Publications (6)15.01 Total impact
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Article: Prognostic Factors for Bacterial Cultures Positive for Propionibacterium acnes and Other Organisms in a Large Series of Revision Shoulder Arthroplasties Performed for Stiffness, Pain, or Loosening.
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ABSTRACT: Propionibacterium acnes has been grown on culture in half of the reported cases of chronic infection associated with shoulder arthroplasty. The presence of this organism can be overlooked because its subtle presentation may not suggest the need for culture or because, in contrast to many orthopaedic infections, multiple tissue samples and weeks of culture incubation are often necessary to recover this organism. Surgical decisions regarding implant revision and antibiotic therapy must be made before the results of intraoperative cultures are known. In the present study, we sought clinically relevant prognostic evidence that could help to guide treatment decisions. We statistically correlated preoperative and intraoperative observations on 193 shoulder arthroplasty revisions that were performed because of pain, loosening, or stiffness with the results of a Propionibacterium acnes-specific culture protocol. Regression models were used to identify factors predictive of a positive culture for Propionibacterium acnes. One hundred and eight of the 193 revision arthroplasties were associated with positive cultures; 70% of the positive cultures demonstrated growth of Propionibacterium acnes. The rate of positive cultures per shoulder increased with the number of culture specimens obtained from each shoulder. Fifty-five percent of the positive cultures required observation for more than one week. Male sex, humeral osteolysis, and cloudy fluid were each associated with significant increases of ≥600% in the likelihood of obtaining a positive Propionibacterium acnes culture. Humeral loosening, glenoid wear, and membrane formation were associated with significant increases of >300% in the likelihood of obtaining a positive Propionibacterium acnes culture. Preoperative and intraoperative factors can be used to help to predict the risk of a positive culture for Propionibacterium acnes. This evidence is clinically relevant to decisions regarding prosthesis removal or retention and the need for immediate antibiotic therapy at the time of revision shoulder arthroplasty before the culture results become available. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.The Journal of Bone and Joint Surgery 11/2012; 94(22):2075-83. · 3.27 Impact Factor -
Article: A quantitative method for determining medial migration of the humeral head after shoulder arthroplasty: preliminary results in assessing glenoid wear at a minimum of two years after hemiarthroplasty with concentric glenoid reaming.
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ABSTRACT: Glenoid erosion and medial migration of the humeral head prosthesis have been observed after most types of shoulder arthroplasty. A method of measuring the change in humeral head position with time after shoulder prosthetic arthroplasty was applied it to 14 shoulders that underwent humeral hemiarthroplasty with concentric glenoid reaming. We hypothesized that the measurement technique would be reproducible and that the rate of wear would be small in the series of shoulders studied. Standardized anteroposterior and axillary radiographs were obtained after surgery. Two examiners measured the position of the humeral head center in relation to scapular reference coordinates for the anteroposterior and axillary projections and plotted these values against time after surgery. The change in position was characterized as the slope of this plot. Shoulders were included if there were at least 3 sets of postoperative films, the last being at least 2 years after surgery. The slopes measured by the 2 examiners agreed within 0.5 mm/y for the anteroposterior and the axillary projections. For the series of shoulder arthroplasties, the rate of movement of the head center toward the scapula was less than 0.4 mm/y for either examiner in either projection. Medial migration is a concern after any type of shoulder arthroplasty, whether a hemiarthroplasty, a biological interpositional arthroplasty, or a total shoulder arthroplasty. Quantifying the rate of medial migration over time after shoulder arthroplasty is an important element of clinical follow-up. This is an inexpensive, practical, and reproducible method that can be used to determine the rate of medial migration of the humeral head on plain radiographs after shoulder arthroplasty. The average rate of medial migration in the shoulders in this study was small.Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 03/2011; 20(2):301-7. · 1.93 Impact Factor -
Article: Postsurgical chondrolysis of the shoulder.
