First Metatarsal Pathology: Can An Implant Provide A Long-Term Solution?

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An Overview Of Previous First Metatarsophalangeal Implants

The Keller resection arthroplasty of the base of the proximal phalanx has generally been regarded as the gold standard for recalcitrant pain of the first metatarsophalangeal joint. Described in 1904, it remains the orthopedic procedure of choice due to its preservation of the first metatarsal head.1 However, if one resects too little bone, the result may be a stiff, painful pseudoarthrosis while over-resection of bone results in loss of hallucal function and disrupts the biomechanics of the foot.2,3

In the early 1950s, several investigators began to implant synthetic materials for the first metatarsophalangeal joint.4,5 In separate studies, Swanson and Seeburger utilized metallic implants in the first metatarsal while Joplin incorporated metal in the base of the proximal phalanx.5,6 Eventually, acrylic was tried as a substitute for metal on the proximal phalanx. The findings for these individual materials as well as combinations of the two yielded less than satisfactory results.

In the late 1960s, Swanson, in conjunction with Dow-Corning, introduced the single-stemmed (hemi) silicone first metatarsophalangeal joint implant. In 1974, Dow introduced Silastic-HP® (high performance) for the double-stemmed (total) implant. The newer material was touted to have a greater modulus of elasticity, allowing greater cyclic loading without the accompanying pattern of stress fracture to the bone.7

Although Swanson’s original design has been modified several times, (i.e., Weil/LPT, Lawrence/MHT, LaPorta/Primus, etc.), none of the prosthetic designs to date have demonstrated an ability to reproduce the normal mechanics of the first metatarsophalangeal joint.8 It is for this reason that double-stemmed implants have been referred to as “dynamic spacers” as opposed to joint replacements. This would also include silicone “ball spacers” currently being used in England.9,10

The debate over the biocompatibility of silicone has taken on a new dimension with the release of earlier research showing the dangers of breast implants. Although silastic implants are of a harder consistency, there is a serious rethinking of their role in the foot.

Surgeons placing silicone implants in the first metatarsophalangeal joint have noted not only cystic changes in the surrounding bone, but also reactive synovitis in many of their patients.11,12 Shereff has found bone resorption to be a consistent finding in a review of first metatarsophalangeal joint silicone implants.8 McCarthy, using electron microscopy, found T-lymphocytes in the area of silicone implants within 12 months of implantation. This suggested a much stronger immune response to silicone than previously thought. Numerous authors using a variety of methodologies for evaluation have reported reactive synovitis.13,14 While the definitive etiology of these reactions eludes the medical community, many in the general public remain skeptical regarding the implantation of silicone.

In 1974, Smith and Weil introduced a prosthetic of ultra-high molecular weight polyethylene for the phalangeal component and stainless steel for the metatarsal component of a total joint implant. The intramedullary aspect was affixed with bone cement.15

It has been suggested that the failure of this implant may be traced less to materials than to design. The implant had a central groove in the phalangeal component and a complementary ridge in the metatarsal component. Although this groove provided stability, it effectively violated two of the three cardinal planes in which the joint functions, constraining it to the sagittal plane.9 This same phenomenon occurs with the double-stemmed implants. The forces constrained by the prosthesis are believed to be transferred to the shaft canal interface, creating a stress riser that effectively weakens the cement bond. This leads to microfracture in the bone and, ultimately, implant failure.16-18

In 1981, Johnson and Buck reported on a surface replacement prosthesis, consisting of two components made of stainless steel and polyethylene, fixed with methyl methacrylate.19 Twenty-one procedures were followed with a satisfaction rate of 81 percent. Johnson and Buck concluded the results were encouraging but they were concerned with prosthetic loosening in two cases and dislocation in another.19 In their discussion, they felt “… on an intuitive basis, joint function should be preserved better by a prosthesis than by an ablative joint procedure.”19

In 1990, Koenig introduced a titanium alloy and polyethylene prosthesis utilizing a press fit system of implantation rather than cementing.20 In this process, cortical bone needed to be resected dorsally, distally and plantarly from the metatarsal head in order to accommodate the component. The sesamoid apparatus is left articulating with the base of the metallic component since its plantar articular surface was sacrificed.

The combination of stripping the metatarsal shaft of its cortex and destroying the weightbearing surface of the metatarsal head (along with the sesamoid apparatus) violated sound physiologic and biomechanical principles. This opened the door to implant failure, chronic pain and ultimately destruction of the first metatarsophalangeal joint. Since a large potion of the blood supply to long bones comes from the cortex, there was also an increased risk of avascular necrosis.

References

1. Keller WL. Surgical treatment of bunions and hallux valgus. NY Med, 80741-2, 1904.

2. Miller RJ, Rattan N, Sorto L. The geriatric bunion correction of metatarsus varus primus and hallux valgus with Swanson total joint implant. Foot Surgery 22(3):263-70, 1983.

3. Mayo C. The surgical treatment of bunions. Ann Surgery 48:300-302, 1906.

4. Borovoy M, Gray W, Rinker A. Total replacement of the first metatarsophalangeal joint. Foot Surgery 2(2):159-164, 1983.

