RESEARCH
What is being quoted was published in 1979. Tsukasa Kumai and Mike Benjamin found in their paper heel spur formation and the subcalcaneal enthesis of the plantar fascia published in ‘The Journal of Rheumatology’ in 2002. The objective of this study was to describe the structure and significance of subcalcaneal heel spurs associated with the plantar fascia. Methodology consisted of the removal of 17 enthesis of the plantar fascia from elderly cadaver specimens using a surgical saw cut either side of the medial tuberosity. The results of the study showed that heel spurs developed on the deep surface of the plantar fascia but their formation is halted due to degenerative changes that occur within it. Kumai and Benjamin reported a difference between small and large spurs. They proposed three stages of spur development these being:-
(1) An initial formation of cartilage cell clusters and fissures at the plantar enthesis;
(2) Thickening of the subchondral bone plate at the enthesis as small spurs form; and
(3) Development of vertical oriented trabeculae buttressing the proximal end of a large spur.
Their conclusion was “contrary to popular belief subcalcaneal heel spurs cannot be a traction spur as they do not develop within the plantar fascia itself. They are thus fundamentally different from heel spurs in the achillis tendon. We suggest instead that they develop as a consequence of degenerative changes that occur in the plantar fascia enthesis.”
In 2003 in skeletal radiography M. Abreu et al presented a paper on plantar calcaneal enthesophytes new observations regarding site of origin based on radiographic, MR imaging, anatomical, and paleopathologic analysis. The objective of this study was to determine the relationship between the site of a calcaneal plantar enthesophytes and the surrounding soft tissue structures using routine radiography. Two observers analyse the MR imaging studies of 40 ankles in a total of 30 patients, 35 male, three female with a mean age of 48.3 years with existing plantar calcaneal enthesophytes that were selected out of all the ankle examinations performed during the previous year. The results were as follows. The size of the enthesophytes, its location in relation to the plantar fascia and the flexor muscles and the thickness and significance of the plantar fascia were observed. The results after careful observation with regard to the MR imaging were as follows. The mean size of the plantar enthesophytes was 4.41 millimetres with a standard deviation of 2.4. 50% had enthesophytes that were located above the plantar fascia, 40% between the plantar fascia and the abductor digiti minumi and the flexor digitorum brevis and abductor hallucis muscles and only 3% were located within the plantar fascia itself there. The conclusion of the study found that plantar calcaneal enthesophytes arise in five different locations. These being the insertion sites of the abductor digiti minumi and the flexor digitorum brevis muscles, between the plantar fascia and these muscles and less frequently within the plantar fascia itself and at the insertion site of the short plantar ligament.
Prichasuks, Subhadrabandhu T. presented a study of the relationship of pes planus and calcaneal spur to plantar heel pain printed in ‘Clinical Orthopaedic’ in 1994. It showed a prospective study of pes planus by using calcaneal pitch and calcaneal spur was carried out in 82 patients with plantar heel pain and in 400 normal subjects. The mean normal calcaneal pitch was 20.54 degrees. Patients with a plantar calcaneal pain had a mean calcaneal pitch of 15.99 degrees, significantly lower than normal subjects. They conclude the incidents of calcaneal spur was 15.5% (62 of 400) and 65.9% (54 of 82), respectively. Increase weight gain, aging are some of the important factors affecting the rolling of the pitch and the increase of spur formations. These factors contribute to the development of plantar heel pain. The current research indicates that there is no relationship between the tensioning pressure put of the plantar fascia and the formation of the heel spur.
So where does that leave us as clinicians? Daily we can all read that it is the pull of the plantar fascia that causes a heel spur however current research begs to differ could this be due to Wolf’s Law that being essentially stresses and strains placed on the bone caused by outside sources cause the spur therefore it must be pulled out by the plantar fascia.
Heel spur formation at the medial condyle may occur due to the reaction of weight overload suffered by the musculature at the calcaneus. Cal PM “a comparative radiological examination for unresponsive plantar fasciitis” looked at a bilateral lateral weight bearing radiograph of patients whereby weight overloading of the musculature lead to heel pain. The tissue suffered excessive plantar spasm which prevented normal movement of the hind foot. It is suggested that this plantar spasm results from posterior calcaneal subluxation and or loss of normal independent joint motion at the subtalar and tarsal articulations leading to an inability for normal hind foot elongation. Interior manipulation is performed using either an activator instrument or a Thompson dropped piece table using a series of treatments until the pain is relieved. The study quoted approximately 70% of patients will show a 40%-100% improvement in calcaneal alignment. Thus increasing the question as to what is causing the pain in the heel and plantar fascia.
In the October edition of ‘Clinical Anatomy’ Li J, Muehleman C. presented a paper entitled Anatomic relationships of heel spurs to surrounding soft tissue: greater variability than previously reported.
“The stimulating factor for the development of heel spurs (calcaneal exostosis) is controversial. In a sample of elderly cadaveric specimens, using radiographic, gross morphological and histological investigation, we demonstrate that heel spurs are generally not found in the trajectory of traction from the plantar aponeurosis entheses or plantar muscles. Rather, they are variably associated with soft tissues including loose connective tissue, fibrocartilage, muscle, and aponeurosis. Furthermore, the bony trabeculae of the spur are not aligned in the direction of the soft tissue traction, but rather in the direction of stress on the calcaneus during walking and standing. These results substantiate the view that the heel spur may be a skeletal response to stress and may serve to protect the bone against the development of microfractures.”
The surgical question arises that if transecting the plantar fascia eliminates the tensile forces from the plantar fascia on the medial calcaneal tuberosity and there is a resultant decrease in pain with an existing calcaneal spur, is the resultant decrease in pain due to a decrease in tension or a decrease in compression of the area. It is believed that most plantar heel spurs are asymptomatic and that not all people with proximal plantar fasciitis have an existing plantar heel spur. The question continues regarding the tensile stresses placed on a plantar fascia and the surrounding musculature and the formation of heel spurs.
