Proximal interphalangeal (PIP) joint replacements with pyrolytic carbon implants in the hand

[摘要] Until the late 1980s, finger joint prosthetic reconstruction had been almost exclusively performed by using monobloc silicone spacers as developed by Swanson et al more than 20 years previously.1 Such implants are not fixed to bone and prosthetic stems are free to glide into the medullary canal during flexion and extension. The so-called ‘piston effect’ allows the distribution of forces over a broader section and permits the flexible hinge to find a better position with respect to the axis of rotation of the joint.1 Outcomes were reasonably good, particularly in the metacarpophalangeal (MP) joints of patients affected by rheumatoid arthritis (RA) and degenerative osteoarthritis (OA). The experience in the reconstruction of proximal interphalangeal (PIP) joints showed variable results and has been reported as less satisfactory.2 Silicone spacers did not offer enough lateral stability, therefore showing high rates of angular instability and secondary wear, leading to stem breakage at the junction with the central body of the spacer. Moreover, in such cases silastic debris may induce a synovial inflammatory reaction leading to the well-known ‘silicone-related synovitis’. Thus, the need for alternative biomaterials and prosthetic designs for PIP articular reconstruction led to the development of new devices. Metal-on-polyethylene implants, cementless or cemented prostheses, total or hemi-arthroplasties, as well as pyrocarbon PIP joint prostheses were proposed with satisfactory results.3-10 The latter are characterised by a biologically inert and biocompatible material with a low tendency to wear. Such implants consist of anatomic bicondylar semi-constrained press-fit components made of a graphite core, visible on radiographs, covered by a radiolucent outer layer of pyrocarbon. A minimal bone resection is required in respect of the anatomical centre of rotation of the joint; collateral ligaments must be preserved or reconstructed. Initial experiences with pyrocarbon implants showed encouraging outcomes.5-11 At mid- and long-term follow-up, among satisfactory reports, early failures or component rupture were recorded.12-19 Post-operative satisfaction and functional ability have been addressed as the clinical parameters associated with variable results, given the generally higher pre-operative patients’ expectations and the actual improvement of range of movement (ROM) after surgery.6-8,14,17,19,20 From the surgeons’ perspective, the significant percentage of additional procedures or revision surgery (reported as up to 25% and 15%, respectively) represent the concern regarding the use of such implants.

[学科分类] 神经科学

[关键词] Proximal interphalangeal joint;finger joints replacement;pyrocarbon;pyrolitic carbon implants;Rheumatoid arthritis;Osteoarthritis;hand;fingers