Clinical validation of the multiplier method for predicting limb length discrepancy and outcome of epiphysiodesis, part II

Relevance of instrumented gait analysis in the prediction of the rebound phenomenon after guided growth intervention

Predictors of rebound after correction of coronal plane deformities using temporary hemiepiphysiodesis (TH) are not well defined. The following research questions were tested: (1) Is the dynamic knee joint load useful to improve rebound prediction accuracy? (2) Does a large initial deformity play a critical role in rebound development? (3) Are BMI and a young age risk factors for rebound? Fifty children and adolescents with idiopathic knee valgus malalignment were included. A deviation of the mechanical femorotibial angle (MFA) of ≥ 3° into valgus between explantation and the one-year follow-up period was chosen to classify a rebound. A rebound was detected in 22 of the 50 patients (44%). Two predictors of rebound were identified: 1. reduced peak lateral knee joint contact force in the first half of the stance phase at the time of explantation (72.7% prediction); 2. minor initial deformity according to the MFA (70.5% prediction). The best prediction (75%) was obtained by including both parameters in the binary logistic regression method. A TH should not be advised in patients with a minor initial deformity of the leg axis. Dynamic knee joint loading using gait analysis and musculoskeletal modeling can be used to determine the optimum time to remove the plates.

The Relationship Between Height and Income With Potential Application to Treatment of Limb Length Discrepancy

Purpose When treating limb length discrepancy (LLD), decisions regarding lengthening versus contralateral shortening require careful consideration of deformity and patient factors. Using the National Longitudinal Survey of Youth 1979 (NLSY79) database, and income as a quantitative representation of overall socioeconomic benefit, we sought to determine the height at which incremental gains in height have the greatest value. Methods Using the NLSY79 database, we collected demographic data, height, yearly income from wages, college education (full- or part-time), and receipt of government financial aid. Multiple-linear regression and graphical analysis were performed. Results The study population included 9,652 individuals, 4,775 (49.5%) males and 4,877 (50.5%) females. Mean heights were 70.0±3.0 inches and 64.3±2.6 inches for males and females, respectively. Multiple-linear regression analysis (adjusted-r²=0.33) demonstrated height had a standardized-ß=0.097 (p<0.001), even when accounting for confounding factors. Using graphical analysis, we estimated cut-offs of 74 inches for males and 69 inches for females, beyond which income decreased with incremental height. Conclusions Using income as a quantitative representation of socioeconomic value, our analysis found income increased with incremental height in individuals with predicted heights up to 74 inches for males and 69 inches for females. Shortening procedures might receive more consideration at predicted heights greater than these cut-offs, while lengthening might be more strongly considered at the lower ranges of height. Additionally, our multiple-linear regression analysis confirms the correlation between height and income, when factoring in other predictors of income.

Validation of central peak height method for final adult height predictions on long leg radiographs

Aims

Accurate skeletal age and final adult height prediction methods in paediatric orthopaedics are crucial for determining optimal timing of growth-guiding interventions and minimizing complications in treatments of various conditions. This study aimed to evaluate the accuracy of final adult height predictions using the central peak height (CPH) method with long leg X-rays and four different multiplier tables.

Methods

This study included 31 patients who underwent temporary hemiepiphysiodesis for varus or valgus deformity of the leg between 2014 and 2020. The skeletal age at surgical intervention was evaluated using the CPH method with long leg radiographs. The true final adult height (FHTRUE) was determined when the growth plates were closed. The final height prediction accuracy of four different multiplier tables (1. Bayley and Pinneau; 2. Paley et al; 3. Sanders - Greulich and Pyle (SGP); and 4. Sanders - peak height velocity (PHV)) was then compared using either skeletal age or chronological age.

Results

All final adult height predictions overestimated the FHTRUE, with the SGP multiplier table having the lowest overestimation and lowest absolute deviation when using both chronological age and skeletal age. There were no significant differences in final height prediction accuracy between using skeletal age and chronological age with PHV (p = 0.652) or SGP multiplier tables (p = 0.969). Adult height predictions with chronological age and SGP (r = 0.769; p ≤ 0.001), as well as chronological age and PHV (r = 0.822; p ≤ 0.001), showed higher correlations with FHTRUE than predictions with skeletal age and SGP (r = 0.657; p ≤ 0.001) or skeletal age and PHV (r = 0.707; p ≤ 0.001).

Conclusion

There was no significant improvement in adult height prediction accuracy when using the CPH method compared to chronological age alone. The study concludes that there is no advantage in routinely using the CPH method for skeletal age determination over the simple use of chronological age. The findings highlight the need for more accurate methods to predict final adult height in contemporary patient populations.

Comparison of Different Bone Age Methods and Chronological Age in Prediction of Remaining Growth Around the Knee

BACKGROUND

Bone age (BA) has been shown to be superior to chronological age (CA) when predicting remaining growth. However, it is not known whether the calculations are more accurate when BA is assessed by the Greulich and Pyle (GP) or the Sauvegrain (SG) methods. The aim of our study was to identify the method which gives an estimate closest to actual growth in the lower extremities.

METHODS

Leg length radiographs, hand radiographs, and elbow radiographs were simultaneously obtained during the adolescent growth spurt (10 to 16 years) in 52 children treated for LLD, with radiographic follow-up of segmental length (femur, tibia, and foot) until skeletal maturity, were randomly selected from a local institutional register. BA, according to GP and SG, were manually rated, and BA based on the GP method was additionally assessed by the automated BoneXpert (BX) method. The remaining growth was calculated based on the White-Menelaus method for both BA methods (GP, SG), the combination of the 2 methods, GP by BX, CA, and the combination of CA and GP by BX. Estimated growth was compared with the actual growth in the distal femur and proximal tibia from the time of BA determination until skeletal maturity.

RESULTS

For all included methods, the average calculated remaining growth was higher compared with the actual growth. The mean absolute difference between calculated remaining growth and actual growth in the femur and tibia was lowest using GP by BX [0.66 cm (SD 0.51 cm) and 0.43 cm (SD 0.34 cm)] and highest using CA [1.02 (SD 0.72) and 0.67 (SD 0.46)]. It was a significant association between calculated growth and the difference between actual and calculated growth for the SG method ( P =<0.001).

