Biomedical subjects

R Forst

Publications and source records attributed to R Forst.

At least 37 records · Page 2Linked to original sources

PubMed1997

Pathogenetic relevance of the pregnancy hormone relaxin to inborn hip instability.

The etiology of inborn hip dysplasia is unknown. In general, a multifactorial genesis is assumed. The influence of hormones on the development of the fetal hip joint and its stability is discussed as well as mechanical influences. This study was carried out with the intention to examine the correlation between the concentration of the pregnancy hormone relaxin and the stability of the hip joint in newborns. Both hips of 90 newborn children were examined clinically and sonographically. In 25 hips (13.9%), pathological sonograms according to the classification of Graf were found. The relaxin concentration was measured in cord blood using a heterologous radioimmunoassay. Statistical evaluation revealed an insignificant decrease of relaxin concentration with increasing sonographic hip instability. The results indicate that hip instability frequently occurs with decreasing relaxin concentration. These facts contradict the earlier assumption that hip instability coincides with increased relaxin concentrations in newborns. We assume that there is a worse preparation of the pelvis and the birth canal during pregnancy due to the lower relaxin concentration and thus that there could be a higher pressure on the fetus in the perinatal phase. A decreased relaxin concentration seems to have no direct effect on the hip joint tissue, but indirectly there is consequent rigidity of the tissue in mother and child, which can further promote the development of hip instability.

Female↗

PubMed1997

Cardiac risks in total hip replacement.

During total hip replacement, identifiable myocardial ischemia occurs intraoperatively, indicating myocardial strain. Coronary heart disease (CHD) patients are at risk during this type of surgery. Perioperatively, CHD patients had significantly longer ST depressions than patients not suffering from CHD (3348 min vs 454 min). The number of depression episodes was also significantly higher for CHD patients (160 vs 36). Comparing the perioperative with the postoperative stage demonstrated that CHD patients experienced a highly significant shift towards shorter periods of ST-segment depression postoperatively.

Aged↗

PubMed1997

Anatomic study of femoral vein occlusion during simulated hip arthroplasty.

An anatomic study was undertaken to establish whether positioning of the leg and surgical approaches for total hip replacement (THR) cause changes in the femoral v. which may contribute to the development of deep vein thrombosis (DVT). The patency of 32 femoral vv. of 18 cadavers was inspected at different levels during simulated THR. Before and after removal of the femoral head through a transgluteal or posterior approach, a wide-angle endoscope was inserted into the femoral v. via the external iliac v. Blood flow was simulated by proximal irrigation with saline through the popliteal v. After removal of the femoral head distinct changes were observed in both approaches. In the transgluteal approach the changes were dependent on the degree of adduction and the body build of the cadaver. Initially, an oval form was seen in a constricted lumen with an increasingly oblique oval deformation and a final facet-like closure, usually at about 5 to 7.5 cm below the inguinal ligament. In total adduction this stenosis occurred regardless of build. Using a posterior approach, the necessary internal rotation caused a closure of the vein in 50% of cases. In combination with flexion and adduction there was stenosis in all cadavers regardless of body build. Our results indicate that the duration of the adducted position of the thigh during THR via a transgluteal approach should be minimised, as there is a reduction in blood flow with even minor degrees of adduction. In the posterior approach the stenosis occurs earlier, and is independent of the build of the cadaver.

Arthroplasty, Replacement, Hip↗

PubMed1997

Scoliosis in Duchenne muscular dystrophy: aspects of orthotic treatment.

