Imperial College London

DrHadiEl Daou

Faculty of EngineeringDepartment of Mechanical Engineering

Research Associate
 
 
 
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h.el-daou

 
 
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City and Guilds BuildingSouth Kensington Campus

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Publications

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27 results found

Lee J, El-Daou H, Alkoheji M, Carlos A, Di Mascio L, Amis Aet al., 2021, Ligamentous and capsular restraints to anterior posterior and superior inferior laxity of the acromioclavicular joint - a biomechanical study, Journal of Shoulder and Elbow Surgery, Vol: 30, Pages: 1251-1256, ISSN: 1058-2746

BACKGROUND: Approximately 9% of shoulder girdle injuries involve the acromioclavicular joint (ACJ). There is no clear gold standard or consensus on surgical management of these injuries, in part perpetuated by our incomplete understanding of native ACJ biomechanics. We have therefore conducted a biomechanical study to assess the stabilizing structures of the ACJ in superior-inferior (SI) and anterior-posterior (AP) translation. METHODS: Twenty fresh frozen cadaver specimens were prepared and mounted to a robotic arm. The intact native joint was tested in SI and AP translations under 50N displacing force. Each specimen was re-tested after sectioning of its stabilizing structures in the following order; investing fascia, ACJ capsular ligaments, trapezoid ligament, and conoid ligament. Their contributions to resisting ACJ displacements were calculated. RESULTS: In the intact native ACJ, mean anterior displacement of the clavicle was 7.9 +/- 4.3mm, mean posterior displacement was 7.2 +/- 2.6mm, mean superior displacement 5.8 +/- 3.0mm, and mean inferior displacement 3.6 +/- 2.6mm. The conoid ligament was the primary stabilizer of superior displacement (45.6%). The ACJ capsular ligament was the primary stabilizer of inferior displacement (33.8%). The capsular ligament and conoid ligament contributed equally to anterior stability, with 23% and 25.2% respectively. The capsular ligament was the primary contributor to posterior stability (38.4%). CONCLUSION: The conoid ligament is the primary stabilizer of superior displacement of the clavicle at the ACJ and contributes significantly to AP stability. Consideration should be given to reconstruction of the ACJ capsular ligament for complete AP stability in high grade and horizontally unstable ACJ injuries.

Journal article

Stephen JM, Teitge RA, Williams A, Calder JDF, El Daou Het al., 2021, A validated, automated, 3-dimensional method to reliably measure tibial torsion, American Journal of Sports Medicine, Vol: 49, Pages: 747-756, ISSN: 0363-5465

Background:Tibial torsion is a twist in the tibia measured as an angle between a proximal axis line and a distal axis line. Abnormal torsion has been associated with a variety of painful clinical syndromes of the lower limb. Measurements of normal tibial torsion reported by different authors vary by 100% (ranging from 20° to 42°), making it impossible to determine normal and pathological levels.Purpose:To address the problem of unreliable measurements, this study was conducted to define an automated, validated computer method to calculate tibial torsion. Reliability was compared with current clinical methods. The difference between measurements of torsion generated from computed tomography (CT) and magnetic resonance imaging (MRI) scans of the same bone, and between males and females, was assessed.Study Design:Controlled laboratory study.Methods:Previous methods of analyzing tibial torsion were reviewed, and limitations were identified. An automated measurement method to address these limitations was defined. A total of 56 cadaveric and patient tibiae (mean ± SD age, 37 ± 15 years; range, 17-71 years; 28 female) underwent CT scanning, and 3 blinded assessors made torsion measurements by applying 2 current clinical methods and the automated method defined in the present article. Intraclass correlation coefficient (ICC) values were calculated. Further, 12 cadaveric tibiae were scanned by MRI, stripped of tissue, and measured using a structured light (SL) scanner. Differences between torsion values obtained from CT, SL, and MRI scans, and between males and females, were compared using t tests. SPSS was used for all statistical analysis.Results:When the automated method was used, the tibiae had a mean external torsion of 29°± 11° (range, 9°-65). Automated torsion assessment had excellent reliability (ICC, 1), whereas current methods had good reliability (ICC, 0.78-0.81). No significant difference was found between the torsion val

