Adapter Sleeves Research Articles

Influence of a Modified Procedure of Joining Ceramic Head and Adapter Sleeve on the Stem Taper in Revision: An Experimental Study.

In revision operations, ceramic heads of modular hip implants can be replaced. As the surface of the stem taper can be damaged, additional adapter sleeves are applied. The components are usually connected manually by the surgeon in a one-step procedure by hammer impacts. In this study, we investigated a two-step joining procedure with reproducible impaction force. First, the adapter sleeve and head were joined quasi-statically with a force of 2 kN using an assembly device. In the second step, these components were applied to the stem taper using a pulse-controlled instrument. For reference, the joints were assembled according to standard conditions using a tensile testing machine. An average pull-off force of 1309 ± 201 N was achieved for the components joined by the instrument, and the average measured values for the components joined by the testing machine were 1290 ± 140 N. All specimens achieved a force >350 N when released and therefore met the acceptance criterion defined for this study. This study showed that a modified procedure in two steps with a defined force has a positive effect on the reproducibility of the measured joining forces compared to previous studies.

Computer-based analysis of the taper connection strength of different revision head and adapter sleeve designs.

Ceramic revision heads, equipped with titanium adapter sleeves, are used in femoral head revision in total hip arthroplasty to avoid ceramic fracture due to the damaged taper. A finite element analysis of the taper connection strength of revision heads with varying head diameters combined with adapter sleeves of different lengths was conducted. The influence of various assembly forces, head diameter, and length of the adapter sleeves was evaluated. For two combinations, the pattern of contact pressure was evaluated when applying a simplified joint load (3 kN, 45° load angle). Experimental validation was conducted with 36 mm heads and adapter sleeves in size S, as well as 28 mm heads and adapter sleeves in size XL. The pull-off force increased with higher assembly forces. Using larger head diameters and adapter sleeves led to decreased pull-off forces, a reduced contact surface, and less contact pressure. The contact pressure showed significant peaks and a diagonal pattern under 45° angle loading when assembly forces were less than 4 kN, and larger adapter sleeves were utilized. A sufficient assembly force should be ensured intraoperatively, especially with an increasing head diameter and adapter sleeve size, as lower assembly forces might lead to reduced taper connection strength.

Taper connection strength of revision heads with adapter sleeves compared to standard heads made of ceramics

Abstract Revision ceramic heads with titanium adapter sleeves are used in case of a femoral head revision in total hip arthroplasty to avoid ceramic fracture due to damaged tapers. Objective of the present study was to evaluate the taper connection strength of revision ceramic heads. Therefore, revision ceramic heads (Ø36 mm; adapter sleeve S) and standard ceramic heads (Ø36 mm; neck length S) were assembled with an axial load (2 kN) to titanium tapers with various damage modes (undamaged, truncated, and elevated). Subsequently, the heads were either pulled-off directly after assembly or after dynamic loading over 2.5 million cycles (sinusoidal 0.3 kN–3.0 kN). Pull-off forces of the revision heads (1.24 kN–1.66 kN) were up to 43.7% higher compared to standard heads (1.02 kN–1.48 kN) in dependency of the taper damage. After dynamic loading, the pull-off forces did not change in case of standard heads. The pull-off forces of the revision heads decreased in combination with the undamaged and truncated tapers but increased in combination with the elevated tapers. In conclusion, revision heads with adapter sleeves (size S) showed higher taper connection strength than standard heads both on undamaged and damaged tapers.

Adapter sleeves are essential for ceramic heads in hip revision surgery

BackgroundRemoving a head during isolated acetabular revision surgery can cause damage to the stem taper surface from extraction tool contact. Implanting a ceramic head on the damaged stem taper might elevate the fracture risk, which can be mitigated with the use of titanium adapter sleeves. The aim of this study was to investigate whether the improved fracture strength of modern generation ceramic heads allows the direct implantation on damaged stem tapers without an adapter sleeve. MethodsFinite element models of taper junctions with and without adapter sleeve were generated. Different stem taper damages were modelled to investigate the influence on the ceramic head fracture load under axial compression. FindingsHeads without adapter sleeves exhibited slightly higher or equal fracture strengths compared with sleeved heads for most scenarios. However, a small metal elevation on the stem taper caused a drastic decrease of the fracture strength if no adapter sleeve was used (−96%). The sleeved head was not influenced by the metal elevation damage. InterpretationAdapter sleeves are essential to ensure patient safety and prosthesis longevity whenever implanting ceramic heads on used stem tapers.

