SICOT e-Newsletter
Issue No. 57 - June 2013
Worldwide News
The value of the three-point index in predicting redisplacement of diaphyseal fractures of the forearm in children
S. Ä°ltar, K.B. AlemdaroÄlu, F. Say, N.H. AydoÄan.
Ankara Training and Research Hospital, Ulucanlar, Ankara, Turkey
Samsun Training and Research Hospital, İlkadım, Samsun, Turkey
Bone Joint J 2013;95-B:563â7.
| Abstract ⨠⨠Introduction: Redisplacement is the most common complication of immobilisation in a cast for the treatment of diaphyseal fractures of the forearm in children. We have previously shown that the three-point index (TPI) can accurately predict redisplacement of fractures of the distal radius. In this prospective study we applied this index to assessment of diaphyseal fractures of the forearm in children and compared it with other cast-related indices that might predict redisplacement.⨠â¨
Methods: A total of 76 children were included. Their ages, initial displacement, quality of reduction, site and level of the fractures and quality of the casting according to the TPI, Canterbury index and padding index were analysed. Logistic regression analysis was used to investigate risk factors for redisplacement.⨠⨠Results: A total of 18 fractures (24%) redisplaced in the cast. A TPI value of > 0.8 was the only significant risk factor for redisplacement (odds ratio 238.5 (95% confidence interval 7.063 to 8054.86); p < 0.001)â¨.⨠Summary: The TPI was far superior to other radiological indices, with a sensitivity of 84% and a specificity of 97% in successfully predicting redisplacement. We recommend it for routine use in the management of these fractures in children. |
| Research Analysis ⨠ ⨠Primary research question: To test the hypothesis that the (Three-Point Index) TPI can be successfully modified to assess the reduction of forearm fractures in children and its success rate in predicting redisplacement can approach that in the distal radius.⨠â¨
Methodology: Prospective case series. ⨠⨠Study population: 84 consecutive children aged < 15 years with fractures of the forearm, 76 were considered eligible for conservative treatment and were included. Exclusion criteria included an unsatisfactory reduction (four patients), open fractures (three) and floating elbow (one). None of the fractures included in the study had an associated neurovascular injury. There were no bilateral fractures.
 ⨠Outcome measurement: Radiographic measurements were made and acceptable initial reduction angulation was < 25° in children aged < four years, < 15° in those between four and nine years and < 10° in those aged ⥠ten years, considering the remodelling potential due to years of growth remaining. All radiological measurements were made on anteroposterior and lateral radiographs by three authors (SI, KBA, FS) using Image J 1.42q (National Institutes of Health, Bethesda, Maryland) with 0.5° or 0.1 mm accuracy. At weekly follow-up visits, redisplacement was defined as further angulation of > 10° in any direction.⨠Statistical analysis: Chi-squared test was used to compare the dichotomous variables between redisplaced and non-redisplaced fractures. The Mann-Whitney U test was used to evaluate the significance of the difference of the means between the independent groups. Multivariate logistic regression analysis was performed to determine the effect of possible risk factors on redisplacement when they were present together. Thus, on the basis of univariate analysis, any variable significantly related with fall occurrence and those with a result of p < 0.25 were drawn into the analysis.15 SPSS v11.5 for Windows (SPSS Inc., Chicago, Illinois) was used for statistical analysis, and p-values < 0.05 were considered significant.⨠⨠Results: In 71 fractures (93%) the TPI predicted correctly whether there would be redisplacement, with a sensitivity of 84%, specificity of 97%, positive predictive value of 89% and negative predictive value of 95%. |
Comment by Shalin Maheshwari
Most paediatric diaphyseal fractures of the forearm are treated by manipulative reduction. The factors leading to redisplacement can be related to the fracture or the surgeon. Unlike fractures of the distal radius, radiological indices have not aroused interest in diaphyseal fractures of the forearm, aside from one study by Bhatia et al (2006) where a retrospective/prospective study was conducted, in which the review of case records and radiographs of forearm and distal radius/ulna fractures were included. In this study, distal radius fractures were included for the first time and even though all indices were higher in the group that showed displacement, there was no subgroup analysis, which means that the forearm fractures were not differentiated from the distal radius fractures, thus acting as a possible confounder.
The Padding index is the proportion of the dorsal gap (measured between the cast and the skin) to the largest interosseous distance between the radius and the ulna. The Cast index is the ratio of inner cast diameter at the fracture site on lateral and anteroposterior view. It proposes that the sectional geometry of the cast should be elliptical rather than circular in the distal forearm. Although later attempts were made to adapt the cast index to forearm fractures, the sectional geometry of the rest of the forearm is not as elliptical as at the wrist, and hence this index is not suitable for predicting redisplacement throughout the forearm. The Canterbury index combines the padding index and the cast index. Three-point index differs from the other indices because it not only takes into account the gaps at the fracture site, it also uses the gaps proximal and distal to the fracture sites, which are important points to maintain reduction against common displacement forces.
In previous studies of pediatric distal radius fractures where these indices were used: AlemdaroÄlu KB et al (2008) have shown that the limitation of these indices is that they are based on measurements of the gap at the fracture site alone and ignore proximal and distal cast fixation. Marcheix et al (2011) found poor moulding of the cast, as measured by the TPI, to be the only important risk factor for redisplacement and again found the TPI to reflect the quality of application of the cast and to be an excellent predictor of redisplacement. Hang et al (2011) concluded that a high TPI was the most significant risk factor for redisplacement, and Devalia et al (2011) reported that the TPI and the quality of reduction were the most significant indicators of redisplacement, recommending its use when judging the technique of moulding the cast.
This is the first report on the use of a modified TPI for the assessment of reduction of diaphyseal fractures of the forearm. The authors have compared all the above-mentioned indices with TPI and have found TPI to have higher sensitivity, specificity, positive predictive value and negative predictive value with acceptable interobserver reliability and intra-observer reliability. The authors were however not involved in the cast application but only in the assessment of the fractures on follow-up. They found a greater tendency for redisplacement of fractures in children aged < seven years which was attributed to difficulty in maintaining the reduction when casting a small forearm.
Paediatric forearm fractures is a very complex subject to be explained by a single factor. In my experience complete initial displacement of the fracture, anatomical reduction and obliquity of the fracture line seem to be the important risk factors for re-displacement. I feel that the casting indices should not be interpreted as a separate issue but in conjunction with fracture characteristics and patients factors. The three-point index has proven to be the superior of all these indices in paediatric distal radius fractures and now also seems promising in paediatric forearm fractures by this study.
Overall it is a good study and I would like to implement TPI assessment in paediatric forearm fractures in my routine practice. However, these results should be collaborated by further larger, multicentric, RCTâs to recommend it strongly as a protocol in radiological assessment of these forearm fractures under treatment and serve as a prognostic value for redisplacement.
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Paediatric forearm fractures is a very complex subject to be explained by a single factor. In my experience complete initial displacement of the fracture, anatomical reduction and obliquity of the fracture line seem to be the important risk factors for re-displacement. I feel that the casting indices should not be interpreted as a separate issue but in conjunction with fracture characteristics and patients factors. The three-point index has proven to be the superior of all these indices in paediatric distal radius fractures and now also seems promising in paediatric forearm fractures by this study.
Overall it is a good study and I would like to implement TPI assessment in paediatric forearm fractures in my routine practice. However, these results should be collaborated by further larger, multicentric, RCTâs to recommend it strongly as a protocol in radiological assessment of these forearm fractures under treatment and serve as a prognostic value for redisplacement.
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