% 0.538
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
dislocation, several researchers have proposed combination surgical treatments based on aforementioned primary surgical methods [7,17,18]. Therefore, this study compared the efficiency of three combination surgical options for RPD. A study conducted by Du et al. [19] in 2016 showed that the MPFL reconstruction and LPR release had the best clinical outcomes among these three methods in terms of joint congruence and knee function. Similarly, this study also showed that the postoperative 6th-month knee function scores of patients in the MPFL reconstruction and LPR release group were highest indicating that MPFL reconstruction combined with LPR release might be a best choice to restore the knee function for patients with RPD. However, patellar position and rotation were all corrected to the same degree after each type of surgery in this study. As is shown in Fig. 2, postoperative CT measurements of a female patient who underwent LPR release and subsequent MPR plication causing the lowest knee function scores, showed that CA, PTA and LFPA have been significantly improved. It is also possible that we could get different results if we adopted more indicators such as the postoperative joint congruence and lateral patellar translation to assess the joint congruence more comprehensively.
The ligaments surrounding the patella are essential in preventing the patella dislocation. Therefore, a force balance needs to be achieved by surrounding soft-tissue structures especially at the medial and lateral part of the patella. LPR release and MPR plication, which can partially improve peripatella tesion and patella movements, are frequently used in RPD. Furthermore, some surgeons proposed MPR plication combined with LPR release for patients with RPD [20,21]. As mentioned earlier, MPFL is the main structure stabilizing the patellofemoral joint that can prevent patella dislocation [10,22]. It was reported that MPFL reconstruction as a wellestablished surgical option could improve the condition of patellar instability [23]. A prospective study conducted by Zhao et al. [24] for 5 years comparing MPFL reconstruction and MPR plication have shown that MPFL reconstruction can result in better static patellar position and functional outcome than MPR plication for RPD in adults. In this study, the lowest knee function scores in the group without MPFL reconstruction might also indicate that MPFL reconstruction plays an irreplaceable role in combination treatments. We planned to use 2 years to compare redislocation rates according to a study conducted by M.Petri et al., in 2012 [25].
Fig. 2. A 27-year-old female patient who underwent LPR release and MPR plication. (a) Preoperative CT of the knee. (b) Postoperative CT showed that congruence angle, patellar tilt angle and lateral patellofemoral angle have been significantly improved.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
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The postoperative 24th-month redislocation rates revealed no statistically significant differences among these three groups with different combination surgical options. We supposed that it required more time to compare redislocation rate more precisely just like the study conducted by Zhao et al. using 5 years [24]. In conclusion, there were no significant differences among three combination surgical options in terms of postoperative joint congruence. However, it is worthwhile to generalize the combination of MPFL reconstruction and LPR release because of its best clinical outcomes including highest knee function scores. Author contributions Xing-Liang Wang: Study conception, Collecting and analyzing the data, Writing and editing the manuscript. Xiao-Long Wang: Collecting and analyzing the data, Writing and editing the manuscript. Chao Peng: Collecting and analyzing the data, Writing and editing the manuscript. Jia-Ji Yang: Collecting and analyzing the data. Guo-Jun Hua: Collecting and analyzing the data. Yun-Peng Liu: Study conception, Collecting and analyzing the data, Writing and editing the manuscript. This research was supported by the Youth program of Wuxi Municipal Health Planning Commission (Q201772, China) and the medicine and public health technology program of Wuxi science and technology development (CSE31N1618, China). Ethical statement This study was approved by the institutional review board of the No.904 Hospital of Peoples Liberation Army. Declaration of Competing Interest On behalf of all authors, the corresponding author states that there is no conflict of interest. References [1] Biabanimoghadam M, Motealleh A, Cowan SM. Core muscle recruitment pattern during voluntary heel raises is different between patients with patellofemoral pain and healthy individuals. Knee 2016 Jun;23(3):382e6. [2] Majewski M, Susanne H, Klaus S. Epidemiology of athletic knee injuries: a 10year study. Knee 2006 Jun;13(3):184e8. [3] Gravesen KS, Kallemose T, Blønd L, Troelsen A, Barfod KW. High incidence of acute and recurrent patellar dislocations: a retrospective nationwide epidemiological study involving 24.154 primary dislocations. Knee Surg Sports Traumatol Arthrosc 2018 Apr;26(4):1204e9. [4] Hsiao M, Owens BD, Burks R, Sturdivant RX, Cameron KL. Incidence of acute traumatic patellar dislocation among active-duty United States military service members. Am J Sports Med 2010 Oct;38(10):1997e2004. [5] Colvin AC, West RV. Patellar instability. J Bone Jt Surg Am Vol 2008 Dec;90(12):2751e62. [6] Fithian DC, Paxton EW, Cohen AB. Indications in the treatment of patellar instability. J Knee Surg 2004 Jan;17(1):47e56.
