Biomedical subjects

H J Refior

Publications and source records attributed to H J Refior.

At least 73 records · Page 4Linked to original sources

PubMed1997

[Reconstruction of acute anterior cruciate ligament rupture by suture and semitendinosus tendon augmentation.].

GOAL OF SURGERY: Restoration of normal knee function. INDICATIONS: Acute avulsion of the anterior cruciate ligament (ACL) from its femoral origin. CONTRAINDICATIONS: Mid substance and remote tears. POSITIONING AND ANAESTHESIA: Supine. Knee flexed, hip bent to 30 degrees . General or regional anaesthesia. SURGICAL TECHNIQUE: Step 1: Arthroscopy to confirm site of rupture, meniscus repair if necessary. Step 2: Mobilisation of semitendinosus tendon, left attached distally. Step 3: Mini-arthrotomy, securing of ACL stump with atraumatic suture. Step 4: Transfer of ST-tendon through 5 mm drill holes through tibial head and lateral femoral condyle. Step 5: Fixation of tendon and ACL-sutures with staple at the exit of the femoral drill hole. POSTOPERATIVE MANAGEMENT: Knee orthosis for 6 weeks, CPM, physiotherapy. ROM day 0-2: 0-10-10 degrees ; day 3-11: 0-0-60 degrees , day 12-42: 0-0-90 degrees . Increase of weight bearing 10 kg/week from operation date. Bicycling and running permitted 3 months post-op. Full sport activity after muscle power has reached that of opposite side. LMW heparin until full weight bearing. POSSIBLE COMPLICATIONS: Thrombosis. Embolism. Infection. Failure of reconstruction. Osteoarthritis. RESULTS: During 1 year, 116 patients were operated. Follow-up after 42 to 57 months (average 52 months) included 95 patients (82%). Of these, 76 underwent full examination (average age 33 1/2 years, 20-49 years), 11 answered a questionnaire, 8 had suffered re-injury. Average Lysholm score was 92 points (+/-13). Tegner activity scale amounted to 7.2 points pre-injury, 7.1 points at follow-up. Anterior translation (KT 1000 arthrometer testing at 89 N) was identical to opposite side in 25 patients, less than 2 mm in 14, up to 4 mm in 19, up to 6 mm in 15, more that 6 mm in 3 patients. Pivot shift was negative or trace 73 times, and positive in 3 patients. ROM was full in 54 patients, 17 times the flexion was limited up to 10 degrees . Ten times extension lag was less than 5 degrees , and twice between 5 and 10 degrees .

English Abstract↗

PubMed1997

[Comparative tribological studies of Chirulen, Hylamer and Enduron combined with A1203].

The creep and wear behaviour of Chirulen, Hylamer and Enduron, materials which differ only in their manufacturing procedures, was examined and compared. Chirulen is manufactured by being pressed into form by plates, whereas Hylamer and Enduron are shaped by tubes. Hylamer differs from Enduron in that intermediate material processing is undertaken with the goal of improving the initial material. The wear and deformation rate was determined by means of the ring-on-disc testing device after 360,000 cycles and after 1.0 x 10(6) cycles, respectively. The static tests for the determination of wear were carried out at a contact stress of 5.62 MPa and a testing time of 100 h in analogy to the ring-on-disc tests. Chirulen and Hylamer demonstrated comparable wear with a tendency toward a lower wear rate in Hylamer, while Enduron presented a clearly higher wear rate.

Biocompatible Materials↗

PubMed1997

[Experimental studies of metal-metal slide combinations and their value in relation to expected in-vivo behavior].

A simulator test was carried out in the hip joint simulator on a metal-on-metal coupling of a modified CoCrMo alloy. The test was run up to 1.9 million cycles and the tribological behaviour of the coupling was documented by means of roundness measurements and scanning electron microscopy. It is seen that the tribological system metal on metal is characterized by mixed friction in the artificial hip joint, thus generating material contacts that are documented by the roundness variation and by the SEM contact zone analysis, showing "three-body" wear of this system. The roundness variations indicate that running-in wear is to be noticed at first with a decreasing tendency over the 1.9 million cycles. Nevertheless, this observation does not allow any prognosis as to the wear rates in the case of a higher number of cycles. It must be taken into consideration that aqua destillata had to be used as a lubricant for technical reasons; the use of serum/Ringer solution might have produced different results. Further investigations in the hip joint simulator and on revised metal-on-metal couplings will be carried out in this respect.

Biomechanical Phenomena↗

PubMed1997

Acute calcific tendinitis of the pectoralis major insertion associated with cortical bone erosion.

