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Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_9 | Pages 69 - 69
1 Oct 2020
Lawrie CM Barrack RL Nunley RM
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Introduction. Bone mineral density (BMD) is correlated with component migration and aseptic loosening after total knee arthroplasty (TKA). Older implant designs have demonstrated BMD loss up to 23% in the first 6 months after TKA, and continued to BMD decline at an average of 5% per year for as long as 2 years after TKA. The impact of component design and fixation method on BMD loss after TKA in modern implant designs has not been fully elucidated. The purpose of this study is to determine the effect of tibial tray thickness and fixation method (cemented versus cementless) on BMD loss patterns of the proximal tibia in two different modern TKA implant systems. Methods. A prospective, nonrandomized, single center study of patients undergoing primary TKA by one of two surgeons was performed with four study cohorts: cemented DePuy Attune, cementless DePuy Attune, cemented Stryker Triathlon, cementless Stryker Triathlon. Target sample size was 80, with 20 per cohort based on adhoc power analysis. Exclusion criteria included: age over 75, BMI >40, inflammatory arthritis, previous knee surgery involving the femur, tibia or tibial bone, and diagnosis of osteopenia/osteoporosis. Implant fixation type was based on surgeon intraoperative assessment of patient bone quality. Demographic data was collected preoperatively. Dual Energy X-ray Absorptiometry (DEXA) Bone Density Monitoring was performed at 6 weeks and one year postoperatively. Bone mineral density was calculated from the DEXA scans for 4 zones for the tibia relative to the keel or central peg: anterior, posterior, medial and lateral. Results were reported as BMD at 1 year postoperatively as a percentage of BMD at 6 weeks postoperatively. Results. 81 knees with complete DEXA studies at 6 weeks and 1 year postoperatively were available for analysis. The mean (SD) age at the time of surgery was 65.4 years (6.1), with 39 men and 42 women and a mean (SD) BMI of 31.2 kg/m. 2. (4.7). The patients who received cementless implants were significantly younger with a mean (SD) age of 62.1 (6.0) than those who received cemented implants with a mean age of 69.1 (3.7) (p < 0.05). There was no difference in age between implant type (p > 0.05). There was no difference in BMI or gender distribution between implant types or fixation type (p > 0.05). There was no significant difference in mean BMD loss between 6 weeks and 1 year postoperatively between the cemented and cementless Triathlon in any zone, between the cemented Triathlon and Attune in any zone, the cementless Triathlon and Attune in any zone, and the cemented and cementless attune in the lateral, anterior and posterior proximal tibia (p > 0.05). There was significantly more BMD loss seen in the medial tibia in the cemented (BMD at 1 year 88% of BMD at 6 weeks) than cementless (BMD at 1 year 103% of BMD at 6 weeks) Attune (p = 0.043). Conclusion. BMD loss at 1 year postoperatively versus 6 weeks postoperatively after TKA with two modern implant designs is not significantly affected by tibial tray thickness. BMD loss was unaffected by fixation type for the Stryker Triathlon, but was significant less for the cementless DePuy Attune than the cemented version


Bone & Joint Research
Vol. 11, Issue 5 | Pages 252 - 259
1 May 2022
Cho BW Kang K Kwon HM Lee W Yang IH Nam JH Koh Y Park KK

Aims. This study aimed to identify the effect of anatomical tibial component (ATC) design on load distribution in the periprosthetic tibial bone of Koreans using finite element analysis (FEA). Methods. 3D finite element models of 30 tibiae in Korean women were created. A symmetric tibial component (STC, NexGen LPS-Flex) and an ATC (Persona) were used in surgical simulation. We compared the FEA measurements (von Mises stress and principal strains) around the stem tip and in the medial half of the proximal tibial bone, as well as the distance from the distal stem tip to the shortest anteromedial cortical bone. Correlations between this distance and FEA measurements were then analyzed. Results. The distance from the distal stem tip to the shortest cortical bone showed no statistically significant difference between implants. However, the peak von Mises stress around the distal stem tip was higher with STC than with ATC. In the medial half of the proximal tibial bone: 1) the mean von Mises stress, maximum principal strain, and minimum principal strain were higher with ATC; 2) ATC showed a positive correlation between the distance and mean von Mises stress; 3) ATC showed a negative correlation between the distance and mean minimum principal strain; and 4) STC showed no correlation between the distance and mean measurements. Conclusion. Implant design affects the load distribution on the periprosthetic tibial bone, and ATC can be more advantageous in preventing stress-shielding than STC. However, under certain circumstances with short distances, the advantage of ATC may be offset. Cite this article: Bone Joint Res 2022;11(5):252–259


