Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction

Tailoring the pore design of embroidered structures by melt electrowriting to enhance the cell alignment in scaffold-based tendon reconstruction

Tissue engineering of ligaments and tendons aims to reproduce the complex and hierarchical tissue structure while meeting the biomechanical and biological requirements. For the first time, the additive manufacturing methods of embroidery technology and melt electrowriting (MEW) were combined to mimic these properties closely. The mechanical benefits of embroidered structures were paired with a superficial micro-scale structure to provide a guide pattern for directional cell growth. An evaluation of several previously reported MEW fiber architectures was performed. The designs with the highest cell orientation of primary dermal fibroblasts were then applied to embroidery structures and subsequently evaluated using human adipose-derived stem cells (AT-MSC). The addition of MEW fibers resulted in the formation of a mechanically robust layer on the embroidered scaffolds, leading to composite structures with mechanical properties comparable to those of the anterior cruciate ligament. Furthermore, the combination of embroidered and MEW structures supports a higher cell orientation of AT-MSC compared to embroidered structures alone. Collagen coating further promoted cell attachment. Thus, these investigations provide a sound basis for the fabrication of heterogeneous and hierarchical synthetic tendon and ligament substitutes.

Comparison of failure rates and functional outcomes between hamstring autografts and hybrid grafts in anterior cruciate ligament reconstruction: A systematic review and meta-analysis

BACKGROUND

The viability of augmenting small-diameter hamstring autografts with allografts remains unclear. Recent studies have reported different clinical results after allograft augmentation. Hence, we sought to determine whether hamstring autografts and hybrid grafts differed in terms of failure rates and functional outcomes after anterior cruciate ligament (ACL) reconstruction. We also evaluated whether the results of the comparisons differed based on allograft sterilization methods.

PATIENTS AND METHODS

This systematic review and meta-analysis were performed by searching the PubMed, Cochrane Library, and EMBASE databases to identify prospective or retrospective studies (evidence levels 1, 2, or 3) that compared the failure rates and functional outcomes of ACL reconstruction using autografts and hybrid grafts.

RESULTS

We identified 15 relevant studies, including 1,521 patients, with 798 and 723 treated using autografts and hybrid grafts, respectively. Fourteen studies were retrospective comparative studies, and one was a prospective randomized controlled trial. Of these, three studies used non-irradiated allografts. In the analysis of all participants, no significant differences in failure rates and subjective International Knee Documentation Committee (IKDC) scores were observed between the autograft and hybrid graft groups. Comparing the autograft and hybrid graft groups that used non-irradiated allografts, no differences in the failure rates and subjective IKDC scores were also noted. Meanwhile, in the groups that used irradiated allograft, the autograft group demonstrated higher Lysholm knee scores and reduced anterior laxity than the hybrid graft group.

DISCUSSION

Overall, ACL reconstruction using hybrid grafts may not reduce failure rates compared to reconstructions using hamstring autografts, although hybrid grafts with irradiation may decrease functional outcomes.

LEVEL OF EVIDENCE

III; systematic review of level II and III studies.

Knee instability caused by altered graft mechanical properties after anterior cruciate ligament reconstruction: the early onset of osteoarthritis?

Anterior cruciate ligament (ACL) rupture is a very common knee joint injury. Torn ACLs are currently reconstructed using tendon autografts. However, half of the patients develop osteoarthritis (OA) within 10 to 14 years postoperatively. Proposedly, this is caused by altered knee kine(ma)tics originating from changes in graft mechanical properties during the in vivo remodeling response. Therefore, the main aim was to use subject-specific finite element knee models and investigate the influence of decreasing graft stiffness and/or increasing graft laxity on knee kine(ma)tics and cartilage loading. In this research, 4 subject-specific knee geometries were used, and the material properties of the ACL were altered to either match currently used grafts or mimic in vivo graft remodeling, i.e., decreasing graft stiffness and/or increasing graft laxity. The results confirm that the in vivo graft remodeling process increases the knee range of motion, up to >300 percent, and relocates the cartilage contact pressures, up to 4.3 mm. The effect of remodeling-induced graft mechanical properties on knee stability exceeded that of graft mechanical properties at the time of surgery. This indicates that altered mechanical properties of ACL grafts, caused by in vivo remodeling, can initiate the early onset of osteoarthritis, as observed in many patients clinically.

Acute Bone Loss and Infrapatellar Fat Pad Fibrosis in the Knee After an In Vivo ACL Injury in Adolescent Mice

BACKGROUND

Young patients are 6 times more likely than adults to have a primary anterior cruciate ligament (ACL) graft failure. Biological factors (ie, tunnel osteolysis) may account for up to a third of these failures. Previous evaluations of patient ACL explants indicated significant bone loss within the entheseal regions. However, it remains unknown if the degree of bone loss within the ACL insertion regions, wherein ACL grafts are fixated, exceeds that of the femoral and tibial condylar bone.

HYPOTHESIS

Bone loss in the mineralized matrices of the femoral and tibial ACL entheses is distinct from that clinically reported across the whole knee after injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

We developed a clinically relevant in vivo mouse ACL injury model to cross-sectionally track the morphological and physiological postinjury changes within the ACL, femoral and tibial entheses, synovial joint space, and load-bearing epiphyseal cortical and trabecular bone components of the knee joint. Right ACLs of 10-week-old C57BL/6J female mice (N = 75) were injured in vivo with the contralateral ACLs serving as controls. Mice were euthanized at 1, 3, 7, 14, or 28 days after injury (n = 12/cohort). Downstream analyses included volumetric cortical and trabecular bone analyses and histopathologic assessments of the knee joint after injury. Gait analyses across all time points were also performed (n = 15 mice).

RESULTS

The majority of the ACL injuries in mice were partial tears. The femoral and tibial cortical bone volumes were 39% and 32% lower, respectively, at 28 days after injury than those of the uninjured contralateral knees (P < .01). Trabecular bone measures demonstrated little difference between injured and control knees after injury. Across all bone measures, bone loss was similar between the injured knee condyles and ACL entheses. There was also significant inflammatory activity within the knee after injury. By 7 days after injury, synovitis and fibrosis were sigificantly elevated in the injured knee compared with the controls (P < .01), which corresponded with significantly higher osteoclast activity in bone at this time point compared with the controls. This inflammatory response signficantly persisted throughout the duration of the study (P < .01). The hindlimb gait after injury deviated from normal, but mice habitually loaded their injured knee throughout the study.

CONCLUSION

Bone loss was acute and persisted for 4 weeks after injury in mice. However, the authors' hypothesis was not confirmed, as bone quality was not significantly lower in the entheses compared with the condylar bone regions after injury. With relatively normal hindlimb loading but a significant physiological response after injury, bone loss in this model may be driven by inflammation.

CLINICAL RELEVANCE

There is persistent bone resorption and fibrotic tissue development after injury that is not resolved. Inflammatory and catabolic activity may have a significant role in the postinjury decline of bone quality in the knee.

