Femoral Graft Fixation Research Articles

Lateral femoral tunnel preparation and graft fixation for anterior cruciate ligament reconstruction-A discussion.

This article provides a discussion and commentary around the recent advances in arthroscopic anterior cruciate ligament reconstruction (ACLR), with a focus on the aspects of lateral femoral tunnel preparation and graft fixation techniques. The paper explores and comments on a recently published review by Dai et al, titled "Research progress on preparation of lateral femoral tunnel and graft fixation in ACLR", while providing insight into its relevance within the field of ACLR, and recommendations for future research.

Satisfactory 5-year functional outcomes following primary ACL reconstructions from the UK National Ligament Registry.

The aim of this study was to describe the 10-year findings from the UK National Ligament Registry (NLR). A retrospective review was performed for prospectively collected data on the NLR between January 2013 and December 2022. All patients who underwent primary ACL reconstruction (ACLR) on the registry were included. Surgical characteristics were analysed, including surgeon grade and case volume, concomitant knee procedures, venous thromboembolic prophylaxis, graft characteristics, femoral and tibial tunnel drilling, and fixation methods. Clinical outcomes were collected preoperatively and at 6 months, 1 year, 2 yearsand 5 years following the index procedure. During the study period, 17,492 unilateral ACLR procedures were recorded. Autograft was used in 98%, most commonly a combined semitendinosus and gracilis graft (77%) or patella tendon graft (31%). Allograft was used in only 1% of the patients. In 52% of cases, ACLR was associated with an additional procedure, with isolated medial meniscal surgery being the most common (21%). Femoral tunnel drilling was mostly performed through an anteromedial portal (73%) and tibial tunnel drilling using an outside-in technique (92%). The most common method of femoral graft fixation was with an Endobutton fixed loop suspensory device (77%), while interference screws predominated for tibial tunnel fixation (86%). Patients who underwent ACLR surgery showed significant improvement in their functional outcome scores at six months, 1 year, 2 yearsand 5 years postoperatively. Data from the NLR shows a detailed description of the current trends and evolution of ACLR in the United Kingdom over the last 10 years. Satisfactory functional outcomes were observed 5 years postoperatively. This study provides useful information on the prevalence of ACL-associated injuries and current surgical techniques with the aim of improving the quality of clinical care and patients' outcomes. Moreover, it provides surgeons with a benchmark against which to compare current practices and functional outcomes following ACLR across the United Kingdom. Level III.

PEEK Interference Screws Show Significant Tunnel Enlargement After ACL Reconstruction and is Comparable to Adjustable-Length Loop Cortical Button Fixation

BackgroundIt is unclear whether the use of polyetheretherketone (PEEK) interference screws for anterior cruciate ligament (ACL) reconstruction leads to postoperative tunnel enlargement. Femoral tunnel enlargement was further compared with adjustable-length loop cortical fixation.MethodsEighteen patients with ACL reconstruction using hamstring grafts were retrospectively divided into two groups. Eleven patients were treated with the ACL reconstruction technique using a PEEK interference screw for femoral graft fixation. Seven patients received adjustable-length loop cortical buttons for femoral fixation. Tibial ACL graft fixation was performed using PEEK interference screws. Tunnel volume changes were assessed using computed tomography (CT) scans performed after surgery (100%) and after 1 year. The maximal tunnel diameter was measured.ResultsThe group with femoral screw fixation showed a mean tunnel volume change of 108.15 ± 13.7% on the tibial side and 124.07 ± 25.38% on the femoral side. The group with femoral button fixation showed a tunnel volume change of 111.12 ± 12.72% on the tibial side and 130.96 ± 21.71% on the femoral side. The differences in femoral tunnel volume changes were not significant (P = 0.562). Femoral tunnels with PEEK screw fixation showed significantly larger diameter after 12 months in comparison with button fixation (13.02 ± 1.43 mm vs. 10.46 ± 1.29 mm, P < 0.001).ConclusionsPEEK interference screws were associated with significant tibial and femoral tunnel enlargement. Femoral tunnel enlargement was comparable between PEEK interference screws and button fixation. Final femoral tunnel diameter was significantly larger with PEEK screw fixation in comparison to button fixation.