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 131 - 131
1 Dec 2013
Murphy J Courtney P Lee G
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Proper restoration of posterior condylar offset during TKA has been shown to be important to maximize range of motion and minimize flexion instability. However, there is little information as to the importance of restoration of mid-sagittal femoral geometry. There is controversy as to whether a TKA prosthesis should have a single radius or multiple radii of curvature. The purpose of this study is to evaluate the effectiveness of a multi-radius femoral component at restoring mid sagittal femoral offset. A consecutive series of 100 TKAs with digital preoperative and postoperative radiographs and standardized radiographic markers were analyzed. There were 71 female and 29 male knees with mean age of 59 years. All TKAs were performed by a single surgeon using a multi-radius femoral component design. The distal femoral resection was set to resect 10 mm from the distal femoral condyle and a posterior referencing system was used to size the femoral component. Using radiographic perfect lateral projections of the knees, a line was drawn along the posterior femoral shaft and another parallel line down the anterior femoral shaft. A 3rd line was then drawn parallel to the posterior shaft at the furthest point posterior on the condyle. A 4th line was drawn parallel to the anterior shaft at the furthest point anterior on the femur. 90 degree angles were constructed to create a grid in the anterior and posterior directions, similar to a previously reported technique. Finally, 45 degree angle lines were created in the grid to assess mid flexion dimensions [Fig-1 and 2]. The percent change in posterior condylar offset (PCO), anterior femoral offset (AFO), mid femoral anterior offset (MAFO) and mid femoral posterior offset (MFPO) were calculated. The mean reproduction of the mid-anterior femoral offset and mid-posterior femoral offset were 101.1% [range 56.5%–167.5%] and 96.8% [range 54.9%–149.0%] of preoperative measurements respectively. The average restoration of posterior offset and anterior offset were 92.8% [range 49.0%–129.8%] and 115.3% of preoperative measurements [range 35.7%–400.0%] respectively. When the posterior condylar offset was restored to within 10% of the native anatomy, the MPFO restoration more closely resembled normal anatomy (103.0% vs. 93.9%, p = 0.005). When the postoperative posterior condylar offset was decreased greater than 20%, both the MAFO (90.1% vs. 104.5%, p = 0.004) and MPFO (78.5% vs. 102.9%, p < 0.001) decreased compared to the native knee. There was no relationship between restoration of the PCO and the MAFO correction (104.6% vs. 99.4%, p = 0.213). Finally, there was no correlation between restoration of anterior femoral offset within 10% of normal and the restoration of mid sagittal femoral offset; 98.0% vs 102.0% for MAFO (p = 0.320) and 98.7% vs 96.3% for MPFO (p = 0.569). A modern multi-radius condylar knee design is capable of reproducing the mid-sagittal geometry of the preoperative knee. However, the restoration of mid sagittal offset is largely dependent on the restoration of the posterior condylar offset. Intraoperative adjustments in anterior and posterior femoral resections can have significant impact in the ability of the implant to reproduce mid-sagittal femoral anatomy


The Bone & Joint Journal
Vol. 102-B, Issue 6 | Pages 709 - 715
1 Jun 2020
Abdelsamie KR Elhawary I Ali H Ali M EL-Shafie M Dominic Meek RM

Aims

Femoral revision component subsidence has been identified as predicting early failure in revision hip surgery. This comparative cohort study assessed the potential risk factors of subsidence in two commonly used femoral implant designs.

