Lower Risk of Revision With 32- and 36-Millimeter Femoral Heads Compared With 28-mm Heads in Primary Total Hip Arthroplasty: A Comparative Single-Center Study (10,104 Hips).

BACKGROUND: We aimed to compare the clinical outcomes of different head sizes (28-, 32-, and 36- millimeter) in primary total hip arthroplasty (THA) at mean 6 years follow-up (range, 1 to 17.5 years). METHODS: This was a retrospective consecutive study of primary THA at our institution (2003 to 2019). Demographic and surgical data were collected. The primary outcome measures were all-cause revision, revision for dislocation, and all-cause revision excluding dislocation. Continuous descriptive statistics used means, median values, ranges, and 95% confidence intervals, where appropriate. Kaplan-Meier survival curves were used to estimate time to revision. Cox proportional hazard regression analyses were used to compare revision rates between the femoral head size groups. Adjustments were made for age at surgery, sex, primary diagnosis, American Society of Anesthesiologists score, articulation type, and fixation methods. There were 10,104 primary THAs included; median age was 69 years (range, 13 to 101) with 61.5% women. A posterior approach was performed in 71.6%. There were 3,295 hips with 28-mm heads (32.6%), 4,858 (48.1%) with 32-mm heads, and 1,951 (19.3%) with 36-mm heads. RESULTS: Overall rate of revision was 1.7% with the lowest rate recorded for the 36-mm group (2.7 versus 1.3 versus 1.1%). Cox regression analyses showed a decreased risk of all-cause revision for 32 and 36-mm head sizes as compared to 28-mm; this was statistically significant for the 32-mm group (P = .01). Risk of revision for dislocation was significantly reduced in both 32-mm (P = .03) and 36-mm (P = .03) head sizes. Analysis of all cause revision excluding dislocation showed no significant differences between head sizes. CONCLUSIONS: We found a significantly reduced risk of revision for all causes, but particularly revision for dislocation with larger head sizes. Concerns regarding increased risk of early revision for aseptic loosening, polyethylene wear, or taper corrosion with larger heads appear to be unfounded in this cohort of 10,104 patients with up to 17 years follow-up.

Factors Associated With Trunnionosis in the Metal-on-Metal Pinnacle Hip.

BACKGROUND: Trunnionosis of the tapered head-stem junction of total hip arthroplasties, either through corrosion or mechanical wear, has been implicated in early implant failure. Retrieval analysis of large numbers of failed implants can help us better understand the factors that influence damage at this interface. METHODS: In this study, we examined 120 retrieved total hip arthroplasties of one bearing design, the 36-mm diameter metal-on-metal, DePuy Pinnacle, that had been paired with 3 different stems. We measured material loss of the bearing and head-trunnion taper surfaces and collected clinical and component data for each case. We then used multiple linear regression analysis to determine which factors influenced the rate of taper material loss. RESULTS: We found 4 significant variables: (1) longer time to revision (P = .004), (2) the use of a 12/14 taper for the head-trunnion junction (P < .001), (3) decreased bearing surface wear (P = .003), and (4) vertical femoral offset (P = .05). These together explained 29% of the variability in taper material loss. CONCLUSION: Our most important finding is the effect of trunnion design. Of the 3 types studied, we found that S-ROM design was the most successful at minimizing trunnionosis.

Detection of metallic cobalt and chromium liver deposition following failed hip replacement using T2* and R2 magnetic resonance.

BACKGROUND: Failed hip prostheses can cause elevated circulating cobalt and chromium levels, with rare reports of fatal systemic organ deposition, including cobalt cardiomyopathy. Although blood cobalt and chromium levels are easily measured, organ deposition is difficult to detect without invasive biopsy. The T2* magnetic resonance (MR) method is used to quantify tissue iron deposition, and plays an important role in the management of iron-loading conditions. Cobalt and chromium, like iron, also affect magnetism and are proposed MR contrast agents. CASE PRESENTATION: We describe a case of a 44-year-old male with a failed hip implant and very elevated blood cobalt and chromium levels. Despite normal cardiac MR findings, liver T2* and R2 values were abnormal, triggering tissue biopsy. Liver tissue analysis, including X-ray fluorescence, demonstrated heavy elemental cobalt and chromium deposition in macrophages, and no detectable iron. CONCLUSIONS: Our case demonstrates T2* and R2 quantification of liver metal deposition in a patient with a failed hip implant. Further work is needed to investigate the role of T2* and R2 MR in the detection of metal deposition from metal on metal hip prostheses.

