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Background
Plantar calcaneal spurs are common, however their pathophysiology is poorly understood. This study aimed to evaluate the prevalence and correlates of plantar calcaneal spurs in a large sample of older people.
Methods
Weightbearing lateral foot radiographs of 216 people (140 women and 76 men) aged 62 to 94 years (mean age 75.9, SD 6.6) were examined for plantar calcaneal and Achilles tendon spurs. Associations between the presence of spurs and sex, body mass index, radiographic measures of foot posture, self-reported co-morbidities and current or previous heel pain were then explored.
Results
Of the 216 participants, 119 (55%) had at least one plantar calcaneal spur and 103 (48%) had at least one Achilles tendon spur. Those with plantar calcaneal spurs were more likely to have Achilles tendon spurs (odds ratio [OR] =2.0, 95% confidence interval [CI] 1.2 to 3.5). Prevalence of spurs did not differ according to sex. Participants with plantar calcaneal spurs were more likely to be obese (OR=7.9, 95% CI 3.6 to 17.0), report osteoarthritis (OR=2.6, 95% CI 1.6 to 4.8) and have current or previous heel pain (OR=4.6, 95% CI 2.3 to 9.4). No relationship was found between the presence of calcaneal spurs and radiographic measures of foot posture.
Conclusions
Calcaneal spurs are common in older men and women and are related to obesity, osteoarthritis and current or previous heel pain, but are unrelated to radiographic measurements of foot posture. These findings support the theory that plantar calcaneal spurs may be an adaptive response to vertical compression of the heel rather than longitudinal traction at the calcaneal enthesis.
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Last edited by Admin2 : 11th August 2008 at 04:04 PM.
Reason: linked to authors profiles
I find the conclusion statements very interesting in that it only refers to planter calcaneal spurs and not to the achilles insertional spurs.
I have not read the paper so can only go on what was lised in the abstract.
It seems to me that seeing the numbers of patients who commonly have both a plantar spur and achilles spur that the two are related as the paper claims. If this is so then how exactly is the achilles spur created from compression due to obesity?
I still view these problems, especially when seen in conjunction, as being caused by prolonged tension regardless of what the radiologic foot posture may be.
" These findings support the theory that plantar calcaneal spurs may be an adaptive response to vertical compression of the heel rather than longitudinal traction at the calcaneal enthesis."
And how did we conclude this????????
The only conclusion I would draw is that those measurements selected did not predict the formation of heel spurs.
Period.
Steve
__________________
DrSArbes
Fellow American College of Foot & Ankle Surgeons
Board Certified Foot & Ankle Surgery, ABPS
Green Bay, Wisconsin, USA
These findings support the theory that plantar calcaneal spurs may be an adaptive response to vertical compression of the heel rather than longitudinal traction at the calcaneal enthesis.
Quote:
Originally Posted by drsarbes
The only conclusion I would draw is that those measurements selected did not predict the formation of heel spurs.
Agreed. I can see nothing the the paper that supports the conclusion drawn by the authers that supports the theory its due to adaptive response to vertical compression.
If we actually look at the anatomy of the foot, and new research from Simon Smith (and others), we can say that the spur formation seems to occur in the tendon insertion of the flexor digitorum brevis, not in the more superficial plantar fascia insertion. Thus if the spur formation in on a deeper structure, it is not on a directly weightbearing structure, thus cannot be due to compression? Also re-enforces Bruce's comment regarding 'compression' causing the achillies spur formation. In my head, traction causing spur formation makes sence, and tension over time on a bony prominence will cause bony adaptation (an adaptation of Wolf's Law I think?).
Ideas?
__________________
Adrian Misseri
B.Pod.,M.Hlth.Sci.(Pod.)
I appreciate your interest in the paper, which is admittedly speculative and intentionally raises more questions than it answers. I am by no means dogmatically fixated on compression as the cause of spurs, but do believe that it is a hypothesis worth considering (this is why the title of the paper is a question rather than a statement).
