Arthroscopic Versus Open Subtalar Arthrodesis for the Treatment of Subtalar Arthritis (ISTA-ASTA RCT)

Comparative Analysis of Open Versus Arthroscopic Approaches for Subtalar Arthrodesis in Patients With Subtalar Arthritis

The goal of this clinical trial is to compare two surgical approaches for treating symptomatic subtalar arthritis in patients who have failed conservative treatment. The main questions it aims to answer are:

What is the fusion rate for each surgical technique? Which technique achieves bony union faster with fewer complications?

Researchers will compare arthroscopic subtalar arthrodesis (ASTA) using a combined three-to-four portal approach to open in situ subtalar arthrodesis (ISTA) to see if one technique results in superior fusion rates, faster healing, and better functional outcomes.

Participants will:

Undergo one of two surgical procedures (either ASTA or ISTA) Attend follow-up visits at 6 weeks, 3 months, 6 months, and 12 months after surgery Have X-rays taken to assess fusion and bone healing Complete pain and function questionnaires at each visit

Study Overview

• Status: Active, not recruiting
• Conditions: Subtalar Arthritis
• Intervention / Treatment: Procedure: Open In Situ Subtalar Arthrodesis; Procedure: Arthroscopic Subtalar Arthrodesis

Detailed Description

Background and Rationale:

Subtalar arthritis is a debilitating condition frequently resulting from intra-articular calcaneal fractures, leading to progressive cartilage degeneration, hindfoot pain, and functional impairment. When conservative management fails, subtalar arthrodesis (fusion) is the established gold standard surgical treatment. Open in situ subtalar arthrodesis (ISTA) via the sinus tarsi approach has a long history of success with reported fusion rates of 85-95%. However, arthroscopic subtalar arthrodesis (ASTA) has gained popularity due to proposed advantages including preservation of blood supply, reduced soft tissue trauma, and lower wound complication rates. High-quality prospective comparative data between these two techniques remain limited.

Study Design:

Single-center, prospective, randomized controlled trial at Kasr Al-Ainy Hospitals, Cairo University. Forty patients with symptomatic subtalar arthritis are randomized 1:1 to ASTA (n=20) or ISTA (n=20) using computer-generated sequences with allocation concealment via sequentially numbered sealed opaque envelopes. Due to the nature of surgical interventions, blinding of patients and surgeons is not feasible; however, outcome assessment is performed by a blinded independent assessor.

Surgical Interventions:

Arthroscopic Subtalar Arthrodesis (ASTA): Performed under spinal anesthesia in the prone position. A combined three-to-four portal arthroscopic technique is used, including anterolateral (sinus tarsi), posterolateral, and posteromedial portals for complete visualization of the subtalar joint. Complete synovectomy and cartilage debridement until healthy bleeding subchondral bone is exposed.. Subchondral drilling creates microfractures to enhance vascular ingrowth. Fixation is achieved with two percutaneously inserted 6.5-7.3 mm cannulated screws under fluoroscopic guidance.

Open In Situ Subtalar Arthrodesis (ISTA): Performed under spinal anesthesia with the patient supine via a 4-5 cm oblique sinus tarsi approach. All residual articular cartilage is removed to bleeding cancellous bone. The subchondral plate is perforated to enhance fusion. Fixation is achieved with two percutaneously inserted cannulated screws under fluoroscopic guidance.

Postoperative Protocol:

Standardized rehabilitation: non-weight-bearing in a short-leg removable cast boot for 6 weeks, followed by progressive weight-bearing once radiographic union is confirmed. Formal physiotherapy begins after transition to full weight-bearing.

Outcome Evaluation:

Patients are assessed at 2 weeks, 6 weeks, 3 months, 6 months, and 12 months postoperatively. Primary outcomes are radiographic fusion rate and time to radiographic union (defined as trabecular bridging across the posterior facet on plain radiographs or CT). Secondary outcomes include pain (VAS), functional status (Modified AOFAS), quality of life (SF-12), operative time, blood loss, and complication rates. Subgroup analyses by age, sex, BMI, smoking status, and arthritis etiology are performed.

Statistical Analysis:

Sample size (40 patients) calculated for expected fusion rates of 100% (ASTA) vs 95% (ISTA) with non-inferiority margin of 0.15, 80% power, and two-tailed alpha 0.05. Analysis includes t-tests, chi-square tests, Kaplan-Meier survival analysis, and multivariable regression. Significance set at p < 0.05.

Ethics:

Study approved by Research Ethics Committee, Faculty of Medicine, Cairo University (13 February 2024). All patients provide written informed consent. Conducted in accordance with the Declaration of Helsinki (2013), ICMJE, and CONSORT guidelines.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Egypt
  • Cairo Governorate
    • Cairo, Cairo Governorate, Egypt, 4240310
      • Cairo University Hospitals

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Clinically and radiographically confirmed symptomatic subtalar arthritis (post-traumatic, primary osteoarthritis, inflammatory or cured post-infective arthritis, symptomatic talocalcaneal coalition, or isolated subtalar arthrosis secondary to pes planovalgus deformity)
• Failure of an adequate trial of non-operative treatment for a minimum of six months
• Skeletal maturity: patients aged 18 years or older
• Ability and willingness to provide written informed consent and to comply fully with the scheduled postoperative follow-up protocol

Exclusion Criteria:

• Primary subtalar arthrodesis performed for an acute, displaced intra-articular calcaneal fracture
• Arthrodesis planned in conjunction with other simultaneous ipsilateral hindfoot procedures
• Patients with open physes (skeletal immaturity)
• Indication for a distraction-type arthrodesis requiring structural bone graft
• History of previous or current active infection at the planned operative site
• Previous failed attempt at subtalar arthrodesis
• Presence of significant peripheral vascular disease or other major medical comorbidities precluding safe surgical intervention

