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Amendment History

Review Timetable

© International Health Terminology Standards Development Organisation 2012. All rights reserved.
SNOMED CT® was originally created by the College of American Pathologists.
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Table of Contents

1 Glossary
1.1 Domain Terms
2 Introduction
2.1 Purpose
2.2 Audience and stakeholder domain:
2.2.1 Input from stakeholders:
2.2.2 Degree of consensus on the statement of problem:
3 Statement of the problem or need
3.1 Summary of problem or need, as reported:
3.2 Summary of requested solution:
3.3 Statement of problem as understood
3.4 Detailed analysis of reported problem, including background
3.4.1 Background
3.4.2 Detailed findings
3.5 Subsidiary and interrelated problems
3.5.1 Grading of Ligament Sprains
3.5.2 Traumatic verses non-traumatic ligament damage
3.5.3 Related content tracker projects:
4 Risks / Benefits
4.1 Risks of not addressing the problem
4.2 Controversy level
4.3 Risks of addressing the problem
5 Requirements: criteria for success and completion
5.1 Criteria for success/completion
5.2 Strategic and/or specific operational use cases
6 Solution Development
6.1 Initial Design
6.1.1 Outline of initial design
6.1.2 Significant design or implementation decisions / compromises
6.1.3 Evaluation of Design
6.2 Iteration One
7 Recommendation
7.1.1 Detailed design final specification
8 Quality program criteria
8.1 Quality metrics
8.1.1 Quality metric 1
8.1.2 Quality metric 2
8.1.3 Quality metric 3
8.2 Use case scenarios
8.2.1 Scenario One
9 Project Resource Estimates
9.1 Scope of construction phase
9.2 Projection of remaining overall project resource requirements
9.2.1 Expected project resource requirement category
9.2.2 Expected project impact and benefit
9.2.3 Indicative resource estimates for construction, transition and maintenance:
10 Appendices
10.1 Appendix One: Related user requests that have been accepted since the January 2015 release:

Glossary

Domain Terms

Introduction

Purpose

The purpose of this project is to review the current hierarchy for |263134008| Ligament rupture and apply quality criteria to this hierarchy, identify and resolve inconsistencies and omissions.

Audience and stakeholder domain:

The audience for this document includes all standards terminology leaders, implementers and users but is especially targeted at those stakeholders from the domain of orthopedics with a particular emphasis on physiotherapists
A further significant audience is the community of SNOMED authors that may be requested to implement the recommended specification.

Input from stakeholders:

The Chartered Society of Physiotherapy (CSP) in the UK commissioned the identification of a subset of SNOMED CT descriptions that could be used as search terms, linking common symptoms, signs and disorders with a directory of physiotherapy services (Clinic Types).
It was during this work that some anomalies were identified within the ligament rupture hierarchy and this was then brought to the attention of the IHTSDO. As the integrity of this hierarchy is important in ensuring that the requirements of the CSP Use Case are met they have remained key stakeholders.
In addition the Quality Assurance Committee have acted as stakeholders and have used this work as an example of how quality criteria might be applied to the content of SNOMED CT following a presentation at the October 2013 IHTSDO Quality Assurance Committee meeting.
A review of the inception/elaboration document was conducted by Cathy Richardson (on the 2013 CTP cohort) and Jeremy Rogers Consultant Clinical Terminologist. Their feedback has been incorporated into this (v0.5) draft.
Two external Consultant Orthopaedic Surgeons reviewed the documents and provided advice; Paul Paul from St Bartholomew's and Royal London Hospital and Andy Goldberg from the Royal National Orthopaedic Hospital Trust, London stakeholders

Degree of consensus on the statement of problem:

There was agreement from all stakeholders on the statement of the problem and proposed solution.

Statement of the problem or need

Summary of problem or need, as reported:

A review of the hierarchy identified the following issues:

• Inconsistency of synonym use

• Inconsistency in availability of synonyms within sibling concepts

• Reduced availability of partial tear concepts with respect to complete tear concepts

• Inconsistency in use of navigational concepts (ligament v joint)

• A significant number of the concepts within the hierarchy remain primitive (71 concepts fully defined, 53 concepts primitive)

The impact of these inconsistencies results in an inability to consistently search and retrieve concepts relating to ligament rupture.

Summary of requested solution:

The stakeholders requested that the solution deliver the following:

• A literature review to ascertain the currently accepted terminology for ligament injuries (rupture or tear).

