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  • Journal article
    WILLIAMS RJN, AMIS AA, 1995,

    A NEW-TYPE OF FLEXOR TENDON REPAIR - BIOMECHANICAL EVALUATION BY CYCLIC LOADING, ULTIMATE STRENGTH AND ASSESSMENT OF PULLEY FRICTION IN-VITRO

    , JOURNAL OF HAND SURGERY-BRITISH AND EUROPEAN VOLUME, Vol: 20B, Pages: 578-583, ISSN: 0266-7681
  • Journal article
    Williams RJ, Amis AA, 1995,

    A new type of flexor tendon repair. Biomechanical evaluation by cyclic loading, ultimate strength and assessment of pulley friction in vitro.

    , J Hand Surg Br, Vol: 20, Pages: 578-583, ISSN: 0266-7681

    Experiments were performed to evaluate biomechanical aspects of the performance of a "deep-biting peripheral suture" for flexor tendon repair, either when used alone or with a square or modified Kessler core stitch, and the technique was compared to the Kleinert repair. Tests included progressively increasing cyclic loads, force to pull the repair into the A2 pulley, and ultimate failure strength. 50% of the Kleinert repairs failed under 30 N cyclic loading, while 100% of the DBPS plus Kessler core stitch repairs survived. There was no discernable difference in gliding function or repair bulk between these sutures, but ultimate strength increased significantly with the DBPS repairs. We concluded that the DBPS plus Kessler-type core stitch will survive active mobilization better than the Kleinert method.
  • Journal article
    AMIS AA, MILLER JH, 1995,

    THE MECHANISMS OF ELBOW FRACTURES - AN INVESTIGATION USING IMPACT TESTS IN-VITRO

    , INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED, Vol: 26, Pages: 163-168, ISSN: 0020-1383
  • Journal article
    Radford WJ, Amis AA, Heatley FW, 1994,

    Immediate strength after suture of a torn anterior cruciate ligament.

    , J Bone Joint Surg Br, Vol: 76, Pages: 480-484, ISSN: 0301-620X

    In an animal model we determined the strength of anterior cruciate ligaments (ACL) after section and repair by four different methods and compared it with that of the intact ligament. The standard suturing technique of multiple loops through the ligament stumps was used. Stronger suture material did not give a stronger repair. Wrapping a fine polyester mesh around the ligament or placing it between the bundles before suture increased the strength of the repair. This modification, allied to protective rehabilitation, may reduce the failure rate of acute ACL repairs.
  • Journal article
    RADFORD WJP, AMIS AA, HEATLEY FW, 1994,

    IMMEDIATE STRENGTH AFTER SUTURE OF A TORN ANTERIOR CRUCIATE LIGAMENT

    , JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 76B, Pages: 480-484, ISSN: 0301-620X
  • Journal article
    RACE A, AMIS AA, 1994,

    THE MECHANICAL-PROPERTIES OF THE 2 BUNDLES OF THE HUMAN POSTERIOR CRUCIATE LIGAMENT

    , JOURNAL OF BIOMECHANICS, Vol: 27, Pages: 13-24, ISSN: 0021-9290
  • Journal article
    Amis AA, 1994,

    Development of the Apex polyester fibre cruciate ligament implant.

    , Clin Mater, Vol: 15, Pages: 51-60, ISSN: 0267-6605

    This paper describes the work done in developing the Apex polyester fibre cruciate ligament implant. A series of animal experiments showed that the material was the basis for good collagenous tissue ingrowth at the calcaneal tendon and within the knee joint. The rate of increase of strength of ingrowth at the calcaneal tendon was investigated. The slow maturation led to the development of a stainless steel screw and grommet anchorage system, which was also tested in vitro. A long-term animal study of the clinical implant and anchor system showed the implant fibres spaced apart by prolific ingrowth, while no implant particles were found, and there was no evidence of synovitis. The tissue reactions in human use have been found to be the same as in the animals, while ultrastructural study of retrieved specimens has given evidence of long-term collagen maturation.
  • Journal article
    Radford WJ, Amis AA, Kempson SA, Stead AC, Camburn Met al., 1994,

    A comparative study of single- and double-bundle ACL reconstructions in sheep.

