Histomorphological studies of the distal internal thoracic artery which support its use for coronary artery bypass grafting.

The use of the internal thoracic artery (ITA) for myocardial revascularization in coronary artery disease increased because of its relative immunity to atherosclerotic obstruction. This study investigated the distal part of the vessel, the region of anastomosis by means of histology to focus the visualization of this region of interest. The histological examination of arterial segments showed minor intimal thickening in 48 out of 100 patients. Twelve patients demonstrated a severe intimal thickening, the residual patients were without any changes. In 52% the elastic type dominated in the distal part. Hybrid and muscular patterns were found in 22 and 26%, respectively. The media could be classified into three different types: muscular, hybrid and elastic type. There was no correlation concerning the different histological type and the incidence of intimal thickening. No evidence whatsoever of atherosclerotic lesion was encountered in any of the investigated vessels. There is no limitation in the use of the distal part of the ITA for coronary artery revascularization.

Cell survival following bone-anterior cruciate ligament-bone allograft transplantation: DNA fingerprints, segregation, and collagen morphological analysis of multiple markers in the canine model.

Bone-anterior cruciate ligament-bone allograft transplantation has become recognized as a potential solution to reconstruction of the anterior cruciate ligament (ACL). The purpose of this study was to determine the time-dependent fibrocyte donor cell survival rate after cryopreserved bone-ACL-bone allograft transplantation. Additionally, bony incorporation of the pediculated bone plugs was examined. The ability to successfully transplant allogenous ACL fibrocytes and have them survive has not previously been documented. In this study, DNA fingerprints identified and documented the survival rate of the cellular DNA in transplanted ACL allografts for ACL re-construction in the knee joints of 10 skeletally mature dogs. At 4, 8, 26 and 52 weeks after ACL allograft transplantation, DNA probes, H & E, Giemsa, Goldner, PAS and polarized light staining was done to demonstrate the time-dependent changes in the allografts after transplantation. At 4 weeks host fibrocytes began to grow into the graft; however, histologically the cells could not be distinguished as to host or donor origin. After 4 weeks the DNA pattern reflected only the band pattern of the host. This reveals the early cellular infiltration activity of the host into the ACL allograft, also demonstrated in the light microscopy stainings. The survival rate of transplanted allogenous ACL fibrocytes had not been documented before this study. There is no evidence that ACL allograft cells survive in the intra-articular environment of the host's knee. Within 4 weeks ACL allografts became completely repopulated with host cells. The cells that migrate early into the ACL allografts are probably of synovial origin because they are present before revascularization and collagen reorganization occur. We conclude from this study that viable cells in transplanted ACL allografts did not survive longer than 4 weeks after intra-articular transplantation. Advances in molecular biology may offer new approaches to alter or stimulate fibrocyte population and function in the transplanted ACL allograft used for ACL reconstruction. New methods to maintain the viability of donor cells may be necessary to improve the biomechanical and histological properties of autografts or allografts for ACL reconstruction.

Sterilisation of canine anterior cruciate allografts by gamma irradiation in argon. Mechanical and neurohistological properties retained one year after transplantation.

Bone-ACL-bone allograft transplantation is a potential solution to the problem of reconstruction of the anterior cruciate ligament (ACL), but sterilisation by gamma irradiation or ethylene oxide causes degradation of the graft. We have studied the biomechanical and histological properties of deep-frozen canine bone-ACL-bone allografts sterilised by gamma irradiation (2.5 Mrad) under argon gas protection. Particular attention was paid to their collagen structure and neuroanatomy compared with those of non-irradiated allografts. We used 60 skeletally mature foxhounds. In 30 animals one ACL was replaced by an irradiated allograft and in the other 30 a non-irradiated graft was used. In both groups the graft was augmented by a Kennedy Ligament Augmentation Device. Examination of the allografts at 3, 6 and 12 months after implantation included mechanical testing, histology, collagen morphometry, neuroanatomical morphology (silver and gold chloride stain) and studies of the microvasculature (modified Spalteholz technique). At 12 months the irradiated ACL allografts failed at a mean maximum load of 718.3 N, 63.8% of the strength of the normal canine ACL. The non-irradiated allografts failed at 780.1 N, 69.1% of normal. All the allografts showed a well-orientated collagen structure one year after transplantation and there was no difference between the irradiated grafts and the others. The silver staining technique demonstrated Golgi tendon organs and free nerve endings within both groups of allografts. As in the normal ACL these structures were most commonly found near the surface of the graft and at its bony attachments. At 12 months the irradiated allografts showed slight hypervascularity compared with the non-irradiated grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior cruciate ligament reconstruction using cryopreserved irradiated bone-ACL-bone-allograft transplants.

Bone-ACL-bone allograft transplantation has been investigated as a potential solution to reconstruction of the anterior cruciate ligament (ACL). To minimize disease transmission (e.g. the acquired immuno deficiency syndrome), bony and collagenous tissues should be sterilized. Recent animal studies indicate that gamma irradiation and ethylene oxide sterilization result in diminished histological and biomechanical properties. The purpose of the present study was biomechanical and histological determination of the fate of deep-frozen gamma-irradiated (2.5 Mrad) canine bone-ACL-bone allografts with argon gas protection. Particular attention was paid to collagenous and neuroanatomical morphology 3, 6 and 12 months after implantation, by comparison to a non-irradiated control group. Sixty skeletally mature foxhounds were operated on in this study, divided up in two groups of 30 dogs each. In group A animals the ACL was replaced by a deep-frozen (-80 degrees C) bone-ACL-bone LAD-augmented allograft subjected to 2.5 Mrad gamma irradiation with argon gas protection. The animals in group B received an LAD-augmented ACL-allograft transplant without gamma irradiation. All knees from both groups were evaluated 3, 6 and 12 months after implantation in regard to biomechanical properties, collagen morphology and routine histology (haematoxylin and eosin stain, polarization microscopy), neuroanatomical morphology (silver and gold chloride stain) and microvasculature (modified Spalteholz technique). The irradiated ACL allografts withstood a maximum load that was 63.8% (718.3 N) of the maximum load of normal ACLs after 12 months. By contrast, the non-irradiated allografts failed at 69.1% (780.1 N) of the maximum load of normal control ACLs.(ABSTRACT TRUNCATED AT 250 WORDS)

