Taper Material Loss in Total Hip Replacements: Is It Affected by Joint Friction?

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.

The lexicon for periprosthetic bone loss versus osteolysis after cervical disc arthroplasty: a systematic review.

BACKGROUND: Periprosthetic bone loss is a common observation following arthroplasty. Recognizing and understanding the nature of bone loss is vital as it determines the subsequent performance of the device and the overall outcome. Despite its significance, the term "bone loss" is often misused to describe inflammatory osteolysis, a complication with vastly different clinical outcomes and treatment plans. Therefore, the goal of this review was to report major findings related to vertebral radiographic bone changes around cervical disc replacements, mitigate discrepancies in clinical reports by introducing uniform terminology to the field, and establish a precedence that can be used to identify the important nuances between these distinct complications. METHODS: A systematic review of the literature was conducted following PRISMA guidelines, using the keywords "cervical," "disc replacement," "osteolysis," "bone loss," "radiograph," and "complications." A total of 23 articles met the inclusion criteria with the majority being retrospective or case reports. RESULTS: Fourteen studies reported periprosthetic osteolysis in a total of 46 patients with onset ranging from 15-96 months after the index procedure. Reported causes included: metal hypersensitivity, infection, mechanical failure, and wear debris. Osteolysis was generally progressive and led to reoperation. Nine articles reported non-inflammatory bone loss in 527 patients (52.5%), typically within 3-6 months following implantation. The reported causes included: micromotion, stress shielding, and interrupted blood supply. With one exception, bone loss was reported to be non-progressive and had no effect on clinical outcome measures. CONCLUSIONS: Non-progressive, early onset bone loss is a common finding after CDA and typically does not affect the reported short-term pain scores or lead to early revision. By contrast, osteolysis was less common, presenting more than a year post-operative and often accompanied by additional complications, leading to revision surgery. A greater understanding of the clinical significance is limited by the lack of long-term studies, inconsistent terminology, and infrequent use of histology and explant analyses. Uniform reporting and adoption of consistent terminology can mitigate some of these limitations. Executing these actionable items is critical to assess device performance and the risk of revision. LEVEL OF EVIDENCE IV: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Objective analysis of intermediate-term outcome of the Ponseti technique: a review of the experience from Los Angeles.

The Ponseti method of manipulative treatment for clubfoot deformity became widely adopted by pediatric orthopaedic surgeons beginning in the mid-1990s. The technique allows correction of most idiopathic clubfeet using gentle manipulation and cast application. The treatment represents a marked advance over past efforts to gain correction of the foot through extensive release surgery. In 2006, we began a Clubfoot Clinic at the Orthopaedic Institute for Children in Los Angeles, California dedicated to managing clubfoot patients using Ponseti's method. An IRB-approved database of patient-related, treatment related, and demographic variables was assembled and used to ascertain the outcome of treatment as well as to address parental questions regarding certain aspects of treatment. Here, we present a review of our body of work, which has improved clinical decision making as well as our ability to better inform our patients' parents regarding the treatment and prognosis of the Ponseti method. Studies from our institution showed that while relapses and the need for extra-articular tibialis anterior tendon transfer (TATT) surgery remain common to the Ponseti method, these events do not adversely affect overall patient function or satisfaction. These findings were not unlike those of classic studies reported from Ponseti's institution. We conclude that the Ponseti method is not only a technique to achieve initial correction of an idiopathic clubfoot, but also how to manage relapses that will inevitably occur in many patients. While relapses and tendon transfer surgery are likely to remain common with this treatment method, these events do not adversely affect overall patient function or satisfaction. The parents of infants whose clubfeet are managed using the Ponseti method should be counselled accordingly.

Does generalized joint hypermobility influence the Ponseti treatment of clubfoot patients?

