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Background: Metal debris and corrosion products generated from the taper junctions of modular joint replacements have been recognized as contributors to failure. Therefore, understanding the factors associated with increased taper wear and corrosion is fundamental to improving implant performance.Methods: A cohort of 85 large-diameter metal-on-metal heads and cups retrieved at revision surgery, after 10 to 96 months of service, was evaluated. First, metrology was conducted to quantify head taper material loss and implant articular surface wear. Then, joint frictional moments for each retrieved head-and-cup pair were measured during 10 cycles of simulated physiological gait in a biomechanical model. Taper material loss was evaluated for correlations with frictional moments, articular wear, head diameter, head-cup clearance, and time in vivo.Results: Peak resultant frictional moments ranged from 9.1 to 26.3 Nm, averaging 17.3 ± 2.7 Nm. Fretting and corrosion damage during in vivo service resulted in material loss from the head tapers ranging between 0.04 and 25.57 mm3, compared with combined head and cup articular wear of 0.80 to 351.75 mm3 in this cohort. Taper material loss was not correlated with higher frictional moments (R = -0.20 to 0.11, p = 0.07 to 0.81). Higher frictional moments from axial rotation were correlated with higher head and cup wear (R = 0.33, p < 0.01). The correlation between taper material loss and head diameter was weak and did not reach statistical significance (R = 0.20, p = 0.07). Taper material loss was not correlated with nominal head-cup clearance (R = 0.06, p = 0.6). Finally, taper material loss increased significantly over time (R = 0.34, p < 0.01).Conclusions: Despite serious concerns regarding trunnionosis, volumes of head taper wear were generally lower than those of articular surface wear. There was no statistical correlation between taper wear and frictional moments. Therefore, the results suggest that high friction in metal-on-metal implants does not contribute to higher material loss at the head taper, despite high bending moments.Clinical Relevance: The amount of metal debris and corrosion products from taper junctions of the joint arthroplasties, widely recognized as an insidious cause of failure, was not correlated with joint frictional moments. Multiple factors affect taper wear: implant design, material, size, surface finish, and patient weight and activity level. However, in the present cohort, high friction of metal-on-metal total hip replacements likely did not contribute to increased volume of material loss at taper interfaces, despite increased moments at the locations of taper material loss. [ABSTRACT FROM AUTHOR]

In the current study, the accuracy of the impingement-free ROM prediction was considered validated by testing the results in a patient-specific 3-D computer-aided design model, which was used to evaluate ROM in 10 patients who underwent robotic-assisted THA [[15]]. One of John Charnley's priorities when he designed the first successful THA more than 50 years ago was to minimize friction at the joint bearing surfaces. If offered as a software tool, the method has the potential of providing key information for planning THA surgeries and predicting the risk of dislocation in patient-specific situations. CORR Insights®: A Modeling Study of a Patient-specific Safe Zone for THA: Calculation, Validation, and Key Factors Based on Standing and Sitting Sagittal Pelvic Tilt. [Extracted from the article]

Background: Developed at the University of Iowa in 1950, the Ponseti method to manage idiopathic clubfoot deformity was slow to gain wide acceptance until the mid-1990s. There is a paucity of intermediate and long-term outcome studies involving this technique, with nearly all such studies coming from a single institution. The purpose of this study is to report the contemporary outcome of patients with clubfoot deformity whose feet were managed with the Ponseti method and who were followed to ≥5 years old, to provide outcome expectations for parents and for clinicians managing patients with idiopathic clubfoot.Methods: Families of infants seen in our clinic diagnosed with idiopathic clubfoot since July 2006 were prospectively invited to participate in our institutional review board-approved study. Patients who received no prior outside treatment and had a minimum follow-up to the age of 5 years were included. Demographic, treatment, and outcome data were collected. To provide an array of outcome measures, both the Dallas outcome criteria and the Roye disease-specific instrument (DSI) were used.Results: One hundred and one patients met the inclusion criteria. The mean length of follow-up (and standard deviation) was 81.1 ± 17.1 months. Initial correction was achieved in all feet. Thirty-seven percent of families reported that they were adherent with the bracing protocol; 68% of patients had ≥1 relapse, and 38% underwent a tendon transfer. With the Dallas criteria, 62% had outcomes rated as good, 38% had outcomes rated as fair, and no patient had an outcome rated as poor. With the Roye DSI, most families were generally very satisfied with the function and appearance of the feet.Conclusions: Satisfactory results at intermediate follow-up were achieved using the Ponseti method. However, despite a better understanding of the Ponseti method and the importance of longer post-corrective brace use, the need for anterior tibial tendon transfer remains an important adjunct to the Ponseti method. Brace adherence also continues to be a critical clinical issue.Level Of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

In the article, the author comments on the issue of oxidation in never-irradiated ultra-high molecular weight polyethylene (UHMWPE) components from revised hip, shoulder, knee, and ankle joint replacements. Other topics include the developments on the use of polyethylene material in joint replacement, and the effects of gamma irradiation on the sterilization of implants.