• Review the ligament rupture hierarchy and produce a set of concepts with their descriptions that adhere to the editorial principles for the fully specified names, preferred and synonymous terms.

• Ensure that there are available matching concepts for partial and complete ruptures.

• That each remaining concept labeled as primitive be modeled such that it becomes fully defined.

Statement of problem as understood

SNOMED CT is an amalgamation of 2 terminologies; SNOMED Reference Terminology and Clinical Terms Version 3. Each of these terminologies has an individual history that has shaped and supported the evolution of the respective terminology content to serve a number of different use cases in the US and UK.
Given that SNOMED CT is an amalgamation of 2 'local' terminologies it is likely that for a given clinical subject area there will be a mixture of descriptions that need to be harmonized and presented in a consistent manner. The subject area of ligament ruptures is one such area that needs to be reviewed with respect to content to ensure that there is consistency in use of descriptions and that those descriptions represent contemporary clinical usage.
The purpose of this content development project is to establish a set of concepts which support the recording of ligament ruptures consistently using contemporary clinical language and fully modeled within SNOMED CT.

Detailed analysis of reported problem, including background

Background

The use case for this implementation of SNOMED CT was the Choose and Book (CAB) application in General Practice within England. The CAB application is a national electronic referral service that allows general practitioners, their staff and patients to choose and book, in real time, an outpatient appointment from a selection available at a date, time, place and provider of their choice.
The CAB application links the general practice to the local outpatient service providers and can be accessed via the GP clinical system. When a GP wants to refer a patient with a particular disorder to a specialist he types an appropriate key word or phrase into the search box and this then returns a list of service providers who can assess and/or treat that problem. For example the GP may type in 'ruptured ligament' and the Choose and Book application will return a list of physiotherapy units within the area who would be able to provide an appropriate service for this condition.
The method used to identify the subset of SNOMED CT descriptions was to identify a particular symptom or disorder and then to use the human anatomical structure to order the list of terms and then use a SNOMED CT browser to identify the appropriate SNOMED CT Identifier and description.
This was a relatively simple process but in trying to achieve consistency and completeness across all of the detail of anatomical structures, symptoms and disorders it became apparent that at this moment in time the content of SNOMED CT within the musculoskeletal domain was not sufficiently consistent and complete to support a use case that required greater detail.
In addition the IHTSDO Quality Assurance Committee (QAC) were working to identify and apply Quality Metrics to the content of SNOMED CT. It was considered that looking more closely at the findings of the CAB subset project might provide useful input into this work. The following purposes were identified by the QAC:

• To identify a method for applying a limited number of quality metrics to the content of SNOMED CT.

• That the quality metrics used should identify inconsistencies and omissions that would be of significance to clinical users of SNOMED CT.

• To identify whether the incidence of the inconsistencies and omissions are of a sufficient level to bring disrepute to the product and IHTSDO, and if so, to raise this to the attention of the Content Committee for consideration

The quality metrics to be measured included:

• Number of primitive and fully defined terms

• Consistency of use of preferred and synonymous descriptions

• Presence/completeness of concepts within the hierarchy

• Consistency in use of 'grouper concept descriptions'

• Visual presentation of hierarchy

• Presence of editorial principles within the Editorial Guide to support consistent authoring in relation to the above.

 

Detailed findings

Examination of the | Ligament rupture | 263134008 hierarchy:

Simple counts (excluding parent concept):

Number of child concepts - 95

Number of fully defined concepts - 64

Number of primitive concepts – 31

 

Quality assurance of the concepts within the hierarchy

:

Potential inconsistency of synonym use:
The fully defined parent concept 263134008 itself has the following descriptions:
F ligament rupture (disorder)
Pligament rupture
Scomplete tear of ligament
Sligament tear
The parent Fully Specified and Preferred term refers to rupture without reference to whether it is partial or complete and therefore the addition of a synonym that specifies 'complete' tear would appear to be an error. This is supported by the presence of both complete and partial rupture/tear as children of this concept.
The Editorial Guide specifies that the use of a 'narrower' synonym must be avoided and therefore this is considered to be an error.

