Surgical management is indicated for patients following failure to address symptoms after 3 mo of conservative treatment. However, if athletic patients want to return to athletic activity promptly, then surgical intervention can be recommended early in the treatment process. Options include open treatment or arthroscopic intervention[3,22,23]. The advantages of arthroscopic procedures for PAIS are that they are less invasive, have a lower risk of postoperative complications, and shorter recovery time for returning to full activity. However, the technical difficulty and relatively steep learning curve are disadvantages. Additionally, it is difficult to perform simultaneous treatments for anterior ankle pathologies using a posterior two-portal approach, while subtalar arthroscopy or conventional ankle arthroscopy with posterolateral (PL) portal are more available.
For patients who have isolated PAIS, the authors utilize posterior hindfoot arthroscopy. For patients who require operative intervention for both PAIS and ankle anterior pathologies (e.g., anterior impingement syndrome, anterior OCL, degenerative ankle arthritis), the authors prefer to treat anterior pathologies in the supine position with traditional anterior arthroscopic portals, then, switch to the prone position for posterior hindfoot arthroscopy.
Typical arthroscopy equipment used in anterior ankle arthroscopy is required for posterior hindfoot arthroscopy. A 2.7/4.0 mm arthroscope with 30/70 degree viewing angle, a 3.5/4.5 mm shaver for soft tissue debridement, a 4.0 mm aggressive shaver or burr for bony resection, osteotomy, and fluoroscopy (optional) are used. Sizes of arthroscopes can be selected depending on the surgeon’s
preference. A thigh tourniquet is necessary to obtain good visualization of hindfoot anatomical structures. Additionally, an irrigation system is useful. The fluid pressure is usually set to 50-60 mmHg, and fluid flow is 0.5 L/min. Although dorsiflexion of hindfoot is usually applied for providing good visualization of the ankle and subtalar joints, a non-invasive distractor is may be applied to assist with visualization.
Marking anatomical landmarks and portal sites: In posterior hindfoot arthroscopy, a PL and PM portal are most commonly utilized. Prior to incision, landmarks including lateral malleoli (LM), medial malleoli (MM) and Achilles tendon should be marked using a sterile surgical marker. Portal sites should then be marked out. The portal sites are 1.0 mm anterior to the borders of Achilles tendon and at the level between the horizontal lines running from the inferior poles of MM and tip of LM (Figure 2). The sural nerve can be palpated and its course marked to avoid iatrogenic nerve injury.
Figure 2 The posterolateral and posteromedial arthroscopic portals.
Establishing portals: After all anatomic landmarks and portal sites have been identified and marked, a #11 blade should be used to make 1 cm vertical incisions at the labeled portal sites for the PM and PL portals. Then, subcutaneous blunt dissection using a mosquito clamp is performed via both portals. At this time, care must be taken to avoid damage to the sural nerve. The “nick and spread” technique is important to avoid sural neurovascular damages. A 2.7-mm arthroscope sleeve with trocar is carefully advanced via a PL portal to touch the posterior aspect of the talus by directing it towards the first interdigital web space. All instruments should be directed towards first interdigital web space to prevent iatrogenic neurovascular bundle injury in the hindfoot. Once the bone can be palpated with the trocar, it is switched out for a 2.7-mm arthroscope.
Creating working space: Initial visualization is poor because of the fat tissue located behind the posterior aspect of talus. After the shaver blade is confirmed in arthroscopic view, soft tissue is debrided to expose the intermalleolar (IM) ligament using a 3.5 or 4.0 mm aggressive shaver. The shaver blade must always be maneuvered very gently under arthroscopic visualization to avoid iatrogenic injury to healthy tissue.
Systematic four-stage approach to visualization of the hindfoot: The systematic approach in posterior ankle arthroscopy allows for a full assessment of all structures at the posterior ankle and subtalar joint (Figure 3). The anatomic landmark for defining the quadrants is the IM ligament that has been well described previously[26,27] based on the IM ligament, the hindfoot structures are divided into 4 regions of interest (superolateral, superomedial, inferomedial, and inferolateral). The authors prefer to start the inspection from the superolateral quadrant and then proceed to the other regions in a counterclockwise fashion for right ankles and a clockwise fashion for left ankles.
Figure 3 Hindfoot extra-articular structures divided into quadrants as defined by the intermalleolar ligament.
(1) Fibula, (2) tibia, (3) posterior-inferior tibiofibular ligament (transverse ligament), (4) flexor hallucis longus tendon, (5a) intermalleolar ligament, (5b) superior tibial insertion of the intermalleolar ligament, (6) tibiotalar joint, (7) subtalar joint, (8) posterolateral talar process, (9) flexor hallucis longus retinaculum, (10) calcaneofibular ligament, and (11) posterior talofibular ligament. Illustration is a copyright of and reproduced with permission from Kennedy JG, MD. Reproduction without express written consent is prohibited.
This quadrant contains the posterior inferior tibiofibular ligament, transverse ligament, and IM ligament. The IM ligament may be associated with PIM[8,27]. During inspection of the superolateral quadrant, the ankle should be passively plantarflexed to see if any of these ligaments are impinged under direct visualization. If impingement is present, the related structures should be debrided using a shaver or punch.
The FHL tendon and its associated fibro-osseous tunnel are found in this quadrant. Of note, the neurovascular bundle lies just medial to FHL tendon. It is therefore essential that any instruments should be maneuvered in the area lateral to FHL tendon. Additionally, surgeons should evaluate if the anomalous muscles particularly the peroneous qaurtus are present. It is sometime difficult to expose the FHL tendon because of soft tissue cicatrization. In these cases, moving (passive flexion/extension) the great toe may help surgeons identify the FHL tendon.
Tenosynovitis around FHL tendon is a typical finding in patients with hindfoot pain (63% to 85%)[8,28]. By moving the great toe, impingement of the tendon in its sheath can be identified and resected using a 4.5-mm shaver. A low-lying muscle of FHL can be found, which may cause impingement between the associated bony or soft tissues. Any tenosynovitis or identified impingement should be debrided.
A Stieda process or separate os trigonum can be observed in this region. These bony structures are removed using osteotomes or shaver, with care taken to avoid causing iatrogenic cartilage lesions in the subtalar joint. The scope and shaver are switched in order to gain optimal access to achieve adequate debridement. The posterior talofibular ligament (PTFL) that attaches to these structures may need to be released, however the authors prefer to preserve as much as possible of the posterior talofibular ligament.
Once those osseous structures are removed, the arthroscope is advanced into the fibro-osseous tunnel, which allows full visualization of the FHL tendon. Any pathology restricting smooth passive movement of the FHL tendon in the fibro-osseous tunnel such as vincula, nodules, or cicatrization should be debrided and removed.
The PTFL and the calcaneofibular ligament (CFL) are found in this region. The PTFL may be thickened and hypertrophied, requiring debridement. In the case of an ankle history of chronic lateral ankle instability, attenuation or scarring of the CFL may be found. Any tenosynovitis or identified impingement should be debrided.
Intra-articular inspection of the talocrural and subtalar joints: The talocrural joint and subtalar joint are inspected following visualization of all four quadrants of the hindfoot. Both joints can be visualized using same standard portals. Ankle dorsiflexion can allow full visualization of joint surfaces, however, soft tissue distractors are sometimes used to obtain better visualization. Any pathology detected including OCLs, synovitis, osteophytes, and hypertrophic capsule should be addressed. For OCLs, the authors recommend bone marrow stimulation using a microfracture pic or drilling to produce fibrocartilage repair tissue.