Abstract
Background
Limited evidence is available comparing the modified transtibial (MTT) and transportal (TP) techniques in anterior cruciate ligament (ACL) reconstruction and their impact on returning to sports participation. The objective was to analyze the outcomes after arthroscopic reconstruction of the ACL in recreational athletes with a 2-year postoperative follow-up, comparing the MTT and TP techniques, based on the method used to drill the femoral tunnel.
Hypotesis
The rate of return to sport would be comparable regardless of the surgical technique used.
Material and methods
A retrospective study was conducted with 66 patients who underwent arthroscopic monofascicular ACL reconstruction between September 2016 and March 2020. Patients aged between 16 and 50 years old, recreational athletes at Tegner levels 6 and 7, with a 2-year follow-up were included. Groups were established for comparative analysis (MTT vs TP) based on the method for drilling the femoral tunnel. The main outcome variable was the return to sport at the same level. Secondary variables included patient satisfaction evaluated with a visual analogue scale (VAS) and knee function according to the Lysholm scale.
Results
At 2 years of postoperative follow-up, the return to sport rate was 30.3 % in the MTT group and 33.3 % in the TP group (p = 0.791). There were no significant differences between both groups in patient satisfaction (p = 0.664) and knee function (p = 0.113).
Conclusion
Drilling the femoral tunnel with the MTT and TP techniques did not influence the rate of return to sport, patient satisfaction, and knee function in recreational athletes with 2 years of postoperative follow-up.
Level of evidence
III.
Keywords: ACL, Knee, Arthroscopy, Ligament reconstruction, Sport, Satisfaction
1. Introduction
In monofascicular arthroscopic reconstruction of the anterior cruciate ligament (ACL), traditionally, the femoral tunnel has been created through the tibial tunnel. However, in the last two decades, the transportal technique (TP) has been gaining popularity. This technique, performed through the anteromedial portal, aims to replicate the anatomical footprint of the ACL on the external femoral condyle, resulting in greater rotational stability as demostrated in biomechanical studies.1 Despite the mechanical advantages of the TP technique, comparative studies have not consistently shown superior clinical outcomes when compared to other femoral tunnel drilling methods.2 Some authors have suggested that achieving an anatomically positioned femoral tunnel can be accomplished through modifications to the transtibial procedure,3,4 resulting in satisfactory clinical outcomes.5, 6, 7
Injuries requiring ACL reconstruction are more common in young and athletic individuals, with returning to sport being a key goal. However, research indicates that the rate of return to sport may be lower than expected,8 and may not align with functional assessments,9 impacting patient satisfaction levels.10 Few studies have compared the outcomes of ACL reconstruction using the transportal technique versus the conventional transtibial technique in terms of return to sport rates and patient satisfaction.11, 12, 13 Furthermore, limited research is available on the comparison between the TP and modified transtibial (MTT) techniques and how they impact the return to sports participation.5,6,14
The main objective of this study was to evaluate the rate of return to sport in amateur athletes after undergoing arthroscopic monofascicular ACL reconstruction, with a 2-year follow-up, comparing the MTT and TP techniques. Secondary goals included assessing patient satisfaction with the final result and the functional outcome of the knee. The hypothesis was that the rate of return to sport would be comparable regardless of the surgical technique used.
2. Material and Methods
2.1. Patients
A retrospective study was conducted at a single institution after receiving approval from the Ethics Committee of Clinical Research, and informed consent was obtained from all patients. The study followed the recommendations of the STROBE (Strengthening the reporting of observational studies in epidemiology) statement. Patients with ACL rupture who underwent arthroscopic monofascicular reconstruction using autograft between September 2016 and March 2020 were identified in the departmental database.
The inclusion criteria were patient between 16 and 50 years old, levels 6 and 7 of the Tegner physical activity scale,15 and a minimum postoperative follow-up of 2 years. In our area, the Tegner levels selected are the most frequent in daily clinical practice. The exclusion criteria included multiligamentous injuries, osteochondral injuries, and meniscal tears treated with meniscal suture, as these cases required different postoperative protocols.
