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Biomedical subjects

R Hertel

Publications and source records attributed to R Hertel.

At least 19 recordsLinked to original sources
PubMed2001

[Open arthrolysis in preserved joint surface geometry].

This review article discusses the operative treatment options for release of essentially extracartilaginous contractures of the elbow (referred to as extrinsic contractures). Indications, preoperative work-up, specific operative strategy and techniques, rehabilitation, possible complications, and results are discussed and compared. Special reference is made to the technique of sequential surgical release based on the transhumeral approach. This technique makes it possible to optimize the articular offset while preserving the static and dynamic stabilizers of the joint. Treatment of contractures of the elbow remains dangerous and delicate. It deserves experienced surgical handling in order to avoid complications. Thus, it remains to be hoped that qualified management will help to improve the relatively mediocre functional results.

Aftercare↗
PubMed2001

[Glenohumeral joint. Anatomical aspects and implications for prosthesis design].

Knowledge of normal anatomy and kinematics of the glenohumeral joint as well as analysis of the pathoanatomic changes that occur during the course of the disease is the condition for successful patient management. This review article critically discusses the most relevant geometrical variables. Systematically, normal anatomy, pathologic anatomy, and the implications for prosthetic design and implantation are presented. The most important aspects concerning the size and shape of the glenoid, the inclination of the articular surface in the horizontal and frontal planes, as well as the geometry of the scapular neck are discussed. The accumulated knowledge is of immediate practical use and might stimulate researchers and manufacturers to develop more adequate glenoid components.

Biomechanical Phenomena↗
PubMed2001

Cotton-induced pseudotumor of the femur.

Twenty-five years prior to presentation a 41-year-old man had a femoral fracture stabilized with a 4.5 mm AO/ASIF steel plate. The femur healed uneventfully and the patient was asymptomatic for the following 20 years. He then noticed a slow-growing swelling of the left thigh associated with a degree of weakness. Radiographs of the femur 25 years after fracture stabilization showed a massive expansive osteolytic process surrounded by a rim of bone. Magnetic resonance imaging (MRI) confirmed the presence of a large tumor. Since malignancy could not be excluded the patient underwent incisional biopsy. The histologic findings were nonspecific. Because of persistent symptoms the lesion was marginally excised. Intraoperatively a folded cotton sponge was found adjacent to the femur. Histopathologic investigation confirmed a foreign body reaction probably related to the retained cotton sponge. Reactive, foreign-body-induced change may mimic bone and or soft tissue malignancies.

Adult↗
PubMed2001

Auxin-induced elongation of short maize coleoptile segments is supported by 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one.

Endogenous extractable factors associated with auxin action in plant tissues were investigated, especially their effects on elongation of 1-mm coleoptile segments of maize (Zea mays L.), in the presence of saturating 10 microM indole-3-acetic acid (IAA). The relative growth response, to auxin alone, was much smaller in segments shorter than 2-3 mm compared to 10-mm segments. Fusicoccin-induced elongation, however, was less affected by shortening the segments. A reduced auxin response may result from the depletion through cut surfaces of a substance required for IAA-mediated growth. Sucrose, phenolics like flavonoids, and vitamins were ruled out as the causal factors. A partially purified methanol extract of maize coleoptiles supported longterm, auxin-controlled elongation. The active material was also found among substances bleeding from scrubbed maize coleoptiles. The active factor from maize was further purified by HPLC and characterised by the UV spectrum and its pH shift. This factor was identified as 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) by mass spectroscopy. Activity tests confirmed that pure DIMBOA from other sources sustained auxin-induced elongation of short maize coleoptile segments. However, DIMBOA only partially restored the activity lost from short segments. This indicates that an additional factor, other than DIMBOA, is required. Extracts from Avena or Cucurbita did not contain the factor DIMBOA; it was active on maize elongation, but not on Avena coleoptiles or Cucurbita hypocotyls. This narrow specificity and the lack of DIMBOA action in short-term tests with maize indicate that DIMBOA is not the general auxin cofactor but may specifically "spare" the co-auxin in maize.

Benzoxazines↗
PubMed2001

Biomechanical and biological considerations relating to the clinical use of the Point Contact-Fixator--evaluation of the device handling test in the treatment of diaphyseal fractures of the radius and/or ulna.