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[7] Dannawi Z, Khanduja V, Palmer CR, El-Zebdeh M. Evaluation of the modified Elmslie-Trillat procedure for patellofemoral dysfunction. Orthopedics 2010 Jan;33(1):13. [8] Balcarek P, Walde TA, Frosch S, Schüttrumpf JP, Wachowski MM, Stürmer KM, Frosch KH. Patellar dislocations in children, adolescents and adults: a comparative MRI study of medial patellofemoral ligament injury patterns and trochlear groove anatomy. Eur J Radiol 2011 Sep;79(3):415e20. [9] Balcarek P, Jung K, Ammon J, Walde TA, Frosch S, Schüttrumpf JP, Stürmer KM, Frosch KH. Anatomy of lateral patellar instability: trochlear dysplasia and tibial tubercle-trochlear groove distance is more pronounced in women who dislocate the patella. Am J Sports Med 2010 Nov;38(11):2320e7. [10] Tsubosaka M, Muratsu H, Takayama K, Miya H, Kuroda R, Matsumoto T. Comparison of intraoperative soft tissue balance between cruciate-retaining and posterior-stabilized total knee arthroplasty performed by a newly developed medial preserving gap technique. J Arthroplasty 2018 Mar;33(3): 729e34. [11] Merchant AC, Mercer RL, Jacobsen RH, Cool CR. Roentgenographic analysis of patellofemoral congruence. J Bone Jt Surg Am Vol 1974 Oct;56(7):1391e6. [12] Schutzer SF, Ramsby GR, Fulkerson JP. The evaluation of patellofemoral pain using computerized tomography. A preliminary study. Clin Orthop Relat Res 1986 Mar;(204):286e93. vesque HP, Dussault R, Labelle H, Peides JP. The abnormal lateral [13] Laurin CA, Le patellofemoral angle: a diagnostic roentgenographic sign of recurrent patellar subluxation. J Bone Jt Surg Am Vol 1978 Jan;60(1):55e60. €ma €l€ [14] Kujala T, Alho K, Kekoni J, Ha ainen H, Reinikainen K, Salonen O, Stand€ ld-Nordenstam CG, Na €a €ta €nen R. Auditory and somatosensory eventertskjo related brain potentials in early blind humans. Exp Brain Res 1995;104(3): 519e26. [15] Lysholm J, Gillquist J. Evaluation of knee ligament surgery results with special emphasis on use of a scoring scale. Am J Sports Med 1982 May-Jun;10(3): 150e4. [16] Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop Relat Res 1985 Sep;(198):43e9. [17] Wegmann H, Würnschimmel C, Kraus T, Singer G, Eberl R, Till H, Sperl M. Medial patellofemoral ligament (MPFL) reconstruction in combination with a modified grammont technique leads to favorable mid-term results in adolescents with recurrent patellofemoral dislocations. Knee Surg Sports Traumatol Arthrosc 2018 Mar;26(3):705e9. [18] Damasena I, Blythe M, Wysocki D, Kelly D, Annear P. Medial patellofemoral ligament reconstruction combined with distal realignment for recurrent dislocations of the patella: 5-year results of a randomized controlled trial. Am J Sports Med 2017 Feb;45(2):369e76. [19] Du H, Tian XX, Guo FQ, Li XM, Ji TT, Li B, Li TS. Evaluation of different surgical methods in treating recurrent patella dislocation after three-dimensional reconstruction. Int Orthop 2017 Dec;41(12):2517e24. [20] Nam EK, Karzel RP. Mini-open medial reefing and arthroscopic lateral release for the treatment of recurrent patellar dislocation: a medium-term follow-up. Am J Sports Med 2005 Feb;33(2):220e30. [21] Coons DA, Barber FA. Thermal medial retinaculum shrinkage and lateral release for the treatment of recurrent patellar instability. Arthroscopy 2006 Feb;22(2):166e71. [22] Kita K, Tanaka Y, Toritsuka Y, Yonetani Y, Kanamoto T, Amano H, Nakamura N, Horibe S. Patellofemoral chondral status after medial patellofemoral ligament reconstruction using second-look arthroscopy in patients with recurrent patellar dislocation. J Orthop Sci 2014 Nov;19(6):925e32. [23] Siebold R, Karidakis G, Fernandez F. Clinical outcome after medial patellofemoral ligament reconstruction