Flexible Hinge Silicone Implant with or without Titanium Grommets for Arthroplasty of the First Metatarsophalangeal Joint

Abstract

Purpose. To review outcomes of 37 patients who underwent arthroplasty of the first metatarsophalangeal joint using flexible hinge silicone implants with or without titanium grommets. Methods. 36 women and one man (63 feet) underwent arthroplasty of the first metatarsophalangeal joint for rheumatoid arthritis (RA) using Swanson flexible hinge silicone toe implants with or without titanium grommets. 20 women (35 feet) aged 31 to 72 (mean, 52) years with Steinbrocker grade II (n=4), grade III (n=6), and grade IV (n=10) RA of the feet were treated with the implant without grommets, whereas 16 women and one man (28 feet) aged 48 to 73 (mean, 60) years with Steinbrocker grade III (n=4) and grade IV (n=13) RA of the feet were treated with the implant with grommets. Pain levels were self-rated. Degenerative changes and the presence of osteophytes or deformity were recorded, as were breakage or deformation of the implants, radiolucencies around the implant, implant loosening, silicone-induced synovitis, and Address correspondence and reprint requests to: Dr Noriyuki Kanzaki, Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan. Email: kanzaki@med.kobe-u.ac.jp Surgery 2014;22(1):42-5 sclerosis around the implant. Results. All patients reported pain relief from severe to mild or moderate. Respectively for the feet with and without grommets, the rates of implant deformation were 25% and 63% (p=0.031), whereas the rates of moderate-to-severe radiolucencies (>2 mm) were 4% and 34% (p=0.004). Sclerosis developed around the implant in all feet. Conclusion. Titanium grommets appear to protect the implant and improve clinical outcomes. Journal of Orthopaedic

Structural assessment of pre-flexion in silicone implants for arthroplasty of the first metatarsophalangeal joint

“…Moreover, maximum stresses obtained for the Swanson implant were located in the implant stem in contact with bone where the cut was done, which suggests a potential risk of failure in this region. This result agrees with clinical data, where the failure of the implant was evaluated, and corresponds with a failing grade of 0, according to the criteria of breakage and deformation of the implants presented by Noriyuki Kanzaki et al 39 and Granberry et al 41 They are classified as grade 0, with no evidence of deformation or fracture; grade 1, slight deformation or fracture of the stem or the hinge; and grade 2, a complete deformation of the implant. Thus, the model was validated considering that the zones where the maximum stresses obtained in the implants models were the stem or hinge, according to within Vivo condition observed by Noriyuki Kanzaki et al 39 and Granberry et al, 39 and they reach up to 22.82% of the tensile strength reported for silicone, for Swanson implant, and 25.92% for Tornier implant, which suggests the absence of fracture, indicating a type 0 failure, by the pre-flexion conditions to which the implants were subjected.…”

“…Comparisons presented in Tables 1 and 2 suggest that large differences that were found between models may generate differences in the structural behavior of complete foot models which include the 39 This agrees with the expected result for strains since not all loads related to the metatarsophalangeal joint were applied; this work was focused on the structural effects of flexion.…”

Silastic replacement of the first metatarsophalangeal joint: historical evolution, modern concepts and a systematic review of the literature

“…The double-stemmed implants suffered from more fractures and fragmentations (4.9%) than the single-stemmed implants (2%) (p < 0.05). The incidence of implant fracture has been reported as between 1% and 11% in different studies, 16,21,22,49 however, implant fracture is not necessarily associated with a poor outcome. Significantly more single-stemmed implants failed (11%) than the double-stemmed implants (3.6%) (p < 0.05).…”

“…It is important to note that these changes do not necessarily correlate with patients’ subjective satisfaction. 9,30,40,42,49,57,59,60 It is believed that satisfactory function continues even after radiographic deterioration because the implant acts as a spacer via encapsulation rather than a fixed hinge. 40 It is considered as the body’s response to surgical intervention with the implant serving as a template for the proper deposition and alignment of encapsulating collagen tissues.…”

“…Three studies assessed the use of titanium grommets with double-stemmed implants. 42,46,49 Two of these studies reported a higher incidence of radiological lucencies and implant failure without the use of grommets and recommended that they be used routinely, 42,49 while the third study did not find any significant differences in the outcomes of implants with or without the use of grommets. 46…”