The cross-sectional shape of the fourfold semitendinosus tendon is oval, not round

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.

Characterization of scar tissue biomechanics during adult murine flexor tendon healing

Tendon injuries are very common and result in significant impairments in mobility and quality of life. During healing, tendons produce a scar at the injury site, characterized by abundant and disorganized extracellular matrix and by permanent deficits in mechanical integrity compared to healthy tendon. Although a significant amount of work has been done to understand the healing process of tendons and to develop potential therapeutics for tendon regeneration, there is still a significant gap in terms of assessing the direct effects of therapeutics on the functional and material quality specifically of the scar tissue, and thus, on the overall tendon healing process. In this study, we focused on characterizing the mechanical properties of only the scar tissue in flexor digitorum longus (FDL) tendons during the proliferative and early remodeling healing phases and comparing these properties with the mechanical properties of the composite healing tissue. Our method was sensitive enough to identify significant differences in structural and material properties between the scar and tendon-scar composite tissues. To account for possible inaccuracies due to the small aspect ratio of scar tissue, we also applied inverse finite element analysis (iFEA) to compute mechanical properties based on simulated tests with accurate specimen geometries and boundary conditions. We found that the scar tissue linear tangent moduli calculated from iFEA were not significantly different from those calculated experimentally at all healing timepoints, validating our experimental findings, and suggesting the assumptions in our experimental calculations were accurate. Taken together, this study first demonstrates that due to the presence of uninjured stubs, testing composite healing tendons without isolating the scar tissue overestimates the material properties of the scar itself. Second, our scar isolation method promises to enable more direct assessment of how different treatment regimens (e.g., cellular ablation, biomechanical and/or biochemical stimuli, tissue engineered scaffolds) affect scar tissue function and material quality in multiple different types of tendons.

No Differences In Clinical Outcomes Between Rectangular and Round Tunnel Techniques For Anterior Crucial Ligament Reconstruction

PURPOSE

To compare the clinical outcomes between conventional round tunnel and rectangular tunnel in anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

This was a retrospective comparative cohort study between March 2015 and September 2018. The primary ACL reconstructions using anteromedial portal technique with minimum of 2 years follow-up were enrolled for this study. The exclusion criteria were patients with revision ACL reconstruction, high tibial osteotomy, multiligament injuries, and associated fractures around the knee. Outcome measures included the subjective International Knee Documentation Committee score, Tegner activity score, knee laxity testing, and measurement of the centers of the femoral and tibial tunnels on postoperative computed tomography (CT) images.

RESULTS

Forty-seven patients with ACL reconstruction with rectangular tunnel (group 1) and 108 patients with ACL reconstructions with conventional rounded tunnel (group 2) were included consecutively. There were no significant differences between groups in terms of clinical scores or knee laxity, as well as femoral and tibial tunnel positions on CT. One patient in group 2 had ACL failure because of trauma and was treated with revision surgery. Two patients had incomplete tibial fracture, but they healed spontaneously and showed no residual laxity at final follow-up. The intraobserver and interobserver reliability for the radiological measurements ranged from 0.78 to 0.86.

CONCLUSIONS

There were no differences in radiological and clinical results between rectangular tunnel group and conventional round tunnel group for arthroscopic ACL reconstruction. ACL reconstruction with a rectangular tunnel could be considered as a reliable technique, but care should be taken during tunnel establishment because of risk of fractures and malposition of rectangular tunnel.

Does remnant tissue preservation in anterior cruciate ligament reconstruction influence the creation of the rectangular femoral tunnel?

PURPOSE

We have previously described anterior cruciate ligament reconstruction with a rounded rectangular femoral tunnel created using a rounded rectangular dilator designed to enable a more anatomical and wider tendon-bone junction. However, the influence of remnant tissue preservation on the creation of the rounded rectangular femoral tunnel is not clear. This study aimed to evaluate the influence of remnant tissue preservation on the creation of the rounded rectangular femoral tunnel.

METHODS

A total of 198 patients who underwent primary anterior cruciate ligament reconstruction with a rounded rectangular femoral tunnel were evaluated retrospectively. Patients were categorized into a remnant preservation group (group P) and a non-preservation group (group N). Computed tomography images taken 1 week postoperatively were analyzed. The location of the rounded rectangular femoral tunnel evaluated using the quadrant method, its rotation angle, and the graft bending angle were compared between the two groups. The differences and the variance in femoral tunnel assessment were compared using the two-sample t-test and Levene's test.

