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Asia-Pacific Journal of Sports Medicine, Arthroscopy, Rehabilitation and Technology 1 (2014) 90—95
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Original article
Risk factors for ipsilateral graft rupture or contralateral anterior cruciate ligament tear after anatomic double-bundle reconstruction
Tatsuo Maea,b *, Konsei Shino c, Norinao Matsumotob, Kenji Yonedab, Hideki Yoshikawaa,
Ken Nakata a
a Osaka University Graduate School of Medicine, Japan b Osaka Kousei-Nenkin Hospital, Japan c Yukioka Hospital, Japan
Received 5 March 2014; revised 16 April 2014; accepted 8 May 2014 Available online 26 June 2014
Abstract
Purpose: The purpose of this study was to clarify the risk factors for graft rupture or contralateral anterior cruciate ligament (ACL) tear after anatomic ACL reconstruction.
Methods: One hundred and eighty one patients with unilateral ACL injury underwent the anatomic double-bundle ACL reconstruction using autogenous semitendinosus tendon grafts. Of these, 149 patients were directly followed-up for more than 5 years (60—108 months) after the primary operation. For those with graft rupture or contralateral ACL tear, timing at re-injury and cause of re-injury were recorded. Demographic factors such as height, body weight, sex, age at operation and sports activity level, as well as the surgical factors such as graft diameter and associated meniscal injury were noted.
Results: Eighteen patients (12.1%) sustained the graft rupture or the contralateral ACL injury in obvious accidents. Of them, ACL graft rupture occurred in seven patients (4.7%), whereas contralateral ACL injury occurred in 11 patients (7.4%). There was a high correlation between graft rupture and age (r = —0.962, p < 0.001) and activity level (r = 0.995, p < 0.001), whereas the other factors had no correlation. Age and activity level also had a high correlation with contralateral ACL tear (p < 0.001).
Conclusion: Both youth and high-level sports activity were potential risk factors for ACL graft rupture or contralateral ACL tear, whereas the other demographic and surgical factors had no correlation to graft or ACL tear. Level of Evidence: Level IV, case series.
Copyright © 2014, Asia Pacific Knee, Arthroscopy and Sports Medicine Society. Published by Elsevier (Singapore) Pte Ltd. All rights reserved.
Keywords: anterior cruciate ligament (ACL); contralateral ACL rear; double-bundle ACL reconstruction; ipsilateral graft rupture; risk factors
Introduction
Anterior cruciate ligament (ACL) reconstruction with hamstring tendon graft has been widely performed due to reduced graft harvest site morbidity. Satisfactory outcomes have also been reported after ACL reconstruction,1—5 but significant percentages of patients suffer from graft ruptures or
* Corresponding author. Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, 2-2, Yamada-oka, Suita-city, Osaka 565-0871, Japan.
E-mail address: ta-mae@umin.ac.jp (T. Mae).
contralateral ACL tear after reconstruction. Salmon et al6 reported that ACL graft rupture occurred in 39 out of 612 patients (6%) with conventional single-bundle ACL reconstruction, whereas contralateral ACL tear was also observed in 6% of cases. Shelbourne et al7 reported that 61 out of 1,415 patients (4.3%) went on to injure the ACL-reconstructed knee and that 5.3% suffered an injury to the contralateral ACL tear. Thus ACL graft rupture and contralateral ACL tear remain a serious issue to be addressed after the reconstruction.
There were several reports for analysing the causes of failure of ACL reconstruction.8—10 Menetrey et al8 proposed that "biological failure" should have been considered when a patient
http://dx.doi.org/10.1016/j.asmart.2014.05.001
2214-6873/Copyright © 2014, Asia Pacific Knee, Arthroscopy and Sports Medicine Society. Published by Elsevier (Singapore) Pte Ltd. All rights reserved.
presented with knee instability following ligament reconstruction and there was no history of a new trauma or identifiable technical errors. By contrast, according to the multicentre ACL revision study cohort,9 the mode of failure as deemed by the revising surgeon was technical (24%) as well as biological (7%).
