Effect of tunnel-graft length on the biomechanics of anterior cruciate ligament-reconstructed knees: intra-articular study in a goat model

Freehand vs. Medial Portal Offset Aimer Technique for Accurate Femoral Tunnel Placement in Arthroscopic ACL Reconstruction

Purpose

In this study, our aim was to reveal the effect of the medial femoral offset aimer usage through the femoral tunnel entry and exit points and the tunnel length during femoral tunnel drilling in arthroscopic anterior cruciate ligament (ACL) reconstruction.

Methods

One hundred patients who underwent arthroscopic single-bundle ACL reconstruction were included in the study. Group 1 consisted of 50 patients who underwent femoral tunnel drilling using a medial portal offset aimer device, while Group 2 consisted of 50 patients who were operated on using the freehand technique. Both groups were compared in terms of femoral tunnel and graft tunnel lengths, femoral tunnel angle in the coronal plane, and the location of the femoral tunnel entry and exit points.

Results

The mean femoral tunnel and graft tunnel lengths were significantly longer in Group 2 (p = 0.000). There was no significant difference in terms of localization of the femoral tunnel entry point in both the axial and sagittal planes. The tunnel exit point was located significantly more posterior in Group 1 in the axial plane (p = 0.028). There was no significant difference in terms of the coronal plane femoral tunnel angle between the two groups.

Conclusion

In arthroscopic ACL reconstructions, more successful results may be obtained with the freehand technique compared to drilling with a femoral offset aimer. For an experienced orthopedic surgeon, using a medial portal offset aimer device during femoral tunnel drilling does not seem necessary.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-023-00929-z.

Intra-femoral tunnel graft lengths less than 20 mm do not predispose to early graft failure, inferior outcomes or poor function. A prospective clinico-radiological comparative study

PURPOSE

Increasing demands on skills with mounting pressures from expectations from arthroscopic anterior cruciate ligament (ACL) reconstructions requires precise knowledge of technical details by surgeons. One such element is the minimum length of graft in femoral tunnel to allow for adequate tendon-to-bone healing and early return to activities and sports. This has, however, remained an unanswered question.

PURPOSE

To study and compare clinico-radiological outcomes of ACL reconstructions in patients with < 20 mm of intra-femoral tunnel graft length with those measuring ≥ 20 mm.

METHODS

All eligible patients undergoing arthroscopic ACL reconstruction were sequentially divided into two groups based on the intra-femoral tunnel graft lengths (A: < 20 mm, n = 27; and B: ≥ 20 mm, n = 25). Exclusions were made for those > 45 years of age, with chondral and/or multi-ligamentous injuries and with systemic pathologies. All patients were postoperatively evaluated in clinics by physical examination and functional scoring (Lysholm and modified Cincinnati scores) at 3, 6 and 12-month intervals. Graft vascularity was assessed by signal-to-noise quotient ratio (SNQR) using magnetic resonance imaging (MRI) at 3 and 12 months.

RESULTS

No significant differences were noted in mean Lysholm and modified Cincinnati scores between the two groups at the end of 1 year. There were also no significant differences in graft maturation over time and SNQR at 3 and 12 months in the region of interest (ROI).

CONCLUSIONS

Intra-femoral tunnel graft length of less than 20 mm does not compromise early clinical and functional outcomes of ACL reconstructions.

Anterior Cruciate Ligament Reconstruction Using a 4-Strand Semitendinosus Tendon Graft or a Doubled Semitendinosus and Gracilis Tendon Graft: A 4.5-Year Prospective, Randomized, Double-Blind, Parallel-Group Study

BACKGROUND

Hamstring tendon grafts are the most common choice for anterior cruciate ligament (ACL) reconstruction (ACLR). Previous studies have provided evidence that offers conflicting opinions concerning the most favorable graft choice.

PURPOSE

To identify whether the use of a quadrupled semitendinosus tendon (ST) or doubled semitendinosus tendon and gracilis tendon (ST/G) graft provides comparable anterior tibial translation (ATT) with similar functional results and similar donor site morbidity.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

This was a prospective, patient- and surgeon-blinded, randomized trial set in a busy orthopaedic and traumatology department at a university hospital. Between 2015 and 2017, a total of 162 patients with ACL lesions were randomized to undergo ACLR with either a quadrupled ST or doubled ST/G graft. The primary endpoint was ATT assessed with the KT-1000 arthrometer. Clinical outcomes were assessed using the patient-reported outcome measures (PROMs) of the visual analog scale (VAS), International Knee Documentation Committee (IKDC) subjective evaluation form, Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner activity scale, and Lysholm knee scoring scale.

RESULTS

Preoperative demographic data, ATT, and PROM scores showed no significant differences. At 4.5 years, no significant differences were found between the ST and ST/G groups with respect to PROM scores and KT-1000 arthrometer, Lachman test, and pivot-shift test findings. Differences in functional results between groups were significant (muscle strength). Subgroup analysis revealed significantly increased ATT in female patients undergoing ACLR with a quadrupled ST graft during the 4.5-year observation period, as assessed by the KT-1000 arthrometer, as well as inferior KOOS, IKDC, Lysholm, and VAS scores.

CONCLUSION

This study showed a significant increase in ATT as well as inferior results on PROMs during a 4.5-year observation period in female patients undergoing ACLR with a quadrupled ST graft. In male patients, the study provided evidence of the noninferiority of ACLR with an ST graft, with no influence on donor site morbidity.

TRIAL REGISTRATION

clinicaltrials.gov: NCT03626883.

Biomechanical Comparison of Anatomic Versus Lower of Anteromedial and Anterolateral Tibial Tunnels in Posterior Cruciate Ligament Reconstruction

OBJECTIVE

In order to reduce the "killer turn" effect, various tibial tunnels have been developed. However, few studies investigated the biomechanical effects of different tibial tunnels during PCL reconstruction. This study aims to compare the time-zero biomechanical properties of anteromedial, anterolateral, lower anteromedial, and lower anterolateral tibial tunnels in transtibial posterior cruciate ligament (PCL) reconstruction under load-to-failure loading.

METHODS

Porcine tibias and bovine extensor tendons were used to simulate in vitro transtibial PCL reconstruction. Forty bovine extensor tendons and 40 porcine tibias were randomly divided into four experimental groups: anteromedial tunnel group (AM group, n = 10), anterolateral tunnel group (AL group, n = 10), lower anteromedial tunnel group (L-AM group, n = 10), and lower anterolateral tunnel group (L-AL group, n = 10). The biomechanical test was then carried out in each group using the load-to-failure test. The ultimate load (in newtons), yield load (in newtons), tensile stiffness (in newtons per millimeter), load-elongation curve, failure mode, and tibial tunnel length (in millimeter) were recorded for each specimen. One-way analysis of variance (ANOVA) was used to compare the mean differences among the four groups.

RESULTS

The biomechanical outcomes showed that there were no differences in the mean tensile stiffness and failure mode among four groups. The ultimate load and yield load of the L-AM group were significantly higher than those of other three groups (P < 0.05). For the AM group, its ultimate load is significantly higher than that of the L-AL group (P < 0.05), and its yield load is higher than that of the AL group and L-AL group (P < 0.05). However, we found no significant differences in either ultimate load or yield load between AL group and L-AL group (P > 0.05). There was significant statistical difference in the length of tibial tunnel between anatomic groups (AM and AL) and lower groups (L-AM and L-AL) (P < 0.05).

CONCLUSION

Compared with the anteromedial, anterolateral, and lower anterolateral tibial tunnel, the lower anteromedial tibial tunnel showed better time-zero biomechanical properties including ultimate load and yield load in transtibial PCL reconstruction.

Short graft anterior cruciate ligament reconstruction: Current concepts

Short graft anterior cruciate igament reconstruction is increasing in popularity for performing a primary ACLR. The short graft coupled with the all-inside technique using closed sockets and suspensory fixation at both femoral and tibial ends are its defining features. The outcomes of this technique have been comparable to well established transportal ACLR techniques. It has the benefits of preserved hamstring strength and less pain attributed to transtibial drilling. However, there is a learning curve involved and will require time before mastery of the technique. Furthermore, in combined osteotomy or multiligament surgery, the use of short graft anterior cruciate ligament reconstruction with sockets preserve bone stock and the single tendon harvest spares the other tendons for use in other ligament reconstruction.

A balance between native footprint coverage and overlap of the anterolateral meniscal root in tibial tunnel positioning during anterior cruciate ligament reconstruction: A 3D MRI study

BACKGROUND

Tibial footprint of anterior cruciate ligament (ACL) is situated close to the anterior lateral meniscal root (ALMR) attachment.

PURPOSE

To investigate the impact of the size and location of the tibial tunnel for ACL reconstruction on the ACL footprint coverage and overlap to the ALMR.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty knee MRI scans from twenty healthy subjects were recruited, and three-dimensional (3D) tibia models were created to show the tibial attachment sites of ACL and ALMR. Surgical simulation of the tibial tunnel drilling was performed on each 3D model, entering the joint at an angle set at 60 degrees from the tibial plateau plane and 55 degrees from the posterior tibial condylar axis, with analysis for six different drill sizes; 7.5, 8, 8.5, 9, 9.5 and 10 mm; and nine locations; the center of the ACL attachment and eight locations 2% of the tibial width apart surrounding it. The width of the tibial plateau, the distance between ACL and ALMR attachment centers, and the size and location of the potential tibial tunnel were evaluated to determine association with the area of the ACL footprint coverage and ALMR overlap using a linear mixed effects model.

