University of Groningen
Grip on prognostic factors after forearm fractures
Ploegmakers, Joris Jan Willem
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Grip on prognostic factors
after forearm fractures
Financial support for the publication of this thesis was provided by:
Anna Fonds NOREF
Nederlandse Orthopaedische Vereniging Research Institute SHARE
University Medical Center Groningen / Rijksuniversiteit Groningen ImplantCast
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Oudshoorn Chirurgische Techniek DePuy Synthes
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© 2019, Joris J.W. Ploegmakers, Groningen, the Netherlands. All rights reserved. No part of this thesis may be reproduced or transmitted in any form or by any means without the prior permission of the copyright owner.
ter verkrijging van de graad van doctor aan de Rijksuniversiteit Groningen
op gezag van de
rector magnificus prof. dr. E. Sterken en volgens besluit van het College voor Promoties.
De openbare verdediging zal plaatsvinden op 20 februari 2019 om 14:30
door
Joris Jan Willem Ploegmakers
geboren op 27 juni 1976 te Mill en Sint Hubert
Grip on prognostic factors
after forearm fractures
Promotor Prof. dr. S.K. Bulstra Copromotores Dr. C.C.P.M. Verheyen Dr. B. The Beoordelingscommissie Prof. dr. R.M. Castelein Prof. dr. D. Eygendaal Prof. dr. C.K. van der Sluis
CONTENTS
Chapter 1
General introduction and aims
Classifying forearm fractures
Chapter 2
Four distal radial fracture classifications tested among a large panel of Dutch trauma surgeons
Normal forearm function represented in normative isokinetic strength measurements
Chapter 3
Grip strength is strongly associated with height, weight and gender in childhood: a cross sectional study of 2241 children and adolescents providing reference values Chapter 4
The influence of hand preference on grip strength in children and adolescents; a cross-sectional study of 2284 children and adolescents
Chapter 5
Normative torque and grip strength profiles with variation in forearm rotation
Isokinetic pronation and supination strength measurements after forearm injury
Chapter 6
The effect of a Galeazzi fracture on the strength of pronation and supination two years after surgical treatment
Chapter 7
Supination and pronation strength deficits persist at 2-4 years after treatment of distal radius fractures
9 19 31 47 63 79 93
105 119 135 151 165 173 181 187 193
Predicting outcome after paediatric forearm fractures
Chapter 8
Acceptance of angulation in the non-operative treatment of paediatric forearm fractures
Chapter 9
The evolution of hand function during remodelling in non-reduced angulated pediatric forearm fractures
Chapter 10
Predictors for losing reduction after reposition in conservative treated both-bone forearm fractures in 38 children
Chapter 11 General discussion Summary Samenvatting Dankwoord CV
Chapter 1
General introduction and aims
Introduction
Forearm fractures account for a substantial proportion of presented trauma on emergency departments worldwide, representing an estimated 16% of all fractures.1-3 Of all upper limb fractures in children 20-33% are localized in the forearm.4-7 Overall forearm fractures are, in prevalence, the most common fractures.8 A close analysis of these long bone injuries shows that the distribution is sex- and age-specific, depending on different characteristics.
Biology
On a histological level bone has a unique age-specific skeletal property.9-15 The unique juvenile properties of bone fade when epiphyseal growth plates (physes) start to ossify in the adolescent. The absorption of energy in the juvenile bone, before the physis starts to ossify, results in a biomechanical situation that is distinct from that in the adult. This can be attributed to differences in osseal composition (less mineralized, high in collagen but a less dense matrix with high cellularity) and differences in osseal structure (highly vascularized and spongious) compared to adults. The juvenile forearm has a firm periosteal sleeve containing the bone, and a weak unique epiphyseal growth plate. This thicker periosteal sleeve in the immature skeleton has a distinct effect not just on impact absorption during injury but also on healing.9-11 Even after a malunited fracture, the juvenile bone has the potency to correct and remodel.9-21 Hence certain fracture malalignment in children can be accepted, which could not be the case in the adult situation. All of these different biological properties make the juvenile bone, during its growth period, absorb energy during trauma in a manner that is very different compared to the adult bone. This results in treatment of paediatric fractures determined by juvenile pathophysiology rather than adult.
Incidence
A second observation is that lifestyle differences between the sexes during the course of time influence forearm fractures. Generally speaking, there are three peaks in incidence. The first is during childhood when there is a peak of forearm trauma at the age of 5-14 years (with a slight predilection for boys), there is another later in life in adult males under the age of 50 years, followed by an increase in females sustaining especially wrist fractures over the age of 40 years.22, 23 The activity level and biological hormonal differences between young adult and geriatric bone, periosteum, and muscles seem to influence the statistics and incidence, thereby influencing the type of fracture.22 In the 5-14 year age group, trauma is inflicted mostly by a fall on an outstretched hand and not by a high impact, although motor vehicle injuries in children have increased. The fractures in the adult male group are caused by a high-energy impact due to injury, caused by traffic or sports, which results in an increased incidence of intra-articular fractures. In the elderly female population, decreased bone mass and density causes the forearm to be at risk for extra-articular fractures when sustaining a fall.
History
The fact that forearm fractures are so common throughout all ages explains why there is a lot of literature concerning their diagnoses and treatment. The risk of fracturing the radius was significantly increased by the transition to bipedal ambulation. Treatment of radius fractures predates the written word as reports of splinting techniques for wrist fractures have been dated back to 5000 years ago in ancient Egyptian hieroglyphics.24 Around 400 BC, notes were
found from Hippocrates describing treatment of forearm fractures and dislocations by manual reduction and bandaging.25
After Abraham Colles and Guillaume Dupuytren had published their insight into the treatment modality of radius fractures, treatment changed little - even with the introduction of plaster of Paris (1850). Physicians struggled to diagnose fractures, although they also realised the existence of different patterns of fracture. A few tried to categorise them to point out the importance of prognosis during (different) treatment regimes. Hence eponyms followed from the pioneers, who first observed, described and published common fracture types. These typical fractures were coupled to a treatment or sometimes a warning for prognostically unfavourable results at a time when there were no radiographs (Pouteau1783, Colles1814, Monteggia1814, Cooper1826, Dupuytren1832, Hutchinson18, Barton1838, Goyrand1832, Smith1847), and even when there were (Galeazzi1934, Essex-Lopresti1951, Hume1957).
