Assessment of Anterior Cruciate Ligament Graft Maturity With Conventional Magnetic Resonance Imaging: A Systematic Literature Review

Outcomes from different aspects indicate the all-inside technique may serve as an ideal option for anterior cruciate ligament reconstruction

PURPOSE

To evaluate the postoperative outcomes of the all-inside technique in arthroscopic anterior cruciate ligament reconstruction (ACLR).

METHODS

Patients who underwent ACLR using the all-inside technique between 2018 and 2021 were retrospectively assessed. All patients were followed up for at least 2 years. Functional recovery and pain relief were assessed using the International Knee Documentation Committee (IKDC) score, Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS) and visual analogue scale (VAS). Instrumented laxity was assessed via side-to-side difference using the Kneelax3 arthrometer. Graft maturity was estimated using the signal-to-noise quotient value based on magnetic resonance imaging (MRI). Adverse events during and after the surgery were recorded.

RESULTS

A total of 78 patients were included in this study, with a mean age of 28.1 ± 7.6 years. The IKDC (p < 0.001), Lysholm (p < 0.001) and KOOS (p < 0.001 for all subgroups) scores at the final follow-up were significantly higher than those before the surgery. The VAS scores (p < 0.05) were significantly lower than those before surgery. The side-to-side difference results indicated that 50 patients had a difference of less than 3 mm, indicating a tight graft, whereas only 1 patient had a difference of >5 mm, indicating a loose graft. The median signal-to-noise quotient of the graft on MRI was 1.4 (P25, P75: 1.0, 2.0). No intraoperative adverse events were observed. Postoperative adverse events included three cases of infection, three cases of graft rerupture, two cases of cyclops lesion and one case of surgical intervention for a meniscal tear.

CONCLUSION

ACLR using the all-inside technique offers promising results in patients with ACL rupture.

LEVEL OF EVIDENCE

Level IV.

Platelet-rich plasma augmentation in anterior cruciate ligament reconstruction: Evidence is still too scattered. A scoping review of randomised controlled trials

PURPOSE

Platelet-rich plasma (PRP) augmentation has been proposed to improve the results of anterior cruciate ligament reconstruction (ACLR). The present study aims to quantify the available evidence to support the use of PRP as biological augmentation in ACLR surgery.

METHODS

A systematic literature search was conducted on the PubMed, Cochrane, Web of Science and Embase databases on 10 March 2023. Inclusion criteria were randomised controlled trials (RCTs), written in English, addressing PRP augmentation in ACLR surgery, with no time limitation. A scoping review was performed to map the body of literature by examining the evidence related to specific aspects of patients' treatment and evaluation. Risk of bias evaluation was performed with the Cochrane risk-of-bias tool for randomised trials Version 2 (RoB 2), while the quality assessment was performed with the use of the Coleman Score.

RESULTS

Out of 983 articles retrieved, 23 RCTs on 943 knees were included in this scoping review. PRP was administered in a liquid form in nine studies and clotted in 11 studies, while in three studies both liquid and clotted PRP were used. Hamstring auto/allografts were used in 14 studies, patellar tendon auto/allografts were used in eight studies and one study described ACLR with peroneus longus allografts. The map of the evidence documented high heterogeneity also in terms of surgical technique, objective and subjective outcome measures and radiological assessment, as well as follow-up times ranging from 1 day to 2 years, with virtually no overlapping data among studies neither in terms of treatments nor evaluations. Risk of bias evaluation showed an overall low quality of the included studies.

CONCLUSIONS

The available literature addressing PRP augmentation in ACLR is largely scattered. PRP was produced and applied following different procedures, and high variability was detected across the included studies for every aspect of ACLR surgery and evaluation. Currently, a meaningful comparison of the available studies is not possible as the quantification of the literature results is biased by their heterogeneity. Future studies should provide more standardisation to investigate the benefits of biological augmentation in ACL surgery and confirm the promising yet weak evidence of PRP potential as well as the most suitable application modality, before routine use in clinical practice.

LEVEL OF EVIDENCE

Levels I and II, scoping review.

Postoperative Return to Play and the Role of Imaging

Return to play (RTP) following surgery is a complex subject at the interface of social and internal pressures experienced by the athlete, psychological readiness, and intrinsic healing of the surgically repaired structures. Although functional testing, time from surgery, clinical examination, and scoring metrics can help clarify an athlete's readiness to return to sport, imaging can allow for a more direct assessment of the structures in question. Because imaging is often included in the diagnostic work-up of pain following surgery, the radiologist must be familiar with the expected postsurgical imaging appearance, as well as the associated complications. We briefly review such findings following anterior cruciate ligament reconstruction, Achilles tendon repair, syndesmotic fixation, and ulnar collateral ligament reconstruction in the context of the athlete, highlighting issues related to RTP.

Preserving the Semitendinosus Distal Attachment Is Associated With Improved Graft Remodeling After ACL Reconstruction

BACKGROUND

The semitendinosus (ST) tendon can be used by itself as a graft for anterior cruciate ligament (ACL) reconstruction. An increasing number of these procedures are being done while preserving the ST's tibial attachment, but there are no data on the remodeling of an attached ST (aST) graft.

PURPOSE

To compare graft remodeling on magnetic resonance imaging (MRI) scans at 1 year after ACL reconstruction between standard free ST graft and aST graft.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This prospective study enrolled 180 patients who were undergoing ACL reconstruction: 90 with the ST graft and 90 with the aST graft. The analysis was performed 1 year after the surgery. The main endpoint was the signal-to-noise quotient (SNQ) on MRI scans (T1-weighted sequence). The secondary endpoints were tibial tunnel widening (TTW), graft maturation (Howell classification), retear rate, new surgery rate, Simple Knee Value, Lysholm score, International Knee Documentation Committee (IKDC) score, postoperative Tegner score, difference between pre- and postoperative Tegner scores, ACL-Return to Sport after Injury (ACL-RSI), return-to-sports rate, and time to return to sports.

RESULTS

The mean adjusted SNQ was 1.18 (95% CI, 0.72-1.65) in the aST group and 3.88 (95% CI, 3.42-4.34) in the ST group (P < .001). The new surgery rate was 2.2% in the aST group and 10% in the ST group (P = .029). The median Lysholm score was significantly higher in the aST group (99; interquartile range [IQR], 95-100) than in the ST group (95; IQR, 91-99) (P = .004). The mean time to return to sports was significantly shorter in the aST group (248.73 ± 141.62 days) than the ST group (317.23 ± 144.69 days) (P = .002). No statistically significant difference was found between groups in the TTW (P = .503), Howell graft maturity grade (P = .149), retear rate (P > .999), Simple Knee Value (P = .061), postoperative Tegner score (P = .320), pre- to postoperative difference in Tegner score (P = .317), ACL-RSI (P = .097), IKDC score (P = .621), and return-to-sports rate (P > .999).

CONCLUSION

At 1 year postoperatively, remodeling of an ST graft assessed using MRI is better when its distal attachment is left intact.