The x-linked Duchenne muscular dystrophy (DMD) is the most frequent generalized muscle disorder arising from a lack of the sarcolemmic protein "dystrophin". Patients with DMD develop in the majority a progressive scoliosis when they cease walking and/or standing at the age of 10 years and become confined to a wheelchair. Increasing muscle weakness leads to a progression of the curvature, the pelvic tilt and problems in sitting. Together with the simultaneous progressive weakness of the respiratory muscles a restrictive pulmonary insufficiency will occur. Surgical stabilization of the spine (> 20 degrees Cobb, forced vital capacity > 35%) by an adequate multisegmental instrumentation enabling early mobilization is now the treatment of choice. However, orthotic treatment may offer an acceptable compromise in exceptional cases, if the patient rejects surgical intervention or is in the late (inoperable) stages of the disease. Such a treatment is superior to a primary sitting support provision with insufficient possibilities of correction. The authors' experiences with 48 scoliosis orthoses made for 28 patients with DMD are reported. A "double plaster" cast has emerged as the best method to optimize adaption, especially in severe curvatures and the time taken for manufacturing the orthosis. A great deal of experience, patience and the consideration of the patients' individual demands are inevitable for a successful orthotic treatment.

Adolescent↗

PubMed1996

An experimental study of tensile strength of six different suture techniques.

Tests were carried out on the strength of six different suture techniques used to join polyester lace ends, for example, in interscapulo-scapulocostal scapulopexy. The following sutures were used: four 5-cm rows of a continuous suture, four 2.5-cm rows of a continuous suture, two 5-cm rows of a continuous suture, 4 or 8 interrupted sutures, and 4 U-sutures. The laces were tested in tension, and load and elongation recorded. The strongest techniques involved a suture of four 5-cm rows of continuous thread (average maximum load at point of failure 1484 N). This was higher than the maximum load at failure of the point of attachment to the scapula.

Analysis of Variance↗

PubMed1996

Anatomo-experimental study for lace fixation of winged scapula in muscular dystrophy.

Winging of the scapula is one of the major features of the rare facio-scapulo-humeral muscular dystrophy. Several methods of retention and fixation of the scapulae have been published, but most have technical disadvantages or complications. A modified method of operative fixation of the scapula to the chest using three polyester laces is described with the results of cadaveric studies on the stability of this system. In order to determine the optimal region for the scapula fixation using polyester laces we performed pull-out tests on twenty cadaver scapulae. Four points of insertion in the inferior part of the scapula were tested. The lateral margin showed the best results with regard to the tensile strength and the morphology of the resulting fractures. The elongation of the laces was measured as well. Compared to scapulothoracic arthrodesis interscapulo-scapulocostal scapulopexy leads to greater preserved mobility between the scapula and the chest wall and conserves vital capacity.

Adolescent↗

PubMed1996

Bone cement penetration of the acetabulum in total hip replacement. An experimental study.

Cones of cement passing through, or below, the acetabulum may be seen after total hip replacement and are due either to iatrogenic perforation of the wall or to substantial bony defects. An experimental study was undertaken to establish which structures might be affected by these cones. In 20 cadaveric specimens, the acetabula were divided into 4 quadrants and, after the cement was set, the structures within the pelvis were dissected. In the antero-inferior quadrant the cement impinged on either the obturator nerve or vein, or the external iliac vein. Anterosuperiorly, these structures and the external iliac artery were impinged. In the posterior quadrants, the obturator muscle and nerve, and vessels, were affected, and inferiorly the external obturator muscle was also involved. The size of the cones depended on the bony depth of the acetabulum. Compared with screws, the cement can cause late complications through heat necrosis and continuous friction. The posterosuperior quadrant is the safest area to make holes for anchoring the cup.

Acetabulum↗

PubMed1995

Importance of lower limb surgery in Duchenne muscular dystrophy.