Methods

A comparative cohort study was undertaken, analyzing a consecutive series of patients following revision total hip arthroplasties using either a tapered-modular (TM) fluted titanium or a porous-coated cylindrical modular (PCM) titanium femoral component, between April 2006 and May 2018. Clinical and radiological assessment was compared for both treatment cohorts. Risk factors for subsidence were assessed and compared.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 159 - 160
1 Mar 2010
Sang-Jin P Eun-Kyoo S Jong-Keun S Young-Jin K Chang-Ick H Young-Hoon P
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Introduction: ROM after TKA can be influenced by multi-factors such as preoperative range of motion, body habitus, implant design, intraoperative surgical technique, and postoperative rehabilitation. Recently many implant manufacturers have made modifications to traditional total knee designs to improved maximal knee flexion and range of motion. Some posterior cruciate ligament (PCL) stabilized total knee prostheses that incorporate design features intended to improve knee kinematics in high flexion were introduced and the use of these prostheses has attracted attention. Recently in the cruciate retaining (CR) prosthesis, high-flexion knee (CR-Flex) and gender-specified prosthesis were designed to allow a greater and safer flexion after TKA. The aim of this study was to evaluate the effect of cruciate retaining typed different femoral component design on knee range of motion using a computerized navigation system. Materials & method: 30 patients who underwent primary TKA because of primary osteoarthritis were included. EM navigation system was used in all cases. After tibia and femoral cutting using standard CR cutting block, standard fixed bearing CR knee (NexGen CR, Zimmer, Warsaw, IN) trial was inserted. If surgeon is satisfactory with alignment, stability and ligament balancing, the maximal knee extension and flexion was recorded using gravity by navigation system. Then, high-flexion fixed bearing CR knees(NexGen CR-Flex and Gender solution NexGen CR-Flex knee, Zimmer, Warsaw, IN) trial was inserted after additional posterior cutting. The maximal knee extension and flexion was evaluated exactly same way. Results: Preoperative mean varus deformity was 10.52°. The mean flexion contracture was 7.52±6.81° and further flexion 129.9±7.94°. The average intraoperative maximal flexion of NexGen CR was 133.5±5.35° (125–146°) and that of hyper-flexion design were 135.5±5.77°(125–147°) in Nexgen CR-Flex and 136.1±5.76°(126–146°) in Gender knee. All knees showed greater than 125° of flexion regardless of the implant design. All knees can achieve physiologic leg alignment and nearly full extension of the knee after operation. Conclusion: Hyper flexion designs showed subtle increase in mean maximal flexion and overall range of motion of the knee compared with the standard design, when it measured using navigation system intraoperatively. But clinically, it is not certain that these differences can lead to significant improvement of range of motion


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVIII | Pages 161 - 161
1 Sep 2012
Waddell JP Edwards M Lutz M Keast-Butler O Escott B Schemitsch EH
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Purpose

To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

Method

All patients undergoing primary total hip replacement surgery at our institution are entered prospectively into a database which includes history and physical examination, radiology, WOMAC and SF-36 scores. The patients are re-examined, re-x-rayed and re-scored at 3 months, 6 months and 1 year after surgery and yearly thereafter.

Using this database we are able to identify patients who have undergone total hip replacement using one of two geometric variants of the acetabular component. The first design is hemispherical and the second design has a peripheral rim expansion designed to increase initial press-fit stability.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XLI | Pages 142 - 142
1 Sep 2012
Edwards M Lutz M Keast-Butler O Escott B Schemitsch E Waddell J
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To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

All patients undergoing primary total hip replacement surgery at our institution are entered prospectively into a database which includes history and physical examination, radiology, WOMAC and SF-36 scores. The patients are re-examined, re-x-rayed and re-scored at 3 months, 6 months and 1 year after surgery and yearly thereafter.

Using this database we are able to identify patients who have undergone total hip replacement using one of two geometric variants of the acetabular component. The first design is hemispherical and the second design has a peripheral rim expansion designed to increase initial press-fit stability.

Five hundred and twenty-seven consecutive primary total hip replacements were identified using either of the geometric variants of the acetabular component. Results at a mean of 7 years revealed a 95.6% survivorship with no significant difference between the two component designs with revision for aseptic loosening as the end point. Functional scores between the two groups of patients also demonstrated no statistically significant difference.

Radiologic assessment, however, showed a difference between the two designs. The hemispherical design which matches the reamer line-to-line had 80% complete osseointegration on final radiologic review while the second design with a peripheral rim expansion had only 57% complete osseointegration. This was statistically significant. The peripherally expanded components also had a greater number of screws inserted at the time of surgery, felt by us to be a reflection of initial surgeon dissatisfaction with component stability at the time of insertion of the component.

The difference in screw numbers was also statistically significant. This study demonstrates that a hemispherical design with line-to-line contact between the acetabular component surface and the acetabular bone is statistically superior in terms of bone ingrowth and probably statistically superior in terms of initial press-fit stability when compared to a peripherally expanded component.

Peripherally expanded components appear to offer no advantage over hemispherical components in terms of clinical outcome and are statistically inferior to hemispherical components in radiologic parameters at 7 years follow-up.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXV | Pages 172 - 172
1 Jun 2012
Waddell J Edwards M Lutz M Keast-Butler O Escott B Schemitsch E Nikolaou V
Full Access

Purpose

To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

Materials & Methods

All patients undergoing primary total hip replacement surgery at our institution are entered prospectively into a database which includes history and physical examination, radiology, WOMAC and SF-36 scores. The patients are re-examined, re-x-rayed and re-scored at 3 months, 6 months and 1 year after surgery and yearly thereafter.