The MTT technique was performed at our center from 2016 to 2018. Subsequently, based on reported evidence, it was gradually replaced by the anatomical technique, creating the femoral tunnel through the anteromedial portal. Therefore, a sequential distribution of the sample was conducted: the MTT method was used in the first part of the study (MTT group), and then the TP method was introduced (TP group). For the purposes of this study, the first 10 surgeries using the TP technique were excluded from the analysis to avoid bias caused by the learning curve associated with the new technique.
2.2. Surgical protocol
All surgeries were performed at least 6 months after the injury and were conducted by the Head of the Knee Department using a hamstring autograft. In the MTT technique, modifications of the transtibial surgical procedure, as described in previous studies,3,5 were utilized to drill the femoral tunnel as close as possible to the anatomical footprint of the ACL. The tibial starting point was discreetly marked, positioned more medially and proximally, always ensuring that the tunnel's length was sufficient for adequate fixation. A laterally rotated 8-mm-offset femoral tunnel guide was used. A femoral tunnel guide with an 8 mm offset, rotated laterally, was utilized. Mild varus and internal rotation of the tibia were employed to better align with the anatomical landmark of the femoral tunnel.
2.3. Methods of assessment
Patients were evaluated both before and after surgery at 1, 3, 6, 12, and 24 months. During each evaluation, data collection for every patient was done in a standardized way. The postoperative data used for analysis were those recorded 2 years after surgery.
The primary outcome variable was the return to sport at the same level. A comparative analysis was conducted between patients who returned to the same level and those who returned to a lower level or did not return to sport. Secondary outcome variables included patient satisfaction and functional knee status. Satisfaction levels were measured using a visual analogue scale (VAS). Functional assessment was evaluated using the Lysholm scale,15 categorizing outcomes as excellent (>90 points), good (84–90), fair (64–83), and poor (<64 points).15,16 For statistical analysis, this variable was dichotomized into satisfactory (excellent and good) and unsatisfactory outcomes (fair and poor). The knee clinical assessment included the manual Lachman test and the pivot-shift test for assessing anteroposterior and rotational stability.
Epidemiological data, as well as the presence of intraoperative and postoperative complications, were also collected.
2.4. Statistical analysis
The sample size was determined based on the proportions of the main outcome variable in a previous study.13 For a 1:1 control/case ratio, α error = 0.05, β error = 0.80, and the reference proportions, a sample of 23 patients per group was calculated. Considering possible losses of 10 %, a minimum sample of 26 patients per group was estimated.
Data were analyzed using the IBM-SPSS program, v. 25.0 (IBM, Armonk, USA). The normal distribution was tested using the Kolmogorov-Smirnov test. Categorical variables were compared using the chi-square test, while continuous variables were compared using either the Student's t-test or the Mann-Whitney test. Multivariate logistic regression analysis was performed and data were presented as odds ratio (OR) with a 95 % confidence interval (CI). The goodness of fit of the model was analyzed using the Hosmer-Lemeshow test. ROC curve analysis was conducted to evaluate the discriminative capacity of continuous variables in distinguishing between patients who returned to sport at the same level and those who did not. Statistical significance was considered for values of p < 0.05.
3. Results
Sixty-eight patients met the selection criteria. In 2 cases, the minimum required postoperative follow-up could not be completed, resulting in their exclusion. The final series consisted of 66 patients, with 33 in the MTT group and 33 in the TP group. Baseline characteristics are shown in Table 1.
Table 1.
