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The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee
THEKNE-02707; No of Pages 6 The Knee xxx (xxxx) xxx–xxx
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The Knee
The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee Ravi Gupta, Anil Kapoor ⁎, Naveen Mittal, Ashwani Soni, Sourabh Khatri, Gladson David Masih Department of Orthopaedics, Government Medical College Hospital, Chandigarh, India
a r t i c l e
i n f o
Article history: Received 13 February 2018 Received in revised form 15 August 2018 Accepted 7 September 2018 Available online xxxx Keywords: Meniscus tear ACL tear Knee stability
a b s t r a c t Background: The role of an intact meniscus in providing mechanical stability to the knee of anterior cruciate ligament (ACL) deficient and ACL reconstructed patients has not been well studied. Methods: This was a prospective cohort study. A total of 205 patients undergoing ACL reconstruction were enrolled, of which 61 had normal menisci, 49 had a tear in the posterior horn of the medial meniscus (PHMM) (tear b40% of width = 19; N 40% of width = 30), 35 had a tear in the lateral meniscus (b 40% of width = 15; N40% = 20), 13 had a tear in the body and/or anterior horn of the medial meniscus (b40% of width = 6; N40% = 7) and 47 patients had a tear in both menisci. Patients with a tear in both menisci were excluded. The anterior translation of the tibia (ATT) was calculated preoperatively and postoperatively at three months and six months using KT-1000. Partial meniscectomy was performed in all unstable meniscal tears. Results: The mean age at the time of surgery was 25.2 ± 5.1 years. Patients with a normal meniscus showed side to side difference in KT-1000 of 4.8 ± 2.5 mm whereas those with a b 40% tear and N 40% tear in PHMM had a difference of 5.36 ± 3.07 mm (P = 0.46) and 7.08 ± 2.78 mm (P = 0.0002), respectively. Patients with a lateral meniscus b 40% and N40% tear had a mean difference of 5.68 ± 2.96 mm (P = 0.22) and 5.95 ± 2.39 mm (P = 0.09), respectively. Patients with body and/or anterior horn of medial meniscus b40% and N 40% had a difference of 5.41 ± 1.11 mm (P = 0.59) and 5.78 ± 2.38 mm (P = 0.35), respectively. At three months and six months KT-1000 differences of 2.3 ± 1.2 mm and 2.1 ± 1.2 mm were seen in patients with normal meniscus; 2.26 ± 1.51 mm and 2.16 ± 0.9 mm with partial meniscectomy of the PHMM b40%; 2.65 ± 1.53 mm and 2.4 ± 1.35 mm with partial meniscectomy of the PHMM N 40%; 2.27 ± 1.19 mm and 2.07 ± 1.52 mm with partial meniscectomy of the lateral meniscus b 40%; and 2.27 ± 1.44 mm and 2.07 ± 1.14 mm with partial meniscectomy of the lateral meniscus N40%; 2.55 ± 1.56 mm and 1.91 ± 1.09 mm with partial meniscectomy in body and/or anterior horn of medial meniscus b 40% and 2.07 ± 1.81 and 2.14 ± 1.10 mm with partial meniscectomy in body and/or anterior horn of medial meniscus N40% (P N 0.05). Conclusion: PHMM acts as a secondary stabilizer of the knee joint in the absence of functional ACL. There is no effect of partial meniscectomy on mechanical stability of the knee in ACL reconstructed patients. Medial or lateral partial meniscectomy performed at the time of ACL reconstruction does not affect the stability of ACL reconstructed knee. However, the presence of a concomitant tear in PHMM is associated with increased instability in ACL deficient knee. © 2018 Elsevier B.V. All rights reserved.
⁎ Corresponding author. E-mail address: [email protected] (A. Kapoor).
https://doi.org/10.1016/j.knee.2018.09.007 0968-0160/© 2018 Elsevier B.V. All rights reserved.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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1. Introduction The anterior cruciate ligament (ACL) acts as a primary restraint to the anterior translation of the tibia (ATT) [1–4]. It also plays an important role in providing rotational stability to the knee [5–8]. In the absence of functional ACL, the menisci, condylar geometry, tibiofemoral loading and active muscle control provide stability to the knee [9,10]. The medial meniscus is firmly attached to the tibia, especially at the posterior horn. This firm attachment allows the medial meniscus to serve as a secondary knee stabilizer [10]. Previous studies have shown that tears of the posterior horn of the medial meniscus (PHMM) are associated with more ATT as compared to intact menisci in ACL deficient knees [4,9–14]. However, most of these are cadaveric studies [9–12,14]. There are only two studies in the available literature that have compared the instability associated with meniscectomy or meniscal repair after ACL reconstruction [15,16]. These studies showed that meniscal removal less than 46% of width does not cause instability of the knee. However, if meniscal removal was more than 46% it was associated with knee instability even in the presence of functional ACL. But no clear consensus could be established as these were cadaveric studies [15,16]. We conducted our study with the following objectives: first, the comparison of meniscal tear with intact menisci on knee stability in ACL deficient knees; and second, the comparison of partial meniscectomy with intact menisci on knee stability in ACL reconstructed knees. We hypothesized that meniscal tear in ACL deficient knees leads to greater instability and partial meniscectomy has no effect on knee stability in ACL reconstructed knees. 