Early MRI-based quantitative outcomes are associated with a positive functional performance trajectory from 6 to 24 months post-ACL surgery

PURPOSE

Quantitative magnetic resonance imaging (qMRI) has been used to determine the failure properties of ACL grafts and native ACL repairs and/or restorations. How these properties relate to future clinical, functional, and patient-reported outcomes remain unknown. The study objective was to investigate the relationship between non-contemporaneous qMRI measures and traditional outcome measures following Bridge-Enhanced ACL Restoration (BEAR). It was hypothesized that qMRI parameters at 6 months would be associated with clinical, functional, and/or patient-reported outcomes at 6 months, 24 months, and changes from 6 to 24 months post-surgery.

METHODS

Data of BEAR patients (n = 65) from a randomized control trial of BEAR versus ACL reconstruction (BEAR II Trial; NCT02664545) were utilized retrospectively for the present analysis. Images were acquired using the Constructive Interference in Steady State (CISS) sequence at 6 months post-surgery. Single-leg hop test ratios, arthrometric knee laxity values, and International Knee Documentation Committee (IKDC) subjective scores were determined at 6 and 24 months post-surgery. The associations between traditional outcomes and MRI measures of normalized signal intensity, mean cross-sectional area (CSA), volume, and estimated failure load of the healing ACL were evaluated based on bivariate correlations and multivariable regression analyses, which considered the potential effects of age, sex, and body mass index.

RESULTS

CSA (r = 0.44, p = 0.01), volume (r = 0.44, p = 0.01), and estimated failure load (r = 0.48, p = 0.01) at 6 months were predictive of the change in single-leg hop ratio from 6 to 24 months in bivariate analysis. CSA (βstandardized = 0.42, p = 0.01), volume (βstandardized = 0.42, p = 0.01), and estimated failure load (βstandardized = 0.48, p = 0.01) remained significant predictors when considering the demographic variables. No significant associations were observed between MRI variables and either knee laxity or IKDC when adjusting for demographic variables. Signal intensity was also not significant at any timepoint.

CONCLUSION

The qMRI-based measures of CSA, volume, and estimated failure load were predictive of a positive functional outcome trajectory from 6 to 24 months post-surgery. These variables measured using qMRI at 6 months post-surgery could serve as prospective markers of the functional outcome trajectory from 6 to 24 months post-surgery, aiding in rehabilitation programming and return-to-sport decisions to improve surgical outcomes and reduce the risk of reinjury.

LEVEL OF EVIDENCE

Level II.

Morphological Changes in the Tibial Tunnel After ACL Reconstruction With the Outside-In Technique and Adjustable Suspensory Fixation

Background

Anterior cruciate ligament reconstruction (ACLR) using the complete tibial tunnel technique and adjustable-loop cortical suspensory fixation is known to leave a "dead space" that holds the loop device in the tibial tunnel. The consequence of the dead space and its effect on graft healing are still uncertain.

Purpose

To investigate morphological changes in the tibial tunnel and their effect on graft healing, and to identify factors affecting bone healing in the tibial loop tunnel after ACLR with a quadrupled semitendinosus tendon autograft using adjustable suspensory fixation.

Study Design

Case series; Level of evidence, 4.

Methods

Included were 48 patients (34 male, 14 female; mean age, 25.2 ± 5.6 years) who underwent ACLR with a quadrupled semitendinosus tendon autograft using adjustable suspensory fixation. To evaluate tibial tunnel morphology, computed tomography was performed at 1 day and 6 months postoperatively. At 1 year postoperatively, graft healing was assessed on magnetic resonance imaging using the graft signal-to-noise quotient (SNQ). Multivariate regression and correlation analyses were performed to determine any associations between volumetric changes in bone healing and operative variables.

Results

At 6 months after ACLR, a mean of 63.2% of the tibial loop tunnel was filled by bone. Multivariate regression analysis showed that remnant preservation was significantly associated with the loop tunnel filling rate (P < .001). At 1 year after ACLR, the tibial loop tunnel was almost completely closed (98.5%). There were no correlations between loop tunnel volume and graft integration or graft SNQ. A significant but weak correlation was found between graft tunnel volume and intratunnel graft SNQ (P = .10) as well as integration grade in the tibial tunnel (P = .30).

Conclusion

Excellent bone filling in the tibial loop tunnel was seen at 1 year after ACLR. Remnant preservation was significantly associated with the loop tunnel filling rate. A weak correlation was found between graft tunnel volume and intratunnel graft SNQ as well as integration grade in the tibial tunnel.

Radial Extracorporeal Shock Wave Therapy Enhances Graft Maturation at 2-Year Follow-up After ACL Reconstruction: A Randomized Controlled Trial

Background

Graft maturation is an important prognostic factor for hamstring autograft anterior cruciate ligament reconstruction (ACLR). It remains unclear whether extracorporeal shock wave therapy (ESWT) can promote graft healing after ACLR.

Purpose

To evaluate the therapeutic and graft maturation effects of ESWT in hamstring autograft ACLR.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

Between May 18, 2019, and September 20, 2019, we randomly assigned 30 patients who met study inclusion criteria to 2 groups. Patients in the control group followed a 5-week advanced rehabilitation training program (30 minutes/session, 5 times/week) starting at 3 months postoperatively. In the ESWT group, together with the 5-week advanced rehabilitation training, radial ESWT was applied once a week for 5 weeks. Functional scores (Lysholm, International Knee Documentation Committee, and Tegner scores), KT-1000 arthrometer knee laxity measurement, and magnetic resonance imaging scans were assessed at 3 months (baseline), 6 months, and 24 months postoperatively. To evaluate graft maturation, we assessed the graft signal-to-noise quotients (SNQs) of the tibial, intra-articular, and femoral sides on magnetic resonance imaging scans. Data were compared between the ESWT and control groups.

Results

In total, 26 patients (13 with ESWT, 13 controls) were assessed. There were no significant between-group differences on any assessment at baseline, and no significant within-group or between-group differences were found in knee laxity at any point. At 24-month follow-up, the ESWT group had significantly higher Lysholm and Tegner scores compared with the controls (P = .012 and .017, respectively). Regarding graft maturation, at 6-month follow-up, the SNQ of the tibial intraosseous graft was significantly lower in the ESWT group versus controls (P = .006), but no differences were detected at the femoral intraosseous graft (P = .321) or the intra-articular graft (P = .314). At 24-month follow-up, the SNQs of the femoral intraosseous graft and intra-articular graft were significantly lower in the ESWT group versus controls (P = .020 and .044, respectively) but no difference was found at the tibial intraosseous graft (P = .579).

Conclusion

Both enhanced graft maturation and improved functional scores at 24-month follow-up were seen in patients who received radial ESWT during rehabilitation after hamstring autograft ACLR.

Registration

ChiCTR1900022853 (Chinese Clinical Trial Registry).

Tibial tunnel expansion does not correlate with four-strand graft maturation after ACL reconstruction using adjustable cortical suspensory fixation

PURPOSE

Anterior cruciate ligament reconstruction (ACLR) using a short, quadrupled semitendinosus (ST-4) autograft, fixed  with an adjustable suspensory fixation (ASF), has several potential advantages. However, the construct is suspected to generate micromotion, tunnel widening and poor graft maturation. The aim of this study was to evaluate post-operative tibial tunnel expansion, graft maturation and clinical outcomes for this type of ACLR.

