Graft fixation in cruciate ligament reconstruction

The Effect of Supplementary Staple Fixation on Biomechanical Properties of Soft Tissue Graft Tibial Fixation in Anterior Cruciate Ligament Reconstruction

This study aimed to test and compare the biomechanical properties of three tibial fixation methods of anterior cruciate ligament (ACL) tendon grafts under cyclic load and load-to-failure testing in the bovine proximal tibiae, comprising (1) staple fixation alone, (2) interference screw fixation alone, and (3) interference screw fixation with a supplementary staple. Twenty-four bovine tibiae used in the study were divided into three groups (eight proximal tibiae in each group) based on tibial fixation methods of ACL tendon grafts: group A (a spiked ligament staple alone), group B (a cannulated interference screw alone), and group C (a cannulated interference screw with a supplementary staple). Each graft fixation was exposed to cyclic loading conditions. Significant differences were determined in failure load among the three groups (p = 0.008). The mean failure load was significantly higher in group B (717.04 ± 218.51 N) than in group A (308.03 ± 17.22 N) (p = 0.006). No significant differences were observed among the groups regarding axial stiffness (p = 0.442). Cyclic displacement differed significantly among the three groups (p = 0.005). In pairwise comparisons, the mean cyclic displacement was significantly higher in group A (8.22 ± 3.24 mm) compared with group C (1.49 ± 0.41 mm) (p = 0.005). Failure displacement varied considerably among the groups (p = 0.037). Although group B (15.53 ± 6.43 mm) exhibited a greater mean failure displacement than both group A (4.9 ± 0.75 mm) and group C (8.84 ± 4.65 mm), these differences did not reach statistical significance (p = 0.602 and p = 0.329, respectively). Interference screw fixation alone and supplementary staple fixation have biomechanically similar characteristics in terms of initial strength and stiffness of tibial ACL soft tissue graft fixation. Regardless of staple use, an interference screw with the same diameter as the tibial tunnel can ensure sufficient tensile strength in tibial ACL graft fixation.

Surgical Techniques in Primary ACL Reconstruction: Getting It Right the First Time

The ideal anterior cruciate ligament reconstruction (ACLR) is an individualized anatomic approach aimed at restoring the native structure and function of the knee. Surgeons are tasked with difficult decisions during operative planning, including the optimal graft choice for the patient and appropriate anatomic tunnel placement. Special considerations should additionally be given for skeletally immature patients and those at high-risk for failure, including younger, active patients participating in pivoting sports. The purpose of this review is to provide an overview of the individualized approach to ACLR, including the necessary preoperative and operative considerations to optimize patient outcomes.

Mechanical Evaluation of Bone-Patellar Tendon-Bone Graft Fixation to the Tibia in ACL Reconstruction: Bone Plug Tensioning and Fixation System versus Interference Screw

This study aimed to evaluate the mechanical properties of bone plug fixation to the tibia with a novel device, the Bone plug Tensioning and Fixation (BTF) system.Forty bone-tendon-bone grafts consisting of the whole patella-patellar tendon-tibial bone plug of 10-mm width and tibiae from the porcine were prepared. After creating a 10-mm tibial tunnel, the tibial bone plug was fixed to the tibia with the BTF system or the interference screw (IFS) to prepare a test specimen of the patella-patellar tendon-tibial bone plug fixed to the tibia. For the graft tension controllability study, a predetermined initial tension of 9.8 or 19.6 N was applied and maintained for 5 minutes. Then the bone plug was fixed to the tibia with the BTF system or IFS in 10 specimens, monitoring the residual tension for an additional 5 minutes. Then, a cyclic loading test and a tension-to-failure test were performed.The mean difference between the residual tension and the predetermined tension was significantly smaller in BTF fixation (9.8 N → 10.6 ± 2.2 N; 19.6 N → 18.9 ± 2.1 N) than in IFS fixation (9.8 N → 23.4 ± 7.4 N; 19.6 N → 28.9 ± 11.5 N). The mean displacement of the bone plug after cyclic loading was significantly less in the BTF group (1.2 ± 0.6 mm) than in the IFS group (2.2 ± 1.0 mm; p < 0.01). Stiffness was significantly greater in the BTF group (504.6 ± 148.8 N/mm) than in the IFS group (294.7 ± 96.7 N/mm; p < 0.01), whereas the maximum failure loads in the two groups did not differ significantly (724.2 ± 180.3 N in the BTF and 634.8 ± 159.4 N in the IFS groups).BTF system better performed in graft tension controllability than IFS did. BTF fixation was superior to IFS fixation in the displacement of the bone plug during the cyclic loading test and in stiffness in the tension-to-failure test.

Metal interference screw fixation combinations show high revision rates in primary hamstring tendon ACL reconstruction

BACKGROUND

Different fixation methods in anterior cruciate ligament reconstruction (ACLR) have been associated with different revision rates, specifically in the early postoperative period. However, most previous research has either grouped together different fixation types or evaluated femoral-sided fixation or tibial-sided fixation separately. Therefore, the purpose of this study was to determine ACL revision rates for specific combinations of femoral and tibial fixation methods within 2 years of primary hamstring tendon autograft ACLR based on data from the Swedish National Knee Ligament Registry (SNKLR).

METHODS

Patients that underwent primary hamstring tendon autograft ACLR between 2005 and 2018 in the SNKLR were included. The collected data included patient characteristics (age, sex, body mass index [BMI]), activity at time of injury, surgical information (concomitant injuries, time from injury to surgery, fixation types at the femur and tibia), and subsequent revision ACLR. Revision rate within 2 years of the index procedure was chosen, as ACLR fixation is most likely to contribute to ACLR revision within the first 2 years, during graft maturation.

RESULTS

Of the 23,238 included patients undergoing primary hamstring ACLR, 581 (2.5%) underwent revision ACLR within 2 years of the index procedure. Among the combinations used for > 300 patients, the femoral metal interference screw/tibial metal interference screw fixation combination had the highest revision rate followed by metal interference screw/resorbable screw and Endobutton/AO screw fixation combinations, with respective revision rates of 4.0, 3.0, and 3.0%. The lowest revision rate within 2 years of ACLR was found in the Endobutton/metal interference screw with backup Osteosuture fixation combination, used in 433 cases, with a failure rate of 0.9%.

CONCLUSION

Different early ACL revision rates were found across different combinations of femoral and tibial fixation devices within 2 years of primary hamstring tendon autograft ACLR. Metal interference screw fixation, particularly when performed on both the femoral and tibial sides, most frequently resulted in revision ACLR. These findings may be helpful for surgeons in selecting appropriate fixation devices for hamstring ACLR.

LEVEL OF EVIDENCE

IV.

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.

Comparison of medial tibiofemoral joint mechanics between all-suture anchors and transtibial pullout technique for posterior medial meniscal root tears

BACKGROUND

The posterior medial meniscal root tear (PMMRT) seriously impacts the tibiofemoral joint biomechanics. Two available techniques for PMMRT repair include the transtibial pullout (TPO) repair and all-suture anchor (ASA) repair techniques. These techniques have not been compared biomechanically.

METHODS

A total of 20 fresh porcine cadaveric knee specimens were used. All 20 knees were randomly and evenly distributed into four groups (five specimens per group): (1) intact posterior meniscal root, (2) PMMRT, (3) TPO repair technique for PMMRT, and (4) ASA repair technique for PMMRT. The tibiofemoral contact mechanics were investigated using a pressure sensor. All knee specimens were tested by being loaded with 600 N axial compressive force at three different flexion angles (0°, 45°, and 90°). The contact surface area, contact pressure, peak pressure, and time-zero displacement were recorded.

RESULTS

The PMMRT caused a significant decrease in contact surface area, an increase in contact pressure, and peak pressure from the reference values observed in the intact meniscus group (P = 0.05, 0.016, and 0.008, respectively). After fixation, no significant difference was observed between the ASA and intact group. Meanwhile, significant differences were found between the TPO and intact group in terms of contact surface area, contact pressure, and peak pressure. In the comparison between the two techniques, the ASA group demonstrated higher contact surface area than the TPO group at the average knee flexion angle (p = 0.05).

CONCLUSION

For most testing conditions, the ASA technique demonstrated superior biomechanical property in terms of contact surface area compared with the TPO technique under compressive loading conditions. The ASA technique could also restore the tibiofemoral contact mechanics to be comparable with those of the native intact knee. Meanwhile, a significant difference in tibiofemoral mechanics, compared with the intact knee, could be observed in the TPO technique.

Biomechanical Evaluation of TensionLoc Versus the Double Spike Plate for ACL Graft Tibial Fixation

Background

The optimal tibial fixation of anterior cruciate ligament (ACL) reconstruction (ACLR) grafts remains controversial.

