Reliability of a semi-automated 3D-CT measuring method for tunnel diameters after anterior cruciate ligament reconstruction: A comparison between soft-tissue single-bundle allograft vs. autograft

Decreased femur tunnel widening after augmented suspensory fixation compared to suspensory fixation for single bundle hamstring ACL reconstruction

Background

Tunnel widening after Anterior cruciate ligament (ACL) reconstruction using a hamstring graft is known to occur at follow-up. Our study aimed to investigate the effect of suspensory fixation augmentation using an interference screw on tunnel widening in single-bundle hamstring ACL reconstruction.

Methods

48 patients who had single bundle ACL reconstruction with femoral fixed loop fixation technique in 15 knees, and, fixed loop with augmented aperture (bio screw) fixation in 33 knees were analyzed. The width of the tunnel was measured using radiographs immediate post-op and at follow-up within 1 year. Computerized Tomogram (CT) measurements of the tunnels and functional scores were also done with overall follow-up for the fixed loop group being 21.33 months (Standard Deviation (SD)11.14) and the Augmentation group 9.12 months (SD 3.83).

Results

Midpoint femur tunnel widening was reduced in the augmentation group, with measurements of 0.74 (SD 1.05) mm Antero Posterior (AP) and 1.01 (SD 1.04) mm in the Lateral view, compared to 1.54 (SD 1.48) mm AP and 1.79 (SD1.47 mm) in the Lateral for the fixed button group. The radiological widening was considerably less in the augmentation group with a p-value of 0.07. AP aperture widening in the augmentation group was 1.25(SD 1.10 mm), and 1.09(SD0.98) mm in the lateral view. The fixed button-only group measured 1.53 (SD1.30) mm in the AP, and 1.65 (SD 1.29) mm in the lateral view, both of which were not statistically significant. The follow-up Lysholm and International Knee Documentation Committee (IKDC) scores were similar for the 2 groups.

Conclusion

Femoral tunnel midpoint and aperture widening were reduced with the fixed loop with aperture (bio screw) augmentation technique for hamstring grafts in single bundle ACL fixation within 1 year with comparable functional scores.

Level of evidence

4.

Eccentrically widened bone tunnels after all-inside anterior cruciate ligament reconstruction: a computed tomography and three-dimensional model-based analysis

PURPOSE

To evaluate the extent of tunnel widening after anterior cruciate ligament reconstruction (ACLR) using the all-inside technique and to establish its correlation with patient-reported clinical outcomes and femoral graft bending angle (GBA).

METHODS

Tunnel widening was evaluated using computed tomography (CT)-based three-dimensional (3D) models, and the femoral GBA was directly measured on CT images using the Picture Archiving and Communication System (PACS) software. Clinical follow-up was routine procedure, and patient-reported clinical outcomes mainly included International Knee Documentation Committee (IKDC), Lysholm, and Knee Injury and Osteoarthritis Outcome Scores (KOOS) scores, and subjective knee stability assessment.

RESULTS

Fifty-two patients received standard all-inside ACLR, with a median follow-up of 6 months. Reconstructed anterior cruciate ligaments (ACLs) were scanned during the first 3 days and 6 months after surgery. On both the femoral and tibial sides, bone tunnels were most significantly enlarged at the articular aperture segment; the femoral tunnel was 9.2 ± 1.3 mm postoperatively and was significantly enlarged by 32% to a mean tunnel diameter of 12.1 ± 2.0 mm at 6 months after surgery. Moreover, the extent of tunnel enlargement gradually decreased as the measured levels approached those of the bone cortex. The femoral tunnel center was shifted into the anterior and distal direction, and the tibial tunnel center was shifted into the posterior and lateral direction. Additionally, the mean femoral GBA was 105.9° ± 8.1° at the 6-month follow-up. Tunnel enlargement and GBA were not significantly correlated with patient-reported outcomes.

CONCLUSIONS

Femoral and tibial tunnels were significantly greater and eccentrically shifted at the 6-month follow-up after all-side ACLR. However, the extent of tunnel widening does not markedly affect the short-term clinical outcomes. Meanwhile, the femoral GBA was not significantly correlated with femoral tunnel widening or patient-reported outcomes. Although the tunnel widening following all-inside ACLR was not associated with clinical outcomes, it potentially caused difficulties in revision ACLR.

LEVEL OF EVIDENCE

Level IV.

