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Surgical Pearls

Current Perspectives On Posterior Ankle Endoscopy/Arthroscopy

Posterior ankle arthroscopy is somewhat of a misnomer. It is initially an endoscopic approach to access the posterior ankle and subtalar joint complexes. Endoscopic techniques for posterior ankle pathology have come into increasing favor by many surgeons, including myself, over traditional open surgery. The benefit is similar to that of anterior ankle arthroscopy and, in fact, all other joint arthroscopy.

I commonly treat posterior ankle impingement syndrome with an endoscopic approach. However, I have recently advanced this technique for harvesting and transfer of the flexor hallucis longus tendon, and chronic Achilles tendinopathy in the presence of a posterior calcaneal enthesophyte.

The minimally invasive nature of arthroscopy limits surgical trauma, reduces risk of infection, allows for a magnified view of diseased tissue and advances patient recovery time. Unlike anterior ankle arthroscopy, which permits immediate entrance to and visualization of the joint, posterior ankle arthroscopy requires endoscopic debridement of intervening tissue. This includes debridement of posterior ankle fat and the crural fascia, which will ultimately lead to arthrotomy of the joint. Accordingly, posterior ankle arthroscopy does have a learning curve and should be conducted by an experienced arthroscopist.

When it comes to endoscopic/arthroscopic evaluation, the posterior ankle joint anatomy is well-defined. Medially, consequential structures including the flexor tendons and neurovascular bundle are critical in establishing this margin of our working environment. All of our work is intended to remain lateral to the flexor hallucis longus tendon so as not to violate the neurovascular complex (see first photo above). Directly posterior is the Achilles tendon, which does serve in producing medial and lateral borders for portal creation. Laterally, the peroneal tendons serve to establish a boundary protecting the sural nerve and small saphenous vein. Directly anterior are the osseous structures of the tibia, talus and calcaneus with the intervening tissue of the crural fascia, posterior joint capsule and ligamentous structures.

Reviewing Treatment Options For Posterior Ankle Impingement Syndrome

One of the more common reasons for performing posterior ankle arthroscopy is posterior ankle impingement syndrome. This impingement may represent a chronic compression of posterior soft tissue structures. Most commonly, this will involve the flexor hallucis longus tendon and one frequently sees this in classical ballet dancers due to repetitive dorsiflexion and plantarflexion of the foot. It can also occur in soccer players when a plantarflexed foot strikes the ball. This action may result in acute avulsions of the lateral process of the talus or Stieda’s process.

Workup for this syndrome includes a physical exam, imaging to include plain radiographs and/or magnetic resonance imaging (MRI), and injections that can serve diagnostic and therapeutic purposes.

Conservative management includes immobilization, physical therapy, activity modification and bracing, or orthotics if the impingement syndrome is due to a biomechanical issue. Those who fail to respond to these measures over three to six months would be reasonable candidates for surgical intervention.

Surgeons should consider open versus arthroscopic management. In a randomized, controlled study, Georgiannos and Bisbinas assessed open and endoscopic techniques in 52 athletes who were suffering from posterior ankle impingement syndrome between 2008 and 2011.1 Patients were equally divided between open and endoscopic techniques. While both approaches led to good functional results and pain relief, endoscopic surgery reportedly yielded a faster return to sport.1

Pertinent Tips And Techniques For Posterior Ankle Endoscopy/Arthroscopy

A safe and reliable endoscopic approach to the posterior ankle joint has been well documented, illustrated and published by van Dijk and colleagues in their 2000 study.2

After ensuring prone placement of the patient on the operating room table with a thigh or calf tourniquet, the surgeon should use a ramp bump to elevate the foot and naturally flex the knee. One can then outline the pertinent anatomic structures and identify the tip of the lateral malleolus. The surgeon then extends a straight line from lateral to medial across the posterior ankle, paralleling the weightbearing surface of the heel. Proceed to identify and mark the medial and lateral borders of the Achilles tendon. The intersection of these lines establishes both posteromedial and posterolateral portal sites (see second set of  photos above). Lastly, the surgeon should direct a line plantarly along the foot from the lateral portal to the first intermetatarsal space to orient initial instrumentation placement.2      

Create the posterolateral portal with a stab incision. Then perform blunt dissection with a hemostat along the plantar first intermetatarsal line to a firm stop against the posterior ankle joint. Introduce the obturator and cannula for a 4.0 mm, 30-degree scope along this corridor. Withdraw the obturator and introduce the scope.

