Ruediger von Eisenhart-Rothe

Relevance of arm position and muscle activity on three-dimensional glenohumeral translation in patients with traumatic and atraumatic shoulder instability.

Background No quantitative data on glenohumeral translation exist allowing one to distinguish insufficiency of the active or passive stabilizers in different forms of shoulder instability. Hypothesis To determine whether 1) in traumatic or atraumatic shoulder instability an increase of glenohumeral translation can be observed in specific relevant arm positions, 2) muscle activity leads to recentering of the humeral head, and 3) there exist differences between traumatic and atraumatic instability. Study Design Prospective clinical trial. Methods In 12 patients with traumatic and 10 patients with atraumatic instability, both shoulders were examined in different arm positions—with and without muscle activity—by using open magnetic resonance imaging and a three-dimensional postprocessing technique. Results At 90° of abduction and external rotation, translation (anterior-inferior) was significantly higher in patients with traumatic unstable shoulders compared with their contralateral side (3.6 ± 1.5 versus 0.7 ± 1.6 mm). In patients with atraumatic instability, significantly increased translation (4.7 ± 2.0 mm) was observed, with the direction being nonuniform. Muscle activity led to significant recentering in traumatic but not in atraumatic instability. Conclusions In traumatic instability, increased translation was observed only in functionally important arm positions, whereas intact active stabilizers demonstrate sufficient recentering. In atraumatic instability, a decentralized head position was recorded also during muscle activity, suggesting alterations of the active stabilizers. Clinical Relevance Clinical Relevance: These data are relevant for optimizing diagnostics and therapeutic strategies.

Influence of adducting and abducting muscle forces on the subacromial space width.

PURPOSE Strengthening of the shoulder depressors is an important component in the treatment of impingement syndrome. However, the quantitative effect of various muscle forces on the width of the subacromial space has never been demonstrated in vivo. Therefore, the purpose of this study was to analyze the influence of adducting and abducting muscle forces on the subacromial space width in healthy volunteers in various arm positions. METHODS The shoulders of 12 healthy volunteers were imaged with an open MR system at 30 degrees, 60 degrees, 90 degrees, 120 degrees, and 150 degrees of arm elevation under both isometric adducting and abducting muscle activity (15 N). After segmentation and three-dimensional reconstruction of anatomically relevant structures, the minimal spatial acromiohumeral and claviculohumeral distances were quantified. RESULTS Adducting muscle forces led to a significant increase of the acromiohumeral distance in all arm positions (P < 0.01), varying from 32% (30 degrees ) to 138% (90 degrees ) relative to abducting muscle forces. The claviculohumeral distance showed an increase of 9% (30 degrees ) to 24% (90 degrees ), this increase being also statistically significant at all positions (P < 0.05). During elevation of the arm (30-120 degrees ), the absolute subacromial space width was reduced significantly (P = 0.001) by 30% under isometric contraction of the adductors compared with 53% (P = 0.001) under activation of the abductors. CONCLUSION This in vivo study shows for the first time that adducting muscle forces lead to a significant increase of the subacromial space width compared with abducting muscle activity. In the future, this technique and data can be used to objectively quantify the effect of physical therapy protocols focused on increasing the depressor effect of adducting muscles in the postoperative and conservative treatment of impingement syndrome of the shoulder.

Functional malcentering of the humeral head and asymmetric long-term stress on the glenoid : potential reasons for glenoid loosening in total shoulder arthroplasty

We tested the hypothesis that functional malcentering of the humeral head during arm elevation exists in patients with glenohumeral osteoarthritis and influences long-term glenoid loading. Twenty-eight healthy volunteers and 10 patients with primary osteoarthritis, 10 with cuff-arthropathy, and 1 with dysplastic glenoid were examined. Open magnetic resonance imaging and 3-dimensional (3D) digital postprocessing techniques were applied in various arm positions. Osteoabsorptiometry was used to determine 3D subchondral mineralization patterns of the glenoid as an indicator of integral long-term stress distribution. At 30 degrees of abduction, 5 patients demonstrated malcentering of the humeral head posteriorly; all patients with cuff arthropathy had malcentering superiorly. At 90 degrees, most patients displayed significant (P < .001) malcentering in the superior and posterior direction. The shoulders showed maximal subchondral mineralization patterns in the direction of malcentering. Most patients with glenohumeral osteoarthritis displayed functional malcentering, which might be responsible for postoperative glenoid loosening in shoulder arthroplasty if not corrected intraoperatively.

