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Biomedical subjects

A Rüter

Publications and source records attributed to A Rüter.

At least 19 recordsLinked to original sources
PubMed2007

[Biomechanical evaluation of glenohumeral stability through muscle force vector analysis. Effect of a decreased glenoid inclination in shoulders with global rotator cuff tears].

OBJECTIVES: The aim of the study was to quantify the decrease in glenohumeral stability following a global rotator cuff tear and to evaluate the effect of a decreased glenoid inclination angle through analysis of muscle force vectors in a computer model. MATERIAL AND METHODS: The lines of action of eight shoulder muscles were integrated into a standard geometric model. Muscle force magnitudes were estimated based on physiological cross-sectional area and normalized electromyographic activity. The magnitude and elevation angle of the resultant force vector was calculated at 0, 30, 60, and 90 degrees of abduction. A rotator cuff tear was simulated by reduction of the corresponding muscle force vectors. RESULTS: At 0 and 30 degrees of glenohumeral abduction a global rotator cuff tear showed a resultant force vector pointing outside the glenoid. In the computer model, decreasing the inclination angle of the glenoid by 30 degrees increased the stability in rotator cuff-deficient shoulders. CONCLUSIONS: The results of this study provide a biomechanical rationale for clinical complications of global rotator cuff tear such as superior humeral head translation. The decreased glenoid inclination simulated in the computer model may represent a biomechanical basis for the development of new operative techniques to treat global rotator cuff tears.

Biomechanical Phenomena↗
PubMed2006

First results with the trochanter fixation nail (TFN): a report on 120 cases.

A complication rate between 4-18% for the conventional osteosynthesis of the proximal femur fracture continues to be unacceptable even if increasing age and co-morbidity of patients are taken into account. Therefore, new intramedullary techniques are under development, and we here report our results with the novel trochanteric fixation nail (TFN). During the study period (March 2003-February 2004) all patients with a trochanteric fracture Type A1-A3 (AO/ASIF classification) were eligible for the study, and 120 patients (mean age 81 years, range 47-100; male/female 1:4) subsequently enrolled. Most frequent was the (according to the AO classification) A.2.1. type of fracture (n=39) and the A.2.2. fracture (n= 39). Operation time from cut to stitch was 45 mins (minimal 21/maximal 194). Thirty-seven (31%) postoperative X-rays were classified as very good, 60 (50%) as good, 18 (15%) as satisfying and five (4%) as bad post-reposition results according to the Garden Alignment Index. The clinical results were documented by the time of hospital stay, postoperative mobilization and time of rehabilitation compared to the old social status. Time to hospital discharge was 17 days (9 /25). Overall complication rate was 7.5% (9 patients) with 5.8% [7] local wound infection; 1.6% [2] cutting out of the helical blade through the cortex of the femoral head. We had three (2.5%) hospital deaths in our patient group. We conclude that TFN is a safe and reliable technique. Compared with techniques like PFN and Gamma-nail, clinical results are excellent with less complications.

Aged↗
PubMed2003

[Proximal humeral fracture in the elderly. Primary head replacement as one alternative].

The treatment of humeral fractures in old patients is still an orthopedic problem. Different surgical schools suggest different treatments for head-preserving procedures. Because of new implants and functionally disappointing results in primary hemiarthroplasty, the indication for hemiarthroplasty was examined more critically. The decision of which procedure to choose is complicated by the lack of proper studies with comparable fracture types and enough cases regarding the specific problems of operative fracture treatment in the elderly. Correctly, besides range of movement, the number of necessary reoperations, length of time until pain reduction, and earliest possible axial weight-bearing of the injured limb should influence the therapeutic decision. Regarding all these topics, primary hemiarthroplasty in old patients and specific fracture situations is still to be recommended.

Age Factors↗
PubMed2003

[Stabilisation of unstable trochanteric femoral fractures. Dynamic hip screw (DHS) with trochanteric stabilisation plate vs. proximal femur nail (PFN)].