The Point Contact-Fixator (PC-Fix) was designed as part of the developmental evolution of more biological devices for internal fixations. It is a device characterized by minimal contact to the underlying periosteum and bone, hereby minimizing potential damage to perfusion. A multicentre handling test was conducted in 1993 and 1994 in six hospitals to assess its performance. A total of 83 fractured forearm bones (34 radii and 49 ulnae) in 52 patients were stabilized with a PC-Fix. The mean age of the patients was 37 years. There were 24 AO type A, 24 type B and 5 type C fractures. Nine fractures were open. Mean follow-up was 15.6 months; follow-up was 100%. All 21 surgeons involved considered the use of the PC-Fix self-explanatory and relatively easy. Handling difficulties were mainly related to insertion of the monocortical screws. In particular, the precision required for insertion, the inability to incline the screw and the inability to pull the plate to the bone using the screw were considered hard to deal with. Stripping of the hexagonal slot was a problem at removal of the implant, possibly related to overtightening of the screws at insertion. In 76 of 83 bones (49 of 53 forearms), the fractures united without additional surgery. The healing pattern typically showed early callus formation bridging the fracture, followed by progressive mineralization of the central radiolucent line. Complications included one infection, one late displacement and four delayed unions, all requiring revision surgery. In 8 forearms, plate removal was performed after a mean of 10.3 months. Two refractures occurred after removal of the implant 6 and 7 months postoperatively. In conclusion, the practical handling of the new implant was straightforward and easily learnt. The treatment failures observed were related to technical and strategic errors. We consider that, when using devices with a locking compression principle, a minimum number of three screws should be placed on each side of the fracture, that interfragmentary compression of simple fractures is desirable in order to increase stability and that, contrary to in vivo animal studies, early plate removal is not indicated. The trend in fracture fixation is to improve the biomechanical and biological properties of operating technique and the devices used. The PC-Fix has proven a useful step in the right direction in this evolutionary process.

Adolescent↗
PubMed2000

[The frozen shoulder].

Painful stiffness of the shoulder is an ill-defined clinical entity that is difficult to assess and delicate to treat. The nomenclature used is broad and includes terms such as frozen shoulder, adhesive capsulitis, focal algodystrophy, stiff shoulder, contracted shoulder, and others. Apart from its idiopathic form, the disease can be initiated by trauma, infection, tumour, radiation, systemic and local metabolic disturbances. Pathoanatomically, the common denominator is an inflammatory vascular proliferation followed by thickening, scarring, and retraction of the joint capsule. The inflammatory process often starts at the rotator interval and may extend to the subacromial space. Clinical diagnosis is based on history and physical examination. Generally the onset of pain precedes the perception of a reduced range of motion by weeks or months. In early stages of the disease, the inflammatory type of pain dominates, i.e., the patient's main complaint ist pain at night. In the later stage, range of motion gradually decreases. Patients do not often complain about reduced motion, probably because of its slow onset. Treatment options are a combination of mobilisation exercises with intra-articular steroids, hydraulic distension of the joint capsule, manipulation under anaesthesia, arthroscopic and/or open arthrolysis. The appropriate choice of protocol is just as important as its correct timing. In the inflammatory phase, aggressive treatment protocols are probably contraindicated. Complications of invasive protocols are rare but deleterious and therefore have to be taken into consideration. New anti-anglogenetic agents may enhance functional results and shorten the rehabilitation phase.

Arthroscopy↗
PubMed2000

[Shoulder injury in general practice].

Injuries to the shoulder and shoulder-girdle represent a demanding diagnostic and therapeutic challenge. The complex and minimally constrained anatomic construction of the joints is critical. Although a large majority of the injuries are relatively trivial it is essential to recognize critical lesions that deserve intensive investigation and appropriate treatment. In view of the severity of the consequences of particular injury patterns this article focuses on fractures of the proximal humerus, gleno-humeral dislocations and on acute ruptures of the rotator cuff. In particular, attention will be drawn on fractures with avascular head fragment, primarily undisplaced fractures of the anatomic neck, unrecognized posterior dislocation and on under diagnosed acute ruptures of the rotator cuff. The key issue for a secure diagnosis are a precise physical examination and an adequate conventional radiologic investigation. Both aspects are discussed with practically relevant suggestions.

Arthroscopy↗
PubMed2000

Free nerve endings in the ligamentum capitis femoris.