Journal article

Ng KCG, Bankes M, El Daou H, Rodriguez y Baena F, Jeffers Jet al., 2021, Cam osteochondroplasty for femoroacetabular impingement increases microinstability in deep flexion: A cadaveric study, Arthroscopy: The Journal of Arthroscopy and Related Surgery, Vol: 37, Pages: 159-170, 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

Stephen JM, Calder JDF, Williams A, El Daou Het al., 2020, Comparative accuracy of lower limb bone geometry determined using MRI, CT, and direct bone 3D models, JOURNAL OF ORTHOPAEDIC RESEARCH, ISSN: 0736-0266

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, Vol: 28, Pages: 3700-3708, 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

Darwood A, Hurst S, Villatte G, Fenton R, Tatti F, El-Daou H, Reilly P, Emery R, Rodriguez Y Baena Fet al., 2019, Towards a commercial system for intraoperative manufacture of patient-specific guides for shoulder arthroplasty, CAOS 2019. The 19th Annual Meeting of the International Society for Computer Assisted Orthopaedic Surgery, Publisher: EasyChair, Pages: 110-114

The accurate placement of orthopaedic implants according to a biomechanically derived preoperative plan is an important consideration in the long-term success of these interventions. Guidance technologies are widely described however, high cost, complex theatre integration, intraoperative inefficiency and functional limitations have prevented the widespread use. A novel, intraoperative mechatronics platform is presented, capable of the rapid, intraoperative manufacture of low-cost patient-specific guides. The device consists of a tableside robot with sterile drapes and some low cost, sterile disposable components. The robot comprises a 3D optical scanner, a three-axis sterile computer numerical control (CNC) drill and a two-axis receptacle into which the disposable consumables may be inserted. The sterile consumable comprises a region of rapidly setting moldable material and a clip allowing it to be reversibly attached to the tableside robot. In use, patient computed tomography (CT) imaging is obtained at any point prior to surgery and a surgical plan is created on associated software. This plan describes the axis and positioning of one or more guidewires which may, in turn, locate the prosthesis into position. Intraoperatively, osseous anatomy is exposed, and the sterile disposable is used to rapidly create a mould of the joint surface. Once set, the mould is inserted into the robot and an optical scan of the surface is taken followed by automatic surface registration, bringing the optical scan into the same coordinate frame of reference as the CT data and plan. The CNC drill is orientated such that the drill axis and position exactly matches the planned axis and position with respect to the moulded surface. A guide hole is drilled into the mould blank, which is removed from the robot and placed back into the patient with the moulded surface ensuring exact replacement. A wire is subsequently driven through the guide hole into the osseous anatomy in accordance with

Conference paper

Lord BR, El-Daou H, Zdanowicz U, Smigielski R, Amis AAet al., 2019, The role of fibers within the tibial attachment of the anterior cruciate ligament in restraining tibial displacement, ARTHROSCOPY-THE JOURNAL OF ARTHROSCOPIC AND RELATED SURGERY, Vol: 35, Pages: 2101-2111, ISSN: 0749-8063

PurposeTo evaluate the load-bearing functions of the fibers of the anterior cruciate ligament (ACL) tibial attachment in restraining tibial anterior translation, internal rotation, and combined anterior and internal rotation laxities in a simulated pivot-shift test.MethodsTwelve knees were tested using a robot. Laxities tested were: anterior tibial translation (ATT), internal rotation (IR), and coupled translations and rotations during a simulated pivot-shift. The kinematics of the intact knee was replayed after sequentially transecting 9 segments of the ACL attachment and fibers entering the lateral gutter, measuring their contributions to restraining laxity. The center of effort (COE) of the ACL force transmitted to the tibia was calculated. A blinded anatomic analysis identified the densest fiber area in the attachment of the ACL and thus its centroid (center of area). This centroid was compared with the biomechanical COE.ResultsThe anteromedial tibial fibers were the primary restraint of ATT (84% across 0° to 90° flexion) and IR (61%) during isolated and coupled displacements, except for the pivot-shift and ATT in extension. The lateral gutter resisted 28% of IR at 90° flexion. The anteromedial fibers showed significantly greater restraint of simulated pivot-shift rotations than the central and posterior fibers (P < .05). No significant differences (all <2 mm) were found between the anatomic centroid of the C-shaped attachment and the COE under most loadings.ConclusionsThe peripheral anteromedial fibers were the most important area of the ACL tibial attachment in the restraint of tibial anterior translation and internal rotation during isolated and coupled displacements. These mechanical results matched the C-shaped anteromedial attachment of the dense collagen fibers of the ACL.Clinical RelevanceThe most important fibers in restraining tibial displacements attach to the C-shaped anteromedial area of the native ACL tibial attachment. This findi