Purpose/Hypothesis

The purpose of this study was to compare the biomechanical characteristics of the TensionLoc (TL) cortical fixation device with the Double Spike Plate (DSP) fixation device for ACL tibial fixation using both bone-patellar tendon-bone (BTB) and quadriceps grafts. It was hypothesized that there would be no differences in biomechanical characteristics between the fixation devices regardless of graft type.

Study Design

Controlled laboratory study.

Methods

ACLR was performed on 14 matched-pair cadaveric knee specimens-7 pairs using quadriceps grafts (n = 3 male cadaveric knee specimens; n = 4 female cadaveric knee specimens; age, 51 ± 8 years) and 7 pairs using BTB grafts (n = 3 male cadaveric knee specimens; n = 4 female cadaveric knee specimens; age, 50 ± 7 years). One side of each pair was randomized to receive DSP fixation, and the contralateral side received TL fixation. Specimens underwent cyclic ramp loading (10 cycles each at 50-100 N, 50-250 N, and 50-400 N), followed by load-to-failure testing, with the tensile force in line with the tibial tunnel. Results between the 2 fixation types were compared with a paired t test.

Results

For the quadriceps graft, there were no significant differences in cyclic loading or load-to-failure characteristics between fixation types (P≥ .092 for all parameters). For the BTB graft, TL fixation resulted in higher stiffness than DSP at all cyclic testing cycles except for cycle 1 during 100-N loading and had lower displacement at 250-N loading (3.4 ± 0.1 vs 5.4 ± 0.3 mm; P = .045). For load to failure, TL fixation resulted in higher stiffness than DSP fixation (232 ± 3.1 vs 188.4 ± 6.4 N/mm; P = .046); however, all other load-to-failure parameters were not statistically different (P≥ .135 for all parameters).

Conclusion

With the quadriceps tendon graft, there were no significant differences in biomechanical characteristics between TL and DSP ACL tibial fixations; however, with BTB grafts, the TL tibial fixation demonstrated greater biomechanical integrity than the DSP tibial fixation.

Clinical Relevance

The TL fixation device may provide an alternative ACL tibial fixation option for BTB and soft tissue grafts.

The "N+10 Rule" to Avoid Graft-Tunnel Mismatch in Bone-Patellar Tendon-Bone ACL Reconstruction Using Independent Femoral Tunnel Drilling

Background

Graft-tunnel mismatch (GTM) is a common problem in anterior cruciate ligament (ACL) reconstruction (ACLR) using bone-patellar tendon-bone (BPTB) grafts.

Hypothesis

Application of the "N+10 rule" in endoscopic ACLR with BPTB grafts will result in acceptable tibial tunnel length (TTL), minimizing GTM.

Study Design

Controlled laboratory study.

Methods

Endoscopic BPTB ACLR was conducted on the paired knees of 10 cadaveric specimens using 2 independent femoral tunnel drilling techniques-accessory anteromedial portal and flexible reamer. The graft bone blocks were trimmed to 10 × 20 mm, and the intertendinous distance (represented by "N") between the bone blocks was measured. The N+10 rule was used to set the angle of the ACL tibial tunnel guide to the appropriate number of degrees for drilling. The amount of excursion or recession of the tibial bone plug in relation to the anterior tibial cortical aperture was measured in both flexion and extension. A GTM threshold of ±7.5 mm was set based on prior studies.

Results

The mean BPTB ACL intertendinous distance was 47.5 ± 5.5 mm. The mean measured intra-articular distance was 27.2 ± 3 mm. Using the N+10 rule, the mean total (flexion plus extension) GTM was 4.3 ± 3.2 mm (GTM in flexion, 4.9 ± 3.6 mm; GTM in extension, 3.8 ± 3.5 mm). In 18 of 20 (90%) cadaveric knees, the mean total GTM fell within the ±7.5-mm threshold. When comparing the actual measured TTL to the calculated TTL, there was a mean difference of 5.4 ± 3.9 mm. When comparing femoral tunnel drilling techniques, the total GTM for the accessory anteromedial portal technique was 2.1 ± 3.7 mm, while the total GTM for the flexible reamer technique was 3.6 ± 5.4 mm (P = .5).

Conclusion

The N+10 rule resulted in an acceptable mean GTM in both flexion and extension. The mean difference between the measured versus calculated TTL using the N+10 rule was also acceptable.

Clinical Relevance

The N+10 rule is a simple and effective intraoperative strategy for achieving desired TTL regardless of patient-specific factors to avoid excessive GTM in endoscopic BPTB ACLR using independent femoral tunnel drilling.

Tibial Press-Fit Fixation Technique in Anterior Cruciate Ligament Reconstruction

Implant-free press-fit tibial fixation technique has gained popularity recently due to the problems in bone tunnel expansion, defect, and revision surgery due to the tibial fixation material preferred in anterior cruciate ligament surgery. Patellar tendon-tibial bone autograft offers several advantages in anterior cruciate ligament reconstruction. We describe a tibial tunnel preparation method and the use of patellar tendon-bone graft in the implant-free tibial press-fit technique. We call this the Kocabey press-fit technique.

Graft-Specific Surgical and Rehabilitation Considerations for Anterior Cruciate Ligament Reconstruction with the Quadriceps Tendon Autograft

Anterior cruciate ligament reconstruction (ACLR) with a bone-patellar tendon-bone (BPTB) or hamstring tendon (HT) autograft has traditionally been the preferred surgical treatment for patients returning to Level 1 sports. More recently, international utilization of the quadriceps tendon (QT) autograft for primary and revision ACLR has increased in popularity. Recent literature suggests that ACLR with the QT may yield less donor site morbidity than the BPTB and better patient-reported outcomes than the HT. Additionally, anatomic and biomechanical studies have highlighted the robust properties of the QT itself, with superior levels of collagen density, length, size, and load-to-failure strength compared to the BPTB. Although previous literature has described rehabilitation considerations for the BPTB and HT autografts, there is less published with respect to the QT. Given the known impact of the various ACLR surgical techniques on postoperative rehabilitation, the purpose of this clinical commentary is to present the procedure-specific surgical and rehabilitation considerations for ACLR with the QT, as well as further highlight the need for procedure-specific rehabilitation strategies after ACLR by comparing the QT to the BPTB and HT autografts.

Level of Evidence

Level 5.

The Bone Bridge for Tibial ACL Graft Fixation: A Biomechanical Analysis of Different Tibial Fixation Methods for ACL Reconstruction

Background

The tibial fixation site is considered the weak link in anterior cruciate ligament (ACL) reconstruction, and conflicting results regarding the biomechanical properties of various fixation methods have been reported.

Purpose

To examine knots tied over a bone bridge and its biomechanical properties as a suitable tibial fixation method in ACL reconstruction.

Study Design

Controlled laboratory study.

Methods

We divided 40 fresh-frozen porcine tibiae into 4 equal groups to evaluate flexor tendon grafts set with standard tibial fixation techniques: (1) bone bridge (BB group), (2) suspension button (SB group), (3) combined interference screw and bone bridge (IFS/BB group), and (4) combined interference screw and suspension button (IFS/SB group). Each construct was subjected to cyclic loading (1500 cycles, 50-250 N, 1 Hz) with a servohydraulic materials testing machine to measure elongation; load-to-failure testing (displacement rate: 25 mm/s) was then performed. Load to failure, stiffness, and yield load were compared between constructs using 1-way analysis of variance.

Results

The hybrid fixation constructs (IFS/BB and IFS/SB groups) showed significantly better biomechanical properties than the isolated extracortical fixation constructs (BB and SB groups) (P < .05 for all). There were no differences between the isolated extracortical fixation constructs or between the hybrid fixation constructs in elongation or load to failure; however, stiffness of the IFS/BB group was significantly higher than that of the IFS/SB group (175.3 ± 16.6 vs 144.9 ± 20.1 N/mm, respectively; P < .05). Stiffness between the SB and BB groups was not significantly different.

Conclusion

Hybrid fixation had superior biomechanical performance compared with isolated extracortical fixation. However, tibial graft fixation using a bone bridge either as isolated extracortical fixation or combined with an interference screw for hybrid fixation showed equivalent biomechanical properties compared with suspension button-based graft fixation.

Clinical Relevance

The clinical use of a bone bridge for tibial graft fixation could reduce the cost for ACL reconstruction and lower the rate of implant-associated issues.

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.

Active exercise therapy improves the recovery of knee joint function and reduction of muscle atrophy after medial patellofemoral ligament reconstruction for recurrent patellar dislocation

OBJECTIVES

Medial patellofemoral ligament (MPFL) reconstruction is an important surgical therapy for recurrent patellar dislocation. However, few studies have focused on exercise therapy after MPFL reconstruction. Therefore, the first purpose was to compare the active and traditional postoperative exercise therapies on the recovery of knee joint function and reduction of muscle atrophy after MPFL reconstruction, and the second purpose was to compare the active and traditional postoperative exercise therapies on the patellar stability after MPFL reconstruction.

