Single harvesting in the all-inside graft-link technique: is the graft length crucial for success? A biomechanical study

Combined All-Inside Anterior Cruciate Ligament Reconstruction With Semitendinosus Plus Anterolateral Ligament Reconstruction With Intact Gracilis Tibial Insertion and Transtibial Passage

The indications for combining anterior cruciate ligament reconstruction with anterolateral ligament reconstruction have increased considerably in recent years since several anatomical, clinical, and biomechanical studies have proven the importance of the anterolateral periphery in knee rotational stability. Much is still being discussed on how to combine these techniques in terms of which grafts and fixation options to use, as well as avoiding tunnel convergence. This study aims to describe anterior cruciate ligament reconstruction with a triple-bundle semitendinosus tendon graft all-inside technique combined with an anterolateral ligament reconstruction maintaining the gracilis tendon insertion on the tibia, using independent anatomical tunnels. With this, we were able to reconstruct both using only hamstring autografts, reducing morbidity in other possible donor areas, in addition to allowing stable fixation of both grafts without tunnel convergence.

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.

Similar biomechanical properties of four tripled tendon graft models for ACL reconstruction

PURPOSE

The present study tested and compared the biomechanical properties of four different triplicate graft tendon techniques.

METHODS

32 tripled tendons from the common extensor muscle of bovine fingers were tested on a material testing machine, passing the end loop over a metal rod of a clevis connected to the load cell on the upper side, and fixing the lower end to a clamp. The samples were divided into four groups: (A) tripled with a free end sutured only to one of the two fixed bundles (B) tripled with a free end positioned between the two fixed strands and sutured to both (C) tripled with an S-shape and all the three strands sutured together at the upper and lower extremities of the graft (D) partially quadrupled with the free end sutured together with the other three bundles at the upper extremity. Each sample was pretensioned at 50 N for 10 min and then subjected to 1000 load control cycles between 50 and 250 N. Finally, each sample was subjected to a load to failure test. Authors also present some preliminary results on the feasibility of a non-contact and full-field Thermoelastic Stress Analysis technique, based on Infrared Thermography, to evaluate the level of stress on the whole graft, and hence on each strand, during fatigue loading.

RESULTS

Eighty five percent of the samples failed at the level of the clamp. The cyclical elongation progressively decreased in all the samples and there was a simultaneous increase in stiffness. An increased stiffness was noted between Group 2 vs Group 3 and Group 2 vs Group 4 at the 500th and 1000th cycle. The failure loads were as follows: (a) 569.10 N, (b) 632.28 N, (c) 571.68 N, (d) 616.95 N. None of the parameters showed a statistically significant difference between the four groups.

CONCLUSION

This study reported similar biomechanical behavior of four different models of tripled grafts suitable for ACL reconstruction. In addition, the biomechanics of overall tripled tendon grafts seems more affected by the viscoelastic property of the tendon itself rather than the preparation method.

Clinical outcomes of Tightrope system in the treatment of purely ligamentous Lisfranc injuries

Background

Purely ligamentous Lisfranc injuries are mainly caused by low energy damage and often require surgical treatment. There are several operative techniques for rigid fixation to solve this problem clinically. This study evaluated the effect of using the Tightrope system to reconstruct the Lisfranc ligament for elastic fixation.

Methods

We retrospectively analyzed 11 cases with purely ligamentous Lisfranc injuries treated with the Tightrope system from 2016 to 2019, including 8 male and 3 female. X-ray was performed regularly after operation to measure the distance between the first and second metatarsal joint and the visual analogue scale (VAS) score was used to evaluate pain relief. American orthopedic foot & ankle society (AOFAS) and Maryland foot score were recorded at the last follow-up.

