Abstract
Resection of symptomatic talocalcaneal coalitions (TCCs) has been performed for patients with normal tarsal joints and <50% involvement of the subtalar joint. For those with TCCs >50% of subtalar articulation or/and subtalar arthritis, a subtalar arthrodesis is done. The purpose of this Technical Note is to describe the arthroscopic resection of TCC and talocalcaneal arthrodesis during the same procedure by using a 2 lateral portal technique. With the patient in lateral decubitus under general or locoregional anaesthesia, the foot and ankle are extended beyond the edge of the surgical table. A lateral portal is created 1 cm anterior to the tip of the lateral malleolus in which the arthroscope is introduced. The anterolateral portal is created 1 cm inferior and 2 cm anterior to the tip of the lateral malleolus. The posterior subtalar surface is prepared progressively. The TCC resection is completed. The fixation is obtained with 2 cannulated screws. The arthroscopic resection of TCC and subtalar arthrodesis during the same procedure by using 2 lateral portals can be done for correctly selected patients.
Technique Video
This video shows a lateral arthroscopic subtalar arthrodesis for talocalcaneal coalition. This surgery is indicated for the talocalcaneal coalition that involves more than 50% of the subtalar articulation or for talocalcaneal coalitions (TCCs) with subtalar arthritis. With the patient in the lateral decubitus, the foot and ankle are extended beyond the edge of the surgical table. A lateral portal is created 1 cm anterior to the tip of the lateral malleolus in which the arthroscope is introduced. Then, the anterolateral portal is created 1 cm inferior and 2 cm anterior to the tip of the lateral malleolus under arthroscopic guidance. The working area is created progressively with the shaver in contact with bone, from distal to proximal. The lack of movements in the subtalar articulation is observed. The posterior subtalar surface is prepared progressively, preserving its shape and ensuring that compression will not cause malalignment in the coronal and sagittal plane during the arthrodesis fixation. The TCC is identified and progressively resected. The tibialis anterior tendon is used as an anatomical landmark for medial neurovascular structures. The resection is complete when the movements in subtalar articulation are confirmed arthroscopically. Under fluoroscopic guidance, 2 guide pins are inserted perpendicular to the posterior subtalar surface from the calcaneal tuberosity to the talus. Then, 1 cannulated screws of 6.5 mm are inserted to apply compression at the fusion site. The final position of screws is radiologically assessed. Wounds are closed.
The documented incidence of tarsal coalition is approximately 1% or less of the population.1,2 The joints most commonly affected are the talocalcaneal coalition (TCC) and calcaneonavicular coalition, which account for approximately 90% of cases.3 The talocalcaneal coalition rate is between 12.7 and 48.1%.3,4 Asymptomatic TCCs do not need treatment, whereas the management of painful coalitions remains disputable.5
Conservative treatment is the first-line recommendation for symptomatic talocalcaneal coalitions, but if it fails, surgical treatment may be indicated.2,5
Many techniques have been described for the treatment of TCCs. Resection of symptomatic TCCs has been performed for patients with normal tarsal joints and <50% involvement of the subtalar joint. For patients who have degenerative lesions of the tarsal joints, a triple arthrodesis is indicated. Those with TCCs >50% of subtalar articulation and/or subtalar arthritis a subtalar arthrodesis is done.5, 6, 7 The purpose of this Technical Note is to describe the arthroscopic resection of TCC and talocalcaneal arthrodesis during the same procedure by using 2 lateral portals technique.
Surgical Technique (With Video Illustration)
A demonstration of the lateral arthroscopic talocalcaneal coalition resection and subtalar arthrodesis is available in Video 1.
Surgical Equipment
A standard 4-mm arthroscope is required. Shavers (3.5 or 5 mm in diameter) and spherical or oval burrs (5 mm in diameter) are used. A tourniquet and an arthroscopy pump may or not be added.8,9 Coalition and cartilage resection and subchondral bone preparation are achieved with burrs, curettes, chisels, and awls. The arthrodesis is fixed with cannulated screws under fluoroscopy to assess the contact and position of the bone surfaces.
Installation
Preoperative antibioprophylaxis is done. With the patient in lateral decubitus under general or locoregional anaesthesia, the foot and ankle are extended beyond the edge of the surgical table. Therefore, the foot can be forced in varus to open up the sinus tarsi and the lateral part of the subtalar joint, making the access easier for arthroscopic procedures (Fig 1).10
Table 2.
