Biomechanical cadaver testing of a fixed-angle plate in comparison to tension wiring and screw fixation in transverse patella fractures

INTRODUCTION

Operative treatment of patella fractures is frequently associated with implant failure and secondary dislocation which can be attributed to the employed hardware. Therefore, a 2.7 mm fixed-angle plate designed for the treatment of patella fractures was tested biomechanically against the currently preferred methods of fixation. It was hypothesized that under simulated cyclic loading fixed-angle plating would be superior to modified anterior tension wiring or cannulated lag screws with anterior tension wiring.

MATERIALS AND METHODS

Eighteen human cadaver knees, matched by bone mineral density and age, were divided into three groups of six. After setting a transverse patella fracture each group received one of the osteosyntheses mentioned above. Repetitive testing over 100 cycles was performed at non-destructive loads by simulating knee motion from 90° flexion to full extension.

RESULTS

Anterior tension wiring as well as lag screws with tension wiring showed significant fracture displacement after the initial cycle already. Both constructs, lag screws plus wiring (3.7 ± 2.7 mm) as well as tension wiring alone (7.1 ± 2.2 mm) displayed fracture displacement of >2 mm which is clinically regarded as failure. Those patellae stabilized with fixed-angle plates showed no significant fracture gap widening after completion of 100 cycles (0.7 ± 0.5 mm). The differences between the fixed-angle plate group and the other two groups were statistically significant (p<0.05).

CONCLUSION

In contrast to modified anterior tension wiring and cannulated lag screws with anterior tension wiring the bilateral fixed-angle plate was the only fixation device to stabilize transverse patella fractures securely and sustainably.

Objective measures of motor dysfunction after compression spinal cord injury in adult rats: correlations with locomotor rating scores

Precise assessment of motor deficits after traumatic spinal cord injury (SCI) in rodents is crucial for understanding the mechanisms of functional recovery and testing therapeutic approaches. Here we analyzed the applicability to a rat SCI model of an objective approach, the single-frame motion analysis, created and used for functional analysis in mice. Adult female Wistar rats were subjected to graded compression of the spinal cord. Recovery of locomotion was analyzed using video recordings of beam walking and inclined ladder climbing. Three out of four parameters used in mice appeared suitable: the foot-stepping angle (FSA) and the rump-height index (RHI), measured during beam walking, and for estimating paw placement and body weight support, respectively, and the number of correct ladder steps (CLS), assessing skilled limb movements. These parameters, similar to the Basso, Beattie, and Bresnahan (BBB) locomotor rating scores, correlated with lesion volume and showed significant differences between moderately and severely injured rats at 1-9 weeks after SCI. The beam parameters, but not CLS, correlated well with the BBB scores within ranges of poor and good locomotor abilities. FSA co-varied with RHI only in the severely impaired rats, while RHI and CLS were barely correlated. Our findings suggest that the numerical parameters estimate, as intended by design, predominantly different aspects of locomotion. The use of these objective measures combined with BBB rating provides a time- and cost-efficient opportunity for versatile and reliable functional evaluations in both severely and moderately impaired rats, combining clinical assessment with precise numerical measures.

Long term higher urinary calcium excretion within the normal physiologic range predicts impaired bone status of the proximal radius in healthy children with higher potential renal acid load

Reduced bone mineral density (BMD) and bone mass have been observed in children with idiopathic hypercalciuria. Whether urinary calcium excretion at the higher end of the normal physiologic range can influence bone health in healthy children independent of dietary intake is unknown. Urinary calcium was quantified in 603 24-h urine samples from 154 healthy children and adolescents who had ≥3 urine collections and parallel 3-day weighed dietary records during the 4years preceding proximal forearm bone analyses by peripheral quantitative computed tomography (pQCT). Urinary potential renal acid load (uPRAL) was determined according to urine ionogram by subtracting measured quantitatively important mineral cations from nonbicarbonate anions. Urinary calcium excretion was significantly associated with volumetric (v)BMD (P=0.04), almost significantly with cortical bone mineral content (BMC) (P=0.05), but not with cortical cross-sectional area (CSA) (P=0.09), total CSA (P=0.3), or Strength-Strain Index (P=0.8) in the total population sample. Stratified analyses based on the median split of uPRAL showed that calcium excretion was negatively associated with vBMD (P=0.007), cortical BMC (P=0.001), and cortical CSA (P=0.004) in those children with higher uPRALs, but not in those with low uPRALs (P>0.3). In conclusion, long-term higher calciuria within the physiological range predicts reduced diaphyseal bone mass and bone density particularly in healthy children and adolescents with long-term unfavorable higher dietary acid load, i.e., with lower fruit and vegetable intake.

