In recent years, cementless stems have dominated the North American market. There are several categories of cementless stems, but in the past 20 years, the two most popular designs in the United States have been the extensively coated cylindrical cobalt-chrome (Co-Cr) stem and the proximally coated tapered titanium stem, which in recent years has become the most common. The 10 year survival for both stem types has been over 95% with a distinction made on factors other than stem survival, including thigh pain, stress shielding, complications of insertion, and ease of revision. Conventional wisdom holds that proximally coated titanium stems have less stress shielding, less thigh pain, and a higher quality clinical result. Recent studies, however, including randomised clinical trials have found that the incidence of thigh pain and clinical result is essentially equivalent between the stem types, however, there is a modest advantage in terms of stress shielding for a tapered titanium stem over an extensively coated Co-Cr stem. One study utilising pain drawings did establish that if a Co-Cr cylindrical stem was utilised, superior clinical results in terms of pain score and pain drawings were obtained with a fully coated versus a proximally coated stem. In spite of the lack of a clinically proven advantage in randomised trials, tapered titanium stems have been favored because of the occasional occurrence of substantial stress shielding, the increased clinical observation of thigh pain severe enough to warrant surgical intervention, ease of use of shorter tapered stems that involve removal of less trochanteric bone and less risk of fracture both at the trochanter and the diaphysis due to the shorter, and greater ease of insertion through more limited approaches, especially anterior approaches. When tapered stems are utilised, there may be an advantage to a more rectangular stem-cross-section in patients with type C bone. In spite of the numerous clinical advantages of tapered titanium stems, there still remains a role for more extensively coated cylindrical stems in patients that have had prior surgery of the proximal femur, particularly for a hip fracture, which makes proximal fixation, ingrowth, and immediate mechanical stability difficult to assure consistently. Cement fixation should also be considered in these cases. While the marketplace and the clinical evidence strongly support routine use of tapered titanium proximally coated relatively short stems with angled rather than straight proximal lateral geometry in the vast majority of cases, there still remains a role for more extensively coated cylindrical and for specific indications.

INTRODUCTION

The Woodpecker pneumatic broaching system facilitates femoral preparation to achieve optimal primary fixation of the stem in direct anterior hip replacement using a standard operating table. The high-frequency axial impulses of the device reduce excess bone tension, intraoperative femoral fractures and overall operating time. The Woodpecker device provides uniformity and enhanced control while broaching, optimizing cortical contact between the femur and implant and thereby maximizing prosthetic axial stability and longevity. This study aims to describe a single surgeon's experience using the Woodpecker pneumatic broaching system in 649 cases of direct anterior approach (DAA) total hip arthroplasties to determine the device's safety and efficacy.

Introduction. In cementless THA the incidence of intraoperative fracture has been reported to be as high 28% [1]. To mitigate these surgical complications, investigators have explored vibro-acoustic techniques for identifying fracture [2–5]. These methods, however, must be simple, efficient, and robust as well as integrate with workflow and sterility. Early work suggests an energy-based method using inexpensive sensors can detect fracture and appears robust to variability in striking conditions [4–5]. The orthopaedic community is also considering powered impaction as another way to minimize the risk of fracture [6– 8], yet the authors are unaware of attempts to provide sensor feedback perhaps due to challenges from the noise and vibrations generated during powered impaction. Therefore, this study tests the hypothesis that vibration frequency analysis from an accelerometer mounted on a powered impactor coupled to a seated femoral broach can be used to distinguish between intact and fractured bone states. Methods. Two femoral Sawbones (Sawbones AB Europe, SKU 1121) were prepared using standard surgical technique up to a size 4 broach (Summit, Depuy Synthes). One sawbone remained intact, while a calcar fracture approximately 40mm in length was introduced into the other sawbone. Broaching was performed with a commercially available pneumatic broaching system (Woodpecker) for approximately 4 secs per test (40 impactions/sec) with hand-held support. Tests were repeated 3 times for fractured and intact groups as well as a ‘control’ condition with the broach handle in mid-air (ie not inserted into the sawbone). Two accelerometers (PCB M353B18) positioned on the femoral condyle and the Woodpecker impactor captured vibration data from bone-broach-impactor system (Fig1). Frequency analysis from impaction strikes were postprocessed (Labview). A spectrogram and area under FFT (AUFFT) [4] were analysed for comparisons between fractured and intact bone groups using a nested ANOVA. Results. Vibration frequency patterns between respective groups were best observed using an accelerometer positioned on the impaction device rather than on a sawbone (fig1). Qualitative assessment revealed that spectrograms showed no obvious difference for characteristic vibration frequencies between intact and fractured bone groups. A frequency signal at approximately 10kHz was absent for control impactions but present with bone impactions (Fig2). Quantitative assessment revealed AU-FFT was noticeably higher for intact bone groups than fractured bone groups for sampled impactions using a nested experimental design for statistics (p=0.11). Discussion. Our pilot study demonstrates that application of powered impaction combined with vibration frequency analysis has the potential to distinguish between an intact and fractured sawbone in a way that minimises instrumentation footprint and complexity of workflow in OR with a new generation of impaction device targeted at reducing and detecting bone fractures. Further investigation should validate these methods by evaluating the variation with sawbones and simulated bone fractures