The Relationship Between Cobalt/Chromium Ratios and the High Prevalence of Head-Stem Junction Corrosion in Metal-on-Metal Total Hip Arthroplasty.

BACKGROUND: The size of the clinical impact of corrosion of the taper junction of metal-on-metal total hip arthroplasties (MOM-THAs) is unclear. Examination of a large number of retrieved MOM resurfacings and total hip arthroplasties can help us understand the role of taper corrosion in metal ion release. METHODS: We graded the severity of corrosion at the taper junction of 395 MOM-THAs and compared the prerevision whole blood metal ion levels of these hips with 529 failed MOM hip resurfacings. RESULTS: Virtually all MOM-THA hips (n = 388) had evidence of corrosion of the head-stem taper junction and graded as severe in 31% (n = 124). The median cobalt/chromium (Co/Cr) ratio was 1.58 (0.01-13.82) and 1.08 (0-4.86) for MOM-THA and MOM hip resurfacing, respectively; this difference was significant (P < .001). THA hips with severely corroded tapers had the highest median Co/Cr ratio of 1.86 (0.01-10). CONCLUSIONS: This study demonstrates the high prevalence of severe taper corrosion, which may be related to an elevated Co/Cr ratio before revision.

Clinical significance of corrosion of cemented femoral stems in metal-on-metal hips: a retrieval study.

PURPOSE: The clinical significance of corrosion of cemented femoral stems is unclear. The purpose of this retrieval study was to: (1) report on corrosion at the stem-cement interface and (2) correlate these findings with clinical data. METHODS: We analysed cemented stems (n = 36) composed of cobalt-chromium (CoCr) and stainless steel (SS) in a series of revised metal-on-metal hips. We performed detailed inspection of each stem to assess the severity of corrosion at the stem-cement interface using a scale of 1 (low) to 5 (severe). We assessed the severity of corrosion at each stem trunnion and measured wear rates at the head taper and bearing surfaces. We used non-parametric tests to determine the significance of differences between the CoCr and SS stems in relation to: (1) pre-revision whole blood Co and Cr metal ion levels, (2) trunnion corrosion, (3) bearing surface wear and (4) taper material loss. RESULTS: The corrosion scores of CoCr stems were significantly greater than SS stems (p < 0.01). Virtually all stem trunnions in both alloy groups had minimal evidence of corrosion. The median pre-revision Co levels of implants with CoCr stems were significantly greater than the SS stems (p < 0.01). There was no significant difference in relation to pre-revision Cr levels (p = 0.521). There was no significant difference between the two stem types in relation to bearing wear (p = 0.926) or taper wear (p = 0.148). CONCLUSIONS: Severe corrosion of cemented femoral stems is a common finding at our retrieval centre; surgeons should consider corrosion of CoCr stems as a potential source of metal ions when revising a hip.

Clinical Usefulness of SPECT-CT in Patients with an Unexplained Pain in Metal on Metal (MOM) Total Hip Arthroplasty.

SPECT-CT is increasingly used to assess painful knee arthroplasties. The aim of this study was to evaluate the clinical usefulness of SPECT-CT in unexplained painful MOM hip arthroplasty. We compared the diagnosis and management plan for 19 prosthetic MOM hips in 15 subjects with unexplained pain before and after SPECT-CT. SPECT-CT changed the management decision in 13 (68%) subjects, Chi-Square=5.49, P=0.24. In 6 subjects (32%) pain remained unexplained however the result reassured the surgeon to continue with non-operative management. SPECT-CT should be reserved as a specialist test to help identify possible causes of pain where conventional investigations have failed. It can help reassure surgeons making management decisions for patients with unexplained pain following MOM hip arthroplasty.

Muscle atrophy and metal-on-metal hip implants: a serial MRI study of 74 hips.

