Reconstruction of a defect of the rotator cuff with polytetrafluoroethylene felt graft. Recovery of tensile strength and histocompatibility in an animal model.

We reconstructed defects in the infraspinatus tendon u sing polytetrafluoroethylene (PTFE) felt grafts in 31 beagle dogs and examined the mechanical responses and histocompatibility. Except for one infected specimen, all the reconstructed infraspinatus tendons healed. We examined eight specimens each immediately after surgery and at six and 12 weeks. The ultimate tensile strength of the reconstructed tendons was 60.84 N, 172.88 N, and 306.51 N immediately after surgery and at six and 12 weeks, respectively. The stiffness of the specimens at the PTFE felt-bone interface was 9.61 kN/m, 64.67 kN/m, and 135.09 kN/m immediately after surgery and at six and 12 weeks, respectively. Six tendons were examined histologically at three, six, 12 and 24 weeks. Histological analysis showed that there was ingrowth of fibrous tissue between the PTFE fibres. Foreign-body reactionswere found at the margin of the PTFE-bone interface between 12 and 24 weeks. The mechanical recovery and tissue affinity of PTFE felt to bone and to tendon support its use for reconstruction of the rotator cuff. The possible development of a foreign-body reaction should be borne in mind.

[Measurement of changes in distance between the femoral and the tibial drill holes for the anterior cruciate ligament reconstruction].

We have developed an experimental system in which a new Gallium-Indium containing transducer can continuously measure the changes of separation distances between the femoral and tibial points. The measurements provides information for the attachment location in the anterior cruciate ligament (ACL) reconstruction and used for various combinations of extra-articular and intra-articular methods. At the first experiment, the distance between each pair of points at the level of the capsule for fifteen combinations during simple flexion-extension knee motion were measured on six cadaveric knees. At the next experiment, in an ACL-deficient knee the distances of ten combinations in the intra-articular method were measured. These results indicated that for an isometric placement the combination of the center of tibial insertion and the postero-proximal of the femoral origin of the ACL appeared to furnish a better location for intraarticular reconstruction. No combination was recommended for extraarticular reconstruction.

Mechanical strength of latissimus dorsi tendon transfer with Teflon felt augmentation.

Tensile properties of Teflon felt augmentation after latissimus dorsi tendon transfer to rotator cuff defect were examined in dog cadaver shoulders. Two experimental groups with latissimus dorsi tendon transfer were designed. In group 1 (right shoulders, n = 7) the tendon ends of latissimus dorsi were sutured to the greater tuberosity. In group 2 (left shoulders, n = 7) the repair was augmented with Teflon felt at the suture site. The ultimate tensile force and stiffness of each specimen in group 2 were individually compared with those in group 1. The average increases in ultimate tensile force and stiffness in group 2 were 53.8% and -3.7%, respectively. The individual value of ultimate tensile force in group 2 was significantly greater than that in group 1. These results demonstrate that augmentation at the repair site is mechanically effective latissimus dorsi tendon transfer. The augmentation procedure may provide protection during the healing period because of this and a surrounding fibrous tissue reaction.