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Biomedical subjects

Aaron G Rosenberg

Publications and source records attributed to Aaron G Rosenberg.

At least 19 recordsLinked to original sources
PubMed2006

Stem diameter and rotational stability in revision total hip arthroplasty: a biomechanical analysis.

BACKGROUND: Proximal femoral bone loss during revision hip arthroplasty often requires bypassing the deficient metaphyseal bone to obtain distal fixation. The purpose of this study was to determine the effect of stem diameter and length of diaphyseal contact in achieving rotational stability in revision total hip arthroplasty. METHODS: Twenty-four cadaveric femoral specimens were implanted with a fully porous-coated stem. Two different diameters were tested and the stems were implanted at multiple contact lengths without proximal bone support. Each specimen underwent torsional testing to failure and rotational micromotion was measured at the implant-bone interface. RESULTS: The larger stem diameter demonstrated a greater torsional stability for a given length of cortical contact (p <or= 0.05). Decreasing length of diaphyseal contact length was associated with less torsional stability. Torsional resistance was inconsistent at 2 cm of depth. CONCLUSION: Larger stem diameters frequently used in revisions may be associated with less diaphyseal contact length to achieve equivalent rotational stability compared to smaller diameter stems. Furthermore, a minimum of 3 cm or 4 cm of diaphyseal contact with a porous-coated stem should be achieved in proximal femoral bone deficiency and will likely be dependent on the stem diameter utilized at the time of surgery.

Journal Article↗
PubMed2006

Clinical performance of contemporary tibial polyethylene components.

A postclinical retrieval analysis was performed on 43 polyethylene tibial components of a contemporary total knee arthroplasty system with implantation duration between 12 and 80 months. Components were scored for 8 potential modes of surface wear or damage on the top and back surfaces. Moderate backside wear of 4.1 microm/y was documented by measuring the extent of manufacturer's engraved lettering removal. Neither the topside nor backside score correlated with duration of in vivo function. No component experienced topside or backside delamination, cracking, or significant deformation. The greatest contribution to wear and damage score was pitting and scratching secondary to bone cement debris. The extent of both wear and damage experienced by these components was moderate, in comparison with that previously reported with older implant systems.

Arthroplasty, Replacement, Knee↗
PubMed2006

What would you do? Challenges in hip surgery.

The panel reviewed cases involving both revision and primary total hip arthroplasties. The panelists are Hugh Cameron and Allan Gross from Toronto, Charles Engh from Arlington, Aaron Rosenberg from Chicago, and Bernard Stulberg from Cleveland. The cases discussed brought up some controversial issues.

Adult↗
PubMed2006

Managing periprosthetic femoral stem fractures.

Periprosthetic fractures can be difficult to manage. The classification system developed in Vancouver is simple and useful in determining appropriate treatment. It takes into account the site of the fracture, the stability of the implant, and the surrounding bone stock, which are the important elements of the fracture and hip that determines treatment. Understanding this classification system should allow the practitioner to choose the appropriate treatment. In addition to fracture management skills, understanding how to perform a host of hip revision technique may also be required.

Arthroplasty, Replacement, Hip↗
PubMed2006

Changing demographics of patients with total joint replacement.

There has been a substantial change in the population demographics of patients who potentially will require total joint replacements. We studied data regarding temporal trends in physical condition, life expectancy, education, and other population demographics of individuals most likely to receive total joint replacements. Changes in this population during the last several decades correlate with temporal changes in the prevalence of joint disease and the incidence of total hip and knee replacements. Compared with several decades ago, patients currently receiving total joint replacements are almost 20% heavier, more physically active, three times more likely to have a high school or college education, and live more than 25% longer. Patients needing total joint replacements are more likely to be female, and twice as likely to receive a total knee replacement than a total hip replacement. Treatment choices and outcome expectations are best determined with accurate knowledge of current surgical science and current patient demographics. Therefore, it is important to realize that today's population most likely to receive total joint replacements is demographically different than in the past.

Adult↗
PubMed2006

Surgical exposures in revision total knee arthroplasty.