Tunnel Enlargement Correlates With Postoperative Posterior Laxity After Double-Bundle Posterior Cruciate Ligament Reconstruction

Background:

There exists little information in the relevant literature regarding tunnel enlargement after posterior cruciate ligament (PCL) reconstruction (PCLR).

Purpose:

To sequentially evaluate tunnel enlargement and radiographic posterior laxity through double-bundle PCLR using autologous hamstring tendon grafts.

Study Design:

Case series; Level of evidence, 4.

Methods:

We prospectively analyzed 13 patients who underwent double-bundle PCLR for an isolated PCL injury. Three-dimensional computed tomography images were obtained at 3 weeks, 6 months, and 1 year postoperatively, and the tunnel enlargement was calculated by sequentially comparing the cross-sectional areas of the bone tunnels. We also sequentially measured radiographic posterior laxity. The correlation between the tunnel enlargement ratio and the postoperative increase in posterior laxity was evaluated.

Results:

The cross-sectional area at the aperture in each tunnel significantly increased from 3 weeks to 6 months (P < .003), but it did not continue doing so thereafter. The 6-month tunnel enlargement ratios of the femoral anterolateral tunnel, the femoral posteromedial tunnel, the tibial anterolateral tunnel, and the tibial posteromedial tunnel were 31.6% ± 23.5%, 90.3% ± 54.7%, 30.5% ± 26.8%, and 49.6% ± 37.0%, respectively, while the corresponding ratios at 1 year were 28.1% ± 19.8%, 83.1% ± 56.9%, 26.8% ± 32.8%, and 47.6% ± 39.0%, respectively. The posterior laxity was 9.0 ± 4.0 mm, −1.5 ± 2.3 mm, 3.4 ± 2.0 mm, and 3.9 ± 1.9 mm, preoperatively, immediately after surgery, 6 months and 1 year postoperatively, respectively. From the immediate postoperative period, the posterior laxity significantly increased at 6 months postoperatively (P < .001), but it did not thereafter. The postoperative increase in posterior laxity had a significant positive correlation with the anterolateral tunnel enlargement ratio in both femoral and tibial tunnels at 6 months (ρ = 0.571-0.699; P = .011-.041) and 1 year (ρ = 0.582-0.615; P = .033-.037).

Conclusion:

Tunnel enlargement after PCLR mainly occurred within 6 months, with no progression thereafter. The anterolateral tunnel enlargement positively correlated with postoperative increase in posterior laxity.

Revision ACL Reconstruction in Adolescent Patients

Background:

High failure rates have been documented after anterior cruciate ligament reconstruction (ACLR) in pediatric patients, and revision surgery is indicated due to high activity levels of children and adolescents.

Purpose:

To define trends in revision ACLR in patients who underwent initial ACLR at younger than 18 years.

Study Design:

Case series; Level of evidence, 4.

Methods:

An electronic medical record was used to retrospectively identify revision ACLR procedures performed by 2 surgeons between the years 2010 and 2016 in patients younger than 18 years at initial reconstruction. Descriptive information, intraoperative findings, surgical techniques, and rehabilitation data were recorded from initial and revision surgeries. Descriptive statistics were used.

Results:

A total of 32 patients (17 girls, 15 boys) met the inclusion criteria, with a mean age of 15.8 years at initial reconstruction. For initial reconstructions, 15 patients underwent transphyseal procedures, 3 patients underwent adult-type procedures using an anatomic reconstruction technique that did not take into account the physis, and 2 patients underwent partial intraepiphyseal procedures. Graft types included hamstring autograft (n = 17), allograft (n = 5), hybrid (n = 4), and bone–patellar tendon–bone autograft (BTB; n = 3). Average primary reconstruction graft diameter was 8.0 mm (girls, 7.72 mm; boys, 8.36 mm; P = .045). After initial reconstruction, 10 patients had postoperative protocol noncompliance, and 8 patients reported delayed recovery. Mean time to retear was 565 days (range, 25-1539 days). At revision, BTB autograft was used in 50% (n = 16), followed by hamstring autograph (31.3%; n = 10) and allograft (12.5%; n = 4); mean graft diameter was 9.05 mm. Chondral surgery was more common during revision (25% for revision vs 0% for index; P = .031). There were 4 patients who required staged reconstruction with bone grafting. At mean final follow-up of 29.5 months (SD, 22.2 months), there were 3 graft failures (9.4%) and 5 contralateral ACL ruptures (15.6%).