METHODS

The cases of 31 patients with recurrent patellar dislocation treated with patella double semi-tunnel anatomical MPFL reconstruction from February 2016 and February 2019 were retrospectively reviewed. The clinical outcomes, including the patellar tilt angle (PTA), lateral patellofemoral angle (LPFA), thigh circumference reduction, Kujala score, and Lysholm score, were compared between two groups (i.e., active exercise and traditional exercise groups) preoperatively, 3 months postoperatively, 6 months postoperatively, 12 months postoperatively, and 24 months postoperatively.

RESULTS

The Kujala score was significantly higher in the active exercise group than traditional exercise group 3 months postoperatively (80.06 vs. 74.80, P < 0.01), 6 months postoperatively (89.19 vs. 82.07, P < 0.01), 12 months postoperatively (91.43 vs. 86.60, P < 0.01), and 24 months postoperatively (92.50 vs. 90.27, P = 0.02). Similarly, there was a higher Lysholm score in the active exercise group compared with traditional exercise group 3 months postoperatively (81.25 vs. 76.53, P < 0.01), 6 months postoperatively (89.81 vs. 84.80, P < 0.01), 12 months postoperatively (93.25 vs. 88.40, P < 0.01), and 24 months postoperatively (93.69 vs. 90.67, P < 0.01). Significantly lower thigh circumference reduction was reported in the active exercise group compared with that in the traditional exercise group 3 months postoperatively (1.90 ± 0.57 vs. 2.45 ± 0.45, P < 0.01) and 6 months postoperatively (1.50 ± 0.31 vs. 1.83 ± 0.32, P < 0.01). No statistical difference was observed between the two groups in terms of PTA (P > 0.05) or LPFA postoperatively (P > 0.05).

CONCLUSIONS

Our results suggested that active exercise therapy might benefit the early recovery of knee joint function and reduction of muscle atrophy in patients with recurrent patellar dislocation after MPFL reconstruction.

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.

Evaluation of the degradation of two bioabsorbable interference screws: an in-vivo study in sheep

PURPOSE

To evaluate in-vivo degradation of two bioabsorbable interference screws.

METHODS

Twenty-two crossbred Santa Inês ewes were used. A poly-DL-lactide (PDLLA) screw (70%/30%) was inserted in the right pelvic limb, and a PDLLA screw (70%) + β-tri-calcium phosphate (β-TCP) (30%) in the left pelvic limb. Animals were euthanized at one, four, seven and a half and 18 months after surgery. Plain radiography, computed tomography (CT), microCT, and histological analysis were accomplished.

RESULTS

PDLLA screw was hypodense at all evaluation moments, but with progressive density increase along the central axis, whereas PDLLA/β-TCP was initially hyperdense and progressively lost this characteristic. No adverse reactions were observed on histological evaluation.

CONCLUSIONS

The inclusion of β-TCP favors screw degradation since the PDLLA/β-TCP screws evidenced a more intense degradation process than the PDLLA screws at the last evaluation. PDLLA screws showed higher bone production, evident around the screw thread, inside the lateral perforations, and in the central canal, whereas the PDLLA/β-TCP screws presented less bone tissue at the implantation site.

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.

Evaluation of Tibial Fixation Devices for Quadrupled Hamstring ACL Reconstruction

Background:

Shortcomings to tibial-side fixation have been reported as causes of failure after anterior cruciate ligament reconstruction. Adjustable-loop suspensory devices have become popular; however, no comparison with hybrid fixation (ie, interference screw and cortical button) exists to our knowledge.

Purpose:

The purpose of this study was to compare the biomechanical properties of adjustable loop devices (ALDs) in full-tunnel and closed-socket configurations in relation to hybrid fixation. We hypothesized that primary stability of fixation by a tibial ALD will not be inferior to hybrid fixation.

Study Design:

Controlled laboratory study.

Methods:

Tibial fixation of a quadrupled tendon graft was biomechanically investigated in a porcine tibia–bovine tendon model using 5 techniques (n = 6 specimens each). The tested constructs included hybrid fixation with a cortical fixation button and interference screw (group 1), single cortical fixation with the full-tunnel technique using an open-suture strand button (group 2) or an ALD (group 3), or closed-socket fixation using 2 different types of ALDs (groups 4 and 5). Each specimen was evaluated using a materials testing machine (1000 cycles from 50-250 N and pull to failure). Force at failure, cyclic displacement, stiffness, and ability to pretension the graft during insertion were compared among the groups.

Results:

No differences in ultimate load to failure were found between the ALD constructs (groups 3, 4, and 5) and hybrid fixation (group 1). Cyclic displacement was significantly higher in group 2 vs all other groups (P < .001); however, no difference was observed in groups 3, 4, and 5 as compared with group 1. The remaining tension on the construct after fixation was significantly higher in groups 3 and 4 vs groups 1, 2, and 5 (P < .02 for all comparisons), irrespective of whether a full-tunnel or closed-socket approach was used.

Conclusion:

Tibial anterior cruciate ligament graft fixation with knotless ALDs achieved comparable results with hybrid fixation in the full-tunnel and closed-socket techniques. The retention of graft tension appears to be biomechanically more relevant than tunnel type.

Clinical Relevance:

The study findings emphasize the importance of the tension at which fixation is performed.

Biomechanical properties of common graft choices for anterior cruciate ligament reconstruction: A systematic review

BACKGROUND

This systematic review explores the differences in the intrinsic biomechanical properties of different graft sources used in anterior cruciate ligament (ACL) reconstruction as tested in a laboratory setting.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, two authors conducted a systematic review exploring the biomechanical properties of ACL graft sources (querying PubMed, Cochrane, and Embase databases). Using the keywords "anterior cruciate ligament graft," "biomechanics," and "biomechanical testing," relevant articles of any level of evidence were identified as eligible and included if they reported on the biomechanical properties of skeletally immature or mature ACL grafts solely and if the grafts were studied in vitro, in isolation, and under similar testing conditions. Studies were excluded if performed on both skeletally immature and mature or non-human grafts, or if the grafts were tested after fixation in a cadaveric knee. For each graft, failure load, stiffness, Young's modulus, maximum stress, and maximum strain were recorded.

FINDINGS

Twenty-six articles were included. Most studies reported equal or increased biomechanical failure load and stiffness of their tested bone-patellar tendon-bone, hamstring, quadriceps, peroneus longus, tibialis anterior and posterior, Achilles, tensor fascia lata, and iliotibial band grafts compared to the native ACL. All recorded biomechanical properties had similar values between graft types.

INTERPRETATION

Most grafts used for ACL reconstruction are biomechanically superior to the native ACL. Utilizing a proper graft, combined with a standard surgical technique and a rigorous rehabilitation before and after surgery, will improve outcomes of ACL reconstruction.

Comparison of Acorn and Fluted Reamers on Tibial Tunnel Outer Aperture Dimensions in ACL Reconstruction

The aim of this study was to determine if the type of reamer used in tibial tunnel creation during anterior cruciate ligament (ACL) reconstruction influences the dimensions of the tunnel's outer aperture. Tibial tunnels were created in tibial saw bones by reaming over a guidewire using an 8 mm acorn or fluted reamer in an antegrade manner. Reaming was aimed either in line with the guidewire, or with 10-degree inferior/superior deviation in relation to the wire. The shape and size of the outer aperture of the tibial tunnel were compared between the two reamers. When using the acorn reamer, a 10-degree deviation in relation to the guidewire resulted in minimal change in outer aperture length (mean 13.6 vs. 15.6 mm, p = 0.11) and width (11.6 vs. 11.1 mm, p = 0.51). However, when using the fluted reamer, although the aperture width showed no substantial change with reamer/guidewire deviation (11.4 vs. 11.2 mm, p = 0.71), the mean length almost doubled (14.7 vs. 28.1 mm, p = 0.002). The use of a fluted reamer when reaming the tibial tunnel creates a distal aperture which is inconsistently sized, larger, and of oblong shape compared with an acorn-shaped reamer. This should be taken in consideration when using a fluted reamer for creating the tibial tunnel in ACL reconstruction.

Anatomical rectangular tunnel anterior cruciate ligament reconstruction provides excellent clinical outcomes

PURPOSE

The purpose of this study was to prospectively evaluate the clinical outcomes following anatomical rectangular tunnel anterior cruciate ligament (ACL) reconstruction with a bone-patellar tendon-bone (BTB) graft using an adjustable-length femoral cortical fixation device with enough patients and a high follow-up rate.

METHODS

This study included 125 patients who underwent anatomical rectangular tunnel ACL reconstruction with a BTB graft. A BTB TightRope^® was used for femoral graft fixation. Clinical evaluations were performed more than 2 years after surgery using the International Knee Documentation Committee (IKDC) Form. Patients interviewed by telephone were only subjectively evaluated. The side-to-side difference in anterior laxity at a manual maximum force was measured using the KT-2000 Arthrometer^®.

