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  • Journal article
    Parkes M, Tallia F, Young G, Cann P, Jones J, Jeffers Jet al., 2021,

    Tribological evaluation of a novel hybrid for repair of articular cartilage defects

    , Materials Science and Engineering C: Materials for Biological Applications, Vol: 119, Pages: 1-10, ISSN: 0928-4931

    The friction and wear properties of silica/poly(tetrahydrofuran)/poly(ε-caprolactone) (SiO2/PTHF/PCL-diCOOH) hybrid materials that are proposed as cartilage tissue engineering materials were investigated against living articular cartilage. A testing rig was designed to allow testing against fresh bovine cartilage. The friction force and wear were compared for five compositions of the hybrid biomaterial articulating against freshly harvested bovine cartilage in diluted bovine calf serum. Under a non-migrating contact, the friction force increased and hence shear force applied to the opposing articular cartilage also increased, resulting in minor damage to the cartilage surface. This worse case testing scenario was used to discriminate between material formulations and revealed the increase in friction and damaged area was lowest for the hybrid containing the most silica. Further friction and wear tests on one hybrid formulation with an elastic modulus closest to that of cartilage were then conducted in a custom incubator system. This demonstrated that over a five day period the friction force, cell viability and glucosaminoglycan (GAG) release into the lubricant were similar between a cartilage-cartilage interface and the hybrid-cartilage interface, supporting the use of these materials for cartilage repair. These results demonstrate how tribology testing can play a part in the development of new materials for chondral tissue engineering.

  • Journal article
    Munford MJ, Ng KCG, Jeffers JRT, 2020,

    Mapping the Multi-Directional Mechanical Properties of Bone in the Proximal Tibia

    , ADVANCED FUNCTIONAL MATERIALS, ISSN: 1616-301X
  • Journal article
    Clark J, Heyraud A, Tavana S, Al-Jabri T, Tallia F, Clark B, Blunn G, Cobb J, Hansen U, Jones J, Jeffers Jet al., 2020,

    Exploratory full-field mechanical analysis across the osteochondral tissue– biomaterial interface in an ovine model

    , Materials, Vol: 13, ISSN: 1996-1944

    Osteochondral injuries are increasingly prevalent, yet success in articular cartilage regeneration remains elusive, necessitating the development of new surgical interventions and novel medical devices. As part of device development, animal models are an important milestone in illustrating functionality of novel implants. Inspection of the tissue-biomaterial system is vital to understand and predict load-sharing capacity, fixation mechanics and micromotion, none of which are directly captured by traditional post-mortem techniques. This study aims to characterize the localised mechanics of an ex vivo ovine osteochondral tissue–biomaterial system extracted following six weeks in vivo testing, utilising laboratory micro-computed tomography, in situ loading and digital volume correlation. Herein, the full-field displacement and strain distributions were visualised across the interface of the system components, including newly formed tissue. The results from this exploratory study suggest that implant micromotion in respect to the surrounding tissue could be visualised in 3D across multiple loading steps. The methodology provides a non-destructive means to assess device performance holistically, informing device design to improve osteochondral regeneration strategies.

  • Journal article
    Clark J, Tavana S, Heyraud A, Tallia F, Jones J, Hansen U, Jeffers Jet al., 2020,