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ABSTRACT: There are multiple reports in the literature of chondrolysis following arthroscopic shoulder surgery. Although the etiology of these cases is not known for certain, there has been speculation that radiofrequency devices, young patient age, instability surgery, intra-articular pain pumps, and type of anesthetic may be precipitating factors. This article describes a case of a 37-year-old law enforcement officer who injured both shoulders and ultimately underwent nearly identical bilateral procedures: arthroscopic superior labrum anteroposterior (SLAP) repair, Bankart repair, capsulorrhaphy, acromioplasty, and distal clavicle excision. Intra-articular pain catheters were placed following both procedures, but the right-sided catheter never functioned properly, as evidenced by continuous leakage outside of her body until it was removed. Subsequently she had an arthroscopic lysis of adhesions done for residual stiffness, in which the left humeral head and glenoid cavity were noted to be completely devoid of articular cartilage. Over the ensuing months, multiple cortisone injections, 5 viscosupplementation injections, physical therapy, and narcotics all failed to relieve her left shoulder pain. Radiographs showed significant left glenohumeral joint space narrowing and a normal-appearing joint space on the right. Our impression was postsurgical chondrolysis of the left shoulder. The patient has recently undergone humeral hemiarthroplasty with nonprosthetic glenoid arthroplasty. This case differs from others reported in the literature in that nearly identical bilateral procedures were performed by the same surgeon, yet chondrolysis only developed on the side that had a functioning postoperative pain catheter.Orthopedics 04/2009; 32(3):215. · 2.66 Impact Factor -
Article: Glenoid component failure in total shoulder arthroplasty.
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ABSTRACT: Glenoid component failure is the most common complication of total shoulder arthroplasty. Glenoid components fail as a result of their inability to replicate essential properties of the normal glenoid articular surface to achieve durable fixation to the underlying bone, to withstand repeated eccentric loads and glenohumeral translation, and to resist wear and deformation. The possibility of glenoid component failure should be considered whenever a total shoulder arthroplasty has an unsatisfactory result. High-quality radiographs made in the plane of the scapula and in the axillary projection are usually sufficient to evaluate the status of the glenoid component. Failures of prosthetic glenoid arthroplasty can be understood in terms of failure of the component itself, failure of seating, failure of fixation, failure of the glenoid bone, and failure to effectively manage eccentric loading. An understanding of these modes of failure leads to strategies to minimize complications related to prosthetic glenoid arthroplasty.The Journal of Bone and Joint Surgery 05/2008; 90(4):885-96. · 3.27 Impact Factor -
Article: Factors affecting fixation of the glenoid component of a reverse total shoulder prothesis.
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ABSTRACT: The semiconstrained design of the reverse arthroplasty allows loads from the humerus to challenge the fixation of the glenoid component to the scapula. We examined some of the factors affecting the quality of glenoid screw fixation, including the density of the material into which the screws are placed, the purchase of individual screws, and the direction of loading in relation to screw placement. Loads were applied by the humeral component to glenoid components with different conditions of fixation. The load to failure for each set of conditions was measured and compared statistically. Load to failure was less when the glenoid component was fixed to material of lesser density. Each screw contributed to the quality of fixation; the screw nearest the point of load application made the largest contribution. Load to failure was less when the load was colinear with a line through the nonlocking holes in the base plate compared to colinear with a line through the locking holes. In performing a reverse total shoulder, surgeons should emphasize secure intraosseous placement of the fixation screws in the best quality bone available. The placement of the inferior screw appears to be the most critical.Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 17(2):323-7. · 1.93 Impact Factor -
Article: Intramedullary reaming for press-fit fixation of a humeral component removes cortical bone asymmetrically.
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ABSTRACT: Periprosthetic humeral fractures are major complications of shoulder arthroplasty. Bone removal during surgical reaming is a risk factor for these fractures. Although it is recognized that the endosteal surface of the humerus is asymmetrical whereas the reamers are symmetrical, to our knowledge, the effect of cylindrical reaming on the pattern of cortical bone removal during reaming has not been previously studied. The medullary canals of 10 cadaveric humeri (mean age, 73 years) were reamed in a manner similar to that used during humeral arthroplasty. Cortical dimensions were obtained from computed tomography scans before and after reaming. In unreamed humeri, the anterior-posterior endocortical diameter was 20% smaller than the medial-lateral diameter. The average medial-lateral diameter (15.6 +/- 2.3 mm) was significantly greater than the anterior-posterior diameter (12.5 +/- 1.9 mm) at 13 cm distal to the tuberosity (P < .00005). Successive cylindrical reaming preferentially thinned the anterior and posterior cortices. This bone loss would not be apparent on anterior-posterior radiographs. Intramedullary reaming to obtain substantial cortical contact asymmetrically removes cortical bone in a manner that may increase the risk of periprosthetic fracture.Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 17(1):150-5. · 1.93 Impact Factor
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2009
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University of Washington Seattle
- Department of Orthopaedics and Sports Medicine
Seattle, WA, USA
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