Eight-year wear analysis in Longevity highly cross-linked polyethylene liners comparing 26- and 32-mm heads

Dislocation after total hip arthroplasty: does head size really matter?

INTRODUCTION

Recent advances in polyethylene and ceramic technologies has allowed us to use larger sized heads without compromising the wear properties of a total hip arthroplasty (THA). 1 benefit of this change has been proposed to be a lower incidence of dislocation.

METHODS

We retrospectively evaluated the dislocation rate in 913 THAs performed using the same standardised surgical technique employed by a single team of surgeons at our institution between 1995 and 2015. Patients were assigned to 2 groups: small (⩽28 mm), large diameter heads (⩾36 mm and larger). The cup position was measured and plotted to determine its status according to the Lewinnek's safe zone (15° ± 10° for anteversion, 40° ± 10° for inclination).

RESULTS

16 of the 472 small heads dislocated (3.4%) while 5 of the 441 in large head group (1.1%) (p = 0.04). In all of the large head patients that dislocated the cup position was in the safe range of Lewinnek. However, in the large head group only 64.5% of the cups were in the safe zone.

CONCLUSIONS

By changing the head size to 36 mm, we were able to decrease the dislocation rate significantly. Errors of cup positioning according to Lewinnek became oblivious when using large heads. In our opinion, using large heads in THA makes a difference in terms of dislocation.

Minimum 10-Year Follow-Up of Cementless Total Hip Arthroplasty With a 32-mm Cobalt-Chromium Head on Highly Cross-Linked Polyethylene and a Tapered, Fiber Metal Proximally Coated Femoral Stem

BACKGROUND

The clinical and radiographic results of cementless total hip arthroplasty using a 32-mm cobalt-chromium head on remelted highly cross-linked polyethylene (HXLPE) and a tapered, fiber metal proximally coated femoral stem were evaluated at a mean follow-up of 12 years.

METHODS

A total of 57 cementless total hip arthroplasties using remelted HXLPE combined with a 32-mm cobalt-chromium head, and a tapered, fiber metal proximally coated femoral stem were performed from October 2004 to December 2006. Clinical evaluation was performed using the Merle d'Aubigné and Postel scoring system. Standardized anteroposterior and lateral radiographs of the pelvis and femur without weight-bearing were analyzed. Radiographic measurements of two-dimensional femoral head penetration into the polyethylene were performed with a computerized method. The steady-state wear rates were measured based on the radiographs from the first year after surgery to the final follow-up.

RESULTS

The mean Merle d'Aubigné and Postel score improved significantly from 10.7 points preoperatively to 15.6 postoperatively (P < .001). No osteolysis was found around the implant. Stem fixation in all cases showed stable bone ingrowth. Third-degree stress shielding was found in 46% of all stems. The total head penetration rate was 0.05 mm/y, and the steady-state wear rate was 0.01 mm/y. The Kaplan-Meier survivorship with the end point of revision was 95% (95% confidence interval, 85%-98%) at 12 years.

CONCLUSION

A 32-mm cobalt-chromium head on remelted HXLPE demonstrated low wear properties, and a tapered, fiber metal proximally coated femoral stem showed good results at long-term follow-up.

Neer Award 2017: wear rates of 32-mm and 40-mm glenospheres in a reverse total shoulder arthroplasty wear simulation model

BACKGROUND

Larger glenosphere diameters have been used recently to increase prosthesis stability and impingement-free range of motion in reverse total shoulder arthroplasty. The goal of this study was to evaluate the rate of polyethylene wear for 32-mm and 40-mm glenospheres.

METHODS

Glenospheres (32 mm and 40 mm, n = 6/group) and conventional polyethylene humeral liners underwent a 5-million cycle (MC) wear simulation protocol. Abduction-adduction and flexion-extension motion profiles were alternated every 250,000 cycles. At each interval, mass loss was determined and converted to volume loss and wear rate. At 0, 2.5 MC, and 5 MC, liners were imaged using micro-computed tomography to determine surface deviation. White light interferometry was performed on liners and glenospheres at 0 and 5 MC to quantify surface roughness. Wear particle morphology was characterized by environmental scanning electron microscopy.