A case of calcific tendinitis of the pectoralis major insertion with cortical bone erosion is presented. Clinical and laboratory findings showed a significant inflammatory reaction. Both CT and MR images demonstrated the extent of the lesion providing additional information on the dimensions of inflammatory soft tissue and bone marrow reaction. Biopsy was performed and histology revealed the typical features of calcification, inflammation and giant cell reaction.

Adult↗

PubMed1997

MRI of posttraumatic cyst-like lesions of bone after a greenstick fracture.

Posttraumatic bone-cyst formation is a known but rare process. Typical location is the distal radius, usually as a result of a greenstick fracture. The pathogenesis is unknown; however, subperiosteal migration of fat or hemorrhage with later absorption may cause cyst formation. We present the first reported case of MR imaging of this lesion. At MRI subperiosteal hemorrhage was found to be the cause of cyst formation.

Bone Cysts↗

PubMed1996

Primary leiomyosarcoma affecting the ankle joint.

In a 50-year-old patient with a malignant tumor of the left distal tibia (stage la, according to Enneking) undermining the cartilage of the ankle joint, an extremely rare primary leiomyosarcoma of bone was diagnosed. The diagnosis of a primary leiomyosarcoma of bone is possible only after a secondary (metastatic) leiomyosarcoma has been excluded. Furthermore, typical histopathological features, including immunohistochemical staining results, are required for the diagnosis. Surgery is the therapy of choice. An R0 resection should always be attempted.

Adolescent↗

PubMed1995

[Effect of the manufacturing process on creep and wear properties of UHMWPE (ultra-high molecular weight polyethylene)].

The creep and wear behaviour of pressed UHMWPE and extruded UHMWPE was compared, taking Chirulen and extruded UHMWPE of the Lennite type as examples. Using the ring-on-disc test, the wear and deformation volumes per 360,000 cycles were determined. The static tests were performed at surface pressures of 5.62 MPa and 9.37 MPa, while the test duration was 41.86 and 100 hours, respectively. The surface pressures result from the axial forces of 900 N and 1500 N, respectively, and a ring surface analogous to the DIN 58,835 and ISO 6474 standards. Between conventionally pressed and the extruded UHMWPE material differences of up to 350% in the sums of wear and deformation were found. It was noted that already at low surface pressures the extruded UHMWPE is more susceptible to creep deformation than is the conventionally pressed material, and that this effect dramatically increases at high surface pressures.

Biomechanical Phenomena↗

PubMed1995

[Clarification of the concept humeroscapular periarthritis].

Shoulder pain may be due to various reasons. It is primarily produced by changes in the periarticular structures of the shoulder joint. The term "periarthritis humeroscapularis" (PHS), often used at diagnosis, is unsuitable however because it prevents differentiation of the various clinical pictures related to the anatomical structures. Among the anatomical structures concerned, above all the rotator cuff and here especially the suprasinatus muscle must be mentioned. Also the long biceps tendon and the shoulder joint capsule are, according to Welfling, locations of painful processes, not to forget the subacromial bursa. The pathology responsible for the clinical symptoms and signs is primarily produced by degenerative changes. They lead to tendopathy, as well as to tendon rupture, and also seem to be of importance in connection with calcifying tendopathy. Capsule shrinkage in shoulder stiffness can also be influenced by neighboring degenerative processes. This also applies to isolated bursitis. Today thorough clinical and radiological clarification makes a differentiated diagnosis possible so that the vague term "periarthritis humeroscapularis" can be dropped.

Diagnosis, Differential↗

PubMed1994

Surgical treatment of acromioclavicular dislocation.

Sixty-five patients were operated on for acromioclavicular dislocation between 1980 and 1991. Seventeen type II and 48 type III dislocations according to the criteria of Tossy et al. were treated. Three different surgical techniques were employed. (1) tension band wiring, (2) a modification of the Bosworth repair, (3) reconstruction of the ligaments with augmentation by a PDS (polydioxanon) cord. Forty-four patients could be investigated retrospectively, and an additional 12 were recorded by questionnaire. The Taft score was used, representing self-assessment, clinical statements and radiological findings. Of all investigated patients 87.5% had a normal range of motion without any loss of strength, and 32% suffered an osteoarthritis of the acromioclavicular joint. The average Taft score was 9.8. With respect to the three surgical techniques, reconstruction of the ligaments augmented by a PDS cord produced the best result, an average Taft score of 10.8.