Inconsistency of use of preferred term within the child concepts:

The parent preferred term is 'ligament rupture' with a synonym of 'ligament tear'. There is mixed use of the terms 'rupture' and 'tear' as preferred terms within the children of the 263134008 parent that suggests inconsistency with the parent term:

• Number of preferred terms 'rupture' 19

• Number of preferred terms 'tear' 76

It should also be noted that a similar anomaly exists within the morphologic abnormality hierarchy for | rupture | 125671007 (syn. - Tear) in which the child concepts listed include:

 

• Number of preferred terms 'tear' 101

• Number of preferred terms 'tear' that have a synonym of 'rupture'0

Therefore while the parent term has a preferred term of ligament rupture if a user enters the search string of ligament rupture, only 18 concepts will be returned whereas using a search string of ligament tear will return 112 concepts.
The Editorial Guide makes no reference to the consistent use of preferred and synonymous terms within the child concepts.

Presence of complete and partial rupture/tear:

For each of the complete rupture terms there exists the possibility of a partial rupture.

• Number of partial rupture of ligament terms6 (discrete concepts)

Clearly there are a significant number of possible partial ruptures that cannot currently be recorded using a pre-coordinated term.
The Editorial Guide makes no reference to the requirement for completeness within any given hierarchy.

Naming of grouper concept descriptions navigational concepts:

There is inconsistency in the naming conventions of the navigational terms within the hierarchy:
595273018 complete tear, elbow joint (disorder)
595315016 complete tear, hip ligament (disorder)
As this section of the hierarchy refers to ligament injuries it would seem more appropriate for 'complete tear, elbow joint' to be replaced by 'complete tear, elbow ligament' and preferably adopt the pattern of. 'complete rupture of elbow ligament'.
The Editorial Guide identifies the requirement for navigational concepts but does not appear to address the specifics of what is considered to be good editorial naming policy for this class of concepts.

Visual presentation of the hierarchy (using UK Preferred descriptions):

If we examine the current groupings within the hierarchy the following pattern emerges:
263134008 ligament rupture
209621009 complete tear, hip ligament
398733004 partial rupture of ligament
263139003 rupture of ligament of knee joint
239725005 rupture of anterior cruciate ligament
209629006 complete tear, knee, anterior cruciate ligament
209520004 partial tear, knee, anterior cruciate ligament
While it is accepted that from description logic perspective the above presentation is not incorrect, except for the inconsistency in use of preferred and synonymous descriptions, from a clinical user's perspective the following might be more acceptable:
263134008 ligament rupture
123456789 rupture of ligament of hip joint
(Syn. tear of ligament of hip joint)
234567890 rupture of ligament of knee joint
(Syn. tear of ligament of knee joint)
345678901 complete rupture of ligament of knee joint
(Syn. complete tear of ligament of knee joint)
456789012 partial rupture of ligament of knee joint
(Syn. partial tear of ligament of knee joint)
In addition consideration could also be given to adding the following grouper concepts to aid retrieval:
xxxxxx rupture of ligament of axial skeleton
xxxxxx rupture of ligament of lower limb

Subsidiary and interrelated problems

Grading of Ligament Sprains

Since this project began there has been an update to the musculoskeletal section, in particular the addition of:

|1791000119105| Sprain of ankle grade I (disorder)

|1781000119107| Sprain of ankle grade II (disorder)

|609495006| Sprain of ankle grade III (disorder)

The following definitions[1] have been assigned to these concepts:

 

Grade 1 sprain:        Microtears and stretching but ligament integrity intact

 

Grade 2 sprain:        Partial tearing of the ligament. If the ankle joint is examined and moved in certain ways, abnormal looseness (laxity) of the ankle joint occurs.

 

Grade 3 sprain:        Complete tear of the ligament. If the examiner pulls or pushes on the ankle joint in certain movements, gross instability occurs.

 

A review of the American Academy of Orthopaedic Surgeons and the medical literature suggest that this grading is fairly uniformly applied to sprains of all of the major ligaments. Further work may be necessary to establish whether this would be acceptable to other jurisdictions.

 

In addition sprain is defined[2] as ‘A joint injury in which some of the fibres of a supporting ligament are ruptured but the continuity of the ligament remains intact’. This definition seems to be at odds with the grading suggested above given that grade 3 is complete rupture.

 

There is a concept | Sprain or partial tear, knee, lateral collateral ligament (disorder) | 209515004 which has an IS_A relationship with | Partial tear, knee, lateral collateral ligament (disorder) | 209517007 and | Sprain of lateral collateral ligament of knee | 35726004 which would suggest that at some point there has been a view that there may be a relationship between sprain and partial rupture.