In the second part of the nineteenth century, x-ray became available for diagnostic purposes. From that time adequate fracture diagnosis could be made, resulting in the publication of large numbers of papers based on radiographic diagnoses (although also based on anatomical dissections and experiments) to assess the different trauma types and fracture patterns, which were described using eponyms. These eponyms could be considered as the predecessors of later classifications. Whilst the eponyms still serve a certain purpose, it became clear that a more detailed and structured distinction, even within the same injury type, was needed to try to understand the differences in outcome between patients, and to perhaps guide treatment in an individually tailored manner.
Classifications
Classically, classifications serve the purpose of processing radial fracture into universal medical code. However the usefulness, and more importantly the aim, depends on how practically a classification can be used. Ideally, it should be practical in use, analytic, reliable (intra-observer reliability and intra-observer variability) and discriminate in treatment and prognosis. Practically, a classification should yield a platform for communication research, give direction to a clinician to make a thorough treatment decision, and provide information to the patient with a reliable rehabilitation phase and treatment outcome.
About 27 different distal forearm fracture classifications have been developed. Most of them give an understanding of the trauma mechanism with a treatment advice, some stress a detail or feature of the fracture from a specialist point of view, and others have been built systematically. These different characteristics lead to different outcomes, for example a systematic classification is often easy to use, and could therefore improve variability. However not all fracture types can be posted in this classification and there is no clear treatment direction, which can predict rehabilitation or prognosis.
Hence Kreder’s statement/proclamation: “In general we feel that treatment should be based on sound basic principles of fracture care and anatomy as well as consideration of the patient and his circumstances, rather than relying on a specific fracture classification system”.26 On the other hand, a classification that is based on a specific trauma mechanism is often too complex, resulting in increased inter-observer variability and intra-observer reliability.
Apparently the variation in forearm fractures is complex, making it a difficult subject to contain in a universal classification that provides satisfactory guidance for treatment and predicted prognosis.27
Function
The restoration of function after a fracture is clearly the most important outcome parameter. Measuring grip strength is historically considered to be a reliable functional score that represents gross forearm function and there is reasonable evidence in adults to support this.28 Grip strength has been used extensively as a parameter in the assessment of hand function, as both neuromuscular and generalized bone diseases directly affect it. It has been used as an indicator in the evaluation of patients with a large variety of pathologies that impair the upper extremities, including rheumatoid arthritis, osteoarthritis, muscle dystrophy, tenosynovitis, strokes, and congenital malformations.28-34
Grip strength measurements also have an established role in determining treatment efficiency, for example in the evaluation of different wrist orthoses, the effect of hand exercises in rheumatoid arthritis, and recovery after trauma.35-40 Finally, grip strength measurements are used as outcome parameters in many different surgical interventions.35, 38-40 Grip strength measurements provide a well-established and objective score, reflecting mobility of different wrist joints and therefore function of the hand and are easily and quickly obtainable by a range of different professionals.41-47 These measurements of the post-injured forearm are usually compared with the contralateral side as best comparable parameter, although normative data can be used as an important indicator as well. Comparison to normative data is important when making statements about specific patient groups or treatment regimes. Obtaining normative data for grip strength in adults has been the subject of many studies; results are widely available from investigations when the forearm is positioned in the neutral position, and also from those related to hand-dominance.48 For grip strength in children and in different forearm positions in adults there remains a lacuna in data.49-51
The situation for grip strength in children is different compared to that in adults. Although more or less the same structures are being stressed in normal use, ligament injury is usually less of a problem in children and more common in adult forearm fractures. Therefore grip strength in the neutral position gives a good indication of general hand function after forearm trauma in children. However during pronation and supination of the forearm, different anatomic structures become taut or relaxed, so measurement of grip strength in a neutral position would miss these problems in adults.50-54 In other words, testing the forearm in only a neutral position would not stress specific ligament injuries and therefore would not adequately test function. The same applies for pronation and supination strength measurements in only the neutral position. In different pronation and supination positions, different ligaments are taut and relaxed and different muscles are being used. Therefore pronation and supination tests in different forearm positions are more specific and complementary when examining ligament and muscular injury in the forearm after injury.
Remodelling in children
Forearm fractures in adults encompass intra-articular structures and firm ligament complexes as part of a complex injury, which eventually are predictive for the traumatised limb’s function. In children most fractures involve the epiphyseal and diaphyseal bone.55-59 and therefore prognosis of function depends merely on growth and the remodelling capacity of bone.9-10, 13, 15, 16, 20, 21 Fractures, especially of the long bones, can correct if malaligned and remodel during time because of the child’s growth potential executed by the growth plate (physis). The compensatory
remodelling capacity is influenced by both intrinsic and extrinsic factors. Important intrinsic factors include the remaining growth period, which is influenced by sex. Boys tend to have a more or less 2 year longer growth period than girls. The proximity of the fracture to the epiphyseal growth plate, and apparently the thick periosteal sleeve in the immature skeleton have a distinct effect on injury healing.
Extrinsic factors for remodelling are the amount of angular deformation and the direction of deformation in relation to the plane of movement, e.g. a rotational deformity or the presence of complete fracture displacement.60, 61
During healing there is a very complex system of mechanotransduction, a process through which forces or other mechanical signals are converted to biomechanical signals and are transduced to a cellular response.9-10 Without attempting to completely understand the intricacies of such a highly complex regulatory system, we do need to gain clinical insight to know when to call an angular deformation acceptable and when not.
