Pain behaviour Plantar heel pain is exacerbated by load , with reports of ‘ feeling stiff ’ on rising or ‘ start up ’ pain after prolonged inactivity . A short period of movement allows the pain to reduce , although with variability experienced by patients . Clinical experience reminds us that some people suffer considerable pain throughout the day , especially in standing occupations . The next day pain phenomenon – twentyfour-hour response in tendons - is well known . Less work has been done on the response of the plantar fascia , but the patient will need to self-monitor next-day pain when progressing through a load program , being alert for spikes in load and potential flare-ups .
Sedentary populations may fall into the category of the ‘ metabolic ’ tendon . Pioneering work by Jamie Gaida ( 7 ) demonstrated co-morbidities such as increased waist to hip ratio , central adiposity , high cholesterol and hyperglycaemia to be strongly associated with Achilles tendinopathy . Follow-up work ( 8,9 ) by other researchers supports these findings . Less data are available regarding the plantar fascia . Increased Body Mass Index ( BMI ) is more closely related to sedentary populations and listed as a risk factor related to mechanical load ( 10 ), but it may be the metabolic biology that is more important in this population .
Soft tissue that is metabolically challenged , and more specifically connective tissue , suffers from Advanced Glycation End stage ( AGEs ) products . These substances are sticky and tend to infiltrate the connective tissue , forming excessive cross-links . Once this process occurs the connective tissue is unable to store and release energy effectively . Further work needs to be done in this area , but at this stage there are strong anatomical and mechanical similarities to suggest that this occurs in the plantar fascia . The question is : does this change our management ?
Aetiology Aetiology of plantar heel pain is multifactorial , involving load-related extrinsic and intrinsic factors . Extrinsic factors are common across many overload injuries , including increasing volume and intensity too quickly , change in footwear , and change in surface . Intrinsic factors may include changes in loading patterns due to fatigue , gender , age , bodyweight , reduced dorsiflexion ( 11 ), old injuries , reduced calf strength ( 10 ) and unique biomechanics – we don ’ t all run the same !
Pathophysiology Plantar heel pain is a chronic degenerative process involving the plantar aponeurosis of the foot , most commonly at its insertion into the medial tubercle of the calcaneus . Changes are consistent with other tendinopathies , including disorganised collagen arrangement , cleavage between fibrils , and proinflammatory cytokines . Still others conform to parts of the inflammatory model ( 10 ), that is , the pathophysiology of plantar fasciitis can be either inflammatory due to vasodilation and immune system activation , or noninflammatory involving fibroblastic hypertrophy .
Assessment The subjective history in the active population often reports a change in load , new load or a spike in intensity . In the sedentary population there may be obvious BMI considerations and increase in loads such as standing for long periods ; however there are often reports of insidious onset . Plantar heel pain tends to warm up in the early stages , but as the condition progresses the pain is present during and after the offending load . From a clinical perspective next day pain also increases . Palpation will usually elicit pain over the medial calcaneal tuberosity . There may be generalised tenderness over the bulk of the plantar fascia , especially when placed on stretch with hallux extension - Jack test ( Figure 3 ). Imaging is rarely needed to confirm plantar heel pain .
Standing assessment will provide the clinician with information about foot function . There are varying views about whether a pes cavus , or ‘ pronated ’ foot position , is a risk factor for plantar heel pain . Clinically , a pronated position does not always correlate with increased plantar fascia issues , but it is an important observation overall . Identify any calf atrophy ( Figures 1 & 2 ): as noted earlier in the description of the anatomy of the region , the muscle tendon complex of the Achilles is continuous with the plantar fascia . Loss of bulk in the calf may have energy storage and release issues when acting dynamically . Assessment of talar tilt is a good local assessment , providing further information about foot function during gait .
Figure 1 . Assessment of calf bulk in standing , Note loss of bulk on right calf .
16 | vol30 | no1 | JATMS