Unicortical Fixation is Sufficient for Surgical Treatment of Tibial Tubercle Avulsion Fractures in Children.

BACKGROUND: Although open reduction and internal fixation are recommended for displaced tibial tubercle avulsion fractures in young athletes, whether to use unicortical or bicortical fixation is debatable. The purpose of this study is to compare the outcomes of unicortical versus bicortical fixation in a series of pediatric tibial tubercle avulsion fractures. METHODS: We reviewed a consecutive series of patients with tibial tubercle fractures treated surgically at 2 level-1 pediatric tertiary care centers over a 12.5-year period. Patients aged below 18 years of age who received surgical treatment for displaced tibial tubercle fractures with postoperative follow-up were included. Fractures were classified using a modified Ogden classification system. The relative proportion of fracture types treated and incidence of complications were compared. RESULTS: The cohort included 90 fractures in 86 patients. There were 82 male and 4 female individuals; average age was 14.7 years (range, 9.0 to 18 y). In total, 87 of 90 were treated with open reduction and internal screw fixation [51 unicortical (59%), 13 mixed (15%), 23 bicortical (26%)] and 3 with percutaneous pinning. All patients were followed-up until healing and postoperative follow-up average was 8 months (range, 3 to 34 mo). There were no significant differences between the 2 groups with regard to patient age (P=0.22), patient weight (P=0.22), and activity clearance times [unicortical: 19.9 wk (range, 10.4 to 42.3 wk); bicortical: 17.7 wk (range, 12.1 to 32 wk); P=0.19]. The mixed cortical group was cleared at an average of 19.9 weeks (range, 10.6 to 29.1 wk). The relative proportion of fracture patterns treated differed negligibly between the unicortical and bicortical groups. Complications were noted in 9 of 90 procedures (10% rate); all subjects showed evidence of full radiographic healing at last follow-up. CONCLUSIONS: There was no difference in outcome whether unicortical or bicortical fixation was used. All patients exhibited full healing and return to activities with very low-complication rates. The results of this study suggest the adequacy of unicortical fixation for treating tibial tubercle fractures in young athletes. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Surgeon Survey Shows No Adverse Events With MRI in Patients With Magnetically Controlled Growing Rods (MCGRs).

STUDY DESIGN: Surgeon survey. OBJECTIVES: To determine if magnetic resonance imaging (MRI) following implantation of magnetically controlled growing rods (MCGRs) is associated with any adverse events. SUMMARY OF BACKGROUND DATA: Magnetically controlled growing rods have been shown to reduce the need for repeated surgical procedures and improve costs when compared to traditional growing rods, but concerns about MRI compatibility exist. MRIs are often clinically indicated in the EOS population. METHODS: Pediatric spine surgeons who are members of the Growing Spine Study Group, Children's Spine Study Group, and early international users of this technology were surveyed regarding MRI use after performing MCGR surgery. RESULTS: A total of 118 surgeons were surveyed. Four surgeons reported that 10 patients had an MRI with an implanted MCGR. Loss of fixation (0%, 0/10), movement of implants (0%, 0/10), unintended lengthening/shortening (0%, 0/10), or noticeable heating of MCGR (0%, 0/10) were not observed. No problems were observed with function of the MCGR following MRI, and a mean of 2.1 mm was obtained at the next lengthening (range, 0.5-3.0 mm). Two patients had brain MRIs, both of which could be interpreted. All cervical spine MRIs could be interpreted without excessive artifact (100%, 7/7). Six patients had MRIs of the thoracic or lumbar spine, but these were considered uninterpretable as a result of artifact from the MCGR device (0%, 0/6). CONCLUSION: These are the first reported cases of MRI use in humans with MCGR. There were no adverse events observed. MCGR rods lengthened as expected following MRI. MRIs of the brain and cervical spine were able to be interpreted, but MRIs of the thoracolumbar spine could not be interpreted because of MCGR artifact. MRIs can be safely performed in patients with MCGRs; however, MRIs of thoracic and thoracolumbar spine may be of limited clinical benefit because of artifact. LEVEL OF EVIDENCE: Level IV, case series.