Previous investigators have suggested a role for generalized joint hypermobility (GJH) in the etiology of clubfoot deformity, while others have suggested its presence may influence treatment outcomes. We sought to determine if GJH was associated with the demographics, treatment, or propensity to relapse of patients whose clubfeet were managed using the Ponseti method. Fifty-seven patients with Ponseti-treated clubfeet comprised the cohort; median age 61 months (range, 38-111 months). A physical therapist evaluated each patient using the nine-point Beighton scale to quantify hypermobility. The scores were then correlated with patient sex, laterality, Dimeglio severity score, treatment, relapse, and surgery. The median Beighton score was 5; 49 of 57 patients (86%) had Beighton scores ≥4. All feet were plantigrade without symptomatic overcorrection at the time of evaluation. Although there was a slightly lower probability of relapse in patients with higher Beighton scores, this was not statistically significant (P = 0.10). Accordingly, the sex, laterality, initial severity, number of pretenotomy casts, need for tenotomy, relapse, and need for tendon transfer surgery were not significantly influenced by the Beighton score. The outcome of Ponseti clubfoot treatment is not altered by the presence of GJH in young children. Joint hypermobility does not appear to influence the likelihood of relapse or surgery. Unlike clubfeet reportedly treated with release surgery, Ponseti-treated clubfeet were not prone to excessive overcorrection regardless of joint laxity. Last, the distribution of Beighton scores in the study's cohort supports an association between GJH and clubfoot deformity.

Quantification of Ankle Dorsiflexion in Ponseti-managed Unilateral Clubfoot Patients During Early Childhood.

BACKGROUND: Following the initial correction of a clubfoot using the Ponseti method, diminished passive ankle dorsiflexion may be observed over time, which could represent a possible relapsed deformity. Alternatively, the change may be attributable to patient age or other variables. Our purpose was to quantify passive ankle dorsiflexion in the involved and contralateral unaffected limbs of Ponseti-managed unilateral clubfoot patients, and to determine what patient-related variables influence this finding. METHODS: In total, 132 unilateral clubfoot patients were studied. Passive ankle dorsiflexion was measured in both limbs at each visit. Data were excluded from visits in which patients showed clear evidence of a relapse. Mean ankle dorsiflexion for clubfeet and contralateral unaffected limbs were reported for annual age intervals and compared using paired t tests. A general linear model was established to assess the effects of age, severity, sex, and side on ankle dorsiflexion. RESULTS: Mean ankle dorsiflexion for unaffected limbs declined with age, measuring 53±6 degrees between 0 and 1 year of age and decreasing to 39±7 degrees by 4 to 5 years of age. Similarly, mean ankle dorsiflexion in treated clubfeet declined with age, measuring 44±7 degrees between 0 and 1 year and 29±7 degrees between 4 and 5 years. Overall, the difference between limbs in these patients averaged ~10 degrees for every age interval through 9 years (P<0.001). Ankle dorsiflexion of clubfeet in 95% of patients aged 0 to 2 years was at least 20 degrees, and in 95% of patients aged 3 to 5 years this was at least 15 degrees. Patient age (P<0.001) and severity of deformity (P<0.001) were found to be the only significant factors affecting ankle dorsiflexion in the affected limbs. CONCLUSIONS: Ankle dorsiflexion in the Ponseti-treated clubfeet was influenced by age of the patient and the initial severity of the affected limb. Furthermore, our data suggest that, in patients who showed no relapse, a minimum of 20 degrees of ankle dorsiflexion in the corrected clubfoot is maintained through age 3 years and a minimum of 15 degrees is maintained through age 5 years. LEVEL OF EVIDENCE: Level IV-this is a retrospective case series.

Preclinical biomechanical testing models for the tibiotalar joint and its replacements: A systematic review.

In recent years, total ankle replacements have gained increasing popularity as an alternative to fusion. Preclinical testing of TARs requires reliable in vitro models which, in turn, need thorough knowledge of the kinematics of the tibiotalar joint. Surprisingly few studies have been published to simulate the in vivo kinematics of the tibiotalar joint. Among these studies, there is a wide range of methods and magnitudes of applied loads. The purpose of the present review was to summarize the applied loads, positions that were tested during static simulations, and ranges of motion simulated that have been used in human cadaveric models of the tibiotalar joint. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, PubMed and Google Scholar were searched for studies pertaining to cadaveric tibiotalar joint kinematics. Our search yielded 12 appropriate articles that were included in the systematic review. While it is well known that loads at the tibiotalar joint are frequently as high as 5 times bodyweight [1], these studies reported applied loads varying from 200N-750N, below average bodyweight. Three studies used dynamic loading of custom apparatuses to drive cadaver limbs along predetermined paths to simulate gait. Conversely, the other nine studies applied static loads (∼300N), performed at discreet points during the stance phase, considerably lower than physiological conditions. The present systematic review calls for an urgent need to establish a consensus for preclinical evaluation of TARs for biomechanical function.