BACKGROUND AND PURPOSE: Muscle atrophy is seen in patients with metal-on-metal (MOM) hip implants, probably because of inflammatory destruction of the musculo-tendon junction. However, like pseudotumors, it is unclear when atrophy occurs and whether it progresses with time. Our objective was to determine whether muscle atrophy associated with MOM hip implants progresses with time. PATIENTS AND METHODS: We retrospectively reviewed 74 hips in 56 patients (32 of them women) using serial MRI. Median age was 59 (23-83) years. The median time post-implantation was 83 (35-142) months, and the median interval between scans was 11 months. Hip muscles were scored using the Pfirrmann system. The mean scores for muscle atrophy were compared between the first and second MRI scans. Blood cobalt and chromium concentrations were determined. RESULTS: The median blood cobalt was 6.84 (0.24-90) ppb and median chromium level was 4.42 (0.20-45) ppb. The median Oxford hip score was 34 (5-48). The change in the gluteus minimus mean atrophy score between first and second MRI was 0.12 (p = 0.002). Mean change in the gluteus medius posterior portion (unaffected by surgical approach) was 0.08 (p = 0.01) and mean change in the inferior portion was 0.10 (p = 0.05). Mean pseudotumor grade increased by 0.18 (p = 0.02). INTERPRETATION: Worsening muscle atrophy and worsening pseudotumor grade occur over a 1-year period in a substantial proportion of patients with MOM hip implants. Serial MRI helps to identify those patients who are at risk of developing worsening soft-tissue pathology. These patients should be considered for revision surgery before irreversible muscle destruction occurs.

The reliability of a scoring system for corrosion and fretting, and its relationship to material loss of tapered, modular junctions of retrieved hip implants.

It has been suggested that corrosion and fretting at the tapered, modular junctions of hip arthroplasties may contribute to implant failure. In this study the reliability of a commonly used peer-reviewed scoring system for visual assessment of corrosion and fretting at these junctions was evaluated. Volumetric material loss at the tapered head surface was measured and associations with the visual scores were investigated. We found that the inter-observer reproducibility and single-observer repeatability of the corrosion scores were substantial using Cohen's weighted Kappa statistic (k = 0.64-0.71). The reproducibility and repeatability of the fretting scores however were slight to fair (k = 0.18-0.31). Taper corrosion scores were significantly and moderately correlated with the volume of material loss measured (Spearman's r = 0.59; P < 0.001). We recommend the continued use of this scoring system but it should not be a substitute for measurement of material loss.

Failure of the Yoke With a Rotating-Hinge Total Knee Arthroplasty: A Case Report.

CASE: A patient underwent revision of a total knee replacement to a cementless rotating-hinge prosthesis. The femoral component became loose, but due to the patient's frailty and cognitive decline, revision was not performed. Subsequently, the yoke failed, dissociating the femoral and tibial components, necessitating a single-stage revision. CONCLUSION: This case underlines the need for robust fixation of components of rotating-hinge knee replacements to avoid mechanical failures. It contributes valuable insights to the limited literature on yoke failure in total knee arthroplasty, emphasizing the importance of implant design, patient selection, and surgical technique to prevent such complications.

Is there an increased revision rate due to early tibial component loosening with a modern total knee arthroplasty design? A retrospective analysis from a large volume arthroplasty centre.

BACKGROUND: The Attune TKR was introduced in 2011 as a successor to its predicate design The PFC Sigma. However, following reports of early failures, there are ongoing concerns related to increased loosening rates. Given the concerns, this study aimed to compare revision rates of the Attune implant to an established predicate, and other implant designs used in a high-volume arthroplasty center. METHODS: We identified 10,202 patients who underwent primary cemented TKR at our institution with a minimum of 1 year follow-up, involving 2406 Attune TKR (557 S +), 4642 PFC TKR, 3154 other designs. Primary outcomes were revision for all-causes, aseptic loosening of any component, and aseptic tibial loosening. Kaplan-Meier survival and Cox regression models were used to compare groups. Matched cohorts were selected for radiographic analysis. RESULTS: 308 knees were revised. The Attune cohort had the lowest risk of revision, with a rate of 2.98 per 1000 implant-years while the PFC and All Other Implant groups had a rate of 3.15 and 4.4 respectively. Aseptic loosing was the most common cause for revision, with 76% (65/88) involving the tibia. Survival analysis showed no significant differences between the Attune and other cohorts. Radiolucent lines were detected in 7.1% of the Attune S + group, 6.8% of the standard Attune group, and 6.3% of the PFC group, with no significant differences found between them. CONCLUSION: This study represents the largest non-registry review of the Attune TKR in comparison to a predicate and other designs. There was no significant increased revision rate for all-cause revision or aseptic loosening, or peri-implant radiolucencies. It appears that increased loosening may not be as concerning as originally thought. LEVEL OF EVIDENCE: Level III.