2. Material and methods This was a prospective cohort study conducted between January 2015 and October 2016 following approval from our institutional medical ethics committee. This study was registered with Clinical Trials Registry India (CTRI). Patients between 16 and 40 years of age who sustained ACL injury while playing sports without concomitant ligamentous or meniscal injury on the contralateral limb were included in the study. The diagnosis of ACL injury was confirmed by arthroscopy and exclusion of multiligamentous injury patients was made after magnetic resonance imaging (MRI). Patients with partial ACL tear, associated posterior cruciate ligament (PCL), lateral collateral ligament (LCL) or medial collateral ligament (MCL) injury and previously operated on the same or contralateral limb were excluded. All surgeries were performed by a single surgeon. ACL reconstruction was performed using either quadruple hamstring tendon graft with preserved insertion (n = 82) or bone patellar tendon bone (BPTB) (n = 76) graft depending on their computer-generated random number. ACL reconstruction was carried out using the trans-portal technique. In BPTB, cohort fixation was performed on both tibial and femoral sides using soft silk screws (Smith and nephew, USA) and in hamstring, cohort fixation was performed only on the femoral side using endobuttons (Smith and Nephew, USA) keeping tibial insertion preserved (free end sutured to its insertion using Ethibond sutures) [17]. ATT for both normal and injured knees was measured using KT-1000 preoperatively, and at three months and six months postoperatively. KT-1000 measurement was performed by a research fellow who was blinded to clinical findings, MRI, and arthroscopic findings. At the time of ACL reconstruction surgery, side (medial or lateral or both) and location of meniscal tear (anterior horn, body or posterior horn) were noted. Partial meniscectomy was carried out in patients who had an unstable meniscal tear and the amount of excised meniscus in terms of percentage of total meniscus was recorded (b40% and N 40% of maximum diameter of the involved area). At the time
Figure 1. Graduated probe showing tear involving three-quarters of the total width of the meniscus. Patients were followed up for a minimum of six months. No cases of meniscal repair were included in the present study. To remove the bias of multiple tears in different locations affecting the knee stability, we excluded patients with tears in both medial and lateral menisci.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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Table 1 Demographic comparison between groups.
Age BMI Type of graft
Intact meniscus (n = 61)
PHMM N40% (n = 30)
PHMM b40% (n = 19)
LM (n = 35)
MM (n = 13)
P
23.8 ± 4.83 26.02 ± 1.92 28 (STG) 33 (BPTB)
25.8 ± 5.75 25.36 ± 1.8 14 (STG) 16 (BPTB)
26.35 ± 6.98 25.25 ± 1.97 10 (STG) 9 (BPTB)
23.23 ± 4.28 25.87 ± 2.01 14 (STG) 21 (BPTB)
23.84 ± 4.27 25.01 ± 1.65 7 (STG) 6 (BPTB)
0.1 0.21 0.88
BMI, body mass index; BPTB, bone patellar tendon bone; LM, lateral Meniscus; MM, medial Meniscus; PHMM, posterior horn of medial meniscus; STG, semitendinosus gracilis.
of surgery, we measured the width of the tear and divided it by the width of the involved meniscus, thereby calculating its percentage. We made the measurement using a graduated probe (Figure 1). We tried to identify the minimal amount of meniscal tear that causes increase in ATT in the ACL deficient knee, and from the previously published literature it was observed that 46% is the cut-off value [15,16]. 3. Statistical analysis Summary statistics including means and standard deviations were calculated for normally distributed continuous variables. Correlation between the size of meniscal tear and ATT in ACL deficient knees was calculated using unpaired Student's t-test. Similarly, comparison of size of partial meniscectomy (b40% and N 40%) with intact menisci on knee stability in ACL reconstructed knee was calculated using unpaired Student's t-test. Age, body mass index (BMI), and type of graft were compared using the analysis of variance (ANOVA) test. A P-value of b 0.05 was considered as significant difference and Pb0.01 was considered as highly significant difference. Power study was calculated using post hoc analysis. The power of the study was calculated on the basis of preoperative mean KT-1000 difference between intact meniscus and PHMM (N40%) tear. The power of the study as calculated using a web-based power calculator (stat.ubc.ca) was 96.2%. 4. Results A total of 158 patients between the ages of 16 and 40 years satisfying the inclusion criteria were evaluated. The mean age of patients at the time of surgery was 25.2 ± 5.1 years. Out of 158 patients, 155 patients were male and three were female. Ninetyseven patients had injury to the non-dominant limb and 61 patients had injury to the dominant limb. The demographic profile of patients is highlighted in Table 1. All groups were matched for their age distribution, BMI and type of graft used. The patients were divided into groups based on the absence or presence of tear, side of tear and percentage of meniscus removed. The patients having unstable meniscal tear were further subdivided into two groups with partial meniscectomy of less than 40% and greater than 40%. A total of seven groups were formed, as shown in Figure 2. The preoperative mean KT-1000 side-to-side difference in each of the groups was computed. The mean in each group was compared with the mean for patients with intact menisci using unpaired Student's t-test and the P-value was calculated. The mean and the respective P-values are shown in Table 2. Analyzing statistically, the difference was highly significant for patients with tear of PHMM greater than 40% and non-significant for tear of PHMM less than 40% in comparison with the intact menisci group. In patients with lateral meniscus tear, tears of body and/or anterior horn of medial meniscus, the difference was non-significant. The scatter graph plots for patients with PHMM tear, lateral meniscus tear, body and/or anterior horn medial meniscus tear are shown in Figure 3. The scatter graphs confirmed that the patients with PHMM had the maximum instability followed by patients with lateral meniscus tear and the least instability was associated with body and/or anterior horn medial meniscus tears.