RESULTS

A large tunnel (p <.001), a central and anterior location (p <.029), and small tibial width (p =.015) were all associated with larger coverage of the ACL footprint. A large tunnel (p <.001), posteriorly and laterally located (p ≤ 0.001), and a small distance between the ACL and ALMR centers (p =.001) were significantly associated with a larger ALMR overlap. The association of the tunnel size to ALMR overlap reduced with a medial tunnel location.

CONCLUSIONS

The short distance between the centers of the ALMR attachment and native ACL footprint suggests that the ALMR will always be susceptible to overlap when the tibial tunnel is drilled in ACL reconstruction. Small alterations in tunnel location can lead to a statistically significant alteration with the amount of ALMR overlap. To minimize this overlap, whilst maintaining acceptable coverage of the ACL footprint, a tibial tunnel positioned in a medial or anteromedial location from the center of the ACL footprint is recommended.

Hamstring autograft utilization in reconstructing anterior cruciate ligament: Review of harvesting techniques, graft preparation, and different fixation methods

Rupture of the anterior cruciate ligament (ACL) is a common orthopedic injury. Various graft options are available for the reconstruction of ruptured ACL. Using the hamstring muscle as an autograft was first described in 1934, and it remains a commonly harvested graft for ACL reconstruction. Hamstring autografts can be harvested using the traditional anteromedial approach or the newer posteromedial technique. An isolated semitendinosus tendon can be used or combined with the gracilis tendon. There are numerous methods for graft fixation, such as intra-tunnel or extra-tunnel fixation. This comprehensive review discusses the different hamstring muscle harvesting techniques and graft preparation options and fixation methods. It provides a comprehensive overview for choosing the optimal surgical technique when treating patients.

Estimating the adequacy of the free quadriceps tendon autograft length using anthropometric measures in anterior cruciate ligament reconstruction

OBJECTIVE

This prospective study aimed to predict the adequacy of free quadriceps tendon (QT) autograft length using simple anthropometric measures.

MATERIALS AND METHODS

One hundred and eighty-four consecutive patients who underwent knee high-resolution MRI were enrolled in this study. The QT and native anterior cruciate ligament (ACL) length were measured using the oblique sagittal section. The adequate free QT length was calculated using the native ACL length and 30 mm for femoral and tibial tunnels in each patient. A QT shorter than the calculated length was considered inadequate. Age, sex, height, weight, body mass index, thigh circumference, and activity score were used to predict the adequacy of QT length with regression analysis.

RESULTS

There were 92 men and 92 women with a mean age of 34.1 ± 8.0 years (range 18-45). The mean QT and ACL lengths were 69.0 ± 8.8 mm (range 48.1-90.3 mm) and 35.6 ± 2.5 mm (range 29.2-42.6 mm), respectively. The QT and the ACL lengths were longer in men (p < 0.001 for both). Twenty-three men and 39 women (total: 62, 33.7%) had inadequate QT length for a free QT autograft, and 6 patients (3 males, 3 females, 3.3%) had inadequate QT length with the bone block technique. There was a weak positive correlation between QT length and height (p < 0.001), weight (p < 0.001), and activity score (p = 0.007). Height was the only independent variable that predicted the QT length adequacy (r² = 0.051, p = 0.009) but ROC analysis showed that height did not have an ability to detect a subject with an inadequate QT length (AUC: 0.384, 95% CI 0.300-0.468).

CONCLUSIONS

Free QT autografts may be inadequate in one-third of the patients, while a QT autograft with a bone block is almost always sufficient. Inadequate free QT autograft is more common in women. Although QT length correlated with height, it cannot be used as an accurate diagnostic tool to identify patients with an inadequate QT autograft. Preoperative measurement of the ACL and QT lengths by MRI might be beneficial to decide whether QT is usable, especially when harvesting without a bone block.

LEVEL OF EVIDENCE

Level II, diagnostic, prospective cohort study.

An Anatomically Placed Tibial Tunnel does not Completely Surround a Simulated PCL Reconstruction Graft in the Proximal Tibia

INTRODUCTION

 It is hypothesized that anatomic tunnel placement will create tunnels with violation of the posterior cortex and subsequently an oblique aperture that is not circumferentially surrounded by bone. In this article, we aimed to characterize posterior cruciate ligament (PCL) tibial tunnel using a three-dimensional (3D) computed tomography (CT) model.

METHODS

 Ten normal knee CTs with the patella, femur, and fibula removed were used. Simulated 11 mm PCL tibial tunnels were created at 55, 50, 45, and 40 degrees. The morphology of the posterior proximal tibial exit was examined with 3D modeling software. The length of tunnel not circumferentially covered (cortex violation) was measured to where the tibial tunnel became circumferential. The surface area and volume of the cylinder both in contact with the tibial bone and that not in contact with the tibia were determined. The percentages of the stick-out length surface area and volume not in contact with bone were calculated.

RESULTS

 The mean stick-out length of uncovered graft at 55, 50, 45, and 40 degrees were 26.3, 20.5, 17.3, and 12.7 mm, respectively. The mean volume of exposed graft at 55, 50, 45, and 40 degrees were 840.8, 596.2, 425.6, and 302.9 mm³, respectively. The mean percent of volume of exposed graft at 55, 50, 45, and 40 degrees were 32, 29, 25, and 24%, respectively. The mean surface of exposed graft at 55, 50, 45, and 40 degrees were 372.2, 280.4, 208.8, and 153.3 mm², respectively. The mean percent of surface area of exposed graft at 55, 50, 45, and 40 degrees were 40, 39, 34, and 34%, respectively.

CONCLUSION

 Anatomic tibial tunnel creation using standard transtibial PCL reconstruction techniques consistently risks posterior tibial cortex violation and creation of an oblique aperture posteriorly. This risk is decreased with decreasing the angle of the tibial tunnel, though the posterior cortex is still compromised with angles as low as 40 degrees. With posterior cortex violation, a surgeon should be aware that a graft within the tunnel or socket posteriorly may not be fully in contact with bone. This is especially relevant with inlay and socket techniques.

Effects of flexible reamer on the femoral tunnel characteristics in anterior cruciate ligament reconstruction

To compare the femoral tunnel characteristics using a rigid versus flexible reamer during anterior cruciate ligament reconstruction. It was hypothesized that the employment of a flexible reamer along with femoral tunnel would exhibit longer tunnel length and more acute femoral graft tunnel angle compared to the case of a rigid reamer.The study population included 28 patients who underwent anatomical single-bundle anterior cruciate ligament reconstruction using transportal technique and were able to take postoperative computed tomography (CT) evaluation. Of these, the femoral tunnel of 14 cases was drilled with a flexible reamer (group I) and in another 14 cases drill was performed with a conventional rigid reamer (group II). The femoral tunnel in group I was made at 90° of knee flexion. In group II, the femoral tunnel was created at 120° of knee flexion. The parameters of the femoral tunnels were compared in terms of the femoral tunnel length and femoral graft tunnel angle. Special software was used to create and manipulate (3-D) 3-dimensional knee models.The difference in the mean femoral tunnel locations expressed in percentage distance between the 2 groups was not significantly different. The mean femoral tunnel length of group I was significantly longer than that of group II, (P = .03, 36.7 ± 2.9 vs 32.9 ± 9.0 mm). The angle formed by the femoral tunnel and the graft in group I was significantly smaller than in group II (P = .01, 109.8° ± 9.4° vs 118.1° ± 7.2°).Our data suggest that the flexible reamer can provide sufficient tunnel length for the suspensory fixation with a fixed loop. Whereas, the femoral graft-tunnel angle through flexible reaming at 90° of knee flexion was more acute compared to rigid reaming at 120° of knee flexion.Study Design: level of evidence III.

The Graft Insertion Length in the Femoral Tunnel During Anterior Cruciate Ligament Reconstruction With Suspensory Fixation and Tibialis Anterior Allograft Does Not Affect Surgical Outcomes but Is Negatively Correlated With Tunnel Widening

PURPOSE

To investigate the surgical outcomes of anterior cruciate ligament (ACL) reconstruction using a low-dose irradiated tibialis anterior allograft with a fixed-loop cortical suspension device for the femur based on the graft insertion length (GIL) in the femoral tunnel.

METHODS

Between January 2010 and January 2018, the medical records of consecutive patients who underwent arthroscopic ACL reconstruction with a tibialis anterior allograft fixed with the EndoButton CL for the femur and who had at least 2 years of follow-up were retrospectively evaluated. Patients were classified into 3 groups based on the GIL in the femoral tunnel (group 1, GIL < 15 mm; group 2, GIL of 15-20 mm; and group 3, GIL > 20 mm), and their functional scores, knee laxity, and radiographic parameters were evaluated.

RESULTS

A total of 91 patients were analyzed. There were no statistically significant differences in the functional scores and knee laxity between the 3 groups at 2 years postoperatively. However, significant differences were observed in tunnel widening at 1 year postoperatively in the femur (P = .045 for absolute value and P = .004 for relative value) and the tibia (P = .014 for absolute value and P = .012 for relative value), revealing that both the femoral and tibial tunnels widened as the GIL decreased. Additional linear regression analyses were performed to identify whether the GIL independently affects tunnel widening. Consequently, the femoral tunnel depth, tunnel diameter, and GIL were found to independently influence femoral tunnel widening (P = .008, P = .019, and P < .001, respectively), whereas the tunnel diameter and GIL affected tibial tunnel widening (P < .001 and P = .004, respectively).

