Retroverting Periacetabular Osteotomy for Symptomatic Acetabular Anteversion.

BACKGROUND: Acetabular dysplasia has traditionally been defined using the lateral center edge angle and treated with periacetabular osteotomy (PAO). However, the recently described Ottawa classification further quantifies dysplasia in 3-dimensional terms, categorizing Ottawa A as dysplasia due to isolated, excessive acetabular anteversion or anterior acetabular under-coverage. We sought to determine if patients who have Ottawa A dysplasia can expect similar outcomes when undergoing a PAO compared to a traditional dysplasia cohort. METHODS: Patients who had undergone PAO with Ottawa A hip dysplasia were selected and compared to a control group of patients who had lateral acetabular undercoverage. The modified Harris Hip Score and International Hip Outcome Tool-33 were collected preoperatively and at various follow-up points for a final follow-up average of 2.3 years (range, 0.9 to 6.2). RESULTS: The 17 patients (21 hips) who had Ottawa A dysplasia were compared to a control cohort of 69 patients (88 hips). Both groups saw significant improvements in modified Harris Hip Score and International Hip Outcome Tool-33 at final follow-up, P < .001. There were no differences between groups in any of the outcome measures or rates of achieving minimal clinically important difference (MCID) or substantial clinical benefit. Rates of MCID ranged from 82.4 to 100%, and rates of achieving substantial clinical benefit ranged from 47.1 to 52.9%. CONCLUSIONS: In patients undergoing a PAO for Ottawa A hip dysplasia, a significant improvement in patient-reported outcomes can be expected with high rates of MCID achievement. This is not significantly different for patients undergoing PAO for more traditional dysplasia parameters.

Prolonged non-weightbearing treatment decreases femoral head deformity compared to symptomatic treatment in the initial stage of Legg-Calvé-Perthes disease.

The purpose of this study is to investigate the potential benefit of using prolonged non-weightbearing (PNWB) as a treatment option for early-stage Legg-Calvé-Perthes disease (LCPD). An Institutional Review Board (IRB) approved this retrospective study of patients with LCPD and ≥2-year follow-up. Patients 6-12 years of age were included if treatment began in Waldenstrom stage 1 or 2A. PNWB consisted of ≥6 months of non- or toe-touch weightbearing. PNWB was recommended if perfusion MRI demonstrated ≥40% hypoperfusion of the femoral head and parents decided against operative treatment. The control group consisted of symptomatically treated patients. Deformity index and epiphyseal quotient were measured at 2-year follow-up. Stulberg classification and sphericity deviation score (SDS) were determined at skeletal maturity or at a minimum of 5-year follow-up. When treatment was initiated in Waldenstrom stage 1, the PNWB group had significantly less femoral head deformity, including deformity index (0.21 vs. 0.52; P < 0.001), epiphyseal quotient (69% vs. 43%; P < 0.001), SDS (18 vs. 52; P = 0.004), and Stulberg (50% good vs. 0% good; P = 0.044). The PNWB group mean hypoperfusion was 68%, indicating severe hypoperfusion. Duration of recommended non-weight bearing in the PNWB group was 11.5 months (range 7-17 months). Despite severe femoral head hypoperfusion, PNWB begun during the initial stage of LCPD decreased femoral head deformity. PNWB should be considered a treatment option for patients/parents who do not wish to pursue operative intervention in early-stage LCPD with substantial hypoperfusion. Level of Evidence III - retrospective comparative study.

Use of transcranial motor-evoked potentials to provide reliable intraoperative neuromonitoring for the Charcot-Marie-Tooth population undergoing spine deformity surgery.

