We performed a retrospective study on 178 Scarf osteotomies with a mean follow-up of 44.9 months (range 15-83 months). Clinical rating was based on the forefoot score of the American Orthopaedic Foot and Ankle Society (AOFAS). Weight bearing X-rays were used to perform angular measurements and assess the first metatarsophalangeal joint (MTP 1). At follow-up the mean AOFAS score had improved significantly (p<0.001), but only 55% of the feet showed a perfect realignment of the first ray. Patients with a hallux valgus angle exceeding 30°and preexisting degenerative changes at the MTP 1 joint displayed inferior clinical results (p<0.05). Nearly 20% of the patients suffered from pain at the MTP 1 joint. This was clearly attributed to an onset or worsening of distinct radiographic signs of arthritis (p<0.05) resulting in painfully decreased joint motion. Comparing radiographic appearance three months postoperatively and at follow-up, we found that radiographic criteria (hallux valgus, first intermetatarsal angle, hallux valgus interphalangeus, MTP 1 joint congruency, arthritic lesions at MTP 1) worsened with time.

Replacement of the first metatarsophalangeal joint (MTP1) is still controversial when compared with MTP1 fusion in treating hallux rigidus and other disabling conditions of the MTP1 joint. Prospective studies concerning endoprosthetic replacement of the MTP1 joint are not available yet. Nevertheless, better understanding of biomechanics and tribology show favour towards total endoprosthesis. Some currently available models are described (Toefit-Plus, Roto-glide, ReFlexion, Bio-Action, Moje). Furthermore the authors report their results with 30 Toefit-Plus total endoprostheses. Five complications (16.6%) included two dislocations of total prostheses and three bone fissures. In 3 of 14 cases (21%) with a 3-year follow-up, revision surgery was necessary (subluxation, persistent pain, recurrence of hallux rigidus). Of 11 cases (63%) with a 4-year follow-up, 7 revealed secondary loss of range of motion. A more aggressive postoperative treatment with early weight bearing and regular push-off of the first ray is recommended. Based on our results, MTP1 replacement should be indicated restrictively (hallux rigidus, no experiments in cases of important first ray insufficiency).

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Osteoarthritis of the first metatarsophalangeal joint (MP1 joint) causes a painful dysfunction of the forefoot, substantial gait changes, limitation of patient's life quality, and work disability. Possible surgical therapy options for this joint degeneration are joint-preserving, joint-stabilizing, or joint-replacing techniques. Joint-preserving techniques have shown good results in the early stage of this entity but a high recurrence rate over the years. Jointstabilizing and fusioning techniques have been the golden standard in the severe and end stages and show good to excellent long-term results. However, the use of MP1 joint replacement might be preferred in a few indications. In this paper a new modular implant system for MP1 joint replacement is presented. The Toefit-Plus TM system consists of nonconstrained implants for hemi-or total joint replacement. A noncemented, self-tapping fixation principle together with the osteophilic properties of the implants ensure excellent stability. Modularity allows intraoperative and secondary hemi-to total conversion and offers reasonable second lines of defense in case of failure. Indications, operative technique, and results after 48 months mean follow-up time are presented. Future research on implant design and functional rehabilitation is advised to improve the range of sometimes restricted dorsiflexion.

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