Rüdiger von Eisenhart-Rothe

Direct comparison of contact areas, contact stress and subchondral mineralization in human hip joint specimens.

Abstract X-ray densitometric and CT osteoabsorptiometric findings suggest that in the human hip subchondral mineralization patterns change from bicentric to monocentric as a function of age. It has been hypothesized that these changes indicate an alteration in the geometric configuration of the joint from incongruous to congruous, possibly associated with the onset of osteoarthrosis. The purpose of this study was therefore to directly compare contact areas, contact stress and subchondral mineralization in the hip joint. Twelve specimens without cartilage lesions (ages 34–86 years) were investigated. Simulating the mid-stance phase, the contact areas were determined by polyether casting and the contact stress with Fuji film. The distribution of subchondral mineralization was assessed non-invasively with CT osteoabsorptiometry. At small loads the load-bearing areas were located at the periphery of the lunate surface. In some joints they were found in the acetabular roof and expanded, with higher loads, to the center of the lunate surface and the anterior and posterior horns. In other joints, the contact areas were recorded at lower loads in the anterior and posterior horns, and only at higher forces they merged in the acetabular roof. The maximal contact stress ranged from 8 to 9 MPa at 300% body weight. Maxima of subchondral mineralization were recorded in the acetabular roof, in the anterior and posterior horns, or in all three locations. There was no clear correlation between the distribution of contact and pressure, and the pattern of subchondral bone density. Incongruity is shown to strongly affect the distribution of contact and pressure in the human hip joint. However, the pattern of subchondral mineralization cannot be readily explained in terms of the contact areas and contact stress during mid-stance. Incongruity may give rise to tensile stresses in the subchondral bone, and the construction of the pelvis as a whole may play an important role in subchondral bone loads and adaptation.

Quantitative Analysis of Incongruity, Contact Areas and Cartilage Thickness in the Human Hip Joint

Joint incongruity and cartilage thickness have been shown to determine the contact stresses and the load partitioning between the solid and fluid phases of articular cartilage. Matrix stresses, which are relevant in the development of osteoarthrosis, can, however, not be determined experimentally but must be calculated using numerical methods. The aim of the present study was to quantify the incongruity and cartilage thickness of the human hip, in order to allow for the construction of morphologically accurate finite element models. Twelve cadaveric specimens (34-86 years), two fresh and ten fixed, were investigated. The loading configuration was based on in vivo measurements of hip joint forces during midstance. The incongruity and contact areas were determined using a polyether casting technique, in the minimally and the fully loaded state. The cartilage thickness was measured at identical coordinate points with an A-mode ultrasonic system. Generally, the contact started at lower loads at the edge of the lunate surface, and the joint space increased towards its central aspects. In some specimens the contact started in the acetabular roof, leaving a joint space of up to 2 mm in the horns of the lunate surface. In others, the initial contact was observed in the anterior and posterior horns of the lunate surface with a joint space width of up to 0.75 mm in the acetabular roof. The size of the contact areas increased from about 20% of the lunate surface to 98% at higher loads. The articular cartilage thickness ranged from 0.7 to 3.6 mm, the maxima being located in the ventral aspects of the femoral head and acetabulum. These quantitative data on joint space width, contact, and cartilage thickness in the human hip joint may be used to construct and validate finite element models which are required to elucidate the mechanical factors involved in osteoarthrosis.

Simultaneous 3D Assessment of Glenohumeral Shape, Humeral Head Centering, and Scapular Positioning in Atraumatic Shoulder Instability: A Magnetic Resonance–Based In Vivo Analysis

Background Success rates in the treatment of atraumatic shoulder instability differ, and in vivo identification of the individual insufficient stabilizers is difficult. Hypothesis Atraumatic shoulder instability is an inhomogeneous entity with varying alterations of the active and passive stabilizers. This might be a reason for inferior treatment results. Study Design Case control study; Level of evidence, 3. Methods Shoulders of 28 healthy volunteers and both shoulders of 14 patients with atraumatic instability and multidirectional laxity were examined in different arm positions using open magnetic resonance imaging. Three-dimensional postprocessing techniques were applied to determine 3D glenoid size and retroversion, radius of the humeral head, and curvature of the glenoid. The results of static stabilizers were compared with those of glenohumeral and scapular positioning in the same patients for identification of the individual insufficient stabilizers. Results The atraumatic unstable shoulders showed an increased mean retroversion on both sides, the difference being significant on the affected side (9.4° ± 4.8° vs healthy 3.9° ± 1.3°; P < .05) with a range of 2.6° to 16.6°. The curvature analysis demonstrated a pronounced flatness of the glenoid with a significantly increased mean radius (103.8 mm vs healthy 41.7 mm). The extent of these changes varied widely among patients. Comparison of the static stabilizers with glenohumeral and scapular positioning revealed that isolated changes of the active stabilizers exist in some patients, whereas no isolated changes of passive stabilizers were found. Conclusion All active and passive stabilizers need to be analyzed in patients with atraumatic instability because the magnitude of alteration varied widely among individuals. Different combinations of alterations of the stabilizers were found. The presented technique allows for in vivo identification of the specific alterations. This is necessary for a better understanding of individual pathomechanics and for initiating a specific causal treatment.