PURPOSE: Intraoperative neuromonitoring (IONM) has historically been difficult to obtain in patients with Charcot-Marie-Tooth (CMT) disease. Transcranial motor-evoked potentials (TcMEPs) have been found to be safe and effective for other spinal deformity patients. Our objective was to determine the effectiveness of TcMEP monitoring in patients with CMT. METHODS: An IRB-approved, retrospective review of CMT patients undergoing spinal deformity surgery assessing TcMEP, somatosensory-evoked potential (SSEP), and neurogenic motor evoked potential (NMEP) IONM was performed. A 2:1 matched cohort control group of idiopathic spinal deformity patients was used. A waveform grading system was applied to review baseline TcMEP reliability and quality, which was validated via intraclass correlation coefficient amongst five raters. RESULTS: Twenty-three CMT patients (26 surgical cases) were identified. The use of TcMEP improved the ability to obtain baseline IONM when compared to SSEP (83% vs. 20%; p < 0.001) and NMEP (83% vs. 18%; p = 0.003). Baseline monitoring was obtained less often for CMT patients using SSEP (20% vs. 100%; p < 0.001) and TcMEP (83% vs. 100%; p = 0.111) compared to idiopathic patients. Sweep length (time from stimulation waveform evaluation) and maximum stimulation voltage were higher in the CMT group (289 ms vs. 111 ms p = 0.007 and 740 V vs. 345 V p = 0.089, respectively). CONCLUSION: TcMEP monitoring significantly improves the ability to provide IONM for CMT patients undergoing spinal deformity surgery. Utilizing longer sweep lengths enhances the ability to attain baseline TcMEP readings, allowing surgeons to more safely proceed with surgery for these complex patients. LEVEL OF EVIDENCE: Therapeutic-Level III.

Acetabular Coverage May Affect Radiographic and Clinical Outcomes of Osteochondral Allograft Transplantation of Focal Femoral Head Lesions: A Case Series From a Single Institution.

Osteochondral lesions of the femoral head in young people are rare and present unique management challenges. Optimal treatment for these lesions is unclear. From 2009 to 2016, clinical and radiographic outcomes were prospectively collected within a series of symptomatic focal osteochondral lesions of the femoral head with a minimum follow-up of 2 years. A surgical hip dislocation followed by implantation of a size-matched fresh osteochondral femoral head allograft was performed. Nine hips in eight patients (6 female patients) underwent surgery at an average of 17 years (11 to 21 years). Individual allograft sizes ranged from 10 to 35 mm in diameter; with 2 of 9 hips receiving two allografts in a stacked or mosaicplasty technique at the time of treatment. The average graft implantation was 3536.5 mm2. Modified Harris hip scores improved by 13.4 (P = 0.018) from preoperative to final follow-up for all patients. Significant improvements in internal rotation (12° versus 23°, P = 0.011), external rotation (32° versus 50°, P = 0.041), and abduction (28° versus 40°, P = 0.042) were also achieved. Three patients (four hips) demonstrated poor radiographic healing (<50% incorporation at 2 years), which correlated with worse clinical outcomes and was associated with a lower preoperative lateral center edge angle (21.5° versus 30.4°, P = 0.049). Fresh osteochondral allograft treatment is a good option for focal osteochondral lesions of the femoral head with improved outcomes and motion; however, higher failure rates may be seen in those with a lower center edge angle.

Reporting Clinical Significance in Hip Arthroscopy: Where Are We Now?

