Contrast-Enhanced MRI Evaluation of Bone-Patellar Tendon-Bone and Hamstring ACL Autograft Healing in Humans: A Prospective Randomized Study

Comparison of "ligamentization" process between preserved insertion hamstring tendon autograft and bone-patellar tendon-bone autograft

BACKGROUND

Ligamentization is a complex process and effect of preservation of hamstring tendon graft insertion on this process is not well studied. Present study was conducted to analyze and compare the ligamentization of semitendinosus gracilis graft with preserved tibial insertion (STGPI) and bone-patellar tendon-bone (BPTB) autografts.

METHODS

A total of 50 sportspeople who underwent ACL reconstruction using either BPTB (group A; n = 25) or STGPI (group B; n = 25) autografts were included in the study. Contrast enhanced MRI was done at 8 months and 14 months post-ACL reconstruction to evaluate the ligamentization using Signal noise quotient (SNQ), graft intensity and enhancement index. Clinical outcomes (Lysholm score) and knee laxity were also assessed at 8 months and 14 months.

RESULTS

18/23 (78%) patients in group A and 14/23 (61%) patients in group B had hyperintense graft signal at 8 months (n.s.) and at 14 months, 1/23 patients in group A and none of the patients in group B had hyperintense graft. SNQ at 8 months was 3.6 ± 2 and 3.7 ± 2 in group A and B respectively (n.s.) and at 14 months, SNQ was 2.5 ± 1.5 in group A and 2.4 ± 1.3 in group B (n.s.). Enhancement index at 8 months was 1.5 ± 0.3 and 1.2 ± 0.3 in group A and B respectively (p = 0.0001). Enhancement index at 14 months was 1.21 ± 0.2 in group A and 1.07 ± 0.2 in group B (p = 0.003). Functional outcomes and knee laxity were comparable in both the groups at 8 and 14 months (n.s.).

CONCLUSION

Both the grafts i.e. BPTB and STGPI are similar in terms of rate and extent of ligamentization. Clinical outcomes and knee laxity are also comparable between two grafts.

Combined press-fit and extracortical fixation in patellar tendon anterior cruciate ligament reconstruction results in reliable graft fixation and early bone block incorporation

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction with bone-patellar-tendon-bone (BPTB) autograft has the potential biological advantage of direct bone-to-bone healing over soft tissue grafts. The primary aim of this study was to investigate possible graft slippage and therefore fixation strength in a modified BPTB autograft technique with suspensory fixation on both sides for primary ACL reconstruction until bony integration takes place.

METHODS

Twenty-one patients undergoing primary ACL reconstruction with a modified BPTB autograft (bone-on-bone (BOB) technique) between August 2017 and August 2019 were included in this prospective study. A computed tomography (CT) scan of the affected knee was performed directly postoperatively, as well as 3 months postoperatively. Examiner-blinded parameters for graft slippage, early tunnel widening, bony incorporation, as well as remodeling of the autologous refilled patellar harvest site were investigated.

RESULTS

A series of 21 patients treated with a BPTB autograft with this technique underwent two CT investigations. Comparison of CT scans showed no bone block displacement and therefore no graft slippage in the patient cohort. Only one patient showed signs of early tunnel enlargement. Radiological bone block incorporation took place showing bony bridging of the graft to the tunnel wall in 90% of all patients. Furthermore, 90% showed less than 1 mm bone resorption of the refilled harvest site at the patella.

CONCLUSIONS

Our findings suggest graft fixation stability and reliability of anatomic BPTB ACL reconstruction with a combined press-fit and suspensory fixation technique by absence of graft slippage within the first 3 months postoperatively.

Early Postoperative MRI Evaluation of a Fascia Lata Autograft With and Without Polypropylene Mesh Augmentation After Superior Capsular Reconstruction

BACKGROUND

Recently, a polypropylene mesh has been introduced and reported to improve clinical outcomes after superior capsular reconstruction (SCR) using a fascia lata autograft (FLA). However, mesh-related events such as a foreign body response may trigger inflammation, which might affect graft healing and remodeling.

PURPOSE/HYPOTHESIS

The aim was to investigate whether the healing and remodeling of an FLA were affected by the use of a mesh by comparing the signal intensity of an FLA-alone group vs an FLA + Mesh group on postoperative magnetic resonance imaging (MRI). The hypothesis was that the use of a mesh would decrease the MRI signal intensity of FLA during the early postoperative phase.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who had undergone SCR using an FLA with or without a mesh between March 2013 and August 2021 were retrospectively analyzed. Follow-up MRI was performed at 3 months. A total of 78 patients (24 in the FLA group and 54 in the FLA + Mesh group) with intact grafts were included. Graft remodeling was evaluated by analyzing the signal-to-noise quotient (SNQ) at the humeral, mid-substance, and glenoid sites. Theoretically, lower SNQ ratios indicate higher strength and better healing of the graft.

