Pullout strength of a novel hybrid fixation technique (Tape Locking Screw™) in soft-tissue ACL reconstruction: A biomechanical study in human and porcine bone

Effect of Different Screw Materials on ACL Reconstruction With the Tape Locking Screw Technique: A Retrospective Study From the FAST Cohort

Background

Screws for graft fixation are available in 3 different materials for anterior cruciate ligament reconstruction (ACLR) with the Tape Locking Screw (TLS) technique: titanium, poly-l-lactic acid bioabsorbable, and polyetheretherketone (PEEK).

Purpose

To compare the effect of the 3 different fixation materials on graft and implant survival after ACLR with the TLS technique.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were 521 patients from the French Prospective ACL Study (FAST) cohort who underwent primary surgical ACLR with the TLS technique. Patients were divided into 3 groups depending on the type of screw material used: titanium (TLS-T group), poly-l-lactic acid bioabsorbable (TLS-B group), or PEEK (TLS-P group). The primary endpoint was a retear within 2 years after ACLR. The secondary endpoints were complication rate, return to sports rate, and functional scores. Objective and subjective functional scores-including the International Knee Documentation Committee, the Knee injury and Osteoarthritis Outcome Score (KOOS), and the Lysholm score-were evaluated preoperatively and at the 2-year follow-up. Pain was assessed with the KOOS-Pain subscore recorded pre- and postoperatively every 6 months up to 2 years. Patient satisfaction was recorded at the 2-year follow-up.

Results

No significant differences between the study groups were found in retear rates (4.4%, 4.5%, and 4.3% in the TLS-T, TLS-P, and TLS-B groups 2 years after surgery) or subjective and objective outcomes. The TLS-T group had the lowest rate of intraoperative implant-related complications (0.9%) compared with the TLS-P (4.3%) and TLS-B (7.7%) groups. Young age was a significant risk factor for retear in the TLS-T (P = .03) and TLS-B (P = .0001) groups, while a high level of sports was found to be a significant risk factor in the TLS-P (P = .04) group. All functional scores improved significantly at the 2-year follow-up (P < .0001), with no significant group difference. The KOOS-Pain subscore improved continuously with no significant group difference. The rate of return to preinjury sports was between 43.4% and 58.6%. The rate of highly satisfied patients at the final follow-up was between 86.2% and 91.8%.

Conclusion

There was no difference in retear rate or objective and subjective functional scores between implant materials for TLS ACLR in this study.

Anterior cruciate ligament reconstruction with a single hamstring tendon graft and tape locking screw (TLS) fixation leads to good clinical outcome in two years of follow-up

Background

There are many fixation methods for hamstring tendon autograft available for anterior cruciate ligament (ACL) reconstruction. The intention of this study was to report clinical follow-up data of the Tape Locking Screw (TLS) reconstruction technique.

Hypothesis

Does TLS method give good long term results in patient satisfaction and in clinical knee tests.

Patients and methods

We selected 119 prospectively collected patients with a two-year follow-up who had an ACL reconstruction using TLS technique. A total of 114 cases were available for follow-up two years postoperatively. The evaluation methods were instrumented laxity measurements, clinical examination and knee scores.

Results

The Lysholm and IKDC scores improved from preoperative 76 and 50 to 95 and 90, respectively. Tegner activity level before surgery was 3 and improved to 6 at 2 years postoperatively.

Discussion

ACL reconstruction with TLS technique showed good objective outcome at the 2-year follow-up. We confirmed improvement in all evaluation method variables.

Level of evidence

Case series; level of evidence, 4.

Trial registration

ISRCTN registry, study ID ISRCTN34011837. Registered retrospectively April 29, 2020.

Anterior cruciate ligament reconstruction with short hamstring grafts: the choice of femoral fixation device matters in controlling overall lengthening

PURPOSE

The purpose was to conduct an independent biomechanical study comparing the main types of femoral fixation adapted to short hamstring grafts in anterior cruciate ligament (ACL) reconstruction surgery and to validate their performance.

METHODS

The ACLip^® Femoral, ToggleLoc™ Ziploop (TLZ), and Tape Locking Screw (TLS^®) implants were tested in tension in the following three different configurations: implant alone, implant fixed on the femur without graft, and implant fixed on the femur with graft. Grafts alone were also tested. The femurs and the 4-strand semi-tendinosus grafts were derived from porcine and human models, respectively. Each set-up was subjected to the same protocol of creep (50 N for 30 s), cycling (1000 cycles between 50 and 250 N, 1 Hz), and load to failure (50 mm/min).