Conclusion:

Most patients with ACL graft failure were adequately treated with a single revision. Conversion from a soft tissue graft to a BTB autograft was the most common procedure. Infrequently, patients required staged reconstructions. Providers should have a high index of suspicion for associated intra-articular injuries resulting from graft failure in adolescent patients.

Tibial tunnel enlargement after anatomic anterior cruciate ligament reconstruction with a bone-patellar tendon-bone graft. Part 2: Factors related to the tibial tunnel enlargement

BACKGROUND

Factors related to tunnel enlargement after anterior cruciate ligament (ACL) reconstruction should be evaluated by multivariate analysis, because the phenomenon has multifactorial characteristics. The purpose of this study was to elucidate the factors related to the tibial tunnel enlargement rate after anatomic ACL reconstruction with a bone-patellar tendon-bone (BTB) graft using multivariate analysis.

METHODS

Eighteen patients with unilateral ACL rupture were included. The anatomic rectangular-tunnel (ART) ACL reconstruction with a BTB autograft was performed. 3D CT models of the tibia, the tibial tunnel, and the bone plug at 3 weeks and 1 year after surgery were reconstructed and superimposed using a surface registration technique. The cross-sectional area (CSA) of the tibial tunnel perpendicular to the tunnel axis was evaluated at the aperture. The CSA was measured at 3 weeks and 1 year after surgery, and the tunnel enlargement rate at the aperture was calculated. Multiple linear regression analysis was performed to detect the significantly related factors to the tibial tunnel enlargement rate at the aperture among potential factors consisting of preoperative demographic factors and predisposing factors with the tibial tunnel.

RESULTS

The tibial tunnel enlargement rate at the aperture was 21.9 ± 14.1% (mean ± standard deviation). Multiple linear regression analysis detected the tendon length inside the tunnel as a significantly independent factor related to the tibial tunnel enlargement rate at the aperture (standardized β = 0.726, P = 0.008). There was no significant relationship between the tibial tunnel enlargement rate at the aperture and postoperative side-to-side difference (SSD) of the anterior knee laxity or Tegner activity level scale under single linear regression analysis.

CONCLUSION

The greater tendon length inside the tunnel was independently related to the higher tibial tunnel enlargement rate at the aperture 1-year after anatomic ACL reconstruction with a BTB graft under multiple linear regression analysis.

Tibial tunnel enlargement after anatomic anterior cruciate ligament reconstruction with a bone-patellar tendon-bone graft. Part 1: Morphological change in the tibial tunnel

BACKGROUND

Three-dimensional (3D) computed tomography (CT) is reliable and accurate imaging modality for evaluating tunnel enlargement after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the tibial tunnel enlargement including the morphological change after anatomic ACL reconstruction with a bone-patellar tendon-bone (BTB) graft using 3D CT models.

METHODS

Eighteen patients with unilateral ACL rupture were included. The anatomic rectangular-tunnel (ART) ACL reconstruction with a BTB autograft was performed. 3D CT models of the tibia, the tibial tunnel, and the bone plug at 3 weeks and 1 year after surgery were reconstructed and superimposed using a surface registration technique. The cross-sectional area (CSA) of the tibial tunnel perpendicular to the tunnel axis was evaluated at the aperture and 5, 10, and 15-mm distal from the aperture. The CSA was measured at 3 weeks and 1 year after surgery and compared between the two time points. The locations of the center and the anterior, posterior, medial, and lateral edges of the tunnel footprint were also evaluated based on the coordinate system for the tibial plateau and compared between the two time points.

RESULTS

At the aperture, the CSA of the tibial tunnel at 1 year after surgery was significantly larger by 21.9% than that at 3 weeks (P < 0.001). In contrast, the CSA at 1 year was significantly smaller than that at 3 weeks at 10 and 15-mm distal from the aperture (P = 0.041 and < 0.001, respectively). The center of the tunnel footprint significantly shifted postero-laterally with significant posterior shift of the anterior/posterior edges and lateral shift of the lateral edge (P < 0.001).

CONCLUSION

The tibial tunnel enlarged at the aperture by 22% 1-year after anatomic ACL reconstruction with a BTB graft, and the tunnel morphology changed in a postero-lateral direction at the aperture and into conical shape inside the tunnel.

