Osteochondrosis juvenilis of the medial malleolar epiphysis

Osteochondrosis juvenilis is caused by a dysfunction of endochondral ossification. Several epiphyses and apophyses can be affected, but osteochondrosis juvenilis of the medial malleolus has not been reported. We describe a 12-year-old boy with bilateral pes planovalgus who was affected by this condition. Conservative management was successful. The presentation, aetiology and treatment are described and the importance of including it in the differential diagnosis is discussed.

Proposal for a nomenclature for magnetic resonance imaging based measures of articular cartilage in osteoarthritis

OBJECTIVE

Magnetic resonance imaging (MRI) of articular cartilage has evolved to be an important tool in research on cartilage (patho)physiology and osteoarthritis (OA). MRI provides a wealth of novel and quantitative information, but there exists no commonly accepted terminology for reporting these metrics. The objective of this initiative was to propose a nomenclature for definitions and names to be used in scientific communications and to give recommendations as to which minimal methodological information should be provided when reporting MRI-based measures of articular cartilage in OA.

METHODS

An international group of experts with direct experience in MRI measurement of cartilage morphology or composition reviewed the existing literature. Through an iterative process that included a meeting with a larger group of scientists and clinicians (December 2nd, 2004, Chicago, IL, USA), they discussed, refined, and proposed a nomenclature for MRI-based measures of articular cartilage in OA.

RESULTS

The group proposes a nomenclature that describes: (1) the anatomical location and (2) the structural feature being measured, each name consisting of a metric variable combined with a tissue label. In addition, the group recommends minimal methodological information that should be described.

CONCLUSIONS

Utilization of this nomenclature should facilitate communication within the scientific community. Further, the uniform adoption of comprehensive nomenclature to describe quantitative MRI- features of articular cartilage should strengthen epidemiological, clinical, and pharmacological studies in OA.

Periprothetische Frakturen nach Knietotalendoprothetik

The increasing implantation rates of knee arthroplasties are associated with a growing prevalence of complications like periprosthetic fractures. Underlying patient, implant and/or operation technique-related risk factors contribute to these fractures which often occur after minor trauma. In the diagnostic process, fracture dislocation, implant stability, and integrity of the extensor mechanism have to be assessed. Valid classification systems are available to guide treatment decisions. Treatment goals are precise reposition, stable fixation, restoration of function, and early mobilization. In the case of an operative revision, the surgeon has to know the implanted device and has to be prepared for extended procedures and revision arthroplasty. Less invasive fixation devices like retrograde nailing or LISS are often sufficient to stabilize femoral supracondylar fractures, while loosening of the implant often requires extended exchange arthroplasty. Tibial fractures are often associated with osteolysis and bone loss which has to be addressed with bone grafts or augmented revision implants. Long-stemmed implants allow bypassing of the reconstructed defect and provide a stable solution for early mobilization. Patella fractures with stable or asymptomatic implants and continuity of the extensor mechanism should be treated conservatively. If reconstruction becomes necessary, results are often associated with significant functional limitations.

Effects of joint unloading and reloading on human cartilage morphology and function, muscle cross-sectional areas, and bone density - a quantitative case report

Recent studies have shown that thinning of human cartilage occurs with unloading, but no data are available on the effect of remobilization (after immobilization) on knee joint cartilage status in humans. We examined a 36-year-old patient after 6 weeks of unilateral immobilization. Knee joint cartilage morphology (patella and tibia), patellar cartilage deformation, and thigh muscle cross-sectional areas were assessed with quantitative MR imaging and bone density with peripheral quantitative computed tomography (pQCT) during 24 months of remobilization. The immobilized limb displayed lower muscle cross-sectional areas (MCSA) of the knee extensors (-36%), lower bone density of the femur and tibia (-12/-6%), lower patellar cartilage thickness (-14%), but no side differences of tibial cartilage thickness. During remobilization, side differences decreased to -4% for knee extensor MCSAs, to -6%/-3% for femoral and tibial BMD, and to -8% for patellar cartilage thickness. No change was observed in tibial cartilage. Patellar deformation decreased from 9% to 4% after 15 months. In conclusion, we observed substantial changes of thigh MCSAs, but little (patella) to no (tibia) change in cartilage thickness during remobilization. These preliminary results indicate that human cartilage macro-morphology may be less adaptive to variations of the mechanical loading than muscle and bone.