Relapse Rates in Patients with Clubfoot Treated Using the Ponseti Method Increase with Time: A Systematic Review.

BACKGROUND: The Ponseti method is the preferred technique to manage idiopathic clubfoot deformity; however, there is no consensus on the expected relapse rate or the percentage of patients who will ultimately require a corrective surgical procedure. The objective of the present systematic review was to determine how reported rates of relapsed deformity and rates of a secondary surgical procedure are influenced by each study's length of follow-up. METHODS: A comprehensive literature search using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed to identify relevant articles. The definition of relapse, the percentage of patients who relapsed, the percentage of feet that required a surgical procedure, and the mean duration of follow-up of each study were extracted. Pearson correlations were performed to determine associations among the following variables: mean follow-up duration, percentage of patients who relapsed, percentage of feet that required a joint-sparing surgical procedure, and percentage of feet that required a joint-invasive surgical procedure. Logarithmic curve fit regressions were used to model the relapse rate, the rate of joint-sparing surgical procedures, and the rate of joint-invasive surgical procedures as a function of follow-up time. RESULTS: Forty-six studies met the inclusion criteria. Four distinct definitions of relapse were identified. The reported relapse rates varied from 3.7% to 67.3% of patients. The mean duration of follow-up was strongly correlated with the relapse rate (Pearson correlation coefficient = 0.44; p < 0.01) and the percentage of feet that required a joint-sparing surgical procedure (Pearson correlation coefficient = 0.59; p < 0.01). Studies with longer follow-up showed significantly larger percentages of relapse and joint-sparing surgical procedures than studies with shorter follow-up (p < 0.05). CONCLUSIONS: Relapses have been reported to occur at as late as 10 years of age; however, very few studies follow patients for at least 8 years. Notwithstanding that, the results indicated that the rate of relapse and percentage of feet requiring a joint-sparing surgical procedure increased as the duration of follow-up increased. Longer-term follow-up studies are required to accurately predict the ultimate risk of relapsed deformity. Patients and their parents should be aware of the possibility of relapse during middle and late childhood, and, thus, follow-up of these patients until skeletal maturity may be warranted. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical comparison of fixation stability using a Lisfranc plate versus transarticular screws.

BACKGROUND: To obtain adequate fixation in treating Lisfranc soft tissue injuries, the joint is commonly stabilized using multiple transarticular screws; however iatrogenic injury is a concern. Alternatively, two parallel, longitudinally placed plates, can be used to stabilize the 1st and 2nd tarsometatarsal joints; however this may not provide adequate stability along the Lisfranc ligament. Several biomechanical studies have compared earlier methods of fixation using plates to the standard transarticular screw fixation method, highlighting the potential issue of transverse stability using plates. A novel dorsal plate is introduced, intended to provide transverse and longitudinal stability, without injury to the articular cartilage. METHODS: A biomechanical cadaver model was developed to compare the fixation stability of a novel Lisfranc plate to that of traditional fixation, using transarticular screws. Thirteen pairs of cadaveric specimens were tested intact, after a simulated Lisfranc injury, and then following implant fixation, using one method of fixation randomly assigned, on either side of each pair. Optical motion tracking was used to measure the motion between each of the following four bones: 1st metatarsal, 2nd metatarsal, 1st cuneiform, and 2nd cuneiform. Testing included both cyclic abduction loading and cyclic axial loading. RESULTS: Both the Lisfranc plate and screw fixation method provided stability such that the average 3D motions across the Lisfranc joint (between 2nd metatarsal and 1st cuneiform), were between 0.2 and 0.4mm under cyclic abduction loading, and between 0.4 and 0.5mm under cyclic axial loading. Comparing the stability of fixation between the Lisfranc plate and the screws, the differences in motion were all 0.3mm or lower, with no clinically significant differences (p>0.16). CONCLUSIONS: Diastasis at the Lisfranc joint following fixation with a novel plate or transarticular screw fixation were comparable. Therefore, the Lisfranc plate may provide adequate support without risk of iatrogenic injury to the articular cartilage.

