Mechanically assisted crevice corrosion of taper interfaces was raised as a concern in total hip arthroplasty (THA) approximately 20 years ago (Gilbert 1993). In total shoulder replacement, however, comparatively little is known about the prevalence of fretting assisted crevice corrosion or the biomechanical and patient factors that influence this phenomenon. Given the comparatively lower loading experienced in the shoulder compared to the hip, we asked: (1) What is the prevalence of fretting assisted corrosion in modular total shoulder replacements, and (2) What patient and implant factors are associated with corrosion? Modular components were collected from 48 revision shoulder arthroplasties as part of a multi-center, IRB approved retrieval program. For anatomic shoulders, this included 40 humeral heads, 32 stems and four taper adapters from seven manufacturers. For reverse shoulders, there were eight complete sets of retrieved components from three manufacturers. The components were predominantly revised for instability, loosening and pain. Anatomical shoulders were implanted for an average of 3.1 years (st dev 3.8; range 0.1–14.5). Reverse shoulders were implanted for an average of 2.2 years (st dev 0.7; range 1.3–3.3). Modular components were disassembled and examined for taper damage. The modular junctions were scored for fretting corrosion using a semi-quantitative four-point scoring system adapted from Goldberg, et al. (Goldberg, 2002, Higgs 2013). The scoring system criteria was adapted from Goldberg and Higgs which is comprised of a one to four grading system (with one indicating little-to-no fretting/corrosion and four indicating extensive fretting/corrosion). The component alloy composition was determined using the manufacturer's laser markings and verified by x-ray fluorescence. Patient age, gender, hand dominance, alloy, flexural rigidity of the trunnion and taper geometry were assessed independently as predictors for fretting corrosion.INTRODUCTION
METHODS
First-generation annealed HXLPE has been clinically successful at reducing both clinical wear rates and the incidence of osteolysis in total hip arthroplasty. However, studies have observed oxidative and mechanical degradation occurring in annealed HXLPE. Thus, it is unclear whether the favorable clinical performance of 1st generation HXLPE is due to the preservation of bearing surface tribological properties or, at least partially, to the reduction in patient activity. The purpose of this study was to evaluate the in vitro wear performance (assessed using multidirectional pin-on-disk (POD) testing) of 1st-generation annealed HXLPE with respect to in vivo duration, clinical wear rates, oxidation, and mechanical properties. 103 1st-generation annealed HXLPE liners were collected at revision surgery. 39 annealed HXLPE liners were selected based on their implantation time and assigned to three equally sized cohorts (n=13 per group); short-term (1.4–2.7y), intermediate term (5.2–8.0y) and long-term (8.3–12.5y). From each retrieved liner, two 9-mm cores were obtained (one from the superior region and one from the inferior region). Sixteen cores were fabricated from unimplanted HXLPE liners that were removed from their packaging and six pins from unirradiated GUR 1050 resin served as positive controls. Multidirectional POD wear testing was conducted against wrought CoCr disks in a physiologically relevant lubricant (20 g/L protein concentration) using a 100-station SuperPOD (Phoenix Tribology, UK). Each pin had its own chamber with 15mL lubricant maintained at 37±1°C. An elliptical wear pattern with a static contact stress of 2.0 MPa was employed. Testing was carried out to 1.75 million cycles at 1.0 Hz and wear was assessed gravimetrically. POD wear rates were calculated using a linear regression of volumetric losses. In vivo penetration was measured directly using a calibrated micrometer. Oxidation was assessed on thin films obtained from superior and inferior regions of the liners (ASTM 2102). Mechanical properties were assessed using the small punch test (ASTM 2183).Introduction
Materials and Methods
In THA, fretting corrosion at the head-stem taper junction has emerged as a clinical concern that may result in adverse local tissue reactions, even in patients with a metal-on-polyethylene bearing [1]. Taper junctions that employ a ceramic head have demonstrated reduced corrosion at the interface [2]. However, during revision surgery with a well-fixed stem, a titanium sleeve is used in conjunction with a ceramic head to ensure proper fit of the head onto the stem and better stress distribution. In vitro testing has suggested that corrosion is not a concern in sleeved ceramic heads [3]; 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. Between 2001 and 2014, 35 sleeved ceramic heads were collected during revision surgery as part of a multi-center retrieval program. The sleeves were all fabricated from titanium alloy and manufactured by 4 companies (CeramTec (n=14), Smith & Nephew (Richards, n=11), Stryker (n=5), and Zimmer (n=5)). The femoral heads were made from 3 ceramics (Alumina (n=7), Zirconia (n=11), and Zirconia-toughened Alumina (n=17)). Sleeve dimensions (length and thickness) were measured using calibrated calipers. Fretting corrosion of the sleeves and available associated stems was scored using a 4-point, semi-quantitative scoring system [4], with 1 being little-to-no damage, and 4 corresponded to severe fretting corrosion. Five sleeves could not be extracted; thus the external surface was not scored.Introduction