Figure 2. Distribution of patients.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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Table 2 Effect of meniscal tear on knee stability in absence of functional anterior cruciate ligament. Group
Mean ± SD (preoperative; in mm)
P (meniscal tear group vs intact menisci group)
Intact menisci PHMM b40% PHMM N40% LM b40% LM N40% MM body and/or anterior horn b40% MM body and/or anterior horn N40%
4.84 ± 2.50 5.36 ± 3.07 7.08 ± 2.78 5.68 ± 2.96 5.95 ± 2.39 5.41 ± 1.11 5.78 ± 2.38
0.46 0.00002 (0.027 post hoc test) 0.22 0.09 0.59 0.35
LM, lateral Meniscus; MM, medial meniscus; PHMM, posterior horn of medial meniscus; SD, standard deviation.
PHMM LM MM
Figure 3. Scatter graph showing the order of instability due to meniscal tear preoperatively. ATT, anterior translation of the tibia; LM, lateral meniscus; MM, medial meniscus; PHMM, posterior horn of medial meniscus.
In this study, we also observed the effect of partial meniscectomy on stability of the knee in the presence of functional ACL by recording KT-1000 difference postoperatively at three months and six months. The mean KT-1000 difference in each group was compared with the group with intact menisci (Table 3). Analyzing statistically, it was observed that the difference was not significant for any of the groups. All of the groups, irrespective of the percentage of meniscus removed and the side of meniscectomy, had no statistically significant difference in instability in comparison with patients with intact menisci at three months and six months postoperatively. 5. Discussion In our study, we observed that partial meniscectomy had no detectable effect on knee stability in the presence of functional ACL using KT-1000 side-to-side difference; however, in the ACL deficient knee meniscal tear of more than 40% in PHMM was associated with significant instability. Menisci play a vital role in the knee. Increased incidence of medial meniscus tear with delay in surgery has been well reported [18–20] and the association of these meniscal tears with occurrence of early osteoarthritis has also been extensively researched [21–23]. However, the role of the intact meniscus in knee stability in the ACL deficient knee and the effect of partial meniscectomy on the stability of the ACL reconstructed knee have not been very well documented. Tears in the medial meniscus are more common as compared to tears in the lateral meniscus in chronic knee injuries, with more than 75% of these tears located in the PHMM [9,24]. The PHMM being firmly attached to the tibia serves as a mechanical block or wedge against anterior tibial translation. This function becomes even more important in ACL deficient knees [11]. Levy et al., in their
Table 3 Effect of partial meniscectomy on knee stability in the presence of functional anterior cruciate ligament. Group
Mean ± SD At 3 months (in mm)
Intact menisci PHMM b40% PHMM N40% LM b40% LM N40% MM body and/or Anterior horn b40% MM body and/or Anterior horn N40%
2.31 ± 1.21 2.26 ± 1.51 2.65 ± 1.53 2.27 ± 1.19 2.27 ± 1.44 2.55 ± 1.56 2.07 ± 1.81
P
0.88 0.25 0.90 0.90 0.65 0.64
Mean ± SD At 6 months (in mm) 2.08 ± 1.23 2.16 ± 0.9 2.4 ± 1.35 2.07 ± 1.52 2.07 ± 1.14 1.91 ± 1.09 2.14 ± 1.10
P
0.79 0.26 0.98 0.97 0.75 0.90
LM, lateral meniscus; MM, medial meniscus; PHMM, posterior horn of medial meniscus; SD, standard deviation.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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cadaveric study, observed that excision of the medial meniscus and resection of the ACL allowed a significantly greater ATT than by isolated resection of ACL [11]. Ahn et al., in their study of 10 cadaveric knees, observed that longitudinal tears of PHMM in ACLdeficient knees resulted in a significant increase in anterior–posterior tibial translation [9]. But all of these are cadaveric studies. We were able to prove in our patients with ACL deficiency that N40% tears in PHMM resulted in increased instability as compared to patients with intact menisci. The instability associated with lateral meniscus tears, body and/or anterior horn of medial meniscus tears in ACL deficient knees has not been documented so far. Although these tears did not result in significant instability as compared to knees with intact menisci, we are able to comment on the order of instability. Thus, the maximum instability resulted from PHMM tears followed by lateral menisci tears, and the least with body and/or anterior horn medial meniscus tears. The effect of meniscectomy on knee stability in the presence of functional ACL is not well studied. Hede et al. [25] observed that there was no increase in knee laxity after partial medial or lateral meniscectomy. However, Arno et al. [15] and Deledda et al. [16] observed that N46% removal of PHMM was associated with an increase in instability of the knee. Thus, a clear consensus is lacking. Our study highlights that partial meniscectomy, irrespective of the percentage of meniscus and side of meniscus removed, did not affect the stability postoperatively in ACL reconstructed knees in comparison with patients with intact menisci in ACL reconstructed knees. Our study has limitations. We did not measure the ATT under anesthesia preoperatively and immediately postoperatively. The value of 40% of meniscal deficiency should be taken with caution and studies with larger numbers are required to determine a precise cut-off value. We were not able to predict whether highly unstable knees (perhaps due to the concomitant capsular tears) lead to large meniscal tears or whether meniscal tears are the cause of the increased instability. In this study, we used a graduated probe to measure the width of the tear but there is scope for a better method of measurement which can measure the volume of meniscus tear. 6. Conclusion The PHMM acted as a secondary stabilizer to the knee joint in the absence of functional ACL. There was no effect of partial meniscectomy on the mechanical stability of the knee in ACL reconstructed patients. However, it is important to preserve the meniscus whenever possible. Although it does not contribute to knee stability in the presence of functional ACL, it has many other functions in the knee such as acting as a shock absorber and being involved in pressure distribution, joint lubrication and nourishment of the joint. