Design of subtalar joint fusion plate and its application

Objective  To design a new calcaneal plate with function of subtalar joint compression fusion, and to evaluate its clinical effect for Sanders type Ⅳ calcaneal fracture.

Methods  A total of 50 cases with Sanders type Ⅳ calcaneal fracture requiring primary subtalar joint fusion were treated with internal fixation using a self-designed subtalar joint fusion plate. The anatomical morphology of the calcaneus was evaluated by observing Bolher Angle and Gissane Angle before operation, after operation and at the last follow-up, and the postoperative function was evaluated by the American Association of Foot and Ankle Surgery (AOFAS) ankle-posterior foot score.

Results  All 50 patients completed operations successfully, the operation time was from 37 to 72 min, with an average of (48.04±9.32) min, intraoperative bleeding volume was from 90 to 140 mL, with an average of (106.00±12.04) mL. There was no significant nerve and vascular injury during operation. All 50 patients were followed up, with follow-up time of 12 to 21 months and an average of (16.36±2.24) months. Bone healing was achieved at the last follow-up in all 50 patients, and the healing time was 8 to 14 weeks, with an average of (9.52±1.25) weeks. The postoperative and final follow-up Bolher angles were significantly larger compared with that before surgery (P < 0.001), while there were no statistically significant differences in Bolher angle and Gissane angle between postoperative and final follow-up (P=0.372, 0.140). AOFAS score at the last follow-up was (83.78±5.61), including 9 feet with excellent rating (score of 90 to 100), 39 feet with fine rating (score of 75 to less than 90), and 2 feet with good rating(score of 50 to less than 75), with an excellent and good rate of 96.00%. Postoperative skin edge necrosis occurred in 3 patients, and wound healed after multiple dressing changes.

Conclusion  The subtalar joint fusion plate is reasonable in designand can provide strong and firm fixation, with satisfactory intraoperative fracture reductionand simple operation. It is an ideal internal fixation material for Sanders type Ⅳ calcaneal fracture requiring primary subtalar joint fusion.