RESULTS

Total volume loss was significantly higher in 40-mm liners from 1.5 MC onward (P < .05). Overall, volumetric wear rate was significantly higher in 40-mm liners compared with 32-mm glenospheres (81.7 ± 23.9 mm³/MC vs. 68.0 ± 18.9 mm³/MC; P < .001). However, micro-computed tomography surface deviation results demonstrated increased linear penetration on 32-mm glenospheres compared with 40-mm glenospheres (0.36 ± 0.03 µm vs. 0.28 ± 0.01 µm; P = .002). Surface roughness measurements showed no difference for liners; however, increased roughness was noted for 40-mm glenospheres at 5 MC compared with 32 mm (P < .05).

CONCLUSION

Larger glenospheres underwent significantly greater polyethylene volume loss and volumetric wear rates, whereas smaller glenospheres underwent greater polyethylene surface deviations. The enhanced stability provided by larger glenospheres must be weighed against the potential for increased polyethylene wear.

Thirteen-year wear rate comparison of highly crosslinked and conventional polyethylene in total hip arthroplasty: long-term follow-up of a prospective randomized controlled trial

BACKGROUND

The purpose of this study was to report the radiographic wear rates from a previous randomized controlled trial of first-generation highly crosslinked versus conventional polyethylene in total hip arthroplasty (THA) at a minimum of 13 years' follow-up.

METHODS

Patients returned for radiographic imaging and radiostereometric analysis (RSA). Radiographs were reviewed for the presence of osteolysis or component loosening. Femoral head penetration (which includes both wear and creep) was measured using RSA. We compared Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), 12-Item Short Form Health Survey (SF-12) and Harris Hip Scores (HHS) with preoperative values.

RESULTS

There was 1 revision in each group. There was no difference in WOMAC, SF-12, or HHS outcome scores between the highly crosslinked and conventional polyethylene groups (all p ≥ 0.13). Wear rate was lower with crosslinked polyethylene than conventional polyethylene (0.04 ± 0.02 mm/year v. 0.08 ± 0.03 mm/year, p = 0.007).

CONCLUSION

First-generation crosslinked polyethylene demonstrates greater wear resistance than conventional polyethylene after 13 years of implantation. Crosslinked polyethylene continues to outperform conventional polyethylene into the second decade of implantation.

Polyethylene Wear Associated With 26- and 32-mm Heads in Total Hip Arthroplasty: A Multicenter, Prospective Study

BACKGROUND

Although there were many clinical studies of highly cross-linked polyethylene (XLPE) wear among different femoral head diameters, few referred to thickness of XLPE in case larger femoral heads were used because smaller sockets were frequently used for Asian population.

METHODS

This prospective study included 240 hips that underwent primary total hip arthroplasty using XLPE combined with 26-mm (group S) or 32-mm (group L) cobalt-chromium head with maximum follow-up of 10 years. We measured 3-dimensional (3-D) linear penetration rate of XLPE among same implant design groups except head diameter and estimated the validity of thinner XLPE.

RESULTS

Our study demonstrated comparable 3-D linear penetration rates, which were 0.06 ± 0.07 mm/y for group S and 0.03 ± 0.02 mm/y for group L at 10 years after surgery and penetration rates seemed to be almost constant with no significant difference after 3 years. Minimum liner thickness (5.3 mm for 48-mm socket in combination with 32-mm femoral head) and the second thinnest XLPE (6.3 mm in case of socket from 50 mm to 54 mm combined with 32-mm femoral head) was distributed in 25% and 72% with group L, respectively, and there were no significant differences in penetration rates between 5.3-mm- and 6.3-mm-thickness groups.

CONCLUSION

Our study suggested that whether to select 26- or 32-mm diameters of femoral head does not affect XLPE wear in combination with this type of articulation.

Fixation and Wear With Contemporary Acetabular Components and Cross-Linked Polyethylene at 10-Years in Patients Aged 50 and Under

We evaluated the mid-term performance of a moderately cross-linked polyethylene THA bearing in younger patients. One hundred consecutive THAs performed in patients 50 years of age and under using the same cementless acetabular component and moderately cross-linked polyethylene were evaluated at minimum 10 year follow-up. At final follow-up 75 patients (89 hips) were living, 7 patients (7 hips) were deceased and 4 patients (4 hips) were lost to follow-up. Average Tegner and UCLA scores were 3.7 and 5.8, respectively. Average steps per year were 1.84 million. The average linear wear rate was 0.05 mm/y and steady state wear rate was 0.033 mm/y. There was no detectable osteolysis. Minimum 10 year follow-up demonstrated durable fixation and reduced wear (P<0.001) when compared to our historical controls.

