Suspensory fixation of grafts in anterior cruciate ligament reconstruction: a biomechanical comparison of 3 implants

Biomechanical Comparison of 3 Adjustable-Loop Suspensory Devices for All-Inside ACL Reconstruction: A Time-Zero Full-Construct Model

Background

Little is known about the stability of adjustable-loop devices (ALDs) for anterior cruciate ligament (ACL) reconstruction (ACLR).

Purpose

To evaluate the stabilization behavior of 3 different types of ALDs for all-inside ACLR in a full-construct surgical technique-based manner.

Study Design

Controlled laboratory study.

Methods

The femoral and tibial devices of Ultrabutton (Smith & Nephew), Infinity (Conmed), and TightRope II (Arthrex) were applied to quadrupled bovine tendon grafts (n = 8 each) with tibial-sided traction applied (350 N) for graft tensioning in a simulated fully extended knee. Knotless femoral graft fixation was based on either a suture-locking device (SLD; Ultrabutton), button-locking device (BLD; Infinity), or dual-locking device (DLD; TightRope II). All constructs were progressively loaded (50 N/500 cycles) from 50 to 300 N for 3000 cycles (0.75 Hz), including complete unloading situations and pull to failure (50 mm/min). Construct elongation, stiffness, and ultimate load were analyzed.

Results

BLD showed significantly greater initial elongation (-2.69 ± 0.15 mm) than DLD (-3.19 ± 0.21 mm; P < .001) but behaved similarly to SLD (-2.93 ± 0.23 mm). While DLD and SLD had the smallest initial elongation at the same significance level, they behaved opposite to each other with gradually increasing peak loading. At the end of testing, DLD had the lowest (-0.64 ± 0.32 mm) and SLD the highest (3.41 ± 1.01 mm) total elongation (P < .003 for both). SLD displayed significantly higher dynamic elongation (6.34 ± 0.23 mm) than BLD (3.21 ± 0.61 mm) and DLD (2.56 ± 0.31 mm) (P < .001 for both). The failure load of BLD (865.0 ± 183.8 N) was significantly lower (P < .026) compared with SLD and DLD (>1000 N). The predominant failure mode was suture rupture and tibial bone breakage with button subsidence (SLD, n = 4). No significant difference in stiffness between constructs was found.

Conclusion

While DLD successfully restricted critical construct elongation, BLD partially and SLD completely exceeded the clinical failure threshold (>3 mm) of plastic elongation with loop lengthening during increasing cyclic peak loading with complete unloading. Higher failure loads of SLD and DLD implants (>1000 N) were achieved at similar construct stiffness to BLD.

Clinical Relevance

A detailed biomechanical understanding of the stabilization potential is pertinent to the continued evolution of ALDs to improve clinical outcomes.

Biomechanical evaluation of an allograft fixation system for ACL reconstruction

The purpose of this study was to compare the biomechanical stability, especially graft slippage of an allograft screw and a conventional interference screw for tibial implant fixation in ACL reconstruction. Twenty-four paired human proximal tibia specimens underwent ACL reconstruction, with the graft in one specimen of each pair fixed using the allograft screw and the other using the conventional interference screw. Specimens were subjected to cyclic tensile loading until failure. The two fixation methods did not show any statistical difference in load at graft slippage (p = 0.241) or estimated mean survival until slippage onset (p = 0.061). The ultimate load and the estimated mean survival until failure were higher for the interference screw (p = 0.04, and p = 0.018, respectively). Graft displacement at ultimate load reached values of up to 7.2 (interference screw) and 11.3 mm (allograft screw). The allograft screw for implant fixation in ACL reconstruction demonstrated comparable behavior in terms of graft slippage to the interference screw but underperformed in terms of ultimate load. However, the ultimate load, occurring at progressive graft slippage, may not be considered a direct indicator of clinical failure.

Comparison of the mechanical properties and mechanical damages to tendon tissue in three suspensory fixation techniques

Background

Anterior cruciate ligament (ACL) injury is the most common traumatic injury to the knee joint. Suspensory fixation has become popular in ACL reconstruction because of its high primary stability, less invasiveness, and surgical convenience. There are two common types of suspensory fixation devices: those with fixed-length and those with adjustable-length loops. Owing to structural differences and differences in initial tensioning techniques, it is expected that mechanical property and damage to the tendons will vary from device to device; however, no literature has examined this so far. The main purpose of this study was to evaluate the damage caused to the tendon by three different suspensory fixation devices. An effective mechanical test was carried out as a prerequisite.

Methods

First, the mechanical properties of simple loop device (SLD) as fixed-length loop device, first-generation, and second-generation adjustable devices (AD1 and AD2) as adjustable-length loop devices were tested (isolated device testing). Second, each device was tested using bovine extensor tendons (specimen testing). Cyclic testing included 2000 cycles; the devices were subsequently displaced until failure, and the ultimate tensile strength was determined using isolated device testing. Six samples of 3 devices were used in each testing experiment. After specimen testing, the surface structure of the tendon was evaluated quantitatively using optical coherence tomography (OCT) and our original histological scoring system.

Results

During isolated device testing, SLD demonstrated the least cyclic displacement, followed by AD1 and AD2. The highest ultimate tensile strength was observed in AD2, followed by SLD and AD1. In specimen testing, the least cyclic displacement was observed in SLD, followed by AD1 and AD2. Histologically, AD1 demonstrated a significantly lower score, with damaged surface morphology, than SLD and AD2. OCT values were significantly higher, with a more disturbing tendon surface structure, in AD1 than in SLD and AD2.

Conclusions

The first-generation adjustable loop device exhibited greatest graft tissue damage at the suspensory site in a clinically relevant setting. The thinner adjustable loop mechanism may have elevated graft damage by frictional stresses during loop adjustment or by repetitive tensioning stresses.

BIOMECHANICAL EVALUATION OF AN INVERTED FIXATION FOR ACL RECONSTRUCTION WITH NONMETALLIC HARDWARE AND TIBIAL SUBCORTICAL SUPPORT TO INCREASE STRENGTH AT THE TIBIAL SITE

In this paper, we evaluate the initial biomechanical properties of an anterior cruciate ligament (ACL) reconstruction technique that inverts the anatomical location of the commonly used hardware and relies the tibial fixation on the subcortical bone to increase tibial site strength. Four 7-specimen groups were tested in a porcine model: for the control ACL reconstruction technique, the femur with a cross-pin fixation supported in the trabecular bone and the tibia with a biodegradable interference screw (BIS); for the new proposed technique, the femur with a BIS and the tibia with a cross-pin fixation leaned on the tibial subcortical bone. The specimens were subjected to cyclic and load-to-failure tests to compute their biomechanical performance. At the tibia, the cross-pin fixation revealed higher resistance than the BIS ([Formula: see text] for ultimate load and [Formula: see text] = 0.006 for yield load), additionally cyclic and total displacement at representative loads showed extremely high values with BIS fixation (in two specimens greater than 9[Formula: see text]mm for 250 N and greater than 10[Formula: see text]mm for 450[Formula: see text]N). At the femur, no differences between fixations were observed. The inverted ACL reconstruction improves resistance at the tibial site with respect to the control technique, with similar resistance at the femoral site and no differences in total displacement at representative loads. It offers a useful and robust solution when greater tibial resistance is required.

Anterior to Posterior Bone Plug Suture Tunnels Provide Optimal Biomechanics for Bone−Patellar Tendon−Bone Anterior Cruciate Ligament Graft

Purpose

Methods

Results

Clinical Relevance

Risk Factors for Femoral Cortical Button Malposition in Posterior Cruciate Ligament Reconstruction

Background

Femoral cortical button suspension fixation is a popular and reliable technique for posterior cruciate ligament reconstruction (PCLR). Button malposition during graft fixation can lead to postoperative graft loosening.

Purpose

To determine the risk factors of femoral cortical button malposition in PCLR when neither direct visualization nor intraoperative fluoroscopy is used.

Study Design

Case-control study; Level of evidence, 3.

Methods

Of the 206 consecutive patients who underwent PCLR without direct visualization or intraoperative radiographs in 2019 at a single institution, 182 met the selection criteria and were included in the study. The distance from the suspension button to the femoral cortex was measured on postoperative computed tomography scans. The button was considered malpositioned if its distance to the femoral cortex was ≥2 mm. We evaluated patient-related and surgery-related variables, including age, sex, concomitant ligament reconstruction, button type, and surgeon experience. Multivariate logistic regression was conducted to evaluate the risk factors for button malposition.

