Metatarsalgia: Diagnosis and Management

1 MARCH 2002 PODIATRY the subject of this ContinuingPodiatric Medical Education isolated complaint ofmetatarsalgia, with pain under themetatarsal head, has been called primary metatarsalgia ,1,2pressuremetatarsalgia,3 or structuralmetatarsalgia. Although there arenumerous etiologies of metatarsal-gia,4,5very few patients present withFreiberg s disease, let alone Tetralo-gy of Fallot as a cause of plantarforefoot pain. This CME article willContinued on page 79 Welcome to Podiatry Management s CME Instructional program. Our journal has been approved as a sponsor of Continu-ing Medical Education by the Council on Podiatric Medical may enroll: 1) on a per issue basis (at $15 per topic) or 2) per year, for the special introductory rate of $99 (you save $51).

2 You may submit the answer sheet, along with the other information requested, via mail, fax, or phone. In the near future, you maybe able to submit via the you correctly answer seventy (70%) of the questions correctly, you will receive a certificate attesting to your earned credits. You willalso receive a record of any incorrectly answered questions. If you score less than 70%, you can retake the test at no additional cost. Alist of states currently honoring CPME approved credits is listed on pg. 136. Other than those entities currently accepting CPME-approvedcredit, Podiatry Management cannot guarantee that these CME credits will be acceptable by any state licensing agency, hospital, man-aged care organization or other entity.

3 PM will, however, use its best efforts to ensure the widest acceptance of this program instructional CME program is designed to supplement, NOT replace, existing CME seminars. Thegoal of this program is to advance the knowledge of practicing podiatrists. We will endeavor to publish high quality manuscripts bynoted authors and researchers. If you have any questions or comments about this program, you can write or call us at: PodiatryManagement, Box 490, East Islip, NY 11730, (631) 563-1604 or e-mail us at this article, an answer sheet and full set of instructions are provided (p. 136). EditorPain under metatarsal headswith callus formation is an ex-tremely common reason forseeking podiatric treatment andBy Ellen Sobel, , , &Steven Levitz, ) To determine the etiology of plantarkeratosis, diffuse callosities, callus underthe first, second, and fifth metatarsalheads as well as to distinguish betweendiffuse and discrete plantar ) To describe the symptoms experi-enced by the patient with structural or me-chanically induced ) To be aware of the nature of asso-ciated digital ) To review the biomechanics ) To be aware of common condi-tions resulting in pain in the forefootwhich may be in the differential diagno-sis for structural ) To update the recent research on theetiology of structural )

4 To update recent research on theeffectiveness of metatarsal pads, insolesand custom foot orthoses in the treat-ment of ) To be aware of the variety of pre-fabricated commercial paddings, in-soles, and foot orthoses in the manage-ment of ) To know the pedorthic manage-ment for patients with EducationMetatarsalgia:DiagnosisandManag ementEtiologies and differential PODIATRYCLINICAL Management MARCH 2002 FIGURE 1. The normal plantar fat pad with fibrous 2A. Second metatarsal head shows sharp plantarlateral condyle responsible for metatarsal Educationbe thought of as a pinched nerve (Figure 2B).Intractable plantar keratoses tend to occurunder metatarsal heads two, three, and four, whichmay or may not be associated with hallux valgus.

5 Theyare deep and painful, however, when an individual hasmultiple IPK s and they may not all hurt. Debridementreduces pressure to the ball of the foot 30%. After de-bridement moleskin padding can be placed over thecallus for two to three days. Some patients will evenbathe with the moleskin in , the dorsal angle of themetatarsophalangeal joint is about160 .16In a hammertoe deformity thisangle may be reduced to 90 , at whichangle the base of the proximal pha-lanx articulates with the dorsum ofthe head of the metatarsal. A hammer-toe deformity causes the proximalphalanx to push down on the dorsalaspect of the metatarsal head, causingthe metatarsophalangeal joint tostretch and the glenoid plate to degenerate.