Baseline data of patients in both groups.
| Variables | MTT group (n = 33) | TP group (n = 33) | p |
|---|---|---|---|
| Age (years) | 32.9 (9.6) | 31.9 (11.3) | 0.683 |
| Gender (n) | 0.215 | ||
| male | 29 (87.9 %) | 24 (72.7 %) | |
| female | 4 (12.1 %) | 9 (27.3 %) | |
| Surgical delay (months) | 5.4 (2.6) | 5.8 (1.1) | 0.435 |
| Surgery time (minutes) | 43.4 (9.8) | 46.9 (6.4) | 0.096 |
| Graft thickness (mm) | 8.3 (0.6) | 8.2 (0.5) | 0.688 |
| Meniscal teara (n) | 0.314 | ||
| yes | 22 (66.7 %) | 18 (54.5 %) | |
| no | 11 (33.3 %) | 15 (45.5 %) | |
| Tegner activity scale (n) | 0.622 | ||
| level 6 | 17 (51.5 %) | 15 (45.5 %) | |
| level 7 | 16 (48.5 %) | 18 (54.5 %) |
Continuous variables expressed as mean (standard deviation).
MTT, modified transtibial. TP, transportal.
Associated meniscal tears that required partial meniscectomy in the same surgical procedure.
After 2 years of follow-up post-ACL reconstruction surgery, 10 patients (30.3 %) in the MTT group and 11 (33.3 %) in the TP group returned to sport at the same level (p = 0.791) (Table 2). Out of the total sample, 17 patients were unable to return to sport, with the main reason being fear of a new injury in 14 patients (82.3 %), while 3 patients (2 from the TP group and 1 from the MTT group) reported occasional discomfort due to mechanical overload in the operated knee.
Table 2.
Return to sport rates by groups.
| Return level | MTT group (n = 33) | TP group (n = 33) |
|---|---|---|
| Same level (n) | 10 (30.3 %) | 11 (33.3 %) |
| Lower level (n) | 15 (45.5 %) | 13 (39.4 %) |
| No return (n) | 8 (24.2 %) | 9 (27.3 %) |
MTT, modified transtibial. TP, transportal.
Patients who returned to the same level had significantly greater postoperative mean flexion (p = 0.000) and less postoperative knee extension lag (p = 0.010) (Table 3). In the multivariate analysis, postoperative knee flexion was a predictor of returning to sport at the same level (OR 1.11; 95 % CI 1.05–1.1; p = 0.000). The Hosmer-Lemeshow test indicated a good fit of the data (p = 0.745).
Table 3.
Comparative analysis of patients who returned to sport at the same level or not.
| Variables | Same level (n = 21) | Not same level (n = 45) | p |
|---|---|---|---|
| Surgical technique (n) | 0.792 | ||
| MTT | 10 (47.6 %) | 23 (51.1 %) | |
| TP | 11 (52.4 %) | 22 (48.9 %) | |
| Age (years) | 30.8 (9.5) | 33.1 (10.8) | 0.405 |
| Gender (n) | 0.928 | ||
| male | 17 (81.0 %) | 36 (80.0 %) | |
| female | 4 (19.0 %) | 9 (20.0 %) | |
| Meniscal teara (n) | 0.140 | ||
| yes | 10 (47.6 %) | 30 (66.7 %) | |
| no | 11 (52.4 %) | 15 (33.3 %) | |
| VAS satisfaction (pts) | 9.2 (0.9) | 7.9 (2.3) | 0.002 |
| Postb Lysholm score (pts) | 96.0 (4.8) | 92.3 (9.4) | 0.039 |
| Postb flexion (°) | 138.1 (11.2) | 123.1 (10.3) | 0.000 |
| Postb extension lag (°) | 0 (0) | 0.8 (2.2) | 0.010 |
Continuous variables expressed as mean (standard deviation).
MTT, modified transtibial. TP, transportal.
Associated meniscal tears that required partial meniscectomy in the same surgical procedure.
Post, postoperative.
