Justin Wernick, DPM, says one of the most common podiatric dilemmas is identifying when to expedite the range of motion at the first metatarsophalangeal joint (MPJ) or when to block range of motion. In the clinical assessment, he says it is important to determine the off-weightbearing range of motion of the hallux. The demand in gait for dorsiflexion of the hallux is 55 to 85 degrees. Dr. Wernick says this is determined by the amount of knee flexion, usually 35 degrees and plantarflexion, which is approximately 25 degrees.
Knowing the length of an individual’s step is very important in this assessment. The longer the step length, the more demand there is for dorsiflexion at the metatarsophalangeal joint, according to Dr. Wernick. He notes that if an individual walks with a rapid cadence or is involved with sports, there will be a greater demand for dorsiflexion. If the range of motion is at least 20 degrees or greater, Dr. Wernick will attempt to expedite motion by:
• supinating the subtalar joint;
• maintaining the medial architecture of the foot; and
• using a Kinetic Wedge™ forefoot modification.
Dr. Wernick notes the wedge is designed to promote the plantarflexion-eversion motion of the first ray via the wedge’s shape (wider medially) and its density (softer under the head).
The wedge’s proximal angle is designed to act as does the first ray axis, says Dr. Wernick, and the distal angle compliments the axis of the hallux. By controlling the rearfoot, he can restore the contour of the arch and increase the plantarflexion angle of the first ray. Combining these efforts with the Kinetic Wedge will increase motion at the first MPJ, notes Dr. Wernick.