The dynamic hip screw (DHS) with trochanteric stabilisation plate (TSP) as the extramedullary power transmission system and the proximal femur nail (PFN) as the means of intramedullary stabilisation are both standard in the treatment of unstable trochanteric femoral fractures in the case of old people. A total of 129 patients (average age: 81,5 years) with 31 A2.2 and A2.3 as well as per-/subtrochanteric femoral fractures were treated by means of osteosynthesis with DHS and TSP (n=64) or with PFN (n=65),and the results plotted in a retro-/prospective study. At low complication rates, the radiological operation results are equally good. 6 revisions were necessary in the case of the DHS with TSP and 4 in the case of PFN. A significantly shorter operation time (44.3 vs. 57.3 min) and a considerably shorter in-patient stay (18.6 vs. 21.3 days) were common with PFN. The application of full-weightbearing immediately after the operation was possible for 97% of the PFN patients and 88% of the DHS patients. In a follow-up 6 months after the operation, the PFN patients displayed a significantly lower pain intensity in the operated leg at the same score for ambulation and the same subjective degree of satisfaction. Unstable pertrochanteric and per-/subtrochanteric femoral comminuted fractures can be treated just as well with PFN as with DHS and TSP. Our study results,however, lead us to recommend treatment with PFN.

Age Factors↗
PubMed2003

[Experiences with the OrTra-prosthesis in primary prosthetic replacement of fractures of the humeral head--indication, technique and results].

Displaced three - and four - part fractures of the humeral head are at high risk for a poor functional outcome after internal fixation. Primary prosthetic replacement can restore the pretraumatic anatomy and early mobilisation is possible. Functional outcome after hemiarthroplasty of the shoulder joint after trauma however is poor, regardless the type of implant used. However, a stable, painless joint is obtained at a "one time surgery". In our institute from April 1996 until January 2001 fifty-eight primary OrTra-prostheses were implanted. In 43 patients we could perform the follow up. The patients revealed a mean range of active movement from about flex./ext. 54 degrees/0/40 with abd./add. 67 degrees/0/20 degrees. Most important for the patients was the achieved painfree shoulder in 86% (ASES index) of all cases.

Follow-Up Studies↗
PubMed2002

[Focal myositis--an indication for surgery? A case report].

This case report describes focal myositis, a rare inflammatory pseudotumorous disease previously not mentioned in the surgical literature. Most often a single muscle of the upper or lower extremity is affected. Usually the diagnostic process and treatment require a long time. We present a useful diagnostic cascade and a surgical therapy, which allows the histological differentiation between malignant and inflammatory disease. Even after partial resection of the tumor, the prognosis of focal myositis is excellent.

Diagnosis, Differential↗
PubMed2002

[Is low intensity ultrasound effective in treatment of disorders of fracture healing?].

This prospective consecutive study judges the effectiveness of pulsed low-intensity ultrasound for treatment of boney healing disorders. 86 out of 100 treatments were successful. Although in these 100 cases 64 delayed unions and 36 nonunions were enrolled ultrasound therapy was performed as an alternative to the indicated operation in every case. Excluding ten cases of ununited fractures of the scaphoid no additional therapy was performed in any case. Stratifying the data no significant differences in healing rate and treatment time were observed between delayed unions and non-unions and between atrophic and hypertrophic healing disorders. Judging the healing rate of 86% one has to take into consideration that according to our in- and excluding criteria we had a preselected sample of patients. Nevertheless the effectiveness of pulsed low-intensity ultrasound for treatment of disorders of the fracture repair process is evident.

Adult↗
PubMed2002

[Tibial diaphyseal fracture in sports - clinical outcome and sports ability after operative treatment].

Sports-related tibial diaphyseal fractures occur mainly in contact sports and in downhill skiing. Due to the demand for rapid healing and the need for an early recovery of the mostly young patients, surgery is almost imperative. The clinical outcome and sports ability of 38 patients with sports-related tibial diaphyseal fractures were investigated 29 months after the initial trauma. Soccer and wintersport accounted for the majority of injuries. Operative treatment has been mainly unreamed nailing. After an average of 10.3 months 32 patients (84 %) returned to sports. Almost one-third, however did change over to a less stressful sport. 6 patients discontinued their sports activity. The activity score of Tegner and Lysholm declined from 5.4 before the injury to 3.4 six months after surgery. At the time of the follow-up examination this rose to 4.6. The long-term result scored after Merchant and Dietz showed 87 % excellent and good results. For the majority of sports-related tibial diaphyseal fractures, unreamed nailing is the treatment of choice.