Results

The average follow-up time was 20.5 months (range, 17–24). There was statistically significant difference in the distance between the first and second metatarsal joint and VAS score at 3 months, 6 months, and the last follow-up when compared with preoperative values (P < 0.05).Mean of postoperative AOFAS mid-foot scale and Maryland foot score were 92.4 ± 4.3, 94.1 ± 3.5, respectively. The Tightrope system was not removed and the foot obtained better biomechanical stability. No complications occurred during the operation.

Conclusion

Tightrope system in the treatment of purely ligamentous Lisfranc injuries can stabilize the tarsometatarsal joint and achieve satisfactory effect.

Viscoelastic and failure properties of two configurations of triple-folded hamstring tendons used for anterior cruciate ligament (ACL) reconstruction

BACKGROUND

Hamstring autografts are commonly used for anterior cruciate ligament (ACL) reconstruction. Different folding techniques exist in tripling the semitendinosus. Few anatomical studies exist in evaluating their viscoelastic properties. The purpose of this study was to characterize and compare the viscoelastic and failure properties of two hamstring graft configurations, the "Z" construct and "2" construct.

METHODS

Ten matched pairs of fresh-frozen cadaveric semitendinosus hamstring grafts were used to create the "2" configuration or "Z" configuration. The biomechanical testing consisted of four phases: preconditioning, where graft dimensions (mm) were measured; stress relaxation, where load, displacement and time data were collected and equilibrium relaxation (%) was calculated; dynamic creep, where the total construct elongation was calculated; and ramp-to-failure, where maximum failure load was recorded.

RESULTS

The "2" configuration demonstrated recorded forces (N) significantly greater at each time point when compared to the "Z" configuration during stress relaxation (p = 0.003). The "2" configuration exhibited significantly less construct elongation (mm) during dynamic creep at 10 cycles (p = 0.008) and 2000 cycles (p = 0.0001). The maximum measured load at failure was significantly greater in the "2" configuration constructs than "Z" configuration (p = 0.013). Moreover, the axial loads at 2, 3 and 4 mm of displacement were, on average, greater in the "2" configuration than "Z" configuration (p = 0.152; p = 0.080; p = 0.012), respectively.

CONCLUSION

The results of this study provide support for folding techniques for tripled grafts to provide higher viscoelastic and failure properties for techniques with less suture interfaces. Future studies can potentially evaluate the clinical significance of these findings.

Biomechanical comparison of different tendon suturing techniques for three-stranded all-inside anterior cruciate ligament grafts

OBJECTIVE

In all-inside anterior cruciate ligament (ACL) reconstruction, it is usually difficult to obtain sufficient autologous semitendinosus tendon length for quadruple stranded graft in Asians, females, and those with short stature. The purpose of this study was to compare biomechanical properties of three different types of suture preparations for tripled graft and determine which method could achieve sufficient strength for ACL through in vitro study. The hypothesis of this study was that suturing with a rip-stop (RS) stitch for tripled-strand graft would lead to stronger mechanical properties than suturing with buried-knot four sutures.

METHODS

Twenty-four bovine digital extensor tendons harvested from forelimbs were prepared for tripled-strand graft in three different ways: (1) buried-knot four sutures, (2) two RS sutures, and (3) four RS sutures. These grafts were directly connected to cylindrical metal rods of a tensile testing machine. All specimens underwent cyclic loading followed by a load-to-failure test. Preparation time, elongation, stiffness, and ultimate failure load were compared.

RESULTS

For biomechanical comparison, the group with buried-knot four sutures was excluded because six (75%) specimens failed during the cycle load test. The group with four RS sutures showed lower total elongation (two RS sutures: 8.42±5.28mm; four RS sutures: 3.86±0.83mm, p=0.030), higher stiffness (two RS sutures: 247.28±53.39N/mm; four RS sutures: 329.27±55.56N/mm, p<0.001), and higher ultimate failure load (two RS sutures: 567.74±60.50N; four RS sutures: 736.46±32.50N, p=0.009). The most common failure mechanism of triple stranded graft was tendon split across sutures.

CONCLUSION

The method with four RS sutures showed sufficient strength for triple stranded graft for all-inside ACL reconstruction without increasing preparation time.