Quantitative determination of the contact pressure distribution in the hip joint during gait

SummaryThe objective of this investigation was the experimental determination of the contact pressures in the hip joint for characteristic phases of the gait cycle. The joint forces determined in vivo with telemetric endoprosthesis by Bergmann et al. (1993) were converted into a pelvic reference system, based on kinematic gait analysis. In eight cadaveric hip joints (age 18–75 yrs.) the reaction forces were applied corresponding to four phases of the gait cycle (heel strike, mid-stance, heel off, toe off) and the pressure distribution determined with FUJI pressure sensitive film. We found maxima of 10 MPa during mid stance. The areas of highest pressure were located in the ventro-superior aspect of the acetabulum (anterior part of the acetabular roof) and in the dorso-inferior aspect of the lunate surface. The pressure distribution was relatively constant during the four phases and the maxima did not vary proportional to the applied load. The normal pressure distribution in the hip appears to be determined by the physiological incongruity of the articular surfaces and the inhomogeneous bony support of the acetabulum. During operative interventions this normal load transfer should be restored as accurately as possible.ZusammenfassungZiel der Untersuchung war die experimentelle Bestimmung der Druckverteilung im Hüftgelenk für charakteristische Phasen des Ganges. Die von Bergmann et al. (1993) mittels telemetrischer Endoprothesen in vivo bestimmten Gelenkkräfte wurden auf Basis kinematischer Ganganalysen in ein beckenbezogenes Koordinatensystem transformiert. An 8 Hüftgelenkpräparaten (Alter 18–75 Jahre) wurden dann während 4 Gangphasen (Fersenkontakt, 1. Kraftmaximum, Ferse vom Boden, Abrollen der Zehen) die Gelenkkräfte eingeleitet und die Druckverteilung mittels FUJI-Druckmeßfolie bestimmt. Wir fanden Maxima von 10 MPa während der mittleren Standbeinphase, die Zonen höchster Druckbelastung waren im ventrosuperioren Anteil des Azetabulums (vorderes Pfannendach) und dorsoinferior (Hinterhorn der Facies lunata) lokalisiert. Die Druckverteilung war während der 4 Phasen relativ konstant, die Größe der Maxima variierte nicht proportional zu den eingeleiteten Kräften. Die normale Druckverteilung im Hüftgelenk wird offensichtlich von der physiologischen Inkongruenz der Gelenkflächen sowie der inhomogenen knöchernen Unterstützung des Azetabulums bestimmt. Bei operativen Maßnahmen im Bereich des Hüftgelenks sollte diese physiologische Druckübertragung möglichst exakt wiederhergestellt werden.

A popliteal giant synovial osteochondroma mimicking a parosteal osteosarcoma

Both giant synovial osteochondroma and parosteal osteosarcoma are rare musculo-skeletal tumors, often localized in the vicinity of the knee. Misdiagnosis of a malignant bone tumor can entail fatal consequences. Etiology of giant synovial osteochondroma is widely unsolved but is believed to originate from synovial chondromatosis, a mostly benign metaplasia of the synovial membrane. Parosteal osteosarcoma is a low-grade surface osteosarcoma with a propensity of local recurrence and the potential of distant metastasis and therefore requiring a different therapeutical approach. We report the case of a popliteal giant osteochondroma mimicking a parosteal osteosarcoma. Relevant facts of this rare entity regarding pathogenesis, treatment, and differential diagnoses will be discussed.

Epithelioid sarcoma of the plantar fascia mimicking Morbus Ledderhose — A severe pitfall for clinical and histopathological misinterpretation

Plantar fibromatosis, also known as Morbus Ledderhose, is a well known and frequently encountered disorder of the planta pedis. When conservative treatment fails, surgical therapy with complete resection is the therapeutical procedure of choice. Soft tissue sarcoma is a heterogeneous and rare malignant disease of the musculoskeletal system with over 50 histopathological subtypes which can potentially arise in any localization but is most commonly found at the extremities. Here, we report the case of an epithelioid sarcoma of the sole of the foot which was initially and repeatedly clinically and histopathologically misinterpreted as plantar fibromatosis, receiving insufficient resection and subsequently ending in amputation of the lower leg.

