Characteristics and demography of low energy fall injuries in patients > 60 years of age: a population-based analysis over a decade with focus on undertriage.

BACKGROUND: An increasing group of elderly patients is admitted after low energy falls. Several studies have shown that this patient group tends to be severely injured and is often undertriaged. METHODS: Patients > 60 years with low energy fall (< 1 m) as mechanism of injury were identified from the Stavanger University Hospital trauma registry. The study period was between 01.01.11 and 31.12.20. Patient and injury variables as well as clinical outcome were described. Undertriage was defined as patients with a major trauma, i.e., Injury Severity Score (ISS) > 15, without trauma team activation. Statistical analysis was performed using the Chi-squared test for categorical variables and the Mann-Whitney U test for continuous variables. RESULTS: Over the 10-year study period, 388 patients > 60 years with low energy fall as mechanism of injury were identified. Median age was 78 years (IQR 68-86), and 53% were males. The location of major injury was head injury in 41% of the patients, lower extremities in 19%, and thoracic injuries in 10%. Thirty-day mortality was 13%. Fifty percent were discharged to home, 31% to nursing home, 9% in hospital mortality, and the remaining 10% were transferred to other hospitals or rehabilitation facilities. Ninety patients had major trauma, and the undertriage was 48% (95% confidence interval, 38 to 58%). CONCLUSIONS: Patients aged > 60 years with low energy falls are dominated by head injuries, and the 30-day mortality is 13%. Patients with major trauma are undertriaged in half the cases mandating increased awareness of this patient group.

Load transfer in the proximal femur and primary stability of a cemented and uncemented femoral stem: An experimental study on cadaver femurs.

There are principally two fixation methods in total hip arthroplasty, cemented and uncemented. Both methods have in general good long-time survival. Studies comparing cemented and uncemented femoral stems indicate that the cemented stems perform somewhat better, at least in the elderly population. The aim of this study was to compare load transfer and the initial micromotion pattern for an uncemented and a cemented stem. A total of 12 human cadavers were tested in a hip simulator during single leg and stair climbing. Strain was measured on the proximal femur before and after implantation of the prostheses, and the values were presented as percentage of physiological strain. The micromovements between the stem and bone were measured and a total point motion was calculated. The results showed small statistically significant differences between the fixation methods, the largest difference being 8.1 percentage points. The uncemented stem had somewhat higher micromotion than the cemented stem, but less than 10 µm. Both stems thus had acceptable primary stability. The main finding of this study is the strain and micromotion pattern of a cemented and an uncemented stem of similar geometry is overall equal. There were small statistical significant differences between the two fixation methods regarding strain and micromotion levels. The differences are considered too small to be clinically relevant.

Deformation pattern and load transfer of an uncemented femoral stem with modular necks. An experimental study in human cadaver femurs.

BACKGROUND: Modular necks in hip arthroplasty allow variations in neck-shaft angles, neck version and neck lengths and have been introduced to improve accuracy when reconstructing the anatomy and hip joint biomechanics. Periprosthetic bone resorption may be a consequence of stress shielding in the proximal femur after implantation of a femoral stem. The purpose of this study was to investigate the deformation pattern and load transfer of an uncemented femoral stem coupled to different modular necks in human cadaver femurs. METHODS: A cementless femoral stem was implanted in twelve human cadaver femurs and tested in a hip simulator corresponding to single leg stance and stair climbing activity with patient-specific loading. The stems were tested with four different modular necks; long, short, retro and varus. The long neck was used as reference in statistical comparisons, as it can be considered the "standard" neck. The deformation of bone during loading was measured by strain gauge rosettes at three levels of the proximal femur on the medial, lateral and anterior side. FINDINGS: The cortical strains were overall reduced on the medial and lateral side of femur, for all implants tested, and in both loading conditions compared to the unoperated femur. Although there were statistical significant differences between the necks, the results did not show a consistent pattern considering which neck retained or lost most strain. In general the differences were small, with the highest significant difference between the necks of 3.23 percentage points. INTERPRETATION: The small differences of strain between the modular necks tested in this study are not expected to influence bone remodeling in the proximal femur.

Initial stability of an uncemented femoral stem with modular necks. An experimental study in human cadaver femurs.