Percutaneous core needle biopsy versus open biopsy in diagnostics of bone and soft tissue sarcoma: a retrospective study

BackgroundBiopsy is a crucial step within the diagnostic cascade in patients with suspected bone or soft tissue sarcoma. Open biopsy is still considered the gold standard. However, recent literature suggests similar results for percutaneous biopsy techniques. Therefore, the aim of this retrospective analysis was to compare open and percutaneous core needle biopsy (CNB) regarding their accuracy in diagnosis of malignant musculoskeletal lesions.MethodsFrom January 2007 to December 2009, all patients with suspected malignant primary bone or soft tissue tumour undergoing a percutaneous CNB or open biopsy and a subsequent tumour resection at our department were identified and enrolled. Sensitivities, specificities, positive predictive values (PPV), negative predictive values (NPV) and diagnostic accuracy were calculated for both biopsy techniques and compared using Fisher’s exact test.ResultsA total of 77 patients were identified and enrolled in this study. Sensitivity, specificity, PPV, NPV and diagnostic accuracy were 100% for CNB in bone tumours. Sensitivity (95.5%), NPV (91.7%) and diagnostic accuracy (93.3%) for open biopsy in bone tumours showed slightly inferior results without statistical significance (p > 0.05). In soft tissue tumours favourable results were obtained in open biopsies compared to CNB with differences regarding sensitivity (100% vs. 81.8%, p = 0.5), NPV (100% vs. 50%, p = 0.09) and diagnostic accuracy (100% vs. 84.6%, p = 0,19) without statistical significance. The overall diagnostic accuracy was 92.9% for CNB and 98.0% for open biopsy (p = 0.55). A specific diagnosis could be obtained in 84.2% and 93.9%, respectively (p = 0.34).ConclusionIn our study we found moderately inferior results for the percutaneous biopsy technique compared to open biopsy in soft tissue tumours whereas almost equal results were obtained for both biopsy techniques for bone tumours. Thus, CNB is a safe, minimal invasive and cost-effective technique for diagnosing bony lesions. In soft tissue masses, the indication for percutaneous core needle biopsy needs to be made carefully by an experienced orthopaedic oncologist with respect to the suspected entity, size of necrosis and location of the lesion to avoid incorrect or deficient results.

Can Bone Tissue Engineering Contribute to Therapy Concepts after Resection of Musculoskeletal Sarcoma

Resection of musculoskeletal sarcoma can result in large bone defects where regeneration is needed in a quantity far beyond the normal potential of self-healing. In many cases, these defects exhibit a limited intrinsic regenerative potential due to an adjuvant therapeutic regimen, seroma, or infection. Therefore, reconstruction of these defects is still one of the most demanding procedures in orthopaedic surgery. The constraints of common treatment strategies have triggered a need for new therapeutic concepts to design and engineer unparalleled structural and functioning bone grafts. To satisfy the need for long-term repair and good clinical outcome, a paradigm shift is needed from methods to replace tissues with inert medical devices to more biological approaches that focus on the repair and reconstruction of tissue structure and function. It is within this context that the field of bone tissue engineering can offer solutions to be implemented into surgical therapy concepts after resection of bone and soft tissue sarcoma. In this paper we will discuss the implementation of tissue engineering concepts into the clinical field of orthopaedic oncology.

Tibiofemoral and patellofemoral joint 3D-kinematics in patients with posterior cruciate ligament deficiency compared to healthy volunteers

BackgroundThe posterior cruciate ligament (PCL) plays an important role in maintaining physiological kinematics and function of the knee joint. To date mainly in-vitro models or combined magnetic resonance and fluoroscopic systems have been used for quantifying the importance of the PCL. We hypothesized, that both tibiofemoral and patellofemoral kinematic patterns are changed in PCL-deficient knees, which is increased by isometric muscle flexion. Therefore the aim of this study was to simultaneously investigate tibiofemoral and patellofemoral 3D kinematics in patients suffering from PCL deficiency during different knee flexion angles and under neuromuscular activation.MethodsWe enrolled 12 patients with isolated PCL-insufficiency as well as 20 healthy volunteers. Sagittal MR-images of the knee joint were acquired in different positions of the knee joint (0°, 30°, 90° flexion, with and without flexing isometric muscle activity) on a 0.2 Tesla open MR-scanner. After segmentation of the patella, femur and tibia local coordinate systems were established to define the spatial position of these structures in relation to each other.ResultsAt full extension and 30° flexion no significant difference was observed in PCL-deficient knee joints neither for tibiofemoral nor for patellofemoral kinematics. At 90° flexion the femur of PCL-deficient patients was positioned significantly more anteriorly in relation to the tibia and both, the patellar tilt and the patellar shift to the lateral side, significantly increased compared to healthy knee joints. While no significant effect of isometric flexing muscle activity was observed in healthy individuals, in PCL-deficient knee joints an increased paradoxical anterior translation of the femur was observed at 90° flexion compared to the status of muscle relaxation.ConclusionsSignificant changes in tibiofemoral and patellofemoral joint kinematics occur in patients with isolated PCL-insufficiency above 30 degrees of flexion compared to healthy volunteers. Since this could be one reasonable mechanism in the development of osteoarthritis (OA) our results might help to understand the long-term development of tibiofemoral and/or patellofemoral OA in PCL-insufficient knee joints.