Evaluation of Autografts Used in Anterior Cruciate Ligament Reconstruction in Terms of Tensile Strength

Introduction Anterior cruciate ligament (ACL) injuries increase the likelihood of chronic knee problems in later years, including early onset osteoarthritis. Therefore, ACL treatment is important in preventing knee problems from developing. The treatment of choice for ACL tears is surgery (ACL reconstruction), and the most popular tendons for ACL reconstruction are the patellar tendon, hamstring tendon (semitendinosus and gracilis tendons), and bone-patellar tendon-bone. The present study compares the tensile strength of autografts used in ACL reconstruction to identify the optimum autograft for ACL in terms of mechanical properties. Methods Cadavers were dissected, and the Achilles tendons, quadriceps tendons, hamstring tendons (semitendinosus and gracilis tendons), patellar tendon grafts, and ACLs were harvested. Tensile tests of each tendon graft were performed using a Shimadzu Autograph AG-IS 100 kN tester (Shimadzu, Kyoto, Japan). Results The mean difference in tensile strength between ACL and other grafts was lowest for the quadriceps in both males and females (p ˂ 0.001), meaning that ACL and quadriceps grafts are more compatible than other tendon grafts in terms of tensile strength. Conclusion The present study found the lowest mean difference in tensile strength to be between the ACL and the quadriceps tendon, suggesting that the use of the quadriceps tendon in ACL reconstruction will yield more positive outcomes.

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.

Scapholunate instability: why are the surgical outcomes still so far from ideal?

The wrist is a universal joint with intrinsic and extrinsic ligaments that function and fail as ligamentous complexes. Those related to scapholunate instability (SLI) include the dorsal scapholunate complex (DSLC), volar radiolunate complex and scaphotrapeziotrapezoid complex. Together the DSLC, scaphoid and lunate create an 'acetabulum' for the capitate, with the dorsal intercarpal ligament being a labrum to contain the capitate. SLI results from failure of the DSLC, typically from its scaphoid attachments. Failure of the lunate and or triquetral attachments increases the instability. DSLC failure leads to radioscaphoid instability, which is the symptomatic clinical problem. SLI reconstruction with open surgery and trans-osseous tendon graft techniques have been challenging. We discuss a biological arthroscopic approach to identify, mobilize and debride the disrupted DSLC. This ligament/capsular/periosteum sheet is then advanced and secured to the debrided footprint. Thereby reconstituting the acetabulum, labrum and scaphoid stability.

The Need To Change Return to Play Testing in Athletes Following ACL Injury: A Theoretical Model

The incidence of knee injuries in sport, particularly involving the ACL, appears to be increasing yearly, especially in younger age athletes. Even more concerning is the frequency of ACL reinjury also appears to be increasing year after year. Improving the objective criteria and testing methods used to determine return to play (RTP) readiness following ACL surgery is one aspect of the rehabilitation process that can significantly help in reducing reinjury rates. Currently, the majority of clinicians are still using post operative time frames as their number one criterion for clearance to RTP. This flawed method demonstrates an inadequate reflection of the true unpredictable, dynamic environment athletes are returning to participate in. In our clinical experience, objective testing to allow for clearance to sport participation following an ACL injury should incorporate neurocognitive and reactive testing due to the nature of the injury typically occurs because of failed control of unanticipated reactive movements. The purpose of this manuscript is to share a neurocognitive testing sequence we currently employ consisting of 8 tests in 3 categories: Blazepod tests, reactive shuttle run tests, and reactive hop tests. The use of a more dynamic reactive testing battery may decrease the reinjury rates when an athlete is cleared for participation by measuring readiness in chaotic circumstances that are more truly reflective of the sporting environment the athlete is working to return to and in the process give them a greater sense of confidence.

Anatomic anterior cruciate ligament reconstruction: Freddie Fu's paradigm

Anterior cruciate ligament (ACL) reconstruction techniques have evolved over the past four decades. There is evidence that non-anatomic reconstruction techniques, such as traditional transtibial drilling, fail to recreate the native anatomy of the ACL, which can lead to increased rotatory knee instability, revision risk, and post-traumatic osteoarthritis. Anatomic ACL reconstruction has emerged as the gold standard, with the goal of restoring the patient's native anatomy and knee kinematics. This review will summarise the relevant anatomy, modern anatomic ACL reconstruction techniques, and literature supporting anatomic ACL reconstruction as the new paradigm. LEVEL OF EVIDENCE: Level V, review article.

Advanced Gene Therapy Strategies for the Repair of ACL Injuries

The anterior cruciate ligament (ACL), the principal ligament for stabilization of the knee, is highly predisposed to injury in the human population. As a result of its poor intrinsic healing capacities, surgical intervention is generally necessary to repair ACL lesions, yet the outcomes are never fully satisfactory in terms of long-lasting, complete, and safe repair. Gene therapy, based on the transfer of therapeutic genetic sequences via a gene vector, is a potent tool to durably and adeptly enhance the processes of ACL repair and has been reported for its workability in various experimental models relevant to ACL injuries in vitro, in situ, and in vivo. As critical hurdles to the effective and safe translation of gene therapy for clinical applications still remain, including physiological barriers and host immune responses, biomaterial-guided gene therapy inspired by drug delivery systems has been further developed to protect and improve the classical procedures of gene transfer in the future treatment of ACL injuries in patients, as critically presented here.

Assessment of Ligament Viscoelastic Properties Using Raman Spectroscopy

Injuries to the ligaments of the knee commonly impact vulnerable and physically active individuals. These injuries can lead to the development of degenerative diseases such as post-traumatic osteoarthritis (PTOA). Non-invasive optical modalities, such as infrared and Raman spectroscopy, provide means for quantitative evaluation of knee joint tissues and have been proposed as potential quantitative diagnostic tools for arthroscopy. In this study, we evaluate Raman spectroscopy as a viable tool for estimating functional properties of collateral ligaments. Artificial trauma was induced by anterior cruciate ligament transection (ACLT) in the left or right knee joint of skeletally mature New Zealand rabbits. The corresponding contralateral (CL) samples were extracted from healthy unoperated joints along with a separate group of control (CNTRL) animals. The rabbits were sacrificed at 8 weeks after ACLT. The ligaments were then harvested and measured using Raman spectroscopy. A uniaxial tensile stress-relaxation testing protocol was adopted for determining several biomechanical properties of the samples. Partial least squares (PLS) regression models were then employed to correlate the spectral data with the biomechanical properties. Results show that the capacity of Raman spectroscopy for estimating the biomechanical properties of the ligament samples varies depending on the target property, with prediction error ranging from 15.78% for tissue cross-sectional area to 30.39% for stiffness. The hysteresis under cyclic loading at 2 Hz (RMSE = 6.22%, Normalized RMSE = 22.24%) can be accurately estimated from the Raman data which describes the viscous damping properties of the tissue. We conclude that Raman spectroscopy has the potential for non-destructively estimating ligament biomechanical properties in health and disease, thus enhancing the diagnostic value of optical arthroscopic evaluations of ligament integrity.

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.

Exosomes derived from magnetically actuated bone mesenchymal stem cells promote tendon-bone healing through the miR-21-5p/SMAD7 pathway

Graft healing after anterior cruciate ligament reconstruction (ACLR) involves slow biological processes, and various types of biological modulations have been explored to promote tendon-to-bone integration. Exosomes have been extensively studied as a promising new cell-free strategy for tissue regeneration, but few studies have reported their potential in tendon-to-bone healing. In this study, a novel type of exosome derived from magnetically actuated (iron oxide nanoparticles (IONPs) combined with a magnetic field) bone mesenchymal stem cells (BMSCs) (IONP-Exos) was developed, and the primary purpose of this study was to determine whether IONP-Exos exert more significant effects on tendon-to-bone healing than normal BMSC-derived exosomes (BMSC-Exos). Here, we isolated and characterized the two types of exosomes, conducted in vitro experiments to measure their effects on fibroblasts (NIH3T3), and performed in vivo experiments to compare the effects on tendon-to-bone integration. Moreover, functional exploration of exosomal miRNAs was further performed by utilizing a series of gain- and loss-of-function experiments. Experimental results showed that both BMSC-Exos and IONP-Exos could be shuttled intercellularly into NIH3T3 fibroblasts and enhanced fibroblast activity, including proliferation, migration, and fibrogenesis. In vivo, we found that IONP-Exos significantly prevented peri-tunnel bone loss, promoted more osseous ingrowth into the tendon graft, increased fibrocartilage formation at the tendon-bone tunnel interface, and induced a higher maximum load to failure than BMSC-Exos. Furthermore, overexpression of miR-21-5p remarkably enhanced fibrogenesis in vitro, and SMAD7 was shown to be involved in the promotive effect of IONP-Exos on tendon-to-bone healing. Our findings may provide new insights into the regulatory roles of IONPs in IONP-Exos communication via stimulating exosomal miR-21-5p secretion and the SMAD7 signaling pathway in the fibrogenic process of tendon-to-bone integration. This work could provide a new strategy to promote tendon-to-bone healing for tissue engineering in the future.