Background: In 2010, a widely used metal-on-metal hip implant design was voluntarily recalled by the manufacturer because of higher than anticipated failure rates at 5 years. Although there was a large published range of revision rates, numerous studies had reported a higher risk of revision for excessive wear and associated adverse tissue reactions when compared with other metal-on-metal total hips. The reasons for this were suggested by some to be related to cup design features.Questions/purposes: From retrievals of ASR metal-on-metal implants and tissue samples obtained at revision surgery, we asked the following questions: (1) What were the common and uncommon surface features? (2) What were the common and uncommon linear and volumetric wear characteristics? (3) Were there common taper corrosion characteristics? (4) What aseptic lymphocytic vasculitis-associated lesion (ALVAL) features were present in the tissues?Methods: Five hundred fifty-five ASRs, including 23 resurfacings, were studied at one academic research center. Features of wear (eg, light and moderate scratching), damage (eg, deposits, gouges), and bone attachment on the porous coating were semiquantitatively ranked from 0 (none) to 3 (> 75%) based on the amount of a feature in each region of interest by the same experienced observer throughout the study. Visible features of head taper corrosion were ranked (Goldberg score) from 1 (none) to 4 (severe) by the same observer using a previously published scoring method. An experienced tribologist measured component wear depth using a coordinate measuring machine and quantified wear volume using previously validated methods. All available tissues were sampled and examined for features of ALVAL and scored from 0 to 10 by a single observer using a method they previously developed and published. A score from 0 to 4 is considered low, 5 to 8 is considered moderate, and 9 or 10 is considered high with regard to the risk of metal hypersensitivity features in the tissues.Results: The most common bearing surface features were light and moderate scratches and removal or postremoval damage. Discoloration and deposits were commonly observed on femoral heads (55% [305 of 553]) and less commonly on cups (30% [165 of 546]). There was no evidence of impingement or dislocation damage. There was typically a small amount of bone attachment in at least one of eight designated regions of interest (84% [460 of 546]); extensive or no bone attachment was uncommon. Edge wear was highly prevalent. The maximum wear of 469 cups (88%) occurred near the edge, whereas the maximum wear of 508 femoral heads (94%) occurred between the pole and 45° from the pole. The median combined head-cup wear volume was 14 mm (range, 1-636 mm). One hundred sixty-nine pairs (32%) had a combined wear volume of < 10 mm, 42 pairs (8%) had volumetric wear of > 100 mm, and 319 pairs (60%) had wear volume between 10 and 100 mm³. Seventy-four percent of tapers (390 of 530) received a Goldberg score of 4, 22% (116 of 530) a score of 3, < 5% (24 of 530) a score of 2, and none received a score of 1. The most frequent ALVAL score was 5 out of 10 (35 of 144 hips [24%]) and ranged from 2 (one hip) to 10 (nine hips); 92 of 144 (64%) had a moderate score, 17 of 144 (12%) had a high score, and 35 (24%) had a low score.Conclusions: Although edge wear was prevalent, in most cases, this was not associated with high wear. The increased diameter and decreased coverage angle of the ASR design may have resulted in the observed high incidence of edge wear while perhaps decreasing the risk for impingement and dislocation.Clinical Relevance: The role of bearing wear in the revisions of metal-on-metal implants is controversial, because it is known that there is a large range of in vivo wear rates even within the same implant type and that patient variability affects local tissue responses to wear debris. The observations from our study of 555 retrieved ASR implant sets indicate that there was a wide range of wear including a subset with very high wear. The results suggested that the failure of the ASR and ASR XL was multifactorial, and the failure of different subgroups such as those with low wear may be the result of mechanisms other than reaction to wear debris. [ABSTRACT FROM AUTHOR]