Registry study on failure incidence in 1,127 revised hip implants with stem trunnion re-use after 10 years of follow-up: limited influence of an adapter sleeve

Background and purpose — Little is known about the role of retained trunnions in revision hip arthroplasties, i.e., when only the femoral head is substituted. Wear (fretting corrosion) and ceramic head fractures are 2 poorly understood concerns related to use, and the role of adapter sleeves has not been defined. In this registry study we assessed the influence of sleeve interposition on re-revision rates in revision hip arthroplasties with retained stems. Confounding factors (demographics, implant-related features) and failures were also analyzed.Patients and methods — We conducted a registry study on 1,127 revised implants (retained trunnion and head exchange). In 26% of implants an adapter sleeve was interposed; in 74% no adapter sleeve was implanted. Demographic and implant-related features were investigated including a descriptive analysis of failures.Results — The mean follow-up of revised implants with and without the use of an adapter sleeve was 3.3 and 5.1 years, respectively. The implant survival without an adapter sleeve was significantly higher, 98.4% (95% CI 96.9–99.8) vs. 95.2% (CI 93.2–96.6) with an adapter sleeve at 5 years. No re-revisions due to adverse local tissue reactions or ceramic head fractures were reported. In order to overcome the different distribution of head materials and head sizes in the two cohorts, only Delta balls were investigated.Interpretation — Adapter sleeve interposition had a minor influence on the revision rates. No adverse local tissue reactions or head fractures occurred.

Impact of stem taper damage on the fracture strength of ceramic heads with adapter sleeves

BackgroundUsing a new ceramic head with a titanium adapter sleeve offers the possibility of maintaining a well fixed stem when conducting cup revision of a total hip arthroplasty. The aim of this study is to test the impact of stem taper damage on the fracture strength of sleeved ceramic heads. MethodsPristine zirconia-toughened alumina heads with titanium adapter sleeves (BIOLOX®OPTION System) were tested on damaged Ti-4Al-6V stem tapers in accordance with ISO7206-10. Four distinctive damage types classified as intolerable by the manufacture were investigated, representing various reductions in contact area between the stem taper and sleeve taper as well as damage incurred from previous ceramic head fracture. FindingsThe largest reduction in fracture strength occurred for a loss of contact for the entire length of the stem taper. Nonetheless, the fracture strength in all investigated cases was several times higher than that defined by the FDA standards. InterpretationThe use of a titanium sleeve recreates a uniform contact situation between the ceramic head and the outer sleeve taper in situations of damaged stem tapers. For the investigated damage types a high fracture strength of the ceramic head was maintained. This study supports the clinical use for sleeved ceramic heads in instances of greater damages of stem tapers than previously defined in order to spare patients from stem removal.

Adapter Sleeves Are Not Needed to Reduce the Risk of Fracture of a New Ceramic Head Implanted on a Well-Fixed Stem.

The purpose of this study was to assess (1) the prevalence of the fracture of ceramic heads implanted on used trunnions of well-fixed stems without using a titanium adapter sleeve; (2) the prevalence of trunnionosis secondary to fretting and/or corrosion at the trunnion of the well-fixed stem; and (3) clinical and radiographic results and the survival rate of the revised acetabular components. Eighty-eight patients (100 hips) underwent isolated revision of the acetabular components for polyethylene wear and osteolysis of the acetabulum. The study group consisted of 70 men and 18 women with a mean age of 52.8 years (range, 31-54 years) when the primary total hip arthroplasty was performed. Evidence of fretting and corrosion of the trunnion of all prostheses was examined macroscopically using a magnifying lens. Degree of fretting and corrosion of the trunnion was assessed using a 4-point scoring technique. A new 36-mm alumina delta ceramic head was implanted on the trunnion of a well-fixed stem without using a titanium adapter sleeve in all hips. The mean follow-up after revision of the acetabular component was 12.8 years (range, 10-14 years). Among the 100 new ceramic heads implanted on a well-fixed stem, no fracture of the ceramic head occurred at a mean follow-up of 12.8 years. The median fretting and corrosion scores for the trunnions were 1.5±1.1 and 1.3±0.9 points, respectively. The mean Harris hip score at the final follow-up was 89±15 points (range, 63-100 points). Survivorship of the revised acetabular components at 14 years was 95% (95% confidence interval, 87.6%-98.6%). [Orthopedics. 2018; 41(3):158-163.].