We report the presence of free nerve endings (FNE) in the ligamentum capitis femoris (LCF). Qualitative and quantitative measurements on the incidence of FNE, as assessed by immuno-histochemistry for the S-100 protein, were obtained from 18 patients undergoing hip surgery. We found FNE in all LCF, with no association to age. The presence of FNE in the LCF suggests a role in noci-/proprioception of the hip.

Adolescent↗
PubMed2000

The evolution of indirect reduction techniques for the treatment of fractures.

During the last decade, classic AO/ASIF techniques for internal fixation shifted from direct reduction and rigid fixation to biologic internal fixation using indirect reduction techniques. Biologic internal fixation is characterized by the preservation of bone and soft tissue vascularity and relative rather than absolute mechanical stability. Reduction is achieved by using soft tissue traction while obtaining axial and rotational alignment and the correct length. Stabilization is performed when possible by compression plating for load sharing or by bridge plating in comminuted fractures. Advancements of these techniques and the development of newer implants that minimize vascular damage have contributed to the development of biologic internal fixation. By using indirect reduction, by using longer plates to improve the mechanical leverage, and by applying fewer screws to avoid unnecessary damage to the bone, fracture union rates were high. There also was a decreased need for supplemental bone grafting. All of these factors provided stable fixation and allowed early motion.

Bone Transplantation↗
PubMed2000

Unexpected resection of soft-tissue sarcoma. More mutilating surgery, higher local recurrence rates, and obscure prognosis as consequences of improper surgery.

Sixteen referred patients were reviewed after excision of an unexpected soft-tissue sarcoma of the extremities. Eight tumors were located in the muscle deep to the fascia, and 8 lesions exceeded the size of 5 cm. The lack of awareness by the primary physician towards the possibility of a malignant lesion was striking, although 11 of 16 tumors presented as a newly formed mass. No imaging studies were done in 11 patients. Fine needle biopsy was unsuccessfully performed in 3 patients. Eleven lesions (63%) were high-grade. Resection margins were intralesional in 12 (75%) and marginal in 4 (25%) patients. Surgical oncologic rules were disregarded in 7 cases, including opening of probably uninvolved joints. Postoperative magnetic resonance imaging (MRI) scans showed a poor negative predictive value for residual tumor. Repeated resection, including three amputations, revealed residual tumor in 10 patients (63%). Four patients received adjuvant local radiation, with additional chemotherapy in 2 of them. At an average follow-up of 4.5 years (range 15-149 months), 4 patients (25%) had developed distant metastases with a local recurrence in 3 (19%). There was one tumor-related death (6%). Physicians' alertness towards the possible malignancy of an enlarging mass cannot be overemphasized. Evaluation by adequate imaging techniques, biopsy, and definitive resection and reconstruction should be performed by an oncologically trained orthopaedic surgeon. Inadequate primary excision leads to a high local recurrence rate and more mutilating surgery and obscures the long-term prognosis.

Adolescent↗
PubMed2000

[In Process Citation]

Painful stiffness of the shoulder is an ill-defined||| clinical entity that is difficult to assess and delicate to treat. The||| nomenclature used is broad and includes terms such as frozen shoulder, adhesive||| capsulitis, focal algodystrophy, stiff shoulder, contracted shoulder, and||| others. Apart from its idiopathic form, the disease can be initiated by trauma,||| infection, tumour, radiation, systemic and local metabolic disturbances.||| Pathoanatomically, the common denominator is an inflammatory vascular||| proliferation followed by thickening, scarring, and retraction of the joint||| capsule. The inflammatory process often starts at the rotator interval and may||| extend to the subacromial space. Clinical diagnosis is based on history and||| physical examination. Generally the onset of pain precedes the perception of a||| reduced range of motion by weeks or months. In early stages of the disease, the||| inflammatory type of pain dominates, i.e., the patient's main complaint ist||| pain at night. In the later stage, range of motion gradually decreases.||| Patients do not often complain about reduced motion, probably because of its||| slow onset. Treatment options are a combination of mobilisation exercises with||| intra-articular steroids, hydraulic distension of the joint capsule,||| manipulation under anaesthesia, arthroscopic and/or open arthrolysis. The||| appropriate choice of protocol is just as important as its correct timing. In||| the inflammatory phase, aggressive treatment protocols are probably||| contraindicated. Complications of invasive protocols are rare but deleterious||| and therefore have to be taken into consideration. New anti-anglogenetic agents||| may enhance functional results and shorten the rehabilitation||| phase.