Recent innovations in arthroscopic techniques and anatomical studies have changed ACL reconstruction more anatomically. There have been several reports of good outcomes after anatomic ACL reconstruction.11—15 Shino et al16 established the anatomic double-bundle ACL reconstruction with two femoral and tibial tunnels in the ACL footprint, and in a previous study13 we reported good 2-year outcomes with this procedure on 51 patients at more than 2-year follow-up. Of these cases, ACL graft rupture in the ipsilateral knees was found in three patients (5.9%) and ACL injury in the contralateral knees was observed in three patients (5.9%), and we were unable to find any technical or biological failures. This may suggest that the improvement in surgical technique has failed to reduce the rate of traumatic graft rupture or contralateral ACL tear. Thus it is important to scrutinize the causes for graft and contralateral ACL tears.
This study aimed to clarify the risk factors for graft rupture or contralateral ACL tear after anatomic ACL reconstruction. Emphases were on demographic factors such as height, body weight, sex, age, and sports activity level, as well as on surgical factors such as graft diameter and associated meniscal injury. Our hypothesis was that youth and high activity level were risk factors for re-injuring to the knee.
Materials and methods
Patients
One hundred and eighty one patients with unilateral ACL injury underwent the anatomic double-bundle ACL reconstruction using autogenous semitendinosus tendon grafts between April 2002 and December 2005. Of these, 149 patients were directly followed-up for more than 5 years after the primary operation, whereas 32 patients were lost to follow-up (follow-up rate: 82%). The follow-up period was 68.0 ± 9.4 months, with a range from 60 months to 108 months. The inclusion criteria were unilateral isolated ACL rupture and a normal contralateral knee. The exclusion criteria were concomitant ligament injury, concomitant fracture, and previous knee operations including meniscal surgery.
All patients had consented to be involved in this study. Informed consent was obtained from all participating adult patients and from parents or legal guardians for minors or incapacitated adults.
There were 78 males and 71 females included in this study. Their age at operation ranged from 13 years to 71 years, with a mean age of 29 years. At the time of the reconstruction, 60 patients had a medial meniscal tear and 55 patients had a lateral meniscal tear. Of the patients with a medial meniscal tear, 16 underwent meniscal repair, 33 underwent partial meniscectomy, and 11 underwent rasping without repair. In those with a lateral meniscal tear, 28 underwent meniscal repair, 30 underwent partial meniscectomy, and seven had rasping.
Operative procedure
ACL reconstruction was performed with the anatomic double-bundle technique under general anesthesia.16 After cleaning up the ACL remnant around the femoral attachment area, two 2.4-mm guide wires were inserted using the ante-rolateral entry femoral aimer (Smith & Nephew Inc. Endos-copy, Andover, MA, USA) with the outside-in technique in the ACL footprint behind the resident's ridge and just anterior to the cartilage margin. Then two 5.0- to 6.0-mm tunnels were made by over-drilling. For the tibia, two guide wires were inserted from the medial tibial cortex to the centre of the footprints of anteromedial and posterolateral bundles (the anterior and posterior portions of the tibial ACL footprint) with a drill guide system (Smith & Nephew Inc. Endoscopy). Two 5.0- to 6.0-mm tunnels were then created by over-drilling.
A previously harvested semitendinosus tendon was transected in half and then folded to make a pair of doubled grafts. Each graft was introduced through the tibial tunnels to the femoral tunnels, and fixed on the lateral femoral cortex by flipping the EndoButton (Smith & Nephew Inc. Endoscopy). Then, two Double-Spike Plates (Smith & Nephew Inc. Endoscopy) connected to each graft, respectively, were fixed on the tibia with a total of 20 N of initial tension (10 N to each graft) at 20° knee flexion with a tensioning boot, which was described previously.13
Rehabilitation program
After brace immobilization at 30° knee flexion for 1 week, range of motion exercise was started. Partial weight-bearing was allowed at 2 weeks, and full weight bearing was started 4 weeks after ACL reconstruction. Jogging was then allowed at 3 months, and return to previous sports activity was permitted at 8—9 months.
