Implants
IMPLANTS
The most common pathogen to cause infection during implant surgery is Staphylococcus epidermis. Vancomycin is the drug of choice for antibiotic prophylaxis during implant surgery. Most metal joint implants are made of cobalt-chromium due to its high strength and smooth-polished finish. The smooth-polished finish is less destructive on cartilage. These same implants may have stems and undersurfaces that are coated with titanium plasma spray to encourage osseous integration.
FIRST METATARSOPHALANGEAL JOINT IMPLANTS
Hemi Implants
Hemi implants are indicated for hallux limitus and hallux rigidus in the first ray and advanced arthritis in the lesser MPJs. They are used to replace the base of the proximal phalanx. On the first ray, minimal bone resection is important to preserve the insertion of the flexor halluces brevis tendon. These implants require an adequate articular surface on the metatarsal head.
AnaToemic Hemi-Prosthesis
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Made of cobalt-chromium with grit-blasted phalangeal surface and stem
Arthrex
Vilex Cannulated Hemi Implant
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Cobalt-chrome
Cannulated
Implant screws into the bone
Cannot be used at the same joint with the Vilex Cannulated Hemi Implant
Wright Hemi Phalangeal Implant (HPI)
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Cobalt-chromium
Trapezoidal shape matches the shape of the phalanx.
Recessed central plantar area to avoid irritation of the flexor tendons
Partial, plasma-sprayed, titanium stem and undersurface coating for osseous integration
Includes optional suture holes for flexor tendon attachment
BioPro First MPJ Hemi Implant
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Cobalt-chromium
Available in porous and nonporous-coated stems
BioPro Lesser MPJ Hemi Implant
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Cobalt-chromium
Indicated for the lesser MPJs
Different stem design to accommodate the smaller phalanges
Available in a cannulated version
OsteoMed Hemi Great Toe Implant
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Cobalt-chromium
Plantar surface of the implant is flat to avoid irritation of the flexor tendons.
Metal Hemi Toe (MHT)
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Cobalt-chromium with a titanium plasma-sprayed stem
Trapezoidal articular surface and stem better match the geometry of the proximal phalanx.
Fifteen-degree angle between the articular surface and the stem in the sagittal plane to accommodate for the metatarsal declination angle
Stem becomes thicker going from the tip toward the base to better conform to the shape of the medullary canal of the proximal phalanx.
Integra LifeSciences Corp.
LPT 2 (Low Profile Toe) Great Toe Implant
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Titanium
Available in straight or angled options for increased PASA
Angled option comes in two sizes: size 1 is 18° and size 2 is 16°.
Only difference between the LPT and the LPT 2 is the instrumentation.
Cruciate stem
Two perforating holes to secure FHB, angled version has a third hole, placed medially to prevent lateral subluxation
Wright Medical Technology Inc.
K2 Hemi Implant
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Cobalt-chromium with titanium plasma-coated stem
Perforating hole plantarly to secure FHL to the base of the phalanx and implant, preventing a hallux hammertoe
Integra LifeSciences Corp.
Metatarsal Resurfacing Implants (Metatarsal Hemi Implants)
Metatarsal Decompression Implant (MDI)
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Cobalt-chromium with plasma-sprayed titanium coating on stem
Head is angled to avoid interference with the weight-bearing surface and provide progressive decompression through dorsiflexory ROM.
Wright Medical Technology Inc.
Lesser Metatarsal Head Implant (LMH)
Same as MDI but made for lesser metatarsals
Wright Medical Technology Inc.
Arthrosurface HemiCAP Toe Implant
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Consists of two components, a cap (cobalt-chrome) and a screw in stem (titanium), that fit together
EnCompass Metatarsal Resurfacing Implant
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Cobalt-chromium with titanium plasma- and hydroxyapatite-coated undersurface
Osteomed
Vilex Cannulated Metatarsal head Implant
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Cobalt-chromium
Cannulated
Implant screws into the bone
Cannot be used in the same joint with the Vilex Cannulated Metatarsal Head Implant
Total One Piece Hinged Implants
Swanson Flexible Toe Implant
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Silicone
Two stem sizes, standard and small
Midsection of the implant is U-shaped; opening of “U” can be directed dorsally or plantarly.
The two stems are in the same plane and perpendicular to the hinge.
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