and autologous chondrocyte implantation following recurrent patella dislocation. Knee Surg Sports Traumatol Arthrosc 2014 Oct;22(10):2477e83. [24] Zhao J, Huangfu X, He Y. The role of medial retinaculum plication versus medial patellofemoral ligament reconstruction in combined procedures for recurrent patellar instability in adults. Am J Sports Med 2012 Jun;40(6): 1355e64. [25] Petri M, Liodakis E, Hofmeister M, Despang FJ, Maier M, Balcarek P, Voigt C, Haasper C, Zeichen J, Stengel D, Krettek C, Frosch KH, Lill H, Jagodzinski M. Operative vs conservative treatment of traumatic patellar dislocation: results of a prospective randomized controlled clinical trial. Arch Orthop Trauma Surg 2013 Feb;133(2):209e13.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Original Article
Comparative study of three different combination surgical methods for recurrent patella dislocation Xing-Liang Wang a, 1, Xiao-Long Wang b, 1, Chao Peng b, Jia-Ji Yang a, Guo-Jun Hua a, Yun-Peng Liu a, * a b
Department of Orthopedic Surgery, The No.904 Hospital of Peoples Liberation Army, Wuxi 214000, China Wuxi Clinical College of Anhui Medical University, Wuxi, 214000, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 March 2019 Received in revised form 18 November 2019 Accepted 20 January 2020 Available online xxx
Purpose: The effects of different combination of surgical techniques for recurrent patella dislocation (RPD) remain unclear. Thus, aim of this study was to investigate the surgical outcomes of different combination of surgical techniques for RPD. Methods: The clinical data of 79 patients with RPD from August 2014 to October 2016 were analysed retrospectively. Knee joint was assessed according to measurements of the congruence angle (CA), patellar tilt angle (PTA) and lateral patellofemoral angle (LPFA). Knee function was evaluated by Kujala patellofemoral score, Lysholm knee score and Tegner score. Patients were followed up by out-patient examination and telephone till October 2018. Results: Preoperative clinical characteristics were similar across groups. It was statistically insignificant among three groups in CA, PTA, LPFA and redislocation rate. In term of knee functions, the MPFL reconstruction and LPR release group had the highest score (Lysholm score: 91.82 ± 4.64, Kujala score: 94.22 ± 4.26, Tegner score: 5.80 ± 1.00, respectively) and the LPR release and MPR plication had the lowest score (Lysholm score: 78.10 ± 6.90, Kujala score: 80.91 ± 4.30, Tegner score: 4.98 ± 1.22, respectively). Conclusion: Three combinations of surgical methods were similar in terms of postoperative joint congruence and redislocation rate, but MPFL reconstruction combined with LPR release is worthy to be promoted with the highest knee function scores. © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
1. Introduction The stability of the patellofemoral joint is mainly maintained by the peripheral bone structure with the medial and lateral ligaments and the strength supported by the quadriceps [1]. Patella dislocation can be easily caused by abnormal tensile stress and patellar movements resulting from loss of normal structural integrity of the patellofemoral joint. Patella dislocations account for 3.3% of all knee joint injuries [2]. The incidence of patellar dislocation has increased during the past several decades and young active persons accounted for the very great proportion [3,4]. Recurrent patellar dislocation (RPD), as the most common complication of acute patellar dislocation, usually causes symptoms (e.g. joint pain, instability, interlocking, sense of dislocation and swelling) affecting
* Corresponding author. E-mail address: [email protected] (Y.-P. Liu). 1 Co-first authors.