BACKGROUND: Although p values are standard for reporting statistical significance of patient-reported outcome measures (PROMs), the shift toward clinically important outcome values, including minimal clinically important difference (MCID) and substantial clinical benefit (SCB), necessitates re-evaluation of the current literature. QUESTIONS/PURPOSES: We sought to answer two questions regarding studies on primary hip arthroscopy performed for the treatment of femoroacetabular impingement syndrome (FAIS). (1) Do such studies reporting statistical significance on common PROMs meet published MCID/SCB thresholds? (2) What proportion of such studies report both statistical and clinical significance? METHODS: We identified four papers published in two journals defining MCID/SCB values on the modified Harris Hip Score (mHHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sport (HOS-Sport), international Hip Outcome Tool (iHOT-33), and its short version (iHOT-12) for different groups of FAIS patients undergoing hip arthroscopy. We reviewed these two journals from the dates of publication to the present to identify papers reporting changes in post-operative PROMs. The difference in pre- and post-operative scores on each PROM was calculated and compared to MCID/SCB thresholds. RESULTS: Twelve studies were included. Ten studies (83%) evaluated mHHS (90% met MCID, 50% met SCB), seven (58%) evaluated HOS-ADL (100% met MCID/SCB) and HOS-Sport (100% met MCID, 57% met SCB), and one (8%) evaluated iHOT-33 (met MCID/SCB) and iHOT-12 (met MCID). Most studies met MCID and SCB at both 1- and 2-year timepoints. Of the studies evaluated, 50% reported clinical relevance. CONCLUSIONS: Nearly all studies evaluated met MCID, while fewer met SCB. Only half discussed these clinical measures. It is proposed that all future studies report both statistical and clinical significance as standard best practice.

Periacetabular Osteotomy as a Salvage Procedure: Early Outcomes in Patients Treated for Iatrogenic Hip Instability.

BACKGROUND: A periacetabular osteotomy (PAO) can reduce pain and improve quality of life in patients with hip dysplasia. While its utility for patients without traditional radiographic parameters for hip dysplasia has not been previously established, the PAO may help treat patients with hip instability that does not improve following single or multiple hip arthroscopic procedures, or when such procedures lead to hip instability. METHODS: A single-surgeon registry of patients at a single institution was queried to identify patients with a lateral center-edge angle (LCEA) of ≥24° and a Tönnis angle of <10° who underwent PAO because of hip pain and/or instability that failed treatment with hip arthroscopy. Descriptive summary statistics were reported on patient demographics, mean change in LCEA, and patient-reported outcome measures, including the modified Harris hip score (mHHS) and the International Hip Outcome Tool-33 (iHOT-33), at a minimum of 6 months of follow-up. RESULTS: Among 25 patients (mean age, 27.3 ± 6.9 years; 100% women), the mean LCEA increased from 27.2° (range, 24° to 37°) preoperatively to 39.0° ± 5.1° postoperatively (net increase, 11.8° ± 4.5°). Overall, the mean improvement in the mHHS was 11.5 ± 16.9 (preoperative, 59.4 ± 11.6; postoperative, 70.9 ± 20.6) and the mean improvement in the iHOT-33 was 23.8 ± 23.6 (preoperative, 32.2 ± 17.2; postoperative, 56.0 ± 30.0). Eighteen patients (72%) achieved a minimal clinically important improvement in mHHS (mean improvement, 17.4 ± 12.9) and iHOT-33 (mean improvement, 32.4 ± 19.1) scores. In comparison with 7 patients who did not show improvement, the 18 patients who showed improvement had significantly greater mean baseline patient-reported outcome scores. CONCLUSIONS: To our knowledge, these findings provide the first report on outcomes of PAO in patients with hip pain following arthroscopy who do not meet the traditional criteria for acetabular dysplasia. Early benefits in clinical outcomes suggest a novel surgical indication for PAO as a potential salvage option for selected patients; however, longer-term studies are needed. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Frontal Crash Injury Metrics Are Below Mandated Limits for a Spica Casted Child Dummy in Currently Available Restraints.