Using this database we are able to identify patients who have undergone total hip replacement using one of two geometric variants of the acetabular component. The first design is hemispherical and the second design has a peripheral rim expansion designed to increase initial press-fit stability.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 105 - 105
1 Mar 2010
Fetto J Leali A Iguchi H
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This is a report on the first 100 THR patients treated with an off the shelf version of a novel “Lateral Flare” femoral component. A prior published report has documented the up to 19 year follow up of custom fabricated stems of an identical design concept as being successful in patients < 55 years of age.

HHS, radiographic measure of bone morphology, implant stability and densitometric measure of bone response after THR with an off the shelf version, “Revelation Lateral Flare”, femoral component, confirm excellent bone preservation and implant stability with this design concept. DEXA analysis of a 20 consecutive patient subset of these 100 patients, documented preservation of more than 95% of proximal femoral bone stock in Gruen zone 1 and 102% of total bone stock in Gruen zones 1–7. Implant stability measurement documented < 0.5mm of subsidence in spite of patients being permitted immediate post-operative full weight bearing activity.

These findings support reasonable optimism for expectation of successful long term results being achievable with the use of an off the shelf version of the “Lateral Flare” design concept, in young, high demand patients suffering with early onset osteoarthrosis of the hip.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXV | Pages 134 - 134
1 Jun 2012
Mahindra P Yamin PM Garg PR Selhi HS Singla S
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Background

There is paucity of data concerning the morphological dimensions of the distal part of the femur and the proximal part of the tibia in Indian population. The objective of this study was to analyse the exact anatomic data collected from patients undergoing total knee arthroplasty.

Methods

Morphologic data from the distal part of the femur and proximal part of the tibia, from 50 knees, were obtained during total knee Arthroplasty, with a microcalliper. The study included 30 women and 20 men, who had a mean age of 65 years. A characterisation of the aspect ratio (the medial-lateral to anterior-posterior dimensions) was made for the proximal aspect of the tibia and distal part of the femur.


The Bone & Joint Journal
Vol. 106-B, Issue 3 Supple A | Pages 115 - 120
1 Mar 2024
Ricotti RG Flevas DA Sokrab R Vigdorchik JM Mayman DJ Jerabek SA Sculco TP Sculco PK

Aims. Periprosthetic femoral fracture (PPF) is a major complication following total hip arthroplasty (THA). Uncemented femoral components are widely preferred in primary THA, but are associated with higher PPF risk than cemented components. Collared components have reduced PPF rates following uncemented primary THA compared to collarless components, while maintaining similar prosthetic designs. The purpose of this study was to analyze PPF rate between collarless and collared component designs in a consecutive cohort of posterior approach THAs performed by two high-volume surgeons. Methods. This retrospective series included 1,888 uncemented primary THAs using the posterior approach performed by two surgeons (PKS, JMV) from January 2016 to December 2022. Both surgeons switched from collarless to collared components in mid-2020, which was the only change in surgical practice. Data related to component design, PPF rate, and requirement for revision surgery were collected. A total of 1,123 patients (59.5%) received a collarless femoral component and 765 (40.5%) received a collared component. PPFs were identified using medical records and radiological imaging. Fracture rates between collared and collarless components were analyzed. Power analysis confirmed 80% power of the sample to detect a significant difference in PPF rates, and a Fisher’s exact test was performed to determine an association between collared and collarless component use on PPF rates. Results. Overall, 17 PPFs occurred (0.9%). There were 16 fractures out of 1,123 collarless femoral components (1.42%) and one fracture out of 765 collared components (0.13%; p = 0.002). The majority of fractures (n = 14; 82.4%) occurred within 90 days of primary THA. There were ten reoperations for PPF with collarless components (0.89%) and one reoperation with a collared component (0.13%; p = 0.034). Conclusion. Collared femoral components were associated with significant decreases in PPF rate and reoperation rate for PPF compared to collarless components in uncemented primary THA. Future studies should investigate whether new-generation collared components reduce PPF rates with longer-term follow-up. Cite this article: Bone Joint J 2024;106-B(3 Supple A):115–120


