Trends in clinical and basic research on rotator cuff tears in Japan

INTRODUCTION: Research on rotator cuff tears in Japan was initially characterized by studies clarifying prevalence, asymptomatic tears, and natural history. It subsequently developed toward evaluation of outcomes after arthroscopic repair, postoperative tendon integrity, and long-term results of conservative treatment. METHODS: This article reviews clinical and basic research on rotator cuff tears that has been conducted in Japan. RESULTS: Representative examples include arthroscopic superior capsule reconstruction (SCR), rotator cuff reconstruction combined with small-head hemiarthroplasty, arthroscopic muscle advancement, and infraspinatus rotational transfer. More recently, basic research on rotator cuff tears in Japan has shifted its focus from simply how to repair the torn tendon to how closely the tendon-bone insertion can be regenerated toward its native structure, and what biological and mechanical conditions can reduce retear. DISCUSSION & CONCLUSION: Because reverse total shoulder arthroplasty (rTSA) was introduced in Japan in 2014, later than in many other countries, several Japan-specific surgical techniques for massive rotator cuff tears were developed during the preceding period.