RESULTS

Among the 125 patients, 99 were ultimately included and 26 were lost to follow-up (follow-up rate: 79%). Eight patients had re-tear (re-tear rate: 8%) and six patients had ACL injuries to the contralateral knee. Three patients did not follow our rehabilitation programme. One patient suffered septic arthritis. These 18 patients were considered ineligible for clinical evaluations. Therefore, clinical evaluations were performed in 81 of the 99 patients (64 were available for direct follow-up and 17 were available for a telephone interview). The follow-up period was 30 ± 10 months (range 24-68 months). According to the IKDC subjective assessment, 48 (59%) and 33 (41%) knees were graded as normal and nearly normal, respectively. A loss of extension (3°-5°) was observed in five patients (8%), whereas one patient (2%) exhibited a loss of flexion (3°-5°). The Lachman test was negative in 63 patients (98%). The pivot shift test was negative in 59 patients (92%). The side-to-side difference in KT value was 0.4 ± 0.7 mm (range - 1-4 mm).

CONCLUSION

Anatomical rectangular tunnel ACL reconstruction with a BTB graft using an adjustable-length femoral cortical fixation device provided excellent clinical outcomes both subjectively and objectively more than 2 years after surgery, whereas 8 of the 99 patients had re-tear of the graft. The adjustable-length femoral cortical fixation device could be safely used in anatomical rectangular tunnel ACL reconstruction with a BTB graft.

LEVEL OF EVIDENCE

III.

Suspensory Versus Interference Tibial Fixation of Hamstring Tendon Autografts in Anterior Cruciate Ligament Reconstruction: Results From the New Zealand ACL Registry

BACKGROUND

The hamstring tendon is frequently used to reconstruct the anterior cruciate ligament (ACL), but there is a lack of consensus on the optimal method of fixation. Registry studies have shown that the type of femoral fixation device can influence the risk of revision ACL reconstruction (ACLR), but it is unclear whether the type of tibial fixation has an effect. In New Zealand, over 95% of hamstring tendon grafts are fixed with an adjustable loop suspensory device on the femoral side, with variable usage between suspensory and interference devices, with or without a sheath, on the tibial side.

PURPOSE

To investigate the association between the type of tibial fixation device and the risk of revision ACLR.

STUDY DESIGN

Cohort Study; Level of evidence, 2.

METHODS

Prospective data recorded in the New Zealand ACL Registry were analyzed. Only primary ACLRs performed with a hamstring tendon autograft fixed with a suspensory device on the femoral side were included. A Cox regression survival analysis with adjustment for patient factors was performed to analyze the effects of the type of tibial fixation device, the number of graft strands, and graft diameter on the risk of revision.

RESULTS

A total of 6145 primary ACLRs performed between 2014 and 2019 were analyzed. A total of 59.6% of hamstring tendon autografts were fixed with a suspensory device on the tibial side (n = 3662), 17.6% with an interference screw with a sheath (n = 1079), and 22.8% with an interference screw without a sheath (n = 1404). When compared with suspensory devices, a higher revision risk was observed when using an interference screw with a sheath (adjusted hazard ratio [HR], 2.05; P = .009) and without a sheath (adjusted HR, 1.81; P = .044). The number of graft strands and a graft diameter of ≥8 mm were associated with the rate of revision on the univariate analysis; however, after adjusting for confounding variables on the multivariate analysis, they did not significantly influence the risk of revision.

CONCLUSION

In this study of hamstring tendon autografts fixed with an adjustable loop suspensory device on the femoral side during primary ACLR, the use of an interference screw, with or without a sheath, on the tibial side resulted in a higher revision rate when compared with a suspensory device.

Assessment of sheep knee joint after ACL replacement with Achilles tendon autograft and PLA-based implant

In this study, we propose a new approach in the anterior cruciate ligament (ACL) replacement to provide stability and integration with bone tunnel. A polylactide (PLA)-based tubular implant was used to support the graft stabilization in femoral and tibial bones and to stimulate the healing process after (ACL) replacement on a sheep model. The ACL was replaced with an autologous Achilles tendon split graft. The tendon-to-bone healing in the model was analyzed after 6 and 12 weeks. Two groups of animals were compared, i.e. the group with the PLA-based implant used in the ACL replacement and the control group without the implant. The knee joints were mechanically and clinically evaluated, including the histopathology tests, to determine their stability and integrity. The results indicated that the bioresorbable PLA-based tubular implant may facilitate integration of the tendon graft with bone. Remodeling the allograft inside the implant improves the joint mobility from the first week of healing: no pathological changes were observed at the surgery site and in the animals' mobility. After 6 and 12 weeks of healing no significant changes in the mechanical parameters of the knee joint were observed, regarding the joint failure force, knee displacement, angular mobility range and joint stiffness. Relatively small values of the non-destructive tests in the knee displacement, already 6 weeks after surgery, indicated the early stabilization of the knee joint. The studies showed that the failure forces of knee joints after the ACL replacement with the PLA-based implant are lower than those of an intact joint, although their biomechanical features, including strain-at- failure, are similar. The biomechanical parameters of the knee joint were significantly improved due to the selected method of attaching the autograft ends to the femoral and tibial bone surfaces. After 12 weeks the intra-tunnel tendon-bone site with the PLA implant revealed the better tibia-femur joint mechanical stability, linear force-strain function and the decreasing strain-to-failure value, as compared to the control group.

Does a combined screw and dowel construct improve tibial fixation during anterior cruciate ligament reconstruction?

PURPOSE

The aims of the present study were to compare the biomechanical properties of tibial fixation in hamstring-graft ACL reconstruction using interference screw and a novel combination interference screw and dowel construct.

MATERIAL AND METHODS

We compared the fixation of 30 (2- and 4-stranded gracilis and semitendinosis tendons) in 15 fresh-frozen porcine tibiae with a biocomposite resorbable interference screw (Group 1) and a screw and dowel construct (Group 2). Each graft was subjected to load-to-failure testing (50 mm/min) to determine maximum load, displacement at failure and pullout strength.

RESULTS

There were no significant differences between the biomechanical properties of the constructs. Multivariate analysis demonstrated that combination constructs (β = 140.20, p = 0.043), screw diameter (β = 185, p = 0.006) and 4-strand grafts (β = 51, p = 0.050) were associated with a significant increase in load at failure. Larger screw diameter was associated with increased construct stiffness (β = 20.15, p = 0.020).

CONCLUSION

The screw and dowel construct led to significantly increased fixation properties compared to interference screws alone in a porcine model. Increased screw diameter and utilization of 4-strand ACL grafts also led to improvement in load-to-failure of the construct. However, this is an in vitro study and additional investigations are needed to determine whether the results are reproducible in vivo.

LEVEL OF EVIDENCE

Level V; Biomechanical study.

Press-fit fixation in anterior cruciate ligament reconstruction yields low graft failure and revision rates: a systematic review and meta-analysis

PURPOSE

Press-fit fixation is a hardware-free technique in anterior cruciate ligament reconstruction (ACLR). The purpose of this review was to quantitatively assess the risk profile and outcomes of press-fit fixation and provide an update on its effectiveness compared to more standard fixation techniques of ACLR.

METHODS

The electronic databases PUBMED, MEDLINE, and EMBASE were searched on March 26, 2020 for therapeutic randomized controlled trials (RCT) addressing press-fit fixation for primary ACLR. The Grading of Recommendations Assessment, Development and Evaluation tool was used to assess the quality for randomized studies. A meta-analysis with a random-effects model was used to pool applicable outcomes data.

RESULTS

A total of six eligible RCTs were included in this review. There were 292 patients (72.9% male) with a mean age of 28.8 ± 3.8 years and a mean follow-up of 81.3 ± 88.3 months that underwent press-fit ACLR on the femoral, tibial or both tunnels. Femoral fixation techniques included press-fit fixation (96.6%) and cross-pin fixation (3.4%). Tibial fixation techniques included press-fit (37.0%), staples (28.1%), interference screws (21.2%) and abarticular post-screws (13.7%). Graft options included bone-patellar tend--bone autografts (73.6%) and semitendinosus and gracilis tendon autograft (26.4%). Significant improvements (p < 0.05) from baseline to follow-up were found for clinical outcomes. Significantly less postoperative bone tunnel enlargement (p < 0.05) was found with tibial press-fit fixation when compared to biodegradable screws. The overall complication rate was 13.3%. There were no significant differences in complication rates [odds ratio = 0.84 (95%CI 0.43-1.66); p = n.s.] (I² = 0%) between patients undergoing femoral press-fit fixation and femoral metal interference screw fixation.

CONCLUSION

The overall graft failure and revision rates with press-fit ACLR were low. There were no significant differences in complication rates between patients undergoing femoral press-fit and femoral metal interference screw fixation. Included studies found that patients undergoing press-fit fixation for ACLR had significant improvements in functional outcome scores postoperatively and had significantly reduced postoperative bone tunnel enlargement compared to patients undergoing bioabsorbable fixation. Thus, early evidence suggests that press-fit fixation appears to be a good option for patients undergoing ACLR.

