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The John Charnley Award: an accurate and extremely sensitive method to separate, display, and characterize wear debris: part 2: metal and ceramic particles.

ABSTRACT: BACKGROUND: Metal-on-metal and ceramic-on-ceramic bearings were introduced as alternatives to conventional polyethylene in hip arthroplasties to reduce wear. Characterization of wear particles has been particularly challenging due to the low amount and small size of wear particles. Current methods of analysis of such particles have shortcomings, including particle loss, clumping, and inaccurate morphologic and chemical characterization. QUESTIONS/PURPOSES: We describe a method to recover and characterize metal and ceramic particles that (1) improves particle purification, separation, and display; (2) allows for precise particle shape characterization; (3) allows accurate chemical identification; and (4) minimizes particle loss. METHODS: After enzymatic digestion, a single pass of ultracentrifugation cleaned and deposited particles onto silicon wafers or grids for imaging analysis. During centrifugation, particles were passed through multiple layers of denaturants and a metal-selective high-density layer that minimized protein and nucleic acid contamination. The protocol prevented aggregation, providing well-dispersed particles for chemical and morphologic analysis. We evaluated the efficacy and accuracy of this protocol by recovering gold nanobeads and metal and ceramic particles from joint simulator wear tests. RESULTS: The new protocol recovered particles ranging in size from nanometers to micrometers and enabled accurate morphologic and chemical characterization of individual particles. CONCLUSION: Both polyethylene and metal wear debris can be simultaneously analyzed from the same sample by combining a silicon wafer display protocol for polyethylene and the metal and ceramics silicon wafer display protocol. CLINICAL RELEVANCE: Accurate analysis of wear debris is essential in understanding the processes that produce debris and a key step in development of more durable and biocompatible implants.

SUBMITTER: Billi F

PROVIDER: S-EPMC3254749 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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The John Charnley Award: an accurate and extremely sensitive method to separate, display, and characterize wear debris: part 2: metal and ceramic particles.

Billi Fabrizio F Benya Paul P Kavanaugh Aaron A Adams John J McKellop Harry H Ebramzadeh Edward E

Clinical orthopaedics and related research 20120201 2

<h4>Background</h4>Metal-on-metal and ceramic-on-ceramic bearings were introduced as alternatives to conventional polyethylene in hip arthroplasties to reduce wear. Characterization of wear particles has been particularly challenging due to the low amount and small size of wear particles. Current methods of analysis of such particles have shortcomings, including particle loss, clumping, and inaccurate morphologic and chemical characterization.<h4>Questions/purposes</h4>We describe a method to re ...[more]

PMID: 21932105

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Project description:BackgroundStructural hip deformities including developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are thought to predispose patients to degenerative joint changes. However, the natural history of these malformations is not clearly delineated.Questions/purposes(1) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what is the natural history and progression of osteoarthritis in the native hip based on morphological characteristics? (2) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what are the radiographic parameters that predict differential rates of degenerative change?MethodsWe identified every patient 55 years of age or younger at our institution who received unilateral primary THA from 1980 to 1989 (n = 722 patients). Preoperative radiographs were reviewed on the contralateral hip and only hips with Tönnis Grade 0 degenerative change that had minimum 10-year radiographic followup were included. A total of 172 patients met all eligibility criteria with the following structural diagnoses: 48 DDH, 74 FAI, and 40 normal morphology, and an additional 6% (10 of the 172 patients) met all eligibility criteria but were lost to followup before the 10-year minimum. Mean age at the time of study inclusion was 47 years (range, 18-55 years), and 56% (91 of 162) of the patients in this study were female. Mean followup was 20 years (range, 10-35 years). Radiographic metrics, in conjunction with the review of two experienced arthroplasty surgeons, determined the structural hip diagnosis as DDH, FAI, or normal morphology. Every available followup AP radiograph was reviewed to determine progression from Tönnis Grade 0 to 3 until the time of last followup or operative intervention with THA. Survivorship was analyzed by Kaplan-Meier methodology, hazard ratios, and multistate modeling. Thirty-five patients eventually underwent THA: 16 (33%) DDH, 13 (18%) FAI, and six (15%) normal morphology.ResultsDegenerative change was most rapid in patients with DDH followed by FAI and normal morphology. Among patients who recently developed Tönnis 1 degenerative change, the probability of undergoing THA in 10 years based on hip morphology was approximately one in three for DDH and one in five for both FAI and normal morphology hips, whereas the approximate probability at 20 years was two in three for DDH and one in two for both FAI and normal morphology hips. The likelihood of radiographic degeneration was increased in patients with the following findings: femoral head lateralization > 8 mm, femoral head extrusion index > 0.20, acetabular depth-to-width index < 0.30, lateral center-edge angle < 25°, and Tönnis angle > 8°.ConclusionsDegenerative change occurred earliest in patients with DDH, whereas the natural history of patients with FAI was quite similar to structurally normal hips. However, patients with cam deformities and concomitant acetabular dysplasia developed osteoarthritis more rapidly. Although the results of this study cannot be directly correlated to highly active patients with FAI, these findings suggest that correction of FAI to a normal morphology may only minimally impact the natural history, especially if intervention takes place beyond Tönnis 0. Analysis of radiographic parameters showed that incremental changes toward dysplastic morphology increase the risk of degenerative change.Level of evidenceLevel III, prognostic study.