RESULTS

Although there was no significant difference in the location of femoral tunnel for the deep/shallow direction along the Blumensaat's line (difference, p = .326; variances, p = .970), the tunnel was significantly lower in group P than in group N, with no variances (difference, p = .001; variances, p = .326). There were no significant differences and no variances in the tunnel rotation angle and the graft bending angle (difference, p = .727 and 0.514, respectively; variances, p = .827 and .445, respectively). Blow out of the posterior wall of the medial aspect of the femoral lateral condyle was an intraoperative complication that occurred in one case in group N.

CONCLUSION

The remnant preservation approach creates a lower femoral tunnel compared to the non-preservation technique. However, a rounded rectangular femoral tunnel can be created safely and is reproducible with remnant tissue preservation.

Method development and characterization of chick embryo tendon mechanical properties

Tendons are involved in multiple disorders and injuries, ranging from birth deformities to tendinopathies to acute ruptures. The ability to characterize embryonic tendon mechanical properties will enable elucidation of mechanisms responsible for functional tendon formation. In turn, an understanding of tendon development could inform approaches for adult and embryonic tendon tissue engineering and regenerative medicine. The chick embryo is a scientifically relevant model that we have been using to study Achilles (calcaneal) tendon development. Chick embryo calcaneal tendons are challenging to mechanically test due to small size and delicate nature, and difficulty distinguishing embryonic tendons from muscle and fibrocartilage using the naked eye. Here, we developed and implemented a "marking protocol" to identify and isolate calcaneal tendons at different stages of chick embryonic development. Mechanical testing of tendons isolated using the marking protocol revealed trends in mechanical property development that were not observed with tendons isolated by naked eye (eyeballing). Marked tendons exhibited non-linear increases in tensile modulus and ultimate tensile strength, whereas eyeballed tendons exhibited linear increases in the same properties, reflecting a need for the marking protocol. Furthermore, the tensile mechanical properties characterized for marked tendons are consistent with previously reported trends in cell length-scale mechanical properties measured using atomic force microscopy. This report establishes new methodology to enable tensile testing of chick embryo tendons and provides new information about embryonic tendon mechanical property development.

Clinical outcomes of rectangular tunnel technique in posterior cruciate ligament reconstruction were comparable to the results of conventional round tunnel technique

PURPOSE

To compare clinical outcomes between the conventional round and rectangular tunnel techniques in single-bundle posterior cruciate ligament (PCL) reconstruction.

METHODS

Twenty-seven and 108 patients who underwent PCL reconstructions using a rectangular dilator (Group 1) and rounded tunnel reamer (Group 2), respectively, were included. The exclusion criteria were having a concomitant fracture, osteotomy, subtotal or total meniscectomy, and no remnant PCL tissue. A 4:1 propensity score matching was performed. The knee laxity on stress radiography, International Knee Documentation Committee Subjective Knee Evaluation score, Tegner activity score and Orthopädische Arbeitsgruppe Knie score were evaluated.

RESULTS

No significant differences were found between the groups in terms of clinical scores. (n.s.) The mean posterior translations were also not significantly different between the Group 1 and 2 (3.6 ± 2.8 and 3.8. ± 3.1 mm, respectively; n.s.). However, 3 patients (11.1%) in Group 1 and 15 patients (13.8%) in Group 2 showed posterior translation of > 5 mm. The combined posterolateral corner sling technique was performed for 27 patients (100%) in Group 1 and for 96 patients (88.9%) in Group 2. We found no significant difference in rotational stability at the final follow-up. One patient was found to have a femoral condyle fracture during rectangular femoral tunnel establishment, which was healed after screw fixation, without laxity, during follow-up. The intra- and inter-observer reliabilities of the radiological measurements ranged from 0.81 to 0.89.

CONCLUSION

Arthroscopic anatomical remnant-preserving PCL reconstruction using a rectangular dilator showed satisfactory clinical results and stability as compared with PCL reconstruction using a conventional rounded reamer. Rectangular tunnel technique in PCL reconstruction could be a good treatment option with theoretical advantage to be anatomic.

LEVEL OF EVIDENCE

Level IV.