CONCLUSION

During the adolescent growth spurt, the GP method compared with the SG method and CA gives the most accurate estimate of remaining growth around the knee according to our results.

CLINICAL RELEVANCE

In calculations of remaining growth around the knee, BA assessment by the GP atlas or BX method should be used as the parameter of biological maturity.

Normative Femoral and Tibial Lengths in a Modern Population of Twenty-First-Century U.S. Children

BACKGROUND

The Green-Anderson (GA) leg-length data remain the gold standard for the age-based assessment of leg lengths in children despite their methodologic weaknesses. We aimed to summarize current growth trends among a cross-sectional cohort of modern U.S. children using quantile regression methods and to compare the median femoral and tibial lengths of the modern U.S. children with those of the GA cohort.

METHODS

A retrospective review of scanograms and upright slot-scanning radiographs obtained in otherwise healthy children between 2008 and 2020 was completed. A search of a radiology registry revealed 3,508 unique patients between the ages of 2 and 18 years for whom a standard-of-care scanogram or slot-scanning radiograph had been made. All patients with systemic illness, genetic conditions, or generalized diseases that may affect height were excluded. Measurements from a single leg at a single time point per subject were included, and the latest available time point was used for children who had multiple scanograms made. Quantile regression analysis was used to fit the lengths of the tibia and femur and overall leg length separately for male patients and female patients.

RESULTS

Seven hundred patients (328 female and 372 male) met the inclusion criteria. On average, the reported 50th percentile tibial lengths from the GA study at each time point were shorter than the lengths in this study by 2.2 cm (range, 1.4 to 3.3 cm) for boys and 2 cm (range, 1.1 to 3.1 cm) for girls. The reported 50th percentile femoral lengths from the GA study at each time point were shorter than the lengths in this study by 1.8 cm (range, 1.1 to 2.5 cm) for boys and 1.7 cm (range, 0.8 to 2.3 cm) shorter for girls.

CONCLUSIONS

This study developed new growth charts for femoral and tibial lengths in a modern U.S. population of children. The new femoral and tibial lengths at nearly all time points are 1 to 3 cm longer than traditional GA data. The use of GA data for epiphysiodesis could result in underestimation of expected childhood growth.

LEVEL OF EVIDENCE

Prognostic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Prediction of loss of correction after hemiepiphysiodesis for the alignment of lower limb angular deformities

Guided growth by temporary hemiepiphysiodesis (HEPD) is established for the alignment of lower limb angular deformities. This retrospective cohort study was designed to assess the effect of HEPD in idiopathic coronal plane deformities around the knee and on the frontal knee joint line orientation, and to test the frontal knee joint line as predictive means for recurrence.Fourty-four patients (78 deformities: valgus n = 64, varus n = 14) were enrolled in the retrospective observational study. Mechanical axis deviation, mechanical lateral distal femoral angle, and mechanical medial proximal tibial angle were assessed prior to surgery and during follow-up. The facultative frontal knee joint line angle (FKJLA) was used as predictive tool. Cases of remaining growth potential (n = 45/78) after implant removal were followed to assess rebound deformity.Pre-operative angles of the mechanical axis were corrected average 9.0 months after HEPD. Pre-operative assessment of the frontal knee joint line revealed a mean of 3.9° in valgus, and -1.0° in varus deformities. At time of complete deformity correction, mean FKJLA was -0.2° in valgus, and -0.8° in varus deformities. Mean shift of FKJLA was significantly higher after singleHEPD compared to combiHEPD (P < .001). Patients having an unphysiological FKJLA (>/<0°-3°) after correction of mechanical axis had a significantly higher risk of rebound deformity (P = .01). Regression analysis showed a 60.5% higher risk of rebound deformity per each degree deviating from the FKJLA physiological range. Age, gender, or body mass index had no impact.Temporary HEPD offers great potential for the correction of the mechanical axis and the frontal knee joint line. An unphysiological change of the frontal knee joint line is associated with a high risk of recurrent angular deformities. CombiHEPD instead of singleHEPD seems to be safer to prevent detrimental frontal knee joint line shift.Level of Evidence: Retrospective comparative therapeutic study, Level III.

Has the Threshold for Epiphysiodesis Versus Lengthening Changed in the Era of Magnetically Controlled Nails?

INTRODUCTION

Limb length discrepancy (LLD) is common in both the pediatric and adult population. Length inequalities can be due to a multitude of etiologies including congenital, developmental, and acquired causes. There has been little consensus on the morbidity of LLD and, as a result, the threshold necessary for treatment of LLD to prevent morbidity. Advances in magnetically controlled lengthening devices achieve greater accuracy and patient satisfaction and create an opportunity to lower the threshold for limb lengthening.

DISCUSSION

Asymptomatic LLD is relatively common in both pediatric and adult populations. Only ~10% of the population has equal leg length. LLD of <5 cm may lead to long-term morbidities such as scoliosis, lower back pain, gait abnormalities, stress on hip or knee joint, and lower extremity symptomatic versus asymptomatic osteoarthritis. The teaching in most orthopaedic textbooks is to adjust the shoe if symptomatic for discrepancies up to 2 cm; consider an orthotic, epiphysiodesis, or skeletal shortening for 2.5 to 5 cm; and possible limb reconstruction for >5 cm. The assumption is that there are no long-term consequences of mild LLD. However, data in recent literature show that small discrepancies may contribute to pathologic changes such as pain, gait abnormalities, and osteoarthritis. Major advances have been made in limb lengthening over the past 40 years. The increased accuracy and superior patient satisfaction of the magnetically controlled lengthening nail versus external fixation methods argue for including lengthening for LLD of <5 cm.

CONCLUSION

If mild LLD can cause long-term pathology, it is important to counsel families on the full range of options for limb equalization no matter the size of the discrepancy. The evolution in technology and understanding of limb lengthening has provided additional safe surgical options. Therefore, the historic treatment protocol for addressing limb differences may need to include lengthening for smaller discrepancies even <2 cm.

Height and Extremity-Length Prediction for Healthy Children Using Age-Based Versus Peak Height Velocity Timing-Based Multipliers

BACKGROUND

The age-based multiplier method described by Paley et al. markedly simplifies height and limb length predictions but may not adequately accommodate children's maturational differences. Multipliers can be derived relative to any maturity measure. This study compares Paley age-based multipliers with those based on peak height velocity (PHV) timing.