[Reconstruction of the extensor tendons in revision total knee arthroplasty and tumor surgery]

Reconstruction of the extensor mechanism in extended revision after total knee replacement and tumor surgery remains a clinically relevant problem. Due to large tibial bone defects with resection of the extensor insertion area, the specific problem of patella ligament refixation frequently arises. Several biological approaches and augmentation techniques have been published. Most of these are associated with a high rate of revision surgery because of failed replacement of the extensor mechanism and unsatisfactory functional outcome. Surgical reconstruction of these tendon defects is complicated by the difficulty of completely neutralizing tensional force across the repair. To overcome this problem, methods have been developed to reinforce the reconstruction with overlapping flaps; in addition, artificial materials are being increasingly used for tension neutralization. These artificial strips need special fixation mechanisms on the tibial component and specific technical modifications of the prosthesis. The present study gives an overview of reconstruction modalities of the extensor mechanism and provides an improved technology for better reconstruction by using artificial strips combined with specific modifications of the tibial component.

[Therapy of arthrofibrosis after total knee arthroplasty]

Arthrofibrosis is one of the most common complications after total knee arthroplasty with an overall incidence of approximately 10%. Nevertheless, published data are rare and clinical trials mostly include small and heterogeneous patient series resulting in controversial conclusions. Clinically, arthrofibrosis after knee arthroplasty is defined as (painful) stiffness with scarring and soft tissue proliferation. Differentiation between local (peripatellar) and generalized fibrosis is therapeutically relevant. Histopathology typically shows subsynovial fibrosis with synovial hyperplasia, chronic inflammatory infiltration, and excessive and unregulated proliferation of collagen and fibroblasts. Diagnostic strategies are based on the exclusion of differential causes for painful knee stiffness, and especially the exclusion of low-grade infections represents a diagnostic challenge. Early and intensive physiotherapy combined with sufficient analgesia should be initiated as a basic therapy. The next therapeutic steps for persisting arthrofibrosis include closed manipulation and open arthrolysis. Arthroscopic interventions should be limited to local fibrosis. Revision arthroplasty represents a rescue surgery, often associated with recurrence of fibrosis. Prevention of arthrofibrosis by sufficient analgesia and early physiotherapy remains the best treatment option for painful stiffness after knee arthroplasty.

Biomechanische Aspekte von Wechselkomponenten für den Kniegelenkersatz

Total knee arthroplasty (TKA) is one of the most frequent orthopaedic surgical procedures. Despite continuous improvements in the endoprostheses, instruments, and operative techniques, revision TKA has a rate of about 10% of overall TKA. In addition to the restoration of the periprosthetic bone stock and a precise alignment, the choice of an adequate implant, which meets the patient's specific requirements, has high impact on the outcome. The most significant differences between implants involve the degree of reconstructed joint area (uni-, bi-, tri-compartimental) and the order of the constraining forces between the femoral and tibial component. Implants for revision TKA commonly range from un- or semiconstrained resurfacing implants to fully constrained hinged endoprostheses. In case of severe osseous, ligamentous, and/or muscular defects, special tumor endoprostheses or implants for arthrodesis might be an alternative option.

Intraoperative, fluoroscopy-based planning for complex osteotomies of the proximal femur

Intertrochanteric osteotomy of the proximal femur is a surgical technique that aims at changing the orientation of the proximal part of the femur in the hip joint by removing a bone wedge between the trochanters. Due to its six degrees of freedom, it presents a complex planning problem for the surgeon. In this paper, we propose an intraoperative planning system for proximal femur osteotomies. Based on two fluoroscopic images taken during the procedure, a primitive femur model is reconstructed, which then allows the user to interactively determine the osteotomy parameters and perform the intervention with the help of a navigation system. Besides the fluoroscopic images, no other imaging is needed. Compared to the traditional approach, this system allows the intervention to be performed with higher precision and less radiation exposure for both patient and surgeon, requiring only little time overhead. An in vitro study has demonstrated the high accuracy and ease of use of this system.

A robotic C-arm fluoroscope

Fluoroscopic C-arms are common devices for acquiring images during surgery. Manual positioning is time consuming and requires considerable experience. Trained users must often take several images to find the best viewing direction. If a second image must be taken from the same position, e.g. for postoperative control, the C-arm must be moved to the exact same position. Without guidance, this is often difficult to accomplish. We developed the idea to completely "robotize" a standard C-arm, i.e. to equip all joints with motors and encoders. A software environment provides for intelligent control. To archive this goal a complete kinematic analysis of the fluoroscope was necessary. On the basis of this analysis a number of clinical applications have been developed: (1) simplified positioning via cartesian control; (2) automatic acquisition of panoramic images; (3) 3D CT with arbitrary viewing angles; (4) 4D intraoperative CT with/without respiration triggering; (5) automated anatomy-oriented positioning. The goal of this research is thus three-fold: minimise radiation exposure of the OR staff, reduce positioning time and offer enhanced imaging capability.