Does the Type of Metal Instrumentation Affect the Risk of Surgical Site Infection in Pediatric Scoliosis Surgery?

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To determine the association of implant metal composition with the risk of surgical site infection (SSI) following pediatric spine surgery. SUMMARY OF BACKGROUND DATA: SSI is a well-described complication following pediatric spine surgery. Many risk factors have been identified in the literature, but controversy remains regarding metal composition as a risk factor. METHODS: This was a retrospective study of patients who underwent posterior spinal instrumentation procedures between January 1, 2006, and December 31, 2008, at three large children's hospitals for any etiology of scoliosis and had at least 1 year of postoperative follow-up. Procedures included posterior spinal fusion, growth-friendly instrumentation, and revision of spinal instrumentation. The Centers for Disease Control and Prevention definition of SSI was used. A chi-squared test was performed to determine the relationship between type of metal instrumentation and development of an SSI. RESULTS: The study included 874 patients who underwent 1,156 total procedures. Overall, 752 (65%) procedures used stainless steel instrumentation, 238 (21%) procedures used titanium instrumentation, and the remaining 166 (14%) procedures used cobalt chrome and titanium hybrid instrumentation. The overall risk of infection was 6.1% (70/1,156) per procedure, with 5.9% (44/752) for stainless steel, 6.7% (12/238) for titanium, and 6.0% (10/166) for cobalt chrome. The multiple regression analysis found no significant differences in the metal type used between patients with and without infection (p = .886) adjusting for etiology, instrumentation to pelvis, and type of procedures. When stratified based on etiology, the multiple regression analyses also found no significant difference in SSI between two metal type groups. CONCLUSIONS: This study found no difference in risk of infection with stainless steel, titanium, or cobalt chrome/titanium instrumentation and is adequately powered to detect a true difference in risk of SSI. LEVEL OF EVIDENCE: Level II, prognostic.

Can Subclinical Rickets Cause SCFE? A Prospective, Pilot Study.

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is a common disorder of the growing hip; however, its etiology remains unknown. Vitamin D (25-OH) is a major regulator of bone homeostasis and calcium metabolism. Vitamin D deficiency is one of the major causes of rickets, and rickets has been associated with SCFE. Increased body mass index (BMI) has been linked to SCFE and obese children are known to have lower vitamin D levels. Therefore, we hypothesize that children who develop SCFE may have subclinical rickets predisposing them to the development of physeal disease. METHODS: This was a pilot, prospective study designed to determine the relationship between vitamin D, bone, muscle, and fat in patients with SCFE. We enrolled 20 consecutive patients with idiopathic SCFE aged 9 to 14 years. Upon diagnosis, vitamin D, PTH, T4, and thyroid-stimulating hormone blood levels were obtained. A single-slice computed tomography was used to measure cortical bone density (CBD) of the femur. Demographics, BMI, and the results obtained were compared to generate a relationship between vitamin D levels and SCFE. RESULTS: Twenty patients were enrolled, 13 males and 7 females, at an average age of 12 years (range, 9 to 14 y), and mean BMI% was 93.9 (range, 81.3 to 99.5). There were 15 stable and 5 unstable SCFE. Overall, mean and SD values for vitamin D, 25-OH were within the normal range (43.9 ± 13.5). We found no difference in values in vitamin D between nonobese (BMI < 95%) and obese (BMI ≥ 95%) subjects (34.8 ± 16.8 vs. 51.6 ± 22.4, P = 0.144). Moreover, we found no difference in CBD between these 2 groups (1126 ± 33.1 vs. 1147 ± 41.2, P = 0.333). There was no relation between blood values of vitamin D and measures of CBD. CONCLUSIONS: Although obese children are known to have lower levels of vitamin D and a higher prevalence of SCFE, we found no correlation between low vitamin D and the development of SCFE in this subset of patients.

Cobalt Chrome Spinal Constructs Trigger Airport Security Screening in 24% of Pediatric Patients.