State of the mineralized tissue comprising the femoral ACL enthesis in young women with an ACL failure

Despite poor graft integration among some patients that undergo an anterior cruciate ligament (ACL) reconstruction, there has been little consideration of the bone quality into which the ACL femoral tunnel is drilled and the graft is placed. Bone mineral density of the knee decreases following ACL injury. However, trabecular and cortical architecture differences between injured and non-injured femoral ACL entheses have not been reported. We hypothesize that injured femoral ACL entheses will show significantly less cortical and trabecular mass compared with non-injured controls. Femoral ACL enthesis explants from 54 female patients (13-25 years) were collected during ACL reconstructive surgery. Control explants (n = 12) were collected from seven donors (18-36 years). Injured (I) femoral explants differed from those of non-injured (NI) controls with significantly less (p ≤ 0.001) cortical volumetric bone mineral density (vBMD) (NI: 736.1-867.6 mg/cm³ ; I: 451.2-891.9 mg/cm³ ), relative bone volume (BV/TV) (NI: 0.674-0.867; I: 0.401-0.792) and porosity (Ct.Po) (NI: 0.133-0.326; I: 0.209-0.600). Injured explants showed significantly less trabecular vBMD (p = 0.013) but not trabecular BV/TV (p = 0.314), thickness (p = 0.412), or separation (p = 0.828). We found significantly less cortical bone within injured femoral entheses compared to NI controls. Lower cortical and trabecular bone mass within patient femoral ACL entheses may help explain poor ACL graft osseointegration outcomes in the young and may be a contributor to the osteolytic phenomenon that often occurs within the graft tunnel following ACL reconstruction.

Mechanical and fatigue behaviour of artificial ligaments (ALs)

A flexible biologic band, ACL is the most injured and ruptured ligament in the knees of humans and animals. This research aims to produce synthetic anterior cruciate ligaments (ACLs) and compare these ligaments' mechanical and fatigue life properties with the natural ACL and commercial synthetic grafts. Artificial ligaments were designed as a core-sheath type structure. The core consisted of straight, parallel yarns and the sheath was a tubular fabric produced by weaving or braiding techniques from polyester or Vectran® yarns. The mechanical properties of the resulting artificial ligaments (AL) were tested before and after the fatigue test and compared to those of the natural ACL and commercial artificial ACLs in the market. Results showed that all ligaments had sufficient tensile strength, and they retained it after the fatigue test. If constructed sheath and core parts were from the same type of yarns, the breaking load of ligaments was higher. The breaking strain and stiffness of woven structures, particularly with Vectran cores, were better than braided ones. After the fatigue test, the breaking strain and stiffness of AL structures with a braided sheath or polyester core were improved. This finding suggests that to prevent the laxity of knee preconditioning of the ligament is necessary if the fabric structure or yarn inherently has high breaking strain and low stiffness. Overall, this study shows that a variety of suitable candidates for replacing ruptured anterior cruciate ligaments could be developed by carefully combining the fatigue-resistant yarns with leno, narrow, and braided structures.

On Measuring Implant Fixation Stability in ACL Reconstruction

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

Achilles Tendon Allograft Preparation Technique for Anterior Cruciate Ligament Reconstruction: A Technical Note

Several factors associated with graft preparation for the surgery of the anterior cruciate ligament (ACL) like the wrong thawed, prophylaxis, bone cuts, excessive bone removal as well as positioning problems like a tunnels-graft mismatch, insufficient harvesting of the donor's tendon, size graft limitations (length and diameter), uncontrolled rotation of graft in their longitudinal axis, over or under tensioned graft, fixation mistakes, bone defects, secondary arthrofibrosis or morbidity of the donor site, and others factors importantly affect the outcomes of the ACL surgery. In this sense, the Achilles tendon Allograft is an advantageous technique where many of the previous limitation factors described can be controlled during an appropriate preparation. However, to obtain the maximum potentialities of the graft a detailed knowledge of the preparation is required. Hence, we aimed to describe how to prepare the Achilles tendon Allograft to control the graft's length and diameter, bone removal, and fixation requirements.

Biomechanical analysis of three different types of fixators for anterior cruciate ligament reconstruction via finite element method: a patient-specific study

Complication rates of anterior cruciate ligament reconstruction (ACL-R) were reported to be around 15% although it is a common arthroscopic procedure with good outcomes. Breakage and migration of fixators are still possible even months after surgery. A fixator with optimum stability can minimise those two complications. Factors that affect the stability of a fixator are its configuration, material, and design. Thus, this paper aims to analyse the biomechanical effects of different types of fixators (cross-pin, interference screw, and cortical button) towards the stability of the knee joint after ACL-R. In this study, finite element modelling and analyses of a knee joint attached with double semitendinosus graft and fixators were carried out. Mimics and 3-Matic softwares were used in the development of the knee joint models. Meanwhile, the graft and fixators were designed by using SolidWorks software. Once the meshes of all models were finished in 3-Matic, simulation of the configurations was done using MSC Marc Mentat software. A 100-N anterior tibial load was applied onto the tibia to simulate the anterior drawer test. Based on the findings, cross-pin was found to have optimum stability in terms of stress and strain at the femoral fixation site for better treatment of ACL-R.

The Top 100 Most Cited Articles on Anterior Cruciate Ligament Reconstruction: A Bibliometric Analysis

Background

The concept of anterior cruciate ligament (ACL) reconstruction (ACLR) has become widely accepted, gaining increased attention in recent years and resulting in many research achievements in this field.

Purpose

The aim of this study was to determine which original articles on ACLR have been most influential in this field by identifying and analyzing the characteristics of the 100 most cited articles.

Study Design

Cross-sectional study.

Methods

Articles on ACLR were identified via the Thomson ISI Web of Science database on November 30, 2019. The 100 most cited articles were identified based on inclusion and exclusion criteria. The data extracted from each article for the subsequent analysis included title, date of publication, total citations, average citations per year (ACY), journal name, first author, institutions, themes, level of evidence, and keywords.

Results

The total number of citations was 29,629. The date of publication ranged from 1975 to 2015. A majority of the articles originated from the United States (58%) and were published in the 1990s (32%) and 2000s (48%). The mean ACY was 18.43 ± 9.51. Of the selected articles, nearly one-half were published in the American Journal of Sports Medicine (42%). The most prolific co-author and first author were Freddie H. Fu (n = 13) and K. Donald Shelbourne (n = 5), respectively. The most productive institution was the University of Pittsburgh (14%). Material comparison (19%) and technique comparison (16%) were the 2 most popular themes. More than one-quarter of articles were level 4 evidence (37%). Moreover, the keywords ACL, ACL reconstruction, ACL rupture, knee joint, knee injuries, and human showed the highest degree of centrality.