Follow-up evaluation
For those with graft rupture or contralateral ACL tear, timing at re-injury and cause of re-injury were recorded. For these patients, height, body weight, sex, age at primary operation, sports activity level after return to play, and knee laxity at final follow-up were noted. At the primary ACL reconstruction, moreover, femoral tunnel diameter as an indication of graft diameter, medial/lateral meniscal injuries, and medial/ lateral meniscectomy were recorded. Activity level was evaluated according to the Tegner activity scale.
Statistical analysis
Mann—Whitney U-test was used to detect significant differences in height, body weight, age, and sports activity level, whereas Chi-square analysis was performed to find significant differences in sex, graft diameter, meniscal injury, and meniscectomy between patients with and without graft rupture/contralateral ACL tear. To detect a significant difference in the timing of re-injury between patients with graft
rupture and those with contralateral ACL tear, Mann—Whitney U-test was also performed. Moreover, the correlative relation between age and graft rupture/contralateral ACL tear was calculated using Pearson's test. A p value of <0.05 was considered a significant difference.
Binary logistic regression analysis was used to measure the relative contribution of the selected variables, which were obtained from the patients' diagram and the operative records, on the risk of graft tear and contralateral ACL tear. Results were considered significant at the 95% confidence interval (CI) level for all statistical analyses.
Results
Of the 149 patients, 18 patients (12.1%) sustained a graft rupture or contralateral ACL injury. Of these, ACL graft rupture occurred in seven patients (4.7%), whereas 11 patients (7.4%) sustained contralateral ACL injury. All the patients who had sustained the graft rupture had had obvious accidents; contralateral ACL tears were also traumatic. The mean time from the reconstruction to graft rupture was 8.0 ± 2.8 months, whereas the time from the reconstruction to contralateral ACL injury was 30.0 ± 24.2 months. Graft rupture occurred significantly earlier than contralateral ACL injury (p = 0.002). Most of graft ruptures happened in the first 12 months after the operation (Fig. 1). Manual knee laxity tests including Lach-man and pivot shift tests did not find abnormal laxity at final follow-up prior to re-injury.
Ipsilateral graft rupture
Average height and body weight were 166.4 cm and 58.6 kg for the patients with graft rupture, whereas the values for the patients with no graft rupture were 165.8 cm and 56.6 kg, respectively. Height or body weight showed no correlation with risk of rupture (Table 1). Sex had no correlation either. There was, however, a significant correlation between rupture and age; as most of the patients with graft rupture were under 30 years of age, there was a high correlation between their age and graft rupture (r = —0.962, p < 0.001; Table 3). On return to sports activity, six patients tore the graft during
1-6 7-12 13-24 25-36 37-48 49-60 60-
Months from reconstruction to repeated injury
Fig. 1. Timing of re-injury. Key: ipsilateral graft tear, contralateral anterior cruciate ligament tear.
Table 1
Comparison of patients with and without ipsilateral graft rupture.
Patients with Patients without p graft rupture graft rupture
165.8 ± 7.5 0.968
56.6 ± 8.0 0.978
52.1 0.795
29.5 ± 12.6 0.013
18.3 0.001
43.7 0.483
52.1 0.659
40.1 0.886
36.6 0.768
22.5 0.608
19.7 0.569
Data are presented as % or mean ± SD. AM: anteromedial, PL: posterolateral.
sports activities above level 7 on the Tegner scale, whereas one slipped on a manhole cover. There was a high correlation between Tegner scale and graft rupture, if the manhole cover case was excluded (r = 0.995, p < 0.001; Table 4). Associated meniscal injuries and their treatments showed no correlation with the rate of graft rupture.
Logistic regression analysis on the selected variables failed to find any correlation between age [odds ratio (OR): 0.923; 95% CI: 0.767—1.109; p = 0.390; Table 5] or activity level (OR: 3.183; 95% CI: 0.950—10.670; p = 0.061) and ACL graft rupture.
Contralateral ACL tear
Average height was 166.5 cm for the patients with contralateral ACL tear and 165.8 cm for those with no
Table 2
Comparison of patients with and without contralateral anterior cruciate ligament (ACL) tear.
