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Biomedical subjects

R Kotz

Publications and source records attributed to R Kotz.

At least 19 recordsLinked to original sources
PubMed1992

Polygonal triple osteotomy of the pelvis. A correction for dysplastic hip joints.

A new triple osteotomy, polygonal pelvic osteotomy (PPO), is described for use in dysplastic hips. The hip joint must be congruous with a centre-edge (CE) angle between +20 degrees and -10 degrees. Templates are used before and during operation which allow precise correction of the position of the acetabulum. The geometry of the osteotomy and a special compression plate achieve sufficient stability to permit early mobilisation. Surgery is indicated in adolescents and young adults if pain persists for at least two months. The surgical exposure, operative technique and postoperative management are presented, with the two-year results in nine cases.

Acetabulum↗
PubMed1992

[Therapy of bone metastases of the lower extremity with the KMFTR modular tumor endoprosthesis system].

During the years 1975 through 1989, 189 patients have been operated because of metastases within bones of the lower extremity. Thereof, 34 patients received an endoprosthesis of the KMFTR (Kotz Modular Femur-Tibia reconstruction system) type. In detail, the following reconstruction elements had been used: proximal femur (n = 20), distal femur (n = 7), complete femur (n = 2), proximal tibia (n = 5). At the time of follow-up examination 30 patients had died. Mean survival time after resection of metastases was 18.6 months (range 8-44 months). According to histologic judgement, in 23 cases wide or marginal resections had been performed whereas 11 patients had been operated intralesionally. In no case local recurrence as relevant to therapy was observed. At the same time-point, survival periods after detection of secondary manifestations of the malignant diseases within the remaining 4 patients were 29, 61, 73 and 125 months, respectively. The following complications were observed: luxation of the prosthesis (n = 6), transient paresis of the peroneus (n = 3), deep vein thrombosis (n = 2), pulmonary infarction (n = 1), wound healing disturbances (n = 2) and hematoma (n = 3).

Acetabulum↗
PubMed1991

Chiari osteotomy for congenital dislocation and subluxation of the hip. Results after 20 to 34 years follow-up.

We reviewed 236 of the 388 Chiari pelvic osteotomies performed between 1953 and 1967 at the Orthopaedic University Clinic of Vienna for the treatment of congenital dislocation and subluxation of the hip. Over 90% of the operations were performed by Chiari himself. Twenty-one hips had needed reoperation after an average of 15.4 years; the other 215 hips had been followed up for 20 to 34 years (mean 24.8). The overall clinical results were excellent or good in 51.4%, fair in 29.8% and poor in 18.3%. The results were worse with increasing age at operation. The Trendelenburg sign improved only in patients aged seven or less at operation, and range of movement decreased in all cases. Subjectively poor results were seen in patients with pre-operative signs of osteoarthritis. Radiological loss of correction during follow-up was seen only in cases with incomplete primary correction. The addition of an intertrochanteric varus osteotomy in 36 cases did not achieve either better centering or better development of the acetabular roof. Degenerative changes increased significantly during the long-term follow-up, but their progress seemed to have been slowed down by the osteotomy in the younger age groups. Indications and contra-indications for the operation are discussed.

Adolescent↗
PubMed1991

Local control and survival from the Cooperative Osteosarcoma Study Group studies of the German Society of Pediatric Oncology and the Vienna Bone Tumor Registry.

The use of aggressive chemotherapy undoubtedly has brought about a dramatic increase in the cure rate of osteosarcoma. The authors' investigations have increased the authors' knowledge of chemotherapy for osteosarcoma, the differential efficacy of currently used agents, and the pronounced schedule dependency and relative route independency of their efficiency. The authors were able to confirm the prognostic significance of tumor response after preoperative chemotherapy. Preoperative chemotherapy in itself has facilitated and promoted limb-salvage surgery. Also, more patients can be cured today by use of aggressive thoracic surgery in case of primary or secondary pulmonary metastases. The authors' efforts to steadily increase metastasis-free survival rates by intensifying chemotherapy in this series of studies, however, have been only moderately successful. Still, chemotherapy-related acute toxicity is considerable and increases with aggressiveness of treatment, and the manifestations of late toxicity may continue to increase with follow-up time. Future trials should be targeted toward exploration of the minimum indispensable amount of toxic treatment yielding comparable or even better results than those currently attainable.

