Standard Liners Research Articles

Large variability in degree of constraint of reverse total shoulder arthroplasty liners between different implant systems.

The liner design is a key determinant of the constraint of a reverse total shoulder arthroplasty (rTSA). The aim of this study was to compare the degree of constraint of rTSA liners between different implant systems. An implant company's independent 3D shoulder arthroplasty planning software (mediCAD 3D shoulder v. 7.0, module v. 2.1.84.173.43) was used to determine the jump height of standard and constrained liners of different sizes (radius of curvature) of all available companies. The obtained parameters were used to calculate the stability ratio (degree of constraint) and angle of coverage (degree of glenosphere coverage by liner) of the different systems. Measurements were independently performed by two raters, and intraclass correlation coefficients were calculated to perform a reliability analysis. Additionally, measurements were compared with parameters provided by the companies themselves, when available, to ensure validity of the software-derived measurements. There were variations in jump height between rTSA systems at a given size, resulting in large differences in stability ratio between systems. Standard liners exhibited a stability ratio range from 126% to 214% (mean 158% (SD 23%)) and constrained liners a range from 151% to 479% (mean 245% (SD 76%)). The angle of coverage showed a range from 103° to 130° (mean 115° (SD 7°)) for standard and a range from 113° to 156° (mean 133° (SD 11°)) for constrained liners. Four arthroplasty systems kept the stability ratio of standard liners constant (within 5%) across different sizes, while one system showed slight inconsistencies (within 10%), and ten arthroplasty systems showed large inconsistencies (range 11% to 28%). The stability ratio of constrained liners was consistent across different sizes in two arthroplasty systems and inconsistent in seven systems (range 18% to 106%). Large differences in jump height and resulting degree of constraint of rTSA liners were observed between different implant systems, and in many cases even within the same implant systems. While the immediate clinical effect remains unclear, in theory the degree of constraint of the liner plays an important role for the dislocation and notching risk of a rTSA system.

Do Constrained Liners (in a 145° onlay implant) Provide Any Benefit? A Matched Retrospective Study

The purpose of this study was to compare the outcomes of primary reverse total shoulder arthroplasty (rTSA) using constrained liners (in a 145° onlay implant, Exactech, Equinoxe) with primary rTSA using standard liners with a minimum 1-year follow-up. A total of 836 primary rTSA patients were analyzed in this study. Patients treated with constrained liners (n=209) were cross-matched 1:3 for age, gender, glenosphere diameter, and follow-up duration, and compared with 627 patients who underwent primary rTSA with standard liners. Study endpoint was at one year. Outcomes were analyzed preoperatively and at the latest follow-up. Patient characteristics, postoperative range of motion (ROM), patient reported outcomes (PROs), complications and revisions were recorded. There was no statistically significant changes in improvement in pain (-4.9 vs -5.1; p=0.356), ROM (abduction, 45.7° vs 47.9°; p=0.522) (forward elevation, 44.0 vs 50.8°; p=0.057) (internal rotation score 1.0 vs 1.1; p=0.709) (external rotation, 17.9° vs 16.7°; p=0.543), or PROs (American Shoulder and Elbow Surgeons Score, 44.5 vs 43.7; p=0.107) (Shoulder Arthroplasty Smart score, 27.5 vs 30.0; p=0.052) between the constrained and standard liner cohorts at minimum 1 year follow-up. However, the constrained liner rTSA cohort had a significantly higher rate of adverse events (6.2% vs. 2.7%; p=0.012), including a higher rate of scapular notching (15.6% vs. 8.8%; p=0.015). The utilization of constrained liners in primary rTSA demonstrated no significant difference in the change in pain, abduction, forward elevation, ER and IR scores, ASES scores, and SAS scores at minimum 1-year follow-up. There was no significant difference in forward elevation or abduction compared to standard liners. However, we observed that the overall rate of adverse events, including scapular notching were significantly higher in the constrained liner cohort. Long-term clinical and radiographic follow-up is necessary to fully elucidate the durability of these results. At this time, it is unclear if constrained liners have any benefit in rTSA.

Standard and special liner in primary hip arthroplasty : Current study and survey results from the German Arthroplasty Registry (EPRD)