BACKGROUND: Uncemented implants are dependent upon initial postoperative stability to gain bone ingrowth and secondary stability. The possibility to vary femoral offset and neck angles using modular necks in total hip arthroplasty increases the flexibility in the reconstruction of the geometry of the hip joint. The purpose of this study was to investigate and evaluate initial stability of an uncemented stem coupled to four different modular necks. METHODS: A cementless femoral stem was implanted in twelve human cadaver femurs and tested in a hip simulator with patient specific load for each patient corresponding to single leg stance and stair climbing activity. The stems were tested with four different modular necks; long, short, retro and varus. The long neck was used as reference in statistical comparisons. A micromotion jig was used to measure bone-implant movements, at two predefined levels. FINDINGS: A femoral stem coupled to a varus neck had the highest value of micromotion measured for stair climbing at the distal measurement level (60µm). The micromotions measured with varus and retro necks were significantly larger than motions observed with the reference modular neck, P<0.001. INTERPRETATION: The femoral stem evaluated in this study showed acceptable micromotion values for the investigated loading conditions when coupled to modular necks with different lengths, versions and neck-shaft angles.

Reliable classification of children's fractures according to the comprehensive classification of long bone fractures by Müller.

BACKGROUND AND PURPOSE: Guidelines for fracture treatment and evaluation require a valid classification. Classifications especially designed for children are available, but they might lead to reduced accuracy, considering the relative infrequency of childhood fractures in a general orthopedic department. We tested the reliability and accuracy of the Müller classification when used for long bone fractures in children. METHODS: We included all long bone fractures in children aged < 16 years who were treated in 2008 at the surgical ward of Stavanger University Hospital. 20 surgeons recorded 232 fractures. Datasets were generated for intra- and inter-rater analysis, as well as a reference dataset for accuracy calculations. We present proportion of agreement (PA) and kappa (K) statistics. RESULTS: For intra-rater analysis, overall agreement (κ) was 0.75 (95% CI: 0.68-0.81) and PA was 79%. For inter-rater assessment, K was 0.71 (95% CI: 0.61-0.80) and PA was 77%. Accuracy was estimated: κ = 0.72 (95% CI: 0.64-0.79) and PA = 76%. INTERPRETATION: The Müller classification (slightly adjusted for pediatric fractures) showed substantial to excellent accuracy among general orthopedic surgeons when applied to long bone fractures in children. However, separate knowledge about the child-specific fracture pattern, the maturity of the bone, and the degree of displacement must be considered when the treatment and the prognosis of the fractures are evaluated.

How reliable and accurate is the AO/OTA comprehensive classification for adult long-bone fractures?

BACKGROUND: Reliable classification of fractures is important for treatment allocation and study comparisons. The overall accuracy of scoring applied to a general population of fractures is little known. This study aimed to investigate the accuracy and reliability of the comprehensive Arbeitsgemeinschaft für Osteosynthesefragen/Orthopedic Trauma Association classification for adult long-bone fractures and identify factors associated with poor coding agreement. METHODS: Adults (>16 years) with long-bone fractures coded in a Fracture and Dislocation Registry at the Stavanger University Hospital during the fiscal year 2008 were included. An unblinded reference code dataset was generated for the overall accuracy assessment by two experienced orthopedic trauma surgeons. Blinded analysis of intrarater reliability was performed by rescoring and of interrater reliability by recoding of a randomly selected fracture sample. Proportion of agreement (PA) and kappa (κ) statistics are presented. Uni- and multivariate logistic regression analyses of factors predicting accuracy were performed. RESULTS: During the study period, 949 fractures were included and coded by 26 surgeons. For the intrarater analysis, overall agreements were κ = 0.67 (95% confidence interval [CI]: 0.64-0.70) and PA 69%. For interrater assessment, κ = 0.67 (95% CI: 0.62-0.72) and PA 69%. The accuracy of surgeons' blinded recoding was κ = 0.68 (95% CI: 0.65- 0.71) and PA 68%. Fracture type, frequency of the fracture, and segment fractured significantly influenced accuracy whereas the coder's experience did not. CONCLUSIONS: Both the reliability and accuracy of the comprehensive Arbeitsgemeinschaft für Osteosynthesefragen/Orthopedic Trauma Association classification for long-bone fractures ranged from substantial to excellent. Variations in coding accuracy seem to be related more to the fracture itself than the surgeon. LEVEL OF EVIDENCE: Diagnostic study, level I.