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Preoperative assessments completed for anterior cruciate ligament reconstructions with remnant preservation
∗Corresponding author: Mitsuaki Kubota. mkubota@juntendo.ac.jp
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Received: ,
Accepted: ,
This article was originally published by Reed Elsevier India Pvt. Ltd. and was migrated to Scientific Scholar after the change of Publisher.
Abstract
Abstract
The purpose of this study was to investigate the preoperative characteristics that are necessary to be able to perform reconstructions of the anterior cruciate ligament (ACL) with remnant preservation. The preoperative period was significantly shorter for patients in patients who received a reconstruction with remnant preservation than for those without remnant (3.9 months vs 16.0 months, p < 0.01). The cut-off time to be able to reconstruct an ACL with remnant preservation were 2.5 months. The preoperative period is important to perform an ACL reconstruction with remnant preservation.
Keywords
ACL
Remnant preservation
Preoperative period
1 Introduction
According to Crain et al, arthroscopic examinations completed for anterior cruciate ligament (ACL) reconstructions have revealed that several types of ACL remnants exist in the intercondylar notch.1 Changes in anterior laxity were associated with a specific pattern of scar formation within the notch. ACL reconstruction with remnant preservation contributes to the prevention of anterior laxity,2–6 preserves the ACL remnant's neural elements and mechanoreceptors,2,7–12 and provides a favorable effect on vascularity and reinnervation of the graft.13–15
There have so far been very few reports on the preoperative assessment of survival for ACL remnant. The purpose of this study is to investigate the preoperative characteristics that are necessary to be able to reconstruct ACL with remnant preservation.
2 Patients and methods
Between September 2006 and July 2010, a total of 640 ACL reconstructions were performed. ACL remnant was tried to preserve the remnant as much as possible. After insertion of the graft, preservation of the remnant was considered possible if following condition were met: (1) the graft was covered with synovial tissues and had abundant blood vessels, (2) coverage of more than 75% of the graft from the tibial attachment, and (3) presence of a bridge between the femur and tibia.16 One hundred patients received a reconstruction with remnant preservation during the period (group R). while the other 540 patients received a conventional reconstruction without remnant preservation. One hundred patients were extracted randomly among the patients who received a conventional reconstruction without remnant preservation (group C). Every patient reported knee trauma with rapid swelling and disability. The MRI was positive for ACL disruption in every patient. All of the patients suffered from an incapacity to resume their previous levels of activity due to the instability of their symptoms, and all were scheduled to receive complete ACL reconstructions. Five surgeons (M.K, Y.T, M.I, Y.S, H.K) performed the operations in this study. Prior to performing the ACL reconstructions, a thorough arthroscopic evaluation of each patient was performed. The arthroscopic evaluations identified four different patterns of ACL morphology, classified according to the criteria of Crain et al; group 1: ACL scarring to the PCL, group 2: ACL healing to roof of the notch, group 3: Attenuated ACL remnant healed to the lateral wall more anterior and distal than its anatomic origin, and group 4: Resorption of the torn ACL.1 The ACL reconstructions were performed with semitendinosous tendon in all cases. We attempted to perform ACL reconstructions with remnant preservation whenever possible.
In every case, the amount of time between the patient's first injury of the ACL and the reconstruction operation (called the preoperative period) was noted. Differences in the preoperative period were assessed for each group (group R and group C). In addition, the cut-off time to be able to reconstruct an ACL with remnant preservation was determined.
Gender, age, injury type (contact or non-contact), amount of antero-posterior instability (measured using KT-2000, 30lbs), pivot shift test grade, rate of meniscus injury (medial meniscus, lateral meniscus, or bilateral meniscus injury), and the rates of four ACL remnant groups were assessed for each group.
3 Statistical analysis
A Mann–Whitney U test (two tailed) was applied to evaluate the differences in the parameters of each operation. A Receiver Operating Characteristic (ROC) curve was applied to evaluate the sensitivity and specificity needed to be able to reconstruct an ACL with remnant preservation. All data analysis was performed with SPSS software, version 16.0.1 (SPSS, Chicago, IL).
4 Results (Table 1)
There were no significant differences for gender, age, injury type (contact or non-contact), or rate of meniscus injury between group R and group C.
| Group R | Group C | p-value | |
| Preoperative period (month) | 3.9 ± 4.5 | 16.0 ± 16.0 | <0.01a |
| Gender (male, %) | 70 ± 46.1 | 59 ± 49.4 | N.S. |
| Age (year) | 24.7 ± 8.3 | 25.4 ± 8.6 | N.S. |
| Injury type (contact injury rate, %) | 24 ± 42.9 | 19 ± 39.4 | N.S. |
| KT-2000 (mm) | 4.4 ± 2.0 | 5.3 ± 2.0 | <0.01a |
| Pivot shift test grade 1 (%) | 14 ± 35.0 | 9 ± 28.8 | N.S. |
| Pivot shift test grade 2 (%) | 94 ± 108.1 | 77 ± 42.3 | N.S. |
| Pivot shift test grade 3 (%) | 3 ± 17.1 | 14 ± 34.9 | <0.01a |
| Medial meniscus injury (%) | 12 ± 32.7 | 21 ± 40.9 | 0.087 |
| Lateral meniscus injury (%) | 16 ± 36.8 | 14 ± 35.0 | N.S. |
| Bilateral meniscus injury (%) | 3 ± 17.1 | 4 ± 19.8 | N.S. |
| ACL remnant group 1 (%) | 33 ± 47.3 | 27 ± 44.6 | N.S. |
| ACL remnant group 2 (%) | 52 ± 50.2 | 12 ± 32.7 | <0.01a |
| ACL remnant group 3 (%) | 15 ± 35.9 | 10 ± 30.2 | N.S. |
| ACL remnant group 4 (%) | 0 ± 0.0 | 51 ± 200.1 | <0.01a |
The preoperative period was significantly shorter for patients in group R than for those in group C (3.9 months in group R, 16.0 months in group C; p < 0.01). The cut-off time to be able to reconstruct an ACL with remnant preservation was 2.5 months (sensitivity 0.790, specificity 0.500).