Materials and Methods
Recent implant design trends have renewed concerns regarding metal wear debris release from modular connections in THA. Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Comparatively little is known about head-neck taper corrosion with ceramic femoral heads or about how taper angle clearance influences taper corrosion. This study addressed the following research questions: 1) Could ceramic heads mitigate electrochemical processes of taper corrosion compared to CoCr heads? 2) Which factors influence stem taper corrosion with ceramic heads? 3) What is the influence of taper angle clearance on taper corrosion in THA? 100 femoral head-stem pairs were analyzed for evidence of fretting and corrosion. A matched cohort design was employed in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design and flexural rigidity. Fretting corrosion was assessed using a semi-quantitative scoring scale where a score of 1 was given for little to no damage and a score of 4 was given for severe fretting corrosion. The head and trunnion taper angles were measured using a roundness machine (Talyrond 585, Taylor Hobson, UK). Taper angle clearance is defined as the difference between the head and trunnion taper angles.Introduction
Methods
The release of metal debris and ions has raised concerns in joint arthroplasty. In THA metal debris and ions can be generated by wear of metal-on-metal bearing surfaces and corrosion at modular taper interfaces, currently understood to be mechanically assisted crevice corrosion (MACC) [1]. More recently, inflammatory-cell induced corrosion (ICIC) has been identified as a possible source of metal debris and/or ions [2]. Although MACC has been shown to occur at modular junctions in TKA, little is known about the prevalence of other sources. The purpose of this study was to determine the sources of metallic debris and ion release in long-term implanted (in vivo > 15y) TKA femoral components. Specific attention was paid to instances of ICIC as well as damage at the implant-bone interface. 1873 retrieved TKA components were collected from 2002–2013 as part of a multi-center, IRB-approved retrieval program. Of these, 52 CoCr femoral condyles were identified as long term TKA (Average: 17.9±2.8y). These components were predominantly revised for loosening, PE wear and instability. 40/52 of the components were primary surgeries. Components were examined using optical microscopy to confirm the presence of 5 damage mechanisms (polyethylene failure, MACC corrosion of modular tapers, corrosion damage between cement and backside, third-body wear, and ICIC). Third-body wear was evaluated using a semi-quantitative scoring method based on the percentage of damaged area. A score of 1 had minimal damage and a score of 4 corresponded to severe damage. Polyethylene components were scored using the Hood method and CoCr components were scored similarly to quantify metal wear. The total area damaged by ICIC was quantified using photogrammetry. Images were taken using a digital SLR with a calibrated ruler in the same focal plane. Using known pixel dimensions, the ICIC damaged area was calculated.Introduction
Methods
Current knowledge regarding outcomes following surgical treatment of Morton's neuroma remains incomplete. This is the first prospective study to report the pre- and post-operative patient reported outcomes and satisfaction scores following excision of interdigital Morton's neuroma. Over a seven year period, 99 consecutive patients (112 feet) undergoing surgical excision of Morton's neuroma were prospectively studied. 78 patients were female with a mean age at operation of 56 years. Patient recorded outcomes and satisfaction were measured using the Manchester-Oxford Foot Questionnaire (MOXFQ), Short Form-12 (SF12) and a supplementary patient satisfaction survey three months pre and six months post-operatively. Statistically significant differences were found between the mean pre- and post-operative MOXFQ and physical component of the SF-12 (p< 0.05). No difference in outcome was identified in patients in whom multiple neuromas were operated compared to single site surgery. However, revision surgery proved to statistically worsen MOXFQ outcomes post-operatively p< 0.004. Overall satisfaction was reported as excellent (49%) or good (29%) by the majority of patients but 10% were dissatisfied with poor (8%) or very poor (2%) results expressed. Only 64% were pain free at the time of follow-up and 8% of patients MOXFQ scores worsened. These findings illustrate that overall, patient reported outcomes following resection of symptomatic Morton's neuroma are acceptable but may not be as favourable as earlier studies suggest. Caution should be taken when considering revision surgery which has shown to be a poor prognostic indicator. Contrary to current knowledge, multiple site surgery can be safely undertaken.