CONCLUSIONS

The GIL in the femoral tunnel during ACL reconstruction using a tibialis anterior allograft with a fixed-loop cortical suspension device for the femur has no significant association with the postoperative functional outcomes and knee laxity, but it has a negative correlation with tunnel widening in the femur and the tibia.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Patients with a quadriceps tendon shorter than 60 mm require a patellar bone plug autograft in anterior cruciate ligament reconstruction

PURPOSE

To assess the length and thickness of the quadriceps tendon (QT) and anterior cruciate ligament (ACL) to predict the required QT length for individual ACL reconstruction.

METHODS

Thirty patients (9 females, 21 males; mean age 24.5 years; mean height 169.3 cm) who underwent ACL reconstruction using the QT with a bone plug autograft were enrolled. The length and thickness of the QT on preoperative magnetic resonance imaging (MRI) were compared with those measured under direct visualization. The ACL length was measured on preoperative MRI and three-dimensional computed tomography after ACL reconstruction. The QT length on MRI was compared with the required graft length, and the factors related to an adequate QT length were assessed.

RESULTS

The mean QT length on MRI was 60.8 ± 1.3 mm and was significantly positively correlated with the QT length under direct visualization (P < 0.01). On MRI, the mean ACL length was 30.8 ± 1.2 mm and the mean QT thickness was 6.3 ± 0.2 mm. Although the mean QT was 0.1 mm longer than the mean required graft length, the QT on MRI was shorter than the required graft length in 37% of patients (11/30). Adequate QT length was related to a QT length of more than 60 mm, but not to age, sex, height, or ACL length.

CONCLUSION

Although preoperative MRI predicted the required QT length for ACL reconstruction, 37% of patients lacked an adequate QT length, and a QT shorter than 60 mm required the addition of patellar bone.

LEVEL OF EVIDENCE

III.

Outcomes of retro-drilled all-inside tibial tunnel vs complete tibial tunnel techniques in anterior cruciate ligament reconstruction-a comparative study

PURPOSE

The all-inside tibial tunnel preparation technique of arthroscopic anterior cruciate ligament (ACL) reconstruction differs from traditional complete tibial tunnel technique in using closed tibial sockets, dual-cortical suspensory graft-fixation, quadrupled semitendinosus tendon graft and lesser bone removal. The study aims to find out if all-inside technique differs from complete tibial tunnel technique of single bundle ACL reconstruction in terms of graft dimensions, functional and clinical outcomes.

METHODS

A prospective comparative study was conducted including 80 patients with isolated ACL tears, divided into 2 groups of 40 patients each without any randomization. The two techniques differed in tibial tunnel preparation. Group 1 underwent ACL reconstruction with a complete tibial tunnel drilled from the anteromedial tibial cortex and group 2 underwent all-inside tibial socket preparation. Duration of the surgery, perioperative and midterm complications were noted. All patients had 24 month follow-up. Functional outcome scores (Tegner-Lysholm knee scoring scale and IKDC score) were assessed preoperatively and postoperatively at 6 months and 24 months. Hamstring and quadriceps muscle strength was assessed preoperatively and postoperatively at 6 months, 9 months and 24 months. Visual analogue score (VAS) for knee pain was assessed preoperatively and postoperatively at day 2, 2 weeks, 6 weeks, 6 months and 24 months.

RESULTS

Quadrupled semitendinosus tendon graft was significantly thicker than doubled semitendinosus and gracilis tendons graft (8.17 ± 0.58 vs 8.71 ± 0.4, p < 0.0001). The VAS score for knee pain at 2 and 6 weeks were lower in group 2 (5.75 ± 0.6 and 1.78 ± 1.0) as compared to group 1 (6.50 ± 0.5 and 2.5 ± 0.8) and the difference was statistically significant (P = 0.0007 and p = 0.002 respectively). There were no statistically significant differences in functional outcome scores and quadriceps muscle strength between the two groups. However, there were significant difference in hamstring power in two groups.

CONCLUSION

The all-inside technique has the advantages of using a single tendon graft, lesser early postoperative pain with similar clinical and functional outcomes compared to the complete tibial tunnel technique. Level of Evidence IIProspective comparative study.

In vivo three-dimensional knee kinematics in goats with unilateral anterior cruciate ligament transection

Although the goat is an established animal model in anterior cruciate ligament (ACL) research, in vivo kinematics associated with ACL deficiency have not been previously described in this species. Three-dimensional knee kinematics were determined before and after unilateral ACL transection in eight goats. Fluoroscopic imaging of the knees during treadmill walking and force-platform gait analysis during over-ground walking were performed prior to ACL transection, and 2 weeks, 3 months, and 6 months after ACL transection. Transient lameness of the ACL-transected limb was noted in all goats but resolved by 3 months post-ACL transection. Increased extension of 8.7° to 17.0° was noted throughout the gait cycle in both the ACL-transected and the contralateral unaffected knees by 3 months post-ACL transection, in a bilaterally symmetric pattern. Peak anterior tibial translation increased by 3 to 6 mm after ACL transection and persisted over the 6-month study period. No changes in axial rotation or abduction angle were observed after ACL transection. Unilateral ACL deficiency in goats resulted in persistent kinematic alterations, despite the resolution of lameness by 3 months post-ACL transection.

Gracilis and semitendinosus moment arm decreased by fascial tissue release after hamstring harvesting surgery: a key parameter to understand the peak torque obtained to a shallow angle of the knee

PURPOSE

Semitendinosus and gracilis muscles whose tendons are used in surgical reconstruction of the anterior cruciate ligament maintain their contractile ability, but the peak torque angle of hamstring muscles shifted to a shallow angle postoperatively. The goal was to quantify the influence of the myofascial structures on instantaneous moment arms of knee muscles to attempt explaining the above-mentioned post-surgical observations.

METHODS

Hamstring harvesting procedures were performed by a senior orthopaedic surgeon on seven lower limbs from fresh-frozen specimens. Femoro-tibial kinematics and tendons excursion were simultaneously recorded at each step of the surgery.

RESULTS

No significant difference was demonstrated for instantaneous moment arm of gracilis during anterior cruciate ligament surgery (84% of the maximum intact values; P ≥ 0.05). The first significant semitendinosus moment arm decrease was observed after tendon harvesting (61% of the maximum intact values; p ≤ 0.005). After hamstring harvesting, the maximum and minimum moment arm (both gracilis and semi tendinosus) shifted to a shallow angle and 90°, respectively.

CONCLUSION

Moment arm modifications by paratenons and the loose connective tissue release are essential to understand the peak torque obtained to a shallow angle.

LEVEL OF EVIDENCE

Basic science study, biomechanics.

Femoral tunnel length has no correlation with graft rupture: A retrospective cohort study

BACKGROUND

Literature is controversial on femoral tunnel length as a risk factor for graft injury if the graft length in the tunnel is kept constant at ≥15 mm.

METHODS

A total of 1079 sportspersons, meeting our inclusion criteria, were assessed for graft rupture. Patients with femoral tunnel length (FTL) ≤30 mm were labeled as Group 1, while those with FTL > 30 mm were labeled as Group 2. Both groups were compared for potential risk factors for graft injury keeping graft length in the tunnel at ≥15 mm and statistical analysis was performed to study whether the femoral tunnel length acted as an additional risk factor.

RESULTS

Of 1079 sportspersons, 37 suffered from graft rupture. Patients with FTL > 30 mm were included in Group 1(n = 22) and patients with FTL ≤ 30 mm (n = 15) were included in Group 2. Both groups were comparable for risk factors for ACL injury: age (P = 0.37), gender (P = 0.53), mode of re-injury (P = 0.38), graft diameter (P = 0.71), level of sports activity (P = not significant), duration from injury to index surgery (P = 0.74), duration from index surgery to re-injury (P = 0.52), timing of return to sports after index surgery (P = 0.30), duration of sporting activity before second injury (P = 0.31), Tegner's level (P = not siginificant), Notch width index (P = 0.12) posterior slope (P = 0.77) and height (P = 0.41).

CONCLUSION

Because the graft length in the tunnel was kept at optimum and the risk factors for ACL injury were comparable in both groups at a follow up period, we suggest that femoral tunnel length is not a risk factor for graft failure.

Biomaterials developed for facilitating healing outcome after anterior cruciate ligament reconstruction: Efficacy, surgical protocols, and assessments using preclinical animal models

Anterior cruciate ligament (ACL) reconstruction is the recommended treatment for ACL tear in the American Academy of Orthopaedic Surgeons (AAOS) guideline. However, not a small number of cases failed because of the tunnel bone resorption, unsatisfactory bone-tendon integration, and graft degeneration. The biomaterials developed and designed for improving ACL reconstruction have been investigated for decades. According to the Food and Drug Administration (FDA) and the International Organization for Standardization (ISO) regulations, animal studies should be performed to prove the safety and bioeffect of materials before clinical trials. In this review, we first evaluated available biomaterials that can enhance the healing outcome after ACL reconstruction in animals and then discussed the animal models and assessments for testing applied materials. Furthermore, we identified the relevance and knowledge gaps between animal experimental studies and clinical expectations. Critical analyses and suggestions for future research were also provided to design the animal study connecting basic research and requirements for future clinical translation.