    Quantifying 3D strain in scaffold implants for regenerative medicine

    , Materials, Vol: 13, ISSN: 1996-1944

    Regenerative medicine solutions require thoughtful design to elicit the intended biological response. This includes the biomechanical stimulus to generate an appropriate strain in the scaffold and surrounding tissue to drive cell lineage to the desired tissue. To provide appropriate strain on a local level, new generations of scaffolds often involve anisotropic spatially graded mechanical properties that cannot be characterised with traditional materials testing equipment. Volumetric examination is possible with three-dimensional (3D) imaging, in situ loading and digital volume correlation (DVC). Micro-CT and DVC were utilised in this study on two sizes of 3D-printed inorganic/organic hybrid scaffolds (n = 2 and n = 4) with a repeating homogenous structure intended for cartilage regeneration. Deformation was observed with a spatial resolution of under 200 µm whilst maintaining displacement random errors of 0.97 µm, strain systematic errors of 0.17% and strain random errors of 0.031%. Digital image correlation (DIC) provided an analysis of the external surfaces whilst DVC enabled localised strain concentrations to be examined throughout the full 3D volume. Strain values derived using DVC correlated well against manually calculated ground-truth measurements (R2 = 0.98, n = 8). The technique ensures the full 3D micro-mechanical environment experienced by cells is intimately considered, enabling future studies to further examine scaffold designs for regenerative medicine.

  • Journal article
    Ng KCG, Bankes M, El Daou H, Rodriguez y Baena F, Jeffers Jet al., 2020,

    Cam osteochondroplasty for femoroacetabular impingement increases microinstability in deep flexion: A cadaveric study

    , Arthroscopy: The Journal of Arthroscopy and Related Surgery, ISSN: 0749-8063

    Purpose: The purpose of this in vitro cadaveric study was to examine the contributions of each surgical stage during cam femoroacetabular impingement (FAI) surgery (i.e., intact cam hip, T8 capsulotomy, cam resection, capsular repair) towards hip range of motion, translations, and microinstability.Methods: Twelve cadaveric cam hips were denuded to the capsule and mounted onto a robotic tester. Hips were positioned in several flexion positions: Full Extension, Neutral 0°, Flexion 30°, and Flexion 90°; and performed internal-external rotations to 5-Nm torque in each position. Hips underwent a series of surgical stages (T-capsulotomy, cam resection, capsular repair) and was retested after each stage. Changes in range of motion, translation, and microinstability (overall translation normalized by femoral head radius) were measured after each stage.Results: For range of motion, cam resection increased internal rotation at Flexion 90° (ΔIR = +6°, P = .001), but did not affect external rotation. Capsular repairs restrained external rotations compared to the cam resection stage (ΔER = –4 to –8°, P ≤ .04). For translations, the hip translated after cam resection at Flexion 90° in the medial-lateral plane (ΔT = +1.9 mm, P = .04), relative to the intact and capsulotomy stages. For microinstability, capsulotomy increased microinstability in Flexion 30° (ΔM = +0.05; P = .003), but did not further increase after cam resection. At Flexion 90°, microinstability did not increase after capsulotomy (ΔM = +0.03; P = .2, d = .24), but substantially increased after cam resection (ΔM = +0.08; P = .03), accounting for a 31% change with respect to the intact stage.Conclusions: Cam resection increased microinstability by 31% during deep hip flexion relative to the intact hip. This suggests that iatrogenic microinstability may be due to separation of the labral seal and resected contour of the femoral head.

  • Journal article
    Athwal KK, Willinger L, Shinohara S, Ball S, Williams A, Amis AAet al., 2020,

    The bone attachments of the medial collateral and posterior oblique ligaments are defined anatomically and radiographically

    , Knee Surgery Sports Traumatology Arthroscopy, Pages: 1-11, ISSN: 0942-2056

    PurposeTo define the bony attachments of the medial ligaments relative to anatomical and radiographic bony landmarks, providing information for medial collateral ligament (MCL) surgery.MethodThe femoral and tibial attachments of the superficial MCL (sMCL), deep MCL (dMCL) and posterior oblique ligament (POL), plus the medial epicondyle (ME) were defined by radiopaque staples in 22 knees. These were measured radiographically and optically; the precision was calculated and data normalised to the sizes of the condyles. Femoral locations were referenced to the ME and to Blumensaat’s line and the posterior cortex.ResultsThe femoral sMCL attachment enveloped the ME, centred 1 mm proximal to it, at 37 ± 2 mm (normalised at 53 ± 2%) posterior to the most-anterior condyle border. The femoral dMCL attachment was 6 mm (8%) distal and 5 mm (7%) posterior to the ME. The femoral POL attachment was 4 mm (5%) proximal and 11 mm (15%) posterior to the ME. The tibial sMCL attachment spread from 42 to 71 mm (81–137% of A-P plateau width) below the tibial plateau. The dMCL fanned out anterodistally to a wide tibial attachment 8 mm below the plateau and between 17 and 39 mm (33–76%) A-P. The POL attached 5 mm below the plateau, posterior to the dMCL. The 95% CI intra-observer was ± 0.6 mm, inter-observer ± 1.3 mm for digitisation. The inter-observer ICC for radiographs was 0.922.ConclusionThe bone attachments of the medial knee ligaments are located in relation to knee dimensions and osseous landmarks. These data facilitate repairs and reconstructions that can restore physiological laxity and stability patterns across the arc of knee flexion.

