Risk of periprosthetic femur fracture after anterior cortical bone windowing: a mechanical analysis of short versus long cemented stems in pigs.

BACKGROUND AND PURPOSE: Removal of distal cement at femoral implant revision is technically challenging and is associated with complications such as cortical perforations. A technique that can reduce the risks and operating time is to make a small cortical window in the distal femur for enhanced access. We wanted to determine whether the use of long, bridging, cemented femoral stems is necessary to reduce the risk of postoperative periprosthetic fractures after using an anterior cortical bone window. METHODS: 66 fresh pig femurs underwent mechanical testing. Steel rods were implanted at 3 locations: (1) at the distal window edge, (2) 15 mm proximally to the cortical window edge, and (3) 15 mm distally. 54 femurs were tested using a 3-point bending setup and 12 femurs were tested using a torsional load setup. RESULTS: Load to fracture ratio and bending stiffness ratio were similar in the 3 groups, for either the 3-point bending test or the torsional load test. INTERPRETATION: Our findings suggest that bypass of cortical windows with a revision femoral component may not reduce the risk of periprosthetic fracture.

Revision total knee arthroplasty: clinical outcome comparison with and without the use of femoral head structural allograft.

The use of femoral head structural allograft (FHSA) for the management of massive bony defects during revision total knee arthroplasty (TKA) is well documented in the literature. The purpose of this study was to compare the clinical outcomes of patients undergoing revision (TKA) with FHSA to those without. All patients undergoing revision TKA between January 2000 and August 2005 were reviewed. Two cohorts were generated: a study cohort--revision TKA using FHSA (n = 24)--and control cohort--revision TKA without FHSA (n = 48). The 2 study cohorts groups were comparable. All patients completed validated outcome questionnaires. The FHSA cohort was found to have significantly better outcome scores. This study demonstrates improved clinical outcomes for patients undergoing revision TKA using a structural allograft compared with those without.

Conversion of hip arthrodesis to total hip arthroplasty: survivorship and clinical outcome.

This study evaluated survivorship and clinical outcomes of patients undergoing conversion of a hip arthrodesis to a total hip arthroplasty (THA) and compared them to 2 patient cohorts: primary THA and first-time revision THA. Patients completed 5 standardized outcome questionnaires. The study cohort was compared to matched groups of primary THA and first-time revision THA patients. Twenty-six patients were identified, 2 deceased and 7 revised, leaving 17 patients available for review. A 10-year survivorship of 74.2% and complication rate of 54% were noted. All outcome scores were lower for the study cohort: clinically significant difference vs revision THA group and statistically significant difference vs primary THA group. Takedown arthrodesis patients experience poor clinical outcomes and high complication rates compared to primary and even revision THA.

Cement-in-cement femoral revision for the treatment of highly selected vancouver B2 periprosthetic fractures.

The use of the cement-in-cement technique for femoral component revisions has been well described. The application of this technique in the management of selected Vancouver B2 periprosthetic femur fractures, after careful preoperative and intraoperative evaluation, offers a novel alternative that is rapid and technically less demanding, with resulting decreased blood loss and decreased risk of iatrogenic fragmentation of bone during cement removal.

Two-stage total hip arthroplasty: how often does it control methicillin-resistant infection?

BACKGROUND: Methicillin-resistant hip infections are increasingly common. Reports of the surgical management of these patients using two-stage THA show variable control of infection, but all reports used static spacers. QUESTIONS/PURPOSES: We therefore determined (1) the rate of successful control of infection and (2) function in patients with methicillin-resistant infection treated with a two-stage THA using an articulated cement spacer during the first stage. METHODS: We retrospectively reviewed 50 patients who had a two-stage revision THA for methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis infection. Twelve patients died, leaving 38 for review. All eligible patients completed quality-of-life outcome questionnaires (WOMAC, SF-12, Oxford-12, UCLA activity score, hip and knee satisfaction score). Minimum followup was 24 months after the second stage (mean, 58 months; range, 24-123 months). RESULTS: Of the 38 patients, eight (21%) had recurrence of their infection requiring further revision surgery. Of the remaining 27 patients, the mean WOMAC was 62, mean Oxford-12 60, mean UCLA activity score 4.3, and mean hip and knee satisfaction score 66. CONCLUSIONS: We found a treatment failure rate of 21% for patients with methicillin-resistant S. aureus or methicillin-resistant S. epidermidis infection. This is a higher rate than reported for two-stage THA for studies including patients infected with both nonresistant and resistant organisms. The functional scores for patients were also lower than those reported in the literature. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Femoral revision hip arthroplasty: a comparison of two stem designs.