METHODS

In a longitudinal cohort of healthy children (66 male and 70 female), actual adult heights and limb lengths were compared with the measurements predicted using the Paley multipliers and multipliers developed relative to PHV timing. The age-based multipliers (adult divided by current) in our series were compared with those reported by Paley et al. to ensure that there were no systematic differences between the series. Absolute differences between the actual and predicted adult heights and limb lengths and the standard deviations of those differences were compared between the 2 methods.

RESULTS

The average age-based multipliers in our series were nearly identical to those reported by Paley et al. The differences between the predicted and actual adult values showed wide ranges when either the Paley or the PHV multipliers were used during infancy. The Paley method performed better than the PHV method throughout pre-growth-spurt childhood. The PHV-timing-derived multipliers became superior as children entered their growth spurt, whereas the performance of the age-based multipliers worsened. In adolescence, the maximum standard deviation for adult-height-prediction errors with use of the Paley multipliers occurred at the age of 13.5 years for boys and 11.5 years for girls and was 7.0 cm for boys and 5.6 cm for girls. For limb lengths, the maximum standard deviations occurred 6 months earlier and were 3.9 cm for boys and 3.2 cm for girls. The maximum standard deviation for the height prediction error with the age-based method occurred at the average time of PHV for the population. The PHV method became better than the Paley method just before growth-spurt initiation, at age 8 in girls and 11 in boys.

CONCLUSIONS

The age-based multipliers described by Paley et al. are superior to PHV-timing-based multipliers prior to the adolescent growth spurt for predicting height. They become less predictive, with wide standard deviations, as children enter their growth spurts, and PHV-derived multipliers become superior. The Paley height multipliers should be used before the age of 8 years in girls and 11 years in boys. After this, PHV-derived multipliers are superior for height and limb length prediction. In practice, these predictions are currently made using skeletal maturity, which is closely related to PHV during adolescence.

Leg Length Discrepancy- Treatment Indications and Strategies

BACKGROUND

Many people have leg-length discrepancies of greater or lesser severity. No evidence-based studies on the need for treatment are currently available.

METHODS

This review is based on publications retrieved by a selective search in the PubMed database, as well as on published recommendations from Germany and abroad and on the authors' own clinical experience.

RESULTS

If the two legs are of different lengths, this is generally because one leg is too short. It is debated whether leg-length discrepancy causes pain or long-term musculoskeletal disturbances. A direct connection to back pain is questionable, but a mildly elevated incidence of knee arthritis seems likely. The evidence base on the indications for treatment of leg-length discrepancy is poor; only informal consensus recommendations are available. There are a wide variety of conservative and surgical treatment options. The final extent of a leg-length discrepancy first noted during the growing years can be estimated with predictive algorithms to within 2 cm. The treatments that can be considered include a shoe insert, a high shoe, or an orthosis, surgically induced slowing of growth by blockade of the epiphyseal plates around the knee joint, or leg lengthening with osteotomy and subsequent distraction of the bone callus with fully implanted or external apparatus. Changes in leg length exert marked mechanical stress on the soft tissues. If the predicted leg-length discrepancy exceeds 5 cm, initial leg-lengthening treatment can already be considered during the patient's growing years.

CONCLUSION

It must be discussed with each patient individually whether the treatment should be conservative or surgical. The extent of the discrepancy is not the sole determining factor for the mode of treatment. The decision to treat is always elective.

Normal Ranges of Upper Extremity Length, Circumference, and Rate of Growth in the Pediatric Population

Background: Upper extremity length and circumference abnormalities are present in a number of conditions in the pediatric population. In most cases, upper limb hypoplasia and hypertrophy are diagnosed when one limb appears substantially different from the other during physical examination. However, occasionally when this discrepancy exists, it can be difficult to determine which limb is the abnormal one. The purpose of this study was to establish normal values for upper extremity length, circumference, and rate of growth in children aged 0 to 17 years. Methods: In all, 377 participants had 4 measurements taken of each upper extremity: upper arm length, upper arm circumference, forearm length, and forearm circumference. Statistical analysis was performed to identify differences and rates of growth. Results: Mean values for arm and forearm length and circumference for each age, 0 to 17 years, were established. The determination of a child's expected arm length is dependent on his or her height, age, and sex, while the calculation of a child's expected forearm length depends on his or her weight, age, and sex. Male and female arms and forearms have similar growth rates of lengths and circumferences. No significant differences were found between right and left extremities for each of the 4 measurements taken. Conclusions: Contralateral limbs can be used for comparison of length and circumference of the arm and forearm in cases of unilateral upper extremity abnormality. The establishment of normal values for upper extremity length, circumference, and growth rate will be a useful diagnostic tool for upper extremity hypoplasia and hypertrophy.

Temporary hemiepiphysiodesis for correcting idiopathic and pathologic deformities of the knee: A retrospective analysis of 355 cases

BACKGROUND

Hemiepiphysiodesis is a well-established treatment option in cases of pathologic deformities and leg discrepancies during evolution. The aim of this study was to evaluate the postoperative angular measurement, correction correlated with age at operation time, and postoperative complication rate.

MATERIAL AND METHODS

A total of 355 patients were treated with 887 8-plates between April 2007 and January 2013. Their mean age was 12.18 years (range four to 16 years), and the mean time to axis correction was 17.32 months (range two to 62 months). We analysed the entire population and also performed subgroup analyses for idiopathic, pathologic, varus, valgus and leg length discrepancy.

RESULTS

The mean durations (time from (hemi-) epiphysiodesis to implant removal) in the idiopathic and pathologic groups were 13.24 and 21.3 months, respectively. The time to implant removal was 18.39 months for idiopathic varus deformities and 11.07 months for idiopathic valgus deformities. For the pathologic deformity group it was 24.9 and 20 months in the varus and valgus subgroups, respectively.

CONCLUSIONS

Hemiepiphysiodesis is a well-established treatment option to correct angular deformities. The rate of correction was slower and less successful in pathologic deformities and for leg length discrepancies. This suggests that earlier intervention is appropriate for these patients. A higher body mass index (BMI) was observed for valgus deformity, but no correlation was present between BMI and durability.