Cementless TKA use as an alternative to cemented TKA in high BMI patients: A systematic review and meta-analysis.

Purpose: Obesity is prevalent, with nearly one-third of the world's population being classified as obese. In patients with high body mass index (BMI)/body mass undergoing total knee arthroplasty (TKA), there is an increase in strain placed on the implant fixation interfaces. As such, component fixation is a potential concern when performing TKA in the obese patient. To address the growing concerns around the longevity of implant fixation, some have advocated cementless over cemented fixation. However, there is no clear consensus on whether a cementless fixation has more favourable outcomes. The aim of this paper was to present a systematic review and meta-analysis of the existing evidence to establish if cementless TKA has a lower rate of aseptic loosening in high BMI patients when compared to cemented TKA procedures. Methods: A systematic review was performed, and the following databases Medical Literature Analysis and Retrieval System Online (1946 to date), PubMed (1966 to date) and Excerpta Medica Database (1974 to date) were searched. All studies comparing cementless to cemented TKA in patients with BMI > 30 were considered. Meta-analysis compared aseptic loosening and all-cause revision between cemented and uncemented implant use in BMI > 30 patients. Results: The search returned 91 articles in total; after duplicates were removed, the yield was 44 studies. Of the remaining studies that were assessed, three studies met the inclusion criteria for meta-analysis. The pooled odds ratio for all-cause revisions was 0.17 (95%, 0.08-0.36) in favour of uncemented implants (p < 0.01). The pooled odds ratio for aseptic loosening was 0.15 (95% confidence interval, 0.02-0.90) in favour of uncemented implants (p = 0.04). Conclusions: Meta-analysis demonstrated a significant decrease in all-cause revisions and revisions for aseptic loosening when using uncemented fixation in high BMI patients when compared to the use of cemented implants. Level of Evidence: The level of evidence is 1 for our systematic review.

Postoperative Continuous Passive Motion Does Not Improve the Range of Movement Achieved After Manipulation Under Anesthetic for Stiffness in Total Knee Replacement.

Background: Stiffness is a common complication following total knee arthroplasty. Manipulation under anesthesia (MUA) is an intervention that can potentially improve range of motion (ROM). Continuous passive motion (CPM) therapy has been utilized to enhance post-MUA ROM, but its effectiveness remains debated. This study assesses whether CPM therapy after MUA results in superior ROM outcomes compared to MUA alone. Methods: A retrospective analysis included patients undergoing MUA for stiff primary total knee arthroplasty between 2017 and 2022. Demographics and ROM data were collected. Patients were in 2 groups: those who received inpatient CPM post-MUA and those who received day-case MUA alone. Complications and further interventions were noted. Results: Of 126 patients, 39 underwent MUA only (day-case group), and 87 received CPM and MUA (inpatient group). Mean preoperative ROM was 69.4° (standard deviation [SD]:18.0°) and 73.9° (SD: 18.1°) for inpatient and day-case groups, respectively. Mean post-MUA ROM improved by 39.4° (SD: 17.7°) and 25.5° (SD: 11.1°) inpatient groups and day-case, respectively. The mean percentage of ROM gained at MUA maintained at final follow-up was 63.7% (40.8%) and 67.0% (47.5%) inpatient and day-case groups, respectively. Conclusions: This study found no advantage in the routine use of CPM post-MUA for stiff total knee replacement patients, suggesting it may not provide sustained ROM improvements compared to MUA alone. Cost-effectiveness and patient selection merit further investigation.

Are postoperative blood tests always required after lower limb arthroplasty?