METHODS

One-hundred and forty-nine patients were reviewed at a minimum of 2 years following 4-ST ACLR, mean 25.6 ± 3.5 months [24-55], with clinical follow-up and MRI scans. Graft maturity of the intra-articular part of the graft and the tibial tunnel portion was assessed using Signal-to-Noise Quotient (SNQ) and Howell score. Tibial tunnel expansion, bone-graft contact and graft volume in the tibial tunnel were calculated from the MRI scans.

RESULTS

Mean tibial tunnel expansion was 13 ± 16.5% [12-122]. Mean SNQ for graft within the tibial tunnel was 3.8 ± 7.1 [ - 7.7 to 39] and 2.0 ± 3.5 [ - 14 to 17] for the intra-articular portion of the graft. The Howell score for graft within the tibial tunnel was 41% Grade I, 37% Grade 2, 20% Grade 3, 2% grade 4, and for the intra-articular part 61% Grade 1, 26% Grade 2, 13% Grade 3 and 1% Grade 4. The mean tibial tunnel bone-graft contact was 81 ± 23% [0-100] and mean graft volume was 80 ± 22% [0-100]. No correlation was found between tibial tunnel expansion and graft maturity assessed at both locations. Graft maturity was correlated with higher graft-bone contact and graft volume in the tibial tunnel (p < 0.05).

CONCLUSIONS

ST-4 ACLR with ASF had low levels of tunnel enlargement at 2 years. No correlation was found between graft maturation and tibial tunnel expansion. Graft maturity was correlated with graft-bone contact and graft volume in the tibial tunnel.

LEVEL OF EVIDENCE

Level III.

Ligamentization of the reconstructed ACL differs between the intraarticular and intraosseous regions: A quantitative assessment using UTE-T2* mapping

Background

The purpose of this study was to prospectively observe the trends of ultrashort echo time (UTE)-T2* values for the intraarticular and intraosseous regions of reconstructed anterior cruciate ligaments from 6 to 12 months after anterior cruciate ligament reconstruction by using UTE-T2* mapping, and to investigate the changes and differences over time in each region.

Methods

Ten patients underwent UTE-T2* mapping of the operated knee at 6, 9, and 12 months after anterior cruciate ligament reconstruction. The UTE-T2* values of intraarticular and intraosseous regions of reconstructed anterior cruciate ligaments at 6, 9, and 12 months postoperatively were statistically compared.

Results

The UTE-T2* values of the intraarticular region at 6 months postoperatively were significantly higher than those at 9 and 12 months. There were no significant differences in the UTE-T2* values at 6, 9, and 12 months postoperatively in the intraosseous region. At 6 months postoperatively, the UTE-T2* values of the intraarticular region were significantly higher than those of the intraosseous region. The UTE-T2* values of the intraosseous region at the tibia were significantly lower than those of the other sites at any postoperative time point.

Conclusions

According to UTE-T2*mapping-based findings, histological maturation of reconstructed ACLs is faster in the intraosseous region than in the intraarticular region. In particular, the intraarticular region is still undergoing rapid histologic changes at 6 months postoperatively, and its tissue structure is less substantial than normal. The findings of this study may provide clues to determine the optimal timing for safe return to sports in terms of ligamentaization of reconstructed ACLs.

Magnetic Resonance Imaging Assessment of Hamstring Graft Healing and Integration 1 and Minimum 2 Years after ACL Reconstruction

BACKGROUND

An increase has been seen in the number of studies of anterior cruciate ligament reconstruction (ACLR) that use magnetic resonance imaging (MRI) as an outcome measure and proxy for healing and integration of the reconstruction graft. Despite this, the MRI appearance of a steady-state graft and how long it takes to achieve such an appearance have not yet been established.

PURPOSE

To establish whether a hamstring tendon autograft for ACLR changes in appearance on MRI scans between 1 and 2 years and whether this change affects a patient's ability to return to sports.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients with hamstring tendon autograft ACLR underwent MRI and clinical outcome measures at 1 year and at a final follow-up of at least 2 years. MRI graft signal was measured at multiple regions of interest using oblique reconstructions both parallel and perpendicular to the graft, with lower signal indicative of better healing and expressed as the signal intensity ratio (SIR). Changes in tunnel aperture areas were also measured. Clinical outcomes were side-to-side anterior laxity and patient-reported outcome measures (PROMs).

RESULTS

A total of 42 patients were included. At 1 year, the mean SIR for the graft was 2.7 ± 1.2. Graft SIR of the femoral aperture was significantly higher than that of the tibial aperture (3.4 ± 1.3 vs 2.6 ± 1.8, respectively; P = .022). Overall, no significant change was seen on MRI scans after 2 years; a proximal graft SIR of 1.9 provided a sensitivity of 96% to remain unchanged. However, in the 6 patients with the highest proximal graft SIR (>4) at 1 year, a significant reduction in signal was seen at final follow-up (P = .026), alongside an improvement in sporting level. A significant reduction in aperture area was also seen between 1 and 2 years (tibial, -6.3 mm², P < .001; femoral, -13.3 mm², P < .001), which was more marked in the group with proximal graft SIR >4 at 1 year and correlated with a reduction in graft signal. The patients had a high sporting level; the median Tegner activity score was 6 (range, 5-10), and a third of patients scored either 9 or 10. Overall, PROMs and knee laxity were not associated with MRI appearance.

CONCLUSION

In the majority of patients, graft SIR on MRI did not change significantly after 1 year, and a proximal graft SIR <2 was a sensitive indicator for a stable graft signal, implying healing. Monitoring is proposed for patients who have a high signal at 1 year (proximal graft SIR >4), because a significant reduction in signal was seen in the second year, indicative of ongoing healing, alongside an improvement in sporting level. A reduction in tunnel aperture area correlated with a reduction in graft SIR, suggesting this could also be a useful measure of graft integration.

Tibial slope, remnant preservation, and graft size are the most important factors affecting graft healing after ACL reconstruction

PURPOSE

The aim of this study was to determine the anatomic, operative and biological factors that influenced graft healing after single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

One hundred fourteen consecutive patients who underwent anatomic single-bundle ACL reconstruction with quadrupled hamstring tendon autografts between 2016 and 2019 were retrospectively analyzed. Ninety-four patients met the inclusion criteria with minimum follow-up of 12 months. Patients were evaluated with multiple clinical measurements, including International Knee Documentation Committee Subjective Knee Form (IKDC-SKF), Lyshom Scores, and Marx activity scale. To evaluate graft healing, the signal-to-noise quotient (SNQ) was measured at intra-articular graft and intra-tunnel integration were evaluated on magnetic resonance imaging (MRI) at one year after surgery. Potential factors affecting graft healing, including age, sex, body mass index, time from injury to surgery, posterior tibial slope, lateral femoral condyle ratio, notch width index, meniscal injury, remnant preservation, tunnel aperture locations, graft size, graft bending angle, graft/remaining notch volume ratio were evaluated for their association with graft SNQ value by stepwise regression analysis.

