The neuronal regulation of fracture healing: Effects of sciatic nerve resection in rat tibia

The effect of sciatic nerve resection on tibial fracture healing was studied in rats 25 days post-trauma. To prevent differences in loading between sham-operated and nerve-resected animals the fractured limbs were cast-immobilized. On radiograms 8 of 11 fractures in the sham-operated animals showed very little callus formation in contrast to only 1 of 8 fractures in the group with nerve resection. Measured by single-photon absorptiometry, animals with sciatic nerve resection had a higher bone mineral content than the sham-operated animals. However, the mechanical strength in three-point cantilever bending was not better in the nerve-resected rats, implying a defective organization of the large callus. These results suggest neural regulation plays a role in the type of fracture healing, primary or secondary, and in the amount and quality of the callus.     

Morphological characterization of cardiac induced intracranial pressure (ICP) waves in patients with overdrainage of cerebrospinal fluid and negative ICP

Symptomatic overdrainage of cerebrospinal fluid (CSF) can be seen in shunted hydrocephalus patients and in non-shunted patients with spontaneous intracranial hypotension (SIH). In these patients, intracranial pressure (ICP) monitoring often reveals negative static ICP, while it is less understood how the pulsatile ICP (cardiac induced ICP waves) is affected. This latter aspect is addressed in the present study. A set of 40 ICP recordings from paediatric and adult hydrocephalus patients were randomly selected. Each cardiac induced ICP wave was automatically identified and manually verified by the beginning and ending diastolic minimum pressures and the systolic maximum pressure. The ICP wave parameters (static pressure, amplitude, rise time, rise time coefficient, downward coefficient, wave duration, and area-under-curve) were then automatically computed. The material of 40 ICP recordings provided a total of 3,192,166 cardiac induced ICP waves (1,292,522 in paediatric patients and 1,899,644 in adult patients). No apparent changes in ICP wave parameters were seen when mean ICP became negative, except that the parameters amplitude, rise time coefficient, downward coefficient and area under curve somewhat increased when mean ICP was below -15 mmHg.     

Application of a novel hybrid study design to explore gene-environment interactions in orofacial clefts

Orofacial clefts are common birth defects with strong evidence for both genetic and environmental causal factors. Candidate gene studies combined with exposures known to influence the outcome provide a highly targeted approach to detecting GxE interactions. We developed a new statistical approach that combines the case-control and offspring-parent triad designs into a "hybrid design" to search for GxE interactions among 334 autosomal cleft candidate genes and maternal first-trimester exposure to smoking, alcohol, coffee, folic acid supplements, dietary folate and vitamin A. The study population comprised 425 case-parent triads of isolated clefts and 562 control-parent triads derived from a nationwide study of orofacial clefts in Norway (1996-2001). A full maximum-likelihood model was used in combination with a Wald test statistic to screen for statistically significant GxE interaction between strata of exposed and unexposed mothers. In addition, we performed pathway-based analyses on 28 detoxification genes and 21 genes involved in folic acid metabolism. With the possible exception of the T-box 4 gene (TBX4) and dietary folate interaction in isolated CPO, there was little evidence overall of GxE interaction in our data. This study is the largest to date aimed at detecting interactions between orofacial clefts candidate genes and well-established risk exposures.     

A randomized study on migration of the Spectron EF and the Charnley flanged 40 cemented femoral components using radiostereometric analysis at 2 years

Background and purpose

We performed a randomized study to determine the migration patterns of the Spectron EF femoral stem and to compare them with those of the Charnley stem, which is regarded by many as the gold standard for comparison of implants due to its extensive documentation.

Patients and methods

150 patients with a mean age of 70 years were randomized, single-blinded, to receive either a cemented Charnley flanged 40 monoblock, stainless steel, vaquasheen surface femoral stem with a 22.2-mm head (n = 30) or a cemented Spectron EF modular, matte, straight, collared, cobalt-chrome femoral stem with a 28-mm femoral head and a roughened proximal third of the stem (n = 120). The patients were followed with repeated radiostereometric analysis for 2 years to assess migration.

Results

At 2 years, stem retroversion was 2.3° and 0.7° (p < 0.001) and posterior translation was 0.44 mm and 0.17 mm (p = 0.002) for the Charnley group (n = 26) and the Spectron EF group (n = 74), respectively. Subsidence was 0.26 mm for the Charnley and 0.20 mm for the Spectron EF (p = 0.5).

