supinatory rock

supinatory rock

visible lateral 'rock' during gait when normal pronation at midstance ceases abruptly and early resupination begins, just before toe off; characteristic of a foot with rigid forefoot valgus (see Table 1)
Table 1: Features of forefoot valgus
PresentationCharacteristics
Rigid forefoot valgusRearfoot relationship to lower leg normal
Non-adaptation of foot during loading, in relation to imposed ground reaction forces under forefoot
Forefoot loads from medial to lateral, i.e. 1 MTPJ to 5 MTPJ (not 5 MTPJ to 1 MTPJ, as in the normal foot)
Little or no available MTJ supination
Excessive supination at the STJ
Reduced contact period pronation
External rotation of the leg with resultant lateral instability of the knee, ankle and STJ
Signs and symptomsIncreased height of the medial longitudinal arch
Calcaneal inversion
Lateral 'rock' during gait due to early stance-phase STJ supination (supinatory rock)
Loss of shock absorption mechanisms in lower limb with induced lower-back, hip, knee and shin pathologies
Reduced MTJ mobility
Retraction or clawing of the lesser toes and triggering of the hallux, with local shoe trauma
Hyperkeratoses of the plantar skin overlying the 1 and 5 MTPJs
Posterolateral calcaneal irritation
Difficulties in obtaining shoes that accommodate the foot deformity
Excess wear on lateral side of sole of shoe
Mobile forefoot valgusRearfoot relationship to lower leg normal
Forefoot loads from medial to lateral, i.e. 1 MTPJ to 5 MTPJ (not 5 MTPJ to 1 MTPJ, as in the normal foot)
The foot is mobile and distorts (pronates excessively) under load, so that the first ray dorsiflexes and the MTJ supinates
The MTPJ unlocks when supinated, with resultant forefoot hypermobility
Signs and symptomsHallux abductovalgus and/or hyperextension of hallux at interphalangeal joint
Lesser-toe deformities, including hammered second toe
Hyperkeratoses of the plantar skin overlying the 2, 3 and 4 MTPJs
Adductovarus of the fifth toe with dorsal and lateral hyperkeratosis
Tailor's bunion
Plantar digital neuritis
Plantar fasciitis and foot strain
Medial sesamoiditis
First metatarsal - medial cuneiform osteoarthritis
Compensatory calcaneal (STJ) pronation leading to Haglund's deformity, medial knee, shin and lower-back pain

MTJ, midtarsal joint; MTPJ, metatarsophalangeal joint; STJ, subtalar joint.