LEVEL OF EVIDENCE

I.

Arthroscopic confirmation of femoral button deployment avoids post-operative X-ray in ACL reconstruction

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) with cortical fixation adjustable-loop devices are associated with high potential risk of button malpositioning or interposition of the soft tissue between lateral femoral cortex and the button. Surgeons usually use X-rays to check and avoid button malposition and soft tissue interposition. Arthroscopic visualization of button position through the lateral gutter has been described. With this technique, it is possible for identification and correction of femoral button malalignment in the setting of soft tissue interposition and it could avoid the use of post-operative X-ray.

METHODS

A total of 193 ACLR were included and patients were randomized into two groups. The first series (Group A) of 112 patients who sustained an ACLR with post-operative X-ray to assess the position of the femoral button and the second series (Group B) of 81 patients who sustained an ACLR with an arthroscopic exploration of the button followed by post-operative X-ray.

RESULTS

On the post-operative radiographs, tissue interposition between the button and femoral cortex was found in nine cases of 112 in Group A (8%) and in zero case of 81 in Group B (0%). In six cases (7,4%) in Group B, there was a soft tissue interposition between the button and femoral cortex as visualized by arthroscopic confirmation and before post-operative X-ray; in all these cases, the soft tissue was removed, and the button was in contact with the bone in all X-ray made in the Group B.

CONCLUSIONS

This technique allows for identification and correction of femoral button malalignment in the setting of soft tissue interposition and reduces the use of post-operative X-ray.

Tibial-graft fixation methods on anterior cruciate ligament reconstructions: a literature review

Introduction

Anterior cruciate ligament (ACL) reconstruction is the most performed orthopedic surgical procedure. The result of ACL reconstructions depends on multiple technical variables, including tension to be applied to the graft for fixation, knee-flexion angle during fixation and the type of fixation to the bone.

Objective

To carry out a survey of the literature with the best evidence on these themes.

Methods

Literature review about methods of tibial-graft fixation in ACL reconstructions – tension applied at the time of fixation, type of graft fixation, and knee-flexion degree during tibial fixation.

Results

Thirty studies on the selected topics were found. Most studies point to graft-tension levels close to 90 N to obtain the best results. Regarding the knee-flexion angle, multiple studies suggest that fixation at a 30° angle would bring superior biomechanical advantages. Regarding the type of implant for fixation, it is not possible to affirm the superiority of one method over another in clinical outcomes.

Conclusions

There is no consensus on the best method for tibial fixation of the grafts in ACL reconstructions regarding tension, type of implant and knee-flexion angle. However, the analysis of the studies pointed to certain trends and allowed the drawing of specific conclusions.

Single-Stage Revision Anterior Cruciate Ligament Reconstruction: Experience With 91 Patients (40 Elite Athletes) Using an Algorithm

BACKGROUND

The increased prevalence of anterior cruciate ligament (ACL) reconstruction has led to an increased need for revision ACL reconstructions. Despite the growing body of literature indicating that single-stage revision ACL reconstruction can yield good outcomes, there is a lack of data for determining when and how to safely perform a single-stage revision.

PURPOSE

To assess the outcomes, graft failure rates, and return-to-play rates of a decision-making algorithm for single-stage revision ACL reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We reviewed a consecutive series of revision ACL reconstructions performed by the senior author between September 2009 and July 2016 with minimum 2-year follow-up. All patients were assessed, and decision making was undertaken according to the algorithm. Outcomes measured were further surgery, graft rerupture, re-revision, Tegner score, and Knee injury and Osteoarthritis Outcome Score (KOOS). For the elite athlete population, return-to-play time, duration, and level of play after surgery as compared with preinjury were also determined.

RESULTS

During this period, 93 procedures were performed in 92 patients (40 elite athletes). Two 2-stage procedures were undertaken, leaving 91 single-stage procedures (91 patients) to form the basis for further study. At a mean 4.3 years (SD, 2.2 years) after surgery, there had been 2 re-revisions (2.2%) and 2 further instances of graft failure that had not been re-revised (total graft failure rate, 4.4%). There were 17 subsequent procedures, including 6 arthroscopic partial meniscectomies, 5 removals of prominent implants, and 1 total knee arthroplasty. The mean Tegner score was 8.02 before graft rerupture and 7.1 at follow-up. At follow-up, the mean KOOS outcomes were 79.3 for Symptoms, 88.0 for Pain, 94.2 for Activities of Daily Living, 73.6 for Sport, and 68.9 for Quality of Life. Of 40 elite athletes, 35 returned to play at a mean 11.2 months (SD, 3.6 months) after surgery.

CONCLUSION

Single-stage revision ACL reconstructions can be performed reliably in the majority of patients, with good clinical outcomes, low rerupture rates, and high-return-to play rates, even in the elite athlete population.

Incorporation of Whipstitch Suture in Tibial Interference Fixation Improves Pullout in Anterior Cruciate Ligament Soft Tissue Grafts

INTRODUCTION

Interference screw fixation of soft tissue grafts is commonly used in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to determine whether including suture material at the graft-screw interface affects ultimate fixation strength of soft tissue grafts using a tibialis anterior tendon allograft model.

MATERIALS AND METHODS

Forty fresh-frozen human tibialis anterior tendon allografts were fixed to rigid polyurethane foam simulating the tibial tunnel. Twenty grafts underwent fixation with interference screws and 20 with interference bolts. Within each group, 10 grafts had suture in contact with either the screw or bolt. A load-to-failure test was then performed at a rate of 200 mm/min.

RESULTS

The group of allografts with sutures in the tibial tunnel had significantly higher load to failure than the group without sutures. Using interference screw fixation, failure load of the grafts without sutures in the tunnel (535.2 ± 73.40 N) was significantly lower (P = .001) than with sutures in the tunnel (696.3 ± 110.0 N). Using interference bolt fixation, failure load of the grafts without sutures in the tunnel (613.0 ± 83.46 N) was significantly lower (P <.0001) than with sutures in the tunnel (845.8 ± 87.23 N).

CONCLUSIONS

In a biomechanical model, suture within the tibial tunnel enhances fixation strength with both interference screw and bolt fixation for soft tissue tibialis anterior allografts. Additionally, there was no difference in load to failure when comparing failure of a screw with suture in the tunnel with an interference bolt without suture. Due to improved biomechanical properties, incorporation of suture in the bone-graft interface should be considered when performing soft tissue ACL allograft reconstructions. Failure at the tibial bone-graft interface is a known complication of ACL reconstruction, and incorporation of suture within the interface should be considered for improved biomechanical properties.

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.

TightRope Versus Biocomposite Interference Screw for Fixation in Allograft ACL Reconstruction: Prospective Evaluation of Osseous Integration and Patient Outcomes

Background

Anterior cruciate ligament (ACL) reconstruction is a commonly performed procedure with many options regarding graft choice and graft fixation. The purpose of this study was to compare suspensory and aperture fixation in terms of femoral osseous integration of the bone block after ACL reconstruction with an Achilles tendon allograft.

Methods

After institutional review board approval and patient consent were obtained, 37 patients underwent ACL reconstruction with an Achilles tendon allograft. The patients were randomized according to the graft femoral fixation technique, which was with either a suspensory device (Arthrex TightRope) or aperture fixation by a biocomposite interference screw (Arthrex BioComposite Interference Screw or DePuy Mitek MILAGRO Interference Screw). Tibial fixation, performed with a biocomposite screw and knotless anchor, was identical in all patients. All patients underwent a computed tomography (CT) scan at 6 months to evaluate bone block incorporation of the femoral graft within the femoral tunnel, which was the study's primary outcome. Secondary outcome measures included a postoperative visual analogue scale (VAS) pain score, range-of-motion measures, and International Knee Documentation Committee scores. Demographic data were collected.

Results

Thirty-three patients (89%) completed the study's 6-month follow-up, at which time the femoral ossification score was significantly greater in the aperture fixation group (p = 0.025). There was no substantial difference between the 2 groups with regard to any other outcome measure.

Conclusions

Performing Achilles tendon allograft ACL reconstruction with femoral aperture fixation results in greater femoral bone block incorporation at 6 months postoperatively compared with what is seen after suspensory fixation.

Level of Evidence

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Investigation of Hamstring Tendon Graft Fixation for the Reconstruction of Anterior Cruciate Ligament using Interference Screw Merely or in Combination with Supplementary Staple: A Clinical Trial

BACKGROUND

Hamstring graft tendon for anterior cruciate ligament (ACL) reconstruction is a common approach worldwide. Tibial side graft fixation to achieve appropriate stability is a serious concern, worldwide. The current study aims to compare the outcomes of mere use of interference screw for fixation of hamstring tendon graft versus the use of interference screw plus supplementary staple.