  • Journal article
    Williams A, Becker R, Amis A, 2020,

    The medial collateral ligament: the neglected ligament

    , Knee Surgery, Sports Traumatology, Arthroscopy, ISSN: 0942-2056
  • Journal article
    Doyle R, van Arkel RJ, Muirhead-Allwood S, Jeffers JRTet al., 2020,

    Impaction technique influences implant stability in low-density bone model

    , BONE & JOINT RESEARCH, Vol: 9, Pages: 386-393, ISSN: 2046-3758
  • Journal article
    Willinger L, Shinohara S, Athwal KK, Ball S, Williams A, Amis AAet al., 2020,

    Length-change patterns of the medial collateral ligament and posterior oblique ligament in relation to their function and surgery

    , Arthroskopie, Vol: 33, Pages: 288-294, ISSN: 0933-7946

    PurposeThe purpose of this study was to define the length-change patterns of the superficial medial collateral ligament (sMCL), deep MCL (dMCL), and posterior oblique ligament (POL) across knee flexion and with applied anterior and rotational loads.Material and methodsTen cadaveric knees were mounted in a kinematics rig with loaded quadriceps and hamstrings muscles. Length change patterns of the anterior and posterior fibres of the sMCL, dMCL and POL were recorded from 0 to 100° flexion. Length changes were recorded while a 90 N anterior load and a 5 Nm internal and external rotational torque were applied. Length changes were normalized to lengths at 0° flexion.ResultsThe anterior sMCL tightened as the knee was flexed (p < 0.01), and further tensioned under tibial external rotation (p < 0.001). Conversely, the posterior sMCL slackened with flexion (p < 0.001), while internal rotation tightened these fibers between 10 and 100° (p < 0.05). Tibial external rotation significantly lengthened the anterior dMCL fibres by 10% compared to the unloaded condition throughout flexion (p < 0.001). Release of the sMCL caused the dMCL fibres to become taut and increased valgus rotation (p < 0.01). The lengths of the anterior and posterior POL fibres decreased continuously with knee flexion (p < 0.001). Tibial internal rotation significantly increased the length of the POL (p < 0.001).ConclusionThe structures of the medial ligament complex reacted differently to knee flexion and applied loads. Structures attaching proximal and posterior to the medial epicondyle were taut in extension, whereas the anterior sMCL tensioned during flexion. The anterior dMCL was extensively strained by tibial external rotation and after sMCL release.

  • Journal article
    Ball S, Stephen JM, El-Daou H, Williams A, Amis AAet al., 2020,