Athletic Injuries↗
PubMed2002

[Hip replacement after failed internal fixation in patients with proximal femur fracture--a simple procedure?].

Between January 1995 and December 2000 we operated on 1 437 patients with fractures of the proximal femur. In 789 cases an osteosynthesis was performed and in 648 cases a prosthesis was implanted. In the group of patients with primary osteosynthesis we stabilized 89 fractures with screws, in 319 patients a dynamic hip screw (DHS) and in 381 patients a Proximal-Femurnail (PFN) were implanted. Because of major complications we had to reoperate on 42 patients (5.3 %) with primary osteosynthesis. For analysis of this high complication rate we studied the fracture type, the type of complication, the operation time, the primary and secondary implant type and the time of postoperative mobilisation in this group of 42 patients. We saw 27 type A and 15 type B fractures, according to the AO classification. In the patient group with complications 4 times a primary screw stabilisation was done, 22 dynamic hipscrews (DHS) and 16 proximal femurnails (PFN) were implanted. After changing the primary osteosynthesis into 15 hemiprostheses and 26 total prostheses of the hip, we found in over 30 % major complications. A change of the procedure after primary osteosynthesis has to be regarded as a more difficult operation than the primary implantation of a prosthesis.

Aged↗
PubMed2001

[Indication and technique for shoulder endoprostheses in fractures].

In the treatment of fractures of the humeral head, prosthetic replacement today is accepted as part of the therapeutic repertoire. The indication for this procedure is given if alternative conservative or operative techniques of preserving the humeral head in hemiarthroplasty of the shoulder joint led to universally poor outcomes. The models of endoprostheses that are currently available on the market mainly differ in the stem fixation method and means of securing the tuberosities and rotator cuff. Functional outcome of hemiarthroplasty of the shoulder joint after trauma is less than satisfactory regardless of the type of implant. However, a stable, painless joint is obtained yielding satisfactory subjective patient outcomes. For correct indications for prosthetic replacement of a fractured humeral head the surgeon also has to know the results that can be achieved by other methods in a given situation.

Follow-Up Studies↗
PubMed2001

[Fractures involving the distal femoral epiphysis. Long-term outcome after completion of growth in primary surgical management].

During a period of 12 years (1983-1994) we operated 13 patients with fractures involving the distal epiphyseal cartilage of the femur. All patients could be followed up in clinical and radiological examination following the completion of growth. By examination no patients had any complaints. The clinical examination revealed no limitation in range of motion of the hip or knee joint compared to the other side in any of the patients. 5 patients out of 13 (38%) were found to have a correct axial alignment with no axis deviation, shortening or lengthening of the leg. The other 8 patients (62%) presented the following one- or multidimensional deformities (compared to the contralateral, uninjured femur): 2 patients had varus deformities, 5 patients had valgus deformities, the axial malalignment in the frontal plane was always less than 10 degrees in all cases. 5 patients were found to have a shortened femur (between 8 and 19 mm), while an elongation of the primarily injured femur (10 and 15 mm) was established in 2 patients. On the basis of this study, we recommend that clinical and, if necessary, radiological and/or sonographic examinations are performed following the completion of growth in all patients with injuries involving the epiphyseal plate of the distal femur.

Adolescent↗
PubMed2001

The nail-insertion point in unreamed tibial nailing and its influence on the axial malalignment in proximal tibial fractures.

The consequence of choosing a point of insertion for the nail (i.e. medial or lateral of the lig. patellae) in unreamed tibial nailing (AO unreamed tibial nail, UTN) was studied in 22 formaldhyde-fixed tibiae. A lateral osteotomy at the transition from the first to the second fifth of the tibia was used as a model for the fracture. A nail insertion point medial of the lig. patellae caused a valgus deformity, combined with a shift of the distal fragment to the medial side. A lateral point of entry resulted in a varus deformity, together with a lateral shift of the distal fragment. Our results show that the insertion point of the nail is important for the alignment of the axis. Choosing a different point for the insertion of the nail can be useful in operative correction of malalignment of the tibia.

Biomechanical Phenomena↗
PubMed2001

Radiographic results of callus distraction aided by pulsed low-intensity ultrasound.