Scope, objective and goal of the thesis
The scope of this thesis encompasses predicting functional recovery after forearm fracture. The objective is to obtain data for evaluating the forearm as such, focused on radiographs and kinematic tests as tools for prognosis. Therefore the reliability of radiographic forearm fracture classifications is tested and the acceptable angular deformation for a conservative treatment is studied, making use of international literature and empiric data. Data on normative grip strength and pronation-supination strength in different positions are obtained using dynamometer tests to evaluate normal forearm function.
The final goal is to use this information from radiographs (classification and acceptable angular deformation), and normative kinematic data (grip strength and pronation-supination strength) to predict functional outcome during rehabilitation after sustained forearm fracture.
General outline summary
Although there are many radiological classification systems for forearm fractures, it remains unclear which of these systems are most reliable and reproducible. Therefore in this thesis we selected four of the most popular classification systems and measured the inter-observer variability and the intra-observer reliability/reproducibility. (Chapter 2)
Grip strength is regarded as a reliable and objective score for forearm function in adults.54, 62-64 Because fracture of the forearm in children generally does not affect the ligamentous structures, grip strength measured in neutral rotation of the forearm is regarded as a useful tool to test the gross forearm function. To sample normative grip strength values for children, we studied a Dutch cohort of normal healthy children, measuring grip strength in relation to sex, height and weight. The primary aim of this study was to provide reference values for grip strength in children and to present this data in a graphical representation that allows easy comparison. (Chapter 3)
In the literature it is suggested that factors such as hand dominance, sex and age might influence grip strength in children.44, 46, 65-67 No quantitative data are available however. Therefore in this study, a multivariate analysis was performed to quantify differences in grip strength due to differences in hand dominance, sex and age. It was found that age-related changes in strength between sex exist and that strength differences vary between left- and right-handed children. As mentioned before, grip strength measured in a neutral position is regarded as a useful tool to
observe forearm function after forearm fractures (without ligamentous disruption). (Chapter 4) Because ligamentous disruption occurs in adults sustaining a forearm fracture, but rarely in children (Monteggia), it is of interest to measure grip strength not only in a neutral forearm position after adults fractured their forearm. Different ligament complexes can only be tested when they are taut, which is in specific forearm positions (pro- and supination of the forearm). In order to get normative values for grip strength in pro- and supination we therefore measured in this study grip strength in pro- and supination positions. (Chapter 5)
Using the selected radiological classification system from Chapter 2, patients were identified who had sustained a forearm fracture in correlation with ligamentous injury. With this selected fracture with ligament injury, the hypothesis was to identify by kinematic testing in different positions the functional deficit when the injured ligament would give way compared to the normative data from Chapter 5. This would be of value and give possibilities for a reliable predicted initial outcome and prognosis after a forearm fracture.
Two adult forearm fracture dislocation injuries were selected, notorious for instability in the distal radial ulnar joint, and compared with the normative data. The prognostic value and functional results after a Galeazzi’s dislocation fracture cohort are described in Chapter 6, the results of a cohort of Frykman’s type two fractures are described in Chapter 7.
The goal of another study was to clarify the extent of angulation that can be accepted and thus for which fractures conservative treatment without reposition can be accepted. The results show that multiple factors have to be taken into account, such as gender, age, apposition, etc. Therefore no clear uniform border for acceptance of angulation can be given for these type of fractures (Chapter 8). Using criteria and advice from experts and literature from chapter eight, combined with the normative grip strength data in children, the angular deformity and forearm function was measured prospectively in time in Chapter 9.
Loss of position in the conservatively treated and not reduced forearm fracture in children is a considerable risk. The effect of accepted alignment loss after comminutive treatment may have considerable impact on the function of the forearm. In this chapter we studied two groups of patients with forearm fractures with the same initial angular deformity who were treated conservatively. In one group the initial position was maintained and in the other group the initial alignment was lost. In order to predict reduction loss, radiological parameters were postulated which a priori have a negative influence on stability. (Chapter 10)
Closing statement
The subject of this thesis represents the vision of our Orthopaedic Department in the University Medical Centre on the subject of healthy ageing and developing. Our approach, besides the classical approach of treatment and cure, is a concept representing prevention and education in health and quality of life with regard to function and mobility.
As such the thesis forms part of a broader Public Health Research (PHR) program, which contributes research on the prediction and (early) detection of adverse health and disease, and on social participation in case of health problems. These research themes are part of the broader areas of prevention and societal participation, that is, of core domains of public health. They are also pivotal parts of the mission of the Research Institute SHARE and of the University Medical Center Groningen.
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Joris J.W. Ploegmakers Konrad Mader Dietmar Pennig Kees C.P.M. Verheyen Injury 2007;38:1268-72
Chapter 2
Four distal radial fracture classifications tested among a large
panel of Dutch trauma surgeons
ABSTRACT
Forty-five observers (trauma surgeons and residents) classified five different radiographs of distal radial fractures according to the AO/ASIF, Frykman, Fernandez and Older classifications. Four months later, the same panel classified the same radiographs in a different order. Mean interobserver correlation for all cases was fair to moderate according to the Spearman rank test. However, these classifications showed poor correlation with the gold standard as classified by the senior author (DP).
All intraobserver agreements were demonstrated a moderate Kappa agreement (K w = 0.52) for the AO/ASIF classification and fair for the Frykman (K w = 0.26), Fernandez (K w = 0.24) and Older (K w = 0.27) classifications. When the group was divided based on years of clinical experience (< 6 years; ≥ 6 years), there was a poor correlation between experience and consistency among all four classifications. Based on these findings, we do not recommend use of these classifications for clinical application because of their questionable reproducibility and reliability.