Attenuated BMP1 function compromises osteogenesis, leading to bone fragility in humans and zebrafish

Bone morphogenetic protein 1 (BMP1) is an astacin metalloprotease with important cellular functions and diverse substrates, including extracellular-matrix proteins and antagonists of some TGFβ superfamily members. Combining whole-exome sequencing and filtering for homozygous stretches of identified variants, we found a homozygous causative BMP1 mutation, c.34G>C, in a consanguineous family affected by increased bone mineral density and multiple recurrent fractures. The mutation is located within the BMP1 signal peptide and leads to impaired secretion and an alteration in posttranslational modification. We also characterize a zebrafish bone mutant harboring lesions in bmp1a, demonstrating conservation of BMP1 function in osteogenesis across species. Genetic, biochemical, and histological analyses of this mutant and a comparison to a second, similar locus reveal that Bmp1a is critically required for mature-collagen generation, downstream of osteoblast maturation, in bone. We thus define the molecular and cellular bases of BMP1-dependent osteogenesis and show the importance of this protein for bone formation and stability.

[Standardized x-ray reports of the spine in osteogenesis imperfecta]

PURPOSE

In this study we present a standard for radiological reports in patients with osteogenesis imperfecta (OI). The parameters can be used to describe X-rays of the lateral spine and give an impartial description of anatomical structures during a treatment with bisphosphonates.

MATERIAL AND METHODS

In this retrospective analysis we included 48 patients with OI (31 female, 17 male [1.5 months - 19 years, mean age 9.0 years]). Lateral spine X-rays were analyzed by 2 radiologists before and during treatment. The parameters of the standardized report are degree of kyphoscoliosis, compression of single vertebrae, predominant type of vertebral deformities and extent of vertebral compression (score 1 - 5).

RESULTS

There was no clear trend in the change of compression of single vertebrae. Some vertebrae with ventral compression showed an upgrowth to vertebrae with harmonic compression. Other deformities showed only marginal changes. In 26 patients the kyphoscoliosis improved (mean 10 degrees), in 36 patients the thoracic vertebrae compression increased and in 30 patients the vertebral height in the lumbar spine increased. The improvement of vertebral height was 1 point in the thoracic and lumbar spine.

CONCLUSION

We propose a standardized report of X-rays of the lateral spine in patients with OI with quantitative and semiquantitative parameters using morphological criteria. These include compression of single vertebrae, degree of kyphoscoliosis, vertebral deformities and the severity of vertebral compression in the thoracic and lumbar spine.

Symptomatic cerebral oedema during treatment of diabetic ketoacidosis: effect of adjuvant octreotide infusion

INTRODUCTION

A potentially lethal complication of diabetic ketoacidosis (DKA) in children is brain oedema, whether caused by DKA itself or by the therapeutic infusion of insulin and fluids.

CASE PRESENTATION

A 10-year old previously healthy boy with DKA became unconscious and apnoeic due to cerebral oedema (confirmed by abnormal EEG and CT-scan) during treatment with intravenous fluids (36 ml/h) and insulin (0.1 units/kg/h). He was intubated and artificially ventilated, without impact on EEG and CT-scan. Subsequently, adjuvant infusion of octreotide was applied (3.5 μg/kg/h), suppressing growth hormone (GH) and IGF-1 production and necessitating the insulin dose to be reduced to 0.05 - 0.025 units/kg/h. The brain oedema improved and the boy made a full recovery.

CONCLUSION

Co-therapy with octreotide was associated with a favourable outcome in the present patient with DKA and cerebral oedema. Whether this could be ascribed to the effects of octreotide on the insulin requirement or on the GH/IGF-axis remains to be elucidated.

Free deoxypyridinoline in urine and serum--results in children and adolescents

The urinary excretion of the collagen crosslinking compound dexoypyridinoline (DPD) is considered a specific index of bone resorption. Here we report on the levels of free (i.e., non peptide-bound) DPD in the urine and serum of subjects from 5 to 19 years of age, as determined by a new radioimmunoassay. Reference values for free DPD were established using 24-h urine collections from 118 healthy children and serum samples from 133 children with acute febrile illnesses. Serum and urine levels of free DPD were compared in samples from 23 short, normal children. Additionally, total (the sum of peptide-bound and free) DPD was measured by high-performance liquid chromatography in the 24-h urine collections. Urinary-free DPD was significantly correlated with total DPD (r = 0.90; P < 0.001) and declined steadily with age. Serum levels of free DPD ranged from 0.9 to 5.7 nmol/l and varied with age in boys only. No significant association was found between serum and urine levels of free DPD (r = 0.08; P = 0.37). In conclusion, urinary-free DPD did not reflect enhanced bone turnover during the time of puberty. Free DPD serum levels are very low, which may be due to rapid clearance via the kidneys.