OBJECTIVES: To determine whether pulsed low-intensity ultrasound (frequency of 1.5 megahertz, pulsed by one kilohertz, signal burst width of 200 microseconds, intensity of thirty milliwatts per square centimeter, and daily treatment time of twenty minutes per day) stimulates regenerate maturation after callus distraction. DESIGN: Prospective, controlled animal trial. METHODS: Operatively, we created a fifteen-millimeter defect in the right metatarsus of eighteen female mature merino sheep. A segmental transport was begun on Day 5 using a high-stiffness experimental ring fixator. The distraction rate was one millimeter per day divided into two increments of 0.5 millimeters each. On Day 21 after the operation, distraction was finished and the maturation period started and lasted until Day 84 after operation. During this period, Group 1 was treated with a daily twenty-minute low-intensity ultrasound stimulation (frequency of 1.5 megahertz, pulsed by one kilohertz, signal burst width of 200 microseconds, intensity of thirty milliwatts per square centimeter). Group 2 had no stimulation. Animals bore full weight. Plain radiographs in the anteroposterior view were taken every two weeks during the maturation period. After the animals were killed on Day 84, anteroposterior and lateral high resolution radiographs and computed tomography (CT) scans of the regenerate were performed. For each plain and high resolution radiograph, two different relationships (callus relation, the ratio of the amount of periosteal callus to the size of the space between the proximal fragment and transported segment; and interzone relation, the ratio of the fibrous callus interzone to the size of the new formed callus) were calculated. Using CT scan, callus area, bone density, and bone mineral content were evaluated. RESULTS: The results of interzone relation (both views) and callus relation (lateral view) in high-resolution radiographs and bone mineral content in CT indicate a significantly accelerated maturation of the regenerate in the ultrasound stimulated group even when a Bonferroni-Holm adjustment was used for multiple testing. CONCLUSION: Pulsed low-intensity ultrasound appears to stimulate the healing processes in the regenerate in this animal model and may have applicability in clinical practice.

Animals↗
PubMed2000

Ultrasound--an alternative healing method for nonunions?

Several years ago, low-intensity pulsed ultrasound (frequency 1.5 MHz; signal burst width 200 micros; signal repetition frequency 1 KHz; intensity 30 mW/cm2) was shown to accelerate fresh fracture healing both clinically and experimentally. On the basis of a prescription use registry, this paper reports on the use of low-intensity pulsed ultrasound in the therapy of 951 delayed unions and 366 nonunions. The overall success rate for delayed unions was 91% (average healing time 129+/-2.7 days) and for nonunions 86% (average healing time 152+/-5.3 days). Stratifying the data, it becomes clear that patient medication with calcium channel blockers, non-steroidal anti-inflammatory drugs, and steroids is a negative predictor for healing nonunions, as well as renal or vascular insufficiency. Patients who were smokers during ultrasound therapy had lower healing rates than those who never smoked. When comparing the patients of our own clinic treated with low-intensity ultrasound under study conditions which demonstrate that if healing was achieved it was an effect of the ultrasound therapy to the worldwide prescription use registry, no difference was seen in healing rate, healing time, or fracture age. Therefore, the results of these two populations support each other. Low-intensity pulsed ultrasound may provide a method of nonoperative treatment of great promise for healing disorders. Determination of ranking of this new method should be done within the near future.

Adult↗
PubMed2000

[Pigmented villonodular synovitis. A rare differential diagnosis of popliteal space-occupying lesion].

Pigmented villonodular synovitis (PVNS) is a disease that involves the lining of joints, bursae and tendon sheaths. The incidence is low and estimated to be 1.8 patients per million population. The cause of PVNS is unclear and discussed to be either inflammatory or neoplastic. PVNS has been described in 2 forms different for prognosis and treatment (nodular and diffuse). The articular form almost appears in the knee joint as we describe below in a 14 year-old patient. PVNS was first defined in 1941 by Jaffe e.a. [7]. Because of the uncommon occurrence of the disease it is difficult to amass patient series to allow confirmed statements on therapy and outcome. Larger patient series raise out of long periods of time. Differences in outcome and recurrence rates exist for the nodular and diffuse form. Clinical findings are moderate pain and swelling of joints due to effusion and synovial proliferation. Magnetic resonance imaging shows typical findings. Surgical procedures are recommended as open or arthroscopic synovectomy for the diffuse form of PVNS, local excision for the nodular form and arthrodesis or prosthetic replacement for joint destruction.

Adolescent↗