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.knee.2018.09.007. References [1] Fukubayashi T, Torzilli P, Sherman M, Warren R. An in vitro biomechanical evaluation of anterior–posterior motion of the knee. Tibial displacement, rotation, and torque. J Bone Joint Surg Am 1982;64:258–64. [2] Butler D, Noyes F, Grood E. Ligamentous restraints to anterior–posterior drawer in the human knee. J Bone Joint Surg Am 1980;62:259–70. [3] Monaco E, Maestri B, Labianca L, Speranza A, Kelly MJ, Ferretti A. Navigated knee kinematics after tear of the ACL and its secondary restraints: preliminary results. Orthopedics 2010;33:87–93. [4] Yammine K. Effect of partial medial meniscectomy on anterior tibial translation in stable knees: a prospective controlled study on 32 patients. BMC Sports Sci Med Rehabil 2013;5:17. [5] Engebretsen L, Wijdicks CA, Anderson CJ, Westerhaus B, Laprade RF. Evaluation of a simulated pivot shift test: a biomechanical study. Knee Surg Sports Traumatol Arthrosc 2012;20:698–702. [6] Noyes FR, Jetter AW, Grood ES, Harms SP, Gardner EJ, Levy MS. Anterior cruciate ligament function in providing rotational stability assessed by medial and lateral tibiofemoral compartment translations and subluxations. Am J Sports Med 2015;43:683–92. [7] Tavlo M, Eljaja S, Jensen J, Siersma VD, Krogsgaard MR. The role of the anterolateral ligament in ACL insufficient and reconstructed knees on rotatory stability: a biomechanical study on human cadavers. Scand J Med Sci Sports 2016;26:960–6. [8] Noyes FR, Huser LE, Levy MS. Rotational knee instability in ACL-deficient knees: role of the anterolateral ligament and iliotibial band as defined by tibiofemoral compartment translations and rotations. J Bone Joint Surg Am 2017;99:305–14. [9] Ahn JH, Bae TS, Kang K-S, Kang SY, Lee SH. Longitudinal tear of the medial meniscus posterior horn in the anterior cruciate ligament-deficient knee significantly influences anterior stability. Am J Sports Med 2011;39:2187–93. [10] Allen CR, Wong EK, Livesay GA, Sakane M, Fu FH, Woo SLY. Importance of the medial meniscus in the anterior cruciate ligament-deficient knee. J Orthop Res 2000;18:109–15. [11] Levy IM, Torzilli P, Warren R. The effect of medial meniscectomy on anterior–posterior motion of the knee. J Bone Joint Surg Am 1982;64:883–8. [12] Spang JT, Dang AB, Mazzocca A, Rincon L, Obopilwe E, Beynnon B, et al. The effect of medial meniscectomy and meniscal allograft transplantation on knee and anterior cruciate ligament biomechanics. Arthroscopy 2010;26:192–201. [13] Fithian DC, Kelly MA, Mow VC. Material properties and structure–function relationships in the menisci. Clin Orthop Relat Res 1990;252:19–31. [14] Shoemaker S, Markolf K. The role of the meniscus in the anterior–posterior stability of the loaded anterior cruciate-deficient knee. Effects of partial versus total excision. J Bone Joint Surg Am 1986;68:71–9. [15] Arno S, Hadley S, Campbell KA, Bell CP, Hall M, Beltran LS, et al. The effect of arthroscopic partial medial meniscectomy on tibiofemoral stability. Am J Sports Med 2013;41:73–9. [16] Deledda D, Rosso F, Cottino U, Bonasia DE, Rossi R. Results of meniscectomy and meniscal repair in anterior cruciate ligament reconstruction. Joints 2015;3:151–7. [17] Gupta R, Bahadur R, Malhotra A, Masih GD, Gupta P. Anterior cruciate ligament reconstruction using hamstring tendon autograft with preserved insertions. Arthroscopy Techniques 2016;5(2):e269–74. [18] Gupta R, Masih GD, Chander G, Bachhal V. Delay in surgery predisposes to meniscal and chondral injuries in anterior cruciate ligament deficient knees. Indian J Orthop 2016;50:492–8.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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[19] Nguyen JT, Wasserstein D, Reinke EK, Spindler KP, Mehta N, Doyle JB, et al. Does the chronicity of anterior cruciate ligament ruptures influence patient-reported outcomes before surgery? Am J Sports Med 2017;45:541–9. [20] Zoller SD, Toy KA, Wang P, Ebramzadeh E, Bowen RE. Temporal relation of meniscal tear incidence, severity, and outcome scores in adolescents undergoing anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2017;25:215–21. [21] Johnson VL, Guermazi A, Roemer FW, Hunter DJ. Loss of anterior cruciate ligament integrity and the risk of secondary meniscal injury and bone marrow lesions: data from the osteoarthritis initiative. Osteoarthr Cartil 2017;25:S364. [22] Persson F, Turkiewicz A, Bergkvist D, Neuman P, Englund M. The risk of symptomatic knee osteoarthritis after arthroscopic meniscus repair vs partial meniscectomy vs the general population. Osteoarthr Cartil 2018;26:195–201. [23] Smith MV, Nepple JJ, Wright RW, Matava MJ, Brophy RH. Knee osteoarthritis is associated with previous meniscus and anterior cruciate ligament surgery among elite college American football athletes. Sports Health 2017;9:247–51. [24] Bellabarba C, Bush-Joseph C, Bach JB. Patterns of meniscal injury in the anterior cruciate-deficient knee: a review of the literature. Am J Orthop 1997;26:18–23. [25] Hede A, Larsen E, Sandberg H. Partial versus total meniscectomy. A prospective, randomised study with long-term follow-up. Bone Joint J 1992;74:118–21.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
Contents lists available at ScienceDirect
The Knee
The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee Ravi Gupta, Anil Kapoor ⁎, Naveen Mittal, Ashwani Soni, Sourabh Khatri, Gladson David Masih Department of Orthopaedics, Government Medical College Hospital, Chandigarh, India
a r t i c l e
i n f o
Article history: Received 13 February 2018 Received in revised form 15 August 2018 Accepted 7 September 2018 Available online xxxx Keywords: Meniscus tear ACL tear Knee stability