Urinary excretion of hydroxy-pyridinium cross-links of collagen reflects skeletal growth velocity in normal children

Two new markers of bone resorption, the collagen cross-linking amino acids pyridinoline (PYD) and deoxypyridinoline (DPD), were measured in 24-h urine collections from 88 healthy children (45 females, 43 males; age 4 to 18 years) and 17 adults. Normal values for pediatric use were established for these parameters. Related to daily excretion of creatinine PYD and DPD were about 3 to 6 fold higher in the pediatric groups than in adults. The collagen cross-links showed a highly significant correlation to the urinary excretion of hydroxyproline (OHP): r = 0.65 for PYD and r = 0.60 for DPD (p < 0.001). Both collagen cross-links and OHP excretion related to creatinine were significantly correlated to growth velocity (r = 0.67, 0.62 and 0.51 for PYD, DPD and OHP respectively; p < 0.001 in each case). PYD and DPD may be useful for the monitoring of growth in children.

Genetic causes of goiter and deafness: Pendred syndrome in a girl and cooccurrence of Pendred syndrome and resistance to thyroid hormone in her sister

CONTEXT

Goiter and deafness can be associated in some genetic syndromes, e.g. Pendred syndrome (PS) and resistance to thyroid hormone (RTH). PS is an autosomal recessive disorder characterized by goiter and sensorineural hearing impairment with an enlarged vestibular aqueduct bilaterally. RTH is an autosomal dominant condition of reduced tissue sensitivity to thyroid hormone in which goiter is very frequent and hearing loss occurs in about 20% of patients. OBJECTIVE, PATIENTS, AND DESIGN: The objective of this study was to identify the cause of goiter and deafness in two sisters born to healthy unrelated parents. We present their history, clinical presentation, and follow-up and report the results of molecular genetic investigations.

RESULTS

The elder sister had an elevated TSH level at newborn screening followed by subclinical hypothyroidism, childhood-onset goiter, and bilateral progressive sensorineural hearing impairment with enlarged vestibular aqueducts, consistent with a diagnosis of PS. Her younger sister had congenital goiter, elevated free T3 and free T4 concentrations with unsuppressed TSH, sinus tachycardia, and bilateral progressive sensorineural hearing impairment with enlarged vestibular aqueducts. This clinical presentation was consistent with a diagnosis of RTH, in which, however, inner ear malformations are uncommon. Interestingly, molecular genetic testing showed that, whereas the elder sister is affected by PS, the younger sister has both PS (due to compound heterozygous SLC26A4 mutations) and RTH (due to a novel de novo heterozygous THRB mutation).

CONCLUSIONS

This is the first report of the cooccurrence, in the same individual, of PS and RTH, two genetic syndromes both associated with goiter and hearing impairment.

Growth response to an individualized versus fixed dose GH treatment in short children born small for gestational age: the OPTIMA study

OBJECTIVE

Initial GH-induced catch up growth is highly variable in short children born small for gestational age (SGA) and mainly influenced by age at start of therapy and GH dose. This study compared the first year growth-promoting effect of an individually adjusted GH dose (IAD) versus a fixed high GH dose (FHD) in pre-pubertal children born SGA with severe short stature.

DESIGN

This was a randomized, open-label, multi-center study.

METHODS

The FHD group received 0.067 mg/kg per day GH throughout the 12-month study. The IAD group initially received 0.035 mg/kg per day GH; at 3 months the Cologne growth-prediction model for first year change in height SDS was applied; if predicted change was <0.75, GH was increased to 0.067 mg/kg per day for the remaining 9 months, otherwise the initial dose was continued.

RESULTS

In the IAD group, 38 out of the 80 patients required the higher GH dose from month 3. From an ANCOVA for non-inferiority, mean difference in change in height SDS between IAD and FHD groups was -0.24 (95% confidence interval (CI) -0.35: -0.12), the CI for height SDS being above the pre-defined non-inferiority margin of -0.5. GH dose reductions due to IGF-I SDS >0.5 and IGFBP-3 SDS <-0.5 were performed in 4/99 FHD patients, but none of the IAD group patients. Safety data were similar between groups.

CONCLUSION

With a mean treatment group difference of 1 cm in 12-month growth response, although statistically significant, the IAD group was considered non-inferior compared with the FHD group. Early growth prediction can be used to tailor the dose to the individual patient's needs, resulting in lower overall GH dose.

Insulin binding to antibodies is a risk factor for inexplicable severe hypoglycaemia in children with type-1 diabetes mellitus

BACKGROUND

Type-1 diabetic individuals differ with regard to both, the formation of circulating insulin antibodies, and the incidence of severe hypoglycaemia.