Function of the glenohumeral ligaments in active stabilisation of the shoulder joint.

UNLABELLED: The joint capsules and the glenohumeral ligaments of 12 human shoulder specimens were histologically investigated by light microscopy. Serial sections of 15 microns thickness were cut. The tissue was stained following the haematoxylin-eosin and van Giesson techniques. For specific identification of neural elements we made use of a special silver impregnation technique, described by Novotny, for staining axons in peripheral nerves. Axons of different diameters ranging from 0.2 microns to 70 microns were discovered within the ligaments. Close to the humeral site we found small nerves forming neurovascular bundles. Within their connective tissue sheaths, the axons exhibited a serpentine configuration, which may give extra length and may allow stretching of the nerve during motion. Most of the axons discovered were located in the subsynovial layer of the ligaments. In general the diameter of these subsynovial axons did not exceed 10 microns. In addition to these axonal structures, we detected nerve endings which can be classified according to Freeman and Wyke as type II mechanoreceptors (Pacinian corpuscles). These mechanoreceptors had a diameter of approximately 150 microns. They were also positioned directly beneath the synovial membrane and close to the humeral site of insertion of the ligaments. CLINICAL SIGNIFICANCE: The described neural structures in the glenohumeral ligaments are of particular clinical importance in the light of the high incidence of recurrent shoulder dislocation and concomitant Bankart lesions. The mechanoreceptors located in the glenohumeral ligaments may control the stabilising shoulder musculature. On this premise, rupture or detachment of these ligaments will lead to a loss of a feedback mechanism.

Anterior cruciate ligament allograft transplantation for intraarticular ligamentous reconstruction.

A multiplicity of surgical operations have been developed in an attempt to achieve satisfactory function after anterior cruciate ligament (ACL) repair. None of these procedures have been able to reproduce the fiber organization anatomy of attachment site, vascularity, or function of the ACL. Twenty-nine foxhounds received a deep-frozen bone-ACL-bone allograft and a ligament augmentation device (LAD). Biomechanical, microvascular, and histological changes were evaluated 3, 6, and 12 months following implantation. The maximum loads of the allograft/LADs were 34.3% (387.2 N) after 3 months, 49.3% (556.6 N) after 6 months, and 61.1% (698.8 N) after a year. The maximum load was 69.1% (780 N). In general, after 6 months the allografts showed normal collagen orientation. The allografts demonstrated no evidence of infection or immune reaction. No bone ingrowth into the LAD was observed. Polarized light microscopy and periodic acid-schiff staining showed that the new bone-ligament substance interface had intact fiber orientation at the area of the ligament insertion. Microvascular examination using the Spalteholtz technique revealed revascularization and the importance of an infrapatellar fat pad for the nourishment of ACL allografts.

Neurohistological findings after experimental anterior cruciate ligament allograft transplantation.

A multiplicity of surgical operations have been developed in an attempt to achieve satisfactory function after anterior cruciate ligament (ACL) repair. None of these procedures have been able to duplicate the fiber organization, anatomy of the attachment site, vascularity, or function of the ACL. Eighteen foxhounds received a deep-frozen bone-ACL-bone allograft and a ligament augmentation device. Neurohistological changes were evaluated 3, 6 and 12 months following implantation. The modified silver impregnation method and gold chloride technique were used to examine the presence of nerve endings and axons. Two morphologically distinct mechanoreceptors were identified and classified as free nerve endings and Golgi-like tendon receptors respectively. Fine nerve endings frequently ramified freely into ligament collagen bundles. Nerves and blood vessels were commonly associated. As in normal ACLs, both neuroreceptor types were mostly located near the surface of the allografts and at the two bony attachments. This study demonstrated the first histological evidence of viable mechanoreceptors and free nerve endings in transplanted ACL allografts, not previously reported in other ACL substitutes used for ACL reconstruction. Particularly importantly for postoperative rehabilitation, this technique may allow the reconstruction of the proprioceptive functions of normal ACLs.

[Homologous replacement of the cruciate ligament in the animal experiment]. / Der homologe Kreuzbandersatz im Tierexperiment.

A homologous cruciate ligament transplantation was effected in 20 Alsation dogs. Clinical, pathologico-anatomical and histological results were obtained from 16 animals after 3, 6 and 9 months, respectively, proving metaplasia of the transplant to endogenous body tissue. The clinical conclusion of this finding is that an anatomically optimally-structured ligament replacement can be inserted by means of a relatively uncomplicated operation--possibly even by using arthroscopy. The low amount of traumatization due to this type of surgery will be of advantage especially to sportsmen, who, as is well known, not only suffer from frequent cruciate ligament ruptures but also have remarkably long-term deficits by large operation wounds both in regaining their proprioceptive performance ability and their muscular power.