SLR - September 2014 - Nida Nawaz

Gait Patterns in Children with Limb Length Discrepancy

Reference: Aiona M, Do KP, Emara K, Dorociak R, Pierce R. Gait Patterns in Children With Limb Length Discrepancy.  Journal of Pediatric Orthopedics. 29 July 2014.  

Scientific Literature Review

Reviewed By: Nida Nawaz, DPM  
Residency Program: DVA Puget Sound

Podiatric Relevance: This article is a level II study that determines various gait patterns in 45 pediatric patients with limb length discrepancies (LLD) and evaluates the gait kinetics affected by the patients’ compensation. Podiatric physicians commonly come into contact with patients with limb length discrepancies that lead to painful joints related to compensation in gait. Although this article did not compare the differences between treatment groups it gives a physician a strong understanding of the level at which the LLD will effect (ex: hip vs ankle) and it gives one insight on when or whether or not early surgical/treatment intervention is warranted or not. Using the information contained in this article, podiatric physicians can better determine from their gait analysis,  at what level the LLD , which allows them to provide the appropriate treatment and better educate their patient’s in regards to what joint(s) may become affected in their future. The author’s clinical question in this study was could the various gait patterns seen in pediatric patients with LLD be defined and correlated to specific compensation on gait kinetics.

Methods: Inclusion criteria for this study included pediatric patients with a LLD of > 2cm that did not have an associated neuromuscular disorder that could independently alter the biomechanics of gait. Forty-five pediatric patients with LLD, measured with a scanogram were enrolled in this study. The patient’s gait patterns were videotaped, using 13 reflective markers placed on the lower extremity according to the model described by Vicon Clinical Manager. Kinetic data was measured utilizing two force plates instrumented with strain gauges, with the patients performing four force plate strikes for each extremity. The  mechanical work was also measured for all study patients and then was compared to a the study patient’s contralateral limb, as well as to a  control group that consisted of 20 developing children that had no statistical difference in age to the study group and did not have an LLD. Four compensatory strategies were defined quantitatively, kinetically, consisting of (1) pelvic obliquity; (2) flexion of the knee; (3) plantarflexion of the angle; and (4) vaulting. Statistical analysis consisted of Paired t tests to analyze the work differences between the limbs in the LLD study patients and unpaired tests were used to compare between four groups (short femurs, short tibias, both, or control groups).

Results: The average LLD in the study population was 4.6cm (range 2 to 12.2cm. Of the 45 patients in the study, 18 had a LLD related to a short femur, nine due to a short tibia, and 18 had shortening in both the femur and the tibia (both).  Both the size of the length difference and the location of the length difference were important factors in determining the compensated gait strategy for the study patients. It was noted that those that had a LLD of > 7cm all used a combination of gait compensation strategies, while only 27 percent of those with a LLD of > 4cm, but < 7cm used a combination of gait strategies.

Study data also showed that contrary to the common clinical belief that otherwise healthy LLD patients develop compensation strategies to maintain a level pelvis in gait, 54 percent of those in this study had a persistent pelvic obliquity in gait.

Work load was also determined to be greater in the longer limb, generally, with the location of the increased work load in the longer limb being related to the location of the LLD. It was determined that shortening in the femur resulted in increased workload  at the ankle, where shortening of the tibia resulted In increased workload in the hip on the shorter extremity and increased total work on the long side, while simultaneously decreasing work load of the shorter extremity ankle. Finally, there appeared to be no statistically significant difference in the walking velocity measured in the study patients when compared to the control group.
 
Conclusions: The authors concluded that their study data demonstrated that a high number of LLD patients have pelvic obliquity in gait than previously believed by clinicians. They also determined that the LLD location and size of the discrepancy significantly impacted the type and number of gait compensations utilized by the LLD patient. I believe that this study is important to podiatric physicians as we frequently see patient’s with foot/ankle pain that may have a diagnosed or undiagnosed LLD. With the ability to recognize LLD gait compensation patterns and having a good understanding of the impact that the size and location/level of the LLD, we can provide the patient better treatment options, as well as educate patients on the possible long-term impact of their specific type of LLD on joint health and inform them of the risks on specific joints related to their LLD. 

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