Micromotion of the polyethylene (PE) inlay may contribute to backside PE wear in addition to articulate wear of total knee arthroplasty (TKA). Using radiostereometric analysis (RSA) with tantalum beads in the PE inlay, we evaluated PE micromotion and its relationship to PE wear. A total of 23 patients with a mean age of 83 years (77 to 91), were available from a RSA study on cemented TKA with Maxim tibial components (Zimmer Biomet). PE inlay migration, PE wear, tibial component migration, and the anatomical knee axis were evaluated on weightbearing stereoradiographs. PE inlay wear was measured as the deepest penetration of the femoral component into the PE inlay.Aims
Methods
Taper corrosion has been widely reported to be problematic for modular total hip arthroplasty implants. A simple and systematic method to evaluate taper damage with sufficient resolution is needed. We introduce a semiquantitative grading system for modular femoral tapers to characterize taper corrosion damage. After examining a unique collection of retrieved cobalt-chromium (CoCr) taper sleeves (n = 465) using the widely-used Goldberg system, we developed an expanded six-point visual grading system intended to characterize the severity, visible material loss, and absence of direct component contact due to corrosion. Female taper sleeve damage was evaluated by three blinded observers using the Goldberg scoring system and the expanded system. A subset (n = 85) was then re-evaluated following destructive cleaning, using both scoring systems. Material loss for this subset was quantified using metrology and correlated with both scoring systems.Aims
Methods
One of the main causes of tibial revision surgery for total knee arthroplasty is aseptic loosening. Therefore, stable fixation between the tibial component and the cement, and between the tibial component and the bone, is essential. A factor that could influence the implant stability is the implant design, with its different variations. In an existing implant system, the tibial component was modified by adding cement pockets. The aim of this experimental in vitro study was to investigate whether additional cement pockets on the underside of the tibial component could improve implant stability. The relative motion between implant and bone, the maximum pull-out force, the tibial cement mantle, and a possible path from the bone marrow to the metal-cement interface were determined. A tibial component with (group S: Attune S+) and without (group A: Attune) additional cement pockets was implanted in 15 fresh-frozen human leg pairs. The relative motion was determined under dynamic loading (extension-flexion 20° to 50°, load-level 1,200 to 2,100 N) with subsequent determination of the maximum pull-out force. In addition, the cement mantle was analyzed radiologically for possible defects, the tibia base cement adhesion, and preoperative bone mineral density (BMD).Aims
Methods
Acetabular edge-loading was a cause of increased wear rates in metal-on-metal hip arthroplasties, ultimately contributing to their failure. Although such wear patterns have been regularly reported in retrieval analyses, this study aimed to determine their in vivo location and investigate their relationship with acetabular component positioning. 3D CT imaging was combined with a recently validated method of mapping bearing surface wear in retrieved hip implants. The asymmetrical stabilizing fins of Birmingham hip replacements (BHRs) allowed the co-registration of their acetabular wear maps and their computational models, segmented from CT scans. The in vivo location of edge-wear was measured within a standardized coordinate system, defined using the anterior pelvic plane.Aims
Methods
Aims. This study aims to enhance understanding of clinical and radiological consequences and involved mechanisms that led to corrosion of the Precice Stryde (Stryde) intramedullary lengthening nail in the post market surveillance era of the device. Between 2018 and 2021 more than 2,000 Stryde nails have been implanted worldwide. However, the outcome of treatment with the Stryde system is insufficiently reported. Methods. This is a retrospective single-centre study analyzing outcome of 57 consecutive lengthening procedures performed with the Stryde nail at the authors’ institution from February 2019 until November 2020. Macro- and microscopic metallographic analysis of four retrieved nails was conducted. To investigate observed corrosion at telescoping junction, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) were performed. Results. Adjacent to the nail’s telescoping junction, osteolytic changes were observed in bi-planar radiographs of 20/57 segments (35%) after a mean of 9.5 months (95% confidence interval 7.2 to 11.9) after surgery. A total of 8/20 patients with osseous alterations (40%) reported rest and ambulation pain of the lengthened segment during consolidation. So far, 24 Stryde nails were retrieved and in 20 (83%) macroscopic corrosion was observed at the nail’s telescoping junction. Before implant removal 11/20 radiographs (55%) of lengthened segments with these 20 nails revealed osteolysis. Implant