INTRODUCTION
Classification systems have been developed to gain greater insight into trauma mechanism, treatment and prognosis of distal radial fractures. The international literature describes about twenty different classification systems for wrist fractures. We selected popular classifications with different rationales. In the literature, small panels have categorised many radiographs with one or several classification systems at different points in time, in order to establish reliability and reproducibility of these classifications (Andersen et al., 1991,Kreder et al., 1996,Andersen et al., 1996,Flikkila et al., 1998,Illarramendi et al., 1998,Oskam et al., 2001).The goal of the present study was to achieve insight into reliability and agreement with a digital questionnaire for four classifications – AO (Johnstone et al., 1993, Kreder et al., 1996 (Johnstone et al., 1993,Kreder et al., 1996,Flikkila et al., 1998,Illarramendi et al., 1998), Frykman (Frykman, 1967), Older (Andersen et al., 1991) and Fernandez (Fernandez, 1993)) – with a large panel and few radiographs on two occasions. In DiRECT (Distal Radial fracture Electronic Classification Trial), both interobserver and intraobserver reproducibility was scored.
MATERIAL AND METHODS
After obtaining authorisation from both Dutch trauma societies boards (Nederlandse Vereniging voor Traumatologie (NVT) for general surgeons and Nederlandse Vereniging voor Orthopaedische Traumatologie (NVOT) for orthopaedic surgeons), we invited their members to link voluntarily onto our website and participate in the trial. All members were informed in the thesis of our research and supplied with the website address and an entry code. Four months later, all 625 + 404 members were asked to participate again and complete the classification part for the second time, but now in a different order. While there was a voluntarily participation of members of both trauma societies and to prevent preliminary ending of participants of the questionnaires we used five cases.
The internet website for DiRECT was constructed, and consisted of two sections: · Personal data: discipline, affiliation, years of clinical trauma experience.
· Radiographs: five sets (anteroposterior and lateral view) of distal radial fractures as selected by the senior author (DP). The objective was to ensure full representation of the spectrum of distal radial fractures. For each of the five cases the participant was asked to classify the fracture. Each classification was illustrated in words and a diagram (figure 1).
Answers were given by marking the box adjacent to the illustration that represented the correct classification according to the observer. An option was also provided to correct a score. In total, 20 responses were requested.
After approval was obtained from the other authors, the scores selected by the senior author (DP) constituted the gold standard.
Statistics
Intraobserver reproducibility for individual cases and all cases collectively was tested with Cohen Kappa statistics (Landis and Koch, 1977a,Landis and Koch, 1977b). Poor generation of only matching values of variables precluded the use of Kappa statistics in our study (Landis and Koch, 1977a,Landis and Koch, 1977b). Kappa is a measurement used for determining the level of agreement in categorical variables corrected for chance. We defined the kappa results as <0.20 poor, 0.21-0.40 fair, 0.41-0.60 moderate, 0.61-0.80 good and 0.81-1.00 very good (Landis and Koch, 1977a,Landis and Koch, 1977b).
Pearson correlation coefficients were used to test the interobserver reliability. Next, the inter-observer relationship between the classifications scored by experienced (≥6 years of clinical practice) and less experienced observers (<6 years of clinical practice) was determined. Spearman correlation coefficients were used for establishing between-groups relationships and relationships between the experienced or less experienced group and classifications based on our gold standard as established by the senior investigator (DP). Compliance with test assumptions was checked, and when no normal distribution of data was observed, either parametric (relying on the central limit theorem when appropriate) or non- parametric testing was performed. All tests were conducted two-tailed with a 0.05 level of significance.
Figure 1. Example of one of the five cases with one of the classifications systems (Older, yet unanswered) as
used on the internet website DiRECT.
Nondisplaced
• Loss of some volar angulation and up to 5° of dorsal angulation. • No significant shortening 2 mm or more above the distal radius.
Displaced with minimal
comminution
• Loss of volar angulation or dorsal displacement of distal fragment. • Shortening usually not below the distal ulna but occasionally up to 3mm below it.
• Minimal comminution of the dorsal radius
Displaced with comminution of the dorsal radius.
• Comminution of the distal radius. • Shortening usually below the distal ulna.
• Comminution of the distal radius fragment usually not marked and often characterised by large pieces.
Displaced with severe
comminution of the radial head
• Marked comminution of the dorsal radius.
• Comminution of the distal radial fragment shattered.
• Shortening usually 2-8mm below the distal ulna.
• Poor volar cortex in some cases. Older 1
Older 2
Older 3
Older 4
Figure 1. Example of one of the five cases with one of the classifications systems (Older, yet unanswered) as
used on the internet website DiRECT.
Nondisplaced
• Loss of some volar angulation and up to 5° of dorsal angulation. • No significant shortening 2 mm or more above the distal radius.
Displaced with minimal
comminution
• Loss of volar angulation or dorsal displacement of distal fragment. • Shortening usually not below the distal ulna but occasionally up to 3mm below it.
• Minimal comminution of the dorsal radius
Displaced with comminution of the dorsal radius.
• Comminution of the distal radius. • Shortening usually below the distal ulna.
• Comminution of the distal radius fragment usually not marked and often characterised by large pieces.
Displaced with severe
comminution of the radial head
• Marked comminution of the dorsal radius.
• Comminution of the distal radial fragment shattered.
• Shortening usually 2-8mm below the distal ulna.
• Poor volar cortex in some cases. Older 1
Older 2
Older 3
RESULTS
The five sets of selected radiographs were reviewed twice with a four-month interval by 45 observers. Of the 450 (45 x 5 x 2) classified fractures of the AO/ASIF, Frykman, Fernandez and Older classifications, mean correspondence with the final consensus (the gold standard) appeared in only 55 fractures for the AO/ASIF classification main group, 45 for Fernandez, 45 for Frykman and 45 for Older.