    The medial ligaments and the ACL restrain anteromedial laxity of the knee

    , Knee Surgery Sports Traumatology Arthroscopy, Pages: 1-9, ISSN: 0942-2056

    PurposeThe purpose of this study was to determine the contribution of each of the ACL and medial ligament structures in resisting anteromedial rotatory instability (AMRI) loads applied in vitro.MethodsTwelve knees were tested using a robotic system. It imposed loads simulating clinical laxity tests at 0° to 90° flexion: ±90 N anterior–posterior force, ±8 Nm varus–valgus moment, and ±5 Nm internal–external rotation, and the tibial displacements were measured in the intact knee. The ACL and individual medial structures—retinaculum, superficial and deep medial collateral ligament (sMCL and dMCL), and posteromedial capsule with oblique ligament (POL + PMC)—were sectioned sequentially. The tibial displacements were reapplied after each cut and the reduced loads required allowed the contribution of each structure to be calculated.ResultsFor anterior translation, the ACL was the primary restraint, resisting 63–77% of the drawer force across 0° to 90°, the sMCL contributing 4–7%. For posterior translation, the POL + PMC contributed 10% of the restraint in extension; other structures were not significant. For valgus load, the sMCL was the primary restraint (40–54%) across 0° to 90°, the dMCL 12%, and POL + PMC 16% in extension. For external rotation, the dMCL resisted 23–13% across 0° to 90°, the sMCL 13–22%, and the ACL 6–9%.ConclusionThe dMCL is the largest medial restraint to tibial external rotation in extension. Therefore, following a combined ACL + MCL injury, AMRI may persist if there is inadequate healing of both the sMCL and dMCL, and MCL deficiency increases the risk of ACL graft failure.

  • Journal article
    Amis A, Willinger L, Shinohara S, Athwal K, Ball S, Williams Aet al., 2020,

    Length change patterns of the medial collateral ligament and posterior oblique ligament in relation to their function and surgery

    , Knee Surgery Sports Traumatology Arthroscopy, ISSN: 0942-2056

    PurposeTo define the length-change patterns of the superficial medial collateral ligament (sMCL), deep MCL (dMCL), and posterior oblique ligament (POL) across knee flexion and with applied anterior and rotational loads, and to relate these findings to their functions in knee stability and to surgical repair or reconstruction.MethodsTen cadaveric knees were mounted in a kinematics rig with loaded quadriceps, ITB, and hamstrings. Length changes of the anterior and posterior fibres of the sMCL, dMCL, and POL were recorded from 0° to 100° flexion by use of a linear displacement transducer and normalised to lengths at 0° flexion. Measurements were repeated with no external load, 90 N anterior draw force, and 5 Nm internal and 5 Nm external rotation torque applied.ResultsThe anterior sMCL lengthened with flexion (p < 0.01) and further lengthened by external rotation (p < 0.001). The posterior sMCL slackened with flexion (p < 0.001), but was lengthened by internal rotation (p < 0.05). External rotation lengthened the anterior dMCL fibres by 10% throughout flexion (p < 0.001). sMCL release allowed the dMCL to become taut with valgus rotation (p < 0.001). The anterior and posterior POL fibres slackened with flexion (p < 0.001), but were elongated by internal rotation (p < 0.001).ConclusionThe structures of the medial ligament complex react differently to knee flexion and applied loads. Structures attaching posterior to the medial epicondyle are taut in extension, whereas the anterior sMCL, attaching anterior to the epicondyle, is tensioned during flexion. The anterior dMCL is elongated by external rotation. These data offer the basis for MCL repair and reconstruction techniques regarding graft positioning and tensioning.

  • Journal article
    Amis A, Joseph M, Carmont M, Stephen J, Tailor Het al., 2020,

    Total knee arthroplasty reduces knee extension torque in-vitro and patellofemoral arthroplasty does not