In terms of patient satisfaction with the outcome, there were no significant differences between both groups (Table 4). Satisfaction levels were notably higher in patients who returned to sport at the same level (p = 0.002). There were no significant differences between groups regarding the Lysholm score (p = 0.113). The final score on the Lysholm scale was better in patients who returned at the same level (Table 3).
Table 4.
Secondary outcome variables.
| Variables | MTT group (n = 33) | TP group (n = 33) | p |
|---|---|---|---|
| VAS satisfaction | 8.4 (1.6) | 8.2 (2.5) | 0.664 |
| Posta Lysholm score (pts) | 94.0 (8.0) | 89.5 (14.0) | 0.113 |
| Posta flexión (°) | 126.5 (9.2) | 123.8 (10.1) | 0.260 |
| Posta extensión lag (°) | 0.4 (1.4) | 0.7 (2.2) | 0.513 |
Continuous variables expressed as mean (standard deviation).
MTT, modified transtibial. TP, transportal. VAS, visual analog scale.
Post, postoperative.
The mean Lysholm score, knee flexion and extension lag significantly improved from preoperative to the final follow-up in both groups. After surgery, there were no significant differences between the groups in terms of Lysholm score, knee motion or the Lachman and pivot shift tests (Table 5).
Table 5.
Clinical outcomes.
| Variables | MTT group (n = 33) | TP group (n = 33) | p |
|---|---|---|---|
| Lysholm score | |||
| Pre | 63.0 (14.3) | 61.6 (14.6) | 0.685 |
| Post | 93.7 (8.0) | 93.3 (8.8) | 0.839 |
| Knee flexion | |||
| Pre | 91.2 (4.1) | 91.5 (5.6) | 0.805 |
| Post | 129.5 (11.8) | 126.2 (13.4) | 0.289 |
| Knee extension lag | |||
| Pre | −5.7 (2.8) | −5.0 (1.2) | 0.166 |
| Post | −0.4 (1.4) | −0.7 (2.2) | 0.513 |
| Lachman test (n) (grade 0-1-2-3) | |||
| Pre | 0/15/16/2 | 0/14/16/3 | 0.889 |
| Post | 27/6/0/0 | 28/5/0/0 | 0.741 |
| Pivot shift-test (n) (grade 0-1-2-3) | |||
| Pre | 0/15/15/3 | 0/18/13/2 | 0.735 |
| Post | 28/5/0/0 | 31/2/0/0 | 0.427 |
Continuous variables expressed as mean (standard deviation).
MTT, modified transtibial. TP, transportal. Pre, preoperative. Post, postoperative.
ROC curve analysis evaluated the discriminatory ability of postoperative knee flexion and postoperative Lysholm score to identify patients who returned to sport at the same level. Only the postoperative Lysholm score showed adequate discriminative capacity (Fig. 1), with an AUC>0.7 (Table 6).
Fig. 1.
ROC curves for both variables.
Tabla 6.
ROC curve analysis outcomes.
| Variable | AUC | p | 95 % CI | Cut-off point | Sensibility | Specificity |
|---|---|---|---|---|---|---|
| Flexiona | 0.670 | 0.038 | 0.530–0.810 | 127.5 | 0.531 | 0.706 |
| Lysholmb | 0.735 | 0.004 | 0.583–0.888 | 88.0 | 0.918 | 0.471 |
AUC, area under the curve. CI, confidence interval.
Postoperative knee flexion.
Postoperative Lysholm score.
No intraoperative or medical complications were recorded. A 34-year-old man from the MTT group developed a granuloma over the tibial tunnel 26 months after surgery, which required surgical treatment. No cases of graft failure or postoperative infection were documented during follow-up.