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Open In Situ Subtalar Arthrodesis (ISTA); Open in situ subtalar arthrodesis via the lateral sinus tarsi approach performed in the supine position. All residual articular cartilage is removed to bleeding cancellous bone. The subchondral plate is perforated to enhance fusion. Fixation is achieved with two percutaneously inserted cannulated screws under fluoroscopic guidance.	Procedure: Open In Situ Subtalar Arthrodesis; Lateral sinus tarsi approach performed supine with 4-5 cm oblique incision. Complete cartilage debridement to bleeding cancellous bone, subchondral plate perforation, and percutaneous screw fixation (two cannulated screws) under fluoroscopic guidance.; Other Names: ISTA
Active Comparator: Arthroscopic Subtalar Arthrodesis (ASTA); Arthroscopic technique using a 4 mm 30° arthroscope in the prone position with a combined three-to-four portal approach (anterolateral sinus tarsi portal, posterolateral portal, posteromedial portal). Includes complete synovectomy, motorized debridement of posterior facet cartilage, subchondral microfracture drilling, and percutaneous screw fixation (two 6.5-7.3 mm cannulated screws) under fluoroscopic guidance.	Procedure: Arthroscopic Subtalar Arthrodesis; Arthroscopic technique using a 4 mm 30° arthroscope in the prone position with a combined three-to-four portal approach (anterolateral sinus tarsi portal, posterolateral portal, posteromedial portal). Includes complete synovectomy, motorized debridement of posterior facet cartilage, subchondral microfracture drilling, and percutaneous screw fixation (two 6.5-7.3 mm cannulated screws) under fluoroscopic guidance.; Other Names: ASTA

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fusion Rate at 6 months	Fusion rate is defined as the proportion of patients achieving successful solid bony union of the subtalar joint. Union is determined using combined clinical and radiographic criteria, including absence of pain on palpation and passive stress, absence of detectable subtalar motion, and presence of continuous trabecular bridging across the posterior facet on plain radiographs or computed tomography when radiographs are inconclusive.	6 months postoperatively
Time to Radiographic Union	Time to radiographic union is defined as the time elapsed from the date of surgery to the first radiographic evidence of continuous trabecular bridging across the subtalar joint fusion interface. Assessment is performed using serial plain radiographs, with computed tomography utilized when findings are equivocal.	Up to 12 months postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Complication Rate	Incidence and nature of all perioperative and postoperative complications, classified by severity including wound complications, nerve injury, hardware-related issues, non-union, malunion, and infection.	Intraoperative through 12 months postoperatively
Change in American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score	Functional outcome is assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score (modified version, maximum 94 points excluding the subtalar motion component). The scale ranges from 0 to 94, with higher scores indicating better function. The score evaluates pain, function, and alignment. Change from baseline is compared between arthroscopic and open subtalar arthrodesis groups.	Preoperative baseline, 6 months postoperatively, and 12 months postoperatively
Change in Pain Intensity Measured by Visual Analog Scale (VAS)	Pain intensity is assessed using the Visual Analog Scale (VAS), a 0 to 10 scale where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain severity. Change from baseline is evaluated at each follow-up time point and compared between treatment groups.	Preoperative baseline, 6 weeks, 3 months, 6 months, 12 months postoperatively
Change in Short Form-12 (SF-12) Health Survey Scores	Health-related quality of life is assessed using the Short Form-12 (SF-12) Health Survey, including the Physical Component Summary (PCS) and Mental Component Summary (MCS). Each component is scored on a scale from 0 to 100, with higher scores indicating better health status. Change from baseline is compared between treatment groups.	Preoperative baseline, 6 months postoperatively, 12 months postoperatively

Collaborators and Investigators

• Sponsor: Cairo University
• Collaborators: Kasr El Aini Hospital
• Investigators: Principal Investigator: Helal Hosny Abdulaziz, M.B., B.Ch., M.Sc., Cairo University; Study Chair: Ahmed Samir Bashandy, Cairo University; Study Chair: Ahmed Mohamed Khedr, Cairo University

Publications and helpful links

General Publications

• Morra R, D'Ambrosio A, Pietroluongo E, De Placido P, Montella L, Del Deo V, Tortora M, Matano E, Damiano V, Palmieri G, De Placido S, Giuliano M. The unusual first sign of presentation of renal cell carcinoma: a rare case report. AME Case Rep. 2022 Oct 30;6:35. doi: 10.21037/acr-22-16. eCollection 2022.
• Tateshima S, Tanishita K, Omura H, Villablanca JP, Vinuela F. Intra-aneurysmal hemodynamics during the growth of an unruptured aneurysm: in vitro study using longitudinal CT angiogram database. AJNR Am J Neuroradiol. 2007 Apr;28(4):622-7.
• Davies J, Chipman JK. Relative importance of oxidation and Ca(2+) in DNA strand breakage by H(2)O(2) in the 2sFou cell line. Toxicol In Vitro. 1994 Feb;8(1):29-36. doi: 10.1016/0887-2333(94)90205-4.
• Anderson TL. Drug identity change processes, race, and gender. II. Microlevel motivational concepts. Subst Use Misuse. 1998 Oct;33(12):2469-83. doi: 10.3109/10826089809059335.

Study record dates

Study Major Dates

• Study Start (Actual): December 5, 2023
• Primary Completion (Estimated): April 1, 2026
• Study Completion (Estimated): June 1, 2026

Study Registration Dates

• First Submitted: March 14, 2026
• First Submitted That Met QC Criteria: March 18, 2026
• First Posted (Actual): March 20, 2026

Study Record Updates

• Last Update Posted (Actual): April 13, 2026
• Last Update Submitted That Met QC Criteria: April 7, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: MD-482-2023

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No