a b s t r a c t Background: The role of an intact meniscus in providing mechanical stability to the knee of anterior cruciate ligament (ACL) deficient and ACL reconstructed patients has not been well studied. Methods: This was a prospective cohort study. A total of 205 patients undergoing ACL reconstruction were enrolled, of which 61 had normal menisci, 49 had a tear in the posterior horn of the medial meniscus (PHMM) (tear b40% of width = 19; N 40% of width = 30), 35 had a tear in the lateral meniscus (b 40% of width = 15; N40% = 20), 13 had a tear in the body and/or anterior horn of the medial meniscus (b40% of width = 6; N40% = 7) and 47 patients had a tear in both menisci. Patients with a tear in both menisci were excluded. The anterior translation of the tibia (ATT) was calculated preoperatively and postoperatively at three months and six months using KT-1000. Partial meniscectomy was performed in all unstable meniscal tears. Results: The mean age at the time of surgery was 25.2 ± 5.1 years. Patients with a normal meniscus showed side to side difference in KT-1000 of 4.8 ± 2.5 mm whereas those with a b 40% tear and N 40% tear in PHMM had a difference of 5.36 ± 3.07 mm (P = 0.46) and 7.08 ± 2.78 mm (P = 0.0002), respectively. Patients with a lateral meniscus b 40% and N40% tear had a mean difference of 5.68 ± 2.96 mm (P = 0.22) and 5.95 ± 2.39 mm (P = 0.09), respectively. Patients with body and/or anterior horn of medial meniscus b40% and N 40% had a difference of 5.41 ± 1.11 mm (P = 0.59) and 5.78 ± 2.38 mm (P = 0.35), respectively. At three months and six months KT-1000 differences of 2.3 ± 1.2 mm and 2.1 ± 1.2 mm were seen in patients with normal meniscus; 2.26 ± 1.51 mm and 2.16 ± 0.9 mm with partial meniscectomy of the PHMM b40%; 2.65 ± 1.53 mm and 2.4 ± 1.35 mm with partial meniscectomy of the PHMM N 40%; 2.27 ± 1.19 mm and 2.07 ± 1.52 mm with partial meniscectomy of the lateral meniscus b 40%; and 2.27 ± 1.44 mm and 2.07 ± 1.14 mm with partial meniscectomy of the lateral meniscus N40%; 2.55 ± 1.56 mm and 1.91 ± 1.09 mm with partial meniscectomy in body and/or anterior horn of medial meniscus b 40% and 2.07 ± 1.81 and 2.14 ± 1.10 mm with partial meniscectomy in body and/or anterior horn of medial meniscus N40% (P N 0.05). Conclusion: PHMM acts as a secondary stabilizer of the knee joint in the absence of functional ACL. There is no effect of partial meniscectomy on mechanical stability of the knee in ACL reconstructed patients. Medial or lateral partial meniscectomy performed at the time of ACL reconstruction does not affect the stability of ACL reconstructed knee. However, the presence of a concomitant tear in PHMM is associated with increased instability in ACL deficient knee. © 2018 Elsevier B.V. All rights reserved.
⁎ Corresponding author. E-mail address: [email protected] (A. Kapoor).
https://doi.org/10.1016/j.knee.2018.09.007 0968-0160/© 2018 Elsevier B.V. All rights reserved.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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1. Introduction The anterior cruciate ligament (ACL) acts as a primary restraint to the anterior translation of the tibia (ATT) [1–4]. It also plays an important role in providing rotational stability to the knee [5–8]. In the absence of functional ACL, the menisci, condylar geometry, tibiofemoral loading and active muscle control provide stability to the knee [9,10]. The medial meniscus is firmly attached to the tibia, especially at the posterior horn. This firm attachment allows the medial meniscus to serve as a secondary knee stabilizer [10]. Previous studies have shown that tears of the posterior horn of the medial meniscus (PHMM) are associated with more ATT as compared to intact menisci in ACL deficient knees [4,9–14]. However, most of these are cadaveric studies [9–12,14]. There are only two studies in the available literature that have compared the instability associated with meniscectomy or meniscal repair after ACL reconstruction [15,16]. These studies showed that meniscal removal less than 46% of width does not cause instability of the knee. However, if meniscal removal was more than 46% it was associated with knee instability even in the presence of functional ACL. But no clear consensus could be established as these were cadaveric studies [15,16]. We conducted our study with the following objectives: first, the comparison of meniscal tear with intact menisci on knee stability in ACL deficient knees; and second, the comparison of partial meniscectomy with intact menisci on knee stability in ACL reconstructed knees. We hypothesized that meniscal tear in ACL deficient knees leads to greater instability and partial meniscectomy has no effect on knee stability in ACL reconstructed knees. 2. Material and methods This was a prospective cohort study conducted between January 2015 and October 2016 following approval from our institutional medical ethics committee. This study was registered with Clinical Trials Registry India (CTRI). Patients between 16 and 40 years of age who sustained ACL injury while playing sports without concomitant ligamentous or meniscal injury on the contralateral limb were included in the study. The diagnosis of ACL injury was confirmed by arthroscopy and exclusion of multiligamentous injury patients was made after magnetic resonance imaging (MRI). Patients with partial ACL tear, associated posterior cruciate ligament (PCL), lateral collateral ligament (LCL) or medial collateral ligament (MCL) injury and previously operated on the same or contralateral limb were excluded. All surgeries were performed by a single surgeon. ACL reconstruction was performed using either quadruple hamstring tendon graft with preserved insertion (n = 82) or bone patellar tendon bone (BPTB) (n = 76) graft depending on their computer-generated random number. ACL reconstruction was carried out using the trans-portal technique. In BPTB, cohort fixation was performed on both tibial and femoral sides using soft silk screws (Smith and nephew, USA) and in hamstring, cohort fixation was performed only on the femoral side using endobuttons (Smith and Nephew, USA) keeping tibial insertion preserved (free end sutured to its insertion using Ethibond sutures) [17]. ATT for both normal and injured knees was measured using KT-1000 preoperatively, and at three months and six months postoperatively. KT-1000 measurement was performed by a research fellow who was blinded to clinical findings, MRI, and arthroscopic findings. At the time of ACL reconstruction surgery, side (medial or lateral or both) and location of meniscal tear (anterior horn, body or posterior horn) were noted. Partial meniscectomy was carried out in patients who had an unstable meniscal tear and the amount of excised meniscus in terms of percentage of total meniscus was recorded (b40% and N 40% of maximum diameter of the involved area). At the time
Figure 1. Graduated probe showing tear involving three-quarters of the total width of the meniscus. Patients were followed up for a minimum of six months. No cases of meniscal repair were included in the present study. To remove the bias of multiple tears in different locations affecting the knee stability, we excluded patients with tears in both medial and lateral menisci.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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Table 1 Demographic comparison between groups.