Aims: It is common practice for patients to have postoperative blood tests after total joint replacement (TJR). However, there have been significant improvements in perioperative care with arthroplasty surgery, and a drive to reduce the length of stay (LOS) and move towards day-case TJR. We should reconsider whether this intervention is necessary for all patients. Methods: This retrospective study included all patients who underwent a primary unilateral TJR at a single tertiary arthroplasty centre during a one-year period. Electronic medical records of 1,402 patients were reviewed for patient demographics, LOS, and American Society of Anesthesiologists (ASA) grade. Blood tests were examined to investigate the incidence of postoperative anaemia, electrolyte abnormalities, and incidence of acute kidney injury (AKI). Results: For total knee arthroplasties, preoperative (R = -0.22) and postoperative haemoglobin (R = 0.2) levels were both negatively correlated with LOS (p < 0.001). For all patients who had undergone a TJR, 19 patients (0.014%) required a blood transfusion postoperatively due to symptomatic anaemia. Risk factors identified were age, preoperative anaemia, and long-term aspirin use. Significant abnormal sodium levels were found in123 patients (8.7%). However, only 36 patients (2.6%) required intervening treatment. Risk factors identified were age, preoperative abnormal sodium level, and long-term use of non-steroidal anti-inflammatory drugs, angiotensin receptor blockers, and corticosteroids. Similarly, abnormal potassium levels were evident in 53 patients (3.8%), and only 18 patients (1.3%) required intervening treatment. Risk factors identified were preoperative abnormal potassium level, and long-term use of angiotensin-converting enzyme inhibitors and diuretics. The incidence of AKI was 4.4% (61 patients). Risk factors identified were age, increased ASA grade, preoperative abnormal sodium, and creatinine level. Conclusion: Routine blood tests after primary TJR is unnecessary for most patients. Blood tests should only be performed on those with identifiable risk factors such as preoperative anaemia and electrolyte abnormalities, haematological conditions, long-term aspirin use, and electrolyte-altering medications.

Ceramic Coatings Confer No Survivorship Advantages in Total Knee Arthroplasty-A Single-Center Series of 1641 Knees.

Background: Ceramic coatings in total knee arthroplasty have been introduced with the aim of reducing wear and consequently improving implant survivorship. We studied both cobalt-chrome-molybdenum (CoCrMo) and ceramic-coated components of the same implant design from a single center to identify if the ceramic coating conferred any benefit. Methods: We identified 1641 Columbus total knee arthroplasties (Aesculap AG, Tüttlingen, Germany) from a prospectively collected arthroplasty database. Of the 1641, 983 were traditional CoCrMo, and 659 had the Columbus AS ceramic coating. Patients were followed up until death or revision of any component of the implant. Results: There was no significant difference in implant survivorship using any component revision as the endpoint between the CoCrMo femur and the ceramic-coated femur at a mean of 9.2 years in follow-up for the CoCrMo group and 5 years for the ceramic-coated group (37 vs 14; P = .76). There was no reduction in the proportion of components revised for aseptic loosening or infection in the ceramic-coated cohort. Conclusions: At midterm follow-up, there was no benefit in terms of implant survivorship in using a ceramic coating.

The impact of a revision arthroplasty network on patient outcomes.