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_20 | Pages 3 - 3
12 Dec 2024
Bhalekar R Wells S Nargol M Nargol A Waller S Wildberg L Sidaginamale R Langton DJ
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Objectives. Unicompartmental knee replacement (UKR) is a conservative option for degenerative disease, with mobile (Oxford UKR) and fixed bearing (Physica ZUK) the most commonly used devices. The primary reasons for revising UKRs include disease progression (36.9%), loosening (31.7%), and pain (7.5%). Loosening typically occurs due to osteolysis caused by wear particles from the polyethylene (PE) inserts. There is limited published literature which has quantified volumetric material loss from the PE inserts of cemented fixed-bearing UKRs. This study aimed to quantify bearing wear and backside deformation of these PE components. Design and Methods. At our national retrieval centre, we measured changes volumetric bearing wear and backside deformation of 31 explanted fixed-bearing Physica ZUK UKR PE inserts using a peer-reviewed methodology based on coordinate measuring machine analysis. These explants had been revised for any indication [Females (19) and Males (12)]. The location of the wear scars was identified and mapped. We compared the volumetric wear from the bearing surface with contemporary total knee replacement (TKR) inserts. Results. The median (IQR) total volumetric wear of the UKR PEs [96(50-152) mm. 3. ] was significantly higher (p<0.001) than contemporary TKR PEs [40 (24-83) mm. 3. ]. The median (IQR) total volumetric wear of the PEs in males [148(122-200) mm. 3. ] was significantly higher(p=0.016) than in females [56(61-119) mm. 3. ]. The wear scars were situated in the anterior third in 61% of cases, with 26% located posteriorly. Examination of the PE backside surfaces exhibited damage in the area directly inferior to the bearing surface wear scar in the majority of cases. Conclusion. In conclusion, this study highlights significant PE wear of Physica ZUK UKR inserts, with higher wear rates compared to contemporary TKR inserts, particularly in males


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_1 | Pages 29 - 29
2 Jan 2024
Bojan A Procter P Karami P Pioletti D
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The fixation of articular fractures, with many small osteochondral fragments, is a challenging unmet need where a bone adhesive would be a useful adjunct to standard treatments. Whilst there are no such adhesives in current clinical use, preclinical animal models have demonstrated good healing of bone in unloaded models using an adhesive based on phosphoserine modified calcium phosphate cement (PM-CPC). An ex-vivo human bone core model has shown that this adhesive bonds freshly harvested human bone. To confirm this adhesive is capable of supporting loaded osteochondral fragments a porcine model has been developed initially ex-vivo on the path to an in-vivo study. In this model bone cores, harvested from the medial knee condyle, are glued in place with the adhesive. In-vivo adjacent pairs of bone cores would be replaced with adhesive and a control with conventional pin fixation respectively. As osteochondral bone fragments have both bone and cartilage components, this suggested a dual adhesive strategy in which components designed for each tissue type are used. This concept has been explored in an ex-vivo porcine pilot study presented herewith. At the subchondral bone level, the PM-CPC was used. At the cartilage level, a second adhesive, a methacrylated phosphoserine containing hyaluronic acid (MePHa) hydrogel designed specifically for soft tissues was applied. This is a challenging model as both adhesives have to be used simultaneously in a wet field. The pilot showed that once the subchondral component is glued in place, the PM-CPC adhesive intruding into the cartilage gap can be removed before applying the cartilage adhesive. This enabled the MePHa adhesive to be injected between the cut cartilage edges and subsequently light-cured. This two-stage gluing method is demanding and an in-vivo pilot is necessary to perfect and prove the operative technique. Acknowledgements: The human bone core project was partially financed by Innovation Fund of Västra Götaland Region, Sweden. The MePHa hydrogel work was supported by a Swiss National Fund grant # CR23I3_159301


The Bone & Joint Journal
Vol. 102-B, Issue 6 Supple A | Pages 66 - 72
1 Jun 2020
Knapp P Weishuhn L Pizzimenti N Markel DC