Anterior cruciate ligament reconstruction is associated with greater tibial tunnel widening when using a bioabsorbable screw compared to an all-inside technique with suspensory fixation

PURPOSE

To compare clinical outcomes and tunnel widening following anterior cruciate ligament reconstruction (ACLR) performed with an all-inside technique (Group A) or with a bioabsorbable tibial screw and suspensory femoral fixation (Group B).

METHODS

Tunnel widening was assessed using computed tomography (CT) and a previously validated analytical best fit cylinder technique at approximately 1-year following ACLR. Clinical follow-up comprised evaluation with IKDC, KSS, Tegner, Lysholm scores, and knee laxity assessment.

RESULTS

The study population comprised 22 patients in each group with a median clinical follow-up of 24 months (range 21-27 months). The median duration between ACLR and CT was 13 months (range 12-14 months). There were no significant differences in clinical outcome measures between groups. There were no differences between groups with respect to femoral tunnel widening. However, there was a significantly larger increase in tibial tunnel widening, at the middle portion, in Group B (2.4 ± 1.5 mm) compared to Group A (0.8 ± 0.4 mm) (p = 0.027), and also at the articular portion in Group B (1.5 ± 0.8 mm) compared to Group A (0.8 ± 0.8 mm) (p = 0.027).

CONCLUSION

Tibial tunnel widening after ACLR using hamstring tendon autograft is significantly greater with suspensory femoral fixation and a bioabsorbable tibial interference screw when compared to an all-inside technique at a median follow-up of 2 years. The clinical relevance of this work lies in the rebuttal of concerns arising from biomechanical studies regarding the possibility of increased tunnel widening with an all-inside technique.

LEVEL OF EVIDENCE

III.

Femoral tunnel widening is similar between anteromedial portal and transtibial techniques following single-bundle anterior cruciate ligament reconstruction: a systematic review and meta-analysis

PURPOSE

In anterior cruciate ligament (ACL) reconstruction, there is concern regarding the potential risk of femoral tunnel widening in the anteromedial portal (AMP) technique due to the acute graft-bending angle at the aperture and the more elliptical aperture shape of the femoral tunnel compared to the transtibial (TT) techniques. Therefore, the aim of the current systematic review and meta-analysis was to compare the femoral tunnel widening between the AMP and TT techniques in patients who underwent ACL reconstruction.

METHODS

It should be included the studies that reported on femoral tunnel widening in patients who underwent single-bundle ACL reconstruction, using soft-tissue tendon graft, with AMP and/or TT techniques. Two reviewers independently recorded data from each study, including the sample size and magnitude of tunnel widening after ACL reconstruction.

RESULTS

Twenty-one studies were finally included in this meta-analysis. The pooled changes of absolute millimeters of tunnel widening from the immediate postoperative status to the last follow-up did not differ significantly between the AMP and TT techniques at both the aperture [3.31 mm, 95% confidence interval (CI) 1.7-5.0. mm versus 2.9 mm, 95% CI 2.4-3.4 mm, P = n.s.] and the midportion (3.5 mm, 95% CI 0.8-6.3 mm versus 3.0 mm, 95% CI 2.2-3.9 mm, P = n.s.) of the femoral tunnel. No significant difference was observed between the two techniques in the relative percentage of femoral tunnel widening (AMP; 28.8%, 95% CI 14.8-42.9% vs. TT; 29.7%, 95% CI 15.6-43.7%, P = n.s.).

CONCLUSION

No significant difference in femoral tunnel widening was observed between the AMP and TT techniques, both in absolute millimeter and relative percentage, in patients who underwent single-bundle ACL reconstruction. This finding could alleviate the potential concerns associated with femoral tunnels being wider for the AMP than for the TT technique.

LEVEL OF EVIDENCE

III.

Autograft Versus Allograft for Posterior Cruciate Ligament Reconstruction: An Updated Systematic Review and Meta-analysis

BACKGROUND

Multiple studies have demonstrated a higher risk of graft failure after anterior cruciate ligament reconstruction with allograft, but limited data are available comparing outcomes of posterior cruciate ligament reconstruction (PCLR) with autograft versus allograft.

PURPOSE

To compare the clinical outcomes of autograft versus allograft for primary PCLR.

STUDY DESIGN

Systematic review.