    , Journal of Biomechanics, Vol: 104, Pages: 1-6, ISSN: 0021-9290

    Patients often have difficulty recovering knee extension strength post total knee arthroplasty (TKA), and that may reflect alteration of the mechanics including geometry and rollback kinematics, so the purpose of this work was to explore this by comparing the knee extension torque (KET) of the native knee, TKA and patellofemoral arthroplasty (PFA) in response to quadriceps tension. Eight fresh-frozen knees were mounted in a knee extension rig with quadriceps loading and tibial extension torque measurement. Each knee was subject to four conditions: native knee, PFA, cruciate-retaining (CR) and posterior-stabilized (PS) TKA. The KET was measured from 120° to 0° knee flexion. Data were analyzed using one-way ANOVA and post-hoc paired t-tests. The native KET was lowest in terminal extension and 70–100° flexion, and maximal at 20–30° flexion. PFA produced the greatest KET (p < 0.008) compared with native, CR- and PS-TKA, at 30–40° flexion. CR- and PS-TKA had lower KET across 0–50° flexion (p < 0.001 across 0–30°), falling to 25% of the native knee KET or the PFA at full extension. PFA had the highest KET in early flexion possibly due to increased trochlear offset and/or preservation of the cruciate mechanism, so PFA may be more beneficial during the functional range of motion. The claimed benefits of PS- over CR-TKA in deep flexion were not detected. Both CR- and PS-TKAs led to lower KET than the native and PFA knee states across 0–50° flexion. This mechanical effect may help to explain clinical findings of knee extension weakness post-TKA.

  • Journal article
    Ajdari N, Tempelaere C, Masouleh MI, Abel R, Delfosse D, Emery R, Dini D, Hansen Uet al., 2020,

    Hemiarthroplasties: the choice of prosthetic material causes different levels of damage in the articular cartilage

    , Journal of Shoulder and Elbow Surgery, Vol: 29, Pages: 1019-1029, ISSN: 1058-2746

    Background Hemiarthroplasty has clear advantages over alternative procedures and is used in 20% of all shoulder joint replacements. Because of cartilage wear, the clinical outcome of hemiarthroplasty is unreliable and controversial. This paper suggests that the optimal choice of prosthetic material may reduce cartilage degeneration and improve the reliability of the procedure. The specific objectives were to assess 3 materials and assess how the severity of arthritis might affect the choice of prosthetic material. Methods A CoCr alloy, an AL2O3 ceramic, and a polycarbonate urethane polymer (PCU) were mechanically tested against 5 levels of human osteoarthritic cartilage (from intact to severely arthritic, n = 45). A high friction coefficient, a decrease in Young's modulus, an increase in permeability, a decrease in relaxation time, an increase in surface roughness, and a disrupted appearance of the cartilage after testing were used as measures of cartilage damage. The biomaterial that caused minimal cartilage damage was defined as superior. Results The CoCr caused the most damage. This was followed by the AL2O3 ceramic, whereas the PCU caused the least amount of damage. Although the degree of arthritis had an effect on the results, it did not change the trend that CoCr performed worst and PCU the best. Discussion and Conclusion This study indicates that ceramic implants may be a better choice than metals, and the articulating surface should be as smooth as possible. Although our results indicate that the degree of arthritis should not affect the choice of prosthetic material, this suggestion needs to be further investigated.

  • Journal article
    Athwal KK, Willinger L, Manning W, Deehan D, Amis AAet al., 2020,

    A constrained-condylar fixed-bearing total knee arthroplasty is stabilised by the medial soft tissues

    , Knee Surgery Sports Traumatology Arthroscopy, ISSN: 0942-2056

    PurposeRevision constrained-condylar total knee arthroplasty (CCK-TKA) is often used to provide additional mechanical constraint after failure of a primary TKA. However, it is unknown how much this translates to a reliance on soft-tissue support. The aim of this study was therefore to compare the laxity of a native knee to the CCK-TKA implanted state and quantify how medial soft-tissues stabilise the knee following CCK-TKA.MethodsTen intact cadaveric knees were tested in a robotic system at 0°, 30°, 60° and 90° flexion with ± 90 N anterior–posterior force, ± 8 Nm varus-valgus and ± 5 Nm internal–external torques. A fixed-bearing CCK-TKA was implanted and the laxity tests were repeated with the soft tissues intact and after sequential cutting. The deep and superficial medial collateral ligaments (dMCL, sMCL) and posteromedial capsule (PMC) were sequentially transected and the percentage contributions of each structure to restraining the applied loads were calculated.ResultsImplanting a CCK-TKA did not alter anterior–posterior laxity from that of the original native knee, but it significantly decreased internal–external and varus-valgus rotational laxity (p < 0.05). Post CCK-TKA, the sMCL restrained 34% of the tibial displacing load in anterior drawer, 16% in internal rotation, 17% in external rotation and 53% in valgus, across the flexion angles tested. The dMCL restrained 11% of the valgus rotation moment.ConclusionsWith a fully-competent sMCL in-vitro, a fixed-bearing CCK-TKA knee provided more rotational constraint than the native knee. The robotic test data showed that both the soft-tissues and the semi-constrained implant restrained rotational knee laxity. Therefore, in clinical practice, a fixed-bearing CCK-TKA knee could be indicated for use in a knee with lax, less-competent medial soft tissues.

