Christian H. Siebert

A modular femoral implant for uncemented stem revision in THR

Abstract We present the early results of 142 uncemented femoral stem revisions using the modular MRP-Titan system. There were 70 cases with marked preoperative femoral bone defects (Paprosky type 2C and type 3); and bone grafts were used in 31 cases. At a mean follow-up of 2.3 years five cases were re-revised due to dislocation and two due to aseptic loosening. The mean Harris hip score improved from 37.4 preoperatively to 92.4. In 122 cases progressive bone regeneration on X-ray was seen; and no further osteolysis was observed.Résumé  Nous avons évalué les premiers résultats de 142 opérations de changement de la prothèse fémorale sans ciment avec le système MRP-Titan modulaire. Dans 70 cas on a observé avant l’intervention des altérations importantes du fémur (typ 2C et typ 3 après Paprosky). Une greffe osseuse dans la zone de défaut n`a été nécessaire que dans 31 cas. Pendant un temps postopératoire de 2.3 années en moyenne, deux implant a dûêtre changéà cause d`un descellement aseptique de la prothèse. Une deuxième opération a été nécessaire dans cinq cas à cause de luxations répétées. Au niveau fonctionnel, on mesure une amélioration du score de Harris de 37.4 points à 92.4 points. Dans 122 cas on a trouvé un rétablissement de la structure osseuse avec une régénération dans la zone de défaut. Des ostéolyses locales n`ont pas été visibles.

Late results after arthroscopic partial medial meniscectomy

Abstract In a retrospective study, 100 patients underwent a clinical and radiological follow-up examination after a minimum of 7 years (range 7.0–9.3 years) following an arthroscopic partial medial meniscectomy. None of these patients had associated intra-articular lesions, apart from minor chondral damage (max. grade 2 Outerbridge classification; < 1 cm2) of the medial compartment at the time of the primary arthroscopy. According to the modified Marshall score, the follow-up evaluation showed excellent clinical results in 96%. Nevertheless, the radiological outcome, as measured by comparing preoperative and postoperative X-rays, demonstrated a development or progression of the osteoarthritis of the affected knee joint in 33%, with a statistically significant correlation between the radiological and clinical outcomes (P < 0.05). The age of the patients at the time of operation and any angular deformity of the knee joint did not influence the radiological results. Women had a statistically significantly higher risk of developing gonarthrosis after partial medial meniscectomy than men (P < 0.05). The arthroscopic partial medial meniscectomy led to excellent subjective and functional results but could not prevent the increase or development of late degenerative changes in the medial knee compartment.

Spinal stabilization in Duchenne muscular dystrophy: principles of treatment and record of 31 operative treated cases.

The aim of this study was to report results of prophylactic spinal stabilization in patients with Duchenne muscular dystrophy. There is still debate regarding the ideal instrumentation. A prospective study of a consecutive series of 31 patients stabilized with the ISOLA system from D2 to S1 will be presented. The mean follow-up was 22 months (range, 1-60 months). The evaluation of the Cobb angle and pelvic obliquity revealed the following: 1) Cobb angle: preoperation, 48.6 degrees (range, 22-82 degrees); postoperation, 12.5 degrees (range, 0-30 degrees); follow-up, 12.5 degrees (range, 0-42 degrees); and 2) pelvic obliquity: preoperation, 18.2 degrees (range, 3-40 degrees); postoperation, 3.8 degrees (range, 0-13 degrees); follow-up, 5.1 degrees (range, 0-14 degrees). Spinal stabilization with the ISOLA system was found to be a suitable treatment for scoliosis owing to Duchenne muscular dystrophy. It should be carried out after loss of ambulation as soon as a progressive curve of more than 20 degrees is documented. The complication rate was found to be high.

In vivo testing of a new in situ setting β‐tricalcium phosphate cement for osseous reconstruction

A new in situ setting tricalcium phosphate cement was implanted in 1.5-mm trepanation defects in rat femurs. Empty cavities and autologous bone grafts were used as controls. Cement resorption and new bone formation were evaluated in undecalcified sections with histologic examination, contact microradiographies, radiodensitometry, and scanning electron microscopy after 1 and 3 weeks. The mechanical integrity was tested in a three-point bending test. The amount of new bone formation over time was determined by intravital fluorescence staining. With the in situ setting substance, a good filling of the whole trepanation defect was achieved without leakage of the paste-like cement. Slow resorption of the cement and new bone formation beginning at the edge of the defect were seen after 1 week. After 3 weeks, resorption was advanced and there was ingrowth of new bone, with close contact between cement particles and bone, as shown in histologic sections and with a calcium/phosphorus analysis by quantitative line scans of an electron microanalysis (SEM-EPMA). This new self-hardening cement is bioactive, resorbable, and osteotransductive. It may be usable for the filling of stable defects, such as cysts or benign tumors, or for bone supplementation in revision arthroplasty.

Tibio-calcaneo-naviculo-cuboidale arthrodesis: 6 patients followed for 1-8 years.

As a salvage procedure for patients with irreparable damage to the peritalar anatomy, we used a new method, the Ilizarov ring fixator, to stabilize a tibio-calcaneo-naviculo-cuboideal (TCNC) arthrodesis after resecting the talus in 6 patients with an average follow-up of 3 years. The tibia was lengthened by callus distraction, mean 6 (3.5-10) cm. Patients with exacerbation of a chronic talar osteomyelitis, symptomatic posttraumatic changes, and those with extremely unstable club feet and talar deformity preventing an adequate reduction of the joint, were successfully treated with the TCNC-fusion. The method permits early weight bearing, while providing stability and compression of the fusion, thereby avoiding further loss of bone stock.