performance of daily activities and joint development in patients [5]. Conservative treatments to these RPD patients may not be adequate and surgical treatments are required [6,7]. In almost 90% of all cases, RPD commonly occurs to the lateral side resulting in ruptures of the medial patellofemoral ligament (MPFL) [8,9]. In addition, a recent biomechanical study conducted by Tsubosaka et al. showed that MPFL is the most important soft tissue in preventing patella dislocation and maintaining appropriate patellar tracking [10]. Therefore, when it comes to surgical methods for RPD, restoring the function of the MPFL is one of the most important factors. There are three basic surgical procedures including MPFL reconstruction, lateral patellar retinaculum (LPR) release and medial patellar retinaculum (MPR) plication for correcting patellar movement and instability in patients with RPD. However, the standard consensus has not been established. In this study, we compared combinations of above-mentioned surgical procedures on the effect of RPD using three-dimensional image techniques in order to find a most effective surgical method for RPD.
https://doi.org/10.1016/j.jos.2020.01.008 0949-2658/© 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
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X.-L. Wang et al. / Journal of Orthopaedic Science xxx (xxxx) xxx
2. Materials and methods 2.1. Patients This retrospective study was approved by the institutional review board of the author’s affiliated institutions. We retrospectively reviewed 79 patients diagnosed with RPD between August 2014 and October 2016 who underwent combination of surgical procedures. The patients were informed of possible complications of the surgical procedure and respective advantages and limitations of MPFL reconstruction, LPR release and MPR plication. The inclusion criteria were used in the selection of patients: (1) diffuse pain and patellar instability at the knee joint; (2) diagnosed with RPD or first patellar dislocation with joints instability lasting more than three months; (3) lost structures at the patella MPR with positive apprehension; (4) patellar track tests with increased motility (1.5 cm) when extending or flexing knee joints to 30 . The exclusion criteria were as follows: (1) generalized ligament laxity; (2) previous history of diseases or surgeries related to the knee joint; (3) femoral trochlear dysplasia which required osteotomy; (4) abnormal Q angles of the knee joints; (5) patellar dysplasia or patellar alta. In total, 79 patients were included in this study with informed consents. At the end, three combinations of surgical procedures were determined according to theoretical basis and patients’ will: (1) MPFL reconstruction and subsequent MPR plication group (n ¼ 15); (2) LPR release and subsequent MPR plication group (n ¼ 26); (3) LPR release and subsequent MPFL reconstruction group (n ¼ 38). It should be noticed that the combination strategy of every patient depended on the admission time: MPFL reconstruction plus MPR plication for August 2014 to April 2015, LPR release plus MPR plication for May 2015 to January 2016, LPR release plus MPFL reconstruction for February 2016 to October 2016.
reconstruction, autologous semitendinosus tendons were used for graft of which the average length was 120 ± 10 mm with a diameter of 4.0 mm. A longitudinal incision was made at the medial aspect of the tibial tubercle and the sartorius fascia was severed to expose the semitendinosus tendon which was then extracted for graft as abovementioned. As is shown in Fig. 1a, the patella was placed at the midpoint of the trochlear groove of femur and the reconstructed ligament was fixed at the midpoint and upper one-third of the medial patella with 5-mm pins. A bone tunnel was formed and enlarged with a 6-mm drill slightly behind the highest point of the medial tuberosity of femur and the midpoint of the adductor tubercle. A guide pin introduced the graft into the bone tunnel and the reconstructed ligament was subsequently folded onto the surface of the patella. A absorbable screw was used to fix the tendon in the femoral tunnel. The tension of tendon was adjusted under the arthroscope by pulling the braided suture on bilateral sides of the tendon. The joint congruence and motion track of the patella returned to normal. The scheme of LPR release is shown in Fig. 1b. The patients were placed in the supine position under combined spinal and epidural anesthesia. A curved incision was made at the lateral side of the patella. The tense fibrous structure at the lateral aspect of the patella was cut and the LPR was released to the lower and lateral borders of the patella. The vastus lateralis oblique muscle was partially cut simultaneously to avoid adhesion. As is shown in Fig. 1c, the medial joint capsule and retinaculum were completely cut open and partially removed during MPR plication, and then sutured together with overlapping edges in order to increase the medial tension against the lateral tension. The knots were tied below the superficial fascia and easily moved into fatty tissue if skin and superficial fascia were separated. Knots could become loose if fatty tissue was incorporated, and thus single MPR plication provided very limited effect on patients with recurrent patella dislocation.
