Trauma and femoral tunnel position are the most common failure modes of anterior cruciate ligament reconstruction: a systematic review

The role of navigation technology in anterior cruciate ligament reconstruction bone tunnel positioning

In the past decade, navigation technology-assisted bone tunnels positioning for anterior cruciate ligament reconstruction (ACLR) has received great attention. The purpose of this review is to summarize the navigation technologies applied in ACLR, describe the tunnel positioning accuracy of these technologies, and summarize their advantages and disadvantages, providing a basis for navigation technology to assist ACLR. This review discusses the limitations of traditional bone tunnel positioning methods in ACLR and further introduces various navigation techniques, focusing on their positioning accuracy and postoperative outcomes for patients. Additionally, it presents commercial systems utilizing reality-based technologies and examines their impact on the arthroscopic learning curve for less experienced surgeons. The osseous landmarks are currently the most used positioning method, but they still have shortcomings. Navigation technologies primarily focus on computer-assisted navigation, which, however, requires additional incisions. Virtual reality and augmented reality are mainly utilized in preoperative planning, with the best-reported positioning accuracy of augmented reality being 0.32 mm, while most other accuracies are within 3 mm. Mixed reality offers a novel approach for precise positioning, resulting in more optimal and consistent postoperative tunnel placement. Navigation technology improves the positioning accuracy of the bone tunnels and achieves good short-term results. Key to the future is long-term follow-up to assess clinical outcomes of navigation techniques.

Causes of failed anterior cruciate ligament reconstruction: A retrospective case series

RATIONALE

The number of anterior cruciate ligament reconstruction (ACLR) surgeries in China is steadily increasing. To enhance the success rate of ACLR, it is crucial to understand the reasons for ACLR failure. The purpose of this study is to determine the primary reasons for ACLR failure and evaluate the technical skills associated with the revision procedure.

PATIENT CONCERNS

A retrospective clinical data analysis was performed for all patients who underwent anterior cruciate ligament revision surgery between January 2014 and September 2022. Each patient's data set consisted of the 3 items listed below: standardized imaging data, medical records, and all arthroscopic images and recordings from the revision surgery.

DIAGNOSES

A total of 65 patients underwent a failed ACLR surgery and then had to undergo revision surgery. Among these patients, the causes of revision were inappropriate tunnel placement (12, 18.75%), graft fixation problems (4, 6.25%), traumatic reinjury (35, 54.69%), graft failure (8, 12.5%), multiple ligament injuries (1, 1.56%), and infection (5, 7.81%).

INTERVENTIONS AND OUTCOMES

In patients with inappropriate tunnel placement, the femoral canal deviated anteriorly in 6 cases, posteriorly in 4 cases, and the tibial canal deviated anteriorly in 2 cases. In patients with graft fixation failure, the loop plate was loose in 1 case, the screw was not screwed in 2 cases, and the metal guidewire was not pulled out in 1 case. Of patients who suffered traumatic reinjury, 24 suffered high-power trauma, whereas 11 suffered low-power trauma. Graft relaxation occurred in 3 cases, and absorption was noted in 5 cases among graft failure patients. Joint instability resulted from multiple knee ligament injuries, along with medial and lateral collateral ligament damage. In cases of infection, knee joint infection occurred in 3 cases, while 1 case involved wound infection combined with bone tunnel lysis, and another case involved a knee joint infection emerging after the revision procedure.

LESSONS

ACLR failure is associated with traumatic reinjury, inappropriate tunnel placement, graft failure, graft fixation problems, infection, and multiple ligament injuries. Particular emphasis should be placed on the precise positioning of bone tunnels during surgical procedures. Proper manipulation of the aforementioned influencing factors is crucial to the success rate and therapeutic efficacy of arthroscopic ACLR.

Increased Lateral Femoral Condyle Ratio Is Associated With a Greater Risk of Anterior Cruciate Ligament Injury and Concomitant Anterolateral Ligament and Meniscus Injuries

PURPOSE

To investigate whether lateral femoral condyle ratio (LFCR) and lateral femoral condyle index (LFCI) were associated with a greater risk of anterior cruciate ligament (ACL) injury and concomitant injuries.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered on PROSPERO. PubMed, Web of Science, Embase, and the Cochrane Library were searched from inception to April 1, 2024. Studies evaluating the association between LFCR or LFCI and ACL injury were included. The following data were extracted: first author's name, study design, level of evidence, information of participants, radiologic method of measurement, and mean values for LFCR and LFCI. The quality assessment followed the Methodological Index for Non-Randomized Studies tool. The literature search, data extraction, and quality assessment were conducted by 2 authors independently.

RESULTS

A total of 14 studies comprising 2,386 participants were included. Notably, 11 studies explored the association between LFCR and ACL. Six studies showed that the mean LFCR in ACL injury group (range, 62.65%-70.1%) was significantly greater than control group (range, 59.3%-66.8%). Five studies reported that the increased LFCR was associated with a greater risk of concomitant anterolateral ligament injury and meniscal tear. However, 2 studies reported no significant association between LFCR and ACL reconstruction revision, with a mean LFCR ranging from 62.5% to 64.4% in the ACL reconstruction revision group and 62.8% to 64.2% in the primary ACL group. In addition, 2 studies reported that decreased LFCI was associated with a greater risk of ACL injury ranging from 0.60 to 0.78 for the ACL injury group and 0.60 to 0.85 for controls.

CONCLUSIONS

Increased LFCR was associated with a greater risk of ACL injury and concomitant anterolateral ligament injuries and meniscal tears. Furthermore, decreased LFCI was associated with a higher risk of ACL injury.

LEVEL OF EVIDENCE

Level III, systematic review of Level III studies.

Accuracy of femoral tunnel placement using three different techniques in performing arthroscopic all-inside anterior Cruciate Ligament reconstruction; A randomized study

Background

One of the key steps in arthroscopic Anterior Cruciate Ligament Reconstruction (ACLR) is getting the femoral tunnel at the right position to attach the graft. While the correct position has been described as a low and posterior position behind the bifurcate ridge on the medial surface of lateral femoral condyle, to reproducibly achieve it more than one technique is being used by surgeons. There are no randomized studies in literature which have evaluated the efficacy of these in a surgeon's hand. This study attempts to do that.

Methods

This randomized study was performed at a military sports injury centre by a single surgical team led by two sports fellowship-trained surgeons. One hundred fifty patients undergoing ACLR surgery were randomized to Anteromedial Portal technique e (AMP)group, Far Anteromedial portal technique (FAMP) group and Outside in drilling (OI) group. We used postoperative three-dimensional Computed Tomogram (3D CT) to study tunnel position (Magnussen method), length and orientation (Basdekis method).

