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Midfoot Arthritis: Understanding the Problem & Treatment Options PDF Print E-mail
Written by Alan J. Zonno, MD   

Midfoot Anatomy
Eleven true articulations exist in the midfoot: 5 tarsometatarsal (TMT) joints, 2 intercuneiform joints, 1 cuneiform-cuboid joint, and 3 separate facets of the navicular bone for each of the corresponding 3 cuneiforms. A potential 12th articulation exists between the navicular and cuboid bones; this can range from a fibrous synchondrosis to a true synovial joint.1 The wedge-shaped metatarsal (MT) bases and cuneiforms are more narrow plantarly and form a “Roman arch” configuration with the apex at the second MT base, which is recessed on the middle cuneiform for additional stability.

The Lisfranc complex includes all 5 MT bases as well as their respective cuneiform and cuboid articulations. This complex forms the transverse arch of the foot, which is supported plantarly by a number of crossing soft tissue structures, including the plantar fascia and the peroneus longus tendon. Dorsal, plantar and interosseous (IO) ligaments exist within the complex, with the plantar and IO ligaments being the strongest.2 The Lisfranc ligament is a plantar structure that connects the base of the second MT to the medial cuneiform. There is no ligamentous attachment that exists between the first and second MT bases, which may place the midfoot at increased risk for injury.3

The midfoot can also be thought of in terms of columns (Figure 1). The medial column consists of the first MT and the medial cuneiform. The middle column contains the second and third metatarsals with their corresponding cuneiforms; the lateral column consists of the fourth and fifth metatarsals and the cuboid.
Figure 1
Midfoot Biomechanics
The function of the midfoot is to allow force transfer from the hindfoot to the forefoot during gait. The subtalar joint everts at heel strike in order to unlock the transversal tarsal (talonavicular and calcaneocuboid) joints and create a supple midfoot from heel strike into mid-stance that is capable of absorbing shock.4 The subtalar joint then inverts at toe-off to again lock the transverse tarsal joints and allow a rigid lever arm for push off.4

Motion does exist in the midfoot, but to a lesser extent than that discussed at the hip, knee, or ankle. The greatest motion exists in the lateral column at the articulations of the fourth and fifth MT bases with the cuboid; approximately 10° of motion exists in each dorsiflexion/ plantarflexion and pronation/supination.5 In contrast, motion is least at the second TMT joint, where only about 1° of motion exists in each plane.5 The second MT is recessed into the middle cuneiform for additional stability and is further tethered by the stout Lisfranc ligament.

Degenerative Pathology
Disruption on the Lisfranc complex (eg, following traumatic injury) results in interruption of force transmission from the hindfoot to the forefoot. The medial arch of the foot collapses to a variable degree resulting in increased plantar tensile forces. Researchers hypothesize that the resulting increase in tensile load on the plantar ligaments causes pain.6 A progressive pes planus deformity accompanied by forefoot abduction and hindfoot valgus may occur over time. Dorsal and plantar osteophytes can form. Dorsal osteophytes create trouble with shoe wear and/or impinge on the deep peroneal nerve. Plantar osteophytes encourage callus formation and increases the risk for ulceration, particularly in patients with decreased protective plantar sensation.

Etiology
Post-traumatic degenerative change (eg, following a Lisfranc injury) may be the most common cause of midfoot arthritis.3,7  However, with an aging population, primary osteoarthritis is becoming more common. Underlying inflammatory diseases such as rheumatoid arthritis, gout and lupus are responsible as well, but to a lesser degree.

According to Schon, the midfoot is the most common site affected by Charcot arthropathy.8 Therefore, a high index of suspicion should be maintained when evaluating any person with diabetes or a neuropathic patient with atraumatic midfoot swelling or deformity (or similarly, swelling and deformity after minimal trauma). An acute Charcot process may mimic an infection – with accompanying erythema and warmth in addition to generalized swelling of the foot. Pain may or may not be present due to underlying neuropathy. The differential diagnosis of infection vs. acute Charcot process is an important decision that needs to be made in order to proceed with treatment. Infections are treated with antibiotics and potential debridement; in contrast, an acute Charcot process requires an extended period of non-weight bearing immobilization. Elevation of the foot will decrease erythema and swelling associated with an acute Charcot process, but not infection.

Other intrinsic etiologies that may contribute to the development of midfoot arthritis include medial column instability (Figure 2) and a long second MT (Figure 3).
Figure 2
Figure 3
Work Up of Midfoot Pain
An adequate history and physical examination is all that is required to make the diagnosis almost 100% of the time; imaging studies (primarily x-rays) are then used to confirm the diagnosis and guide surgical intervention.

In terms of physical examination, the patient should have palpable pulses. If no pulses are palpable, then I send the patient for noninvasive arterial studies to evaluate wound healing potential. Be sure to palpate all joints in the midfoot complex, as well as the more proximal transverse tarsal joints and distal metatarsophalangeal joints. Tenderness upon examination, together with the radiographs, will help guide any planned surgical intervention. Use the Silfverskiöld test to evaluate for contracture of the gastrocsoleus complex; and finally, assess hindfoot alignment – looking specifically for valgus malalignment.

Radiographic Studies
Three-view weight-bearing x-rays should be taken of the affected foot. The anterior-posterior (AP) x-ray will be used to examine the medial and middle columns; the internal rotation oblique will be used to assess the lateral column. The lateral x-ray can be used to identify the apex of the deformity as well as any medial column instability (as described in Figures 4 and 5). Contralateral foot x-rays can be taken for comparison if necessary.

Advanced imaging studies including CT scan and MRI are not routinely required for diagnostic purposes, but may be useful in certain situations, such as the work-up of a tarsal coalition, soft tissue mass or lytic lesion in a patient with a history of malignancy.

