Biomedical subjects

H Bereiter

Publications and source records attributed to H Bereiter.

At least 19 recordsLinked to original sources

PubMed2006

Trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia. A 4- to 14-year follow-up study.

We investigated the clinical and radiological outcome of trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia in 38 consecutive patients (45 knees) with a mean follow-up of 8.3 years (4 to 14). None had recurrence of dislocation after trochleaplasty. Post-operatively, patellofemoral pain, present pre-operatively in only 35 knees, became worse in 15 (33.4%), remained unchanged in four (8.8%) and improved in 22 (49%). Four knees which had no pain pre-operatively (8.8%) continued to have no pain. A total of 33 knees were available for radiological assessment. Post-operatively, all but two knees (93.9%) had correction of trochlear dysplasia radiologically but degenerative changes of the patellofemoral joint developed in 30% (10) of the knees. We conclude that recurrent patellar dislocation associated with trochlear dysplasia can be treated successfully by trochleaplasty, but the impact on patellofemoral pain and the development of patellofemoral osteoarthritis is less predictable. Overall, subjective patient satisfaction with restored patellofemoral stability after trochleaplasty appeared to outweigh its possible sequelae.

Adolescent↗

PubMed2005

[Arthroscopic surgery].

Although arthroscopy of the knee joint had already been reported during the 1930's, the general dissemination of this method first began in the 1970's. The main reason for the rapid dissemination of this method was especially the fact that in addition to diagnostics, therapeutic possibilities were recognized and immediately implemented. This meant that arthroscopy had great potential and was made well known since the surgery was minimally invasive. Today we can assume that the technological side of the arthroscopic method is very widely developed and new innovations only arise slowly. Innovations are mostly connected with new innovative operating techniques. Surgery of the knee joint was the dominant application of arthroscopy in the beginning. The method was quickly applied to other joints. Today there is practically no joint which is inaccessible to arthroscopy. From surgical and therapeutic perspectives, arthroscopy is most frequently used today for the knee joint, followed by the shoulder joint, ankle joint, elbow joint, hip joint as well as wrist joint. Arthroscopic surgery within the field of joint surgery is regarded as indispensable. This specific surgery needs corresponding ability and skill, which must be individually acquired. Arthroscopic surgery evidently depends on technology and accordingly requires a corresponding fully operational medical infrastructure and knowledge. The big advantage of arthroscopic surgery lies in the minimally invasive technique, which has reduced the primary postoperative mortality significantly. Therefore, with good indicators the patient has decisive advantages as well as good cost to benefit ratios.

Ankle Joint↗

PubMed2005

[Actual relevance of minimal invasive surgery in fracture treatment].

Minimal invasive osteosynthesis (MIO) should belong nowadays in the armentarium of each trauma surgeon. The tendency to minimize the invasivity of every operation is a logical development considering the goal of each surgeon to reduce the iatrogenic damage caused by the operation. The term 'MIO" stands for this criteria: Fracture zone not opened, reduction by indirect manoeuvres or percutaneously by joy-sticks, small approaches for the application of the implants, intraoperative assessment of the reduction by imaging (fluoroscopy, arthroscopy, endoscopy, etc.). Long time before the definition of "minimal invasive surgery" some technologies in trauma surgery as external fixator or intramedullary nailing already fulfilled these criteria. In the nineties of the 20th century first cases of percutaneously inserted plate osteosynthesis have been reported. This technique got a widespread acceptance under the term of MIPO (minimal invasive plate osteosynthesis) during the last five years, especially pushed with the new angular stable screw-plate systems (LISS, LCP). The main problem of the MIPO-technique is and remains the reduction (no direct manipulation possible) and their intraoperative assessment (no direct visualisation). The balance between the degree of invasivity and the achieved quality of reduction and stability is often difficult to define and must be related to several factors (localisation and type of fracture, local soft tissue conditions, quality of the bone, age and wishes of the patient, available implants, experience of the surgeon, etc.). New technologies as improved imaging, intraoperative navigation and percutaneous reduction tools will help to further reduce the invasivity of fracture surgery in the future.

Aged↗

PubMed2005

[A comparison of the antiresorptive effects of bisphosphonates and statins on polyethylene particle-induced osteolysis].