Numerical analysis of the biomechanical complications accompanying the total hip replacement with NANOS-Prosthetic: bone remodelling and prosthesis migration

Aseptic loosening of the prosthesis is still a problem in artificial joint implants. The ýloosening can be caused by the resorption of the bone surrounding ýthe prosthesis according to stress shielding. A numerical model was developed and validated by means of DEXA-studies in order to ýanalyse the bone remodelling process in the periprosthetic bone. A total loss of about 3.7% of the bone density in the periprosthetic Femur with NANOS is computed. The bone remodelling calculation was validated by means of a DEXA-study with a 3-years-follow-up. The model was further developed in order to be able to calculate and consider the migration of the implants. This method was applied on the ýNANOS-implant with a computed total migration of about 0.43 mm. These calculations showed good results in comparison with a 2-year-follow-up clinical study, whereby a RSA-method was used to determine the stem migration in the bone. In order to ýstudy the mutual influence between the implant migration and the hip contact forces ý, a software is developed by our scientific group to couple a multi body simulation (MBS) of human lower limps with the FEA of the periprosthetic Femur.

Fixation and wear with a contemporary acetabular component and cross-linked polyethylene at minimum 10-year follow-up

Long term total hip arthroplasty follow-up has demonstrated bearing surface wear and failure of fixation as the major modes of failure. The purpose of this study was to evaluate the minimum 10year results of a third generation cementless acetabular component using moderately cross-linked polyethylene liners. 150 primary THAs were evaluated clinically for need for revision and activity evaluated using accelerometers, WOMAC, Tegner and UCLA activity-level scores. Radiographs were evaluated for wear, osteolysis and loosening. We compared this cohort to three of our previously reported cohorts. The only revision was unrelated to liner wear and all acetabular components were bone ingrown. There were no cases of acetabular osteolysis and one case of femoral osteolysis. Average steps per year were 1.59 million. Mean steady state wear rate averaged 0.04mm/year. At 10-years, excellent fixation and low wear were demonstrated using a cementless acetabular construct and moderately cross-linked polyethylene liner.

LEVEL OF EVIDENCE

Therapeutic study, Level III (retrospective comparative study-prospective cohort with historical control).

Raman spectroscopic study of remelting and annealing-induced effects on microstructure and compressive deformation behavior of highly crosslinked UHMWPE for total hip arthroplasty

Three-dimensional crystallographic morphologies were studied by means of confocal/polarized Raman spectroscopy as developed upon manufacturing in three different types of first and second generation highly crosslinked UHMWPE (HXLPE) acetabular liners. The impact of such microstructural characteristics on the deformation behavior of the liners was also evaluated and discussed from the viewpoint of molecular chain mobility. All the investigated liners showed similar microstructural transitions within the first 35 μm below their surfaces in terms of crystallinity, molecular orientation, and crystalline anisotropy. Interestingly, different postirradiation heat treatments (remelting or annealing in single step or in sequential steps) led to clear differences in the subsurface microstructure among the three liners. Remelted liner possessed both lower bulk crystallinity and degree of molecular orientation as compared to the annealed liners. Sequentially, irradiated/annealed liner showed the highest degree of crystallinity and orientation among the studied liners. The peculiar microstructure of this latter liner exhibited the highest restoring (shape-recovery) force against the applied uniaxial strain. Accordingly, the present study suggests that the sequential irradiation and annealing offers an efficient way to obtain microstructure quite suitable for attaining high creep resistance. However, all the investigated liners exhibited the significantly low values of surface anisotropy, which could be equally efficient in minimizing strain-softening-assisted wear phenomena.

Jogging after total hip arthroplasty

BACKGROUND

Jogging has been classified as a high-impact sport, and jogging after total hip arthroplasty (THA) has not been well documented.

PURPOSE

To investigate the participation rate for postoperative jogging as well as jogging parameters and the influence of jogging on implant stability and bearing wear.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Included in this study were 804 hips in 608 patients (85 men, 523 women) who underwent THA between 2005 and 2011 with follow-up longer than 1 year. The mean patient age was 62 years (range, 26-98 years), and mean follow-up duration was 4.8 years (range, 2.3-7.8 years). Hip resurfacing arthroplasty (HRA) was performed in 81 patients and conventional THA in 527 patients. During routine postsurgical visits, patients were given a questionnaire concerning preoperative and postoperative jogging routines. For joggers, frequency, distance, duration, and velocity of jogging were recorded. Patients who did not jog postoperatively were asked to provide reasons for not jogging. Radiographs concerning implant migration and polyethylene wear were evaluated with specialized software, and serum cobalt and chromium ion concentrations were investigated for patients with metal-on-metal articulation.