The weighted Kappa values for intraobserver reproducibility were 0.52 for the AO/ASIF classification, 0.26 for Frykman, 0.42 for Fernandez and 0.27 for Older (Table 1). These data represent an overall agreement between two measurements in time, from ‘poor’ to ‘fair’ (Fleiss J.L., 1981). There is a modest precision of measurements, resulting in rather wide reliability intervals.
Intraobserver correlation between our internet and gold standard scores lacked significance for all classifications in both measurement rounds, with only one exception for the Frykman classification in round two (Table 2).
Table 1. Weighted Kappa values for intraobserver agreement of four distal radial fracture classification systems.
Value Classification
AO/ASIF Frykman Fernandez Older
Weighted kappa 0.52 0.26 0.42 0.27
Confidence interval 0.37-0.63 Not calculable 0.20-0.58 Not calculable
Number 243 161 238 237
Table 2. Pearson correlation coefficient for intraobserver reliability of four distal radial fracture classification
systems.
AO / ASIF first measurement 0.23 0.00 500
AO / ASIF second measurement* 0.14 0.00 554
Frykman first measurement 0.13 0.00 497
Frykman second measurement* 0.03 0.43 547
Fernandez first measurement 0.28 0.00 494
Fernandes second measurement* 0.21 0.00 546
Older first measurement -0.22 0.00 492
Older second measurement* -0.19 0.00 546
Classification Values
Pearson correlation coefficient p-value number of participants
Dividing the observers in two groups based on years of experience, a Spearman correlation coefficient was calculated for all five classified cases to determine interobserver reliability. This correlation was poor but statistically significant for scores between observers (Figure 2) and between observer and our gold standard (Table 3).
Table 3. Spearman rank correlation coefficient with p-value for interobserver reliability of four distal radial
fracture classification systems
Group 1: responders < 6 yr. clinical experience; group 2, responders ≥ 6 yr .clinical experience; GS, Gold standard; vs, versus.
* Second round of observations made 4 months after first round.
AO 0.10 (0.04) 0.10 (0.05) 0.08 (0.06) 0.10 (0.15) 0.12 (0.05) 0.10 (0.08) Fernandez 0.16 (0.00) 0.16 (0.00) 0.13 (0.02) 0.14 (0.03) 0.07 (0.06) 0.10 (0.03) Frykman 0.10 (0.05) 0.13 (0.01) 0.09 (0.09) 0.06 (0.10) 0.05 (0.31) 0.05 (0.41) Older 0.15 (0.00) 0.20 (0.00) -0.08 (0.31) -0.72 (0.20) -0.08 (0.10) -0.11 (0.12) Classification Group 1 vs Group 2 Round 1 Round 2*
DISCUSSION
Confirming the results of previous studies, (Andersen et al., 1991), (Kreder et al., 1996), (Illarra-mendi et al., 1998,Oskam et al., 2001) {Oskam, Kingma, et al. 2001 66 /id}our Kappa values for intraobserver agreement were also relatively low but consisted out of a full range of most popular classification systems for distal radial fractures (Table 4).
The AO/ASIF classification seems to be the most reliable; by limiting the number of subgroups, its reliability could probably be enhanced, diminishing the intended precision of the classification. The fact that we consulted clinical trauma physicians and not only specialists with a vast experience with the tested classifications (Kreder et al., 1996) could explain the apparently poor intraobserver and interobserver reproducibility of the four classifications. Still, in our opinion it reflects best on those physicians who commonly use the classification systems of communication and indication for choice of treatment.
All data indicate there is poor correlation, neither for intraobserver or interobserver reproducibility nor for level of experience, which makes using one of the four tested classifications for distal radial fractures virtually unsuitable for daily practise. This statement is also supported by literature (Kreder et al., 1996,Andersen et al., 1996,Flikkila et al., 1998,Illarramendi et al., 1998).
Certain limitations of our study are the few cases we tested by the (large) panel. We choose the number of five cases intentionally as we anticipated this to the maximum to be “tolerated” by the physicians as to completing the survey completely. But by using five cases we did not test the whole spectrum of each classification what could have a negative effect on the Kappa for interobserver reliability but should not influence intraobserver variability. Using only a moderate amount of cases could give a Kappa bias in case of a “borderline” fracture for a certain classification. Certain fracture patterns could well (dis)favour one or several of the tested classification systems. As our results indicate a fairly regular distribution of interobserver scores over each case and classification system (Figure 2) the assumption probably is not applicable on our data.
We conclude that these classifications do not suffice for individual communication-related use in daily practice. For research purposes, the best classification to evaluate fractures would be the AO/ASIF.
Table 4. Intraobserver Kappa values reported in the literature and used classification, with numbers of
observers and cases.
DiRECT, Distal Radial fracture Electronic Classification Trial. Andersen et al., 1996 4 55 0.57-0.70 Kreder et al., 1996 36 30 0.75 Illarramendi et al., 1998 6 200 0.57 0.61 Oskamp et al., 2001 2 124 0.56 Andersen et al., 1991c 4 185 0.75 DiRECT 45 5 0.52 0.26 0.42 0.27
Report Number Classification system
Figure 2. Interobserver scores for individual cases and each classification separately. 1 2 3 4 120 100 80 60 40 20 0
case 1 case 2 case 3 case 4 case 5
120 100 80 60 40 20 0 160 140 120 100 80 60 40 20 0 140 120 100 80 60 40 20 0 1 2 3 4 5 1 2 3 4 5 6 7 8 A A A B B B C C C 1 2 3 1 2 3 1 2 3 AO/ASIF classification Frykman classification Fernandez classification Older classification Responders
ACKNOWLEDGEMENT
REFERENCES
1. Andersen D J, Blair W F, Steyers C M, Jr., Adams B D, el Khouri G Y, Brandser E A. Classification of distal radius fractures: an analysis of interobserver reliability and intraobserver reproducibility. J Hand Surg [Am ] 1996; (21): 574-582.