Background: A successful outcome for the treatment of idiopathic clubfoot is believed to require adequate adherence to brace use. Previous studies have relied on parental reporting of brace application. We used temperature sensors to determine the adherence to the bracing protocol, the accuracy of parent-reported use, and differences in adherence between patients who experienced relapse of deformity and those who did not.Methods: Using wireless sensors attached to brace sandals, we monitored brace wear over a 3-month period in this cross-sectional study involving 48 patients in 4 age-based groups: 6 to 12 months (Group 1), >1 to 2 years (Group 2), >2 to 3 years (Group 3), and >3 to 4 years (Group 4). Parents were blinded to the purpose of the sensors. The mean number of hours of daily brace use as measured by the sensors was compared with the physician-recommended hours and parent-reported hours of brace use.Results: Sensors were retrieved from 44 of 48 patients. Overall, the median brace use recorded by the sensors was 62% (range, 5% to 125%) of that recommended by the physician, and 77% (range, 6% to 213%) of that reported by the parents. For Groups 1 to 3, the difference between the physician-recommended and measured number of hours of daily brace use was significant (p ≤ 0.002), and the difference between the parent-reported and measured number of hours of daily brace use was also significant (p ≤ 0.013). Eight (18%) of the 44 patients who completed the study experienced relapse during the period of monitoring; most importantly, the mean number of hours of brace wear for these patients, 5 hours per day (median, 4; and standard deviation [SD], 3 hours per day) was significantly lower than the 8 hours per day for those who did not experience relapse (median, 9; and SD, 5 hours per day) (p = 0.045).Conclusions: The present study objectively quantified the number of daily hours of post-corrective brace wear for patients with clubfoot in varying age groups and provides an estimate of the number of hours required to avoid relapse.Level Of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

The article offers information on spinal fusion related to the changes in acetabular orientation and reductions in pelvic mobility. It mentions that there is a relationship between acetabular tilt in the sagittal plane and the motion of the sacrum in patients with no spine or hip disorders. It focuses on standing-to-sitting alignment of the lumbar spine, pelvis, and femur.

The article presents a study which highlights the importance of retrieval analysis in the process of implant design and development. It mentions that Retrieval analyses call for advanced technology, including high-resolution metrology equipment and software for the quantification of extremely small changes in dimensions and surface textures.

Unlabelled: Liner cementation into a preexisting stable socket may reduce the morbidity of revision hip arthroplasty and preserve acetabular bone. However, the long-term outcomes of this technique remain unknown. The purpose of this report was to analyze the long-term results of a previously reported cohort of patients. Cementation of thirty-two liners (seventeen polyethylene and fifteen metal liners) into preexisting sockets was performed during revision hip arthroplasty, and the patients were followed for a minimum of two years. A retrospective chart review was performed to investigate the complications and survivorship. The mean duration of follow-up was 12.7 years (range, 2.1 to 19.1 years), with ten hips requiring rerevision at a mean of 6.4 years (range, 1.0 to 15.5 years). Nine patients experienced posterior dislocations, and two hips required rerevision for instability. Liner dissociation from the shell occurred in two patients. Survivorship analysis, with rerevision as the end point, demonstrated ten and fifteen-year survivorship of 77.3% and 68.8%, respectively. Dissociation of the cemented liner from the acetabular shell was an infrequent cause of failure despite long-term follow-up. Given the high rate of dislocations in this study, careful patient selection and surgical technique should be considered.Level Of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Liner cementation into a preexisting stable socket may reduce the morbidity of revision hip arthroplasty and preserve acetabular bone. However, the long-term outcomes of this technique remain unknown. The purpose of this report was to analyze the long-term results of a previously reported cohort of patients. Cementation of thirty-two liners (seventeen polyethylene and fifteen metal liners) into preexisting sockets was performed during revision hip arthroplasty, and the patients were followed for a minimum of two years. A retrospective chart review was performed to investigate the complications and survivorship. The mean duration of follow-up was 12.7 years (range, 2.1 to 19.1 years), with ten hips requiring rerevision at a mean of 6.4 years (range, 1.0 to 15.5 years). Nine patients experienced posterior dislocations, and two hips required rerevision for instability. Liner dissociation from the shell occurred in two patients. Survivorship analysis, with rerevision as the end point, demonstrated ten and fifteen-year survivorship of 77.3% and 68.8%, respectively. Dissociation of the cemented liner from the acetabular shell was an infrequent cause of failure despite long-term follow-up. Given the high rate of dislocations in this study, careful patient selection and surgical technique should be considered. [ABSTRACT FROM AUTHOR]

The author discusses the study of Boutin and colleagues on the unexplored variables related to knuckle cracking such as swelling, joint laxity and weakness immediately before and after cracking. It mentions that the results of the study show that knuckle cracking does not have an adverse effects on grip strength and swelling. the author adds that the study need to be reinforced by a restrospective research.