LEVEL OF EVIDENCE

III, controlled laboratory study.

Hamstring Braid Graft Technique for Anterior Cruciate Ligament Reconstruction

Hamstring autograft is one of the most used grafts for anterior cruciate ligament (ACL) reconstruction, although there are several graft preparation techniques. It is extremely difficult to mimic the biomechanical properties of the native ACL; thus, it is important to achieve a proper graft configuration, diameter, and length. To avoid reruptures, an optimal and reproducible hamstring autograft is desired. Hamstring autograft has been traditionally devalued when compared with other options such as bone-patellar tendon-bone autograft. The purpose of this Technical Note is to describe in detail a hamstring braid graft configuration that could potentially overcome the past disadvantages of ACL reconstruction.

Adjustable-length loop cortical button versus interference screw fixation in quadriceps tendon anterior cruciate ligament reconstruction - A biomechanical in vitro study

BACKGROUND

This biomechanical cadaveric in vitro study aimed to evaluate and compare the dynamic elongation behavior and ultimate failure strength of tibial adjustable-length loop cortical button versus interference screw fixation in quadriceps tendon-based anterior cruciate ligament reconstruction.

METHODS

Sixteen human quadriceps tendons were harvested and fixed into porcine tibiae using either biodegradable interference screw (n = 8) or adjustable loop device (n = 8) fixation. An acrylic block was utilized for femoral adjustable loop device fixation for both groups. All constructs were precycled for 10 times at 0.5 Hz and manually retensioned before tested in position and force control mode each for 1000 cycles at 0.75 Hz according to in vitro loading conditions replicating the in vivo ACL environment. Subsequently, an ultimate failure test at 50 mm/min was performed with mode of failure noted.

FINDINGS

Tibial IS fixation showed no statistically significant differences in the initial (-0.46 vs. -0.47 mm; P = 0.9780), dynamic (2.18 mm vs. 2.89 mm; P = 0,0661), and total elongation (1.72 mm vs. 2.42 mm; P = 0,0997) compared to adjustable loop device fixation. The tibial button fixation revealed an increased ultimate failure load (743.3 N vs. 606.3 N; P = 0.0027), while stiffness was decreased in comparison to screw fixation (133.2 N/mm vs. 153.5 N/mm; P = 0,0045).

INTERPRETATION

Anterior cruciate ligament reconstruction for quadriceps tendon graft using a tibial adjustable-length loop cortical button provides for comparable dynamic stabilization of the knee with increased ultimate failure load at decreased stiffness compared to screw fixation.

A biomechanical comparison of all-inside cruciate ligament graft preparation techniques

Background

The all-inside cruciate ligament graft preparation technique has become popular due to its utility in sparing a growing physis, preserving a tendon in ACL surgery, and/or reduction of pain. However, few studies have compared graft preparation techniques to determine the ideal construct for cruciate ligament reconstruction. We sought to compare biomechanical properties of two quadrupled all-inside cruciate ligament graft preparation techniques and three alternative all-inside graft preparation techniques that may be used when the available tendon is too short to be quadrupled.

Methods

Fifty porcine extensor tendons were evenly divided into five groups (n = 10) representing all-inside graft preparation techniques, including two quadrupled (Quad-A, Quad-B) and three alternative methods (Tripled, Folded, Two-Doubled). Each graft construct underwent preconditioning (10 loading cycles from 20 to 50 N at 0.1 Hz), cyclic loading (500 loading cycles from 50 to 250 N at 1.0 Hz) and load-to-failure (tension applied at 20 mm/min).