Results

80 % of femoral entry points were in satisfactory position using all three techniques. The ideal position was achieved more often using FAMP & OI technique which was better than AMP, however it was not below level of significance set at P < 0.025 (18, 13 & 5 respectively using FAMP, OI and AMP techniques, p-value 0.08 OI vs AMP & 0.07 AMP vs FAMP). The average femoral tunnel length was longest in OI group 34.72 ± 2.41 mm. The mean FAMP tunnel lengths were significantly smaller than the mean tunnel length of AMP and OI groups. (p-value <0.01 FAMP vs OI and p-value <0.01 FAMP vs AMP).

Conclusion

Our study showed that all three techniques achieved acceptable femoral tunnel placement in 80 % cases. However, FAMP and OI technique further improved accuracy of achieving ideal tunnel location and OI technique predictably achieved longer tunnel length preventing risk of lateral blow out while using suspensory fixation.

Location of the Anatomic Footprint Centers of the Anterior Cruciate Ligament Determined by Quadrant Method on Three-Dimensional Magnetic Resonance Imaging

Background

The quadrant method is widely used to determine the femoral footprint center (FFC) on radiographs or computed tomography (CT) and can also describe the tibial footprint center (TFC). However, its application on three-dimensional (3D) magnetic resonance imaging (MRI) has been limited. This study aims to describe the ACL footprint center position on 3D MRI of healthy knees using the quadrant method.

Methods

Proton density (PD) sequence 3D MRI was conducted on 45 intact knees, aged 18 to 45 years. The centers of the ACL footprints were determined, and 2D simulated radiographic images were generated from the 3D MRI data. The quadrant method was then applied to calculate the positions of the footprint centers.

Results

The FFC was located at 31.6% in the deep-shallow (DS) direction and 31.3% in the high-low (HL) direction. The TFC was positioned at 45.1% in the mediolateral (ML) direction and 39.9% in the anteroposterior (AP) direction.

Conclusions

The ACL footprint centers identified in this study were positioned similarly to previous studies, with the exception of the TFC in the ML direction, which was found to be more medial. This approach has the potential to enhance preoperative planning and intra-operative navigation in ACL reconstruction surgeries.

Patient and Operative Risk Factors for Osteoarthritis After Primary Anterior Cruciate Ligament Reconstruction: A Cohort Study of 41,976 Patients

BACKGROUND

The reported incidence of posttraumatic knee osteoarthritis (PTOA) after primary anterior cruciate ligament reconstruction (ACLR) varies considerably. Further, there are gaps in identifying which patients are at risk for PTOA after ACLR and whether there are modifiable factors.

PURPOSE

To (1) determine the incidence of PTOA in a primary ACLR cohort and (2) identify patient and perioperative factors associated with the development of PTOA after primary ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data from the Kaiser Permanente ACLR Registry were used to conduct a cohort study. Patients who had undergone primary ACLR without a previous diagnosis of osteoarthritis were identified (2009-2020). The crude incidence of PTOA was calculated using the Aalen-Johansen estimator with a multistate model. The association of patient and operative factors with the development of PTOA after primary ACLR was modeled as a time to event using multistate Cox proportional hazards regression. Models stratified by age (<22 and ≥22 years) were also conducted because of the effect modification of age.

RESULTS

The study sample included 41,976 cases of primary ACLR. The incidence of PTOA was 1.7%, 5.1%, and 13.6% at 2, 5, and 10 year follow-ups, respectively. Risk factors for PTOA that were consistently identified in the overall cohort and age-stratified groups included a body mass index ≥30 versus <30 and an allograft or quadriceps tendon autograft versus a hamstring tendon autograft. Patients presenting with knee pain after ACLR were further identified when considering postoperative factors. Other risk factors for PTOA in the overall cohort included age ≥22 versus <22 years, bone-patellar tendon-bone autograft versus hamstring tendon autograft, hypertension, cartilage injury, meniscal injury, revision after primary ACLR with concomitant meniscal/cartilage surgery, multiligament injury, other activity at the time of injury compared with sport, and tibial tunnel drilling technique rather than the anteromedial portal.

CONCLUSION

Knee pain after ACLR may be an early sign of PTOA. Surgeons should consider the adverse associations of a higher body mass index and an allograft or quadriceps tendon autograft with the development of PTOA, as these were factors identified with a higher risk, regardless of a patient's age at the time of primary ACLR.

Young men undergoing anterior cruciate ligament reconstruction with patellar tendon autograft and anteromedial drilling outperform at 5- to 10-year follow-up in terms of graft stability and activity levels compared to those undergoing reconstruction with hamstring autograft and transtibial drilling

OBJECTIVE

To compare 5- to 10-year outcomes of anterior cruciate ligament (ACL) reconstruction in young men performed with bone-patellar tendon bone (BPTB) autograft and anteromedial portal to reconstruction with hamstring autograft and transtibial technique. It was hypothesised that in young adult men, at 5- to 10-year follow-up, superior restoration of knee laxity and activity levels would be demonstrated using BPTB autograft and anteromedial portal technique.

METHODS

Ninety-four men who had ACL reconstruction with BPTB autograft and anteromedial portal were eligible for comparison to 106 men who had reconstruction with hamstring autograft and transtibial technique. Inclusion criteria were: (1) age 18-35 years, (2) ACL tear caused by sports trauma only, (3) no concomitant ligament reconstruction and (4) 5- to 10-year follow-up. Outcome measures compared between the two groups included Lachman and pivot shift tests, KT side-to-side difference, Tegner and Marx scores, International Knee Documentation Committee (IKDC)-subjective score, Knee Osteoarthritis Outcome Scale (KOOS), Short Form (SF)-36, and single hop test for distance. P value ​< ​0.05 indicated statistical significance.

RESULTS

Forty-five patients with BPTB and 55 patients with hamstring ACL reconstruction were available for in-person assessment at 5-10 years after surgery. Outcomes in the BPTB group compared to the hamstring group showed KT difference 1.4 ​± ​1.9 mm vs. 2.8 ​± ​2.3 mm (p ​< ​0.01), pivot shift grade 2-3 in 4% vs. 34% (p ​< ​0.01), return to preinjury Tegner level in 51% vs. 36% (p ​= 0.1) and to preinjury Marx score in 29% vs. 11% (p ​= 0.02), and IKDC-subjective 88 ​± ​10 vs. 82 ​± ​13 vs (p ​< ​0.01), respectively. Statistically significant inter-relationships were found between KT side-to-side difference and the Tegner, Marx and IKDC-subjective scores at follow-up (r ​= ​-0.314, p ​< ​0.01; r ​= ​-0.263, p ​< ​0.01; r ​= ​-0.218, p ​= ​0.03, respectively).

