Case Overview We present a case of tendon sheath reconstruction for extensor carpi ulnaris instability. We also discuss indications, contraindications, technical pearls, and potential pitfalls. Method/Technique Tendon sheath reconstruction for extensor carpi ulnaris instability is performed. The technical pearls and potential pitfalls of this procedure are discussed. Results Historical results and outcomes from earlier literature are presented and discussed. Summary We present a case of tendon sheath reconstruction for extensor carpi ulnaris instability. We discuss indications, contraindications, technical considerations, and outcomes.