A total of 123 patients with Duchenne muscular dystrophy (DMD) was surgically treated during two different periods of their course by hip and knee release, aponeurectomy of the iliotibial band and z-shaped Achilles' tendon lengthening. In 57 patients (group I) this was carried out prophylactically as retractions of the lower limb joints were just beginning at the age of 6.4 +/- 1.43 years and in 66 patients (group II) as mild contractures of the joints at the end of walking ability were already manifest with an average age of 9.27 +/- 1.86 years. The average follow-up was 3.7 +/- 1.2 years in both groups. To be able to assess the interindividual course of both groups, we defined "joint and motor quotients", which allowed a complex assessment of joint function and motoric capacity. In addition, both groups were compared with a control group (natural history) consisting of 100 non-operated DMD patients. In both groups a significant release of the contractures could be obtained primarily. Patients in group I showed a much better long-term effect than those in group II. The motor quotient in group I was significantly better over the whole follow-up period (P < 0.001) than in group II or the control group. The prolongation of walking ability by about 2 years compared with the natural history is in our opinion not the central goal of this surgical treatment concept of lower limbs in DMD, but rather the additionally achieved prolongation of an assisted standing ability with the lower limbs free from contractures and deformities.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗

PubMed1995

Ipsilateral peroneus brevis tendon grafting in a complicated case of traumatic rupture of tibialis anterior tendon.

Ruptures of tibialis anterior tendon can be caused by open, closed, direct, or indirect trauma, as well as spontaneously. Sixty-three cases of tibialis anterior tendon ruptures have been reported in the international literature. The treatment of choice is the surgical end-to-end or side-to-side anastomosis after previous Z-lengthening. The case of a 28-year-old world-class female triathlete who sustained an open laceration of the tibialis anterior tendon from the bicycle chain guard is reported. The primarily applied tendon suture became infected and a wound revision with wide resection of the tendon stumps was necessary. This lead to an extensive defect of the tendon combined with a deep-seated keloidal scar reaction of the skin. The surgical closure was performed using free ipsilateral peroneus brevis tendon grafting. Four months after the operation the patient was completely rehabilitated. Eight months later she became the second European triathlon champion.

Adult↗

PubMed1995

[Differential therapy of traumatically-induced persistent posterior shoulder dislocation. Review of the literature].

Three-hundred and twenty-nine cases of posterior dislocation of the shoulder documented in 300 articles published in the international literature are reviewed. They included 130 cases in which the duration of the dislocation was longer than 6 weeks and the dislocation could be classified as persistent primary dislocation. This group is the second largest group following that with acute primary dislocation. The mechanism of injury may be direct or indirect force: trauma, convulsions or electrocution are usually responsible for this type of dislocation, which often persists for longer than 6 weeks. Anatomically, 97.5% of dislocations are classified as subacromial. Posterior dislocation of the shoulder is commonly misdiagnosed on plain antero-posterior radiographs, and in over 50% of cases the diagnosis was missed on first examination. The typical signs of primary traumatic posterior dislocation of the shoulder are described. Management of persistent traumatic posterior dislocation of the shoulder depends on the size of the anterior Hill-Sachs lesion, the precipitating mechanism and the duration of dislocation. The results of 109 surgically and 24 conservatively treated dislocations of this type that have been published in the international literature are reviewed. Closed reduction is indicated in carefully selected cases with an anterior Hill-Sachs lesion under 15% of the size of humeral head (measured in the axillary view) that has been dislocation for less than 2 months. In most due to convulsions there was a distinct anterior Hill-Sachs lesion, which led to recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthroplasty↗

PubMed1995

Atraumatic recurrent posterior shoulder subluxation: review of the literature and recommendations for treatment.

Isolated atraumatic recurrent posterior subluxation of the shoulder (ARPS) constitutes 1% of all shoulder subluxations; it is therefore difficult for any single clinic to gain a large experience in treating this condition. Based on a review of the literature 83 cases of ARPS out of 237 reported cases with all types of posterior subluxation of the shoulder (185 patients) were analyzed. Most cases of ARPS occur between 11 and 20 years of age; they are frequently associated with changes such as dysplasia of the glenoid labrum or an alteration in the spinoglenoid angle. More than half of all ARPS occur bilaterally. The diagnosis is based on history, physical examination including tests of instability, or on techniques of dynamic examination (ultrasonography, arthroscopy). A plan of management related to the underlying etiology has been developed. At the first occurrence, cases of subluxation should be treated conservatively by kinesitherapy and physical therapy. Operative treatment is indicated when conservative management for at least 6 months has been unsuccessful and subluxation continues to occur during everyday activities, but it should never be instituted in patients with emotional disorders. The underlying pathologic lesion should determine the technique for shoulder reconstruction in atraumatic posterior shoulder subluxation. In cases in the atraumatic voluntary subgroup, surgery is indicated if conservative treatment fails and the voluntary component has been eliminated. In this subgroup, isolated soft tissue procedures have not been shown to produce good long-term results, and supplementary bony procedures are considered necessary. Conservative treatment exclusively is recommended in voluntary cases.

