MED. INFORM. (1976) VOL. 1, NO. 3, 203-208

Musculo-skeletal diseases-a system of nosology

S. NADE and G. W. NADEt Department of Surgery, The University of Sydney, Sydney, N.S.W., Australia.

(Received 28 September 1976)

Keywords: taxonomy, orthopaedic, classification, coding

A system of classification of musculo-skeletal diseases has been developed, which is based on topographical, morphological and aetiological criteria. The system is simple, each disease having a three-unit alpha-numeric code generated from a short key-list. The system currently has a potential of 2300 unique codes. Diseases grouped together under the same code are few and are so similar as not to lessen the value of the classification system for epidemiological studies.

Un systtme de classification des maladies osteo-musculaires a CtC dCveloppC : I1 repose sur des critkres topographiques, morphologiques et Ctiologiques. Le systtme est simple. Chaque maladie est repCrCe par un code composC de trois caractkres alpha-numCriques pris dans une courte liste de mots-clefs. Le systtme dispose d'un potentiel de 2300 codes. Les maladies qui ont CtC regroupCes sous un m&me code sont peu nombreuses. Comme il s'agit de maladies voisines, le systkme de classification garde toute sa valeur pour les ttudes Cpidkmiologiques.

1. Introduction Classijication is fundamental to the quantitative study of any phenomenon.

It is the basis of all scientific generalization and an essential element in statistical methodology. Any classification of diseases depends upon the use to be made of the statistics compiled.

Nomenclature is a list or catalogue of approved terms for describing and recording clinical and pathological observations. It is too varied and incon- sistent to serve as a statistical classification in a satisfactory way.

A statistical classification must be confined to a limited number of categories which will encompass the entire range of diseases. The categories should be chosen in such a way as to facilitate the statistical study of disease phenomena. A specific disease entity should have a separate title in the classification only when its separation is warranted because of its frequency of occurrence or importance as a morbid condition.

Every disease however, must have a place in the classification and miscel- laneous conditions not classified under specific title must be kept to a minimum.

Doctors are bad at recording data and use many different nomenclatures. The construction of a practical scheme of classification of diseases and injury for general statistical use necessitates various compromises, depending upon who is to use the classification.

t Systems Analyst.

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204 S. Nade and G. W. Nade

2. Objectives of the work Several of the orthopaedic associations of the English speaking world have

had sub-committees on classification of musculo-skeletal diseases. That of the Australian Orthopaedic Association, after considerable discussion, declared the purpose of a suitable classification, for its own use, to be: ‘ To record data pertaining to orthopaedics and traumatic surgery in such a way that is simple and logical, and places emphasis on common conditions. Such data couId then be used by orthopaedic surgeons, hospitals and a central registry as a data-base for epidemiological studies ’.

The requirements of the system of nosology to be developed were stated as:

1. Each disease entity should have a unique code. 2. There should be a key which allows easy generation of a code. 3. The system should accommodate about 2500 diseases. Other features deemed to be important in the system were preservation of

privacy for patient and participating surgeon, and adequate feedback of statistical data for participating surgeons to ensure their continuing co-operation.

Several international systems of nosology currently exist and have wide use, in addition to participating surgeons’ personal classifications. The reasons for seeking yet another system derive from the complexity, difficulty in coding and time taken to use those which exist. International Classification of Diseases [l], Standard Nomenclature of Diseases and Operations [2] and Systematized Nomenclature of Pathology [3] have been designed for use by a larger group of people, and find use in hospitals, which restricts their scope to only part of the population affected by musculo-skeletal diseases. The system of nosology to be described has a specific interest to orthopaedic surgeons, across the whole spectrum of their practice.

3. Methods Systematized Nomenclature of Pathology (SNOP), generates a 16-digit

numerical code for diseases, 4 groups of 4 digits being derived from key lists under the headings Topography, Morphology, Aetiology and Function. This gives an accurate and unique code for each disease, with a potential capacity of 1016.

Before the existence of SNOP was realized, we had independently arrived at a similar type of self-generating system of nosology, based on three headings and having a single alpha-numeric code for each, which would fulfil the specific criteria for musculo-skeletal disease and injuries defined above.

The headings used were Anatomical Area (Topography), Tissue Involved (Morphology) and Aetiology. Table 1 lists the titles under each heading and the alpha-numeric codes used. The potential number of combinations available is therefore :

Column 1 x Column 2 x Column 3 = 23 x 10 x 10 = 2300.

