Therefore, femoral offset restoration is essential to improve function and longevity of hip arthroplasty. CT-scan is more accurate than plain radiography to assess femoral offset. Hip resurfacing decreases offset without effect on function. Modular neck and computer assistance may improve intraoperative calculation and reproduction of femoral offset. Increasing offset with a standard cemented design may decrease long-term fixation. Level IV: Retrospective or historical series.

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Numerous surgical techniques have been developed to treat osteochondral defects of the knee. A study reported encouraging outcomes of third-generation autologous chondrocyte implantation achieved using the solid agarose-alginate scaffold Cartipatch 1 . Whether this scaffold is better than conventional techniques remains unclear. This multicenter randomized controlled trial compared 2-year functional outcomes (IKDC score) after Cartipatch 1 versus mosaicplasty in patients with isolated symptomatic femoral chondral defects (ICRS III and IV) measuring 2.5-7.5 cm 2 . In addition, a histological evaluation based on the O'Driscoll score was performed after 2 years. We needed 76 patients to demonstrate an at least 10-point subjective IKDC score difference with a ¼ 5% and 90% power. During the enrolment period, we were able to include 55 patients, 30 of them were allocated at random to Cartipatch 1 and 25 to mosaicplasty. After 2 years, eight patients had been lost to follow-up, six in the Cartipatch 1 group, and two in the mosaicplasty group. The baseline characteristics of the two groups were not significantly different. The mean IKDC score and score improvement after 2 years were respectively 73.7 AE 20.1 and 31.8 AE 20.8 with Cartipatch 1 and 81.5 AE 16.4 and 44.4 AE 15.2 with mosaicplasty. The 12.6-point absolute difference in favor of mosaicplasty is statistically significant. Twelve adverse events were recorded in the Cartipatch 1 group against six in the mosaicplasty group. After 2 years, functional outcomes were significantly worse after Cartipatch 1 treatment compared to mosaicplasty for isolated focal osteochondral defects of the femur. ß

Objective: The clinical outcome of a total knee arthroplasty.(TKA) is maidy determined by the accuracy of the surgical procedure itself. T o improve the final result, one must take into account (a) the alignment of the prosthesis with respect to the mechanical axis, and (b) the balance of the soft tissues. Therefore, morphologic data (such as the shape of the epiphysis) and geometric data are essential. We present a new method for performing TKA based on morphologic and geometric data without preoperative images. Materials and Methods: The global method is based on the digitization of points with an optical 3D localizer. For the morphologic acquisitions, we use a method based on the registration of sparse point data with a 3D statistical deformable model. T o build the mechanical axis, we use a kinematics method for the hip center and digitization of anatomical landmarks for the ankle centers. The knee center is not determined by digitization or kinematics of the knee, as this would not be accurate. The surgical planning relies totally on the soft-tissue balance, which is the key issue for a good kinematics result. Results: We have used this system for 6 months in a randomized clinical mal involving 35 patients to date. For the first 11 patients that could be measured in the navigation group, the postoperative frontal alignment was within the range of 180 & 3". Fluoroscopic assessment of the soft-tissue balancing will be performed at the conclusion of an extended 2-year study to evaluate the results from a functional point of view. Conclusion: Bone Morphing is an accurate, fast, and user-friendly method that can provide morphologic as well as geometric data. We have introduced the important notion of soft-tissue balancing into the intraoperative planning step to optimize the kinematics as well as the anatomy. Therefore, this method should be considered as an alternative to the CT-based method. Comp Aid Surg 7:156-168 (2002). 02002 WiIey-Liss, Inc.

The goal of ligament balancing in total knee arthroplasty (TKA) is to distribute the tibiofemoral compressive forces symmetrically between the medial and lateral compartments of a well-aligned prosthetic knee, as well as to reestablish a rectangular and identical tibiofemoral gap in both flexion and extension. Nowadays, the proper alignment of knee mechanical axis and the perfect equalization of flexion and extension gaps are ensured by computer-assisted TKA (CATKA). Nevertheless, any residual imbalance of collateral ligaments at the time of surgery can lead to an excessive imbalance in the postoperative period during the weight-bearing activities, which subject the knee collateral ligaments to increased loading. This in turn leads to an accelerated polyethylene wear, and consequently, to early failure of TKA. The instrumented tibial implant proposed in this study can postoperatively assess and monitor the progression of residual postoperative ligament imbalance of a prosthetic knee, which is perfectly aligned during the surgery thanks to CATKA, via a center-of-pressure (COP)-based approach. This approach depends on the measurement of relative displacement of COP position during the postoperative period with respect to a reference position recorded at the beginning of this period. This measurement is performed for six predetermined flexion angles representative of an entire gait cycle. The tibial implant can also generate the electrical power in addition to their role in monitoring the COP position thanks to the piezoceramics embedded within the tibial tray to achieve this twofold task. Experimental and finite-element analysis (FEA) studies have been conducted to validate the methodology used for the postoperative assessment of residual knee laxity. The issues concerning electrical energy generation and data transmission will be thoroughly discussed in another paper.

The goal of our paper is to quantify the electrical energy that can be harvested within a new generation of instrumented knee implant during normal walking. This generation of knee implant is proposed to assess the in vivo anteroposterior and mediolateral distributions of tibiofemoral force on the tibial baseplate without the need to be powered from an external source of energy. The proposed self-powered diagnostic knee implant can provide the clinicians with useful information on the sagittal and coronal instabilities of the prosthetic knee throughout its lifespan. Four piezoelectric elements were embedded within the anteromedial, posteromedial, anterolateral, and posterolateral compartments of the tibial baseplate. These elements can simultaneously be used to sense the force distribution and generate the electric power needed to supply the acquisition, processing, and transmission system located in the stem of the implant. In order to study the power generation issue, OrCAD/PSpice and MATLAB/Simulink models of the piezoelectric element have been developed to quantify the electrical energy harvested under operating conditions close to those encountered in vivo during normal walking. Furthermore, an experimental prototype of the self-powered diagnostic knee implant has been designed, developed, and tested in our laboratory (LaTIM, INSERM U650, Brest, France) in order to validate the modeling results. Index Terms-Piezoelectric energy harvesters, postoperative instability, self-powered sensors, total knee replacement. I. INTRODUCTION A. Motivation D URING total knee arthroplasty (TKA), two key issues must be addressed: the mobility and the stability of the knee joint. The bone removal performed at the time of surgery to allow the implantation of the prosthetic replacement leads to complete loss of the articular conformity. This conformity Manuscript

This new standardized molecular test showed a lack of detection when the bacterial inoculum was low (number of positive media per sample and number of colonies per media) but can be useful when patients have received antibiotic therapy previously.