There's no point simply restating what is in the paper, but in response to some specific issues raised:
Bruce said:
Quote:
I have not read the paper so can only go on what was lised in the abstract. It seems to me that seeing the numbers of patients who commonly have both a plantar spur and achilles spur that the two are related as the paper claims. If this is so then how exactly is the achilles spur created from compression due to obesity?
Sorry Bruce, but there's no excuse for only reading the abstract, as the full text of the paper is freely available on the website. We do not argue that Achilles tendon spurs are related to compression.
drsarbes said:
Quote:
The only conclusion I would draw is that those measurements selected did not predict the formation of heel spurs. Period
This is a reasonable conclusion based solely on the lack of association between foot posture measurements and spurs. However, we believe that this observation, in conjunction with the very strong association between obesity and spurs (and previous histological findings) justifies our speculation as to the possible underlying mechanism of spurs.
Adrian said:
Quote:
If we actually look at the anatomy of the foot, and new research from Simon Smith (and others), we can say that the spur formation seems to occur in the tendon insertion of the flexor digitorum brevis, not in the more superficial plantar fascia insertion. Thus if the spur formation in on a deeper structure, it is not on a directly weightbearing structure, thus cannot be due to compression? Also re-enforces Bruce's comment regarding 'compression' causing the achillies spur formation. In my head, traction causing spur formation makes sence
Simon Smith's paper also suggests that compression may be the cause of spurs rather than traction. His findings are consistent with those of Kumai and Benjamin who first suggested that compression may play a role. Spurs in the FDB would still be subject to compression associated with weightbearing despite being located deep to the plantar fascia.
I agree with Adrian that the traction hypothesis "makes sense" - at least to some extent. However, as stated in the paper, there are several inconsistencies in the literature that can be (at least partly) explained by the compression hypothesis. On balance, our results seem to be more consistent with compression as the cause rather than traction.
In my opinion, the two key observations that don't sit well with the traction hypothesis are:
i. Spurs can reform after surgical release of the plantar fascia
ii. The trabecular pattern of a spur (which is indicative of the direction of the stresses applied to bone) is vertically, not horizontally oriented
There may of course be several possible explanations for these observations that can be explained within the framework of the traction hypothesis, but I can't think of any. Any ideas?
__________________
Cheers,
Hylton
Hylton B. Menz, PhD
Associate Professor and Reader
NHMRC Australian Clinical Research Fellow
Director, Musculoskeletal Research Centre
La Trobe University
Looking at the idea that the calcaneal spur could be a combination of traction and compression, and going along with the bony remodling due to stress idea, there would still have to be vertical trabeculation within the spur as it needs to be resistive to compressive GRFs, otherwise it would be brittle and we'd clinically see a multitude of fractures to the spurs?
Cheers for the feedback Hylton!
__________________
Adrian Misseri
B.Pod.,M.Hlth.Sci.(Pod.)
I agree that plantar compression stresses from ground reaction force (GRF) on the calcaneus may cause plantar heel pain (which I have been lecturing on for years) . Here is a discussion I wrote just about six months ago on Podiatry Arena regarding my thoughts on the subject.
Quote:
Originally Posted by Kevin Kirby
Plantar fasciitis" as we currently call it, is probably not just one diagnosis, but several diagnoses. Certainly, even though the pain in "plantar fasciitis" is generally in or directly adjacent to the central component of the plantar aponeurosis (the correct anatomical name for the "plantar fascia"), it may be caused by different forces. For example, "distal plantar fasciitis", where the pain is only within the longitudinal arch of the foot, is nearly always caused by increased magnitudes of plantar fascial tensile force. But in "proximal plantar fasciitis", where the pain is plantar to the medial calcaneal tubercle (the origin of the central component of the plantar aponeurosis), the pain may be caused both by an increased magnitude of compression force from the plantar heel hitting the ground too hard and/or an increased magnitude of tensile force within the plantar fascia.
The problem is that when a patients presents to us with plantar heel pain and we tentatively make a diagnosis of proximal plantar fasciitis, we may not know if the injury was initially caused by compression forces on the plantar heel (e.g. walking barefoot on a tile or hardwood floor at home, plantar fat pad atrophy that decreases the natural cushioning force on the plantar calcaneus) or by a tensile force that is causing a traction injury to the plantar fascial origin site on the plantar calcaneus. This variable biomechanical etiology of what we call "plantar fasciitis" may directly influence our ability to get these patients all better and how these patients respond to various treatments.