Age BMI Type of graft
Intact meniscus (n = 61)
PHMM N40% (n = 30)
PHMM b40% (n = 19)
LM (n = 35)
MM (n = 13)
P
23.8 ± 4.83 26.02 ± 1.92 28 (STG) 33 (BPTB)
25.8 ± 5.75 25.36 ± 1.8 14 (STG) 16 (BPTB)
26.35 ± 6.98 25.25 ± 1.97 10 (STG) 9 (BPTB)
23.23 ± 4.28 25.87 ± 2.01 14 (STG) 21 (BPTB)
23.84 ± 4.27 25.01 ± 1.65 7 (STG) 6 (BPTB)
0.1 0.21 0.88
BMI, body mass index; BPTB, bone patellar tendon bone; LM, lateral Meniscus; MM, medial Meniscus; PHMM, posterior horn of medial meniscus; STG, semitendinosus gracilis.
of surgery, we measured the width of the tear and divided it by the width of the involved meniscus, thereby calculating its percentage. We made the measurement using a graduated probe (Figure 1). We tried to identify the minimal amount of meniscal tear that causes increase in ATT in the ACL deficient knee, and from the previously published literature it was observed that 46% is the cut-off value [15,16]. 3. Statistical analysis Summary statistics including means and standard deviations were calculated for normally distributed continuous variables. Correlation between the size of meniscal tear and ATT in ACL deficient knees was calculated using unpaired Student's t-test. Similarly, comparison of size of partial meniscectomy (b40% and N 40%) with intact menisci on knee stability in ACL reconstructed knee was calculated using unpaired Student's t-test. Age, body mass index (BMI), and type of graft were compared using the analysis of variance (ANOVA) test. A P-value of b 0.05 was considered as significant difference and Pb0.01 was considered as highly significant difference. Power study was calculated using post hoc analysis. The power of the study was calculated on the basis of preoperative mean KT-1000 difference between intact meniscus and PHMM (N40%) tear. The power of the study as calculated using a web-based power calculator (stat.ubc.ca) was 96.2%. 4. Results A total of 158 patients between the ages of 16 and 40 years satisfying the inclusion criteria were evaluated. The mean age of patients at the time of surgery was 25.2 ± 5.1 years. Out of 158 patients, 155 patients were male and three were female. Ninetyseven patients had injury to the non-dominant limb and 61 patients had injury to the dominant limb. The demographic profile of patients is highlighted in Table 1. All groups were matched for their age distribution, BMI and type of graft used. The patients were divided into groups based on the absence or presence of tear, side of tear and percentage of meniscus removed. The patients having unstable meniscal tear were further subdivided into two groups with partial meniscectomy of less than 40% and greater than 40%. A total of seven groups were formed, as shown in Figure 2. The preoperative mean KT-1000 side-to-side difference in each of the groups was computed. The mean in each group was compared with the mean for patients with intact menisci using unpaired Student's t-test and the P-value was calculated. The mean and the respective P-values are shown in Table 2. Analyzing statistically, the difference was highly significant for patients with tear of PHMM greater than 40% and non-significant for tear of PHMM less than 40% in comparison with the intact menisci group. In patients with lateral meniscus tear, tears of body and/or anterior horn of medial meniscus, the difference was non-significant. The scatter graph plots for patients with PHMM tear, lateral meniscus tear, body and/or anterior horn medial meniscus tear are shown in Figure 3. The scatter graphs confirmed that the patients with PHMM had the maximum instability followed by patients with lateral meniscus tear and the least instability was associated with body and/or anterior horn medial meniscus tears.
Figure 2. Distribution of patients.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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Table 2 Effect of meniscal tear on knee stability in absence of functional anterior cruciate ligament. Group
Mean ± SD (preoperative; in mm)
P (meniscal tear group vs intact menisci group)
Intact menisci PHMM b40% PHMM N40% LM b40% LM N40% MM body and/or anterior horn b40% MM body and/or anterior horn N40%
4.84 ± 2.50 5.36 ± 3.07 7.08 ± 2.78 5.68 ± 2.96 5.95 ± 2.39 5.41 ± 1.11 5.78 ± 2.38
0.46 0.00002 (0.027 post hoc test) 0.22 0.09 0.59 0.35
LM, lateral Meniscus; MM, medial meniscus; PHMM, posterior horn of medial meniscus; SD, standard deviation.
