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

Single bundle hamstrings autograft preparation techniques for anterior cruciate ligament reconstruction: current concepts

Anterior cruciate ligament reconstruction (ACLR) is one of the most common orthopedic procedures, and huge variation exists in the surgical technique. Single bundle hamstrings autograft reconstruction is a common method and has good clinical outcomes. A criticism of the hamstrings autograft is a small graft diameter, often less than 8-mm, which has been associated with increased re-rupture rates. Several graft preparation techniques for single bundle hamstrings autograft exist. Perioperative decisions include the number of tendons utilized, number of graft strands, graft configuration, and femoral and tibial fixation methods. Awareness of the minimum tendon and graft length required to produce each graft variation is necessary to avoid common pitfalls. However, intraoperative graft modification is possible to maximize graft diameter, and obtain proper fixation. The objective of this current concepts review is to describe the indications, surgical anatomy, technique, intraoperative tips, clinical outcomes, and complications for single bundle hamstrings autograft preparation techniques in ACLR.

Evaluation of biomechanical properties and biocompatibility: are partially absorbable cords eligible for anterior cruciate ligament reconstruction?

Introduction: Independent augmentation technology based on reinforcing devices has been reported to signifi-cantly reduce the elongation behavior of graft and improve knee stability after anterior cruciate ligament reconstruction (ACLR). Using biodegradable devices could reduce the risk of severe inflammatory reactions due to particle accumulation from foreign bodies. Given the limitations of the mechanical properties of biodegradable materials, partially biodegradable composite devices may offer a compromise strategy. Methods: Three types of partially absorbable core-sheath sutures, including low-absorbable cord (LA-C), medium-absorbable cord (MA-C) and high-absorbable cord (HA-C), were braided using unabsorbable ultra-high molecular weight polyethylene (UHMWPE) yarn and absorbable polydioxanone (PDO) monofil-ament bundle based on the desired configuration. The feasibility of these partially absorbable cords were verified by biomechanical testing, material degradation testing, and cell experiments, all performed in vitro. Results: Reinforcement of an 8 mm graft with the cords decreased dynamic elongation by 24%-76%, was positively related to dynamic stiffness, and increased the failure load by 44%-105%, during which LA-C showed maximum enhancement. Human ligament-derived fibroblasts showed good proliferation and vitality on each cord over 2 weeks and aligned themselves in the direction of the fibers, especially the UHMWPE portion. Discussion: This study supports the potential of partially degradable UHMWPE/PDO cords, particularly LA-C, for graft protection. Nervertheless, a higher proportion of biodegradable material results in lower stiffness, which may impair the protective and lead to mechanical instability during degradation.

Comparative analysis of the results of the anterior cruciate ligament reconstruction using an autograft preparation by known and new methods

Background. To date, the problem of choosing the optimal graft for anterior cruciate ligament (ACL) reconstruction and the methods for its formation is one of the main trends in the surgical treatment of patients with anterior knee joint instability.The aim. To compare the results of the anterior cruciate ligament reconstruction using the known method and the new proposed method for autograft formation.Materials and methods. The results of treatment of ACL injury in 44 patients were assessed. In the main group (19 patients), an original technique of ACL reconstruction from 1/2 of the width of m. peroneus longus tendon was used. In the control group (25 patients), ACL reconstruction was performed using a graft from the m. semitendinosus tendon prepared by the Lubowitz method.Results. The mean difference in the circumference of the distal third of the hip in the main group was 1.57 ± 1.162 cm and was statistically significantly better than in the control group, where the mean difference in the hip circumference was 4.74 ± 1.7207 cm.The range of motion of the knee joint in the main group 3 months after the surgery was 128.42 ± 9.287°, and in the control group mean flection was 109.6 ± 9.120°.The functional results in the main group were assessed by the Lisholm scale and were statistically significantly better than the results in the control group. The functional results by the AOFAS (American Orthopedic Foot & Ankle Society) scale in the main group were 100 points before the surgery and at all terms after the surgery: this indicates that the use of 1/2 of the width of m. peroneus longus tendon does not cause the its functional impairement.Conclusion. Anterior cruciate ligament plasty with use of 1/2 of the width of m. peroneus longus tendon prepared by the proposed method showed statistically significantly better results compared to the preparation of autograft from semitendinous muscle tendon using known method.

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.