Results

The overall prevalence of button malposition was approximately 17.0% (31/182), and the mean distance from the button to the femoral cortex was 6.11 ± 5.82 mm in the malposition group. Male sex was the most significant risk factor for button malposition (odds ratio [OR], 13.86; 95% confidence interval [CI], 1.73-111.17; P = .013). Other independent risk factors were low surgical volume (completing ≤3 procedures; OR, 6.41; 95% CI, 1.89-21.72; P = .003), concomitant ligament reconstruction (OR, 5.56; 95% CI, 2.12-14.58; P < .001), and fixed-loop button (OR, 3.96; 95% CI, 1.11-14.18; P = .034).

Conclusion

Male sex, low surgical volume, concomitant ligament reconstruction, and fixed-loop button were independent risk factors for femoral cortical button malposition during PCLR.

The "Not" Good, the Bad and the Ugly: Prevention and Management of Common Intraoperative and Delayed Complications in Orthopedic Sports Medicine Surgical Procedures

Despite advances in techniques designed to make arthroscopic sports medicine procedures simple, complications still arise in the operating room; even in the most trained hands. However, what marks a skilled surgeon is not just the ability to steer the ship amidst smooth seas, but a knack for getting out of trouble once things deviate from the set course. Each surgical case presents a unique challenge, and no 2 are the same. For this reason, a true expert surgeon must know how to deal with "complications" ranging from a mild swell to a raging storm. In this review we present strategies to prevent and navigate some of the most common, and fearsome complications a sports medicine surgeon may face during surgery. A great surgeon is one that acknowledges that throughout their career it is not a question of "if" these situations will arise, but "when"; and preparation is the key to success.

Anterior Cruciate Ligament Length in Pediatric Populations: An MRI Study

Background:

As regards anterior cruciate ligament (ACL) reconstruction (ACLR), graft diameter has been identified as a major predictor of failure in skeletally mature patients; however, this topic has not been well-studied in the higher risk pediatric population. Hamstring tendon autograft configuration can be adjusted to increase graft diameter, but tendon length must be adequate for ACLR. Historical parameters of expected tendon length have been variable, and no study has quantified pediatric ACL morphology with other osseous parameters.

Purpose:

To develop magnetic resonance imaging (MRI)–derived predictors of native ACL graft length in pediatric patients so as to enhance preoperative planning for graft preparation in this skeletally immature patient population.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

MRI scans of 110 patients were included (64 girls, 46 boys; median age, 10 years; range, 1-13 years). Patients with musculoskeletal diseases or prior knee injuries were excluded. The following measurements were taken on MRI: ACL length; sagittal and coronal ACL inclination; intercondylar notch width and inclination; and femoral condyle depth and width. Associations between these measurements and patient sex and age were investigated. Univariate linear regression and multivariable regression models were created for each radiographic ACL measure to compare R².

Results:

Female ACL length was most strongly associated with the depth of the lateral femoral condyle as viewed in the sagittal plane (R² = 0.65; P < .001). Other statistically significant covariates of interest included distal femoral condylar width, age, and coronal notch width (P < .05). For males, the ACL length was most strongly associated with the distal femoral condyle width as viewed in the coronal plane (R² = 0.70; P < .001). Other statistically significant covariates of interest for male ACL lengths were lateral femoral condyle depth, age, and coronal notch width (P < .05).

Conclusion:

In pediatric populations, femoral condylar depth/width and patient age may be valuable in assessing ACL size and determining appropriate graft dimensions and configuration for ACLRs. The use of this information to optimize graft diameter may lower the rates of ACL graft failure in this high-risk group.

On Measuring Implant Fixation Stability in ACL Reconstruction

Numerous methods and devices are available for implant fixation in anterior cruciate ligament (ACL) reconstruction. Biomechanical data indicate high variability in fixation stability across different devices. This study aims to provide a better insight into measuring the structural characteristics and mechanical behavior of ACL implant fixations. Fourteen human tibial specimens with reconstructed ACLs were subjected to progressively increasing dynamic loading until failure. The motions of the tibia, the proximal and distal graft ends, as well as the testing frame and actuator, were continuously recorded via a motion tracking system. Significantly higher displacements of the machine actuator (1.0 mm at graft slippage onset, and 12.2 mm at ultimate load) were measured compared to the displacements of the proximal (0.8 and 4.3 mm, respectively) and distal graft (0.1 and 3.4 mm, respectively) ends. The displacements measured at different sites showed significant correlations. The provided data suggest significant and systematic inaccuracies in the stiffness and slippage of the fixation when using machine displacement, as commonly reported in the literature. The assessment of the distal graft displacement excludes the artifactual graft elongation, and most accurately reflects the graft slippage onset indicating clinical failure. Considering the high displacement at the ultimate load, the ultimate load could be used as a standardized variable to compare different fixation methods. However, the ultimate load alone is not sufficient to qualitatively describe fixation stability.

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.

Clinical Reliability of Adjustable Femoral Cortical Suspensory Fixation in Anterior Cruciate Ligament Reconstruction and Correlation of Clinical Outcomes With Demographic and Perioperative Factors

Background and objective

The primary goal of anterior cruciate ligament reconstruction (ACLR) is to protect the initial graft fixation against heavy loads encountered during the rehabilitation phase. The purpose of this study was to evaluate the functional outcomes (Lysholm score) and laxity [anterior tibial translation (ATT), anterior drawer test, Lachman test, and pivot shift test] of ACLR with adjustable-loop femoral cortical suspensory fixation (CSF) and tibial interferences crew fixation.

Methods

This study included 100 patients who underwent primary ACL reconstruction using quadruple hamstring grafts secured with TightRope® (Arthrex Inc, Naples, FL) femoral fixation and an interference screw on the tibial end. Six patients were excluded from the final analysis (four lost to follow-up, one suffered re-injury, and one had septic arthritis). The remaining 94 patients were evaluated for laxity and functional outcomes preoperatively, as well as at one, six, and 12 months postoperatively. Regression analysis was performed to determine the association between outcomes and 11 independent variables. This was designed as a prospective cohort study (level of evidence: II).

Results

The mean age of the participants was 28.46 ± 7.01 years. The median preoperative Lysholm knee score of 49 (mean ± SD: 48.2 ± 5.42) improved to 93 (92.7 ± 2.1) at six months and 98 (97.6 ± 2.1) at the one-year follow-up. The improvement was found to be statistically significant (p<0.01). The median ATT was 10 mm preoperatively, which decreased to 2 mm at one month, remained the same at six months, and rose to 3 mm at the one-year follow-up. ATT was found significantly reduced at one month postoperatively (p<.001) and did not show any significant further changes at subsequent follow-ups (p>0.05). Multiple linear regression revealed that one-year postoperative ATT (Rolimeter, Aircast Europa, Stephanskirchen, Germany) was independent of all demographic and perioperative variables tested.

Conclusion

Quadrupled hamstring graft ACLR with adjustable-loop fixation showed excellent subjective and objective outcomes with no residual laxity or failure of graft over mid-term follow-up. Postoperative laxity was not correlated with graft and tunnel dimensions.

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.

The effect of soft tissue interposition of the Endobutton on clinical results and on its postoperative migration after single-bundle anterior cruciate ligament reconstruction

BACKGROUND

This study aimed to investigate the possible consequences of soft tissue interposition of Endobutton on clinical outcomes and reoperation rates after anterior cruciate ligament reconstruction.

METHODS

We measured the distance between the centre of the Endobutton and the lateral femoral cortex on the postoperative first day anteroposterior X-rays of the 156 knees that underwent anterior cruciate ligament reconstruction. Those with a distance less than 1 mm were regarded as Group 1 (118 patients), the ones between 1 mm and 2 mm were regarded as Group 2 (30 patients) and the ones more than 2 mm were regarded as Group 3 (8 patients). The movement of the Endobutton of more than 1 mm along the femoral tunnel axis on anteroposterior X-rays or its rotation by more than 5° on lateral X-rays during follow-up were considered migration. Clinical assessment scores (Lysholm, Tegner Activity Scale), clinical examination tests, and rates of Endobutton migration in the groups were analysed.

RESULTS

Eleven Endobuttons (9.3%) in Group 1, 26 Endobuttons (86.7%) in Group 2 and all of the 8 Endobuttons (100%) in Group 3 were observed to have migrated. Clinical results and examination tests showed no significant difference between Groups 1 and 2, whereas a significant difference was detected in Group 3 compared to Groups 1 and 2 (p < 0.05).

CONCLUSION

Soft tissue interposition is a major cause of Endobutton migration, and an interposition over 2 mm between the Endobutton and the lateral femoral cortex can negatively affect the outcomes after an anterior cruciate ligament surgery.