AIM OF THE STUDY

To assess the association of insulin binding to antibodies with the incidence of severe hypoglycaemia.

PATIENTS AND METHODS

In a cross sectional study, 73 children with type-1 diabetes mellitus (median age 14 years, duration of diabetes 6 years) were investigated, 22 of whom had experienced severe hypoglycaemia during the past 18 months, and 51 had never experienced severe hypoglycaemia. Of the patients with severe hypoglycaemia 16 had experienced severe unexplained hypoglycaemias, and 6 had experienced severe hypoglycaemias which were explicable (by missed meals, unplanned physical exercise etc.). Insulin binding was measured in a blinded central laboratory by radioimmunoassay, and expressed as ratio bound/unbound insulin; a binding >15% was considered relevant insulin binding.

RESULTS

A total of 38 patients displayed relevant insulin binding (17 of whom had experienced severe hypoglycaemia), and 35 patients did not (5 of whom had experienced severe hypoglycaemia; p=0.0055, Fisher's exact test). Patients with relevant insulin binding were younger (12.2 vs 14.5 years, p=0.006) than patients without relevant insulin binding. From the 16 patients with inexplicable severe hypoglycaemia, 15 displayed relevant insulin binding, compared to 2 of the 6 patients with explicable severe hypoglycaemia (p=0.009). The association of any severe hypoglycaemia, and of inexplicable severe hypoglycaemia, with relevant insulin binding was significant (odds ratio 4.8 (95%CI 1.5-15.2), and 22.1(95%CI 2.7-179.6), p<0.006). Patients with/without relevant insulin binding, or with/without severe hypoglycaemia, did not differ significantly regarding sex, duration of diabetes, number of insulin injections per day, HbA1c and C-peptide levels (ANOVA).

CONCLUSION

Insulin binding to antibodies >15% appears to be a strong risk factor for inexplicable severe hypoglycaemias in type-1 diabetic children.

Muscle function improves during growth hormone therapy in short children born small for gestational age: results of a peripheral quantitative computed tomography study on body composition

BACKGROUND

Short small for gestational age (SGA) children can be affected by a lack of muscle mass rather than fat mass. They also face a high risk of the metabolic syndrome developing after childhood. It is not known whether low muscle mass influences muscle function.

AIM

Our aim was to investigate muscle-fat distribution and muscle function before and during GH treatment in short SGA children.

PATIENTS

A total of 34 prepubertal short SGA children (11 females, seven with Silver-Russell syndrome) were included in the study. Mean values were: age at GH start 7.3 yr; height sd score (SDS) -3.3; and birth weight SDS -2.7.

METHODS

Investigations over 24 months on GH treatment (57 microg/kg.d) were performed. Body composition, including fat area and muscle area (MA), was assessed through peripheral quantitative computed tomography (XCT 2000; Stratec, Inc., Pforzheim, Germany). Maximal isometric grip force was performed with a Jamar dynamometer (Preston, Jackson, MI). Comparison with height-dependent reference values (SDS(Height)) was calculated.

RESULTS

MA SDS(Height) at GH start was -1.8 and increased to -0.8 (P < 0.001) and -0.8, and fat area SDS(Height) decreased from -0.6 to -2.0 (P < 0.001) and -1.5 after 12 and 24 months on GH. Maximal isometric grip force SDS(Height) increased from -0.9 to 0.3 (P < 0.001) and 0.5. MA at start correlated negatively with height velocity (R = -0.54; P < 0.001) and MA SDS at start and Delta-height SDS during the first year of GH treatment (R = -0.40; P < 0.001).

CONCLUSIONS

Short stature in SGA children is associated with low muscle mass and function. Supraphysiological GH doses led to a concomitant increment in height, muscle mass, and function, whereas fat mass decreased. Furthermore, body composition at GH start gives insight into GH responsiveness and the individual risk of metabolic syndrome.

[Bisphosphonate therapy for children and adolescents with primary and secondary osteoporotic diseases]

Bisphosphonates have a set place in the treatment of osteoporosis in adults. For the last 10 years they have also been used in pediatrics. Due to inhibition in differentiation and reduction in osteoclasts, both pamidronate and alendronate, the most commonly used preparations, cause an increase in bone density. Most experience comes from the i.v. treatment of forms with severe courses of osteogenesis imperfecta (OI). There is an increase in bone substance, a decrease in rate of fractures and a reduction in pain with higher mobility of those effected. In addition to the use of drugs, intramedullary nailing and physiotherapy are important therapeutic standards. Bisphosphonates are also used for other diseases involving bone remodeling, such as juvenile idiopathic osteoporosis or familial hyperphosphatemia. Acute side effects usually occur with the first infusion, involve "flu-like" symptoms and are self limiting. The question of long-term side effects cannot be answered with the currently available data.