METHODS

A systematic review was performed by searching PubMed, the Cochrane Library, and EMBASE to locate studies (level of evidence I-III) comparing clinical outcomes of autograft versus allograft in patients undergoing primary PCLR with the conventional transtibial technique. Search terms used were "posterior cruciate ligament," "autograft," and "allograft." Patients were evaluated based on graft failure rate, examination of knee laxity, and patient-reported outcome scores (Lysholm, Tegner, subjective International Knee Documentation Committee [IKDC], and objective IKDC scores).

RESULTS

Five studies (2 level II, 3 level III) were identified that met inclusion criteria, including a total of 132 patients undergoing PCLR with autograft (semitendinosus-gracilis or bone-patellar tendon-bone) and 110 patients with allograft (tibialis anterior, Achilles tendon, or bone-patellar tendon-bone). No patients experienced graft failure. Average anteroposterior (AP) knee laxity was significantly higher in allograft patients (3.8 mm) compared with autograft patients (3.1 mm) ( P < .01). Subjective IKDC, Lysholm, and Tegner scores improved for both groups across studies, without a significant difference in improvement between groups except in one study, in which Lysholm scores improved to a significantly greater extent in the autograft group ( P < .01).

CONCLUSION

Patients undergoing primary PCLR with either autograft or allograft can be expected to experience improvement in clinical outcomes. Autograft patients experienced less AP knee laxity postoperatively, although the clinical significance of this is unclear and subjective outcomes improved substantially and to a similar degree in both groups.

Increased lateral tibial posterior slope is related to tibial tunnel widening after primary ACL reconstruction

PURPOSE

The purpose of the study was to determine the influence of femoral and tibial bone morphology on the amount of femoral and tibial tunnel widening after primary anatomic ACL reconstruction. It was hypothesized that tibial and femoral bone morphology would be significantly correlated with tunnel widening after anatomic ACL reconstruction.

METHODS

Forty-nine consecutive patients (mean age 21.8 ± 8.1 years) who underwent primary single-bundle anatomic ACL reconstruction with hamstring autograft were enrolled. Two blinded observers measured the bone morphology of tibia and femur including, medial and lateral tibial posterior slope, medial and lateral tibial plateau width, medial and lateral femoral condyle width, femoral notch width, and bicondylar width on preoperative magnetic resonance imaging (MRI) scans. Tibial and femoral tunnel width at three points (aperture, mid-section, and exit) were measured on standard anteroposterior radiograph from 1 week and 1 year postoperatively (mean 12.5 ± 2 months). Tunnel width measurements at each point were compared between 1 week and 1 year to calculate percent of tunnel widening over time. Multivariable linear regression was used to analyze correlations between bone morphology and tunnel widening.

RESULT

Increase in lateral tibial posterior slope was the only independent bony morphology characteristics that was significantly correlated with an increased tibial tunnel exit widening (R = 0.58). For every degree increase in lateral tibial posterior slope, a 3.2% increase in tibial tunnel exit width was predicted (p = 0.003). Excellent inter-observer and intra-observer reliability were determined for the measurements (ICC = 0.91 and 0.88, respectively).

CONCLUSION

Increased lateral tibial posterior slope is an important preoperative anatomic factor that may predict tunnel widening at the tibial tunnel exit. In regard to clinical relevance, the results of this study suggest that lateral tibial posterior slope be measured preoperatively. In patients with increased lateral tibial posterior slope, more rigid graft fixation and a more conservative physical therapy regiment may be preferred. Level of evidence IV.

How to evaluate bone tunnel widening after ACL reconstruction - a critical review

Background

Comparing different imaging modalities and methods for assessment tunnel widening after ACL reconstruction and providing a detailed evidence-based literature overview.

Methods

PubMed was searched from 1970 to 2016 using the terms "ACL reconstruction" and "tunnel" and "imaging" or "CT" or "computerized tomography" or "MRI" or "magnetic resonance imaging" or "radiographs". 647 studies were found. 575 articles were excluded due to absence of specific radiological measurement methods of tunnel widening and 40 due to repetition of a previously published radiological measurement method. 32 articles were included reporting interand intraobserver reliabilities of tunnel measurement methods after ACL reconstruction.