Therefore, fracture of the shaft of the femur would be coded as

and S (Thigh) 1 (Bone) 2 (Traumatic)

Osteoarthrosis of the hip as R 3 4.

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Musculo-sketetat diseases--a system of nosology 205

Anatomical areas Tissue Aetiology

A. Hand B. Wrist C. Forearm D. Elbow E. Arm F. Scapula/Clavicle G. Shoulder H. Head J. Neck K. Thoracic (Spine) L. Thorax/Chest

M. Lumbar (Spine) N. Abdomen P. Sacrum and Pelvis R. Hip S. Thigh T. Knee

1. Bone 1. Congenital 2. Cartilage 2. Traumatic 3. Joint or Synovium 4. Ligament 4. Degenerative 5. Muscle/Tendon 5. ' Rheumatic ' 6 . Nerve 6 . Vascular 7. Vessel 7. Neoplastic 8. Skin and Fascia 8. Metabolic/Endocrine 9. All tissues in area 9. Neurologic

3. Infective

10. Other (including Viscus) 10. Other /Unknown

U. Leg V. Ankle W. Foot X. M-S as a whole Y. Body as a whole 2. Other

Table 1. Key for self-generating code for musculo-skeletal diseases

The titles for each list were chosen intuitively and from experience and were an initial list which could be altered and developed as necessary after testing.

T h e questions that needed to be answered about this coding system were: 1. How many different diseases shared the same code? and 2. Did the system allow adequate subdivision of different disease entities for its specified purpose? (An obvious inadequacy is the failure to separate fractures of the neck of the femur from fractures in the shaft or supracondylar area.)

I n order to answer these questions and to test the system, electronic data processing methods were used so that compilation of lists, sorting of diseases into codes, modification of codes and additions and deletions from the disease lists could be done without difficulty.

The initial list of musculo-skeletal diseases was compiled from lists in the various classification systems mentioned and others used for personal classifica- tion systems. They were manually coded to provide a starting list of about 450 diseases.

Data processing was performed on a Digital P D P 11/40 computer with programmes written in Fortran (Figure 1).

Programmes were written to :

1 . Accept and validate the list of diseases, automatically giving each a sequence index number, and accepting a 30-character disease description.

2. Store the list on magnetic disc and cassette tape for backup.

3. Print out a sequential list of coded diseases.

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206 S. Nade and G. W. Nade

KEYBOARD CAPTURE ENTRY

+ UPDATING

MA1 NTENANCE

REJECT

MASTER MINTENANCE

t REFERENCE

Flow chart to show scheme for development of system of nosoIogy.

4. Update the sequential list by deleting, adding or changing items on the

5. Sort through the sequential list of diseases and extract, print out and

list, each identified by a unique sequence number.

total those having the same codes.

4. Results The current sequential list of diseases, including synonyms, numbers 21 20.

When diseases having the same code are grouped together, most are in groups of 1, 2 or 3 diseases. The larger groups are those with codes * 1 3 (bone infections), * 1 7 (bone neoplasms), * 5 2 (muscle injuries), * 0 7 (soft tissue neoplasms), W 1 0 (other foot bone disorders), W 1 1 (congenital foot bone disorders), W 9 1 (congenital foot disorders), X 1 0 (anomalies of all bones, of unknown cause), X 1 8 (metabolic/endocrine bone diseases), Y 9 0 (idiopathic disorders of body as a whole). (* Means that any anatomical area can be substituted.) Many of these lists include rare disorders, or those that have several synonyms.

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Musculo-skeletal diseases-a system of nosology 207

5. Discussion A new system of nosology for musculo-skeletal diseases has been developed

which should serve the purposes of orthopaedic surgeons and allow statistical information to be compiled.

The use of electronic data processing techniques has aided the development of the system. Without such rapid data processing the task of modifying a coding system for over 2000 diseases would have been monumental. Further modifica- tions can be easily made, and other data required for making the system usable can be added without difficulty. Such further data include, 1. An identifier for the patient, 2. An identifier for the surgeon whose patient it is, 3. The age of the patient, 4. The sex of the patient and 5 . The year of the disease or injury presentation.

