Introduction

We studied free (= local powder) tobramycin and doxycycline, and controlled release (= local lipid bilayer) doxycycline formulations in a rat model representing a generic joint infection. We hypothesized that evidence of infection (quantitative colony forming units (CFU), qualitative SEM, histopathology) (1a) would be reduced with local vs. systemic antibiotic, (1b) any antibiotic would be superior to control (2) there would be a difference among antibiotics, and (3) antibiotic would not be detectable in serum at 4-week euthanasia.

Removal of a long cement mantle that is well fixed distally during total hip revision can be a technically demanding procedure with many potential complications.

The extended femoral slot offers a technique that allows direct visualisation during cement removal while maintaining an intact femoral tube.

The proximal end of the femur is exposed taking care to remove all soft tissue that might prevent removal of the loose femoral component. The loose femoral component is removed using thin osteotomes and a femoral extraction device as needed. The proximal cement mantle is removed under direct vision to the level of the flare of the greater trochanter. The outside of the femoral shaft below the flare of the greater trochanter is exposed by splitting the vastus lateralis. Pre-operative measurements are imperative to determine the distal level of the cement mantle. An extended rectangular slot approximately 1.5cm wide is made in the anterolateral aspect of the femur starting just below the flare of the greater trochanter and continuing to the level of the distal aspect of the cement mantle. This can be done using a pencil-tipped burr on the Midas Rex or an oscillating saw. The rectangular strip of bone is removed and saved to be replaced and secured with cerclage technique during closure.

The entire cement mantle is removed under direct vision using osteotomes and other cement removing instruments as needed. The opened femoral canal is then reamed to accept a new revision femoral component.

The extended femoral slot is a safe and effective technique for cement removal during revision hip arthroplasty in selected cases. It is not used when there is varus deformity of the proximal femur but in selected cases is an alternative to the extended greater trochanteric osteotomy and preserves the circumference of the femoral tube.

To properly care for femoral neck fractures, the surgeon must decide which fractures are to be fixed and which fractures will require a prosthesis. In addition, the type of prosthesis, hemiarthroplasty versus total hip arthroplasty must be selected. Total hip arthroplasty is an option in the active elderly.

The literature supports internal fixation in non-displaced fractures. Current literature supports the fact that ORIF of displaced femoral neck fractures results in failure and re-operation of 20% to 30%. By considering arthroplasty when the patient has multiple co-morbidities including renal disease, diabetes, rheumatoid arthritis and severe osteoporosis the re-operation rate can be reduced significantly. The single most important factor in preventing failure with fixation is an anatomic reduction. A femoral neck fracture left in varus is doomed to failure and re-operation.

A prosthesis should be used in most displaced femoral neck fractures in patients physiologically older than 65. In active elderly patients total hip replacement should be considered. In elderly patients with multiple co-morbidities who are relatively inactive in a nursing home or lower level community ambulators, a hemi-prosthesis should be considered. The decision-making process is always shared with the patient.

When a prosthetic replacement is performed, the low level nursing home or community ambulator who is not expected to live longer than six to seven years is a candidate for a cemented hemi-arthroplasty. Studies report a 25% – 30% re-operation rate in hemi-arthroplasty if the patient survives greater than six to seven years. In the active elderly with little co-morbidity, a total hip replacement should be used. This is not only cost effective but provides the best pain relief of any of the options for treatment of displaced femoral neck fractures. Treatment of femoral neck fractures remains a challenge but the surgeon must select the proper treatment based on fracture displacement, physiologic age of the patient as well as co-morbidities of the patient.

Periprosthetic fractures are becoming an increasing problem because of the number of total joint replacements that are performed yearly as well as the increase in longevity of the patients that receive total joint replacement. the risk factors for intraoperative fracture are rheumatoid arthritis, cementless arthroplasty, metabolic bone disease, Paget’s Disease, complex deformities, and revisions. The risk factors for post-operative fracture are weakened bone secondary to stress risers, screw holes, cortical perforations and stem tip protrusion, loose implants, and osteolysis. As a general rule the surgeon should make sure that all stress risers such as cortical windows and holes in the diaphysis should be bypassed at least two times the shaft diameter with a longer stem which restores the strength of the shaft to approximately 80%. Areas of transition between stem tips and plates or stem tips and stem tips should be avoided. Cortical strut grafts over holes, windows, and in areas of transition are of value. Johannsen’s Classification with a Type I fracture being proxmial to the tip of the stem, Type II fracture being around the tip of the stem, and Type III fracture distal to the tip of the stem is of value. In a cementless implant the majority of fractures are type I with the minority being Type II and Type III. In periprosthetic fractures with a well fixed prosthesis, the surgeon should maintain the components, restore alignment, and restore function. In periprosthetic fractures with a loose prosthesis, the surgeon should revise the components,restore alignment,and restore function. Treatment options for an intact prosthesis include cerclage wiring in high fractures and the use of plating and allograft struts in lower fractures. With loose implants, treatment options include removal of the implant while maintaining as much bone stock as possible. A loose implant must then be replaced and longer stems and cortical strut grafts are options in the reconstruction. Weight bearing is delayed to allow fracture healing. With this knowledge in hand, the orthopaedic surgeon can anticipate problems and reconstruct bony lesions causing periprosthetic fracture with some confidence in his mechanical constructs.

