Biomechanical and Computed Tomography Analysis of Adjustable Femoral Cortical Fixation Devices for Anterior Cruciate Ligament Reconstruction in a Cadaveric Human Knee Model

Role of Quadriceps Tendon Autograft in Primary and Revision Anterior Cruciate Ligament Reconstruction

» The quadriceps tendon (QT) autograft is becoming increasingly popular in both primary and revision anterior cruciate ligament reconstruction (ACLR).» The biomechanical properties of the QT are similar to those of the native ACL, the hamstring tendon (HT), and bone-patellar tendon-bone (BTB) autografts.» QT autograft allows surgeons to be flexible with their graft size and reconstruction technique.» The QT autograft performs in a similar fashion to the BTB and HT autografts, with excellent patient-reported outcomes, consistent postoperative knee stability, and low rates of postoperative complications including graft failure and donor site morbidity.» There are emerging data that the QT autograft is a viable option in revision ACLR.

Current strategies for enhancement of the bioactivity of artificial ligaments: A mini-review

Background and objective

Anterior cruciate ligament (ACL) reconstruction calls for artificial ligaments with better bioactivity, however systematic reviews regarding bioactivity enhancement strategies, technologies, and perspectives of artificial ligaments have been rarely found.

Methods

Research papers, reviews, and clinical reports related to artificial ligaments were searched and summarized the current status and research trends of artificial ligaments through a systematic analysis.

Results

Having experienced ups and downs since the very first record of clinical application, artificial ligaments differing in material, and fabrication methods have been reported with different clinical performances. Various manufacturing technologies have developed and realized scaffold- and cell-based strategies. Despite encouraging in-vivo and in-vitro test results, the clinical results of such new designs need further clinical examinations.

Conclusion

As the demand for ACL reconstruction dramatically increases, novel artificial ligaments with better osteoinductivity and mechanical performance are promising.

The translational potential of this article

To develop novel artificial ligaments simultaneously possessing excellent osteoinductivity and satisfactory mechanical performance, it is important to grab a glance at recent research advances. This systematic analysis provides researchers and clinicians with comprehensive and comparable information on artificial ligaments, thus being of clinical translational significance.

Current and future of anterior cruciate ligament reconstruction techniques

In recent years, anterior cruciate ligament (ACL) reconstruction has generally yielded favorable outcomes. However, ACL reconstruction has not provided satisfactory results in terms of the rate of returning to sports and prevention of osteoarthritis (OA) progression. In this paper, we outline current techniques for ACL reconstruction such as graft materials, double-bundle or single-bundle reconstruction, femoral tunnel drilling, all-inside technique, graft fixation, preservation of remnant, anterolateral ligament reconstruction, ACL repair, revision surgery, treatment for ACL injury with OA and problems, and discuss expected future trends. To enable many more orthopedic surgeons to achieve excellent ACL reconstruction outcomes with less invasive surgery, further studies aimed at improving surgical techniques are warranted. Further development of biological augmentation and robotic surgery technologies for ACL reconstruction is also required.

Anterior Cruciate Reconstruction with Quadriceps Autograft using QuadLink Anterior Cruciate Ligament FiberTag TightRope Implant

Quadriceps tendon autografts have been shown to be a reliable option for anterior cruciate ligament (ACL) reconstruction. The graft allows for optimal functional outcomes while reducing donor site morbidity. Although quadriceps graft fixation can be achieved using a variety of techniques, there is a lack of consensus on the optimal technique. Additionally, femoral fixation techniques have variance in durability and reproducibility. The purpose of this Technical Note and video is to provide our preferred method of quadriceps tendon autograft preparation and fixation using the Quad Link ACL FiberTag TightRope Implant in a single-bundle ACL reconstruction.

Confirming Proper Button Deployment of Suspensory Fixation During ACL Reconstruction

Background

Suspensory fixation of anterior cruciate ligament (ACL) reconstruction (ACLR) grafts has emerged as a popular device for femoral graft fixation. However, improper deployment of the suspensory fixation can compromise proper graft tensioning, leading to failure and revision. Also, soft tissue interposition between the button and bone has been associated with graft migration and pain, occasionally requiring revision surgery. Many surgeons rely on manual testing and application of distal tension to the graft to confirm proper button deployment on the lateral cortex of the femur for ACL graft fixation.

Purpose

To determine the reliability of the manual resistance maneuver when applying distal tension to deploy the suspensory device along the lateral cortex of the femur.

Study Design

Case series; Level of evidence, 4.