Hamstring Anterior Cruciate Ligament Reconstruction Using an Adjustable-Loop Cortical Suspension Device: Immediate Postoperative Magnetic Resonance Imaging

The purpose of this study is to determine whether the hamstring grafts are fully inserted into the femoral tunnel with the adjustable loop using immediate postoperative magnetic resonance imaging (MRI) after anterior cruciate ligament (ACL) reconstructions. A total of 62 consecutive patients underwent hamstring ACL reconstruction using an adjustable-loop cortical suspension device for the femoral fixation and the Intrafix sheath and screw for the tibial fixation. Multiplanar reformatted images of 3-T MRI scans were obtained at the 1st postoperative day before weight bearing is initiated in all patients to evaluate the gap (the tunnel-graft gap) between the top of the hamstring graft and top of the femoral tunnel. Postoperative MRI scans showed that the tunnel-graft gap was 1.5 ± 2.7 mm (range, 0-12 mm). In 43 (69.4%) patients, there was no gap between the top of the femoral tunnel and hamstring graft. In 19 (30.6%) patients, there was a gap between the tunnel and graft, and nine patients demonstrated a tunnel-graft gap greater than 5 mm. Immediate postoperative MRI scans demonstrated that an adjustable-loop cortical suspension device may not pull the hamstring graft completely into the femoral tunnel.

Confirmation of Femoral Button Deployment Under Direct Visualization During ACL Reconstruction Is Not Beneficial

The purpose of this study was to determine whether direct visualization of adjustable-loop cortical suspensory button deployment onto the lateral femur increases the cortical contact rate of the button, thereby improving clinical outcomes after anterior cruciate ligament (ACL) reconstruction. Sixty-five single-bundle anteromedial portal ACL reconstructions using an adjustable-loop button were retrospectively divided into 2 groups according to use of the blind pulling technique (control group; 32 patients) or the direct visualization technique (visualization group; 33 patients) when confirming deployment of the button. Cortical contact rate of the button on immediate and 2-year postoperative radiographs, knee stability measured using a KT-1000 arthrometer, and functional scores (Lysholm score and International Knee Documentation Committee score) at 2 years postoperative were compared between the groups. There was no significant difference in femoral cortical contact rate between the groups immediately (56% control group vs 55% visualization group; P=1.000) and at 2 years postoperative (78% control group vs 82% visualization group; P=.764). At 2 years postoperative, there was no difference between the groups regarding knee stability (1.3±0.9 mm vs 1.5±0.8 mm, respectively; P=.404), Lysholm score (P=.436), and International Knee Documentation Committee score (P=.507). Confirmation of adjustable-loop button deployment under direct visualization during anteromedial portal ACL reconstruction neither increased cortical contact rate nor improved clinical outcomes. [Orthopedics. 2020;43(5);270-276.].

ACL reconstruction using a quadruple semitendinosus graft with cortical fixations gives suitable isokinetic and clinical outcomes after 2 years

PURPOSE

The objective of this single-center randomized single-blinded trial was to assess the hypothesis that anterior cruciate ligament reconstruction (ACLR) using a four-strand semitendinosus (ST) graft with adjustable femoral and tibial cortical fixation produced good outcomes compared to an ST/gracilis (ST/G) graft with femoral pin transfixation and tibial bioscrew fixation. Follow-up was 2 years.

METHODS

Patients older than 16 years who underwent primary isolated ACLR included for 1 year until August 2017 were eligible. The primary outcome measures were the subjective International Knee Documentation Committee (IKDC) score, isokinetic muscle strength recovery, and return to work within 2 years. The study was approved by the ethics committee.

RESULTS

Of 66 eligible patients, 60 completed the study and were included, 33 in the 4ST group and 27 in the ST/G group. Mean age was 30.5 ± 8.9 years in the 4ST group and 30.3 ± 8.5 in the ST/G group (n.s.). No significant between-group differences were found for mean postoperative subjective IKDC (4ST group, 80.2 ± 12.5; ST/G group, 83.6 ± 13.6; n.s.), side-to-side percentage deficits in isokinetic hamstring strength (at 60°/s: ST group, 17% ± 16%; ST/G group, 14% ± 11%; n.s.) or quadriceps strength (at 60°/s: ST group, 14% ± 12%; ST/G group, 19% ± 17%; n.s.), return to work, pain during physical activities, side-to-side differential laxity, balance, loss of flexion/extension, or surgical complications.

CONCLUSION

This trial demonstrates that functional outcomes after 4ST for ACLR with cortical fixations could be as good, although not better, than those obtained using ST/G. The 4ST technique spares the gracilis tendon, which thus preserves the medial sided muscle and thereby could improve function and limit donor-side morbidity.

LEVEL OF EVIDENCE

Level I.

Assessment of fixation for anterior cruciate ligament reconstruction using oversized suspensory devices on full-length femoral tunnels

BACKGROUND

In ACL repair, full-length single-diameter tunnels facilitate anatomic femoral fixation with suspensory devices, especially with outside-in techniques, and are required after accidental cortical perforation. With tunnel diameters over 6 mm, fixation resistance using regular suspensory devices may not suffice. Oversized cortical footprint devices could be a solution to guarantee fixation performance in larger tunnel diameters. This study aims to assess the biomechanical properties of ACL femoral fixation provided by two enlarged suspensory devices of similar characteristics, a fixed loop (G-Lok™ with G-Lok-XL™) and an adjustable loop (ProCinch™ with G-Lok-XL™), resting on a full-length 9 mm diameter tunnel compared to the widely accepted regular fixed-loop device (G-Lok™) on a socket tunnel.

METHODS

Twenty-seven fresh frozen porcine femurs and flexor digitorum profundus tendons were randomly assigned to a study group depending on the fixation method used (N = 9). Graft-femur constructs were subjected to a traction cyclic test (5000 cycles, [50-250]N load, 1 Hz) followed by a load-to-failure test (v = 1 mm/s). Residual displacement during the cyclic test and stiffness, displacements at physiological loads, ultimate load and corresponding displacement during the load-to-failure test were determined.

FINDINGS

No significant differences could be established for any parameter measured in the comparison between the control with the socket tunnel and the oversized fixations with full-length tunnels.

INTERPRETATION

ACL femoral fixation achieved in full-length single diameter tunnels by using an enlarged suspension device, both with a fixed or an adjustable loop, provide similar biomechanical properties to the gold-standard fixed-loop device in a socket tunnel. Therefore, its clinical use may be safe.

Biomechanical testing of fixed and adjustable femoral cortical suspension devices for ACL reconstruction under high loads and extended cyclic loading

Purpose

To compare loop elongation after 5000 cycles, loop-elongation at failure, and load at failure of the fixed-loop G-Lok device and three adjustable-loop devices (UltraButton, RigidLoop Adjustable and ProCinch RT), during testing over extended cycles under high loading.

Methods

Five devices of each type were tested on a custom-built rig fixed to an Instron machine. The testing protocol had four stages: preloading, cyclic preconditioning, incremental cyclic loading and pull-to-failure. Outcome measures were loop elongation after 5000 cycles, loop-elongation at failure, and load at failure.

Results

The loop elongation after 5000 cycles for G-Lok was 1.46 ± 0.25 mm, which was comparable to that of RigidLoop (1.51 ± 0.16 mm, p = 1.000) and ProCinch (1.60 ± 0.09 mm, p = 1.000). In comparison, the loop elongation for UltraButton was 2.66 ± 0.28 mm, which was significantly larger than all other devices (p = 0.048). The failure load for all devices ranged between 1455 and 2178 N. G-Lok was significantly stronger than all adjustable-loop devices (p = 0.048). The elongation at failure was largest for UltraButton (4.20 ± 0.33 mm), which was significantly greater than G-Lok (3.17 ± 0.33 mm, p = 0.048), RigidLoop (2.88 ± 0.20 mm, p = 0.048) and ProCinch (2.78 ± 0.08 mm, p = 0.048). There was no significant difference in elongation at failure for the rest of the devices.

Conclusions

Our study has shown that the G-Lok fixed-loop device and the three adjustable-loop devices (UltraButton, RigidLoop Adjustable and ProCinch RT) all elongated less than 3 mm during testing over an extended number of cycles at high loads, nonetheless, the fixed loop device performed best in terms of least elongation and highest load at failure.

The improved cortical button shows better breaking strength of sutures compared with 10 original cortical button after cyclic loading

Background

Suspensory cortical buttons are widely used for fixation of reconstructed ligaments during anterior cruciate ligament (ACL) reconstruction because they have high usability and a favorable fixing force. However, it is not always easy to fix a reconstructed ACL while maintaining appropriate ligament tension. Therefore, we developed an improved cortical button that provides temporary tension until suturing is completed.

Methods

Button holes of our improved EndoButton are not perpendicular to the bone surface on which the button is placed, but have an angle of 45 degrees so that the button can be temporarily fixed by applying tension to the suture. The improved EndoButton and the original EndoButton (Smith & Nephew Inc., Andover, Massachusetts) were each tied to FiberWire 5/7 metric (5 M) (manufactured by Arthrex). Ten cycles of preliminary loading (0–50 N) were applied to each suture, followed by test loading (0–250 N) for 500 or 1000 cycles. Then, a tensile test was performed at a displacement velocity of 20 mm/min.