Aims: Revision total knee arthroplasty (rTKA) and revision total hip arthroplasty (rTHA) are complex procedures with higher rates of re-revision, complications, and mortality compared to primary TKA and THA. We report the effects of the establishment of a revision arthroplasty network (the East Midlands Specialist Orthopaedic Network; EMSON) on outcomes of rTKA and rTHA. Methods: The revision arthroplasty network was established in January 2015 and covered five hospitals in the Nottinghamshire and Lincolnshire areas of the East Midlands of England. This comprises a collaborative weekly multidisciplinary meeting where upcoming rTKA and rTHA procedures are discussed, and a plan agreed. Using the Hospital Episode Statistics database, revision procedures carried out between April 2011 and March 2018 (allowing two-year follow-up) from the five network hospitals were compared to all other hospitals in England. Age, sex, and mean Hospital Frailty Risk scores were used as covariates. The primary outcome was re-revision surgery within one year of the index revision. Secondary outcomes were re-revision surgery within two years, any complication within one and two years, and median length of hospital stay. Results: A total of 57,621 rTHA and 33,828 rTKA procedures were performed across England, of which 1,485 (2.6%) and 1,028 (3.0%), respectively, were conducted within the network. Re-revision rates within one year for rTHA were 7.3% and 6.0%, and for rTKA were 11.6% and 7.4% pre- and postintervention, respectively, within the network. This compares to a pre-to-post change from 7.4% to 6.8% for rTHA and from 11.7% to 9.7% for rTKA for the rest of England. In comparative interrupted time-series analysis for rTKA there was a significant immediate improvement in one-year re-revision rates for the revision network compared to the rest of England (p = 0.024), but no significant change for rTHA (p = 0.504). For the secondary outcomes studied, there was a significant improvement in trend for one- and two-year complication rates for rTHA for the revision network compared to the rest of England. Conclusion: Re-revision rates for rTKA and complication rates for rTHA improved significantly at one and two years with the introduction of a revision arthroplasty network, when compared to the rest of England. Most of the outcomes studied improved to a greater extent in the network hospitals compared to the rest of England when comparing the pre- and postintervention periods.

Should patient age thresholds dictate fixation strategy in total hip arthroplasty?

AIMS: Total hip arthroplasty (THA) is a very successful and cost-effective operation, yet debate continues about the optimum fixation philosophy in different age groups. The concept of the 'cementless paradox' and the UK 'Getting it Right First Time' initiative encourage increased use of cemented fixation due to purported lower revision rates, especially in elderly patients, and decreased cost. METHODS: In a high-volume, tertiary referral centre, we identified 10,112 THAs from a prospectively collected database, including 1,699 cemented THAs, 5,782 hybrid THAs, and 2,631 cementless THAs. The endpoint was revision for any reason. Secondary analysis included examination of implant survivorship in patients aged over 70 years, over 75 years, and over 80 years at primary THA. RESULTS: Cemented fixation had the lowest implant survival in all age groups, with a total ten-year survivorship of 97.0% (95% confidence interval (CI) 95.8 to 97.8) in the cemented group, 97.6% (95% CI 96.9 to 98.1) in the hybrid group, and 97.9% (95% CI 96.9 to 98.6) in the cementless group. This was not statistically significant (p = 0.092). There was no age group where cemented fixation outperformed hybrid or cementless fixation. CONCLUSION: While all fixation techniques performed well at long-term follow-up, cemented fixation was associated with the lowest implant survival in all age groups, including in more elderly patients. We recommend that surgeons should carefully monitor their own outcomes and use fixation techniques that they are familiar with, and deliver the best outcomes in their own hands. Cite this article: Bone Joint J 2022;104-B(2):206-211.

Meta-analysis and metaregression of risk factors associated with mortality in hip fracture patients during the COVID-19 pandemic.

Incidence of hip fractures has remained unchanged during the pandemic with overlapping vulnerabilities observed in patients with hip fractures and those infected with COVID-19. We aimed to investigate the independent impact of COVID-19 infection on the mortality of these patients. Healthcare databases were systematically searched over 2-weeks from 1st-14th November 2020 to identify eligible studies assessing the impact of COVID-19 on hip fracture patients. Meta-analysis of proportion was performed to obtain pooled values of prevalence, incidence and case fatality rate of hip fracture patients with COVID-19 infection. 30-day mortality, excess mortality and all-cause mortality were analysed using a mixed-effects model. 22 studies reporting 4015 patients were identified out of which 2651 (66%) were assessed during the pandemic. An excess mortality of 10% was seen for hip fractures treated during the pandemic (OR 2.00, p = 0.007), in comparison to the pre-pandemic controls (5%). Estimated mortality of COVID-19 positive hip fracture patients was four-fold (RR 4.59, p < 0.0001) and 30-day mortality was 38.0% (HR 4.73, p < 0.0001). The case fatality rate for COVID-19 positive patients was 34.74%. Between-study heterogeneity for the pooled analysis was minimal (I2 = 0.00) whereas, random effects metaregression identified subgroup heterogeneity for male gender (p < 0.001), diabetes (p = 0.002), dementia (p = 0.001) and extracapsular fractures (p = 0.01) increased risk of mortality in COVID-19 positive patients.

