A long nail is often recommended for treatment of complex trochanteric fractures but requires longer surgical and fluoroscopy times. A possible solution could be a nail with an appropriate length which can be locked in a minimally invasive manner by the main aiming device. We aimed to determine if such a nail model* offers similar structural stability on biomechanical testing on artificial bone as a standard long nail when used to treat complex trochanteric fractures. An artificial osteoporotic bone model was chosen. As osteosynthesis material two cephalomedullary nails (CMN) were chosen: a superior locking nail (SL-Nail) which can be implanted with a singular targeting device, and a long nail (long-nail) with distal locking using free-hand technique. AO31-A2.2 fractures were simulated in a standardized manner. The insertion of the nail was strictly in accordance with the IFU and surgical manual of the manufacturer. The nail was locked dynamically proximally and statically distally. Axial height of the construct, varus collapse, and rotational deformity directly after nail insertion were simulated. A Universal Testing Machine was used. Measurements were made with a stereo-optic tracking system. Reactive movements were recorded and evaluated in all six degrees of freedom. A comparative analysis provided information about the stability and deformation of the assemblies to be compared.Introduction
Method
Overviewing the literature, pain and redislocation after surgical treatment of patellofemoral instability (PFI) is described with up to 30 %, especially with techniques involving the extensor mechanism, the lateral retinaculum or the medial vastus. However, outcome data about revision surgery is missing. Therefore, it was the purpose of this prospective study to evaluate the clinical outcome after revision surgery with an isolated or a combined reco. of the medial patellofemoral ligament (MPFL) with a follow up of 12 months. The indication for additional procedures such as distal femoral osteotomies (DFO), trochleoplasty, reclosing of the lateral retinaculum (RLR) or lateralisation of the tuberosity (LT) were performed depending on the clinical and radiological pathomorphologies. In between 3/07–4/09, 42 pat. with a mean age of 24 years (13–46ys) were revised due to persistent PFI after mean 1.8 failed previous operations (lateral release, medial gather/VMO-distal., medial. of the tuberosity) in our department. An isolated reco. of the MPFL was performed in 15 cases, while a combination with a DFO due to massive femoral axis deformity (n=5), trochleoplasty due to a convex trochlear morphology (n=1) and/or LT (n=4) and/or RLR due to medial instability or lateral pain (n=22) was done in 27 cases. The clinical result was evaluated by the pre- and postop. IKDC/Kujala/Tegner-score and by a subjective questionnaire. Radiologically, the patellashift/-tilt/-height and level of the eventual degeneration were defined preop. and at the point of follow up with the help of straight lateral radiographs and by MRI. Significance level was set at p=.05, statistical calculation was done by the use of the t-test.Objective
Methods