Interpretation

The Spectron EF femoral stem was more stable than the Charnley flanged 40 stem in our study when evaluated at 2 years. In a report from the Norwegian arthroplasty register, the Spectron EF stem had a higher revision rate due to aseptic loosening beyond 5 years than the Charnley. Initial stability is not invariably related to good long-term results. Our results emphasize the importance of prospective long-term follow-up of prosthetic implants in clinical trials and national registries and a stepwise introduction of implants.Femoral stem loosening in cemented total hip arthroplasty (THA) is a multifactorial process with different mechanisms (Gruen et al. 1979, Barrack 2000). Factors such as the material, design, and surface finish are of fundamental importance for the long-term performance of cemented femoral hip implants (Scheerlinck and Casteleyn 2006). The longevity of cemented femoral stems has been related to the quality, stability, and endurance of the bonding between stem and cement (Chang et al. 1998, Scheerlinck and Casteleyn 2006). Different femoral stem designs have been developed to obtain increased fixation at this interface, since debonding between the cement and stem is an important mechanism in the initiation of loosening (Jasty et al. 1991).The satin-finish Spectron femoral stem has been one of the best performing stems in the Swedish National Arthroplasty Register (Malchau et al. 2002). A modified, proximally roughened version of the Spectron stem, the Spectron EF (Smith and Nephew, Memphis, TN), was introduced in 1989 to enhance stem-cement bonding.The use of this implant gained increasing popularity, and in 2007 the Spectron EF stem used with the Reflection All-Poly acetabular cup (Smith and Nephew) was the most commonly used primary total hip prosthesis in Norway (Espehaug et al. 2009).The degree of migration during the first years after surgery has been shown to correlate with the long-term performance of joint prostheses (Kärrholm et al. 1994, Kobayashi et al. 1997). Radiostereometric analysis (RSA) allows the accurate measurement of implant movement and has been extensively used for measurement of the in vivo migration of implants (Kärrholm et al. 1997).An earlier prospective randomized study reported an increased revision rate of the Charnley stem compared to the satin-finished Spectron stem (Garellick et al. 1999). In the present randomized, controlled clinical trial we wanted to evaluate the early migration of the successor to this stem, the Spectron EF stem and to compare it to that of the Charnley stem using RSA. The null hypothesis was that the migration of the Spectron EF stem was equal to that of the Charnley prosthesis (DePuy International Ltd., Leeds, UK), which has the longest follow-up and the largest volume of documentation of implants used for primary total hip arthroplasty (Aamodt et al. 2004).     

Long-term outcome of slipped capital femoral epiphysis: a 38-year follow-up of 66 patients

Purpose  

The purpose of this retrospective study was to evaluate the long-term outcome of different methods of treatment in slipped capital femoral epiphysis (SCFE), to find risk factors for poor outcome, and to assess whether prophylactic fixation is indicated.     

Human infants orient to biological motion rather than audiovisual synchrony

Both orienting to audiovisual synchrony and to biological motion are adaptive responses. The ability to integrate correlated information from multiple senses reduces processing load and underlies the perception of a multimodal and unified world. Perceiving biological motion facilitates filial attachment and detection of predators/prey. In the literature, these mechanisms are discussed in isolation. In this eye-tracking study, we tested their relative strengths in young human infants. We showed five-month-old infants point-light animation pairs of human motion, accompanied by a soundtrack. We found that audiovisual synchrony was a strong determinant of attention when it was embedded in biological motion (two upright animations). However, when biological motion was shown together with distorted biological motion (upright animation and inverted animation, respectively), infants looked at the upright animation and disregarded audiovisual synchrony. Thus, infants oriented to biological motion rather than multimodally unified physical events. These findings have important implications for understanding the developmental trajectory of brain specialization in early human infancy.     

Wear and migration of highly cross‐linked and conventional cemented polyethylene cups with cobalt chrome or Oxinium femoral heads: A randomized radiostereometric study of 150 patients

This randomized study was performed to compare wear and migration of five different cemented total hip joint articulations in 150 patients. The patients received either a Charnley femoral stem with a 22.2 mm head or a Spectron EF femoral stem with a 28 mm head. The Charnley articulated with a γ‐sterilized Charnley Ogee acetabular cup. The Spectron EF was used with either EtO‐sterilized non‐cross‐linked polyethylene (Reflection All‐Poly) or highly cross‐linked (Reflection All‐Poly XLPE) cups, combined with either cobalt chrome (CoCr) or Oxinium femoral heads. The patients were followed with repeated RSA measurements for 2 years. After 2 years, the EtO‐sterilized non‐cross‐linked Reflection All‐Poly cups had more than four times higher proximal penetration than its highly cross‐linked counterpart. Use of Oxinium femoral heads did not affect penetration at 2 years compared to heads made of CoCr. Further follow‐up is needed to evaluate the benefits, if any, of Oxinium femoral heads in the clinical setting. The Charnley Ogee was not outperformed by the more recently introduced implants in our study. We conclude that this prostheses still represents a standard against which new implants can be measured. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1222–1229, 2011     

Head injury mortality in the Nordic countries

Traumatic brain injury (TBI) is a major cause of morbidity and mortality in Western countries. Effective management planning for these patients requires knowledge of TBI epidemiology. The purpose of this study was to describe and analyze the development of TBI mortality in the Nordic countries during the period 1987-2001. Data on TBI deaths were retrieved from the national official statistical agencies according to specified diagnostic codes. We also collected data on the number of operations for acute TBI in the year 2000 from all Nordic hospitals admitting trauma patients. Finland had about twice as high a TBI mortality rate as the other countries. Similarly, the Finnish incidence of acute TBI operations was nearly twice that of the other countries. The median TBI death rate for Finland was 21.2 per 100,000 per year, and for Denmark, Norway, and Sweden 11.5, 10.4, and 9.5, respectively. There were more male than female deaths in all countries. The mortality rate from extracranial injuries was relatively equal between the countries. We observed a sizeable reduction in TBI mortality rates for all countries, except in Finland. Younger age groups had the most pronounced decrease in TBI mortality rates. The oldest age group had the least favorable development of TBI mortality rates, and the mean age of TBI casualties increased substantially during the study period. This study demonstrates considerable differences in and between the Nordic countries regarding TBI mortality. Preventive measures and implementation of regional guidelines are needed to assure a positive development in the future.