Adolescent↗

PubMed1994

Posterior dislocation of the shoulder: recommendations for a classification.

Posterior dislocation of the should is rare, constituting only 2.1% of all shoulder dislocations. The mechanisms of injury may be due to direct or indirect forces, and constitutional predisposing factors also play a role. Anatomically, 97.5% of dislocations are subacromial. Three hundred articles published in the international literature concerning posterior shoulder dislocation and subluxation were reviewed and a classification determined by the underlying aetiology was developed. On this basis dislocations and subluxations may be traumatic or atraumatic, primary and recurrent; recurrent cases of voluntary dislocation are considered separately. In addition, a follow-up assessment score weighted towards stability of the shoulder after treatment is detailed.

Humans↗

PubMed1994

[Core decompression in Ahlbäck's disease. Follow-up and therapy control using MR tomography].

Clinically suspected spontaneous osteonecrosis of the knee (Ahlbäck's disease) was confirmed by MR imaging and subsequent histology in 4 male patients with sudden onset of severe knee pain. The first typical radiological sign for osteonecrosis--flattening of the affected femoral condyle--was seen in no case. All patients were treated surgically by extraarticular drilling for core decompression and were delivered from the complained severe knee pain immediately after surgery. The healing process of early osteonecrosis could be confirmed by the normalisation of bone marrow signal in MR imaging (3 to 15 months follow-up). Core decompression seems to be an effective treatment in early osteonecrosis of femoral condyles. MR imaging is the most sensitive method for early diagnosis of osteonecrosis and for preoperative planning as well as a helpful tool for a non-invasive postoperative follow-up.

Follow-Up Studies↗

PubMed1993

Effect of upper tibial osteotomy on fibula movement and ankle joint motion.

Several techniques of upper tibial osteotomy in the treatment of unicompartmental osteoarthritis of the knee have been described. Osteotomy of the fibula is normally also carried out, or alternatively, dissection of the capsule of the proximal tibiofibular joint. There is concern, however, that this latter procedure may have an adverse effect on the mobility of the ankle joint and on fibula rotation. To investigate these suspected interactions we performed experimental studies in 14 cadaver legs. The vertical, lateral and rotational movements of the fibula were measured with the ankle in neutral (0 degrees) and maximal ankle dorsiflexion before and after performing an interligamental upper tibial osteotomy of a standardised valgus wedge. Maximal ankle dorsiflexion before the osteotomy produced external rotation of the fibula in most specimens, whereas after osteotomy this movement caused mainly internal rotation. In the neutral position of the ankle, upper tibial osteotomy lead to external rotation of the fibula. The upward movement of the fibula head after osteotomy was 0.64 cm on average. There was no measurable vertical motion of the fibula during ankle dorsiflexion either before nor after upper tibial osteotomy. Ankle dorsiflexion improved minimally after osteotomy. In conclusion, this study shows that upper tibial osteotomy with dissection of the capsule of the proximal tibiofibular joint has no adverse effect on movement of the fibula or of the ankle joint. In addition, unlike fibular osteotomy, this technique also has the advantage that the risk of common peroneal nerve injury is minimal.

Ankle Joint↗

PubMed1993

Clinical application of a noninvasive multi-electrode array EMG for the recording of single motor unit activity.

