{'fraction_non_alphanumeric': 0.026404224675948152, 'fraction_numerical': 0.016802688430148822, 'mean_word_length': 5.023121387283237, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Fracture of the proximal phalanx pyrocarbon implant after metacarpophalangeal arthroplasty

Dear Sir, In reference to the letter previously published (Syed et al., 2010), we present a stem fracture in the distal proximal phalangeal component of a pyrocarbon implant (Ascension Orthopaedics Inc., Austin, Texas, USA). A 63-year-old gentleman had a pyrocarbon arthroplasty of his non-dominant left index metacarpophalangeal joint (MCPJ) for primary osteoarthritis. He had had his right index and middle finger MCPJs successfully replaced with the same implants, 2 years before. The surgery was uneventful and he made an uncomplicated recovery. Six weeks after surgery, the active range of movement of the MCPJ was 21–70 flexion, the grip strength was 30 kg and tripod pinch strength was 6.8 kg. His quick DASH score was 4.6. Within 6 weeks of surgery he managed to re-tile his roof and he remained asymptomatic undertaking many heavy manual DIY tasks throughout the next 12 months. A radiograph taken 2 months after surgery showed satisfactory implant position with no evidence of lucency around the stem (Fig 1). A routine radiograph taken at one year demonstrated a transverse fracture through the stem of the proximal phalangeal component (Fig 2). The patient was asymptomatic at 20 months, although his grip strength had decreased slightly to 27 kg and he remains under regular surveillance. The implant failure occurred at the transition zone between metaphyseal and diaphyseal bone. The implant appeared well fixed distally. Possible reasons for the fracture could include over-reaming of the metaphysis, subtle rotational malposition or stress shielding proximally although pyrocarbon has a Young’s modulus similar to bone. Our patient had an asymptomatic fracture of the stem of the proximal phalangeal component of a pyrocarbon implant. The only other component fractures were described by Syed et al. (2010) and Cook et al. (1999), both of which needed revision. We agree with the previous recommendation to restrict heavy manual tasks in patients having pyrocarbon implants.