Patients with Patients without p
contralateral contra lateral
ACL tear ACL tear
Height (cm) 166.5 ± 10.1 165.8 ± 7.3 0.659
Weight (kg) 57.5 ± 13.5 56.7 ± 8.3 0.673
Male sex 54.5 52.2 0.880
Age (y) 18.2 ± 4.6 29.9 ± 12.6 <0.001
Activity level 63.6 17.4 0.187
>8 level of Tegner scale
Graft diameter (femoral tunnel diameter)
AM graft <5.0 mm 45.5 44.2 0.936
PL graft <5.0 mm 36.4 52.9 0.313
Meniscal injury
Medial meniscus 36.4 40.6 0.784
Lateral meniscus 54.5 35.5 0.227
Meniscectomy
Medial 18.2 22.5 0.742
Lateral 18.2 20.3 0.867
Data are presented as % or mean ± SD. AM: anteromedial, PL: posterolateral.
Height (cm) 166.4 ± 7.8
Weight (kg) 58.6 ± 13.5
Male sex 57.1
Age (y) 19.3 ± 5.3
Activity level 71.4
>8 level of Tegner scale Graft diameter (femoral tunnel diameter)
AM graft <5.0 mm 57.1
PL graft <5.0 mm 42.9 Meniscal injury
Medial meniscus 42.9
Lateral meniscus 42.9 Meniscectomy
Medial 14.3
Lateral 28.6
Table 3
Age versus ipsilateral graft rupture/contralateral anterior cruciate ligament (ACL) tear.
Table 5
Association of graft/contralateral anterior cruciate ligament tear with individuals and operation.
Age (y) Number of Ipsilateral graft rupture Contralateral ACL tear
patients Number Incidence (%) Number Incidence (%)
(female) (female) (female)
10-20 36 (24) 4(3) 11.1 7(4) 19.4
20-30 52 (17) 2 (0) 3.8 4(1) 7.7
30-40 36 (17) 1 (0) 2.7 0 0
40-50 11 (6) 0 0 0 0
50-60 9 (6) 0 0 0 0
>60 5 (1) 0 0 0 0
contralateral injury, whereas average body weight was 57.5 kg for patients with contralateral ACL tear and 56.7 kg for those without (Table 2). Height and body weight had no significant correlation with injury. Sex and activity level did not show significant correlation, but age was correlated with injury during follow up. Seven teenagers (19.4%) and four patients aged between 20 years and 30 years (3.8%) sustained a contralateral ACL tear, whereas no patients over 30 years of age tore it during the follow-up period (Table 3). There was also a high correlation between age and contralateral ACL tear (r = -0.992, p < 0.001). All 11 patients with contralateral ACL tear had returned to a sports activity level of more than 6 on the Tegner scale and sustained tears while playing (Table 4). There was also a high correlation between Tegner scale and contralateral ACL tear (r = 0.741, p < 0.001; Table 5). There was no correlation between graft diameter, meniscal injury, and type of meniscus surgery.
Logistic regression analysis found a significant correlation between age and contralateral ACL tear; (OR: 0.766; 95% CI: 0.627—0.936; p = 0.009). It did, however, fail to find a significant association between activity level and contralateral ACL tear (OR: 0.796; 95% CI: 0.380—1667; p = 0.545).
Discussion
In the current study, 4.7% of patients had ACL graft rupture and 7.4% suffered contralateral ACL injury during more than 5 years of follow-up after anatomic ACL reconstruction. Most
Table 4
Tegner activity scale versus ipsilateral graft rupture/contralateral anterior cruciate ligament (ACL) tear.
