[Our Experience with the Total Replacement of the First Metatarsophalangeal Joint by Medin PH-flex]

The first metatarsophalangeal (MTP) joint replacement ranks among the treatment methods of patients with hallux rigidus. The paper aims to evaluate the short-term to mid-term outcomes and to present clinical experience with our Medin PH-flex implant. MATERIAL AND METHODS In the period from January 2011 to 2016 we performed total replacement of the first MTP joint in 31 patients, in 4 cases bilaterally. In total, 35 implants were evaluated. The mean age of the patient at the time of surgery was 57.7 years (39-72 years). The surgery was conducted in 29 women and 2 men. The patients were evaluated using the AOFAS score (American Orthopaedic Foot and Ankle Society score), the radiographs were assessed as to the potential occurrence of radiolucent lines, with major stress put on the assessment of the mobility in MTP joint and its position. The pain was assessed based on the VAS score. RESULTS Prior to the joint replacement surgery, the mean AOFAS score in patients was 55.6 (35-65). Postoperatively, the mean AOFAS score was 80.8 (65-95). The pain suffered by patients was evaluated with the use of the Pain Visual Analogue Scale (VAS score). The preoperative mean VAS score was 5 (2-8), whereas the postoperative score improved to mean VAS 2 (0-4). The range of motion was clinically assessed with a goniometer. The mean range of motion of plantar flexion and dorsiflexion was 16.00° (5-35°) and 28.60° (10-55°), respectively. The mean range of motion was 36° (15-60°). No intraoperative complications were observed. In all the patients, the surgical wound healed per primam. In 2 female - (5.7 %) of the whole group of patients who underwent surgery a deep infection occurred, namely 10 and 21 months following the implantation. In both the female patients their condition was managed by joint revision operation and by a simple removal of the implant. DISCUSSION Joint replacement related matters were repeatedly discussed in professional literature. There are many papers published in the literature on this topic. A whole range of the first MTP joint implants of different shapes have been developed, with extremely different clinical results. CONCLUSIONS An appropriately chosen type of the implant, a fitting indication and a correctly applied implantation technique can lead to the desired good outcome. The first MTP joint replacement should be indicated after careful consideration since the management of a potential joint replacement failure can often be very technically challenging and quite mutilating for the patient. The mid-term outcomes of the Medin a.s. first MTP implant seem to be promising. It will, however, be necessary to wait for long-term outcomes in order to evaluate the final benefits of this type of implant in patients with hallux rigidus. Key words: hallux rigidus, arthroplasty of the MTP joint, hemiarthroplasty, silicone implant.