Pearls and Pitfalls of Lateral Arthroscopic Subtalar Arthrodesis for Talocalcaneal Coalition (TCC)
| Pearls |
| Forcing the foot in varus with the patient in lateral decubitus opens the sinus tarsi, the lateral part of the subtalar joint, and can reduce the pes planus that is often associated with TCCs |
| Posterior tibialis tendon is an anatomical landmark for medial resection of the TCC |
| Flexor hallucis longus is a medial anatomical landmark for articular preparation |
| TCC is resected when movements in subtalar articulation ca be confirmed |
| Using a square-tipped awl to make holes in the cancellous bone promote bone fusion |
| Pitfalls |
| If the articular shape is not preserved, the compression can cause malalignment during fusion fixation (medial over-resection leads to varus malalignment; lateral over-resection leads to valgus malalignment) |
| Resecting medially to flexor hallucis longus tendons can damage the medial neurovascular bundle |
Table 1.
Advantages, Disadvantages, and Limitations of Lateral Arthroscopic Subtalar Arthrodesis for Talocalcaneal Coalition (TCC)
| Advantages |
| Good exposure of subtalar joint |
| Hindfoot malalignment because of TCC can be corrected |
| The technique can be done with usual arthroscopic instruments |
| Low rates of complications |
| Reduced risk of skin complication (necrosis, infection, delayed healing) compared with open procedures |
| Shorter time to fusion compared with open procedures |
| One-day surgery |
| Full weight-bearing immediately after the procedure and quicker recovery compared with open procedures |
| Minimal invasive surgery |
| Disadvantages |
| Long surgery |
| Lesser saphenous vein is at risk with anterolateral portal placement |
| Clinical studies are needed to validate this technique |
| Limitations |
| Limited number of patients suitable for this procedure |
Fig 1.
Patient positioning for the lateral arthroscopic subtalar arthrodesis for talocalcaneal coalition. The patient is in the lateral decubitus with the left foot and ankle beyond the edge of the surgical table.
Portals
A lateral portal is created 1 cm anterior to the tip of the lateral malleolus11,12 in which the arthroscope is introduced. The anterolateral portal is created 1 cm inferior and 2 cm anterior to the tip of the lateral malleolus under arthroscopic guidance (Fig 2).13 The working area is created progressively with the shaver in contact with bone, from distal to proximal. The lack of movements in the subtalar articulation is observed.
Fig 2.
Arthroscopic portals of the left foot for lateral arthroscopic subtalar arthrodesis for talocalcaneal coalition and anatomical landmarks. Patient is in lateral decubitus. Lateral malleolus (1) and calcaneocuboid articulation (2). The anterolateral (yellow arrow) portal is positioned 1 cm inferior and 2 cm anterior to the tip of the lateral malleolus and lateral (red arrow) portal that is done 1 cm anterior to the tip of the fibula.
Bone Surface Preparation and Coalition Resection
The posterior subtalar surface is prepared progressively preserving its shape and ensuring that compression will not cause malalignment in the coronal and sagittal plane during the arthrodesis fixation. The preparation is done until the tibialis posterior tendon (Fig 3) and TCC is identified. As middle facet coalitions are oblique rather than horizontal, the TCC resection is done from dorsal to caudal, lateral to medial, and distal to proximal so as not to miss any extension into the posterior facet on the medial side.14 The TCC is resected with an arthroscopic burr until the movements of the subtalar articulation can be clinically and arthroscopically confirmed. After the cartilage is completely removed and coalition is completely resected, a square-tipped awl is used to make holes down to the cancellous bone on the articular surfaces to promote bone fusion (Fig 4).
Fig 3.
Talocalcaneal coalition resection until the tibialis posterior tendon (red arrow) is identified during lateral arthroscopic arthrodesis for left talocalcaneal coalition. The patient is in lateral decubitus.
Fig 4.
Left subtalar joint after bone surface preparation during lateral arthroscopic arthrodesis for talocalcaneal coalition. The patient is in lateral decubitus.