RESULTS

A total of 93 tests were performed (30 ACLip^®, 30 TLZ, 20 TLS^®, and 13 ST4 alone). For the implants tested with femur and graft, the mean ± standard deviation (SD) overall elongation at 250 N after cycling was 5.2 ± 0.2 mm, 8.4 ± 2.1 mm, and 5.3 ± 0.8 mm, the mean ± SD ultimate load to failure was 736 ± 116 N, 830 ± 204 N, and 640 ± 242 N, and the mean ± SD stiffness at the 1000th cycle was 185 ± 15 N/mm, 172 ± 19 N/mm, and 178 ± 21 N/mm for ACLip^®, ToggleLoc™, and TLS^® devices, respectively. There was no significant difference between the implants except for post-cycling elongation between TLZ and the other two implants (p < 0.05).

CONCLUSION

The choice of femoral fixation device plays a decisive role in controlling the overall lengthening of an ACL reconstruction using a short hamstring graft. All implants validated the specifications in terms of ultimate load to failure, the TLS^® system had, however, a low performance limit. ToggleLoc™ with adjustable loop should no longer be used on the femur side; instead the other types of fixation should be used to improve the overall elongation control.

In Vitro Testing of 2 Adjustable-Loop Cortical Suspensory Fixation Systems Versus Interference Screw for Anterior Cruciate Ligament Reconstruction

Background:

It is not clear whether the mechanical strength of adjustable-loop suspension devices (ALDs) in anterior cruciate ligament (ACL) reconstruction is device dependent and if these constructs are different from those of an interference screw.

Purpose:

To compare the biomechanical differences of 2 types of ALDs versus an interference screw.

Study Design:

Controlled laboratory study.

Methods:

ACL reconstruction was performed on porcine femurs and bovine extensor tendons with 3 types of fixation devices: interference screw, UltraButton (UB) ALD, and TightRope (TR) ALD (n = 10 for each). In addition to specimen testing, isolated testing of the 2 ALDs was performed. The loading protocol consisted of 3 stages: preload (static 150 N load for 5 minutes), cyclic load (50-250 N at 1 Hz for 1000 cycles), and load to failure (crosshead speed 50 mm/min). Displacement at different cycles, ultimate failure load, yield load, stiffness, and failure mode were recorded.

Results:

In specimen testing, displacement of the ALDs at the 1000th cycle was similar (3.42 ± 1.34 mm for TR and 3.39 ± 0.92 mm for UB), but both were significantly lower than that of the interference screw (7.54 ± 3.18 mm) (P < .001 for both). The yield load of the UB (547 ± 173 N) was higher than that of the TR (420 ± 72 N) (P = .033) or the interference screw (386 ± 51 N; P = .013), with no significant difference between the latter 2. In isolated device testing, the ultimate failure load of the TR (862 ± 64 N) was significantly lower than that of the UB (1879 ± 126 N) (P < .001).

Conclusion:

Both ALDs showed significantly less displacement in cyclic loading at ultimate failure than the interference screw. The yield load of the UB was significantly higher than that of the other 2. The ultimate failure occurred at a significantly higher load for UB than it did for TR in isolated device testing.

Clinical Relevance:

Both UB and TR provided stronger fixation than an interference screw. Although difficult to assess, intrinsic differences in the mechanical properties of these ALDs may affect clinical outcomes.

Anterior tibial translation and patient-reported outcomes after anterior cruciate ligament reconstruction with a tape locking screw: A 5-year follow-up study

BACKGROUND

The Tape Locking Screw system (TLS) is a recognised technique used in anterior cruciate ligament reconstruction (ACLR). However, only a few previous studies have reported associated outcomes, all of which had been examined over a short-term period. The aim of this study was to assess the time-dependent changes in the objective and patient-reported outcome measures (PROM) in a group of patients with anterior cruciate ligament deficiency who have been operated on with this technique.

HYPOTHESIS

Previously reported satisfactory short-term outcomes following TLS persist for several years after the operation.

PATIENTS AND METHODS

This study was a retrospective observational study including 26 patients, who were followed after unilateral ACLR with TLS. Anterior tibial translation (ATT) was measured in both knees using the KT-1000 arthrometer and two PROMs: International Knee Documentation Committee (IKDC) and Lysholm subjective form scores were examined preoperatively, 6 months postoperatively, and annually for 5 years thereafter in all patients.