Sixty Years On: Ponseti Method for Clubfoot Treatment Produces High Satisfaction Despite Inherent Tendency to Relapse.

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.

How Many Patients Who Have a Clubfoot Treated Using the Ponseti Method are Likely to Undergo a Tendon Transfer?

BACKGROUND: The Ponseti method has become the standard of care for the treatment of idiopathic clubfoot. A commonly reported problem encountered with this technique is a relapsed deformity that is sometimes treated in patients older than 2.5 years by an anterior tibial tendon transfer (ATTT) to the third cuneiform. Presently, there is insufficient information to properly counsel families whose infants are beginning Ponseti treatment on the probability of needing later tendon transfer surgery. METHODS: All idiopathic clubfoot patients seen at the authors' institution during the study period who met the inclusion criteria and who were followed for >2.5 years were included (N=137 patients). Kaplan-Meier Survival analysis was used to determine the probability of survival without the need for ATTT surgery. In addition, the influence of patient characteristics, socioeconomic variables, and treatment variables on need for surgery was calculated. RESULTS: On the basis of the survivorship analysis, the probability of undergoing an ATTT remained below 5% for all patients at 3 years of age, but exceeded 15% by 4 years of age, increasing steadily afterwards such that by 6 years of age, the probability of undergoing an ATTT reached 29% of all patients. Overall, controlling for all other variables in the analysis, parent-reported adherence with bracing reduced the odds of undergoing surgery by 6.88 times, compared with parent-reported nonadherence (P<0.01). CONCLUSIONS: This is the first study to report the probability of undergoing ATTT surgery as a function of age using survivorship analysis following Ponseti clubfoot treatment. Although the overall probability reached 29% at 6 years, this was significantly reduced by compliance with bracing. This information may be useful to the clinician when counseling families at the start of treatment. LEVEL OF EVIDENCE: Level III-theraputic.

Opioid Prescription and Usage in Adolescents Undergoing Orthopaedic Surgery in the United States: A Systematic Review.

BACKGROUND: The proper use of opioid analgesia for postoperative pain management is controversial. While opioids are considered the standard of care for multimodal postoperative pain modulation in the United States, there is a lack of established protocols for prescribing opioids in adolescents undergoing outpatient orthopaedic surgery. The objective of this review was to identify and report on current literature on opioid prescription for pain management in adolescents undergoing all procedures, as well as in adults undergoing outpatient orthopaedic surgery. METHODS: A comprehensive literature search using PRISMA guidelines was performed to identify all articles relevant to opioid use in adolescents for postoperative pain and in adults following outpatient orthopaedic procedures. RESULTS: A total of 4,446 results were identified from databases and relevant journal web sites. Of these, 9 articles were selected that fit the criteria for review. Five studies discussed the dosage and type of opioids prescribed in adolescent populations, and 4 quantified patient self-administration in adult populations. CONCLUSIONS: Adolescent opioid pain management following outpatient orthopaedic surgery is not documented. Current recommendations for opioid prescription in adolescents lack support and are primarily based on adult dosages. Adult studies suggest that opioid medications may be overprescribed following outpatient orthopaedic surgery. These results clearly indicate that there is a pressing need for quantitative research on pain management following outpatient orthopaedic surgery in the adolescent population in the United States. CLINICAL RELEVANCE: There appear to be no studies on self-administered opioid pain medication following orthopaedic surgery in an adolescent population, suggesting that there is no objective basis for the current prescription recommendations.

Periprosthetic femoral bone loss in total hip arthroplasty: systematic analysis of the effect of stem design.

INTRODUCTION: Periprosthetic bone loss may lead to major complications in total hip arthroplasty (THA), including loosening, migration, and even fracture. This study analysed the influence of femoral implant designs on periprosthetic bone mineral density (BMD) after THA. METHODS: The results of all previous published studies reporting periprosthetic femoral BMD following THA were compiled. Using these results, we compared percent changes in bone loss as a function of: femoral stem fixation, material, and geometry. RESULTS: The greatest bone loss was in the calcar region (Gruen Zone 7). Overall, cemented stems had more bone loss distally than noncemented stems, while noncemented stems had more proximal bone loss than cemented stems. Within noncemented stems, cobalt-chromium (CoCr) stems had nearly double the proximal bone loss compared to titanium (Ti) alloy stems. Finally, within noncemented titanium alloy group, straight stems had less bone loss than anatomical, tapered, and press-fit designs. DISCUSSION: The findings from the present study quantified percent changes in periprosthetic BMD as a function of fixation method, alloy, and stem design. While no one stem type was identified as ideal, we now have a clearer understanding of the influence of stem design on load transfer to the surrounding bone.