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

Little is known about the stability of adjustable-loop devices (ALDs) for anterior cruciate ligament (ACL) reconstruction (ACLR). To evaluate the stabilization behavior of 3 different types of ALDs for all-inside ACLR in a full-construct surgical technique-based manner. Controlled laboratory study. 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. 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. 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. A detailed biomechanical understanding of the stabilization potential is pertinent to the continued evolution of ALDs to improve clinical outcomes.

Femoral Physeal-Sparing ACL Reconstruction With Iliotibial Band Autograft Over-the-Top With Associated Lateral Extra-Articular Tenodesis

Background: Injuries to the anterior cruciate ligament (ACL) in the pediatric population have been exponentially increasing over the years. However, surgical techniques typically employed for ACL reconstruction (ACL-R) in adults may injure the physes of skeletally immature patients, resulting in growth disturbances. Indications: Currently, ACL-R is recommended for most patients, aiming to return the patient to their previous activities as well as reduce the risk of further instability, meniscal and chondral injuries, and early osteoarthritis. Pediatric ACL-R techniques may vary widely. In this video, the technique chosen was over-the-top on the femur with a vertical tibial tunnel, in addition to a lateral extra-articular tenodesis, using the iliotibial (IT) band as the graft. Technique Description: The patient is positioned in standard supine arthroscopic position. An incision is made over the lateral epicondyle and the IT band is exposed. A 2-cm-wide graft is harvested. The proximal aspect of the graft is truncated as high as possible, and the distal aspect is left attached to Gerdy tubercle. Arthroscopic portals are established, and the remanent ACL is debrided, exposing the posterior aspect of the lateral femoral condyle. The capsule is penetrated using a Schnidt tonsil to establish the over-the-top position, which is subsequently exchanged for a cardiac clamp. The graft sutures are grasped using the clamp and pulled into the joint. The tibial tunnel is drilled at the anatomic footprint of the ACL. The graft is threaded over-the-top of the lateral femoral condyle and through the tibial tunnel. Finally, femoral graft fixation is performed on the lateral femoral condyle using interrupted sutures through the IT band and periosteum, and tibial graft fixation is performed with standard interference fixation. Results: Previous literature shows low re-rupture rates, excellent postoperative patient-reported outcomes, and high return to sport rates. Conclusion: In the pediatric population, there is still no ACL-R technique defined as the gold standard. The described technique is a valuable option for ACL-R in skeletally immature patients, with low revision rates and excellent postoperative outcomes. In addition, this technique minimizes the risk of growth disturbances and effectively stabilizes the knee, allowing patients to return to previous activities. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Combined Reconstruction of the Medial Patellofemoral Ligament and Medial Quadriceps Tendon Femoral Ligament in Skeletally Immature Patients

The medial patellofemoral ligament (MPFL) reconstruction is challenging in skeletally immature patients due to the anatomical particularities at this age. Recently, the medial quadriceps tendon femoral ligament (MQTFL) has received great interest for its ability to restrain the patella’s instability along with MPFL. No gold-standard technique has been described so far to reconstruct both MPFL and MQTFL in skeletally immature patients. We present a technique to safely reconstruct the MPFL and the MQTFL in children and adolescents. The gracilis tendon autograft is harvested and passed through the medial collateral ligament as a pulley. The free ends of the graft are passed through the patella by an “L-shaped tunnel” and tied to itself. The other free end of the graft is pulled through the medial third of the quadriceps tendon and tied to itself to achieve tension. Our technique is reproducible, implant-free and avoids complications associated with femoral drilling and graft fixation. However no long-term follow-up results are available.

Evaluation of the Optimal Femoral Fixation Site for Medial Patellofemoral Ligament Reconstruction in the Skeletally Immature Patient.