CONCLUSION

Young men undergoing ACL reconstruction with patellar tendon autograft and anteromedial drilling outperform at 5- to 10-year follow-up in terms of graft stability and activity levels compared to young men undergoing reconstruction with hamstring autograft and transtibial drilling.

LEVEL OF EVIDENCE

III (Retrospective cross-sectional comparative study).

Functional and Symptomatic Improvements Based on the Femoral Tunnel Drilling Technique in Anterior Cruciate Ligament (ACL) Reconstruction

BACKGROUND

The current literature comparing femoral tunnel techniques often reports on short-term outcomes after anterior cruciate ligament reconstruction (ACLR), but only a few studies have analyzed long-term outcomes. In addition, many studies have compared transtibial to anteromedial portal techniques without differentiating whether rigid or flexible reaming is used, making it difficult to infer how the techniques truly compare to one another.

PURPOSE

This study aimed to detect differences in patient-reported outcome scores in those treated with three different femoral tunnel drilling techniques.

STUDY DESIGN

This study is a prospective cohort study.

METHODS

Of 650 patients treated for anterior cruciate ligament (ACL) injuries with ACLR, 350 were 5+ years out from surgery. Of these patients, 111 completed patient-reported outcome surveys (PROs). The Kruskal-Wallis H test was used to detect differences between patients treated with either of the three femoral tunnel drilling techniques: transtibial (TT), anteromedial portal with rigid reaming (AMP-RR), or anteromedial portal with flexible reaming (AMP-FR). Bonferroni correction was applied to the p-values to reduce the risk of making a type 1 error.

RESULTS

No differences were found between the three groups in demographics or postoperative PROs. However, there was a significant change between pre-surgery and post-surgery PROs. TT, when compared to AMP-RR, had a greater increase in satisfaction and greater improvement in a patient's ability to go up and down the stairs from pre-surgery to post-surgery. AMP-FR, when compared to TT, had greater improvement of the patient's knee stiffness/swelling. AMP-FR, when compared to AMP-RR, had greater improvement in knee pain during stairs and the ability to go down the stairs. No differences in return to sport, additional procedures on the affected knee (meniscal surgeries or cyclops lesion excisions), or revision surgery rates were found.

CONCLUSION

Overall, postoperative PROs did not show statistically significant differences between the three femoral tunnel drilling techniques. Differences, however, were identified in the responses to specific questions on PRO surveys, which may have otherwise been overlooked. It is important to recognize the differences between TT, AMP-RR, and AMP-FR in the improvement of stair climbing and swelling/stiffness as these likely directly affect a patient's satisfaction from pre-ACLR to post-ACLR.

Revision Anterior Cruciate Ligament Reconstruction and Associated Procedures

Failure of anterior cruciate ligament reconstruction (ACLR) is a common yet devastating complication due to inferior clinical outcomes associated with revision ACLR. Identifying the cause and associated risk factors for failure is the most important consideration during preoperative planning. Special attention to tunnel quality, concomitant injuries, and modifiable risk factors will help determine the optimal approach and staging for revision ACLR. Additional procedures including lateral extra-articular tenodesis and osteotomy may be considered for at-risk populations. The purpose of this review is to explore causes of ACLR failure, clinical indications and appropriate patient evaluation, and technical considerations when performing revision ACLR.

Evaluation of Failed ACL Reconstruction: An Updated Review

Failure rates among primary Anterior Cruciate Ligament Reconstruction (ACLR) range from 3.2% to 11.1%. Recently, there has been increased focus on surgical and anatomic considerations which predispose patients to failure, including excessive posterior tibial slope (PTS), unaddressed high-grade pivot shift, and improper tunnel placement. The purpose of this review was to provide a current summary and analysis of the literature regarding patient-related and technical factors surrounding revision ACLR, rehabilitation considerations, overall outcomes and return to sport (RTS) for patients who undergo revision ACLR. There is a convincingly higher re-tear and revision rate in patients who undergo ACLR with allograft than autograft, especially amongst the young, athletic population. Unrecognized Posterior Cruciate Ligament (PLC) injury is a common cause of ACLR failure and current literature suggests concurrent operative management of high-grade PLC injuries. Given the high rates of revision surgery in young active patients who return to pivoting sports, the authors recommend strong consideration of a combined ACLR + Anterolateral Ligament (ALL) or Lateral extra-articular tenodesis (LET) procedure in this population. Excessive PTS has been identified as an independent risk factor for ACL graft failure. Careful consideration of patient-specific factors such as age and activity level may influence the success of ACL reconstruction. Additional technical considerations including graft choice and fixation method, tunnel position, evaluation of concomitant posterolateral corner and high-grade pivot shift injuries, and the role of excessive posterior tibial slope may play a significant role in preventing failure.

The relationship between lateral femoral condyle ratio measured by MRI and anterior cruciate ligament injury

Background

Previous studies have shown that the lateral femoral condyle ratio (LFCR) measured by X-ray has a significant relationship with the anterior cruciate ligament (ACL) injury. However, few relevant studies have been performed on LFCR measured by magnetic resonance imaging (MRI).

Purpose

(1) To evaluate the relationship between LFCR measured by MRI and ACL injury or rerupture. (2) To compare the LFCR measured by MRI with existing bony morphological risk factors and screen out the most predictive risk factors for primary ACL injury or rerupture.

Study Design

Cohort study; Level of evidence, 3.

Methods

Totally 147 patients who underwent knee arthroscopic surgery from 2015 to 2019 with minimum follow-up of 48 months were retrospectively evaluated. Patients were placed into three groups: 1) the control group of patients with simple meniscus tears without ligament injury; 2) the primary noncontact ACL injury group; 3) ACL rerupture group (ACL reconstruction failure). The LFCR measured by MRI and other previous known risk factors associated with MRI (notch width index, medial tibial slope, lateral tibial slope, medial tibial depth, lateral tibial height) were performed to evaluate their predictive value for ACL injury and rerupture. All the risk factors with p < 0.01 according to univariate analysis were included in the logistic regression models. Receiver operating characteristic (ROC) curves were analyzed for sensitivity, specificity, cut-off, and area under the curve (AUC). Z tests were used to compare the AUC values.

Results

The LFCR measured by MRI was obviously higher in primary ACL injury group (0.628 ± 0.020) and in ACL rerupture group (0.625 ± 0.021) than that in the control group (0.593 ± 0.030). The best risk factor was the LFCR with a cut-off of 0.602 (AUC, 0.818; 95% CI, 0.748-0.878; sensitivity, 90%; specificity, 66%). When combined with lateral tibial slope (cutoff, 7°) and lateral tibial height (cutoff, 3.6 mm), the diagnostic performance was improved significantly (AUC, 0.896; 95% CI, 0.890-0.950; sensitivity, 87%; specificity, 80%).