RESULTS

A total of 94 patients were evaluated with mean follow-up 28.5 ± 9 months. Univariate regression analysis showed that posterior tibial slope, notch width index, remnant preserving procedure, high femoral tunnel, anterior tibial tunnel, graft bending angle, and graft/remaining notch volume ratio significantly associated with graft SNQ values. Multivariate regression analysis showed that lateral tibial slope, remnant preservation, and graft/remaining notch volume ratio were independent factors correlated with graft SNQ values. Also, the graft SNQ values was weakly correlated with femoral tunnel integration and Marx activity scale at one year. There was no correlation between graft SNQ values and IKDC-SKF and Lysholm scores. There was no correlation between graft SNQ values and International Knee Documentation Committee and Lysholm scores.

CONCLUSIONS

Tibial slope, remnant preservation and graft/remaining notch volume ratio were significant independent associated factors of graft SNQ value at one year. The graft SNQ values were also weakly correlated with femoral tunnel integration and the Marx activity scale. These factors should be taken into account for ensuring the ideal graft healing and for the return to sport decision-making.

LEVEL OF EVIDENCE

Level IV.

Vancomycin Presoaking of Hamstring Autografts in Anterior Cruciate Ligament Reconstruction Is Associated With Higher Magnetic Resonance Imaging Graft Signal Without Influencing Clinical Outcome

PURPOSE

To present the clinical and imaging results of a series of patients undergoing anterior cruciate ligament reconstruction with vancomycin presoaking of the hamstring autograft compared with patients in the immediate period prior, when no vancomycin was used.

METHODS

This was a retrospective sequential series of patients with anterior cruciate ligament reconstruction using either a graft protocol with no vancomycin presoaking (group 1, January 2013 to October 2015) or a graft protocol with vancomycin presoaking (group 2, November 2015 to December 2018). Lysholm and International Knee Documentation Committee scores were obtained at a minimum 24-month follow-up. Graft ruptures were recorded. Between 6 and 12 months' follow-up, magnetic resonance imaging (MRI) was obtained to evaluate graft healing and integration.

RESULTS

There were 102 patients (72% male patients), with 40 in group 1 (mean age, 32.2 years) and 62 in group 2 (mean age, 32.3 years). A graft rupture occurred in 5 patients (13%) in group 1 and 6 patients (10%) in group 2 (P = .65). The median Lysholm score was 95 points (interquartile range [IQR], 86-100 points) in group 1 and 95 points (IQR, 90-100 points) in group 2 (P = .37). The median International Knee Documentation Committee score was 93 points (IQR, 82-99 points) in group 1 and 94 points (IQR, 86-99 points) in group 2 (P = .22). MRI evaluation of integration showed that 87 patients (90%) had no synovial fluid at the tunnel-graft interface, without a difference between groups (P = .24). On the basis of graft signal appearance, hyperintense grafts were found in 45 patients (46%); isointense, 45 (46%); and hypointense, 7 (7%). Group 1 had a higher prevalence of hypointense grafts, whereas group 2 had a higher prevalence of hyperintense and isointense grafts (P = .003).

CONCLUSIONS

Vancomycin presoaking of hamstring grafts increased the number of hyperintense and isointense grafts on MRI. Additionally, more hypointense grafts were noted when vancomycin was not used, suggesting the presence of more mature grafts in the non-vancomycin group.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Randomized controlled trial of all-inside and standard single-bundle anterior cruciate ligament reconstruction with functional, MRI-based graft maturity and patient-reported outcome measures

Background

All-inside anterior cruciate ligament reconstruction (ACLR) is a novel technique that has gained attention due to its minimally invasive and graft-saving properties. However, studies comparing MRI-based graft maturity between all-inside and standard ACLR are lacking.

Purpose

This study focused on the functional, knee laxity, and MRI-based graft maturity characteristics of all-inside and standard single-bundle ACLR.

Study Design

Randomized controlled trial (RCT).

Methods

Fifty-four patients were randomly assigned to an all-inside reconstruction group (n = 27) or standard reconstruction group (n = 27). Using the same rehabilitation strategy. The Tegner, International Knee Documentation Committee, and Lysholm scores were recorded at postoperative months 3, 6, and 12 to assess functional recovery. MRI was conducted to measure the signal/noise quotient (SNQ) of the intra-articular graft to assess the maturity. A higher SNQ indicates lower graft maturity. Knee laxity was assessed using GNRB arthrometer at the postoperative month 12.

Results

The graft SNQ of the all-inside group was significantly higher than that of the standard group at postoperative month 6 (p < 0.05). There was no statistical difference in graft SNQ between the two groups at postoperative months 3 and 12 (p > 0.05). Both groups exhibited the highest SNQ in the middle region of the graft, followed by the proximal region, and the distal region. Functional scores improved significantly for both groups and had no statistical difference (p > 0.05). The knee laxity was higher in the all-inside group (p < 0.05) at postoperative month 12. There was no correlation between the functional scores and graft maturity in both groups (p > 0.05).

Conclusions

All-inside and standard single-bundle ACLR show good functional outcomes; however, knee laxity was relatively higher in the all-inside ACLR group than in the standard ACLR group. Moreover, both techniques exhibited poor maturity in the middle graft region and the best in the distal region. Graft maturity with all-inside ACLR is inferior to that with standard ACLR in the early postoperative stages. There is no correlation between knee function and graft maturity.

Trial registration

Clinical trial registration numbers: ChiCTR1800018543.

Date of registration: 09/23/2018.

ACL Size, but Not Signal Intensity, Is Influenced by Sex, Body Size, and Knee Anatomy

Background:

Little is known about sex-based differences in anterior cruciate ligament (ACL) tissue quality in vivo or the association of ACL size (ie, volume) and tissue quality (ie, normalized signal intensity on magnetic resonance imaging [MRI]) with knee anatomy.

Hypothesis:

We hypothesized that (1) women have smaller ACLs and greater ACL normalized signal intensity compared with men, and (2) ACL size and normalized signal intensity are associated with age, activity levels, body mass index (BMI), bicondylar width, intercondylar notch width, and posterior slope of the lateral tibial plateau.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Knee MRI scans of 108 unique ACL-intact knees (19.7 ± 5.5 years, 62 women) were used to quantify the ACL signal intensity (normalized to cortical bone), ligament volume, mean cross-sectional area, and length. Independent t tests were used to compare the MRI-based ACL parameters between sexes. Univariate and multivariate linear regression analyses were used to investigate the associations between normalized signal intensity and size with age, activity levels, BMI, bicondylar width, notch width, and posterior slope of the lateral tibial plateau.

Results:

Compared with men, women had significantly smaller mean ACL volume (men vs women: 2028 ± 472 vs 1591 ± 405 mm³), cross-sectional area (49.4 ± 9.6 vs 41.5 ± 8.6 mm²), and length (40.8 ± 2.8 vs 38.1 ± 3.1 mm) (P < .001 for all), even after adjusting for BMI and bicondylar width. There was no difference in MRI signal intensity between men and women (1.15 ± 0.24 vs 1.12 ± 0.24, respectively; P = .555). BMI, bicondylar width, and intercondylar notch width were independently associated with a larger ACL (R² > 0.16, P < .001). Younger age and steeper lateral tibial slope were independently associated with shorter ACL length (R² > 0.03, P < .04). The combination of BMI and bicondylar width was predictive of ACL volume and mean cross-sectional area (R² < 0.3). The combination of BMI, bicondylar width, and lateral tibial slope was predictive of ACL length (R² = 0.39). Neither quantified patient characteristics nor anatomic variables were associated with signal intensity.