Figure 4 and Figure 5 contain what I believe are the more essential radiographic lines to be familiar with in terms of diagnosing midfoot pathology.
Figure 4
Figure 5
Treatment Options
Treatment options for midfoot arthiritis are non-operative vs. operative management. The cornerstones of non-operative management for the treatment of midfoot arthritis include both activity and shoe modification. Patients should be counseled to decrease or avoid aggravating activities. In terms of shoe modification, stiff-soled shoes with or without a rocker-bottom are recommended. Alternatively, carbon-fiber plates or more rigid custom orthotics can be tried. The purpose of stiff-soled shoes, carbon-fiber plates and rocker-bottoms is to facilitate force transfer across the midfoot.3

Full-length carbon fiber plates have been shown to reduce plantar pressures as well as medial midfoot contact time,12 thus reducing load seen by the arthritic midfoot and hopefully, improving pain control. When compared with three-quarter length carbon fiber plates, full-length carbon fiber plates demonstrate a 20% additional reduction in medial midfoot pressure (P<.015) and 8.5% additional reduction (P<.01) in medial midfoot contact time.12 In terms of functional outcome, the use of full-length carbon fiber plates in 20 women with midfoot osteoarthritis resulted in a 12% improvement (P=0.03) in the revised Foot Function Index.12

A more recent Level II study conducted by Ibuki et al compared the use of custom full-length semi-rigid orthotics in 57 patients vs. the same custom full-length semi-rigid orthotics in addition to a carbon fiber insert in 36 patients.13 Both groups reported significantly improved pain, activity level and footwear comfort. However, there were no significant differences between study groups.

Patients can also try a short course of a non-steroidal anti-inflammatory medication if there are no contraindications. Alternatively, a corticosteroid injection can be attempted.

Operative intervention is recommended when conservative management fails for 3 months to 6 months. Two primary surgical options exist – debridement vs. reconstruction. Debridement generally consists of cheilectomy in order to remove impinging dorsal osteophytes.  Decompression of the deep peroneal nerve may be accomplished simultaneously by removing the osteophytes.

Reconstruction is accomplished by arthrodesis of symptomatic joints. The goals of arthrodesis are to create a painless, plantar-grade and “shoeable” foot. Myerson recommends in situ fusion with displacement less than 2 mm and angulation less than 15°;14 otherwise, realignment of the midfoot is recommended at the time of arthrodesis. Midfoot arthrodesis has proved historically to be a reliable procedure with union rates greater than or equal to 97% reported in the literature.14, 15 Additionally, concomitant deformities, including hindfoot valgus and gastrocsoleus contracture, need to be addressed at the time of midfoot reconstruction.

References
  1. Jaffe WL, Gannon PJ, Laitman JT. Paleontology, embryology, and anatomy of the foot. In: JahssMH. Disorders of the Foot and Ankle:  Medical and Surgical Management. Philadelphia, PA: Saunders; 1991:3-34.
  2. Desmond EA, Chou LB. Current concepts review: Lisfranc injuries. Foot Ankle Int. 2006;27(8):653-660.
  3. Patel A, Rao S, Nawoczenski D, et al. Midfoot arthritis. J Am Acad Orthop Surg. 2010;18:417-425.
  4. Elftman H. The transverse tarsal joint and its control. Clin Orthop. 1960;16:41-46.
  5. Ouzounian TJ, Shereff MJ. In vitro determination of midfoot motion. Foot Ankle. 1989;10(3):140-146.
  6. Gazdag AR, Cracchiolo A. Rupture of the posterior tibial tendon: Evaluation of injury of the spring ligament and clinical assessment of tendon transfer and ligament repair. J Bone Joint Surg Am. 1997;79(5):675-681.
  7. Sayeed SA, Khan FA, Turner NS, Kitaoka HB. Midfoot arthritis. Am J Orthop. 2008;37(5):251-256.
  8. Schon LC, Easley ME, Weinfeld SB. Charcot neuroarthropathy of the foot and ankle. Clin Orthop Relat Res. 1998;349:116-131.
  9. Sanicola SM, Arnold TB, Osher L. Is the radiographic appearance of the hallucal tarsometatarsal joint representative of its true anatomical structure?  J Am Podiatr Med Assoc. 2002;92(9):491-498.
  10. Davitt JS, Kadel N, Sangeorzan BJ, et al. An association between functional second metatarsal length and midfoot arthrosis. J Bone Joint Surg Am. 2005;87(4):795-800.
  11. Steel MW 3rd, Johnson KA, DeWitz MA, Ilstrup DM. Radiographic measurements of the normal adult foot. Foot Ankle. 1980;1(3):151-158.
  12. Rao S, Baumhauer JF, Becica L, Naqoczenski DA. Shoe inserts alter plantar loading and function in patients with midfoot arthritis. J Orthop Sports Phys Ther. 2009;39(7):522-531.
  13. Ibuki, A, Cornoiu A, Clarke A, et al. The effect of orthotic treatment on midfoot osteoarthritis assessed using specifically designed patient evaluation questionnaires. Prosthet Orthot Int. 2010;34(4):461-471.
  14. Komenda GA, Myerson MS, Biddinger KR. Results of arthrodesis of the tarsometatarsal joints after traumatic injury. J Bone Joint Surg Am. 1996;78:1665-1676.
  15. Mann RA, Prieskorn D, Sobel M. Mid-tarsal and tarsometatarsal arthrodesis for primary degenerative osteoarthrosis or oastroarthrosis after trauma. J Bone Joint Surg Am 1996;78(9):1376-1385.
 

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