BACKGROUND: There is a paucity of data defining safe transport protocols for children treated with hip spica casting. Although restraint devices for casted children are available, all federally mandated testing uses a noncasted anthropomorphic test device (ATD or crash dummy). The purpose of this study was to evaluate current restraint options in simulated frontal crash testing using a casted pediatric ATD to determine injury risk to the head, cervical spine, chest, and pelvis. METHODS: Using a 3-year-old ATD, dynamic crash sled tests simulating frontal crash were performed in accordance with government safety standards. The ATD was casted in a double-leg spica and the following restraint devices were tested: a seat designed for spica casted children, a restraint vest-harness, a traditional booster seat, and 2 traditional forward-facing car seats. RESULTS: Although the presence of the cast increased many of the injury metrics measured, all seats passed current federal guidelines for the head and chest. No single seat performed best in all metrics. The greatest magnitude of neck loading and second-highest head injury criterion values were observed for the booster seat. The vest-harness produced the highest head injury criterion and the chest compression exceeded proposed federal limits. CONCLUSIONS: The results suggest safe transport in commercially available seats is possible with the child properly restrained in a correctly fitting seat. However, parents should not assume a child restraint system is appropriate for use just based on fit as, for example, seats with harnesses outperformed an easy to fit booster seat. CLINICAL RELEVANCE: Each child and the position of the child's cast are unique and discharge planning involves consideration of safe transportation. Although this study suggests several seats used to transport spica casted children pass the federal head and chest injury prevention requirements, it is important to recognize that some children may still require emergency vehicle transport.

Discrepancy between true distance of tibial tuberosity advancement and cage size: An ex vivo study.

OBJECTIVE: To determine the discrepancy between true distance of tibial tuberosity advancement (tTTA) and the most commonly used cages. The null hypothesis was that tTTA would be within 1.5 mm difference of the cage size. STUDY DESIGN: Ex vivo study. SAMPLE POPULATION: Eight foam cortical shell specimens modeled from canine tibias. METHODS: Modified tibial tuberosity advancement (TTA) was performed to allow repeated measurement of the tTTA. The Pearson correlation test was used to evaluate the relationships of tTTA and cage sizes (P < .05). The difference between tTTA and cage size was calculated to establish the degree of underadvancement during the TTA. RESULTS: Two hundred forty tTTA measurements were recorded. The tTTA was less than each corresponding cage size (P < .001). Four cage sizes resulted in a difference greater than 1.5 mm (P < .001-.04). The 6-mm cage resulted in median tTTA of 4.3 mm, which did not differ significantly from 4.5 mm (range, 3.2-6.65). The median underadvancement ranged from 1.7 to 2.5 mm for the tested cage sizes. The percentage underadvancement ranged from 21% to 28% for the tested cage sizes. CONCLUSION: The tTTA was less than the corresponding cage sizes by at least 1.5 mm in all except the 6-mm cage. CLINICAL SIGNIFICANCE: Selection of a larger cage size during the TTA may be advantageous to compensate for underadvancement and to minimize the risk of residual cranial tibial translation.

The Flint Lock: A Novel Technique in Total Knee Arthroplasty Closure.

Conventional interrupted sutures are traditionally used in extensor mechanism closure during total knee arthroplasty (TKA). In recent years, barbed suture has been introduced with the proposed benefits of decreased closure time and a watertight seal that is superior to interrupted sutures. Complication rates using barbed sutures and conventional interrupted sutures are similar. We propose a novel closure technique known as the Flint Lock, which is a double continuous interlocking stitch. The Flint Lock provides a quick and efficient closure to the extensor mechanism in TKA. In addition, similar to barbed suture, the Flint Lock should provide a superior watertight seal. It utilizes relatively inexpensive and readily available materials.

Optimizing Hybrid Plate Fixation with a Locked, Oblique End Screw in Osteoporotic Fractures.

