Arthroplasty in the hand: what works and what doesn't?

Toward a disruptive, minimally invasive small finger joint implant concept: Cellular and molecular interactions with materials in vivo

Osteoarthritis (OA) poses significant therapeutic challenges, particularly OA that affects the hand. Currently available treatment strategies are often limited in terms of their efficacy in managing pain, regulating invasiveness, and restoring joint function. The APRICOTⓇ implant system developed by Aurora Medical Ltd (Chichester, UK) introduces a minimally invasive, bone-conserving approach for treating hand OA (https://apricot-project.eu/). By utilizing polycarbonate urethane (PCU), this implant incorporates a caterpillar track-inspired design to promote the restoration of natural movement to the joint. Surface modifications of PCU have been proposed for the biological fixation of the implant. This study investigated the biocompatibility of PCU alone or in combination with two surface modifications, namely dopamine-carboxymethylcellulose (dCMC) and calcium-phosphate (CaP) coatings. In a rat soft tissue model, native and CaP-coated PCU foils did not increase cellular migration or cytotoxicity at the implant-soft tissue interface after 3 d, showing gene expression of proinflammatory cytokines similar to that in non-implanted sham sites. However, dCMC induced an amplified initial inflammatory response that was characterized by increased chemotaxis and cytotoxicity, as well as pronounced gene activation of proinflammatory macrophages and neoangiogenesis. By 21 d, inflammation subsided in all the groups, allowing for implant encapsulation. In a rat bone model, 6 d and 28 d after release of the periosteum, all implant types were adapted to the bone surface with a surrounding fibrous capsule and no protracted inflammatory response was observed. These findings demonstrated the biocompatibility of native and CaP-coated PCU foils as components of APRICOTⓇ implants. STATEMENT OF SIGNIFICANCE: Hand osteoarthritis treatments require materials that minimize irritation of the delicate finger joints. Differing from existing treatments, the APRICOTⓇ implant leverages polycarbonate urethane (PCU) for minimally invasive joint replacement. This interdisciplinary, preclinical study investigated the biocompatibility of thin polycarbonate urethane (PCU) foils and their surface modifications with calcium-phosphate (CaP) or dopamine-carboxymethylcellulose (dCMC). Cellular and morphological analyses revealed that both native and Ca-P coated PCU elicit transient inflammation, similar to sham sites, and a thin fibrous encapsulation in soft tissues and on bone surfaces. However, dCMC surface modification amplified initial chemotaxis and cytotoxicity, with pronounced activation of proinflammatory and neoangiogenesis genes. Therefore, native and CaP-coated PCU possess sought-for biocompatible properties, crucial for patient safety and performance of APRICOTⓇ implant.

More than 10 years' follow-up of the Swanson metacarpophalangeal joint arthroplasty for the rheumatoid hand

BACKGROUND

In recent years, advances in pharmacotherapy for rheumatoid arthritis have dramatically improved the control of disease activity. However, a significant number of patients still develop hand deformity and require surgical reconstruction. The objective of this study was to evaluate the long-term efficacy and drawbacks of the Swanson metacarpophalangeal joint arthroplasty for patients with rheumatoid arthritis over 10 years.

METHODS

Clinical and radiological evaluations were performed for 87 joints of 29 hands in 27 patients who underwent metacarpophalangeal joint arthroplasty using the Swanson implant, and who were followed up for an average of 11.4 (10-14) years.

RESULTS

The number of operated tender and swollen metacarpophalangeal joints decreased from 24 (27.6%) and 28 (32.2%) to 1 (1.1%) and 2 (2.3%), respectively. The patients' general health and disease activity score 28-erythrocyte sedimentation rate improved at the last survey. Mild recurrence of ulnar drift was observed, but the deformity was generally well-corrected. Implant fracture was noted in eight joints (9.2%), and revision surgery was performed in two joints (2.3%). The average active range of extension/flexion changed from -46.3°/65.9° to -32.3°/56.6°. While a significant change was not noted in grip or pinch strength, patients were satisfied with the operation especially in terms of pain relief and improved hand appearance.

CONCLUSIONS

The long-term results of Swanson metacarpophalangeal joint arthroplasty were good in pain relief and correction of deformity, but some problems remain with regard to implant durability and mobility.

Small Joint Arthroplasty of the Hand: An Update on Indications, Outcomes, and Complications

Small joint arthroplasty of the hand is a well-established surgery that can preserve motion and provide reliable pain relief, joint preservation, and improvement in hand function. Soft-tissue integrity is critical in patient and implant selection to avoid postoperative joint instability. Although instability is more common in nonconstrained implants such as pyrocarbon, silicone arthroplasty is associated with high rates of late implant fracture and failure with resultant recurrent deformity and instability. Additional complications such as stiffness, extension lag, and intraoperative fractures may be mitigated by alterations in surgical technique and postoperative rehabilitation protocols. Revision arthroplasty with soft-tissue stabilization procedures have reliable outcomes and can avoid conversion to arthrodesis. This article will review the surgical indications, outcomes of small joint arthroplasty in the hand, and common complications and their management.

Pyrocardan® interpositional arthroplasty for trapeziometacarpal osteoarthritis: a minimum four year follow-up

BACKGROUND

Pyrocardan® (Wright Medical-Tornier) is a pyrocarbon implant proposed in the treatment of trapeziometacarpal joint (TMCJ) osteoarthritis. Our aim was to assess the clinical and radiographic results after Pyrocardan® arthroplasty at midterm follow-up.

METHODS

In this prospective monocentric study, we enrolled 119 patients treated with Pyrocardan® for TMCJ osteoarthritis and followed up at a minimum of four years. The clinical outcome was assessed through the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, the Visual Analog Score (VAS) for pain and the Kapandji score collected pre-operatively, at three, six and 12 months, then yearly. Hand radiographs were taken before surgery, at three months and every year. Complications and re-operations were also recorded.

RESULTS

The mean follow-up was 5.2 years (range, 4-9). DASH, VAS and Kapandji scores significantly improved at three (p < 0.001 in all cases) and six months (p < 0.001, p = 0.01 and p < 0.001, respectively), remaining stable over time. The dislocation and subluxation rates were 3.3% (4 cases) and 16.8% (20 patients), respectively. The two year, four year and seven year survivorship of the implant was 99%, 98% and 95%, respectively.

CONCLUSION

Pyrocardan® arthroplasty provides a satisfactory clinical and radiographic outcome for treating TMCJ osteoarthritis, with a 97% survival rate at four years. We advocate comparative studies with more common techniques (i.e., trapeziectomy) to verify its cost-effectiveness.