Journal article

Ng KCG, El Daou H, Bankes M, Rodriguez y Baena F, Jeffers Jet al., 2019, Hip joint torsional loading before and after cam femoroacetabular impingement surgery, American Journal of Sports Medicine, Vol: 47, Pages: 420-430, ISSN: 0363-5465

Background: Surgical management of cam femoroacetabular impingement (FAI) aims to preserve the native hip and restore joint function, though it is unclear how the capsulotomy, cam deformity, and capsular repair influence joint mechanics to balance functional mobility.Purpose: The purpose was to examine the contributions of the capsule and cam deformity to hip joint mechanics. Using in vitro, cadaveric methods, we examined the individual effects of the surgical capsulotomy, cam resection, and capsular repair towards passive range of motion and resistance of applied torque.Study Design: Descriptive laboratory study.Methods: Twelve cadaveric hips with cam deformities (n = 12) were skeletonized to the capsule and mounted onto a robotic testing platform. The robot positioned each intact hip in multiple testing positions: 1) Extension, 2) Neutral 0°, 3) Flexion 30°, 4) Flexion 90°, 5) flexion-adduction and internal rotation (FADIR), 6) flexion-abduction and external rotation (FABER); and performed applicable internal and external rotations, recording the neutral path of motion until a 5-Nm torque was reached in each rotational direction. Each hip then underwent a series of surgical stages (T-capsulotomy, cam resection, capsular repair) and was retested to reach 5 Nm internal and external torque again after each stage. In addition, during the capsulotomy and cam resection stages, the initial intact hip’s recorded path of motion was replayed to measure changes in resisted torque.Results: Examining changes in motion, external rotation increased substantially after capsulotomies, but internal rotation only further increased at Flexion 90° (change = +32%, P = .001, d = .58) and FADIR (change = +33%, P < .001, d = .51) after cam resections. Capsular repair provided marginal restraint for internal rotation, but restrained the external rotation compared to the capsulotomy stage. Examining changes in torque, both internal and external torque resistance dec

Journal article

El Daou H, Ng KC, van Arkel R, Jeffers J, Rodriguez y Baena Fet al., 2019, Robotic hip joint testing: Development and experimental protocols, Medical Engineering and Physics, Vol: 63, Pages: 57-62, ISSN: 1350-4533

The use of robotic systems combined with force sensing is emerging as the gold standard for in vitro biomechanical joint testing, due to the advantage of controlling all six degrees of freedom independently of one another. This paper describes a novel robotic platform and the experimental protocol used for hip joint testing. An experimental protocol implemented optical tracking and registration techniques in order to define the position of the hip joint centre of rotation (COR) in the coordinate system of the robot's end effector. The COR coordinates defined the origin of the task-related coordinate system used to control the robot, with a hybrid force/position law to simulate standard clinical tests. The axes of this frame were defined using the International Society of Biomechanics (ISB) anatomical coordinate system.Experiments were carried out on two cadaveric hip joint specimens using the robotic testing platform and a mechanical testing rig previously developed and described by our group. Simulated internal-external and adduction/abduction laxity tests were carried out with both systems and the resulting peak range of motion (ROM) was measured. Similarities and differences were observed in these experiments, which were used to highlight some of the limitations of conventional systems and the corresponding advantages of robotics, further emphasising their added value in vitro testing.