How to Achieve an Accurate Anatomical Femoral Tunnel Technique in ACL Reconstruction in the Early Years of Your Consultancy? Femoral Offset Aimer Technique: Consistent and Reproducible Technique

Femoral tunnel malposition is the most common reason for failure of primary anterior cruciate ligament reconstruction. There are several methods to identify the anatomical location of femoral footprint. Femoral offset aimer technique is one such technique which is easy to use and reliable. It is an ideal technique for junior and inexperienced surgeons to recreate the femoral tunnel in its anatomical footprint. The senior author (P.E.) has been using this technique for 30 consecutive cases in his first year of independent practice during his consultancy without any major intraoperative complications. The author describes this technique in this article with tips and tricks which will especially guide the junior and inexperienced surgeons to avoid running into intraoperative problems while drilling the femoral tunnel.

Intraoperative fluoroscopy shows better agreement and interchangeability in tibial tunnel location during single bundle anterior cruciate ligament reconstruction with postoperative three-dimensional computed tomography compared with an intraoperative image-free navigation system

BACKGROUND

Fluoroscopy and navigation systems provide an accurate and reproducible method of guiding anatomical tunnel positioning during anterior cruciate ligament reconstruction (ACLR). The aim was to evaluate the differences in tibial tunnel location assessed by both an intraoperative navigation system and fluoroscopy, validated using a one-week postoperative three-dimensional computed tomography (3DCT).

METHODS

The tibial tunnel location in a consecutive series of 35 patients who received a single-bundle ACLR was evaluated by intraoperative navigation system, fluoroscopic image and compared with postoperative 3DCT position. The location to the anterior-posterior (AP) and medial-lateral (ML) direction were compared between all three methods.

RESULTS

The tibial tunnel locations were 46.7 ± 4.5%, 44.5 ± 1.9%, and 43.6 ± 2.4% in ML direction, and 42.8 ± 7.6%, 37.9 ± 3.8%, and 37.9 ± 3.7% in AP direction using an intraoperative navigation system, fluoroscopic image and postoperative 3DCT, respectively. Significant differences between the navigation system and fluoroscopic image (ML, P = 0.001; AP, P = 0.006), and the navigation system and 3DCT (ML, P = 0.001; AP, P < 0.001) were seen. However, there was no significant difference between fluoroscopy and 3DCT (ML, P = 0.315; AP, P = 0.999). There was a significant lack of agreement for analyses measured using a navigation system and 3DCT. Fluoroscopy and 3DCT demonstrated an acceptable agreement (ML, r_pt = -0.21, P = 0.232; AP, r_pt = 0.04, P = 0.826).

CONCLUSIONS

A tibial tunnel location assessed by intraoperative fluoroscopy shows better agreement and interchangeability with one-week postoperative 3DCT validation during single-bundle ACLR compared with an intraoperative image-free navigation system.

Techniques for Femoral Socket Creation in ACL Reconstruction

Anterior cruciate ligament (ACL) injury is common and affects a wide variety of individuals. An ACL reconstruction is the treatment of choice for patients with subjective and objective symptoms of instability and is of particular importance to cutting or pivoting athletes. With many variables involved in ACL reconstruction, femoral tunnel placement has been found to affect clinical outcomes with nonanatomic placement being identified as the most common technical error. Traditionally the femoral tunnel was created through the tibial tunnel or transtibial with the use of a guide and a rigid reaming system. Because of proximal, nonanatomic tunnel placement using the transtibial technique, the use of the anteromedial portal and outside-in drilling techniques has allowed placement of the tunnel over the femoral footprint. In this paper, we discuss the difference between the 3 techniques and the advantages and disadvantages of each. The authors then explore the clinical differences and outcomes in techniques by reviewing the relevant literature.

A two-portal technique using a flexible reamer system is a safe and effective method for transportal anterior cruciate ligament reconstruction

INTRODUCTION

A flexible reamer system (FRS) for transportal anterior cruciate ligament reconstruction (ACLR) has been developed to overcome the technical challenges of a rigid reamer system. The purpose of this study was to investigate the safety and effectiveness of the two-portal technique using an FRS by evaluating femoral tunnel geometry.

METHODS

This study included 30 patients (mean age 30 ± 12.1) who underwent transportal single-bundle ACLR. Operations were performed with the two-portal technique using an FRS. Three-dimensional computed tomography was performed for all patients 2 days after the operation. The femoral tunnel position, femoral graft bending angle, femoral tunnel length, and posterior wall breakage were evaluated. These radiologic outcomes were compared to previous literature-reported outcomes.

RESULTS

The mean distances (measured as a percentage) from the posterior wall and the intercondylar notch roof to the femoral tunnel center were 29.6 ± 5.5% and 20.1 ± 6.7%, respectively. The femoral graft bending angle (108.4° ± 6.9°) was similar to that associated with the traditional transportal technique using a rigid reamer system, but it was less acute than that associated with the three-portal technique using an FRS. The femoral tunnel length (32.8 ± 4.5 mm) was also similar to the results of the traditional transportal technique using a rigid reamer system, but it was shorter than that of three-portal technique using an FRS. The prevalence of posterior wall breakage was as low as the reported outcomes of the outside-in technique (2 cases, 6.6%).

CONCLUSIONS

The two-portal technique for transportal ACLR using an FRS can achieve comparable femoral graft bending angle and femoral tunnel length compared with the conventional three-portal technique using the rigid reamer system and had a low risk of posterior wall breakage. Therefore, the two-portal technique using the FRS can be considered a safe and effective method for transportal ACLR.

LEVEL OF EVIDENCE

Retrospective case series; level of evidence, 4.

ACL hamstring grafts fixed using adjustable cortical suspension in both the femur and tibia demonstrate healing and integration on MRI at one year

PURPOSE

To present the clinical outcomes and magnetic resonance imaging (MRI) analysis of adjustable cortical suspensory fixation for the femur and tibia in hamstring autograft anterior cruciate ligament reconstruction.

METHODS

A cohort of 233 sequential patients was analysed for graft failure rate and subjective IKDC, Tegner and Lysholm scores. 144 validated 1-year MRIs assessed and correlated graft healing and tunnel widening.

RESULTS

At mean follow-up of 28 months ± 8.2 [median 26, range 12-49], the graft failure rate was 4.7%. Significant improvements were seen in all clinical scores (p < 0.001). MRI analysis showed 71% with fully integrated grafts in the tibia and 24% in the femur, with the remainder all showing greater than 50% integration. Graft signal was low and homogenous in 67% in the tibia, 29% in the intra-articular portion and 20% in the femur. One patient had greater than 50% high signal in the tibial graft and one in the intra-articular graft, all others demonstrated greater than 50% low signal. Both graft integration and signal were significantly better in the tibia than the femur (p < 0.01). Tunnel widening was 2.2 ± 1.4 mm and 2.7 ± 1.3 mm in the tibia and femur, respectively. Comparison of individual MRI appearances and overall clinical outcome at the same 12-month point demonstrated no consistent significant correlation.

CONCLUSION

Adjustable cortical suspensory fixation in both femoral and tibial tunnels provides good clinical outcomes and a low graft rupture rate. Grafts demonstrate healing with comparatively low tunnel widening. There was no consistent significant correlation between the appearances on MRI and clinical outcome.

LEVEL OF EVIDENCE

Case-control study, Level III.

Large Animal Models for Anterior Cruciate Ligament Research

Large animal (non-rodent mammal) models are commonly used in ACL research, but no species is currently considered the gold standard. Important considerations when selecting a large animal model include anatomical differences, the natural course of ACL pathology in that species, and biomechanical differences between humans and the chosen model. This article summarizes recent reports related to anatomy, pathology, and biomechanics of the ACL for large animal species (dog, goat, sheep, pig, and rabbit) commonly used in ACL research. Each species has unique features and benefits as well as potential drawbacks, which are highlighted in this review. This information may be useful in the selection process when designing future studies.

Adjustable buttons for ACL graft cortical fixation partially fail with cyclic loading and unloading

PURPOSE

Despite good initial pullout strength, it is unclear whether adjustable button (AB) devices for anterior cruciate ligament (ACL) soft-tissue graft fixation, which are based on the Chinese finger trap technique, resist cyclic loading. Furthermore, they have never been tested in a cyclic protocol including complete unloading. It was hypothesized, that the displacement of AB devices with the Chinese finger trap technique would be greater than that of continuous suture loop devices and other available AB mechanisms in a cyclic loading with complete unloading protocol.

METHODS

ACL reconstruction was performed in a porcine knee model using three different types of cortical fixation devices: two different AB devices that use the Chinese finger trap design, one AB device that uses a locked suture loop mechanism and two different continuous loop devices as control groups (n = 40). Specimens were mounted in a material-testing machine (Instron Inc.) that permitted 2500 loading and complete unloading cycles to a maximum of 250 N, as well as continuous elongation recording. A one-way ANOVA was performed for statistical analysis.