Long-term results and comparison of the Green-Anderson and multiplier growth prediction methods after permanent epiphysiodesis using Canale's technique

PURPOSE

The aim of the study was to evaluate the accuracy and radiographic outcomes of Canale's method in patients with idiopathic leg-length discrepancy (LLD) following percutaneous epiphysiodesis. The accuracy of two common growth prediction methods was assessed.

METHODS

A total of 18 patients with 26 affected bones (eight distal femur, two proximal tibia, five combined) were clinically and radiologically analyzed after reaching skeletal maturity. We compared the final effect of epiphysiodesis at maturity with the expected effect of epiphysiodesis before surgery; these measures were calculated using the Green-Anderson and multiplier methods, respectively. We furthermore compared pre- and postoperative frontal and lateral plane radiographs.

RESULTS

The average LLD was 21.2 mm before surgery and 7.9 mm after epiphysiodesis. The final effect of both methods was not significantly different compared with the expected effect of epiphysiodesis before surgery. However, the prediction by the Green-Anderson method was closer to the definitive epiphysiodesis effect. The frontal plane radiographic deformity parameters did not change significantly after epiphysiodesis. The postoperative sagittal plane radiographic deformity parameters were in the normal range.

CONCLUSION

The Canale technique is a reliable method to reduce LLD in children. With regards to growth prediction, the Green-Anderson method using bone age seems to be more accurate than the multiplier method using chronological age. However, a relative over-estimation was observed with both methods in several cases, which might result in an insufficient correction.

LEVEL OF EVIDENCE

IV, Therapeutic study.

Growth modulation in idiopathic angular knee deformities: is it predictable?

PURPOSE

To evaluate the temporal and spatial sequence of events following temporal hemiepiphysiodesis in idiopathic knee varus/valgus.

METHODS

This is a retrospective multicentre study on 372 physes in 206 patients. The average rate of correction (ROC) was calculated; univariate and multivariate analysis were performed.

RESULTS

In all, 92% of the femoral physes were followed for more than one year/reached skeletal maturity. Of those, 93% were corrected to a mechanical lateral distal femoral angle (mLDFA) of 85° to 89°; 2% did not, while 5% were over-corrected. A total of 92% of the tibial physes were followed for more than one year/reached skeletal maturity. Of those, 92% were corrected to a mechanical medial proximal tibial angle (mMPTA) of 85° to 89°; 2% did not, while 6% were over-corrected. Factors significantly influencing success and ROC were age, direction and magnitude of deformity. Femoral ROC was significantly faster than tibial ROC: 0.85° versus 0.78°/month, respectively (p = 0.05). Femoral valgus ROC was significantly faster than varus ROC: 0.90° versus 0.77°/month, respectively (p = 0.04). A constant was derived to calculate the amount of correction. Significant correlation was found between calculated and actual mLDFA in valgus deformity during the first year (r = 0.58 to 0.87, p < 0.01). Calculated mLDFA of varus deformity did not correlate with actual mLDFA. Significant correlation was found when calculating mMPTA correction in all deformities.

CONCLUSIONS

Femur corrects faster than tibia; valgus femoral deformities are corrected faster than varus. Valgus correction in the distal femur/proximal tibia as well as varus correction in the tibia in idiopathic patients is highly predictable. The constant derived is the first tool which enables predicting and monitoring amount of correction in hemiepiphysiodesis when correcting angular deformities around the knee.

LEVEL OF EVIDENCE

IV.

Understanding Skeletal Growth and Predicting Limb-Length Inequality in Pediatric Patients

Limb-length inequality in a child can be a complex condition for patients, parents, and medical providers. Managing these patients and explaining the treatment options to families requires knowledge of the potential risks associated with leaving a discrepancy untreated and a thorough understanding of skeletal growth. The provider must also be familiar with the available growth prediction methods as treatment is influenced by the anticipated discrepancy at skeletal maturity. This article provides an overview to skeletal growth, assessing skeletal maturity and growth prediction to help providers develop an organized and thoughtful approach to treating pediatric patients with limb-length inequalities.

How Accurate is the Multiplier Method in Predicting the Timing of Angular Correction After Hemiepiphysiodesis?

PURPOSE

The purpose of the study was to validate the accuracy of the Multiplier Method (MM) in predicting the timing of angular correction after hemiepiphysiodesis and to determine the role of using skeletal age when calculating those predictions.

METHODS

This retrospective study included 131 physes in 77 patients treated with hemiepiphysiodesis to gradually correct a coronal plane deformity before skeletal maturity. To compare the MM's predictions to the actual treatment duration, the "desired angular correction" was considered the actual achieved angular correction determined from the "endpoint x-ray" (last x-ray before implant removal). We measured the bone length and width of the growth plate from the preoperative x-ray and calculated the MM's prediction of the duration of treatment based on the MM formula. We compared the predicted duration to the observed duration of treatment for each case. The difference was calculated by subtracting the observed duration from the predicted duration. The result was the "absolute difference," which is the number of months over or under predicted by the MM.

RESULTS

The mean absolute difference between the MM's predicted duration and the observed duration was 2.31 months, which was highly significant (P≤0.001). The MM's prediction agreed with the observed duration of treatment (ie, zero absolute difference) in 15% of the predictions, 69% were under predicted, and 16% were over predicted. Sixty-eight percent of the absolute differences were within 3 months regardless of the direction of error. The mean difference was relatively less in genu varum cases and was statistically significant (P=0.047). Comparing the mean difference using chronological age and skeletal age in the formula showed no statistically significant difference.

CONCLUSIONS

The MM has a tendency to under predict. Therefore, doing a guided growth right before skeletal maturity should be started 2 to 4 months earlier than suggested by the MM. Moreover, our data did not show that the bone age gave more accurate predictions than chronological age.

LEVEL OF EVIDENCE

Level IV.

Tension band plating is less effective in achieving equalization of leg length

PURPOSE

Little data is available on the efficiency of different implants for epiphysiodesis. The purpose of this study is to compare the efficacy between plates and staples in decreasing leg-length discrepancy.

METHODS

A retrospective review of 19 children who underwent temporary epiphysiodesis of the legs was conducted, with a minimum of two years of follow-up. The bone length and length ratio to the short side were measured at six months, one year and two years postoperatively. The change in discrepancy was compared between staples and plates by an independent t-test, and the shortest time to a significant decrease in discrepancy was determined using a paired t-test.

