Functional and patient-reported outcomes of the Swanson metacarpo-phalangeal arthroplasty in the rheumatoid hand.

INTRODUCTION: Replacement of the metacarpo-phalangeal joints (MCPJ) with silastic Swanson's implants can help decrease pain, stiffness and allow for improved function in rheumatoid arthritis (RA). There is a lack of patient reported outcome measure (PROM) studies assessing the efficacy of this procedure in RA. The aim of this study was to report any change in function, pain, stiffness and satisfaction following the Swanson MCPJ replacement using patient reported outcomes in a rheumatoid population. METHODS: The combined results of 64 RA patients (71 hands) with 284 Swanson MCPJ arthroplasties (mean follow-up: 75.85 months) were assessed using the validated M-SACRAH questionnaire and a separate satisfaction questionnaire. Radiographic evaluation was performed to insure correct alignment of the hinged prosthesis postoperatively. No attempt was made to identify other predictors, radiologically or clinically. Data analysed in the study was interpreted in the context of the number of hands and survivorship was defined as implant fracture, loosening or revision. RESULTS: The mean total functional outcome score improved by 46.2% and the total pain outcome improved by 60.2%. The total stiffness outcome improved by 56.9% postoperatively and the results obtained from the satisfaction questions revealed that 73.2% of patients would retrospectively elect to have the procedure again. We report two postoperative complications in this group of superficial wound infections. Radiographically, all MCPJs showed improved alignment, however five patients reported worsening pain, four patients reported increased stiffness and four reported reduced function postoperatively. There was one re-operation of a 5th MCPJ Swanson's, which did not require implant exchange and one implant was revised. Implant survivorship was 98.6%. CONCLUSIONS: Patient satisfaction and functional surrogate markers were overall favourable. Our results support the continued use of Swanson silastic arthoplasty in advanced RA.

Fabrication of silastic testosterone enanthate implants to achieve virilizing levels of serum testosterone in swine.

The aim of this study was to create a continuous drug delivery system that would yield serum testosterone levels in sexually mature, female pigs consistent with serum testosterone levels of human transgender men. Testosterone enanthate was mixed with medical grade silicone at a ratio of 20 % by weight, placed in silastic tubing to cure at room temperature for 24 h, then removed from the tubing mold and stored at 4 °C until surgical implantation. Testosterone enanthate oxidizes at high temperatures which is why the implants had to be stored cold. Each implant was 9 cm long and contained 0.56 g of testosterone enanthate. A minimum of one implant (0.56 g testosterone enanthate) and a maximum of four implants (2.24 g testosterone enanthate) were placed in the cervical subcutaneous fat of each pig. After implantation, serum testosterone was assessed over 40 days. Silastic testosterone enanthate implants increase serum testosterone and maintain it in a relatively constant state in a dose-dependent manner for ∼ 21-25 days post-implantation. •Effective method for subcutaneous delivery of large quantities of testosterone or testosterone metabolites in compact implants to large animal biomedical model species.•Maintains increased circulating testosterone levels for up to 3, 4 weeks post-implantation in pigs.

Silastic Joint Arthroplasty as a Joint-Preserving Alternative for End-Stage Hallux Rigidus: Outcomes From 112 First Metatarsophalangeal Joint Arthroplasties.

Aim Osteoarthritis of the first metatarsophalangeal joint (MTPJ) is a common forefoot problem affecting patients in later years. It leads to pain, gait problems, and difficulty with activities of daily living. Treatment is controversial and varies according to patient symptoms and surgeon preference. Arthrodesis remains the gold standard but it has its own complications. It is associated with adjacent joint arthritis and transfer metatarsalgia. The aim of this study was to analyze the outcome of double-stemmed silastic joint arthroplasty (Wright-Medical, Memphis, TN) for end-stage hallux rigidus. Methods This retrospective analysis included 117 consecutive first MTPJ silastic arthroplasties done between January 2016 and February 2023 for end-stage hallux rigidus. There were 77 females and 40 males with a mean age of 65 years (46-82 years). Radiological and clinical assessments were performed, and patient-reported outcome measure data (PROMS) and visual analogue scale (VAS) scores were collected pre- and post-operatively. Results Findings showed 99.1% survivorship following a silastic joint arthroplasty with a mean follow-up of four years (six months to seven years). The MOXFQ (Manchester Oxford Foot Questionnaire) score improved from a mean of 81 (59.8-100) to 13 (0-57). The mean VAS scores improved from 7.2 (5-10) to 1.5 (0-7) postoperatively. Five patients were lost to follow-up. Two patients developed deep infection and one required revision. The other patient with infection was lost to follow-up. In total 10 patients (8.9%) developed complications, out of which eight patients responded to simple treatments. Conclusion Results have shown good to excellent outcomes following a silastic arthroplasty of the first MTPJ for the treatment of end-stage hallux rigidus. The survivorship at a mean follow-up of four years was 99.1% and the patient satisfaction rate was 90.1%. As historically reported, we did not see any soft tissue reaction or progressive osteolysis in any of our patients. It provides comparable and predictable outcomes to joint fusion for end-stage arthritis.