Fixation
The fixation is obtained with 2 cannulated screws inserted from the posterior aspect of the heel to the talus.8,15, 16, 17 Two pins are inserted perpendicular to the posterior subtalar surface from the calcaneal tuberosity to the talus maintaining the hindfoot in its final position. The pins and arthrodesis final position are radiologically assessed. Then, 2 cannulated of 6.5-mm diameter screws (FAST of SERF Extremity Society, Decines France) are inserted to apply compression at the arthrodesis site (Fig 5).
Fig 5.
(A) Intraoperative lateral radiograph of the left ankle after fixation of the arthroscopic arthrodesis for talocalcaneal coalition. (B) Intraoperative anteroposterior radiograph of the left ankle after fixation of the arthroscopic arthrodesis for talocalcaneal coalition.
Postoperative Management
This technique can be performed as a 1-day surgery procedure. A walking boot is required to be used immediately after the procedure for 4 to 6 weeks with full weight-bearing as tolerated. Analgesics and nonsteroidal anti-inflammatory drugs are prescribed for the early postoperative period. Thromboprophylaxis for 4 weeks is prescribed. Clinical and radiologic evaluation can be performed at 6 weeks and 3, 6, and 12 months’ postoperatively.
Discussion
Many case series describing the treatment of TCCs and its results are available in the literature but, to our knowledge, at the time of writing this paper, this is the first Technical Note reporting a resection of TCC followed by arthrodesis by lateral subtalar arthroscopy.
However, the optimal surgical treatment for symptomatic TCCs after failed conservative management has yet to be determined.5 Postoperative pain after resection of symptomatic tarsal coalitions remains an issue and is usually associated with pre-existing secondary arthritic changes and synovitis.18,19 Preoperative assessment of the size and extent of particularly posterior facet articular surface involvement can help to select which patients would be expected to benefit from tarsal coalition resection only or in combination with arthrodesis as treatment.14,20,21 In cases in which resection is not possible or desired, the fusion of the subtalar joint only can be performed, instead of the traditional triple arthrodesis, reasoning that any motion saved in the midtarsal joints would maintain force transfer during motion, decreasing or slowing degenerative changes in adjacent joints.22
Lateral subtalar arthroscopy is a technique with good results and low iatrogenic complication rates that allows good visualization of the entire subtalar articulation.5,8,23, 24, 25 The safety of the portals was proved in the literature.8,11, 12, 13,24 No structures are at risk with the lateral portal placement.11, 12, 13,24 The structures at risk for the anterolateral portal are dorsal intermediate cutaneous branch of the superficial peroneal nerve, the dorsal lateral cutaneous branch of the sural nerve, the peroneus tertius tendon, and a small branch of the lesser saphenous vein. Frey et al.11 demonstrated that only the branch of the lesser saphenous vein is at risk to be lacerated, but the rest of the structures are at a safe distance of the placement of anterolateral portal.
Arthroscopic tarsal coalition resection is a feasible and effective surgery,26 and the TCCs can be resected using lateral portals arthroscopic technique.14 The medial open approach to the TCC does not provide adequate exposure of the posterior and posterolateral extent of the coalition without excessive retraction on the tibial nerve and vessels.14 Moreover, conventional open surgery for symptomatic TCCs can lead to complications that are independent of the used technique, including incisional neuroma formation (10%), superficial wound infection (4%), and delayed wound healing (4%).5,21,27,28
The posterior subtalar surface can be prepared under lateral arthroscopic guidance and subtalar arthrodesis can be done.8,24,29 Studies of arthroscopic subtalar arthrodesis showed good results with low rates of complications,30 a bone rate fusion greater than 90% with a shorter time to fusion (average of 8 weeks), and a quicker recovery.16,17,30, 31, 32, 33
In conclusion, the arthroscopic resection of TCC and subtalar arthrodesis during the same procedure by using 2 lateral portals can be done for correctly selected patients.
