Posterior Ankle and Hindfoot Arthroscopy

Hindfoot pain can be caused by any part of the posterior ankle anatomy with bony and soft tissue, including os trigonum, large posterior talar process, tenosynovitis of the flexor hallucis longus tendon, osteochondral lesions of the talus, subtalar arthritis and arthrosis, prominent calcaneus posterior process and free bodies, such as synovial chondromatosis. Because these structures are deeply situated and difficult to palpate, there remain diagnostic difficulties. Posterior ankle and hindfoot arthroscopy gives excellent access to such a posterior ankle compartment1, and it is regarded as the ideal diagnostic tool for accurate diagnosis of the hindfoot disorders. Furthermore, it is also regarded as an effective tool especially for the athletes who expect to return to their initial athletic activities with a shorter recovery time. The arthroscopic approach to the posterior ankle was first described by Parisien and Vangsness in 1985 as a subtalar arthroscopy2. In 2000, van Dijk advanced an epoch-making technique, a two portal endoscopic approach, which makes it possible to obtain broad field of vision and working space1. Recently, posterior ankle and hindfoot arthroscopy utilizing a two portal endoscopic approach has been developed and widely used for diagnosis and treatment of hindfoot disorders. In this part, the author describes the posterior ankle and hindfoot arthroscopy utilizing a two portal endoscopic approach.


Introduction
Hindfoot pain can be caused by any part of the posterior ankle anatomy with bony and soft tissue, including os trigonum, large posterior talar process, tenosynovitis of the flexor hallucis longus tendon, osteochondral lesions of the talus, subtalar arthritis and arthrosis, prominent calcaneus posterior process and free bodies, such as synovial chondromatosis. Because these structures are deeply situated and difficult to palpate, there remain diagnostic difficulties. Posterior ankle and hindfoot arthroscopy gives excellent access to such a posterior ankle compartment 1 , and it is regarded as the ideal diagnostic tool for accurate diagnosis of the hindfoot disorders. Furthermore, it is also regarded as an effective tool especially for the athletes who expect to return to their initial athletic activities with a shorter recovery time. The arthroscopic approach to the posterior ankle was first described by Parisien and Vangsness in 1985 as a subtalar arthroscopy 2 . In 2000, van Dijk advanced an epoch-making technique, a two portal endoscopic approach, which makes it possible to obtain broad field of vision and working space 1 . Recently, posterior ankle and hindfoot arthroscopy utilizing a two portal endoscopic approach has been developed and widely used for diagnosis and treatment of hindfoot disorders. In this part, the author describes the posterior ankle and hindfoot arthroscopy utilizing a two portal endoscopic approach.

Indications
The indications of hindfoot endoscopy are posterior ankle joint pathologies including osteochondral lesions of the posterior talus, loose bodies, ossicles, posttraumatic calcification or avulsion fragment; posterior subtalar joint pathologies including osteophyte, loose bodies, osteoarthritis or intraosseous talar ganglion; periarticular pathologies including posterior ankle impingement syndrome, deltoid ligament avulsion, tenosynovitis or intratendinous ganglion of the flexor hallucis longus, tenosynovitis or partial rupture of the peroneal tendon and posterior tibial tendon, retrocalcaneal bursitis and entrapment of the tibian nerve within the tarsal tunnel 3 .

Set-up and normal anatomy 2.2.1 Set-up
Hindfoot endoscopy was performed under spinal lumbar anesthesia. The patient was placed in a prone position on an operating table (Figure 1). www.intechopen.com A small support was placed under the lower leg. A pneumotourniquet is inflated to a pressure of 300 mm Hg. An arthroscope 4.0 mm in diameter with a 30 degree angle and the irrigation of saline with a pressure of 50 to 80 mmHg is used. Although any distraction device may not be needed in most cases, the bandage distraction technique 4 with a force of 78.4 Newtons ( Figure 2) is beneficial in cases where it is needed to be widen the posterior talocrural joint (Figure 3).

