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Biomedical subjects

Aaron A Hofmann

Publications and source records attributed to Aaron A Hofmann.

12 recordsLinked to original sources
PubMed2006

Surface cementation of stemmed tibial components in primary total knee arthroplasty: minimum 5-year follow-up.

Cement remains the "gold standard" for fixation in total knee arthroplasty. Between 1991 and 1998, 128 consecutive knees in 109 patients underwent primary cemented total knee arthroplasty using a surface cementation technique. The average follow-up was 95 (range, 63-155) months. Preoperative range of motion (ROM) averaged 5 degrees to 111 degrees which improved to 1 degrees to 116 degrees postoperatively. Modified Hospital for special surgery score (HSS) scores improved from 61 (range, 47-76) to 97 (range, 81-100) and the corresponding Knee Society Scores from 122 (range, 94-152) to 195 (range, 162-200). No osteolytic lesions were found; however, 3 tibias had radiolucent lines which were asymptomatic, nonprogressive, and not associated with implant failure. The average depth of penetration of cement was 2.7 mm. One knee (1%) required revision surgery for femoral loosening, and 1 required revision of the polyethylene liner. The present cementation technique provides excellent durable results at midterm follow-up.

Aged↗
PubMed2006

Clinical and radiographic analysis of accurate restoration of the joint line in revision total knee arthroplasty.

A clinical and radiographic analysis was performed on 89 consecutive revision total knee arthroplasties. The postoperative joint line position was evaluated and correlated with the clinical outcome. The joint line position was evaluated radiographically. Average follow-up was 8.2 years (24-197 months). Clinical outcome values were correlated to joint line position. More improvement was seen with recreation of the normal joint line to within +/-4 mm of the normal unaffected knee for Knee Society Score, average total arc of motion, flexion, and extension. There was a significant difference found for all 4 variables when combined outliers were compared with goal range (-4 to 4 mm). In this study, clinical outcome was improved if the joint line was accurately reproduced.

Adult↗
PubMed2006

Does celecoxib have an adverse effect on bone remodeling and ingrowth in humans?

Although celecoxib may provide perioperative pain relief, the effect of the short-term use of celecoxib on bone ingrowth into porous-coated devices has not been previously studied in humans. Bone ingrowth into titanium and tantalum plugs was measured in nine patients who underwent staged bilateral total knee arthroplasty (TKA) and were taking celecoxib as part of a perioperative pain relief protocol. Patients were given tetracycline to measure the mineral apposition rate before and after celecoxib administration. Time zero plugs were implanted and retrieved during the first TKA, and 12 weeks later the contralateral implanted plugs were retrieved at the second TKA. The mineral apposition rate was similar for the titanium (0.97 microm per day) and the tantalum (1.15 microm per day) plugs at 12 weeks as was bone ingrowth (886 microm versus 632 microm, respectively). Celecoxib does not seem to inhibit bone ingrowth or bone formation.

Arthroplasty, Replacement, Knee↗
PubMed2005

Oxidative degradation in highly cross-linked and conventional polyethylene after 2 years of real-time shelf aging.

Previous studies have reported oxidative degradation of conventional polyethylene (PE) components during shelf aging, following radiation. However, no studies have yet reported data concerning the effect of real-time shelf aging in the manufacturer's packaging on the oxidative degradation of commercially available highly cross-linking PE components. The null hypothesis tested was that in either highly cross-linked or conventional PE acetabular components there would be no significant difference in the amount of oxidative degradation between time zero PE liners and PE liners that had been real-time shelf aged for 2 years in their respective packaging. The results of the study indicated that after 2 years of real-time shelf aging, negligible oxidative degradation occurred with minimal changes in oxidation index, density, and percent crystallinity in commercially available highly cross-linked and conventional PE acetabular liners. These data suggested that oxidative degradation was not a clinical issue in the highly cross-linked and conventional PE components examined after 2 years of real-time shelf aging. It is likely that current manufacturing and packaging technologies have limited the previous clinical concerns related to oxidative degradation during shelf aging of highly cross-linked and conventional PE components.

Arthroplasty, Replacement, Hip↗
PubMed2005

Ten-year experience using an articulating antibiotic cement hip spacer for the treatment of chronically infected total hip.

Infection is a devastating complication after total-hip arthroplasty. Between June 1991 and December 2001, 42 patients were treated at our center for chronically infected total-hip arthroplasty using a 2-stage articulating antibiotic hip spacer technique. Of the 27 patients available for review, 26 (94%) remain clinically free of infection at an average 76 months (range, 28-148 months) postoperatively. Twenty-two (81%) patients had a positive identification of the infecting organism. All patients received a minimum of 6 weeks of intravenous antibiotics and the Harris Hip Scores improved from 53 (range, 36-68) to 92 (range, 81-99) postoperatively. Advantages of this technique include improved patient function, maintenance of bone stock and soft tissue tension, thus simplifying reimplantation.