BACKGROUND: The end screw in a fracture plate creates the greatest resistance to bending. For osteoporotic fractures treated with plates, there is some question as to the optimal screw insertion technique for the screw farthest from the fracture. A locked, oblique end screw was previously shown to increase resistance to periprosthetic fracture. It is unknown, however, how this end screw configuration would resist pullout when subjected to bending. METHODS: Narrow, low contact 3.5 mm locking compression plates with 6 and 12 holes were anchored to simulated bone material with material properties representing osteoporotic bone. Four configurations were evaluated for the end screw: perpendicular and angulated 30 degrees away from the fracture for both non-locked and locked screws (n=6 per group). The constructs were subjected to 3 point bending until the peak load and finally total construct failure was achieved. RESULTS: Peak force, stiffness, energy to peak load, and the failure mode of each construct were determined. All four 12-hole construct groups failed by gross plastic bending deformation of the plate at the fulcrum past a previously established clinically relevant limit for failure (15°). All 12-hole plate constructs failed at statistically higher loads and energy than any of the 6-hole plate constructs, with the exception of the 6-hole locked, oblique construct. CONCLUSION: The locked, oblique end screw provides equivalent pull out strength for 3.5 mm low contact plates regardless of plate length. Combined with its resistance to periprosthetic fracture, this end screw configuration appears to be the best option for the construct integrity of hybrid plating for osteoporotic fractures. CLINICAL RELEVANCE: Osteoporotic fractures are challenging to treat. The current study and the existing literature show that resistance to both bending loads and refracture at the end of a plate are minimized with a locked screw angled away from the fracture.

Inter- and intra-observer variability of radiography and computed tomography for evaluation of Zurich cementless acetabular cup placement ex vivo.

OBJECTIVE: To evaluate the inter- and intra-observer variability in measurement of the angle of lateral opening (ALO) and version angle measurement using digital radiography and computed tomography (CT). METHODS: Each hemipelvis was implanted with a cementless acetabular cup. Ventrodorsal and mediolateral radiographs were made of each pelvis, followed by CT imaging. After removal of the first cup, the pelves were implanted with an acetabular cup in the contralateral acetabulum and imaging was repeated. Three surgeons measured the ALO and version angles three times for each cup from the mediolateral radiographic projection. The same measurements were made using three-dimensional multiplanar reconstructions from CT images. Two anatomical axes were used to measure pelvic inclination in the sagittal plane, resulting in six measurements per cup. Two-way repeated measures analysis of variance evaluated inter- and intra-observer repeatability for radiographic and CT-based measurements. RESULTS: Version angle based on radiographic measurement did not differ within surgeons (p = 0.433), but differed between surgeons (p <0.001). Radiographic measurement of ALO differed within surgeons (p = 0.006) but not between surgeons (p = 0.989). The ALO and version angle measured on CT images did not differ with or between surgeons. CLINICAL SIGNIFICANCE: Assessment of inter- and intra-observer measurement of ALO and version angle was more reproducible using CT images than conventional mediolateral radiography for a Zurich cementless acetabular cup.

Osteosarcoma: A Meta-Analysis and Review of the Literature.

Over the past 30 years, treatment advances and the addition of neoadjuvant chemotherapy have led to improved 5-year survival in patients with osteosarcoma. More recent literature suggests the overall prognosis remains highly variable, with little improvement since the introduction of neoadjuvant chemotherapy. Tumor necrosis is an important predictor of patient prognosis. Necrosis of more than 90% correlates with overall survival (OS) approaching 75%. We reviewed the history of osteosarcoma treatment and survival and performed a meta-analysis of the 2000-2011 literature. Forty articles were included in the study. Five-year OS was 63% (95% confidence interval, 60%-66%) in studies that included patients with metastatic and nonmetastatic disease and 71% (95% confidence interval, 67%-76%) in studies that included only patients with nonmetastatic disease. Fifty percent of the patients in the studies of those with nonmetastatic osteosarcoma achieved 90% necrosis on histology. Five-year OS and number of patients achieving 90% necrosis are consistent with previous reports. Research is needed to improve treatment regimens and patient outcomes.

Reducing Fracture Risk Adjacent to a Plate With an Angulated Locked End Screw.