Investigation of metallic adapter sleeves for high throughput dilatometry on spherical micro samples

AbstractThe rods of an available quenching dilatometer are modified for investigations on spherical micro samples (Ø = 1 mm) via metallic adapter sleeves. The experiments can be seen as preliminary tests for a planned high throughput dilatometer, in which adapters are needed as well. Sleeve geometry and materials are varied in the trials to reproduce the transformation of the micro samples using standardized temperature measuring techniques. Sleeves made out of molybdenum produce the best results because molybdenum has a low and nearly constant thermal expansion up to 700 °C. Sleeves of nickel alloy 36 (Invar) or of an austenitic steel (1.4841) do not produce satisfying results. Thermally induced phase transformations of balls of 100Cr6 and X46Cr13 are successfully measured with the existing dilatometer for common macro samples. First the martensitic transformation is investigated, later the process is verified by the isothermal bainitic transformation of 100Cr6.

A System for Clearance Measurement of Bearings before and after Assembling

In this work, a method for measuring the radial clearance of bearings mounted on a shaft before and after assembling in an automatically and standardized way will be described. A setup was constructed, which enables to measure the radial clearance of different types of bearings with different dimensions. Tests with roller and ball bearings with tapered bore and adapter sleeves show that the developed system provides as good or better results than the manual test method. The results are reliable, objective, independent from the user and reproducible. Based on the results, the process of assembling could be readjusted. By using a closed loop method, it will be achieved that bearings will be mounted on a shaft with the specified radial clearance which is defined by the manufacturer of the bearing.

Ceramic Bearings with Titanium Adapter Sleeves Implanted During Revision Hip Arthroplasty Show Minimal Fretting or Corrosion: a Retrieval Analysis.

The BIOLOX® option system, consisting of a BIOLOX® delta ceramic femoral head with a titanium alloy adapter sleeve, is being increasingly utilized in revision hip arthroplasty. The sleeve protects the ceramic head from fracture and improper motion about the stem trunnion when a damaged trunnion is encountered at revision surgery. Corrosion and fretting due to metal-metal contact at the taper region of hip prosthesis create the potential of causing periprosthetic osteolysis and adverse local tissue reactions. The objective of this study was to identify the type and extent of damage to retrieved sleeves and ceramic heads to determine their in vivo performance. Twenty-four ceramic heads with titanium alloy sleeves were examined. The articular and taper surfaces for each ceramic head were assessed for metal transfer using a subjective grading system. All surfaces of the 24 titanium sleeves and stem trunnions (only available for 7 of 24 cases) were assessed for corrosion and fretting using an established grading system. Scanning electron microscopy and energy dispersive X-ray analysis were conducted on representative sample of sleeves. Fretting and corrosion were higher at the inner surface of the taper sleeve than the outer sleeve. Mean fretting scores at the inner taper and outer taper sleeve surfaces were 1.8 and 1.2, respectively. The mean corrosion score at the inner taper surface was 1.8; no corrosion was observed on the outer surface of any taper sleeve. SEM and EDS analyses provided further indications of low levels of damage. Fretting and corrosion were less severe than previously reported for conventional THA metal-metal taper connections, indicating that a ceramic head and titanium sleeve is a safe alternative in revision THA.