Introduction:. Purpose of mini-invasive hip arthroplasty, is least damage to skin and muscles. Unlike Roettinger modification to Watson-Jones, our approach requires no special table or instruments. Besides, direction of skin incision is perpendicular to interval between glutei and tensor muscles, thus called a Crisscross Approach. Incision is at direction of retractors causing less skin damage; and parallel to femur allowing expansion. No tendon or muscles are severed achieving a true inter-muscular non invasive approach. Unlike anterior approach, femoral circumflex vessels and lateral femoral cutaneous nerve are spared. Material and Methods:. 240 prospective patients underwent mini-invasive crisscross technique since December 2006. A standard non-cemented hip was implanted. Previously disrupted hip muscles patients were excluded. In the operating room, patients were secured in a lateral decubitus position with the pelvis flexed at 20°–30° to allow operated leg to extend beyond the table to be placed in a standard plastic bag. The anterior superior iliac spine (ASIS), the greater trochanter (GT) and its tubercle are identified and marked. A line is drawn between ASIS and GT tubercle representing the interval between the glutei and the tensor fascia lata muscles. Another line representing the skin incision is drawn perpendicular. It may be curved a little toward the femur starting two inches inferior and posterior to ipsilateral ASIS extending distally for 3 inches or more for obese or muscular patients. The Crisscross Approach starts with a skin incision being made as above and through the subcutaneous fat identifying the inter-muscular interval between the glutei and the tensor fascia lata. Sharp dissection is made in the connecting fascia only and blunt dissection is needed to separate the two muscles. A branch of the superior gluteal nerve proximally crossing from the glutei to the tensor fascia lata may be encountered but it should not be disturbed as long as blunt dissection is maintained. Curved retractors are placed one above and the other below the femoral neck exposing the anterior capsule. Incision is made in the capsule and the retractors are re-placed to better expose the femoral neck. The appropriate level of neck is osteotomized and the head is extracted as routine. Acetabulum is further exposed by placing the curved retractors at about mid anterior and mid posterior. The final appropriate cup size and orientation is implanted routinely. Before exposing the femoral canal the deep fascia at the junction of the glutei and the vastus lateralis should be incised (about 2–3 inches). This will tremendously help femoral canal exposure. Then the surgeon is positioned anterior, the patient is made fully paralyzed and the table is tilted 20°–30° posteriorly (away from the surgeon). Hip extended 20°–30°, externally rotated to 80°–90° and adducted with a retractor underneath femoral neck and a curved one on greater trochanter to protect the glutei. Leg is allowed to drop in a bag (posteriorly). Canal finder is helpful to avoid going through the cortex Broaching or reaming and final implant insertion as routine. Posterior capsule need not be disturbed; however, the superior and inferior capsule should be detached from the neck to allow better exposure of the femoral canal. Closure starts with one or two stitches in the remainder of the capsule. Then suture deep fascia at the junction of glutei and vastus lateralis with absorbable suture. Finally, subcutaneous fat and skin are closed as routine. Results:. There was no major neurovascular damage or complications related to this exposure. Follow up to a maximum of 75 months revealed no deep infection and no dislocation or fracture. We undersized three stems at the beginning but that did not require re-operation. Surgery time averaged 15 minutes longer but that was reduced as we gained experience. Cup position was navigated and postoperative CT scan confirmed satisfactory cup and stem position. One case that had an undersized prosthesis settling to about half an inch short which required a 3/8 inch insole for the patient to wear. Rehab goals were met after 4–6 sessions in all patients. Patients were allowed to go home on two crutches in 2–3 days. Full weight bearing was allowed in 2–4 weeks. No limping noted at 3 months follow up. Discussion:. Crisscross approach differs by transecting no tendon or muscles, requiring no special table or instruments with incision parallel to femur facilitating expansion and reducing skin damage resulting in true non-invasive approach