Methods

All patients undergoing ACLR with a suture button suspensory device for femoral fixation were eligible for enrollment in the study. The surgeries were performed by 3 board-certified, sports medicine fellowship-trained orthopaedic surgeons at a single outpatient surgical center between May 2018 and June 2019. All grafts were passed in a retrograde manner into the femoral tunnel, and a vigorous manual tensioning maneuver in a distal direction was placed on the graft to deploy and secure along the lateral cortex of the femur. Intraoperative mini c-arm fluoroscopy was obtained to demonstrate proper suture button positioning. If interposing tissue or an improperly flipped button was identified, rectifying steps were undertaken and recorded.

Results

A total of 51 patients with a mean age of 33.3 years were included in the study. Of these patients, 74.5% had normal suture button positioning identified via intraoperative fluoroscopic imaging, while 15.7% had interposed soft tissue and 9.8% had an improperly flipped button. In all cases, the surgeon was able to rectify the malpositioning intraoperatively.

Conclusion

Despite the manual sensation of proper suspensory button positioning, intraoperative fluoroscopy identified suture button deployment errors in ACLR 25% of the time. Correcting the malpositioning is not technically demanding. These findings advocate for routine intraoperative surveillance to confirm appropriate suture button seating during ACLR.

Adjustable Loop Femoral Cortical Suspension Devices for Anterior Cruciate Ligament Reconstruction: A Systematic Review

BACKGROUND

Anterior cruciate ligament (ACL) injury is a common sports injury. Symptomatic knee instability after this injury is usually treated operatively through ACL reconstruction. The surgery involves a tendon graft being fixed in bony tunnels drilled through femur and tibia. The fixation of the graft is of critical importance to achieving good results. One of the commonest devices used to fix the graft in the femoral bony tunnel is a fixed loop cortical suspensory device. More recently, adjustable loop cortical suspension devices have been introduced, and have gained popularity for ACL reconstruction. These allow for adjusting the length of the suspension loop after insertion. There is currently much debate concerning whether the adjustable loop devices are superior or inferior to the fixed loop devices.

PURPOSE

To critique and review the current biomechanical and clinical evidence on the use of adjustable loop devices in hamstring ACL reconstruction. To our knowledge, there have been no previous reviews of this topic.

STUDY DESIGN

Systematic review.

METHODS

This systematic review was conducted in accordance with PRISMA. Five databases were searched using multiple search terms and MeSH terms where possible. The following limits were applied: papers published in English and papers published in the last 21 years.

RESULTS

Eleven laboratory and six clinical studies were reviewed. The laboratory-based studies have frequently shown elongation of adjustable loop devices to more than 3 mm under loading protocols, whereas the clinical studies have not shown any significant differences between the patients with fixed loop and the ones with adjustable loop devices.

CLINICAL SIGNIFICANCE

This review shows a discrepancy between laboratory-based and clinical studies. The review of clinical studies in our paper would give future researchers confidence and act as a prompt to construct randomised clinical trials to investigate these devices further.

CONCLUSION

We feel that more robust clinical randomised studies and trials are needed to evaluate these new devices.

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.

A Biomechanical Study of the Role of the Anterolateral Ligament and the Deep Iliotibial Band for Control of a Simulated Pivot Shift With Comparison of Minimally Invasive Extra-articular Anterolateral Tendon Graft Reconstruction Versus Modified Lemaire Reconstruction After Anterior Cruciate Ligament Reconstruction

PURPOSE

To determine whether the deep fibers of the iliotibial band (dITB) or the anterolateral ligament (ALL) provides more control of a simulated pivot shift and whether a minimally invasive anterolateral reconstruction (ALR) designed to functionally restore the ALL and dITB is mechanically equivalent to a modified Lemaire reconstruction (MLR).

METHODS

Six matched pairs of cadaveric knees (N = 12) were subjected to a simulated pivot shift to evaluate anteroposterior translation; internal rotation; and valgus laxity at 0°, 30°, and 90° of flexion. The anterior cruciate ligament (ACL) was sectioned in all specimens, and retesting was performed. Within each pair, sequential sectioning of the ALL and dITB was performed, followed by testing; the contralateral knee was sectioned in reverse order. Knees underwent ACL reconstruction (ACLR) and repeat testing. Then, MLR (n = 6) or ALR (n = 6) was performed on matched pairs for final testing.

RESULTS

Sectioning of the dITB versus ALL (after ACL sectioning) produced significantly more anterior translation at all flexion angles (P = .004, P = .012, and P = .011 for 0°, 30°, and 90°, respectively). The ACL-plus-dITB sectioned state had significantly more internal rotation at 0° versus ACL plus ALL (P = .03). ACLR plus ALR restored native anterior translation at all flexion angles. ACLR plus MLR restored anterior translation to native values only at 0° (P = .34). We found no statistically significant differences between ACLR plus ALR and ACLR plus MLR at any flexion angle for internal rotation or valgus laxity compared with the native state.

