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IHTSDO- 1125 Fast Track - Flap procedures

IHTSDO- 1125 Fast Track - Flap procedures

2022-Apr-01

JIRA Link:  

https://snomed.atlassian.net/browse/IHTSDO-1125

https://snomed.atlassian.net/browse/GC-1018

A subtask of QI << 782901001 |Insertion procedure (procedure)|
https://snomed.atlassian.net/browse/QI-917 Flap procedures



Document Links:

Release used for analysis: January 2022





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Version

Date

Approved by

Comments

Version

Date

Approved by

Comments

0.5

Dec 6, 2021 

James T. Case, Chief Terminologist



0.5

Dec 7, 2021 

Farazaneh Ashrafi, Substances











1. Content Issue Summary 

a. Summary of issue 

  • Inconsistency in flap procedures in SNOMED CT, both terming and modeling.

How does a flap differ from a graft? A flap is transferred with its blood supply intact, and a graft is a transfer of tissue without its own blood supply. Therefore, a graft relies on the recipient site for vascular perfusion whereas a flap has its own blood supply, or, in the case of a free flap then the blood vessels are 'reconnected' often microsurgically. Flap surgery is a subspecialty of plastic and reconstructive surgery.
Flaps can be classified in different ways based on:

  • Donor site location and proximity to recipient site (local, distant)

  • Method of transfer, for example, can be advanced, and/or pivotal (geometric) including rotation, transposition, and interpolation

  • Flaps can be pedicled (transferred while still attached to their original blood supply) or free flaps (transferred unattached to their blood supply)

  • Tissue composition/type of tissue to be transferred (eg, musculocutaneous, fasciocutaneous)

  • The type of blood supply (eg, random, axial)

b. Related content projects and requests 

Freshdesk tickets from Australia:
https://ihtsdo.freshdesk.com/a/tickets/34643
https://ihtsdo.freshdesk.com/a/tickets/27452

https://request.ihtsdotools.org/#/requests/preview/735992

https://snomed.atlassian.net/browse/GC-840

https://snomed.atlassian.net/browse/GC-366

https://snomed.atlassian.net/browse/IHTSDO-175

https://snomed.atlassian.net/browse/SUBST-118

https://snomed.atlassian.net/browse/GC-342

https://snomed.atlassian.net/browse/IHTSDO-1188

https://snomed.atlassian.net/browse/DLM-290

2. Analysis of Issue

Inconsistency across the whole flap procedure hierarchy. Many issues raised over many years by stakeholders both internally and externally including wrong inferences, inconsistent terming, redundant role groups being inherited (see 177429004 |Local rotation flap, myocutaneous (procedure)|), 304039000 |Skin flap operation (procedure)| is not a subtype of top flap procedure concept 74799003 |Flap graft (procedure)|, no model or guidance so different attributes being applied, conflation of flap with graft etc.

For << 256683004 |Flap (substance)| the subtypes are not correctly grouped and other issues see 3. Additional issues identified below.

Now QI has moved to procedures these issues can be addressed with the development of a model for flap procedures, and editorial guidance.

Number of concepts impacted:

Flap graft (procedure) SCTID: 74799003, Defined, Active. Descendants Count, Stated: 116 concepts, Inferred: 211 concepts.

Skin flap operation (procedure) SCTID: 304039000, Defined, Active. Descendants Count, Stated: 114 concepts, Inferred: 114 concepts.

256683004 |Flap (substance)| 353 sub-concepts.

3. Additional issues identified

  • Top concept in the procedure hierarchy 74799003 |Flap graft (procedure)| is ambiguous as flap graft sounds like a technique not a procedure. A graft and a flap are not the same.

  • << 74799003 |Flap graft (procedure)| and << 304039000 |Skin flap operation (procedure)| are not related: Skin flap operation (procedure) is not a subtype of Flap graft (procedure) and it should be.

  • Incorrect synonym on 119829000 |Integumentary system transposition (procedure)| of 'Skin flap and skin graft operations'

  • Both 363701004 |Direct substance (attribute)| and 424361007 |Using substance (attribute) currently used to model flap procedures.