Journal Article↗
PubMed1999

Glial cell line-derived neurotrophic factor rescues target-deprived sympathetic spinal cord neurons but requires transforming growth factor-beta as cofactor in vivo.

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor for several populations of CNS and peripheral neurons. Synthesis and storage of GDNF by the neuron-like adrenal medullary cells suggest roles in adrenal functions and/or in the maintenance of spinal cord neurons that innervate the adrenal medulla. We show that unilateral adrenomedullectomy causes degeneration of all sympathetic preganglionic neurons within the intermediolateral column (IML) of spinal cord segments T7-T10 that project to the adrenal medulla. In situ hybridization revealed that IML neurons express the glycosylphosphatidylinositol-linked alpha receptor 1 and c-Ret receptors, which are essential for GDNF signaling. IML neurons also display immunoreactivity for transforming growth factor-beta (TGF-beta) receptor II. Administration of GDNF (recombinant human, 1 microg) in Gelfoam implanted into the medullectomized adrenal gland rescued all Fluoro-Gold-labeled preganglionic neurons projecting to the adrenal medulla after four weeks. Cytochrome c applied as a control protein was not effective. The protective effect of GDNF was prevented by co-administration to the Gelfoam of neutralizing antibodies recognizing all three TGF-beta isoforms but not GDNF. This suggests that the presence of endogenous TGF-beta was essential for permitting a neurotrophic effect of GDNF. Our data indicate that GDNF has a capacity to protect a population of autonomic spinal cord neurons from target-deprived cell death. Furthermore, our results demonstrate for the first time that the previously reported requirement of TGF-beta for permitting trophic actions of GDNF in vitro (Kreiglstein et al., 1998) also applies to the in vivo situation.

Adrenal Glands↗
PubMed1999

The medial malleolar network: a constant vascular base of the distally based saphenous neurocutaneous island flap.

Based on 30 fresh cadaver dissections a detailed anatomic study of the medial malleolar network is presented with particular attention to the anastomoses between the latter and the vascular axis that follows the saphenous nerve. The medial malleolar network is formed by the anterior medial malleolar artery, branches from the medial tarsal arteries, the posterior medial malleolar artery and branches from the medial plantar artery. A distinct anterior medial malleolar artery and posterior medial malleolar artery could be identified in 80 and 20%, respectively, as well as constant additional small branches arising from the anterior tibial or posterior tibial artery. A constant anastomosis was found between the arcade formed by the medial tarsal arteries and the medial plantar a. in 60%, and the medial branch of the medial plantar artery in 40%, respectively. This anastomosis always gave rise to branches to the medial malleolar network. In the perimalleolar area and with regard to the great saphenous v. a larger anterior and a smaller posterior branch of the saphenous nerve was found in 100 and 90%, respectively. In all dissections, for both branches of the saphenous nerve two to four small, but distinct anastomoses between the medial malleolar network and the perineural vascular axis were identified. These constant anastomoses represent a new and reliable vascular base for the distally-based saphenous neurocutaneous island flap. Thus, the pivotal point of the flap can be chosen in the area of the medial malleolus without respecting the most distal septocutaneous anastomosis between the perineural vascular axis and the posterior tibial artery. Additionally, an illustrative clinical case is presented.

Adult↗
PubMed1999

On the timing of soft-tissue reconstruction for open fractures of the lower leg.

The timing of soft-tissue reconstruction for severe open fractures of the lower leg is considered crucial to the later outcome, and yet pertinent publications are few. The purpose of this study was to add some based on evidence arguments for the choice of the most adequate timing in the management of these injuries. Twenty-nine consecutive open fractures of the tibia, including 24 grade 3B and 5 grade 3C fractures, were treated using a protocol of immediate debridement, early definitive skeletal stabilisation and early soft-tissue reconstruction. Fifteen lower legs were reconstructed after a mean delay of 4.4 days (range 1-9 days), while 14 lower legs were reconstructed immediately, i.e. as an emergency procedure on the day of admission. Both groups were comparable for sex, age, type of trauma, associated general injuries, type of fracture, associated arterial lesion, associated tendon rupture, type of soft-tissue reconstruction and duration of follow-up. All patients were reviewed at a mean follow-up of 47 months (range 15-89 months). In the delayed reconstruction group the time to full, unprotected weight-bearing (P = 0.0021), the time to definitive union (P = 0.0049), the number of reoperations (P = 0.0001) and the infection rate (P = 0.0374) were significantly higher. The data suggest that immediate reconstruction is, the general condition of the patient permitting, the timing of choice for soft-tissue coverage.