Create the posteromedial portal next with a similar initial stab and blunt dissection with a hemostat. In this case, direct the hemostat at 90 degrees to come into contact with the shaft of the cannula and scope. Slowly walk the hemostat down the shaft. Once the arthroscope is in contact with the posterior ankle, gently walk the arthroscope back to triangulate with the hemostat and visualize on the monitor. Withdraw the hemostat and introduce an engine device, such as a shaver, through the posteromedial portal in a similar fashion until one can see the shaver and begin local debridement (see bottom right photo).

Throughout the entire procedure, it is important to place all engine equipment through the posteromedial portal and direct it laterally to avoid injury to the medial neurovascular structures. During the initial arthroscopic evaluation, identify the flexor hallucis longus tendon and remain lateral to this structure during the procedure. With this access, one can readily perform excision of a symptomatic os trigonum, excision of a posterolateral fracture fragment and/or debridement of the flexor hallucis longus tendon. Upon completion of the procedure, remove the instrumentation and close the portals with simple interrupted sutures.

Addressing A Case Of Recalcitrant Posterior Ankle Pain In An Athlete

A 32-year-old semi-professional soccer player presented to my office after sustaining an acute injury of the right ankle. The mechanism of injury was fixed plantarflexion of the foot. The patient was attempting to strike the soccer ball when he was challenged by a slide tackle. He experienced immediate pain with subsequent development of swelling and ecchymosis to the hindfoot and ankle. X-ray and MRI of the right ankle demonstrated findings consistent with an acute avulsion fracture of the posterior talus (see third images above).

Initial treatment consisted of immobilization, elevation and restricted activity for three weeks with subsequent referral to physical therapy and rehabilitation. He appropriately transitioned to full weightbearing status after six weeks and proceeded with advancing phases of rehabilitation. At three months post-injury, he continued to experience ankle pain posteriorly. Additionally, the patient had persistent challenges when attempting to perform sport-specific activities such as striking the ball with the foot plantarflexed.

Subsequent MRI of the right ankle suggested limited healing of the avulsed fracture fragment. In order to help the patient return to his sport for the upcoming season, we discussed and proceeded to perform endoscopic excision of the fracture fragment and debridement of the flexor hallucis longus tendon.

The patient presented one week after surgery with no swelling and limited pain. We removed the sutures at 10 days postoperatively. The patient proceeded to immediate post-op rehabilitation and returned to soccer activities six weeks after the procedure with minimal pain and dysfunction. At eight weeks postoperatively, he was asymptomatic and fully engaged in sport.

When A Patient With Diabetes Has Unrelenting Posterior Heel Pain

As I mentioned earlier, I also use posterior arthroscopy/endoscopy for other disease states. To limit surgical trauma and the use of extensile incisions, particularly for compromised patients, I have employed this approach to perform calcaneoplasty for distal insertional Achilles tendinopathy with calcific enthesopathies.

A recent case example of this involved a patient with diabetes, who presented  with unrelenting posterior heel pain, which was non-responsive to exhaustive conservative care for greater than six months. To limit the risk of an often required large posterior heel incision, I performed arthroscopy/endoscopy via posteromedial and lateral incisions with the patient supine and a bump under the leg. After introducing the arthroscope and shaver in a similar manner, I performed local debridement. Lui demonstrated this approach well in a 2016 publication.3

Final Thoughts

With appropriate knowledge of local anatomy, one can reproducibly create safe corridors to the posterior ankle joint to allow for access of endoscopic equipment. This permits effective treatment of disease processes and injuries to this area. The notable advantage of endoscopic surgery in comparison to traditional surgery, as with any minimally invasive technique, is the limitation of surgical trauma, which helps facilitate a quicker recovery and return to activity and sport. 

Dr. Theodoulou is a Fellow of the American College of Foot and Ankle Surgeons. He is Chief of the Division of Podiatric Surgery with the Cambridge Health Alliance and is an Instructor of Surgery at Harvard Medical School. Dr. Theodoulou has disclosed that he is a consultant for Arthrex, Inc.

Surgical Pearls
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By Michael Theodoulou, DPM, FACFAS
References

References

1. Georgiannos D, Bisbinas I. Endoscopic versus open excision of os trigonum for the treatment of posterior ankle impingement syndrome in an athletic population: a randomized controlled study with 5-year follow-up. Am J Sports Med. 2017;45(6):1388-1394.

2. van Dijk CN, Scholten PE, Krips R. A 2-portal endoscopic approach for diagnosis and treatment of posterior ankle pathology. Arthroscopy. 2000;16(8):871-876.

3. Lui TH. Endoscopic calcaneoplasty and achilles tendoscopy with the patient in supine position. Arthrosc Tech. 2016;5(6):e1475-e1479.

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