UNLABELLED: Safely obtaining adequate exposure at the time of revision total knee arthroplasty is an integral step in successfully performing the procedure. A medial capsular approach combined with an extensive intraarticular synovectomy provides adequate exposure for most patients. If further exposure is required, a quadriceps snip can be used to free the proximal extensor mechanism. The benefits of this approach include its technically simple nature and an unaltered postoperative rehabilitation regimen. We report a series of 126 consecutive revision knee procedures in which a medial capsular approach was adequate in 111 cases, representing 92% of the patients with an intact extensor mechanism. A quadriceps snip was required in nine cases. If more extensive exposure is required for an excessively stiff or difficult to expose knee, a tibial tubercle osteotomy or V-Y quadricepsplasty provides wider exposure. LEVEL OF EVIDENCE: Therapeutic study, level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Arthroplasty, Replacement, Knee↗
PubMed2006

Anesthesia and analgesia protocols for total knee arthroplasty.

Uncontrolled pain associated with total knee arthroplasty can have significant untoward effects on patient outcomes, leading to delayed recovery, inability to participate in rehabilitation, prolonged hospitalization, and increased use of health care resources. In this article, I review the methodologies and outcomes of several studies and protocols involving preemptive, perioperative, and postoperative use of various anesthetic and analgesic agents. Used together with minimally invasive techniques, appropriate pain control should result in significant improvements in patient outcomes.

Analgesia, Epidural↗
PubMed2006

The surgeon skill set in minimally invasive total knee arthroplasty.

The traditional didactic approach to improving the skill set of surgeons has been shown to have minimal impact. Surgeons, like other adults, learn best by doing, by practicing what they do. and by challenging themselves to take on increasingly difficult scenarios. To be effective, surgical practice requires deconstruction of a procedure into key elements, each of which is repeated until optimal results are achieved before moving on to the next element. Given the multifactorial nature of a procedure such as minimally invasive surgery for total knee arthroplasty, surgeons need to introduce incremental changes into their operating environment to allow for realistic self-assessment during postoperative self-debriefing. One technique, visualization, can be used for virtual practice. In the future, surgical simulators may allow for true virtual practice as well as systematic recording of results. However, psychomotor skills are only one component of surgical success. Intuition and innovation are also key, but these components are more difficult to teach and to learn. The key ingredient to successful practice and ultimate self-improvement in surgery, as in other pursuits in life, is that a person be self-motivated and competitive and have a strong desire to improve coupled with appropriate practice routines that can lead to improvement.

Arthroplasty, Replacement, Knee↗
PubMed2005

High failure rate of a constrained acetabular liner in revision total hip arthroplasty.

Fifty-five consecutive revision total hip arthroplasties (THAs) in 51 patients in which a constrained acetabular liner was used (Duraloc Constrained Liner, DePuy, Warsaw, Ind) were reviewed. In these revisions, 41 constrained liners were placed for recurrent instability and 14 for inadequate stability at the time of revision THA. The mean age of the cohort was 62 years, and 38 of the hips were in female patients (69%). At a minimum of 2 years, 9 of the 55 hips (16%) dislocated. Of these 9 dislocations, 8 occurred in patients who had undergone revision to a constrained liner for recurrent instability without femoral or acetabular component revision. Revision THA for recurrent instability by placing a constrained liner without optimizing other aspects of the reconstruction leads to a high rate of recurrent failure.

Acetabulum↗
PubMed2005

Outpatient total knee arthroplasty with a minimally invasive technique.

Fifty consecutive patients were enrolled in this prospective study. This was 37% of the 135 patients undergoing primary total knee arthroplasty (TKA) by one surgeon. The average patient age was 68 years (50-79 years). A comprehensive perioperative management pathway was developed and was implemented, which combined regional anesthesia with a minimally invasive, TKA technique in which the only incision in the capsule and extensor mechanism is a capsular incision from the joint line to the superior pole of the patella. Postoperatively, patients received oral analgesia. After specific discharge criteria were met, 48 patients (96%) chose to go home the day of surgery. No intraoperative complications occurred. There were 3 readmissions, none related to early discharge: gastrointestinal bleed at 8 days, superficial irrigation and debridement at 21 days, and a closed manipulation at 9 weeks. This study demonstrates that, in these selected patients, outpatient TKA was safe with no short-term readmission or complications related to early discharge. This comprehensive pathway may make it possible for this minimally invasive TKA to be done as an outpatient in specialized surgicenters in the future.