RESULTS

The displacement of ABs with a Chinese finger trap loop (mean 8.1; SD 1.5 mm and mean 6.1; SD 1.4 mm) was significantly greater than that of AB with a locked suture loop (mean 4.7; SD 1.0 mm; p < 0.05) and devices with a continuous loop (mean 4.1; SD 0.5 mm and mean 4.4, SD 0.3 mm; p < 0.01). No significant differences were detected between the ABs with a locked suture loop and the continuous loops.

CONCLUSION

Cyclic loading and unloading of AB using the Chinese finger trap technique leads to significantly greater construct lengthening compared with other devices. Complete unloading of the ACL is very likely to occur during rehabilitation after ACL reconstruction. Lengthening of the AB device due to cyclic loading might be a potential mode of failure of the ACL graft fixation. Therefore, when using an AB femoral fixation technique, a locked suture loop design or a careful rehabilitation protocol should be considered.

Anteversion and length of the femoral tunnel in ACL reconstruction: in-vivo comparison between rigid and flexible instrumentation

Background

Due to it being tangential to the distal femoral axis, the anteromedial portal presents significant risk of causing iatrogenic damage, and of producing tunnels that are too short for optimal osseointegration. Flexible reamers were developed to eliminate the need for knee hyperflexion and offer better-controlled orientation of the femoral tunnel. We aimed to compare the anteversion and length of femoral tunnels drilled using flexible reamers to those drilled using rigid reamers.

Methods

Between May 2012 and December 2013, all patients receiving ACL reconstruction performed by one surgeon were operated on using either a rigid or a flexible reamer from the same supplier (Versi-Tomic® system, Stryker, Kalamazoo, Michigan). The height of each patient was recorded, and the length and anteversion of the femoral tunnels were measured intra-operatively and on true lateral radiographs, respectively.

Results

Thirty-seven patients underwent operations using the rigid instrumentation, and 43 using the flexible instrumentation. There was no statistically significant difference between the two groups in either sex or height (p = n.s.). The patients operated on using the rigid instrumentation had tunnels anteverted by 18.6° ± 6° and 33.6 ± 2.9 mm long. Those operated on using the flexible instrumentation had tunnels anteverted by 40° ± 2° and 41.1 ± 3.57 mm long. Both anteversion and tunnel length were significantly greater for tunnels drilled using the flexible instrumentation (p < 0.001).

Conclusions

This study demonstrated that flexible reamers produce significantly more anteverted and longer femoral tunnels during ACL reconstruction than rigid reamers. Clinical studies remain necessary to assess the outcomes of ACL reconstruction using flexible reamers.

Relationship between anterior cruciate ligament and anterolateral meniscal root bony attachment: High-resolution 3-T MRI analysis

BACKGROUND

The tibial bony attachments of the anterior cruciate ligament (ACL) and the anterolateral meniscal root (ALMR) are very close, and drilling the tibial tunnel in ACL reconstruction may damage the ALMR attachment. This study investigated the relationship between the tibial attachment of the ACL and ALMR using high-resolution 3-T magnetic resonance imaging (MRI).

METHODS

Twenty healthy subjects (35.8 ± 13.0 years) had 20 knees scanned using high resolution 3-T MRI. The tibial bony attachments of ACL, ALMR, and the tibia were segmented and three-dimensional models were created. The shape, area, and location of each attachment were evaluated using this model.

RESULTS

The ACL tibial attachment was elliptical in nine knees (45%), C-shaped in nine knees (45%) and triangle in two knees (10%). The mean values of the ACL vs ALMR tibial attachments were as follows: area, 106.2 ± 21.3 vs 56.2 ± 21.3 mm²; length, 16.8 ± 2.0 vs 11.0 ± 1.8 mm; and width, 6.9 ± 1.3 vs 6.6 ± 1.0 mm. The location of the ACL vs ALMR attachment centres was 46.5 ± 1.7% vs 56.5 ± 1.9% in the medial-lateral direction and 36.3 ± 3.6% vs 36.7 ± 3.5% in the anterior-posterior direction. The distance between the ACL and ALMR centres was 8.1 ± 1.3 mm.

CONCLUSIONS

ACL and ALMR tibial attachments were individually distinguished using high resolution 3-T MRI. The short distance between both centres of the attachments may suggest that ALMR can be damaged when the tibial tunnel is drilled in ACL reconstruction.

Arthroscopic ACL reconstruction using fixed suspensory device versus adjustable suspensory device for femoral side graft fixation: What are the outcomes?

INTRODUCTION

The aim of the study was to evaluate the outcomes of Arthroscopic ACL Reconstruction using Fixed suspensory device and Adjustable suspensory device for femoral side graft fixation.

MATERIAL AND METHODS

We conducted a prospective study of sixty two patients with ACL deficient knees treated with arthroscopic ACL reconstruction. Consecutively patients were operated with fixed loop and adjustable loop suspensory devices for femoral side graft fixation and no randomization was done.

RESULTS

Functional assessment was performed with VAS score, IKDC score and Lyshom score before and after surgery with ACL reconstruction. The postoperative Lyshom score in fixed loop group and adjustable loop group was 94.23 and 94.32 respectively. The IKDC score in fixed group and adjustable group was 92.03 and 92.16 respectively. VAS in fixed loop group improved from score of 5-3, while in adjustable loop group from score of 4-3. There was significant improvement in stability of knee assessed by Lachman's test, anterior drawer test, and Pivot shiff's test and both methods of fixation provide stability to knee. The complications included; restriction of terminal flexion in 12 patients: 6 in each group. There was no implant breakage in both groups.

CONCLUSION

Arthroscopic ACL reconstruction using fixed loop and adjustable loop suspensory devices are equally effective fixation methods.

Radiological evaluation of the femoral tunnel positioning in anterior cruciate ligament reconstruction

OBJECTIVE

To evaluate the inclination and the length of the femoral tunnel in patients submitted to anterior cruciate ligament reconstruction (ACL) surgery by transtibial and anatomical techniques.

METHODS

This is an analytical observational study in patients with ACL injury that underwent arthroscopic reconstruction through transtibial and anatomical surgical techniques. In the immediate postoperative period, computed tomography (CT) and anteroposterior (AP) view digital radiographs (X-rays) were performed to evaluate the inclination and length of the femoral tunnel.

RESULTS

Forty-two patients were analyzed: 27 underwent anatomical reconstruction and 15, transtibial reconstruction. The inclination angle and tunnel length by the transtibial technique are always greater than by the anatomical technique. The mean inclination angles were 59.75° (53.9-66.1°) in the X-rays and 54.17° (43.5-62.3°) in CT for the transtibial technique, and 42.91° (29.3-57.4°) in the X-rays and 39.10° (23.8-50.6°) in CT for the anatomical technique. Regarding the length of the femoral tunnel, the transtibial technique promotes longer tunnels: mean 55.7 mm (40.0-70.2 mm) in the transtibial and 35.5 mm (24.5-47 mm) in the anatomical technique. No statistically significant correlation was observed between the length and the inclination of the tunnel, regardless of the technique used. Thus, these variables can be considered as independent.

CONCLUSION

The anatomical reconstruction technique presented shorter femoral tunnels and lower angle of inclination than the transtibial technique. The CT showed smaller inclination angle than the X-rays, regardless of the surgical technique.

The effect of femoral bone tunnel configuration on tendon-bone healing in an anterior cruciate ligament reconstruction: An animal study

Objectives

To compare the effect of femoral bone tunnel configuration on tendon-bone healing in an anterior cruciate ligament (ACL) reconstruction animal model.

Methods

Anterior cruciate ligament reconstruction using the plantaris tendon as graft material was performed on both knees of 24 rabbits (48 knees) to mimic ACL reconstruction by two different suspensory fixation devices for graft fixation. For the adjustable fixation device model (Socket group; group S), a 5 mm deep socket was created in the lateral femoral condyle (LFC) of the right knee. For the fixed-loop model (Tunnel group; group T), a femoral tunnel penetrating the LFC was created in the left knee. Animals were sacrificed at four and eight weeks after surgery for histological evaluation and biomechanical testing.

Results

Histologically, both groups showed a mixture of direct and indirect healing patterns at four weeks, whereas only indirect healing patterns were observed in both groups at eight weeks. No significant histological differences were seen between the two groups at four and eight weeks in the roof zone (four weeks, S: mean 4.8 sd 1.7, T: mean 4.5 sd 0.5, p = 0.14; eight weeks, S: mean 5.8 sd 0.8, T: mean 4.8 sd 1.8, p = 0.88, Mann-Whitney U test) or side zone (four weeks, S: mean 5.0 sd 1.2, T: mean 4.8 sd 0.4, p = 0.43; eight weeks, S: mean 5.3 sd 0.8,T: mean 5.5 sd 0.8, p = 0.61, Mann-Whitney U test) . Similarly, no significant difference was seen in the maximum failure load between group S and group T at four (15.6 sd 9.0N and 13.1 sd 5.6N) or eight weeks (12.6 sd 3.6N and 17.1 sd 6.4N, respectively).

Conclusion

Regardless of bone tunnel configuration, tendon-bone healing after ACL reconstruction primarily occurred through indirect healing. No significant histological or mechanical differences were observed between adjustable and fixed-loop femoral cortical suspension methods.

Cite this article: Y. Sato, R. Akagi, Y. Akatsu, Y. Matsuura, S. Takahashi, S. Yamaguchi, T. Enomoto, R. Nakagawa, H. Hoshi, T. Sasaki, S. Kimura, Y. Ogawa, A. Sadamasu, S. Ohtori, T. Sasho. The effect of femoral bone tunnel configuration on tendon-bone healing in an anterior cruciate ligament reconstruction: An animal study. Bone Joint Res 2018;7:327–335. DOI: 10.1302/2046-3758.75.BJR-2017-0238.R2.

