Complications following hamstring anterior cruciate ligament reconstruction with femoral cross-pin fixation

Fixed- Versus Adjustable-Loop Femoral Cortical Suspension Devices for Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Biomechanical Studies

Background:

Fixed- and adjustable-loop femoral cortical suspension devices are commonly used for femoral graft fixation during anterior cruciate ligament reconstruction (ACLR).

Purpose:

To compare the biomechanical results of fixed- versus adjustable-loop femoral cortical suspension devices in studies simulating ACLR with an isolated device and/or specimen setup using porcine femora and bovine flexor tendons.

Study Design:

Systematic review.

Methods:

Two independent reviewers searched PubMed, Embase, and the Cochrane Library databases to find studies comparing the biomechanical strength of fixed- and adjustable-loop cortical suspension devices for ACLR with isolated device and/or specimen setups using porcine femora and bovine flexor tendons. Studies that compared both devices with similar biomechanical methods were included. Data extracted included displacement during cyclic loading, ultimate load to failure, and mode of failure of the different cortical suspension devices for ACLR.

Results:

Six studies were identified that met the inclusion criteria, including a total of 76 fixed-loop devices and 120 adjustable-loop devices. Load to failure was significantly different (P < .0001), with the strongest fixation device being the ToggleLoc with ZipLoop adjustable-loop device (1443.9 ± 512.3 N), compared with the Endobutton CL fixed-loop device (1312.9 ± 258.1 N; P = .04) and the TightRope RT adjustable-loop device (863.8 ± 64.7 N; P = .01). Cyclic displacement was significantly different, with Endobutton CL (3.7 ± 3.9 mm) showing the least displacement, followed by ToggleLoc with ZipLoop (4.9 ± 2.3 mm) and TightRope RT (7.7 ± 11.1 mm) (P < .0001). Mode of failure was statistically different between the 3 groups (P = .01), with suture failure accounting for 83.8% of TightRope RT devices, 69.4% of ToggleLoc with ZipLoop devices, and 60.3% of Endobutton CL devices.

Conclusion:

Current biomechanical data suggest that the ToggleLoc with ZipLoop device is the strongest fixation device at “time zero” in terms of ultimate load to mechanical failure. However, the Endobutton CL device demonstrated the least cyclic displacement, which may be a more clinically applicable measure of device superiority.

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.

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).

Femoral suspension devices for anterior cruciate ligament reconstruction: do adjustable loops lengthen?

BACKGROUND

Cortical suspension devices are commonly used for femoral graft fixation during anterior cruciate ligament (ACL) reconstructive surgery. Adjustable-length fixation devices provide technical advantages over fixed-length loops but may be more susceptible to lengthening during cyclic loading.

HYPOTHESIS

Both fixed-length and adjustable-length femoral cortical suspension devices would withstand ultimate loads greater than those normally experienced by the native ACL and would prevent clinically significant lengthening during prolonged cyclic loading.

STUDY DESIGN

Controlled laboratory study.

METHODS

Mechanical testing was performed on 3 ACL graft cortical suspensory devices by use of an extended cyclic loading (4500 cycles at 10-250 N) and pull-to-failure protocol. Two adjustable-length devices were additionally tested with the free suture ends tied.

RESULTS

Total displacement after 4500 cycles of tensioning at variable loads (expressed as mean ± SD) was 42.45 mm (±7.01 mm) for the Arthrex TightRope RT, 5.76 mm (±0.35 mm) for the Biomet ToggleLoc, and 1.34 mm (±0.03 mm) for the Smith & Nephew EndoButton CL Ultra (P < .001). The Arthrex TightRope reached clinical failure of 3 mm lengthening after fewer cycles (1349 ± 316) than the Biomet ToggleLoc (2576 ± 73) (P < .001). The Smith & Nephew EndoButton did not reach clinical failure during cyclic testing. With the free suture ends tied, after 4500 cycles, the Arthrex TightRope had a significant decrease in lengthening to 13.36 ± 1.86 mm (P < .037) There was also a significant difference in ultimate load between the TightRope (809.11 ± 52.94 N) and the other 2 constructs (P < .001).

CONCLUSION

The ultimate load of all graft-fixation devices exceeded the forces likely to be experienced in a patient's knee during the early postoperative rehabilitation period. However, the adjustable-length fixation devices experienced a clinically significant increase in loop lengthening during cyclic testing. This lengthening is partially caused by suture slippage into the adjustable-length loop.

CLINICAL RELEVANCE

Adjustable-length ACL graft cortical suspension devices lengthen under cyclic loads because free suture ends are pulled into the adjustable loop. This may allow for graft-fixation device lengthening during the acute postoperative period.

Complications using bioabsorbable cross-pin femoral fixation: a case report and review of the literature

The use of bioabsorbable cross-pin transcondylar fixation has remained a viable option for femoral fixation in anterior cruciate ligament reconstruction. Although numerous biomechanical studies have demonstrated high fixation strength and minimal slippage with use of this method of fixation, there have been increasing reports of a variety of clinical complications associated with these implants. We reviewed the literature for all complications associated with the Bio-TransFix implant and present a case report of a patient status after ACL reconstruction using Bio-TransFix cross-pin femoral fixation with iliotibial band friction syndrome from a broken cross-pin four month post-operatively.