  • For Method the proposed target value is << 360032005 |Flap reconstruction - action (qualifier value)| but will need new subtypes (see Solution below).

  • The proposal will involve substances from << 256683004 |Flap (substance)| but within this hierarchy the correct subtypes for each concept have not been assigned.

  • High level groupers are distorting the sub-hierarchy in 256683004 |Flap (substance)| - Head and neck flap (substance)  - and others.

  • Nonsensical substance groupers exist e.g. 256852000 |General flap (substance)|.

  • Conflation of action and flap substance -736772001 |Rotation flap (substance)| and others.

  • Conflation of graft and flap in substance hierarchy and  - e.g. 417257008 |Skin flap autograft (substance)|.

  • Non-standard terming - e.g. 416744008 |Flap with osseous tissue only (substance)|.

  • Many procedure terming variants exist: 

9353002 |Muscle flap of trunk (procedure)| - sounds more like a harvest procedure rather than a reconstruction?

271530000 |Mucosal flap operation (procedure)|

265665001 |Sensory skin flap (procedure)|

54766001 |Conjunctival flap, total (procedure)|

70889007 |Double pedicle flap graft (procedure)|

dental -234684004 |Repositioned periodontal flap (procedure)|

Both 'with' and 'using' 240983003 |Reconstruction with local flap (procedure)| and 771225007 |Reconstruction using free flap (procedure)|

'to': 367451009 |Muscle flap graft to breast (procedure)|

177429004 |Local rotation flap, myocutaneous (procedure)|

14600001000004107 |Closure of wound of ankle with flap (procedure)|

4. Solution

Overall Proposal

To represent the 3 different elements of flap reconstruction procedures in one role group.

Template 

Created a Template model (in progress) to capture these 3 elements:
Reconstruction using flap (procedure) - v1.0



Screenshot 2021-12-01 at 19.45.27.png



Screenshot 2021-12-13 at 15.30.09.png

Procedure Terming: 

Terming Proposal - For FSN utilising the term "using", i.e. "Reconstruction using flap" and "with" as an additional synonymous description - see example below.
When the type of the flap is known, i.e FSN "Reconstruction of x body structure using y flap".

a. Simplest procedure terming:  FSN Reconstruction using flap (procedure)    PT Reconstruction using flap  SYN Flap reconstruction  SYN Reconstruction with flap

Proposed example FSN: Reconstruction using free flap (procedure)  PT  Reconstruction using free flap SYN Free flap reconstruction  SYN  SYN Reconstruction with free flap


b. Flap reconstruction site known: FSN Reconstruction of x body structure using y flap (procedure)    PT Reconstruction of x body structure using y flap  SYN  x body structure reconstruction using y flap  SYN Reconstruction of x body structure with y flap SYN y flap reconstruction of x body structure

Proposed example:  FSN Reconstruction of breast using free flap (procedure)|  PT Reconstruction of breast using free flap SYN Breast reconstruction using free flap  SYN  Reconstruction of breast with free flap SYN Free flap reconstruction of breast

Currently - 61938004 |Breast reconstruction with free flap (procedure)|



4.1 363701004 |Direct substance (attribute)|

|Direct substance (attribute) is the correct attribute to use as the procedure is directly acting on the flap substance.  |Direct substance (attribute) is used in procedures for grafts and transplants, and has been agreed for the flap procedures.

Remodel 256683004 |Flap (substance)|PRIMITIVE, Active. Descendants Count, Stated: 353 concepts, Inferred: 353 concepts. 

