Abstract
Background
Anterior Cruciate Ligament (ACL) injuries are often associated with meniscus tears. These meniscus tears in long term may affect the functional outcomes after ACL reconstruction. The present study aims to identify the incidence and relative association of meniscus injuries in complete and partial ACL injuries.
Methods
This was a retrospective study. Patients were divided into 2 groups; group I: partial ACL tear and group 2: complete ACL tear. Both groups were assessed for meniscal tears; either isolated medial/lateral or combined and odds ratio was measured between two groups.
Results
A total of 43 and 219 patients were enrolled in group I and II respectively. The mean age (years) in group I and II were 25.32 ± 7.12 and 28.64 ± 10.84 respectively. There were a total of 5 and 28 females in group I and II respectively. Mean pre-injury Tegner score in group I and II was 7.02 ± 2.87 and 6.82 ± 3.14 respectively. Mean time from injury to surgery (months) in group I and II was 8.04 ± 6.43 and 7.62 ± 4.83 respectively. In group 1 There were a total of 6 with lateral meniscus tears, 9 with medial meniscus tears And 3 with combined meniscal tears in group 1 while in group 2, 47 had lateral meniscal tears, 71 had medial meniscal tears and 71 had combined tears. Group II patients had stronger association for isolated meniscal tears compared to group I, with an odds ratio of 5.05(p < 0.05). Combined meniscal tears had non-significant relation in two groups (p = 0.58).
Conclusion
Partial ACL injuries present with less risk of acquiring isolated meniscus tears, compared to complete ACL injuries.
Keywords: Meniscus tears, Relative risk, Anterior cruciate ligament, Complete, Partial
1. Introduction
Anterior Cruciate ligament (ACL) is a primary restraint to the anterior translation of the knee and provides rotational stability in both the frontal and sagittal planes.1 Non-contact mechanism is the most common mode of injury, with pivoting and cutting sports contributing to most of the ACL injuries in the young athletic population.2 It is a widely accepted fact that ACL repair provides unsatisfactory healing and poor functional outcomes thus, Anterior Cruciate Ligament Reconstruction (ACLR) remains to be the current gold standard treatment to enable swift return to pre injury level sporting performance.
ACL injuries comprise of around 25%–50% of all the knee ligamentous injuries and partial ACL injuries represent 10%–27% of total ACL injuries, symbolizing a significant share of injuries.3 A combination of clinical examination including Lachman test, Pivot Shift test and imaging studies including Magnetic Resonance Imaging (MRI), provides a provisional diagnosis though no definitive diagnosis, can be reached without the help of diagnostic arthroscopy.3 The continued presence of the torn ACL fibres aids in biomechanical stability, better vascularity and proprioception aiding in the healing process and therefore the management depends upon the prevailing knee instability, functional limitations and laxity in the sportspersons when they are unable to reach an optimal fitness level to resume sporting activities at a pre-injury level.4
Meniscus tears are associated with the ACL injuries.5 Whereby, the incidence of meniscus tear in patients with complete ACL injury has been reported to be 51.9%–63%, incidence of meniscus injuries in partial ACL injuries remains to be undetermined.6,7 Further, the incidence of isolated tear of the medial meniscus and lateral meniscus and injury of the both menisci in complete ACL injuries has been reported from 13.9% to 29%, 19%–24.9%, and 9%–15% respectively, which in partial ACL injuries remains controversial.3,6,8, 9, 10
The presence of the biomechanical kinematic imbalance, resulting in meniscus injuries, has been proven in complete ACL injuries.11 As there are some left over fibres of the ACL in partial injuries, some inherent stability to frictional forces should exist under different loading conditions in pivoting and cutting sporting injuries and therefore, less meniscal injuries should occur in partial ACL tears as compared to complete tears.11 Based on this inference, we hypothesized that less meniscus injuries be observed in partial ACL injuries compared to the complete ACL injuries.
2. Materials and methods
This was a retrospective study carried out in the orthopaedics department of in a tertiary care setup. The data of consecutive patients (including demographic factors and site and type of meniscal tears), who got operated for partial ACL tears and complete ACL tears from 2017 to 2019, were taken from the operation theatre records, which were doubly checked from the admission files and electronic database, maintained in the medical records department and orthopaedics department respectively. Partial menisectomy was done in the patients s with unstable meniscal tears. (An unstable tear refers to a tear with a tear length that is more than one-half of the meniscus and the fragment subluxes under the condyle with probing. The meniscus also rolls when it is probed and there is delamination of the fibers with shredding of the meniscus).
All the surgeries were performed by a single surgeon (RG) using hamstring graft.10 The preoperative diagnoses were made using a combination of clinical examination (Lachman test, Anterior Drawer test and Pivot Shift test) and radiological examination including X-rays and Magnetic Resonance Imaging. On the arthroscopic evaluation, a partial tear was defined if even one of the bundles of the ACL (posterolateral bundle/anteromedial bundle) remained in continuity, if pivot shift on examination under anaesthesia was +1 of <, if Lachman test was found to be positive with firm end point and if on MRI some continuity of fibres of the ACL could be made out.12,13 The patients were divided into 2 groups; with group I having patients with partial ACL tear and group 2 having patients with complete ACL tear. Both the groups were assessed for meniscal injuries; isolated medial meniscus/lateral meniscus tear or combined meniscal tears and odds of the outcome were measured between the two groups.