Results

The breaking strength of the sutures of the improved EndoButton were tend to higher than those of the sutures of the original EndoButton after 1000 loading cycles (p = 0.067, d = 0.883). The moduli of rigidity of the sutures of the improved EndoButton were higher than those of the sutures of the original EndoButton after 500 loading cycles (p = 0.027) and remained almost the same regardless of the number of loading cycles.

Conclusion

We found that compared with the original cortical button, the improved cortical button was better able to retain suture breaking strength and modulus of rigidity, regardless of the number of load cycles.

Biomechanical Evaluation of a Novel Loop Retention Mechanism for Cortical Graft Fixation in ACL Reconstruction

BACKGROUND

Implant fixation by means of a cortical fixation device (CFD) has become a routine procedure in anterior cruciate ligament reconstruction. There is no clear consensus whether adjustable-length CFDs are more susceptible to loop lengthening when compared with pretied fixed-length CFDs.

PURPOSE

To assess biomechanical performance measures of 3 types of CFDs when subjected to various loading protocols.

STUDY DESIGN

Controlled laboratory study.

METHODS

Three types of CFDs underwent biomechanical testing: 1 fixed length and 2 adjustable length. One of the adjustable-length devices is based on the so-called finger trap mechanism, and the other is based on a modified sling lock mechanism. A device-only test of 5000 cycles (n = 8 per group) and a tendon-device test of 1000 cycles (n = 8 per group) with lower and upper force limits of 50 and 250 N, respectively, were applied, followed by ramp-to-failure testing. Adjustable-length devices then underwent further cyclic testing with complete loop unloading (n = 5 per group) at each cycle, as well as fatigue testing (n = 3 per group) over a total of 1 million cycles. Derived mechanical parameters were compared among the devices for statistical significance using Kruskal-Wallis analysis of variance followed by post hoc Mann-Whitney U testing with Bonferroni correction.

RESULTS

All CFDs showed elongation <2 mm after 5000 cycles when tested in an isolated manner and withstood ultimate tensile forces in excess of estimated peak in vivo forces. In both device-only and tendon-device tests, differences in cyclic performance were found among the devices, favoring adjustable-length fixation devices over the fixed-length device. Completely unloading the suspension loops, however, led to excessive loop lengthening of the finger trap device, whereas the modified sling lock device remained stable throughout the test. The fixed-length device displayed superior ultimate strength over both adjustable-length devices. Both adjustable-length devices showed adequate fatigue behavior during high-cyclic testing.

CONCLUSION

All tested devices successfully prevented critical construct elongation when tested with constant tension and withstood ultimate loads in excess of estimated in vivo forces during the rehabilitation phase. The finger trap device gradually lengthened excessively when completely unloaded during cyclic testing.

CLINICAL RELEVANCE

Critical loop lengthening may occur if adjustable-length devices based on the finger trap mechanism are repeatedly unloaded in situ.

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.

Graft Fixation and Timing of Surgery Are Predictors of Early Anterior Cruciate Ligament Revision: A Cohort Study from the Swedish and Norwegian Knee Ligament Registries Based on 18,425 Patients

The identification of surgical risk factors for early anterior cruciate ligament (ACL) revision is important when appropriate treatment for patients undergoing primary ACL reconstruction is selected. The purposes of this study were to determine the short-term ACL revision rate of patients undergoing primary ACL reconstruction and to identify surgical risk factors for ACL revision within 2 years of primary ACL reconstruction.

Clinical Outcome of Arthroscopic Posterior Cruciate Ligament Reconstruction with Adjustable-Loop Femoral Cortical Suspension Devices

BACKGROUND

Incidence of isolated posterior cruciate ligament (PCL) injury is lower than PCL rupture is associated with other knee injuries. Adjustable loop femoral cortical suspension device is commonly used for femoral graft fixation during PCL reconstruction.

AIM

This study purpose is to describe the functional outcome of PCL reconstruction using an adjustable loop femoral cortical suspension device.

METHODS

This study used prospective design with consecutive sampling. All patients underwent PCL reconstruction with adjustable loop femoral cortical suspension devices using peroneus longus tendon autograft. Patients were evaluated at 6 months after surgery using posterior drawer test and functional outcome scoring system (Lysholm knee score, Cincinnati Score and International Knee Documentation Committee (IKDC) score).

RESULTS

20 patients were enrolled in this study with a mean age of 27.65 ± 9.78. Lysholm knee means the score was improved from 59.80 ± 18.73 pre-operative and 80.55 ± 11.72 post-operative (p < 0.05). Cincinnati mean score was improved from 52.01 ± 20.29 pre-operative to 72.95 ± 15.26 post-operative (p < 0.05). IKDC mean score was improved from 48.36 ± 13.18 at pre-operative to 72.5 ± 13.13 post-operative (p < 0.05).

CONCLUSION

PCL reconstruction using adjustable loop femoral cortical suspension device using peroneus longus tendon autograft showed good clinical outcome and knee functional outcome (Lysholm, Cincinnati, and IKDC score) at 6 months follow-up.

Fixed- Versus Adjustable-Loop Devices for Femoral Fixation in Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To compare biomechanical and clinical outcomes between adjustable-loop devices (ALDs) and fixed-loop devices (FLDs) in the femoral fixation component of anterior cruciate ligament reconstruction (ACLR) using a hamstring autograft or allograft.

METHODS

A multi-database search was performed on July 18, 2018, according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. All articles directly comparing ALDs and FLDs in ACLR using hamstring grafts were included. Non-English-language articles were excluded.

RESULTS

We included 13 biomechanical, 2 prospective, and 6 retrospective studies in this review. Retensioning of ALDs was performed in 4 of 13 biomechanical studies and in all clinical studies. Biomechanically, 11 studies showed a statistically significantly larger maximum irreversible displacement of the graft in the ALD group. Two studies showed no statistically significant difference with retensioning of the TightRope ALD, whereas all 3 studies that examined knotting of ALDs showed no statistically significant difference between the FLD and ALD groups. Five studies reported statistically significantly higher graft stiffness for FLDs than ALDs. Retensioning or knotting did not produce any significant change in construct stiffness. Nine studies reported a statistically significantly higher ultimate load to failure for FLDs. With knotting of ALDs, this difference was no longer statistically significant in only 1 study. Clinical studies showed no statistically significant differences in clinical, functional, radiologic, and complication outcomes between both groups.

CONCLUSIONS

Despite the superior biomechanical properties of FLDs, ALDs and FLDs yielded similar clinical outcome scores and graft rerupture rates. Biomechanical outcomes were improved with retensioning of ALDs after tibial fixation, as per manufacturer recommendations.

LEVEL OF EVIDENCE

Level III, systematic review of Level III and IV studies.

Femoral Cortical Button Malposition Rates in Anterior Cruciate Ligament Reconstruction: A Retrospective Review

The purpose of this study was to determine the rate of malposition of the femoral cortical button during anterior cruciate ligament reconstruction and to present a classification system of femoral cortical button positioning that is both accurate and reproducible. A total of 361 patients undergoing primary anterior cruciate ligament reconstruction during a 5-year period were identified, and postoperative button position was graded as follows: reduced and congruent (entirety of button <2 mm from cortex); reduced and incongruent (part of button <2 mm from cortex, part of button >2 mm from cortex); displaced (entirety of button >2 mm from cortex); intraosseous (all or part of button remains within bone); or ungradable. Radiographs were evaluated by 2 orthopedic surgeons at 2 time points to define interrater and intrarater reliability. A total of 312 buttons (86.43%) were reduced and congruent, 18 (4.99%) were reduced and incongruent, 10 (2.77%) were displaced, 13 (3.60%) were intraosseous, and 8 (2.21%) were ungradable based on the available postoperative imaging. There was outstanding interrater reliability, with an overall kappa value of 0.84. Intrarater reliability for raters 1 and 2 was 0.77 and 0.83, respectively, representing excellent intrarater reliability for both observers. Cortical button placement during femoral fixation in anterior cruciate ligament reconstruction is variable. This study presents a classification system for grading femoral cortical button placement that is accurate and reproducible. An organized grading scheme may be useful for future studies of the effect of cortical button malposition on stability and durability of fixation. [Orthopedics. 2019; 42(1):e56-e60.].

Clinical and Functional Outcomes of Anterior Cruciate Ligament Reconstruction at a Minimum of 2 Years Using Adjustable Suspensory Fixation in Both the Femur and Tibia: A Prospective Study

Background:

The success of anterior cruciate ligament (ACL) reconstruction requires reliable and rigid graft fixation. Cortical suspensory fixation (CSF) devices have become an acceptable alternative to interference screws for soft tissue ACL grafts. However, CSF devices have been reported to be associated with tunnel widening and increased postoperative anterior laxity compared with interference screw fixation. Adjustable CSF devices were introduced to avoid these problems but have been associated with graft lengthening and inconsistent outcomes.