Low Intensity Pulsed Ultrasound Therapy (LIPUS): A review of evidence and potential applications in diabetics.

Low Intensity Pulsed Ultrasound Therapy (LIPUS) is a non-invasive treatment and aims to reduce fracture healing time and avoid non-union by delivering micro-mechanical stress to the bone to stimulate bone healing. In 2018, the National Institute for Health and Clinical Excellence (NICE) recommended that the evidence for LIPUS to promote healing of delayed-union and non-union fractures raised no major safety concerns, but the current evidence on efficacy is inadequate in quality. Little is known about the potential benefits of LIPUS for fracture healing in diabetic patients. In this article, we review the current evidence of LIPUS therapy both in animal and human studies and its possible application on fractures in diabetics.

Assessing for Cardiotoxicity from Metal-on-Metal Hip Implants with Advanced Multimodality Imaging Techniques.

BACKGROUND: High failure rates of metal-on-metal (MoM) hip implants prompted regulatory authorities to issue worldwide safety alerts. Circulating cobalt from these implants causes rare but fatal autopsy-diagnosed cardiotoxicity. There is concern that milder cardiotoxicity may be common and underrecognized. Although blood metal ion levels are easily measured and can be used to track local toxicity, there are no noninvasive tests for organ deposition. We sought to detect correlation between blood metal ions and a comprehensive panel of established markers of early cardiotoxicity. METHODS: Ninety patients were recruited into this prospective single-center blinded study. Patients were divided into 3 age and sex-matched groups according to implant type and whole-blood metal ion levels. Group-A patients had a ceramic-on-ceramic [CoC] bearing; Group B, an MoM bearing and low blood metal ion levels; and Group C, an MoM bearing and high blood metal-ion levels. All patients underwent detailed cardiovascular phenotyping using cardiac magnetic resonance imaging (CMR) with T2*, T1, and extracellular volume mapping; echocardiography; and cardiac blood biomarker sampling. T2* is a novel CMR biomarker of tissue metal loading. RESULTS: Blood cobalt levels differed significantly among groups A, B, and C (mean and standard deviation [SD], 0.17 ± 0.08, 2.47 ± 1.81, and 30.0 ± 29.1 ppb, respectively) and between group A and groups B and C combined. No significant between-group differences were found in the left atrial or ventricle size, ejection fraction (on CMR or echocardiography), T1 or T2* values, extracellular volume, B-type natriuretic peptide level, or troponin level, and all values were within normal ranges. There was no relationship between cobalt levels and ejection fraction (R = 0.022, 95% confidence interval [CI] = -0.185 to 0.229) or T2* values (R = 0.108, 95% CI = -0.105 to 0.312). CONCLUSIONS: Using the best available technologies, we did not find that high (but not extreme) blood cobalt and chromium levels had any significant cardiotoxic effect on patients with an MoM hip implant. There were negligible-to-weak correlations between elevated blood metal ion levels and ejection fraction even at the extremes of the 95% CI, which excludes any clinically important association. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Management of metal-on-metal hip implant patients: Who, when and how to revise?

The debate on how best to manage patients with metal-on-metal (MOM) hip implants continues. With over 1 million patients affected worldwide, the impact is far reaching. The majority of the aggressive failures of MOM hip implants have been dealt with by revision hip surgery, leaving patients with a much more indolent pattern of failure of devices that have been in situ for more than 10 years. The longer-term outcome for such patients remains unknown, and much debate exists on how best to manage these patients. Regulatory guidance is available but remains open to interpretation due to the lack of current evidence and long-term studies. Metal ion thresholds for concern have been suggested at 7 ppb for hip resurfacing arthroplasty and below this level for large diameter total hip arthroplasties. Soft tissue changes including pseudotumours and muscle atrophy have been shown to progress, but this is not consistent. New advanced imaging techniques are helping to diagnose complications with metal hips and the reasons for failure, however these are not widely available. This has led to some centres to tackle difficult cases through multidisciplinary collaboration, for both surgical management decisions and also follow-up decisions. We summarise current evidence and consider who is at risk, when revision should be undertaken and how patients should be managed.