RESULTS

The mean SNQ was 30.603 (range, 11.790-72.710) in the FLA group and 18.367 (range, 4.464-69.500) in the FLA + Mesh group (P < .001). Furthermore, significant differences were found between the 2 groups at the humeral and mid-substance sites (37.863 [range, 5.092-81.187] vs 15.512 [range, 1.814-80.869], P < .001; and 29.168 [range, 6.103-73.900] vs 16.878 [range, 2.454-92.416], P = .003; respectively). However, there was no difference between the 2 groups at the glenoid site (25.346 [range, 7.565-86.353] vs 20.354 [range, 3.732-88.468], P = .057).

CONCLUSION

At the 3-month follow-up, the FLA + Mesh group showed a lower MRI signal intensity than the FLA group. The healing and remodeling of an FLA may be enhanced when a mesh is used.

Association Between Early Postoperative Graft Signal Intensity and Residual Knee Laxity After Anterior Cruciate Ligament Reconstruction

Background:

Magnetic resonance imaging (MRI) graft signal intensity is associated with graft damage after anterior cruciate ligament reconstruction (ACLR). However, little is known about the relationship between graft signal intensity and residual laxity of the reconstructed knee based on patient age.

Purpose/Hypothesis:

To evaluate the relationship between graft signal intensity and residual laxity in younger and older patients who underwent ACLR. We hypothesized that higher graft signal intensity would be associated with reduced postoperative knee stability.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 192 patients who underwent double-bundle ACLR were recruited. Proton density–weighted and T2-weighted MRI was performed at 3, 6, and 12 months after surgery, and the signal intensity ratio (SIR) of the anteromedial and posterolateral bundles was measured as the graft signal intensity reference values. At 12 months after surgery, if the KT-1000 arthrometer measurement exhibited a side-to-side difference of ≥2 mm, the patient was determined as having anterior knee laxity. Rotatory knee laxity was defined as a positive pivot shift with International Knee Documentation Committee grade ≥1. The Mann-Whitney U test was used to compare the SIR in patients with and without residual laxity. The Spearman correlation coefficient was used to evaluate the relationship between demographic parameters and the SIR. Based on receiver operating characteristic curves, the optimal SIR cutoff values to predict residual laxity were calculated, and logistic regression analysis was conducted.

Results:

Of 192 patients, 26 (13.5%) had anterior knee laxity, and 20 (10.4%) had rotatory knee laxity. The SIR was negatively correlated with age. In younger patients (<30 years; n = 135), those with residual laxity had a significantly higher SIR than those without laxity; this relationship was not significant in older patients (≥30 years; n = 57). Based on receiver operating characteristic curves and logistic regression analysis, the cutoff values that were determined for the SIR were significantly associated with a higher odds ratio of residual laxity.

Conclusion:

Graft signal intensity decreased with patient age. Patients with higher graft signal intensity in the early postoperative phase after ACLR exhibited a higher prevalence of residual laxity, particularly in younger patients.

Superb microvascular imaging (SMI) detects increased vascularity of the torn anterior cruciate ligament

PURPOSE

Ultrasound with superb microvascular imaging (SMI) is a novel microvascular imaging technology which may be useful to assess the vascularity of the torn anterior cruciate ligament (ACL) as a potential measure of healing potential following surgery. This study aimed to quantify the vascularity of the torn and intact ACL using ultrasound with SMI.

METHODS

23 patients (mean age ± standard deviation, 27.1 ± 12.8 years), who were diagnosed with an ACL tear with an intact contralateral ACL were enrolled (ACL injury group). Ten healthy volunteers (36.1 ± 4.9 years) who had intact ACLs in both knees were also recruited (ACL healthy controls). The vascularity of the ACL was assessed using SMI within 15 mm from the tibial insertion in both knees. The amount of the vascular signal was assessed using a semi-quantitative grading scale (vascularity grade: grade 0-3) and a quantified ratio of vascularized area with respect to total area of the region of interest (vascularity ratio).

RESULTS

In the ACL injury group, a significantly higher vascularity grade and ratio were observed in the torn ACL (vascularity grade 0-3: 1, 8, 7, and 7 patients, respectively; vascularity ratio: 1.3 ± 1.4%) than the contralateral intact ACL (vascularity grade 0-3: 21, 1, 1, and 0 patients, respectively; vascularity ratio: 0.1 ± 0.5%) (P < 0.001), whereas no significant difference was observed between both ACLs in the ACL healthy control group.