Conclusion

The increased LFCR measured by MRI was associated with a significantly higher risk for ACL injury or rerupture. The combination of LFCR, lateral tibial slope and lateral tibial height were the most predictive risk factors. This may help clinicians identify susceptible individuals and allow precision approaches for better prevention, treatment and management of this disease.

Femoral Tunnel Malposition, Increased Lateral Tibial Slope, and Decreased Notch Width Index Are Risk Factors for Non-Traumatic Anterior Cruciate Ligament Reconstruction Failure

PURPOSE

To identify risk factors for patients who sustain nontraumatic anterior cruciate ligament reconstruction (ACLR) failure.

METHODS

A retrospective analysis was performed on patients undergoing primary or revision ACLR in our institution between 2010 and 2018. Patients sustaining insidious-onset knee instability without history of trauma were identified as nontraumatic ACLR failure and assigned to the study group. The control group of subjects who showed no evidence of ACLR failure with minimum 48-month follow-up were matched in a 1:1 ratio based on age, sex, and body mass index. Anatomic parameters including tibial slope (lateral [LTS], medial [MTS]); tibial plateau subluxation (lateral [LTPsublx], medial [MTPsublx]); notch width index (NWI); and lateral femoral condyle ratio were measured with magnetic resonance imaging or radiography. Graft tunnel position was assessed using 3-dimensional computed tomography and reported in 4 dimensions: deep-shallow ratio (DS ratio) and high-low ratio for femoral tunnel, anterior-posterior ratio and medial-lateral ratio for tibial tunnel. Interobserver and intraobserver reliability were evaluated by the intraclass correlation coefficient (ICC). Patients' demographic data, surgical factors, anatomic parameters, and tunnel placements were compared between the groups. Multivariate logistic regression and receiver operating characteristic curve analysis was used to discriminate and assess the identified risk factors.

RESULTS

A total of 52 patients who sustained nontraumatic ACLR failure were included and matched with 52 control subjects. Compared to patients with intact ACLR, those who sustained nontraumatic ACLR failure showed significantly increased LTS, LTPsublx, MTS, and deceased NWI (all P < .001). Moreover, the average tunnel position in the study group was significantly more anterior (P < .001) and superior (P = .014) at the femoral side and more lateral (P = .002) at the tibial side. Multivariate regression analysis identified LTS (odds ratio [OR] = 1.313; P = .028), DS ratio (OR = 1.091; P = .002), and NWI (OR = 0.813; P = .040) as independent predictors of nontraumatic ACLR failure. LTS appeared to be the best independent predictive factor (area under the curve [AUC] = 0.804; 95% confidence interval [CI], 0.721-0.887), followed by DS ratio (AUC = 0.803; 95% CI, 0.717-0.890), and NWI (AUC = 0.756; 95% CI, 0.664-0.847). The optimal cutoff values were 6.7° for increased LTS (sensitivity = 0.615, specificity = 0.923); 37.4% for increased DS ratio (sensitivity = 0.673, specificity = 0.885); and 26.4% for decreased NWI (sensitivity = 0.827, specificity = 0.596). Intraobserver and interobserver reliability was good to excellent, with ICCs ranging from 0.754 to 0.938 for all radiographical measurements.

CONCLUSIONS

Increased LTS, decreased NWI, and femoral tunnel malposition are predictive risk factors for nontraumatic ACLR failure.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The Iliotibial Band is the Main Secondary Stabilizer for Anterolateral Rotatory Instability and both a Lemaire Tenodesis and Anterolateral Ligament Reconstruction Can Restore Native Knee Kinematics in the Anterior Cruciate Ligament Reconstructed Knee: A Systematic Review of Biomechanical Cadaveric Studies

PURPOSE

To obtain a comprehensive overview of comparative biomechanical cadaveric studies investigating the effect of both the iliotibial band (ITB) and anterolateral ligament (ALL) on anterolateral rotatory instability (ALRI) in anterior cruciate ligament (ACL)-injured knees, and the effect of lateral extra-articular tenodesis (LET) versus ALL reconstruction (ALLR) in ACL-reconstructed knees.

METHODS

An electronic search was performed in the Embase and MEDLINE databases for the period between January 1, 2010, and October 1, 2022. All sectioning studies comparing the role of both the ITB and ALL on ALRI and all studies comparing the effect of both LET and ALLR were included. Articles were assessed for methodological quality according to the Quality Appraisal for Cadaveric Studies scale.

RESULTS

Data of 15 studies were included, representing the mean values of biomechanical data collected from 203 cadaveric specimens, with sample sizes ranging from 10 to 20 specimens. All 6 sectioning studies reported that the ITB acts as a secondary stabilizer to the ACL and helps resist internal knee rotation, whereas in only 2 of 6 sectioning studies the ALL contributed significantly to tibial internal rotation (IR). Most reconstruction studies reported that both a modified Lemaire tenodesis and an ALLR could significantly reduce the residual ALRI in isolated ACL-reconstructed knees and were able to restore IR stability/IR stability during the pivot shift.

CONCLUSIONS

The ITB acts as the main secondary stabilizer to the ACL in resisting IR/IR during pivot shift and an anterolateral corner (ALC) reconstruction with either a modified Lemaire tenodesis and ALLR can improve residual knee rotatory laxity in ACL reconstructed knees.

CLINICAL RELEVANCE

This systematic review provides insight in the biomechanical function of the ITB and ALL and emphasizes the importance of adding an ALC reconstruction to ACL reconstruction.

Reliability of the Tibial Spine Versus ACL Stump in Assisting Tibial Tunnel Positioning During ACL Reconstruction: Analysis Based on 3-Dimensional Computed Tomography Modeling

Background

Several techniques have been used by surgeons for anatomic tibial tunnel placement in anterior cruciate ligament (ACL) reconstruction, including the ACL stump positioning (ASP) technique and the tibial spine positioning (TSP) technique.

Purpose/Hypothesis

The purpose of this study was to evaluate whether bony landmarks (medial and lateral tibial spine [MLTS]) can be a reliable reference for improving the accuracy of tibial tunnel placement in anatomic single-bundle ACL reconstruction compared with the ACL stump. It was hypothesized that the MLTS would not be a reliable bony landmark for tibial tunnel placement.

Study Design

Cohort study; Level of evidence, 3.

Methods

The 3-dimensional computed tomography images of 111 patients who underwent ACL reconstruction between 2020 and 2021 were included in this study. For tibial tunnel placement, the ASP technique was used in 49 patients, and the TSP technique was used in 62 patients. The 3-dimensional computed tomography images were reconstructed to enable measurements of the locations of the MLTS and tunnel center based on a grid method. Statistical analysis was conducted to compare the MLTS location and tibial tunnel position as well as the accuracy (mean distance of each actual location from the anatomic center) and precision (standard deviation of the accuracy, indicating the reproducibility of the tunnel position) of the tunnel position between the ASP and TSP groups.

