Treatment of hallux rigidus by a novel bi-phasic aragonite-based implant: results of a two year multi-centre clinical trial

Purpose: The two year results of a multi-centre clinical trial were examined to evaluate surgical treatment of hallux rigidus using a novel, bi-phasic, biodegradable, and cell-free aragonite-based scaffold (Agili-C™, CartiHeal Ltd, Israel). Methods: Twenty patients with moderate-to-severe hallux rigidus were recruited. After thorough metatarsophalangeal joint (MTPJ-1) debridement, the scaffolds were implanted into the defect centre. Eight patients received concomitant osteotomy. Treatment outcome was followed clinically (Pain VAS, FAAM-ADL, FAAM-Sport, AOFAS-HMIS, maximum active range of extension ROM-EXT, and flexion ROM-FLEX), and by medical imaging, at six month intervals for two years. Adverse events were recorded throughout the study follow-up period. Results: Significant clinical improvement over time was observed in all evaluated parameters (screening to final evaluation averages: Pain VAS 59 to 26, FAAM-ADL 57 to 77, FAAM-Sport 39 to 66, AOFAS-HMIS 51 to 81, ROM-EXT 18° to 36°), except for ROM-FLEX. Radiographs showed stable MTPJ-1 width over the two years in 17/18 cases (94%). MRI demonstrated progressive implant biodegradation, coupled with articular cartilage and subchondral bone regeneration, with a repair tissue defect fill of 75–100% in 14/17 (82%) subjects at their final visit. Revision surgery with implant removal was performed in two patients. Conclusion: Bi-phasic, osteochondral, biodegradable, aragonite-based scaffold demonstrated positive clinical outcome and a good safety profile in the treatment of medium-to-advanced hallux rigidus. According to the medical imaging, this implant has the potential to restore the entire osteochondral unit of metatarsal head.