Acromioclavicular Joint↗

PubMed1994

[MRI in orthopedics: diagnosis of joint disorders].

For the visualization of joint structures, magnetic resonance imaging (MRI) has definite advantages over other imaging modalities. High soft tissue contrast and multiplanar capabilities contribute to adequate representation of the joints. With surface and special coils as well as high gradient field strengths, superior spatial resolution can be achieved, thus allowing for depiction of fine anatomical details. Newly developed pulse sequences, especially with fat suppression techniques and utilization of paramagnetic contrast agents (gadolinium complexes) have improved image contrast. Examination techniques, results and diagnostic value of MRI in various joints are discussed. Close cooperation between orthopaedic surgeons and radiologists is mandatory for effective and economically acceptable use of MRI in the diagnosis of joint disorders.

Ankle Joint↗

PubMed1994

[Results of surgical treatment of posterior knee instability].

A retrospective study was performed to evaluate the outcome of operative treatment of posterior cruciate ligament (PCL) lesions in 115 patients operated on between 1980 and 1989. Follow-up was possible in 89 patients at 18-124 months postoperatively (average 76 months). In 65 re-examination was possible, while 24 patients returned a questionnaire. The results of patients who were operated on in the acute state were superior to those with chronic instabilities (Lysholm 79.9 +/- 18.5 vs 64.3 +/- 22.1; Tegner 5.7 +/- 2.3 vs 4.2 +/- 2.2; instrumented posterior drawer 5.3 +/- 3.5 mm vs 5.9 +/- 3.8 mm). On the other hand, the preoperative scores of symptomatic patients with chronic instabilities (Lysholm 38.8 +/- 22.0; Tegner 2.1 +/- 1.7) were clearly lower. Extraarticular procedures (Hughston) slightly improved symptoms in posterolateral instabilities. Olecranization of the patella had no influence on the results. Interpretation of the data is difficult as there was no matched group of patients with nonoperative treatment. A reviews of the literature suggests that isolated PCL tears are best treated with conservative management. Only in cases where associated ligamentous injuries require operative treatment should PCL reconstruction be performed. Chronic posterior instabilities should be treated operatively only if the patients are severely symptomatic. However, complete restoration of knee stability was usually not achieved with the techniques presented in this paper.

Adolescent↗

PubMed1993

Mechanical failure of the femoral component in cemented total hip replacement--a finite element evaluation.

The quality of cementation is of paramount importance for the long-term clinical outcome in cemented total hip replacement. Four "modes of failure" have been differentiated by various authors and correlated with the clinical findings. A finite element analysis was performed to simulate an ideally cemented femoral stem-type prosthesis as well as failure modes III (proximal anchorage of implant only) and IV (Distal anchorage of implant only). While failure mode III produces a stress distribution at the bone/acrylic cement interface, which is similar to the ideally cemented prosthesis, failure mode type IV leads to a hazardous rise of the interface stresses. This correlates well with the clinical findings given in the literature, thus validating the computer simulation used. Distal cementation only of a stem-type femoral component in total hip replacement should definitely be avoided.

Bone Cements↗

PubMed1993

The importance of arthroscopy in sports injuries in children and adolescents.

Within a 3-year period (1985-1988), 60 children and adolescents with knee injuries sustained mainly while skiing or playing football (soccer) underwent clinical examination, X-radiography and arthroscopy. Nearly all the patients still had open epiphyseal plates in the knee region. Arthroscopy revealed more severe intra-articular trauma than had been suspected on the basis of clinical findings. The skiing injuries most commonly involved anterior cruciate ligament tears, whereas injuries of the patellar retinaculum and medial meniscus lesions predominated in soccer injuries. On comparison with arthroscopic diagnosis, clinical diagnosis was erroneous in about 45%. The most common mistaken clinical diagnosis was "medial meniscus tear". Of the 60 knee joints subjected to arthroscopy, 40 were severely enough injured to warrant surgery. Only one had normal intra-articular findings. The study demonstrates that children and adolescents can suffer knee trauma requiring surgery, despite open growth plates. Downhill skiing and soccer are particularly risky sports in this respect. Therefore, sports injuries involving haemarthrosis are clearly an indication for arthroscopy, even in childhood and adolescence. Arthroscopy enables early identification of the type and extent of intra-articular trauma and subsequent early initiation of appropriate therapy.

Adolescent↗

PubMed1993

[Possibilities for HIV inactivation in homologous bone transplants].