Journal article

El Daou H, Calder JD, Stephen JM, 2018, Development and validation of a robotic system for ankle joint testing, MEDICAL ENGINEERING & PHYSICS, Vol: 62, Pages: 53-57, ISSN: 1350-4533

Journal article

Stephen JM, Marsland D, Masc L, Calder JDF, El Daou Het al., 2018, Differential Motion and Compression Between the Plantaris and Achilles Tendons A Contributing Factor to Midportion Achilles Tendinopathy?, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 46, Pages: 955-960, ISSN: 0363-5465

Journal article

El Daou H, Lord B, Amis A, Rodriguez y Baena Fet al., 2017, Assessment of pose repeatability and specimen repositioning of a robotic joint testing platform, MEDICAL ENGINEERING & PHYSICS, Vol: 47, Pages: 210-213, ISSN: 1350-4533

This paper describes the quantitative assessment of a robotic testing platform, consisting of an industrial robot and a universal force-moment sensor, via the design of fixtures used to hold the tibia and femur of cadaveric knees. This platform was used to study the contributions of different soft tissues and the ability of implants and reconstruction surgeries to restore normal joint functions, in previously published literature.To compare different conditions of human joints, it is essential to reposition specimens with high precision after they have been removed for a surgical procedure. Methods and experiments carried out to determine the pose repeatability and measure errors in repositioning specimens are presented. This was achieved using an optical tracking system (fusion Track 500, Atracsys Switzerland) to measure the position and orientation of bespoke rigid body markers attached to the tibial and femoral pots after removing and reinstalling them inside the rigs. The pose repeatability was then evaluated by controlling the robotic platform to move a knee joint repeatedly to/from a given pose while tracking the position and orientation of a rigid body marker attached to the tibial fixture.The results showed that the proposed design ensured a high repeatability in repositioning the pots with standard deviations for the computed distance and angle between the pots at both ends of the joint equal to 0.1 mm, 0.01 mm, 0.13° and 0.03° for the tibial and femoral fixtures respectively. Therefore, it is possible to remove and re-setup a joint with high precision. The results also showed that the errors in repositioning the robotic platform (that is: specimen path repeatability) were 0.11 mm and 0.12°, respectively.

Journal article

Athwal KK, El Daou H, Inderhaug E, Manning W, Davies AJ, Deehan DJ, Amis AAet al., 2017, An in vitro analysis of medial structures and a medial soft tissue reconstruction in a constrained condylar total knee arthroplasty, Knee Surgery Sports Traumatology Arthroscopy, Vol: 25, Pages: 2646-2655, ISSN: 0942-2056

Purpose: The aim of this study was to quantify the medial soft tissue contributions to stability following constrained condylar (CC) total knee arthroplasty (TKA) and determine whether a medial reconstruction could restore stability to a soft tissue-deficient, CC-TKA knee.Methods: Eight cadaveric knees were mounted in a robotic system and tested at 0°, 30°, 60°, and 90° of flexion with ±50 N anterior–posterior force, ±8 Nm varus–valgus, and ±5 Nm internal–external torque. The deep and superficial medial collateral ligaments (dMCL, sMCL) and posteromedial capsule (PMC) were transected and their relative contributions to stabilising the applied loads were quantified. After complete medial soft tissue transection, a reconstruction using a semitendinosus tendon graft was performed, and the effect on kinematic behaviour under equivocal conditions was measured.Results: In the CC-TKA knee, the sMCL was the major medial restraint in anterior drawer, internal–external, and valgus rotation. No significant differences were found between the rotational laxities of the reconstructed knee to the pre-deficient state for the arc of motion examined. The relative contribution of the reconstruction was higher in valgus rotation at 60° than the sMCL; otherwise, the contribution of the reconstruction was similar to that of the sMCL.Conclusion: There is contention whether a CC-TKA can function with medial deficiency or more constraint is required. This work has shown that a CC-TKA may not provide enough stability with an absent sMCL. However, in such cases, combining the CC-TKA with a medial soft tissue reconstruction may be considered as an alternative to a hinged implant.

