Current Pedorthics November-December 2017 - Vol.49, Issue 6 - Page 26

Biomechanical Analysis of an Achondroplastic Dwarf with Limb Length Discrepancy The mutation can present with below average trunk size, symmetric rhizomelic shortening of the extremities at birth 2 , a different schedule of milestone development, excess weight, tibia bowing 3, 4 , foramen magnum compression, recurrent otitis media, dental overcrowding, hearing loss, sleep apnea, hypermobility except for elbow and hip, disturbance of gait with regular falls, and disproportionate short stature 3 . A summation of these deformities can lead to biomechanical abnormalities, such as, limb length discrepancy. Limb length discrepancy can have a profound effect on gait and biomechanical fluidity resulting in a high correlation of injury on short leg side 5 . These patients often present with a pes cavus foot type on the shorter limb and a pes planus foot type on the longer limb. However, these patients often present a varus pressure distribution 6 . Angular deformities of the limbs alter the joint axes and the dynamic distribution of force causing abnormal anatomical stress to be placed on joints leading to the development of osteoarthritis 7 . In our case study, a 40-year-old achondroplastic female dwarf, height 3’6” with a BMI of 58.98, presented with pain on the plantar lateral aspect of her right foot. The patient had not undergone any corrective orthopedic surgeries in the past and her medical history included spina bifida and hydrocephalus. Physical examination revealed pain on palpation of the plantar lateral column of the right foot. Limbs measured bilaterally from the ASIS to the medial malleolus, measuring 45.5cm on the right and 46.0 cm on the left. The patient had a waddling gait with some balance disturbances. The right side appeared to function shorter as she drops down quickly on to the leg through mid-stance into "Limb length discrepancy can have a profound effect on gait and biomechanical fluidity resulting in a high correlation of injury on short leg side" 24 Pedorthic Footcare Association www.pedorthics.org