Project description:BACKGROUND:The choice of surgical approach for THA remains controversial. Some studies suggest that the direct anterior approach (DAA) leads to less muscle damage than the miniposterior approach (MPA), but there is little high-quality evidence indicating whether this accelerates recovery, or whether this approach-which may be technically more demanding-is associated with component malposition or more complications. QUESTIONS/PURPOSES:(1) Does the DAA result in faster return to activities of daily living than the MPA? (2) Does the DAA have superior patient-reported outcome measures than the MPA? (3) Does the DAA result in improved radiographic outcomes than the MPA? (4) Does the DAA have a higher risk of complications than the MPA? METHODS:Between March 1, 2013, and May 31, 2016, 116 patients undergoing primary unilateral THA were randomized to either the DAA or MPA; 15 patients withdrew after randomization, and one died 6 months after surgery from a stroke unrelated to the procedure. Recruitment stopped when 52 patients had been randomized into the DAA group and 49 in the MPA group (n = 101). After patient randomization, one high-volume surgeon performed all of the DAAs and three high-volume surgeons performed the MPA THAs. The groups did not differ in age (65 years; SD 11; range, 38-86 years), sex (52% women), or body mass index (mean 29 kg/m; SD 6 kg/m; range, 21-40 kg/m; all p > 0.40). Functional results included time to discontinue gait aids, discontinue all narcotics, and independence with various activities of daily living; accelerometer data evaluated activity level. Clinical and radiographic outcomes, Hip disability and Osteoarthritis Outcome Score, SF-12, and Harris hip scores to 1 year were also tabulated. The minimum followup was 365 days (mean ± SD, 627 ± 369 days). RESULTS:There were slight differences in early functional recovery that favored the DAA versus the MPA: time to discontinue walker use (10 versus 15 days, p = 0.01) and time to discontinue all gait aids (17 versus 24 days, p = 0.04). There were no other differences in early functional milestones, although at 2 weeks after surgery, mean steps per day were 3897 (SD 2258; range, 737-11,010) for the DAA versus 2235 for the MPA (SD 1688; range, 27-7450; p < 0.01). There was no difference in activity monitoring at 1 year. There were no differences in patient-reported outcome scores between the groups. There was no difference in the radiographic parameters measured in the two groups, including leg length discrepancy, component position, or offset, and there was no subsidence observed in any hip. There was no difference in complications between the DAA and the MPA groups (8% [four of 52] versus 10% [five of 49]; p = 0.33). CONCLUSIONS:Both the DAA and MPA approaches provided excellent early recovery with a low risk of complications. Patients undergoing the DAA had a slightly faster recovery, as measured by milestones of function and quantified by activity monitor data, but no substantive differences were evident at 2 months. Because the DAA is the less studied approach, longer term (> 1 year) complications may yet accrue, will be important to quantify, and may offset early benefits. LEVEL OF EVIDENCE:Level I, therapeutic study.

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The John Charnley Award: an accurate and extremely sensitive method to separate, display, and characterize wear debris: part 2: metal and ceramic particles.

Publications

The John Charnley Award: an accurate and extremely sensitive method to separate, display, and characterize wear debris: part 2: metal and ceramic particles.

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