The aim of this study was to assess which femoral fixation site, distal to the physis, most closely emulates the native medial patellofemoral ligament (nMPFL) length relationship in the pediatric knee. Lateral knee radiographs were taken incrementally, from 0° to 120° of flexion. The femoral origin of the nMPFL and 3 other MPFL femoral fixation sites distal to the physis were identified (P1, 1 cm distal to physis along the posterior femoral cortex; P2, 2 cm distal to physis along the posterior femoral cortex; P3, 1 cm distal and 1 cm anterior). Virtual MPFL lengths were measured from all sites. Measurement reliability was assessed using intraclass correlation coefficients. Primary comparison between simulated MPFL length at native and femoral fixation sites was made using a repeated measures analysis of variance at 30° flexion. Bivariate Pearson correlation was used to assess the relationship between fixation sites and nMPFL through the range of motion (alpha=0.05). The intra-class correlation coefficient for intraobserver reliability of MPFL length measurement was excellent. Analysis of variance showed virtual MPFL lengths from proposed femoral fixation sites at 30° were significantly different from nMPFL length (P<.01). The P1 MPFL had the least difference in means compared with nMPFL (-2.6±1.8 mm). Correlational analysis showed that P1 MPFL had the closest relationship with nMPFL compared with other femoral fixation sites (R=0.91, P<.01). The P1 MPFL had the length change most comparable to that of nMPFL (23.9±3.1 mm vs 13.3±2.85 mm) compared with the other simulated MPFLs. Femoral graft fixation site 1 cm distal to the physis in the lateral view along the posterior femoral cortex closely represents the length relationship of the nMPFL. [Orthopedics. 2023;46(2):108-113.].

Biomechanical effects of cross-pin's diameter in reconstruction of anterior cruciate ligament – A specific case study via finite element analysis

For anterior cruciate ligament reconstruction (ACL-R), one of the crucial aspects of treatment is the fixator selection that could provide initial graft fixation post-operatively. Literature on biomechanical stabilities of different sizes of fixators as femoral graft fixation is limited. Therefore, this study aims to analyse the influence of different diameters of cross-pins on the stability of graft fixations after ACL-R via finite element analysis (FEA). In the methodology, three-dimensional (3D) models of three different diameters of cross-pins were developed, of which anterior tibial loads (ATL) were applied onto the tibia. From the findings, the cross-pin with a smaller diameter (4 mm) provided optimum stability than larger diameter cross-pins, whereby it demonstrated acceptable stresses at the fixators (both cross-pin and interference screw) with a different percentage of 28%, while the stresses at the corresponding bones were favourable for osseointegration to occur. Besides, the strains of the knee joint with 4 mm diameter cross-pin were also superior in providing a good biomechanical environment for bone healing, while the recorded strain values at fixators were comparable with a larger diameter of cross-pins without being inferior in terms of deformation. To conclude, the cross-pin with 4 mm diameter depicted the best biomechanical aspects in graft fixation for ACL-R since it allows better assistance for the osseointegration process and can minimise the possibility of the breakage and migration of fixators. This study is not only useful for medical surgeons to justify their choices of pin diameter to treat patients, but also for researchers to conduct future studies.

A Comparative Study on Functional Outcomes of Fixed Versus Adjustable Length-Loop Device for Femoral Fixation of Graft in Anterior Cruciate Ligament Reconstruction

A Comparative Study on Functional Outcomes of Fixed Versus Adjustable Length-Loop Device for Femoral Fixation of Graft in Anterior Cruciate Ligament Reconstruction

A prospective randomized study of arthroscopic ACL reconstruction with adjustable- versus fixed-loop device for femoral side fixation

