Assessing the reliability of the modified Gartland classification system for extension-type supracondylar humerus fractures

PURPOSE

The Gartland extension-type supracondylar humerus (SCH) fracture is the most common paediatric elbow fracture. Treatment options range from nonoperative treatment (taping or casting) to operative treatments (closed reduction and percutaneous pinning or open reduction). Classification variability between surgeons is a potential contributing factor to existing controversy over treatment options for type II SCH fractures. This study investigated levels of agreement in extension-type SCH fracture classification using the modified Gartland classification system.

METHODS

A retrospective review was conducted on 60 patients aged between two and 12 years who had sustained an extension-type SCH fracture and received operative or nonoperative treatment at a tertiary children's hospital. Baseline radiographs were provided, and surgeons were asked to classify the fractures as type I, IIA, IIB or III according to the modified Gartland classification. Respondents were then asked to complete a second round of classifications using reshuffled radiographs. Weighted kappa values were calculated to assess interobserver and intraobserver levels of agreement.

RESULTS

In all, 21 paediatric orthopaedic surgeons responded to the survey and 15 completed a second round of ratings. Interobserver agreement for classification based on the Gartland criteria between surgeons was substantial with a kappa of 0.679 (95% confidence interval (CI) 0.501 to 0.873). Intraobserver agreement was substantial with a kappa of 0.796, (95% CI 0.628 to 0.864).

CONCLUSION

Radiographic classification of extension-type SCH fractures demonstrated substantial agreement both between and within surgeon raters. Therefore, classification variability may not be a major contributing factor to the treatment controversy for type II SCH fractures and treatment variability may be due to differences in surgeon preferences.

LEVEL OF EVIDENCE

III.

Skeletal muscle and plasma concentrations of cefazolin during complex paediatric spinal surgery

BACKGROUND

Surgical site infections (SSIs) can have devastating consequences for children who undergo spinal instrumentation. Prospective evaluations of prophylactic cefazolin in this population are limited. The purpose of this study was to describe the pharmacokinetics and skeletal muscle disposition of prophylactic cefazolin in a paediatric population undergoing complex spinal surgery.

METHODS

This prospective pharmacokinetic study included 17 children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, with a median age of 13.8 [interquartile range (IQR) 13.4-15.4] yr and a median weight of 60.6 (IQR 50.8-66.0) kg. A dosing strategy consistent with published guidelines was used. Serial plasma and skeletal muscle microdialysis samples were obtained during the operative procedure and unbound cefazolin concentrations measured. Non-compartmental pharmacokinetic analyses were performed. The amount of time that the concentration of unbound cefazolin exceeded the minimal inhibitory concentration for bacterial growth for selected SSI pathogens was calculated.

RESULTS

Skeletal muscle concentrations peaked at a median of 37.6 (IQR 26.8-40.0) µg ml(-1) within 30-60 min after the first cefazolin 30 mg kg(-1) dose. For patients who received a second 30 mg kg(-1) dose, the peak concentrations reached a median of 40.5 (IQR 30.8-45.7) µg ml(-1) within 30-60 min. The target cefazolin concentrations for SSI prophylaxis for meticillin-sensitive Staphylococcus aureus (MSSA) and Gram-negative pathogens were exceeded in skeletal muscle 98.9 and 58.3% of the intraoperative time, respectively.

CONCLUSIONS

For children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, the cefazolin dosing strategy used in this study resulted in skeletal muscle concentrations that were likely not to be effective for intraoperative SSI prophylaxis against Gram-negative pathogens.

Incidence of acetabular dysplasia in breech infants following initially normal ultrasound: the effect of variable diagnostic criteria

PURPOSE

This study aimed to determine the incidence of acetabular dysplasia at six months of age in patients with breech presentation and previously normal hip ultrasounds, reporting primary radiographic measurements to allow for comparison with other patient cohorts.

METHODS

A retrospective analysis of breech infants with initially normal clinical examinations and hip ultrasounds was performed to determine the rate of subsequent acetabular dysplasia and to characterise the distribution of acetabular index (AI). At approximately six months of age, AI was measured bilaterally on anteroposterior (AP) pelvic radiographs and reported using descriptive statistics.