2.2. Surgical procedure
2.3. Diagnostic techniques and postoperative assessment
All surgery was conducted by well-trained and experienced surgeons who performed at least 20 operations previously. In MPFL
Diagnosis of RPD is based on the measurement of the congruence angle (CA) [11], patellar tilt angle (PTA) [12], and lateral
Fig. 1. Schemes of three surgery options. (a) MPFL reconstruction; (b) LPR release; (c) MPR plication. MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
X.-L. Wang et al. / Journal of Orthopaedic Science xxx (xxxx) xxx
patellofemoral angle (LPFA) [13] using computed tomography (CT) three-dimensional reconstruction techniques which can observe the structure of the patellofemoral joint at different levels. CT scans have the ability to directly measure the CA, PTA, LPFA at the midpatellar level. Knee joint function was evaluated by Kujala patellofemoral score [14], Lysholm knee score [15] and Tegner score [16]. The combination of these three scoring systems can indicate the overall knee function. In addition, postoperative redislocation rate became as an independent factor to assess the reliability of surgical methods in this study. Postoperative follow-ups were performed through out-patient review or telephone interview every three months till October 2018. The follow-up contents included CT measurements and knee function evaluations. 2.4. Statistical analysis All statistical analyses were performed using SPSS version 19.0 (SPSS Inc., Chicago, IL, USA). Results are presented as mean ± SD. One-way analysis of variance (ANOVA) was used for quantitative data among three groups and Chi-squared test or Fisher’s exact test was used for qualitative data. P values that were less than 0.05 were considered statistically significant. It should be noticed that we used bootstrap (10000 bootstrap samples) which can avoid the small sample bias, to evaluate the 95% confidence interval of postoperative redislocation rate. 3. Results
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3.2. Preoperative CT measurement and knee function results It was statistically insignificant among these three groups in terms of preoperative CT measurement and knee function results including congruence angle (P ¼ 0.430), patellar tilt angle (P ¼ 0.331), lateral patellofemoral angle (P ¼ 0.819), Lysholm knee score (P ¼ 0.184), Kujala patellofemoral score (P ¼ 0.900), and Tegner score (P ¼ 0.673), which are shown in Table 2. Therefore, we could think that all preoperative information of these three group patients associated with this clinical study are similar allowing for comparison. 3.3. Postoperative assessment and follow-up All patients were followed up for 24 months postoperatively. Postoperative 6th-month CT measurements (Table 3) returned to a similar range in all groups and were statistically insignificant in congruence angle, patellar tilt angle and lateral patellar tilt angle (P ¼ 0.336, 0.268 and 0.341, respectively). In terms of postoperative 6th-month knee function evaluation (Table 3), there were statistically significant differences among these three groups (Lysholm score: P ¼ 0.000, Kujala score: P ¼ 0.000, Tegner score: P ¼ 0.002, respectively). The highest and lowest scores were all in the MPFL reconstruction and LPR release group and the LPR release and MPR plication group, respectively. Taken three groups together, 15.2% of the patients (12/79) sustained a redislocation and 84.8% (69/79) remained stable after 24 months. As shown in Table 4, there were no statistically significant differences in postoperative redislocation rate among these three groups (P ¼ 0.538).
3.1. Baseline characteristics 4. Discussion The three group patients’ data of baseline characteristics (i.e. age, gender, Body mass index (BMI), left or right side of dislocation, duration of dislocation and the number of dislocations) are summarized in Table 1. The number of patients in MPFL reconstruction and MPR plication group, LPR release and MPR plication group and MPFL reconstruction and LPR release group, was 15, 26 and 38, respectively. There were no statistically significant differences among the three groups in the baseline characteristics (P>0.05).