Results

Significant differences were observed between the ASP and TSP groups in terms of the tibial tunnel position on the mediolateral axis (46.7% ± 2.0% vs 45.9% ± 2.2%, respectively; P = .034), while no significant differences were found in terms of the accuracy (4.1% vs 4.6%, respectively; P = .259) or precision (2.1% vs 2.1%, respectively; P = .259) of tibial tunnel positioning between the 2 groups.

Conclusion

In anatomic single-bundle ACL reconstruction, the use of the MLTS for tibial tunnel placement achieved comparable accuracy and precision compared with the use of ACL remnants, supporting its role as a reliable bony landmark in tibial tunnel positioning.

Revision Rates After Primary Allograft ACL Reconstruction by Allograft Tissue Type in Older Patients

Background

While there is extensive literature on the use of allograft versus autograft in anterior cruciate ligament (ACL) reconstruction, there is limited clinical evidence to guide the surgeon in choice of allograft tissue type.

Purpose

To assess the revision rate after primary ACL reconstruction with allograft and to compare revision rates based on allograft tissue type and characteristics.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients who underwent primary allograft ACL reconstructions at a single academic institution between 2015 and 2019 and who had minimum 2-year follow-up were included. Exclusion criteria were missing surgical or allograft tissue type data. Demographics, operative details, and subsequent surgical procedures were collected. Allograft details included graft tissue type (Achilles, bone-patellar tendon-bone [BTB], tibialis anterior or posterior, semitendinosus, unspecified soft tissue), allograft category (all-soft tissue vs bone block), donor age, irradiation duration and intensity, and chemical cleansing process. Revision rates were calculated and compared by allograft characteristics.

Results

Included were 418 patients (age, 39 ± 12 years; body mass index, 30 ± 9 kg/m2). The revision rate was 3% (11/418) at a mean follow-up of 4.9 ± 1.4 years. There were no differences in revision rate according to allograft tissue type across Achilles tendon (3%; 3/95), BTB (5%; 3/58), tibialis anterior or posterior (3%; 5/162), semitendinosus (0%; 0/46), or unspecified soft tissue (0%; 0/57) (P = .35). There was no difference in revision rate between all-soft tissue versus bone block allograft (6/283 [2%] vs 5/135 [4%], respectively; P = .34). Of the 51% of grafts with irradiation data, all grafts were irradiated, with levels varying from 1.5 to 2.7 Mrad and 82% of grafts having levels of <2.0 Mrad. There was no difference in revision rate between the low-dose and medium-to high-dose irradiation cohorts (4% vs 6%, respectively; P = .64).

Conclusion

Similarly low (0%-6%) revision rates after primary ACL reconstruction were seen regardless of allograft tissue type, bone block versus all-soft tissue allograft, and sterilization technique in 418 patients with mean age of 39 years. Surgeons may consider appropriately processed allograft tissue with or without bone block when indicating ACL reconstruction in older patients.

Consistent Indications and Good Outcomes Despite High Variability in Techniques for Two-Stage Revision Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To systematically review the current literature regarding the indications, techniques, and outcomes after 2-stage revision anterior cruciate ligament reconstruction (ACLR).

METHODS

A literature search was performed using SCOPUS, PubMed, Medline, and the Cochrane Central Register for Controlled Trials according to the 2020 Preferred Reporting Items for Systematic Reviews and Meta Analyses statement. Inclusion criteria was limited to Level I-IV human studies reporting on indications, surgical techniques, imaging, and/or clinical outcomes of 2-stage revision ACLR.

RESULTS

Thirteen studies with 355 patients treated with 2-stage revision ACLR were identified. The most commonly reported indications were tunnel malposition and tunnel widening, with knee instability being the most common symptomatic indication. Tunnel diameter threshold for 2-stage reconstruction ranged from 10 to 14 mm. The most common grafts used for primary ACLR were bone-patellar tendon-bone (BPTB) autograft, hamstring graft, and LARS (polyethylene terephthalate) synthetic graft. The time elapsed from primary ACLR to the first stage surgery ranged from 1.7 years to 9.7 years, whereas the time elapsed between the first and second stage ranged from 21 weeks to 13.6 months. Six different bone grafting options were reported, with the most common being iliac crest autograft, allograft bone dowels, and allograft bone chips. During definitive reconstruction, hamstring autograft and BPTB autograft were the most commonly used grafts. Studies reporting patient-reported outcome measures showed improvement from preoperative to postoperative levels in Lysholm, Tegner, and objective International Knee and Documentation Committee scores.

CONCLUSIONS

Tunnel malpositioning and widening remain the most common indications for 2-stage revision ACLR. Bone grafting is commonly reported using iliac crest autograft and allograft bone chips and dowels, whereas hamstring autograft and BPTB autograft were the most used grafts during the second-stage definitive reconstruction. Studies showed improvements from preoperative to postoperative levels in commonly used patient reported outcomes measures.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I, III, and IV studies.

3D assessment of graft malposition after ACL reconstruction: Comparison of native and 11o'clock ligament orientations

BACKGROUND

Femoral tunnel malposition makes up the majority of technical failures for ACL reconstructive surgery. The goal of this study was to develop adolescent knee models that accurately predict anterior tibial translation when undergoing a Lachman and pivot shift test with the ACL in the 11o'clock femoral malposition (Level of Evidence: IV).

METHODS

FEBio was used to build 22 subject-specific tibiofemoral joint finite element representations. To simulate the two clinical tests, the models were subject to loading and boundary conditions established in the literature. Clinical, historical control data were used to validate the predicted anterior tibial translations.

RESULTS

A 95% confidence interval showed that with the ACL in the 11o'clock malposition, the simulated Lachman and pivot shift tests produced anterior tibial translations that were not statistically different from the in vivo data. The 11o'clock finite element knee models resulted in greater anterior displacement than those with the native (approximately 10o'clock) ACL position. The difference in anterior tibial translation between the native and 11o'clock ACL orientations was statistically significant.

CONCLUSION

Clinically, by understanding the impact that ACL orientation has in anterior tibial displacement biomechanics, surgical interventions can be improved to prevent technical errors from occurring. The integration of this methodology into surgical practice not only allows for anatomical visualization prior to surgery, but also creates the opportunity to optimize graft placement, thus improving post-surgical outcomes.