  • Journal article
    Ruiz de Galarreta S, Jeffers JRT, Ghouse S, 2020,

    A validated finite element analysis procedure for porous structures

    , MATERIALS & DESIGN, Vol: 189, ISSN: 0264-1275
  • Journal article
    Lagae KC, Robberecht J, Athwal KK, Verdonk PCM, Amis AAet al., 2020,

    ACL reconstruction combined with lateral monoloop tenodesis can restore intact knee laxity

    , Knee Surgery Sports Traumatology Arthroscopy, Vol: 28, Pages: 1159-1168, ISSN: 0942-2056

    PurposeAn anterior cruciate ligament (ACL) injury is often combined with injury to the lateral extra-articular structures, which may cause a combined anterior and rotational laxity. It was hypothesised that addition of a ‘monoloop’ lateral extra-articular tenodesis (mLET) to an ACL reconstruction would restore anteroposterior, internal rotation and pivot-shift laxities better than isolated ACL reconstruction in combined injuries.MethodTwelve cadaveric knees were tested, using an optical tracking system to record the kinematics through 0°–100° of knee flexion with no load, anterior and posterior translational forces (90 N), internal and external rotational torques (5 Nm), and a combination of an anterior translational (90 N) plus internal rotational load (5 Nm). They were tested intact, after sectioning the ACL, sectioning anterolateral ligament (ALL), iliotibial band (ITB) graft harvest, releasing deep ITB fibres, hamstrings tendon ACL reconstruction, mLET combined with ACL reconstruction, and isolated mLET. Two-way repeated-measures ANOVA compared laxity data across knee states and flexion angles. When differences were found, paired t tests with Bonferroni correction were performed.ResultsIn the ACL-deficient knee, cutting the ALL significantly increased anterior laxity only at 20°–30°, and only significantly increased internal rotation at 50°. Additional deep ITB release significantly increased anterior laxity at 40°–90° and caused a large increase of internal rotation at 20°–100°. Isolated ACL reconstruction restored anterior drawer, but significant differences remained in internal rotation at 30°–100°. After adding an mLET there were no remaining differences with anterior translation or internal rotation compared to the intact knee. With the combined injury, isolated mLET allowed abnormal anterior translation and rotation to persist.ConclusionsCutting the deep fibres of the ITB

  • Journal article
    Munford M, Hossain U, Ghouse S, Jeffers JRTet al., 2020,

    Prediction of anisotropic mechanical properties for lattice structures

    , ADDITIVE MANUFACTURING, Vol: 32, ISSN: 2214-8604
  • Journal article
    Huber C, Zhang Q, Taylor WR, Amis AA, Smith C, Hosseini Nasab SHet al., 2020,

    Properties and function of the medial patellofemoral ligament: A systematic review