Conclusion

By analyzing the characteristics of articles, this study demonstrated that ACLR is a growing and popular area of research, with the focus of research varying through timeline trends. Studies on anatomic reconstruction and biomechanics might be areas of future trends.

The Use of Suture Augmentation for Graft Protection in ACL Reconstruction: A Biomechanical Study in Porcine Knees

Purpose

To biomechanically evaluate the use of the suture augmentation construct at time 0 of ACL reconstruction.

Methods

Eighty porcine knees underwent ACL reconstruction using 2 techniques for graft fixation: a single suspensory construct (SSC), performed with a femoral button and tibial interference screw; and a double suspensory construct (DSC), with a femoral and tibial button. Each fixation technique was performed on 40 porcine knees divided into 4 subgroups. The first group had a nonaugmented ACL reconstruction, the second group had an ACL reconstruction with suture augmentation, and the third and fourth groups were the same as the first and second groups, with the graft resected 80% to simulate graft weakening. Ultimate load, yield load, stiffness, cyclic displacement values, and mode of failure were recorded for each graft.

Results

In a weakened graft model with 80% graft resection, there was a significant increase in ultimate strength (P < .001), yield strength (P < .001), and cyclic displacement (P < .001) with suture augmentation. There was no significant increase in stiffness with suture augmentation with either construct (P = .278). In the setting of an intact graft, there were no differences in either SSC or DCS groups with or without suture augmentation.

Conclusions

The addition of a suture to ACL reconstruction techniques resulted in minimal changes in baseline biomechanical characteristics while improving ultimate load, yield load, and cyclic displacement in a weakened graft model.

Clinical Relevance

Suture augmentation of ACL reconstruction may confer improved integrity of the graft and is worth consideration and future clinical study.

The Influence of Anterior Cruciate Ligament Matrix Mechanical Properties on Simulated Whole-Knee Biomechanics

Knee finite element (FE) models are used to study tissue deformation in response to complex loads. Typically, ligaments are modeled using transversely isotropic, hyperelastic material models fitted to tension data along the predominant fiber direction (longitudinal) and, less commonly, to tension data orthogonal to the fiber direction (transverse). Currently, the shear and bulk responses of the anterior cruciate ligament (ACL) are not fitted to experimental data. In this study, a newly proposed material model was fitted to longitudinal tension, transverse tension, and shear experimental data. The matrix transverse tensile, shear, and bulk stiffnesses were then varied independently to determine the impact of each property on knee kinematics and tissue deformation in a whole-knee FE model. The range of values for each parameter was chosen based on published FE studies of the knee. For a knee at full extension under 134 N anterior tibial force (ATF), increasing matrix transverse tensile stiffness, shear stiffness, or bulk stiffness decreased anterior tibial translation (ATT), ACL longitudinal strain, and ACL shear strain. For a knee under 134 N ATF and 1600 N compression, changing the ACL matrix mechanical properties caused variations in ATT and thus changed cartilage deformation contours by changing the point of contact between the femoral and the tibial cartilage. These findings indicate that material models for the ACL must describe matrix material properties to best predict the in vivo response to applied loads.

Comparative Efficacy of Graft Options in Anterior Cruciate Ligament Reconstruction: A Systematic Review and Network Meta-Analysis

Purpose

To evaluate the effectiveness of various graft options for anterior cruciate ligament reconstruction using network meta-analysis.

Methods

A medical literature search was conducted of PubMed, the Cochrane Library, Embase, SCOPUS, and Web of Science from their inception through March 1, 2019. The outcomes, including International Knee Documentation Committee (IKDC) form, Lachman test, Lysholm score, Pivot shift test, and Tegner score, were evaluated among graft options. Data extraction was carried out according to inclusion and exclusion criteria, and a network meta-analysis was performed using STATA 14.0.

Results

A total of 45 trials with 3992 patients were included. The forest plots revealed no significant differences in IKDC, Lysholm, or Tegner score among the grafts. In Lachman score, a significant difference was found in the comparisons of hamstring tendon allograft (HT-AL) versus patellar tendon autograft (PT-AU) and HT-AL versus hamstring tendon autograft (HT-AU). In pivot shift test, PT-AU was superior to all the other grafts, and quadriceps tendon autograft (QT-AU) was superior to HT-AL and artificial ligament (Art-L) in the number of cases with negative results. According to surface under the cumulative ranking area (SUCRA), PT-AU had the highest probability to be the best intervention in Lachman test and Tegner score; tibialis anterior tendon allograft (TA-AL) in IKDC and Lysholm score; and QT-AU in pivot shift test. Based on the cluster analysis of SUCRA, PT-AU was considered the most appropriate intervention by IKDC and Lachman test.

Conclusion

This study suggests that PT-AU may be the most appropriate graft for ACL reconstruction according to IKDC and Lachman test results.

Level of Evidence

Level I, network meta-analysis of randomized controlled trials.

No difference in revision rates between anteromedial portal and transtibial drilling of the femoral graft tunnel in primary anterior cruciate ligament reconstruction: early results from the New Zealand ACL Registry

PURPOSE

The use of an accessory anteromedial portal to drill the femoral graft tunnel in primary anterior cruciate ligament (ACL) reconstruction was introduced in the 2000s in an effort to achieve a more anatomic femoral tunnel position. However, some early studies reported an increase in revision ACL reconstruction compared to the traditional transtibial technique. The aim of this study was to analyse recent data recorded by the New Zealand ACL Registry to compare outcomes of ACL reconstruction performed using the anteromedial portal and transtibial techniques.

METHODS

Analysis was performed on primary isolated single-bundle ACL reconstructions recorded between 2014 and 2018 by the New Zealand ACL Registry. Patients were categorised into two groups according to whether an anteromedial portal or transtibial technique was used to drill the femoral graft tunnel. The primary outcome was revision ACL reconstruction and was compared between both groups through univariate and multivariate survival analyses. The secondary outcomes that were analysed included subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Marx activity score.

RESULTS

Six thousand one hundred and eighty-eight primary single-bundle ACL reconstructions were performed using either the anteromedial portal or transtibial drilling techniques. The mean time of follow-up was 23.3 (SD ± 14.0) months. Similar patient characteristics such as mean age (29 years, SD ± 11), sex (males = 58% versus 57%) and time to surgery (median 4 months, IQR 5) were observed between both groups. The rate of revision ACL reconstruction was 2.6% in the anteromedial portal group and 2.2% in the transtibial group (n.s.). The adjusted risk of revision ACL reconstruction was 1.07 (95% CI 0.62-1.84, n.s.). Patients in the anteromedial portal group reported improved scores for subscales of the KOOS and higher Marx activity scores at 1-year post-reconstruction.

CONCLUSION

There was no difference in the risk of revision ACL reconstruction between the two femoral tunnel drilling techniques at short-term follow-up. We observed minor differences in patient-reported outcomes at 1-year follow-up favouring the anteromedial portal technique, which may not be clinically relevant. Surgeons can achieve good clinical outcomes with either drilling technique.

LEVEL OF EVIDENCE

III.

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.