A Surgical Technique for Anterior Cruciate Ligament Reconstruction Using Semitendinosus Graft: An All-Inside Transfemoral Approach

Given the paucity of reports on all-inside reconstruction procedures via the transfemoral approach, we describe a minimally invasive, all-inside transfemoral technique that enables creating femoral and tibial sockets from the intra-articular cavity. Our transfemoral approach makes it possible to sequentially create femoral and tibial sockets using the same reamer bit, while a single drilling guide is set in place. Our custom socket drilling guide was designed to integrate with a tibial tunnel guide, which helped locate the tunnel exit at an anatomically acceptable location. The advantages of this method include easy and precise positioning of the femoral tunnel, narrow tibial tunnel, minimal damage to the intramedullary trabecular bone integrity, and low postoperative risks of pain, bleeding, and infections.

Comparison of the Clinical Outcomes of Revision and Primary ACL Reconstruction: A Matched-Pair Analysis With 3-5 Years of Follow-up

BACKGROUND

There are limited studies designed by matching related factors to compare clinical outcomes and return to sport (RTS) between patients undergoing revision anterior cruciate ligament reconstruction (R-ACLR) and primary ACLR (P-ACLR).

PURPOSE

(1) To compare the outcomes between R-ACLR and P-ACLR in a matched-pair analysis with 3- to 5-year follow-up and (2) to evaluate patient-reported factors for not returning to preinjury-level sport.

STUDY DESIGN

Cohort study; Level of evidence, 4.

METHODS

Patients who underwent R-ACLR between September 2016 and November 2018 were propensity matched by age, sex, body mass index, passive anterior tibial subluxation, and generalized hypermobility in a 1:1 ratio to patients who underwent P-ACLR during the same period. By combining in person follow-up at 2 years postoperatively and telemedicine interview at the final follow-up (January 2022), knee stability and clinical scores were compared, including International Knee Documentation Committee (IKDC), Lysholm, and Tegner. Status of RTS was requested, specifically whether the patient returned to preinjury level of sport. Patient-reported reasons for not returning were analyzed.

RESULTS

There were 63 matched pairs in the present study. Knee stability was similar in terms of KT-2000 arthrometer, Lachman test, and pivot-shift test results between the groups at 2 years of follow-up. At the final follow-up, no significant difference was found between groups for postoperative clinical scores (IKDC, Tegner, and Lysholm) (P > .05). There was a significant difference in total RTS: 53 (84.1%) in the P-ACLR cohort and 41 (65.1%) in the R-ACLR cohort (P = .014). No significant difference was shown in terms of RTS at the same level: 35 (55.6%) in P-ACLR and 31 (49.2%) in R-ACLR (P = .476). Significantly more patients showed fear of reinjury: 26 of 32 (81.3%) in the R-ACLR group as compared with 15 of 28 (53.5%) in the P-ACLR group (P < .021).

CONCLUSION

R-ACLR resulted in similar clinical scores (IKDC, Tegner, and Lysholm) but significantly lower RTS versus P-ACLR at 3 to 5 years of follow-up. Fear of reinjury was the most common factor that caused sport changes in patients with R-ACLR.

Failure modes after anterior cruciate ligament reconstruction: a systematic review and meta-analysis

PURPOSE

The reason for graft failure after anterior cruciate ligament reconstruction (ACLR) is multifactorial. Controversies remain regarding the predominant factor and incidence of failure aetiology in the literature. This review aimed to provide a meta-analysis of the literature to evaluate the relative proportion of various failure modes among patients with ACLR failure.

METHODS

The PubMed, Embase, Cochrane Library, Web of Science, and EBSCO databases were searched for literature on ACLR failure or revision from 1975 to 2021. Data related to causes for ACLR surgical failure were extracted, and a random effects model was used to pool the results, which incorporates potential heterogeneity. Failure modes were compared between different populations, research methods, graft types, femoral portal techniques, and fixation methods by subgroup analysis or linear regression. Funnel plots were used to identify publication bias and small-study effects.

RESULTS

A total of 39 studies were analyzed, including 33 cohort studies and six registry-based studies reporting 6578 failures. The results showed that among patients with ACLR failure or revision, traumatic reinjury was the most common failure mode with a rate of 40% (95% CI: 35-44%), followed by technical error (34%, 95% CI: 28-42%) and biological failure (11%, 95% CI: 7-15%). Femoral tunnel malposition was the most common cause of the technical error (29%, 95% CI: 18-41%), with more than two times higher occurrence than tibial tunnel malposition (11%, 95% CI: 6-16%). Traumatic reinjury was the most common factor for ACLR failure in European populations and in recent studies, while technical errors were more common in Asian populations, earlier studies, and surgery performed using the transtibial (TT) portal technique. Biological factors were more likely to result in ACLR failure in hamstring (HT) autografts compared to bone-patellar tendon-bone (BPTB) autografts.

CONCLUSION

Trauma is the most important factor leading to surgical failure or revision following ACLR. Technical error is also an important contributing factor, with femoral tunnel malposition being the leading cause of error resulting in failure.

The apex of the deep cartilage is a stable landmark to evaluate the femoral tunnel position in ACL reconstruction

PURPOSE

To develop a simple and effective method for evaluating the femoral tunnel position using the apex of the deep cartilage (ADC) as the landmark.

METHODS

A total of 52 patients who underwent arthroscopic ACL reconstruction were recruited between June and September 2021. The femoral tunnel was placed on the central point of the anteromedial footprint with an accessory anteromedial and a high anterolateral portal. Then, the length from the ADC to the shallow cartilage margin (L₁) and to the center of the femoral tunnel (l₁), as well as the center to the low cartilage margin (H₁, intraoperative height), was measured under arthroscopy and on postoperative CT scans (L₂, l₂ and H₂). Moreover, intraoperative and postoperative cartilage ratios were equivalent to l₁/L₁ and l₂/L₂, respectively. Linear regression, Pearson correlation and Bland-Altman analysis were performed to evaluate the consistency between these two measurements of cartilage ratio (l/L) and height (H).

RESULTS

The mean age at the time of surgery was 28.7 years; 42 patients were male, and 17 patients were hurt in the left knee among 52 patients. The intraoperative cartilage ratio was 0.37 ± 0.04, and the height was 8.1 ± 1.1 mm with almost perfect inter-observer reproducibility. After the surgery, the cartilage ratio and height were measured as 0.39 ± 0.04 and 8.2 ± 1.3 mm on 3D-CT, respectively, with almost perfect intra- and inter-observer reproducibility. Significant positive correlations and linear regression were detected in the cartilage ratio (r = 0.844, p < 0.001), and height (r = 0.926, p < 0.001) intraoperatively and postoperatively. The Bland-Altman plot also showed excellent consistency between arthroscopy and 3D-CT.

CONCLUSIONS

The ADC is a good landmark in the assessment of femoral tunnel position, with excellent consistency between intraoperative arthroscopic measurements and postoperative 3D-CT.

CLINICALTRIALS

gov Identifier: NCT04937517.