Tegner Activity Number Ipsilateral graft rupture Contralateral ACL tear
scale of patients Number Incidence (%) Number Incidence (%)
10 0 0 0 0 0
9 15 3 20 2 13.3
8 16 2 12.5 2 12.5
7 52 1 1.9 6 11.5
6 43 0 0 1 2.3
5 2 0 0 0 0
4 2 0 0 0 0
3 9 0 0 0 0
2 8 1 12.5 0 0
1 2 0 0 0 0
Ipsilateral graft rupture
Contralateral ACL tear
OR 95% CI p OR 95% CI p
Individuals
Height 0.804 (0.586, 1.103) 0.177 0.993 (0.780, 1.667) 0.951
Weight 0.861 (0.592, 1.233) 0.139 1.102 (0.898, 1.352) 0.355
Sex 0.302 (0.006, 14.375) 0.544 0.732 (0.028, 19.445) 0.852
Age 0.923 (0.767, 1.109) 0.390 0.766 (0.627, 0.936) 0.009
Activity 3.183 (0.950, 10.670) 0.061 0.796 (0.380, 1.667) 0.545
Operation
Graft diameter
AM graft 1.72 (0.371, 7.971) 0.483 1.619 (0.417, 6.286) 0.483
PL graft 0.689 (0.149, 3.191) 0.632 0.734 (0.189, 2.849) 0.654
Meniscal injury
Medial 0.894 (0.193, 4.146) 0.886 1.373 (0.330, 5.718) 0.662
meniscus
Lateral 0.77 (0.166, 3.577) 0.738 0.716 (0.184, 2.788) 0.629
meniscus
Meniscectomy
Medial 1.745 (0.203, 15.034) 0.608 0.995 (0.197, 5.037) 0.996
meniscus
Lateral 0.548 (0.101, 2.989) 0.482 2.09 (0.251, 17.389) 0.486
meniscus
ACL = anterior cruciate ligament; AM = anteromedial; CI = confidence interval; OR = odds ratio; PL = posterolateral.
of the graft ruptures occurred in the first 12 months after ACL surgery. The principle findings of this study were that the risk factors for subsequent injury included age and Tegner activity scale, which had a high correlation with the graft rupture and contralateral ACL tear.
Ipsilateral graft rupture
One of the major aims of ACL reconstruction is to restore normal ACL function, and therefore to let patients return to previous sports activities but some athletes are obliged to quit their sports activities following the graft or contralateral ACL tear. Shelbourne et al7 reported that 136 (9.6%) out of the 1,415 patients in their study had a subsequent ACL injury to either knee during a minimum of 5-years' follow-up after their mini-open ACL reconstruction. They also mentioned that 4.3% had an injury to the ipsilateral ACL-reconstructed knee. In the other previous reports, 3—10% of cases of ACL graft rupture occurred after arthroscopic reconstructions aiming for isometric single-bundle graft.6,17 The causes of ACL rupture included non-traumatic failure. There were some reports giving details of the causes of ACL reconstruction failure, such as biological failure, femoral/tibial tunnel malposition, and elongation of graft.8—10 In their multicentre retrospective study, Trojani et al9 stated that the main cause of failure was femoral tunnel malposition (36% of cases). Due to improvement in surgical instruments based on recent anatomical studies, ACL reconstruction technique shifted to the anatomic double-bundle technique, and was followed by many reports of good outcomes.11—'15 In this study, although there were no cases of biological failure or tunnel malpositioning in our
series, graft rupture occurred in 4.7% of the 118 cases that had undergone anatomic double-bundle ACL reconstruction. Though it may appear that the graft rupture rate was similar to that in previous reports, the patients with no graft ruptures in the current study showed better kT values or restored stability compared to the previous reports in which some loosened grafts were insidiously included. Thus the current advancement in anatomic ACL reconstruction may have achieved a better success rate, while it could not reduce the traumatic graft rupture.
Contralateral ACL tear
Contralateral ACL tear after a return to sports activity was also one of the unsolved problems after ACL reconstruction. According to previous reports, 3—10% of contralateral ACL tears were observed after isometric single-bundle ACL re-constructions.6,7,17 Shelbourne et al7 reported that 5.3% of the 1,415 patients injured the contralateral normal knee during a minimum 5-year follow-up. In this study, contralateral ACL tear happened in 7.4% of the 118 cases with anatomic double-bundle ACL reconstruction. As the rate of the contralateral ACL tear was similar to that in previous reports, rehabilitation programmes or timing of return to play may be a problem and should be reconsidered.