I tend to doubt that plantar calcaneal spurs are caused by compression stresses from GRF for these biomechanical reasons:
1. GRF plantar to the calcaneus is maximal on the plantar aspect of the medial calcaneal tubercle, not on the anterior aspect of the medial calcaneal tubercle, where plantar calcaneal spurs are located.
2. Osseous exostoses in the human and animal body are more commonly caused by tensile forces over time, rather than by compression forces.
3. There are significant plantar tensile forces within the plantar intrinsics that originate from the anterior aspect of the medial calcaneal tubercle where plantar calcaneal spurs are found (specifically the flexor digitorum brevis attaches directly to the part of the anterior aspect of the medial calcaneal tubercle where plantar calcaneal spurs are found, in the surgeries I have performed for plantar spurs).
4. Finite element analysis studies of the plantar calcaneus have demonstrated tensile forces acting on the area of the calcaneus where plantar calcaneal spurs form, not compression forces (Wu L: Nonlinear finite element analysis for musculoskeletal biomechanics of medial and lateral plantar longitudinal arch of Virtual Chinese Human after plantar ligamentous structure failure. Clin Biomech, 22:221-229, 2007).
5. Obesity (i.e. increased body weight) likely increases not only the GRF on the plantar calcaneus but also will increase the tensile forces within the plantar fasia and plantar intrinsic muscles during weightbearing activities (Erdimir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA: Dynamic loading of the plantar aponeurosis in walking. JBJS, 86A:546-552, 2004). There is also a direct relationship between Achilles tendon tensile force and plantar fascial tensile force (Erdimir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA: Dynamic loading of the plantar aponeurosis in walking. JBJS, 86A:546-552, 2004; Carlson RE, Fleming LL, Hutton WC: The biomechanical relationship between the tendoachilles, plantar fascia and metatarsophalangeal joint dorsiflexion angle. Foot Ankle Intl., 21:18-25, 2000). This all makes good biomechanics sense to me since your study found traction spurs both on the plantar calcaneus and posterior calcaneus, which is a very common occurence from what I have seen in the thousands of patients I have seen with posterior and plantar calcaneal spurs in my 25 years of clinical practice.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Thanks for your thoughts on the paper. In response to your comments:
Quote:
1. GRF plantar to the calcaneus is maximal on the plantar aspect of the medial calcaneal tubercle, not on the anterior aspect of the medial calcaneal tubercle, where plantar calcaneal spurs are located.
The fact that GRFs are lower on the anterior aspect of the medial calcaneal tubercle doesn't, in itself, mean that compression can't lead to spurs, as there will still be some degree of compression occuring to structures in this area.
Quote:
2. Osseous exostoses in the human and animal body are more commonly caused by tensile forces over time, rather than by compression forces.
Not everyone would agree with this. Fibrocartilage, which is evident in spurs, is also found in tendons which wrap around bony prominences and are subject to compressive loads. There are several lab-based studies which demonstrate growth of fibrocartilage in tendons when compression is applied (for a good review, see Fibrocartilage in tendons and ligaments - an adaptation to compressive load - full text link).
Quote:
3. There are significant plantar tensile forces within the plantar intrinsics that originate from the anterior aspect of the medial calcaneal tubercle where plantar calcaneal spurs are found (specifically the flexor digitorum brevis attaches directly to the part of the anterior aspect of the medial calcaneal tubercle where plantar calcaneal spurs are found, in the surgeries I have performed for plantar spurs).
No disagreement here. I'm not arguing that there are no tensile forces, I'm just questioning whether these tensile forces are responsible for the spur.
Quote:
4. Finite element analysis studies of the plantar calcaneus have demonstrated tensile forces acting on the area of the calcaneus where plantar calcaneal spurs form, not compression forces (Wu L: Nonlinear finite element analysis for musculoskeletal biomechanics of medial and lateral plantar longitudinal arch of Virtual Chinese Human after plantar ligamentous structure failure. Clin Biomech, 22:221-229, 2007).