RESULTS

One patient suffered a rupture of the graft, and one patient had a screw loosening. Two patients were lost for follow-up, so 22 patients were the final study group. Median (25-75%) ATT side-to-side differences between the injured and uninjured sides were 4 (3,5-4)mm preoperatively, 0,75 (0-1)mm 1 year postoperatively, and 0,75 (0-1)mm 5 years after the operation (P<0.001). Median (25-75%) IKDC scores were 44.25 (35.6-55.15), 92.55 (87.08-96.6), and 95.4 (90.8-97.7) points preoperatively and 1 year (P<0.001) and 5 years postoperatively, respectively. Median (25-75%) Lysholm scores were 52 (38.75-64.5), 95.5 (94.75-99.25), and 97.5 (95-99) points preoperatively and 1 year (P<0.001) and 5 years postoperatively, respectively.

DISCUSSION

ACLR with TLS might already achieve favourable outcomes 1 year postoperatively, when measured objectively (ATT) and with PROMs. These outcomes persist 5 year postoperatively. LEVEL OF EVIDENCE IV: retrospective cohort study.

Suspension button constructs restore posterior knee laxity in solid tibial avulsion of the posterior cruciate ligament

PURPOSE

Dislocated tibial avulsions of the posterior cruciate ligament (PCL) require surgical intervention. Several arthroscopic strategies are options to fix the fragment and restore posterior laxity, including two types of suspension button devices: adjustable (self-locking) and rigid knotted systems. Our hypothesis was that a rigid knotted button construct has superior biomechanical properties regarding laxity restoration compared with an adjustable system. Both techniques were compared with standard screw fixation and the native PCL.

METHODS

Sixty porcine knees were dissected. The constructs were tested for elongation, stiffness, yield force, load to failure force, and failure mode in a material testing machine. Group N (native, intact PCL) was used as a control group. In group DB (Dogbone™), TR (Tightrope™), and S (screw), a standardized block osteotomy with the osteotomized fragment attached to the PCL was set. The DB and TR groups simulated using a suspension button system with either a rigid knotted (DB) or adjustable system (TR). These groups were compared to a screw technique (S) simulating antegrade screw fixation from posterior.

RESULTS

Comparing the different techniques (DB, TR, S), no significant elongation was detected; all techniques achieved a sufficient posterior laxity restoration. Significant elongation in the DB and TR group was detected compared with the native PCL (N). In contrast, screw fixation did not lead to significant elongation. The stiffness, yield load, and load to failure force did not differ significantly between the techniques. None of the techniques reached the same level of yield load and load to failure force as the intact state.

CONCLUSION

Arthroscopic suspension button techniques sufficiently restore the posterior laxity and gain a comparable construct strength as an open antegrade screw fixation.

Estudo biomecânico de diferentes dispositivos de fixação femoral na reconstrução do ligamento patelofemoral medial em joelhos de suínos

Objetivo Avaliar diferentes dispositivos de fixação femoral na reconstrução do ligamento patelofemoral medial para comparar sua eficácia quanto à força de fixação até a falha em joelhos suínos.

Métodos Foram ensaiados 30 joelhos de suínos subdivididos em 3 grupos de 10 joelhos. Os enxertos retirados foram dissecados de tendões extensores das patas dos suínos. Cada grupo teve o enxerto fixado ao fêmur com parafuso de interferência, âncora, ou tenodese no tendão adutor. Os 3 métodos foram submetidos à testes biomecânicos utilizando uma máquina universal de ensaio de tração com uma velocidade de 20 mm/min.

Resultados Verificamos que a média mais elevada da resistência linear sob tração lateral (185,45 ± 41,22 N) ocorreu no grupo 1: “fixação por parafuso,” seguido do grupo 2: “fixação por âncora” (152,97 ± 49,43 N), e a média foi menor no grupo 3: “fixação por tenodese” (76,69 ± 18,90 N). Para a margem de erro fixada (5%), comprovou-se a diferença significativa entre os grupos (p < 0,001) e também através dos testes de comparações múltiplas (entre os pares de grupos) verificou-se a ocorrência de diferenças significativas. A variabilidade expressada por meio do coeficiente de variação mostrou-se reduzida, já que a referida medida foi inferior a 33,3%.