Conclusion:

Men had larger ACLs compared with women even after adjusting for BMI and knee size (bicondylar width). No sex difference was observed in signal intensity, suggesting no difference in tissue quality. The association of the intercondylar notch width and lateral tibial slope with ACL size suggests that the influence of these anatomic features on ACL injury risk may be partially explained by their effect on ACL size.

Registration:

NCT02292004 and NCT02664545 (ClinicalTrials.gov identifier).

Can we afford to ignore the biology of joint healing and graft incorporation after ACL reconstruction?

Anterior cruciate ligament (ACL) reconstruction is successful at restoring stability to return ACL injured patients to high-demand work, sports, and recreational activities. The development of posttraumatic osteoarthritis (OA) in roughly half of patients just 10-15 years after ACLR highlight the need to improve clinical care pathways. Graft failure and reinjury rates, which further increase OA risk, also remain high for younger and more active patients. The biological components of joint recovery and graft incorporation, therefore, impact short- and long-term clinical outcomes. Biochemical and magnetic resonance imaging (MRI) data show substantial compromise of articular cartilage metabolism and matrix composition after ACL injury and reconstructive surgery suggesting a potential need for activity modulation in early recovery. Furthermore, joint recovery is variable with compositional MRI studies showing progressive cartilage degeneration 1 and 2 years after ACLR. Biopsy and MRI studies also show high variability in ACL graft characteristics within the 1st year after ACLR followed by continued graft maturation into the 2nd year and beyond. To improve the care of ACL injured patients, there is a critical need for clinical attention and scientific inquiry into timing the reintroduction of higher load activities in relationship to neuromuscular recovery, joint biology, and graft maturation. In addition to symptomatic and mechanical recovery, development and validation of biological markers for joint and cartilage homeostasis as well as ACL graft healing are needed for personalized decision making on rehabilitation needs, reduction of OA risk, and resumption of athletic, recreational, and vocational activities.

Different timing in allograft and autograft maturation after primary anterior cruciate ligament reconstruction does not influence the clinical outcome at mid-long-term follow-up

PURPOSE

The use of allografts in primary anterior cruciate ligament reconstruction (ACLR) is increasing although they are still supposed to be associated to greater risk of re-rupture due to a slower and less efficient graft maturation. The aim of this prospective randomized controlled study was to compare the graft maturation after ACLR with allograft and autograft by MRI at 6- and 12-month follow-up and integrate these data with the functional and clinical results observed at 6-, 12- and 60-month follow-up.

METHODS

Fifty patients with indication to primary ACLR were randomly and equally divided into hamstring autograft or allograft tendon groups. The graft maturation was measured at 6- and 12-month follow-up by the SNQ score and other radiological parameters on MRI scans. Clinical and functional recovery was evaluated by Lysholm score, Visual Analogues Scale, Tegner activity scale and modified Cincinnati knee rating system at 6, 12 and 60 months after surgery to estimate the predictive value of the radiological parameters for clinical outcomes. Return-to-sport (ACL-RSI) was measured 60 months after surgery.

RESULTS

Three patients had retear of the neo-ligament (two from Auto group and one from Allo group). All the clinical/functional parameters significantly improved over time, with no statistically significant difference between the groups. At 6 months, the SNQ value was significantly higher in the Auto than in the Allo group (12.9 vs 7.9, p = 0.038), but at 12 months they were comparable (9.8 vs 10.4). The 6-month SNQ values did not correlate with the clinical scores, whereas the 12-month SNQ values significantly correlated with the Cincinnati score, Lysholm score and Tegner activity scale collected at 60-month follow-up.

CONCLUSION

No clinical or functional differences have been found between the two treatment groups, supporting the suitability of using allograft in primary ACLR, when available. The results at MRI scans showed a different graft maturation trend in the two groups, with allografts being more reactive in the first 6 months. MRI together with the subjective evaluation allows to evaluate objectively the status of the neo-ligamentization process and therefore helps the surgeon to dictate the individual time for return-to-sport.

LEVEL OF EVIDENCE

Level I.

Anterior cruciate ligament autograft maturation on sequential postoperative MRI is not correlated with clinical outcome and anterior knee stability

PURPOSE

Magnetic resonance imaging (MRI) signal intensity is correlated to structural postoperative changes of the anterior cruciate ligament (ACL) autograft. The purpose of this study was to investigate the ACL autograft maturation process via MRI over 2 years postoperatively, compare it to a native ACL signal and correlate the results with clinical outcome, return to preinjury sports levels, and knee laxity measurements.

METHODS

ACL autograft signal intensity was measured in 17 male patients (age, 28.3 ± 7.0 years) who underwent ACL reconstruction with hamstring autograft at 6 weeks, 3-, 6-, 12-, and 24 months postoperatively by 3 Tesla MRI. Controls with an intact ACL served as control group (22 males, 8 females; age, 26.7 ± 6.8 years). An ACL/PCL ratio (APR) and ACL/muscle ratio (AMR) was calculated to normalize signals to soft tissue signal. APR and AMR were compared across time and to native ACL signal. Clinical outcome scores (IKDC, Lysholm), return to preinjury sports levels (Tegner activity scale), and knee laxity measurement (KT-1000) were obtained and correlated to APR and AMR at the respective time points.

RESULTS

The APR and AMR of the ACL graft changed significantly from the lowest values at 6 weeks to reach the highest intensity after 6 months (p < 0.001). Then, the APR and AMR were significantly different from a native ACL 6 months after surgery (p < 0.01) but approached the APR and AMR of the native ACL at 1- and 2 years after surgery (p < 0.05). The APR changed significantly during the first 2 years postoperatively in the proximal (p < 0.001), mid-substance (p < 0.001), and distal (p < 0.01) intraarticular portion of the ACL autograft. A hypo-intense ACL MRI signal was associated with return to the preinjury sports level (p < 0.05). No correlation was found between ACL MRI graft signal and clinical outcome scores or KT-1000 measurements.

CONCLUSION

ACL grafts undergo a continuous maturation process in the first 2 years after surgery. The ACL graft signals became hyper-intense 6 months postoperatively and approximated the signal of a native intact ACL at 12- and 24 months. Patients with a hypo-intense ACL graft signal at 2 years follow-up were more likely to return to preinjury sports levels. The results of the present study provide a template for monitoring the normal ACL maturation process via MRI in case of prolonged clinical symptoms. However, subjective outcome and clinical examination of knee laxity remain important to assess the treatment success and to allow to return to sports.

LEVEL OF EVIDENCE

III.

Regional Differences in Anterior Cruciate Ligament Signal Intensity After Surgical Treatment

BACKGROUND

Magnetic resonance-based measurements of signal intensity have been used to track healing of surgically treated anterior cruciate ligaments (ACLs). However, it is unknown how the signal intensity values in different regions of the ligament or graft change during healing.