RESULTS

Ten patients underwent 13 staple procedures in nine femurs and four tibias for a 2.8-cm discrepancy at age 11.8 years, and nine patients underwent 14 plate procedures in seven femurs and seven tibias for a 3.1-cm discrepancy at age 12.4 years. Patients were followed up to skeletal maturity, except two. The use of staples decreased the discrepancy in the bone ratio from +4.8% to +1.2% in two years, and the use of plates decreased this ratio from +5.1% to +3.3% in two years. The change in the length ratio was significantly greater after stapling. Six months were required after stapling before the first significant decrease in discrepancy; it took two years after plating.

CONCLUSIONS

This study showed a significantly lower efficacy for decreasing leg-length discrepancy by tension band plating. Orthopaedic surgeons should be aware of the limitations of using plates for suppressing bone growth.

LEVEL OF EVIDENCE

III.

Timing of Epiphysiodesis to Correct Leg-Length Discrepancy: A Comparison of Prediction Methods

BACKGROUND

The purpose of this study was to compare the accuracy of different methods used to predict ultimate leg lengths and residual leg-length discrepancy in a group of patients treated with epiphysiodesis at our institution.

METHODS

Seventy-seven patients with adequate preoperative radiographs, no postoperative complications, and follow-up to skeletal maturity composed the study group. We compared the predicted lengths of both legs and residual leg-length discrepancy at maturity with actual outcomes using the White-Menelaus, Anderson-Green, Moseley, and multiplier methods.

RESULTS

Skeletal age varied >1 year from chronological age in 61 (26%) of 231 observations, including 19 patients (25%) whose average skeletal age from 3 determinations differed by >1 year from chronological age. The prediction accuracy of each method was improved by using skeletal, rather than chronological, age. Error in prediction of the length of the short leg varied from a mean (and standard deviation) of 1.8 ± 1.2 cm for the straight-line graph to 2.5 ± 2.0 cm for the multiplier method. Prediction error for the long leg (after epiphysiodesis) varied from a mean of 1.2 ± 1.1 cm for the straight-line graph to 1.7 ± 1.5 cm for the multiplier method. Leg-length-discrepancy prediction error ranged from a mean of 0.7 ± 0.6 cm for the White-Menelaus method incorporating a growth inhibition factor to 1.1 ± 0.9 cm for the multiplier method. The multiplier method was the least accurate of all. All differences were significant.

CONCLUSIONS

Determination of skeletal age is clinically relevant in patients being considered for epiphysiodesis to manage leg-length inequality. The multiplier method was the least accurate of the prediction methods in this patient population, which may have implications in calculating the appropriate timing of epiphysiodesis.

Analysis of Serial Radiographs of the Foot to Determine Normative Values for the Growth of the First Metatarsal to Guide Hemiepiphysiodesis for Immature Hallux Valgus

BACKGROUND

Hallux valgus deformity in the immature patient can be difficult to manage, as osteotomy can result in recurrence with additional growth. Lateral hemiepiphysiodesis of the first metatarsal offers a promising alternative, by permitting gradual correction of the intermetatarsal angle with growth. An important limitation of this approach is the lack of normative tables of first metatarsal growth to guide timing of intervention.

METHODS

First metatarsal lengths were measured from anteroposterior foot radiographs of children. For females, 95 patients totaling 894 radiographs were used ranging from 6 months to 18 years of age. For males, 122 patients totaling 1018 radiographs were measured ranging from 8 months to 19.5 years of age. All patients with image series including a closed proximal metatarsal physis were sorted into an older group, with multipliers generated by setting last image to a multiplier of 1. Patients with serial imaging not inclusive of a closed physis were classified as a younger group, with multipliers based off of the multiplier at age 7 from the older group. First metatarsal multiplier values were then compared with published multiplier values for the overall foot.

RESULTS

For both females and males, the multipliers followed a logarithmic curve versus age, with R values of 0.921 and 0.888, respectively. Comparison of the first metatarsal multiplier values with previously studied multiplier values of the entire foot showed high correlation with ICC=0.955 for females and ICC=0.969 for males.

CONCLUSIONS

The pattern of growth of the first metatarsal follows a logarithmic regression curve. These normative tables allow for clinical prediction of first metatarsal remaining growth based on age and sex, and in turn guide timing of hemiepiphysiodesis for the surgical correction of hallux valgus deformity.

CLINICAL RELEVANCE

The normative tables generated in this study can be used for the calculation of hemiepiphysiodesis and the timing of intervention. Future clinical correlation studies will be important.

Evaluation of a Mobile Application for Multiplier Method Growth and Epiphysiodesis Timing Predictions

BACKGROUND

The multiplier method (MM) is frequently used to predict limb-length discrepancy and timing of epiphysiodesis. The traditional MM uses complex formulae and requires a calculator. A mobile application was developed in an attempt to simplify and streamline these calculations. We compared the accuracy and speed of using the traditional pencil and paper technique with that using the Multiplier App (MA).

METHODS

After attending a training lecture and a hands-on workshop on the MM and MA, 30 resident surgeons were asked to apply the traditional MM and the MA at different weeks of their rotations. They were randomized as to the method they applied first. Subjects performed calculations for 5 clinical exercises that involved congenital and developmental limb-length discrepancies and timing of epiphysiodesis. The amount of time required to complete the exercises and the accuracy of the answers were evaluated for each subject.

RESULTS

The test subjects answered 60% of the questions correctly using the traditional MM and 80% of the questions correctly using the MA (P=0.001). The average amount of time to complete the 5 exercises with the MM and MA was 22 and 8 minutes, respectively (P<0.0001).

CONCLUSIONS

Several reports state that the traditional MM is quick and easy to use. Nevertheless, even in the most experienced hands, performing the calculations in clinical practice can be time-consuming. Errors may result from choosing the wrong formulae and from performing the calculations by hand. Our data show that the MA is simpler, more accurate, and faster than the traditional MM from a practical standpoint.

LEVEL OF EVIDENCE

Level II.