Aims. Postoperative range of movement (ROM) is an important measure of successful and satisfying total knee arthroplasty (TKA). Reduced postoperative ROM may be evident in up to 20% of all TKAs and negatively affects satisfaction. To improve ROM, manipulation under anaesthesia (MUA) may be performed. Historically, a limited ROM preoperatively was used as the key harbinger of the postoperative ROM. However, comorbidities may also be useful in predicting postoperative stiffness. The goal was to assess preoperative comorbidities in patients undergoing TKA relative to incidence of postoperative MUA. The hope is to forecast those who may be at increased risk and determine if MUA is an effective form of treatment. Methods. Prospectively collected data of TKAs performed at our institution’s two hospitals from August 2014 to August 2018 were evaluated for incidence of MUA. Comorbid conditions, risk factors, implant component design and fixation method (cemented vs cementless), and discharge disposition were analyzed. Overall, 3,556 TKAs met the inclusion criteria. Of those, 164 underwent MUA. Results. Patients with increased age and body mass index (BMI) had decreased likelihood of MUA. For every one-year increase in age, the likelihood of MUA decreased by 4%. Similarly, for every one-unit increase in BMI the likelihood of MUA decreased by 6%. There were no differences in incidence of MUA between component type/design or fixation method. Current or former smokers were more likely to have no MUA. Surprisingly, patients discharged to home health service or skilled nursing facility were approximately 40% and 70% less likely than those discharged home with outpatient therapy to be in the MUA group. MUA was effective, with a mean increased ROM of 32.81° (SD 19.85°; -15° to 90°). Conclusion. Younger, thinner patients had highest incidence of MUA. Effect of discharge disposition on rate of MUA was an important finding and may influence surgeons’ decisions. Interestingly, use of cement and component design (constraint) did not impact incidence of MUA. Level of Evidence II: Prospective cohort study. Cite this article: Bone Joint J 2020;102-B(6 Supple A):66–72


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_1 | Pages 69 - 69
1 Feb 2020
Hippensteel E Whitaker D Langhorn J
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Introduction. Retrieval investigations have shown that cracking or rim failure of polyethylene hip liners may occur at the superior aspect of the liner, in the area that engages the locking ring of the shell. 1. Failure could occur due to acetabular liner/stem impingement and/or improper cup position. Other contributing factors may include high body mass index, patient activity and design characteristics such as polyethylene material properties, thin liner rim geometry and cup rim design. Currently no standard multi-axis simulator methodology exists for high angle rim fatigue testing, although tests have been developed using static uniaxial load frames. 2. The purpose of this study was to develop a technique to create a clinically relevant rim crack/fracture event on a 4-axis hip simulator, and to understand the contribution of component design and loading and motion parameters. Method. A method for creating rim fracture in vitro was developed to evaluate implant design features and polyethylene liner materials. Liners were secured into acetabular shells, fixtured in resin mounted at a 55° (in vitro; 65° in vivo) inclination to ensure high load/stress was at the area of interest. Ranges of kinematic and maximum applied load profiles were investigated (parameters summarized in Table 1). Testing was conducted on an AMTI 12-station hip simulator for 0.25–1.0 million cycles or until fracture (lubrication maintained with lithium grease). At completion, liners were cleaned and examined for crack propagation/fracture. Inspection of the impingement site on the opposite rim was also analyzed. Additional assessments included liner disassociation/rock out, deformation of characteristics such as anti-rotation devices and microscopic inspection of high-stress regions. Results/Discussion. This study summarizes testing on hip wear simulators to create rim cracking/fracture in vitro. Results indicate that cup/stem angles must be controlled to ensure contact areas are reproducible, and therefore on a multi-station machine (i.e. AMTI), only one test station can/should be run at a time to ensure repeatability. Component design characteristics, such as head size and liner material had a marked effect on the results. It is noted that the kinematics, load and cycle count must be adjusted per the component design to create rim fracture in the high-risk region. Finite element analysis modeling may help identify the high-stress region(s) prior to simulator testing. Deformation of the rim opposite the fracture region (rim/taper impingement) was observed due to the high angle of inclination combined with the abduction/adduction angles. Conclusion. Rim fractures similar in location and morphology to those seen in retrieval studies can be created using a multi-axis hip simulator in vitro. It is noted, however, that the factors presented in this study must be considered and controlled to assure a repeatable method, as the differences in component design investigated and simulator inputs were seen significantly affect the outcome. This study was limited and did not attempt to reproduce rim damage seen in all implant retrievals (e.g. lateralized liners, high offset implants, etc.). These design inputs are being investigated and will be reported upon in the future. For any figures or tables, please contact the authors directly