PurposeSuspensory devices are extensively used in the management of anterior cruciate ligament (ACL) tear. They include fixed- and adjustable-loop devices. There are only a few studies comparing the efficacy of these two devices in the available literature. Therefore, the aim of this study is to compare clinical outcomes between the adjustable-loop device (group I) and fixed-loop device (group II).Materials and methodsThis was a prospective randomized study. Both groups were equivalent in demographic, preoperative, and intraoperative variables. Twenty-three patients underwent femoral side graft fixation with adjustable-loop and 20 with fixed-loop devices. Four patients were lost to follow-up. Assessment of clinical outcome was done with International Knee Documentation Committee (IKDC) score, Lysholm score, and knee stability tests (Lachman test and pivot shift test). Patient evaluation was performed preoperatively and finally postoperatively 2 years after surgery.ResultsPostoperative IKDC scores of group I and II were 91.9 ± 3.6 and 91.5 ± 3.6, respectively, and Lysholm scores were 91.0 ± 3.6 and 91.4 ± 3.5, respectively, after 2 years; however, the difference in the outcomes was statistically insignificant (p > 0.05). Twenty patients (87%) in group I and 17 patients (85%) in group II had a negative Lachman test (p = 0.8). Twenty-two patients (95.7%) in group I and 19 patients (95%) in group II had a negative pivot shift test (p = 0.9).ConclusionACL reconstruction with fixed- and adjustable-loop suspensory devices for graft fixation gives equivalent and satisfactory clinical results.Level of evidence1.

Anterior cruciate ligament graft forces are sensitive to fixation angle and tunnel position within the native femoral footprint during passive flexion

BackgroundAnterior cruciate ligament (ACL) graft position within the anatomic femoral footprint of the native ACL and the flexion angle at which the graft is fixed (i.e., fixation angle) are important considerations in ACL reconstruction surgery. However, their combined effect on ACL graft force remains less well understood. HypothesisDuring passive flexion, grafts placed high within the femoral footprint carry lower forces than grafts placed low within the femoral footprint (i.e., high and low grafts, respectively). Forces carried by high grafts are independent of fixation angle. All reconstructions impart higher forces on the graft than those carried by the native ACL. Study DesignControlled laboratory study. MethodsFive fresh-frozen cadaveric knees were mounted to a robotic manipulator and flexed from full extension to 90° of flexion. The ACL was sectioned and ACL force was calculated via superposition. ACL reconstructions were then performed using a patellar tendon autograft. For each knee, four different reconstruction permutations were tested: high and low femoral graft positions fixed at 15° and at 30° of flexion. Graft forces were calculated from full extension to 90° of flexion for each combination of femoral graft position and fixation angle again via superposition. Native ACL and ACL graft forces were compared through early flexion (by averaging tissue force from 0 to 30° of flexion) and in 5° increments from full extension to 90° of flexion. ResultsWhen fixed at 30° of flexion, high grafts carried less force than low grafts through early flexion bearing a respective 64 ± 19 N and 88 ± 11 N (p = 0.02). Increasing fixation angle from 15° to 30° caused graft forces through early flexion to increase 40 ± 13 N in low grafts and 23 ± 6 N in high grafts (p < 0.001). Low grafts fixed at 30° of flexion differed most from the native ACL, carrying 67 ± 9 N more force through early flexion (p < 0.001). ConclusionACL grafts placed high within the femoral footprint and fixed at a lower flexion angle carried less force through passive flexion compared to grafts placed lower within the femoral footprint and fixed at a higher flexion angle. At the prescribed pretensions, all grafts carried higher forces than the native ACL through passive flexion. Clinical RelevanceBoth fixation angle and femoral graft location within the anatomic ACL footprint influence graft forces and, therefore, should be considered when performing ACL reconstruction.

Novel press-fit technique of patellar bone plug in anterior cruciate ligament reconstruction is comparable to interference screw fixation.