There are numerous predisposing factors for patellar dislocation or instability and single surgical option cannot balance the tension of peripatella joints and soft tissues. Numerous techniques have been developed to treat this problem, but the optimal surgical treatment remains controversial. MPFL reconstruction, LPR release and MPR plication are the primary surgical methods for mild patellar joint lesions. In allusion to serious recurrent patellar
Table 1 Baseline characteristics of the study population of three groups. Variables
MPFL reconstruction and MPR plication group (n ¼ 15)
LPR release and MPR plication group (n ¼ 26)
MPFL reconstruction and LPR release group (n ¼ 38)
P value
Age (years) Males/females BMI Left side/right side Duration of dislocation (months) Number of dislocations
23.0 ± 8.3 5/10 24.3 ± 4.4 6/9 17.3 ± 8.4 4.8 ± 2.9
24.9 ± 6.6 11/15 23.0 ± 5.9 10/16 16.9 ± 7.6 3.6 ± 2.2
26.2 ± 6.6 13/25 23.7 ± 4.7 16/22 19.4 ± 5.9 4.3 ± 2.1
0.312 0.769 0.738 0.957 0.315 0.255
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Table 2 Comparison of preoperative patella associated measurements and knee function among three groups.
Congruence angle Patellar tilt angle Lateral patellofemoral angle Lysholm knee score Kujala patellofemoral score Tegner score
MPFL reconstruction and MPR plication group (n ¼ 15)
LPR release and MPR plication group (n ¼ 26)
MPFL reconstruction and LPR release group (n ¼ 38)
P value
32.06 ± 6.40 12.59 ± 3.51 3.44 ± 3.86 56.22 ± 5.94 52.63 ± 5.83 3.16 ± 0.46
31.45 ± 5.52 13.81 ± 2.73 3.03 ± 6.07 54.99 ± 6.39 53.46 ± 5.64 3.24 ± 0.45
33.06 ± 3.72 13.54 ± 2.25 2.59 ± 3.56 57.67 ± 5.09 53.04 ± 5.61 3.27 ± 0.32
0.430 0.331 0.819 0.184 0.900 0.673
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
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X.-L. Wang et al. / Journal of Orthopaedic Science xxx (xxxx) xxx
Table 3 Comparison of postoperative 6th-month patella associated measurements and knee function among three groups.
Congruence angle Patellar tilt angle Lateral patellofemoral angle Lysholm knee score Kujala patellofemoral score Tegner score
MPFL reconstruction and MPR plication group (n ¼ 15)
LPR release and MPR plication group (n ¼ 26)
MPFL reconstruction and LPR release group (n ¼ 38)
P value
13.38 ± 7.40 8.03 ± 1.30 9.63 ± 4.54 86.76 ± 4.89 88.00 ± 5.99 4.74 ± 1.10
16.20 ± 6.60 7.29 ± 1.42 8.10 ± 2.65 78.10 ± 6.90 80.91 ± 4.30 4.98 ± 1.22
14.96 ± 4.60 7.48 ± 1.44 8.93 ± 3.11 91.82 ± 4.64 94.22 ± 4.26 5.80 ± 1.00
0.336 0.268 0.341 0.000 0.000 0.002
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
Table 4 Comparison of postoperative 24th-month redislocation rate among three groups.
MPFL reconstruction and MPR plication (n ¼ 15) LPR release and MPR plication (n ¼ 26) MPFL reconstruction and LPR release (n ¼ 38) P value
Number of redislocation
Bootstrap 95% C.l.
Postoperative redislocation rate
3 5 4
0e19.23% 3.85e34.62% 0e19.23%
20.0% 19.23% 10.53% 0.538
MPFL ¼ medial patellofemoral ligament; LPR ¼ lateral patellar retinaculum; MPR ¼ medial patellar retinaculum.
dislocation, several researchers have proposed combination surgical treatments based on aforementioned primary surgical methods [7,17,18]. Therefore, this study compared the efficiency of three combination surgical options for RPD. A study conducted by Du et al. [19] in 2016 showed that the MPFL reconstruction and LPR release had the best clinical outcomes among these three methods in terms of joint congruence and knee function. Similarly, this study also showed that the postoperative 6th-month knee function scores of patients in the MPFL reconstruction and LPR release group were highest indicating that MPFL reconstruction combined with LPR release might be a best choice to restore the knee function for patients with RPD. However, patellar position and rotation were all corrected to the same degree after each type of surgery in this study. As is shown in Fig. 2, postoperative CT measurements of a female patient who underwent LPR release and subsequent MPR plication causing the lowest knee function scores, showed that CA, PTA and LFPA have been significantly improved. It is also possible that we could get different results if we adopted more indicators such as the postoperative joint congruence and lateral patellar translation to assess the joint congruence more comprehensively.
