Purpose. The purpose of this study was to evaluate the results of modular revision stems, uncemented fluted, tapered to treat periprosthetic femoral (PFF) fracture; we specifically evaluated fracture union, implant stability, patient outcomes, and complications to compare the differences between cemented and cementless primary stem. Materials and Methods. We retrospectively reviewed 56 cases of unstable periporsthetic femoral fracture (forty B2 and sixteen B3) treated with the uncemented fluted and tapered modular distal fixation stem with or with or without autogenous bone graft. Clinical outcomes were assessed with Harris Hip Score and WOMAC score. Radiologic evaluations were conducted using Beals and Tower's criteria. Any complication during the follow-up period was recorded. Results. The average follow-up period was 52.1±32.7 months. The average Harris Hip Score was 72.4±19.1. All fractures were united, and a good consolidation was achieved in 47 cases. There was femoral stem subsidence in 3 cases less than 10 mm without an evidence of loosening both radiologically and clinically. The radiologic results using Beals and Towers’ criteria were excellent in 36 hips, good in 10 hips and poor in 10 hips. Radiologic bone union took longer time and statistically significant stem subsidence was observed in cemented primary stem compared to cementless primary stem (Fig1,2). At each follow-up examination the clinical score was significantly higher in patients with cementless primary stem. Conclusion. Our results support the view that cement primary stem has less favorable result in terms of revision arthroplasty for periprosthetic femoral fractures

Modern modular revision stems employ tapered conical (TCR) distal stems designed for immediate axial and rotational stability with subsequent osseo-integration of the stem. Modular proximal segments allow the surgeon to achieve bone contact proximally with eventual ingrowth that protects the modular junction. The independent sizing of the proximal body and distal stem allows for each portion to obtain intimate bony contact and gives the surgeon the ability precisely control the femoral head center of rotation, offset, version, leg length, and overall stability. The most important advantage of modular revision stems is versatility - the ability to manage ALL levels of femoral bone loss (present before revision or created during revision). Used routinely, this allows the surgeon to quickly gain familiarity with the techniques and instruments for preparation and implantation and subsequently master the use for all variety of situations. This also allows the operating room staff to become comfortable with the instrumentation and components. Additionally, the ability to use the stem in all bone loss situations eliminates intra-operative shuffle (changes in the surgical plan resulting in more instruments being opened), as bone loss can be significantly under-estimated pre-operatively or may change intra-operatively. Furthermore, distal fixation can be obtained simply and reliably. Paprosky 1 femoral defects can be treated with a primary-type stem for the most part. All other femoral defects can be treated with a TCR stem. Fully porous coated stems also work for many revisions but why have two different revision stem choices available when the TCR stems work for ALL defects?. The most critical advantage is the ability to separate completely the critical task of fixation from other important tasks of restoring offset, leg length, and stability. Once fixation is secured, the surgeon can concentrate on hip stability and on optimization of hip mechanics (leg length and offset). The ability to do this allows the surgeon to maximise patient functionality post-operatively. Modular tapered stems have TWO specific advantages over monolithic stems in this important surgical task. The proximal body size and length can be adjusted AFTER stem insertion if the stem goes deeper than the trial. Further, proximal/distal bone size mismatch can be accommodated. The surgeon can control the diameter of the proximal body to ensure proper bony apposition independent of distal fitting needs. If the surgeon believes that proximal bone ingrowth is important to facilitate proximal bone remodeling, modular TCR stems can more easily accomplish this. The most under-appreciated advantage is the straightforward instrumentation system that makes the operation easier for the staff and the surgeon, while enhancing the operating room efficiency and reducing cost. Also, although the implant itself may result in more cost, most modular systems allow for a decrease in inventory requirements, which make up the cost differential. One theoretical disadvantage of modular revision stems is modular junction fracture, which can happen if the junction itself is not protected by bone. Ensuring proximal bone support can minimise this problem. Once porous ingrowth occurs proximally, the risk of junction fracture is eliminated. Even NON-modular stems fracture when proximal bone support is missing. Another theoretical issue is modular junction corrosion but this not a clinical one, since both components are titanium. One can also fail to connect properly the two parts during surgery

