**2.3.1 Posterior ankle impingement syndrome**

Posterior ankle impingement syndrome (PAIS) is generally considered to be the clinical disorder characterized by posterior ankle pain in forced plantar flexion6. The etiology of this syndrome is varied and may involve any part of the posterior ankle anatomy, including bony and soft tissue structures. Among them, os trigonum and large posterior talar process are frequent (Figure 12).

An arrow shows a large posterolateral process of the talus and an arrow head shows an os trigonum.

According to the author's experiences gained in approximately 200 cases, it should be noted that hindfoot endoscopies have shown that large posterolateral talar processes compress a

Posterior Ankle and Hindfoot Arthroscopy 297

Care should be taken as it is difficult for diagnosis of tenosynovitis of the FHL with preoperative imaging7, especially in the early stage cases. For treating this disorder, operative release of the FHL is recommended when disabling symptoms persist despite non-operative treatment8-12, and hindfoot endoscopic surgery is beneficial, especially for athletes who expect to return to their initial athletic activities with a shorter recovery time. After removing the hypertrophic synovium over the FHL tendon with forceps, the hypertrophic flexor retinaculum, which lays at the insertion of the tarsal tunnel and/or abnormal bony structures, were removed with curved forceps and motorized shaver for

Fig. 15. Decompression of the flexor hallucis longus tendon (arrow) with curved forceps.

After surgery, the ankle was immobilized with an elastic bandage for two days. One day after the surgery, an active range of motion was allowed, and a passive range of motion was allowed two weeks after the surgery. Full weight bearing was allowed at 2 days after the surgery. Athletic activity was allowed if the patients feel no pain and no limitation of range of motion of their affected foot. They will return to the full athletic activity at four to seven

Recently, arthroscopic subtalar arthrodesis has been reported as an alternative to traditional open methods for intractable hindfoot disorders, such as subtalar arthritis after fracture of the calcaneus or talus, primary arthritis, talocalcaneal coalition or inflammatory arthritis13-17, because of its advantages, including minimizing invasion to the soft tissue around the hindfoot and preserving blood supply to the talus. Although the lateral approach using anterolateral and posterolateral portals in the supine or lateral decubitus position was initially introduced for arthroscopic subtalar arthrodesis18, 19, the recent trend is the use of

decompression of the constricted FHL tendon (Figure 15).

weeks after surgery.

**2.3.2 Osteoarthritis of the subtalar joint** 

FHL tendon in most cases (Figure 13) and in some cases constrict the FHL tendon at the posteromedial part of the fibro-osseous tunnel leading to tenosynovitis of the FHL (Figure 14).

Fig. 13. Flexor hallucis longus tendon (arrow head) compressed by large posterolateral talar process (arrow).

Fig. 14. Constriction of the flexor hallucis longus tendon (arrow head) at the posteromedial part of the fibro-osseous tunnel (cut, arrow).

FHL tendon in most cases (Figure 13) and in some cases constrict the FHL tendon at the posteromedial part of the fibro-osseous tunnel leading to tenosynovitis of the FHL (Figure 14).

Fig. 13. Flexor hallucis longus tendon (arrow head) compressed by large posterolateral talar

Fig. 14. Constriction of the flexor hallucis longus tendon (arrow head) at the posteromedial

part of the fibro-osseous tunnel (cut, arrow).

process (arrow).

Care should be taken as it is difficult for diagnosis of tenosynovitis of the FHL with preoperative imaging7, especially in the early stage cases. For treating this disorder, operative release of the FHL is recommended when disabling symptoms persist despite non-operative treatment8-12, and hindfoot endoscopic surgery is beneficial, especially for athletes who expect to return to their initial athletic activities with a shorter recovery time. After removing the hypertrophic synovium over the FHL tendon with forceps, the hypertrophic flexor retinaculum, which lays at the insertion of the tarsal tunnel and/or abnormal bony structures, were removed with curved forceps and motorized shaver for decompression of the constricted FHL tendon (Figure 15).

Fig. 15. Decompression of the flexor hallucis longus tendon (arrow) with curved forceps.

After surgery, the ankle was immobilized with an elastic bandage for two days. One day after the surgery, an active range of motion was allowed, and a passive range of motion was allowed two weeks after the surgery. Full weight bearing was allowed at 2 days after the surgery. Athletic activity was allowed if the patients feel no pain and no limitation of range of motion of their affected foot. They will return to the full athletic activity at four to seven weeks after surgery.
