Novel Measurement Technique of the Tibial Slope on Conventional MRI

The posterior inclination of the tibial plateau, which is referred to as posterior tibial slope, is determined routinely on lateral radiographs. However, radiographically, it is not always possible to reliably recognize the lateral plateau, making a separate assessment of the medial and lateral plateaus difficult. We propose a technique to measure the plateaus separately by defining a tibial longitudinal axis on a conventional MRI. The medial plateau posterior tibial slope obtained from radiographs was compared with MR images in 100 consecutive patients with knee pain when ligament or meniscal injury was assumed. The posterior tibial slope on MRI correlated with those on radiographs. The mean posterior tibial slope was 3.4° smaller on MRI compared with radiographs (4.8°±2.4° versus 8.2°±2.8°, respectively). The reproducibility was slightly better on radiographs than MRI (±0.9° versus±1.4°). Twenty-one of the 100 cases had more than a 5° difference (range, −8.7° to 8.9°) between the medial and lateral plateaus. The proposed technique allows measurement of the posterior tibial slope of the medial and lateral plateaus on a standard knee MRI. By using this novel measurement technique, a reliable assessment of the medial and lateral tibial plateaus is possible. Level of Evidence: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidenc

Expression of Atrophy mRNA Relates to Tendon Tear Size in Supraspinatus Muscle

Skeletal muscle atrophy and fatty infiltration develop after tendon tearing. The extent of atrophy serves as one prognostic factor for the outcome of surgical repair of rotator cuff tendon tears. We asked whether mRNA of genes involved in regulation of degradative processes leading to muscle atrophy, ie, FOXOs, MSTN, calpains, cathepsins, and transcripts of the ubiquitin-proteasome pathway, are overexpressed in the supraspinatus muscle in patients with and without rotator cuff tears. We evaluated biopsy specimens collected during surgery of 53 consecutive patients with different sizes of rotator cuff tendon tears and six without tears. The levels of corresponding gene transcripts in total RNA extracts were assessed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Supraspinatus muscle atrophy was assessed by MRI. The area of muscle tissue (or atrophy), decreased (increased) with increasing tendon tear size. The transcripts of CAPN1, UBE2B, and UBE3A were upregulated more than twofold in massive rotator cuff tears as opposed to smaller tears or patients without tears. These atrophy gene products may be involved in cellular processes that impair functional recovery of affected muscles after surgical rotator cuff repair. However, the damaging effects of gene products in their respective proteolytic processes on muscle structures and proteins remains to be investigate

Improvement of a robot based experimental setup for the assessment of biomechanic properties of the knee in 6 degrees of freedom

Eine exakte und reproduzierbare Analyse biomechanischer Eigenschaften des Kniegelenks stellt die Grundlage für das Verständnis und die Therapie von Verletzungen dar. Im Rahmen einer Machbarkeitsstudie wurde ein roboterbasierter Versuchsstand entwickelt, der eine exakte und umfangreiche Analyse des Kniegelenks in 6 Freiheitsgraden ermöglicht. Im Vergleich zu bekannten Systemen konnte die Meßdauer um 75% reduziert werden, bei sehr hoher technischer Genauigkeit und Reproduzierbarkeit. Zusätzlich konnte erstmals eine Methodik zur transversalen Positionierung des tibialen vorderen Kreuzbandansatzes mit gleichzeitiger Kraftmessung und zeitgleich der Einfluß einer Positionierung auf die Kinematik des Kniegelenks untersucht werden. Das anatomische Kreuzband wurde als physiologisches Transplantat gewählt, um eine parameterweise Analyse zu ermöglichen. Der Versuchsaufbau dient als Grundlage für vergleichende Messungen verschiedener Kreuzbandtransplantate und Positionen an einem Kniegelenk.An exact and reproducible analysis of biomechanical properties of the knee is the basis for the understanding and therapy of injuries. In a feasibility study a robot based experimental setup was developed to allow an exact and comprehensive analysis of the knee in 6 degrees of freedom. Compared to other known systems the measurement duration was reduced by 75% with a very high technical accuracy and reproducibility. Furthermore, a method was developed to position the tibial insertion of the anterior cruciate ligament (ACL) in the transverse plane. Simultaneously the forces in the ACL and the influence of the positioning on the kinematics of the knee could be measured. The anatomical ACL was used as a physiological transplant to enable a parametric analysis. The experimental setup is supposed to provide the basis for comparative measurements of different ACL transplants and positions in a specific knee