Results

A variety of different algorithms and measurement methods using radiographs, magnetic resonance imaging, computed tomography or SPECT/CT evaluating tunnel position and bone tunnel enlargement have been described. Tunnel delination restricts an exact analysis using X-ray. Measurements using CT or MR were mostly obtained perpendicular to the tunnel axis or using specialized software for tunnel volume calculation in 3D.Based on the review the width of the femoral and tibial tunnels should be assessed perpendicular to the tunnel axis at different levels in relation to the joint. At least one measurement should be performed at the tunnel entrance, exit and midpoint of the tunnel.

Conclusion

CT should be considered the gold standard assessing tunnel widening in patients after ACL reconstruction. If specialized software is available calculating the tunnel volume, measurements should be preferably performed in 3D CT.

Level of evidence

II.

Morphological changes in tibial tunnels after anatomic anterior cruciate ligament reconstruction with hamstring tendon graft

Background

Three-dimensional (3D) reconstructed computed tomography (CT) is crucial for the reliable and accurate evaluation of tunnel enlargement after anterior cruciate ligament (ACL) reconstruction. The purposes of this study were to evaluate the tibial tunnel enlargement at the tunnel aperture and inside the tunnel and to clarify the morphological change at the tunnel footprint 1 year after the anatomic triple-bundle (ATB) ACL reconstruction using 3D CT models.

Methods

Eighteen patients with unilateral ACL rupture were evaluated. The ATB ACL reconstruction with a semitendinosus tendon autograft was performed. 3D computer models of the tibia and the three tibial tunnels were reconstructed from CT data obtained 3 weeks and 1 year after surgery. The cross-sectional areas (CSAs) of the two anterior and the one posterior tunnels were measured at the tunnel aperture and 5 and 10 mm distal from the aperture and compared between the two periods. The locations of the center and the anterior, posterior, medial, and lateral edges of each tunnel footprint were also measured and compared between the two periods.

Results

The CSA of the posterior tunnel was significantly enlarged at the aperture by 40.4%, whereas that of the anterior tunnels did not change significantly, although the enlargement rate was 6.1%. On the other hand, the CSA was significantly reduced at 10 mm distal from the aperture in the anterior tunnels. The enlargement rate in the posterior tunnel was significantly greater than that in the anterior tunnels at the aperture. The center of the posterior tunnel footprint significantly shifted postero-laterally. The anterior and posterior edges of the posterior tunnel footprint demonstrated a significant posterior shift, while the lateral edge significantly shifted laterally. There was no significant shift of the center or all the edges of the anterior tunnels footprint.

Conclusions

The posterior tibial tunnel was significantly enlarged at the aperture by 40% with the morphological change in the postero-lateral direction reflected by the ACL fiber orientation 1 year after the ATB ACL reconstruction. The proper tibial tunnel location in the ACL reconstruction should be determined considering the tunnel enlargement in postero-lateral direction after surgery.

Tunnel widening prevention with the allo-Achilles tendon graft in anterior cruciate ligament reconstruction: Surgical tips and short term followup

BACKGROUND

Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction can be a serious complication, and there is controversy over how to prevent it. This study aimed to suggest surgical approaches to prevent TW using an allo-Achilles tendon graft, and then to evaluate TW after these surgical tips were applied.

MATERIALS AND METHODS

Sixty two patients underwent ACL reconstruction with an allo-Achilles tendon graft. Four surgical approaches were used: Making a tibial tunnel by bone impaction, intraarticular reamer application, bone portion application for the femoral tunnel, and an additional bone plug application for the tibial tunnel. After more than 1-year, followup radiographs including anteroposterior and lateral views were taken in 29 patients encompassing thirty knees. The diameter of the tunnels at postoperation day 1 (POD1) and at followup was measured and compared.

RESULTS

In 18 knees (60%), there were no visible femoral tunnel margins on the radiographs at POD1 or followup. In the other 12 cases, which had visible femoral tunnel margins on followup radiographs, the mean femoral tunnel diameter was 8.6 mm. In the tibial tunnel, the mean diameters did not increase on all three levels (proximal, middle, and distal), and there was no statistically significant difference between the diameters at POD1 and followup.

CONCLUSION

The suggested tips for surgery involving an allo-Achilles tendon graft can effectively prevent TW after ACL reconstruction according to this case series. These surgical tips can prevent TW.

The anterior cruciate ligament: a study on its bony and soft tissue anatomy using novel 3D CT technology

PURPOSE

The purpose of this study is twofold: first, to visualize both the tibial and femoral bony insertion surfaces and second, to describe the anterior cruciate ligament (ACL) geometrically, using novel 3D CT imaging. In addition, new concepts of best-fit cylinder and central axis are introduced and evaluated.

