Plantar Calcaneal Spurs: Is Surgery Necessary?
The etiology of heel pain is quite varied. First described by Wood in 1812, the most common cause is thought to be plantar fasciitis. This is typically marked by focal tenderness to any component of the aponeurosis but most frequently at the proximal medial insertion of the plantar aponeurosis.1 Many symptomatic patients with plantar fasciitis demonstrate plantar heel spurs (traction enthesopathies) of the os calcis. One may best appreciate this shelf of exostosis on the lateral and lateral oblique views of standard radiographic studies.2 On rare occasions, fracture of this spur has been documented in the absence of obvious trauma.3 Frequently, clinicians may also see a lateral view Achilles tendon exostosis at the posterior tuberosity. However, these calcaneal spur formations, particularly the plantar shelf, are also present among patients with no active or prior history of pain. Is the plantar calcaneal spur the culprit or merely an innocent bystander? Be aware that one may mistakenly attribute plantar heel spur formation to excess tension solely from the aponeurosis or fascia. In reality, it is the intrinsic plantar muscles that primarily serve as attachments to the apex of this spur. Researchers have found that the flexor digitorum brevis, as well as the quadratus plantae and the abductor hallucis, arise from this structure.4-6 The abductor digiti minimi remains lateral to the spur attachment and is non-contributory. The plantar fascia attaches inferiorly or below the calcaneal processes or tubercles. The central fascial band is attached to the larger medial plantar tubercle, plantar and slightly posterior to the origin of the FHB. Proximally, the entire aponeurosis sends fibers to blend coherently with the Achilles tendon in the form of a “mesh” at the inferior calcaneus and remains plantar to the spur as a “sling.”4 Theoretically, poor foot mechanics invoking greater intrinsic muscle activity can lead to excessive traction at the tubercle.7 Over time, calcification of the periostitis allows radiographic visualization of the spur. Initially, inferior calcaneal spurs can appear ill-defined and even irregular as with the seronegative arthridites. When clinicians see these spurs with gout, sclerosis and small erosions may accompany them.8 Spur formation can become well defined as one might see with degenerative joint disease, rheumatoid arthritis or advanced plantar fasciitis. The spurs can sometimes appear hook-shaped. Are Heel Spurs Associated With Plantar Fasciitis? Plantar fasciitis often responds to conservative care. In fact, most patients successfully respond to conservative treatment modalities for plantar fasciitis (fasciosis). Traditional strategies include oral steroid and non-steroidal regimens, local injections, strappings, complete or partial offloading, physical therapy, ice, stretching, orthotics, heel cups, night spints and improved shoe gear. Lapidus and Guidotti examined 364 feet and conservative therapy alleviated more than 90 percent of painful heels. When pain resolved in the face of plantar spurring, the spurs remained despite dissipation of the symptomatic inflammation.9 Also keep in mind that one may often see plantar heel spurs in feet that do not exhibit symptoms of plantar fasciitis. Barrett reported that 21 percent of 200 cadaveric feet contained heel spurs although this is a much larger proportion to those with plantar fasciitis in the general population.10 Rubin found that although 21 percent of his patients (125/461) possessed heel spurs, only 13 of them (10 percent with spurs) were symptomatic with heel pain.11 Although Shama, et. al., reported somewhat higher numbers with 39 percent being symptomatic (132 out of 1,000 spurs found), this was still well less than half of all spurs they examined.12 Tanz noted 16 asymptomatic heel spurs among 100 patients on lateral view plain film radiography.13 Therefore, many cases with plantar heel spurs are or become asymptomatic. Conversely, one can safely state that a large percentage of patients with painful plantar fasciitis heel pain lack an inferior calcaneal spur. For example, O’Malley observed that 12 of 19 patients with symptomatic plantar fasciitis had no spur present.14 When Surgery Is Indicated There remains a small subsection of patients who ultimately require surgical intervention when all else fails. Partial plantar fasciotomy has remained a mainstay with good long-term outcomes when such patients need a more aggressive treatment approach. When considering surgery for recalcitrant heel pain, one must ensure a careful and comprehensive differential diagnosis in addition to a thorough history and physical exam. When heel pain is associated with radiographic presence of enthesopathy, the differential should include a history of trauma, degenerative disease, inflammatory joint disease, crystal deposition disease, endocrine disorders (including diabetes mellitus) and infection (such as Reiter’s).8 What The Literature Reveals One may release a portion of the proximal plantar aponeurosis either openly, percutaneously or endoscopically. Regardless, controversy remains as to the necessity of concomitantly resecting the calcaneal heel spur. As it is technically challenging to resect the spur alone while leaving the plantar fascia inviolate, very few such studies have been reported. Steindler noted that less than half (7/16) of patients with isolated spur resection had good outcomes.15 Anderson found that 11 out of 72 patients had only fair or poor clinical results when the spur was resected alone.16 On the other hand, Ward and Clippinger found that seven out of eight patients had excellent results while one patient had 75 percent improvement with a partial fasciotomy without resecting the spur.17 Snider, et. al., reported that 10 of 11 such procedures among runners also yielded excellent results.18 Brekke and Green found those with minimal incision fasciotomy alone experienced greater pain reduction when they compared them to those who