Although International Classification of Diseases [l], Standard Nomen- clature of Disease [2] and the Pocket Guide to Diagnostic Coding for Depart- ments of Orthopaedic and Traumatic Surgery [4] produced by the Royal National Orthopaedic Hospital have widespread use in English speaking countries, they all have the disadvantage of the user having to seek out the correct code from a book containing many pages. Indeed, I C D and the Pocket Guide have no index and are not listed alphabetically.

The system of nosology described in this paper allows the code to be self- generated, in a hierarchal manner, from a short list of names and keys which are listed on a single page.

It is a simple classification of diseases for the purposes of research, incidence and epidemiology, which should fulfil all the requirements of participating orthopaedic surgeons, whether in a local area, nationally or even internationally.

The main objectives of any coding system are: the transformation of data into a form in which it can readily be stored, collected, processed, retrieved and manipulated ; the identification of the patient; and the compilation of statistics of prevalence and incidence of disease.

We believe that the proposed system has the following advantages over those at present used :

1. I t is simple in concept, and to use.

2. It is brief and concise, the key for the code being in three short columns

3 . It has utility, in that the defined objectives are more easily achieved with

4. I t is consistent in that any disease has the same identification from day to A ' telephone directory ' list of codes could easily be compiled from

which fit easily on a page.

the coding system than without it.

day. the coded disease list to check a code of which a user was uncertain.

5 . It is sufficiently precise for any two or more items that can usually be distinguished to have separate identifiers. Those areas where a large number of disease names have the same code have been described above. To separate these further is a simple matter, using a fourth modifying column in the code. Many different modifiers are possible : their mode of use would depend on whether the coding system satisfied its users.

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208 Musculo-skeletal diseases-a system of nosology

6 . Because of the partial hieiarchal structure of code generation, the system has generality, thus aggregating separate codes with minimum difficulty to achieve broader groupings. The use of a computer sort routine makes this criterion less important than if manual sorting is done.

7. The coding system is relatively easy for a clerk with some medical knowledge to use and thus is economical; however, its economy of time in use allows for the doctor to do the coding with even greater accuracy.

8. The code system has such a degree of uniqueness that comparisons can be made over as wide an area and time interval as possible. Standardization of nomenclature is not important as the criteria of topography, morphology and aetiology remain constant regardless of nomenclature. Some diseases will no doubt cause confusion in the choice of category to code them, especially where more than one tissue is involved. Only general use, in a selected test population, will illuminate these and such a trial is planned as the next phase of development.

As extensions of knowledge and new techniques introduce more precise identification of diseases, the hierarchal and self- generating design of the code system can be modified to encompass the changes.

This would appear to be the hardest goal to achieve. Because of its fulfilment of the other criteria discussed above, the proposed system warrants wider discussion and trial.

9. The system is adaptable.

10. The final essential criterion for a coding system is acceptability.

Acknowledgments Financial assistance for the system development was granted by the Post

Gradual Medical Foundation Grants Fund of the Coppleson Post Graduate Medical Institute in The University of Sydney, especially its Ladies’ Auxilliary ; and the Medical Research Committee of the University of Sydney. Dr A. H. Goodman helped solve the problems in the operation of the computer, and Dr V. X. Gledhill gave helpful advice in discussion of the early development of the system.

The stimulus to the study followed the appointment of Dr Sydney Nade to a sub-committee of the Australian Orthopaedic Association on Classification of Diseases. The other members of the sub-committee, Dr W. N. Gilmour (convener) and Professor R. L. Huckstep share credit for the development of the key for the coding system, and the discussions which led to the decision to adopt such a system.

All this help is gratefully acknowledged.

REFERENCES 1 . Manual of the International Statistical Classification of Diseases, Injuries and Causes of

Death, 1967, Eighth Revision 1965 (World Health Organisation, Geneva). 2. HAYDEN, A. C., and THOMPSON, E. T. (Eds.), Standard Nomenclature of Diseases and

Operations, 1961, 5th Edition (McGraw Hill, New York). 3. WELLS, A. H., 1963, Systematised Nomenclature of Pathology (American College of

Pathologists, Chicago). 4. Pocket Guide to Diagnostic Coding for Departments of Traumatic or Orthopaedic Surgery,

1973, based on the Handbook of the Royal National Orthopaedic Hospital, London, and the VIIIth Revision of the I.C.D.

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