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_4 | Pages 9 - 9
1 Apr 2022
Williams S Pryce G Board T Isaac G Williams S
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The 10 year survivorship of THR is generally over 95%. However, the incidence of revision is usually higher in year one. The most common reason being dislocation which at least in part is driven by inadequate range of motion (ROM) leading to impingement, subluxation and ultimately dislocation which is more frequently posterior. ROM is affected by patient activity, bone and component geometry, and component placement. To reduce the incidence of dislocation, supported by registry data, there has been an increase in the use of so-called ‘lipped’ liners. Whilst this increases joint stability, the theoretical ROM is reduced. The aim of this study was to investigate the effect of lip placement on impingement. A rigid body geometric model was incorporated into a CT scan hemi-pelvis and femur, with a clinically available THR virtually implanted. Kinematic activity data associated with dislocation was applied, comprising of five posterior and two anterior dislocation risk activities, resulting from anterior and posterior impingement respectively. Cup inclination and anteversion was varied (30°-70°, 0°-50° respectively) to simulate extremes of clinical outcomes. The apex position of a ‘lipped’ liner was rotated from the superior position, anteriorly and posteriorly in steps of 45°. Incidence and location of implant and bone impingement was recorded in 5346 cases generated. A liner with the lip placed superior increased the occurrence of implant-implant impingement compared with a neutral liner. Rotation of the lip from superior reduced this incidence. This effect was more marked with posterior rotation which after 90° reduced anterior impingement to levels similar to a neutral liner. Complete inversion of the lipped liner reduced impingement, but this and anterior rotation both negate its function – additional stability. This study comprises one bone geometry and component design and one set of activity profiles. Nevertheless, it indicates that appropriate lip placement can minimise the likelihood of impingement for a range of daily activities whilst still providing additional joint stability


The Bone & Joint Journal
Vol. 106-B, Issue 4 | Pages 359 - 364
1 Apr 2024
Özdemir E de Lange B Buckens CFM Rijnen WHC Visser J

Aims. To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time. Methods. We performed a single-centre historical prospective cohort study, including all patients with revision THA using the aMace CTAC between January 2017 and March 2021. A total of 18 patients (18 CTACs) were included. Models of the hemipelvis and the scaffold component of the CTACs were created by segmentation of CT scans. The CT scans were performed immediately postoperatively and at least one year after surgery. The amount of bone in contact with the scaffold was analyzed at both times, and the difference was calculated. Results. The mean time between the implantation and the second CT scan was two years (1 to 5). The mean age of the patients during CTAC implantation was 75 years (60 to 92). The mean scaffold-bone contact area increased from 16% (SD 12.6) to 28% (SD 11.9). The mean scaffold-bone distance decreased from a mean of 6.5 mm (SD 2.0) to 5.5 mm (SD 1.6). None of the CTACs were revised or radiologically loose. Conclusion. There was a statistically significant increase of scaffold-bone contact area over time, but the total contact area of the scaffold in relation to the acetabular bone remained relatively low. As all implants remained well fixed, the question remains to what extend the scaffold contributes to the observed stability, in relation to the screws. A future design implication might be an elimination of the bulky scaffold component. This design modification would reduce production costs and may optimize the primary fit of the implant. Cite this article: Bone Joint J 2024;106-B(4):359–364


Aims. Psychoeducative prehabilitation to optimize surgical outcomes is relatively novel in spinal fusion surgery and, like most rehabilitation treatments, they are rarely well specified. Spinal fusion patients experience anxieties perioperatively about pain and immobility, which might prolong hospital length of stay (LOS). The aim of this prospective cohort study was to determine if a Preoperative Spinal Education (POSE) programme, specified using the Rehabilitation Treatment Specification System (RTSS) and designed to normalize expectations and reduce anxieties, was safe and reduced LOS. Methods. POSE was offered to 150 prospective patients over ten months (December 2018 to November 2019) Some chose to attend (Attend-POSE) and some did not attend (DNA-POSE). A third independent retrospective group of 150 patients (mean age 57.9 years (SD 14.8), 50.6% female) received surgery prior to POSE (pre-POSE). POSE consisted of an in-person 60-minute education with accompanying literature, specified using the RTSS as psychoeducative treatment components designed to optimize cognitive/affective representations of thoughts/feelings, and normalize anxieties about surgery and its aftermath. Across-group age, sex, median LOS, perioperative complications, and readmission rates were assessed using appropriate statistical tests. Results. In all, 65 (43%) patients (mean age 57.4 years (SD 18.2), 58.8% female) comprised the Attend-POSE, and 85 (57%) DNA-POSE (mean age 54.9 years (SD 15.8), 65.8% female). There were no significant between-group differences in age, sex, surgery type, complications, or readmission rates. Median LOS was statistically different across Pre-POSE (5 days ((interquartile range (IQR) 3 to 7)), Attend-POSE (3 (2 to 5)), and DNA-POSE (4 (3 to 7)), (p = 0.014). Pairwise comparisons showed statistically significant differences between Pre-POSE and Attend-POSE LOS (p = 0.011), but not between any other group comparison. In the Attend-POSE group, there was significant change toward greater surgical preparation, procedural familiarity, and less anxiety. Conclusion. POSE was associated with a significant reduction in LOS for patients undergoing spinal fusion surgery. Patients reported being better prepared for, more familiar, and less anxious about their surgery. POSE did not affect complication or readmission rates, meaning its inclusion was safe. However, uptake (43%) was disappointing and future work should explore potential barriers and challenges to attending POSE. Cite this article: Bone Jt Open 2022;3(2):135–144