HYPOTHESES

(1) Normalized signal intensity of the healing graft or repaired ACL is heterogeneous; (2) temporal changes in normalized signal intensity values differ among the tibial, middle, and femoral regions; and (3) there are no differences in regional normalized signal intensity values 2 years postoperatively among grafts, repaired ACLs, and contralateral native ACLs.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Magnetic resonance imaging scans were analyzed from patients in a trial comparing ACL reconstruction (n = 35) with bridge-enhanced ACL repair (n = 65). The ACLs were segmented from images acquired at 6, 12, and 24 months postoperatively and were partitioned into 3 sections along the longitudinal axis (femoral, middle, and tibial). Linear mixed modeling was used to compare location-specific differences in normalized ligament signal intensity among time points (6, 12, and 24 months) and groups (ACL reconstruction, repair, and contralateral native ACL).

RESULTS

For grafts, the middle region had a higher mean normalized signal intensity when compared with the femoral region at all time points (P < .01) but compared with the tibial region only at 6 months (P < .01). For repaired ACLs, the middle region had a higher mean normalized signal intensity versus the femoral region at all time points (P < .01) but versus the tibial region only at 6 and 12 months (P < .04). From 6 to 24 months, the grafts showed the greatest reduction in normalized signal intensity in the femoral and middle regions (vs tibial regions; P < .01), while there were no regional differences in repaired ACLs. At 2 years after surgery, repaired ACLs had a lower normalized signal intensity in the tibial region as compared with reconstructed grafts and contralateral native ACLs (P < .01).

CONCLUSION

The results suggest that graft remodeling is location specific. Repaired ACLs were more homogeneous, with lower or comparable normalized signal intensity values at 2 years as compared with the contralateral native ACL and reconstructed grafts.

Two-year postoperative MRI appearances of anterior cruciate ligament hamstrings autografts are not correlated with functional outcomes, anterior laxity, or patient age

Aims

MRI has been suggested as an objective method of assessing anterior crucate ligament (ACL) graft “ligamentization” after reconstruction. It has been proposed that the MRI appearances could be used as an indicator of graft maturity and used as part of a return-to-sport assessment. The aim of this study was to evaluate the correlation between MRI graft signal and postoperative functional scores, anterior knee laxity, and patient age at operation.

Methods

A consecutive cohort of 149 patients who had undergone semitendinosus autograft ACL reconstruction, using femoral and tibial adjustable loop fixations, were evaluated retrospectively postoperatively at two years. All underwent MRI analysis of the ACL graft, performed using signal-to-noise quotient (SNQ) and the Howell score. Functional outcome scores (Lysholm, Tegner, International Knee Documentation Committee (IKDC) subjective, and IKDC objective) were obtained and all patients underwent instrumented side-to-side anterior laxity differential laxity testing.

Results

Two-year postoperative mean outcome scores were: Tegner 6.5 (2 to 10); Lysholm 89.8 (SD 10.4; 52 to 100); and IKDC subjective 86.8 (SD 11.8; 51 to 100). The objective IKDC score was 86% A (128 patients), 13% B (19 patients), and 1% C (two patients). Mean side-to-side anterior laxity difference (134 N force) was 0.6 mm (SD 1.8; -4.1 to 5.6). Mean graft SNQ was 2.0 (SD 3.5; -14 to 17). Graft Howell scores were I (61%, 91 patients), II (25%, 37 patients), III (13%, 19 patients), and IV (1%, two patients). There was no correlation between either Howell score or SNQ with instrumented anterior or Lysholm, Tegner, and IKDC scores, nor was any correlation found between patient age and ACL graft SNQ or Howell score.

Conclusion

The two-year postoperative MRI appearances of four-strand, semitendinosus ACL autografts (as measured by SNQ and Howell score) do not appear to have a relationship with postoperative functional scores, instrumented anterior laxity, or patient age at surgery. Other tools for analysis of graft maturity should be developed.

Cite this article: Bone Jt Open 2021;2(8):569–575.

Artificial Intelligence in the Management of Anterior Cruciate Ligament Injuries

Background:

Technological innovation is a key component of orthopaedic surgery. With the integration of powerful technologies in surgery and clinical practice, artificial intelligence (AI) may become an important tool for orthopaedic surgeons in the future. Through adaptive learning and problem solving that serve to constantly increase accuracy, machine learning algorithms show great promise in orthopaedics.

Purpose:

To investigate the current and potential uses of AI in the management of anterior cruciate ligament (ACL) injury.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

A systematic review of the PubMed, MEDLINE, Embase, Web of Science, and SPORTDiscus databases between their start and August 12, 2020, was performed by 2 independent reviewers. Inclusion criteria included application of AI anywhere along the spectrum of predicting, diagnosing, and managing ACL injuries. Exclusion criteria included non-English publications, conference abstracts, review articles, and meta-analyses. Statistical analysis could not be performed because of data heterogeneity; therefore, a descriptive analysis was undertaken.

Results:

A total of 19 publications were included after screening. Applications were divided based on the different stages of the clinical course in ACL injury: prediction (n = 2), diagnosis (n = 12), intraoperative application (n = 1), and postoperative care and rehabilitation (n = 4). AI-based technologies were used in a wide variety of applications, including image interpretation, automated chart review, assistance in the physical examination via optical tracking using infrared cameras or electromagnetic sensors, generation of predictive models, and optimization of postoperative care and rehabilitation.

Conclusion:

There is an increasing interest in AI among orthopaedic surgeons, as reflected by the applications for ACL injury presented in this review. Although some studies showed similar or better outcomes using AI compared with traditional techniques, many challenges need to be addressed before this technology is ready for widespread use.

MRI following medial patellofemoral ligament reconstruction: assessment of imaging features found with post-operative pain, arthritis, and graft failure

OBJECTIVE

To assess MR features following MPFL reconstruction and determine their influence on post-operative pain, progressive arthritis, or graft failure.

MATERIALS AND METHODS

Retrospective study on 38 patients with MPFL reconstruction and a post-operative MRI between January 2010 and June 2019. Two radiologists assessed MPFL graft signal, graft thickness, femoral screw, femoral tunnel widening, and patellofemoral cartilage damage. The third performed patellofemoral instability measurements. All three assessed femoral tunnel position with final result determined by majority consensus. Imaging findings were evaluated in the setting of post-operative pain, patellofemoral arthritis, and MPFL graft failure including need for MPFL revision. Statistics included chi-square, Fisher's exact test, t test, and kappa.

RESULTS

Mean graft thickness was 6.0 ± 1.8 mm; 24% of the grafts were diffusely hypointense. Mean femoral tunnel widening was 2.5 ± 1.8 mm; 34% of the femoral screws were broken or extruded. Fifty-two percent of the patients had no interval cartilage change. Non-anatomic femoral tunnels were found in 66% of patients, including in all 9 patients requiring revision MPFL reconstruction (p = 0.013). Revised MPFL grafts had more abnormal femoral screws compared to those that did not (67% vs. 24%) (p = 0.019). Other MR features did not significantly influence the evaluated outcomes.