Strength of Thoracic Spine Under Simulated Direct Vertebral Rotation: A Biomechanical Study.

BACKGROUND: Direct vertebral rotation (DVR) has gained increasing popularity for deformity correction surgery. Despite large moments applied intraoperatively during deformity correction and failure reports including screw plow, aortic abutment, and pedicle fracture, to our knowledge, the strength of thoracic spines has been unknown. Moreover, the rotational response of thoracic spines under such large torques has been unknown. PURPOSE: Simulate DVR surgical conditions to measure torsion to failure on thoracic spines and assess surgical forces. STUDY DESIGN: Biomechanical simulation using cadaver spines. METHODS: Fresh-frozen thoracic spines (n = 11) were evaluated using radiographs, magnetic resonance imaging (MRI) and dual-energy x-ray absorptiometry. An apparatus simulating DVR was attached to pedicle screws at T7-T10 and transmitted torsion to the spine. T11-T12 were potted and rigidly attached to the frame. Strain gages measured the simulated surgical forces to rotate spines. Torsional load was increased incrementally till failure at T10-T11. Torsion to failure at T10-T11 and corresponding forces were obtained. RESULTS: The T10-T11 moment at failure was 33.3 ± 12.1 Nm (range = 13.7-54.7 Nm). The mean applied force to produce failure was 151.7 ± 33.1 N (range = 109.6-202.7 N), at a distance of approximately 22 cm where surgeons would typically apply direct vertebral rotation forces. Mean right rotation at T10-T11 was 11.6°±5.6°. The failure moment was significantly correlated with bone mineral density (Pearson coefficient 0.61, p = .047). Failure moment also positively correlated with radiographic degeneration grade (Spearman rho > 0.662, p < .04) and MRI degeneration grade (Spearman rho = 0.742, p = .01). CONCLUSION: The present study indicated that with the advantage of lever arms provided with DVR techniques, relatively small surgical forces, <200 N, can produce large moments that cause irreversible injury. Although further studies are required to establish the safety of surgical deformity correction surgeries, the present study provides a first step in the quantification of thoracic spine strength.

Distal fibula fracture fixation: Biomechanical evaluation of three different fixation implants.

BACKGROUND: The goal of this study was to evaluate the biomechanical performance of three distal fibula fracture fixation implants in a matched pair cadaveric fibula model: (1) a 5-hole compression plate with lag screw, (2) a 5-hole locking plate with lag screw, and (3) the 6-hole tabbed-plate with locking screws. METHODS: Three-dimensional motions between the proximal and distal fibular segments were measured under cyclic valgus bending, cyclic compressive axial loading, and cyclic torsional external-rotation loading. During loading, strains were measured on the surfaces of each fibula near the simulated fracture site, and on the plate, to assess load transfer. Bone quality was quantified globally for each donor using bone mineral density (BMD) measured using Dual X-ray absorptiometry (DEXA) and locally at the fracture site using bone mineral content (BMC) measured using peripheral quantitative computed tomography (pQCT). RESULTS: Mean failure loads were below 0.2Nm of valgus bending and below 4Nm of external-rotational torque. Mean failure angulation was below 1degree for valgus bending, and failure rotation was below 7degrees for external-rotation. In the compression plate group, significant correlations were observed between bone quality (global BMD and local BMC) and strain in every one of the five locations (Pearson correlation coefficients >0.95, p<0.05). In contrast, in the locking and tabbed-plate groups, BMD and BMC correlated with far fewer strain locations. CONCLUSIONS: Overall, the tabbed-plate had similar construct stability and strength to the compression and locking plates. However, the distribution of load with the locking and tabbed-plates was not as heavily dependent on bone quality.

The Objective Measurement of Brace-Use Adherence in the Treatment of Idiopathic Clubfoot.