Adolescent↗
PubMed1991

The management of IIB osteosarcoma. Experience from 1976 to 1985.

From 1976 to 1985, 75 IIB osteosarcomas have been treated out of a total of 98 osteosarcomas at the authors' institution. Because of the effective chemotherapy including high-dose methotrexate administered during this time period, the surgical management changed, and only ten patients out of the 75 IIB osteosarcomas required an amputation. The overall result of 76.7% of disease-free, three-year survival was equally distributed regardless of the surgical procedure. Endoprosthesis, resection with or without grafts, and rotationplasties, as well as amputations, revealed similar results. No negative influence from the limb-sparing surgery could be observed.

Adolescent↗
PubMed1991

Rotationplasty for limb salvage in the treatment of malignant tumors at the knee. A follow-up study of seventy patients.

Seventy patients who had a rotationplasty for treatment of a malignant tumor in the region of the knee (the femur or the tibia) between 1974 and 1987 were followed for two to thirteen years (mean duration of follow-up, four years). Forty-seven patients had a stage-IIB osteosarcoma; the remaining twenty-three patients had a malignant fibrous histiocytoma, a chondrosarcoma, a Ewing sarcoma, or a giant-cell tumor. The most severe postoperative complication was occlusion of the reanastomosed vessels (seven patients), leading to amputation proximal to the knee in three patients. Other complications were problems with wound-healing (eight patients), transient nerve palsy (five patients), irreversible nerve palsy (two patients), pseudarthrosis (four patients), and rotational malalignment (one patient). Late complications included eight fractures, two infections, two delayed unions, and one lymphatic fistula. More than half of the patients were free of complications related to the operative procedure. Forty-four of the patients who had a stage-IIB osteosarcoma could be followed, and their data were analyzed for survival statistics. These patients had a 58 percent rate of disease-free survival and a 70 per cent rate of over-all survival. One patient had a local recurrence five years after the operation.

Adolescent↗
PubMed1990

Effect of intraarterial versus intravenous cisplatin in addition to systemic doxorubicin, high-dose methotrexate, and ifosfamide on histologic tumor response in osteosarcoma (study COSS-86).

In osteosarcoma, intraarterial (IA) administration of systemic treatment has been advocated to improve local tumor response preparing for, or even obviating, definitive surgery. Because data from the literature did not unequivocally support the local superiority of IA infusion, a comparative study was started in 1986. Preoperative chemotherapy consisted of 45 mg/m2 of doxorubicin on days 1 and 2; 12 g/m2 of high-dose methotrexate on days 15 and 22; and 3 g/m2 of ifosfamide on days 29, 30, 50, and 51 followed on days 31 and 52 by intravenous (IV) versus IA tourniquet infusion of cisplatin (DDP). A strict randomization of patients was not feasible. A balanced distribution of risk factors was strived for by stratifying and allocating the appropriate patients centrally. The infusion time was prolonged from 1 to 5 hours in the IV group, and the DDP dose was reduced from 150 to 120 mg/m2 in both arms when intolerable ototoxicity became apparent. A multivariate analysis was performed to exclude a bias on the response rates from risk factor distribution and from modifications of DDP infusion time and dosage. The overall fraction of histologic good responders (greater than 90% necrosis) was not found to be different after IA versus IV treatment (34/50 [68%] vs. 41/59 [69%]). Intraarterial instead of IV use of DDP within an aggressive systemic treatment does not seem to improve the local tumor response.

Adolescent↗
PubMed1990

[Sugioka's trans-trochanteric osteotomy. Results of interventions 1975-1983].