The most important advantage of modular revision stems is versatility - managing ALL levels of femoral bone loss (present before revision or created during revision). The surgeon quickly gains familiarity with the techniques and instruments for preparation and implantation and subsequently masters its use for all variety of situations. This allows the operating room staff to become comfortable with the instrumentation and components. This ability to use the stem in a variety of bone loss situations eliminates intraoperative shuffle (changes in the surgical plan resulting in more instruments being opened), as bone loss can be significantly under-estimated preoperatively or may change intraoperatively. Furthermore, distal fixation can be obtained simply and reliably. The most critical advantage is the ability to separate completely the critical task of fixation from other important tasks of restoring offset, leg length, and stability. Once fixation is secured, the surgeon can concentrate on hip stability and on optimization of hip mechanics (leg length and offset). This allows the surgeon to maximise patient functionality postoperatively. Additionally, the surgeon can control the diameter of the proximal body to ensure proper bony apposition, especially if an extended trochanteric osteotomy was made to obtain femoral exposure. The most under-appreciated advantage is the straightforward instrumentation that makes the operation easier for the staff and the surgeon, while enhancing the operating room efficiency and reducing cost. Also, although the implant itself may result in more cost, most modular systems allow for a decrease in inventory requirements, which make up the cost differential

Introduction. The success of cementless total hip arthroplasty (THA), primary as well as for revision, largely depends on the initial stability of the femoral implant. In this respect, several studies have estimated that the micromotion at the bone-implant interface should not exceed 150µm (Jasty 1997, Viceconti 2000) in order to ensure optimal bonding between bone and implant. Therefore, evaluating the initial stability through micromotion measurements serves as a valid method towards reviewing implant design and its potential for uncemented THAs. In general, the methods used to measure the micromotion assume that the implant behaves as a rigid body. While this could be valid for some primary stems (Østbyhaug 2010), studies that support the same assumption related to revision implants were not found. The aim of this study is to assess the initial stability of a femoral revision stem, taking into account possible non-rigid behaviour of the implant. A new in vitro measuring method to determine the micromotion of femoral revision implants is presented. Both implant and bone induced displacements under cyclic load are measured locally. Methods. A Profemur R modular revision stem (MicroPort Orthopedics Inc. Arlington, TN, United States of America) and artificial femora (composite bone 4th generation #3403, Sawbones Europe AB, Malmö, Sweden) prepared by a surgeon were used. The micromotions were measured in proximal-distal, medial-lateral or anterior-posterior directions at four locations situated in two transverse planes, using pin and bushing combinations. At each measuring location an Ø8mm bushing was attached to the bone, and a concentric Ø3mm pin was attached to the implant [Fig.1 and 2]. A supporting structure used to hold either guiding bushings or linear variable displacement transducers (LVDT) is attached to the proximal part of the implant. The whole system was installed on a hydraulic force bench (PC160N, Schenck GmbH, Darmstadt, Germany) and 250 physiological loading cycles were applied [Fig.3]. Results. By combining the local bone and implant displacements, the relative average micromotion appeared to be less than 25µm in the proximal region and less than 50µm in the distal region. These data correspond to a regular implant-bone fit. Also the micromotion is on average larger in the medial-lateral plane than in the posterior-anterior plane. If the implant deformations were not taken into account then the average values for micromotion were overestimated up to 20µm at proximal levels, and up to 140µm at distal levels. Conclusion. Good initial stability is achieved in each case, suggesting a successful long-term outcome. These findings are consistent with a success rate of 96% reported for the used implant over an average of 10 years (Köster 2008). To adequately evaluate the initial stability of femoral implants, the non-rigid behaviour cannot be ignored. Acknowledgments. This research is supported by BVOT (Belgian Association for Orthopaedics and Traumatology) and Impulse Fund KU Leuven