Aged↗
PubMed2005

Implant survivorship and complication rates after total knee arthroplasty with a third-generation cemented system: 5 to 8 years followup.

UNLABELLED: We evaluated implant survivorship, reoperation rates, and complication rates of a group of patients who had total knee arthroplasty with a third-generation cemented prosthetic device using cruciate-retaining and posterior-stabilized designs at 5 to 8 years followup. Three hundred thirty-four consecutive primary total knee arthroplasties (186 cruciate retaining and 148 posterior stabilized) were done in 287 patients at our institution during a 2-year period. Kaplan Meier survivorship using revision for any reason and revision for aseptic loosening as endpoints were 95.9% and 99.5% respectively at 8 years. Nine patients (four with cruciate-retaining total knee arthroplasties, five with posterior-stabilized total knee arthroplasties; 3.1%) had reoperations for any reason. No patients had reoperation for problems related to the patellofemoral joint. Thirty-two patients (11.1%) had intraoperative or postoperative complications. There were no differences in any of the outcomes analyzed between patients who had cruciate-retaining or posterior-stabilized total knee replacements. Our results show that with appropriate patient selection and meticulous attention to surgical technique, excellent clinical and radiographic results can be achieved with a third-generation total knee arthroplasty system at intermediate followup. LEVEL OF EVIDENCE: Therapeutic study, Level III-2 (retrospective cohort study).

Aged↗
PubMed2005

Decision analysis in orthopaedics.

Orthopaedic surgeons are faced with an ever-growing amount of clinical information from which they are required to make treatment decisions. Many of these decisions can be approached with relative certainty. However, there are many situations where the optimal decision is less clear. These treatment decisions will have competing risks, benefits, or costs. Decision analysis is one method to critically evaluate alternative treatment options with multiple potential outcomes. This method of decision making can be extremely valuable because of the growing number of treatment alternatives, and to the ever-increasing complexity of medical scenarios.

Decision Support Techniques↗
PubMed2005

Results of unicompartmental knee arthroplasty at a minimum of ten years of follow-up.

BACKGROUND: There is a renewed interest in unicompartmental knee arthroplasty. The present report describes the minimum ten-year results associated with a unicompartmental knee arthroplasty design that is in current use. METHODS: Sixty-two consecutive unicompartmental knee arthroplasties that were performed with cemented modular Miller-Galante implants in fifty-one patients were studied prospectively both clinically and radiographically. All patients had isolated unicompartmental disease without patellofemoral symptoms. No patient was lost to follow-up. Thirteen patients (thirteen knees) died after less than ten years of follow-up, leaving thirty-eight patients (forty-nine knees) with a minimum of ten years of follow-up. The average duration of follow-up was twelve years. RESULTS: The mean Hospital for Special Surgery knee score improved from 55 points preoperatively to 92 points at the time of the final follow-up. Thirty-nine knees (80%) had an excellent result, six (12%) had a good result, and four (8%) had a fair result. At the time of the final follow-up, thirty-nine knees (80%) had flexion to at least 120 degrees . Two patients (two knees) with well-fixed components underwent revision to total knee arthroplasty, at seven and eleven years, because of progression of patellofemoral arthritis. At the time of the final follow-up, no component was loose radiographically and there was no evidence of periprosthetic osteolysis. Radiographic evidence of progressive loss of joint space was observed in the opposite compartment of nine knees (18%) and in the patellofemoral space of seven knees (14%). Kaplan-Meier analysis revealed a survival rate of 98.0% +/- 2.0% at ten years and of 95.7% +/- 4.3% at thirteen years, with revision or radiographic loosening as the end point. The survival rate was 100% at thirteen years with aseptic loosening as the end point. CONCLUSIONS: After a minimum duration of follow-up of ten years, this cemented modular unicompartmental knee design was associated with excellent clinical and radiographic results. Although the ten-year survival rate was excellent, radiographic signs of progression of osteoarthritis in the other compartments continued at a slow rate. With appropriate indications and technique, this unicompartmental knee design can yield excellent results into the beginning of the second decade of use.

Aged↗