Posterior ankle impingement surgery is an arthroscopic procedure to remove bone (os trigonum or Stieda's process) and soft tissue from the back of the ankle that causes pain in full plantarflexion — common in ballet dancers, footballers, and fast bowlers.
Performed arthroscopically through two small incisions at the back of the ankle (hindfoot endoscopy). The os trigonum (an accessory bone) or prominent Stieda's process (elongated posterolateral tubercle of the talus) is removed. Impinging soft tissue, including the flexor hallucis longus (FHL) tendon sheath, is debrided. The FHL tendon is released if it is tight or tendinopathic. The operation takes 30–45 minutes.
Surgery is recommended for posterior ankle pain provoked by full plantarflexion (pointing the foot down) — such as going en pointe in ballet, kicking a ball, or bowling in cricket — that has not responded to physiotherapy and injection.
Physiotherapy, corticosteroid injection (posterior ankle under ultrasound guidance), activity modification, and taping. Many cases resolve with non-operative management.
X-rays or CT showing os trigonum or posterior bony prominence. MRI to assess FHL tendon and surrounding structures. Day-case procedure.
Excellent pain relief and return to full plantarflexion in approximately 90% of patients. Very high satisfaction rates in dancers and athletes.
For two to four weeks.
Numbness on the outer heel. Usually temporary.
Temporary limitation of big toe flexion if the FHL was released.
Permanent numbness on the outer foot.
Damage during surgery.
Joint infection.
Very rare.
Residual symptoms from remaining bone.
General, spinal, or ankle block anaesthesia. Prone position.
Weight-bearing immediately. Ankle exercises from day one. Return to running at three to four weeks. Return to dance or sport at six to eight weeks. Full recovery two to three months.
Review at two weeks. Return to sport clearance at six to eight weeks.
An os trigonum is a small accessory bone at the back of the talus, present in approximately 10–15% of people. In most people it causes no problems, but in those who repeatedly plantarflex the ankle (dancers, footballers), it can become painful as it is compressed between the tibia and calcaneus.
Most dancers return to full pointe work at six to eight weeks after posterior impingement surgery.