Synergistic effect of the anterolateral ligament and capsule injuries on the knee laxity in anterior cruciate ligament injured knees: A cadaveric study

INTRODUCTION

There is much controversy about the practical role of the anterolateral ligament (ALL) and its relation to other anterolateral knee structures including the anterolateral capsule (ALC) and iliotibial band (ITB). The purpose of this cadaveric study was to investigate the effect of the ALL and ALC injuries on knee laxity with the iliotibial band (ITB) preserved in the anterior cruciate ligament (ACL)-injured knee.

HYPOTHESIS

The ALL and ALC would contribute to knee joint stability during anterior translation and internal rotation of the tibia in an ACL-injured knee.

MATERIAL AND METHODS

For 10 fresh-frozen cadaveric knees, we measured knee laxity with the following state of knee injuries with ITB preserved: (1) intact knee, (2) ACL-sectioned knee (ACL-), (3) additional sectioning of the ALL (ACL-/ALL-), and (4) additional sectioning of the ALC (ACL-/ALL-/ALC-). We did biomechanical measurements in internal-external rotation, anterior-posterior translation, and varus-valgus angulation for each condition at knee flexion angles of 0°, 30°, 60°, and 90°.

RESULTS

After we sectioned the ALL (ACL-/ALL-), the mean IR at 0°, 30°, 60°, and 90° of knee flexion were significantly increased, compared to the intact knee (p=<0.001, <0.001, <0.001, and 0.002) and ACL- (p=<0.001, <0.001, <0.001, and 0.002). The additional transection of the ALC (ACL-/ALL-/ALC-) significantly increased IR laxity from the ACL-/ALL- at 30°, 60°, and 90° (p=0.005, 0.003, and 0.047). For anterior laxity, ACL-/ALL- resulted in significantly increased anterior laxity from the ACL- at 30° and 60° (p=0.003 and 0.019), and ACL-/ALL-/ALC- significantly increased anterior laxity even from the ACL-/ALL- at 30° and 60° (p=0.007 and 0.011). For varus laxity, ACL-/ALL- resulted in significantly increased varus laxity from both the intact knee and ACL- at 60° (p=0.004 and 0.007) and 90° (p=<0.001 and<0.001). ACL-/ALL-/ALC- resulted in significantly increased varus from ACL-/ALL- at 60° and 90° (p=<0.001 and 0.003).

CONCLUSION

The anterolateral ligament and anterolateral capsule injuries in ACL-injured knees even with ITB preserved had a synergistic effect on knee laxity in the aspects of internal rotation, anterior translation, and varus angulation.

LEVEL OF EVIDENCE

II, Controlled laboratory study.

Biomechanical Comparison of a Novel Tibial Fixation Technique Versus Interference Screw Fixation for ACL Reconstruction Using Soft Tissue Grafts

Background:

Controversy remains regarding the optimal technique for tibial fixation of soft tissue grafts in anterior cruciate ligament (ACL) reconstruction.

Purpose/Hypothesis:

To compare the biomechanical outcomes of a novel transtibial tubercle fixation technique with those of a commonly utilized interference screw fixation at the tibial site. Our hypothesis was that transtibial tubercle fixation achieves higher ultimate failure loads than interference screw fixation.

Study Design:

Controlled laboratory study.

Methods:

We used 24 matched porcine tibias and digital extensor tendons, from which 12 grafts and tibial tunnels were prepared using the novel transtibial tubercle fixation technique and 12 were prepared using the interference screw fixation technique. The specimens underwent a cyclic loading test (50-250 N applied for 1000 cycles at a frequency of 1 Hz), followed by a load-to-failure test. The slippage, stiffness, and ultimate failure loads were compared between the techniques.

Results:

No differences in slippage were found during the cyclic loading test, and no graft fixation or tibial complex failures occurred during cyclic testing in either group. The transtibial tubercle fixation technique had higher ultimate failure loads (mean ± SD, 756.28 ± 123.43 N) as compared with interference screw fixation (602.15 ± 81.62 N; P < .05). The grafts in the transtibial tubercle fixation group were less stiff than those in the interference screw fixation group (84.43 vs 101.23 N/mm; P < .05).

Conclusion:

Transtibial tubercle fixation achieved higher ultimate failure loads than interference screw fixation in the load-to-failure test.

Clinical Relevance:

The novel transtibial tubercle fixation technique compared favorably with interference screw fixation during ACL reconstruction. This technique does not require hardware, has a low cost, theoretically eliminates the risk of complications associated with hardware implantation (eg, graft damage and pain attributed to retained hardware requiring removal), and is relatively easy to perform.