Journal article

Athwal KK, El Daou H, Inderhaug E, Manning W, Davies AJ, Deehan DJ, Amis AAet al., 2017, Erratum to: An in vitro analysis of medial structures and a medial soft tissue reconstruction in a constrained condylar total knee arthroplasty, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 25, Pages: 2656-2656, ISSN: 0942-2056

Journal article

Inderhaug E, Stephen JM, El-Daou H, Williams A, Amis AAet al., 2017, The Effects of Anterolateral Tenodesis on Tibiofemoral Contact Pressures and Kinematics., American Journal of Sports Medicine, Vol: 45, Pages: 3081-3088, ISSN: 0363-5465

BACKGROUND: Anterolateral tenodeses are increasingly popular in combination with intra-articular anterior cruciate ligament reconstructions. Despite the perception of risk of overconstraint and lateral osteoarthritis, evidence is lacking regarding the effect of graft tensioning on knee kinematics and intra-articular compartmental joint pressures. PURPOSE: To investigate tibiofemoral joint contact pressures and kinematics related to an anterolateral lesion and the effectiveness of a MacIntosh tenodesis in restoring these when varying (1) graft tension and (2) tibial rotation during graft fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Eight fresh-frozen cadaveric knees were tested in a customized rig with femur fixed and tibia free to move from 0° to 90° of flexion. The quadriceps and iliotibial band were loaded by means of a weighted pulley system. At 30° intervals of knee flexion, tibiofemoral contact pressures were measured with a Tekscan sensor and tibiofemoral kinematics were recorded by use of an optical tracking system. The knee was tested intact and then with an anterolateral soft tissue transection. MacIntosh tenodeses were then tested in a randomized order with 20 N or 80 N of graft tension, each with the tibia held in neutral intact alignment or free to rotate. RESULTS: Tibial anterior translation and internal rotation were significantly increased and lateral contact pressures significantly reduced compared with the intact knee following anterolateral soft tissue cutting ( P < .05). Contact pressures were restored with fixed neutral tibial rotation combined with 20 N or 80 N of graft tension or by a free-hanging tibia with 20 N of graft tension (all P values > .5). Grafts tensioned with 80 N caused significant overconstraint both when the tibia was fixed and free hanging (all P values < .05). Increases in the lateral tibiofemoral contact pressures were also seen when the tibia was free hanging and 80 N was used for graft

Journal article

Athwal K, El Daou, Lord B, Davies AJ, Manning W, Rodriguez y Baena, Deehan DJ, Amiset al., 2016, Lateral soft-tissue structures contribute to cruciate-retaining total knee arthroplasty stability., Journal of Orthopaedic Science, Vol: 35, Pages: 1902-1909, ISSN: 0949-2658

Little information is available to surgeons regarding how the lateral structures prevent instability in the replaced knee. The aim of this study was to quantify the lateral soft‐tissue contributions to stability following cruciate‐retaining total knee arthroplasty (CR TKA). Nine cadaveric knees were tested in a robotic system at full extension, 30°, 60°, and 90° flexion angles. In both native and CR implanted states, ±90 N anterior–posterior force, ±8 Nm varus–valgus, and ±5 Nm internal–external torque were applied. The anterolateral structures (ALS, including the iliotibial band), the lateral collateral ligament (LCL), the popliteus tendon complex (Pop T), and the posterior cruciate ligament (PCL) were transected and their relative contributions to stabilizing the applied loads were quantified. The LCL was found to be the primary restraint to varus laxity (an average 56% across all flexion angles), and was significant in internal–external rotational stability (28% and 26%, respectively) and anterior drawer (16%). The ALS restrained 25% of internal rotation, while the PCL was significant in posterior drawer only at 60° and 90° flexion. The Pop T was not found to be significant in any tests. Therefore, the LCL was confirmed as the major lateral structure in CR TKA stability throughout the arc of flexion and deficiency could present a complex rotational laxity that cannot be overcome by the other passive lateral structures or the PCL. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1902–1909, 2017.

Journal article

Lord BR, El-Daou H, Sabnis BM, Gupte CM, Wilson AJ, Amis AAet al., 2016, Erratum to: Biomechanical comparison of graft structures in anterior cruciate ligament reconstruction (vol 25, pg 559, 2017), Knee Surgery, Sports Traumatology, Arthroscopy, Vol: 25, Pages: 988-988, ISSN: 0942-2056