Drilling through anteromedial portal with a femoral aiming device ensures a sufficient length and a proper graft position, and prevents posterior wall breakage during anterior cruciate ligament reconstruction

OBJECTIVE

The aim of this study was to evaluate the characteristics of the femoral tunnel (FT) which was drilled through the AM portal by using a femoral aimer device and AP stability of the knee.

METHODS

Thirty-eight patients, with the mean age 29.6 (range: 20-43) years, were evaluated after ACL reconstruction. The mean follow-up time was 31.9 (range: 16-57) months. The FT was drilled using a femoral aimer with different offset according to the graft size measured, through the AM portal. The semitendinous and gracilis tendon autograft was used for reconstruction. The angles of FT and the exit point on the lateral condyle were measured on AP views of the knee. AP stability of the knee was measured with the KT-2000.

RESULTS

The mean angle of FT was 46.5° (± 8.4°), on the AP view. The mean distance between the exit point of FT and the most distal end of the femoral condyles was 46.7 (± 4.9) mm. The mean FT length was 36.1 (± 3.1) mm. The mean difference of anterior translation compared to the intact knee was 1.9 (± 1.6) mm. Except the three patients, with "one positive" pivot shift test, in the remaining 35 knees stability was equal to the healthy knee.

CONCLUSIONS

Femoral drilling by using a femoral aimer device through AM portal provided long enough FT for safe graft fixation and appropriate coronal plan obliquity. The exit point was far proximal from the insertion site of the popliteus tendon and lateral collateral ligament. Furthermore, the AM portal technique significantly improved AP stability of the knee.

Inside-out Tibial Tunnel Drilling Technique for All-inside Anterior Cruciate Ligament Reconstruction

All-inside anterior cruciate ligament reconstruction passed through a series of modifications over the past 2 decades, maintaining 2 common factors: half tunnels in both the femur and tibia and introduction of the graft into the knee through an arthroscopic portal. One of the disadvantages noted with this technique is the excessive cost of the instrumentation needed to perform it and its economic impact on the health care system. We describe a modification of the original technique, both maintaining the cortical bone in an intact state and avoiding the retrograde drill aiming device.

Arthroscopic Viewing Position Affects Anterior Cruciate Ligament Reconstruction Femoral Tunnel Length Measurements

Purpose

To purpose of this study was to compare arthroscopic anterior cruciate ligament (ACL) reconstruction femoral tunnel length measurements from the anterolateral portal between the standard notch view using a 30° arthroscope versus a "top-down" view utilizing a 70° arthroscope to visual the far side of the femoral tunnel aperture.

Methods

Arthroscopic femoral tunnel length measurements using calibrated reamers from the standard notch versus the "top-down" view were obtained and reviewed in 54 skeletally mature patients undergoing ACL reconstruction with no prior bony knee surgery. Patient age, height, weight, sex, and surgery laterality were also recorded. Measurements of femoral tunnel length were repeated using both views for inter-observer and intra-observer correlation.

Results

Inter-observer and intra-observer intra-class correlation coefficients for the standard notch view and "top-down" views were excellent, with higher reliability values appreciated using the "top down" view. Mean overall femoral tunnel length measurements obtained using the standard notch view were significantly longer than measurements from the "top-down" view (p < 0.001).

Conclusions

The standard notch view provides significantly longer femoral tunnel length measurements in comparison to the "top-down" view.

Hamstring Graft Incorporation According to the Length of the Graft Inside Tunnels

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction with a quadrupled semitendinosus (ST4) graft is an evolution of the standard technique with 2 hamstring tendons (semitendinosus + gracilis [STG]). However, there is no published comparison of how well these 2 types of hamstring grafts are incorporated into the bone tunnels. Because the ST4 graft is shorter, there is less graft material inside the tunnels.

PURPOSE

To use magnetic resonance imaging (MRI) to compare graft incorporation in the tibial bone tunnels 1 year after ACL reconstruction with either an STG graft or ST4 graft.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Sixty-two patients who underwent ACL reconstruction were enrolled prospectively: 31 with an ST4 graft and 31 with an STG graft. The same surgical technique, fixation method, and postoperative protocol were used in both groups. Graft incorporation and ligamentization were evaluated with MRI after 1 year of follow-up. The following parameters were evaluated: signal-to-noise quotient (SNQ), tibial tunnel enlargement, signal intensity at the bone-graft interface, and graft signal according to the Howell scale. The number of participants needed to show that the mean SNQ did not differ between the 2 techniques was 31 in each group (with a 1-sided alpha of 2.5% and a 1-sided beta of 10.0%). The Student t test was used to compare the distribution of continuous secondary endpoints.

RESULTS

The mean SNQ was 5.2 ± 4.5 for the STG group and 5.9 ± 3.7 for the ST4 group ( P = .5100). The mean tibial tunnel widening was 93.7% ± 51.7% for the STG group versus 80.0% ± 42.9% for the ST4 group ( P = .2605). The groups did not differ in signal intensity at the bone-graft interface ( P = .7502) or in graft signal according to the Howell scale ( P = .4544).

CONCLUSION

At the 1-year postoperative follow-up, incorporation and ligamentization of the STG and ST4 grafts were the same based on MRI analysis. The results were at least as good with the ST4 technique as with the standard STG technique in terms of incorporation and ligamentization.

Location of the tibial tunnel aperture affects extrusion of the lateral meniscus following reconstruction of the anterior cruciate ligament

The anterior root of the lateral meniscus provides functional stability to the meniscus. In this study, we evaluated the relationship between the position of the tibial tunnel and extrusion of the lateral meniscus after anterior cruciate ligament reconstruction, where extrusion provides a proxy measure of injury to the anterior root. The relationship between extrusion and tibial tunnel location was retrospectively evaluated from computed tomography and magnetic resonance images of 26 reconstructed knees, contributed by 25 patients aged 17-31 years. A measurement grid was used to localize the position of the tibial tunnel based on anatomical landmarks identified from the three-dimensional reconstruction of axial computed tomography images of the tibial plateaus. The reference point-to-tibial tunnel distance (mm) was defined as the distance from the midpoint of the lateral edge of the grid to the posterolateral aspect of the tunnel aperture. The optimal cutoff of this distance to minimize post-operative extrusion was identified using receiver operating curve analysis. Extrusion of the lateral meniscus was positively correlated to the reference point-to-tibial tunnel distance (r ²  = 0.64; p < 0.001), with a cutoff distance of 5 mm having a sensitivity to extrusion of 83% and specificity of 93%. The mean extrusion for a distance >5 mm was 0.40 ± 0.43 mm, compared to 1.40 ± 0.51 mm for a distance ≤5 mm (p < 0.001). Therefore, a posterolateral location of the tibial tunnel aperture within the footprint of the anterior cruciate ligament decreases the reference point-to-tibial tunnel distance and increases extrusion of the lateral meniscus post-reconstruction. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1625-1633, 2017.

Pullout strength of a novel hybrid fixation technique (Tape Locking Screw™) in soft-tissue ACL reconstruction: A biomechanical study in human and porcine bone

INTRODUCTION

A novel hybrid anterior cruciate ligament (ACL) reconstruction technique known as Tape Locking Screw™ (TLS) is gaining popularity. Utilizing a suspension-type construct in conjunction with an interference screw, this technique has demonstrated successful initial clinical results with the use of quadruple hamstring graft. However, there is currently limited data available on the biomechanical strength of this fixation. This study investigates the pullout strength of the construct in human distal femora as well as in a porcine model. The construct is tested in isolation, without the use of any graft. We hypothesized that the pullout strength of this construct would be similar to or better than current fixation systems available.

MATERIALS AND METHODS

The Tape Locking Screw hybrid fixation system was implanted into twenty-two fresh frozen human distal femora (50-89 years old) randomized to 10×20mm titanium or polyether ether ketone (PEEK) screws by a single sports fellowship trained orthopedic surgeon. Given that the graft is secured to polyethylene terephthalate tape within the construct, the construct was implanted without any graft in order to isolate the device for biomechanical testing. After implantation, a tensile force was applied directly to the loop of tape at a loading rate of 5mm/min using an electromechanical testing system. The failure load was calculated from the resultant load-displacement curve. Specimens were then visually examined for mode of failure. Similar biomechanical tests were performed on sixteen porcine femora.

RESULTS

In the human model, the mean pullout strength was 523±269N with the PEEK screw and 578±245N with the titanium screw. In the porcine femur model, mean strength was 616±177N with PEEK, 584±245N with titanium. There was no statistically significant difference in failure loads between these four groups. Tape slippage at the screw bone interface was the primary mode of failure in all the groups tested.

DISCUSSION

Our results demonstrate that the hybrid technique provides excellent pullout strength in comparison to other soft-tissue ACL fixation methods, with tape slippage being the mode of failure in all specimens tested. This data, in addition to the advantages of the TLS system, support its consideration in the armamentarium of constructs available for soft-tissue ACL reconstruction.

LEVEL OF EVIDENCE

Laboratory controlled study level 2.