[Chronic radiculopathy. Use of minimally invasive percutaneous epidural neurolysis according to Racz]

Treatment of chronic low back pain exhibiting radicular symptoms poses a clinical problem that has not yet been solved. The technique of percutaneous minimally invasive neurolysis described by Racz is being performed increasingly to treat chronic radiculopathy. A total of 61 patients with corresponding symptomatology after screening for inclusion and exclusion criteria in the region of the lumbar spinal nerve were treated with the Racz catheter technique. Distinct clinical improvement was observed at the 3- and 6-month follow-ups after percutaneous minimally invasive epidural neurolysis. Subjective pain perception, quantified by the McNab score, clearly improved after 3 as well as 6 months. With the exception of partial catheter shearing in two cases and one occurrence of infection, no relevant side effects were noted. The Racz catheter technique for treatment of chronic radiculopathy following disk surgery is suitable with minimal side effects.

Fluoroskopiebasierte 3D-Navigation komplexer Korrekturosteotomien des proximalen Femurs

BACKGROUND

Despite great advances in hip alloarthroplasty there are still numerous indications for joint-saving procedures such as correction osteotomies. Often these procedures include complex 3D rearrangements of the proximal femur, which are for the surgeon technically very demanding. The project aim was to develop a precise intraoperative virtual 3D planning tool including a detailed biomechanical analysis and enable the surgeon to realize exactly this plan by using computer-assisted techniques.

METHODS

Using only two different angled fluoro frames a simplified femoral model was inversely constructed. For navigation a passive optical system was used with a C-arm calibration kit and PC-based software. For in vitro evaluation complex osteotomies were performed on ten femora under simulated OR conditions.

RESULTS

The mean difference between the planning and real surgical outcome for the wedge size was less then 2 degrees and for the femur head center position less then 4 mm. No implant penetrated the femur neck isthmus.

CONCLUSION

Without changing the standard operative procedure the method can be of high clinical importance to improve planning accuracy and consecutive operative realization for precise fragment positioning and plate location without penetrating the isthmus of the femoral neck. And -- besides precision -- it can potentially help to reduce intraoperative complications such as implant penetration and minimize X-ray use.

[Diagnosis specific differences in knee joint geometry. A challenge for the correct axial implantation of long stems in total knee arthroplasty]

BACKGROUND

Arthrotic deformities with changes in knee geometry can produce difficulties in implanting long stem knee prosthesis systems using intramedullary alignment. They can result in incorrect lower limb axis and prosthesis positioning. The aim of the presented study was to measure knee geometry in patients with varus and valgus gonarthrosis in order to define diagnosis related differences.

METHODS

A total of 75 patients with indication for total knee arthroplasty were divided in two groups using the weight bearing lower limb axis: patients with varus gonarthrosis (n=43) and with valgus gonarthrosis (n=32). Angles and extensions, important for knee prosthesis implantation, were measured, digitalized and analyzed. The results were investigated for diagnosis specific differences.

RESULTS

After regulation of the measured extension in mean femur/tibia lengths, significant diagnosis specific differences were found: femur condyles were widened towards pathologic weight bearing (P<0.044), and the mechanical tibia axis of the varus gonarthrosis group is transferred to the lateral side (P<0.046) and in projection over the lateral internal cortical substance.

CONCLUSION

The significant differences in deformed arthrotic knees indicate that for an optimal postoperative result the use of standard implants is not always sufficient. Modular knee prosthesis systems can provide adequately for individual demands.

Optimised robot-based system for the exploration of elastic joint properties

Numerous publications provide measured biomechanical data relating to synovial joints. However, in general, they do not reflect the non-linear elastic joint properties in detail or do not consider all degrees of freedom (DOF), or the quantity of data is sparse. To perform more comprehensive, extended measurements of elastic joint properties, an optimised robot-based approach was developed. The basis was an industrial, high-precision robot that was capable of applying loads to the joint and measuring the joint displacement in 6 DOF. The system was equipped with novel, custom-made control hardware. In contrast to the commonly used sampling rates that are below 100 Hz, a rate of 4 kHz was realised for each DOF. This made it possible to implement advanced, highly dynamic, quasi-continuous closed-loop controllers. Thus oscillations of the robot were avoided, and measurements were speeded up. The stiffness of the entire system was greater than 44 kNm(-1) and 22 Nm deg(-1), and the maximum difference between two successive measurements was less than 0.5 deg. A sophisticated CT-based referencing routine facilitated the matching of kinematic data with the individual anatomy of the tested joint. The detailed detection of the elastic varus-valgus properties of a human knee joint is described, and the need for high spatial resolution is demonstrated.