An ongoing unraveling of the molecular mechanisms in aseptic loosening of hip arthroplasty has opened up novel potential pharmacological interventions. In this study the antiresorptive effects of the bisphosphonate zoledronate and the statin simvastatin on ultra high molecular weighted polyethylene (UHMWPE) particle-induced osteolysis were compared. Two previous studies of our group based on the murine calvarial model of UHWMPE particle-induced osteolysis were pooled to form four study groups. Animals in group I (n=14) underwent sham surgery only. In groups II (n=14), III (n=7) and IV (n=7) UHMWPE particles were implanted on the calvariae. Animals in groups III and IV were additionally treated with zoledronate (single 25 microg/kg s.c. injection) and simvastatin (120 mg/day p.o. for 14 days), respectively. After two weeks, calvaria were processed for undecalcified histomorphometry. Bone resorption was measured using Giemsa staining. Osteoclast numbers were determined using TRAP-staining. UHMWPE particle implantation resulted in a grossly pronounced osteolytic activity with significantly increased values of bone resorption (p < 0.001) and osteoclast numbers (p < 0.001). Additional treatment with zoledronate or simvastatin counteracted the particle-induced effects. A comparison of the two medical treatments revealed no statistically significant differences in bone resorption (p = 0.63) and osteoclast numbers (p = 0.41). A single dose of the bisphosphonate zoledronate decreased UHMWPE particle-induced osteolysis in a murine calvarial model as effectively as a daily treatment with simvastin. Both drug groups may have a preventive and therapeutic role as antiresorptive agents in wear particle-induced bone resorption following total joint replacement.

Animals↗

PubMed2004

Investigating the effect of remodelling signal type on the finite element based predictions of bone remodelling around the thrust plate prosthesis: a patient-specific comparison.

The resorption of bone in the human femur following total hip arthroplasty is recognized to be related to the loading in the bone surrounding the prosthesis. However, the precise nature of the mechanical signal that influences the biological remodelling activity of the bone is not completely understood. In this study, a validated finite element modelling methodology was combined with a numerical algorithm to simulate the biological changes over time. This was used to produce bone remodelling predictions for an implanted thrust plate prosthesis (Centerpulse Orthopedics Limited) in a patient specific bone model. The analysis was then repeated using different mechanical signals to drive the remodelling algorithm. The results of these simulations were then compared to the patient-specific clinical data, to distinguish which of the candidate signals produced predictions consistent with the clinical evidence. Good agreement was found for a range of strain energy based signals and also deviatoric remodelling signals. The results, however, did not support the use of compressive dilatational strain as a candidate remodelling signal.

Bone Plates↗

PubMed2002

[Cementless socket fixation based on the "press-fit" concept in total hip joint arthroplasty].