MATERIALS AND METHODS

This is a randomized clinical trial conducted on 53 patients who underwent ACL reconstruction from 2016 to 2018. The study population was randomly divided into two groups: graft fixation with interference screw only and interference screw plus supplementary staple. Postoperative recovery time, postoperative clinical examinations, and the scale of the International Knee Documentation Committee were assessed for participants and compared between two groups.

RESULTS

Comparison of two groups regarding demographic information, including age, gender distribution, postoperative recovery time, and body mass index, showed no statistical difference (P > 0.05). Postoperative Pivot test was insignificantly positive in 4 (16.7%) cases of screw interference with supplementary staple while it was positive in 3 (10.7%) cases with screw interference only approach (P = 0.98). IKCD index was not statistically different between two groups postoperatively (P = 0.72), while IKCD scores changed significantly following the surgical procedure, regardless of the type of the surgical procedure (P < 0.001).

CONCLUSION

Use of supplementary staple beside interference screw was as successful as mere use of interference screw for fixation of hamstring tendon autologous graft of the ACL reconstruction, regarding force withstanding. The comparison of the two approaches revealed no remarkable difference.

A Review on Finite Element Modeling and Simulation of the Anterior Cruciate Ligament Reconstruction

The anterior cruciate ligament (ACL) constitutes one of the most important stabilizing tissues of the knee joint whose rapture is very prevalent. ACL reconstruction (ACLR) from a graft is a surgery which yields the best outcome. Taking into account the complicated nature of this operation and the high cost of experiments, finite element (FE) simulations can become a valuable tool for evaluating the surgery in a pre-clinical setting. The present study summarizes, for the first time, the current advancement in ACLR in both clinical and computational level. It also emphasizes on the material modeling and properties of the most popular grafts as well as modeling of different surgery techniques. It can be concluded that more effort is needed to be put toward more realistic simulation of the surgery, including also the use of two bundles for graft representation, graft pretension and artificial grafts. Furthermore, muscles and synovial fluid need to be included, while patellofemoral joint is an important bone that is rarely used. More realistic models are also required for soft tissues, as most articles used isotropic linear elastic models and springs. In summary, accurate and realistic FE analysis in conjunction with multidisciplinary collaboration could contribute to ACLR improvement provided that several important aspects are carefully considered.

Comparative Risk-Benefit Profiles of Individual Devices for Graft Fixation in Anterior Cruciate Ligament Reconstruction: A Systematic Review and Network Meta-analysis

PURPOSE

To compare the efficacy and safety of individual devices for femoral and/or tibial graft fixation in anterior cruciate ligament (ACL) reconstruction.

METHODS

The PubMed, Embase, Cochrane Library, and Web of Science databases were searched from inception to December 12, 2018. Randomized controlled trials comparing individual devices for ACL graft fixation were included. Bayesian network meta-analysis was performed to assess the efficacy profile using the following outcomes: Lysholm score, International Knee Documentation Committee (IKDC) category, laxity, range of motion, and Tegner score. The incidence of infection, effusion, and graft rupture for each device was reported.

RESULTS

We included 57 randomized controlled trials involving 4,304 patients aged 23.8 to 40.9 years. The female proportion ranged from 0% to 100%. The length of follow-up ranged from 6 to 144 months. Of the 13 studied femoral fixation devices, none was significantly different from the others regarding the Lysholm score, IKDC category, range of motion, and Tegner score. Bioabsorbable interference screws (standardized mean difference, 1.3; 95% credible interval, 0.0-2.5) showed higher laxity than the EndoPearl at a borderline level of statistical significance, but the difference varied substantially within multiple sensitivity analyses. Infection (2.0%) was most commonly seen with the EndoPearl, whereas the bone mulch screw had the highest incidence of effusion (5.5%) and graft rupture (5.5%). For the 9 studied tibial fixation devices, no significant difference was observed in the aforementioned efficacy measurements. Bioabsorbable interference screws with staples had the highest incidence of infection (11.1%) and effusion (15.6%), whereas graft rupture was most commonly seen with the bone plug (4.0%).

CONCLUSIONS

Graft fixation devices in ACL reconstruction share a similar efficacy profile in terms of the Lysholm score, IKDC category, range of motion, and Tegner score but not laxity. On the other hand, safety profiles seem to vary among different devices. These findings can support surgeons, alongside their experience and preference, as well as the relative cost of each device, in delivering an individualized plan for an optimal operation.

LEVEL OF EVIDENCE

Level II, meta-analysis of Level I and II studies.

Aperture and Suspensory Fixation Equally Efficacious for Quadriceps Tendon Graft Fixation in Primary ACL Reconstruction: A Systematic Review

This review is aimed to compare suspensory and aperture quadriceps tendon autograft femoral and tibial fixations in primary anterior cruciate ligament reconstruction (ACL-R), and the clinical outcomes and complication profiles of each fixation method. Greater understanding of the optimal graft fixation technique for quadriceps tendon (QT) autografts may assist surgeons in improving outcomes after ACL-R. PubMed, Embase, and Medline were searched from database inception to September 2017, and again to July 2018, and identified 3,670 articles, 21 studies of which satisfied inclusion/exclusion criteria. Across included studies, 1,155 QT ACL-R patients (mean age, 28.7 years [range, 15-59 years], with mean postoperative follow-up of 36.1 months [range, 3.4-120 months]), were analyzed. Suspensory fixation on both sides demonstrated a higher percentage of patients (81.7%) achieving the highest rating of "A or B" on the International Knee Documentation Committee (IKDC) knee ligament examination form compared with aperture fixation on both sides (67.7%). Moreover, suspensory fixation had a lower side-to-side difference in anterior laxity (1.6 mm) when compared with aperture fixation (2.3 mm). Among studies which reported graft failure, all of which employed aperture fixation, the rate was 3.2%. Across available data, primary ACL-R using QT grafts appears to have successful short-term outcomes with a short-term graft failure rate of 3% independent of fixation method. While there is limited data regarding the comparison of aperture and suspensory soft-tissue quadriceps tendon (SQT) fixation in ACL-R, the findings of this systematic review suggest that suspensory fixation and aperture fixation in both the femoral and tibial tunnels are equally efficacious based on clinical outcome data on IKDC grade and measured laxity. This is a level IV, systematic review study.

Three-Dimensional Printed Porous Titanium Screw with Bioactive Surface Modification for Bone-Tendon Healing: A Rabbit Animal Model

The interference screw fixation method is used to secure a graft in the tibial tunnel during anterior cruciate ligament reconstruction surgery. However, several complications have been reported, such as biodegradable screw breakage, inflammatory or foreign body reaction, tunnel enlargement, and delayed graft healing. Using additive manufacturing (AM) technology, we developed a titanium alloy (Ti₆Al₄V) interference screw with chemically calcium phosphate surface modification technology to improve bone integration in the tibial tunnel. After chemical and heat treatment, the titanium screw formed a dense apatite layer on the metal surface in simulated body fluid. Twenty-seven New Zealand white rabbits were randomly divided into control and additive manufactured (AMD) screw groups. The long digital extensor tendon was detached and translated into a tibial plateau tunnel (diameter: 2.0 mm) and transfixed with an interference screw while the paw was in dorsiflexion. Biomechanical analyses, histological analyses, and an imaging study were performed at 1, 3, and 6 months. The biomechanical test showed that the ultimate pull-out load failure was significantly higher in the AMD screw group in all tested periods. Micro-computed tomography analyses revealed early woven bone formation in the AMD screw group at 1 and 3 months. In conclusion, AMD screws with bioactive surface modification improved bone ingrowth and enhanced biomechanical performance in a rabbit model.

Significant Loss of ACL Graft Force With Tibial-Sided Soft Tissue Interference Screw Fixation Over 24 Hours: A Biomechanical Study

Background

Tibial-sided graft fixation is thought to be critical for the success of anterior cruciate ligament (ACL) reconstruction. Nevertheless, little is known about the graft force after fixation during the first 24 hours after surgery or the influence of screw diameter and length during this time.

Purpose

To investigate the force, over the course of 24 hours, in soft tissue grafts secured with a tibial interference screw and to evaluate the effect of different screw diameters (7, 8, and 9 mm) and lengths (25 and 30 mm) on the force in these grafts.

Study Design

Controlled laboratory study.

Methods

Quadruple-strand flexor tendon grafts were fixed with bioabsorbable interference screws in 60 porcine tibiae. Grafts were pretensioned at 80 N over 10 minutes, and screws were inserted outside-in while a preload force of 80 N was applied. Different screw lengths (25 and 30 mm) and diameters (7, 8, and 9 mm), resulting in 6 groups with 10 specimens each, were tested. After release of the preload, graft force was recorded over 24 hours.