Conventional press-fit technique for anterior cruciate ligament reconstruction (ACLR) is performed with extraction drilling of the femoral bone tunnel and manual shaping of the patellar bone plug. However, the disadvantages of this technique include variation in bone plug size and, thus, the strength of the press-fit fixation, bone loss with debris distribution within the knee joint, potential heat necrosis, and metal wear debris due to abrasion of the guide wire. To overcome these disadvantages, a novel technique involving punching of the femoral bone tunnel and standardized compression of the bone plug was introduced. In this study, the fixation strength and apparent stiffness were tested and compared to that of the gold-standard interference screw fixation technique in three flexion angle configurations (0°/45°/90°) in a porcine model. We hypothesized that the newly developed standardized press fit fixation would not be inferior to the gold standard method. Sixty skeletally mature porcine knees (30 pairs) were used. Full-thickness central third patellar tendon strips were harvested, including a patellar bone cylinder of 9.5mm in diameter. The specimens were randomly assigned to 10 pairs per loading angle (0°, 45°, 90°). One side of each pair was prepared with the press-fit technique, and the contra-lateral side was prepared with interference screw fixation. Equivalent numbers of left- and right-sided samples were used for both fixation systems. A three-way multifactor ANOVA was carried out to check for the influence of (a) fixation type, (b) flexion angle, and (c) side of the bone pair. The primary fixation strength of femoral press-fit graft fixation with punched tunnels and standardized bone plug compression did not differ significantly from that of interference screw fixation (p = 0.51), which had mean loads to failure of 422.4 ± 134.6N and 445.4 ± 135.8N, respectively. The flexion angle had a significant influence on the maximal load to failure (p = 0.01). Load values were highest in 45° flexion for both fixations. The anatomical side R/L was not a statistically significant factor (p = 0.79). The primary fixation strength of femoral press-fit graft fixation with punched femoral tunnels and standardized bone plug compression is equivalent to that of interference screw fixation in a porcine model. Therefore, the procedure represents an effective method for ACL reconstruction with patellar or quadriceps tendon autografts including a patellar bone plug.

Effect of Surgical Design Variations on the Knee Contact Behavior during Anterior Cruciate Ligament Reconstruction.

In this study, we aimed to develop an in-silico synthesis of the effect of critical surgical design parameters on articular contact behavior for a bone-patellar-tendon-bone anterior cruciate ligament reconstruction (ACL-R) surgery. A previously developed finite element model of the knee joint consisting of all relevant soft tissues was employed. The knee model was further updated with additional features to develop the parametric FE model of the biomechanical experiments that depicted the ACL-R surgery. The parametricity was created involving femoral tunnel architecture (orientations and locations) and graft fixation characteristics (pretension and angle of fixation). A global sensitivity analysis based on variance decomposition was used to investigate the contribution of the surgical parameters to the uncertainty in response to the ACL-R joint. Our examinations indicated that the total contact force was primarily influenced by either combined or individual action of the graft pretension and fixation angle, with a modest contribution of the graft insertion sites. The joint contact center and area were affected mainly by the angle of fixation and the tunnel placements. Graft pretension played the dominant role in the maximum contact pressure variability, an observation that has been well-documented in the literature. Interestingly, the joint contact behavior was almost insensitive to the tunnel's coronal and sagittal orientations. Our data provide an evaluation of how the surgical parameters affect the knee joint's contact behavior after ACL-R and may provide additional information to better explain the occurrence of osteoarthritis as an aftermath of such surgery.

Anatomical rectangular tunnel anterior cruciate ligament reconstruction provides excellent clinical outcomes.

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. 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 2years 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®. 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 ± 10months (range 24-68months). 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 ± 0.7mm (range - 1-4mm). 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 2years 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. III.

Confirming Proper Button Deployment of Suspensory Fixation During ACL Reconstruction.

Background:Suspensory fixation of anterior cruciate ligament (ACL) reconstruction (ACLR) grafts has emerged as a popular device for femoral graft fixation. However, improper deployment of the suspensory fixation can compromise proper graft tensioning, leading to failure and revision. Also, soft tissue interposition between the button and bone has been associated with graft migration and pain, occasionally requiring revision surgery. Many surgeons rely on manual testing and application of distal tension to the graft to confirm proper button deployment on the lateral cortex of the femur for ACL graft fixation.Purpose:To determine the reliability of the manual resistance maneuver when applying distal tension to deploy the suspensory device along the lateral cortex of the femur.Study Design:Case series; Level of evidence, 4.Methods:All patients undergoing ACLR with a suture button suspensory device for femoral fixation were eligible for enrollment in the study. The surgeries were performed by 3 board-certified, sports medicine fellowship–trained orthopaedic surgeons at a single outpatient surgical center between May 2018 and June 2019. All grafts were passed in a retrograde manner into the femoral tunnel, and a vigorous manual tensioning maneuver in a distal direction was placed on the graft to deploy and secure along the lateral cortex of the femur. Intraoperative mini c-arm fluoroscopy was obtained to demonstrate proper suture button positioning. If interposing tissue or an improperly flipped button was identified, rectifying steps were undertaken and recorded.Results:A total of 51 patients with a mean age of 33.3 years were included in the study. Of these patients, 74.5% had normal suture button positioning identified via intraoperative fluoroscopic imaging, while 15.7% had interposed soft tissue and 9.8% had an improperly flipped button. In all cases, the surgeon was able to rectify the malpositioning intraoperatively.Conclusion:Despite the manual sensation of proper suspensory button positioning, intraoperative fluoroscopy identified suture button deployment errors in ACLR 25% of the time. Correcting the malpositioning is not technically demanding. These findings advocate for routine intraoperative surveillance to confirm appropriate suture button seating during ACLR.