RESULTS

A total of 33 patients (5.4%) performed jogging preoperatively, and 23 patients (3.8%) performed jogging postoperatively. Of the 23 who jogged postoperatively, conventional THA was performed in 13 patients and HRA in 10 patients. Postoperatively, joggers trained a mean of 4 times (range, 1-7 times) per week, covering a mean distance of 3.6 km (range, 0.5-15 km) in a mean time of 29 minutes (range, 5-90 minutes) per session and at a mean speed of 7.7 km/h (range, 3-18 km/h). No patient complained of pain or showed serum cobalt and chromium ion elevation greater than 7 ppb. No hip showed loosening, abnormal component migration, or excessive wear at a mean 5-year follow-up. There were 74 postoperative non-joggers with an interest in jogging. The reasons given for avoiding jogging included anxiety (45 patients; 61%); impossible because of several reasons, including pain, decreased range of motion, and muscle weakness (18 patients; 24%); and lumbar or knee pain (11 patients; 15%). Multivariate analysis revealed that male sex and a history of preoperative jogging demonstrated significant relationships with postoperative jogging.

CONCLUSION

A total of 3.8% of THA patients participated in postoperative jogging. Short-term postoperative follow-up did not identify any negative influence of jogging on implant survival.

Uncemented third-generation ceramic-on-ceramic total hip arthroplasty using metal acetabular shell with direct taper locking liner

BACKGROUND

The ceramic-on-ceramic (CoC)-bearing couple in total hip arthroplasty (THA) was developed to reduce the wear debris and osteolysis. Although the mechanical strength of third-generation ceramic has improved over previous generations, the risk of osteolysis and ceramic fracture is still an important concern.

METHODS

We studied 124 uncemented THAs with third-generation CoC-bearing couple implanted between 2000 and 2004. The ceramic liner and head were secured with the direct taper locking mechanism. One hundred and eleven hips were followed-up for minimum of 8 years, with an average follow-up period of 10.1 years (range 8.0-12.8 years). Patients were evaluated with a particular emphasis on the prevalence of the osteolysis and the ceramic fracture.

RESULTS

The survivorship with the end point as implant revision for any reason was 94.9 % (95 % confidence intervals 90.0-99.3 %) at 12.8 years. Revisions were performed because of one ceramic liner fracture, three dislocations, and two deep infections. No radiographic evidence of wear or osteolysis was observed. The preoperative Merle d'Aubigne and Postel hip score increased from 11.6 to 17.1.

CONCLUSIONS

Patients, who received third-generation CoC THA had no detectable wear and osteolysis. One ceramic fracture occurred, and the main reason for revision was dislocation.

Ideal femoral head size in total hip arthroplasty balances stability and volumetric wear

BACKGROUND

Over the last several years, a trend towards increasing femoral head size in total hip arthroplasty to improve stability and impingement free range of motion has been observed.

PURPOSE

The specific questions we sought to answer in our review were: (1) What are the potential advantages and disadvantages of metal-on-metal, ceramic-on-ceramic, and metal-on-polyethylene bearings? (2) What is effect that femoral head size has on joint kinematics? (3) What is the effect that large femoral heads have on bearing surface wear?

METHODS

A PubMed search and a review of 2012 Orthopaedic Research Society abstracts was performed and articles were chosen that directly answered components of the specific aims and that reported outcomes with contemporary implant designs or materials.

RESULTS

A review of the literature suggests that increasing femoral head size decreases the risk of postoperative dislocation and improves impingement free range of motion; however, volumetric wear increases with large femoral heads on polyethylene and increases corrosion of the stem in large metal-on-metal modular total hip arthroplasty (THA); however, the risk of potentially developing osteolysis or adverse reactions to metal debris respectively is still unknown. Further, the effect of large femoral heads with ceramic-on-ceramic THA is unclear, due to limited availability and published data.

CONCLUSIONS

Surgeons must balance the benefits of larger head size with the increased risk of volumetric wear when determining the appropriate head size for a given patient.