STUDY DESIGN: Retrospective study. OBJECTIVES: To determine whether pediatric patients undergo additional airport security screening after posterior spinal fusion. SUMMARY OF BACKGROUND DATA: Airport security has expanded to include body scanners as well as traditional metal detectors. Families frequently ask whether spinal implants will trigger airport security, but there is limited information on modern implants and screening methods. METHODS: The researchers conducted a survey of 50 pediatric patients after posterior spinal fusion from 2004 to 2013. Inclusion criteria were posterior instrumentation, pedicle screws for at least 80% of anchors, and at least 1 trip through an American airport after surgery. Charts and radiographs were reviewed for metal type, number of levels fused, number of anchors, and rod diameter. RESULTS: A total of 16% of patients (8 of 50) were detected by body scan or metal detector and all had cobalt chrome (CoCr) rods. No patients with stainless-steel (SS) rods were detected. The CoCr rods triggered additional screening in 24% of children (8 of 33), compared with none of 17 with SS rods (p = .03). For patients with CoCr rods, the detection rate was 18% (5 of 28) by metal detector and 17% (3 of 18) by body scanner. For patients with CoCr rods, there was no significant difference between detection rates and levels fused (p = .30), number of anchors (p = .15), or rod diameter (p = .17). CONCLUSIONS: In this series, CoCr constructs were more likely to incur additional airport security compared with more traditional SS constructs.

Is there a relationship between thoracic dimensions and pulmonary function in early-onset scoliosis?

STUDY DESIGN: Cross-sectional retrospective analysis. OBJECTIVE: To examine the degree of correlation between thoracic dimension outcome measures and pulmonary function in early-onset scoliosis (EOS). SUMMARY OF BACKGROUND DATA: Change in thoracic dimension (TD) measurements and spine length are commonly reported outcome measures after treatment for EOS. Although ultimately improving or maintaining pulmonary function is the goal of EOS treatment strategies, it is unclear whether commonly reported 2-dimensional TD measurements represent good predictors of pulmonary function. METHODS: A cross-sectional analysis of patients including all diagnoses obtained from 2 EOS databases containing TD measurements and pulmonary function data was performed. Relationships between individual TD measurements and pulmonary function measurements were assessed using the Pearson correlation analysis. TD measurements (pelvic inlet width, T1-T12 height, T1-S1 height, and coronal chest width) and standard pulmonary function measurements were compared. TD percentiles normalized for pelvic inlet width were also calculated and correlated with pulmonary function measurement percentiles. Univariate and multivariate linear regression analyses determined whether TD measurements could predict pulmonary function. RESULTS: There were 121 patients (65 females, 56 males) in the study. Mean age at evaluation was 9.3 years (range, 2.7-18.1 yr). T1-T12 height, T1-S1 height, maximal chest width, and pelvic inlet width were all significantly correlated with forced air volume expelled in 1 second, total forced air volume, and total lung capacity (correlation coefficients [r] 0.33-0.61; all P<0.001). T1-T12 predicted percentile (normalized for pelvic width) was significantly correlated with forced air volume expelled in 1 second and total forced air volume predicted percentiles (r=0.32, P<0.001 and r=0.27, P=0.004, respectively). Regression analysis determined that T1-T12 percentile was a significant predictor of forced air volume expelled in 1 second percentile and total forced air volume percentiles. Regression analysis found no predictive factors of total lung capacity percentile. CONCLUSION: Traditional 2-dimensional TD measurements (T1-T12 height) used to measure outcomes in EOS can be used as weak predictors of pulmonary function outcome. However, better outcome measures need to be developed, such as 3-dimensional and dynamic measurements. LEVEL OF EVIDENCE: 3.

The results of metal-on-metal hip resurfacing in patients under 30 years of age.