The long-term results of 46 Sugioka osteotomies are presented: In 22 patients no joint replacement had yet been necessary, and 17 hip joints had already been replaced by total hip prostheses. Of the 22 preserved joints, 12 were graded as clinically excellent and good, 10 as fair or poor. The radiological course showed worsening osteoarthritic changes in almost all cases. In the "survival curve" for the Sugioka osteotomy in the group with 17 total hip prostheses the most significant slope can be seen during the first 3 years postoperatively; between 5 and 10 years there are no failures; and then the curve descends again. Fair and poor results are noted most frequently between 6 and 10 years after the operation in the group of 22 patients with no joint replacement. The preoperative extent of necrosis and the radiological stage are the main factors determining the result. Over the years it has been possible to define a narrow spectrum of indications: the greatest benefit is obtained in young, cooperative patients with necrotic sectors of about 90 degrees and good function of the hip joint.

Adult↗
PubMed1989

Refixation of muscular insertions after endoprosthetic replacement of the proximal humerus.

We describe the refixation of muscle insertions after resection of the proximal humerus in tumor patients. The prosthesis specially designed for this purpose carries large drill holes in the places corresponding to the anatomical sites of the muscle insertions. The muscles are attached to the prosthesis by means of tendon strips from the fascia lata. This can be expected to produce better functional results and to prevent subluxation.

Biomechanical Phenomena↗
PubMed1989

[Results of treatment in primary disseminated osteosarcoma. Analysis of the follow-up of patients in the cooperative osteosarcoma studies COSS-80 and COSS-82].

Since the long-term disease-free survival rate in adjuvantly treated osteosarcoma has nowadays reached a level of about 70%, increasing interest is also being directed towards primarily disseminated forms of the disease. Primary metastases, which were confined to the lungs in 42 cases, were detected in 59 out of 421 patients from the prospective therapy trials COSS-80 and COSS-82. The primary tumors were more frequently localized in the proximal femur and flat bones as compared to patients without detectable metastases at diagnosis. Following chemotherapy and surgery of the primary tumor, 15/31 (48%) patients whose metastases were excised have survived for 4-8 years, in contrast to only 1/22 (5%) of those patients whose metastases could not be removed for a variety of reasons. Clinical or histological evidence of tumor response after primary chemotherapy significantly influenced the outcome of the metastasectomized patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

[Management of the administration of leucovorin calcium in high-dose methotrexate therapy].

At the Orthopaedic University Hospital Vienna, neoadjuvant chemotherapy with high-dose methotrexate (MTX) has been applied since 1975 in patients with osteosarcoma. Since 1977 the hospital has been a participant in the Cooperative German-Austrian Study on Osteosarcoma (COSS, 77, 80, 82, 85, 86). Therapeutic results and incidence of side effects are reviewed at regular intervals. Over a 2-year period (1/86 to 12/87), a total of 1999 g MTX were given to 15 patients in 102 therapeutic cycles. In patients treated with MTX in our hospital, only minor intolerance phenomena occurred, owing to careful leucovorin monitoring. Intoxications of up to grade III (modified WHO-score) have been seen in only a few patients. The management of the administration of leucovorin (leucovorin calcium, calcium folinate, INN; citrovorum factor) which is directly dependent on the serum level of MTX, is exactly shown in the discussion.

Adult↗
PubMed1988

[Vascular surgical reconstructions in orthopedic tumor operations].

The surgical treatment of bone tumors today results more and more in a radical resection therapy. The major vessels are often included in the tumor mass and therefore they have to be resected and reconstructed. Between 1981-1986 30 patients of the Orthopaedic University Clinic in Vienna were treated with tumor resection. The arterial and/or venous reconstruction was done in cooperation with the I. Department of Surgery of the University of Vienna. In 73% of the cases rotation plasty of the knee was performed, in 10% a local tumor resection and in 7% a tumor resection and reconstruction by a tumor endoprosthesis (KMFTR-system). Three patients underwent partial pelvic resection, hemipelvectomy and rotation plasty of the hip respectively.

Adolescent↗