Purpose:

To (1) report the side-to-side difference (SSD) in anterior laxity at 150 N, clinical scores, and failure rates 2 years after ACL reconstruction with 4-strand semitendinosus autografts using an adjustable CSF device and (2) determine the preoperative factors associated with clinical outcomes.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

A total of 131 patients who had undergone primary ACL reconstruction, performed with 4-strand semitendinosus grafts that were secured using Pullup adjustable-length CSF devices with femoral and tibial fixation techniques, were prospectively enrolled in this study; 34 patients were excluded because of contralateral instability or ipsilateral knee injuries that required additional surgery. This left a cohort of 97 patients who were evaluated preoperatively and at 6, 12, and 24 months. The evaluation consisted of measuring the SSD in anterior laxity and patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Lysholm scores). Regression analyses were performed to determine associations between these outcomes and 9 preoperative variables.

Results:

Only 2 patients could not be reached, 2 could not be evaluated because of contralateral ACL tears, and 2 had graft failure. At 2-year follow-up, the remaining 91 patients had a mean SSD in anterior laxity of 0.8 ± 1.8 mm (range, –4.2 to 5.3 mm), mean IKDC score of 87.6 ± 10.6 (range, 43.7-100.0), and mean Lysholm score of 90.8 ± 9.3 (range, 56.0-100.0). At final follow-up, compared with knees with partial ruptures, those with complete ruptures had equivalent laxity (P = .266) and Lysholm scores (P = .352) but lower IKDC scores (P = .009). Multivariable regression revealed that the IKDC score decreased with increased preoperative laxity (β = –1.35 [95% CI, –2.48 to –0.23]; P = .019).

Conclusion:

The novel adjustable-length CSF device produced satisfactory anterior laxity and clinical outcomes, with a failure rate of 2.1%, which compare favorably with those reported for nonadjustable CSF devices.

Passive Knee Stability After Anterior Cruciate Ligament Reconstruction Using the Endobutton or ToggleLoc With ZipLoop as a Femoral Fixation Device: A Comparison of 1654 Patients From the Danish Knee Ligament Reconstruction Registry

Background

Biomechanical studies show varying results regarding the elongation of adjustable fixation devices. This has led to growing concern over the stability of the ToggleLoc with ZipLoop used in anterior cruciate ligament (ACL) reconstruction (ACLR) in vivo.

Purpose/Hypothesis

The purpose of this study was to compare passive knee stability 1 year after ACLR in patients in whom the Endobutton or ToggleLoc with ZipLoop was used for femoral graft fixation. The hypothesis was that the ToggleLoc with ZipLoop would be inferior in knee stability to the Endobutton 1 year after primary ACLR.

Study Design

Cohort study; Level of evidence, 2.

Methods

Data from 3175 patients (Endobutton: n = 2807; ToggleLoc with ZipLoop: n = 368) were included from the Danish Knee Ligament Reconstruction Registry (DKRR) between June 2010 and September 2013. Data were retrieved from standardized ACL forms filled out by the operating surgeon preoperatively, during surgery, and at a clinical examination 1 year after surgery. Passive knee stability was evaluated using 1 of 2 arthrometers (Rolimeter or KT-1000 arthrometer) and the pivot-shift test. Using the same database, the number of reoperations performed up to 4 years after primary surgery was examined.

Results

Full data were available for 1654 patients (Endobutton: n = 1538; ToggleLoc with ZipLoop: n = 116). ACLR with both devices resulted in increased passive knee stability (P < .001). Patients who received the ToggleLoc with ZipLoop were found to have a better preoperative (P = .005 ) and postoperative (P < .001) pivot-shift test result. No statistically significant difference regarding the number of reoperations (P = .086) or the time to reoperation (P = .295) was found.

Conclusion

Patients who underwent fixation with the ToggleLoc with ZipLoop had improved passive knee stability 1 year after surgery, measured by anterior tibial translation and pivot-shift test results, similar to patients who underwent fixation with the Endobutton. No difference was seen in knee stability or reoperation rates between the 2 devices.

Magnetic Resonance Imaging and Clinical Results of Outside-in Anterior Cruciate Ligament Reconstruction: A Comparison of Fixed- and Adjustable-Length Loop Cortical Fixation

Background

Cortical suspensory femoral fixation is commonly performed for graft fixation to the femur in anterior cruciate ligament (ACL) reconstruction using hamstring tendons. The purpose of this study was to compare graft healing in the femoral tunnel, implant-related failure, and clinical results between fixed- and adjustable-length loop devices in outside-in ACL reconstruction.

Methods

A total of 109 patients who underwent ACL reconstruction using the outside-in technique from December 2010 to July 2014 were included. For femoral graft fixation, a fixed-length loop device was used in 48 patients (fixed-loop group) and an adjustable-length loop device was used in 61 patients (adjustable-loop group). For evaluation of graft healing in the femoral tunnel, magnetic resonance imaging was performed at postoperative 6 months and the signal-to-noise ratios (SNRs) of the tendon graft and tendon-bone interface in the femoral bone tunnel were evaluated. The presence of synovial fluid was evaluated to determine loop lengthening at the femoral tunnel exit. Clinical results assessed using International Knee Documentation Committee score, Tegner-Lysholm Knee Scoring scale, and knee instability tests were compared between groups.

Results

The SNRs of the tendon graft and tendon-bone interface were not statistically different between groups. The presence of synovial fluid at the femoral exit showed no statistical difference between groups. Clinical results were not significantly different between groups.

Conclusions

The adjustable-length loop device provided comparable graft healing, implant-related failure, and clinical results with the fixed-length loop device, allowing adaptation of the graft to the different tunnel lengths. Therefore, it could be effectively used with an adjustment according to the femoral tunnel length.

The Influence of Graft Fixation Methods on Revision Rates After Primary Anterior Cruciate Ligament Reconstruction

BACKGROUND

The method of graft fixation in primary anterior cruciate ligament (ACL) reconstruction is important for initial stability of the graft. Poor graft fixation can result in failure of the reconstruction. The effect of ACL graft fixation principles and fixation implant combinations on the risk of revision after ACL reconstruction is not well understood.

PURPOSE

The study aimed to compare the risk of revision among 4 categories of femoral fixation divided by their principle of function using a hamstring tendon (HT) graft only. Furthermore, this study aimed to compare the risk of revision among the most frequently used combinations (tibia and femur) of graft fixation implants in a national patient cohort.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors divided the femoral fixation constructs into 4 categories by their principle of function: cortical suspensory fixation, adjustable cortical suspensory fixation, intratunnel transfixation, and interference screw (aperture) fixation. Data on revision rates and graft fixation methods were extracted from the Danish ACL Reconstruction Registry. The study included patients who underwent primary ACL reconstruction with either an HT or patellar tendon (PT) graft and were followed up at 2 to 10 years. Revision rates at 2-year and full follow-up were extracted for the category of graft fixation in the femur as well as for the most common implant combinations (those involving >175 patients). Patients with infrequently used fixation devices were excluded from this analysis. The HT group included 14 frequently used combinations (n > 175), and there were 2 such combinations in the PT group. A total of 13,200 ACL reconstructions were included in the study. For ACL reconstruction with an HT graft, there were 4680 with cortical suspensory fixation, 577 with adjustable cortical suspensory fixation, 5921 with intratunnel transfixation, and 617 with interference screw fixation. There were 1405 ACL reconstructions with a PT graft.

RESULTS

When only comparing primary ACL reconstructions using an HT graft, cortical suspensory fixation exhibited a significantly higher risk of revision at 2-year follow-up than the other categories of femoral fixation (hazard ratio [HR], 1.24 [95% CI, 1.07-1.44]; P < .05). Intratunnel transfixation exhibited a significantly lower risk of revision (HR, 0.83 [95% CI, 0.73-0.94]; P < .05). Comparing the most frequently used femoral/tibial fixation implant combinations with the mean risk of revision, Endobutton/Intrafix and Endobutton/Biosure PEEK for HT grafts exhibited an increased risk of revision, with an relative risk (RR) of 1.36 (95% CI, 1.03-1.81; P < .05) and 1.55 (95% CI, 1.15-2.09; P < .05), respectively. The Atlantech metal screw/metal screw and Softsilk/Softsilk combinations (both for PT grafts) exhibited a significantly decreased risk of revision, with an RR of 0.41 (95% CI, 0.18-0.91; P < .05) and 0.36 (95% CI, 0.15-0.87; P < .05), respectively.

CONCLUSION

When comparing ACL graft fixation methods in the 4 categories using an HT graft, cortical suspensory fixation was found to have a significantly increased risk of revision, while intratunnel transfixation exhibited a lower risk of revision. Both Endobutton/Intrafix and Endobutton/Biosure PEEK implant combinations exhibited a significantly higher risk of revision. For PT grafts, Atlantech metal screw/metal screw and Softsilk/Softsilk exhibited a significantly lower risk of revision.