Adult↗
PubMed2005

Treatment of infected total knee arthroplasty using an articulating spacer: 2- to 12-year experience.

UNLABELLED: Fifty consecutive patients with late infected total knee arthroplasties were treated by debridement and removal of all components and cement, preserving the collateral ligaments. At the time of debridement, an articulating spacer was made to allow partial weightbearing and range of motion of the knee during rehabilitation. This spacer was implanted using antibiotic-impregnated bone cement. For this purpose, 4.8 g powdered tobramycin was mixed with 40 g Simplex cement. Cement was applied early to the components, but applied late to the femur, tibia, and patella to allow molding to the defects and bone without adherence to bone. Patients had tailored intravenous antibiotic therapy for 6 weeks for treatment of various gram-positive and gram-negative organisms. All patients had cemented revision total knee arthroplasty using antibiotic-impregnated cement with standard cementing techniques. Range of motion before reimplantation was 6 degrees -91 degrees . Followup averaged 73 months (range, 24-150 months). The average modified Hospital for Special Surgery knee score after revision was 89 points (range, 70-100 points) with 90% good to excellent results, excluding the results of patients with reinfection. Range of motion after reimplantation was 4 degrees -104 degrees. Six patients had recurrences of infection, and one patient with a poor postoperative range of motion had a fusion. Use of an articulating spacer achieved soft tissue compliance, allowed for ease of operation, reduced postoperative pain, improved function, and eradicated infection equal to standards reported in the literature. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series-no, or historical controls).

Adult↗
PubMed2004

Determining relevance of a weight-bearing ovine model for bone ingrowth assessment.

A weight-bearing ovine model was used to quantify cancellous bone ingrowth and remodeling in porous-coated implants over 6, 12, and 24 weeks in situ. The null hypothesis for the investigation was that there would be no significant difference between the amount of cancellous bone ingrowth and rate of remodeling in this ovine model compared to a reported human bilateral implant model. Bone ingrowth progressed from 20.1 +/- 8.2% at 6 weeks in situ to 23.8 +/- 7.9% at 12 weeks, and 30 +/- 5.1% at 24 weeks. Fluorochrome analysis demonstrated a mineral apposition rate of 1.07 +/- 0.28 microm/day for bone at the porous-coating interface, whereas host bone remodeling at 0.89 +/- 0.23 microm/day. Histological analysis showed no adverse tissue or inflammatory response. The null hypothesis was supported in that regression analysis demonstrated that the amount of cancellous bone ingrowth over time (p = 0.545) and mineral apposition rate over time (p = 0.089) in this ovine model was not significantly different than reported human bilateral knee data. The results of this study appear to validate the ovine model for use in understanding skeletal attachment of porous-coated implants to cancellous bone in humans.

Animals↗
PubMed2004

Bone viability determination in human cancellous bone from patients undergoing revision hip arthroplasty.

In December 2000, Sulzer Orthopedics Inc. announced the recall of specific lots of Inter-Op acetabular components as a result of an adverse tissue response to a contaminant on the porous surface of the component. This study was initiated to assess bone viability surrounding the primary and revision components. Twelve patients were placed on a double-tetracycline labeling protocol before revision surgery. Initial and final acetabular reamings were frozen-sectioned using cryostat technology. A mineral apposition rate, preoperative and postoperative radiographs, and Harris Hip Scores were evaluated. The tetracycline data showed that bone viability was not compromised at initial or final reaming levels in this series of patients. Significant improvement was observed in postoperative Harris Hip Scores when compared with preoperative Harris Hip Scores.

Acetabulum↗
PubMed2002

Cementless total knee arthroplasty in patients 50 years or younger.

Total knee arthroplasty now is being advocated for use in younger patients with posttraumatic and rheumatoid arthritis. Advances in technology, design, and materials potentially have allowed for more predictable results. There has been continued interest in cementless fixation for use in younger patients. Between 1986 and 1998, 75 total knee replacements in 57 patients 50 years or younger were done. All surgeries were done by one surgeon (AAH). There were 35 left knees and 40 right knees. The average age of the patients was 42 years (range, 31-50 years). Followup averaged 111 months. Preoperative range of motion was 5 degrees to 106 degrees and postoperative range of motion was 2 degrees to 113 degrees. Modified Hospital for Special Surgery knee scores improved from an average of 67 points preoperatively to an average of 97 points postoperatively. The majority of the diagnoses were posttraumatic arthritis or osteoarthritis (57%), indicating a young, active group of patients. There were two infections and 12 polyethylene exchanges. There were no revisions for loosening or implant failure. There was a correlation between prior knee surgeries and the need for a manipulation. Radiographically, there were no loose implants. Cementless fixation in the young patient with high physical demands was clinically reliable.

Adult↗