2. Andersen G R, Rasmussen J B, Dahl B, Solgaard S. Older’s classification of Colles’ fractures. Good intraobserver and interobserver reproducibility in 185 cases. Acta Orthop Scand 1991; (62): 463-464. 3. Fernandez D L. Fractures of the distal radius: operative treatment. Instr Course Lect 1993; (42): 73-88. 4. Fleiss J.L. Statistical Methods for Rates and Proportions. John Wiley & Sons, New York 1981.
5. Flikkila T, Nikkola-Sihto A, Kaarela O, Paakko E, Raatikainen T. Poor interobserver reliability of AO classification of fractures of the distal radius. Additional computed tomography is of minor value. J Bone Joint Surg Br 1998; (80): 670-672.
6. Frykman G. Fracture of the distal radius including sequelae--shoulder-hand-finger syndrome, disturbance in the distal radio-ulnar joint and impairment of nerve function. A clinical and experimental study. Acta Orthop Scand 1967;Suppl. 108: 1-155
7. Illarramendi A, Gonzalez D, V, Segal E, De Carli P, Maignon G, Gallucci G. Evaluation of simplified Frykman and AO classifications of fractures of the distal radius. Assessment of interobserver and intraobserver agreement. Int Orthop 1998; (22): 111-115.
8. Johnstone D J, Radford W J, Parnell E J. Interobserver variation using the AO/ASIF classification of long bone fractures. Injury 1993; (24): 163-165.
9. Kreder H J, Hanel D P, McKee M, Jupiter J, McGillivary G, Swiontkowski M F. Consistency of AO fracture classification for the distal radius. J Bone Joint Surg Br 1996; (78): 726-731.
10. Landis J R, Koch G G. An application of hierarchical kappa-type statistics in the assessment. Biometrics 1977a; (33): 363-374.
11. Landis J R, Koch G G. The measurement of observer agreement for categorical data. Biometrics 1977b; (33): 159-174.
12. Oskam J, Kingma J, Klasen H J. Interrater reliability for the basic categories of the AO/ASIF’s system as a frame of reference for classifying distal radial fractures. Percept Mot Skills 2001; (92): 589-594.
J.J.W. Ploegmakers A.M. Hepping J.H.B. Geertzen S.K. Bulstra M. Stevens Journal of Physiotherapy 2013;59: 255-26
Chapter 3
Grip strength is strongly associated with height, weight and
gender in childhood:
A cross sectional study of 2241 children and adolescents
providing reference values
ABSTRACT
Question: What are reference values for grip strength in children and adolescents based on a
large and heterogeneous study population? What is the association of grip strength with age, gender, weight and height in this population?
Design: Cross-sectional study.
Participants: Participants were recruited from schools in the northern provinces of the
Netherlands. The study included healthy children and adolescents ranging in age from 4 to 15 years.
Outcome measures: All children had their height (cm) and weight (kg) measured and were
allowed a total of four attempts using the Jamar® hand dynamometer: twice with each hand. Grip strength scores (kg) were recorded for the dominant and non-dominant hands.
Results: The study population comprised 2241 children and adolescents. Reference values
for both genders are provided according to age and dominance. Grip strength shows a linear and parallel progression for both genders until the age of 11 or 12, after which grip strength development shows an acceleration that is more prominent in boys.
Conclusion: There is a significant difference in grip strength with each ascending year of age
in favor of the older group, as well as a trend for boys to be stronger than girls in all age groups between 4 and 15 years. Weight and especially height have a strong correlation with grip strength in children.
INTRODUCTION
Grip strength is used extensively in the assessment of hand function. Because it is directly affected by the neural, muscular and skeletal systems, grip strength is used in the evaluation of patients with a large range of pathologies that impair the upper extremities, including rheumatoid arthritis, osteoarthritis, muscular dystrophy, tenosynovitis, stroke, and congenital malformations. Grip strength measurements also have an established role in determining treatment efficacy, such as in the evaluation of different wrist orthoses, the effect of hand exercises in rheumatoid arthritis, and recovery after trauma. Also, they are used as an outcome measure after many different surgical interventions. Grip strength measurements provide a well established and objective score that is reflective of hand function and that is easily and quickly obtainable by a range of different health professionals.
Since comparison to normative data is important when making statements about specific patient groups or treatments, obtaining normative data for grip strength in adults has been the subject of many studies. In contrast, normative data for children is far less readily available. To identify studies on this topic we searched PubMed, MEDLINE and Embase using combinations of the search terms: children, adolescents, grip strength, dynamometer, JAMAR hand dynamometer, JHD, normative data and reference values. Reference lists of relevant articles were then screened to identify additional articles that might not have shown up in the search. Although we found several studies focusing specifically on grip strength in children, most of them have not assessed height and weight as factors of influence (Ager et al 1984, Bear-Lehman et al 2002, Butterfield et al 2009, De Smet and Vercammen 2001, Mathiowetz et al 1986). This is remarkable in the case of growing children, especially when weight and height are known to correlate with strength in children (Rauch 2002, Häger-Ross and Rösblad 2002, Newman et al 1984). Moreover, although some of these studies included a large number of children in total (with exception of Newman at al 1984, varying between 81 and 736), the number of children in each different age group and/or the range of age groups is often limited and relatively small for establishing reference values. Also, a variety of methods and instruments was used. For example, some studies did not differentiate between scores of the dominant and non-dominant hand, used a device that is no longer used in clinical practice, or scored the maximum instead of the mean of attempts. Therefore, it can be concluded that there is a need for a study that assesses the development of grip strength in children, based on large groups according to age and gender and performed according to current standardised methods regarding measurement of grip strength.