Using a recently developed noninvasive EMG recording technique with multi-electrode arrays we investigated the pattern and distribution of motor unit action potentials (MUAP) following maximal voluntary contraction of the musculus abductor pollicis brevis. An additional parameter, i.e. muscular conduction velocity (CV) in single motor units, was calculated from the multi-electrode array EMG recordings. From 63 healthy children of various age the normal EMG pattern and CV were derived and compared to the EMG of diagnosed patients known to suffer from Duchenne muscular dystrophy and from spinal muscular atrophy. In normal individuals the muscular CV in neonates was lowest at 1-2 m/s and gradually reached a plateau of 2.9-4 m/s from the age of 4 years onwards. The EMG in 31 children with Duchenne muscular dystrophy showed an abnormal pattern with low amplitude action potentials. In 30 out of 31 patients a significantly lower muscular CV was found. In 10 children with spinal muscular atrophy the EMG showed action potentials of abnormally large amplitude and a reduced recruitment of firing motor units. The muscular CV remained within the normal range. Compared to classical needle EMG the application of this new noninvasive EMG technique in children is painless and offers an easy-to-handle diagnostic tool to differentiate between neuromuscular diseases of denervating or of myopathic origin.

Adolescent↗

PubMed1991

[The selection of spongiosa donors for a bone bank].

A prospective trial was carried out in 156 unselected patients (41 men, mean age 67.5 years, 115 women, mean age 71.4 years) who had undergone total hip joint replacement because of degenerative or inflammatory arthritis or fracture of the neck of the femur. The excised femoral heads were subjected to three-stage bone bank screening so as to ascertain how many of them would pass the clinical, biochemical and microbiological exclusion criteria. Only 26 out of 156 femoral heads (17%) proved to be acceptable for the bone bank. Ninety patients (58%) were excluded on clinical grounds such as old age (over 80 years), malignant neoplasms, rheumatoid arthritis, previous intraarticular injections or long-term steroid medication. Positive hepatitis serology excluded 19%, and raised preoperative neopterin concentration excluded 25%, though three months postoperatively this was confirmed in only 2%. Routine neopterin assay seems to be a useful step towards improved bone bank screening, since neopterin concentration is clearly increased in recent virus infections such as HIV. Bacterial contamination was of no practical importance. Because of the low proportion of femoral heads passed as suitable for the bone bank, the existing exclusion criteria will have to be critically scrutinized, and alternative procedures for harvesting bone safe for transplantation (freeze drying, autoclaving, irradiation) will have to be employed.

Aged↗

PubMed1991

[The percutaneous removal of osteoid osteomas via CT-guided drilling].

Osteoid osteomas were removed by CT-guided core drill excision of the nidus in 4 patients. All osteoid osteomas were located in the lower extremity and included cortical lesions in the femur (n = 2), and the tibia (n = 1) and one spongious lesion in the navicular bone of the foot. Nidus diameter ranged from 2 to 3 mm. The patients were discharged after the procedure same day or next day depending on the kind of anaesthesia performed. Follow-up periods ranged from 6 to 56 months and revealed no signs of recidivation. CT-guided core-drill excision of the nidus seems to be a very promising alternative to surgical procedures because of its high cost-effectiveness and minimal invasiveness.

Adolescent↗

PubMed1990

Influence of bone and soft-tissue operations on serum concentrations of growth hormone, somatomedin C and alkaline phosphatase.

After animal experiments suggested there was an interaction between growth hormone and bone healing, our aim in this paper was to ascertain whether there were any changes or possible interaction between the serum level of growth hormone, somatomedin C and alkaline phosphatase while a fractured bone was healing. To this end, the serum concentrations of growth hormone, somatomedin C, alkaline phosphatase and calcium were ascertained both pre- and post-operatively in two groups of patients--one with bone operations, the other with soft-tissue operations--and the results were compared. Comparing the groups, we found that after bone operations there was no increase in the serum level of growth hormone, nor of somatomedin C. An increase would have implied that these two hormones are directly involved in bone regeneration. There was no change in the serum level of alkaline phosphatase or calcium after either bone or soft-tissue operations.

Adolescent↗