Anchor-Based Femoral Fixation for Physeal-Sparing Medial Patellofemoral Ligament Reconstruction: A Time-Zero Biomechanical Comparison With Tenodesis Screw Fixation

Background: Open physes and trochlear/notch geometries in pediatric patients limit the safe corridor for femoral interference screw graft fixation during medial patellofemoral ligament (MPFL) reconstruction. Accordingly, interest is increasing in anchor-based fixation, but biomechanical validation is deficient. Purpose: To compare anchor-based and tenodesis screw femoral fixation of MPFL grafts in a time-zero biomechanical model. Study Design: Controlled laboratory study. Methods: Twenty-seven fresh-frozen porcine distal femurs were potted for testing in an electromechanical load frame, while bovine tendons were used for MPFL grafts. Reconstructions were performed with 1 of 3 femoral fixation strategies: 4.5-mm biocomposite double-loaded threaded anchor (DLA group), 3.9-mm biocomposite knotless threaded anchor (KA group), or traditional 7 × 23–mm biocomposite tenodesis screw (TS group). For testing, femoral specimens were oriented and secured in the mechanical testing apparatus such that actuator tensile pull re-created the normal MPFL trajectory. Specimens underwent 10 cycles of 5- to 15-N loading at 1-Hz preconditioning, followed by 1000 cycles of 10- to 50 N-loading at 1 Hz. After cyclic loading, all specimens were loaded to failure at 305 mm/min. The average cyclic construct stiffness, displacement, and load-to-failure data between the 3 groups were compared using analysis of variance (ANOVA) with the significance level set at P < .05. Results: Average cyclic construct stiffnesses were comparable across groups per repeated-measures ANOVA analysis: 68.3 ± 6.3, 71.4 ± 6.4, and 74.3 ± 7.9 N/mm for TS, DLA, and KA groups, respectively (at cycle 1000). Average construct displacements at cycles 100 and 1000 were significantly less in the anchor versus tenodesis screw groups per ANOVA and Tukey post hoc analysis: 7.7 ± 4.2 mm for the TS group versus 3.7 ± 0.4 and 4.3 ± 0.6 mm for the DLA and KA groups, respectively (at cycle 1000). There was no significant difference in ultimate failure loads between the anchor and tenodesis screw groups, but 3 of 9 TS constructs failed at loads below the average failure load of the native MPFL. Conclusion: Compared with the tenodesis group, anchor-based fixation produced constructs with equivalent cyclic stiffnesses, improved load-displacement characteristics, and had less failure load variability in the porcine cadaveric model. Clinical Relevance: Femoral fixation of the MPFL graft with a single anchor (4.5 or 3.9 mm threaded) is a viable alternative to traditional tenodesis screw fixation.