Background: There is a general perception that adverse local tissue reactions in metal-on-metal hip arthroplasties are caused by wear, but the degree to which this is the case remains controversial. Questions/purposes: To what extent is the magnitude of wear associated with (1) the histological changes; (2) presence of metallosis; and (3) likelihood of pseudotumor formation in the periprosthetic tissues? Methods: One hundred nineteen metal-on-metal total hip arthroplasties and hip resurfacings were selected from a retrieval collection of over 500 implants (collected between 2004 and 2012) based on the availability of periprosthetic tissues collected during revision, clinical data including presence or absence of pseudotumor or metallosis observed intraoperatively, and wear depth measured using a coordinate measurement machine. Histological features of tissues were scored for aseptic lymphocytic vasculitis-associated lesions (ALVAL). Correlation analysis was performed on the three endpoints of interest. Results: With the sample size available, no association was found between wear magnitude and ALVAL score (ρ = −0.092, p = 0.423). Median wear depth (ball and cup) was greater in hips with metallosis (137 μm; range, 8-873 μm) than in those without (18 μm; range, 8-174 μm; p < 0.0001). With the numbers available, no statistically significant association between wear depth and pseudotumor formation could be identified; median wear depth was 74 μm in hips with pseudotumors and 26 μm in those without (p = 0.741). Conclusions: Wear alone did not explain the histopathological changes in the periprosthetic tissues. A larger sample size and more sensitive outcome variable assessments may have revealed a correlation. However, wear depth has been inconsistently associated with pseudotumor formation, perhaps because some patients with hypersensitivity may develop pseudotumors despite low wear. Clinical Relevance: Metal wear alone may not explain the histological reactions and pseudotumors around metal-on-metal hip implants. [ABSTRACT FROM AUTHOR]

Background: The Ponseti method is an established approach to treating idiopathic clubfoot in infants. The method involves a period of cast immobilization and postcorrective bracing that potentially interferes with normal movements of the lower extremities. In the present study, we investigated the age at which infants who had idiopathic clubfoot treated using the Ponseti method achieved independent walking. Methods: We prospectively evaluated patients of a single surgeon. Included in the study were all patients with idiopathic clubfoot who were full term at birth, were no more than twelve weeks of age at the start of treatment, had received no prior outside treatment, and were followed for a minimum of twenty-four months. Results: Ninety-four patients were included. The mean age at which patients began walking independently was 14.5 ± 2.6 months (range, ten to twenty-two months). By eighteen months, 90% of the patients were walking without assistance. Patients with moderate or severe clubfoot deformity began walking earlier than did patients with very severe deformity (a mean of 14.2 months compared with 15.8 months; p = 0.03). Patients who experienced a relapse before learning to walk began walking later than those who did not relapse (a mean of 15.9 months compared with 14.2 months; p = 0.04). Other patient and treatment-related variables had no significant influence on the onset of walking. Conclusions: On the basis of our findings, parents of infants with idiopathic clubfoot treated using the Ponseti method may expect their child to achieve independent walking approximately two months later than infants without clubfoot deformity. A greater delay may be expected for those patients who have a very severe deformity or those who experience a deformity relapse. [ABSTRACT FROM AUTHOR]

Background: Component design, size, acetabular orientation, patient gender, and activity level have been suggested as factors leading to elevated metal ion concentrations after-on-metal hip resurfacing arthroplasty (MMHRA). The calculation of the contact patch to rim (CPR) distance integrates component size, design, and acetabular orientation and may be a good predictor of elevated metal ion levels. Questions/purposes: We evaluated the effects and the predictive value of the CPR distance on serum cobalt (CoS) and chromium (CrS) ion levels. Methods: We retrospectively studied 182 patients with Conserve Plus MMHRAs at a minimum of 12 months after surgery (median, 57 months; range, 12-165 months). CoS and CrS levels were analyzed using inductively-coupled plasma mass spectrometry. Multiple logistic regression was performed to determine which if any of the factors related to serum ion levels. Results: Patients with CPR distances of 10 mm or less had a 37-fold increased risk of having elevated CoS of 7 μg/L or higher. Similarly, these patients had an 11-fold increased risk of having elevated CrS of 7 μg/L or higher. Sex and University of California Los Angeles activity scores did not influence the postoperative CoS and CrS levels. The negative predictive value for CPR distance less than 10 mm was 99.3% for CoS greater than 7 μg/L and 98.0% for CrS greater than 7 μg/L. Conclusions: Our observations suggest the CPR distance would be a useful indicator to determine which patients are at risk for elevated ion levels. Patients with CPR distances greater than 10 mm need not be monitored unless they become symptomatic. [ABSTRACT FROM AUTHOR]