  • Remove 4 very high level groupers:180679002 |Head and neck flap (substance)|, 256754008 |Trunk flap (substance)|, 256815000 |Lower limb flap (substance)|, 256784000 |Upper limb flap (substance)|256852000 |General flap (substance)|

  • Missing isa relationships. Need to group subtype concepts in << 256683004 |Flap (substance) sub-hierarchy: for example, 783408009 |Muscle flap (substance)| currently only has 3 subtypes, 261138003 |Myocutaneous flap (substance)| currently only has 2 subtypes, 262088005 |Random pattern flap (substance)| currently has  0 subtypes

  • Remove those substances combining methodology and substance from << 256683004 |Flap (substance)|(see Method section below)

  • Included correctly in substances: Tissue composition or type of tissue (eg, fasciocutaneous)

  • Included correctly in substances: Blood supply, for example, flaps can be pedicled (still attached to their original blood supply) or free (unattached from their blood supply when transferred to be reattached at the donor site), random pattern blood supply (no named blood vessel) or axial pattern blood supply(named blood vessel) 

Test remodel of 256683004 |Flap (substance)| sub-hierarchy (note - I added subtypes to existing concepts to secure correct inferences)

Screenshot 2021-12-01 at 18.07.52.png
Screenshot 2021-12-01 at 18.08.44.png
Screenshot 2021-12-01 at 18.10.27.png
Screenshot 2021-12-01 at 18.14.33.png



4.2 260686004 |Method (attribute)|

  • For Method attribute: proposed target value is 360032005 |Flap reconstruction - action (qualifier value)|

  • Propose addition of subtypes to 360032005 |Flap reconstruction - action (qualifier value)|

  • Proposal includes: Proximity of flap donor site to recipient site (Local flap/ Distant flap) is the methodology of the procedure not a substances. Example, distant flap relates to remote distance of donor site from recipient site.

  • Propose for procedure concepts that include the source of the flap e.g. 172229007 |Reconstruction of upper eyelid with lower eyelid skin flap (procedure)|,425633001 |Reconstruction of breast using flap of skin of buttock (procedure)| would require a new "action" for the creation of the flap  - Flap creation - action (qualifier value)  - a subtype of  360025001 |Harvesting - action (qualifier value)| to be used in a separate Role Group (and for flap harvesting procedures to remodel as phase 2 add-on to this project).



4.3 405813007 |Procedure site - Direct (attribute)| 

Where the flap reconstruction with the flap substance occurs.

Do not include general value 442083009 |Anatomical or acquired body structure (body structure)| if no body site is stated.

5 Construction


1. Re-model << 256683004 |Flap (substance)| subhierarchy as 4.1 above

2. Create new - action qualifier concepts as 4.2 above 


3. Flap (procedure) term and Model procedure concepts to be consistent with Template. Use automation!

4. Modeling guidance for Editorial Guide



Glossary of Terms 



Term

Definition

Term

Definition

Axial flap, axial pattern flap

The blood supply for an axial pattern flap comes from a named or recognized artery or group of arteries. Most muscle flaps have axial blood supplies. (Ref: Medscape)

Distant flap

Distant flaps use tissue that is from a donor site that is remote from the defect to be covered or recipient site and can be transferred over a large distance as a pedicled flap or free flap (for example, 177379002 |Distant microvascular transferred flap, fasciocutaneous (procedure)|).

Fasciocutaneous flap

A fasciocutaneous flap is composed of skin, subcutaneous tissue, and the underlying fascia.

Flap

A flap is a unit of tissue that maintains its own blood supply while being transferred from a donor site to a recipient site. In contrast, grafts are transferred unattached to a vascular source and rely on the blood supply at the recipient site to perfuse the donor tissue.  Flaps range from simple advancements of skin and subcutaneous tissue to composite flaps that may contain any combination of skin, muscle, bone, fat, or fascia.

Flap classification

Flaps can be classified according to the proximity of the recipient site to their donor site (local flap, distant flap) or according to the  technique used (eg, rotation flap, advancement flap.
Flaps can be categorized by their tissue composition: e.g. muscle, skin, fat, musculocutaneous, fasciocutaneous, osseocutaneous and compound flaps.
Flaps can be classified by their blood supply (axial, random pattern, pedicle, free flap). 

https://emedicine.medscape.com/article/1284474-overview#a2

Free flap

The blood vessels are disconnected during the transfer and reconnected usually microsurgically to a new artery and vein at or near the recipient site. Ref: UptoDate

Interpolation flap

The interpolated flap, like the transposition flap, is transferred by pivotal movement and has a linear configuration but differs from transposition flaps in that its base is not contiguous with the defect. https://www.clinicalkey.com/#!/content/book/3-s2.0-B9780323683906000062?scrollTo=%23hl0000542

Local flap 

A flap can be local, regional or distant depending on the proximity of the recipient site to the donor site. A local skin flap is used to cover a defect that is adjacent to the donor site. 