CONCLUSION

The need for revision MPFL reconstruction occurs more frequently when there is a non-anatomic femoral tunnel and broken or extruded femoral screws. The appearance of the MPFL graft itself is not an influencing factor for post-operative pain, progression of patellofemoral arthritis, or graft failure.

Magnetic Resonance Imaging 1 Year After Hamstring Autograft Anterior Cruciate Ligament Reconstruction Can Identify Those at Higher Risk of Graft Failure: An Analysis of 250 Cases

BACKGROUND

There is currently no analysis of 1-year postoperative magnetic resonance imaging (MRI) that reproducibly evaluates the graft of a hamstring autograft anterior cruciate ligament reconstruction (ACLR) and helps to identify who is at a higher risk of graft rupture upon return to pivoting sports.

PURPOSE

To ascertain whether a novel MRI analysis of ACLR at 1 year postoperatively can be used to predict graft rupture, sporting level, and clinical outcome at a 1-year and minimum 2-year follow-up.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Graft healing and integration after hamstring autograft ACLR were evaluated using the MRI signal intensity ratio at multiple areas using oblique reconstructions both parallel and perpendicular to the graft and tunnel apertures. Clinical outcomes were assessment of side-to-side laxity and International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Lysholm, and Tegner activity level scores at 1 year. Repeat outcome measures and detection of graft rupture were evaluated at a minimum of 2 years.

RESULTS

A total of 250 patients (42.4% female) underwent MRI analysis at 1 year, and assessment of 211 patients between 1 year and the final follow-up (range, 24-36 months) detected 9 graft ruptures (4.3%; 5 in female patients). A significant predictor for graft rupture was a high signal parallel to the proximal intra-articular graft and perpendicular to the femoral tunnel aperture (P = .032 and P = .049, respectively), with each proximal graft signal intensity ratio (SIR) increase by 1 corresponding to a 40% increased risk of graft rupture. A cutoff SIR of 4 had a sensitivity and specificity of 66% and 77%, respectively, in the proximal graft and 88% and 60% in the femoral aperture. In all patients, graft signal adjacent to and within the tibial tunnel aperture, and in the mid intra-articular portion, was significantly lower than that for the femoral aperture (P < .001). A significant correlation was seen between the appearance of higher graft signal on MRI and those patients achieving top sporting levels by 1 year.

CONCLUSION

ACLR graft rupture after 1 year is associated with MRI appearances of high graft signal adjacent to and within the femoral tunnel aperture. Patients with aspirations of quickly returning to a high sporting level may benefit from MRI analysis of graft signal. Graft signal was highest at the femoral tunnel aperture, adding further radiographic evidence that the rate-limiting step to graft healing occurs proximally.

Hamstring grafts for anterior cruciate ligament reconstruction show better magnetic resonance features when tibial insertion is preserved

PURPOSE

Comparing the MRI features of the grafts between a group of patients treated with an over-the-top anterior cruciate ligament reconstruction technique that preserves the hamstring attachment and a control group with a classical reconstruction technique.

METHODS

Patients were assigned to a standard reconstruction technique or an Over-the-top plus lateral plasty technique. All patients underwent preoperative, 4-months and 18-months MRI; together with a clinical evaluation with KOOS and KT1000 laxity assessment. MRI study involved different parameters: the "Graft" was evaluated with the continuity, Howell Grading system, presence of liquid and signal noise quotient. The "Tibial Tunnel" was evaluated with the signal noise quotient, presence of edema or liquid and tunnel widening. All points assigned to each parameter formed a composite score ranging from 0-10. Tunnel and graft positioning were evaluated.

RESULTS

At 18-month 20 MRIs (10 each group) were available, demographics were not significantly different between groups. The non-detached group showed significantly less liquid within the graft at 4-months (p = 0.008) and 18-months (p = 0.028), the tunnel was significantly smaller (p < 0.05) and less enlarged at both follow-ups (p < 0.05), signal noise quotient of the intra-tunnel graft was lower at 18-months (p < 0.05). The total score of the non-detached group saw a significant improvement at 4-months (p = 0.006) that remained stable at 18-months (n.s.).

CONCLUSIONS

Hamstring grafts, which tibial insertions were preserved, showed better MRI features at 4-and 18-months follow-up, especially in terms of liquid effusion, tunnel enlargement and signal noise quotient.

LEVEL OF EVIDENCE

IV.

Mesenchymal stromal cells and platelet-rich plasma promote tendon allograft healing in ovine anterior cruciate ligament reconstruction

PURPOSE

The effect of bone marrow mesenchymal stromal cells (BMSCs) and platelet-rich plasma (PRP) on tendon allograft maturation in a large animal anterior cruciate ligament (ACL) reconstruction model was reported for the first time. It was hypothesised that compared with non-augmented ACL reconstruction, BMSCs and PRP would enhance graft maturation after 12 weeks and this would be detected using magnetic resonance imaging (MRI).

METHODS

Fifteen sheep underwent unilateral tendon allograft ACL reconstruction using aperture fixation and were randomised into three groups (n = 5). Group 1 received 10 million allogeneic BMSCs in 2 ml fibrin sealant; Group 2 received 12 ml PRP in a plasma clot injected into the graft and bone tunnels; and Group 3 (control) received no adjunctive treatment. At autopsy at 12 weeks, a graft maturation score was determined by the sum for graft integrity, synovial coverage and vascularisation, graft thickness and apparent tension, and synovial sealing at tunnel apertures. MRI analysis (n = 2 animals per group) of the signal-noise quotient (SNQ) and fibrous interzone (FIZ) was used to evaluate intra-articular graft maturation and tendon-bone healing, respectively. Spearman's rank correlation coefficient (r) of SNQ, autopsy graft maturation score and bone tunnel diameter were analysed.

RESULTS

The BMSC group (p = 0.01) and PRP group (p = 0.03) had a significantly higher graft maturation score compared with the control group. The BMSC group scored significantly higher for synovial sealing at tunnel apertures (p = 0.03) compared with the control group. The graft maturation score at autopsy significantly correlated with the SNQ (r = - 0.83, p < 0.01). The tunnel diameter of the femoral tunnel at the aperture (r = 0.883, p = 0.03) and mid-portion (r = 0.941, p = 0.02) positively correlated with the SNQ.

CONCLUSIONS

BMSCs and PRP significantly enhanced graft maturation, which indicates that orthobiologics can accelerate the biologic events in tendon allograft incorporation. Femoral tunnel expansion significantly correlated with inferior maturation of the intra-articular graft. The clinical relevance of this study is that BMSCs and PRP enhance allograft healing in a translational model, and biological modulation of graft healing can be evaluated non-invasively using MRI.

Quantitative Assessment of In Vivo Human Anterior Cruciate Ligament Autograft Remodeling: A 3-Dimensional UTE-T2* Imaging Study

BACKGROUND

The timing of return to play after anterior cruciate ligament (ACL) reconstruction is still controversial due to uncertainty of true ACL graft state at the time of RTP. Recent work utilizing ultra-short echo T2* (UTE-T2*) magnetic resonance imaging (MRI) as a scanner-independent method to objectively and non-invasively assess the status of in vivo ACL graft remodeling has produced promising results.