Current knowledge regarding outcomes following surgical treatment of Morton's neuroma remains incomplete. This is the first prospective study to report the pre- and post-operative patient reported outcomes and satisfaction scores following excision of interdigital Morton's neuroma. Over a seven year period, 99 consecutive patients (112 feet) undergoing surgical excision of Morton's neuroma were prospectively studied. 78 patients were female with a mean age at operation of 56 years. Patient recorded outcomes and satisfaction were measured using the Manchester-Oxford Foot Questionnaire (MOXFQ), Short Form-12 (SF12) and a supplementary patient satisfaction survey three months pre and six months post-operatively. Statistically significant differences were found between the mean pre- and post-operative MOXFQ and physical component of the SF-12 (p<0.05). No difference in outcome was identified in patients in whom multiple neuromas were operated compared to single site surgery. However, revision surgery proved to statistically worsen MOXFQ outcomes post-operatively p<0.004. Overall satisfaction was reported as excellent (49%) or good (29%) by the majority of patients but 10% were dissatisfied with poor (8%) or very poor (2%) results expressed. Only 64% were pain free at the time of follow-up and 8% of patients MOXFQ scores worsened. These findings illustrate that overall, patient reported outcomes following resection of symptomatic Morton's neuroma are acceptable but may not be as favourable as earlier studies suggest. Caution should be taken when considering revision surgery which has shown to be a poor prognostic indicator. Contrary to current knowledge, multiple site surgery can be safely undertaken.
This study assessed whether patient satisfaction with their hospital stay influences the early outcome of total knee replacement (TKR). During a five year period patients undergoing primary TKR at the study centre had prospectively outcome data recorded (n=2264). Patients with depression (p=0.04) and worse mental wellbeing (p<0.001), according to the short form (SF)-12, were more likely to be dissatisfied with their hospital stay. Decreasing level of satisfaction with their hospital stay was associated with a significantly worse post-operative OKS (p<0.001) and SF-12 score (p<0.001). Multivariable regression analysis confirmed that the patients perceived level of satisfaction with their hospital stay was an independent predictor of change in the OKS (p<0.001) and SF-12 score (p<0.001) after adjusting for confounding variables. Patient satisfaction with their TKR was significantly influenced by their hospital experience, decreasing from 96% in those with an excellent experience to 42% in those with a poor experience. Food, staff/care, and the hospital environment were the most frequent reasons of why patients rated their hospital experience as fair or poor. A patient's perception of their inpatient hospital experience after surgery is an important modifiable predictor of early functional outcome and satisfaction with TKR.
Two major challenges in arthroplasty are obesity and antibiotic resistance. This study was performed to characterise the organisms responsible for deep infection following total hip arthroplasty and to determine if obesity affected the microbiology profile. A retrospective analysis of the national surgical site infection register was made to obtain data regarding deep infection following 10948 primary total hip arthroplasty (THA) from 1998–2013, with a minimum of 2 year follow-up. Of all the primary THAs performed, there were 108 deep infections (56 patients had a BMI >30 (obese) and 52 patients <30). There were no significant differences between cardio-respiratory disease, smoking and alcohol status, and diabetes between the 2 groups. Over the last 15 years, staphylococcus aureus continues to be the most frequently isolated organism. Infection with multiple organisms was found exclusively in obese patients. Furthermore, in obese patients, there was a linear increase with methicillin resistant staphylococcus aureus (MRSA) infections and streptococcus viridans. On this basis, we recommend careful selection of antibiotic therapy in obese patients, rather than empirical therapy, which can be especially important if there is no growth in an infected THA. In addition, a preoperative discussion regarding dental prophylaxis against streptococcus viridans may be warranted.