View-Angle Tilting and Slice-Encoding Metal Artifact Correction for Artifact Reduction in MRI: Experimental Sequence Optimization for Orthopaedic Tumor Endoprostheses and Clinical Application.

Background MRI plays a major role in follow-up of patients with malignant bone tumors. However, after limb salvage surgery, orthopaedic tumor endoprostheses might cause significant metal-induced susceptibility artifacts. Purposes To evaluate the benefit of view-angle tilting (VAT) and slice-encoding metal artifact correction (SEMAC) for MRI of large-sized orthopaedic tumor endoprostheses in an experimental model and to demonstrate clinical benefits for assessment of periprosthetic soft tissue abnormalities. Methods In an experimental setting, tumor endoprostheses (n=4) were scanned at 1.5T with three versions of optimized high-bandwidth turbo-spin-echo pulse sequences: (i) standard, (ii) VAT and (iii) combined VAT and SEMAC (VAT&SEMAC). Pulse sequences included coronal short-tau-inversion-recovery (STIR), coronal T1-weighted (w), transverse T1-w and T2-w TSE sequences. For clinical evaluation, VAT&SEMAC was compared to conventional metal artifact-reducing MR sequences (conventional MR) in n=25 patients with metal implants and clinical suspicion of tumor recurrence or infection. Diameters of artifacts were measured quantitatively. Qualitative parameters were assessed on a five-point scale (1=best, 5=worst): “image distortion”, “artificial signal changes at the edges” and “diagnostic confidence”. Imaging findings were correlated with pathology. T-tests and Wilcoxon-signed rank tests were used for statistical analyses. Results The true size of the prostheses was overestimated on MRI (P<0.05). A significant reduction of artifacts was achieved by VAT (P<0.001) and VAT&SEMAC (P=0.003) compared to the standard group. Quantitative scores improved in the VAT and VAT&SEMAC group (P<0.05). On clinical MR images, artifact diameters were significantly reduced in the VAT&SEMAC-group as compared with the conventional-group (P<0.001). Distortion and artificial signal changes were reduced and diagnostic confidence improved (P<0.05). In two cases, tumor-recurrence, in ten cases infection and in thirteen cases other pathologies were diagnosed. Conclusions Significant reduction of metallic artifacts was achieved by VAT and SEMAC. Clinical results suggest, that these new techniques will be beneficial for detecting periprosthetic pathologies during postoperative follow-up.

Local Staging of Soft-Tissue Sarcoma: Emphasis on Assessment of Neurovascular Encasement-Value of MR Imaging in 174 Confirmed Cases.