had open procedures with or without heel spur resection.19 In fact, many other studies have also confirmed good postoperative results while the calcaneal spur was left intact.20-26 What You Should Know About Potential Complications While surgery is generally successful, one must consider potential postoperative complications.27 These complications include recurrent heel pain, permanent local numbness, painful nerve entrapment, wound dehiscence, infection and hypertrophic scar formation. Furthermore, any procedure involving plantar fascial release can also lead to instability, foot pain, cramping, metatarsalgia, metatarsal stress fractures, tendonitis and sinus tarsitis. These complications are not unique whether clinicians perform the surgery by minimal incision, open or endoscopically. Additionally, these complications are irrespective of whether one performs the fasciotomy with or without plantar heel spur resection. Of particular concern is whether one should combine the fasciotomy with osseous work to remove the heel spur. Two of the more serious complications following heel spur surgery are a calcaneal fracture, presumably from stress risers following minimal bone removal, and deep infection in the surgical area. Manoli, et. al., observed three calcaneal fractures following a fascial release and spur resection for chronic plantar fasciitis.28 One patient developed displacement with nonunion and arthritis, and ultimately required a subtalar joint arthrodesis. The authors treated another patient successfully with a short leg cast. Both cases resulted in calcaneal fractures with weightbearing before the patients even left the surgery centers. A third patient required an open reduction and internal fixation through a conventional posterolateral approach when she fractured the os calcis 10 days after primary heel spur resection. A fourth patient ultimately required a below knee amputation secondary to painful nonunion after she underwent plantar bone debridement. This particular situation was complicated by diabetes, neuropathy and local osteomyelitis.28 Hoffman and Thul reported two cases of calcaneal fractures following subcalcaneal spur resection. They treated both patients successfully with casting and offloading.29 The patients fell two days and two weeks respectively after their primary heel surgery. Donohue, et. al., performed closed reduction with Steinman pin fixation after a patient fractured her right calcaneus two months following heel spur and plantar fascia surgery.30 The senior author of this article has also observed at least two cases of calcaneal fractures in the immediate post-op period following heel spur resection with no history of additional trauma to the area. Stress fractures arise from excess repetitive fatigue on normal bone (fatigue fractures) or from nominal weightbearing forces on insufficient bone stock (insufficiency fractures).31 They generally do not arise from direct impact but can propagate from a region where focal integrity has been compromised (i.e. stress riser). Gordon described this notion from a material science perspective and also cited other works that showed fracture progression from small holes and cracks within structures that grossly appeared undisturbed macroscopically.32 Smith, et. al., outlined four progressive stages of “standard” calcaneal fatigue fractures before surgical intervention, describing the fatigue perturbation emanating from the plantar tubercle region.33 This is noteworthy given the fact that calcaneal fractures following heel spur surgery have arisen from this same region of apparent weakness in the os calcis.28-30 Deep infections can be very difficult to eradicate when they occur at this surgical site. Some surgeons have suggested rasping the spur down using either hand or power instrumentation to minimize the risk of creating heel stress risers. However, increased potential still exists for creating local infection or even osteomyelitis by violating the periosteal and cortical structures, or by burring. In Conclusion Accordingly, resection of the plantar heel spur is seldom a necessary adjunct to partial plantar fasciotomy. There is no significant anatomic correlation of the plantar heel spur with the plantar fascia. The vast majority of plantar fasciitis cases will resolve with conservative care even in the face of plantar heel spur. In these cases, the asymptomatic spur remains. One may often see asymptomatic plantar heel spurs in patients without any symptoms of plantar fasciitis. Conversely, many patients with fasciitis are devoid of infracalcaneal heel spurs. Therefore, it is hard to make a case that the plantar heel spur is directly correlated to plantar fasciitis at all. Plantar fasciotomy may be an option for appropriately selected candidates who have recalcitrant plantar heel pain. The literature supports releasing part of the plantar aponeurosis at its most proximal medial attachment to the os calcis without spur resection as the partial release yields good clinical outcomes. There is a small but devastating potential for calcaneal fracture and an increased potential for deep infection following spur resection. Consequently, we find no evidence to support “routine” surgical resection of bone spurs during the course of plantar fascial release. Dr. Green is the Director of Podiatric Surgical Residency at the Scripps Mercy Medical Center in San Diego. He is a Clinical Professor at the California School of Podiatric Medicine at Samuel Merritt College, and is a Fellow of the American College of Foot and Ankle Surgeons. Dr. Green is also a Clinical Assistant Professor at UCSD Medical School, a faculty member of the Podiatry Institute and has a private practice in San Diego. Dr. Kim is a second-year resident within the Scripps Mercy Kaiser Residency Program in San Diego. Dr. Burks is a Fellow of the American College of Foot and Ankle Surgeons and is board-certified in foot and ankle surgery. Dr. Burks practices in Little Rock, Ark.
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