Correction of kyphotic deformity before and after transection of the anterior longitudinal ligament--a cadaver study.

Abstract With a custom-made measuring unit, two separate experiments, involving six and five cadaveric torsos with intact rib cages and sternums, respectively, were carried out to determine the effect of the transection of the anterior longitudinal ligament with and without osteodiscectomy and its influence on the thoracic kyphosis. The open or thoracoscopically assisted anterior release, as part of the operative treatment of scoliosis or kyphosis, usually consists of a transection of the anterior longitudinal ligament (ALL) and an additional discectomy. A complete osteodiscectomy, however, is not always possible with a minimally invasive approach. As part of our biomechanical research, we attempted to quantify the amount of correction achievable with a defined force prior to and following the isolated transection of the anterior longitudinal ligament. The aim of the study was to clarify whether or not an isolated transection of the anterior longitudinal ligament is sufficient to obtain an adequate anterior release of the spine. In the surgical treatment of kyphotic deformities, anterior release of the spine is performed in the form of a transection of the ALL and discectomy. Recently, video-assisted thoracic surgery has become increasingly popular in spine surgery. As part of this change in surgical technique, the question has arisen as to what extent an isolated transection of the ALL provides an adequate release of the thoracic spine. Eleven human spines were retrieved from fresh cadavers, dissected, and attached to a specially constructed apparatus. The spine was attached to the construct at the twelfth vertebral body. C6 and C7 were fixed in synthetic resin. We installed the instruments in such a manner as to reproducibly apply a torsional moment of 10 Nm to the spine. Motion was only permitted in the sagittal plane. Segmental transections of the ALL were carried out from T3 to T7. For comparison, the sagittal Cobb angle was also documented following an anterior release combined with an osteodiscectomy. With the isolated transection of the ALL, an average correction of the sagittal Cobb angle of 4° in each functional spinal motion segment was recorded. In comparison, the additional osteodiscectomy led to a further average increase of only 2° per level. The measurements performed on human cadavers showed that the isolated transection of the ALL leads to a sufficient anterior release of the thoracic spine, allowing a correction of the kyphotic deformity. The release with a concomitant osteodiscectomy represents a more time-consuming and more invasive procedure resulting in only a slightly greater amelioration of the sagittal Cobb angle, while being associated with a greater patient morbidity.

The quadriceps tendon cyst: an uncommon cause of chronic anterior knee pain.

Abstract The causes of knee pain are manifold. One of the uncommon causes of chronic anterior knee pain are cysts and ganglia. Magnetic resonance imaging not only reveals the intra-articular pathology but also accurately depicts such cystic structures about the knee. As part of this case report, a cyst of the lateral border of the quadriceps tendon is presented as a cause of such discomfort. Although cystic lesions around the knee are a common clinical problem, the described location is rare. After surgical revision of the lateral border of the quadriceps tendon and excision of the cyst, the patient was found to be asymptomatic.

Dynamic Load Balancing for Unstructured Meshes on Space-Filling Curves

Load imbalance is an important impediment on the path towards higher degrees of parallelism - especially for engineering codes with their highly unstructured problem domains. In particular, when load conditions change dynamically, efficient mesh partitioning becomes an indispensable ingredient of scalable design. However, popular graph-based methods such as those used by ParMetis require global knowledge, which effectively limits the problem size on distributed-memory machines. On such architectures, space-filling curves (SFCs) offer a memory-efficient alternative and many sophisticated schemes have already been proposed. In this paper, we present a simple strategy based on SFCs that is custom-tailored to the needs of static meshes with dynamically changing computational load. Exploiting the properties of this class of problems, it is not only easy to implement but also reduces memory requirements substantially. Moreover, exclusively relying on MPI collective operations, our load-balancing scheme also offers portable performance across a broad range of HPC systems. Experimental evaluation shows excellent scaling behavior for up to 16,384 cores on a Nehalem-Infiniband system and up to 294,912 processes on a Blue Gene/P system.

A Simple, Pipelined Algorithm for Large, Irregular All-gather Problems

We present and evaluate a new, simple, pipelined algorithm for large, irregularall-gather problems, useful for the implementation of the MPI_Allgatherv collective operation of MPI. The algorithm can be viewed as an adaptation of a linear ring algorithm for regular all-gather problems for single-ported, clustered multiprocessors to the irregular problem. Compared to the standard ring algorithm, whose performance is dominated by the largest data size broadcast by a process (times the number of processes), the performance of the new algorithm depends only on the total amount of data over all processes. The new algorithm has been implemented within different MPI libraries. Benchmark results on NEC SX-8, Linux clusters with InfiniBand and Gigabit Ethernet, Blue Gene/P, and SiCortex systems show huge performance gains in accordance with the expected behavior.

Reactive knee and ankle joint arthritis: abnormal manifestation of Legionella pneumophila

This case report demonstrates that active legionellosis is not always characterised by pulmonary symptoms and specific radiomorphological findings. Whereas the initial clinical presentation, as described in the literature, includes fever, cough, expectoration, extrapulmonary organ changes or typical laboratory findings, atypical manifestations such as reactive arthritis must be considered.