Instability constitutes the main reason for revision hip arthroplasties. Modified polyethylene liners are designed to improve the stability of ahip replacement. In July 2022 The Bone & Joint Journal published astudy with data of the German Arthroplasty Registry (EPRD). The study investigated mechanical failure of standard and modified liner designs in primary, cementless total hip arthroplasty. Following the study, the EPRD conducted asurvey of German clinics to research the utilization of lipped liners in primary total hip replacement. The liner study included 151,096 primary, elective, cementless total hip arthroplasties. Data from November 2012 to November 2020 were obtained from the EPRD. Standard polyethylene liners were compared with lipped, angulated, offset and angulated/offset inlays. Cumulative incidences for endpoint revision due to mechanical complication were calculated with acompeting risk analysis. The influence of other variables was investigated with amultivariate Cox regression. In the following online survey, 237 out of 789 hospitals completed aform. In our analysis, only offset liners were, compared to standard liners, associated with areduced risk of mechanical failure in ashort to medium follow up. However, the resultant joint reaction force is increased with offset liners due to the lateralization of the hip center of rotation. Thus, the long-term performance of offset liners needs to be observed. Our survey indicated that lipped liners were implanted more often if the posterior approach was used. Moreover, lipped liners were mostly positioned with the elevated rim in the biomechanically less optimal posterior-superior quadrant. To improve stability it is suggested to position the elevated rim in the posterior-inferior quadrant.

No difference in range of motion in reverse total shoulder arthroplasty using standard or constrained liners: a matched cohort study.

Prosthetic instability is one of the most common short-term complications following reverse total shoulder arthroplasty (RTSA). Numerous strategies exist to attempt to mitigate this complication, including utilization of constrained polyethylene humeral liners. A concern of constrained humeral liners is that they may come at the expense of restricted rotational range of motion (ROM). The purpose of the present study is to compare range of ROM and patient-reported outcomes (PROs), and satisfaction among matched cohorts using constrained vs. unconstrained liners after RTSA. A multicenter shoulder arthroplasty registry was retrospectively reviewed to identify patients with two-year clinical follow-up after RTSA with constrained liners used at the surgeon's discretion. All patients had the same inlay humeral prosthesis with a 135° neck shaft angle. This study cohort was matched 1:2 to control patients who underwent RTSA with standard liners based on age, sex, total glenoid-sided lateralization, glenosphere diameter, and surgery performed on the dominant arm. Improvement in PROs and ROM was compared between groups. Twenty-two patients were identified who underwent RTSA with a constrained humeral liner; these were compared to 44 matched patients with standard liners. The groups were found to have no notable differences in demographics, baseline PROs and ROM. At two years postoperatively, both cohorts demonstrated improvements in all PROs without statistically significant differences between the two groups. There were no differences between groups in improvement in any ROM measure, including forward flexion (constrained: 54°, standard: 57°, P=.771), external rotation at the side (constrained: 42°, standard: 41°, P=.906) or internal rotation at 90° of abduction (constrained: 24°, standard: 20°, P=.587). For an inlay humeral prosthesis with a 135° neck shaft angle, utilization of a constrained liner for RTSA demonstrates no significant difference in ROM or PROs compared to a well-matched cohort of patients who underwent RTSA with a standard polyethylene humeral liner. These are reassuring data for using constrained liners when there is intraoperative concern for prosthetic instability.

Modified acetabular component liner designs are not superior to standard liners at reducing the risk of revision : an analysis of 151,096 cementless total hip arthroplasties from the German Arthroplasty Registry.

Registry studies on modified acetabular polyethylene (PE) liner designs are limited. We investigated the influence of standard and modified PE acetabular liner designs on the revision rate for mechanical complications in primary cementless total hip arthroplasty (THA). We analyzed 151,096 primary cementless THAs from the German Arthroplasty Registry (EPRD) between November 2012 and November 2020. Cumulative incidence of revision for mechanical complications for standard and four modified PE liners (lipped, offset, angulated/offset, and angulated) was determined using competing risk analysis at one and seven years. Confounders were investigated with a Cox proportional-hazards model. Median follow-up was 868 days (interquartile range 418 to 1,364). The offset liner design reduced the risk of revision (hazard ratio (HR) 0.68 (95% confidence interval (CI) 0.50 to 0.92)), while the angulated/offset liner increased the risk of revision for mechanical failure (HR 1.81 (95% CI 1.38 to 2.36)). The cumulative incidence of revision was lowest for the offset liner at one and seven years (1.0% (95% CI 0.7 to 1.3) and 1.8% (95% CI 1.0 to 3.0)). No difference was found between standard, lipped, and angulated liner designs. Higher age at index primary THA and an Elixhauser Comorbidity Index greater than 0 increased the revision risk in the first year after surgery. Implantation of a higher proportion of a single design of liner in a hospital reduced revision risk slightly but significantly (p = 0.001). The use of standard acetabular component liners remains a good choice in primary uncemented THA, as most modified liner designs were not associated with a reduced risk of revision for mechanical failure. Offset liner designs were found to be beneficial and angulated/offset liner designs were associated with higher risks of revision. Cite this article: Bone Joint J2022;104-B(7):801-810.

Dual-mobility implants prevent hip dislocation following hip revision in obese patients.