The primary aim of this study was to provide reference values for grip strength in children and to present this data graphically to allow easy comparison with patient outcomes by a range of clinicians in daily practice. Therefore the research questions were:
1. What are the reference values for grip strength in children aged 4 to 15 years according to age, gender and dominance based on a large, heterogeneous study population?
METHOD
Design
This cross-sectional study measured grip strength in a cohort of healthy children and adolescents. The data were used to generate normative values for grip strength.
Participants
Children and adolescents ranging in age from 4 to 15 years were included. Participants were recruited by approaching schools in the four Northern provinces of The Netherlands. All children of participating school classes were invited to participate. Exclusion criteria were: pain or restriction of movement of a hand or arm, neuromuscular disease, generalised bone disease, aneuploidy, any condition that severely interfered with normal growth or required hormonal supplementation, and children who could not be instructed in how to use the dynamometer. All included subjects were assigned to a group based on their calendar age at the time of the assessment, thereby creating 9 subgroups in total. The study aimed to include at least 200 children in each age group, with a near to equal representation of boys and girls.
Outcome measures
Each measurement session started with a short lecture by the researchers to introduce themselves to the school class and to explain the procedures and the purpose of the study. A demonstration of the use of the dynamometer was given, using the teacher as an example. Individually, dominance was determined by asking which hand was used to write or, in case of young children, used to perform activities such as cutting or painting. Children aged 4 and 5 years, in whom hand dominance is not yet fully established, and any older children that displayed uncertainty regarding hand dominance were asked to draw a circle. To avoid suggestion by the researcher, these participants had to pick up the pencil from the table themselves. The hand used to draw the shape was then scored as the dominant hand. The height (in cm) and weight (in kg) of each participating child were then measured.
Grip strength was measured using the Jamar® hydraulic hand dynamometer. A total of six cali-brated dynamometers were at the researchers’ disposal. The devices were replaced twice, at sub-sequent time intervals, with two used devices exchanged for two non-used devices after approx-imately a third, and again after two thirds of the total number of children we aimed to recruit had been assessed. The following standardised testing position for measuring grip strength was used, as advocated by the American Society of Hand Therapists (ASHT): the participants is seated with shoulders adducted and neutrally rotated, elbow flexed at 90 degrees, wrist between 0 and 30 de-grees extension and between 0 and 15 dede-grees ulnar deviation (Balogun et al 1985, Fess 1992). The handle of the device was set to the second position for all participants, with the exception of 4 and 5 year olds, for whom the bar was set to the first position, and who were allowed to manually sup-port the arm with the other hand. Participants were allowed four attempts using the dynamometer, two with each hand, and each individual attempt was scored. The starting hand was alternated between subjects and a 10-sec break was allowed between attempts. A Dutch translation of the Southampton grip strength measurement protocol was used as verbal encouragement (Roberts et al 2011). Encouragement was kept as consistent as possible for every participant in volume and tone; counting down from 3 to 0, followed by “squeeze as hard as you can… squeeze and let go”.
Data analysis
Descriptive statistics were used to describe the main characteristics of the participants. The Mann-Whitney U test was used to compare grip strength between genders. In order to establish the correlation of gender, age, height and weight with grip strength in more detail, we performed a multilevel analysis adding them as fixed factors. As intercept the school the child attended was added. Results were accepted to be significant when the p-value was <0.05.
RESULTS
In total 19 schools participated, located in 12 towns and cities. Thirteen children were ineligible for participation in the study. Two children were excluded because of Down syndrome, two children because they suffered from active juvenile arthritis, four because they had preexisting pain of a hand or arm, and one because she received hormonal therapy to improve growth. Another four children were excluded because they did not meet the inclusion criteria, but no specific reason was recorded. Nine eligible children were excluded because the form on which measurements were written was not filled in completely. In order to get an impression how many children refused to participate we randomly registered the number of children that refused to participate at half of the schools visited. Based on this registration it can be estimated that about 1% of invited children did not participate in the study. The reasons cited most commonly were unfamiliarity (children who just started school), problems with (self-perceived) body weight, or simply ‘not feeling like it’.
The final study population comprised 2241 children and adolescents (1112 boys and 1129 girls) ranging in age from 4 to 15 years. Values for grip strength according to age, hand dominance, and gender are presented in Figures 1 A to D. Grip strength in both hands increased with age, showing a nearly linear progression for boys until the age of 12. Above the age of 12, the increase in strength shows acceleration in the dominant hand. A similar observation can be made for the non-dominant hand after reaching the age of 13. For girls, this acceleration was less prominent but began at the earlier age of 11 for both hands. Regardless of this acceleration, the difference in mean strength between all age groups was significant for both hands and in both genders in favour of the older group (p < 0.01), with exception for the values of the non-dominant hand between girls aged 13 and 14 where p was 0.02.
A more extensive overview of all the results, including additional details regarding the study population, is presented in Table 1. Boys were significantly stronger than girls with the dominant hand at ages 4 (p = 0.02), 5 (p = 0.04), 6 (p = 0.003), 8 (p = 0.001), 9 (p = 0.001), and 14 (p < 0.001). For the non-dominant hand this was true at ages 4 (p = 0.03), 6 (p = 0.02), 8 (p < 0.001), 9 (p < 0.001), 11 (p = 0.01), and 14 (p < 0.001). With the exception of the dominant hand at age 7, where both genders scored equal, there was a trend for boys to score higher than girls with both their dominant and non-dominant hand in all age groups. The percentage difference in grip strength in favor of boys fluctuated, from 0–14% at ages 4 to 13, rising to 26% at age 14.