Shapes and Sizes of Common Silicone Metacarpophalangeal Arthroplasties: Clinical Implications.

Background: Silastic metacarpophalangeal joint (MCPJ) arthroplasty is a recognised treatment for painful finger arthritis. There are two commonly used, albeit different, designs; the Swanson and the NeuFlex©. Which design is optimal is unclear. The purpose of this study was to evaluate the radiological differences relative to the bones following implantation. Methods: We examined the radiological features of these implants up to 1 year of follow-up. We reviewed the postoperative radiographs of 42 patients with 113 MCPJ arthroplasties and assessed the implant body anatomical 'fit' relative to the widths of the cut metacarpals and proximal phalanges and resection lengths of the metacarpal heads. We also looked for potential axial implant rotation. Results: The Swanson implants were consistently and statistically significantly wider than the NeuFlex© implants and almost always overhung the margins of the native MCPJ. Four of 33 (12%) of the Swanson and 1 of 80 NeuFlex© implants had rotated axially, the difference was statistically significant. One NeuFlex© implant had fractured at its hinge. Conclusions: The appreciable difference in the positions of the implant bodies relative to the bones may be important. The overhang of the Swanson implants may confer some stability to the arthroplasty helping to resist lateral deviation forces, but concomitant ligament reconstruction may increase the risk of implant rotation which is likely to reduce the postoperative ranges of motion. Axial silastic implant rotation has not previously been reported. It may influence joint biomechanics; future implant designs should consider the risks of implant rotation. Level of Evidence: Level IV (Therapeutic).

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

Silastic implants for the first metatarsophalangeal joint (MTPJ) have been in use for over 50 years. Initial reports were associated with high failure rates leading to development of new designs that are currently in use.The aim of this article is to review the historical evolution and the outcomes of silastic implants for the treatment of end-stage OA of the first MTPJ. Databases were searched for studies reporting the outcomes of silastic implants for the first MTPJ. Various relevant search terminologies were used. Studies reporting the outcomes of metallic implants or arthrodesis were excluded.The literature search revealed 522 studies, of which 28 were included. Eight studies used single-stemmed implants and 20 used double-stemmed implants for their patients. Twenty-eight studies had a total of 2354 feet with silastic replacements in 1884 patients (1968 to 2003) with an average age of 53 years and the average follow-up was 85.3 months. There were a total of 5.3% (124 feet) failed prostheses. Improvement in pain was reported in 76.6% (1804 feet) with an average patient satisfaction rate of 84%. Radiological changes around the implants were found to be significantly higher with single-stemmed implants (30.3%) compared to the double-stemmed implants (14.7%) (p < 0.05).Significantly more single-stemmed implants failed (11%) than the double-stemmed implants (3.6%) (p < 0.05). Despite the initial reports of failed implants and complications, first- and second-generation silastic implants were associated with high patient satisfaction and pain improvement. Current literature lacks long-term outcomes of implants currently in use. Cite this article: EFORT Open Rev 2019;4:77-84. DOI: 10.1302/2058-5241.4.180055.

Comparison of Two Methods of Estradiol Replacement: their Physiological and Behavioral Outcomes.

Fluctuating sex steroids during the estrous or menstrual cycle of mammalian females make it difficult to determine their role on behaviors and physiology. To avoid this, many investigators ovariectomize their animals and administer progesterone, estradiol or a combination of both. Several different strategies are used to administer estradiol, which confounds interpretation of results. This study compared two methods of estradiol replacement implants: Silastic tubes filled with crystalline estradiol benzoate (E2) and commercially available estradiol benzoate pellets. Implants were placed subcutaneously in adult ovariectomized (OVX) rats and blood samples obtained weekly. Control OVX rats received empty Silastic tubes or placebo pellets. Our data shows that E2 plasma levels from rats with Silastic implants peaked after one week and decreased slowly thereafter. In contrast, plasma E2 from commercial pellets peaked after two weeks, increasing and decreasing over time. To validate hormone release, body weight was monitored. All E2 treated animals maintained a similar body weight over the four weeks period whereas an increase in body weight over time was observed in the OVX group that received empty implants, confirming E2 release and supporting the role of E2 in the regulation of body weight. Furthermore, the effects of E2 on basal locomotor activity were assessed using animal activity cages. Results showed no difference between E2 and control group in several locomotor activities. These results indicate that Silastic implants achieve more stable plasma estradiol levels than pellets and thus are a better alternative for studies of estradiol on brain function and behavior.