The main advantage of 3D-printed, off-the-shelf acetabular implants is the potential to promote enhanced bony fixation due to their controllable porous structure. In this study we investigated the extent of osseointegration in retrieved 3D-printed acetabular implants. We compared two groups, one made via 3D-printing (n = 7) and the other using conventional techniques (n = 7). We collected implant details, type of surgery and removal technique, patient demographics, and clinical history. Bone integration was assessed by macroscopic visual analysis, followed by sectioning to allow undecalcified histology on eight sections (~200 µm) for each implant. The outcome measures considered were area of bone attachment (%), extent of bone ingrowth (%), bone-implant contact (%), and depth of ingrowth (%), and these were quantified using a line-intercept method.Aims
Methods
The optimum clearance between the bearing surfaces of hip arthroplasties is unknown. Theoretically, to minimize wear, it is understood that clearances must be low enough to maintain optimal contact pressure and fluid film lubrication, while being large enough to allow lubricant recovery and reduce contact patch size. This study aimed to identify the relationship between diametrical clearance and volumetric wear, through the analysis of retrieved components. A total of 81 metal-on-metal Pinnacle hips paired with 12/14 stems were included in this study. Geometrical analysis was performed on each component, using coordinate and roundness measuring machines. The relationship between their as-manufactured diametrical clearance and volumetric wear was investigated. The Mann-Whitney U test and unpaired Aims
Methods
The aim of this study was to determine the polyethylene wear rate of Phase 3 Oxford Unicompartmental Knee Replacement bearings and to investigate the effects of resin type and manufacturing process. A total of 63 patients with at least ten years’ follow-up with three bearing types (1900 resin machined, 1050 resin machined, and 1050 resin moulded) were recruited. Patients underwent full weight-bearing model-based radiostereometric analysis to determine the bearing thickness. The linear wear rate was estimated from the change in thickness divided by the duration of implantation.Objectives
Methods
Objectives. The Attune total knee arthroplasty (TKA) has been used in over 600 000 patients worldwide. Registry data show good clinical outcome; however, concerns over the cement-tibial interface have been reported. We used
Previous studies have suggested that metal-on-metal (MoM) Pinnacle (DePuy Synthes, Warsaw, Indiana) hip arthroplasties implanted after 2006 exhibit higher failure rates. This was attributed to the production of implants with reduced diametrical clearances between their bearing surfaces, which, it was speculated, were outside manufacturing tolerances. This study aimed to better understand the performance of Pinnacle Systems manufactured before and after this event. A total of 92 retrieved MoM Pinnacle hips were analyzed, of which 45 were implanted before 2007, and 47 from 2007 onwards. The ‘pre-2007’ group contained 45 implants retrieved from 21 male and 24 female patients, with a median age of 61.3 years (interquartile range (IQR) 57.1 to 65.5); the ‘2007 onwards’ group contained 47 implants retrieved from 19 male and 28 female patients, with a median age of 61.8 years (IQR 58.5 to 67.8). The volume of material lost from their bearing and taper surfaces was measured using coordinate and roundness measuring machines. These outcomes were then compared statistically using linear regression models, adjusting for potentially confounding factors.Objectives
Methods
Objectives. The Precice nail is the latest intramedullary lengthening nail with excellent early outcomes. Implant complications have led to modification of the nail design. The aim of this study was to perform a retrieval study of Precice nails following lower-limb lengthening and to assess macroscopical and microscopical changes to the implants and evaluate differences following design modification, with the aim of identifying potential surgical, implant, and patient risk factors. Methods. A total of 15 nails were retrieved from 13 patients following lower-limb lengthening. Macroscopical and microscopical surface damage to the nails were identified. Further analysis included radiology and micro-CT prior to sectioning. The internal mechanism was then analyzed with scanning electron microscopy and energy dispersive x-ray spectroscopy to identify corrosion. Results. Seven male and three female patients underwent 12 femoral lengthenings. Three female patients underwent tibial