    , American Journal of Sports Medicine, Vol: 48, Pages: 754-766, ISSN: 0363-5465

    BACKGROUND: As the main passive structure preventing patellar lateral subluxation, accurate knowledge of the anatomy, material properties, and functional behavior of the medial patellofemoral ligament (MPFL) is critical for improving its reconstruction. PURPOSE: To provide a state-of-the-art understanding of the properties and function of the MPFL by undertaking a systematic review and statistical analysis of the literature. STUDY DESIGN: Systematic review. METHODS: On June 26, 2018, data for this systematic review were obtained by searching PubMed and Scopus. Articles containing numerical information regarding the anatomy, mechanical properties, and/or functional behavior of the MPFL that met the inclusion criteria were reviewed, recorded, and statistically evaluated. RESULTS: A total of 55 articles met the inclusion criteria for this review. The MPFL presented as a fanlike structure spanning from the medial femoral epicondyle to the medial border of the patella. The reported data indicated ultimate failure loads from 72 N to 208 N, ultimate failure elongation from 8.4 mm to 26 mm, and stiffness values from 8.0 N/mm to 42.5 N/mm. In both cadaveric and in vivo studies, the average elongation pattern demonstrated close to isometric behavior of the ligament in the first 50° to 60° of knee flexion, followed by progressive shortening into deep flexion. Kinematic data suggested clear lateralization of the patella in the MPFL-deficient knee during early knee flexion under simulated muscle forces. CONCLUSION: A lack of knowledge regarding the morphology and attachment sites of the MPFL remains. The reported mechanical properties also lack consistency, thus requiring further investigations. However, the results regarding patellar tracking confirm that the lack of an MPFL leads to lateralization of the patella, followed by delayed engagement of the trochlear groove, plausibly leading to an increased risk of patellar dislocations. The observed isometric behavior up to

  • Book chapter
    Ng KCG, Bankes MJK, Cobb J, Jeffers Jet al., 2020,

    Biomechanics of the Native Hip from Normal to Instability

    , Hip Dysplasia Understanding and Treating Instability of the Native Hip, Editors: Beaulé, Publisher: Springer, Pages: 55-70, ISBN: 9783030333577

    This book represents the most advanced understanding of diagnosis and management of hip dysplasia in the young adult, written by the world’s leading experts and covering advanced imaging and biomechanical studies as well as latest ...

  • Journal article
    Eljaja SB, Konradsen L, Siersma VD, Athwal K, Amis AA, Krogsgaard MRet al., 2020,

    Reconstruction of the anterior cruciate- and anterolateral ligament deficient knee with a modified iliotibial graft reduces instability more than with an intra-articular hamstring graft

    , Knee Surgery Sports Traumatology Arthroscopy, Vol: 28, Pages: 2526-2534, ISSN: 0942-2056

    PURPOSE: To compare knee kinematics before and after anterior cruciate ligament ACL reconstruction (ACL-R) using hamstring graft (HG) and a double-stranded iliotibial tract graft attached to Gerdy's tubercle (providing an extra-articular anterolateral tenodesis) (named the modified iliotibial tract graft = MIT). METHOD: Eighteen cadaveric knees were tested in a 6 degree of freedom kinematics rig. An optical tracking system recorded kinematics of the knee from 0 to 80 degrees of flexion applying no load, internal/external rotation (IR/ER), valgus/varus rotation (VGR/VRR), simulated pivot shift (SPS), anterior translation (AT) and posterior translation loads. The knee was tested before and after resection of the ACL and the anterolateral ligament (ALL), respectively; then after HG-ACL-R and MIT-ACL-R. Grafts were fixed at 20° of flexion. Results were compared to the intact knee. RESULTS: ACL resection resulted in a significant increase in AT (p < 0.05) over the entire range of motion, peaking at 20° of flexion, mean difference 6.6 ± 2.25 mm (p = 0.0007). ACL-R with HG-ACL and MIT-ACL restored AT. Resection of the ALL increased IR in the fully extended knee, mean difference 2.4 ± 2.1° (p = 0.024). When compared to the intact knee and the knee after HG-ACL-R, MIT-ACL-R knee reduced IR/SPS significantly (p < 0.05) in deep flexion angles (60°-80°), peaking at 80° of flexion. The MIT-ACL-R caused significantly less VRR at 80° flexion (p = 0.02). CONCLUSION: MIT-ACL-R restored AT equally to the HG-ACL-R. The MIT-ACL-R reduced IR and SPS in deep flexion, resulting in overconstraint. MIT-ACL-R can be used as an alternative to standard reconstruction methods.

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