Distribution patterns of foot and ankle tumors: a university tumor institute experience

BackgroundBone and soft tissue masses of the foot and ankle are not particularly rare but true neoplasia has to be strictly differentiated from pseudotumorous lesions. Diagnosis is often delayed as diagnostic errors are more common than in other regions. Awareness for this localization of musculoskeletal tumors is not very high and neoplasia is often not considered. The purpose of this study is to provide detailed information on the incidence and distribution patterns of foot and ankle tumors of a university tumor institute and propose a simple definition to facilitate comparison of future investigations.MethodsAs part of a retrospective, single-centre study, the data of patients that were treated for foot and ankle tumors between June 1997 and December 2015 in a musculoskeletal tumor centre were analyzed regarding epidemiologic information, entity and localization. Included were all cases with a true tumor of the foot and ankle. Exclusion criteria were incomplete information on the patient or entity (e.g. histopathological diagnosis) and all pseudotumoral lesions.ResultsOut of 7487 musculoskeletal tumors, 413 cases (5,52%) of tumors of the foot and ankle in 409 patients were included (215 male and 198 female patients). The average age of the affected patients was 36 ± 18y (min.3y, max.92y). Two hundred sixty-six tumors involved the bone (64%), among them 231 (87%) benign and 35 (13%) malignant. There were 147 soft tissue tumors (36%), 104 (71%) were benign, 43 (29%) malignant. The most common benign osseous tumor lesions included simple bone cysts, enchondroma and osteochondroma. By far the most common malignant bone tumor was chondrosarcoma. Common benign soft tissue tumors included pigmented villo-nodular synovitis, superifcial fibromatosis and schwannoma whereas the most common malignant members were synovial sarcoma and myxofibrosarcoma. Regarding anatomical localization, the hindfoot was affected most often.ConclusionsKnowledge of incidence and distribution patterns of foot and ankle tumors will help to correctly assess unclear masses and initiate the right steps in further diagnostics and treatment. Unawareness can lead to delayed diagnosis and inadequate treatment with serious consequences for the affected patient.

Metatarsalgie: Differentialdiagnose und Therapie

ZusammenfassungDer Begriff Metatarsalgie bezeichnet lokalisierte oder generalisierte Schmerzen im Bereich der Metatarsaleköpfchen. Die gezielte Anamnese und klinische Untersuchung vermag meist relativ einfach die Diagnose einer Metatarsalgie zu stellen, die zugrundeliegende Ursache ist aber häufig erst durch entsprechende Erfahrung und weiterführende Bildgebung nach gründlicher Abwägung möglicher Differentialdiagnosen zu identifizieren. Neben konservativen Therapiemöglichkeiten unter Einbeziehung der Orthopädietechnik und Physiotherapie können unterschiedlichste operative Maßnahmen in Abhängigkeit der zu Grunde liegenden Pathologie meist Abhilfe der Beschwerden erreichen. Auch hier gilt, wie für alle Fußpathologien, begleitende Deformitäten im kausalen Zusammenhang mit einer Metatarsalgie zu behandeln, um ein Rezidiv der Beschwerden und eine dauerhafte Ausheilung der Metatarsalgie zu erreichen. Die profunde Kenntnis relevanter Differentialdiagnosen und Begleitpathologien ist hierbei für eine erfolgreiche Behandlung ebenso notwendig wie eine differenzierte und individualisierte Behandlungsstrategie.SummaryMetatarsalgia refers to localized or generalized forefoot pain in the region of the metatarsal heads. Symptoms can be isolated or in combination with accompanying deformities occurring in the forefoot and/or hindfoot. Anamnesis and clinical investigation usually yield to the diagnosis, the underlying cause on the other hand is not always easy to identify. In the foreground of the treatment is the exhaustion of conservative forms of therapy to minimize the symptoms of local pressure increase and callus under the metatarsal heads. In addition, various surgical methods are available, such as corrective osteotomy of the metatarsale bone, soft tissue interventions and the correction of associated deformities. The indications for surgical intervention should be made with caution in order to avoid failures and complaints persisting after surgery. The most common problems are an inadequate indication for surgery, technical problems and insufficient postoperative treatment.

[Metatarsalgia: non-specific pain under the ball of the foot].

Schmerzen unter den Mittelfuskopfchen der Kleinzehenstrahlen sind nicht nur bei alteren, sondern auch bei jungeren Menschen haufig zu beobachten. Als Begleitbefund findet sich bei chronischen Formen oft eine plantare Schwiele, die Ausdruck einer Fehlbelastung ist.Schmerzen unter den Mittelfußköpfchen der Kleinzehenstrahlen sind nicht nur bei älteren, sondern auch bei jüngeren Menschen häufig zu beobachten. Als Begleitbefund findet sich bei chronischen Formen oft eine plantare Schwiele, die Ausdruck einer Fehlbelastung ist.

Hammer — Krallen — Klauen

Kleinzehendeformitäten, v. a. Hammer- und Krallenzehen, finden sich bei hausärztlichen Patienten häufig (Inzidenzen bis zu 20%). Auch ist der Leidensdruck bei den Betroffenen meist erheblich. Deshalb sind Grundkenntnisse in Diagnostik und Therapie für Sie essenziell.Kleinzehendeformitaten, v. a. Hammer- und Krallenzehen, finden sich bei hausarztlichen Patienten haufig (Inzidenzen bis zu 20%). Auch ist der Leidensdruck bei den Betroffenen meist erheblich. Deshalb sind Grundkenntnisse in Diagnostik und Therapie fur Sie essenziell.