Adolescent↗
PubMed1998

TrkB and neurotrophin-4 are important for development and maintenance of sympathetic preganglionic neurons innervating the adrenal medulla.

The adrenal medulla receives its major presynaptic input from sympathetic preganglionic neurons that are located in the intermediolateral (IML) column of the thoracic spinal cord. The neurotrophic factor concept would predict that these IML neurons receive trophic support from chromaffin cells in the adrenal medulla. We show here that adrenal chromaffin cells in the adult rat store neurotrophin (NT)-4, but do not synthesize or store detectable levels of BDNF or NT-3, respectively. Preganglionic neurons to the adrenal medulla identified by retrograde tracing with fast blue or Fluoro-Gold (FG) express TrkB mRNA. After unilateral destruction of the adrenal medulla, 24% of IML neurons, i.e., all neurons that are preganglionic to the adrenal medulla in spinal cord segments T7-T10, disappear. Administration of NT-4 in gelfoams (6 microgram) implanted into the medullectomized adrenal gland rescued all preganglionic neurons as evidenced by their presence after 4 weeks. NT-3 and cytochrome C were not effective. The action of NT-4 is accompanied by massive sprouting of axons in the vicinity of the NT-4 source as monitored by staining for acetylcholinesterase and synaptophysin immunoreactivity, suggesting that NT-4 may enlarge the terminal field of preganglionic nerves and enhance their access to trophic factors. Analysis of TrkB-deficient mice revealed degenerative changes in axon terminals on chromaffin cells. Furthermore, numbers of FG-labeled IML neurons in spinal cord segments T7-T10 of NT-4-deficient adult mice were significantly reduced. These data are consistent with the notion that NT-4 from chromaffin cells operates through TrkB receptors to regulate development and maintenance of the preganglionic innervation of the adrenal medulla.

Adrenal Medulla↗
PubMed1998

[Complex trauma of the shoulder girdle].

Complex injuries of the shoulder require differentiated management. Interestingly there is a relative lag of warranted information on this subject. Generally the different lesions are discussed separately. However it is not acceptable to simply add the standard diagnostic and therapeutic measures, because major tactic, strategic and rehabilitation incompatibilities could occur. Diagnostic and therapeutic difficulties are frequent for the following injuries: complex proximal humerus dislocation fractures, dislocation fractures with associated lesions of the rotator cuff, posterior dislocation fractures, peri- and intraarticular segmental fractures and fractures or dislocations associated with major neurovascular lesions. Increased awareness of the most relevant diagnostic and therapeutic aspects should contribute to optimize treatment protocols.

Fracture Fixation, Internal↗
PubMed1998

[Missed compartment syndrome after anterior cruciate ligament-plasty following continuous peridural anesthesia].

In this article we report a case of an early postoperative compartment syndrome of the anterior tibial compartment with complete sensomotoric palsy of the peroneal nerve after arthroscopic-assisted replacement of the anterior cruciate ligament (ACL) of the knee. The tourniquet pressure was 360 mm Hg and operation time was 1.75 h. After the operation the leg was bandaged to avoid swelling of the leg and as antithrombotic prophylaxis. Analgesic therapy was by continuous epidural bupivacaine infusion. Increasing pain of the lower leg was suppressed by additional analgesia. Due to persistent pain despite regular analgesia, the patient was sent to a main hospital on the 3rd postoperative day, where an extremely painful and swollen anterior tibial compartment with intracompartmental pressure of over 100 mm Hg was found. The compartment was released immediately. Despite the appearance of severe muscle damage, no extensive débridement was done. At the second examination, at 48 h, there was minimal perfusion of the muscles without contraction and islands of ischemic necrosis. Clinically, there was complete palsy of the dorsiflexors of the foot. The case shows the danger of a compartment syndrome when tourniquet of the limb, arthroscopy and a firm bandage are combined. Continuous epidural analgesia masks the classic symptoms of compartment syndrome.

Adult↗