Clinico-radiological outcomes following anatomical anterior cruciate ligament reconstruction using the TransLateral, all-inside technique

We present early clinical outcomes of patients following anatomical anterior cruciate ligament reconstruction using a TransLateral, single bundle, all-inside technique with a one-year follow-up and radiological evaluation of socket position. Eligible Patients who underwent a primary ACL reconstruction, using the TransLateral, all-inside technique alone, between Jan 2013 and Feb 2016 were included in this study. Of this group, all patients underwent isolated semitendinosus graft harvest. The Lysholm knee scores were measured preoperatively and at one-year follow-up in 40 patients who underwent ACL reconstruction. Postoperatively, antero-posterior and lateral radiographs were obtained to evaluate the position of the femoral socket (using the Bernard and Hertel Grid) and tibial socket (using the Amis-Jakob line). There were 36 males and 4 females with a mean age of 27.1 years (range 16-49). There was a single non-surgical related mortality prior to the one year follow up. We report no postoperative infections or graft failure at one year. The mean preoperative Lysholm score was 68.7 (Range: 29-95). The mean Lysholm score increased to 92.5% (Range: 59-100, p < 0.05). Evaluation of femoral sockets revealed accurate positioning on the Bernard and Hertel Grid with a mean ACL center of 27% along Blumensaat's line and 34% of the height of the intercondylar notch. The mean tibial socket position was 41.8% (Range: 32%-47%) along the Amis-Jakob Line. Our single surgeon case series utilizing the all-inside, TransLateral ACLR technique highlights good early outcomes with no postoperative complications or graft failure at one year.

Anterior Cruciate Ligament Reconstruction in Patients Older Than 50 Years: A Systematic Review and Meta-analysis

Background:

There is no consensus regarding the best treatment approach for middle-aged patients with anterior cruciate ligament (ACL) injuries. Chronic ACL-deficient knees are often associated with instability as well as secondary meniscal and cartilage lesions. ACL reconstruction (ACLR) has achieved satisfactory outcomes in younger patients; however, the effectiveness and safety of ACLR in middle-aged patients remain uncertain.

Purpose:

To compare the patient-reported functional scores, arthrometric outcomes, and complications of primary ACLR between older (≥50 years) and younger (<50 years) patients.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

We conducted a systematic review of cohort studies that compared the clinical outcomes of ACLR between patients aged ≥50 years and those aged <50 years. The Cochrane Central Register of Controlled Trials, Embase, and MEDLINE databases were searched for relevant studies. The Methodological Index for Non-randomized Studies (MINORS) criteria was used to assess the risk of bias and conducted a random-effects meta-analysis to combine the data, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to evaluate the overall quality of the body of retrieved evidence. The primary outcome was knee functional outcomes, and secondary outcomes were arthrometric outcomes of ACLR and complications.

Results:

This study included 4 retrospective cohort studies with a total of 287 participants (129 in the older group and 158 in the younger group). All included studies reported significant improvements in clinical outcomes in both groups after ACLR. No significant differences were noted in the improvement of International Knee Documentation Committee (IKDC) scores (mean difference [MD], 0.20 [95% CI, −2.65 to 3.05]; P = .89) and Lysholm scores (MD, −1.98 [95% CI, −6.93 to 2.98]; P = .43) between the 2 groups. No significant differences were observed in anteroposterior stability or risk of complications between the groups.

Conclusion:

ACLR may be performed in middle-aged patients (≥50 years) without concern for inferior clinical and arthrometric results compared with younger patients (<50 years).

Prevalence of knee injuries among male college students in Riyadh, Kingdom of Saudi Arabia

BACKGROUND

The knee is considered the most common injured joint between young sport participants. However, there is lack of proper prevalence estimation in our population. The purpose of this study was to identify the prevalence of knee injuries among male college students and to observe the demographic data associated with it. Our secondary objective was to evaluate the awareness and knowledge about these injuries.

METHODS

This is a cross-sectional study. A survey was distributed to collect the data among male college students, King Saud University, Riyadh, Saudi Arabia. Out of 688 students who participated and completed the questionnaire, a total of 482 were considered valid and met the inclusion criteria. Data were analyzed using Statistical Package for Social Sciences (SPSS).

RESULTS

The overall prevalence of knee injury was 23.2% (n = 112). Most of them injured during sport activities especially soccer and 68.7% involved in a non-contact mechanism of injury. Among those who went to a hospital mostly were diagnosed as contusion (31.4%) then as meniscus tear, ACL, and collateral ligament injury, respectively. Majority was treated conservatively and only 10.7% needed surgery surprisingly. There was no statistically significant difference between those who are injured and whether they were warmed up and stretched or not (P = 0.619). Low level of knowledge about knee injuries was noticed among the participants 57.7%.

CONCLUSION

Our study has highlighted the high prevalence of knee injuries and the need to raise the level of awareness and knowledge about these injuries in our population. Soccer was the most common sport associated with knee injuries; most of these injuries were treated conservatively.

Adjustable Loop Femoral Cortical Suspension Devices for Anterior Cruciate Ligament Reconstruction: A Systematic Review

BACKGROUND

Anterior cruciate ligament (ACL) injury is a common sports injury. Symptomatic knee instability after this injury is usually treated operatively through ACL reconstruction. The surgery involves a tendon graft being fixed in bony tunnels drilled through femur and tibia. The fixation of the graft is of critical importance to achieving good results. One of the commonest devices used to fix the graft in the femoral bony tunnel is a fixed loop cortical suspensory device. More recently, adjustable loop cortical suspension devices have been introduced, and have gained popularity for ACL reconstruction. These allow for adjusting the length of the suspension loop after insertion. There is currently much debate concerning whether the adjustable loop devices are superior or inferior to the fixed loop devices.

PURPOSE

To critique and review the current biomechanical and clinical evidence on the use of adjustable loop devices in hamstring ACL reconstruction. To our knowledge, there have been no previous reviews of this topic.

STUDY DESIGN

Systematic review.

METHODS

This systematic review was conducted in accordance with PRISMA. Five databases were searched using multiple search terms and MeSH terms where possible. The following limits were applied: papers published in English and papers published in the last 21 years.

RESULTS

Eleven laboratory and six clinical studies were reviewed. The laboratory-based studies have frequently shown elongation of adjustable loop devices to more than 3 mm under loading protocols, whereas the clinical studies have not shown any significant differences between the patients with fixed loop and the ones with adjustable loop devices.

CLINICAL SIGNIFICANCE

This review shows a discrepancy between laboratory-based and clinical studies. The review of clinical studies in our paper would give future researchers confidence and act as a prompt to construct randomised clinical trials to investigate these devices further.

CONCLUSION

We feel that more robust clinical randomised studies and trials are needed to evaluate these new devices.

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.

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.

Does non-contact or delayed contact of an adjustable-loop femoral button affect knee stability following anterior cruciate ligament reconstruction?

BACKGROUND

The purpose of this study was to investigate whether cortical non-contact or delayed contact of an adjustable-loop button for femoral fixation could affect knee stability following anterior cruciate ligament (ACL) reconstruction.

METHODS

Eighty subjects who underwent single-bundle ACL reconstruction using an adjustable-loop femoral cortical button were retrospectively reviewed regarding patient demographics, graft size, combined surgery, and postoperative 2-year results of knee stability, functional scores, and radiographic tunnel widening. We compared the contact and the non-contact groups determined by position of the button observed in immediate postoperative radiographs. According to 2-year postoperative radiographs, the non-contact group was further divided into two subgroups (delayed contact and persisting non-contact subgroups) and results were compared.

RESULTS

The contact group had 46 patients and the non-contact group had 34 patients. The average gap distance in the non-contact group was 1.9 ± 0.6 (1.1-3.4) mm. There were no significant differences in KT-1000 arthrometric knee stability (p = .667) or Lysholm score (p = .198), or International Knee Documentation Committee (IKDC) score (p = .091) between the two groups. No significant differences in tunnel widening were found at femoral and tibial tunnels on anteroposterior and lateral radiographs (p > .1, all tunnels). In addition, delayed contact subgroup and persisting non-contact subgroup showed similar radiographic and clinical outcomes.

