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Biomedical subjects

U Holz

Publications and source records attributed to U Holz.

At least 73 records · Page 4Linked to original sources
PubMed1980

[Achilles tendon rupture and achillodynia. The importance of tissue regeneration].

Ruptures of the Achilles tendon mainly occur in males aged 30 to 40 years; in an analysis of 561 specimens taken from ruptured tendons only 25% were classified as degenerative tendopathy. Ultrastructural studies of areas in and near the tendon rupture and of specimens of tendonitis show more collagen fibres with small diameter in comparison to normal samples. These morphological changes correspond to structures of tendon tissue after reversible damage of rabbit tendons. Test models were throttling of the Arteria poplitea or Arteria femoralis, sheathing of the Achilles tendon and deflecting the tendon in order to increase the tension. The electrophoretic determination of collagen showed increasing type III collagen with formation of repair tissue. First of all the experimental findings as well as the clinical fact of rare secondary ruptures after operatively treated ruptures of Achilles tendons prove good conditions for tendon repair. But probably an increasing number of small diameter collagen fibres and changings in the pattern of collagen types weaken the mechanical properties of the tendon.

Achilles Tendon↗
PubMed1980

[Biomechanical problems in elbow joint dislocations with coronoid and capitulum radii fractures (author's transl)].

Dorsal dislocation occurs in 80% of all fracture dislocations of the elbow joint. In 10-15% of these njuries the coronoid process and the radial head are involved. If this injury causes the defect of the radial head - which means the loss of the main supporting part of the joint, - it is only the coronoid process which gives stability to the elbow joint. Therefore, in cases of coronoid fracture it is of utmost importance to reconstruct the coronoid process, if the fracture involves more than 1/6 of the incisura olecrani. Advisable for fixation is the use of a lag screw. In some cases the reconstruction with autogenous bone graft or osteotomy of the olecranon is indicated.

Elbow Joint↗
PubMed1980

[Classification and clinical diagnosis of lesions to the capsule and the ligaments of the knee point (author's transl)].

A classification of lesion of the capsule and ligaments of the knee joint can be related to the possible dislocation of the tibial head due to the injury. Analysing the dislocation the injured structures can be determined. This classification provides a better planning for the reconstruction of fresh and old injuries. A proper knowledge of the anatomy and the biomechanics of the knee joint is essential. Experimental and clinical experience over the last decade show that a simple classification in lateral, medial, anterior and posterior instability is inadequate. Therefore a more specific classification is recommended. Under this aspect history and clinical findings are of utmost importance for the diagnosis of injuries to the capsule and the ligaments of the knee joint.

Bursa, Synovial↗
PubMed1980

[Experience in surface replacement arthroplasty of the hip (author's transl)].

A four year follow up trial of 109 cases of the Wagner type of prosthetic surface replacement has been undertaken. It has been found that this type of arthroplasty has been associated with a higher rate of loosening that the conventional total hip replacement. This loosening mainly affects the femoral component. The morphological changes which occured below the loosened femoral component did not show typical avascular necrosis due to implantation of the prosthesis. The changes seen were due to mechanical failure of the bone which resulted from previous structural weakness of the femoral head. Hence loosening of the implant occurred mainly in femoral heads which had cysts, partial necrosis or osteoporosis. Loosening of the implant was not definitely related to the position of the hip and occured in both the valgus as well as the biomechanically unfavourable varus position.

Bone Cysts↗
PubMed1979

[Valgus osteotomy in treatment of osteoarthrosis of hip (author's transl)].

The article reports on Bombelli's theory on the genesis of arthrosis of the hip. Clinical experience has shown that valgus and extension osteotomy is indicated in dysplasia arthrosis, in cystic changes and formation of osteophytes. Although the good clinical results cannot be accepted as a proof of the biomechanical deliberations, they do extend the range of indications pointing to surgery of the diseased hip joint performed for the purpose of preserving the femoral head.

Bone Plates↗
PubMed1978

[Mechanical tests with polymethylmethacrylate in fresh specimens and specimens obtained from loosened prosthesis (author's transl)].

Mechanical testing of specimen from fresh acrylic cement and from lossened prostheses between one and two years after implantation shows difference in compressive strength. Air bubbles, blood particles, and folds distinctly influence mechanical properties. Therefore, care should be taken to avoid these enclosures during implantation. But it is not the aging of the acrylic cement which presents the main problem in endoprosthetic fixation, but the cement-bone interface. Clinical experience and this mechanical study show that fracture of the acrylic cement is not due to primary fatigue of the material, but occurs secondarily after loosening of the bonding between bone and cement.

Biomechanical Phenomena↗
PubMed1977

[Disordered fibrillar structure in ruptured tendons (author's transl)].

Areas of disordered fibrillar structure similar to kinking deformities have been observed in specimens from ruptured tendons. It seems possible to compare this phenomenon with experimentally produced deformations. The significance for the pathomechanics of tendon rupture is discussed.

Achilles Tendon↗
PubMed1977

[Periarticular ossification following replacement of the hip-joint. Clinical and radiologic examination of 697 hip-joints (author's transl)].

Systematic examination of 733 cases of replacement of the hip-joint, operated on with an identical technique and method of post-operative treatment. Frequency and severity of periarticular ossification, their relationship to pre-operative arthrosis and their effect on joint function are described. Development and localization of periarticular ossification, their higher incidence after tearing off of the trochanter, removal of osteophytes and occurrence of hematomata hint at surgical trauma as one of the causes. Preliminary operations on the proximal end of femur did not influence ectopic ossification. Ossification of grade I did not interfere with function, grades II and III limited movement in varying degrees.

Follow-Up Studies↗
PubMed1975

[Clinical and experimental experiences of important factors concerning the permanent anchorage of hip-joint-prostheses (author's transl)].

Amomg a lot of conditions influencing the permanent anchorage of hip-joint-prostheses the following factors are very important: form and surface conditions of the material, in addition to a valgus position of the prostheses. The importance of these parameters in changed biomechanics after arthroplastic replacement is confirmed by measurements of spherical shape, morphology of the surface and diameter of the material. Furthermore, the vectorial distribution of weight by the different varus and valgus positions were examined. The experimental results were confirmed by clinical studies on 1407 prostheses during the course of 5 years.

Alloys↗