RESULTS

A total of 94 hips in 47 breech infants were eligible for analysis. All infants demonstrated normal ultrasound findings at a mean age of 6.9 ± 1.7 weeks and returned for follow-up at a mean age of 6.4 ± 0.5 months. On AP pelvic radiographs, mean right hip AI was 25.0°, with an interquartile range (IQR) (25^th -75^th percentile) of 23° to 27° and mean left hip AI was 25.5°, with an IQR of 22° to 28°. If one applies a single commonly used threshold value for defining dysplasia (AI ≥ 30°), 10/94 hips (10.6%) meet diagnostic criteria. Alternatively, strict adherence to previously established normative AI values stratified by gender and laterality results in 4/94 hips (4.3%) qualifying as significantly dysplastic.

CONCLUSIONS

The proportion of breech infants who, despite normal initial ultrasound findings, were diagnosed with dysplasia at six months supports observation of breech-born patients beyond six weeks. Reliance on different threshold values for diagnosing acetabular dysplasia can lead to discrepancies in incidence rates.

An improved method for measuring hip abduction in spica after surgical reduction for developmental dysplasia of the hip

PURPOSE

Excessive in-spica abduction is a risk factor for oste-onecrosis after surgical reduction for developmental dysplasia of the hip (DDH). The traditional method for radiographically measuring hip abduction using axial imaging does not reflect the true angle, which usually lies in an oblique plane. The purpose of this study was to describe a novel method for measuring true hip position using advanced imaging.

METHODS

A trigonometric model was derived to define hip position based upon the femoral axis angular deviation from midline as measured on axial and coronal sequences of MRI studies. In-spica MRIs of 28 hips having undergone surgery for DDH were reviewed. On two separate occasions, the same three raters measured the femoral axis deviation from mid-line on axial and coronal imaging. Abduction was estimated using the traditional method of measurement and our novel method. Intra- and inter-rater reliability were assessed.

RESULTS

The methods yielded different estimates (p < 0.001). Inter- and intra-rater reliability were excellent for both methods (inter-rater ICC > 0.922, intra-rater ICC > 0.919). The traditional method is accurate at 90° of flexion, but it increasingly overestimates abduction as hip flexion decreases. All cases where hip flexion was ≤ 40° exhibited ≥ 10° of error.

CONCLUSIONS

Decreasing hip flexion in spica modifies the perceived angle of abduction as measured using axial imaging. This inaccuracy can be overcome through assessment of orthogonal views using our new approach, which is accurate and reliable. It should be considered for future research investigating the effects of in-spica hip position on outcomes of DDH treatment.

Sciatic nerve blockade in infant, adolescent, and adult rats: a comparison of ropivacaine with bupivacaine

BACKGROUND

Ropivacaine is a newly introduced local anesthetic. No data are available regarding its safety, efficacy, or sensory-selectivity in children. The sciatic block duration and systemic toxicity of bupivacaine and ropivacaine were compared among infant, adolescent, and adult rats.

METHODS

Infant, adolescent, and adult rats received blocks with ropivacaine or bupivacaine. Nociceptive, proprioceptive, and motor blockade were assessed. Systemic effects (contralateral leg analgesia, seizures, respiratory distress, apnea) were quantified. Plasma local anesthetic concentrations were measured at terminal apnea.

RESULTS

Nerve blockade for a given absolute dose lasted longer in infants than in older rats for both drugs. Block duration from ropivacaine generally was the same as or slightly shorter than bupivacaine. There was no difference in sensory-selectivity between the drugs. Doses required to induce all systemic toxicity indices were inversely related to age (e.g., the lethal dose in 50% of animals [LD50] of ropivacaine in infants is 155 mg/kg; in adults it is 54 mg/kg). All indices of toxicity occurred at higher doses per kilogram for ropivacaine than bupivacaine, at all ages (e.g., the LD50 of bupivacaine in infants is 92 mg/kg; in adults it is 30 mg/kg). Plasma concentrations at terminal apnea were higher for ropivacaine than for bupivacaine at all ages, and were higher in infants than in older rats.

CONCLUSIONS

Ropivacaine resembles bupivacaine in its local anesthetic effects but has a greater margin of safety. For a given absolute dose, sciatic blockade in infant rats lasts longer than in adolescents or adults. Although the doses (in milligrams per kilogram) causing toxicity were much higher in infants than in adults, this probably does not correspond to a wider therapeutic index.