Making the portal and the working space
A line was drawn from the tip of the lateral malleolus to the Achilles tendon, parallel to the sole of the foot. The posterolateral and posteromedial portals were made just above this line and 3 mm medial and lateral of the Achilles tendon using a pneumotourniquet inflated to a pressure of 300 mm Hg ( Figure 4). If the portals are close to the Achilles tendon it may lead to tenosynovitis of the Achilles tendon. On the other hand, if the portals are too far from the Achilles tendon, it is difficult to watch the field fully. The deep layer is split by mosquito clamp via a posterolateral portal that is directed to the first web or second toe through the 1 cm vertical skin incision ( Figure  5). When the tip of the clamp touches the bone, it is exchanged for a 4.5 mm arthroscope shaft with the blunt trocar to direct to the first web or second toe ( Figure 6). www.intechopen.com

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The trocar is exchanged to an arthroscope 4.0 mm in diameter with a 30 degree angle. Next, a mosquito clamp is introduced via a posteromedial portal. A mosquito clamp touches the shaft of the arthroscope and the deep layer around the arthroscope is split. A 4.0 to 5.0 mm motorized shaver (full radius shaver) is inserted through the posteromedial portal in order to make the working space ( Figure 7). For bringing the shaver into the field of vision of the arthroscopy, it is helpful that the tip of the shaver touches the shaft of the arthroscope and slide distally (Figure 8). Adipose tissue and the posterior joint capsule are removed by motorized shaver. First of all, the surgeon must show the FHL tendon ( Figure 9). The neurovascular bundle lies medial to the FHL tendon, so the surgeon should perform the arthroscopic surgery laterally to the FHL tendon ( Figure 10).      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 www.intechopen.com 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).

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Care should be taken as it is difficult for diagnosis of tenosynovitis of the FHL with preoperative imaging 7 , especially in the early stage cases. For treating this disorder, operative release of the FHL is recommended when disabling symptoms persist despite non-operative treatment [8][9][10][11][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). 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.

Osteoarthritis of the subtalar joint
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 arthritis [13][14][15][16][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 arthrodesis 18,19 , the recent trend is the use of www.intechopen.com the posterior two portals with patients in the prone position, permitting surgeons to access the posterior subtalar joint easily, as compared to the lateral approach 13,17 . Accompanying techniques, such as the use of a third accessory portal 14,15,17 or bone substitute for grafting 13,15 , have been reported to result in successful prognosis without complications. The author recommends arthroscopic subtalar arthrodesis via a posterior approach using two portals accompanied by grafting of autologous cancellous bone, which is harvested by means of a tube harvester and grafted thorough these arthroscopic portals. First, the shaver is inserted through the posteromedial portal and the soft tissue is removed until the FHL tendon is identified by arthroscopic visualization. If tenosynovitis is present around the FHL tendon, release of the flexor retinaculum and synovectomy are performed. After identification of the FHL tendon, the soft tissue overlying the posterior facet of the subtalar joint is removed from the lateral field of the FHL tendon. Next, the articular cartilage of the posterior facet of the subtalar joint is removed using a small chisel and a shaver until subchondral bone is exposed (Figure 16). After curettage of the anterior region of the posterior facet is confirmed arthroscopically, temporary fixation is performed using guide wires with the hindfoot in a neutral position. Subsequently, cancellous autograft bone is harvested from the ipsilateral iliac crest by using a tube harvester (OATS system, Arthrex, Naples, Florida) ( Figure 17). Two or three rigid cancellous bone plugs harvested through an approximately 1.5-cm skin incision are cut by a blade into small bone columns ( Figure 18) so that autologous bone grafting is easily performed via arthroscopic portals.  Under arthroscopic visualization, two guide wires of the headless cannulated screws (Acutrak plus, Acumed, Hillsboro, Oregon) are inserted from the plantar of the heel to the talus body through the posterior facet of the subtalar joint and was followed by the overdrilling ( Figure 19). After autologous bone is grafted to the void after curettage of the posterior facet of the subtalar joint via portals (Fugure 20), the headless cannulated screws with a diameter of 6.5 mm are inserted (Figure 21). www.intechopen.com   After surgery, operated feet are not placed in casts, and active range-of-motion exercise of the talocrural joint is allowed the next day. Partial weight-bearing is allowed six weeks after surgery and full weight-bearing is permitted after a bridging callus is confirmed between posterior facets by radiological investigation.

Conclusion
Since 1997, the author has performed about 300 hindfoot endoscopic procedures utilizing posterior two portals without any complications. The patients complained of less pain after surgery and recovered earlier than those who underwent open surgery. The author believes that hindfoot endoscopic surgery, performed by an experienced arthroscopist who has enough knowledge for local anatomy and become skillful in this art, is safe and reliable method for posterior ankle disorders.