Sustentaculum Tali Screw Fixation Mode and Postoperative Foot-Ankle Function in Calcaneal Fractures

Impact of Sustentaculum Tali Screw Fixation Mode on Radiographic and Functional Outcomes in Patients With Intra-Articular Calcaneal Fractures: An Ambidirectional Cohort Study

This is an observational, ambidirectional cohort study. Calcaneal fractures are the most common tarsal bone fractures, and most are intra-articular fractures involving the subtalar joint. Surgery with open reduction and internal fixation is the standard treatment for displaced intra-articular calcaneal fractures. During surgery, a sustentaculum tali screw is placed from the lateral wall of the calcaneus toward the medial side to support the reduced posterior articular surface. Depending on the screw tip position, fixation is classified as sustentaculum tali fixation (ST; screw fixed directly into the sustentaculum tali) or sustentaculum tali fragment fixation (STF; screw fixed into the larger medial fragment containing the sustentaculum tali). This study compares radiographic reduction quality, foot and ankle function, and complications between these two fixation groups. Approximately 92 participants with intra-articular calcaneal fractures will be enrolled, retrospectively from January 2015 to August 2026 and prospectively from September 2026. The fixation mode is determined on postoperative X-rays. Outcomes, including the Maryland Foot Score, the AOFAS ankle-hindfoot score, Böhler's angle, Gissane's angle, calcaneal height and width, and complications, will be compared between groups over at least 12 months of follow-up. No randomization is performed and no treatment is altered by this study.

Study Overview

• Status: Not yet recruiting
• Conditions: Calcaneal Fractures
• Intervention / Treatment: Other: Screw Tip Position Relative to the Sustentaculum Tali

Detailed Description

Background: Calcaneal fractures account for approximately 1% to 2% of all fractures and are the most common tarsal bone fractures, usually caused by high-energy injuries such as falls from height and motor vehicle accidents. Most are intra-articular fractures involving the subtalar joint. Open reduction and internal fixation is the mainstay of treatment for displaced intra-articular calcaneal fractures, aiming to restore the congruity of the subtalar articular surface and the normal morphology of the calcaneus.

The sustentaculum tali is a bony prominence on the medial side of the calcaneus that forms the middle facet of the subtalar joint. Because of its dense bone and strong ligamentous attachments, it is a key anchor point for fracture reduction and internal fixation. During surgery via a lateral approach, a sustentaculum tali screw is inserted from the lateral wall toward the medial side to provide stable support for the reduced posterior articular surface.

Depending on the screw tip position on postoperative imaging, fixation is classified as sustentaculum tali fixation (ST; screw penetrates within the range of the sustentaculum tali) or sustentaculum tali fragment fixation (STF; screw is fixed into the larger medial fragment containing the sustentaculum tali, with the penetration point outside the sustentaculum tali range). Because the sustentaculum tali is small and irregularly shaped, accurate screw placement is technically demanding, with reported accuracy of only 60% to 80% even among experienced surgeons. Recent studies suggest that fixation into the sustentaculum fragment may achieve clinical outcomes similar to precise sustentaculum tali fixation; however, the effect of the different fixation modes on postoperative foot and ankle function remains insufficiently investigated.

Design and methods: This is an ambidirectional cohort study. Approximately 92 participants with intra-articular calcaneal fractures treated by open reduction and internal fixation will be enrolled, including retrospective cases from January 2015 to August 2026 and prospective cases from September 2026. Participants will be naturally allocated to the ST or STF group according to the fixation mode determined on postoperative lateral and axial X-rays; no randomization is performed and no treatment plan is altered by the study.

Data are collected during routine clinical follow-up at 1 week, 6 weeks, 12 weeks, 24 weeks, and 1 year after surgery; no additional examinations or interventions are required. Radiographic parameters (Böhler's angle, Gissane's angle, calcaneal height and width) are measured on pre- and postoperative X-rays, and functional outcomes are assessed with the AOFAS ankle-hindfoot score and the Maryland Foot Score at least 12 months postoperatively.

Statistical analysis: Continuous variables will be compared using the t-test or the Wilcoxon rank-sum test according to their distribution, and categorical variables will be compared using the chi-square test. Two-sided P < 0.05 will be considered statistically significant. Multivariable regression may be used to adjust for potential confounders where appropriate. Analyses will be performed with SPSS 26.0 (IBM, Armonk, NY, USA).

• Study Type: Observational
• Enrollment (Estimated): 92

Contacts and Locations

• Study Contact: Name: Clinical Trial Office; Phone Number: 010-82266699; Email: bysy@bjmu.edu.cn

Study Locations

• China
  • Beijing Municipality
    • Beijing, Beijing Municipality, China, 100191
      • Peking University Third Hospital
      • Contact: Clinical Trial Office; Phone Number: 010 82266699; Email: bysy@bjmu.edu.cn

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of adults with intra-articular calcaneal fractures who underwent open reduction and internal fixation at Peking University Third Hospital. Retrospective cases will be identified from January 2015 to August 2026, and prospective cases will be enrolled from September 2026 onward. Participants will be classified into the ST or STF group according to screw tip position on postoperative lateral and axial X-rays. Approximately 92 participants are expected. No treatment is assigned by the study; all participants receive routine clinical care.