Muscle flap, 
Musculocutaneous flap

Muscle-only flaps are usually used for coverage of large ablative or trauma-induced defects, or for functional purposes. Muscle flaps are well vascularized, and, if skin coverage is inadequate, a split-thickness skin graft can be placed to complete wound closure. An example of a muscle flap for defect coverage is the medial gastrocnemius flap, which is based on the medial sural artery and vein

A flap composed of muscle and its overlying skin and subcutaneous tissue is a musculocutaneous flap.

https://www.uptodate.com/contents/overview-of-flaps-for-soft-tissue-reconstruction?search=muscle%20flap&source=search_result&selectedTitle=1~78&usage_type=default&display_rank=1

 Osteocutaneous flap

An osteocutaneous flap is a flap containing a bony component. It is used to replace missing bone in the head and neck, or long bones of the extremities. An example of an osteocutaneous flap is a fibular free flap.

https://www.uptodate.com/contents/overview-of-flaps-for-soft-tissue-reconstruction?search=perforator%20flap&source=search_result&selectedTitle=1~23&usage_type=default&display_rank=1

Pedicle flap,

Distant pedicled flap

Pedicle flaps are attached to the donor site with a pedicle that contains the blood supply (also known as peduncle). 

A distant pedicled flap involves transfer of tissue to a remote site while still attached to a pedicle. Examples of distant pedicled flaps include the omental flap transferred to the chest and the transverse rectus abdominis muscle (TRAM) flap. (UptoDate) When the TRAM flap is a pedicle flap, it remains attached to its blood supply, with the tissue surgically tunneled underneath the skin to the breast. Distant pedicle flaps can be detached from their blood supply after a delay to allow it to inset. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/pedicle-flap https://www.sciencedirect.com/topics/medicine-and-dentistry/pedicled-skin-flap

Perforator flap

Perforator flaps are a special type of free tissue flap that contain a transmuscular and/or transfascial vascular "leash" or pedicle that leads to the overlying fascia and/or skin only [5]. The vessels are dissected out of the muscle through which they perforate, and the muscle is left behind, relatively undamaged. Perforator flaps are technically demanding and more time consuming to create than pedicled flaps.

https://www.uptodate.com/contents/overview-of-flaps-for-soft-tissue-reconstruction?search=perforator%20flap&source=search_result&selectedTitle=1~23&usage_type=default&display_rank=1

Plastic surgery

The surgical specialty or procedure concerned with the restoration, construction, reconstruction, or improvement in the shape and appearance of body structures that are missing, defective, damaged, or misshapen.https://medical-dictionary.thefreedictionary.com/reconstructive+surgery

Random flap, Random pattern flap

The blood supply to a random flap is provided by the many small unnamed vessels of the subdermal plexus. Random flaps contain skin and subcutaneous tissue only and are in close proximity to the recipient site. Most commonly, skin flaps are random pattern flaps with no specific named vascular supply: UptoDate

Reconstructive surgery

A procedure that attempts to restore a tissue as closely as possible to its original state.https://medical-dictionary.thefreedictionary.com/reconstructive+surgery

Rotation flap

Transfer of skin and/or other tissue to an adjacent area while pivoting or rotating about a pivot point.

Sliding or advancement flap

Transfer of skin and/or other tissue from an adjacent area without torsion of the base.

Transposition flap

A transposition flap is a (usually rectangular) flap that is rotated (laterally) about a pivot point into an immediately adjacent defect. Because the effective length of the flap becomes shorter the farther the flap is rotated, the flap must be designed longer than the defect to be covered.

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