Physeal-Sparing Medial Patellofemoral Ligament Reconstruction With Suture Anchor for Femoral Graft Fixation

Patellar instability is a common problem in the active pediatric population. When nonoperative treatment of the instability fails, growth-respecting surgical stabilization techniques are required. As the incidence of medial patellofemoral ligament (MPFL) reconstruction has increased, techniques have improved to avoid physeal injury to the distal femur. These techniques are technically demanding because of the small size of the distal femoral epiphysis in children, as well as the relatively large socket size (7-8 mm in diameter, >20 mm in length) required for sound fixation with a tenodesis screw as originally described. The size of the femoral tunnel for interference fixation puts the surrounding structures at risk of damage. We present a modification of the epiphyseal socket technique for anatomic growth-sparing MPFL reconstruction using a small soft anchor for femoral graft fixation. This has the proposed advantages of diminishing volumetric bony removal from the epiphysis; increasing the margin of safety with respect to notch, trochlear, and/or physeal damage; and reducing the risk of thermal damage to the physis during socket reaming. This technique is technically simple and can be easily learned by surgeons familiar with adult MPFL reconstruction techniques.

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

To compare the efficacy and safety of individual devices for femoral and/or tibial graft fixation in anterior cruciate ligament (ACL) reconstruction. 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. 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%). 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 II, meta-analysis of Level I and II studies.

The interposition of soft tissue between the cortical button and femoral lateral cortex significantly increases button migration but does not negatively affect knee stability and clinical outcome

BackgroundIn clinical practice, soft tissue interposition may occur during femoral graft fixation. Soft tissue interposition between the lateral femoral cortex and the cortical button may affect graft tension and related longitudinal graft motion in the tunnel. We aimed to investigate the effect of soft tissue interposition on button migration and clinical outcomes in anatomical single-bundle anterior cruciate ligament reconstruction. MethodsEighty-four patients aged 18–40 years, who underwent anatomical single-bundle anterior cruciate ligament reconstruction with quadruple hamstring autograft were included. Patients were divided into two groups as Group 1 (n = 32) with soft tissue interposition between the cortical button and cortex, and Group 2 (n = 52) without soft tissue interposition. At the one-year follow-up visit, the anteroposterior knee stability of the patients was evaluated using the Lachman test and KT-2000 arthrometer, and rotational stability was assessed with the pivot shift test. The Lysholm knee score was used to evaluate the functional outcome of the patients. Relationship between tissue interposition and clinical outcome, and button migration was examined. ResultsButton migration was observed in 12 patients in Group 1 (37.5%) and two patients (3.84%) in Group 2 (p < 0.001). However, no significant difference was observed between patients with and without tissue interposition or those with and without button migration regarding knee stability parameters and clinical outcome (p < 0.05). ConclusionsPostoperative tissue interposition is found to be associated with cortical button migration during the follow-up. However, it does not affect the clinical outcome.

A novel approach for optimal graft positioning and tensioning in anterior cruciate ligament reconstructive surgery based on the finite element modeling technique

BackgroundIn ACL-reconstructed patients the postoperative knee biomechanics may differ from the intact knee biomechanical behavior which can alter knee kinematics and kinetics, and as a result lead to the progression of knee osteoarthritis. The aim of this study was to demonstrate the potential of finite element models to define the optimal choices in surgical parameters in terms of optimal graft positioning in combination with graft type in order to restore the kinematic and kinetic behavior of the knee as best as possible. MethodsA workflow was proposed based on cadaveric experiments in order to restore the injured knee to a near normal physiological condition. Femoral and tibial graft insertion sites and graft fixation tension were optimized to obtain similar intact knee laxity, for three common single-bundle and one double-bundle reconstructions. To verify the success of the surgery with the variables calculated using the proposed workflow, a full walking cycle was simulated with the intact, ACL-ruptured, optimal ACL-reconstructed and non-optimal reconstructed knees. ResultsOur results suggested that for patellar tendon and hamstring tendon grafts, anatomical positioning (fixation force: 40 N), and for quadriceps tendon graft, isometric positioning (fixation tension: 85 N) could recover the intact joint kinematics and kinetics. Also for double-bundle reconstruction, with the numerically calculated optimal insertion sites, both bundles needed 50-N fixation force. ConclusionsWith optimal graft positioning parameters, following the proposed workflow in this study, any of the single-bundle graft types and surgical techniques (single vs. double-bundle) may be used to acceptably recover the intact knee joint biomechanical behavior.