Background: Many orthopaedic surgeons treat tibial shaft fractures in children with a period of non-weight-bearing after application of a long leg cast, presumably to prevent fracture angulation and shortening. We hypothesized that allowing children to immediately bear weight as tolerated in a cast with the knee in 10° of flexion would lessen disability, without increasing the risk of unacceptable shortening or angulation. Methods: We divided eighty-one children, between the ages of four and fourteen years, with a low-energy, closed tibial shaft fracture into two groups. One group (forty children) received a long leg cast with the knee flexed 60° and were asked not to bear weight. The second group (forty-one children) received a long leg cast with the knee flexed 10° and were encouraged to bear weight as tolerated. All patients were switched to short leg walking casts at four weeks. We compared time to healing, overall alignment, shortening, and physical disability as determined by the Activities Scale for Kids-Performance (ASK-P) questionnaire. Results: The mean time to fracture union was 10.8 weeks in both groups (p = 0.47). At the time of healing, mean coronal alignment was within 1.3° in both groups, mean sagittal alignment was within 1°, and mean shortening was <0.5 mm, with no significant differences. The ASK-P scores showed that both groups had overall improvement in physical functioning over time. However, at six weeks, the children who were allowed to bear weight as tolerated had better overall scores (p = 0.03) and better standing skills (p = 0.01) than those who were initially instructed to be non-weight-bearing. Conclusions: Children with low-energy tibial shaft fractures can be successfully managed by immobilizing the knee in 10° of flexion and encouraging early weight-bearing, without affecting the time to union or increasing the risk of angulation and shortening at the fracture site. [ABSTRACT FROM AUTHOR]

Background: Metal-on-metal and ceramic-on-ceramic bearings were introduced as alternatives to conventional polyethylene in hip arthroplasties to reduce wear. Characterization of wear particles has been particularly challenging due to the low amount and small size of wear particles. Current methods of analysis of such particles have shortcomings, including particle loss, clumping, and inaccurate morphologic and chemical characterization. Questions/purposes: We describe a method to recover and characterize metal and ceramic particles that (1) improves particle purification, separation, and display; (2) allows for precise particle shape characterization; (3) allows accurate chemical identification; and (4) minimizes particle loss. Methods: After enzymatic digestion, a single pass of ultracentrifugation cleaned and deposited particles onto silicon wafers or grids for imaging analysis. During centrifugation, particles were passed through multiple layers of denaturants and a metal-selective high-density layer that minimized protein and nucleic acid contamination. The protocol prevented aggregation, providing well-dispersed particles for chemical and morphologic analysis. We evaluated the efficacy and accuracy of this protocol by recovering gold nanobeads and metal and ceramic particles from joint simulator wear tests. Results: The new protocol recovered particles ranging in size from nanometers to micrometers and enabled accurate morphologic and chemical characterization of individual particles. Conclusion: Both polyethylene and metal wear debris can be simultaneously analyzed from the same sample by combining a silicon wafer display protocol for polyethylene and the metal and ceramics silicon wafer display protocol. Clinical Relevance: Accurate analysis of wear debris is essential in understanding the processes that produce debris and a key step in development of more durable and biocompatible implants. [ABSTRACT FROM AUTHOR]

Background: Numerous studies indicate highly crosslinked polyethylenes reduce the wear debris volume generated by hip arthroplasty acetabular liners. This, in turns, requires new methods to isolate and characterize them. Questions/purposes: We describe a method for extracting polyethylene wear particles from bovine serum typically used in wear tests and for characterizing their size, distribution, and morphology. Methods: Serum proteins were completely digested using an optimized enzymatic digestion method that prevented the loss of the smallest particles and minimized their clumping. Density-gradient ultracentrifugation was designed to remove contaminants and recover the particles without filtration, depositing them directly onto a silicon wafer. This provided uniform distribution of the particles and high contrast against the background, facilitating accurate, automated, morphometric image analysis. The accuracy and precision of the new protocol were assessed by recovering and characterizing particles from wear tests of three types of polyethylene acetabular cups (no crosslinking and 5 Mrads and 7.5 Mrads of gamma irradiation crosslinking). Results: The new method demonstrated important differences in the particle size distributions and morphologic parameters among the three types of polyethylene that could not be detected using prior isolation methods. Conclusion: The new protocol overcomes a number of limitations, such as loss of nanometer-sized particles and artifactual clumping, among others. Clinical Relevance: The analysis of polyethylene wear particles produced in joint simulator wear tests of prosthetic joints is a key tool to identify the wear mechanisms that produce the particles and predict and evaluate their effects on periprosthetic tissues. [ABSTRACT FROM AUTHOR]