Footnotes
The authors report the following potential conflicts of interest or sources of funding: R.L. reports grants from Arthrex, Implant Service Orthopedie, and SERF, outside the submitted work. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
Supplementary Data
This video shows a lateral arthroscopic subtalar arthrodesis for talocalcaneal coalition. This surgery is indicated for the talocalcaneal coalition that involves more than 50% of the subtalar articulation or for talocalcaneal coalitions (TCCs) with subtalar arthritis. With the patient in the lateral decubitus, the foot and ankle are extended beyond the edge of the surgical table. A lateral portal is created 1 cm anterior to the tip of the lateral malleolus in which the arthroscope is introduced. Then, the anterolateral portal is created 1 cm inferior and 2 cm anterior to the tip of the lateral malleolus under arthroscopic guidance. The working area is created progressively with the shaver in contact with bone, from distal to proximal. The lack of movements in the subtalar articulation is observed. The posterior subtalar surface is prepared progressively, preserving its shape and ensuring that compression will not cause malalignment in the coronal and sagittal plane during the arthrodesis fixation. The TCC is identified and progressively resected. The tibialis anterior tendon is used as an anatomical landmark for medial neurovascular structures. The resection is complete when the movements in subtalar articulation are confirmed arthroscopically. Under fluoroscopic guidance, 2 guide pins are inserted perpendicular to the posterior subtalar surface from the calcaneal tuberosity to the talus. Then, 1 cannulated screws of 6.5 mm are inserted to apply compression at the fusion site. The final position of screws is radiologically assessed. Wounds are closed.
References
- 1.Klammer G., Espinosa N., Iselin L.D. Coalitions of the tarsal bones. Foot Ankle Clin. 2018;23:435–449. doi: 10.1016/j.fcl.2018.04.011. [DOI] [PubMed] [Google Scholar]
- 2.Lemley F., Berlet G., Hill K., Philbin T., Isaac B., Lee T. Current concepts review: Tarsal coalition. Foot Ankle Int. 2006;27:1163–1169. doi: 10.1177/107110070602701229. [DOI] [PubMed] [Google Scholar]
- 3.Zaw H., Calder J.D.F. Tarsal coalitions. Foot Ankle Clin. 2010;15:349–364. doi: 10.1016/j.fcl.2010.02.003. [DOI] [PubMed] [Google Scholar]
- 4.Stormont D., Peterson H. The relative incidence of tarsal coalition. Clin Orthop Rel Res. 1983;181:28–36. [PubMed] [Google Scholar]
- 5.Bonasia D.E., Phisitkul P., Saltzman C.L., Barg A., Amendola A. Arthroscopic resection of talocalcaneal coalitions. Arthroscopy. 2011;27:430–435. doi: 10.1016/j.arthro.2010.10.018. [DOI] [PubMed] [Google Scholar]
- 6.Thorpe S.W., Wukich D.K. Tarsal coalitions in the adult population. Foot Ankle Clin. 2012;17:195–204. doi: 10.1016/j.fcl.2012.03.004. [DOI] [PubMed] [Google Scholar]
- 7.Zhou B., Tang K., Hardy M. Talocalcaneal coalition combined with flatfoot in children: Diagnosis and treatment: A review. J Orthop Surg Res. 2014;9:129. doi: 10.1186/s13018-014-0129-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Lopes R., Andrieu M., Bauer T. Arthroscopic subtalar arthrodesis. Orthop Traumatol Surg Res. 2016;102:S311–S316. doi: 10.1016/j.otsr.2016.08.002. [DOI] [PubMed] [Google Scholar]
- 9.Zaidi R., Hasan K., Sharma A., Cullen N., Singh D., Goldberg A. Ankle arthroscopy: A study of tourniquet versus no tourniquet. Foot Ankle Int. 2014;35:478–482. doi: 10.1177/1071100713518504. [DOI] [PubMed] [Google Scholar]
- 10.Maceira E., Monteagudo M. Subtalar anatomy and mechanics. Foot Ankle Clin. 2015;20:195–221. doi: 10.1016/j.fcl.2015.02.001. [DOI] [PubMed] [Google Scholar]
- 11.Frey C., Gasser S., Feder K. Arthroscopy of the subtalar joint. Foot Ankle Int. 1994;15:424–428. doi: 10.1177/107110079401500804. [DOI] [PubMed] [Google Scholar]