CONCLUSION

Surgeons should strive to obtain cortical contact of the adjustable-loop femoral button. Nevertheless, cortical non-contact with less than 3 mm of gap distance did not affect knee stability, radiographic outcomes, or clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The effect of cyclic knee motion on the elongation of four-strand hamstring autograft in anterior cruciate ligament reconstruction: an in-situ pilot study

Background

Pretension of the viscoelastic graft by cyclic knee motion has been confirmed to decrease the graft creep and improve the outcome of anterior cruciate ligament (ACL) reconstruction. The purpose of the present study was to investigate the effect of cyclic knee motion on the elongation of the four-strand hamstring tendon autograft in situ and to explore the stable level cycle, in which the tendon length achieved a stable level.

Methods

The study was performed with 53 consecutive patients undergoing transtibial ACL reconstruction with four strand hamstring tendon from Aug 2013 to Apr 2015. 43 males and 10 females were included with mean age of 29 ± 10 years. The pretension of the tendons was operated by cyclical knee motion ranging from 0 to 110°after the femoral fixation with Endo-button. The tendon length after 10, 20, 30 and 40 cycles was measured respectively and compared by repeated measure ANOVA. Then multivariate logistic regression was used to investigate the effect of the patients’ parameters (age, gender, height, body weight, tendon length, etc.) on the elongation of the graft and the stable level cycle.

Results

The mean lengthening of the graft at 10, 20, 30 and 40 times was 3.0 ± 1.4 mm, 4.3 ± 1.5 mm, 4.8 ± 1.7 mm and 4.8 ± 1.8 mm respectively. No significant correlation was found between the elongation and the patients’ parameters. There was significant difference of the tendon length from 0 to 30 cycles (F = 264.8, df = 1.95, p<0.001). However, the tendon length achieved a stable level after 30 cycles and the median elongation from 30 cycles to 40 cycles was 0 (0–1) mm with no significant difference (F = 2.039, p = 0.159). The male and female tendon length achieved to a stable level at 20 cycles and 30 cycles respectively but with no significant difference (p = 0.074).

Conclusions

The four-strand hamstring tendon was elongated after cyclic knee motion and the elongation achieved a stable level after 30 cycles for the transtibial technique. Both of the tendon elongation and the stable level cycle were not correlated with patients’ gender, age, preoperative duration, graft diameter and length.

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.

Comparison of Tibial Tuberosity-Trochlear Groove (TT-TG) distances between different anterior cruciate ligament reconstructions: A retrospective clinical and imaging study

BACKGROUND:

Previous studies showed that compared with single-bundle (SB) precedures, double-bundle (DB) anterior cruciate ligament (ACL) reconstruction perform better.

OBJECTIVE:

To make assurance that distance of TT-TG may be altered along with ACL rupture and reconstruction.

METHODS:

Imaging study of 201 patients’s related cases by MRI and CT scans.

RESULTS:

Compared with the intact knee’s overall mean TT-TG value, the mean overall pre/postoperative TT-TG values showed a significant difference. For SB reconstruction, the mean pre/postoperative TT-TG values were 15.67± 2.46 mm and 14.72± 2.48 mm, respectively. Postoperative and intact knee TT-TG values were significantly different (p< 0.001). For DB reconstruction, the pre/postoperative mean TT-TG values were 15.11± 1.99 mm and 13.11± 1.71 mm. Postoperative and intact knee TT-TG values were not significantly different (p= 0.141).

CONCLUSIONS:

The increased TT-TG value from a ruptured ACL was significantly restored after ACL reconstruction. The TT-TG value after SB reconstruction was still obviously larger than that of the intact knee. It showed no significant difference between the postoperative TT-TG of the DB group and intact knees. The original TT-TG values of the knees were much closer to restoration after DB reconstruction.

Anatomical relationship between insertion sites, tunnel placement, and lateral meniscus anterior horn injury during single and double bundle anterior cruciate ligament reconstructions: A comparative macroscopic and histopathological evaluation in cadavers

PURPOSE

The influence of tunnel extension outside the anatomical anterior cruciate ligament (ACL) insertion in single-bundle (SB) or double-bundle (DB) ACL reconstruction is unclear. This study aimed to investigate the anatomical relationship between ACL insertion and tunnel extension in SB and DB ACL reconstruction, and the impact of tibial tunnel extension to the insertion of anterior horn of lateral meniscus in terms of injury.

METHODS

Forty-six paired cadaver knees (mean age, 82.7 ± 10.7 years) were used. Right and left knees were used for SB (10 mm) and DB tunnel reaming (6 mm for the anteromedial and posterolateral bundles). Tibial and femoral tunnels were created to aim at the center of the ACL insertion by arthroscopic visualization. The relationship between tunnel extension and ACL insertion was evaluated macroscopically, and there ratio in two groups were compared by chi-square test. Further, the relative risk for meniscus injury based on tunnel placement was estimated. Coronal section of tibia and parallel section to Blumensaat line in femur were prepared to evaluate the relationship among tunnel position, ACL insertion, and anterior horn of the meniscus histologically.

RESULTS

Tibial tunnel extension out of the ACL insertion was observed macroscopically in 9 (39.1%) knees of the SB group, and 3 (13.0%) of the DB group (p = 0.045). In femoral tunnels, extension out of the ACL insertion was seen in 8 (34.8%) knees of the SB group and 1 (4.3%) of the DB group (p = 0.011). Partial injuries of the lateral meniscus anterior horn (LMAH) were observed in 5 (21.7%) knees of the SB group and 1 (4.3%) knee of the DB group (p = 0.091). The relative risk for LMAH injury was calculated as 5.0 (odds ratio, 6.1). Microscopically, SB tunnels appeared to expand out of ACL insertion, both in the femur and tibia.

CONCLUSIONS

The incidence of tunnel extension out of the ACL insertion in femur and tibia were higher with SB than with DB reconstruction. Furthermore, injury rate of the LMAH in the DB group was lower.

Activity-related outcome in anterior cruciate ligament reconstruction with synthetic ligament advanced reinforcement system

BACKGROUND

Arthroscopic anterior cruciate ligament (ACL) reconstruction with ligament advanced reinforcement system (LARS) had revealed good results with low complication and failure rate in series of studies. The specific candidates for ACL reconstruction with LARS are still unknown anyway. The purpose of this study is to evaluate the activity-related outcome in ACL reconstruction using LARS ligament.

METHODS

A total of 43 unilateral arthroscopic ACL reconstructions with LARS were collected and divided into two groups: group A (preinjury Tegner score ≥ 6, n = 20) and group B (preinjury Tegner score < 6, n = 23). We had analyzed the stability of knee and functional outcome with a minimum of 2-years follow up.

RESULTS

All patients were aware of improvement over the knee stability immediately after ACL reconstruction with LARS. The functional outcome of knee was improved in both groups by analysis with the Lysholm score and modified International Knee Documentation Committee (IKDC) score. The postoperative grading of the knee examination form of modified IKDC grade showed no statistical difference in both groups.

CONCLUSION

Arthroscopic ACL reconstruction with LARS was encouraged as an alternative option even in high sports demand patients.

Knee extensor and flexor strength before and after anterior cruciate ligament reconstruction in a large sample of patients: influence of graft type

OBJECTIVE

Hamstring and patellar tendon autografts are the most frequently-used graft types for anterior cruciate ligament (ACL) reconstruction, with no consensus on their respective effects on thigh muscle strength. The objective of this study was to re-examine isokinetic knee extensor and flexor strength before and after ACL reconstruction with patellar and hamstring tendon grafts using a single-center and a relatively large database, where surgical, rehabilitation and testing procedures were strictly standardized for all patients.