Recently, the availability of bone allografts has declined dramatically, due to the three-month HIV test which is often difficult to obtain. Accordingly, there is a search for methods to inactivate HIV in bone allografts without compromising the biologic quality of the grafts. Chemical substances require long exposure and desorption times, to ensure that no toxic agents remain within the bone before actual transplantation. X-ray inactivation leads to complete loss of any osteoinductive properties of the allografts, according to some authors. In addition, the high doses that are necessary are difficult to apply. Autoclaving has been practiced in some instances, but all experimental results and some more recent clinical observations warn that osteoinductive properties of the allografts are lost during the autoclaving process. Lower temperatures (56 degrees C) are sufficient to warrant inactivation of HIV, and some experimental results and preliminary clinical observations indicate that moderate heat treatment of bone allografts in a water bath may become a useful method for virus inactivation of bone allografts.

Bone Transplantation↗

PubMed1993

[Primary suture of the anterior cruciate ligament. A critical analysis].

Recently some authors have claimed that primary repair of an acute tear in the anterior cruciate ligament will fail in the long run. A review of the literature reveals that this opinion is mainly based on an American study in 1976. However, the poor results presented in this study were never reproduced. The study is critically analyzed, and 14 more papers presenting successful primary reconstructions of the anterior cruciate ligament are discussed. Preserving proprioceptive structures may be an important advantage of this technique, as it is hypothesized that the anterior cruciate ligament functions as a significant sensory organ, not only providing proprioceptive information, but also initiating protective and stabilizing muscular reflexes. In conclusion, it is recommended that primary suture be used combined with intra-articular semitendinosus tendon augmentation for rapid rehabilitation in cases of acute tears in the anterior cruciate ligament.

Anterior Cruciate Ligament↗

PubMed1992

Clinical results and radiologic findings after cementless implantation of PCA stems in total hip replacement.

The results of radiologic and clinical follow-up of 81 PCA (porous coated anatomie) hip joint prostheses implanted in our clinic between 1986 and 1988 are presented. One of the prostheses had to be explanted because of aseptic loosening after 2.5 years' implantation. Contrary to the fixation concept of the prosthesis, which requires both proximal osseointegration and free axial shifting of the distal part of the prosthesis, our follow-up radiographs showed proximal lysis of 2 mm and more as well as distal hypersclerosis of 3 mm and more in the form of endosteal bone formation in 70% of cases 3 years after implantation. On the basis of our data, the question whether these bone reactions will finally lead to aseptic loosening of the implant cannot be answered yet.

Biomechanical Phenomena↗

PubMed1992

Bone-cement removal with the excimer laser in revision arthroplasty.

The excimer laser was thought to be an appropriate tool for the removal of bone cement without damaging the bone. However, due to its low ablation rate, its clinical use in total hip revision arthroplasty proved to be impossible. This experimental study was designed to evaluate the maximal ablation rate by adjusting the laser's parameters. Energy density, frequency, pulse duration, radiation area, quantity of pulses, and environmental conditions were varied in the experimental setup. Even with the best set of parameters the excimer laser was about ten times slower than, e.g., the carbon dioxide laser. The removal of 10 g bone cement takes about 1 h. Thus, complete cement removal by means of the excimer laser alone is not possible. However, selective application of the excimer laser in combination with other techniques could be discussed.

Arthroplasty↗

PubMed1992

Moderate heat treatment of bone allografts. Experimental results of osteointegration.

The use of bone allografts is often essential in orthopedic surgery. Strict donor screening, including HIV testing 3 months postoperatively, is mandatory before a transplant may be used. Yet these measures do not definitely rule out the possibility of HIV transmission, as there is a window period before infection is revealed by blood testing. Accordingly, there is a need for virus inactivation methods that can be used on bone allografts. As radiation treatment and chemical methods have a number of disadvantages, we chose a moderate heat treatment of 65 degrees C for a series of animal experiments. In 12 rabbit femoral condyles, moderate-heat-treated bone allografts were implanted into 6-mm drill holes. Twelve normal allografts and 12 empty drill holes served as controls. Radiologic and histological evaluation up to 12 weeks postoperatively revealed slow spontaneous bone remodeling from the rim to the center of the empty cavities. Normal deep frozen allografts were quickly intergrated after a short period of osteoclast reaction around the transplant, with occasional bone bridges between host and allograft. The examination of heat-treated allografts showed no differences to the controls, including morphologic aspects and the time course of osteointegration. Five zones of bone repair and osteointegration were distinguished. We conclude that thermal treatment of bone allografts has adverse effects on osteointegration in the rabbit femoral condyle. Thus, it may contribute to improving safety in human bone transplantation.

Animals↗