    , Knee Surg Sports Traumatol Arthrosc, Vol: 2, Pages: 94-99, ISSN: 0942-2056

    Work in vitro has previously shown superior restoration of knee stability using a double-bundle anterior cruciate ligament (ACL) reconstruction compared with single bundles taken through the condyle or 'over the top'. This paper describes an animal study designed to compare the three ACL reconstructions in vivo, in order to collect data that could support the clinical use of a double-bundle reconstruction. The three methods were compared in three groups of eight sheep, the ovine ACL having a distinct double-bundle structure. Biomechanically matched polyester fibre implants were used, with 6 months in vivo. The three methods led to similar intra-articular fibrous tissue integration of the implants and no evidence of implant damage, and biomechanical testing found greater laxity than normal for all three groups. The double-bundle group, however, had more joint surface degeneration than the other groups. It was concluded that clinical use of the double-bundle reconstruction was not indicated by the results of this experiment, in view of the more complex surgery and lack of superior performance.
  • Journal article
    Amis AA, Beynnon B, Blankevoort L, Chambat P, Christel P, Durselen L, Friederich N, Grood E, Hertel P, Jakob Ret al., 1994,

    Proceedings of the ESSKA Scientific Workshop on Reconstruction of the Anterior and Posterior Cruciate Ligaments.

    , Knee Surg Sports Traumatol Arthrosc, Vol: 2, Pages: 124-132, ISSN: 0942-2056
  • Journal article
    Andersen HN, Amis AA, 1994,

    Review on tension in the natural and reconstructed anterior cruciate ligament.

    , Knee Surg Sports Traumatol Arthrosc, Vol: 2, Pages: 192-202, ISSN: 0942-2056

    This article reviews the methodology and results of published studies concerned with tension in the natural and reconstructed anterior cruciate ligament (ACL). This also includes studies of fiber length changes with knee motion and the relationships between graft tunnel placements and isometricity. Little work has been done in vivo: in humans, length changes of the anterior ACL fibers have been measured at operation, while animal longitudinal studies have been few and have given conflicting results. Work in vitro has used many methods to study ACL tension directly or indirectly, via length changes in fibers, but many authors have reported variable results, caused partly by inter-specimen differences and lack of control of forces or kinematics. It seems likely that different grafts require different peroperative tensions to restore normal stability when measured immediately after application at one knee position. But graft placement and the angle at which tensioning is performed also matter. Over-tensioning constrains knees under load cycling. Similarly, it is difficult to measure and therefore also to decide how tension should be distributed between an ACL graft and and augmentation to the graft. It was concluded that the published studies provide many guidelines for the effects of different graft placements or tensioning protocols but, overall, there is little firm evidence on which to recommend any particular ACL reconstruction protocol.
  • Conference paper
    AMIS AA, 1994,

    THE MECHANICAL-PROPERTIES OF FINGER FLEXOR TENDONS AND DEVELOPMENT OF STRONGER TENDON SUTURING TECHNIQUES

    , NATO Advanced Research Workshop on Advances in the Biomechanics of the Hand and Wrist, Publisher: PLENUM PRESS DIV PLENUM PUBLISHING CORP, Pages: 41-57, ISSN: 0258-1213
  • Journal article
    AMIS AA, SCAMMELL BE, 1993,

    BIOMECHANICS OF INTRAARTICULAR AND EXTRAARTICULAR RECONSTRUCTION OF THE ANTERIOR CRUCIATE LIGAMENT

    , JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 75, Pages: 812-817, ISSN: 0301-620X
  • Journal article
    KNIGHT DJ, RYMASZEWSKI LA, AMIS AA, MILLER JHet al., 1993,

    PRIMARY REPLACEMENT OF THE FRACTURED RADIAL HEAD WITH A METAL PROSTHESIS

    , JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 75, Pages: 572-576, ISSN: 0301-620X
  • Journal article
    AMIS AA, CAMBURN M, KEMPSON SA, RADFORD WJP, STEAD ACet al., 1993,