Results

Quad-A and Quad-B demonstrated no significant differences in cyclic displacement (10.5 ± 0.3 vs 11.7 ± 0.4 mm; p = 0.915), cyclic stiffness (1086.2 ± 487.3 vs 460.4 ± 71.4 N/mm; p = 0.290), pullout stiffness (15.9 ± 4.3 vs 7.4 ± 4.4 N/mm; p = 0.443), ultimate failure load (641.2 ± 84.7 vs 405.9 ± 237.4 N; p = 0.672), or ultimate failure displacement (47.3 ± 6.7 vs 55.5 ± 0.7 mm; p = 0.778). The mean cyclic displacement of the Two-Doubled group was significantly greater than the Quad-A (29.7 ± 2.2 vs 10.5 ± 0.3 mm; p < 0.001), Quad-B (29.7 ± 2.2 vs 11.7 ± 0.4 mm; p < 0.001), Tripled (29.7 ± 2.2 vs 11.3 ± 0.2 mm; p < 0.001), and Folded group (29.7 ± 2.2 vs 13.3 ± 0.2 mm; p < 0.001). There were no other statistically significant differences between the three alternative all-inside graft preparation techniques.

Conclusion

The current study demonstrates the biomechanical properties of two quadrupled all-inside graft constructs, Quad-A and Quad-B, are not significantly different. When the available tendon is of insufficient length, the Two-Doubled group demonstrated more than twice the cyclic displacement of all other graft preparation techniques, and is therefore not recommended for use in all-inside cruciate ligament reconstruction.

Tripled semitendinosus with single harvesting is as effective but less invasive compared to standard gracilis-semitendinosus harvesting

Introduction

The anterior cruciate ligament (ACL) reconstruction with pes anserinus tendons has been increasingly used throughout the last years. Although less invasive compared to other autologous grafts, a reduction of internal rotation and flexion strength after gracilis and semitendinosus harvesting has been reported. Harvesting one tendon instead of two from the pes anserinus can reduce the deficit of the knee flexor strength and improve the functional recover without weakening the reconstructed ligament.

Methods

Forty-five (45) patients who had ACL reconstruction with triple semitendinosus graft (ST3) have been compared with other 45 similar patients who had ACL reconstruction with double gracilis-semitendinosus tendons (GST). Patients have been evaluated at a minimum of 12 months after surgery: IKDC scale, KT-1000, One Leg Hop Test for the objective stability; Isokinetic test for the strength; Tegner scale, Lysholm and IKDC subjective evaluation form for the function.

Results

No differences have been detected between the groups for the objective item assessed. Male patients' subjective IKDC score was statistically better for the ST3 group. Recreational soccer players showed a higher Lysholm and subjective IKDC score in ST3 group compared to GST group. There was no difference regarding the return to sport.

Conclusion

ST3 guarantees the same objective knee stability compared to a GST. It is a viable option for ACL reconstruction that allows a better preservation of patient's anatomy and a less invasive harvesting surgery.

Level of evidence

III b, case control study.

Biomechanical comparison of four coupled fixation systems for ACL reconstruction with bone socket or full-tunnel on the tibial side

BACKGROUND

To compare in an animal model the biomechanical properties of four coupled fixation devices currently used in ACL reconstruction. Three out of four devices used a full tibial tunnel with an interference screw, while the other one system used a tibial socket and an adjustable loop suspension device. The null hypothesis is that there are no biomechanical differences between all the techniques tested.

METHODS

Thirty two femur-graft-tibia complexes were mounted on a tensile machine using bovine digital extensor tendons, porcine knees and four different fixation device combinations: After a preconditioning with a tensile load of 90N for five minutes, 1000cycles between 0 and 150N were applied to the complex before the final pulled to failure. Stiffness and strength were evaluated at the final pullout, as was the displacement (slippage) at one, 100, 500, and 1000cycles.

RESULTS

The multiple mean comparison led to a significant difference for the case of stiffness, with worse results in group C compared to group A (p=0.037). Conversely, no differences were found in UFL and slippage between all groups (p>0.05).

CONCLUSION

All the tested systems demonstrated in an animal model sufficient properties for a safe postoperative rehabilitation both for strength and for stiffness and slippage under cyclic loading.