1 Lecture 2: Normal radiographic anatomy of the foot and ankle cont. Lecture outline 1. Bone anatomy (Lecture 1) 2. Ossification centres (Lecture 1) 3. Accessory bones cont. 4. Other normal variants Os peroneum Lateral and plantar to the cuboid Within the peroneus longus tendon May be multipartite Often bilateral Common: approx. 15% of the population (Dameron, JBJS, 1975) Adapted from Berquist, T.H. (1989). Radiology of the Foot and Ankle. New York: Raven Press Os supranaviculare Os supranaviculare Calcaneus secondarius Os Os vesalianum vesalianum At base of 5th metatarsal At base of 5th metatarsal Rare Rare (1 in 1000, (1 in 1000, Dameron Dameron, 1975) , 1975) Need to differentiate with an apophysis Need to differentiate with an apophysis or an avulsion fracture or an avulsion fracture – Os Os vesalianum vesalianum lies proximal to a well lies proximal to a well- developed tuberosity developed tuberosity – Ossification centre runs longitudinal Ossification centre runs longitudinal – Fracture runs transverse Fracture runs transverse
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1
Lecture 2: Normal radiographic anatomy of
the foot and ankle cont.
Lecture outline
1. Bone anatomy (Lecture 1)
2. Ossification centres (Lecture 1)
3. Accessory bones cont.
4. Other normal variants
Os peroneum
Lateral and plantar to the cuboidWithin the peroneus longus tendonMay be multipartiteOften bilateralCommon: approx. 15% of the population (Dameron, JBJS, 1975)
Adapted from Berquist, T.H. (1989). Radiology of the Foot and Ankle. New York: Raven Press
Os supranaviculare
Os supranaviculare
Calcaneussecondarius
Os Os vesalianumvesalianum
At base of 5th metatarsalAt base of 5th metatarsalRare Rare (1 in 1000, (1 in 1000, DameronDameron, 1975), 1975)
Need to differentiate with an apophysis Need to differentiate with an apophysis or an avulsion fractureor an avulsion fracture
–– Os Os vesalianumvesalianum lies proximal to a welllies proximal to a well--developed tuberositydeveloped tuberosity
–– Ossification centre runs longitudinalOssification centre runs longitudinal–– Fracture runs transverseFracture runs transverse
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Adapted from Berquist, T.H. (1989). Radiology of the Foot and Ankle. New York: Raven Press
Os supranaviculare
Os supranaviculare
Calcaneussecondarius
Some confusion in the literature between os vesalianumand an unfused 5th metatarsal apophysis
Os intermetatarseum
Between the metatarsalsMost common between the base of the 1st & 2ndPositioned dorsallyUsually spindle shapedReasonably common, although frequency varies (0-10%, Sarrafian, 1983)
Adapted from Berquist, T.H. (1989). Radiology of the Foot and Ankle. New York: Raven Press
Os supranaviculare
Os supranaviculare
Calcaneussecondarius
Calcaneus Calcaneus secondariumsecondarium
AKA os calcaneus AKA os calcaneus secondariussecondariusLocated dorsally on the anterior beak of Located dorsally on the anterior beak of the calcaneus between the junction of the calcaneus between the junction of the calcaneus, talus, cuboid and the calcaneus, talus, cuboid and navicularnavicularFrequency 2Frequency 2--11% 11% ((SarrafianSarrafian, 1983), 1983)
DDxDDx: # of the anterior beak of the : # of the anterior beak of the calcaneuscalcaneus
3
Adapted from Berquist, T.H. (1989). Radiology of the Foot and Ankle. New York: Raven Press
Os supranaviculare
Os supranaviculare
Calcaneussecondarius
Accessory bones distal to the tibia and fibula
Common17-24% of females & up to 47% males have ossicles distal to tibia (Berquist, 1989)
Often bilateralCare needed to differentially diagnose with avulsion fracturesMay also get irregular ossification of the distal growth plates
4. Other Normal Variants
i. Accessory sesamoidsii. Nutrient artery channel in a
metatarsal diaphysisiii. Pseudo or simulated calcaneal cystiv. Cone-shaped epiphyseal growth
platesv. Epiphyseal cleftvi. Split epiphyses
4(i) Accessory sesamoids
Small sesamoids predominantly in the forefoot and the digitsUsually located plantarlyCan be multiple in one areaRelatively commonIf plantar to the 1st IPJ, may cause hyperkeratosis due to increased pressure
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Adapted from Berquist, T.H. (1989). Radiology of the Foot and Ankle. New York: Raven Press
Os supranaviculare
Os supranaviculare
4.(ii) Nutrient artery channel4.(ii) Nutrient artery channel
On an oblique projection On an oblique projection the nutrient artery the nutrient artery channel may showchannel may show
Has a characteristic Has a characteristic location in metatarsalslocation in metatarsals
Rarely seen, howeverRarely seen, howeverDDxDDx with stress #with stress #
4(iii) Pseudo or simulated 4(iii) Pseudo or simulated calcaneal cystcalcaneal cyst
Area of radiolucencyArea of radiolucencyin the midin the mid--portion ofportion ofthe body of the the body of the calcaneuscalcaneus
Corresponds to a Corresponds to a decrease in stress of decrease in stress of this part of the bone,this part of the bone,therefore lesstherefore lesstrabeculaetrabeculae
4(iv) Cone4(iv) Cone--shaped epiphyseal shaped epiphyseal growth platesgrowth plates
4(v) Epiphyseal cleft4(v) Epiphyseal cleft 4(vi) Split epiphyses4(vi) Split epiphyses
DDxDDx Salter Harris Salter Harris type fracture of thetype fracture of thegrowth plategrowth plate
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SummarySummary
Must know anatomy and normal Must know anatomy and normal variantsvariantsMany normal variants masquerade as Many normal variants masquerade as pathologypathologyHowever, some normal variants (e.g. However, some normal variants (e.g. accessory navicular) can become accessory navicular) can become problematicproblematic
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