    ANTERIOR CRUCIATE LIGAMENT REPLACEMENT WITH POLYESTER FIBER - A LONG-TERM STUDY OF TISSUE-REACTIONS AND JOINT STABILITY IN SHEEP (J BONE SURG, VOL 74-B, PG 605, 1992)

    , JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 75, Pages: 169-169, ISSN: 0301-620X
  • Journal article
    AMIS AA, CAMBURN M, KEMPSON SA, RADFORD WJP, STEAD ACet al., 1992,

    ANTERIOR CRUCIATE LIGAMENT REPLACEMENT WITH POLYESTER FIBER - A LONG-TERM STUDY OF TISSUE-REACTIONS AND JOINT STABILITY IN SHEEP

    , JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 74, Pages: 605-613, ISSN: 0301-620X
  • Journal article
    MASHADI ZB, AMIS AA, 1992,

    VARIATION OF HOLDING STRENGTH OF SYNTHETIC ABSORBABLE FLEXOR TENDON SUTURES WITH TIME

    , JOURNAL OF HAND SURGERY-BRITISH AND EUROPEAN VOLUME, Vol: 17B, Pages: 278-281, ISSN: 0266-7681
  • Journal article
    Mashadi ZB, Amis AA, 1992,

    Variation of holding strength of synthetic absorbable flexor tendon sutures with time.

    , J Hand Surg Br, Vol: 17, Pages: 278-281, ISSN: 0266-7681

    This study examined the potential use of absorbable polytrimethylene carbonate (Maxon) sutures for tendon surgery. Flexor tendons of the third toe of 48 chickens were transected and sutured, then evaluated both mechanically and histologically at 0, five, 15 and 45 days after operation. Mechanical testing showed that the suture kept its strength long enough to unite tendon ends. However, high tissue reactivity of polytrimethylene carbonate during its dissolution caused adhesions.
  • Journal article
    Mashadi ZB, Amis AA, 1992,

    Strength of the suture in the epitenon and within the tendon fibres: development of stronger peripheral suture technique.

    , J Hand Surg Br, Vol: 17, Pages: 172-175, ISSN: 0266-7681

    In tendon repair, the peripheral stitches are usually placed in the epitenon, but it has not yet been defined whether the grasping strength of the sutures in the epitenon and within the tendon fibres are different. The first stage of this work investigated this difference and found that peripheral stitches within cadaveric tendon fibres were 83% stronger than those in the epitenon layer. A new peripheral stitch, based on this finding, has been designed. Mechanical tests of a range of peripheral suture types in vitro found that the new technique gave a resistance to gap formation twice that of the peripheral stitches commonly in use at present and a rupture strength more than three times, while still avoiding eversion problems.
  • Journal article
    MASHADI ZB, AMIS AA, 1992,

    STRENGTH OF THE SUTURE IN THE EPITENON AND WITHIN THE TENDON FIBERS - DEVELOPMENT OF STRONGER PERIPHERAL SUTURE TECHNIQUE

    , JOURNAL OF HAND SURGERY-BRITISH AND EUROPEAN VOLUME, Vol: 17B, Pages: 172-175, ISSN: 0266-7681
  • Journal article
    Wetherell RG, Unsworth A, Amis AA, 1992,

    The function of bipolar hip prostheses--a laboratory study using cadaveric acetabula.

    , Proc Inst Mech Eng H, Vol: 206, Pages: 37-42, ISSN: 0954-4119

    Cadaveric acetabula were mounted in a hip simulator and the friction developed in each during articulation with a series of metal femoral head prostheses of differing sizes was measured. In a separate study, assembled Hastings bipolar hip prostheses were subjected to weight-bearing forces in the same acetabula and their self-righting mechanism was observed. The self-righting mechanism was found to function efficiently, in most cases overcoming the combined friction of the inner and outer articulations of the Hastings hip. However, during motion in the hip simulator a wide variation of friction was observed between different acetabula and within the same acetabulum with differing head size. In several cases this acetabular friction was found to be less than the friction in the inner articulation of the Hastings bipolar hip prosthesis, and this may explain some cases of reported failure of biarticular function.

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