Skeletally immature patient showed lower graft maturity than skeletally mature patient after ACL reconstruction with a rounded rectangular femoral tunnel

To compare the clinical results and ligamentization of anterior cruciate ligament reconstruction (ACLR) between skeletally immature and mature patients. Two-hundred-and-two patients who underwent primary ACLR were evaluated retrospectively. The clinical outcomes were compared between skeletally immature (immature group 1, n = 27) and mature (control group 1, n = 175) groups. Graft ligamentization of the reconstructed anterior cruciate ligament (ACL) using magnetic resonance imaging (MRI) signal intensity at 6 months postoperatively was compared between immature group 2 (n = 16), which included participants from immature group 1, and control group 2 (n = 32), created by recruiting data-matched controls from control group 1. Immature group 1 had significantly higher revision (14.8%) and pivot shift test positive (22.2%) rates than control group 1 (2.9% and 4.0%, respectively) (P = 0.020 and 0.003, respectively). The signal intensity in immature group 2 were significantly higher at the mid-substance and distal site of the reconstructed ACL than those in control group 2 (P = 0.003 and 0.034, respectively). Skeletally immature patients had higher graft revision and residual rotational laxity rates. Reconstructed ACL in skeletally immature patients showed higher signal intensity on MRI at 6 months postoperatively.

Anatomical Anterior Cruciate Ligament Reconstruction with Hamstring Tendon Autografts: A Comparative Study of Three Different Techniques

The ideal procedure for anterior cruciate ligament (ACL) reconstruction is one that can achieve anatomical restoration for a better ACL function. This retrospective comparative study was conducted to evaluate the objective and subjective clinical results of the conventional single-bundle femoral round (SBR) tunnel technique, the single-bundle femoral oval (SBO) tunnel technique, and the double-bundle (DB) surgical technique for anatomical ACL reconstruction with hamstring tendon autografts. Patients who underwent the SBO, SBR, and DB ACL reconstructions from January 2016 to August 2017 were included in this study. A total of 163 patients underwent different surgical techniques; 41 patients underwent the SBO procedure, 78 patients received SBR, and the remaining 44 patients underwent the DB procedure. The Lachman's test, pivot-shift test, Lysholm's score, International Knee Documentation Committee (IKDC) score, and Tegner's score were compared among groups postoperatively. KT-1000 was used to measure the anterior laxity of the knee. Magnetic resonance imaging was used to compare the ACL graft maturity. Second-look arthroscopy was conducted to compare the graft status and synovial coverage. Significant differences among groups were found with respect to the Lysholm's score, Tegner's score, and IKDC score. Patients in the SBO and DB groups acquired higher functional scores than the SBR group. More patients with positive pivot-shift test were observed in the SBR group than other groups at 12- and 24-month postoperative follow-ups. The postoperative KT-1000 was better in the SBO and DB groups than in the SBR group. The mean signal/noise quotient (SNQ) of the SBO group was 2.70 ± 0.92, significantly lower than 3.58 ± 1.21 of the SBR group. Despite a higher proportion of patients with grade B or C synovial coverage and partial graft injury found in the SBR group, there were no significant differences among the groups. The SBO and DB technique achieved better clinical results than the SBR technique. The SBO technique was indeed an ideal surgical procedure for ACL reconstruction provided that the shortcoming of DB technique must be taken into account. This is a Level III, retrospective comparative study.

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.

Clinical study of anatomical ACL reconstruction using a rounded rectangular dilator

Background

The aim of this study was that to compare clinical results between the rounded rectangular femoral tunnel ACL reconstruction (RFTR) and the conventional round femoral tunnel ACL reconstruction using a hamstring tendon. The hypothesis was that ACL reconstruction performed using the rounded rectangular dilator technique was better than that performed using the conventional round femoral tunnel technique in terms of clinical results and bone tunnel enlargement.

Methods

We conducted retrospective study. After exclusions, 40 patients were included in the conventional anatomical single-bundle ACL reconstruction (ASBR) group and 40 patients were included in the RFTR group. The evaluation items were knee stability, Lysholm knee score, IKDC subjective score at 2 years after surgery and bone tunnel enlargement.