Prediction of rebound phenomenon after removal of hemiepiphyseal staples in patients with idiopathic genu valgum deformity

AIMS

Our aim was to investigate the predictive factors for the development of a rebound phenomenon after temporary hemiepiphysiodesis in children with genu valgum.

PATIENTS AND METHODS

We studied 37 limbs with idiopathic genu valgum who were treated with hemiepiphyseal stapling, and with more than six months remaining growth at removal of the staples. All children were followed until skeletal maturity or for more than two years after removal of the staples.

RESULTS

On multivariate logistic regression analysis, the rate of correction, body mass index (BMI), age, and initial valgus angle were significantly associated with a rebound phenomenon. With those characteristics, a predictive model for rebound was generated using recursive partitioning analysis. Children with a rapid rate of correction had the most frequent and severe rebound phenomenon (incidence 79%, mean 4°), whereas those with a slow rate of correction had less rebound when they had low BMI (43%, 2°) and none when the BMI was ≥ 21 kg/m(2).

CONCLUSION

This is the first study to evaluate a predictive model for a rebound phenomenon after temporary hemiepiphysiodesis in children with idiopathic genu valgum. Cite this article: Bone Joint J 2016;98-B:1270-5.

Validation of the multiplier method for leg-length predictions on a large European cohort and an assessment of the effect of physiological age on predictions

PURPOSE

The Avon Longitudinal Study of Parents and Children (ALSPAC) prospective cohort was used to determine the accuracy of the Paley multiplier method for predicting leg length. Using menarche as a proxy, physiological age was then used to increase the accuracy of the multiplier.

METHODS

Chronological age was corrected in female patients over the age of eight years with documented date of first menses. Final sub-ischial leg length and predicted final leg length were predicted for all data points.

RESULTS

Good correlation was demonstrated between the Paley and ALSPAC data. The average error in prediction depended on the time of assessment, tending to improve as the child got older. It varied from 2.2 cm at the age of seven years to 1.8 cm at the age of 14 years. When chronological age was corrected, the accuracy of multiplier increased. Age correction of 50% improved multiplier predictions by up to 28%.

CONCLUSION

There appears to have been no significant change in growth trajectories of the two populations who were chronologically separated by 40 years. While the Paley data were based on extracting trends from averaged data, the ALSPAC dataset provides descriptive statistics from which it is possible to compare populations and assess the accuracy of the multiplier method. The data suggest that the accuracy improves as the patient gets close to the average skeletal maturity but that results need to be interpreted in conjunction with a radiological assessment of the growth plates. The magnitude of the errors in prediction suggest that when using the multiplier, the clinician must remain vigilant and prepared to perform a contralateral epiphyseodisis if the prediction proves to be wrong. The data suggest a relationship between the multiplier and menarche. There appears to be a factorisation and when accounting for physiological age, one needs to correct by 50% of the difference between chronological and physiological age.

Correction of lower limb deformities in children with renal osteodystrophy by guided growth technique

PURPOSE

Renal osteodystrophy (ROD) may cause severe lower limb deformities in children. The purpose of this study is to evaluate the efficacy of the temporary hemiepiphysiodesis for the correction of lower limb deformities in children with ROD.

METHODS

Guided growth correction by hemiepiphysiodesis has been performed in skeletally immature patients with deformities of the lower limbs caused by ROD. The correction of the mechanical axes of the lower limbs and its correction speed have been evaluated.

RESULTS

A total of seven patients with ROD, five males and two females, were treated with the above technique. The average age of the patients at their first surgery was 7.8 years (2.9 to 13.6). The average follow-up time 5.2 years (2.3 to 8). There were 13 valgus deformities and one varus deformity of the knee. The measure of the lower limb angular deformity was in the range of 10° to 47°. Restoration of normal mechanical axis was achieved in all patients at the final follow-up. Three patients relapsed and required further hemiepiphysiodesis. The average time for correction was 20 months (7 to 30). The average speed of correction was 0.49° per month for a tibia and 1.73° per month for a femur. There were two minor complications: a screw mobilisation and a screw breakage occurred during removal.

CONCLUSION

Guided growth technique by hemiepiphysiodesis is a mini-invasive surgical procedure that has been found to be effective for the correction of misalignment due to ROD in skeletally immature patients. The method has allowed progressive correction of the deformities at any age in childhood. These patients are predisposed to relapse to their deformities, thus a strict follow-up is required.

Surgical reconstruction for fibular hemimelia

Fibular hemimelia presents with foot deformity and leg length discrepancy. Previous classifications have focused on the degree of fibular deficiency rather than the type of foot deformity. Published methods of surgical reconstruction have often failed due to residual or recurrent foot deformity. The purpose of this report is to introduce new classification and reconstruction methods. The Paley SHORDT procedure is used to stabilize the ankle when there is a hypoplastic distal fibula with a dynamic valgus deformity. It involves shortening and realignment of the distal tibia relative to the fibula. In contrast, the Paley SUPERankle procedure is used when there is a fixed equinovalgus foot deformity. The SUPERankle uses a supramalleolar shortening-realignment osteotomy and/or subtalar osteotomies with anlage resection. Due to the bony instead of soft tissue correction of deformity, residual or recurrent deformity is prevented. Weakening of gastro-soleus and peroneal muscles is avoided by shortening of the tibia instead of tendon lengthening. The limitation of ankle motion is related to ankle dysplasia rather than surgery or lengthening. A plantigrade-stable foot and ankle leads to an excellent functional result comparable or better than a Syme's amputation with prosthetic fitting. Serial lengthening procedures combined with the SHORDT or SUPERankle reconstruction lead to limb length equalization with a plantigrade, painless, functional foot.

Is There a Reliable Method to Predict the Limb Length Discrepancy after Chemotherapy and Limb Salvage Surgery in Children with Osteosarcoma?

Background:

For a child with osteosarcoma, prediction of the limb length discrepancy at maturity is important when planning for limb salvage surgery. The purpose of this study was to provide a reliable prediction method.

Methods:

A retrospective review of Chinese children receiving chemotherapy for osteosarcoma before skeletal maturity was conducted. Standing full-length radiographs of the lower extremity were used for length measurements. Length-for-age curves were constructed using the LMS method. The lower limb multiplier for a specific age and gender was calculated using the formula M = L_m/L, where M was the gender- and age-specific multiplier, L_m was the bone length at maturity, and L was the age-specific bone length. Prematurity and postmaturity radiographs were used to assess the accuracy of the prediction methods.