PURPOSE/HYPOTHESIS

The purpose of this study was to prospectively and noninvasively investigate longitudinal changes in T2* within ACL autografts at incremental time points up to 12 months after primary ACL reconstruction in human patients. We hypothesized that (1) T2* would increase from baseline and initially exceed that of the intact contralateral ACL, followed by a gradual decline as the graft undergoes remodeling, and (2) remodeling would occur in a region-dependent manner.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twelve patients (age range, 14-45 years) who underwent primary ACL reconstruction with semitendinosus tendon or bone-patellar tendon-bone autograft (with or without meniscal repair) were enrolled. Patients with a history of previous injury or surgery to either knee were excluded. Patients returned for UTE MRI at 1, 3, 6, 9, and 12 months after ACL reconstruction. Imaging at 1 month included the contralateral knee. MRI pulse sequences included high-resolution 3-dimensional gradient echo sequence and a 4-echo T2-UTE sequence (slice thickness, 1 mm; repetition time, 20 ms; echo time, 0.3, 3.3, 6.3, and 9.3 ms). All slices containing the intra-articular ACL were segmented from high-resolution sequences to generate volumetric regions of interest (ROIs). ROIs were divided into proximal/distal and core/peripheral sub-ROIs using standardized methods, followed by voxel-to-voxel registration to generate T2* maps at each time point. This process was repeated by a second reviewer for interobserver reliability. Statistical differences in mean T2* values and mean ratios of T2*_inj/T2*_intact (ie, injured knee to intact knee) among the ROIs and sub-ROIs were assessed using repeated measures and one-way analyses of variance. P < .05 represented statistical significance.

RESULTS

Twelve patients enrolled in this prospective study, 2 withdrew, and ultimately 10 patients were included in the analysis (n = 7, semitendinosus tendon; n = 3, bone-patellar tendon-bone). Interobserver reliability for T2* values was good to excellent (intraclass correlation coefficient, 0.84; 95% CI, 0.59-0.94; P < .001). T2* values increased from 5.5 ± 2.1 ms (mean ± SD) at 1 month to 10.0 ± 2.9 ms at 6 months (P = .001), followed by a decline to 8.1 ± 2.0 ms at 12 months (P = .129, vs 1 month; P = .094, vs 6 months). Similarly, mean T2*_inj/T2*_intact ratios increased from 62.8% ± 22.9% at 1 month to 111.1% ± 23.9% at 6 months (P = .001), followed by a decline to 92.8% ± 29.8% at 12 months (P = .110, vs 1 month; P = .086, vs 6 months). Sub-ROIs exhibited similar increases in T2* until reaching a peak at 6 months, followed by a gradual decline until the 12-month time point. There were no statistically significant differences among the sub-ROIs (P > .05).

CONCLUSION

In this preliminary study, T2* values for ACL autografts exhibited a statistically significant increase of 82% between 1 and 6 months, followed by an approximate 19% decline in T2* values between 6 and 12 months. In the future, UTE-T2* MRI may provide unique insights into the condition of remodeling ACL grafts and may improve our ability to noninvasively assess graft maturity before return to play.

Assessment of Graft Maturity After Anterior Cruciate Ligament Reconstruction Using Autografts: A Systematic Review of Biopsy and Magnetic Resonance Imaging studies

Purpose

The purpose of this investigation was to evaluate systematically the literature concerning biopsy, MRI signal to noise quotient (SNQ) and clinical outcomes in graft-maturity assessment after autograft anterior cruciate ligament reconstruction (ACLR) and their possible relationships.

Methods

The systematic review was reported and conducted according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Studies through May 2019 evaluating methods of intra-articular ACL autograft maturity assessment were considered for inclusion. Eligible methods were histologic studies of biopsy specimens and conventional MRI studies reporting serial SNQ and/or correlation with clinical parameters.

Results

Ten biopsy studies and 13 imaging studies, with a total of 706 patients, met the inclusion criteria. Biopsy studies show that graft remodeling undergoes an early healing phase, a phase of remodeling or proliferation and a ligamentization phase as an ongoing process even 1 year after surgery. Imaging studies showed an initial increase in SNQ, peaking at approximately 6 months, followed by a gradual decrease over time. There is no evident correlation between graft SNQ and knee stability outcome scores at the short- and long-term follow-up after ACLR.

Conclusions

The remodeling of the graft is an ongoing process even 1 year after ACLR, based on human biopsy studies. MRI SNQ peaked at approximately 6 months, followed by a gradual decrease over time. Heterogeneity of the MRI methods and technical restrictions used in the current literature limit prediction of graft maturity and clinical and functional outcome measures by means of MRI graft SNQ after ACLR.

Level of evidence

Level IV, systematic review, including level III and IV studies.

Study protocol: a single-blind, multi-center, randomized controlled trial comparing dynamic intraligamentary stabilization, internal brace ligament augmentation and reconstruction in individuals with an acute anterior cruciate ligament rupture: LIBRƎ study

Background

The current gold standard for the treatment of an anterior cruciate ligament (ACL) rupture is reconstruction with tendon graft. Recently, two surgical ACL repair techniques have been developed for treating an acute ACL rupture: Dynamic Intraligamentary Stabilization (DIS, Ligamys®) and Internal Brace Ligament Augmentation (IBLA, InternalBrace™). We will conduct a single-blind, multi-center, randomized controlled trial which compares DIS, IBLA and reconstruction for relative clinical efficacy and economic benefit.

Methods

Subjects, aged 18–50 years, with a proximal, primary and repairable ACL rupture will be included. DIS is preferably performed within 4 weeks post-rupture, IBLA within 12 weeks and reconstruction after 4 weeks post-rupture. Patients are included in study 1 if they present within 0–4 weeks post-rupture and surgery is feasible within 4 weeks post-rupture. Patients of study 1 will be randomized to either DIS or IBLA. Patients are included in study 2 if they present after 4 weeks post-rupture and surgery is feasible between 5 and 12 weeks post-rupture. Patients of study 2 will be randomized to either IBLA or reconstruction. A total of 96 patients will be included, with 48 patients per study and 24 patients per study arm. Patients will be followed-up for 2 years. The primary outcome is change from baseline (pre-rupture) in International Knee Documentation Committee score to 6 months post-operatively. The main secondary outcomes are the EQ-5D-5 L, Tegner score, Lysholm score, Lachman test, isokinetic and proprioceptive measurements, magnetic resonance imaging outcome, return to work and sports, and re-rupture/failure rates. The statistical analysis will be based on the intention-to-treat principle. The economic impact of the surgery techniques will be evaluated by the cost-utility analysis. The LIBRƎ study is to be conducted between 2018 and 2022.

Discussion

This LIBRƎ study protocol is the first study to compare DIS, IBLA and ACL reconstruction for relative clinical efficacy and economic benefit. The outcomes of this study will provide data which could aid orthopaedic surgeons to choose between the different treatment options for the surgical treatment of an acute ACL rupture.

Trial registration

This study is registered at ClinicalTrials.gov; NCT03441295. Date registered 13.02.2018.