All-Inside Bicruciate Ligament Reconstruction Technique: A Focus on Graft Tensioning Sequence

Bicruciate ligament (BCL) reconstructions are challenging procedures. One of the main operative goals is to stabilize the knee in the correct anterior-posterior position. We present an all-inside arthroscopic BCL reconstruction technique using hamstring tendon grafts. Ipsilateral semitendinosus (ST) and gracilis tendons are used for TriLink (Arthrex, Naples, FL) double-bundle posterior cruciate ligament (PCL) reconstruction and contralateral ST tendon is used for GraftLink (Arthrex) single-bundle anterior cruciate ligament (ACL) reconstruction. The use of instruments for retrograde reaming and devices for adjustable cortical suspensory fixation allows for a safe, reproducible all-inside BCL reconstruction by simplifying these difficult steps. To minimize the risk of anterior-posterior malposition, the ACL graft is first tensioned with the knee in full extension, ensuring a neutral anteroposterior positioning of the tibia under the femur. The PCL anterolateral bundle can then be independently tensioned with the knee at 90° of flexion, and the posteromedial bundle at 30° of flexion, while applying an anterior translation to the tibia to reduce the posterior drawer without any risk of overcorrection. The purpose of this Technical Note was to describe an all-inside BCL reconstruction with a specific focus on the graft tensioning sequence.

Comparison of transtibial and retrograde outside-in techniques of anterior cruciate ligament reconstruction in terms of graft nature and clinical outcomes: a case control study using 3T MRI

INTRODUCTION

This study was performed to compare ACL graft maturation and morphologies using MRI between trans-tibial (TT) and retrograde outside-in (OI) techniques, and to compare clinical outcomes between the two groups.

MATERIALS AND METHODS

Patients underwent single-tunnel ACL reconstruction using quadrupled hamstring autografts, with the TT technique used on 42 patients (TT group) and the retrograde OI technique used on 39 patients (OI group). All patients were examined with 3 T MRI at 6 months (between 5 and 7 months) after surgery. The signal intensity of the reconstructed graft was analyzed and compared between the two groups, using the signal/noise quotient (SNQ), the orientation of the ACL graft and the tibial tunnel location of the graft. The SNQ value is indicative of graft maturation, and the orientation of the graft and the tibial tunnel location of the graft represent graft morphology. Clinical evaluation was performed before the surgery and 2 years or more after the surgery.

RESULTS

The mean SNQ value of the TT group was significantly (P = 0.030) lower than that of the OI group. The mean sagittal ACL angle (P < 0.001) and the mean coronal ACL angle (P < 0.001) were more vertical in the TT group. The tibial tunnel aperture was located at a significantly (P < 0.001) more posterior position in the TT group. There was no statistically significant difference in the clinical results between the two groups.

CONCLUSIONS

The OI technique showed a more anteriorly positioned tibial tunnel and a more oblique graft orientation in both sagittal and coronal planes. However, in comparison with the TT group, a significantly higher SNQ value was noticed in the follow-up MRI of the OI group at 6 months, although clinical results of the two groups were not significantly different during at least the 2-year follow-up.

Hamstring Graft Biological Preparation for Anterior Cruciate Ligament Reconstruction

The all-inside anterior cruciate ligament reconstruction (ACLR) success depends on biologic integration of the graft in the bone tunnel. Sutures wrapping the tendon in the bone tunnel may affect tendon-bone healing in shorter bone tunnels. To achieve better graft integration, we propose a variation of the graft link suture technique wherein the graft is linked chain-like to the femoral and tibial TightRope (Arthrex), which increases the tendon-bone contact area by eliminating sutures from the noose of the graft and thus may allow better graft integration.

The influence of femoral tunnel length on graft rupture after anterior cruciate ligament reconstruction

Background

For ACL reconstruction, the minimum length of the femoral tunnel and the flexor tendon graft length needed within the tunnel for proper integration have not been defined. The aim of this study was to assess whether a short tunnel is a risk factor for poor prognosis and re-rupture by comparing the outcomes of patients with short femoral tunnels to those of patients with longer tunnels.

Materials and methods

A retrospective observational study of 80 patients who underwent ACL reconstruction using flexor tendons via the medial transportal or transtibial technique was performed. Patients were categorized according to the amount of graft within the tunnel: ≤1.5 versus >1.5 cm; ≤2 versus >2 cm; ≤2.5 versus >2.5 cm; and ≤1.5 versus >2.5 cm. Patients were evaluated 2 years after surgery by performing a physical examination (Lachman, pivot shift and anterior drawer tests), using a KT1000 arthrometer, calculating objective and subjective International Knee Documentation Committee scores, conducting the Lysholm score, and recording re-ruptures.

Results

Of the 80 operated patients, nine were lost to follow-up. Comparative assessment of the patients with different amounts of graft within the tunnel indicated no significant differences in the evaluated outcomes, except for positive Lachman test results, which were more frequent in patients with tunnels with ≤2 cm of graft than in those with tunnels with >2 cm of graft.

Conclusion

The amount of graft within the femoral tunnel does not appear to be a risk factor for clinical instability of the knee or re-rupture of the graft. Level of evidence: case series, level IV.

Level of evidence

Case series, level IV.

Clinical and arthrometric outcomes of an anatomic outside-in single-bundle anterior cruciate ligament reconstruction using a retrodrill

BACKGROUND

The main option to perform an anatomic anterior cruciate ligament (ACL) reconstruction is the anteromedial portal (AMP) technique. It has several reported complications (iatrogenic chondral injury, posterior-wall blowout, short sockets, increased risk of injury to common peroneal nerve). In an attempt to avoid these complications the outside-in (OI) technique was revived with the addition of a retrodrill. The aim of this study is to evaluate the clinical and arthrometric outcomes of a series of anatomical OI single bundle ACL reconstruction using a retrodrill.

METHODS

Prospective case series. KT-1000 and Pivot Shift Test were done at 24 months follow-up. International Knee Documentation Committee (IKDC), Lysholm and Tegner activity scores preoperatively and at final follow-up. Complications were reported. Statistical analysis was done with t-test.

RESULTS

275 knees of 200 (73%) males and 75 (27%) females were enrolled in the study. Mean age 29.1 years (15-54). Mean follow-up 34.5 months (24-49). Mean preoperatively Lysholm Score 62 (25-95) versus 95 (76-100) at final follow-up (p<0.001) Mean preoperatively IKDC score 60 (26.4-90.8) versus 92 (59.8-100) at final follow-up (p<0.001) Mean Tegner activity Score pre injury 5 versus 5 at final follow-up. (p=0.59) Mean KT-1000 side-to-side difference 2mm (1-6). Pivot Shift test negative in 243 patients (90%); positive in 32 (10%) patients. 13 (5%) ACL re-ruptures. 2 (0.7%) infections. No other complications were reported.

CONCLUSION

OI single bundle anatomic ACL reconstruction using a retrodrill is a valid and safe option that avoids the complications reported with the AMP technique.

Double-Bundle, All-Inside Posterior Cruciate Ligament Reconstruction: A Technique Using 2 Separate Autologous Grafts

In a double-bundle posterior cruciate ligament reconstruction, several surgical techniques are available. Compared with other techniques, the advantages of the all-inside technique and cortical suspension devices with variable loop length are that shorter grafts can be used, tendons can be quadrupled, and a double-bundle posterior cruciate ligament reconstruction can be performed with autologous grafts. Furthermore, the all-inside technique provides independent outside-in socket reaming and is soft tissue, cortex, and bone sparing because no full diameter tunnels but sockets are created with a small diameter guide pin, which can transform into a retrograde drill. Sockets could however lead to bottoming out of the grafts at the femoral side and subsequent residual laxity. This can be avoided by using 2 separate grafts that are fixed in 2 femoral sockets before they are independently fixed and tensioned in 1 tibial socket in their corresponding flexion angle. In this technical note, we present a double-bundle, all-inside posterior cruciate ligament reconstruction using 2 separate autologous grafts.

Comparison Between Single- and Double-Bundle Anterior Cruciate Ligament Reconstruction With 6- to 8-Stranded Hamstring Autograft: A Prospective, Randomized Clinical Trial

BACKGROUND

Whether double-bundle (DB) anterior cruciate ligament (ACL) reconstruction with 6- to 8-stranded hamstring autograft (HG) is better than single-bundle (SB) ACL reconstruction remains debatable, as long-term follow-up data are lacking.

PURPOSE

To prospectively investigate and compare the long-term results of DB and SB ACL reconstruction with a 6- to 8-stranded HG.

STUDY DESIGN

Randomized controlled clinical trial;

LEVEL OF EVIDENCE

1.

METHODS

A total of 80 patients with chronic ACL rupture were randomized to SB or DB ACL reconstruction with a 6- to 8-stranded HG. In the SB group, both the semitendinosus tendon (ST) and the gracilis tendon (GT) were prepared in 3 or 4 strands, with a total of 6 to 8 strands. In the DB group, the ST was prepared in 3 or 4 strands used for the anteromedial bundle, and the GT was prepared in the same manner for the posterolateral bundle. Each graft was fixed with an EndoButton, a bioabsorbable interference screw, and a staple. Outcome assessment was performed by a blinded independent observer using International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores, as well as range of motion (ROM), Lachman test, pivot-shift test, KT-2000 arthrometer side-to-side difference, and return-to-sport data.

