Incidence and Volume of Pelvic Osteolysis at Early Follow-up with Highly Cross-linked and Noncross-linked Polyethylene

Background Little is known about intraarticular pathology following THA prior to the radiographic appearance of osteolysis, primarily due to imaging limitations. MRI has recently been applied to imaging the postarthroplasty hip with the ability to detect periarticular bony and soft tissue pathology; specifically, it is able to detect abnormal synovial patterns and focal bone loss well before the radiographic appearance of osteolysis. Questions/purposes We therefore used MRI to determine the incidence of early reactive synovitis and osteolysis in asymptomatic patients after THA, and whether there is an association between these MRI findings and clinical outcomes or radiographic wear measurements at this early stage. Methods We recruited 31 patients (33 hips) who underwent routine noncemented THA with one of three types of bearing surfaces: metal-on-cross-linked polyethylene (n = 7), ceramic-on-ceramic (n = 12), and ceramic-on-cross-linked polyethylene (n = 14). Patients underwent specialized MRI at a minimum of 12 months (mean, 23 months; range, 12-37 months) after surgery. MR images were analyzed for the presence of synovitis or osteolysis. WOMAC scores, patient assessment questionnaires, and radiographic wear measurements were correlated with MRI findings. Results Reactive synovitis was observed in 13 of 33 patients (39%) and focal osteolysis in one of 33 (3%). The presence of synovitis did not correlate with pain, activity level, patient satisfaction or clinical outcome scales, nor did it correlate with radiographic wear measurements at early followup. Conclusions Our observations suggest reactive synovitis is common yet asymptomatic at short-term followup. We do not know either the etiology or the long-term implications of these observations.

Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 81%

Early Reactive Synovitis and Osteolysis after Total Hip Arthroplasty

Cooper

Ranawat

Potter

et al. 2010

“…As noted, this contradicts subsequent clinical experience [5,28]. In addition to the limitations of the filtration-based protocol employed by Endo et al [11], they assumed biologic activity indices obtained from in vitro tests of particles from noncrosslinked PE particles also applied to crosslinked PE particles within the same size band.…”

Section: Discussionmentioning

confidence: 99%

“…With followup exceeding 12 years, the incidence and extent of osteolysis have been markedly lower for hip arthroplasties using crosslinked PEs [5,27,28]. This outcome contradicts the predictions by some early studies [11,18,25], which indicated the osteolytic potentials with elevated crosslinking could be as high as or higher than for historical PEs.…”

Section: Discussionmentioning

confidence: 99%

The John Charnley Award: An Accurate and Sensitive Method to Separate, Display, and Characterize Wear Debris: Part 1: Polyethylene Particles

Billi

Benya

Kavanaugh

et al. 2012

Background Numerous studies indicate highly crosslinked polyethylenes reduce the wear debris volume generated by hip arthroplasty acetabular liners. This, in turns, requires new methods to isolate and characterize them. Questions/purposes We describe a method for extracting polyethylene wear particles from bovine serum typically used in wear tests and for characterizing their size, distribution, and morphology.Methods Serum proteins were completely digested using an optimized enzymatic digestion method that prevented the loss of the smallest particles and minimized their clumping. Density-gradient ultracentrifugation was designed to remove contaminants and recover the particles without filtration, depositing them directly onto a silicon wafer. This provided uniform distribution of the particles and high contrast against the background, facilitating accurate, automated, morphometric image analysis. The accuracy and precision of the new protocol were assessed by recovering and characterizing particles from wear tests of three types of polyethylene acetabular cups (no crosslinking and 5 Mrads and 7.5 Mrads of gamma irradiation crosslinking). Results The new method demonstrated important differences in the particle size distributions and morphologic parameters among the three types of polyethylene that could not be detected using prior isolation methods. Conclusion The new protocol overcomes a number of limitations, such as loss of nanometer-sized particles and artifactual clumping, among others. Clinical Relevance The analysis of polyethylene wear particles produced in joint simulator wear tests of prosthetic joints is a key tool to identify the wear mechanisms that produce the particles and predict and evaluate their effects on periprosthetic tissues.

“…Although the wear rate was less than the osteolysis threshold suggested by Dumbleton et al [8], Illgen et al [17] suggested that the benefit of a decrease in wear rate for XLPE may be offset by an increase in the inflammatory profile of these wear particles compared with those from conventional polyethylene. Leung et al [21] reported three of 36 patients with Marathon TM liners had osteolytic lesions observed on CT scans at 5 years. Therefore, long-term studies investigating the presence of osteolysis are needed to confirm the clinical benefits of reduced wear with XLPE liners.…”

Section: Discussionmentioning

confidence: 99%

Wear of a 5 Megarad Cross-linked Polyethylene Liner: A 6-year RSA Study

Callary

Campbell

Mercer

et al. 2013

Background One cross-linked polyethylene (XLPE) liner is manufactured using a lower dose of radiation, 5 Mrad, which may result in less cross-linking. The reported in vivo wear rate of this XLPE liner in patients undergoing THA has varied, and has included some patients in each reported cohort who had greater than 0.1 mm/year of wear, which is an historical threshold for osteolysis. Previous studies have measured wear on plain radiographs, an approach that has limited sensitivity.Questions/purposes We therefore measured the amount and direction of wear at 6 years using Radiostereometric analysis (RSA) in patients who had THAs that included a cross-linked polyethylene liner manufactured using 5 Mrad radiation. Methods We prospectively reviewed wear in 30 patients who underwent primary THAs with the same design of cross-linked acetabular liner and a 28-mm articulation. Tantalum markers were inserted during surgery and all patients had RSA radiographic examinations at 1 week, 6 months, 1, 2, and 6 years postoperatively. Results The mean proximal, two-dimensional (2-D) and three-dimensional (3-D) wear rates calculated between 1 year and 6 years were 0.014, 0.014, and 0.018 mm/per year, respectively. The direction of the head penetration recorded between 1 week and 6 years was in a proximal direction for all patients, proximolateral for 16 of 24 patients, and proximomedial for eight of 24 patients. Conclusions The proximal, 2-D and 3-D wear of a XLPE liner produced using 5 Mrad of radiation was low but measurable by RSA after 6 years. No patients had proximal 2-D or 3-D wear rates exceeding 0.1 mm/year. Further followup is needed to evaluate the effect of XLPE wear particles on the development of long-term osteolysis.