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The Journal of Bone & Joint Surgery British Volume
Vol. 87-B, Issue 3 | Pages 426 - 432
1 Mar 2005
Mueller CA Eingartner C Schreitmueller E Rupp S Goldhahn J Schuler F Weise K Pfister U Suedkamp NP

The treatment of fractures of the proximal tibia is complex and makes great demands on the implants used. Our study aimed to identify what levels of primary stability could be achieved with various forms of osteosynthesis in the treatment of diaphyseal fractures of the proximal tibia. Pairs of human tibiae were investigated. An unstable fracture was simulated by creating a defect at the metaphyseal-diaphyseal junction. Six implants were tested in a uniaxial testing device (Instron) using the quasi-static and displacement-controlled modes and the force-displacement curve was recorded. The movements of each fragment and of the implant were recorded video-optically (MacReflex, Qualysis). Axial deviations were evaluated at 300 N.

The results show that the nailing systems tolerated the highest forces. The lowest axial deviations in varus and valgus were also found for the nailing systems; the highest axial deviations were recorded for the buttress plate and the less invasive stabilising system (LISS). In terms of rotational displacement the LISS was better than the buttress plate.

In summary, it was found that higher loads were better tolerated by centrally placed load carriers than by eccentrically placed ones. In the case of the latter, it appears advantageous to use additive procedures for medial buttressing in the early phase.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 234 - 234
1 Mar 2004
Adam F Pape D Schiel K Rupp S Kohn D
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Aims: The purpose was to evaluate the biomechanical properties of Hamstring graft fixation methods with ability for circumferential graft ingrowth in a standardized experiment with high precision Radiostereometric Analysis (RSA). Methods: We used 30 porcine specimens for the study. A fourstranded graft was sutured with a baseball stitch. Ten trials were performed in each group. The sutured end of the graft was fixed with a Washer-Lock (WL) or two resorbable Cross-Pins (CP). In the Suture-Disc (SD) group 8 polyester sutures (Ethibond 5USP) were knotted over a titanium button. The tibial bone and the tendon-graft were marked with tantalum beads. The grafts were loaded axially under RSA control increasing the force in steps of 50N to load of failure. Micromotion between tendon graft and tibial bone was measured with RSA. Results: Load at failure was significantly higher for the WL and CP fixation (722±173N; 647±129N) compared to SD fixation (445±37N). Stiffness of fixation was significantly higher for WL and CP fixation 492N/mm; 416N/mm) compared to SD fixation 111N/mm). Graft displacement started at low loads for SD fixation (47N) compared to WL and CP (344N; 250N). Graft motion at 200N load was significantly higher in the SD group (1.85mm) than for the WL (0.33mm) and CP (0.3mm) fixation. Bungee cord effect at 200N for the SD was measured 1.32mm, for the CP 0.50mm and for the WL 0.22mm in average. Conclusions: Direct fixation of a quadrupled tendon graft with WL or CP is preferable to SD fixation. Low linear stiffness of SD fixation with linkage suture material allows for a high amount of elastic deformation.


The Journal of Bone & Joint Surgery British Volume
Vol. 83-B, Issue 6 | Pages 832 - 833
1 Aug 2001
Gödde S Rupp S Dienst M Seil R Kohn D

The Fulkerson osteotomy has proved to be a reliable treatment for subluxation of the patella due to malalignment. Aggressive rehabilitation in the early postoperative period is unwise since the proximal tibia is weakened by the oblique osteotomy. Early weight-bearing and unrestricted activity have caused fractures in a few patients. Even late in the postoperative period the osteotomy may adversely influence the biomechanical properties of the proximal tibia.

We describe two athletes who sustained a fracture of the proximal tibia, during recreational activities, six months after a Fulkerson osteotomy. Both had been bearing full weight for about ten weeks without complaint. Bony healing of the osteotomy had been demonstrated on plain radiographs at ten and at 12 weeks. After a Fulkerson osteotomy, jogging and activities which impose considerable impact force should be discouraged for at least nine to 12 months.


The Journal of Bone & Joint Surgery British Volume
Vol. 82-B, Issue 7 | Pages 1059 - 1064
1 Sep 2000
Rupp S Seil R Kohn D Müller B

Our aim was to analyse the effect of avascularity on the morphology and mechanical properties (tensile strength, viscoelasticity) of human bone-patellar-tendon-bone (BPTB) grafts in vitro. These were harvested at postmortem and stored submerged in denaturated human plasma at a constant pH, pO2, pCO2, temperature and humidity under sterile conditions. Mechanical testing was performed two and four weeks after removal of the graft. The mean ultimate strength was 1085.7 ± 255.8 N (control), 1009.0 ± 314.9 N (two weeks cultured) and 1076.8 ± 414.8 N (four weeks cultured). There was no significant difference in linear stiffness or deformation to failure between the groups. There was a difference in viscoelasticity between the control group and the avascular grafts and the latter had significant lower peak load-to-load ratios after 15 minutes compared with the control group. After two and four weeks the graft contained viable fibroblasts. There was regular cellularity in the superficial layers and decreased cellularity in the midportion. The structure of the collagen including the crimp pattern appeared to be normal in polarised light.

We conclude that avascularity does not significantly affect ultimate failure loads or stiffness of BPTB grafts. Slight changes in viscoelasticity were induced, but the significance of the increased stress relaxation is not fully understood.