[Proximal tibia fracture treatment with a new locking device with polyaxial screw placement: technique and early results]. / Frakturversorgung an der proximalen Tibia mit einem neuartigen winkelstabilen Implantat mit polyaxialer Schraubenplatzierung: Technik und erste Ergebnisse.

BACKGROUND: Surgical treatment of tibial head fractures can be challenging due to the close anatomic relationship to the knee joint which can be affected including its intraarticular structures. Frequently, soft tissue damages are present which can have a strong impact on the planning and choice of surgical technique. An important therapeutic requirement is the anatomic reconstruction and high primary stability to allow early functional treatment. The aim of the present study was to describe a recent locking device and its surgical technique and to analyse the early results. MATERIAL AND METHODS: The Non-Contact-Bridging Plate for the proximal tibia (NCB® PT, Zimmer Inc.) features a polyaxial locking mechanism which allows both compression and locking with the same screw. The system can be applied both minimally invasively and open. 36 patients (16 female, 20 male; average age 53 years) with three type A, 21 type B and 12 type C fractures according to the AO classification were treated. In 22 cases the system was applied open and in 14 minimally invasively. Clinical and radiological follow-up was obtained at 6 weeks, 3, 6 and 12 months. RESULTS: The handling of the system turned out to be straightforward after an initial learning curve. Implant failure was not detected in our sample. The minimally invasive technique can be beneficial in cases of severe soft tissue damage, but must not compromise the quality of reduction. The functional result at 1-year follow-up using a knee score was good or very good and comparable to the literature. The rate of general surgical complications was 11 % (haematoma, superficial or deep wound infection). Implant-related complications were not detected. At the 3-months' follow-up 44 % and at the 12-months' 100 % of the fractures were healed on X-ray. CONCLUSION: The NCB PT plate offers a broad variety of treatment options due to the specific locking mechanism and the fact that it can be applied both minimally invasively and open. In cases of intraarticular involvement the application of compression and locking with the same screw turned out to be very beneficial. The primary stability of the system allows early functional treatment. Clinical results and complication rates of the present study are comparable to those in the literature.

[Clinical evaluation of PFNA® and relationship between the tip-apex distance and mechanical failure]. / Klinische Evaluation des PFNA® und Zusammenhang zwischen Tip-Apex-Distanz und mechanischem Versagen.

The incidence of trochanteric fractures is increasing in Europe, and the economic impact and mortality is high. The aim of the study was to evaluate the PFNA® (proximal femoral nail antirotation) with respect to its clinical use and mechanical complications.All patients with a trochanteric fracture who had been treated with a PFNA® between 12/2004 and 12/2007 were identified and analysed regarding complications and radiological findings. The study included 195 patients; 61.2% of the patients were classified as Singh I und II. The mean duration of surgery was 57 min. In ten cases (5.1%) the blade migrated, four cases (2.1%) showed blade cut out and in one case the nail broke (0.5%). The mean TAD was 26.7 mm, in cases of cut out 41.3 mm and in blade migrations 38.6 mm. No failure could be documented when the TAD was less then 30 mm. There is a strong relationship between increasing TAD and mechanical failure (P<0.001); 84.6% of the patients have been followed up, and 30.2% died in the follow-up period.The PFNA® is an easy-to-use implant for the treatment of stable and instable proximal femur fractures. Mechanical failure depends on the TAD.

[Biomechanical evaluation of biointegrable suture anchors composed of bovine compact bone in a pull-to-failure test in porcine tibial head specimens]. / Biomechanische Untersuchungen zur Fixationsfestigkeit von Fadenankern aus boviner Kompakta (CB-Anker) in porciner Tibiakopfspongiosa im Ausreissversuch.

AIM: Suture anchors of various designs have gained wide acceptance for securing soft tissues to bone. The biointegrable Tutofix CB anchors derived from bovine compact bone are available with diameters of 3 mm (CB3 anchor), 4 mm (CB4 anchor) and 5 mm (CB5 anchor). The CB anchors are push-in anchors and, from the biomechanical standpoint, they are a combination of press-fit and angulation anchors. The purpose of this study was to evaluate the CB anchors for singular pull load-to-failure strength using porcine tibial head specimens as a test model. METHODS: In all specimens, the joint surface was removed by performing a subchondral osteotomy. Axial PQ-CT scans of 12 specimens were obtained to determine the trabecular BMD. The anchors were implanted posteromedially and centrolaterally in the porcine tibial head specimens. After threading the anchors with a steel suture and predrilling of the anchor holes perpendicular to the osteotomy surface they were inserted 4 mm below the osteotomy surface. A universal testing machine applied tensile loads parallel to the axis of insertion at rates of 10 mm/min and 500 mm/min until pull-out failure or anchor breakage and mean anchor fixation strengths were calculated. RESULTS: The fixation strength of the CB anchors was found to be much higher at the dorsomedial implantation site than at the centrolateral implantation site. The CB4 anchors and CB5 anchors provided nearly the same fixation strength at a level much higher than that of the CB3 anchors. Bone mineral density had a strong influence on axial pull-out force of the anchors, especially the CB4 anchors and CB5 anchors. The overall correlation coefficient for bone mineral density with ultimate load-to-failure was 0.869 for the CB4 anchors and 0.716 for the CB5 anchors. Differences in failure strengths were also seen between the low and high extraction rates. With the high extraction rate much higher failure strengths were obtained than with the low extraction rate. The sudden pull eccentrically on the anchors caused a better fixation due to angulation of the anchor within the drill holes. CONCLUSION: In spite of the double worst-case scenario in the testing conditions, the CB anchors provided a high fixation strength in the trabecular bone of porcine tibial head specimens with the CB4 anchors and CB5 anchors being nearly equal and both being superior to the CB3 anchors. Bone mineral density had a strong influence on the axial pull-out force. Our results show that the CB anchors seem to be a reasonable alternative to metal and bioabsorbable suture anchors.