This study assesses oxidation, mechanical behavior and revision reasons of 2nd generation HXLPE used in total hip and knee arthroplasty. While oxidation was low for both X3 and E1 HXLPEs, oxidative regional variations were detected in the sequentially annealed cohort. First generation highly crosslinked polyethylenes (HXPLEs) have proven successful in lowering both penetration and osteolysis rates. However, 1st generation annealing and remelting thermal stabilization have been associated with in vivo oxidation or reduced mechanical properties. Thus, 2nd generation HXLPEs were developed to improve oxidative stability while still maintaining material properties. Little is known about the in vivo clinical failure modes of these 2nd generation HLXPEs. The purpose of this study was to assess the revision reasons, wear, oxidative stability, and mechanical behavior of retrieved sequentially annealed Vitamin E diffused HXLPE in THA and TKA.Summary Statement
Introduction
Fretting and corrosion has been identified as a clinical problem in modular metal-on-metal THA, but remains poorly understood in modern THA devices with polyethylene bearings. This study investigates taper damage and if this damage is associated with polyethylene wear. Degradation of modular head-neck tapers was raised as a concern in the 1990s (Gilbert 1993). The incidence of fretting and corrosion among modern, metal-on-polyethylene and ceramic-on-polyethylene THA systems with 36+ mm femoral heads remains poorly understood. Additionally, it is unknown whether metal debris from modular tapers could increase wear rates of highly crosslinked PE (HXLPE) liners. The purpose of this study was to characterise the severity of fretting and corrosion at head-neck modular interfaces in retrieved conventional and HXLPE THA systems and its effect on penetration rates.Summary Statement
Introduction
Service industry metrics (the net promoter score) are being introduced as a measure of UK healthcare satisfaction. Lower limb arthroplasty, as a ‘service’, scores comparably with the most successful commercial organisations. Satisfaction with care is important to both the patient and the payer. The Net Promoter Score, widely used in the service industry, has been recently introduced to the UK National Health Service as an overarching metric of patient satisfaction and to monitor performance. This questionnaire asks ‘customers’ if they would recommend a service or products to others. Scores range from −100 (everyone is a detractor) to +100 (everyone is a promoter). In industry, a positive score is well regarded, with those over 50 regarded as excellent. Our aims were to assess net promoter scores for joint arthroplasty, to compare these scores with direct measures of patient satisfaction, and to evaluate which factors contributed to net promoter response.Summary Statement
Background
In our department, currently there is variation in the number of xrays that patients receive following ORIF of distal radius fractures. This audit investigated the use of xrays following ORIF of distal radius fractures. Patients were identified from daily trauma lists. Patients who had a primary ORIF or ORIF following failed conservative management were included in the study. PACS was used to identify the number of post-operative xrays performed. These were correlated with clinic letters to see if there was any change in management following xray review. Between July and November 2013, 102 patients were admitted with distal radius fracture. Of these, 35 (mean age:51 years) had an ORIF. Four were not followed-up in Scotland. Of the remaining 31 patients, eleven had one post-operative xray, seventeen had two and three had three xrays. Of the patients who had one xray, seven had the xray in the first three weeks, the rest at six weeks. Patients who had two xrays had an xray at two and 6 weeks. Of the three patients who had three xrays, two had comminuted fractures that required further CT investigation, one for a suspicion of an intra-articular screw, the other for possibility of non-union. The third patient had no apparent reason for requiring three xrays. Thus of the 31 patients in the study, 29 did not require any further investigations. The results show a variation in the frequency of post-operative xrays after fixation of distal radius fractures. In most cases the management plan was unchanged after plain xrays were undertaken. This suggests that a protocol driven approach to follow-up after fixation of distal radius fractures could reduce the burden on fracture clinic and radiology departments. We propose that unless indicated by intra-operative findings or post-operative concerns, patients should have xrays at the two week review appointment.