CONCLUSIONS

ALR of the knee in conjunction with ACLR can return the knee to its native biomechanical state without causing overconstraint. The dITB plays a more critical role in controlling anterior translation and internal rotation at 0° than the ALL. The minimally invasive ALR was functionally equivalent to MLR for restoration of knee kinematics after ACLR.

CLINICAL RELEVANCE

The dITB is more important than the ALL for control of the pivot shift. A minimally invasive extra-articular tendon allograft reconstruction was biomechanically equivalent to a modified Lemaire procedure for control of a simulated pivot shift.

Editorial Commentary: The Search for the Perfect Fixation Method in Anterior Cruciate Ligament Reconstruction Continues

Anterior cruciate ligament reconstruction fixation methods have long been the subject of frequent debate. The ability to optimize tendon-to-bone or bone-to-bone healing with secure graft fixation in a manner that can be performed as minimally invasively as possible is the goal. As we continue to develop and understand various graft fixation methods, our ability to achieve this goal continues to improve.

Loop Length Change of an Adjustable-Length Femoral Cortical Suspension Device in Anatomic Rectangular Tunnel Anterior Cruciate Ligament Reconstruction With a Bone-Patellar Tendon-Bone Graft and Associated Clinical Outcomes

PURPOSE

To evaluate loop length changes of an adjustable femoral cortical suspensory fixation device and assess the clinical results after anatomic rectangular tunnel anterior cruciate ligament (ART-ACL) reconstruction with a bone-tendon-bone (BTB) graft.

METHODS

The study included 50 patients who underwent ART-ACL reconstruction with a BTB graft fixed using the adjustable-length device BTB TightRope for femoral fixation between July 2013 and December 2014. Computed tomography examinations were performed at 1 and 12 weeks after the surgery. Loop length was measured in the reconstructed plane just parallel to the femoral tunnel, including the bone plug and the button. Measurement was performed thrice, and the mean value was used. Loop length change was defined as the difference in loop length between 1 and 12 weeks after the surgery. A paired t test was conducted with the effect size for statistical analysis. At 2 years postoperatively, clinical evaluations, including subjective and objective assessments, were performed.

RESULTS

The mean loop lengths at 1 and 12 weeks were 25.77 ± 3.88 mm and 25.81 ± 3.89 mm, respectively, with a significant difference (P = .01). However, the effect size was 0.01, suggesting that the difference was not meaningful. The mean individual loop length change was 0.04 ± 0.13 mm. All individual loop length changes were within the measurement error range. At 2 years postoperatively, 49 patients (98%) were graded as normal or nearly normal according to the International Knee Documentation Committee form. The mean side-to-side difference in anterior laxity at manual maximum force was 0.2 ± 0.5 mm.

CONCLUSIONS

The loop length change of an adjustable-length femoral cortical suspension device was negligible after ART-ACL reconstruction with a BTB graft. This ART-ACL reconstruction with a BTB graft using an adjustable-length device could safely provide sufficient stability to the operated knee.

LEVEL OF EVIDENCE

Level Ⅳ, therapeutic case series.

Anterior Laxity at 2 Years After Anterior Cruciate Ligament Reconstruction Is Comparable When Using Adjustable-Loop Suspensory Fixation and Interference Screw Fixation

BACKGROUND

Adjustable-loop suspensory fixation (ALSF) devices are commonly used in anterior cruciate ligament reconstruction (ACLR). However, concern exists regarding the potential for lengthening under cyclical loads.

PURPOSE

To compare the residual anterior laxity of 2 methods of femoral fixation, ALSF versus interference screw fixation, in patients undergoing isolated ACLR in the absence of meniscal injuries. To determine the preoperative risk factors associated with residual postoperative anterior laxity.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective analysis was performed comparing 2 groups of patients that underwent primary ACLR using ALSF versus bioabsorbable interference screw fixation. Anterior knee laxity was assessed with Telos stress radiography, while functional outcomes were evaluated with the Knee injury and Osteoarthritis Outcome Score (KOOS) and Tegner activity level scale at a minimum of 2 years postoperatively. A multivariate analysis was performed to identify factors associated with residual postoperative laxity >3 mm.

