Christoph Theis

High-energy extracorporeal shock wave treatment of nonunions

Forty-three consecutive patients who did not have healing of tibial or femoral diaphyseal and metaphyseal fractures and osteotomies for at least 9 months after injury or surgery were examined prospectively for use of high-energy extracorporeal shock waves. Former treatment modalities (cast, external fixator, plate osteosynthesis, limitation of weightbearing) remained unchanged. In all cases a 99mTechnetium dicarboxyphosphonate regional two-phase bone scintigraphy was performed before one treatment with 3000 impulses of an energy flux density of 0.6 mJ/mm2. Radiologic and clinical followups were done at 4-week intervals starting 8 weeks after shock wave treatment. The success criterion was bridging of all four cortices in the anteroposterior and lateral radiographic views, in oblique views, or by conventional tomography. An independent observer described bony consolidation in 31 of 43 cases (72%) after an average of 4 months (range, 2–7 months). Twenty-nine of 35 (82.9%) patients with a positive bone scan had healing of the pseudarthrosis compared with two of eight (25%) patients with a negative bone scan. Six of these eight patients with negative scans were heavy smokers. No complications were observed. High-energy shock wave therapy seemed to be an effective noninvasive tool for stimulation of bone healing in properly selected patients with a diaphyseal or metaphyseal nonunion of the femur or tibia. Additional controlled studies are mandatory.

Repetitive Low-Energy Shock Wave Treatment for Chronic Lateral Epicondylitis in Tennis Players

Background There is conflicting evidence regarding extracorporeal shock wave treatment for chronic tennis elbow. Hypothesis Treatment with repetitive low-energy extracorporeal shock wave treatment is superior to repetitive placebo extracorporeal shock wave treatment. Methods Seventy-eight patients enrolled in a placebo-controlled trial. All patients were tennis players with recalcitrant MRIconfirmed tennis elbow of at least 12 months’ duration. Patients were randomly assigned to receive either active low-energy extracorporeal shock wave treatment given weekly for 3 weeks (treatment group 1) or an identical placebo extracorporeal shock wave treatment (sham group 2). Main outcome measure was pain during resisted wrist extension at 3 months; secondary measures were >50% reduction of pain andthe Upper Extremity Function Scale. Results At 3 months, there was a significantly higher improvement in pain during resisted wrist extension in group 1 than in group 2 (mean [SD] improvement, 3.5 [2.0] and 2.0 [1.9]; P= .001 for between-group difference of improvement) and in the Upper Extremity Function Scale (mean [SD] improvement, 23.4 [14.8] and 10.9 [14.9]; P< .001 for between-group difference of improvement). In the treatment group, 65% of patients achieved at least a 50% reduction of pain, compared with 28% of patients in the sham group (P= .001 for between-group difference). Conclusion Low-energy extracorporeal shock wave treatment as applied is superior to sham treatment for tennis elbow.

Robotic total knee arthroplasty: the accuracy of CT-based component placement.

Background Accurate alignment of the components in total knee arthroplasty is important. By use of postoperative CT controls, we studied the ability of a robotic effector to accurately place and align total knee arthroplasty (TKA) components according to a purely CT-based preoperative plan.Patients and methods Robotic TKA was performed in 13 patients (6 men) with primary gonarthrosis. Locator screws were placed into femur and tibia under spinal anesthesia. A CT-scan including the femoral head, knee and ankle was performed. In the preoperative planning software, virtual components were positioned into the CT volume. In a second operation, the robot milled femur and tibia with a high-speed milling tool according to the preoperative plan. On the 10th day, CT controls were performed following the same protocol as preoperatively.Results The mean deviation of the postoperative from the preoperatively planned mechanical axis was 0.2° (95% CI: −0.1° to 0.5°). The accuracy of angular component placement in frontal, sagittal and transverse planes was within±1.2°, and the accuracy of linear component placement in mediolateral, dorsoventral and caudocranial directions was within±1.1 mm.Interpretation Robotic TKA allows placement of components with unparalleled accuracy, but further development is mandatory to integrate soft-tissue balancing into the procedure and make it faster, easier and cheaper.

Neutron scattering and molecular correlations in a supercooled liquid.

We show that the intermediate scattering function S(n)(q,t) for neutron scattering (ns) can be expanded naturally with respect to a set of molecular correlation functions that give a complete description of the translational and orientational two-point correlations in the liquid. The general properties of this expansion are discussed with special focus on the q dependence, and hints for a (partial) determination of the molecular correlation functions from neutron scattering results are given. The resulting representation of the static structure factor S(n)(q) is studied in detail for a model system using data from a molecular dynamics simulation of a supercooled liquid of rigid diatomic molecules. The comparison between the exact result for S(n)(q) and different approximations that result from a truncation of the series representation demonstrates its good convergence for the given model system. On the other hand it shows explicitly that the coupling between translational and orientational degrees of freedom of each molecule and rotational motion of different molecules cannot be neglected in the supercooled regime. Further we report the existence of a prepeak in the ns static structure factor of the examined fragile glass former, demonstrating that prepeaks can occur even in the most simple molecular liquids. Besides examining the dependence of the prepeak on the scattering length and the temperature we use the expansion of S(n)(q) into molecular correlation functions to point out the intermediate range orientational order as its principle origin.

Test of the semischematic model for a liquid of linear molecules

We apply to a liquid of linear molecules the semischematic mode-coupling model, previously introduced to describe the center of mass (COM) slow dynamics of a network-forming molecular liquid. We compare the theoretical predictions and numerical results from a molecular dynamics simulation, both for the time and the wave-vector dependence of the COM density-density correlation function. We discuss the relationship between the presented analysis and the results from an approximate solution of the equations from molecular mode-coupling theory [R. Schilling and T. Scheidsteger, Phys. Rev. E 56 2932 (1997)].

Non-ergodicity parameters for a molecular liquid: a comparison between mode coupling theory and simulation

Abstract We apply the mode coupling theory (MCT) which was recently applied to molecular liquids to a liquid of diatomic, rigid molecules. Making use of the static correlators, Sll′m(q), from a molecular dynamical simulation, we have solved the MCT equations for the non-ergodicity parameters (NEP), f l m (q)= lim t→∞ S ll m (q,t)/S ll m (q) , assuming that all correlators are non-zero for l=l′=0,1,…,lco, only. Depending on lco=0,1,2 we obtain different types of ideal glass transitions with transition temperatures, T(l)c which are, from a molecular dynamics (MD) simulation, below TMDc. The q-dependence of the critical NEP, (flm)cMD, from the simulation is reasonably well reproduced by the corresponding MCT result. The affect of a strong and weak diagonalization approximation on the results is discussed.