UNLABELLED: For various reasons the tapered, fluted, modular titanium (TFMT) stem has become our component of choice over cylindrical, nonmodular cobalt chrome (CNCC) components for THA revision. We therefore asked whether the TFMT femoral components better achieved three important goals of revision arthroplasty than CNCC stems: (1) improving quality of life; (2) avoiding complications; and (3) preserving or restoring femoral bone stock. We compared patients undergoing femoral component revision hip arthroplasty with either a CNCC (N = 105) component or a TFMT (N = 95) component to determine if the increased use of TFMT components is justified. We retrospectively reviewed all patients undergoing revision total hip arthroplasty between January 2000 and March 2006. All eligible patients completed outcome questionnaires (WOMAC, SF-12, Oxford-12, UCLA Activity Score, and Satisfaction Scores). Radiographs were evaluated for loosening and preservation or restoration of the proximal femur host bone. The TFMT and CNCC cohorts were comparable with respect to age, gender, diagnosis, and comorbidities. The TFMT cohort had worse preoperative bone defects (65% Paprosky 3B and 4). The TFMT cohort had higher outcome scores (WOMAC pain, WOMAC stiffness, Oxford-12, and Satisfaction), fewer intraoperative fractures, and better restoration of the proximal femur host bone. Our data suggest the TFMT stem provided improved clinical outcomes (improved quality of life, decreased complications, and preservation of bone stock) than the CNCC stem. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Severe femoral bone loss in infected total hip arthroplasty: surgical management.

The management of severe bone loss in a patient with a chronically infected total hip arthroplasty is a complex surgical challenge. The surgical alternatives are numerous and include the use of allografts, both structural and morcellized; cemented and cementless femoral components; and segmental replacement megaprostheses.

Vancouver type B3 periprosthetic fractures: evaluation and treatment.

Periprosthetic fracture with preexisting severe loss of bone stock is a challenging condition to treat. Available surgical options can be divided into three categories: complex reconstruction of the deficient proximal femur with secure distal fixation; segmental substitution of the proximal femur with a megaprosthesis or allograft/stem composite; and distally fixed replacement with a modular stem, which acts as a scaffold around which the remaining deficient proximal bone can be assembled, to unite and possibly reconstitute.

Distally fixed scaffold technique for the management of Vancouver B3 periprosthetic fractures.

Periprosthetic femoral fractures with associated severe bone loss are challenging problems to treat. High failure rates are reported throughout the literature for the various surgical options. The novel distally fixed scaffold technique is a rapid procedure with reduced blood loss and high versatility that allows early mobilization. Early results have been promising, but further long-term data are required.

Risk of periprosthetic femoral neck fracture after hip resurfacing arthroplasty: valgus compared with anatomic alignment. A biomechanical and clinical analysis.

BACKGROUND: Early clinical results of hip resurfacing arthroplasty have led to the recommendation to achieve a neck-shaft angle of 140 degrees when inserting the femoral component. In addition, the idea of adhering to an absolute angle when inserting instrumentation in hips with excessive anatomic varus or valgus neck-shaft angles has raised concern. A biomechanical analysis was completed in order to determine if the achieved valgus orientation of the femoral component reduced the risk of periprosthetic fracture. METHODS: Twenty fresh-frozen cadaveric femora were blindly assigned to be implanted with a neutral or valgus-oriented hip-resurfacing femoral component. Bone mineral density scans were acquired for all femora. All specimens were loaded axially to failure at a rate of 0.21 mm per second. Radiographs of the specimens were measured in order to determine the relative valgus orientation of the femoral components and the change in offset. RESULTS: There was a significant increase in the ultimate failure load for the valgus-oriented components. While the bone density scans revealed that the bone mineral densities measured in the neutral and valgus-oriented femoral components were almost identical, the ultimate failure load was found to be significantly increased for the valgus-oriented components (6955 N) compared with the neutral-oriented components (5254 N). For the valgus-oriented femoral components, two had failure at the subcapital level, seven had vertical shear fractures, and one had an anterior shear fracture. For the neutral-oriented components, five subcapital fractures and five vertical shear failures were observed. CONCLUSIONS: The study suggests that a valgus orientation decreases the risk of periprosthetic femoral neck fracture following hip resurfacing. It also brings into question the use of an absolute angle for all patients. Obtaining the maximum possible valgus angle, while avoiding notching, may in fact provide the optimum protection from periprosthetic femoral neck fractures.

Surgical nuances to minimize muscle damage during the anterolateral intermuscular approach in minimally invasive hip replacement.

Muscle damage that can occur during minimally invasive total hip replacement is an important concern. Minimizing this iatrogenic injury can help achieve the goals of the minimally invasive approach: decreased postoperative pain, decreased blood loss, and faster rehabilitation. Knowledge of particular aspects of minimally invasive anterolateral total hip arthroplasty is important, with focus on the nuances that aid in reducing muscle injury.