X-Ray Musculoskeletal Conditions of the Foot and Ankle part 2

Acquired: things that happen after we are born and cause the mechanics of the foot and ankle to alter (may be caused by congenital abnormalities or feet can be normal at birth)

Acquired Musculoskeletal Conditions:

• Osteochondritis/ Osteochondrosis

• Hallux Valgus

• Hallux Rigidus

• Osteoarthritis

• Pes Planus

• Calcaneal Spur

Osteochondritis:

Osteochondritis = “bone cartilage inflammation”

• Sometimes referred to as Osteochondritis Dissecans or Osteochondrosis

• Probably an abnormality of the bone’s vascular supply, but other factors such as acute or chronic trauma may be contributory

• The configuration of the bone is important – curved articular surfaces are at greatest risk

• End result is premature secondary osteoarthritis

Bone Density - factors :

• Blood supply

• Calcium metabolism

• Hormonal effects

Bone Density – descriptive terms:

• Sclerosis – bone denser than normal (whiter on x rays)

• Osteopaenia – bone less dense (blacker on x rays)

• Osteoporosis – histological not radiological diagnosis

Bone Density – blood supply;

• Too much blood – hyperaemia- reduction in bone density (osteopaenia)

• Too little blood – bone density gradually increases

• No blood – very dense bone – the radiological end point of osteochondritis Bone

Osteochondritis in the ankle and foot:

• Talar dome

• Navicular (Kohler’s disease)

• Metatarsal head (

Freiberg’s

• Usually 2nd or 3rd metatarsal (also commonest sites of stress fracture)

• Presents with pain in affected joint, worse on walking or standing

• 14-18 years old typically

• F:M = 5:1

• At least 30% of the adult foot x rays I look at have some degree of flattening of the head of the 2nd metatarsal

• Implies many sub-clinical cases

• Treatment depends on extent of abnormality

Ostechondritis Grading/Staging System

• There are several different grading systems – can cause confusion

• Freiberg’s – Smilie, Gauthier and Elbaz, Thompson and Hamilton

• Most grading systems start with Grade 0/I representing “normal radiographs” or “subclinical lesion” because MR and Isotope scanning are more sensitive

• Most grading systems extend to Grade IV “detached fragment” via Grade III “stable undetached fragment” Sever’s Disease

• 8-13 years old

• Heel pain +/- limp

• Actually an apophysitis (similar to Osgood-Schlatter’s disease)

• Clinical not radiological diagnosis

Hallux Valgus

• The commonest foot deformity

• Involves the 1st metatarso-phalangeal joint

• Commoner in women than men (9:1)

• May be present to a greater or lesser extent in up to 30% adult women • May be related to footwear but there is also a familial tendency

• Weakness of medial soft tissue supporting structures causing proximal phalanx to turn laterally. There is also flattening of the bony ridge on the undersurface of the 1st metatarsal head which normally separates the sesamoids, so that there is lateral drift of these bones (and the flexor tendon).

• First metatarsal deviated medially, widening normal gap between the heads of the 1st and 2nd metatarsals

• Chronic bursitis over inner aspect of 1st metatarsal head = BUNION

Hallux Valgus (Bunion) - treatment:

• Bunion – painkillers, orthotics, bunion pads

• Manipulation therapy

• Deformity – surgery (osteotomy) to restore normal anatomical relationships at the 1st metatarso-phalangeal joint

Hallux Rigidus

• Osteoarthritis of the metatarso-phalangeal joint of the big toe

• Pain in base of big toe on walking

• Osteophytes on dorsal aspect of joint especially – impinge on walking

• F>M

• Onset usually 30-60 years old

Hallux Rigidus - Treatment:

• Symptomatic – painkillers, wide fitting shoes, orthotics.

• Surgery – cheilectomy, arthrodesis

Pes Planus (Flat Foot)

• The tarsal bones by themselves are so shaped that when they articulate they tend to form a straight line rather than a curve

• Normal human foot has 2 arches – transverse and longitudinal

• These are achieved by soft tissue supporting structures holding the tarsals in a curved configuration

• Both arches are involved in flat foot

• Flat feet are normal in babies and toddlers – increased soft tissue and joint laxity and large amount of plantar fat

• May be symptomatic or not

• Flat foot may be due to congenital abnormality (e.g. tarsal coalition), or be acquired due to failure of the bony or soft tissue structures which maintain the normal arches.

Pes Planus - Treatment:

• Usually based on physically supporting the foot into a position where the arches are restored into a configuration as near normal as possible using orthotics.

• Surgery may involve fusing individual joints or reconstituting tendons Toe deformities

• Hammer Toe

• Claw Toe

Hammer Toe:

• Flexion deformity at PIP joint

• Precise cause unknown – involvement of 2nd toe often seen in Hallux Valgus

• DIP remains mobile but toe rests with it in compensatory hyperextension

• Often callosity/corn overlying dorsal aspect of PIP joint

Claw Toe:

• Flexion deformities at PIP and DIP joints

• May be related to footwear

• Can be associated with Diabetes Mellitus

Calcaneal Spur

• Radiographic imaging is not indicated routinely

• Plantar spurs are common incidental findings

• There is no direct relationship between the presence or absence of a bony spur on plain films and the symptom of heel pain (Grade B evidence – robust experimental or observational studies) • 16% asymptomatic people have them present on images performed for other indications

• Present in only 50% of symptomatic patients (please feel free to toss a coin rather than x-ray the heel)

Summary

• Think about the normal anatomy of the foot – the individual bones, their shape, their density, their relationship to other bones, and the overall configuration of the foot

• Remember normal variations in the shape and number of bones

• Look at everything – take your time: “If you look at everything, you’ll see everything”

• If you are using a staging/grading system, make sure it’s one that is universal within your practice

• Please when you refer a patient for plain films speak to the Lab and tell what are you looking for.