CONCLUSIONS

SMI was useful to assess the increased vascularity in torn ACL, which may reflect the potential for, or state of, ACL maturation following reconstruction or repair.

LEVEL OF EVIDENCE

Level III.

Effect of Lateral Extra-articular Tenodesis on Anterior Cruciate Ligament Graft Incorporation

Background:

It has been shown that adding lateral extra-articular tenodesis (LET) to standard anterior cruciate ligament (ACL) reconstruction significantly decreases the loads on the ACL composite graft. To date, the possible effect of LET on ACL graft incorporation is not known.

Purpose:

To compare the incorporation in tibial bone tunnels of a standard quadrupled semitendinosus (ST4) graft to an ST4 graft plus LET at 1 year postoperatively using magnetic resonance imaging (MRI).

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 62 patients who underwent ACL reconstruction were enrolled prospectively: 31 received an ST4 graft, and 31 received an ST4 graft plus LET. Graft incorporation was evaluated with MRI at the 1-year follow-up visit. The following parameters were evaluated: signal-to-noise quotient (SNQ), tibial tunnel widening, graft healing, and graft maturity according to the Howell scale. The primary endpoint was the SNQ of the ST4 graft at 1 year postoperatively; this parameter was adjusted because of unequal baseline characteristics between groups. Clinical and functional outcomes as well as incorporation of the graft were analyzed as secondary endpoints.

Results:

The mean adjusted SNQ was 0.5 ± 2.1 (95% CI, 0.4-4.6) in the ST4 + LET group and 5.9 ± 3.7 (95% CI, 4.7-7.0) in the ST4 group (P = .0297). The mean tibial tunnel widening was 73.7% ± 42.2% in the ST4 + LET group versus 77.5% ± 46.7% in the ST4 group (P = .5685). Howell grade I, indicative of better graft maturity, was statistically more frequent in the ST4 + LET group (P = .0379). No statistically significant difference was seen between groups in terms of graft healing (P = .1663). The Lysholm score was statistically higher in the ST4 + LET group (P = .0058). No significant differences were found between groups in terms of the International Knee Documentation Committee subjective score (P = .2683) or Tegner score (P = .7428). The mean SNQ of the LET graft at the 1-year follow-up visit was 2.6 ± 4.9.

Conclusion:

At 1 year postoperatively, the MRI appearance of ACL grafts showed generally better incorporation and maturation when combined with LET.

The relationship between graft synovialization and graft revascularization after ACL reconstruction: Assessment using dynamic contrast enhanced-MRI and second-look arthroscopy

PURPOSE

To assess graft vascularity via dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) at 1-year and 2-year postoperatively and to evaluate the relationship between the vascularity using DCE-MRI and the synovialization using second-look arthroscopy.

MATERIALS AND METHODS

Fifty-four patients from prospective data included who underwent anterior cruciate ligament reconstruction (ACLR) and DCE-MRI. The graft was divided into proximal, middle, and distal zones; average of three zones was calculated. Signal/noise quotient (SNQ) was measured on proton-density image and normalized area under the curve (nAUC) was calculated from DCE-MRI. The results at 1-year (SNQ-1 and nAUC-1) and 2-year (SNQ-2 and nAUC-2) postoperatively were compared between two time points. Forty-one patients underwent second-look arthroscopy were classified into three groups according to the synovialization: Excellent (n = 17), Fair (n = 16), and Poor (n = 8). The SNQs and nAUCs were compared between three groups.

RESULTS

Fifty-four and 23 patients underwent DCE-MRI at 1-year and 2-year, respectively. A significant decrease was observed from nAUC_average-1 to nAUC_average-2 (95 % confidential interval, 0.4-2.3; P = .007). Both SNQ_average-1 and SNQ_average-2 were significantly lower in the excellent than in the poor (SNQ_average-1, P < .001; SNQ_average-2, P = .003). Both SNQ_average-1 and SNQ_average-2 were significantly lower in the fair than in the poor (SNQ_average-1, P=.032; SNQ_average-2, P = .012). Both nAUC_average-1 and nAUC_average-2 were significantly higher in the excellent than in the poor (nAUC_average-1, P < .001; nAUC_average-2, P = .010). The nAUC_average-1 was significantly higher in the excellent than the fair (nAUC_average-1, P < .001).

CONCLUSION

Well-synovialized grafts showed significantly lower SNQs and significantly higher nAUCs than did poor-synovialized grafts based on the second-look arthroscopic findings. We can indirectly infer from this result that well-synovialized grafts may have better biomechanical properties.