PURPOSE To evaluate utility of magnetic resonance (MR) imaging in local staging of soft-tissue sarcoma, with an emphasis on assessment of neurovascular encasement. MATERIALS AND METHODS Institutional review board approval was obtained; informed consent requirement was waived. Preoperative MR images in 174 patients with soft-tissue sarcoma were analyzed by two readers. Tumor staging according to the American Joint Committee on Cancer/Union International Contre le Cancer and Enneking staging systems and analysis of osseous and articular invasion were performed. To assess neurovascular encasement, contact between tumor and arteries, between tumor and veins, and between tumor and nerves was classified (no contact, contact ≤90°, 91°-180°, 181°-270°, >271°). Interobserver agreement was determined; imaging findings were correlated with intraoperative findings and/or histopathologic findings (Pearson correlation coefficient [r] and Cohen κ coefficient). RESULTS Intraoperative evaluation and/or histopathologic evaluation confirmed osseous, articular, and neurovascular invasion in 8.6%, 2.9%, and 25.3% of patients. Interobserver agreement was excellent for tumor staging (American Joint Committee on Cancer/Union International Contre le Cancer staging, κ = 0.811; Enneking staging, κ = 0.943) and osseous invasion (κ = 1.000). It was substantial for articular invasion (κ = 0.794). Sensitivity and specificity for osseous invasion were 100% and 98.7%, respectively (both readers). For articular invasion, sensitivity was 80% (both readers); specificities were 100% and 98.8% for readers 1 and 2, respectively. Interobserver agreement in quantifying contact between tumor and vessels and between tumor and nerves was excellent for arteries, veins, and nerves (κ = 0.845, 0.892, 0.893, respectively). Receiver operating characteristic analysis revealed optimal threshold of greater than 180° for prediction of arterial and venous encasement (both readers). For neural encasement, optimal threshold was greater than 180° (reader 1) and greater than 270° (reader 2). Sensitivities in diagnosing encasement for arteries, veins, and nerves were 84.6%, 84.6%, and 77.8% (reader 1) and 84.6%, 84.6%, and 72.2% (reader 2). Specificities for encasement of arteries, veins, and nerves, respectively, were 97.5%, 97.5%, and 93.2% (reader 1) and 93.8%, 94.7%, 97.3% (reader 2). CONCLUSION MR imaging allows reliable and accurate local staging of soft-tissue sarcoma. Encasement of arteries, veins, and nerves should be diagnosed, if the contact between tumor and vascular or neural circumference exceeds 180°.

Biomarkers for tissue engineering of the tendon-bone interface

The tendon-bone interface (enthesis) is a highly sophisticated biomaterial junction that allows stress transfer between mechanically dissimilar materials. The enthesis encounters very high mechanical demands and the regenerative capacity is very low resulting in high rupture recurrence rates after surgery. Tissue engineering offers the potential to recover the functional integrity of entheses. However, recent enthesis tissue engineering approaches have been limited by the lack of knowledge about the cells present at this interface. Here we investigated the cellular differentiation of enthesis cells and compared the cellular pattern of enthesis cells to tendon and cartilage cells in a next generation sequencing transcriptome study. We integrated the transcriptome data with proteome data of a previous study to identify biomarkers of enthesis cell differentiation. Transcriptomics detected 34468 transcripts in total in enthesis, tendon, and cartilage. Transcriptome comparisons revealed 3980 differentially regulated candidates for enthesis and tendon, 395 for enthesis and cartilage, and 946 for cartilage and tendon. An asymmetric distribution of enriched genes was observed in enthesis and cartilage transcriptome comparison suggesting that enthesis cells are more chondrocyte-like than tenocyte-like. Integrative analysis of transcriptome and proteome data identified ten enthesis biomarkers and six tendon biomarkers. The observed gene expression characteristics and differentiation markers shed light into the nature of the cells present at the enthesis. The presented markers will foster enthesis tissue engineering approaches by setting a bench-mark for differentiation of seeded cells towards a physiologically relevant phenotype.

Evaluation of calcium dihydroxide- and silver-coated implants in the rat tibia.

Background Silver ions (Ag+) have strong antibacterial effects, and silver-coated materials are in widespread clinical use. However, the application of silver-coated medical devices is not without concerns: its use with direct bone contact is not established, and systemic toxic side effects of released Ag+ have been described. Therefore, alternative bactericidal coatings with a more localized way of acting – e.g., calcium dihydroxide, Ca(OH)2 (CH) – would be advantageous. Methods A new rat model of the animals tibial metaphysis was developed. In the left proximal tibiae of 36 male Wistar rats, titanium screws were implanted. The screws were coated with hydroxyapatite (HA; 12 animals: group I), low-dosed HA silver (HA-Ag; 12 animals: group II) and CH (12 animals: group III). After 6 weeks, all rats were sacrificed. The implants were evaluated for morphological changes on their surfaces, by light microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy; for osteointegration, by measurement of resistance to removal; and for bacterial colonization, by quantitative culture analysis. Additionally, the tibial bone was investigated histologically for signs of osteomyelitis and sonicated to detect bacterial loads. Results (i) No microbiological or histological signs of infection could be determined on any of the screws or the surrounding bone. (ii) The bone-implant interface analysis revealed extensive bone formation and direct bone-implant contact on all HA, HA-Ag and HA-CH coated screws. (iii) HA and HA-Ag were partially, and CH was fully, degraded on the screw coating, allowing host bone to osteointegrate.