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.

Can wear explain the histological variation around metal-on-metal total hips?

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.

Effect of proximal femoral bone support on the fixation of a press-fit noncemented total hip replacement femoral component.

PURPOSE: Proximal femoral bone loss is a common challenge in revision hip arthroplasty. In this study, in-vitro fixation of a non-cemented, rectangular, dual-tapered, press-fit femoral component designed to achieve metadiaphyseal fixation was analyzed using an accelerated proximal femoral bone loss model to assess the potential use in revision cases. METHODS: The press-fit AlloclassicTM femoral stem was implanted in ten cadaveric femurs and tested under cyclic biomechanical loading in an intact state, and then again after sequential proximal femoral bone resections, simulating increasing amounts of bone deficiency. Anterior-posterior and medial-lateral interface motions were measured at the distal stem tip throughout loading. 
 RESULTS: Three specimens remained stable throughout testing, with initial and peak per-cycle motions of less than 50 µm. Six specimens were destabilized under loading with higher per-cycle motions, specifically at the distal stem tip during peak loading in the anterior-posterior direction, with motions of 78±69 µm, compared to 12±9 µm in the stable specimens (P<.05). Total migration of the destabilized specimens was also significantly higher, specifically at the proximal stem tip in the medial-lateral direction, with migrations of 101±34 µm (P<.05) and at the distal stem tip in the anterior-posterior direction, with migrations of 155±179 µm (P<.05), compared to 33±12 µm and 13±11 µm for the stable specimens. CONCLUSION: The results indicate that when strong initial fixation is achieved, long-term success is possible given substantial proximal femoral bone loss.

The current management of idiopathic clubfoot revisited: results of a survey of the POSNA membership.

BACKGROUND: In 2001, the members of the Pediatric Orthopaedic Society of North America (POSNA) were surveyed regarding their approach to treating idiopathic clubfoot deformity. Since that time, several studies have advocated a change in the approach to treating this deformity, moving away from surgical release and toward less invasive methods. The purpose of this study was to assess the recent approach to treating clubfoot among the POSNA membership. METHODS: A survey was emailed to all POSNA members to define their current treatment of idiopathic clubfoot deformity. RESULTS: We received 323 responses. Ninety-three percent of participants were fellowship trained and were in practice for an average of 17.2 years. On an average, physicians reported each treating 23.5 new clubfoot patients during the year of survey. Nearly all (96.7%) of those surveyed stated that they use the Ponseti treatment method. The average time to initial correction was estimated at 7.1 weeks. Eighty-one percent of patients were estimated to require a tenotomy; 52.7% were performed under general anesthesia or conscious sedation, whereas 39.4% were done under local. Those surveyed estimated that 22% of clubfeet relapsed and 7% required a comprehensive release. Seventy-five percent of the respondents stated that their current treatment approach differed from how they were trained, and 82.7% were trained in the Ponseti method in the last few years. CONCLUSIONS: Our study provides convincing evidence that a large majority of pediatric orthopaedic surgeons now prefer the Ponseti method to treat idiopathic clubfoot and indicates that the move away from extensive release surgery occurred during the past decade. LEVEL OF EVIDENCE: Not applicable.

Resident selection: how we are doing and why?

Selection of the best applicants for orthopaedic residency programs remains a difficult problem. Most quantifiable factors for residency selection evaluate test-taking ability and grades rather than other aspects, such as patient care, professionalism, moral reasoning, and integrity. Four current department members on our resident selection committee ranked four consecutive classes of orthopaedic residents interviewed for residency. We ranked incoming residents in order of best to least qualified and compared those rankings with rank lists by the same faculty on completion of residency. Rankings also were compared with the residents' United States Medical Licensing Examination (USMLE) Part I scores, American Board of Orthopaedic Surgery (ABOS) Part I scores, and fourth-year Orthopaedic-in-Training Examination (OITE) scores. We found fair or poor correlations between the residents' initial rankings, rankings on graduation, and their USMLE, ABOS, and OITE scores. The only relatively strong correlation found was between the OITE and ABOS scores. Despite the faculty's consensus regarding selection criteria, interviewers did not agree in their rankings of residents on graduation. Additional work is necessary to refine the inexact yet important science of selecting residency applicants.