- 12.Mekhail A.O., Heck B.E., Ebraheim N.A., Jackson W.T. Arthroscopy of the subtalar joint: Establishing a medial portal. Foot Ankle Int. 1995;16:427–432. doi: 10.1177/107110079501600709. [DOI] [PubMed] [Google Scholar]
- 13.Serge Parisien J., Vangsness T. Arthroscopy of the subtalar joint: An experimental approach. Arthroscopy. 1985;1:53–57. doi: 10.1016/s0749-8063(85)80079-7. [DOI] [PubMed] [Google Scholar]
- 14.Jagodzinski N.A., Hughes A., Davis N.P., Butler M., Winson I.G., Parsons S.W. Arthroscopic resection of talocalcaneal coalitions—A bicentre case series of a new technique. Foot Ankle Surg. 2013;19:125–130. doi: 10.1016/j.fas.2013.03.001. [DOI] [PubMed] [Google Scholar]
- 15.Scanlan R.L., Burns P.R., Crim B.E. Technique tip: Subtalar joint fusion using a parallel guide and double screw fixation. J Foot Ankle Surg. 2010;49:305–309. doi: 10.1053/j.jfas.2010.02.017. [DOI] [PubMed] [Google Scholar]
- 16.Scranton P.E. Comparison of open isolated subtalar arthrodesis with autogenous bone graft versus outpatient arthroscopic subtalar arthrodesis using injectable bone morphogenic protein-enhanced graft. Foot Ankle Int. 1999;20:162–165. doi: 10.1177/107110079902000304. [DOI] [PubMed] [Google Scholar]
- 17.Amendola A., Lee K.B., Saltzman C.L., Suh J.S. Technique and early experience with posterior arthroscopic subtalar arthrodesis. Foot Ankle Int. 2007;28:298–302. doi: 10.3113/FAI.2007.0298. [DOI] [PubMed] [Google Scholar]
- 18.Kumar S.J., Guille J.T., Lee M.S., Couto J.C. Osseous and non-osseous coalition of the middle facet of the talocalcaneal joint. J Bone Joint Surg Am. 1992;74:529–535. [PubMed] [Google Scholar]
- 19.Downey M. Tarsal coalitions. A surgical classification. J Am Podiatr Med Assoc. 1991;81:187–197. doi: 10.7547/87507315-81-4-187. [DOI] [PubMed] [Google Scholar]
- 20.Wilde P.H., Torode I.P., Dickens D.R., Cole W.G. Resection for symptomatic talocalcaneal coalition. J Bone Joint Surg Br. 1994;76:797–801. [PubMed] [Google Scholar]
- 21.Aldahshan W., Hamed A., Elsherief F., Abdelaziz A.M. Endoscopic resection of different types of talocalcaneal coalition. Foot Ankle Int. 2018;39:1082–1088. doi: 10.1177/1071100718770625. [DOI] [PubMed] [Google Scholar]
- 22.Mann R.A., Baumgarten M. Subtalar fusion for isolated subtalar disorders: Preliminary report. Clin Orthop Rel Res. 1988;(226):260–265. [PubMed] [Google Scholar]
- 23.Tryfonidis M., Whitfield C.G., Charalambous C.P., Baraza W.K., Blundell C., Sharp R.J. The distance between the sural nerve and ideal portal placements in lateral subtalar arthroscopy: A cadaveric study. Foot Ankle Int. 2008;29:842–844. doi: 10.3113/FAI.2008.0842. [DOI] [PubMed] [Google Scholar]
- 24.Lintz F., Guillard C., Colin F., Marchand J.B., Brilhault J. Safety and efficiency of a 2-portal lateral approach to arthroscopic subtalar arthrodesis: A cadaveric study. Arthroscopy. 2013;29:1217–1223. doi: 10.1016/j.arthro.2013.04.016. [DOI] [PubMed] [Google Scholar]
- 25.Muñoz G., Eckholt S. Subtalar arthroscopy. Foot Ankle Clin. 2015;20:93–108. doi: 10.1016/j.fcl.2014.10.010. [DOI] [PubMed] [Google Scholar]
- 26.Addar A., Marwan Y., Algarni N., Algarni N., Berry G.K., Benaroch T. Tarsal coalition: Systematic review of arthroscopic management. Foot. 2021;49:101864. doi: 10.1016/j.foot.2021.101864. [DOI] [PubMed] [Google Scholar]
- 27.O’Neill D.B., Micheli L.J. Tarsal coalition: A followup of adolescent athletes. Am J Sports Med. 1989;17:544–549. doi: 10.1177/036354658901700416. [DOI] [PubMed] [Google Scholar]
- 28.Luhmann S.J., Schoenecker P.L. Symptomatic talocalcaneal coalition resection: Indications and results. J Pediatr Orthop. 1998;18:748–754. [PubMed] [Google Scholar]
- 29.Bernasconi A., Guillard C., Lintz F. Anterolateral arthroscopic posterior subtalar arthrodesis: The surgical technique. Arthrosc Tech. 2017;6:e1183–e1188. doi: 10.1016/j.eats.2017.04.005. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Dutra J.M.G., Barcelos V.A., Prata S.D.S., Rizzo M.A.G., Ramos Filho R.L., de Oliveira D.B. Arthroscopic subtalar arthrodesis—results and complications: A systematic review. J Foot Ankle. 2020;14:205–210. [Google Scholar]