Inclusion criteria were: 1) patients aged 18–45 years with a history of clear trauma 2) either a partial or a complete ACL tear as determined by clinical examination and MRI 3) complaints of instability (feeling of giving away of knee) and/or locking.
Exclusion criteria were: 1) Patients with multi-ligamentous injuries 2) Associated inflammatory or infective pathologies 3) Patient whose data could not be retrieved from any database.
Statistical Analysis: Quantitative data were given as mean ± SD. Multiple t-tests were applied to compare the quantitative data. Shapiro-Wilk test was performed to check the normal distribution of data. Categorical variables were reported as counts and percentages. Chi-square or Fisher exact test was used to compare the categorical data. All statistical analyses were performed at a significance level of p = 0.05. The analysis was conducted using IBM SPSS STATISTICS (version 22.0).
3. Results
A total of 43 patients with partial ACL tear and 219 patients with complete ACL tear fulfilled the inclusion criteria. The mean age of the patients (years) in the group I and group II was 25.32 ± 7.12 and 28.64 ± 10.84 respectively (Table 1). There were a total of 5 females and 38 males in group I and 28 females and 191 males in group II (Table 1). The mean pre-injury Tegner activity score in group I and group II was 7.02 ± 2.87 and 6.82 ± 3.14 respectively (Table 1). Mean time from injury to surgery in group I and group II were 8.04 ± 6.43 months and 7.62 ± 4.83 months respectively (Table 1). There were a total of 6 patients with lateral meniscus injuries, 9 patients with medial meniscus injuries and 3 patients with combined medial and lateral meniscus injuries in group I and 47 patients with lateral meniscus injuries, 71 patients with medial meniscus injuries and 29 patients with combined medial and lateral meniscus injuries in group II (Table 2). Further, rates of meniscal injuries as reported on MRI at the time of initial injury are mentioned in Table 5. Posterior horn and posterior horn with body were found to be the most commonly region of meniscal tear (Table 3). The group II patients were found to have stronger association for meniscal injuries compared to group I, with an odds ratio of 5.05 (Table 4). Further, isolated meniscal injuries (lateral/medial) were found to be statistically significant in complete ACL injury patients compared to the partial ACL injury patients (p < 0.05) [Table 5]. However, combined meniscal injuries were found to have non-significant relation in the two groups, with p value of 0.58 (Table 2).
Table 1.
Demographic details between the two groups.
| Category | Group I (n = 43) | Group II (n = 219) | P Value |
|---|---|---|---|
| Age (years) | 25.32 ± 7.12 | 26.64 ± 10.84 | 0.32 |
| Gender (Males: Females) | 5:38 | 28:191 | 0.83 |
| Mean time from injury to surgery (months) | 8.04 ± 6.43 | 7.62 ± 4.83 | 0.62 |
| Mean Tegner score | 7.02 ± 2.87 | 6.82 ± 3.14 | 0.69 |
Table 2.
Meniscus tears detail between the two groups.
| Category | Group I (n = 43) | Group II (n = 219) | P value |
|---|---|---|---|
| Medial Meniscus | 9 | 81 | 0.04 |
| Lateral Meniscus | 6 | 57 | 0.09 |
| Combined Lateral plus Medial Meniscus | 3 | 21 | 0.58 |
Table 5.
Meniscus tears detail between the two groups determined at the time of initial injury.
| Category | Group I (n = 43) | Group II (n = 219) | P value |
|---|---|---|---|
| Medial Meniscus | 12 | 85 | 0.03 |
| Lateral Meniscus | 7 | 59 | 0.14 |
| Combined Lateral plus Medial Meniscus | 5 | 23 | 0.72 |
Table 3.
Geographical mapping of meniscal tears between the two groups.
| Medial Meniscus | Lateral Meniscus | |||
|---|---|---|---|---|
| Group I (n = 12) | Group II (n = 102) | Group I (n = 9) | Group II (n = 78) | |
| Anterior horn | 0 | 0 | 0 | 0 |
| Posterior horn | 7 | 52 | 6 | 47 |
| Body | 1 | 4 | 0 | 3 |
| Posterior horn + Body | 4 | 43 | 3 | 26 |
| Anterior horn + Body | 0 | 2 | 0 | 1 |
| Complete tear | 0 | 1 | 0 | 1 |
Table 4.