Pseudotumor-like periprosthetic tissue reactions around metal-on-metal (M-M) hip replacements can cause pain and lead to revision surgery. The cause of these reactions is not well understood but could be due to excessive wear, or metal hypersensitivity or an as-yet unknown cause. The tissue features may help distinguish reactions to high wear from those with suspected metal hypersensitivity. We therefore examined the synovial lining integrity, inflammatory cell infiltrates, tissue organization, necrosis and metal wear particles of pseudotumor-like tissues from M-M hips revised for suspected high wear related and suspected metal hypersensitivity causes. Tissue samples from 32 revised hip replacements with pseudotumor-like reactions were studied. A 10-point histological score was used to rank the degree of aseptic lymphocytic vasculitis-associated lesions (ALVAL) by examination of synovial lining integrity, inflammatory cell infiltrates, and tissue organization. Lymphocytes, macrophages, plasma cells, giant cells, necrosis and metal wear particles were semiquantitatively rated. Implant wear was measured with a coordinate measuring machine. The cases were divided into those suspected of having high wear and those suspected of having metal hypersensitivity based on clinical, radiographic and retrieval findings. The Mann-Whitney test was used to compare the histological features in these two groups. The tissues from patients revised for suspected high wear had a lower ALVAL score, fewer lymphocytes, but more macrophages and metal particles than those tissues from hips revised for pain and suspected metal hypersensitivity. The highest ALVAL scores occurred in patients who were revised for pain and suspected metal hypersensitivity. Component wear was lower in that group. Pseudotumor-like reactions can be caused by high wear, but may also occur around implants with low wear, likely because of a metal hypersensitivity reaction. Histologic features including synovial integrity, inflammatory cell infiltrates, tissue organization, and metal particles may help differentiate these causes. Painful hips with periprosthetic masses may be caused by high wear, but if this can be ruled out, metal hypersensitivity should be considered. [ABSTRACT FROM AUTHOR]

Background: In the late 1990s, renewed interest emerged in less invasive treatment options, most notably the Ponseti method, to correct idiopathic clubfoot deformity. Recently, reports from several centers have demonstrated that such minimally invasive techniques may be used reliably to correct this complex deformity. The present study sought to determine whether the rate of extensive surgical releases to treat idiopathic clubfoot in the United States has decreased. Methods: We used data from the Centers for Disease Control and Prevention and the Nationwide Inpatient Sample to determine the number of live births, the number of patients diagnosed with clubfoot, and the number of extensive surgical releases that were performed each year from 1996 to 2006. The trends over time were evaluated with use of regression analysis, and changes in frequency were analyzed with use of time series analysis. The percentage of clubfeet that were treated with surgery in each year was calculated by dividing the number of surgical release procedures by the number of clubfoot diagnoses. Results: Between 1996 and 2006, the estimated number of patients under six months of age diagnosed with clubfoot remained fairly constant, averaging 2140 infants per year. The linear equation estimated a slight decrease of approximately thirty-one infants with clubfoot per year (R2 = 0.51, p < 0.05). In contrast, in the same decade, the estimated number of surgical releases performed in patients less than twelve months of age decreased substantially, from 1641 releases in 1996 to 230 releases in 2006. The linear equation estimated a decrease of approximately 157 surgical releases per year (R2 = 0.83, p < 0.05). The trend analysis indicated that the percentage of clubfeet treated with surgical release generally decreased over time at a rate of 6.7% per year, decreasing from just over 70% in 1996 to just over 10% in 2006 (R2 = 0.81, p < 0.05). Conclusions: In the United States between 1996 and 2006, the rate of extensive surgery to treat idiopathic clubfoot in patients less than twelve months old decreased substantially. This trend is likely due to an increased use of less invasive techniques, such as the Ponseti method, which a growing body of evidence has shown to be a viable treatment option for clubfoot. [ABSTRACT FROM AUTHOR]

Background: Functional and health-related quality-of-life data on a population of patients with hallux valgus are lacking. Similarly, the correlation of the severity of the deformity with these measures is unknown. Methods: Two hundred and eighty-five women with an average age of forty-nine years who were scheduled for bunion surgery were enrolled in the study. The patients completed a baseline American Academy of Orthopaedic Surgeons (AAOS) foot and ankle outcomes questionnaire, which includes the Short Form-36 (SF-36) and a specific lower-extremity section on the foot and ankle. Preoperative radiographic data with regard to the hallux valgus angle and the intermetatarsal angle were stratified into groups according to the severity of the deformity (mild, moderate, or severe). The data were then stratified into age-groups consistent with those reported for the SF-36, and the results were compared with the SF-36 scores for the general population. The global foot and ankle score and the shoe comfort score were compared with general population scores that were published previously. The severity of the preoperative deformity was correlated with the baseline scores. Results: General health scores were noted to be relatively stable throughout the age-groups for patients with bunions, with the older groups demonstrating better scores than the general population. Bodily pain scores were consistently worse for patients with a bunion through all age-groups compared with the general population. The average global foot and ankle score and the shoe comfort score were significantly lower (p < 0.001 for both) for the patients with a bunion than for the general population. The severity of the preoperative deformity did not correlate with any of the outcome scores. Conclusions: The bodily pain score from the SF-36 appears to be a sensitive measure of problems experienced by patients undergoing bunion surgery. Surprisingly, the severity of the deformity as measured radiographically did not correlate with any of the fifteen scores measured. These data may serve as a baseline for clinical hallux valgus studies with use of the SF-36 or the AAOS outcomes questionnaire. [ABSTRACT FROM AUTHOR]