Results:

A total of 513 radiographs of 131 boys and 314 radiographs of 86 girls were used to calculate the coefficients of the multiplier. The multipliers of 8-, 9-, 10-, 11-, 12-, 13-, 14-, 15-, 16-, 17-, and 18-year-old boys after chemotherapy for osteosarcoma were 1.394, 1.306, 1.231, 1.170, 1.119, 1.071, 1.032, 1.010, 1.004, 1.001, and 1.000, respectively; while for girls at the same ages, the multipliers were 1.311, 1.221, 1.146, 1.092, 1.049, 1.021, 1.006, 1.001, 1.000, 1.000, and 1.000, respectively. Prematurity and postmaturity femoral and tibial lengths of 21 patients were used to assess the prediction accuracy. The mean prediction error was 0 cm, 0.8 cm, and 1.6 cm for the multiplier method using our coefficients, Paley's coefficients, and Anderson's method, respectively.

Conclusions:

Our coefficients for the multiplier method are reliable in predicting lower limb length growth of Chinese children with osteosarcoma.

An improved spreadsheet for calculating limb length discrepancy and epiphysiodesis timing using the multiplier method

PURPOSE

The multiplier method is a technique to predict limb length discrepancy (LLD) at maturity in pediatric patients. Various tools have been developed for performing the multiplier calculations to predict LLD and timing of epiphysiodesis. These include multiplier/growth applications (apps) and a spreadsheet which have helped to facilitate LLC calculations in an efficient and easy manner. We have updated the spreadsheet to improve features for making LLD calculations and facilitate pasting data into electronic medical records (EMRs).

METHODS

Tools currently in use were critically examined for features that limited their function, created possible sources of error or could be more user-friendly. These features were modified and recreated in an improved Excel spreadsheet that uses patient age, sex, limb lengths, and previous lengthening surgeries as inputs to predict LLD at maturity and offer options for timing of epiphysiodesis for both congenital and developmental LLD. Our multiplier spreadsheet function was then compared to manual calculations and other multiplier tools for accuracy and ease of use.

RESULTS

Our spreadsheet accurately calculates LLD at maturity and timing of epiphysiodesis when compared to other methods. It contains a function to calculate predicted leg lengths after previous lengthenings, and concise single-page worksheets for developmental LLD, congenital LLD, and height prediction.

CONCLUSIONS

This spreadsheet was developed to provide a more efficient and user-friendly method of calculating LLD at maturity and timing of epiphysiodesis. It can easily be pasted into the EMR for ease of documentation. We recommend this method for both clinical practice and educational use.

Comparison of the Paley method using chronological age with use of skeletal maturity for predicting mature limb length in children

BACKGROUND

Treating patients with congenital or acquired limb-length inequality requires accurate estimations of limb length at skeletal maturity. There is controversy over the best indicator of maturity to be used for limb-length calculations. Paley popularized the multiplier method, in which chronological age is used, which has the virtue of simplicity but does not account for the wide variance in timing of the adolescent growth spurt. The purpose of this study was to determine whether the use of chronological age or the level of skeletal maturity provides more accurate limb-length predictions.

METHODS

We identified patients with limb-length inequality, for whom scanograms had been obtained before and at maturity, and who had had no surgical procedures on their normal lower limb. Skeletal maturity was determined with use of the Greulich and Pyle atlas, Tanner-Whitehouse-3 method, and simplified stages described by Sanders et al. The length of the lower extremity was compared with the ultimate limb length and the actual multiplier (final limb length divided by current limb length) for each point in time. A linear model was used to determine the log-transformed multipliers for the level of skeletal maturity, and Paley's multipliers were used for chronological age. Residual standard errors were determined to compare the results of the methods. We also conducted piecewise linear regression on each of the methods and used the residual standard errors to rank their performance and cross-validated the results.

RESULTS

We identified twenty-four patients (twelve girls and twelve boys) who met the study criteria. Most subjects had had multiple scanograms along with skeletal age radiographs (average, 4.5) at different ages. When all ages are considered, the Paley method had the best overall performance, with residual standard errors that were typically =5 cm. However, the Paley method did not perform best for subjects at stage-2 skeletal maturity or above; in those cases, skeletal-maturity-based predictions had residual standard errors of &lt;2 cm.

CONCLUSIONS

While the Paley method, which is based on chronological age, provides reasonable estimates of ultimate limb length for most patients, use of skeletal-maturity determinations appears to provide better predictions of mature limb length during adolescence.

Surgical epiphysiodesis indications and techniques: update

PURPOSE OF REVIEW

To present a summary of epiphysiodesis indications and to report most recent advances in the field, along with their clinical relevance.

RECENT FINDINGS

Percutaneous epiphysiodesis using transphyseal screws (PETS) and guided growth using eight plates represent the most recent techniques used for hemiepiphysiodesis.

SUMMARY

PETS and guided growth have yielded very good results and low rates of complications and are the current standard for the management of angular deformities of the lower extremities in children. Permanent percutaneous epiphysiodesis remains the preferred method for the treatment of limb length discrepancies.

Possible mistakes in prediction of bone maturation in fibular hemimelia by Moseley chart

The purpose of this study was to establish a nomogram in order to predict limb length discrepancies in children with unilateral fibular hemimelia more accurately. In 31 children with unilateral fibular hemimelia the femoral-tibial length and skeletal age were determined an average of seven times per case by sequential radiographs during growth. From the data, a skeletal age nomogram was developed which shows a steeply declining mean skeletal age pattern in unilateral fibular hemimelia (the slope in girls was -0.59 and in boys -0.64). This nomogram crosses the normal mean skeletal age line of the Moseley straight-line graph at 10.5 years in girls and at 12 years in boys, and continues to decline until maturity. The results demonstrate an abnormal skeletal maturation process in patients with unilateral fibular hemimelia. The consistently declining steep skeletal age nomogram in unilateral fibular hemimelia makes prediction of skeletal maturity and limb length discrepancy inaccurate by the standard predictive methods particularly when using early skeletal ages. The skeletal age nomogram from our data determines skeletal maturation in children with unilateral fibular hemimelia more accurately, and allows a correct prediction of limb length discrepancy.