Purpose: Double-bundle (DB) anterior cruciate ligament (ACL) reconstruction may offer kinematic restoration superior to anatomic single bundle (SB), but it remains technically challenging. The femoral attachment site has the most effect on ACL graft isometry, so a simplified three-socket (3S) construct which still uses two sockets to cover the femoral ACL attachment is attractive. It was hypothesised that ACL reconstruction using three- and four-socket techniques would more closely restore native knee kinematics compared to anatomic two-socket (SB) surgery.Methods: Nine cadaveric knees were used to evaluate the kinematics of ACL-intact, ACL-deficient, anatomic SB, three-socket, and DB arthroscopic ACL reconstructions. Suspensory fixation was used, and grafts were tensioned to match the anterior draw of the intact knee at 20°. A six-degree-of-freedom robotic system measured knee laxity under 90 N anterior tibial force and rotational laxity under 5 N-m torque. Combined moments were applied to simulate the pivot-shift subluxation: 4 N-m internal rotation and 8 N-m valgus.Results: Significant differences between reconstructions were not found during anterior tibial loading, apart from SB being more lax than DB at 60° flexion. All reconstructions produced comparable laxity to the intact state, apart from SB at 60°. Significant differences between reconstructions were not found at any flexion angle during tibial internal/external applied torques. Under combined loading, DB produced significantly less laxity than SB constructs apart from anterior tibial translation at 0° and internal rotation at 45°. 3S and DB were comparable to the native knee throughout.Conclusion: Although 3S restored laxities to a similar extent to DB, significant superiority over SB surgery was not observed. Although statistically significant differences were found between SB and DB surgery during anterior tibial and simulated pivot-shift loading, both remained similar to the nativ

Journal article

Lord BR, El-Daou H, Sabnis BM, Gupte CM, Wilson AM, Amis AAet al., 2016, Biomechanical comparison of graft structures in anterior cruciate ligament reconstruction, Knee Surgery Sports Traumatology Arthroscopy, Vol: 25, Pages: 559-568, ISSN: 1433-7347

PURPOSE: Double-bundle (DB) anterior cruciate ligament (ACL) reconstruction may offer kinematic restoration superior to anatomic single bundle (SB), but it remains technically challenging. The femoral attachment site has the most effect on ACL graft isometry, so a simplified three-socket (3S) construct which still uses two sockets to cover the femoral ACL attachment is attractive. It was hypothesised that ACL reconstruction using three- and four-socket techniques would more closely restore native knee kinematics compared to anatomic two-socket (SB) surgery. METHODS: Nine cadaveric knees were used to evaluate the kinematics of ACL-intact, ACL-deficient, anatomic SB, three-socket, and DB arthroscopic ACL reconstructions. Suspensory fixation was used, and grafts were tensioned to match the anterior draw of the intact knee at 20°. A six-degree-of-freedom robotic system measured knee laxity under 90 N anterior tibial force and rotational laxity under 5 N-m torque. Combined moments were applied to simulate the pivot-shift subluxation: 4 N-m internal rotation and 8 N-m valgus. RESULTS: Significant differences between reconstructions were not found during anterior tibial loading, apart from SB being more lax than DB at 60° flexion. All reconstructions produced comparable laxity to the intact state, apart from SB at 60°. Significant differences between reconstructions were not found at any flexion angle during tibial internal/external applied torques. Under combined loading, DB produced significantly less laxity than SB constructs apart from anterior tibial translation at 0° and internal rotation at 45°. 3S and DB were comparable to the native knee throughout. CONCLUSION: Although 3S restored laxities to a similar extent to DB, significant superiority over SB surgery was not observed. Although statistically significant differences were found between SB and DB surgery during anterior tibial and simulated pivot-shift loading, both remain

Journal article

Kittl C, El-Daou H, Athwal KK, Gupte CM, Weiler A, Williams A, Amis AAet al., 2016, The Role of the Anterolateral Structures and the ACL in Controlling Laxity of the Intact and ACL-Deficient Knee: Response., American Journal of Sports Medicine, Vol: 44, Pages: NP15-NP18, ISSN: 1552-3365

Journal article

Kittl C, El-Daou H, Athwal KK, Gupte CM, Weiler A, Williams A, Amis AAet al., 2016, The role of the anterolateral structures and the ACL in controlling laxity of the intact and ACL-deficient knee, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 44, Pages: 345-354, ISSN: 0363-5465