OBJECTIVES: Locking screws often are used in the treatment of osteoporotic fractures. Studies show that locking screws can increase bone stresses at the plate end, which increases the possibility of peri-implant fracture. This study evaluates whether the technique used to insert the end screw is related to the fracture tolerance adjacent to the plate. METHODS: Twelve groups of plate constructs were evaluated using a fibular diaphyseal surrogate with mechanical properties similar to osteoporotic bone. All inboard screws were nonlocked with only the end screw fixation differing among groups. The end screws were inserted either perpendicularly to the plate or at an angle of 30 degrees for 6- and 12-hole plates. For both orientations, the end screws were inserted nonlocked, locked, or by a locked overdrilling technique, resulting in 6 groups per plate length. The perpendicular nonlocked screws represented a control group. The constructs were tested to failure in 4-point bending to determine peak load, failure energy, and stiffness. RESULTS: All constructs failed by peri-implant fracture along a plane through the 2 cortical holes of the end screw. Compared with the control group, an angulated locked screw at the plate end significantly increased the peak bending moment and energy required to produce a fracture for both plate lengths (6-hole, P = 0.008, P < 0.001; 12-hole, P = 0.006, P < 0.001). CONCLUSIONS: The use of an angulated locked end screw may enhance the resistance of osteoporotic bone to peri-implant fractures caused by bending forces.

The Safety Tips for ATV Riders (STARs) programme: short-term impact of a school-based educational intervention.

BACKGROUND: Since 1985, one-third of all US all-terrain vehicle (ATV)-related injuries and one-quarter of deaths involved victims <16 years of age. ATV safety education of youth could help reduce these tragedies. OBJECTIVES: To assess the efficacy of the Safety Tips for ATV Riders (STARs) school-based programme targeting adolescents. METHODS: A survey was anonymously administered before and after the programme to determine demographics, knowledge and reported likelihood of using the information learned. RESULTS: Over 4600 students in 30 Iowa schools participated from November 2010 to April 2013. Initially, 52% knew most ATVs are designed for one rider, 25% knew the recommended vehicle size for their age range and 42% knew riding on Iowa's roads was legal only for agricultural purposes. After the programme, this increased to 92%, 82% and 76%, respectively (p<0.0001 in each case), with 61% of students correct on all three. Better preintervention scores were associated with being males, higher riding frequency and being from isolated rural communities. After the programme, 48% and 32% said they were likely/very likely versus unlikely/very unlikely to use the safety information learned, respectively; younger students, females and infrequent riders reported higher likelihoods. CONCLUSIONS: STARs increased short-term ATV safety knowledge and almost half the participants reported they would use the safety information presented. Males and frequent riders seemed more resistant, but some groups that may be more vulnerable to potential ATV crash and injury appeared amenable to the training with higher increases in postprogramme scores and greater intention of improving safety behaviours.

Effect of dorsal acetabular rim loss on stability of the zurich cementless total hip acetabular cup in dogs.

OBJECTIVE: To evaluate magnitude and mode of acute load to failure of the Zurich Cementless acetabular cup prosthesis in cadaveric specimens with and without 50% dorsal acetabular rim loss. STUDY DESIGN: In vitro mechanical study. SAMPLE POPULATION: Cadaveric hemipelves of adult dogs (n = 8). METHODS: Each pair of hemipelves was prepared by dissection of surrounding musculature and implantation of a Zurich Cementless acetabular cup prosthesis. One hemipelvis had the dorsal rim left intact (group 1) and the contralateral hemipelvis had 50% of the dorsal rim excised (group 2). Each hemipelvis underwent acute load to failure with an axial load applied through a prosthetic femoral head. Load at failure was compared between hemipelves with and without dorsal rim loss with a paired t-test; P < .05 was considered significant. RESULTS: Mean failure load was not significantly different between group 1 (3,713 ± 362 N) and group 2 (3,640 ± 751 N; P = .8). Bone fracture (n = 6), ventroversion of the cup (1), and absolute failure unreached at 6,000 N (1) occurred in group 1 and bone fracture (6), ventroversion of cup (1), and cup loosening (1) occurred in group 2. CONCLUSIONS: Zurich Cementless acetabular cup stability does not appear to be compromised by 50% acetabular rim loss at normal physiologic weight bearing loads. Thus, for this system, modifying procedures such as augmentation of the dorsal acetabular rim or deeper reaming for acetabular bed preparation may not be necessary with up to 50% dorsal rim loss with the Zurich Cementless acetabular cup.

