BackgroundThe purpose of this study is to describe the mechanical durability and the clinical and radiographic outcomes of a viscoelastic total disc replacement (VTDR). The human intervertebral disc is a complex, viscoelastic structure, permitting and constraining motion in 3 axes, thus providing stability. The ideal disc replacement should be viscoelastic and deformable in all directions, and it should restore disc height and angle.MethodsMechanical testing was conducted to validate the durability of the VTDR, and a clinical study was conducted to evaluate safety and performance. Fifty patients with single-level, symptomatic lumbar degenerative disc disease at L4-5 or L5-S1 were enrolled in a clinical trial at 3 European sites. Patients were assessed clinically and radiographically for 2 years by the Oswestry Disability Index (ODI), a visual analog scale (VAS), and independent radiographic analyses.ResultsThe VTDR showed a fatigue life in excess of 50 million cycles (50-year equivalent) and a physiologically appropriate level of stiffness, motion, geometry, and viscoelasticity. We enrolled 28 men and 22 women in the clinical study, with a mean age of 40 years. Independent quantitative radiographic assessment indicated that the VTDR restored and maintained disc height and lordosis while providing physiologic motion. Mean ODI scores decreased from 48% preoperatively to 23% at 2 years’ follow-up. Mean VAS low-back pain scores decreased from 7.1 cm to 2.9 cm. Median scores indicated that half of the patient population had ODI scores below 10% and VAS low-back pain scores below 0.95 cm at 2 years.ConclusionsThe VTDR has excellent durability and performs clinically and radiographically as intended for the treatment of symptomatic lumbar degenerative disc disease.Clinical RelevanceThe VTDR is intended to restore healthy anatomic properties and stability characteristics to the spinal segment. This study is the first to evaluate a VTDR in a 50-patient, multicenter European study.

Zusammenfassung OperationszielHeilung lokalisierter Knorpelschäden am Knie, um die Funktionsfähigkeit des Gelenks zu erhalten oder wiederherzustellen. IndikationenUmschriebene traumatische oder degenerative Knorpelschäden oder Schäden bei Osteochondrosis dissecans eines Femurkondylus. KontraindikationenGleichzeitige fortgeschrittene Gonarthrose, akute und chronische Arthritis. OperationstechnikAnteromediale Arthrotomie. Aus defekten Knorpelarealen werden Knorpel-Knochen-Zylinder entnommen und verworfen. Aus den Randbereichen des patellaren femoralen Gleitlagers werden entsprechende Knorpel-Knochen-Zylinder entnommen und "press fit" in die Defektzone transplantiert. Es werden diamantbesetzte, innengekühlte Knochenfräsen und Knorpelstanzen verwendet, die als Zwillingsinstrumente Zylinder von 2,8-20,05 mm Durchmesser erzeugen können. Für die Knorpelschäden pathogenetisch wesentliche Bandinstabilitäten und Achsfehler müssen vor oder während der Knorpelsanierung korrigiert werden. WeiterbehandlungMotorschienenbehandlung ("continuous passive motion") während der stationären Behandlung; für 2 Wochen Teilbelastung bis halbes Körpergewicht, anschließend Vollbelastung. Sportfähigkeit nach 3 Monaten. Ergebnisse52 Patienten (23 Männer, 29 Frauen, Durchschnittsalter 36,4 [17-72] Jahre) mit Knorpeldefekten im Kniegelenk wurden operiert. Die durchschnittliche Nachuntersuchungszeit betrug 56 (12-84) Monate. 15 Patienten wiesen eine traumatische Knorpelläsion und elf eine Osteochondrosis dissecans auf. Bei 26 Patienten lag eine halbseitige Gonarthrose vor. Nach dem Lysholm-und Knee-Society- Abstract ObjectiveHealing of localized cartilaginous defects at the knee to maintain or to restore function.

Chondroblastoma is a rare benign bone tumor of cartilaginous origin. The typical localization of a chondroblastoma is the epiphysis of long tubular bones--the patella is a very unusual site with an estimated occurrence of 2%. We report a case of a 16-year-old patient with a chondroblastoma of the patella associated with a pathologic fracture. Partial resection of the patella was performed. This is the sixth case in the literature that associates patellar chondroblastoma with fracture.

Background Lumbar disc degeneration (LDD) is one of the most frequently diagnosed spinal diseases. The symptoms these disorders cause are anticipated to increase as the population in Western countries ages.

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Hollow prostheses appear to represent a promising approach for the durable fixation of cementless hip-joint endoprostheses. The goal of the planned development is the design-engineering, quality-assured production and clinical testing of hollow prostheses displaying largest possible interior space and optimized wall thickness. With hollow prostheses the possibility exists for the first time of filling both the interior space of the prosthesis and cavities between the prosthesis bearing and the prosthesis with spongiosa. Theoretical considerations indicate that this should result in early and durable secondary stability. First results from animal experiments show that the canine femora operated on display a stress distribution closely approximating the natural stress distribution in the bone and exhibit the expected ingrowth of spongiosa into the interior space of the hollow prosthesis. The choice of suitable materials and particularly of wall thickness and cross-sectional shape has a decisive bearing on the elastic behaviour of the prosthesis. Compared with a solid prosthesis of the same geometry, a hollow prosthesis exhibits reduced flexural rigidity and hence higher elasticity. The dynamic tests performed on hollow prostheses in line with DIN 58,840 have shown that--given careful design and manufacture as well as effective quality-assurance measures--fatigue failure is not to be expected in the case of hollow prostheses.