lengthening. All patients obtained the desired length with no implant failure. Surface degradation was noted on the telescopic part of every nail design, less on the latest implants. Microscopical analysis confirmed fretting and pitting corrosion. Following sectioning, black debris was noted in all implants. The early designs were found to have fractured actuator pins and the pin and bearings showed evidence of corrosive debris. The latest designs showed evidence of biological deposits suggestive of fluid ingress within the nail but no corrosion. Conclusion. This study confirms less internal corrosion following modification, but evidence of titanium debris remains. We recommend no change to current clinical practice. However, potential reuse of the Precice nail, for secondary limb lengthening in the same patient, should be undertaken with caution. Cite this article: V. C. Panagiotopoulou, K. Davda, H. S. Hothi, J. Henckel, A. Cerquiglini, W. D. Goodier, J. Skinner, A. Hart, P. R. Calder. A
Objectives. We have encountered patients who developed large joint fluid collections with massive elevations in chromium (Cr) and cobalt (Co) concentrations following metal-on-metal (MoM) hip arthroplasties. In some cases,
Objectives. The use of ceramic femoral heads in total hip arthroplasty (THA) has increased due to their proven low bearing wear characteristics. Ceramic femoral heads are also thought to reduce wear and corrosion at the head-stem junction with titanium (Ti) stems when compared with metal heads. We sought to evaluate taper damage of ceramic compared with metal heads when paired with cobalt chromium (CoCr) alloy stems in a single stem design. Methods. This retrieval study involved 48 total hip arthroplasties (THAs) with CoCr V40 trunnions paired with either CoCr (n = 21) or ceramic (n = 27) heads. The taper junction of all hips was evaluated for fretting/corrosion damage and volumetric material loss using a roundness-measuring machine. We used linear regression analysis to investigate taper damage differences after adjusting for potential confounding variables. Results. We measured median taper material loss rates of 0.210 mm. 3. /year (0.030 to 0.448) for the metal head group and 0.084 mm. 3. /year (0.059 to 0.108) for the ceramic group. The difference was not significant (p = 0.58). Moreover, no significant correlation between material loss and implant or patient factors (p > 0.05) was found. Conclusions. Metal heads did not increase taper damage on CoCr trunnions compared with ceramic heads from the same hip design. The amount of material released at the taper junctions was very low when compared with available data regarding CoCr/Ti coupling in metal-on-metal bearings. Cite this article: A. Di Laura, H. Hothi, J. Henckel, I. Swiatkowska, M. H. L. Liow, Y-M. Kwon, J. A. Skinner, A. J. Hart.
Mechanical wear and corrosion at the head-stem junction of total hip arthroplasties (THAs) (trunnionosis) have been implicated in their early revision, most commonly in metal-on-metal (MOM) hips. We can isolate the role of the head-stem junction as the predominant source of metal release by investigating non-MOM hips; this can help to identify clinically significant volumes of material loss and corrosion from these surfaces. In this study we examined a series of 94 retrieved metal-on-polyethylene (MOP) hips for evidence of corrosion and material loss at the taper junction using a well published visual grading method and an established roundness-measuring machine protocol. Hips were retrieved from 74 male and 20 female patients with a median age of 57 years (30 to 76) and a median time to revision of 215 months (2 to 324). The reasons for revision were loosening of both the acetabular component and the stem (n = 29), loosening of the acetabular component (n = 58) and infection (n = 7). No adverse tissue reactions were reported by the revision surgeons.Objectives
Methods
We are entering a new era with governmental bodies
taking an increasingly guiding role, gaining control of registries,
demanding direct access with release of open public information
for quality comparisons between hospitals. This review is written
by physicians and scientists who have worked with the Swedish Knee
Arthroplasty Register (SKAR) periodically since it began. It reviews
the history of the register and describes the methods used and lessons
learned. Cite this article:
We aimed to determine the effect of surgical approach on the
histology of the femoral head following resurfacing of the hip. We performed a histological assessment of the bone under the
femoral component taken from retrieval specimens of patients having
revision surgery following resurfacing of the hip. We compared the
number of empty lacunae in specimens from patients who had originally
had a posterior surgical approach with the number in patients having alternative
surgical approaches.Objectives
Methods