[Prosthetic possibilities after amputations in the upper extremities]

Whereas passive prostheses are fitted onto the patient after the amputation of an arm, hand or finger and are mostly cosmetic in function, active prostheses have much more potential. They can transform the movements of other body regions to movement in the artificial limb. Belts or harnesses, for example, effect the direct transfer of the power from the muscle to the prosthesis. The range of movement possible depends upon the level of the amputation, the length of the residual limb, the age of the patient, his body build and fitness. Myoelectrically controlled prostheses possess their own drive and power source. They control movement through the electrical action potentials of the residual limb muscles, which are detected, amplified and transmitted with help of electrodes.

Feasibility of T and Z scores from magnetic resonance imaging data for quantification of cartilage loss in osteoarthritis

OBJECTIVE

T scores (an indicator of the difference between patients and young healthy subjects) and Z scores (an indicator of the difference between patients and age-matched healthy subjects) are used in the diagnosis of osteoporosis and form the current basis for the definition of osteoporosis by the World Health Organization. We tested the feasibility of using T and Z scores derived from quantitative cartilage imaging with magnetic resonance imaging (MRI) for the diagnosis of osteoarthritis (OA).

METHODS

High-resolution MR images of tibial cartilage were acquired from 126 young healthy adults (ages 20-35 years), 24 age-matched elderly healthy adults (ages 50-75 years), 7 OA patients prior to tibial osteotomy, and 7 OA patients prior to knee arthroplasty. Cartilage volume, thickness, surface area, and original joint surface area (before onset of disease) were determined in the medial and lateral tibia.

RESULTS

The cartilage volume of the medial tibia of osteotomy patients with varus malalignment displayed moderate T scores (-1.0), and more negative T scores (-3.8) were observed in knee arthroplasty patients with varus malalignment. Normalization of the cartilage volume to the original joint surface area substantially enhanced the scores in patients undergoing osteotomy (-2.3) and in patients undergoing knee arthroplasty (-5.5), and this was superior to the normalization ratios of cartilage volume to body height and cartilage volume to body weight, in terms of distinguishing the loss of articular cartilage.

CONCLUSION

Quantitative analysis of OA by MRI is feasible using T and Z scores. However, cartilage volume should be normalized to the individual joint surface area in order to maximize the discriminatory power of this technique for the diagnosis of OA.

[Leading symptom elbow pain. Differential diagnosis]

Pain affecting the elbow joint may be caused by a number of different pathologies. In principle, these can be grouped by causality criteria into degenerative causes, inflammatory causes, tumor disease, congenital disease and the sequelae of trauma. The majority of these latter are associated with typical clinical symptoms that can be established with the aid of a systematic clinical examination, history-taking, inspection, palpation, an examination of joint mobility, and finally radiography. In this way, the diagnosis can rapidly be established.

[Congenital clubfoot]

Owing to the relatively high incidence of this condition (2 in 1,000 neonates) and the poor functional outcome of inadequate treatment, clubfoot represents a major clinical problem. Although its etiology is not fully known, modern three-dimensional analyses have led to a better understanding of the pathomorphology and provide a new basis for a differentiated therapeutic strategy. Of central importance is early diagnosis and immediate postpartum initiation of primarily conservative treatment taking the form of intensive redressment measures. Depending on the residual deformity, an appropriate surgical procedure aimed at achieving complete correction should be done between the age of 4 to 6 months. To ensure a lasting positive outcome, rigorous follow-up physiotherapeutic treatment and close surveillance are essential.

[Initial results with the Munich knee simulator]

In orthopaedics more than 50 different clinical knee joint evaluation tests exist that have to be trained in orthopaedic education. Often it is not possible to obtain sufficient practical training in a clinical environment. The training can be improved by Virtual Reality technology. In the frame of the Munich Knee Joint Simulation project an artificial leg with anatomical properties is attached by a force-torque sensor to an industrial robot. The recorded forces and torques are the input for a simple biomechanical model of the human knee joint. The robot is controlled in such way that the user gets the feeling he moves a real leg. The leg is embedded in a realistic environment with a couch and a patient on it.