Single-centre study of hip fractures in Prague, Czech Republic, 1997-2007

Pathoanatomy of pertrochanteric fractures - a postmortem study

BACKGROUND

Recent pathoanatomic studies based on 3D CT reconstructions have questioned validity of AO/OTA classification because it does not reflect the reality and requires revision. These 3D CT studies, however, do not allow analysis of all details. Therefore, we have exploited the possibility to analyze the pathoanatomy of pertrochanteric fractures on postmortem specimens.

MATERIAL AND METHODS

From the collection of the Institute of Anatomy, the authors obtained 16 specimens of hip joints of individuals who had sustained a pertrochanteric fracture and died within 30 days of the injury, with anteroposterior radiographs of the injured hip available in all of them. The number of major fragments and their shape, and the courses of the main fracture lines were studied.

RESULTS

Three major fragments (a proximal head and neck fragment, a distal diaphyseal fragment and a posterior flat fragment), separated by three types of fracture lines (primary, secondary and tertiary lines) were identified. The primary line separated the proximal fragment (head and neck) from the distal diaphyseal fragment. The secondary fracture line separated the posterior flat fragment from the distal diaphyseal fragment. The tertiary fracture line split the posterior fragment into two parts. A key factor for fracture instability is the defect of the posterior cortex, which depends on the size and shape of the posterior fragment. Avulsion of the lesser trochanter and the adjacent cortex results in an unstable configuration of fracture lines on the medial side, while on the lateral side a large posterior fragment weakens the lateral trochanteric wall.

CONCLUSION

In agreement with recent CT studies, the findings of this pathoanatomical study change, in a number of aspects, the traditional view of the pathoanatomy and classification of pertrochanteric fractures, and introduces the concept of three, instead of the traditional four, main fragments.

Association of Brain Natriuretic Peptide Levels at Time of Injury with Morbidity and Mortality in Patients with Surgically Treated Hip Fractures

An elevated brain natriuretic peptide (BNP) level has been shown to be associated with mortality and cardiac events in cardiac surgery, but its utility in the prediction of morbidity and mortality in hip fracture surgery is unknown. The primary aim of this study was to determine if there is a difference in BNP level at the time of injury between patients who do and do not develop complications after hip fracture surgery. The secondary aim was to determine if there is a predictive relationship between complications associated with the initial BNP level and mortality.

Stochastic Strength Analyses of Screws for Femoral Neck Fractures

This paper represents a multidisciplinary approach to biomechanics (medicine engineering and mathematics) in the field of collum femoris fractures, i.e., of osteosyntheses with femoral/cancellous screws with full or cannulated cross-sections. It presents our new numerical model of femoral screws together with their stochastic (probabilistic, statistical) assessment. In the first part of this article, the new simple numerical model is presented. The model, based on the theory of planar (2D) beams on an elastic foundation and on 2nd-order theory, is characterized by rapid solution. Bending and compression loadings were used for derivation of a set of three 4th-order differential equations. Two examples (i.e., a stainless-steel cannulated femoral screw and full cross-section made of Ti6Al4V material) are presented, explained, and evaluated. In the screws, the internal shearing forces, internal normal forces, internal bending moments, displacement (deflections), slopes, and mechanical stresses are calculated using deterministic and stochastic approaches. For the stochastic approach and a “fully” probabilistic reliability assessment (which is a current trend in science), the simulation-based reliability assessment method, namely, the application of the direct Monte Carlo Method, using Anthill software, is applied. The probabilities of plastic deformations in femoral screws are calculated. Future developments, which could be associated with different configurations of cancellous screws, nonlinearities, experiments, and applications, are also proposed.

Reduced complication rates for unstable trochanteric fractures managed with third-generation nails: Gamma 3 nail versus PFNA

INTRODUCTION

Third-generation nails for the management of unstable trochanteric fractures were evaluated with regard to outcomes.

PATIENTS AND METHODS

A prospective observational study comparing the Gamma 3 nail and the Proximal Femoral Nail Antirotation (PFNA) in 106 unstable trochanteric fractures confirms the recently reported low intra- and postoperative complication rates from retrospective cohort studies.

RESULTS

Studies of same generations of both intramedullary nail systems did not reveal significant differences in intra- or postoperative complications. Intraoperative dislocation during nail insertion occurred 7 times for the Gamma nail and 9 times for the PFNA. The standard PFNA had to be exchanged intraoperatively for a shorter one on two occasions. Superficial wound healing disorders and hematoma requiring revision were observed in four patients in the Gamma 3 nail group and in three patients in the PFNA group. No deep infections were documented. Mechanical complications required revision in four patients (7.5%) after Gamma nailing and in two patients (3.8%) after PFNA. Postoperative rotation of the head-neck fragment was observed for the Gamma nail in three patients, not in the PFNA group. This was not statistically significant (p = 0.08). There were neither incidences of cut out without renewed trauma nor intraoperative fracture or postoperative femoral fracture. Nonunion affected 1 of 18 patients in late follow-up (p = 0.3) in the Gamma 3 nail group.

DISCUSSION

The Gamma 3 nail and the PFNA yielded comparable clinical results and significantly improved outcomes for unstable trochanteric fractures compared to older nail generations.