RESULTS

Of the 1136 patients who underwent ACLR during the study period, 363 met the inclusion criteria. A total of 272 patients (75%) (mean age, 31.7 ± 10.7 years) with a mean follow-up of 25.7 ± 4.6 months (range, 24-36 months) consented to participate (screw group: n = 121; ALSF group: n = 151). The 2 groups were statistically comparable in terms of age, sex ratio, time from injury to surgery, graft diameter, preoperative laxity, preoperative objective International Knee Documentation Committee (IKDC) grade, and preoperative Tegner score. The mean postoperative laxity as a continuous variable was significantly different comparing the ALSF and screw groups (1.49 ± 1.98 mm and 2.32 ± 1.97 mm, respectively; P < .001). In the screw group, 76 patients (62.8%) had normal (<3 mm), 40 (33.1%) had nearly normal (3-6 mm), and 5 (4.1%) had abnormal (≥6 mm) postoperative knee laxity according to the IKDC grade, while in the ALSF group, 112 patients (74.2%) had normal, 37 (24.5%) had nearly normal, and 2 (1.3%) had abnormal laxity ( P = .0833). No significant difference was found in KOOS or Tegner scores comparing the 2 femoral fixation methods: KOOS, 90.6 ± 7.5 (ALSF group) and 90.6 ± 7.4 (screw group) ( P = .7631), versus Tegner, 6.5 ± 1.3 (ALSF group) and 6.3 ± 1.4 (screw group) ( P = .2992). A negative correlation was found between postoperative laxity and final Tegner ( r_s = -0.303, P < .001) and KOOS scores ( r_s = -0.168, P = .005). The initial univariate analysis showed differences between groups of patients with residual knee laxity ≥3 mm and <3 mm on preoperative pivot shift, preoperative laxity, age, fixation type, and preoperative objective IKDC grade. The multivariate analysis on these factors showed that the pivot shift remained the only significant predictor for residual laxity ≥3 mm for pivot shift grade 2 compared with grade 1 (odds ratio, 4.689 [95% CI, 2.465-9.286]) and for pivot shift grade 3 compared with grade 1 (odds ratio, 58.025 [95% CI, 12.757-557.741]) ( P < .001).

CONCLUSION

For primary ACLR, the use of an ALSF device for femoral fixation is associated with noninferior postoperative anterior knee laxity results compared with interference screw fixation at a minimum 2 years' follow-up. The preoperative pivot shift is the only significant risk factor for postoperative residual anterior knee laxity >3 mm.

Biomechanical comparisons of current suspensory fixation devices for anterior cruciate ligament reconstruction

PURPOSE

Cortical suspensory devices are routinely used for femoral side fixation of soft tissue graft in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the biomechanical properties of a new adjustable loop device (GraftMax®) compared with established devices (EndoButton® and TightRope®) in ACL reconstruction and to investigate whether knotting the free end of TightRope could improve biomechanical properties.

METHODS

The three cortical suspensory devices (GraftMax® Button; Conmed, EndoButton® CL; Smith & Nephew, and TightRope® RT; Arthrex) were tested under cyclic load (50-250 N for 1000 cycles) and pull-to-failure conditions at 50 mm/h in a device-only setup using a tensile testing machine. The TightRope was additionally tested with its free suture ends knotted. The statistical analyses were done with one-way analysis of variance (ANOVA) and post hoc Tukey HSD tests.

RESULTS

There are significant differences in the load-to-failure among the devices. The EndoButton showed the highest mean failure load at 1204.7 N compared to other devices (GraftMax (914.2 N), knotted TightRope (868.1 N) and TightRope (800.1 N) (p < 0.001). The mean total displacement after 1000 cycles was 0.76 mm, 2.11 mm, 1.56 mm and 1.38 mm for the EndoButton, GraftMax, TightRope, and knotted TightRope, respectively. The EndoButton showed significantly better properties than both the GraftMax (p = 0.000) and the TightRope (p = 0.020) but not the knotted TightRope (p = n.s.) in total displacement. However, there was no significant difference between the TightRope and GraftMax (p = n.s.).

CONCLUSION

The fixed loop (EndoButton) showed significantly better mechanical properties in failure load and displacement than TightRope or GraftMax in this biomechanical study. However, the mechanical properties of the GraftMax is comparable to the TightRope. Moreover, the knotting of TightRope improved mechanical properties in total displacement more than TightRope, but not in failure load.

CLINICAL RELEVANCE

The biomechanical properties of the GraftMax are comparable to the TightRope. The TightRope, when knotted, shows an improvement both in load to failure and cyclic displacement, though the differences are not significant.

Editorial Commentary: Not All Cortical Suspensory Fixation Devices Are Created Equal

Fixed-loop and adjustable-loop cortical suspensory fixation devices are both available as graft fixation options for surgeons. Fixed devices require facilities to manage various available sizes in the inventory, whereas adjustable devices are a true one-size-fits-all device requiring one inventory item for all cases. Adjustable-loop devices are also the only device that allows for postfixation tightening that may be advantageous for the surgeon who desires to tighten and retighten the graft construct once again before the case is completed.

Editorial Commentary: Controversy on Fixation Properties of the Adjustable-Loop Cortical Suspension Fixation Device Used for Anterior Cruciate Ligament Reconstruction

Two adjustable-loop femoral cortical suspensory fixation devices tested in this cadaveric human knee study could afford comparably secure fixation properties under a cyclic loading condition.