Via Research Recognition Day Program VCOM-Carolinas 2025

Clinical Educational Research

A Closer Look at Foot Height as a Cause of Unplanned Limb Length Difference in Fibular Hemimelia Patients Ashley Startzman, DO; Luke Hedrick OMS II

1. Shriners Hospital, Orthopedics, Greenville, SC. 2. VCOM, Spartanburg, SC

Introduction

Results

Discussion

Fibular hemimelia (FH) is a congenital disorder of unknown etiology that leads to a spectrum of lower limb deformities including foot hypoplasia. The quantitative foot height effects have not been well described in this population. Treatment algorithms for FH address limb length and foot height separately. Indicated treatments require accurate predictive measurements of limb length at skeletal maturity for best outcomes. The multiplier method and the Mosley straight line graph are two tools currently used for predictive measurements of final limb length at skeletal maturity. Both tools were developed in the mid- 1900’s with far inferior technology than what is available today. Both tools do not take foot height into consideration. In patients with FH, including foot height in the calculation of total limb length will result in more accurate predictions of limb length inequality at skeletal maturity compared to traditional methods that exclude foot height. • Single institution retrospective review from January 2008 – January 2018 with at least two limb alignment radiographs at separate time points. • Inclusion criteria: 1. FH diagnosis, 2. Adequate imaging (not standing on toes, block height included in x-ray). • Exclusion criteria: 1. Additional skeletal dysplasia, 2. Bilateral fibular hemimelia, 3. Inadequate radiographs. • On full length standing radiograph, a line is drawn across: 1. plafond, 2. distal medial femoral condyle, 3. top of hip, 4. top of iliac crest. • Values were recorded and statistical analysis was performed. Methods

• 19 patients met inclusion criteria

• We propose changing the definition of limb length to: Total lower limb length, the distance from iliac crest to the distal calcaneus. • Accurately measuring the total limb length inequality is important when surgically planning to optimize outcomes, and we suggest that models should include foot height. • Further prospective investigation into surgical outcomes with foot height being taken into consideration. • Does ankle surgery affect limb length outcomes. (SUPERankle, Coalition surgery, SHORDT procedure). Conclusions • The foot height difference can be calculated using the differences in the tibial plafond measurements on a standing limb radiograph

• 9 Left

• 10 Right

• All physes open

• Achterman-Kalamchi classification: • 1A: 16, 1B: 2, 2: 1

• Birch classification:

• 1A: 15, 1B: 4, 2: 0

Figure 2. Achterman-Kalamchi type 2 classification .

• Fibular hemimelia patients do have significant foot height differences

Table 1. Examining foot height and leg length difference in relation to pelvic obliquity.

• Foot height difference should be considered when predicting leg length difference in fibular hemimelia patients

• Foot height difference + leg length difference = pelvic obliquity • Mann-Whitney U test is 0.98 • Pearson Correlation coefficient 0.99 • The pelvic obliquity unaccounted for in femur and tibia length = within 1.1 mm of foot height difference (range 0-4 mm)

References

1. Paley D, Bhave B, Herzenberg J, et al. Multiplier Method for Predicting Limb-Length Discrepancy. JBJS. 2000; vol 82 A(10):1432-1446 2. Moseley, C. R: A straight-line graph for leg-length discrepancies. J Bone and Joint Surg., 59-A: 174-179, March 1977. 27. Moseley, C. R: A straight line graph for leg length discrepancies. Clin. Orthop., 136: 33-40,1978. 3. Achterman C, Kalamchi A (1979) Congenital deficiency of the fibula. J Bone Joint Surg Br 61:133 – 157 4. Coventry MB, Johnson EW (1952) Congenital absence of the fibula. J Bone Joint Surg Am 34:941 – 955 5. Anderson, M; Messner, MB, Green, WT. Distribution of lengths of the normal femur and tibia in children from one to eightneen years of age. JBJS, 46-A:1197-1202, Sept 1964 6. Aguilar JPD, Paley J, Santpure S, Patel M, Bhave A, Herzenberg JE. Clinical validation of the multiplier method for predicting limb length at maturity, part I.J Pediatr.2005;25:186 – 191

Acknowledgements

• All patients had a foot height difference

Huirong Zhu – Statistician Proposal was granted exemption status.

Figure 3. Pelvic obliquity accounting for limb length and foot height difference .

Figure 1. Three examples of calculated foot height .

2025 Research Recognition Day

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