The amount of antero-posterior instability, measured using KT-2000, was significantly lower for patients in group R than for those in group C. The incidence of pivot shift test grade 3 was lower for patients in group R than for those in group C (3% in group R, 14% in group C; p < 0.01).
The rates of four ACL remnant groups in a total 200 cases was 30%, 32%, 12.5% and 25.5% in group 1, 2, 3, and 4 respectively. In group R, the rates of four ACL remnant groups was 33%, 52%, 15%, and 0% in group 1, 2, 3 and 4, respectively. Otherwise, in group C, the rates of four ACL remnant groups 27%, 12%, 10% and 51% in group 1, 2, 3 and 4, respectively. The rate of group 2 ACL remnants (ACL healing to roof of the notch) was significantly higher in group R than in group C, and the rate of group 4 ACL remnants (Resorption of the torn ACL) was significantly lower in group R than in group C.
5 Discussion
According to Crain, arthroscopic examinations completed for anterior cruciate ligament (ACL) reconstructions have revealed that several types of ACL remnants exist in the intercondylar notch.1 In that study, 38% of patients had ligament scarring on the posterior cruciate ligament, 8% of patients had scar tissue that appeared to extend from the ACL fibers to the roof of the notch, 12% of patients appeared to have healed scarring on the lateral wall of the notch or the medial aspect of the lateral femoral condyle in a position anterior and distal to the ACL anatomic footprint, and 42% of patients had no identifiable ligament tissue remaining. In many cases, the femoral attachment of the ACL remnant is the posterior cruciate ligament (PCL); however, in some cases, the ACL remnant bridges the femur and the tibia, although the remnant's diameter is attenuated and its femoral attachment positions are slightly different from the normal anatomic origin.15 To some extent, this type of ACL remnant helps to prevent anterior knee laxity. In our study, a total of 200 ACL reconstruction was performed in 30% of the patients in group 1, 32% of the patients in group 2, 12.5% of the patients in group 3, and 25.5% of the patients in group 4. The rate of ACL remnant healing to roof of the notch was higher than that of the other reports. However, that is not accuracy because the incidence of ACL reconstruction with remnant preservation and that of without remnant preservation was not equal.
The ACL has an important proprioceptive role in the knee because it provides both antero-posterior (AP) and rotational knee stability.2–5,8,12,17–21 ACL remnants make a biomechanical contribution to AP and rotational knee stability in patients with a complete ACL injury.6 ACL remnants contributed to AP knee stability evaluated at 30° of knee flexion for up to one year after injury.22 Adachi et al reported that significantly better results of position sense and joint stability were obtained from ACL augmentation (with remnant preservation) than from conventional ACL reconstruction (without remnant preservation).2 Gohil et al used MRI scans to assess differences in revascularization after the use of standard vs minimal debridement techniques.23 They indicated that minimal debridement leads to earlier revascularization within the mid-substance of the ACL graft at two months. There was a significant reduction of the mid-substance signal six months after use of the minimal debridement technique. Therefore, ACL reconstruction with remnant preservation has many benefits for proprioception, vascularity, reinnervation of the graft, and prevention of anterior laxity.
There have so far been very few reports on the preoperative assessment of survival for an ACL remnant. Clinically, a partial rupture of the ACL should be suspected when the differential instrumented laxity is equal to or less than 6 mm with a typical delayed firm anterior endpoint noted during the Lachman test.24 Seki et al reported the frequency of major ruptures and meniscus injuries to affect the rate of remnant preservation.25 They separated patients into three groups based on the percentage of remnant preservation (0%–29%: disappear group, 30%–59%: moderate group, 60%–100%: preserving group). The patients in the preserving group had the lowest rate of major giving way and meniscus injury among the three groups.
The preoperative condition of patients with ACL injury was different depending upon the remnant volume.26 ACL remnant volume showed a weak correlation with age at surgery, preoperative period and preoperative knee laxity and that remnant volume also indicated a weak correlation with postoperative anterior laxity and subjective instability.
In our study, there was a statistically significant difference in the amount of antero-posterior laxity in patients with and in those without remnants. There were no statistically significant differences in meniscus injury; however, the patients who received a reconstruction without remnant preservation had more meniscus injury than those who received a reconstruction with remnant preservation. The preoperative period was significantly shorter in patients with remnant preservation than in those without remnant. The result was same as the report of Muneta.26 The incidence of giving way was expected to be higher when the preoperative period was longer. Therefore, we believe that ACL reconstructions should be performed earlier in order to preserve the remnants. The cut-off time to be able to reconstruct an ACL with sufficient remnant preservation was determined to be 2.5 months in this study.
There are some limitations and weaknesses associated with this study. First, a small number of cases were included. Second, five surgeons were involved. Finally, the technique of performing an ACL reconstruction with remnant preservation is difficult, and a learning curve was necessary in order to master the operation. All surgeons tried to perform ACL reconstructions with remnant preservation whenever possible. This procedure might be performed more often as the technique improves. More cases of ACL reconstructions with remnant preservation and clinical studies are required.
Conflicts of interest
All authors have none to declare.
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