METHODS

A total of 464 patients with a unilateral ACL rupture underwent arthroscopic ACL reconstruction with either patellar or hamstring tendon grafts. Isokinetic concentric strength was evaluated prior to surgery and at 5- and 9-month postoperative follow-ups in different patient subgroups (n = 140, 464 and 215, respectively).

RESULTS

Knee extensor strength was lower in patients operated with the patellar tendon graft at the 5-month (p < 0.05) but not at the 9-month follow-up. Knee flexor strength was lower in patients operated with the hamstring tendon graft at both postoperative time points (p < 0.05). The prevalence of quadriceps weakness was high (66-91%) in both patient groups at both follow-ups.

CONCLUSION

Overall, postoperative recovery of thigh muscle function seems to be better with the patellar than with the hamstring tendon graft due to the fact that both, knee extensor and flexor strength, were more impaired after ACL reconstruction with the hamstring tendon autograft.

Mechanical advantage of preserving the hamstring tibial insertion for anterior cruciate ligament reconstruction - A cadaver study

INTRODUCTION

The best fixation method for an anterior cruciate ligament (ACL) graft is debated. The tibial fixation of tendon grafts is the principal weak point for mechanical and anatomical reasons. Preserving the tibial insertion for hamstring grafts during ACL reconstruction make provide a mechanical benefit. The aim of this study was to compare the strength at the tibial tunnel of a hamstring graft with intact tibial insertion without a screw, to that of a graft with intact tibial insertion and screw fixation, and to that of a free graft with screw fixation. We hypothesized that preserving the graft's tibial insertion increases the maximum resistance of the tibial fixation relative to a free graft.

MATERIALS AND METHODS

Five pairs of knees (10 specimens) from frozen human donors were used. The tendons of the semitendinosus and gracilis were prepared as a four-strand graft while preserving their tibial insertion. The graft was passed through the tibial tunnel using standard instrumentation and the usual landmarks. Three conditions were tested: group 1 - graft with intact tibial insertion without interference screw; group 2 - graft with intact tibial insertion and interference screw; group 3 - knees from group 1 in which the tendons were detached (free graft) after the first test and fixed with an interference screw in the tibial tunnel. The screw diameter was chosen based on the graft diameter. The specimens were tested in traction using a materials testing system (Instron^® 8500 PLUS) in the axis of the tunnel. The main outcome measure was the maximum load at failure (N). The secondary outcome measure was the stiffness. The groups were compared using the Friedman test and the Nemenyi post-hoc test with a 5% threshold.

RESULTS

The load at failure was 33% higher in group 1 than group 3 (89.2N vs. 67.2N, p>0.05). The load at failure of group 2 was 25% higher than group 1 (111.2N vs. 89.2N, p>0.05) and 65% higher than group 3 (111.2N vs. 67.2N p=0.005). There were no differences in stiffness between groups 1 and 2 (p=1).

DISCUSSION

Our hypothesis was confirmed-preserving the tibial insertion of hamstring tendons intended for ACL reconstruction increases the maximum load to failure at the tibial tunnel. Under these experimental conditions it seems that adding a screw increases the pullout strength of the graft by +25% in absolute terms; however this difference was not statistically significant.

LEVEL OF EVIDENCE

III, controlled laboratory study.

Increased knee laxity with hamstring tendon autograft compared to patellar tendon autograft: a cohort study of 5462 patients with primary anterior cruciate ligament reconstruction

PURPOSE

To compare anterior knee laxity and patient-reported outcome measures (PROMs) between anterior cruciate ligament reconstruction (ACLR) performed with bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) autografts and, moreover, to study any correlation between postoperative anterior knee laxity and PROMs.

METHODS

Patients who underwent primary ACLR at Capio Artro Clinic, Stockholm, Sweden, from January 2000 to October 2015, were identified in our local database. Instrumented laxity measurements and PROMs were reviewed. The KT-1000 arthrometer, with an anterior tibial load of 134-N, was used to evaluate knee laxity preoperatively and at the 6-month follow-up. The Lysholm score was collected preoperatively and at 6 months postoperatively. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and at the 1-year follow-up.

RESULTS

A total of 5462 primary ACLRs, 692 BPTBs and 4770 HT autografts were included in the study. All the patients showed a significant reduction in knee laxity from preoperatively to postoperatively (BPTB group: from 3.8 ± 2.6 to 1.2 ± 2.1 mm; HT group: from 3.6 ± 3.1 to 1.8 ± 2.2 mm; P < 0.001 for both). The HT group showed a significantly increased postoperative knee laxity compared with the BPTB group (1.8 ± 2.2 vs 1.2 ± 2.1 mm; P < 0.001). The mean anterior tibial translation (ATT) reduction from preoperative to postoperative was significantly larger for the BPTB graft compared with the HT graft (2.7 ± 2.2 vs 1.7 ± 2.6 mm; P < 0.001). A significantly higher rate of "surgical failures", defined as a postoperative side-to-side (STS) difference > 5 mm, was found in the HT group compared with the BPTB group at follow-up (4.3 vs 2.4%; P < 0.001). A significantly larger improvement was found in the HT group compared with the BPTB group for the KOOS Pain (9.5 vs 8.0; P = 0.02), Activities of Daily Living (7.2 vs 5.7; P = 0.006), Sports (24.2 vs 15.3; P < 0.001) and Quality of Life (25.8 vs 22.1; P = 0.001) subscales. No significant difference regarding the mean improvement in the Lysholm knee score was found between the two grafts (BPTB group: 14.5, HT group: 14.0; n.s.). No correlation between postoperative anterior knee laxity and PROMs was found in either graft group.

CONCLUSION

Primary ACLR performed with HT autograft resulted in greater postoperative anterior knee laxity and significantly more surgical failures (STS > 5 mm) compared with BPTB autograft. The BPTB autograft showed a larger anterior knee laxity reduction (ATT reduction) in conjunction with primary ACLR. The HT autograft led to a significantly larger improvement in four of five KOOS subscales from preoperatively to the 1-year follow-up, compared with BPTB autograft. There was no association between postoperative anterior knee laxity and PROMs for either graft. The findings of the present study provide clinicians with valuable information regarding differences in knee laxity and subjective knee function between BPTB and HT autograft after primary ACLR. The use of BPTB autograft should be considered for patients with high knee stability demands.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

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.

Patients older than 50 years had similar results of knee strength and anteroposterior stability after ACL reconstruction compared to younger patients

PURPOSE

To evaluate knee strength, ligament stability, and functional outcomes in patients older than 50 years who underwent anterior cruciate ligament (ACL) reconstruction, and to compare these results with those obtained from a younger patient group (< 40 years).

METHODS

Forty patients older than 50 years and 50 patients younger than 40 years who underwent ACL reconstruction were retrospectively studied. Isokinetic extensor and flexor muscle strength were evaluated. The peak torque was determined at speeds of 60°/s and 180°/s. The highest peak torque at each velocity was compared with that on the uninjured side. Patients were also evaluated for knee anteroposterior (AP) laxity and functional outcomes, which were measured by the Lysholm and International Knee Documentation Committee (IKDC) scores. All tests were evaluated at baseline and 1 year postoperatively.

RESULTS

The groups were comparable at the baseline. Both groups had significant improvements in all parameters, including isokinetic muscle strength, AP laxity, and functional scores, at 1 year postoperatively (all p < 0.05). Compared with younger patients, older patients had similar results for extensor and flexor strength, AP laxity, and Lysholm score (n.s.). However, younger patients had better IKDC scores than did older patients [median 81.1; 95% confidence interval (CI) 95% CI 78.9-88.7 vs. median 75.6; 95% CI 70.1-79.3, p = 0.007].