Intraoperative Workflow for All-Inside Anterior Cruciate Ligament Reconstruction: An In Vitro Biomechanical Evaluation of Preconditioning and Knot Tying

PURPOSE

To evaluate and compare the effect of preconditioning according to intraoperative workflow on the elongation behavior of single-side and fully knotted all-inside anterior cruciate ligament (ACL) reconstruction configurations in a biomechanical in vitro study.

METHODS

Four full construct all-inside ACL reconstruction groups (n = 8 per group) were tested using porcine tibias and bovine tendons. Groups included both an all-inside configuration with one- (group 1) and both-side knotted adjustable loop-length devices (group 2), without and with performing intraoperative preconditioning (group 1-intraoperative preconditioned [IPC], group 2-IPC). Adjustable loop-length devices for control groups were knotted according to test configurations. Intraoperative preconditioning specimens were further precycled for 10 times at 0.5 Hz and manually retensioned before knotting. All groups underwent dynamic cycling in position and force control mode each for 1,000 cycles at 0.75 Hz according to in vitro loading parameters replicating the in vivo ACL environment. Finally, a load-to-failure test at 50 mm/min was performed.

RESULTS

Intraoperative preconditioning increases initial graft tension for single- (242 ± 22 N vs 174 ± 13 N; P < .0001) and both-side knotted configurations (225 ± 15 N vs 159 ± 10 N; P < .0001) compared with controls and allows maintained graft tension at higher levels until reaching the end of position-controlled cyclic loading. Furthermore, dynamic elongation is reduced for one- (1.93 ± 0.28 vs 0.76 ± 0.12; P < .0001) and both-side knotted (1.84 ± 0.20 vs 0.96 ± 0.32; P < .0001) configurations by 61% and 47%, respectively. No intergroup (group 1 vs group 2 and group 1-IPC vs group 2-IPC) statistically significant differences could be found between one- and both-side knotted configurations.

CONCLUSIONS

All-inside ACL reconstruction with preconditioning according to intraoperative workflow leads to a statistically significant improved mechanical behavior and may allow for optimizing initial graft tension and elongation for all-inside ACL reconstruction to reduce knee laxity. A single-side knotted configuration achieves similar stabilization strength to fully knotted constructs.

CLINICAL RELEVANCE

Graft insertion until tunnel docking increases the intratunnel graft portion that may optimize graft incorporation. Eliminating a suture knot stack may improve intraoperative workflow and reduce postoperative knot irritation.

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.

Posterior Cruciate Ligament Reconstruction with Retrograde Femoral Technique, Posterior Trans-septal Portal and Full Tibial Tunnel

Suspensory femoral graft fixation has been a popular and reliable method in anterior cruciate ligament (ACL) reconstruction. Some authors have introduced suspensory femoral fixation in posterior cruciate ligament (PCL) reconstruction using inside-out (IO) technique. The use of IO technique for femoral tunnel preparation could significantly sharpen the critical corner, which might result in graft failure. A retrograde drilling pin that recently has been popular in ACL reconstruction allows "no incision" in the outside-in (OI) technique for the creation of a femoral socket. Here we describe the suspensory femoral fixation using a retro-socket technique in single-bundle PCL reconstruction. By using this technique, it is possible to create a retrograde femoral socket for suspensory femoral fixation in an OI manner in a desirable direction and reduce angulation of the graft in the entry area of the femoral tunnel.

Biomechanical Comparison of Fixed-Loop and Adjustable-Loop Cortical Suspensory Devices for Metaphyseal Femoral-Sided Soft Tissue Graft Fixation in Anatomic Anterior Cruciate Ligament Reconstruction Using a Porcine Model

PURPOSE

To compare the displacement, stiffness, and ultimate failure load of a fixed-loop cortical suspensory device with 2 adjustable-loop devices when positioned on metaphyseal bone.

METHODS

Thirty devices (10 of each device) were positioned on the metaphyseal cortex of 30 porcine femora simulating anatomic anterior cruciate ligament femoral tunnel placement. Bovine tendons were used for soft tissue grafts, and the constructs were then cycled 1,000 times and pulled to failure, measuring displacement, stiffness, and failure load.

RESULTS

Initial displacement, cyclic displacement, and total displacement were 2.98 mm, 2.09 mm, and 5.08 mm for the Endobutton CL (ECL), 2.82 mm, 2.27 mm, and 5.09 mm for the Tightrope (TRT), and 4.25 mm, 3.19 mm, and 7.44 mm for the adjustable-loop ToggleLoc Inline with Ziploop (TLZ), respectively. There was no difference between the ECL and the TRT on any measured outcome. Differences between the TLZ and ECL were statistically significant (initial displacement P = .024, cyclic displacement P < .001, and total displacement P < .001), as were those between the TLZ and TRT (initial displacement P = .010, cyclic displacement P = .001, and total displacement P < .001). Failure loads were 804 N, 801 N, and 682 N for the TRT, ECL, and TLZ, respectively, with no statistically significant difference.

CONCLUSIONS

When positioned on the metaphyseal cortex, there was no difference in the biomechanical performance of the fixed-loop ECL and adjustable-loop TRT, and no lengthening of the TRTs was observed during cycling. However, the TLZ showed statistically significantly lower stiffness and more displacement during cycling with lengthening of the adjustable loop, the clinical significance of which is unknown.

CLINICAL RELEVANCE

When used for femoral-sided soft tissue graft fixation in an anatomically placed femoral tunnel, the adjustable-loop TRT was biomechanically equivalent to the fixed-loop ECL. However, the adjustable-loop TLZ showed displacement during biomechanical testing that could potentially contribute to clinical failure after anterior cruciate ligament reconstruction. However, the clinical significance was not directly tested.

Arthroscopic Control for Safe and Secure Seating of Suspensory Devices for Femoral Fixation in Anterior Cruciate Ligament Reconstruction Using Three Different Techniques

Purpose

The purpose of this study was to evaluate the efficacy of our technique that allows direct visualization of seating of suspensory devices in anterior cruciate ligament (ACL) reconstruction.

Materials and Methods

Three different suspensory devices (TightRope RT, RetroButton, and EndoButton) were used in ACL reconstruction using 3 different techniques (outside-in, anteromedial [AM] portal, and transtibial techniques). Positioning of a guiding material and seating pattern of the suspensory devices were evaluated according to the surgical technique and suspensory device used.

Results

On the transtibial technique, 21 of total 26 cases (81%) of single bundle reconstructions and 22 of total 22 cases (100%) of double bundle reconstructions required superolateral capsulotomy where buttons were found in 21 of total 21 cases (100%) and 17 of 22 cases (77%), respectively. On the AM portal technique, all patients required capsulotomy and the button was found in only 18 of total 32 cases (56%) even after capsulotomy. On the outside-in technique, all patients required capsulotomy and the button was found in 86 of total 86 cases (100%).

Conclusions

Our technique for direct visualization of seating of the suspensory devices was more effective in outside-in and single bundle transtibial ACL reconstruction. However, it was less effective in double bundle transtibial and AM portal ACL reconstructions.

Clinical and Radiological Outcomes After Hamstring Anterior Cruciate Ligament Reconstructions: Comparison Between Fixed-Loop and Adjustable-Loop Cortical Suspension Devices

BACKGROUND

Few studies have compared clinical and radiological outcomes after hamstring anterior cruciate ligament (ACL) reconstruction with fixed-loop and adjustable-loop cortical suspension devices. Purpose/Hypothesis: The purpose of this retrospective study was to compare clinical outcomes and tunnel widening after hamstring ACL reconstructions with fixed- and adjustable-loop cortical suspension devices. The hypothesis was that compared with femoral graft fixation with the fixed-loop device, fixation with the adjustable-loop device would show similar clinical outcomes and would result in less tunnel widening after hamstring ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 117 consecutive patients underwent hamstring ACL reconstruction at a single institution. The fixed-loop cortical suspension device was used in 67 patients, and the adjustable-loop cortical suspension device was used in 50 patients. All patients were observed for a minimum of 2 years. Postoperative knee laxity was evaluated with the Lachman test, pivot-shift test, and KT-1000 arthrometer. Functional evaluations were performed by use of the Lysholm score and the Tegner activity scale. On anteroposterior (AP) and lateral radiographs, the measured diameters of the femoral tunnel at 1 year after surgery were compared with the diameter of the reamer used at surgery. The measured diameters of the tibial tunnel at 1 year after surgery were compared with those taken immediately after surgery.