In order to establish the association of gender, age, height and weight with grip strength in more detail, we performed a multilevel analysis adding them as fixed factors. Adding the school the child attended as an intercept resulted in a better fit of the model for both the dominant and the non-dominant hand data. For both the dominant and the non-dominant hand, the variables age, height, weight and gender had a significant association with grip strength (p = <0.001), resulting in the following predictive equations:
Dominant hand = -20.58 (+ 1.09 if male) + 0.85 * age + 0.17 * height (cm) + 0.14 * weight (kg) Non-dominant hand = -19.5 (+1.17 if male) + 0.79 * age + 0.16 * height (cm) + 0.12 * weight (kg) A more extensive overview of these results is presented in Table 2.
Age Age Age Age Str ength (kg) Str ength (kg) Str ength (kg) Str ength (kg) P97 P90 P50 P10 P3 P97 P90 P50 P10 P3 P97 P90 P50 P10 P3 P97 P90 P50 P10 P3 50 45 40 35 30 25 20 15 10 5 0 50 45 40 35 30 25 20 15 10 5 0 50 45 40 35 30 25 20 15 10 5 0 50 45 40 35 30 25 20 15 10 5 0 4 5 6 7 8 9 10 11 12 13 14 4 5 6 7 8 9 10 11 12 13 14 4 5 6 7 8 9 10 11 12 13 14 4 5 6 7 8 9 10 11 12 13 14
Figure 1. Reference values for grip strength according to gender, dominance, and age.
A = boys, dominant hand, B = boys, non-dominant hand, C = girls, dominant hand, D = girls, non-dominant hand. Scores are plotted according to percentiles 3, 10, 50, 90, and 97. The upper and lower limits indicate the borders of reference values for strength at the corresponding age. The darker shaded areas represent the centralised 80% of scores.
Girls, dominant hand Girls, non-dominant hand
C D
Boys, dominant hand Boys, non-dominant hand
4 124 5.7 (2) 5.3 (2) 111 (5) 19 (3) 109 5.1 (2) 4.7 (2) 111 (5) 19 (3) 1-12 2-10 100-126 15-26 1-11 2-10 100-126 13-29 5 102 7.5 (3) 6.8 (3) 117 (6) 22 (3) 105 6.7 (2) 6.0 (2) 118 (6) 22 (3) 2-14 3-14 103-138 15-30 2-15 1-12 102-131 15-32 6 123 10.2 (3) 9.4 (3) 125 (5) 25 (4) 108 9.0 (3) 8.3 (3) 124 (6) 25 (4) 5-18 4-17 111-139 17-44 3-18 2-16 100-137 16-39 7 104 13.0 (4) 12.0 (3) 131 (6) 28 (5) 98 12.9 (3) 11.9 (3) 131 (6) 29 (5) 7-21 5-19 116-145 20-54 7-21 5-18 113-141 17-40 8 113 15.9 (4) 14.6 (3) 139 (6) 32 (6) 118 14.4 (3) 13.1 (3) 136 (6) 31 (6) 8-25 8-23 124-155 23-55 8-22 7-21 122-151 20-49 9 116 18.2 (4) 16.8 (4) 142 (6) 36 (7) 119 16.7 (3) 15.1 (3) 141 (5) 35 (7) 10-29 8-33 126-162 25-60 9-26 8-29 126-154 24-53 10 109 19.6 (2) 18.1 (3) 147 (7) 38 (7) 103 19.1 (4) 17.2 (4) 149 (7) 41 (8) 12-29 9-28 129-161 26-65 10-35 11-30 132-167 25-63 11 113 22.0 (5) 20.6 (4) 154 (8) 43 (10) 113 20.6 (4) 19.1 (4) 154 (8) 44 (9) 9-35 8-33 134-172 27-74 15-39 13-33 135-181 28-79 12 96 24.7 (5) 22.9 (5) 159 (9) 48 (10) 106 24.2 (5) 22.3 (4) 160 (6) 48 (11) 13-36 13-35 140-180 30-73 15-39 13-33 144-178 32-110 13 66 28.2 (6) 25.8 (6) 166 (9) 52 (10) 97 26.4 (5) 24.5 (4) 163 (7) 49 (8) 17-45 17-42 150-189 39-85 14-39 17-36 138-176 33-89 14 46 36.0 (7) 33.5 (7) 175 (8) 60 (11) 53 29.1 (5) 26.6 (5) 169 (6) 55 (10) 24-51 22-51 155-193 38-89 16-43 15-36 157-183 42-103 Boys Girls Age N Dominant Non-dominant Height Weight N Dominant Non-dominant Height Weight (yr) (kg) (kg) (cm) (kg) (kg) (kg) (cm) (kg) Table 1 . Number of participatnts, grip strength values for the dominant and non-dominant hands, heigth and weight, according to age and gender. mean (SD) range mean (SD) range
Hand Estimate SE DF t Wald Z p 95% CI
Parameter Lower Upper
Dominant Intercept -20.59 1.16 1707.65 -17.80 0.00 -22.85 -18.32 Male 1.09 0.14 2224.61 8.00 0.00 0.83 1.36 Height 0.17 0.13 2231.36 13.72 0.00 0.15 0.20 Weight 0.14 0.12 2231.41 11.78 0.00 0.12 0.16 Age 0.85 0.07 2172.38 12.05 0.00 0.71 0.99 Covariance Residual 10.23 0.31 33.30 0.00 9.64 10.85 Intercept school 1.11 0.42 2.64 0.01 0.53 2.33 Non-dominant Intercept -19.52 1.15 1832.86 -16.92 0.00 -21.78 -17.25 Male 1.17 0.14 2226.23 8.58 0.00 0.91 1.44 Height 0.16 0.13 2233.39 12.90 0.00 0.14 0.19 Weight 0.12 0.12 2233.49 10.47 0.00 0.10 0.15 Age 0.79 0.07 2130.14 11.21 0.00 0.65 0.93 Covariance Residual 10.29 0.31 33.30 0.00 9.70 10.91 Intercept school 0.87 0.34 2.60 0.01 0.41 1.86
