Plantar fasciitis is the most common cause of inferior heel pain (fig 1). Its aetiology is poorly understood by many, which has led to a confusion in terminology.1 It is said to affect patients between the ages of 8 and 80, but is most common in middle aged women and younger, predominantly male, runners. 2The role of the doctor in the management of plantar fasciitis is to make an appropriate diagnosis and to allow enough time for the condition to run its course, with the aid of supportive measures. If treatment is begun soon after the onset of symptoms, most patients can be cured within six weeks. MethodsThis article is based largely on our experience and recent concepts that have changed our management of inferior heel pain. Reviews written by experts have been supplemented by selected original articles cited in Medline between 1976 and 1995 and published in high quality journals. We used the following keywords for the Medline search: plantar fasciitis, inferior heel pain, heel spur, calcaneodynia. AetiologyThe plantar fascia is a strong band of white glistening fibres which has an important function in maintaining the medial longitudinal arch: spontaneous rupture or surgical division of the plantar fascia will lead to a flat foot.4 5 The plantar fascia arises predominantly from the medial calcaneal tuberosity on the undersurface of the calcaneus, and its main structure fans out to be inserted through several slips into the plantar plates of the metatarso-phalangeal joints, the bases of the proximal phalanges of the toes and the flexor tendon sheaths. Just after heel strike during the first half of the stance phase of the gait cycle, the tibia turns inward and the foot pronates to allow flattening of the foot. This stretches the plantar fascia. The flattening of the arch allows the foot to accommodate to irregularities in the walking surface and also to absorb shock.If there is a predisposing or aggravating factor (box), the repetitive traction placed on the plantar fascia during walking or running may lead to microtears (fig 2), which induce a reparative inflammatory response. 6 Biopsy specimens of the inflamed fascia show fibroblastic proliferation and chronic granulomatous tissue.1 6 A normal plantar fascia has a dorsoplantar thickness of 3 mm; in plantar fasciitis this can be 15 mm.

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Opportunistically breeding species offer the unique opportunity to understand mechanisms in reproductive physiology that allow for extreme flexibility in the regulation of reproduction. We studied a well-known opportunistic breeder, the zebra finch (Taeniopygia guttata) to test the hypothesis that the reproductive axis of opportunists is in a constant state of ‘near-readiness’. In wild zebra finches, reproduction is highly correlated with rainfall, and in the laboratory, water availability and humidity are the strongest cues to affect reproductive activation. We therefore subjected individuals to water restriction for eleven weeks followed by a two week period of ad libitum access to water. The control group had water freely available for the entire experiment. We measured the state of activation of the hypothalamo-pituitary gonad (HPG) axis at three levels: in the hypothalamus by measuring immunoreactive (ir) cGnRH-I and cGnRH-II; in the anterior pituitary gland by measuring plasma luteinizing hormone (LH); and in the gonads by measuring gonadal volume and function. We found that water restriction caused a reduction in circulating LH concentrations and that testis volume was more likely to decrease in water restricted than in control birds. Subsequent short-term return to ad libitum water availability caused LH to return to baseline in water restricted birds. These changes occurred without significant changes in ir-cGnRH-I, ir-cGnRH-II, or in testis function. These data suggest that in these opportunistic breeders, an inhibition of parts of the reproductive axis is not necessarily correlated with full inactivation of reproductive potential. GnRH-ir cells in the hypothalamus appear to remain active and able to respond to subsequent stimulation.

Epidemiologic study, level III.