LEVEL OF EVIDENCE

Level III.

A wear model to predict damage of reconstructed ACL

Impingement with surrounding tissues is a major cause of failure of anterior cruciate ligament reconstruction. However, the complexity of the knee kinematics and anatomical variations make it difficult to predict the occurrence of contact and the extent of the resulting damage. Here we hypothesise that a description of wear between the reconstructed ligament and adjacent structures captures the in vivo damage produced with physiological loadings. To test this, we performed an in vivo study on a sheep model and investigated the role of different sources of damage: overstretching, excessive twist, excessive compression, and wear. Seven sheep underwent cranial cruciate ligament reconstruction using a tendon autograft. Necropsy observations and pull-out force measurements performed postoperatively at three months showed high variability across specimens of the extent and location of graft damage. Using 3D digital models of each stifle based on X-ray imaging and kinematics measurements, we determined the relative displacements between the graft and the surrounding bones and computed a wear index describing the work of friction forces underwent by the graft during a full flexion-extension movement. While tensile strain, angle of twist and impingement volume showed no correlation with pull-out force (ρ = -0.321, p = 0.498), the wear index showed a strong negative correlation (r = -0.902, p = 0.006). Moreover, contour maps showing the distribution of wear on the graft were consistent with the observations of damage during the necropsy. These results demonstrate that wear is a good proxy of graft damage. The proposed wear index could be used in implant design and surgery planning to minimise the risk of implant failure. Its application to sheep can provide a way to increase preclinical testing efficiency.

Etiology of Failed Anterior Cruciate Ligament Reconstruction: a Scoping Review

PURPOSE OF REVIEW

Recent literature was reviewed to identify and summarize the etiology of primary anterior cruciate ligament (ACL) reconstruction (ACLR) failure reported.

METHODS

The databases Embase, PubMed, and Medline were searched on March 10, 2022, for English-language, clinical studies that reported on the etiology of failure of primary ACLR. The studies were systematically screened in duplicate and data abstracted.

RECENT FINDINGS

Forty-three studies were identified that reported mode of failure in primary ACLR. Trauma (43 studies), technical error (11 studies), and biology (9 studies) remain the most reported etiologies of ACLR failure. A combination of causes was listed in three studies. No reported cause or "other" was listed in 22 studies. Many clinical studies fail to report etiology of ACLR failure. Level of detail provided regarding mode of failure varies widely. Trauma, technical error, and biological failure remain the leading etiologies of ACLR failure reported in recent literature. Technical error is likely underreported and a contributing factor in traumatic failures.

Meniscal Tears, Posterolateral and Posteromedial Corner Injuries, Increased Coronal Plane, and Increased Sagittal Plane Tibial Slope All Influence Anterior Cruciate Ligament-Related Knee Kinematics and Increase Forces on the Native and Reconstructed Anterior Cruciate Ligament: A Systematic Review of Cadaveric Studies

PURPOSE

To obtain a comprehensive list of pathologies that cause increased anterior cruciate ligament (ACL) forces and pathologic knee kinematics to evaluate for in both primary and revision ACL reconstruction to decrease the risk of subsequent graft overload.

METHODS

An electronic search was performed in the Embase and MEDLINE databases for the period between January 1, 1990, and December 10, 2020. All articles investigating medial and lateral meniscal injury, (postero)lateral corner injury, (postero)medial corner/medial collateral ligament injury, valgus alignment, varus alignment, and tibial slope in relation to ACL (graft) force and knee kinematics were included.

RESULTS

Data of 43 studies were included. The studies reported that high-volume medial and lateral meniscectomies, peripheral meniscus tears, medial meniscus ramp tears, lateral meniscus root tears, posterolateral corner injuries, medial collateral ligament tears, increased tibial slope, and valgus and varus alignment were reported to have a significant impact on ACL (graft) force and related knee kinematics.

CONCLUSIONS

This systematic review on biomechanical cadaver studies provides a rationale to systematically identify and treat pathologies in ACL-injured knees, because when undiagnosed or left untreated, these specific concomitant pathologies could lead to ACL graft overload in both primary and revision ACL-reconstructed knees.

CLINICAL RELEVANCE

it is necessary that orthopaedic surgeons who treat ACL-injured knees understand the surgically relevant biomechanical consequences of additional pathologies and use this knowledge to optimize treatment in ACL-injured patients.

Minimizing the risk of graft failure after anterior cruciate ligament reconstruction in athletes. A narrative review of the current evidence

Anterior cruciate ligament (ACL) tear is one of the most common sport-related injuries and the request for ACL reconstructions is increasing nowadays. Unfortunately, ACL graft failures are reported in up to 34.2% in athletes, representing a traumatic and career-threatening event. It can be convenient to understand the various risk factors for ACL failure, in order to properly inform the patients about the expected outcomes and to minimize the chance of poor results. In literature, a multitude of studies have been performed on the failure risks after ACL reconstruction, but the huge amount of data may generate much confusion.The aim of this review is to resume the data collected from literature on the risk of graft failure after ACL reconstruction in athletes, focusing on the following three key points: individuate the predisposing factors to ACL reconstruction failure, analyze surgical aspects which may have significant impact on outcomes, highlight the current criteria regarding safe return to sport after ACL reconstruction.

Ideal Combination of Anatomic Tibial and Femoral Tunnel Positions for Single-Bundle ACL Reconstruction

Background:

Anatomic anterior cruciate ligament reconstruction (ACLR) is preferred over nonanatomic ACLR. However, there is no consensus on which point the tunnels should be positioned among the broad anatomic footprints.

Purpose/Hypothesis:

To identify the ideal combination of tibial and femoral tunnel positions according to the femoral and tibial footprints of the anteromedial (AM) and posterolateral (PL) anterior cruciate ligament bundles. It was hypothesized that patients with anteromedially positioned tunnels would have better clinical scores, knee joint stability, and graft signal intensity on follow-up magnetic resonance imaging (MRI) than those with posterolaterally positioned tunnels.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 119 patients who underwent isolated single-bundle ACLR with a hamstring autograft from July 2013 to September 2018 were retrospectively investigated. Included were patients with clinical scores and knee joint stability test results at 2-year follow-up and postoperative 3-dimensional computed tomography and 1-year postoperative MRI findings. The cohort was divided into 4 groups, named according to the bundle positions in the tibial and femoral tunnels: AM-AM (n = 33), AM-PL (n = 26), PL-AM (n = 29), and PL-PL (n = 31).

Results:

There were no statistically significant differences among the 4 groups in preoperative demographic data or postoperative clinical scores (Lysholm, Tegner, and International Knee Documentation Committee subjective scores); knee joint stability (anterior drawer, Lachman, and pivot-shift tests and Telos stress radiographic measurement of the side-to-side difference in anterior tibial translation); graft signal intensity on follow-up MRI; or graft failure.