RESULTS

A total of 68 patients (DB group, 34; SB group, 34) were observed for a mean of 80 months (range, 74-86 months). There were 2 traumatic instability failures and two 5° extension restrictions in the DB group, while no failures or 5° extension restrictions were observed in the SB group. The mean Lysholm, Tegner, and IKDC scores improved significantly in both groups compared with preoperation scores (P < .05). No patient had a positive Lachman test result. No significant differences were found between groups in functional scores, incidence of pivot shift, ROM, Lachman test, KT-2000 arthrometer anterior laxity, or time and level of return to sport.

CONCLUSION

Both SB and DB ACL reconstruction with 6- to 8-stranded HG showed satisfactory results in subjective scores and anteroposterior and rotational stability over a nearly 7-year follow-up; neither technique was superior.

Overestimation of femoral tunnel length during anterior cruciate ligament reconstruction using the retrograde outside-in drilling technique

PURPOSE

When the femoral tunnel socket is reamed in an oblique direction from the wall of inter-condylar notch in anterior cruciate ligament (ACL) reconstruction, the tunnel length can be shorter at the periphery than at the centre. Because surgeons can manipulate the direction of tunnel in the outside-in femoral tunnel drilling technique, this length mismatch would vary depending on the direction of the tunnel. The purpose of this study was to investigate this length mismatch when reamed in various directions.

METHODS

In total of thirteen points were defined as femoral drilling entry points on concentric lines with 0, 1, 2, and 3 cm radius from the lateral epicondyle of a three-dimensional bone model from 40 subjects. Femoral tunnel drilling was simulated on the models by connecting the centre of the ACL footprint with each defined point on the lateral femoral surface. The mismatch length was measured between the centre and the shortest peripheral side of the tunnel socket.

RESULTS

When the distance between the drilling entry point on the lateral femoral surface and the lateral epicondyle was increased to anterior proximal direction, there was a significant increase in the mismatch length. The mismatch length became more than 2 mm when the entry point was located more than 2 cm away from the lateral epicondyle.

CONCLUSIONS

When the drilling entry point is set far away from the lateral epicondyle, a significant increase was observed in tunnel length mismatch between the centre of the tunnel and its shortest peripheral side. Because the tunnel length is measured with a guide pin introduced at the centre of the tunnel before reaming in retrograde outside-in technique, this length mismatch could cause an overestimation of the tunnel length. Surgeons should recognise this mismatch when preparing the length of graft and socket to optimise the graft insertion length into the socket.

Graft bending angle is correlated with femoral intraosseous graft signal intensity in anterior cruciate ligament reconstruction using the outside-in technique

BACKGROUND

The purposes of this study were as follows: 1) to determine the correlation between the bending angle of the anterior cruciate ligament (ACL) graft at the femoral tunnel and the magnetic resonance imaging (MRI) signal intensity of the ACL graft and 2) to analyze the difference in the MRI signal intensity of the reconstructed ACL graft in different areas of the graft after single-bundle hamstring autograft ACL (SB ACL) reconstruction using an outside-in (OI) technique with bone-sparing retro-reaming.

METHODS

Thirty-eight patients who underwent SB ACL reconstruction with the hamstring tendon autograft using the OI technique were enrolled in this study. All patients were assessed using three-dimensional computed tomography (CT) to evaluate femoral tunnel factors, including tunnel placement, tunnel length, tunnel diameter, and femoral tunnel bending angle. At a mean of 6.3±0.8months after surgery, 3.0-T MRI was used to evaluate the graft signal intensity using signal/noise quotient for high-signal-intensity lesions.

RESULTS

Among various femoral tunnel factors, only the femoral tunnel bending angle in the coronal plane was significantly (p=0.003) correlated with the signal/noise quotient of the femoral intraosseous graft. The femoral intraosseous graft had significantly (p=0.009) higher signal intensity than the other graft zone. Five cases (13.2%) showed high-signal-intensity zones around the femoral tunnel but not around the tibial tunnel.

CONCLUSION

After ACL reconstruction using the OI technique, the graft bending angle was found to be significantly correlated with the femoral intraosseous graft signal intensity, indicating that increased signal intensity by acute graft bending might be related to the maturation of the graft.

LEVEL OF EVIDENCE

This was a retrospective comparative study with Level III evidence.

Transportal femoral drilling creates more horizontal ACL graft orientation compared to transtibial drilling: A 3D CT imaging study

BACKGROUND

The principle of anatomic anterior cruciate ligament (ACL) reconstruction is to create a femoral and tibial tunnel that resembles the insertion of the native ACL. Anatomic reconstruction leads to a more horizontal graft orientation that provides more rotational stability. The aim of this study is to investigate the best method to achieve anatomical reconstruction of femoral insertion of the ACL and thus, a more horizontal orientation of the ACL. We compared tunnel position and orientation between transportal femoral drilling technique and transtibial technique.

METHODS

Thirty-two patients were included. Post-operative CT scans were obtained and femur, tibia and ACL tunnels were reconstructed. The position and orientation of tibial and femoral tunnels were quantified using the quadrant method, and femoral tunnel length, ellipticity and posterior wall breakage were assessed. We also investigated clinical outcome.

RESULTS

Analyses show that transportal drilled femoral tunnels were situated significantly lower than transtibial drilled tunnels (p<0.0001), resulting in a significantly more horizontal oriented ACL in the transportal group in coronal (p<0.0001) and sagittal plane (p=0.01). No differences were observed in depth of femoral tunnel position (p=0.44). Femoral tunnel length was shorter in the transportal group (p=0.01) with a more ellipsoidal femoral aperture (p=0.01). There were no differences between both groups in tibial position. There were no differences in clinical outcome measure between the transportal and transtibial groups.

CONCLUSION

This study indicates that transportal drilling of the femoral tunnel leads to a more horizontal graft orientation of the ACL, without differences in clinical outcome.

Graft Bending Angle at the Intra-articular Femoral Tunnel Aperture After Single-Bundle Posterior Cruciate Ligament Reconstruction: Inside-Out Versus Outside-In Techniques

BACKGROUND

To date, no in vivo 3-dimensional computed tomography (3D-CT) studies have compared graft bending angles at the femoral tunnel aperture and femoral tunnel length in patients who underwent posterior cruciate ligament (PCL) reconstruction with outside-in (OI) and inside-out (IO) techniques.

PURPOSE/HYPOTHESIS

This study used in vivo 3D-CT analysis to compare graft bending angles at the femoral tunnel aperture and femoral tunnel lengths after OI and IO femoral drilling techniques in single-bundle PCL reconstruction. It was hypothesized that the graft bending angle at the femoral tunnel aperture would be less acute with the OI compared with the IO technique, with no difference in femoral tunnel lengths.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Immediate postoperative in vivo 3D-CT and curved planar reformation were used to assess the graft bending angles and femoral tunnel lengths in the sagittal, axial, and coronal planes in 67 patients who underwent single-bundle PCL reconstruction with the OI (n = 37) and IO (n = 30) techniques.

RESULTS

The mean graft bending angles on the sagittal and axial planes were 8.2° more acute (23.5° vs 15.3°, P = .011) and 5.3° more acute (49.0° vs 43.7°, P = .013), respectively, with the IO compared with the OI technique, but the difference in the coronal plane was not statistically significant (25.3° vs 24.8°, P = .623). Femoral tunnel length was similar in the 2 groups.

CONCLUSION

The graft bending angles in single-bundle PCL reconstruction were more acute in the sagittal and axial planes with the IO compared with the OI technique, but there was no difference in the coronal plane. In addition, femoral tunnel lengths did not differ significantly in patients who underwent OI and IO single-bundle PCL reconstructions. Although further biomechanical studies are needed to evaluate the effect on graft failure of a <10° difference in graft bending angle, the small magnitude of this difference would likely have little adverse effect on graft survival.

Comparison of Femoral Tunnel Length and Obliquity Between Transtibial, Anteromedial Portal, and Outside-In Surgical Techniques in Single-Bundle Anterior Cruciate Ligament Reconstruction: A Meta-analysis

PURPOSE

It is unclear whether femoral tunnel length and obliquity differ after transtibial and independent femoral drilling techniques of anterior cruciate ligament (ACL) reconstruction. This meta-analysis therefore compared femoral tunnel length and obliquity in patients who underwent ACL reconstruction by the transtibial, anteromedial (AM) portal, and outside-in (OI) techniques.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, all studies comparing femoral tunnel length and obliquity with various measurement tools-from direct measurement to imaging methods such as plain radiography, computed tomography, or magnetic resonance imaging-in patients who underwent reconstruction by the transtibial or independent femoral drilling (AM portal or OI) techniques were included.

RESULTS

Fourteen studies were included in the meta-analysis. The femoral tunnel length was 7.8 to 11.0 mm longer (P < .05) and coronal obliquity was 7.5° to 29.1° more vertical (P < .05) with the transtibial technique than with the AM portal or OI technique. Femoral tunnel and graft obliquity in the sagittal plane, however, did not differ significantly (P > .05).

CONCLUSIONS

ACL reconstruction using the AM portal and OI femoral drilling techniques resulted in a shorter length and greater coronal obliquity of the femoral tunnel than did the transtibial technique. However, these 3 femoral drilling techniques resulted in similar obliquities of the femoral tunnel and graft in the sagittal plane.

LEVEL OF EVIDENCE

Level III, meta-analysis.