Results

A significant decrease in graft force progressed in all groups over the 24-hour period. In total, a median loss of 75 N (IQR, 68-79 N) compared with the initial loading force was observed. Compared with the loading force of 80 N, this corresponded to a median loss of 91%. No significant differences in the remaining graft force could be found among the 6 different screw length and diameter groups after 10 minutes, 100 minutes, or 24 hours.

Conclusion

Graft force in soft tissue grafts secured with a tibial interference screw decreased substantially over the first 24 hours after fixation. Neither the screw diameter nor the screw length affected the decrease in graft force. This raises substantial questions regarding the remaining fixation strength in vivo.

Clinical Relevance

It should not be expected that ACL reconstruction can mechanically restabilize an injured knee as would an intact ACL. Reconstructed knees should be protected from mechanical overload in the early postoperative period.

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.

Fixation of the Anterior Ligament Graft at the Tibial Pole: Biomechanical Analysis of Three Methods

Objective  Comparative biomechanical analysis of tibial fixation strength for ligament reconstruction with interference screw compared with screw post and washer, and compared with the associated fixation of both methods (hybrid fixation).

Method  A total of 54 specimens were used (porcine tibias and bovine flexor digital tendons), which were divided into three groups with fixation types similar to those used in anterior cruciate ligament (ACL) reconstruction: 1) fixation with interference screw; 2) fixation with screw post and toothed washer over knot and suture strand; and )- fixation with screw post and washer combined with interference screw (hybrid fixation). The analyses were performed through pull-out biomechanical tensile tests to determine the stiffness and load to system failure (yield load).

Results  The hybrid fixation group presented a significantly higher final stiffness (59.10 ± 3.45 N/mm) in comparison to the other groups ( p  < 0.05) and a higher yield load (581.34 ± 33.48 N) compared to the interference screw group ( p  < 0.05).

Conclusion  Hybrid fixation had biomechanical advantages over the bovine digital flexor graft fixation system in swine tibia during tensile tests.

Stratifying the mechanical performance of a decellularized xenogeneic tendon graft for anterior cruciate ligament reconstruction as a function of graft diameter: An animal study

Objectives

This study investigated the biomechanical performance of decellularized porcine superflexor tendon (pSFT) grafts of varying diameters when utilized in conjunction with contemporary ACL graft fixation systems. This aimed to produce a range of ‘off-the-shelf’ products with predictable mechanical performance, depending on the individual requirements of the patient.

Methods

Decellularized pSFTs were prepared to create double-bundle grafts of 7 mm, 8 mm, and 9 mm diameter. Femoral and tibial fixation systems were simulated utilizing Arthrex suspension devices and interference screws in bovine bone, respectively. Dynamic stiffness and creep were measured, followed by ramp to failure from which linear stiffness and load at failure were measured. The mechanisms of failure were also recorded.

Results

Dynamic stiffness was found to increase with greater graft diameter, with significant differences between all groups. Conversely, dynamic creep reduced with increasing graft diameter with significant differences between the 7 mm and 9 mm groups and the 8 mm and 9 mm groups. Significant differences were also found between the 7 mm, 8 mm, and 9 mm groups for linear stiffness, but no significant differences were found between groups for load at failure. The distribution of failure mechanisms was found to change with graft diameter.

Conclusion

This study showed that decellularized pSFTs demonstrate comparable biomechanical properties to other ACL graft options and are a potentially viable option for ACL reconstruction. Although grafts can be stratified by their diameter to provide varying biomechanical properties, it may be more appropriate to alter the fixation technique to stratify for a greater diversity of biomechanical requirements.

Cite this article: Bone Joint Res 2019;8:518–525.

Cyclic testing of tibialis tendon allografts for anterior cruciate ligament reconstruction using suture-post versus spiked washer tibial fixation

BACKGROUND

The purpose of this study was to directly compare spiked washer and suture-post tibial-sided fixation techniques used for anterior cruciate ligament reconstruction by measuring anterior tibial translation during cyclic tests.

METHODS

Fresh-frozen human knees were tested using a robotic system that applied 250 cycles of anterior-posterior tibial force (134 N) at 30° flexion, while recording tibial translation. Ten intact knees were tested to collect baseline data for native specimens. A single knee was selected to test ligament reconstructions using doubled tibialis tendon allografts. All grafts were fixed proximally using an EndoButton™, and the tibial end of the graft was fixed with either a spiked washer or with a suture post placed at two different locations (near and distant) relative to the tibial tunnel.

FINDINGS

Mean first cycle translation for intact knees was 4.8 (sd 1.8) mm; means after reconstruction were 2.6 (sd 0.9) mm (spiked washer), 10.1 (sd 1.9) mm (suture post near), and 10.4 (sd 1.5) mm (suture post distant). Corresponding means for translation increase over 250 cycles were 0.3 (sd 0.2) mm, 3.6 (sd 1.3) mm, 7.2 mm (sd 0.9) mm, and 8.0 (sd 1.3) mm. All mean increases (first cycle and cyclic) after ACL reconstruction were significantly greater than those for the intact knees, and all means with a suture post were significantly greater than those with a spiked washer. There were no significant differences between mean translations for near and distant suture post locations.

INTERPRETATION

Use of suture post fixation for anterior cruciate ligament reconstruction is questioned since increases in anterior tibial translation could lead to excessive post-operative knee laxity and possibly early clinical failure.

Femoral-tibial fixation affects risk of revision and reoperation after anterior cruciate ligament reconstruction using hamstring autograft

PURPOSE

Newer fixation devices for hamstring (HS) autograft have been introduced over the years, yet the impact of these devices on ACLR outcomes requiring surgical intervention remains unclear. We sought to evaluate the risk of aseptic revision and reoperation after HS autograft ACLR according to various femoral-tibial fixation methods.

METHODS

A cohort study was conducted using the Kaiser Permanente ACLR Registry. Primary isolated unilateral ACLR patients who received a HS autograft were identified (2007-2014). Fixation devices were categorized as crosspin, interference, suspensory, or combination (defined as more than one fixation device used on the same side) and femoral-tibial fixation groups used in more than 500 ACLR were evaluated. Cox proportional-hazard regression was used to evaluate the association between femoral-tibial fixation method and outcomes while adjusting for confounders.

RESULTS

6,593 primary ACLR were included. Four femoral-tibial fixation groups had more than 500 ACLR: suspensory-interference (n = 3004, 45.6%), interference-interference (n = 1659, 25.2%), suspensory-combination (n = 1103, 16.7%), and crosspin-interference (n = 827, 12.5%). After adjusting for covariates, revision risk was lower for crosspin-interference (HR = 0.43, 95% CI 0.29-0.65) and interference-interference (HR = 0.63, 95% CI 0.41-0.95) methods compared to the suspensory-interference. In contrast, reoperation risk was higher for crosspin-interference (HR = 2.13, 95% CI 1.37-3.32) and suspensory-combination (HR = 1.68, 95% CI 1.04-2.69) methods compared to suspensory-interference.

CONCLUSIONS

ACLR using HS autograft appears to have the lowest risk of aseptic revision when crosspin or interference fixation is used on the femoral side and is coupled with an interference screw on the tibial side.

LEVEL OF EVIDENCE

III.

Comparison of Clinical and Radiologic Outcomes and Second-Look Arthroscopic Findings After Anterior Cruciate Ligament Reconstruction Using Fixed and Adjustable Loop Cortical Suspension Devices

PURPOSE

To compare clinical and radiological outcomes, including tunnel widening, and to evaluate graft status by second-look arthroscopy after anterior cruciate ligament (ACL) reconstruction using 2 different femoral cortical suspension devices (fixed and adjustable loop).

METHODS

Seventy-nine patients were included for this study. The patients were divided into 2 groups, 41 patients of fixed loop group (EndoButton) and 38 patients of adjustable loop group (TightRope). The Tegner activity, Lysholm knee score, Lachman test, and pivot-shift test were compared between the 2 groups. Anterior stress radiographs and femoral tunnel widening on plain radiographs were also compared. Twenty-seven patients (66%) in the EndoButton group and 21 patients (55%) in the TightRope group underwent the second-look arthroscopy.

RESULTS

At the final follow-up, the mean Tegner activity, Lysholm, and International Knee Documentation Committee scores were improved in both groups and there were no statistically significant differences (5.1 ± 1.6 and 5.5 ± 2.1, P = .312; 90.4 ± 7.8 and 91.0 ± 6.5, P = .525; and 87.4 ± 6.7 and 88.7 ± 5.3, P = .127, respectively). There were no statistical significances in the both groups in terms of Lachman test and pivot-shift tests (P = .392, .559) as well as anterior stress radiographs (mean 3.2 ± 1.4 mm and 2.9 ± 1.1 mm, P = .343). Moreover, radiologic measurements comparing femoral tunnel widening at proximal and distal half also showed no significant differences (P = .540 and .412 on anteroposterior view; P = .254 and .437 on lateral view). In the second-look arthroscopy findings for graft tear and synovial coverage, there were no significant differences (P = .784 and .897).