Conclusion:

No significant differences in clinical scores, knee joint stability, or graft signal intensity on follow-up MRI were identified between the patients with anteromedially and posterolaterally positioned tunnels.

Local Infiltration Analgesia Versus Femoral Nerve Block for Pain Control in Anterior Cruciate Ligament Reconstruction: A Systematic Review With Meta-analysis

Background:

Anterior cruciate ligament reconstruction (ACLR) is often performed on an outpatient basis; thus, effective pain management is essential to improving patient satisfaction and function. Local infiltration analgesia (LIA) and femoral nerve block (FNB) have been commonly used for pain management in ACLR. However, the comparative efficacy and safety between the 2 techniques remains a topic of controversy.

Purpose:

To compare pain reduction, opioid consumption, and side effects of LIA and FNB after ACLR.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

A systematic search of MEDLINE, Embase, and Cochrane Library databases was performed to identify studies comparing pain on the visual analog scale (a 100-mm scale), total morphine-equivalent consumption, and side effects between the 2 techniques after ACLR at the early postoperative period. The LIA was categorized into intra-articular injection and periarticular injection, and subgroup analyses were performed comparing either intra-articular injection or periarticular injection with FNB. Two reviewers performed study selection, risk-of-bias assessment, and data extraction.

Results:

A total of 10 studies were included in this systematic review and meta-analysis. In terms of VAS pain scores, our pooled analysis indicated that FNB was significantly more effective at 2 hours postoperatively compared with LIA (mean difference, 8.19 [95% confidence interval (CI), 0.75 to 15.63]; P = .03), with no significant difference between the 2 techniques at 4, 8, and 12 hours postoperatively; however, LIA was significantly more effective at 24 hours postoperatively compared with FNB (mean difference, 5.61 [95% CI, −10.43 to −0.79]; P = .02). Moreover, periarticular injection showed a significant improved VAS pain score compared with FNB at 24 hours postoperatively (mean difference, 11.44 [95% CI, −20.08 to −2.80]; P = .009), and the improvement reached the threshold of minimal clinically important difference of 9.9. Total morphine-equivalent consumption showed no difference between the 2 techniques, and side effects were unable to be quantified for the meta-analysis because of a lack of data.

Conclusion:

Compared with FNB, LIA was not as effective at 2 hours, comparable within 12 hours, and significantly more effective at 24 hours postoperatively for reducing pain after ACLR. Total morphine-equivalent consumption showed no significant differences between the 2 techniques.

Current and future of anterior cruciate ligament reconstruction techniques

In recent years, anterior cruciate ligament (ACL) reconstruction has generally yielded favorable outcomes. However, ACL reconstruction has not provided satisfactory results in terms of the rate of returning to sports and prevention of osteoarthritis (OA) progression. In this paper, we outline current techniques for ACL reconstruction such as graft materials, double-bundle or single-bundle reconstruction, femoral tunnel drilling, all-inside technique, graft fixation, preservation of remnant, anterolateral ligament reconstruction, ACL repair, revision surgery, treatment for ACL injury with OA and problems, and discuss expected future trends. To enable many more orthopedic surgeons to achieve excellent ACL reconstruction outcomes with less invasive surgery, further studies aimed at improving surgical techniques are warranted. Further development of biological augmentation and robotic surgery technologies for ACL reconstruction is also required.

Effect of Demineralized Bone Matrix, Bone Marrow Mesenchymal Stromal Cells, and Platelet-Rich Plasma on Bone Tunnel Healing After Anterior Cruciate Ligament Reconstruction: A Comparative Micro-Computed Tomography Study in a Tendon Allograft Sheep Model

Background:

The effect of demineralized bone matrix (DBM), bone marrow–derived mesenchymal stromal cells (BMSCs), and platelet-rich plasma (PRP) on bone tunnel healing in anterior cruciate ligament reconstruction (ACLR) has not been comparatively assessed.

Hypothesis:

These orthobiologics would reduce tunnel widening, and the effects on tunnel diameter would be correlated with tunnel wall sclerosis.

Study Design:

Controlled laboratory study.

Methods:

A total of 20 sheep underwent unilateral ACLR using tendon allograft and outside-in interference screw fixation. The animals were randomized into 4 groups (n = 5 per group): Group 1 received 4mL of DBM paste, group 2 received 10 million BMSCs in fibrin sealant, group 3 received 12 mL of activated leukocyte-poor platelet-rich plasma, and group 4 (control) received no treatment. The sheep were euthanized after 12 weeks, and micro-computed tomography scans were performed. The femoral and tibial tunnels were divided into thirds (aperture, midportion, and exit), and the trabecular bone structure, bone mineral density (BMD), and tunnel diameter were measured. Tunnel sclerosis was defined by a higher bone volume in a 250-µm volume of interest compared with a 4-mm volume of interest surrounding the tunnel.

Results:

Compared with the controls, the DBM group had a significantly higher bone volume fraction (bone volume/total volume [BV/TV]) (52.7% vs 31.8%; P = .020) and BMD (0.55 vs 0.47 g/cm³; P = .008) at the femoral aperture and significantly higher BV/TV at femoral midportion (44.2% vs 32.9%; P = .038). There were no significant differences between the PRP and BMSC groups versus controls in terms of trabecular bone analysis or BMD. In the controls, widening at the femoral tunnel aperture was significantly greater than at the midportion (46.7 vs 41.7 mm²; P = .034). Sclerosis of the tunnel was common and most often seen at the femoral aperture. In the midportion of the femoral tunnel, BV/TV (r = 0.52; P = .019) and trabecular number (r_S = 0.50; P = .024) were positively correlated with tunnel widening.

Conclusion:

Only DBM led to a significant increase in bone volume, which was seen in the femoral tunnel aperture and midportion. No treatment significantly reduced bone tunnel widening. Tunnel sclerosis in the femoral tunnel midportion was correlated significantly with tunnel widening.

Clinical Relevance:

DBM might have potential clinical use to enhance healing in the femoral tunnel after ACLR.

Editorial Commentary: Independent Femoral Tunnel Drilling Avoids Anterior Cruciate Ligament Graft Malpositioning: Advice From a Transtibial Convert

Optimal femoral anterior cruciate ligament graft placement has been extensively studied. The champions of transtibial reconstruction debate the backers of anteromedial portal and outside-in drilling. The holy grail is footprint restoration and how we best to get there. To me, creating the femur independently provides the best chance of finding that footprint by being unconstrained by the tibia. Anterior cruciate ligament surgery is challenging enough; decrease intraoperative stress and increase your likelihood of femoral footprint restoration by drilling it though the anteromedial portal.