CONCLUSIONS

Though with lower IKDC scores, older patients with ACL reconstruction had comparable results of knee strength and ligament laxity to younger patients. ACL reconstruction is recommended for treating patients older than 50 years with ACL insufficiency, especially for those with high functional demand.

LEVEL OF EVIDENCE

Retrospective cohort study, III.

No association between positive intraoperative allograft cultures and infection rates after reconstructive knee ligament surgery

BACKGROUND

Several reports of severe infections associated with allograft tissue in knee reconstructive surgery have led many surgeons to consider routine intraoperative culture of allograft tissue before implantation. Thus, the purpose of this study was to determine the prevalence of positive soft tissue allograft cultures in reconstructive knee surgery, and evaluate its association with surgical site infection.

METHODS

Retrospective study of 202 patients who underwent knee reconstructive ligament surgeries, including revisions, between January 2013 and July 2017. Intraoperative culture results were obtained and the report of a surgical site infection during follow-up was recorded. Patients without cultures were excluded. A priori power analysis was performed. The association between positive culture results and development of surgical site infection was evaluated using Fisher's Exact test (P < 0.05).

RESULTS

A total of 300 allografts were implanted in 202 patients. Mean average follow-up was 32.9 ± 12.5 (range 13 to 57.9) months. Sixteen patients had positive intraoperative allograft cultures (7.9%). The most frequently isolated organism was Bacillus species (six cultures); none of these patients presented with clinical signs of infection. Nine patients developed surgical site infections and were treated with oral antibiotics, and one patient developed septic arthritis that required surgical debridement of the implanted graft; all of these patients had a negative soft tissue allograft culture. No significant association was found between a positive culture and surgical site infection (P = 0.43).

CONCLUSION

There was no apparent association between positive intraoperative irradiated soft tissue allograft cultures and surgical site infection in reconstructive knee surgery.

Three-dimensional characterization of the microstructure in rabbit patella-patellar tendon interface using propagation phase-contrast synchrotron radiation microtomography

Understanding the three-dimensional ultrastructure morphology of tendon-to-bone interface may allow the development of effective therapeutic interventions for enhanced interface healing. This study aims to assess the feasibility of propagation phase-contrast synchrotron radiation microtomography (PPC-SRµCT) for three-dimensional characterization of the microstructure in rabbit patella-patellar tendon interface (PPTI). Based on phase retrieval for PPC-SRµCT imaging, this technique is capable of visualizing the three-dimensional internal architecture of PPTI at a cellular high spatial resolution including bone and tendon, especially the chondrocytes lacuna at the fibrocartilage layer. The features on the PPC-SRµCT image of the PPTI are similar to those of a histological section using Safranin-O staining/fast green staining. The three-dimensional microstructure in the rabbit patella-patellar tendon interface and the spatial distributions of the chondrocytes lacuna and their quantification volumetric data are displayed. Furthermore, a color-coding map differentiating cell lacuna in terms of connecting beads is presented after the chondrocytes cell lacuna was extracted. This provides a more in-depth insight into the microstructure of the PPTI on a new scale, particularly the cell lacuna arrangement at the fibrocartilage layer. PPC-SRµCT techniques provide important complementary information to the conventional histological method for characterizing the microstructure of the PPTI, and may facilitate in investigations of the repair mechanism of the PPTI after injury and in evaluating the efficacy of a different therapy.

Long-Term Results of Anterior Cruciate Ligament Reconstruction Using Hamstring Grafts and the Outside-In Technique: A Comparison Between 5- and 15-Year Follow-up

Background:

Increased femoral tunnel widening and weakness of the hamstring muscles postoperatively have been described as potential adverse events after anterior cruciate ligament (ACL) reconstruction (ACLR) with a hamstring graft. Meniscectomy and cartilage lesions are important factors for the development of degenerative osteoarthritis.

Purpose:

To compare 15-year follow-up data with 5-year follow-up data from the same cohort of patients after ACLR with a hamstring autograft using an outside-in technique.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 72 patients who underwent anatomic ACLR with a quadruple hamstring graft and an outside-in technique were selected for this prospective study. Patients were reviewed at a minimum follow-up of 15 years. Results were compared with the same series of patients previously reviewed at 5 years after surgery. Lysholm, International Knee Documentation Committee (IKDC), and Tegner scores as well as KT-1000 arthrometer measurements were obtained at final follow-up. Comparative weightbearing radiographs were obtained and analyzed according to the Fairbank, Kellgren-Lawrence, and IKDC classifications and used for the tunnel evaluation.

Results:

No significant difference was detected on the subjective evaluation. Objectively, patients categorized as A or B according to the IKDC score were not significantly different at 5 and 15 years (P < .01). A KT-1000 arthrometer side-to-side manual maximum difference >5 mm, a pivot shift >2+, any giving-way episode, and ACL revision surgery were considered as failures, and these were noted in 6 patients at 5 years and 6 patients at 15 years. The radiological evaluation at 15 years showed a higher rate of osteoarthritis in 2 of 3 radiological scales used in the study compared with results at 5-year follow-up (P < .01). At 15-year follow-up, there was a statistically significant reduction in the mean tibial tunnel diameter (P < .01).

Conclusion:

Endoscopic single-bundle ACLR using hamstring grafts and an outside-in technique demonstrated good results at 15-year follow-up in terms of subjective, objective, and radiographic evaluations. As compared with 5-year follow-up, clinical results remained stable both subjectively and objectively. However, a progression of osteoarthritis changes was observed, especially in patients in whom meniscectomy had been performed.

Risk Factors for Abnormal Anteroposterior Knee Laxity After Primary Anterior Cruciate Ligament Reconstruction

PURPOSE

To identify preoperative and intraoperative factors associated with abnormal anterior knee laxity after primary anterior cruciate ligament (ACL) reconstruction.

METHODS

A total of 5,462 patients who underwent primary ACL reconstruction at our institution from January 2000 to October 2015, with no associated ligament injuries, were included. Demographic data, information regarding graft used, concomitant meniscal surgery, and instrumented laxity were reviewed. The KT-1000 arthrometer, with an anterior tibial load of 134 N, was used to evaluate knee laxity preoperatively and at 6-month follow-up. Patients were considered to have abnormal anterior knee laxity if the postoperative side-to-side difference was greater than 5 mm (International Knee Documentation Committee laxity grade C or D). A logistic regression analysis was used to evaluate whether patient age, gender, preoperative knee laxity, graft type, and presence of medial or lateral meniscus resection or suture were risk factors for abnormal knee laxity.

RESULTS

The risk of having abnormal anterior knee laxity was significantly related to younger age (<30 years) (odds ratio [OR] 1.44; 95% confidence interval [CI], 1.07-1.95; P = .016), preoperative side-to-side difference greater than 5 mm (OR, 6.57; 95% CI, 4.94-8.73; P < .001), hamstring tendon graft (OR, 1.83; 95% CI, 1.08-3.11; P = .025), and medial meniscus resection (OR, 2.22; 95% CI, 1.61-3.07; P < .001). Female gender (OR, 0.96; 95% CI, 0.72-1.28; P = .80), medial meniscus suture (OR, 0.82; 95% CI 0.42-1.62; P = .58), lateral meniscus resection (OR, 0.73; 95% CI 0.49-1.10; P = .13), and lateral meniscus suture (OR, 0.99; 95% CI, 0.46-2.11; P = .98) were not associated with increased risk of abnormal knee laxity.

CONCLUSIONS

Age less than 30 years, preoperative side-to-side difference greater than 5 mm, hamstring tendon graft, and medial meniscus resection are associated with increased risk of having abnormal anterior knee laxity 6 months after primary ACL reconstruction.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.