 

 

 

A further complication arises as SNOMED CT morphology suggests the following:

 

|384709000| Sprain (morphologic abnormality is a form of |3399917004| Traumatic abnormality by mechanism (morphologic abnormality) whereas |263722006| Complete rupture (morphologic abnormality) and |263834005| Partial tear (morphologic abnormality) are both forms of |107658001| Mechanical abnormality (morphologic abnormality).

 

So we have a situation in which a sprain is considered to be secondary to some traumatic injury and yet the definitions of the grades of sprain are defined by structural characteristics which are agnostic to the mechanism of injury, whether traumatic or non-traumatic.

 

1.1.1 Traumatic verses non-traumatic ligament damage

A further question arises as to whether it is possible to suffer any form of ligament structural damage without a traumatic insult and, if you can, whether such disease entities should properly be labelled a ‘sprain’ or, if sprain and rupture are synonymous, a ‘rupture’.. A review of the literature suggests that there are certain genetic conditions which can give rise to abnormalities of collagen structure (regulation of size and configuration of type I collagen fibrils).

 

The literature cites Achilles tendon and anterior cruciate ligament rupture associated with collagen, type V, alpha 1 (COL5A1) polymorphism[3], these are reported as spontaneous sprains/ruptures in athletes undergoing normal athletic activity rather than as a result of ‘traumatic injury’. This begs the question of whether the label ‘trauma’ does, or should, distinguish between excessive force applied to normal strength tissue, and normal forceapplied to unusually weak tissue. A pathological fracture is not normally considered a subclass of traumatic injury, so we may assume neither should a pathological sprain.Anatomy for structure of ligament of joint

An attempt to identify all possible ligaments was made by examination of the body structure section and in particular:

| Structure of ligament of joint (body structure) | 123859001

There are 714 concepts within this section, all primitive. Some concepts are, however, known to be either missing or are misplaced and it is quite difficult to ascertain the full number of body ligaments. This is being addressed as part of the anatomy project.

At the time that this project was first begun there are many non-human anatomical structures present within this hierarchy, including:

370627006 annular ligament of equine distal limb

370712001 suspensory ligaments of equine limb

These have now been addressed as part of the veterinary extension and are no longer present in the core release.

1.1.2 Related content tracker projects:

The following content tracker projects have a relationship with or may be impacted by this project:

• artf6206 : Anatomy

• artf222770 : Review concepts: Non-human

• artf222524 : Rework Hierarchy: Arthropathy of knee joint

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[1] http://orthoinfo.aaos.org/topic.cfm?topic=A00150

[2] http://medical-dictionary.thefreedictionary.com (Dorland’ Medical Dictionary)

[3] Posthumus M, September AV, O'Cuinneagain D, van der Merwe W, Schwellnus MP, Collins M. The COL5A1 gene is associated with increased risk of anterior cruciate ligament ruptures in female participants Am J Sports Med. 2009 Nov;37(11):2234-40

Mokone GG, Schwellnus MP, Noakes TD, Collins M. The COL5A1 gene and Achilles tendon pathology. Scand J Med Sci Sports. 2006 Feb;16(1):19-26.

Risks / Benefits

Some of the problems identified may not be soluble given the current state of 'knowledge' of the subject area; in particular the extent to which it is possible to clearly identify whether any grade of sprain can be easily attributed

to a traumatic or non-traumatic (genetic or otherwise) cause.
For this reason a decision has been taken to consider the risks of addressing all the issues raised except those associated with the cause, traumatic v non-traumatic, of the ligament rupture, however, this risk cannot be excluded from the risk of actually addressing the problem.

Risks of not addressing the problem

The following risks may arise if the problems identified are not addressed:

• Difficulty in searching concepts relating to ligament rupture/tear consistently and accurately

• Difficulty in computing equivalence and therefore retrieving concepts consistently for decision support and aggregate analysis

• Translation into other languages will be more difficult if there is inconsistency in use of descriptions

• Possible reputational risk if potential users perceive the content in this area to be inconsistent or incomplete

• Potential confusion due to apparent duplication of concepts between the hierarchies of ligament rupture and sprains.

The project risk profile is determined using the project risk profile assessment instrument as described in the "Guide to Stakeholder Engagement in Content Development" document.