Long-term results of reconstructing the joints' articular surface in the knee and ankle with the surgical diamond instrumentation (SDI).

PURPOSE: The surgical diamond instrumentation (SDI), a precise wet-grinding technology, promised contact healing of press-fit inserted bone and even hyaline cartilage, lacks medium- and long-term results. This retrospective study was conducted to identify risk factors associated with the failure of the technique and the subjective patient outcome. METHODS: All patients treated for cartilage defects of the knee or ankle joint using the SDI technology between 2000 and 2012 with a follow-up > 1 year were included. Patients with general joint diseases or joint-related procedures, except for corrective osteotomies, were excluded. A standardized questionnaire (EQ-5D) and a questionnaire-based patient-reported outcome survey were used. Descriptive statistics were applied. A multivariate analysis examining risk factors for joint failure was performed. A p value < 0.05 was considered to indicate significant differences. RESULTS: 87 patients with autologous osteochondral transplantation (68 knee, 19 ankle) were included. The median age was 53 years (IQR 37.5-63.0 years) for knee and 36 years (IQR 27.5-54.0 years) for ankle joints. 57.9% of knee and 55.6% of ankle patients were female. Nine patients (8 knee, 1 ankle) had received arthroplasty. 93.3% of knee and 83.3% of ankle patients had an excellent function or minor disabilities. 73.3% of knee and 64.7% of ankle patients did not require pain medication. The mean EQ-5D score was 0.84 for knee and 0.77 for ankle. Patients with higher age were more likely to receive arthroplasty (p = 0.022). CONCLUSIONS: The SDI technique provides promising results with excellent joint survival rates and satisfying patient-reported outcomes. Failure of the technique might be associated with higher age.

Autologous resurfacing.

BACKGROUND: There is a discrepancy between the interest in joint-reconstructions and the current knowledge about the healing-processes involved. Major reconstructions are performed with osteosynthesized allografts and fresh allografts for cartilage. OBJECTIVES: The main question to be answered is: what do we know about metaphyseal and epiphyseal cancellous bone healing, contact healing of the subchondral bone and its influence on cartilage healing? Can we achieve healing of all four compartments in contact? PURPOSE: The purpose is to systematically investigate through animal testing the healing processes of metaphyseal and epiphyseal bone, including the subchondral bone and the healing of cartilage of press-fit-inserted grafts, considering nondemineralized high-resolution histology. MATERIAL AND METHODS: Primary cancellous-bone healing of osteosynthesized hemi-osteotomies was studied in 13 canine tibial heads, the contact healing was investigated in 7 dogs and 18 giant-rabbits comparing contact-healing of press-fit-inserted autologs cylindrical grafts with empty defects applying the wet-grinding diamond-technology. Bench-experiments on the epiphyseal bones of swine including pullout-tests of cylindrical grafts formed the basis for validation of that press-fit diamond technology. RESULTS: Primary metaphyseal and epiphyseal contact healing, including hyaline cartilage, was found in all compartments of the meta-and epiphysis in the precisely performed experiments. The press-fit principle, which employs cylindrical grafts and diamond instrumentation featuring a difference of 15/100 mm between graft and recipient bed, achieved high loads between 73.48 and 178.95 N (mean value 118.16 and standard deviation 32.79) in the pullout tests. CONCLUSION: Autologous press-fit grafting with alignment of the bony baseplate using wet-grinding precision has attained promising histo-morphological results.

The bone-to-cement interface improvement by Ca-phosphate ceramics.

BACKGROUND: Polymethylmethacrylate used in surgery is one of the first biomaterials. Conventional histology dissolves the resin; one of the reasons that only few complete histology is published. OBJECTIVES AND PURPOSE: The question is, whether a complete histology changes the understanding, influences the application and opens approaches for improvements. The dos and don'ts of the processing technology are presented in reproducible manner. MATERIAL AND METHODS: Ten femurs of giant rabbits were taken from running experiments of femur-canal filling with bone cement. Different stages were considered for high-resolution histology and electron microscopy: 4-weeks-stage (bone healing), 12-weeks-stage (remodelling) and one and two years. A human-cadaver specimen with a follow up of two years was processed. All animals were perfusion-fixated and the complete vasculature micro-casted. Serial cuts were performed with a stone saw, followed by a wet grinding processing. The fluorescence documentation in the High Intensity Incident Fluorescent Light (HIIFL) and Orthoplan Leitz Ploemopak(®) was applied and high resolution microradiography used the Siemens Kristalloflex(®) . The Scanning Electron Microscopy (SEM) was performed applying deep-freezing technology for the PSEM-500. The human specimen was embedded after sectioning using epoxy-resin. RESULTS: All cement implants showed osseointegration and remodelling with a tangential adherence of bone onto the ceramic/PMMA surfaces. Intact cancellous structures after one and two years did not show any signs of heat necrosis. The human specimen confirmed the results from the animal experiments. CONCLUSION: The complete bone-to-cement histology changed the understanding of the bone cements function, influenced its application and opened new ways for improvement.

ε-Caprolactone in micro-chambered ceramic beads--a new carrier for gentamicin.

PURPOSE: The purpose of this preliminary and descriptive study was to evaluate a biodegradable drug delivery system in combination with an innovative ceramic implant. METHODS: The delivery of gentamicin of standardized samples was measured in the laboratory using ultra-high-performance liquid chromatography. Biocompatibility and biodegradation of the materials was investigated in an animal experiment in sheep up to 14 months. As carrier ε-caprolactone, 1:1 mixed with gentamicin, intruded into micro-chambered ß-tricalcium-phosphate beads (MCB®) was studied. RESULTS AND DISCUSSION: Gentamicin was released in calculable concentrations during the first 30 days. The release from ε-caprolactone was higher than that from polymethylmethacrylate and more predictable. The caprolactone carrier was reabsorbed by osteoclasts.

Strain adaptive bone remodelling in total joint replacement.

Histomorphologic analyses of artificial joint components implanted into bone need special technology for processing and for documentation; published histological work systematically done therefore is rare. The histopathology, three-dimensionally analyzed in a complete sequence of sections is, however, the only precise answer in terms of biocompatibility and bone response. A complete analysis allows a type-related predictable prognosis of an implantation that is at least comparable to a finite element analysis with respect to load transfer to host bone. The histopathologic collection of the ZOW Munich is comprised of more than 5000 nondemineralized bone and joint specimens and more than 500 artificial joint components implanted in the human skeleton for up to 25 years. Fifty-nine implant-bone specimens without signs of loosening already have been processed and analyzed systematically. According to the strain-adapted bone remodelling, different types of anchorage clearly were differentiated and their morphologic substrate could be worked out. Based on that, the cemented standard anchorage could be distinguished histologically from the cemented press-fit procedure, and the noncemented press-fit from the porous ingrowths pattern. In terms of the topography of the bony integration, the proximal and distal press-fit and ingrowth pattern were analyzed; beside that, the cemented and noncemented epiphyseal resurfacings could be defined histologically. In all histologic specimens the remodelling appeared as a result of stress-related strain, reflecting stiffness of the implant and the resistance of bone to deformation. It clearly was worked out that all success of cemented components is based on preserved cancellous bone honeycombs stiffened by bone cement, representing an adaptation of bone in terms of stiffness to the stiff implants.