Description

Inclusion Criteria:

- Adults aged ≥ 18 years.

Diagnosis of intra-articular calcaneal fracture.

Treated with open reduction and internal fixation (ORIF).

Availability of postoperative lateral and axial X-rays for assessment of screw tip position.

Complete medical records for retrospective data collection, or willingness to participate in prospective follow-up.

Written informed consent for prospective participants; informed consent waived for retrospective participants as approved by the ethics committee.

Exclusion Criteria:

- Pathological fractures.

Open calcaneal fractures.

Previous surgery on the affected calcaneus.

Severe medical conditions that may affect follow-up or functional assessment.

Inability to complete follow-up or functional questionnaires.

Lack of adequate imaging or medical records for group allocation.

Patients who declined to participate (for prospective cases).

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Sustentaculum Tali (ST) Fixation; Participants with intra-articular calcaneal fractures treated with open reduction and internal fixation. The exposure of interest is screw tip position: the sustentaculum tali screw penetrates within the range of the sustentaculum tali on postoperative lateral and axial X-rays. No treatment was assigned by the study; all participants received routine clinical care.	Other: Screw Tip Position Relative to the Sustentaculum Tali; Postoperative screw tip position on lateral and axial X-rays, classified as either ST (within the sustentaculum tali) or STF (in the larger medial fragment, outside the sustentaculum tali range). This is the exposure of interest; the study does not assign this exposure.
Sustentaculum Tali Fragment (STF) Fixation; Participants with intra-articular calcaneal fractures treated with open reduction and internal fixation. The exposure of interest is screw tip position: the screw is fixed into the larger medial fragment containing the sustentaculum tali, with the penetration point outside the sustentaculum tali range on postoperative lateral and axial X-rays. No treatment was assigned by the study; all participants received routine clinical care.	Other: Screw Tip Position Relative to the Sustentaculum Tali; Postoperative screw tip position on lateral and axial X-rays, classified as either ST (within the sustentaculum tali) or STF (in the larger medial fragment, outside the sustentaculum tali range). This is the exposure of interest; the study does not assign this exposure.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maryland Foot Score	A validated 100-point scoring system for assessing foot function after injury. Domains include pain, gait, distance walked, stability, support, limp, and wearing shoes. Higher scores indicate better function. Score categories: Excellent 90-100; Good 75-89; Fair 50-74; Failure <50.	At least 12 months postoperatively
AOFAS Ankle-Hindfoot Score	A validated 100-point scoring system for assessing ankle and hindfoot function. Comprises three domains: pain (40 points), function (50 points), and alignment (10 points). Higher scores indicate better function. Score categories: Excellent 90-100; Good 80-89; Fair 65-79; Poor <65.	At least 12 months postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Böhler's Angle	Change in Böhler's angle measured on lateral X-rays. Böhler's angle is formed by the intersection of a line from the highest point of the anterior process to the highest point of the posterior facet and a line from the highest point of the posterior facet to the superior margin of the calcaneal tuberosity. Normal range is approximately 20°-40°. A decrease indicates loss of calcaneal height and posterior facet collapse.	Preoperative, immediate postoperative, and at least 12 months postoperatively
Change in Gissane's Angle	Change in Gissane's angle measured on lateral X-rays. Gissane's angle is formed at the intersection of the downward and upward slopes of the calcaneal superior surface, located beneath the lateral process of the talus. Normal range is approximately 120°-140°. An increase indicates architectural disruption of the posterior facet.	Preoperative, immediate postoperative, and at least 12 months postoperatively
Change in Calcaneal Height	Change in calcaneal height measured on lateral X-rays from preoperative to postoperative and final follow-up. A decrease in calcaneal height indicates collapse of the fractured calcaneus.	Preoperative, immediate postoperative, and at least 12 months postoperatively
Change in Calcaneal Width	Change in calcaneal width measured on axial X-rays from preoperative to postoperative and final follow-up. An increase in calcaneal width indicates lateral wall bulging after fracture.	Preoperative, immediate postoperative, and at least 12 months postoperatively
Postoperative Complications	Number of participants with postoperative complications, including wound infection, screw loosening, sural nerve injury, and other surgery-related adverse events. Complications will be recorded during routine clinical follow-up.	Up to 12 months postoperatively

Collaborators and Investigators

• Sponsor: Peking University Third Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): September 20, 2026
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: September 12, 2026
• First Submitted That Met QC Criteria: September 12, 2026
• First Posted (Actual): September 16, 2026

Study Record Updates

• Last Update Posted (Actual): September 16, 2026
• Last Update Submitted That Met QC Criteria: September 12, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Keywords: Calcaneal Fracture; Sustentaculum Tali Screw
• Other Study ID Numbers: PekingUTH ZF SUS Screw

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