Many psychological factors have been associated with function after joint replacement. Personality is a stable pattern of responses to external conditions and stimuli. The aim of this study was to investigate the relationship between personality, joint function, and general physical in patients undergoing total hip (THR) and knee replacement (TKR). We undertook a prospective cohort study of 184 patients undergoing THA and 205 undergoing TKA. Personality was assesed using the Eysneck Personality Questionaire, brief version (EPQ-BV). Physical health was measured using the EuroQol (EQ-5D). Joint function was measured using the relevant Oxford Score. Outcomes were assessed at six months. Multivariable models were constructed. The stable introvert personality was most common. Unstable introverts had poorer pre-operative function with hip arthrosis, but not knee arthrosis. Personality was not directly associated with post-operative function – the only independent predictors were pre-operative function (p=0.002) and comorbidity (p<0.001). While satisfaction after TKR was associated with personality (p=0.026), there was no association after THR (p=0.453). The poorest satisfaction was in those with the unstable introvert personality type. Personality was a predictor of preoperative status. It did not have a direct association with postoperative status, but may have as preoperative function was the main predictor of postoperative function, personality may have had an indirect effect. Personality was also a predictor of satisfaction after TKR. This suggests that predicting satisfaction after knee replacement is more complex. Therefore certain patient may benefit from a tailored preoperative education to explore and manage expectations.
Expectations of patients requiring knee arthroplasty surgery have become higher than in the past, with more strain being put on modern prostheses by fitter and younger patients. The objective of this study was to analyse the survivorship of primary knee arthroplasties at a minimum of ten years, with end points of revision and death. Patients who had a total (TKA) or unicompartmental (UKA) knee arthroplasty performed at a university teaching hospital were identified from the local arthroplasty database. Electronic and operative records were analysed to determine parameters including operative indication, subsequent revision surgery, and patient mortality. Results were collated and analysed using PASW software. A total of 1023 patients were recruited, with 566 (55%) female and 457 (45%) male. Minimum follow up was 10.1 years, with an average of 12.1 years (S.D 0.87). 64.9% of patients were alive at follow up, with an average age of 79.7 years (S.D 8.7). 92.8% were operated on for osteoarthritis (OA), 6.6% for rheumatoid arthritis (RA) and 0.6% for other indications. Kaplan–Meier analysis estimated survival of 94% (S.D 0.008) at eleven years, with no statistical difference found in survivorship of knees operated on for OA or RA. Similarly no statistical difference was found between survivorship of UKA or TKA implants. Of those that died by follow up, 95.2% did so with their original implant. We conclude that both TKA and UKA offer a lasting solution for patients, with excellent outcomes achieved in both rheumatoid and osteoarthritic patients.
This study assessed the effect of concomitant
back pain on the Oxford knee score (OKS), Short-Form (SF)-12 and patient
satisfaction after total knee replacement (TKR). It involved a prospectively
compiled database of demographics and outcome scores for 2392 patients
undergoing primary TKR, of whom 829 patients (35%) reported back
pain. Compared with those patients without back pain, those with
back pain were more likely to be female (odds ratio (OR) 1.5 (95%
confidence interval (CI) 1.3 to 1.8)), have a greater level of comorbidity,
a worse pre-operative OKS (2.3 points (95% CI 1.7 to 3.0)) and worse
SF-12 physical (2.0 points (95% CI 1.4 to 2.6)) and mental (3.3
points (95% CI 2.3 to 4.3)) components. One year post-operatively, those with back pain had significantly
worse outcome scores than those without with a mean difference in
the OKS of 5 points (95% CI 3.8 to 5.4), in the SF-12 physical component
of 6 points (95% CI 5.4 to 7.1) and in the mental component of
4 points (95% CI 3.1 to 4.9). Patients with back pain were less
likely to be satisfied (OR 0.62, 95% CI 0.5 to 0.78). After adjusting for confounding variables, concomitant back pain
was an independent predictor of a worse post-operative OKS, and
of dissatisfaction. Clinicians should be aware that patients suffering
concomitant back pain pre-operatively are at an increased risk of
being dissatisfied post-operatively. Cite this article:
First generation highly crosslinked polyethylenes (HXPLEs) have proven successful in lowering both penetration and osteolysis rates. However, 1st generation annealing and remelting thermal stabilization have been associated with in vivo oxidation or reduced mechanical properties. Thus, 2nd generation HXLPEs were developed to improve oxidative stability while still maintaining material properties. Little is known about the in vivo clinical failure modes of these 2nd generation HLXPEs. The purpose of this study was to assess the revision reasons, wear, oxidative stability, and mechanical behavior of retrieved sequentially annealed Vitamin E diffused HXLPE in THA and TKA. 251 2nd Generation HXLPE hip and knee components were consecutively retrieved during revision surgeries and continuously analyzed in a prospective, IRB approved, multicenter study. 123 acetabular liners (Implanted 1.2y; Range 0–5.0y) and 117 tibial inserts (Implanted 1.6y; Range 0–5.8y) were highly crosslinked and annealed in 3 sequential steps (X3). Five acetabular liners (Implanted 0.6y; Range 0–2.0y) and six tibial inserts (Implanted 1.3y; Range 0.5–1.8y) were diffused with Vitamin E (E1). Patient information was collected from medical records (Table 1). Linear penetration of liners was measured using a calibrated digital micrometer (accuracy: 0.001 mm). Surface damage of tibial components was assessed using the Hood method. Thin sections were taken from the acetabular liners (along the superior/inferior axis) and the tibial components (along the medial condyle and central spine) for oxidation analysis and analyzed according to ASTM 2102. Mechanical behavior was assessed via the small punch test (ASTM 2183).Introduction:
Methods:
Degradation of modular head-neck tapers was raised as a concern in the 1990s (Gilbert 1993). The incidence of fretting and corrosion among modern, metal-on-polyethylene and ceramic-on-polyethylene THA systems with 36+ mm femoral heads remains poorly understood. Additionally, it is unknown whether metal debris from modular tapers could increase wear rates of highly crosslinked PE (HXLPE) liners. The purpose of this study was to characterize the severity of fretting and corrosion at head-neck modular interfaces in retrieved conventional and HXLPE THA systems and its effect on penetration rates. 386 CoCr alloy heads from 5 manufacturers were analyzed along with 166 stems (38 with ceramic femoral heads). Metal and ceramic components were cleaned and examined at the head taper and stem taper by two investigators. Scores ranging from 1 (mild) to 4 (severe) were assigned in accordance with the semi-quantitative method adapted from a previously published technique. Linear penetration of liners was measured using a calibrated digital micrometer (accuracy: 0.001 mm). Devices implanted less than 1 year were excluded from this analysis because in the short-term, creep dominates penetration of the head into the liner.Introduction:
Patients & Methods:
Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads. We asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads.Background:
Questions/purposes:
Nerve damage is a complication of THA and TKA procedures. The incidence of subclinical nerve injury following arthroplasty is unknown. The aim was to determine the prevalence of asymptomatic nerve deficits in an arthroplasty population group, and the incidence of post-operative changes in nerve function. A Secondary aim was to identify the nature of any deficits. And the association between nerve deficits and history of backache. A non-randomised prospective series of patients undergoing lower limb arthroplasty for osteoarthritis were studied at a single hospital. The peroneal nerve was investigated using nerve conduction in forty patients. Twenty patients had upper limb testing to differentiate between a polyneuropathy or isolated lower limb neuropathy. Nerve function deficits were detected in the peroneal nerve in fifteen patients pre-operatively and fifteen post-operatively, of those twelve had A waves detected suggestive of a generalised neuropathy. Ten patients who had upper limb testing had a conduction defect (five had asymptomatic Carpal tunnel). There was a positive correlation between presence of post-operative deficit and age(r=0.389, p=0.013). A negative correlation was found for presence of post-operative A waves and BMI(r=−0.370, p=0.019). The prevalence of pre-operative subclinical peroneal neuropathy is much higher than expected in this group (37.5%) of arthroplasty patients. There is a strong correlation between presence of post-operative conduction abnormalities and age. There is no relationship between peripheral neuropathy and history of backache or residual post-operative deficit.