A new and very unstable intertrochanteric fracture complex is described. The intertrochanteric fracture with extension into the femoral neck is rare but results in an extremely high failure rate because of its instability. A ten-year retrospectic analysis of patients (246) with intertrochanteric fractures treated with a sliding compression hip screw at Hennepin County Medical center was performed. Of these 246 fractures, 20 were classified as fractures with a major intertrochanteric component with extension into the femoral neck. These fractures were similar to intertrochanteric fractures type I-IV described by Kyle and Gustilo in demographics, osteoporosis, and surgical treatment, but this new fracture fracture now described as Type V had a statistically higher rate of mechanical complications 0.0001, reoperation 0.0002, and failure of fixation 0.0001. The overall failure rate was 50%. The majority of these fractures were the result of complete collapse of the hip screw. We feel this higher complication and reoperation rate is secondary to inherent instability in the intertrochanteric fracture which extends into the femoral neck. This instability leads to cmplete collapse of a sliding hip screw result ing in a rigid device that leads to failure of fixation. This fracture complex also has a higher rate of nonunion and avascular necrosis. Although rare, this fracture must be recognized in the fracture classification of intertrochanteric fractures because of its poor prognosis. Other forms of treatment than a sliding hip screw may be considered with this fracture complex because of its high failure rate with standard treatment.

Unreamed, small diameter nails with interlocking capability have become the preferred treatment for most unstable tibial fractures, but have been shown to have a high rate of hardware breakage and frequently require secondary procedures to obtain union. Reamed nailing may offer advantages for fracture healing due to the use of larger implants and increased stability, but may cause higher rates of infection and compartment syndrome. In order to determine if there is a difference in healing or complications in open and closed tibial fractures treated with reamed or unreamed intramedullary nailing, we performed a prospective, surgeon-randomized comparative study. Ninety-four closed and open, unstable tibial shaft fractures (excluding Gustilo Types IIIB and C) treated with intramedullary nailing were studied. Our findings support the use of reamed nailing in closed tibial fractures, which led to earlier time to union without increased complications. In addition, reaming did not increase the risk of complications in open tibial fractures.

Aim: The objective of this study was to compare the initial stability of an uncemented curved long stem femoral component (ABR, Zimmer, Warsaw Indiana) implanted using conventional broaching to an uncemented ABR implanted as a revision using morselized compacted allograft to fill a circumferential proximal bone defect.

Materials and Methods: Primary: Eight fresh frozen human femurs were implanted with correctly sized ABR stems without cement using standard surgical instruments and 1mm distal overreaming. The implant was loaded cyclically at 3 hz on a MTS servohdraulic materials test frame in a direction representing the peak force of the stance phase of the gait (2.5 X body weight). A 3-dimensional motion measurement device with six linear variable transformers measure the relative motion between the bone and the prosthesis with an accuracy of 0.5μm. The contruct was loaded in ten cycle increments until the component was seated and then recoverable motion was recorded over a further ten loading cycles. Revision: In the revision case bone loss was modelled by removing all the cancellous bone from the proximal femur with 1mm distal overreaming. Morselized bone graft was impacted into the defect using specially prepared smooth tamps shaped to the geometry of the ABR stem. The original prosthesis was then reimplanted without the use of cement. The seating and testing cycles were repeated. Primary and revision vectors were compared using a paired students t – test.

Results: There was no statistically significant difference in the magnitude of the resultant vector of the 3 translational components of the micro motion between the two methods of implantation (p=0.19).

Conclusions: Initial stability of a cementless femoral implant is a requirement for bone ingrowth. The use of compacted morsellized allograft in a revision Total Hip Arthroplasty with a proximal circumferential defect can provide a stable bed for the implantation of an uncemented femoral component. The revised implant using the compacted allograft method was initially as stable as the primary implantation.

This technique would be particularly applicable when the surgeon would like to avoid the use of cement in a revision setting. The use of this method for uncemented revision Total Hip Arthroplasty should be studied further in a clinical setting before it is advocated for widespread use.