Results

The RFTR group had a larger femoral tunnel area (average area, 53.1 ± 4.0 mm² vs. 46.1 ± 7.0 mm²; P < 0.01), better anteroposterior stability, and higher Lysholm scores than the ASBR group (average side-to-side difference for anterior tibial translation, 0.6 ± 0.8 mm vs. 1.6 ± 1.4 mm; P < 0.01; average Lysholm score, 98.5 ± 2.1 vs. 97.5 ± 3.5; P < 0.01). Further, bone tunnel enlargement ratio was significantly lower in the RFTR group (73 ± 38% vs. 107 ± 41%; P < 0.01).

Conclusions

We designed and developed an original rounded rectangular dilator to perform a novel ACL surgery. This technique can create a larger bone tunnel and improve clinical results than the conventional round anatomical single-bundle ACL reconstruction.

Adjustable suspension versus hybrid fixation in hamstring autograft anterior cruciate ligament reconstruction

BACKGROUND

There has been increased use of adjustable suspensory fixation (ASF) for anterior cruciate ligament reconstruction (ACLR). Potential benefits are the ability to use a shorter graft and to prevent graft displacement and damage. The purpose of this study was to establish the efficacy of this fixation method and assess whether it leads to less tunnel widening, and avoids known complications of screw fixation.

METHODS

Thirty-eight patients who underwent ACLR with ASF on both the femoral and tibial sides met the inclusion criteria and were propensity matched demographically with 38 patients who underwent hybrid fixation with femoral suspensory and tibial screw and sheath. At one-year, KT-1000 knee laxity measurements were recorded and detailed MRI analysis looking at tunnel aperture widening, tunnel appearance, graft integration within the tunnels, and graft healing.

RESULTS

MRI comparison between ASF and hybrid cohorts revealed no significant differences in graft signal or integration, and clinically there were no differences in knee laxity between cohorts (mean 1.5 mm ± 2.0 and 1.5 mm ± 2.3 (n.s.) in the ASF and hybrid fixation respectively). Significantly less aperture tibial tunnel widening (2.2 mm versus 4.4 mm, p < 0.0001) and tibial cysts (2 versus 9, p = 0.047) were observed in the ASF cohort, whilst mean femoral tunnel widening was comparable between both cohorts (ASF 2.8 mm, hybrid 3.2 mm; n.s.).

CONCLUSIONS

Hamstring autografts for ACLR fixed using either ASF or a hybrid fixation technique provided comparable knee stability and MRI graft signal intensity. Tibial ASF demonstrated significantly less tibial aperture widening and tunnel cyst formation when compared to screw and sheath fixation.

Oval femoral tunnel technique is superior to the conventional round femoral tunnel technique using the hamstring tendon in anatomical anterior cruciate ligament reconstruction

PURPOSE

This study was conducted to compare the efficacy between the oval femoral tunnel technique and the conventional round femoral tunnel technique in ACL reconstruction using an autologous hamstring tendon on the basis of the postoperative clinical outcomes and ACL graft tendon maturity. The hypothesis was that ACL reconstruction performed using the oval femoral tunnel technique was better than that performed using the round femoral tunnel technique in clinical functions and graft maturity.

METHODS

One hundred and eight patients who underwent anatomical single-bundle ACL reconstruction were included in this study and the follow-up period was at least 2 years. Thirty-nine patients admitted between February and August in 2016 were included in the oval femoral tunnel group and 69 patients admitted between September 2016 and March 2017 were included in the round femoral tunnel group. The Lachman test result, pivot-shift test result, Lysholm score, IKDC score, and VAS score were used for the clinical evaluation. An objective assessment of anteroposterior stability was performed using a KT1000 arthrometer. Postoperative MRI was conducted to compare the ACL graft maturity differences between the oval femoral tunnel group and round femoral tunnel group, where the signal/noise quotient (SNQ) was calculated. In addition, second-look arthroscopy was conducted to compare the graft status and synovial coverage at 24 months postoperatively.

RESULTS

All the patients presented with significant improvement in all clinical scores from the preoperative period to the 24-month follow-up. During the postoperative follow-up period, no statistically significant differences were found between the two groups in terms of the VAS score, knee ROM, Lachman test results, and graft status determined in the second-look arthroscopic evaluation. The Lysholm score was 97.1 ± 3.9 and 94.8 ± 5.6 in the oval femoral tunnel group and round femoral tunnel group, respectively, at the 24-month follow-up (p = 0.031). The IKDC subjective score was 92.0 ± 2.6 and 89.0 ± 3.6 in the oval femoral tunnel group and round femoral tunnel group, respectively, at the end of the follow-up period (p < 0.001). Significantly more patients with 1-degree positive pivot-shift test results were observed in the round femoral tunnel group (10/65) than in the oval femoral tunnel group (1/37) at the end of the follow-up period (p = 0.048). The mean SNQ of the oval femoral tunnel group was 2.7 ± 0.9, which was significantly lower than that of the round femoral tunnel group (3.6 ± 1.1) at the 24-month postoperative follow-up (p < 0.001).