Revision total hip arthroplasty (THA) is associated with increased rates of dislocation in obese patients. It is not known whether dual-mobility implants decrease dislocation in these patients with obesity. We retrospectively reviewed two groups of revision THAs to compare the dislocation rate between 32 obese patients (BMI >30kg/m2) with standard cups, and 35 obese patients (BMI >30kg/m2) with dual-mobility cups. All patients received the same implants except for diameter head (32-mm head with standard cups and 28-mm head with dual mobility) and had the same cemented stem that was not changed at revision. The patients were followed at routine intervals and were specifically queried about dislocation. The two groups were similar in terms of age, gender, causes of revision and follow-up since the primary arthroplasty. With standard liners, more hips in obese patients dislocated than did hips in obese patients who received dual-mobility implants. The number of dislocations in standard hips was at one year follow-up 15.6% (5 of 32) compared with 0% in dual-mobility hips and was at five year follow-up 21.8% (7 of 32) compared with 2.8% (1 of 35). After a mean follow-up of sevenyears no cases of loosening were found. Five patients in the obese group with a standard liner underwent re-revision surgery, the additional re-operations being necessary to treat recurrent postoperative dislocation. Obese patients should be counselled about the important risk of dislocation that occurs with standard liners after revision THA. Dual-mobility liners in these patients with hip revision is an efficient technique to prevent post-operative hip dislocation.

Evaluation of temperature management and packaging options to reduce under-skin browning in ‘Honey Gold’ mango fruit

'Honey Gold' is an Australian mango cultivar with attractive skin colour and good flavour when ripe. Under-skin browning (USB) is a disorder that develops on 'Honey Gold' fruit after harvest. The disorder is usually not evident until fruit reach the wholesale market. Thus, fruit often need re-packing at the markets, causing considerable wastage and financial loss. Previous research suggested that USB results from an interaction between physical pressure (i.e., mechanical stress) and low temperature (i.e., physiological stress) during transport and distribution. To address this issue, fruit from three farms in the Northern Territory were either cooled to 13°C within 10 h of harvest, or held at 18-20°C for 1-2 days before cooling to 13°C. The fruit were packed within commercial fibreboard trays in either standard plastic liners, a 'softer' liner to potentially minimise fruit damage, or were individually wrapped in plastic or bubble wrap to prevent any damage. The fruit were then palletised and transported for three days to southern Australia in a refrigerated truck. Delaying cooling after harvest for two days reduced the incidence of USB by 52-85%. As compared to using standard liners and cooling immediately after harvest, the proportion of fruit with USB decreased from 25 to 3% when fruit packed with soft liners were held at 18-20°C for two days before cooling at 13°C and transporting. These findings show that reducing the risk of vibration damage by using soft liners in combination with a delay in temperature reduction after harvest can significantly reduce USB in commercial practice.

Analysis of the Results of Use of Bone Graft and Reconstruction Cages in a Group of Patients with Severe Acetabular Bone Defects

Introduction. Rings and cages are indicated for use in revision total hip with severe bone loss. Material and Methods. A retrospective study was performed on 37 acetabular revision cases with an average age at revision of 67.8 years. According to Paprosky classification, 54% grade II and 46% grade III. We used two types of cages, Protrusio and Contour cage. We used 23 standard liners and 14 dual mobility cups. Results. The average follow-up was 5.4 years. The mean Merlé-d’Aubigné score improved from 5.48 to 10.5 points (P<0.05). There were 10 nerve palsies, 6 rings that lost fixation, 10 dislocations, and 4 infections. The need for reoperation for any reason rose to 32% (12/37). Success, defined as a stable reconstruction, was 73%. We found that, using a dual mobility cup cemented into the cage, the dislocation rate and revision rate came down (P<0.05). Conclusions. The treatment of severe acetabular defects using bone graft and reconstruction cages is a viable option. The use of a dual mobility cup cemented into the cage could avoid dislocations and the insertion of the ischial flap inside the ischial portion of the acetabulum for further ring stability and protection of the sciatic nerve.

Primary total hip arthroplasty revision due to dislocation: Prospective French multicenter study

Dislocation following total hip arthroplasty (THA) may require surgical revision, and is one of the most frequent causes for revision in national registers. The goals of this study were to determine the characteristics of revision THA for dislocation and identify the typical features of hips revised due to dislocation. A prospective multicenter study (30 centers) was performed in first revision THA performed between January 1, 2010 and December 31, 2011 (multiple revisions were excluded). Two hundred nineteen (10.4%) of all first revisions (2153 cases in 2107 patients) were for dislocation, which was the fifth cause of revision. There were 135 men and 84 women, mean age 65.9 years old (24.3-92.4) at primary THA and 72.9 years old (31.9-98.8) at revision. Revision surgery was performed a mean 7.1 years (± 7.1) after primary THA. The predictive risk factors for dislocation were: a 22.2mm diameter femoral head (risk × 2.4), a posterolateral approach (risk × 1.7), older age (risk × 1.1), an elevated rim liner for primary THA (risk × 6.6). The use of a dual mobility cup did not influence the rate of revision for dislocation (8.8%) compared to the use of a flat rim liner (9.1%). The 10.4% rate of revision of THA for dislocation seems markedly lower than the results in the literature both for frequency and ranking. The use of elevated rim or constrained liners designed to decrease the risk of dislocation does not improve results compared to standard liners. Level IV, prospective prognostic study without a control group.