4. Discussion
In the present study, there were no significant differences in the rate of return to sport, patient satisfaction, and knee function between MTT and TP groups at 2 years of postoperative follow-up. After ACL reconstructive surgery, only 31.8 % returned to sport at the same level. These rates are similar to those reported in studies with recreational athletes.13,17
Sohn et al.14 reported that the femoral tunnel was more horizontal with the TP or outside-in techniques compared to the MTT technique. However, this difference did not result in any significant variations in the rotational stability of the knee. Some randomized studies have also found no substantial differences in clinical outcomes between both methods.5,18 Similarly, in the meta-analysis of comparative studies by Cuzzolin et al.,2 independent drilling of the femoral tunnel yielded better outcomes than the transtibial approach, although the difference was not significant. This suggests that the key factor in achieving success was the accurate placement of the tunnel, rather than the specific drilling technique used.
Returning to sport is a primary goal for athletes following an ACL injury. However, few studies have evaluated this outcome by comparing femoral tunnel drilling techniques,11, 12, 13,19 with most studies using the conventional transtibial technique rather than the MTT as in our study. Some researchers noted a substantial decrease in surgery recovery time with the TP technique, with athletes returning to sports on average 1 month11,19 or 1.5 months12 earlier than those treated with the transtibial technique. However, these studies did not analyze the return rate, and had a postoperative follow-up of less than 24 months.12,19 Ruiz et al.13 evaluated the return to sport rate and found no significant differences between both groups, with a 2-year follow-up.
The literature indicates high levels of patient satisfaction following ACL reconstruction, closely linked to return to sport.10 Few comparative studies have examined patient satisfaction, particularly comparing the TP technique with the traditional transtibial technique. Our results align with those of Alentorn et al.11 and Ruiz et al.,13 who found no significant differences. However, Mardani et al.19 reported significantly higher satisfaction with the TP technique. Contrary to our results, the meta-analysis by Riboh et al.20 showed better scores on the Lysholm questionnaire with the TP technique. However, the authors questioned its clinical relevance, while Liu et al.21 found in their systematic review that the TP technique was superior to the transtibial technique.
The literature does not offer conclusive results on the clinical superiority of one technique over another, and the few comparative studies are focused on the conventional transtibial technique with a more verticalized femoral tunnel. On the other hand, studies using the MTT technique primarily focus on showing that anatomical reconstruction is achievable with this method, rather than on comparing clinical outcomes, return to sports, and patient satisfaction.4,7,22,23
The study has several limitations. The non-random distribution of patients may be a bias, although all surgeries were performed by the same surgeon, following the same postoperative protocols. The sample is small. Our intention was to continue with the study, but the COVID-19 pandemic stopped the scheduling of elective surgeries at our institution. The knee instability were recorded during follow-up, but objective measurements with an arthrometer were not performed. No radiological measurements have been performed to assess the precision of tunnel positioning with each surgical technique. However, the surgeries were carried out by an experienced surgeon in arthroscopic knee surgery and the initial procedures of the TP technique were omitted to minimize bias caused by the learning curve.
5. Conclusion
In monofascicular ACL reconstruction, femoral tunnel drilling using the MTT technique yields comparable outcomes to the TP technique, in terms of the return to sport rate, patient satisfaction, and knee function in recreational athletes who are at a level 6–7 on the Tegner activity scale, with 2 years of postoperative follow-up.
Declarations of interest
None.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Ethical statement
The work has been performed in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments with humans. The manuscript is in line with the Recommendations for the Conduct, Reporting, Editing and Publication of Scholarly Work in Medical Journals and aims for the inclusion of representative human populations (sex, age and ethnicity) according to those recommendations. The terms sex and gender have been used correctly.
Disclosure of interest
The authors declare that they have no conflict of interest.
Funding
None.
Contribution of authors
FAMM: conceptualization, methodology, validation, software, supervision. CPZ: analysis, investigation and interpretation of data. LAC: analysis and visualization. MFVM: critical revision.
All co-authors have seen and approved the final version of the paper and have agreed to its submission for publication.
Use of generative AI and AI-assisted technologies in the writing process
No generative artificial intelligence (AI) and AI-assisted technologies in the writing process.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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