PURPOSE OF THE STUDY: The key problem of implant fixation in THR is stress distribution, i.e. load transmission between bone and implant. The closer the load transfer is to the original physiological situation, the easier the adaptation of the periprosthetic bone to the new biomechanical conditions after implantation of the cup and the safer is its longlasting fixation. The aims of the studies were 1) to get information about the physiological load transfer in the normal hip joint, 2) to get information about the load transfer between acetabulum and acetabular sockets and vice versa, 3) to measure the periacetabular pelvic bone deformation as the stimulator of the remodelling process (third stage of osseointegration) in the normal hip joint and in hip joints fitted with different acetabular cups, 4) to study the morphological stages of osseointegration of a non-cemented press-fit cup and to compare the morphological structure of the periacetabular bone with the biomechanical data obtained by the in vitro studies and finally, 5) to compare the clinical and radiological outcome of follow-up studies of the senior author's "Press-Fit cup" with the theoretical hypotheses according to the experimental observations. MATERIAL AND METHODS: Load transfer between the acetabular bone and the femoral head on one side and press-fit cups has been determined by strain gauge measurements, finite element studies, pressure sensitive Fuji prescale films, CT-osteoabsorptiometry and telemetric measurements. Periacetabular deformation has been measured by Imetric Markers. Osseointegration of the senior author's press-fit cup and, thus, the remodelling process of the bony structures adjacent to the cup have been studied in autopsy specimens of THRs which have been in situ for several years. RESULTS: Load transfer measurements have shown that the main load in the original acetabulum as well as in the acetabulum fitted with a press-fit cup is transmitted to the periphery, especially to the acetabular cortical rim whereas the subchondral bone is exposed to lower, predominantly meridional (tension) stresses. Direct measurements of the periacetabular deformation under load revealed an increase of the peripheral press-fit with increasing stability of a (oversized) press-fit cup. Both the normal as well as the acetabulum fitted with a non-cemented cup deforms in a postero-medial direction. The histo-morphology of the periacetabular bone of autopsy specimens showed excellent bony in- and ongrowth of a porous titanium coating (SULMESH) and bone formation, especially at the periphery in zone 1 and 3 according to DeLee and Charnley. CONCLUSION: The studies have shown that the subchondral bone plate of the acetabulum has very little supportive function for non-cemented press-fit cups. For the preparation of the acetabulum it is, therefore, more important to ream the sclerotic subchondral bone until there is a well vascularized, well bleeding bone bed to facilitate osseointegration of a non-cemented acetabular socket than to preserve the subchondral bone plate as is the case in cement fixation. A non-cemented press-fit socket must transmit load predominantly to the cortical bone of the acetabular rim. Therefore, a too far medial positioning of the cup, and therefore loosing contact to the cortical rim, must be avoided under all circumstances. The clinical experience with acetabular revisions and with conversions of hip arthrodeses into a THR (where there is no subchondral bone at all) have shown the superiority of a well vascularized over a sclerotic (even mechanically stronger) bone bed. Furthermore, it has been shown that the additional use of screws for fixation of an acetabular cup is not only unnecessary but can be deleterious and causes complications including osteolysis and aseptic loosening.

Acetabulum↗

PubMed2001

[Palliative surgery for bone metastases].

Advances in the treatment of patients who have bone metastases are an issue of high importance to the orthopaedic surgeon. Early diagnosis requires knowledge of the pathogenesis of bone metastases. A primary route of metastatic cells is via Batson's vertebral vein plexus. An understanding of the pathophysiology enables the surgeon to plan effective treatment. As many patients continue to survive for prolonged periods following the detection of bone metastases, it is important to plan treatment that relieves pain and is functional. In long bones non-operative treatment with radiotherapy, patient education to avoid excessive torsional loads and systemic chemotherapy or hormonal therapy as well as diphosphonates are utilized for small lesions with less than 25 percent of the cortical diameter. The indications for surgical treatment include lesions with elevated fracture risk according to Mirels score. Special emphasis is led on the surgical treatment of spinal metastasis. Early and effective treatment improves the remaining quality of life in patients with metastatic bone disease. However a firm knowledge of the pathogenesis and pathophysiology helps the clinician in making an early diagnosis. Nevertheless the orthopaedic surgeon must recognize the need to approach management of these patients from a multidisciplinary perspective in cooperation with the oncologist, radiotherapist, rehabilitation medicine specialist, radiologist, and pathologist. The cooperation among all members of the team will assure the best possible care for the patient who has metastatic bone disease.

Bone Neoplasms↗

PubMed1998

[Leg pain from the orthopedic viewpoint].

The purpose of this paper is to analyze the etiology of pain in the lower limb provoked by the locomotor apparatus. Vertebral, pseudoradicular, radicular syndromes, the hip pain including the acetabular rim syndrome, the generally localized knee and foot pain are discussed. Major symptoms and clinical findings necessary for an effective differential diagnosis of the lower limb pain are pointed out.

Diagnosis, Differential↗

PubMed1995

Severe skiing injuries: a retrospective analysis of 361 patients including mechanism of trauma, severity of injury, and mortality.