The ligaments surrounding the patella are essential in preventing the patella dislocation. Therefore, a force balance needs to be achieved by surrounding soft-tissue structures especially at the medial and lateral part of the patella. LPR release and MPR plication, which can partially improve peripatella tesion and patella movements, are frequently used in RPD. Furthermore, some surgeons proposed MPR plication combined with LPR release for patients with RPD [20,21]. As mentioned earlier, MPFL is the main structure stabilizing the patellofemoral joint that can prevent patella dislocation [10,22]. It was reported that MPFL reconstruction as a wellestablished surgical option could improve the condition of patellar instability [23]. A prospective study conducted by Zhao et al. [24] for 5 years comparing MPFL reconstruction and MPR plication have shown that MPFL reconstruction can result in better static patellar position and functional outcome than MPR plication for RPD in adults. In this study, the lowest knee function scores in the group without MPFL reconstruction might also indicate that MPFL reconstruction plays an irreplaceable role in combination treatments. We planned to use 2 years to compare redislocation rates according to a study conducted by M.Petri et al., in 2012 [25].
Fig. 2. A 27-year-old female patient who underwent LPR release and MPR plication. (a) Preoperative CT of the knee. (b) Postoperative CT showed that congruence angle, patellar tilt angle and lateral patellofemoral angle have been significantly improved.
Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008
X.-L. Wang et al. / Journal of Orthopaedic Science xxx (xxxx) xxx
The postoperative 24th-month redislocation rates revealed no statistically significant differences among these three groups with different combination surgical options. We supposed that it required more time to compare redislocation rate more precisely just like the study conducted by Zhao et al. using 5 years [24]. In conclusion, there were no significant differences among three combination surgical options in terms of postoperative joint congruence. However, it is worthwhile to generalize the combination of MPFL reconstruction and LPR release because of its best clinical outcomes including highest knee function scores. Author contributions Xing-Liang Wang: Study conception, Collecting and analyzing the data, Writing and editing the manuscript. Xiao-Long Wang: Collecting and analyzing the data, Writing and editing the manuscript. Chao Peng: Collecting and analyzing the data, Writing and editing the manuscript. Jia-Ji Yang: Collecting and analyzing the data. Guo-Jun Hua: Collecting and analyzing the data. Yun-Peng Liu: Study conception, Collecting and analyzing the data, Writing and editing the manuscript. This research was supported by the Youth program of Wuxi Municipal Health Planning Commission (Q201772, China) and the medicine and public health technology program of Wuxi science and technology development (CSE31N1618, China). Ethical statement This study was approved by the institutional review board of the No.904 Hospital of Peoples Liberation Army. Declaration of Competing Interest On behalf of all authors, the corresponding author states that there is no conflict of interest. References [1] Biabanimoghadam M, Motealleh A, Cowan SM. Core muscle recruitment pattern during voluntary heel raises is different between patients with patellofemoral pain and healthy individuals. Knee 2016 Jun;23(3):382e6. [2] Majewski M, Susanne H, Klaus S. Epidemiology of athletic knee injuries: a 10year study. Knee 2006 Jun;13(3):184e8. [3] Gravesen KS, Kallemose T, Blønd L, Troelsen A, Barfod KW. High incidence of acute and recurrent patellar dislocations: a retrospective nationwide epidemiological study involving 24.154 primary dislocations. Knee Surg Sports Traumatol Arthrosc 2018 Apr;26(4):1204e9. [4] Hsiao M, Owens BD, Burks R, Sturdivant RX, Cameron KL. Incidence of acute traumatic patellar dislocation among active-duty United States military service members. Am J Sports Med 2010 Oct;38(10):1997e2004. [5] Colvin AC, West RV. Patellar instability. J Bone Jt Surg Am Vol 2008 Dec;90(12):2751e62. [6] Fithian DC, Paxton EW, Cohen AB. Indications in the treatment of patellar instability. J Knee Surg 2004 Jan;17(1):47e56.
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Please cite this article as: Wang X-L et al., Comparative study of three different combination surgical methods for recurrent patella dislocation, Journal of Orthopaedic Science, https://doi.org/10.1016/j.jos.2020.01.008