Not strictly correct. Both tensile and compressive forces are demonstrated in this paper, but again, I'm not arguing that there's no tensile forces.
Quote:
5. Obesity (i.e. increased body weight) likely increases not only the GRF on the plantar calcaneus but also will increase the tensile forces within the plantar fasia and plantar intrinsic muscles during weightbearing activities
No disagreement here, and this mechanism probably explains the relationship between obesity and chronic plantar heel pain (but not necessarily spurs).
I suspect that we probably won't reach agreement on this, which is OK as both opposing hypotheses have some degree of merit. The idea behind our paper was to simply report associations between obesity, foot posture, OA and spurs, and we believe that our findings sit more comfortably within the compression framework than the traction framework. Obviously there's lots more work to be done in the area before definitive conclusions can be reached.
If anyone is interested in exploring the idea of compression leading to spurs further, I strongly recommend Kumai and Benjamin's paper. I've uploaded the PDF to this post. Sorry for the poor quality, but it's a scan from an old hard copy of mine.
__________________
Cheers,
Hylton
Hylton B. Menz, PhD
Associate Professor and Reader
NHMRC Australian Clinical Research Fellow
Director, Musculoskeletal Research Centre
La Trobe University
Thanks for replying to my posting. I enjoy having academic discussions with you.
My little time away from Podiatry Arena, I thought, would be much longer than the 5 weeks I took off. I had so many projects and lectures lined up at the time, that I needed to take some time away from posting to Podiatry Arena, even though I was still reading a few posts here and there during that time. Thanks for your concern.
I reread the paper by Wu on finite element analysis of foot stresses with sectioning of the plantar fascia and can find no where in the paper where they state that the area of the anterior aspect of the medial calcaneal tuberosity where calcaneal spurs grow has a focus of increased magnitudes of compression stresses that would be a reasonable explanation for formation of a spur in that non-weightbearing area of the calcaneus. Possibly you can post the quote from his paper that shows that compressive stresses in this area of the calcaneus are intensified in this area of the calcaneus, where the flexor digitorum brevis (FDB) originates from.
An obvious question is that if you can't find a reason or any references that show a focus of increased magnitudes compressive stresses acting at this non-weightbearing area of the calcaneus where plantar calcaneal spurs are commonly found, then why don't calcaneal spurs also grow on the medial or lateral body of the calcaneus also? Certainly the medial and lateral aspects of the medial calcaneal tubercle must receive similar magnitudes of compressive stresses to the anterior aspect of the medial calcaneal tubercle, but I have never seen even a 1-2 mm calcaneal spur in this area on my calcaneal axial radiographic views, whereas I have surgically removed plantar calcaneal spurs over 10 mm in length. If compression is the most likely cause of plantar calcaneal spurs, then why don't other areas of the calcaneus, which are under even more compression stresses, also grow spurs???
In rereading Wu's paper, they note that the flexor digitorum brevis (FDB) has considerable tensile stresses within it, especially with sectioning of the plantar fascia. In the many cadaver specimens I have dissected, and in the patients I have surgically removed calcaneal spurs from, the spur is just superior to the central component of the plantar aponeurosis (1-2 mm superior). This corresonds to the very thin slice of anterior aspect of the medial calcaneal tubercle where the FDB originates from.
I feel it is much more likely that the plantar calcaneal spurs that we see in adult feet are the direct result from the considerable tensile forces from the FDB pulling on a very thin slice of the anterior aspect of the medial calcaneal tubercle so that the tensile stress (force/surface area of attachment) on this area of the calcaneus is significantly increased so that ectopic bone if formed from the repetitive irritation to the periosteal elements in this small region of the calcaneus. I just can't imagine how enough compressive stresses somehow "reach up" to this non-weightbearing area of the anterior aspect of the medial calcanel tubercle to cause this isolated growth of an exostosis in a large number of adult feet.
Good discussion.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Calcaneal spurs - traction or compression?
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