Background: Although the orientation of the femoral component has been shown to influence the outcome of total hip replacement, its effect on the clinical outcome of surface arthroplasty has not been studied, to our knowledge. The purpose of this study was to examine the relationship between femoral component positioning and the outcome of a surface arthroplasty of the hip. Methods: We reviewed the results of ninety-four hybrid metal-on-metal surface arthroplasties in patients who were forty years old or younger at the time of the operation and were followed for a minimum of two years or until the prosthesis failed. Measurements of the hip reconstruction were made on the anteroposterior pelvic radiograph. The correlation between the orientation of the femoral component and the outcome of the arthroplasty was evaluated, as were stresses within the resurfaced femoral head as a function of the orientation of the femoral component. Results: The mean duration of follow-up was 4.2 years. Thirteen hips had an adverse outcome, defined as conversion to a total hip replacement, radiolucency of >1 mm in thickness adjacent to the femoral stem, or narrowing of the femoral neck of >10%. The mean femoral stem-shaft angle in the coronal plane was 138°, with the hips that had an adverse outcome having a significantly lower mean angle than the rest of the cohort (133° compared with 139°, p 0.03). Hips with an angle of ≤130° had an increase in the relative risk of an adverse outcome by a factor of 6.1 (p < 0.004). In the entire cohort, stresses in the superior aspect of the resurfaced femoral head were substantially lower during slow walking than they were during fast walking (7.1 N/mm² compared with 14.2 N/mm²). Conclusions: Optimizing the femoral stem-shaft angle toward a valgus orientation during the preparation of the femoral head is important when a hip is being reconstructed with a surface arthroplasty because the resurfaced hip transmits the load through a narrow critical zone in the femoral head-neck region and the valgus angulation may reduce these stresses. Level of Evidence: Therapeutic study, Level III-2 (retrospective cohort study). See Instructions to Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Background: During revision hip replacement surgery, the cementless acetabular shell is often well fixed but the locking mechanism may be ineffective. Cementing a new liner into the existing acetabular shell (the double-socket technique) can provide a simple solution. The purposes of the present study were to review our initial clinical results and to define the potential limitations of this technique.Methods: Thirty-two hips with a preexisting well-fixed acetabular socket that had been in situ for an average of 8.6 years were treated with the insertion of a new polyethylene liner (seventeen hips) or a metal liner (fifteen hips) with use of cement. The indication for this technique was a deficient locking mechanism in twenty-two hips and the unavailability of a matching liner in ten hips. Anteroposterior radiographs of all hips were analyzed by a single independent reviewer.Results: The mean duration of follow-up was 5.1 years. Six hips required a reoperation after a mean of 29.7 months; the reasons for the reoperations included aseptic failure of the acetabular construct (four hips), instability (one hip), and sepsis (one hip). The University of California at Los Angeles hip scores improved significantly (p < 0.001) compared with the preoperative values; specifically, the mean score improved from 6.2 to 9.1 for pain, from 6.3 to 8.3 for walking, from 6.2 to 7.8 for function, and from 4.7 to 5.8 for activity. The prevalence of dislocation was 22%. Kaplan-Meier analysis with revision as the end point revealed a five-year survival rate of 78% (95% confidence interval, 55% to 91%).Conclusions: The double-socket technique is a good alternative to acetabular socket removal for suitable candidates who have a well-fixed cementless socket with an inner diameter that is larger than the outer diameter of the cemented liner. This technique preserves acetabular bone stock and permits conversion to alternate bearing surfaces. We believe, however, that removal of a well-fixed acetabular shell or the use of a constrained liner should be strongly considered for patients with a history of hip instability. [ABSTRACT FROM AUTHOR]