Growth rate after limb deformity correction by the Ilizarov method with or without knee joint distraction: lengthening in 30 children followed for at least 2 years

BACKGROUND AND PURPOSE

Growth inhibition and stimulation have both been reported after juvenile limb lengthening. Distraction of a joint usually suspends and unloads the growth plate and may stimulate growth. We investigated the influence of knee joint distraction on the speed of growth after limb lengthening. METHODS In a retrospective study, growth patterns were analyzed in 30 children mean 61 (24-109) months after limb lengthening with the Ilizarov method, each child having more than 2 years of remaining growth. In 14 patients with knee joint instability, the knee was bridged over during lengthening for joint stabilization. Whether or not joint bridging and distraction would affect patterns of growth of the lengthened limb by unloading the growth plate was evaluated with a repeated measurements analysis of variance.

RESULTS

After lengthening procedures, the proportionate leg-length discrepancy was found to decrease in 16 children, suggesting increased growth rate in the lengthened limbs. A statistically significantly faster growth rate was seen in 8 of 14 patients with knee distraction as compared to patients with single bone frame configurations.

INTERPRETATION

Further research is required to investigate whether growth stimulation is due to the surgical technique and whether joint distraction should be recommended during limb lengthening in growing children.

Efficacy and safety of percutaneous epiphysiodesis

BACKGROUND

The aims of this study were to evaluate outcomes of percutaneous epiphysiodesis, as described by Bowen, in 97 patients and to assess complications and determine whether the effect of the epiphysiodesis will accurately follow the Moseley chart predictions.

METHODS

A total of 97 patients were reviewed retrospectively. Fifty-six girls and 41 boys, with a mean skeletal age of 12.6 years (range, 10-16 years) at the time of operation, were followed up until skeletal maturity, a mean of 3.8 years (range, 1-10 years).

RESULTS

The mean residual leg length discrepancy (LLD) in 88 patients at maturity was 1.3 cm (range, 0-3.5 cm). In 9 patients, the epiphysiodesis was combined with a femoral lengthening or femoral shortening. The residual leg length discrepancy in these 9 patients was 3.3 cm at maturity (range, 0-6.5 cm). Minor complications including knee effusion (n = 2), superficial wound infection (n = 1), and exostosis (n = 3) occurred in 6 patients. Failure of the epiphysiodesis was the only major complication seen (n = 3).

CONCLUSIONS

This study shows that complications are infrequent when performing percutaneous epiphysiodesis and that the Moseley straight-line method accurately and efficaciously predicted the timing for percutaneous epiphysiodesis in all but one patient who had unpredictable growth from hemihypertrophy secondary to a hemangiomatosis.

Estimation of stature and length of limb segments in children and adolescents from whole-body dual-energy X-ray absorptiometry scans

BACKGROUND

Anthropometric standards vary among different populations, and renewal of these reference values is necessary.

OBJECTIVE

To produce formulae for the assessment of limb segment lengths.

MATERIALS AND METHODS

Whole-body dual-energy X-ray absorptiometry scans of 413 Caucasian children and adolescents (170 boys, 243 girls) aged from 6 to 18 years were retrospectively analysed. Body height and the lengths of four long bones (humerus, radius, femur and tibia) were measured. The validity (concurrent validity) and reproducibility (intraobserver reliability) of the measurement technique were tested.

RESULTS

High linear correlations (r > 0.9) were found between the mentioned five longitudinal measures. Corresponding linear regression equations for the most important relationships were derived. The tests of validity and reproducibility revealed a good degree of precision of the applied technique.

CONCLUSION

The reference formulae obtained from the analysis of whole-body DEXA scans will be useful for anthropologists, and forensic and nutrition specialists, as well as for prosthetists and paediatric orthopaedic surgeons.

Multiplier method for limb-length prediction in the upper extremity

PURPOSE

Limb-length discrepancy occurs in both the upper and lower extremities. Methods of predicting discrepancies at skeletal maturity have generally focused on the lower limbs. Paley et al devised the multiplier method to predict lower-limb-length discrepancy at skeletal maturity. The purpose of this study was to generate a similar methodology applicable for the upper limb.

METHODS

Using radiographic, clinical, and anthropologic databases, we divided humeral, radial, and ulnar lengths at skeletal maturity by the humeral, radial, and ulnar lengths at each age and for each percentile given. The multipliers for the radius, the ulna, and the humerus were compared with each other. The multipliers also were compared based on percentile, ethnic and racial group, nationality, and anthropologic data.

RESULTS

The multipliers for the humerus, radius, and ulna were equivalent in all percentile groups, varying only by age and gender after 1 year of age. The multipliers of different national and racial groups also were the same. The upper-extremity multipliers calculated from anthropologic data were very similar.

CONCLUSIONS

The multiplier method is a quick and easy method of predicting upper-limb growth. It is simpler to use than previous methods and is independent of percentile, generation, ethnicity, nationality, and race. The upper-extremity multiplier can be used to determine timing of epiphysiodesis and predict bone length at skeletal maturity, growth remaining, and congenital and developmental limb-length discrepancy.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

Multiplier method for predicting adult foot length

Lower and upper limb lengths and total height can be predicted by the multiplier method. The multiplier is a coefficient that corresponds to each age and gender. The coefficient for any age can be multiplied by the length at that age to give the length at skeletal maturity. Our purpose was to calculate foot length multipliers and determine whether they are independent of percentile, much like the multipliers for lower and upper limb lengths and total height. Foot length multipliers were calculated from 3 separate previously published databases of foot length in children. The multipliers were calculated by dividing foot length at maturity by foot length at each respective age for each percentile and for both genders. The multiplier values for each percentile group at each age were found to be relatively equivalent, with little variability (as was found for the validated multipliers for lower limb length and total height). Also, little variability was found among multipliers calculated from different databases. In addition, we compared foot length multipliers with lower limb, upper limb, and total height multipliers. Compared with lower limb (tibial and femoral) multipliers, the foot length multipliers were significantly different because the foot achieves a higher percentage of maturity length earlier than does the femur or tibia. Because prediction of limb length and limb length discrepancy can be achieved accurately by using the lower limb multiplier, it is also likely that the foot length multiplier can be used to predict foot length and foot length discrepancy at maturity.