The patients with graft rupture and those with contralateral ACL tear were significantly younger than those without in this study. Shelbourne et al7 sorted patients into the three groups based on age (<18 years, 18—25 years, and >25 years) and compared the incidence of subsequent ACL injury to either knee among the three groups. They reported that the highest risk of subsequent injury was in the <18-years group, where there was 8.7% incidence of injuring the previously ACL-reconstructed knee and an 8.7% incidence of injuring the contralateral knee. Magnussen et al 18 compared revision rates in patients aged > 20 years and those aged < 20 years. They found that 0.7% of 137 patients aged > 20 years required revision surgery, whereas 14.3% of 119 patients aged < 20 years had revision surgery. We first divided the relationship between age and graft/contralateral ACL tears into 10-year bands and found that there was a significant negative correlation between the subsequent injuries and age among the patients with wide range of ages (from 13 years to 71 years). No patients >40 years in age sustained graft rupture or contralateral ACL tear, therefore youth is a risk factor for both.
Sex could also be a factor for graft rupture and contralateral ACL tear, as it is well accepted that females more frequently sustained ACL injury than males. Salmon et al,6 however, mentioned an overall incidence of graft rupture in the ACL reconstructed knee of 8% for males and 4% for females, and showed no significant difference. They also reported that an
incidence rate of contralateral ACL injury was 5% for males and 7% for females, and that there was no significant difference. Laboute et al19 reported no significant difference between sexes, with the incidences of graft rupture after ACL reconstruction being 8.9% for males and 7.8% for females. We found no significant difference in the incidence between sexes either. It is worth noting, however, that all three females with graft rupture were teenagers, and males with graft rupture were distributed from teens to 30s. Thus, female teenagers might have a higher risk of graft rupture.
Sports activity
There are some previous reports that athletes with higher sports activity had a higher risk of graft rupture.6,7,20 Borchers et al20 reported that those with a high activity level had greater odds of ACL graft rupture than those with a lower activity level, though there were no increased odds of graft rupture based on activity level at the time of the initial injury. Salmon et al6 reported that regression analysis revealed that the most significant contributor to the odds of contralateral ACL injury was return to level 1 or 2 activities according to the 1993 International Knee Documentation Committee scale, as the incidence of the contralateral ACL injury in level 1 or 2 activity participants was 10 times as high as those participating in level 3 or 4 activities. In the current study, there were six re-tear cases during sports activities of level 7 or greater according to the Tegner scale, with the exception of one accidental injury. A care or training programme may therefore be needed to prevent further injuries when highly active patients are allowed to return to sports.
Operative procedure
Magnussen et al18 reported that the distribution of graft revisions increased with smaller graft diameter in single-bundle ACL reconstruction with hamstring autograft, and mentioned that revision was required in 13.6% of cases with a graft of 7 mm or less in diameter. However, this study did not show any relation between graft diameter and graft rupture in the anatomic double-bundle reconstruction. It was our policy to avoid using too thin a graft, and to harvest gracilis tendon as well in case of a thin SMT graft of <7 mm as a whole, so our results were unable to show the correlation between graft diameter and ACL rupture. The current study did not demonstrate any correlation between meniscal injury/menis-cectomy and ACL graft/contralateral ACL tears, thus the association between meniscal injury and meniscectomy had little effect on graft rupture or contralateral ACL injury. This suggests that our thicker ACL grafts are tough enough to protect against anterior shear stress without the support of the posterior horn of the menisci.
Limitations
There were some limitations in this study. First, the patients were only followed-up for 68 months on average. The longer
the follow-up was, the more likely a graft and/or contralateral ACL tear would be to occur; however it could be assumed that a 5-year follow-up period is appropriate, as most athletes reduce their sports activity level due to graduation or aging. Second, no athletes of a very highly active sports level (a Tegner scale of 10) were included in this study. Though a high correlation between activity level and graft/contralateral ACL tears was found, the correlation might have been different with the inclusion of very high activity athletes, who have a high rate of injury.
Conclusion
ACL graft rupture most frequently occurred in the 12 months after anatomic double-bundle ACL reconstruction. Both youth and high levels of sports activity were potential risk factors for ACL graft rupture or contralateral ACL tear, whereas other demographics and surgical factors did not have any correlation with graft or ACL tear.
Conflicts of interest
K.S. is a consultant for Smith & Nephew. The remaining authors have no conflicts of interest.
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