Background: Although current designs of cemented femoral stems for total hip replacement include both those with and those without a flanged shape at the proximal end, the influence of anteroposterior dorsal flanges on the fixation of the stem is not completely understood. The purpose of this study was to assess the effects of flanges on femoral stem stability and load transfer to the femur with use of an in vitro model. Methods: We measured femoral surface strains and three-dimensional micromotion in synthetic femora under cyclic loading with four types of stems: those with flanges and those without flanges in two sizes each. The four types of stems were otherwise identical; that is, all of them were straight, polished, and collarless. Stem-cement micromotion measurements and strain measurements were repeated with three stems of each type, whereas bone-cement micro- motion measurements were made with one stem of each type. Results: Flanges had a greater influence on femoral strains and micromotion than did the difference in the cement thickness resulting from the different stem sizes. Specifically, the flanged stems produced greater strains on the me- dial femoral surface but smaller strains on the anterior surface than did the non-flanged stems. Flanged stems achieved tighter mechanical interlock within the cement, but these stems increased bone-cement micromotion. Specifically, the motion per cycle of flanged stems within the cement mantle was smaller than that of non-flanged stems, whereas the motion per cycle of the cement mantle within the femoral canal was greater with the flanged stems than with the non-flanged stems. Conclusions: Flanges on a total hip femoral stem increase the interlock between the stem and the cement and decrease the proximal-medial stress-shielding. However, these advantages occur with increased bone-cement interface motion, which may be detrimental to the survival of the implant. [ABSTRACT FROM AUTHOR]

Background: The optimum surface roughness of cemented femoral stems used for total hip replacement is a subject of controversy. While rougher surfaces provide stronger cement adhesion, it has been hypothesized that polished, tapered, noncollared stems settle into the cement mantle, providing improved stability. However, the effects of surface finish on the stability of straight, cemented stems tapered only in the coronal plane are not known.Methods: Using composite model femora, we assessed the initial stability of a straight, cemented femoral stem as a function of surface roughness, the presence or absence of a collar, stem size, and the resultant cement thickness under simulated walking and stair-climbing loads. Otherwise identical stems were manufactured with polished or rough surfaces, with or without a collar, in two different sizes. We isolated these three variables and compared their relative contributions to the motion at the stem-cement interface throughout cyclic loading. We defined three indicators of stability: per-cycle motion, rate of migration, and final migration.Results: Surface roughness had a greater influence on per-cycle motions than did the presence or absence of a collar or cement thickness. Specifically, in the medial-lateral direction, per-cycle motion of polished stems was 43 micro m greater than that of rough stems (p < 0.01). None of the per-cycle motions decreased over the 77,000 load cycles. In contrast, with all stems, the rate of migration decreased over the course of cyclic loading, but the rate of migration of the polished stems was greater than that of the rough stems. Final migrations of the stems over the course of loading were generally distal, medial, and into retroversion. Compared with rough stems, polished stems had 8 to 18 micro m more axial migration (p < 0.001), 48 micro m more anterior-posterior migration (p < 0.001), and 0.4 degrees more rotational migration (p = 0.01).Conclusions: andClinical Relevance: The results indicated that, for cemented, straight femoral stems tapered only in the coronal plane, a rough surface offers the advantage of less per-cycle motion. These results may apply to widely used cemented stem designs based on the profile of the original Charnley femoral component, which has approximately parallel anterior and posterior aspects. [ABSTRACT FROM AUTHOR]

Although a number of methods are used to estimate polyethylene liner wear from radiographs of total hip replacements, there is no consensus with regard to the accuracy of these methods. The purpose of this study was to compare the accuracy of several such measurement methods with use of both laboratory radiographs and routine clinical radiographs. A phantom apparatus was designed to simulate random values of three-dimensional wear, with varying degrees of cup abduction and anteversion, and to obtain anteroposterior and cross-table lateral radiographs with each value. Wear was measured with use of the Charnley duoradiographic method, the Livermore method, and the method described by Dorr and Wan, as well as with use of PolyWare and Hip32 software packages, both with and without three-dimensional measurements. Clinical wear was measured from conventional radiographs made prior to revision surgery in fourteen patients and was compared with wear measured directly from the retrieved liners with use of a coordinate measuring machine. With laboratory radiographs, computerized methods of polyethylene wear measurement offered distinctly greater accuracy than did manual methods; however, with clinical radiographs, they offered only slightly better accuracy. Although the increased accuracy of computerized methods may be necessary in research settings, manual methods provided sufficient accuracy for routine clinical assessment of wear. [ABSTRACT FROM AUTHOR]

The article presents the author's comments on the article Blood Metal Ion Thresholds to Identify Patients with Metal-on- Metal Hip Implants at Risk of Adverse Reactions to Metal Debris. An ExternalMulticenter Validation Study of Birmingham Hip Resurfacing and Corail- Pinnacle Implants, published in this issue. She opines on the failure of authors to link the observed ARMD risk factors.

The article focuses on a study related to aspects of wear and damage to the surfaces of a cervical disc replacement. Topics discussed include PEEK-on-ceramic bearings as a reasonable alternative to polyethylene-on- Cobalt-chrome (CoCr) or metal-on-metal bearing for cervical disc replacements, need for clinicians and regulatory agencies to work with independent researchers and academic institutions; and requirements framed by International Organization for Standardization and ASTM.