METHODS

Eight unpaired knees of embalmed cadavers were used in this study. Following the dissection process, the ACL was injected with a contrast medium for CT imaging. The obtained CT images in extension, 45°, 90° and full flexion were segmented and rendered in 3D allowing morphological and morphometric analysis of the ACL. Anatomical footprint centres, femoral and tibial footprint surface area, best-fit ACL-cylinder intersection area, best-fit ACL-cylinder/footprint coverage ratio, best-fit ACL-cylinder central axis projections at the tibial and femoral footprint in the four positions were used to describe the anatomy of the ACL, based on the Bernard, Hertel and Amis grid.

RESULTS

Based on these parameters, with the best-fit cylinder representing the bulk of the ACL, a changing fibre-recruitment pattern was seen with a moving position of the central axis from posterior to anterior on the femoral and tibial footprint, going from extension to flexion. Furthermore, the numerical data show an increase in tibial footprint coverage by the best-fit cylinder through the ACL when the knee is progressively flexed, whereas an inverse relationship was seen on the femoral side.

CONCLUSION

This study is the first to describe the detailed anatomy of the human ACL with respect to its course and footprints using a 3D approach. It confirms the large difference and inter-patient variability between the tibial and femoral footprint area with the former being significantly smaller. The best-fit cylinder concept illustrates the recruitment pattern of the native ACL where in extension the postero-lateral fibres are recruited and in flexion rather the antero-medial bundle, which can be valuable information in reconstructive purposes. The best-fit cylinder and central axis concept offers additional insights into the optimal tunnel placement at the tibial and femoral footprint in order to cover the largest portion of the native ACL soft tissue, aiming for optimal ACL reconstruction.

Tunnel widening in single- versus double-bundle anterior cruciate ligament reconstructed knees

PURPOSE

The consequence of tunnel widening after ACL reconstructions is foremost of importance in case of revision surgery. Tunnel expansion leads to bone loss close to the joint, and additional surgery with bone grafting prior to revision surgery might be necessary. The purpose of the study was to measure widening of the tunnels in single-bundle (SB) and double-bundle (DB) ACL reconstructed knees during the first year after surgery, detected by a novel, semi-automated 3D CT imaging modality. Our hypothesis was that there would be a difference between the initial tunnel size and the size measured one year post-operatively due to the tunnel widening process. Further, the purpose was to evaluate whether there were any differences in the amount of tunnel widening between the two surgical techniques.

METHODS

Twenty patients who underwent DB ACL reconstruction, and 22 patients who underwent SB ACL reconstruction, performed a CT scan of the bony tunnels, during their first days after surgery and one year post-operatively. The CT scans were transformed into 3D CT reconstructions, and the tunnels were measured with the "best-fit cylinder" method, measurements at the level of tunnel aperture and 10.0 mm from the joint line.

RESULTS

All tunnels in the DB and SB ACL reconstructed knees exhibited widening during the first year after the operation (p < 0.001). The SB femoral tunnels showed more widening compared to the DB femoral AM tunnels (1.4 ± 0.9 vs. 0.5 ± 0.6 mm) (p < 0.001), and the SB tibial tunnels widened more compared to the DB tibial PL tunnels (1.0 ± 1.0 vs. 0.5 ± 0.6) (p < 0.043).

CONCLUSION

All tunnels widened during the first year after the ACL reconstruction with a larger amount of widening in the SB tunnels compared to the DB femoral AM tunnels and the DB tibial PL tunnels. This is the first study to detect tunnel widening in DB reconstructed knees through a semi-automated 3D CT imaging modality.

LEVEL OF EVIDENCE

Prospective cohort study, Level III.

Radiological and Clinical Evaluation of the Transosseous Cortical Button Technique in Distal Biceps Tendon Repair

PURPOSE

One of the options to repair a ruptured distal biceps tendon to the radial tuberosity is by means of a transosseous cortical button. Although excellent functional outcomes have been reported, no studies have been performed to quantify the effect of the transosseous fixation technique on the radius. Our study evaluated the clinical outcome and radiological outcome of this technique. The main goal of this study was to evaluate the radiographic evolution of the bone tunnel in the radius.