Long-term sequelae and management following anterior cruciate ligament injury.

This article discusses a case in which a patient who sustained an anterior cruciate ligament (ACL) injury returned with anterior knee pain in the same knee approximately 20 years later. He underwent reconstruction at the time of the injury and had a revision reconstruction performed 10 years later. The case highlights the long-term consequences of ACL injury and subsequent reconstruction for the knee joint, as this patient has developed anterior knee pain during his mid-40s. Additionally, non-operative management of knee osteoarthritis is discussed.

A school-based study of adolescent all-terrain vehicle exposure, safety behaviors, and crash experience.

PURPOSE: More youth are killed every year in the United States in all-terrain vehicle (ATV) crashes than on bicycles, and since 2001, one-fifth of all ATV fatalities have involved victims aged 15 years or younger. Effectively preventing pediatric ATV-related deaths and injuries requires knowledge about youth riding practices. Our objective was to examine ATV use, crash prevalence, and riding behaviors among adolescent students in a rural state. METHODS: We administered a cross-sectional survey to 4,684 youths aged 11 to 16 years at 30 schools across Iowa from November 2010 to April 2013. Descriptive and comparative analyses were performed. RESULTS: Regardless of rurality, at least 75% of students reported having been on an ATV, with 38% of those riding daily or weekly. Among ATV riders, 57% had been in a crash. Most riders engaged in risky behaviors, including riding with passengers (92%), on public roads (81%), or without a helmet (64%). Almost 60% reported engaging in all 3 behaviors; only 2% engaged in none. Multivariable modeling revealed male youth, students riding daily/weekly, and those reporting both riding on public roads and with passengers were 1.61 (95% CI, 1.36-1.91), 3.73 (95% CI, 3.10-4.50), and 3.24 (95% CI, 2.09-5.04) times more likely to report a crash, respectively. CONCLUSIONS: Three-fourths of youths surveyed were exposed to ATVs. The majority of riders had engaged in unsafe behaviors and experienced a crash. Given this widespread use and the potentially considerable morbidity of pediatric ATV crashes, prevention efforts, including anticipatory guidance by primary care clinicians serving families at risk, should be a higher priority.

Mechanical evaluation of adjunctive fixation for prevention of periprosthetic femur fracture with the Zurich cementless total hip prosthesis.

OBJECTIVE: To evaluate whether cerclage wire or a lateral plate increases the peak-torque load to failure, compared to femora without adjunctive fixation, in femora implanted with Zurich Cementless stems. STUDY DESIGN: In vitro biomechanical study. SAMPLE POPULATION: Paired femora from adult dogs (n = 24) weighing 28-35 kg. METHODS: Pairs of femora were implanted with a stem and randomly assigned to 2 treatment groups: cerclage or plate. Within each pair, either 3 loop cerclage wires or a laterally applied 12-hole Advanced Locking Plate System 10-mm plate (ALPS 10) were implanted in a femur, whereas the contralateral femur acted as control with no adjunctive fixation. After application of a static axial load each specimen was loaded to failure in torsion. Peak torque load at failure was compared between femora with each adjunctive fixation and the control using a paired t-test; P < .05 was considered significant. RESULTS: In both treatment groups, femora with adjunctive fixation failed at higher loads compared to the femora without fixation; however, significant difference in peak torque at failure between treated femora and control was found only in the plated group (P < .05). Femora implanted with plates and with cerclage were 13.9% and 7.2% stronger in torsion than the femora without fixation, respectively. CONCLUSIONS: Adjunctive fixation with a laterally applied ALPS 10 may aid in the prevention of peri-prosthetic fractures associated with Zurich Cementless medium stems.