Degenerative hip conditions most commonly affect older patients. However, many cases occur in younger patients. Total hip arthroplasty is the conventional approach; however, hip resurfacing is a viable option. Fifty-three metal-on-metal resurfacings in 46 patients under age 30 were performed. Patients had a variety of etiologies, and were followed clinically and radiographically with mean follow-up of 98.2 months. Clinical scores and x-rays were compared pre-operatively and post-operatively. The last follow-up SF-12 and UCLA scores significantly improved post-operatively (P<0.0001). Range of motion scores also improved (P<0.001), and the mean Harris Hip Score was 88. There were 6 revisions. The Kaplan-Meier survivorship estimate at 8 years was 95%. Metal-on-metal hip resurfacing appears to be an effective procedure for younger patients. Longer-term data are needed for confirmation.

Childhood development after maternal metal-on-metal hip resurfacing.

Metal-on-metal (MoM) hip resurfacing has been used in many young, active patients, including women of childbearing age. While ion levels have been measured in mothers with MoM hip resurfacing and their babies, little is known about how these ions affect child development. Out of 1300, MoM hip resurfacing surgeries, we had 48 women of childbearing age (defined as 40 years of age or younger at the time of surgery). These women were contacted to see if they had had pregnancies after their surgery, and those who had were sent surveys asking about their pregnancies and the development of their children. Eleven women reported pregnancies, and eight returned the surveys. There were no significant differences between women with pregnancies and those without pregnancies in any demographic or clinical measures. From the eight women who completed surveys, there were seventeen pregnancies resulting in fourteen births. There were complications in three of the births resulting in two premature births, but no children were born with birth defects. Overall, the children appear to be developing normally. Based on this unique data, we do not feel that MoM hip resurfacing is contraindicated for women of childbearing age, but power analyses show that we cannot draw conclusive results from our sample. We recommend that other groups publish their own data to allow us to generate sufficient sample sizes to draw meaningful conclusions.

High performance of metal-on-metal bearings: a case report.

There has been considerable initial success with the use of total hip and resurfacing metal-metal implants tempered by poor performance of certain bearing designs, specifically small and/or abnormal component orientation. With a growing number of reports relating to adverse local tissue reactions, the need to monitor ion levels is crucial. This report presents a case of an extremely active bilateral metal-metal implant patient who had severe arthritis of the left hip and was originally treated with a cementless metal-on-polyethylene surface replacement. This implant lasted 12~years and after complete wear through of the polyethylene, the prosthesis was converted to metal-on-metal total hip. The patient continued to cycle vigorously and engaged in downhill skiing. Eventually his contralateral hip developed arthritis and he underwent metal-on-metal surface arthroplasty. Since his last surgery 8~years ago, the patient has resumed his activities, cycling an average of 6,400 miles and skiing over 60~days a year. He has been followed clinically and radiographically for 23 years with ion levels measured serially.

Results of Conserve Plus® metal-on-metal hip resurfacing for post-traumatic arthritis and osteonecrosis.

The safety and efficacy of metal-on-metal surface arthroplasty in post-traumatic arthritis and post-traumatic osteonecrosis (PT OA and PT ON) cases has not previously been thoroughly investigated. This study compared the outcomes of metal-on-metal hip resurfacing (HR) in patients performed for an indication of OA secondary to trauma to compared to PT ON. Metal-on-metal resurfacing arthroplasties were performed on 62 hips, 43 with PT OA and 19 with PT ON with secondary osteoarthritis. There were 51 males and 11 females. All patients were followed up clinically and radiographically with a mean follow-up of 87.2 months. Clinical outcome scores, survivorship, and radiographs were compared between the PT OA and PT ON group. The clinical outcomes for the PT ON and PT OA groups were similar with a survival rate of 95% (95% CI 82.1% to 98.8%) for the PT OA group alone at 8 years and 91% for those with PT OA with ON at 8 years (95% CI 50.8%-98.7%). The Kaplan-Meier survivorship curves for the cohorts of PT OA and PT ON patients were not statistically significantly different (Log rank, p=0.6036). Metal-on-metal hip resurfacing appears to be a safe and effective procedure for the treatment of both post-traumatic osteoarthritis and osteonecrosis.