All ski accident patients requiring an inhospital treatment at our institute from 1984 to 1992 (n = 2,053) were analyzed retrospectively. The incidence, pattern, and severity of the injuries, as well as the 30-day mortality comparing two time slots (1984 to 1988 and 1989 to 1992) were analyzed for the 361 cases classified as "serious" injuries according to the following definitions and groupings: group 1, multiple trauma (Injury Severity Score > or = 18) and patients with multiple fractures (n = 179; group 2, abdominal or thoracic single trauma (Abbreviated Injury Scale (AIS) score > or = 2, n = 58); and group 3, isolated head injuries (AIS score > or = 2, n = 124). Serious injuries were observed in 19% in the first period compared to 16% in the second period (not significant). Two hundred thirty-eight of 361 patients injured themselves by just falling, while 117 collided with some sort of obstacle like other skiers (45), trees or rocks (27), posts, pylons, barriers (20), and moving objects (25) such as piste machines, ski lifts, automobiles, and in one case a helicopter. Six skiers were caught on the ski run by an avalanche. Comparing the two time periods, trauma circumstances did not change significantly. The number of most severe head injuries (AIS score > or = 4) increased from 11.6 to 19.3% (p < 0.05). The overall mortality increased from 2 to 7% (p < 0.05). Group 2 had the best prognosis with no mortality, while group 3 was rated worst with 8%. Skiing remains a major source of serious trauma in winter resort areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

[Experiences with Ilizarov distraction osteogenesis with the AO spindle fixator].

For correction of leg length discrepancies and for the treatment of segmental bony defects we used a modular AO-fixator knowing that the principle of the distraction osteogenesis is not dependent of a special fixation device. In our small series the AO-fixator proved to be a good alternative to the ring fixator of Ilizarov for the use on the tibia but not on the femur where we noticed a relatively high incidence of complications, especially deformities of the axis. The distraction osteogenesis has proved to be an efficient technique for limb lengthening and segmental bone transport but is high demanding for the patient and the surgeon.

Adolescent↗

PubMed1994

[Blessings of technology? The severely injured skier--a result of technical equipment on the ski slope].

In a retrospective manner we studied the injury pattern of 2053 patients following a skiing accident that required hospital admission in the year 1984-1992. Of these 361 or 18% were categorised as severely injured according to the AIS/ISS scoring system. 31% of these 361 skiers were injured by colliding at considerable speed with either a moving object (other skier, snow cat, ski-lift, etc) or fixed obstacles (trees, rocks, pilons, etc) along the ski slopes. As the most extensive injuries seem to result from collisions with the latter, fixed obstacles, it should be requested that more protective measures are being taken to prevent such severe accidents.

Adolescent↗

PubMed1994

[Epidemiology, treatment and long-term results of spinal fractures at a non-university affiliated central hospital with special reference to fractures of the lumbar spine].

In a retrospective study epidemiology, treatment, clinical and radiological results of 283 patients with spine fractures in a five-year period are presented. The operation rate ranges from 42% of the cervical to 9% of the thoracical and 24% of the lumbar spine. We found good radiological results concerning the correction of the wedge compression and the collapse of the lumbar vertebral body by fixation with an internal fixator. After a follow-up of 2-5 years nearly 80% of conservative as well as operative treated patients had more or less residual back pain. Because there is a correlation between the quantity of pain and the radiological dislocation, exact initial diagnosis, without overlooking an instability, and adequate conservative or operative treatment is very important.

Adolescent↗

PubMed1993

[Initial results with the unreamed AO tibial nail].

It is generally accepted that intramedullary nailing in combination with reaming should be avoided in treating open fractures. However, the use of an unreamed, solid nail combined with interlocking also allows stabilization of open and complex fractures. 20 tibia fractures (65% open, 45% complex fractures) have been treated by the AO unreamed tibial nail (UTN), 12 (5 of them open fractures) by direct nailing and 8 after initial stabilization by an external fixator. In our series no intraoperative complications, no soft-tissue healing problems and no infections occurred. Thus, treatment of both open and comminuted fractures by UTN appears to be safe and generally needs no secondary stabilization.

Adult↗

PubMed1993

Long-term results with the uncemented thrust plate prosthesis (TPP).