Fretting and Corrosion Damage in Taper Adapter Sleeves for Ceramic Heads: A Retrieval Study

BackgroundDuring revision surgery with a well-fixed stem, a titanium sleeve can be used in conjunction with a ceramic head to achieve better stress distribution across the taper surface. In vitro testing suggests that corrosion is not a concern in sleeved ceramic heads; however, little is known about the in vivo fretting corrosion of the sleeves. The purpose of this study was to investigate fretting corrosion in sleeved ceramic heads in retrieved total hip arthroplasties. MethodsThirty-seven sleeved ceramic heads were collected during revision. The femoral heads and sleeves were implanted 0.0-3.3 years. The implants were revised predominantly for instability, infection, and loosening. Fifty percent of the retrievals were implanted during a primary surgery. Fretting corrosion was assessed using the Goldberg-Higgs semiquantitative scoring system. ResultsMild-to-moderate fretting corrosion scores (score = 2-3) were observed in 92% of internal tapers, 19% of external tapers, and 78% of the stems. Severe fretting corrosion was observed in 1 stem trunnion that was previously retained during revision surgery and none of the retrieved sleeves. There was no difference in corrosion damage of sleeves used in primary or revision surgery. ConclusionThe fretting corrosion scores in this study were predominantly mild and lower than reported fretting scores of cobalt-chrome heads in metal-on-polyethylene bearings. Although intended for use in revisions, we found that the short-term in vivo corrosion behavior of the sleeves was similar in both primary and revision surgery applications. From an in vivo corrosion perspective, sleeves are a reasonable solution for restoring the stem taper during revision surgery.

Mechanical Stability of the Taper Connection of Large Metal Femoral Heads With Adapter Sleeves in Total Hip Arthroplasty Analyzed Using Explicit Finite Element Simulations

BackgroundLarge diameter heads (LDHs) of metal-on-metal bearings in total hip arthroplasty provide increased range of motion and reduced dislocation rates. However, major concerns grew over high wear rates from the modular connection between femoral stem and head, especially in combination with adapter sleeves. MethodsA computational study on the taper connection stability of LDH (50 mm) with adapter sleeves of different lengths (S, M, L, and XL) compared with a standard femoral head (32 mm) without adapter sleeves was conducted using explicit finite element analyses. Four different impact configurations were considered resulting from varied mallet mass (0.5 vs 1.0 kg) and velocity (1.0 vs 2.0 m/s). The taper stability was evaluated by determination of the pull-off forces and micromotions due to simulated joint loads during walking (2 kN and 7.9 Nm, respectively). Moreover, the deformations of the adapter sleeves and the contact area in the taper connections were evaluated. ResultsAlthough the pull-off forces of the LDH with different-sized adapter sleeves were comparable, contact area decreased and adapter sleeve deformations increased (up to 283%) with an increasing adapter sleeve length. Moreover, the micromotions of LDH with adapter sleeves were up to 7-times higher, as compared with the standard femoral head without an adapter sleeve. ConclusionThe present numerical study confirms that the assembly technique of LDH with adapter sleeves reveals increased micromotions compared with standard femoral head sizes. We could demonstrate that deviations of the stem trunnion geometry and improper surgical instructions led to worse mechanical stability of the taper connection.

The influence of stem taper re-use upon the failure load of ceramic heads

Ceramic components are frequently used in total hip replacement due to their good tribological properties. In revision of broken ceramic heads clinical uncertainties arise, whether the taper of the stem can be re-used with a new ceramic head, especially if the stem is well fixed. Ceramic is a brittle material. Even small damage on the male stem taper can lead to stress concentrations causing premature failure of a new ceramic head. As a consequence, manufactures strictly prohibit stem taper re-use for ceramic heads. The aim of this study was to determine the fracture strength of ceramic heads assembled to re-used male stem tapers, which were subjected to prior head fracture. Five 12/14 Ti6Al4V male tapers and 15 Al2O3 ceramic heads (BIOLOX forte®; ∅ 28 mm, L) were used for three consecutive fracture tests. Before and after every fracture test, all components were inspected visually and the surface geometry was analyzed. Mean fracture force (52.5 kN) did not decrease with the number of taper re-uses (p ≥ 0.77) but the range increased significantly from initially 4.1 kN to 31.8 kN for the first and 52.6 kN for the second re-use due to some components failing at very low loads. Visual inspection was not sufficient to predict the reduced failure loads. Ceramic heads should therefore not be put on used male tapers without metal adapter sleeves.

Pacing Leads & Adapter Sleeves Manufactured With Nonconforming Materials

Pacing Leads & Adapter Sleeves Manufactured With Nonconforming Materials

Machine for crimping adapter sleeves on rubber hoses

Machine for crimping adapter sleeves on rubber hoses