The Bone & Joint Journal
Vol. 102-B, Issue 5 | Pages 573 - 579
1 May 2020
Krueger DR Guenther K Deml MC Perka C

Aims. We evaluated a large database with mechanical failure of a single uncemented modular femoral component, used in revision hip arthroplasty, as the end point and compared them to a control group treated with the same implant. Patient- and implant-specific risk factors for implant failure were analyzed. . Methods. All cases of a fractured uncemented modular revision femoral component from one manufacturer until April 2017 were identified and the total number of implants sold until April 2017 was used to calculate the fracture rate. The manufacturer provided data on patient demographics, time to failure, and implant details for all notified fractured devices. Patient- and implant-specific risk factors were evaluated using a logistic regression model with multiple imputations and compared to data from a previously published reference group, where no fractures had been observed. The results of a retrieval analysis of the fractured implants, performed by the manufacturer, were available for evaluation. Results. There were 113 recorded cases with fracture at the modular junction, resulting in a calculated fracture rate of 0.30% (113/37,600). The fracture rate of the implant without signs of improper use was 0.11% (41/37,600). In 79% (89/113) of cases with a failed implant, either a lateralized (high offset) neck segment, an extralong head, or the combination of both were used. Logistic regression analysis revealed male sex, high body mass index (BMI), straight component design, and small neck segments were significant risk factors for failure. Investigation of the implants (76/113) showed at least one sign of improper use in 72 cases. Conclusion. Implant failure at the modular junction is associated with patient- and implant-specific risk factors as well as technical errors during implantation. Whenever possible, the use of short and lateralized neck segments should be avoided with this revision system. Implantation instructions and contraindications need to be adhered to and respected. Cite this article: Bone Joint J 2020;102-B(5):573–579


The Bone & Joint Journal
Vol. 102-B, Issue 1 | Pages 108 - 116
1 Jan 2020
Burger JA Kleeblad LJ Laas N Pearle AD

Aims. Limited evidence is available on mid-term outcomes of robotic-arm assisted (RA) partial knee arthroplasty (PKA). Therefore, the purpose of this study was to evaluate mid-term survivorship, modes of failure, and patient-reported outcomes of RA PKA. Methods. A retrospective review of patients who underwent RA PKA between June 2007 and August 2016 was performed. Patients received a fixed-bearing medial or lateral unicompartmental knee arthroplasty (UKA), patellofemoral arthroplasty (PFA), or bicompartmental knee arthroplasty (BiKA; PFA plus medial UKA). All patients completed a questionnaire regarding revision surgery, reoperations, and level of satisfaction. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were assessed using the KOOS for Joint Replacement Junior survey. Results. Mean follow-up was 4.7 years (2.0 to 10.8). Five-year survivorship of medial UKA (n = 802), lateral UKA (n = 171), and PFA/BiKA (n = 35/10) was 97.8%, 97.7%, and 93.3%, respectively. Component loosening and progression of osteoarthritis (OA) were the most common reasons for revision. Mean KOOS scores after medial UKA, lateral UKA, and PFA/BiKA were 84.3 (SD 15.9), 85.6 (SD 14.3), and 78.2 (SD 14.2), respectively. The vast majority of the patients reported high satisfaction levels after RA PKA. Subgroup analyses suggested tibial component design, body mass index (BMI), and age affects RA PKA outcomes. Five-year survivorship was 98.4% (95% confidence interval (CI) 97.2 to 99.5) for onlay medial UKA (n = 742) and 99.1% (95% CI 97.9 to 100) for onlay medial UKA in patients with a BMI < 30 kg/m. 2. (n = 479). Conclusion. This large single-surgeon study showed high mid-term survivorship, satisfaction levels, and functional outcomes in RA UKA using metal-backed tibial onlay components. In addition, favourable results were reported in RA PFA and BiKA. Cite this article: Bone Joint J 2020;102-B(1):108–116