CONCLUSIONS

Based on the clinical evaluations, MRI findings and second-look arthroscopy results of the two groups, the oval femoral tunnel technique yielded significantly better knee function and knee laxity restoration and more mature ACL grafts than the round femoral tunnel technique, whereas no significant differences were found at the second-look arthroscopy.

LEVEL OF EVIDENCE

III.

[Comparison of femoral oval tunnel technique and round tunnel technique in single-bundle anterior cruciate ligament reconstruction]

OBJECTIVE

To evaluate the effectiveness of femoral oval tunnel technique versus round tunnel technique in single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Between March 2016 and February 2018, 125 patients who underwent anatomical single-bundle ACL reconstruction with hamstring tendon and met the inclusive criteria were included in the retrospective study. Of the included patients, 43 patients underwent ACL reconstruction using oval tunnel technique (group A) and 82 patients with round tunnel technique (group B). There was no significant difference between the two groups in terms of age, gender, body mass index, the interval between injury and operation, the injured side, the cause of injury, and preoperative Lysholm score, International Knee Documentation Committee (IKDC) score, Tegner score, and the outcome of KT-1000 measurement ( P>0.05). At 3, 6, 12, and 24 months after operation, the knee function scores (Lysholm score, IKDC score, Tegner score) were recorded; and KT-1000 was used to evaluate the knee stability. The position and shape of the tunnels were evaluated by the three-dimensional CT (3D-CT) at 1 day after operation; and MRI was performed at 6, 12, and 24 months to calculate the signal/noise quotient (SNQ) of ACL grafts. Secondary arthroscopy was conducted to estimate the graft status, synovial coverage, and tension.

RESULTS

All patients were followed up 12-26 months (mean, 23 months). Two patients in group A and 5 patients in group B presented with redness and swelling of the surgical site, 1 patient in group B sustained a tibial tunnel fracture, and 1 patient in group A had postoperative stiffness. The Lysholm score, IKDC score, and Tegner score were significantly higher in group A than in group B at the different time points ( P<0.05) except for the Tegner score at 3 months. The outcomes of KT-1000 measurement were significantly lower in group A than in group B ( P<0.05). The entrances of the femoral tunnel and tibial tunnel in both groups were within the ACL anatomical footprint confirmed by 3D-CT. No re-rupture of ACL occurred confirmed by the MRI. There was no significant difference in SNQs of the middle and distal grafts between the two groups at 6 months ( P>0.05), whereas the SNQ of the proximal grafts in group A was significantly lower than that in group B ( P<0.05). The SNQs of the proximal, middle, and distal grafts in group A were significantly lower than those in group B at 12 and 24 months after operation ( P<0.05). Twenty-one patients in group A and 38 patients in group B underwent secondary arthroscopy and the results showed no significant difference in graft status, synovial coverage, and tension between the two groups ( P>0.05).

CONCLUSION

The effectiveness and graft maturity of the femoral oval tunnel technique were superior to the round tunnel technique. The single-bundle ACL reconstruction with femoral oval tunnel technique can obtain a better knee function.

Anatomical single bundle anterior cruciate ligament reconstruction with rounded rectangle tibial tunnel and oval femoral tunnel: a prospective comparative study versus conventional surgery

