The Corrective Power of Subtalar Arthrodesis With Mini/Medial Bone Block (SAMBB) in Patients Affected by Progressive Collapsing Foot Deformity (PCFD): Analysis Using Weight-bearing Cone Beam CT.

March 31, 2026 updated by: Istituto Ortopedico Rizzoli

Progressive Collapsing Foot Deformity (PCFD) is a complex, multiplanar condition characterized by hindfoot valgus, peritalar subluxation, midfoot abduction, and collapse of the medial arch, which may progress to rigid deformity with pain and functional impairment. In advanced stages, subtalar arthrodesis is a well-established surgical option to restore hindfoot alignment and stability.

Subtalar Arthrodesis with Mini/Medial Bone Block (SAMBB) is an evolution of the Grice-Green technique, using an autologous bone graft to achieve stable correction of talocalcaneal alignment and improve joint congruency, with favorable clinical and radiographic outcomes.

This study aims to evaluate the three-dimensional corrective effect of SAMBB using weight-bearing CT (WBCT), focusing on hindfoot alignment and talocalcaneal and talonavicular relationships.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

20

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Italy
      • Bologna, Italy, 40136
        • Istituto Ortopedico Rizzoli

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Patients of both sexes, aged between 18 and 80 years
  • Patients affected by grade A2 Progressive Collapsing Foot Deformity (PCFD)
  • Patients who have provided informed consent to participate in the study

Exclusion Criteria:

  • Patients who have previously undergone corrective surgery on the deformity under study.
  • Patients with prior lower limb fractures resulting in altered biomechanics.
  • Patients affected by PCFD of grade A1, B2, C2, E1, or E2 according to the PCFD classification [2].
  • Patients with active acute or chronic infections.
  • Patients with chronic inflammatory joint diseases.
  • Patients with significant lower limb trauma occurring after the surgical intervention.
  • Patients with pre-existing gait abnormalities (e.g., amputations, neuromuscular diseases, poliomyelitis, hip dysplasia).
  • Patients with cognitive deficits.
  • Patients with concomitant neurological disorders.
  • Patients affected by cancer.
  • Pregnant patients.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: enrolled patients
Patients of both sexes, aged between 18 and 80 years, affected by grade A2 Progressive Collapsing Foot Deformity (PCFD).
Diagnostic test: Weight-Bearing CT scan
Weight-Bearing CT scan after surgery

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Foot and Ankle Offset
Time Frame: At baseline; After 6 months post op
A three-dimensional parameter derived from weight-bearing CT (WBCT) acquisitions that allows objective quantification of the global alignment of the foot-ankle unit. It measures the spatial relationship between the functional tripod of the foot (first metatarsal, fifth metatarsal, and calcaneus) and the geometric center of the tibiotalar joint, effectively representing a synthetic index of the morpho-functional balance of the hindfoot-midfoot complex.
At baseline; After 6 months post op

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Talo-navicular congruency angle
Time Frame: At baseline; After 6 months post op
A three-dimensional parameter that assesses talonavicular joint alignment and quantifies the degree of midfoot abduction (PCFD class B). It reflects the extent to which the talar head is "uncovered" relative to the navicular, indicating external rotation and lateral translation of the midfoot typical of PCFD. An increased TNCA corresponds to greater talonavicular incongruity and represents a three-dimensional marker of the transverse component of the deformity.
At baseline; After 6 months post op
Middle facet Incongruency angle
Time Frame: At baseline; After 6 months post op
The degree of incongruity between the talus and calcaneus at the level of the middle facet of the subtalar joint. It is a direct indicator of peritalar subluxation, one of the key features of PCFD (class A/D). Increased values suggest instability of the subtalar complex, loss of joint congruency, and three-dimensional hindfoot malalignment, with impairment of the subtalar joint's rotational function and load distribution.
At baseline; After 6 months post op
Forefoot arch angle
Time Frame: At baseline; After 6 months post op
A three-dimensional parameter that evaluates the stability and morphology of the medial and transverse arches at the level of the midfoot (PCFD class C). It reflects the behavior of the medial cuneiform and the first ray under load, describing the ability of the medial column to maintain adequate structural support.
At baseline; After 6 months post op
Hindfoot moment arm
Time Frame: At baseline; After 6 months post op
A three-dimensional measure of calcaneal alignment relative to the tibial axis, representing a direct index of hindfoot valgus. It quantifies the lateral displacement of the calcaneus under the tibial load, objectively describing the hindfoot deviation that characterizes the coronal component of PCFD (class A).
At baseline; After 6 months post op
Calcaneofibular distance and subtalar impigemen
Time Frame: At baseline; After 6 months post op
It evaluates the three-dimensional distance between the lateral surface of the calcaneus and the medial aspect of the fibula, serving as an indirect indicator of subfibular impingement (SFI). A reduction in this distance suggests mechanical conflict due to the combination of calcaneal valgus, lateral displacement of the hindfoot, and instability of the subtalar ligamentous complex. SFI is typical of advanced, rigid PCFD and is associated with progressive lateral load alteration (PCFD class D).
At baseline; After 6 months post op

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Istituto Ortopedico Rizzoli

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

May 1, 2026

Primary Completion (Estimated)

November 1, 2028

Study Completion (Estimated)

May 1, 2029

Study Registration Dates

First Submitted

March 31, 2026

First Submitted That Met QC Criteria

March 31, 2026

First Posted (Actual)

April 7, 2026

Study Record Updates

Last Update Posted (Actual)

April 7, 2026

Last Update Submitted That Met QC Criteria

March 31, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • SAMBB-WBCT

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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