PHMM LM MM
Figure 3. Scatter graph showing the order of instability due to meniscal tear preoperatively. ATT, anterior translation of the tibia; LM, lateral meniscus; MM, medial meniscus; PHMM, posterior horn of medial meniscus.
In this study, we also observed the effect of partial meniscectomy on stability of the knee in the presence of functional ACL by recording KT-1000 difference postoperatively at three months and six months. The mean KT-1000 difference in each group was compared with the group with intact menisci (Table 3). Analyzing statistically, it was observed that the difference was not significant for any of the groups. All of the groups, irrespective of the percentage of meniscus removed and the side of meniscectomy, had no statistically significant difference in instability in comparison with patients with intact menisci at three months and six months postoperatively. 5. Discussion In our study, we observed that partial meniscectomy had no detectable effect on knee stability in the presence of functional ACL using KT-1000 side-to-side difference; however, in the ACL deficient knee meniscal tear of more than 40% in PHMM was associated with significant instability. Menisci play a vital role in the knee. Increased incidence of medial meniscus tear with delay in surgery has been well reported [18–20] and the association of these meniscal tears with occurrence of early osteoarthritis has also been extensively researched [21–23]. However, the role of the intact meniscus in knee stability in the ACL deficient knee and the effect of partial meniscectomy on the stability of the ACL reconstructed knee have not been very well documented. Tears in the medial meniscus are more common as compared to tears in the lateral meniscus in chronic knee injuries, with more than 75% of these tears located in the PHMM [9,24]. The PHMM being firmly attached to the tibia serves as a mechanical block or wedge against anterior tibial translation. This function becomes even more important in ACL deficient knees [11]. Levy et al., in their
Table 3 Effect of partial meniscectomy on knee stability in the presence of functional anterior cruciate ligament. Group
Mean ± SD At 3 months (in mm)
Intact menisci PHMM b40% PHMM N40% LM b40% LM N40% MM body and/or Anterior horn b40% MM body and/or Anterior horn N40%
2.31 ± 1.21 2.26 ± 1.51 2.65 ± 1.53 2.27 ± 1.19 2.27 ± 1.44 2.55 ± 1.56 2.07 ± 1.81
P
0.88 0.25 0.90 0.90 0.65 0.64
Mean ± SD At 6 months (in mm) 2.08 ± 1.23 2.16 ± 0.9 2.4 ± 1.35 2.07 ± 1.52 2.07 ± 1.14 1.91 ± 1.09 2.14 ± 1.10
P
0.79 0.26 0.98 0.97 0.75 0.90
LM, lateral meniscus; MM, medial meniscus; PHMM, posterior horn of medial meniscus; SD, standard deviation.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007
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cadaveric study, observed that excision of the medial meniscus and resection of the ACL allowed a significantly greater ATT than by isolated resection of ACL [11]. Ahn et al., in their study of 10 cadaveric knees, observed that longitudinal tears of PHMM in ACLdeficient knees resulted in a significant increase in anterior–posterior tibial translation [9]. But all of these are cadaveric studies. We were able to prove in our patients with ACL deficiency that N40% tears in PHMM resulted in increased instability as compared to patients with intact menisci. The instability associated with lateral meniscus tears, body and/or anterior horn of medial meniscus tears in ACL deficient knees has not been documented so far. Although these tears did not result in significant instability as compared to knees with intact menisci, we are able to comment on the order of instability. Thus, the maximum instability resulted from PHMM tears followed by lateral menisci tears, and the least with body and/or anterior horn medial meniscus tears. The effect of meniscectomy on knee stability in the presence of functional ACL is not well studied. Hede et al. [25] observed that there was no increase in knee laxity after partial medial or lateral meniscectomy. However, Arno et al. [15] and Deledda et al. [16] observed that N46% removal of PHMM was associated with an increase in instability of the knee. Thus, a clear consensus is lacking. Our study highlights that partial meniscectomy, irrespective of the percentage of meniscus and side of meniscus removed, did not affect the stability postoperatively in ACL reconstructed knees in comparison with patients with intact menisci in ACL reconstructed knees. Our study has limitations. We did not measure the ATT under anesthesia preoperatively and immediately postoperatively. The value of 40% of meniscal deficiency should be taken with caution and studies with larger numbers are required to determine a precise cut-off value. We were not able to predict whether highly unstable knees (perhaps due to the concomitant capsular tears) lead to large meniscal tears or whether meniscal tears are the cause of the increased instability. In this study, we used a graduated probe to measure the width of the tear but there is scope for a better method of measurement which can measure the volume of meniscus tear. 6. Conclusion The PHMM acted as a secondary stabilizer to the knee joint in the absence of functional ACL. There was no effect of partial meniscectomy on the mechanical stability of the knee in ACL reconstructed patients. However, it is important to preserve the meniscus whenever possible. Although it does not contribute to knee stability in the presence of functional ACL, it has many other functions in the knee such as acting as a shock absorber and being involved in pressure distribution, joint lubrication and nourishment of the joint. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.knee.2018.09.007. References [1] Fukubayashi T, Torzilli P, Sherman M, Warren R. An in vitro biomechanical evaluation of anterior–posterior motion of the knee. Tibial displacement, rotation, and torque. J Bone Joint Surg Am 1982;64:258–64. [2] Butler D, Noyes F, Grood E. Ligamentous restraints to anterior–posterior drawer in the human knee. J Bone Joint Surg Am 1980;62:259–70. [3] Monaco E, Maestri B, Labianca L, Speranza A, Kelly MJ, Ferretti A. Navigated knee kinematics after tear of the ACL and its secondary restraints: preliminary results. Orthopedics 2010;33:87–93. [4] Yammine K. Effect of partial medial meniscectomy on anterior tibial translation in stable knees: a prospective controlled study on 32 patients. BMC Sports Sci Med Rehabil 2013;5:17. [5] Engebretsen L, Wijdicks CA, Anderson CJ, Westerhaus B, Laprade RF. Evaluation of a simulated pivot shift test: a biomechanical study. Knee Surg Sports Traumatol Arthrosc 2012;20:698–702. [6] Noyes FR, Jetter AW, Grood ES, Harms SP, Gardner EJ, Levy MS. Anterior cruciate ligament function in providing rotational stability assessed by medial and lateral tibiofemoral compartment translations and subluxations. Am J Sports Med 2015;43:683–92. [7] Tavlo M, Eljaja S, Jensen J, Siersma VD, Krogsgaard MR. The role of the anterolateral ligament in ACL insufficient and reconstructed knees on rotatory stability: a biomechanical study on human cadavers. Scand J Med Sci Sports 2016;26:960–6. [8] Noyes FR, Huser LE, Levy MS. Rotational knee instability in ACL-deficient knees: role of the anterolateral ligament and iliotibial band as defined by tibiofemoral compartment translations and rotations. J Bone Joint Surg Am 2017;99:305–14. [9] Ahn JH, Bae TS, Kang K-S, Kang SY, Lee SH. Longitudinal tear of the medial meniscus posterior horn in the anterior cruciate ligament-deficient knee significantly influences anterior stability. Am J Sports Med 2011;39:2187–93. [10] Allen CR, Wong EK, Livesay GA, Sakane M, Fu FH, Woo SLY. Importance of the medial meniscus in the anterior cruciate ligament-deficient knee. J Orthop Res 2000;18:109–15. [11] Levy IM, Torzilli P, Warren R. The effect of medial meniscectomy on anterior–posterior motion of the knee. J Bone Joint Surg Am 1982;64:883–8. [12] Spang JT, Dang AB, Mazzocca A, Rincon L, Obopilwe E, Beynnon B, et al. The effect of medial meniscectomy and meniscal allograft transplantation on knee and anterior cruciate ligament biomechanics. Arthroscopy 2010;26:192–201. [13] Fithian DC, Kelly MA, Mow VC. Material properties and structure–function relationships in the menisci. Clin Orthop Relat Res 1990;252:19–31. [14] Shoemaker S, Markolf K. The role of the meniscus in the anterior–posterior stability of the loaded anterior cruciate-deficient knee. Effects of partial versus total excision. J Bone Joint Surg Am 1986;68:71–9. [15] Arno S, Hadley S, Campbell KA, Bell CP, Hall M, Beltran LS, et al. The effect of arthroscopic partial medial meniscectomy on tibiofemoral stability. Am J Sports Med 2013;41:73–9. [16] Deledda D, Rosso F, Cottino U, Bonasia DE, Rossi R. Results of meniscectomy and meniscal repair in anterior cruciate ligament reconstruction. Joints 2015;3:151–7. [17] Gupta R, Bahadur R, Malhotra A, Masih GD, Gupta P. Anterior cruciate ligament reconstruction using hamstring tendon autograft with preserved insertions. Arthroscopy Techniques 2016;5(2):e269–74. [18] Gupta R, Masih GD, Chander G, Bachhal V. Delay in surgery predisposes to meniscal and chondral injuries in anterior cruciate ligament deficient knees. Indian J Orthop 2016;50:492–8.
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[19] Nguyen JT, Wasserstein D, Reinke EK, Spindler KP, Mehta N, Doyle JB, et al. Does the chronicity of anterior cruciate ligament ruptures influence patient-reported outcomes before surgery? Am J Sports Med 2017;45:541–9. [20] Zoller SD, Toy KA, Wang P, Ebramzadeh E, Bowen RE. Temporal relation of meniscal tear incidence, severity, and outcome scores in adolescents undergoing anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2017;25:215–21. [21] Johnson VL, Guermazi A, Roemer FW, Hunter DJ. Loss of anterior cruciate ligament integrity and the risk of secondary meniscal injury and bone marrow lesions: data from the osteoarthritis initiative. Osteoarthr Cartil 2017;25:S364. [22] Persson F, Turkiewicz A, Bergkvist D, Neuman P, Englund M. The risk of symptomatic knee osteoarthritis after arthroscopic meniscus repair vs partial meniscectomy vs the general population. Osteoarthr Cartil 2018;26:195–201. [23] Smith MV, Nepple JJ, Wright RW, Matava MJ, Brophy RH. Knee osteoarthritis is associated with previous meniscus and anterior cruciate ligament surgery among elite college American football athletes. Sports Health 2017;9:247–51. [24] Bellabarba C, Bush-Joseph C, Bach JB. Patterns of meniscal injury in the anterior cruciate-deficient knee: a review of the literature. Am J Orthop 1997;26:18–23. [25] Hede A, Larsen E, Sandberg H. Partial versus total meniscectomy. A prospective, randomised study with long-term follow-up. Bone Joint J 1992;74:118–21.
Please cite this article as: Gupta R, et al, The role of meniscal tears and meniscectomy in the mechanical stability of the anterior cruciate ligament deficient knee, Knee (2018), https://doi.org/10.1016/j.knee.2018.09.007