Conclusão O uso de parafusos de interferência no túnel ósseo de joelhos porcinos é suficientemente forte para fixação femoral na reconstrução do ligamento patelofemoral medial, assim como a fixação com âncoras montáveis com fio de alta resistência. Entretanto, a tenodese no tendão adutor mostrou-se frágil para essa finalidade.

A Randomized Controlled Trial of PEEK Versus Titanium Interference Screws for Anterior Cruciate Ligament Reconstruction With 2-Year Follow-up

BACKGROUND

Graft fixation with interference screws for anterior cruciate ligament (ACL) reconstruction is a highly successful technique. Polyether ether ketone (PEEK) is a novel thermoplastic polymer with high biocompatibility and mechanical properties that mimic native bone, and it can be imaged on computed tomography or magnetic resonance imaging (MRI) without signal flare.

PURPOSE

To compare the clinical performance of ACL reconstruction with PEEK and titanium interference screws at 2 years and to evaluate a novel method of measuring tunnel volume.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 133 patients underwent arthroscopic ACL reconstruction with 4-strand hamstring autografts and were randomized to have titanium or PEEK interference screws for femoral and tibial tunnel fixation. At 2 years, subjective Lysholm and International Knee Documentation Committee scores were assessed and clinical examination performed. At 12 months, MRI was performed to assess graft incorporation and cyst formation, and a novel technique was employed to measure tunnel volumes.

RESULTS

There were no significant differences in graft rerupture rate, contralateral ACL rupture rate, subjective outcomes, or objective outcomes. In the titanium and PEEK groups, MRI demonstrated high overall rates of graft integration (96%-100% and 90%-93%, respectively) and ligamentization (89% and 84%) and low rates of synovitis (22% and 10%) and cyst formation (0%-18% and 13%-15%). There was a higher proportion of patients with incomplete graft integration within the femoral tunnel in the PEEK group as compared with the titanium group (10% vs 0%, P = .03); however, the authors suggest that metal artifact precluded proper assessment of the graft in the titanium group by MRI. Tunnel volumes also appeared to be equivalent in the 2 groups and were measured with a novel technique that was highly reproducible in the PEEK group secondary to the absence of flare.

CONCLUSION

Two-year clinical analysis of PEEK interference screws for femoral and tibial fixation of ACL reconstructions showed equivalent clinical performance to titanium interference screws. Given the excellent mechanical characteristics, biological compatibility, and absence of metal artifact on MRI, PEEK has become our material of choice for interference screw fixation in ACL reconstruction.

Axial and shear pullout forces of composite, porcine and human metatarsal and cuboid bones

Objectives

The varying mechanical properties of human bone have influence on the study results. Pullout and shear forces of human bone were compared to different substitutes to evaluate their suitability for biomechanical studies.

Methods

After bone mineral density (BMD) determination, axial pullout tests were performed with cortical 3.5 mm nonlocking (NL) and 2.7 mm head locking (HL) screws on human, porcine and polyurethane composite bones. Porcine and human constructs were additionally loaded in shear direction.

Results

Apparent BMD was significantly lower in osteoporotic (159 mgHA/ccm ± 56) and nonosteoporotic (229 mgHA/ccm ± 25) human bone than that in porcine bone (325 mgHA/ccm ± 42; p < 0.01). Axial construct stiffness and ultimate pullout force of porcine bone (NL: 666N/mm ± 226, 910N ± 140; HL: 309N/mm ± 88, 744N ± 185) was significantly different from composite bone (NL: 1284N/mm ± 161; 1175N ± 116; HL: 1241N/mm ± 172, 1185N ± 225) and osteoporotic human bone (NL: 204N/mm ± 121, 185N ± 113; HL: 201N/mm ± 65; 189N ± 58) but not from nonosteoporotic human bone (NL: 620N/mm ± 205, 852N ± 281; HL: 399N/mm ± 224; 567N ± 242). Porcine bone exhibited an ultimate shear force (NL: 278N ± 99; HL: 431N ± 155) comparable to nonosteoporotic human bone (NL: 207 ± 68: HL: 374N ± 137).

Conclusion

Screw pullout and shear forces of porcine bone are close to nonosteoporotic human bone.

The translational potential of this article

Human bone specimens used in biomechanical studies are predominantly of osteoporotic bone quality. Conclusions on nonosteoporotic human bone behaviour are difficult. Alternatives such as porcine bone and composite bone were investigated, and it could be shown that screw pullout and screw shear forces of porcine bone are close to nonosteoporotic human bone.