Conventional anatomical single bundle anterior cruciate ligament (ACL) reconstruction technique with round tunnels could not simulate morphology of native insertion, while studies about ACL reconstruction technique with modified tunnels based on morphology of anatomical insertion are rare. The purpose of this study was to demonstrate an ACL reconstruction technique with rounded rectangle tibial tunnel and oval femoral tunnel and compare clinical outcomes with conventional technique. A prospective comparative study was performed in 80 consecutive subjects who underwent ACL reconstruction with the conventional round tunnels (RT-Group, n=40) or modified tunnels (MT-Group, n=40). For the modified surgery, the tunnel was modified with a bone file based on the anatomical direction and area of the remnant insertion fibers. Graft maturity were evaluated by MR images at 12 months postoperatively and patients were examined for functional scores, physical examinations at 2-year follow-up. The primary variable was the pivot-shift test. No serious complications were experienced in either group. Seventy patients (87.5%) were examined at 2-year follow-up, significant improvements were seen in both groups compared with the preoperative values in terms of all clinical assessments. Tegner scores, pivot-shift test results and SNQ value in the MT-Group were significantly better than RT-Group (P=0.04, P=0.03 and P=0.001, respectively). There were no significant differences in Lysholm scores, IKDC scores, KT-2000 measurements and Lachman tests. We successfully developed the ACL reconstruction technique with rounded rectangle tibial tunnel and oval femoral tunnel, which was superior to conventional technique in terms of postoperative Tegner scores, pivot-shift tests and early graft maturity.

Measurement of the Whole and Midsubstance Femoral Insertion of the Anterior Cruciate Ligament: The Comparison with the Elliptically Calculated Femoral Anterior Cruciate Ligament Footprint Area

PURPOSE

The purpose of this study was to measure the detailed morphology of the femoral anterior cruciate ligament (ACL) footprint. The correlation and the comparison between the measured area and the area which mathematically calculated as elliptical were also evaluated.

MATERIALS AND METHODS

Thirty nine nonpaired human cadaver knees were used. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the whole footprint and the midsubstance insertion. Lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The area, length, and width of the femoral ACL footprint were measured with Image J software (National Institution of Health). Using the length and width of the femoral ACL footprint, the elliptical area was calculated as 0.25 π (length × width). Statistical analysis was performed to reveal the correlation and the comparison of the measured and elliptically calculated area.

RESULTS

The sizes of the whole and midsubstance femoral ACL footprints were 127.6 ± 41.7 mm² and 61 ± 20.2 mm², respectively. The sizes of the elliptically calculated whole and midsubstance femoral ACL footprints were 113.9 ± 4.5 mm² and 58.4 ± 3 mm², respectively. Significant difference was observed between the measured and the elliptically calculated area. In the midsubstance insertion, significant correlation was observed between the measured and the elliptically calculated area (Pearson's correlation coefficient = 0.603, P = 0.001). However, no correlation was observed in the whole ACL insertion area.

CONCLUSION

The morphology of the femoral ACL insertion resembles an elliptical shape. However, due to the wide variation in morphology, the femoral ACL insertion cannot be considered mathematically elliptical.

No difference in the graft shift between a round and a rounded rectangular femoral tunnel for anterior cruciate ligament reconstruction: an experimental study

INTRODUCTION

We developed a novel technique of creating a rounded rectangular femoral bone tunnel for anatomical, single-bundle, autologous hamstring tendon anterior cruciate ligament (ACL) reconstruction. Although this tunnel has many advantages, its non-circular shape has raised concerns regarding excessive graft shift within the bone tunnel. This study aimed to compare the graft shift between round and rounded rectangular tunnels using a graft diameter tester for simulating the femoral bone tunnel.

MATERIALS AND METHODS

Seven semitendinosus tendon grafts harvested from fresh-frozen cadavers were prepared by removing all excess soft tissue. The two ends of a double-fold hamstring tendon were sutured using a baseball stitch and then looped over a TightRope (Arthrex Co., Ltd., Naples, Florida, USA) to make a fourfold graft. The diameter of the graft was standardized to 8 mm using a round graft diameter tester. A round and an original rounded rectangular graft diameter tester were used for simulating the respective femoral bone tunnels. The graft was inserted into the tunnel, with the TightRope positioned on the outside of the tunnel. The distal end of the graft was tensioned to 40 N at an angle of 75° to reproduce the most severe graft bending angle. Digital photographs of the tunnel aperture taken at each simulated tunnel and the range of graft shift in the simulated tunnel were analyzed by ImageJ software. Statistical analyses were performed using the Tukey test. P < 0.05 was considered to be significant.

RESULTS

There were no significant differences between the round and the rounded rectangular tunnel groups (P > 0.05) in terms of graft shift, gap area, and graft shift ratio.

CONCLUSION

In a simulated ACL reconstruction, there is no difference in the graft shift between a round and a rounded rectangular bone tunnel.