CONCLUSIONS

Both fixed loop and adjustable loop devices in ACL reconstruction provided good clinical and radiological outcomes. In patients with both devices, femoral tunnel widening at proximal and distal portion have no significant differences after ACL reconstruction. Moreover, second-look arthroscopy revealed no significant differences in terms of synovial coverage and rupture of the graft.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Effectiveness of Reconstruction of the Anterior Cruciate Ligament with Quadrupled Hamstrings and Bone-Patellar Tendon-Bone Autografts

Background

The 2 most frequently used autografts for anterior cruciate ligament reconstruction are the bone-patellar tendon-bone and the quadrupled hamstrings tendon.

Hypothesis

Hamstring tendon graft is superior to patellar tendon graft in restoring tibial rotation during highly demanding activities because of its superiority in strength and linear stiffness and because it is closer morphologically to the anatomy of the natural anterior cruciate ligament.

Study Design

Case control study; Level of evidence, 3.

Methods

Eleven patients with patellar tendon graft anterior cruciate ligament reconstruction, 11 patients with hamstring tendon graft anterior cruciate ligament reconstruction, and 11 controls were assessed. Kinematic data were collected (50 Hz) with a 6-camera optoelectronic system while the subjects descended stairs and, immediately after, pivoted on their landing leg. The dependent variable examined was the tibial internal-external rotation during pivoting. All patients in both groups were also assessed clinically and with the use of a KT-1000 arthrometer to evaluate anterior tibial translation.

Results

The results demonstrated that reconstructions with either graft successfully restored anterior tibial translation. However, both anterior cruciate ligament reconstruction groups had significantly increased tibial rotation when compared with the controls, whereas no differences were found between the 2 reconstructed groups.

Conclusion

The 2 most frequently used autografts for anterior cruciate ligament reconstruction cannot restore tibial rotation to normal levels.

Clinical Relevance

New surgical techniques are needed that can better approximate the actual anatomy and function of the anterior cruciate ligament.

No difference in outcomes between femoral fixation methods with hamstring autograft in anterior cruciate ligament reconstruction - A network meta-analysis

BACKGROUND

There is mixed opinion regarding the optimal femoral fixation method for hamstring tendon autograft in anterior cruciate ligament (ACL) reconstruction. Currently, no study exists showing a superior method of femoral fixation, and thus the topic has remained controversial. The purpose of this study is to network meta-analyze the randomized control trials comparing cortical-button (CB), cross-pin (CP) and interference screws (IS) for femoral fixation with hamstring tendon autograft in ACL reconstruction.

METHODS

The literature review was conducted in accordance with the PRISMA guidelines. Randomized control trials comparing CB, CP and IS were included. Clinical outcomes were compared using a frequentist approach to network meta-analysis, with all statistical analysis performed using R, with a p-value <0.05 being considered statistically significant.

RESULTS

There were 11 studies included comparing; 194 patients with CB to 201 patients with CP (6 studies), 48 patients with CB to 50 patients with IS (1 study), and 172 patients with CP to 162 patients with IS (5 studies). One study compared all three groups, including 48 patients with CB, 50 patients with IS, and 52 with CP. There was a mean follow-up time of 26.4 months. No statistically significant difference was found between the fixation methods when evaluating knee stability, functional outcomes, graft failures, or revision procedures.

CONCLUSION

Using a network meta-analysis, our study found that, there was no difference in failure rate, knee stability, functional outcomes or incidence of revision procedures between CB, CP or IS femoral fixation techniques of hamstring tendon autografts in ACL reconstruction.

LEVEL OF EVIDENCE

Level I, network meta-analysis of Level I studies.

Excellent bone plug–socket integration at 8 weeks after anterior cruciate ligament reconstruction using an adjustable-length loop cortical fixation device

Objectives

Recently, adjustable-length loop cortical fixation devices (ALCFDs) have been developed. However, they are not frequently used for bone–patellar tendon–bone (BTB) grafting, mainly because it is uncertain whether an ALCFD enables sufficient integration of the bone plug. Thus, the purpose of this study was to evaluate bone plug–socket integration in anterior cruciate ligament reconstruction (ACL-R) with an ALCFD.

Methods

Twenty consecutive patients with a mean age of 25±10 years underwent primary anatomic rectangular tunnel (ART) ACL-R with a BTB graft using BTB TightRope. The operated knees were evaluated by CT at 4 weeks and 8 weeks postoperatively. Union between the bone plug and the socket wall were assessed on 30 evaluation planes. No border between the plug and the socket wall, or trabecular continuity, were defined as complete union and a visible gap of >1 mm as incomplete union. When complete union was observed on >20, 11–20, 5–10 or <5 of the evaluation planes, bone integration was graded as excellent, good, fair or poor, respectively. In addition, the interface area between the plug and the socket wall was assessed by CT value index. Clinical evaluation was performed at 2 years postoperatively using the International Knee Documentation Committee (IKDC) form.

Results

The proportion of patients with excellent bone integration was 20% at 4 weeks and 85% at 8 weeks, showing a significant difference (p=0.00015). Moreover, the CT value index of the interface area at 4 weeks was 25.8%±11.8% and that at 8 weeks was 15.3%±9.0%, again showing a significant difference (p=0.005). These suggest that bone integration of the interface area progresses over time and adequate at 8 weeks. Clinically, all 16 patients examined directly were rated their knees as normal or nearly normal with a mean side-to-side difference in anterior laxity at manual maximum force by KT-2000 of 0.2±0.3 mm.

Conclusion

Excellent bone plug–socket integration was observed at 8 weeks after ART ACL-R using an ALCFD with satisfactory clinical results. An ALCFD could be safely applied for ART ACL-R.

Level of evidence

4 (case series).

Arthroscopic ACL reconstruction using fixed suspensory device versus adjustable suspensory device for femoral side graft fixation: What are the outcomes?

INTRODUCTION

The aim of the study was to evaluate the outcomes of Arthroscopic ACL Reconstruction using Fixed suspensory device and Adjustable suspensory device for femoral side graft fixation.

MATERIAL AND METHODS

We conducted a prospective study of sixty two patients with ACL deficient knees treated with arthroscopic ACL reconstruction. Consecutively patients were operated with fixed loop and adjustable loop suspensory devices for femoral side graft fixation and no randomization was done.

RESULTS

Functional assessment was performed with VAS score, IKDC score and Lyshom score before and after surgery with ACL reconstruction. The postoperative Lyshom score in fixed loop group and adjustable loop group was 94.23 and 94.32 respectively. The IKDC score in fixed group and adjustable group was 92.03 and 92.16 respectively. VAS in fixed loop group improved from score of 5-3, while in adjustable loop group from score of 4-3. There was significant improvement in stability of knee assessed by Lachman's test, anterior drawer test, and Pivot shiff's test and both methods of fixation provide stability to knee. The complications included; restriction of terminal flexion in 12 patients: 6 in each group. There was no implant breakage in both groups.

CONCLUSION

Arthroscopic ACL reconstruction using fixed loop and adjustable loop suspensory devices are equally effective fixation methods.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level Ⅳ, therapeutic case series.

Improvement of bone-tendon fixation by porous titanium interference screw: A rabbit animal model

The interference screw is a widely used fixation device in the anterior cruciate ligament (ACL) reconstruction surgeries. Despite the generally satisfactory results, problems of using interference screws were reported. By using additive manufacturing (AM) technology, we developed an innovative titanium alloy (Ti₆ Al₄ V) interference screw with rough surface and inter-connected porous structure designs to improve the bone-tendon fixation. An innovative Ti₆ Al₄ V interference screws were manufactured by AM technology. In vitro mechanical tests were performed to validate its mechanical properties. Twenty-seven New Zealand white rabbits were randomly divided into control and AM screw groups for biomechanical analyses and histological analysis at 4, 8, and 12 weeks postoperatively; while micro-CT analysis was performed at 12 weeks postoperatively. The biomechanical tests showed that the ultimate failure load in the AM interference screw group was significantly higher than that in the control group at all tested periods. These results were also compatible with the findings of micro-CT and histological analyses. In micro-CT analysis, the bone-screw gap was larger in the control group; while for the additive manufactured screw, the screw and bone growth was in close contact. In histological study, the bone-screw gaps were wider in the control group and were almost invisible in the AM screw group. The innovative AM interference screws with surface roughness and inter-connected porous architectures demonstrated better bone-tendon-implant integration, and resulted in stronger biomechanical characteristics when compared to traditional screws. These advantages can be transferred to future interference screw designs to improve their clinical performance. The AM interference screw could improve graft fixation and eventually result in better biomechanical performance of the bone-tendon-screw construct. The innovative AM interference screws can be transferred to future interference screw designs to improve the performance of implants. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2633-2640, 2018.