METHODS

Patients with an acute distal biceps tendon rupture treated with a transosseous cortical button were invited to take part in the study. Fourteen patients were included in the final analysis. All patients were evaluated both clinically and by computed tomography scanning of the proximal radius after a minimum follow-up of 2 years. Outcomes were recorded using the visual analog scale score for pain, the Mayo Elbow Performance Score, and Disabilities of the Arm, Shoulder, and Hand scores. Bone tunnel volume was measured with semiautomated computed tomography segmentation using image-processing software.

RESULTS

There were no failures of fixation in the patient group examined. Elbow mobility, arm, and forearm circumference were symmetric for all patients. Average visual analog scale for pain was less than 2. Mean Disabilities of the Arm, Shoulder, and Hand score and Mayo Elbow Performance Score were 2.3 and 97.6, respectively. Computed tomography images showed an average closure of the radial bony tunnel of 64% of the initial volume.

CONCLUSIONS

Biceps tendon repair with cortical button fixation only shows partial tunnel closure. This could reduce the risk of potential complications due to osteolysis, such as radius fracture or hardware failure. Functional results were excellent and comparable to other fixation methods. The role of interference screws in transosseous cortical button techniques to strengthen the repair and to avoid osteolysis may therefore be questioned.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Distal biceps tendon repair: comparison of clinical and radiological outcome between bioabsorbable and nonabsorbable screws

BACKGROUND

Distal biceps tendon repair to the radial tuberosity can be conducted by means of an interference screw in combination with a transosseous button. Bioabsorbable interference screws have been associated with complications such as severe osteolytic reactions. We questioned whether patients with a distal biceps tendon repair with bioabsorbable poly-L-lactide (PLLA) screws had different functional, clinical, and radiologic outcome than patients with nonabsorbable poly-ether ether ketone (PEEK) screws.

METHODS

Between 2010 and 2014, 23 patients with an acute distal biceps tendon rupture were treated with reinsertion of the distal biceps tendon in a bone tunnel at the radial tuberosity through a single anterior incision using a transosseous button combined with an interference screw. A PLLA screw was used in 12 patients and a PEEK screw in 11 patients. All patients were retrospectively evaluated with a minimal follow-up of 1 year clinically and by means of the visual analog scale for pain, Mayo Elbow Performance Score, and Disabilities of Arm, Shoulder and Hand Outcome Measure score. Bone tunnel volume was measured with computed tomography segmentation.

RESULTS

Elbow mobility and arm and forearm circumference were symmetric for all patients. The visual analog scale for pain was 0.2 in the PLLA group and 0.7 in the PEEK group. The Disabilities of Arm, Shoulder and Hand score and Mayo Elbow Performance Score were 5.4 and 98.7 in the PLLA group vs. 3.1 and 95.9 in the PEEK group. Bone tunnel enlargement of 43% in the PLLA and 38% in the PEEK group was noted.

CONCLUSIONS

Clinical and functional outcome at more than 1 year after distal biceps tendon repair was excellent in both groups. Bone tunnel widening occurred in all patients.

Quantification of tibial bone loss in antegrade versus retrograde tunnel placement for anterior cruciate ligament reconstruction

PURPOSE

Tibial bone destruction during primary graft tunnel placement and tibial bone loss following tunnel enlargement represent major challenges in revision reconstruction of the anterior cruciate ligament (ACL). Initial all-inside ACL reconstruction facilitates the preparation of tibial bone sockets rather than full tunnels that potentially preserve tibial bone stock. The purpose of this study was to comparatively assess length, diameter and volume of tibial graft tunnels following all-inside and conventional ACL reconstruction.

METHODS

Postoperative computed tomography (CT) scans of 59 patients were assessed following ACL reconstruction. In 35 patients we used conventional antegrade tibial tunnel drilling and in 24 all-inside retrograde tibial bone sockets. Imaging analysis included total, minimal and maximal tunnel length and tunnel diameter. Tunnel volumes were calculated corresponding to these parameters.

RESULTS

Statistically significant group differences (p < 0.01) could be detected for tibial tunnel volume, length and diameter between conventional antegrade and all-inside retrograde tibial bone tunnels and sockets, respectively.

CONCLUSIONS

Compared with conventional techniques, all-inside retrograde drilling of tibial bone sockets is effective in preserving significant bone stock, which might be beneficial for revision reconstruction in cases of eventual primary graft failure.