- 31.Beimers L., de Leeuw P.A.J., van Dijk C.N. A 3-portal approach for arthroscopic subtalar arthrodesis. Knee Surg Sports Traumatol Arthrosc. 2009;17:830–834. doi: 10.1007/s00167-009-0795-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Carro L.P., Golanó P., Vega J. Arthroscopic subtalar arthrodesis: The posterior approach in the prone position. Arthroscopy. 2007;23:445.e1–445.e4. doi: 10.1016/j.arthro.2006.07.049. [DOI] [PubMed] [Google Scholar]
- 33.Lee K.B., Park C.H., Seon J.K., Kim M.S. Arthroscopic subtalar arthrodesis using a posterior 2-portal approach in the prone position. Arthroscopy. 2010;26:230–238. doi: 10.1016/j.arthro.2009.07.008. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
This video shows a lateral arthroscopic subtalar arthrodesis for talocalcaneal coalition. This surgery is indicated for the talocalcaneal coalition that involves more than 50% of the subtalar articulation or for talocalcaneal coalitions (TCCs) with subtalar arthritis. With the patient in the lateral decubitus, the foot and ankle are extended beyond the edge of the surgical table. A lateral portal is created 1 cm anterior to the tip of the lateral malleolus in which the arthroscope is introduced. Then, the anterolateral portal is created 1 cm inferior and 2 cm anterior to the tip of the lateral malleolus under arthroscopic guidance. The working area is created progressively with the shaver in contact with bone, from distal to proximal. The lack of movements in the subtalar articulation is observed. The posterior subtalar surface is prepared progressively, preserving its shape and ensuring that compression will not cause malalignment in the coronal and sagittal plane during the arthrodesis fixation. The TCC is identified and progressively resected. The tibialis anterior tendon is used as an anatomical landmark for medial neurovascular structures. The resection is complete when the movements in subtalar articulation are confirmed arthroscopically. Under fluoroscopic guidance, 2 guide pins are inserted perpendicular to the posterior subtalar surface from the calcaneal tuberosity to the talus. Then, 1 cannulated screws of 6.5 mm are inserted to apply compression at the fusion site. The final position of screws is radiologically assessed. Wounds are closed.
This video shows a lateral arthroscopic subtalar arthrodesis for talocalcaneal coalition. This surgery is indicated for the talocalcaneal coalition that involves more than 50% of the subtalar articulation or for talocalcaneal coalitions (TCCs) with subtalar arthritis. With the patient in the lateral decubitus, the foot and ankle are extended beyond the edge of the surgical table. A lateral portal is created 1 cm anterior to the tip of the lateral malleolus in which the arthroscope is introduced. Then, the anterolateral portal is created 1 cm inferior and 2 cm anterior to the tip of the lateral malleolus under arthroscopic guidance. The working area is created progressively with the shaver in contact with bone, from distal to proximal. The lack of movements in the subtalar articulation is observed. The posterior subtalar surface is prepared progressively, preserving its shape and ensuring that compression will not cause malalignment in the coronal and sagittal plane during the arthrodesis fixation. The TCC is identified and progressively resected. The tibialis anterior tendon is used as an anatomical landmark for medial neurovascular structures. The resection is complete when the movements in subtalar articulation are confirmed arthroscopically. Under fluoroscopic guidance, 2 guide pins are inserted perpendicular to the posterior subtalar surface from the calcaneal tuberosity to the talus. Then, 1 cannulated screws of 6.5 mm are inserted to apply compression at the fusion site. The final position of screws is radiologically assessed. Wounds are closed.