Odds ratio for meniscal injuries between the two groups.
| Category | Group I (n = 43) | Group II (n = 219) | Odds Ratio |
|---|---|---|---|
| Medial Meniscus + Lateral Meniscus + Combined Lateral plus Medial Meniscus | 9 + 6+3 | 81 + 57+21 | 5.05 |
4. Discussion
In the present study, fewer number of meniscus tears were observed in partial ACL injuries compared to patients with complete ACL injury. Patients with complete ACL injury were found to have more risk of developing meniscal injuries, compared to patients with partial ACL injury (odds ratio = 5.05). Further, statistically significant correlation was observed with either of the isolated meniscal injuries (medial meniscus/lateral meniscus) with complete ACL injury patients, compared to the partial ACL injury patient group (p < 0.05). However, combined meniscus injuries were found to be same in the complete ACL injury patient group and partial ACL injury patient group (p > 0.05). In addition, posterior horn was most commonly involved region, for meniscal tears in both the groups and for both lateral and medial meniscus, as has been reported previously in the literature also. Both the group were comparable for age, gender, mean time from injury to surgery and mean Tegner activity score.
Yoo et al. Naranje et al. and Panisset et al. in their respective studies have reported strong association of complete ACL injuries with meniscus injuries, similar to the results of the current study, in which higher meniscal injuries were observed in the complete ACL injury patient group.12,14,15 Similarly, sensor testing system/biomechanical studies by several authors revealed higher mechanical forces on menisci in ACL deficient knees and thus greater chance of getting menisci injuries complementing the results of the present study.1,16 However, all the above studies have several limitations. Firstly, they were either done on cadaveric models or finite system element system, which may not exactly relate to a knee in different stressful conditions. Further, these studies did not have a separate group of partial ACL injuries, compared to the present study, where partial ACL injury correlation with meniscus injuries was studied separately with a control group.
Gadeyne et al. stated that severity and incidence of lesions to the lateral meniscus appear to be unaffected by the time to surgery after trauma.6 Similarly, Michalitsis et al. revealed that time from injury to operative intervention was not a significant factor for the presence of a meniscal lesion.7 Both of these studies add on to the discussion that the incidence of meniscal injuries at the time of initial injury as compared to the incidence of meniscal injury at the time of surgery is similar and that incidence can be fairly predicted by the arthroscopic findings without creating any bias, as was done in the present study.6,7
Fayard et al. stated that a partial ACL injury progressed to a complete ACL tear in 39% of young active patients treated conservatively, with half of the complete tears presenting with a concomitant meniscal lesion at the time of reconstruction.11 Similarly, Fritschy et al. and Bak et al. in their respective studies found higher meniscal injuries in similar cohort of patients when their injuries progressed from partial to complete ACL injuries.13,16 However, these studies have several limitations. Firstly, these studies had a limited sample size, with no control groups, unlike the present study where separate groups were compared for meniscal injuries in complete ACL and partial ACL injuries. Secondly, mean time of injury to surgery was always more in these studies as similar cohort of patients was examined for meniscal injuries at different points of time.
Jiang et al. in their study reported, equal propensity of having meniscus injuries in partial and complete ACL injuries.15 However, this study was a cadaveric study with several limitations. Firstly, the cadaveric specimens don't accurately represent the age composition of the general population. Secondly, only the sagittal and axial plane forces were taken into consideration and not the coronal plane forces as the specimen model only allows such calculations to be done. Thirdly, the soft tissues surrounding the knees in the cadaveric knees may influence the impact force in various loading settings.
Studying the literature, the correlation of partial ACL injuries with menisci injuries remains to be controversial. Varied results have been reported in the literature adding to the discrepancy.2,5,7,11, 12, 13,15, 16, 17 Further, most the studies are limited by the presence of a small sample size, lack of control group, and heterogeneous group of patients in terms of age group, Tegner activity score and mean time from injury to surgery. The present study has case group and control group, with a homogenous group of population and optimal number of patients, with a similar Tegner activity score and mean time from injury to surgery.
4.1. Limitations of the study
This was a single centre study. Morphological classification of meniscal tears and chondral damage was not studied. Sample size was limited for partial ACL tears, though the standardised diagnosis, treatment, preoperative Tegner activity scores may have balanced the same. Despite these factors, this study cohort was relatively large when considering the incidence of partial ACL injuries. No follow-up of patients was done to assess for functional outcomes after menisectomy. Another limitation, may be a possible bias in recall of time interval between injury and surgery, and may not be the precise time interval.
5. Conclusion
Patients with complete ACL injury have more risk of acquiring isolated meniscal tears, compared to the partial ACL injury patients. However, combined meniscus tears are comparable in both partial and complete ACL injuries.
Funding
No funding received.
Ethical approval
Institutional ethical committee permission was taken before the start of the research.
Author credit statement
RG was the primary surgeon in all the cases and conceptualized the study. AS assisted in the case and wrote the manuscript. AR did the proof reading. GD and SS did the review of literature and editing of the manuscript.
Declaration of competing interest
No conflict of Interest for any author.
Contributor Information
Ravi Gupta, Email: ravikgupta@hotmail.com.
Akash Singhal, Email: akash15636@ymail.com.
Atul Rai Sharma, Email: atortho00001@gmail.com.
Sumukh Shail, Email: sumukh279@gmail.com.
Gladson David Masih, Email: gladsondavid32@gmail.com.
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