The long-term clinical results of a novel concept for total joint replacement called the Thrust Plate Prosthesis (TPP) are presented. Only a restricted number of patients were provided with this new prosthesis (115 at the Orthopedic Department, Canton Hospital, Chur, and 47 at the Department of Orthopedic Surgery, University of Zurich). All patients have undergone clinical and radiological follow-up covering a period from 1980 to 1991. The basic feature of the Thrust Plate Prosthesis is the direct load transfer to the medial cortical bone of the femoral neck, and this has been unchanged since 1978. Titanium alloy has been used since 1986. The good clinical and radiological results are confirmed by a histological examination of an 8-year-old implant: In the crucial area of load transfer newly formed bone can be seen in direct contact with the thrust plate without fibrous tissue in between. The clinical results and histological findings have confirmed the validity of the biomechanical principle of the TPP. The TPP is therefore to be considered a true alternative to the conventional hip prosthesis. In contrast to the conventional intramedullary anchored stem prosthesis the TPP requires the removal of a minimum amount of bone stock, which is certainly important in young patients.

Adult↗

PubMed1993

[The dynamic hip screw (DHS) in femoral neck fractures].

Out of 224 patients with femoral neck fractures, 40 patients have been treated by ORIF with the dynamic hip screw, whereas 27 have been fixed by large cancellous bone screws and 148 femoral heads were replaced by a prosthesis. The ORIF with dynamic hip screw has been performed as an emergency intervention within 6.2 hours after accident. Good general condition without contraindication against an emergency operation as well as a biological age below 65 years and no pre-existing coxarthrosis are mandatory for the indication for open rigid internal fixation. Personal follow-up of 37 patients with x-ray documentation after at least 18 months (mean 35.4 months) showed complete rehabilitation in 31 patients and 4 femoral head necrosis (10.8%). We conclude that these good results are due to the short interval between accident and operation as well as to the evacuation of the intraarticular hematoma together with stable internal fixation and functional rehabilitation. Due to our good results we prefer long cancellous bone screws for the operative fixation of femoral neck fractures in younger patients, whereas in the older group the dynamic hip screw is preferred.

Adolescent↗

PubMed1993

[Initial experiences with the unreamed AO tibial nail].

It is generally accepted that intramedullary nailing in combination with reaming should be avoided in treating open fractures. However the use of an unreamed, solid nail combined with interlocking allows stabilization also of open and complex fractures. 20 tibia fractures (65% open, 45% complex fractures) have been treated by the AO unreamed tibial nail (UTN), 12 (5 of them open fractures) by direct nailing and 8 after initial stabilization by an external fixator. In our series no intraoperative complications, no soft-tissue healing problems and no infections occurred. Thus, treatment of both, open and comminuted fractures by UTN appears to be rather safe and generally needs no secondary stabilization.

Adult↗

PubMed1992

[The temporal behavior of the anchorage of a cement-free implanted acetabular cup in animal experiments].

The mechanical qualities of the cementless press-fit cup of a hip prosthesis were examined in sheep. Primary anchorage of the cup is achieved by relative oversize of the cup in relation to the acetabulum, causing a press-fit effect. The surface of the cup consists of Sulmesh, a titanium net, which allows bony ingrowth. The quality of the mechanical anchorage in the acetabular bone was tested by measurements of the torque and cranio-caudal tilting moment needed to pull out the cup. It was shown that the secondary biological anchorage of the press-fit cup exceeds the primary mechanical anchorage (measured in previous in vitro experiments) by a factor of three. This improvement of the mechanical fixation of the press-fit cup in the acetabular bone can be explained by bony ingrowth into the Sulmesh and can be confirmed by histological findings.

Acetabulum↗

PubMed1991

[Interlocking intramedullary nailing of the femur: is the advantage of early mobilization gained by risking a malposition?].

We report a follow-up of 57 consecutive femoral fractures treated by internal fixation with the AO Universal Interlocking Nall. All fractures (91% follow-up) had healed within a mean of 22 months (range 9-50) after operation. Full weight-bearing was possible after an average of 9 weeks (range 2-20). The only infection occurred after a secondary open lengthening osteotomy. In 5 cases a rotational malposition or length discrepancy had to be corrected shortly after initial surgery. Rotational malposition in excess of 10 degrees occurred in 26% of cases (mostly external rotation) and length discrepancy exceeding 1 cm in 13% (mostly shortening). The frequency of malposition is explained by the absence of rotational or length control during operation. We recommend that malposition be correlated without delay by reoperation.

Adolescent↗