RESULTS

The mean KT-1000 arthrometer laxity measurement was 1.5 ± 1.8 mm in the fixed-loop group and 1.2 ± 2.3 mm in the adjustable-loop group ( P = .530). Results of postoperative knee laxity evaluations and functional outcomes from both groups showed no statistically significant differences. However, the fixed-loop group showed significantly better stability in the pivot-shift test than did the adjustable-loop group ( P = .018). On AP radiographs, the mean diameter of the femoral and tibial tunnels increased by 42.2% ± 15.9% and 37.0% ± 17.8%, respectively, in the fixed-loop group and by 43.0% ± 15.4% and 36.8% ± 18.2% in the adjustable-loop group. On lateral radiographs, the mean diameter of the femoral and tibial tunnels increased by 38.1% ± 14.8% and 39.9% ± 13.8%, respectively, in the fixed-loop group and by 35.8% ± 12.2% and 38.1% ± 21.0% in the adjustable-loop group. No significant differences were found between the 2 groups in postoperative femoral and tibial tunnel widening on AP radiographs ( P = .801 and .951, respectively) or lateral radiographs ( P = .422 and .621, respectively).

CONCLUSION

Compared with femoral fixation by use of the fixed-loop device, femoral fixation by use of the adjustable-loop device showed similar clinical outcomes but did not reduce tunnel widening after hamstring ACL reconstructions.

Outcomes of ACL Reconstruction With Fixed Versus Variable Loop Button Fixation

Suspensory femoral fixation of anterior cruciate ligament (ACL) grafts with fixed loop button and variable loop button devices has gained popularity for ACL reconstruction. This study examined these 2 methods of fixation to determine their effect on graft laxity and patient-reported outcome scores. A database search was performed to identify patients who had undergone ACL reconstruction with either a fixed loop or a variable loop button technique performed by the primary surgeon. Lysholm, Tegner, and 12-Item Short Form Health Survey scores were obtained, and KT-1000 knee ligament arthrometer (MEDmetric, San Diego, California) mechanical knee testing was performed. Results were compared with the uninjured knee. Of the 112 patients who were identified, 91 met the study criteria. Of these patients, 57 completed KT-1000 knee testing, 33 in the variable group and 24 in the fixed group. The average KT-1000 value for the variable group was 0.38 mm, and the average for the closed group was 0.92 mm (P=.19; 95% confidence interval, -0.28 to 1.35). Among the 19 patients in the variable group and the 13 in the closed group who completed the subjective outcomes questionnaires, no statistically significant difference was found. Clinically lax knees (KT-1000>3 mm) were found in 6.1% and 12.5% of patients in the variable group and the fixed group, respectively (P=.2). The variable group had a rerupture rate of 4.7%, whereas the fixed group had a rerupture rate of 8.7% (P=.21). The study found no statistical difference in ACL graft laxity or postoperative functional outcomes between grafts fixed with the variable loop or fixed loop button technique. [Orthopedics. 2017; 40(2):e275-e280.].

Lack of stability at more than 12 months of follow-up after anterior cruciate ligament reconstruction using all-inside quadruple-stranded semitendinosus graft with adjustable cortical button fixation in both femoral and tibial sides

INTRODUCTION

The use of the semitendinosus tendon alone for anterior cruciate ligament reconstruction keeps the gracilis muscle intact and decreases anterior pain in comparison with the use of the patellar tendon. Recently, Lubowitz described a new all-inside technique with an ST4 tendon fixed with a cortical button in both femoral and tibial sides. We hypothesized that this type of graft with cortical button fixation provides well-controlled residual anterior tibial translation (<3mm). The aim of this study was to assess the results obtained with this technique in terms of laxity and IKDC score at more than 1 year of follow-up.

MATERIAL AND METHODS

We performed a prospective single-center study to evaluate the results with this procedure with at least 1 year of follow-up. The primary endpoint was the objective IKDC score and side-to-side anterior tibial translation difference. The secondary endpoint was the subjective assessment using the subjective IKDC and Lysholm scores. Tunnel positioning was assessed using the Aglietti criteria.

RESULTS

Thirty-five patients were included and reviewed with a mean follow-up of 19.7 months. Sixty-three percent of the patients were male and the mean age at the procedure was 28 years. The IKDC score was A or B in 43% of the patients and C or D in 57%; 54% of the patients had a residual side-to-side anterior tibial translation difference less than 3mm and 29% presented significant pivot shift (grade C or D). Five patients underwent revision surgery, including one for rupture of the ACL reconstruction. The meniscal status did not influence postoperative laxity and the IKDC grade.

DISCUSSION

Our hypothesis was not verified and the postoperative stability of the knee was insufficient. Postoperative side-to-side anterior tibial translation difference remained greater than 3mm for 16 patients and the analysis seems to indicate that the distal cortical fixation of the graft with an adjusted loop is insufficient.

LEVEL OF EVIDENCE

Prospective study - Level IV.

Posterior Wall Blowout in Anterior Cruciate Ligament Reconstruction: A Review of Anatomic and Surgical Considerations

Violation of the posterior femoral cortex, commonly referred to as posterior wall blowout, can be a devastating intraoperative complication in anterior cruciate ligament (ACL) reconstruction and lead to loss of graft fixation or early graft failure. If cortical blowout occurs despite careful planning and adherence to proper surgical technique, a thorough knowledge of the anatomy and alternative fixation techniques is imperative to ensure optimal patient outcomes. This article highlights anatomic considerations for femoral tunnel placement in ACL reconstruction and techniques for avoidance and salvage of a posterior wall blowout.

Posterior Wall Blowout During Anterior Cruciate Ligament Reconstruction: Suspensory Cortical Fixation With a Screw and Washer Post

Posterior wall blowout can be a devastating intraoperative complication in anterior cruciate ligament reconstruction. This loss of osseous containment can cause difficulty with graft fixation and can potentially lead to early graft failure if unrecognized and left untreated. If cortical blowout occurs despite careful planning and proper surgical technique, a thorough knowledge of the local anatomy and surgical salvage options is paramount to ensure positive patient outcomes. This article highlights our preferred salvage technique using suspensory cortical fixation with a screw and washer construct.

Does immediate elbow mobilization after distal biceps tendon repair carry the risk of wound breakdown, failure of repair, or patient dissatisfaction?

BACKGROUND

Rehabilitation protocols after distal biceps repair are highly variable, with many surgeons favoring at least 2 weeks of immobilization. Is this conservative approach necessary to protect the repair?

METHODS

This was a consecutive series of 22 distal biceps tendon repairs in which a cortical button system was used. Patients were encouraged to mobilize their elbow actively from the day of surgery. Physiotherapy commenced at 3 weeks, with strengthening exercises when full range of movement (ROM) was achieved. The primary outcome measured was the clinical integrity of the repaired tendon. Secondary outcomes comprised wound or nerve complication, elbow ROM, and patient-reported outcome measures (the 11-item version of the Disabilities of Arm, Shoulder and Hand, Mayo Elbow Performance Index, and Oxford Elbow Score).

RESULTS

All patients were male, and the dominant arm was repaired in 60%. Mean age was 40.6 years (range, 27-62 years), and mean time to surgery was 17 days (range, 5-99 days). Mean follow-up was 16.6 months (range, 3.8-29 months). All tendons were clinically intact at time of review. No wound breakdown occurred. Mean extension was -6° (range, -10° to 10°), and flexion was 144° (range, 135°-150°). All patients achieved full pronosupination. ROM was equivalent to the uninjured arm (P = .7). The mean 11-item version of the Disabilities of Arm, Shoulder and Hand score was 2.7 (range, 0-15.9), the Mayo Elbow Performance Index was 97.8 (range, 70-100), and the Oxford Elbow Score was 46.9 (range, 43-48) at the latest follow-up. One-third of patients experienced a transient sensory neurapraxia.

CONCLUSION

Immediate mobilization after biceps tendon repair with a cortical button is possible, and in this series was not associated with failure of the repair, wound breakdown, or patient dissatisfaction. However, this series emphasizes the high incidence of nerve complication that can be associated with the single transverse incision technique.

Lateral Knee Pain after Outside-in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the TightRope RT

The anterior cruciate ligament (ACL) TightRope RT (TR) was recently introduced as a novel cortical suspension device for ACL reconstruction. It has an adjustable graft loop that gives the surgeon some advantages during ACL reconstruction. We report three patients who required removal of the TR after an outside-in anatomical ACL reconstruction because of lateral knee pain. We assumed that the knee pain was associated with friction between the TR button of the posterolateral bundle and iliotibial band (ITB). Placing the TR button close to the lateral epicondyle and tissue interposition between the TR button and lateral femoral cortex may be potential risk factors for ITB irritation. Therefore, we recommend not placing the TR button close to the top of the lateral epicondyle and reducing the tissue interposition between the TR button and lateral femoral cortex as much as possible.

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

PURPOSE

To evaluate and compare two adjustable femoral cortical suspensory fixation devices used for anterior cruciate ligament reconstruction through a novel, direct computed tomography (CT) analysis metric and biomechanical laxity testing in a matched cadaveric human knee study.