Strength Analyses of Screws for Femoral Neck Fractures

This article represents a multidisciplinary approach to biomechanics (engineering + medicine) in the field of “collum femoris” fractures. One possible treatment method for femoral neck fractures, especially for young people, is the application of cancellous (i.e. lag or femoral) screws (with full or cannulated cross-section) made of Ti6Al4V or stainless steel. This paper therefore aims to offer our own numerical model of cancellous screws together with an assessment of them. The new, simple numerical model presented here is derived together with inputs and boundary conditions and is characterized by rapid solution. The model is based on the theory of beams on an elastic foundation and on 2nd order theory (set of three differential 4th order equations, combination of pressure and bending stress-deformation states). It presents the process for calculating displacements, slopes, bending moments, stresses etc. Two examples (i.e. combinations of cancellous screws with full or cannulated cross-section made of stainless steel or Ti6Al4V material) are presented and evaluated (i.e. their displacement, slopes, bending moments, normal forces, shearing forces and stresses). Future developments and other applications are also proposed and mentioned.

Prolonged pre-operative hospital stay as a predictive factor for early outcomes and mortality after geriatric hip fracture surgery: a single institution open prospective cohort study

INTRODUCTION

The aim of this open prospective cohort study was to determine if a prolonged pre-operative hospital stay is a true predictor of higher morbidity or mortality in geriatric patients with hip fractures.

MATERIALS AND METHODS

We analysed early outcome parameters, such as functional independence measure (FIM), at discharge and four months post-operatively, peri-operative nonsurgical complications, intra-hospital and one year mortality compared with prolonged pre-operative hospital stay in 308 patients from a continuous cohort of 344.

RESULTS

Average pre-operative stay was 8.39 ± 5.80 days. Delaying surgery for > 72 hours was independently predictive for general complications and lower motor FIM gain at four months. All findings worsen progressively after the fifth day of delay. Pre-operative period was not found to be an independent predictor of mortality.

CONCLUSION

In all observed outcome parameters except mortality, pre-operative delay > 72 hours was shown to be a true predictive factor.

The importance of intramedullary hip nail positioning during implantation for stable pertrochanteric fractures: biomechanical analysis

PURPOSE

Proximal femoral fractures are among the most commonly sustained fractures. The current treatment of stable proximal femoral fractures located in trochanteric region primarily involves the use of two systems: extramedullary dynamic hip screws and intramedullary hip nails. Given that these fractures are mainly found in the elderly population, the necessity of a repeat, due to failure of the first, may jeopardize the patient's life. Decisive factors contributing to the healing of a fracture (or the failure thereof) include fracture pattern, technical implementation of the operation (i.e., position of the implant), implant's properties and its changes in relation to the surrounding bone tissue during loading. Each screw insertion variant results in damage to various load-bearing bone structures, which can be expected to influence healing quality and stability of newly formed bone.

METHOD

With the aid of a numerical model and finite element methods, the authors analyzed several different positions of IMHN/PFH-nails in the proximal femur, with the objective of determining positions with an increased risk of failure.

RESULTS AND CONCLUSION

In model situations, it has been shown that in stable fractures results do not depend on absolutely precise positioning and small deflections in the nails and neck screws positions do not significantly increase the risk of failure for the entire fixation. Damage to load-bearing structures relative to various implant placements does not impact the resultant overall fixation stability. Therefore, it is not necessary to re-introduce implants in the ideal position, which can lead to reduced patient radiation doses during surgery.

DXA and pQCT predict pertrochanteric and not femoral neck fracture load in a human side-impact fracture model

The validity of dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) measurements as predictors of pertrochanteric and femoral neck fracture loads was compared in an experimental simulation of a fall on the greater trochanter. 65 proximal femora were harvested from patients at autopsy. All specimens were scanned with use of DXA for areal bone mineral density and pQCT for volumetric densities at selected sites of the proximal femur. A three-point bending test simulating a side-impact was performed to determine fracture load and resulted in 16 femoral neck and 49 pertrochanteric fractures. Regression analysis revealed that DXA BMD trochanter was the best variable at predicting fracture load of pertrochanteric fractures with an adjusted R(2) of 0.824 (p < 0.0001). There was no correlation between densitometric parameters and the fracture load of femoral neck fractures. A significant correlation further was found between body weight, height, femoral head diameter, and neck length on the one side and fracture load on the other side, irrespective of the fracture type. Clinically, the DXA BMD trochanter should be favored and integrated routinely as well as biometric and geometric parameters, particularly in elderly people with known osteoporosis at risk for falls.

Predicting discharge location of hip fracture patients; the new discharge of hip fracture patients score

Purpose

This paper reports on the development and validity of a new instrument, called the discharge of hip fracture patients score (DHP), that predicts at admission the discharge location in patients living in their own home prior to hip fracture surgery.

Methods

A total of 310 patients aged 50 years and above were included. Risk factors for discharge to an alternative location (DAL) were analysed with a multivariable regression analysis taking the admission variables into account with different weights based on the estimates. The score ranged from 0–100 points. The cut-off point for DAL was calculated using a ROC analysis. Reliability of the DHP was evaluated.

Results

Risk factors for DAL were higher age, female gender, dementia, absence of a partner and a limited level of mobility. The cut-off point was set at 30 points, with a sensitivity of 83.8%, a specificity of 64.7% and positive predictive value of 79.2%.

Conclusion

The DHP is a valid, simple and short instrument to be used at admission to predict discharge location of hip fracture patients.