6 This pro-cess can occur very Metatarsal Head CallusCallus on the fibular side of the fifth metatarsalhead occurs because the head of the fifth metatarsal isContinuingMedical Educationfocus on the most common structural causes ofmetatarsalgia, and provide several examples of fre-quently occurring differential diagnoses and the practi-cal Management of this common Keratosis CallositiesPlantar callus or tyloma is the most common causeof metatarsalgia . Pain limited to thehead of the metatarsophalangeal ar-ticulation with callus formation be-neath the metatarsal head is a sign ofabnormal weight bearing stress of the body weight resultsin an inflammation on the plantarsurface of the head of the metatarsalbone as well as at the metatarsopha-langeal plantar fatpad has been thought to atrophy withaging in some people and fails to pro-vide adequate cushioning, producing generalized dis-comfort beneath the metatarsal heads (Figure 1).

7 7 Hyperkeratosis or callus is a thickening of the skincaused by hyperplasia of the keratin layer, histological-ly similar to a ,9,10,11It is found most frequentlyunder one or more of the lesser metatarsal heads in theforefoot12,13especially under subcutaneous tissuethinned by continuous and excessive callosities are divided into large diffusekeratosis and well localized intractable plantar keratosis(IPK). DIFFUSE PLANTAR KERATOSES lack a discretecentral core and are usually one to two centimeters may be caused by a relatively long orplantar-flexed second metatarsal. The Morton s foot,consisting of a short first metatarsal, causes increasedstress under the second metatarsal and subsequently alarge, diffuse keratosis.

8 In patients with significant hal-lux valgus deformity, the stress-absorbing function ofthe first metatarsal diminishes and a so-called transferlesion develops under the second Plantar Keratosis (IPK)The cause of the discrete IPK is an enlargement ofthe plantar lateral condyle of the metatarsal head (Fig-ure 2A).10 The condylar process on the fibular side is al-ways thelarger ofthe pro-duced byan IPK iscaused bytrappednerves andcapillaries(redipegs)resultingin IPK on page 80 MARCH 2002 PODIATRY 2B. Entrapment of capillary andnerve within the IPK. The enlarged plantarlateral condyle is callus or tyloma is the mostcommon cause of sesamoid becomes a weight-bearing focus andcauses a keratotic lesion.

9 The keratotic lesion producedby the tibial sesamoid is a discrete, localized keratosiswith a dense keratotic center. When this lesion is de-brided, a punctate keratotic focus is of the Metatarsal HeadsAll of the metatarsals sustain the body s ,18 One-half of the body weight passes through each ankleminus the weight of the foot. Half of the force on thefoot passes to the five metatarsal heads and the remain-ing half passes to the heel. If plantar weight bearing isdivided into 12 units, 6 units will pass to the heel and 6units will pass to the forefoot. Of the six units underthe metatarsal head, each of the lesser metatarsals takesone unit and the first metatarsal head takes 2 the first metatarsal normally carries approxi-mately twice as much weight as each lesser a first ray insufficiency syndromein which the first metatarsal cannot bear its share ofthe weight.

10 Conditions such as hallux valgus, short firstmetatarsal, metatarsus adductus, and proximal place-ment of the sesamoids result in reduced weightbearingfor the first ray and place increased pressure under thelesser metatarsals. Flatfoot with resultant forefootsupinatus indirectly reduces the weightbearing underthe first metatarsal head. Relaxation of the capsuloliga-mentous structures prevents the firm tight contact ofthe first metatarsal to the ground, resulting in an up-ward or dorsal tilt of the first metatarsal. Conversely,first ray overload syndrome, chiefly exemplified by hal-lux rigidus and sesamoiditis, places too much pressureon the first ray with possible clinical symptoms (callosi-ty and pain) under the first metatarsal that the cause of metatarsalgiawas a structural shortness of the first metatarsal whichhad to be compensated via lateral weight functional shortness of the first metatarsal manifest-ed with hypertrophy of the second metatarsal head andcortex, metatarsal-cuneiform split, and proximally dis-the most prominent point on the outer border of Presentation 1:This 50 year old male maintenanceworker had severe pain under the fifth metatarsal head forthe past several years.