METHODS

Anterior cruciate ligament reconstructions with bovine tendon grafts were performed using two adjustable femoral cortical suspensory fixation devices (RigidLoop Adjustable [DePuy Synthes Mitek, Raynham, MA] and TightRope [Arthrex, Naples, FL]) in 12 knees (6 matched pairs). A mechanical testing series was used to determine each knee's laxity in the intact condition. After reconstruction, each specimen was again tested for laxity and also imaged with CT. The laxity testing and CT imaging were then repeated after 1,000 cycles of anteroposterior loading on each knee to compare changes in laxity for the two fixation devices and to visualize changes in button-to-graft distance migration through a three-dimensional CT imaging method.

RESULTS

No significant differences were found between the two fixation groups' laxity measures after reconstruction (all P values ≥ .620) or after cycling (all P values ≥ .211) at any flexion angle. In addition, no significant differences were found between the two groups regarding button-to-graft distance migration (P = .773; mean, 0.61 ± 0.6 mm [95% confidence interval, -0.1 to 1.3 mm] in RigidLoop Adjustable group and 0.53 ± 0.6 mm [95% confidence interval, -0.1 to 1.2 mm] in TightRope group).

CONCLUSIONS

There were no significant differences between the two femoral cortical suspensory adjustable-loop devices regarding laxity outcomes or loop displacement as measured by button-to-graft distance migration.

CLINICAL RELEVANCE

Use of either of the adjustable-loop cortical suspensory devices in our analysis would appear to produce similar, acceptable laxity outcomes and minimal effects in terms of device-related loop displacement.

Suspensory Anterior Tibial Fixation in the Anatomic Transtibial Posterior Cruciate Ligament Reconstruction

The transtibial technique is the most relevant among many surgical techniques for posterior cruciate ligament reconstruction, and many types of fixation devices are used for tibial fixation according to the technique and the length of the graft. However, bone density in the fixation areas should be taken into consideration when choosing the fixation device to achieve rigid and stable fixation. However, density is not a substantial issue for anteromedial cortical fixation using a cortical suspension device. We describe tibial fixation with a TightRope RT (Arthrex, Naples, FL), which is a cortical suspension device, in anatomic transtibial posterior cruciate ligament reconstruction.

A guided surgical approach and novel fixation method for arthroscopic Latarjet

BACKGROUND

Most of the complications of the Latarjet procedure are related to the bone block positioning and use of screws. The purpose of this study was to evaluate if an arthroscopic Latarjet guiding system improves accuracy of bone block positioning and if suture button fixation could be an alternative to screw fixation in allowing bone block healing and avoiding complications.

MATERIALS AND METHODS

Seventy-six patients (mean age, 27 years) underwent an arthroscopic Latarjet procedure with a guided surgical approach and suture button fixation. Bone graft union and positioning accuracy were assessed by postoperative computed tomography imaging. Clinical examinations were performed at each visit.

RESULTS

At a mean of 14 months (range, 6-24 months) postoperatively, 75 of 76 patients had a stable shoulder. No neurologic complications were observed; no patients have required further surgery. The coracoid graft was positioned strictly tangential to the glenoid surface in 96% of the cases and below the equator in 93%. The coracoid graft healed in 69 patients (91%).

CONCLUSIONS

A guided surgical approach optimizes graft positioning accuracy. Suture button fixation can be an alternative to screw fixation, obtaining an excellent rate of bone union. Neurologic and hardware complications, classically reported with screw fixation, have not been observed with this guided technique and novel fixation method.

Femoral Footprint Reconstruction With a Direct Viewing of the Posterior Insertion Using a Trans-Septal Portal in the Outside-In Anterior Cruciate Ligament Reconstruction

We established a technique for femoral tunnel preparation through direct vision of the femoral footprint with maximum preservation to the native anterior cruciate ligament (ACL) remnant using a posterior trans-septal portal. Anterior arthroscopy is difficult for the proper tunnel placement without sacrificing the ACL remnant. Posterior arthroscopy could be helpful for viewing the posterior insertion of the ACL remnant that provides excellent femoral footprint exposure without sacrificing the native ACL remnant. Therefore, a posterolateral portal technique using a 70° arthroscope through a posterolateral portal is introduced. However, using the 70° arthroscope, an oblique view is displayed and distorted view could be seen. Therefore, to achieve the goal of posterior arthroscopy and avoid obstacles of the posterolateral view with the 70° arthroscope, we introduce this technique that uses the posterior trans-septal portal with a 30° arthroscope that provides an excellent viewing to the femoral footprint through a hole of the posterior septum.

Does adjustable-loop femoral cortical suspension loosen after anterior cruciate ligament reconstruction? A retrospective comparative study

BACKGROUND

Recent biomechanical research has suggested that adjustable-loop graft suspension constructs in anterior cruciate ligament (ACL) reconstruction may loosen after deployment. Our objective was to compare short-term knee stability and graft failure rate between adjustable-loop and fixed-loop femoral cortical suspension in patients undergoing primary ACL reconstruction.

METHODS

A consecutive series of 188 patients who underwent primary ACL reconstruction using hamstrings autograft by a single surgeon were divided into two groups; 73 received adjustable-loop (TightRope RT (Arthrex Inc., Naples, FL)) and 115 received fixed-loop (RetroButton (Arthrex Inc., Naples, FL)) femoral cortical suspension. The two groups were compared at six months, one year, and two years postoperatively using KT-1000 arthrometer testing and graft failure rate (revision surgery, grade 2+ Lachman test, any pivot shift, >5mm side-to-side KT-1000 difference).

RESULTS

There was no significant difference between the two groups in maximum side-to-side difference in KT-1000 testing at six months (mean 1.51mm (adjustable-loop group) vs. 1.79mm (fixed-loop group), p=0.23), one year (mean 1.44mm vs. 1.64mm, p=0.48), or two years (mean 1.14mm vs. 1.07mm, p=0.90) postoperatively. There was no significant difference between the two groups in rate of graft failure (10% vs. 11%, p=0.71) or timing of graft failure in affected patients (mean 11.4months vs. 13.8months, p=0.51).

CONCLUSIONS

We found no significant difference in postoperative knee stability or graft failure rate between adjustable-loop and fixed-loop femoral cortical suspension in patients undergoing primary ACL reconstruction. Our results suggest that adjustable-loop suspension does not clinically loosen after ACL reconstruction.

LEVEL OF EVIDENCE

III (retrospective cohort study).

Registry data highlight increased revision rates for endobutton/biosure HA in ACL reconstruction with hamstring tendon autograft: a nationwide cohort study from the Norwegian Knee Ligament Registry, 2004-2013

BACKGROUND

Compared with a patellar tendon autograft (PT), a hamstring tendon autograft (HT) has an increased risk of revision after anterior cruciate ligament reconstruction (ACLR). There are no studies analyzing whether this can be explained by inferior fixation devices used in HT reconstruction or whether the revision risk of ACLR with an HT or a PT is influenced by the graft fixation.

PURPOSE

To compare the risk of revision and the revision rates between the most commonly used combinations of fixation for HTs with PTs.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This study included all patients registered in the Norwegian Knee Ligament Registry from 2004 through 2013 who underwent primary PT or HT ACLR with no concomitant ligament injury and known graft fixation. The 2-year revision rates were calculated using the Kaplan-Meier analysis. Hazard ratios (HRs) for revision at 2 years were calculated using multivariate Cox regression models.

RESULTS

A total of 14,034 patients with primary ACLR were identified: 3806 patients with PTs and 10,228 patients with HTs; the mean follow-up time was 4.5 years. In the HT group, 5 different combinations of fixation in the femur/tibia were used in more than 500 patients: Endobutton/RCI screw (n = 2339), EZLoc/WasherLoc (n = 1352), Endobutton/Biosure HA (n = 1209), Endobutton/Intrafix (n = 687), and TransFix II/metal interference screw (MIS) (n = 620). The crude 2-year revision rate for patients with PTs was 0.7% (95% CI, 0.4%-1.0%), and for patients with HTs, it ranged between the groups from 1.5% (95% CI, 0.5%-2.4%) for TransFix II/MIS to 5.5% (95% CI, 4.0%-7.0%) for Endobutton/Biosure HA. When adjusted for detected confounding factors and compared with patients with PTs, the HR for revision at 2 years was increased for all HT combinations used in more than 500 patients, and the combinations Endobutton/Biosure HA and Endobutton/Intrafix had the highest HRs of 7.3 (95% CI, 4.4-12.1) and 5.5 (95% CI, 3.1-9.9), respectively.

CONCLUSION

The choice of fixation after ACLR with an HT has a significant effect on a patient's risk of revision. In this study population, none of the examined combinations of HT fixation had a revision rate as low as that for a PT.