5. Swanson AB, Lumsden RM, Swanson GD. Silicone implant arthroplasty of the great toe. Clin Orthopedics 142:30, 1979.

6. Seeburger R. Surgical implants of alloyed metals in joints of the foot. Am Podiatry Association 54:391-6, 1964.

7. Merkle PF, Soutoo TP. Prosthetic replacement of the first metatarsophalangeal joint. Foot and Ankle 10(6):191-192, 1989.

8. Sgarlato TE. Sutter double-stem silicone implant arthroplasty of the lesser metatarsophalangeal joints. Foot Surgery 28(5):410-413, 1989.

9. Broughton NS, Doran A, Meggit BF. Silastic ball spacer arthroplasty in the management of hallux valgus and hallux rigidus. Foot and Ankle 10(2):61-64, 1989.

10. McAuliffe TB, Helal B. Replacement of the first metatarsophalangeal joint with a silicone elastomer ball shaped spacer. Foot and Ankle 10(5):257-262, 1990.

11. Kampner SL. Total joint prosthetic arthroplasty of the great toe. Clin Orthopedics 142:30, 1979.

12. Cracchiolo AS, Swanson GD. The arthritic great toe metatarsophalangeal joint: a review of flexible silicone implant and arthroplasty from two medical centers. Clin Orthopedics 157:64-69, 1981.

13. McCarthy DJ, Kershisnik K, O’Donnell E. The histopathology of silicone elastomer implant failure in podiatric surgery. JAPMA 76(5):247-265, 1986.

14. McCarthy DJ, Chapman HL. Ultrastructure of collapsed metatarsophalangeal silicone elastomer implant. Foot Surgery 27(5):218-227, 1988.

15. Weil LS, Pollak RA, Goller WL. Total first joint replacement in hallux valgus and hallux rigidus: long-term results in 484 cases. Clin Podiatry 1(1):103-129, 1984.

16. Mondull M, Jacobs PM, Caneva RG, Crowhurst JA, Morehead DE. Implant arthroplasty of the first metatarsophalangeal joint: a twelve-year retrospective study. Foot Surgery 24(4):175-279, 1985.

17. Gudmundsson G, Robertsson M. Silastic arthroplasty of the first metatarsophalangeal joint. Acta Orthop Scand 51(3):575-578, 1981.

18. Verhaar J, Bulstra S, Walenkamp G. Silicone arthroplasty for hallux rigidus: implant wear and osteolysis. Acta Orthop Scand 60(1):30-33, 1989.

19. Johnson KA, Buck PG. Total replacement arthroplasty of the first metatarsophalangeal joint. Foot and Ankle 1(6):307-317, 1981.

20. Keonig RD. Koenig total great toe implant (preliminary report). JAPMA 80(9):462-468, 1990.

This intraoperative photo shows the first metatarsophalangeal joint with the silicone implant removed. Note the erosion of the proximal phalanx and the first metatarsal head. (Photo courtesy of Graham A. Hamilton, DPM)
Addressing the biomechanics of the first metatarsophalangeal joint as well as the first ray are the keys to any surgical correction of the first metatarsal pathology. The Bio-Action implant may facilitate long-term, pain-free range of motion, according to
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Author(s): 
By Kerry Zang, DPM, Shahram Askari, DPM, A’Nedra Fuller, DPM, and Chris Seuferling, DPM

However, minimal osseous resection is critical in order to preserve the sesamoid apparatus as well as the flexor/extensor function. Since this is a joint destructive procedure, surgeons must resect the prominent dorsolateral, dorsal, dorsomedial and medial aspects of the metatarsal to exactly match the circumference of the metatarsal component. Removing this bone will minimize the possibility of osseous impingement and diminish the potential for recurrent bony overgrowth.
Mark the center of the respective medullary canals with an awl through the centering guides in order to facilitate acceptance of the implant stems. Drill a guide hole with a football/egg shaped burr parallel to the shaft of the respective bone. One may make this evacuation in the presence of any previous fixation or other implanted device (wire/anchor), provided there is sufficient osseous structure for the implant stem support.
Use the implant sizers to ensure proper implant selection and to estimate the range of motion within the joint. When there are some questions as to which implant size to choose (large or small), we feel the best outcome is achieved with the smaller size. This allows the surgeon to skive off any additional overhanging bone, further minimizing the possibility of bony overgrowth.
Following proper implant selection, proceed to resect any overhanging bone on the metatarsal about the trial flanges to prevent impingement. When properly seated, the head of the metatarsal component should be slightly shorter clinically than the second metatarsal head. This allows for minimal disruption of the weightbearing surface of the first metatarsal and preserves the metatarsal parabola.
Double-check the range of motion within the joint. Copiously irrigate the operative side and place the implants within the appropriate impactor. Again, check the range of motion within the joint and close the capsule with the suture of choice. If the extensor hallucis is contracted, one may lengthen it to a functional position. Close the tissue layers and secure them according to preference. Apply a mild compression with the hallux placed in a functional position.
Another key to the success of the Bio-Action Implant is immediate, postoperative, passive range of motion. Daily sagittal plane range of motion exercises, performed by the patient or caregiver, are crucial to minimizing the length of the overall recovery period.

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yiceliseosays: February 21, 2011 at 9:46 am

Thanks for this nice post.

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kicalasEOsays: February 24, 2011 at 3:24 am

Thanks for this tip.

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