Subjective Evaluation of Novel Comfort Liners for Motorcycle Helmet

Motorcycle helmets manufactured in developing countries such as Tunisia are not specially designed, adapted or modified to provide extra comfort especially in hot and humid environment. In this study, three comfort liners manufactured from natural fibers are proposed and compared with standard liners. Subjective evaluation based on subject’s opinions and objective evaluation using liners characteristics: are used in this comparison. It was found that non woven liner made from wool and alfa fibre is more advantageous in term of comfort and acceptance than the other liner. It was judged comfortable, acceptable, not sweating and not hot. This result was confirmed by liners characteristics witch can convince helmet designer that more work is needed in this aspect.

Measurement of sound absorption coefficients of flat surfaces in a workshop

To improve the acoustic treatment of facings and provide appropriate solutions for noise control at workplace, it is necessary to develop methods of acoustic characterization of the walls in industrial halls. Sound absorption coefficient measurement in industrial rooms is however quite a difficult task because of the partially reverberant conditions. This work describes the measurement of the sound absorption coefficient of flat panels subject to small angle sound incidence, in an industrial hall using an experimental device equipped with an acoustic array. The directivity of this array has been optimized so that the major part of the received acoustic energy would come from one portion only of the investigated facing, this, in turn attenuating the reflected beams due to the reverberation. This new device includes an impulse sound source targeting the panels. The present article focuses mainly on the sound source design and implementation. It also describes some sound absorption measurements carried in a semi-anechoic chamber and in an industrial hall in order to examine the performance of the device. Sound absorption coefficients of several standard liners obtained through this device have been compared to those resulted from the two microphone technique.

The creep and wear of highly cross-linked polyethylene

The creep and wear behaviour of highly cross-linked polyethylene and standard polyethylene liners were examined in a prospective, double-blind randomised, controlled trial using radiostereometric analysis. We randomised 54 patients to receive hip replacements with either highly cross-linked polyethylene or standard liners and determined the three-dimensional penetration of the liners over three years. After three years the mean total penetration was 0.35 mm (SD 0.14) for the highly cross-linked polyethylene group and 0.45 mm (SD 0.19) for the standard group. The difference was statistically significant (p = 0.0184). From the pattern of penetration it was possible to discriminate creep from wear. Most (95%) of the creep occurred within six months of implantation and nearly all within the first year. There was no difference in the mean degree of creep between the two types of polyethylene (highly cross-linked polyethylene 0.26 mm, SD 0.17; standard 0.27 mm, SD 0.2; p = 0.83). There was, however, a significant difference (p = 0.012) in the mean wear rate (highly cross-linked polyethylene 0.03 mm/yr, SD 0.06; standard 0.07 mm/yr, SD 0.05). Creep and wear occurred in significantly different directions (p = 0.01); creep was predominantly proximal whereas wear was anterior, proximal and medial. We conclude that penetration in the first six months is creep-dominated, but after one year virtually all penetration is due to wear. Highly cross-linked polyethylene has a 60% lower rate of wear than standard polyethylene and therefore will probably perform better in the long term.

Infrared Thermography and Ultrasonography to Indirectly Monitor the Influence of Liner Type and Overmilking on Teat Tissue Recovery

Eight Danish Holstein cows were milked with a 1-mm thick specially designed soft liner on their right rear teat and a standard liner mounted under extra high tension on their left rear teat. Four of the animals were overmilked for 5 min. Rear teats were subjected to ultrasound examination on the first day and to infrared thermography on the second day. Teats were submersed in ethanol 20 min post-milking on the second day. Ultrasonography measurements showed that teat canal length increased by 30–41% during milking. Twenty minutes after milking, teats milked with modified standard liners still had elongated teat canals while teats milked with the soft liner were normalized. Overmilking tended to increase teat wall thickness. Approximately 80% of variability in teat canal length, from before teat preparation to after milking, could be explained by changes during teat preparation. Thermography indicated a general drop in teat temperature during teat preparation. Teat temperature increased during milking and continued to increase until the ethanol challenge induced a significant drop. Temperatures approached pre-challenge rather than pre-milking temperatures within 10 minutes after challenge. Teat temperatures were dependent on type of liner. Mid-teat temperatures post-challenge relative to pre-teat preparation were dependent on overmilking. Thermography and ultrasound were considered useful methods to indirectly and non invasively evaluate teat tissue integrity.