Background:Anterolateral rotatory instability (ALRI) may result from combined anterior cruciate ligament (ACL) and lateral extra-articular lesions, but the roles of the anterolateral structures remain controversial.Purpose:To determine the contribution of each anterolateral structure and the ACL in restraining simulated clinical laxity in both the intact and ACL-deficient knee.Study Design:Controlled laboratory study.Methods:A total of 16 knees were tested using a 6 degrees of freedom robot with a universal force-moment sensor. The system automatically defined the path of unloaded flexion/extension. At different flexion angles, anterior-posterior, internal-external, and internal rotational laxity in response to a simulated pivot shift were tested. Eight ACL-intact and 8 ACL-deficient knees were tested. The kinematics of the intact/deficient knee was replayed after transecting/resecting each structure of interest; therefore, the decrease in force/torque reflected the contribution of the transected/resected structure in restraining laxity. Data were analyzed using repeated-measures analyses of variance and paired t tests.Results:For anterior translation, the intact ACL was clearly the primary restraint. The iliotibial tract (ITT) resisted 31% ± 6% of the drawer force with the ACL cut at 30° of flexion; the anterolateral ligament (ALL) and anterolateral capsule resisted 4%. For internal rotation, the superficial layer of the ITT significantly restrained internal rotation at higher flexion angles: 56% ± 20% and 56% ± 16% at 90° for the ACL-intact and ACL-deficient groups, respectively. The deep layer of the ITT restrained internal rotation at lower flexion angles, with 26% ± 9% and 33% ± 12% at 30° for the ACL-intact and ACL-deficient groups, respectively. The other anterolateral structures provided no significant contribution. During the pivot-shift test, the ITT provided 72% ± 14% of the restraint at 45° for th

Journal article

Athwal KK, Daou HE, Kittl C, Davies AJ, Deehan DJ, Amis AAet al., 2015, The superficial medial collateral ligament is the primary medial restraint to knee laxity after cruciate-retaining or posterior-stabilised total knee arthroplasty: effects of implant type and partial release., Knee Surgery, Sports Traumatology, Arthroscopy, Vol: 24, Pages: 2646-2655, ISSN: 0942-2056

PURPOSE: The aim of this study was to quantify the contributions of medial soft tissues to stability following cruciate-retaining (CR) or posterior-stabilised (PS) total knee arthroplasty (TKA). METHODS: Using a robotic system, eight cadaveric knees were subjected to ±90-N anterior-posterior force, ±5-Nm internal-external and ±8-Nm varus-valgus torques at various flexion angles. The knees were tested intact and then with CR and PS implants, and successive cuts of the deep and superficial medial collateral ligaments (dMCL, sMCL) and posteromedial capsule (PMC) quantified the percentage contributions of each structure to restraining the applied loads. RESULTS: In implanted knees, the sMCL restrained valgus rotation (62 % across flexion angles), anterior-posterior drawer (24 and 10 %, respectively) and internal-external rotation (22 and 37 %). Changing from CR TKA to PS TKA increased the load on the sMCL when resisting valgus loads. The dMCL restrained 11 % of external and 13 % of valgus rotations, and the PMC was significant at low flexion angles. CONCLUSIONS: This work has shown that medial release in the varus knee should be minimised, as it may inadvertently result in a combined laxity pattern. There is increasing interest in preserving constitutional varus in TKA, and this work argues for preservation of the sMCL to afford the surgeon consistent restraint and maintain a balanced knee for the patient.

Journal article

Akanyeti O, Brown JC, Chambers LD, el Daou H, Fiazza M-C, Fiorini P, Jezov J, Jung DS, Kruusmaa M, Listak M, Liszewski A, Maud JL, Megill WM, Rossi L, Qualtieri A, Rizzi F, Salumaee T, Toming G, Venturelli R, Visentin F, De Vittorio Met al., 2014, FILOSE for Svenning A Flow Sensing Bioinspired Robot, IEEE ROBOTICS & AUTOMATION MAGAZINE, Vol: 21, Pages: 51-62, ISSN: 1070-9932

Journal article

El Daou H, Salumaee T, Chambers LD, Megill WM, Kruusmaa Met al., 2014, Modelling of a biologically inspired robotic fish driven by compliant parts, BIOINSPIRATION & BIOMIMETICS, Vol: 9, ISSN: 1748-3182

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