Classification system
Rockwood Classification
Rockwood Classification of Acromioclavicular Joint Injuries
The Rockwood classification grades acromioclavicular joint injuries into six types by which ligaments are torn and by the direction and magnitude of clavicular displacement, where types I and II are treated non-operatively, types IV to VI operatively, and type III remains contested.
What the Rockwood category means
Rockwood categories describe different patterns, not increasing severity — a higher-lettered or higher-numbered category is not necessarily a worse problem. The groups below are descriptive.
- Non-operative (types I–II)1–2
Sling, analgesia and early motion. Residual prominence and cross-body discomfort are common but rarely disabling.
- Contested (type III)3–3
Randomised and comparative evidence does not favour routine surgery. The ISAKOS split into a stable IIIA and an unstable IIIB exists precisely because a single grade was being used for two different injuries.
- Operative (types IV–VI)4–6
Displacement is either in a direction the soft tissues cannot accommodate or large enough that the deltotrapezial fascia has failed.
Published criteria and reliability
The published cut-offs that define this instrument, and the measured agreement between observers using it. Each is reported with the population it was derived in.
| Type | Value | Subscale | Population | Follow-up | Source |
|---|---|---|---|---|---|
| Criterion | Coracoclavicular distance increased less than 25% over the uninjured side — type II | — | Acromioclavicular injuries on a bilateral anteroposterior (Zanca) view | — | Rockwood CA Jr 1984 |
| Criterion | Coracoclavicular distance increased 25% to 100% — type III | — | Acromioclavicular injuries on a bilateral anteroposterior (Zanca) view | — | Rockwood CA Jr 1984 |
| Criterion | Coracoclavicular distance increased 100% to 300% with deltotrapezial detachment — type V | — | Acromioclavicular injuries on a bilateral anteroposterior (Zanca) view | — | Rockwood CA Jr 1984 |
| Criterion | Type III subdivided into stable IIIA and unstable IIIB on scapular dyskinesis and reduction on a cross-body view | — | ISAKOS Upper Extremity Committee consensus on acromioclavicular injuries | — | Beitzel K 2014 |
Criterion is a published cut-off, definition or performance figure belonging to a classification or decision rule — it is not a change score and should not be read as one.
How the score is calculated
Stated in full so the calculation can be independently checked, and reproduced by hand if needed.
Type I is a sprain of the acromioclavicular ligaments with a normal radiograph. Type II is disruption of the acromioclavicular ligaments with the coracoclavicular ligaments intact, giving a coracoclavicular distance less than 25% greater than the uninjured side. Type III is disruption of both ligament complexes with the coracoclavicular distance 25% to 100% greater than the uninjured side and the deltotrapezial fascia largely intact. Type IV is posterior displacement of the distal clavicle into or through the trapezius, identified on the axillary view and defined by direction rather than magnitude. Type V is superior displacement with the coracoclavicular distance 100% to 300% greater than the uninjured side and detachment of the deltoid and trapezius from the distal clavicle. Type VI is inferior displacement of the clavicle to a subacromial or subcoracoid position. Because the magnitude criteria are expressed as a percentage difference, a bilateral comparison view is required: an absolute coracoclavicular measurement on the injured side alone cannot assign a type. The ISAKOS consensus recommends subdividing type III into IIIA (stable, no scapular dyskinesis, reduces on a cross-body view) and IIIB (unstable, scapular dyskinesis or persistent displacement), because those two subgroups behave differently and were the main source of disagreement about operating on type III.
Instrument profile
- Developer
- Charles A. Rockwood Jr., extending the earlier grades of Tossy and of Allman
- Institution
- University of Texas Health Science Center at San Antonio, United States
- First published
- 1984
- Custodian
- Refined by the ISAKOS Upper Extremity Committee, which in 2014 recommended subdividing type III into a stable IIIA and an unstable IIIB
- Items
- 1
- Response format
- Single radiographic pattern selected from six
- Score range
- 1 to 6
- Direction
- Categories are not ranked by severity
- Completion time
- About 1 minutes
- Regions
- Shoulder
- Conditions
- Acromioclavicular joint injury, Acromioclavicular joint separation, Shoulder separation, Distal clavicle injury
- Procedures
- Coracoclavicular ligament reconstruction, Acromioclavicular joint stabilisation, Hook plate fixation, Distal clavicle excision
- Validity
- The grouping into non-operative (I–II) and operative (IV–VI) is well supported. The predictive value of type III alone is poor, which is what the ISAKOS subdivision was designed to address.
- Reliability
- Agreement is good for types I, II and VI and weakest between III and V, where the distinction rests on a percentage measurement taken from a single static film; adding a stress or cross-body view and an assessment of scapular control improves it.
When to use the Rockwood
Well suited to
- Grading an acute acromioclavicular separation to decide between a sling and surgical referral.
- Documenting the injury in terms that transfer between clinicians and into registries and trials.
- Identifying the posteriorly displaced type IV, which changes management and is easily missed without an axillary view.
Limitations and poor fits
- Grading from an anteroposterior radiograph of the injured shoulder alone — every magnitude criterion is a comparison with the uninjured side, and posterior displacement is invisible on that view.
- As a treatment algorithm for type III, where the type on its own does not settle the decision; assess scapular control and dynamic reduction, and weigh the patient’s demands.
- Chronic or recurrent instability, where the tissue quality and the time from injury matter more than the original grade.
- Distal clavicle fractures, which can mimic a separation radiographically but are classified and treated differently.
Rockwood compared with other instruments
Instruments measuring a related construct, with the practical difference between them.
| Instrument | Items | Range | What it adds |
|---|---|---|---|
| Constant Score | 10 | 0–100 | The Constant-Murley score is a 100-point clinician-administered shoulder assessment combining 35 subjective points for pain and daily activities with 65 objective points for measured range of motion and abduction strength, where 100 represents a normal, pain-free shoulder. |
| ASES Score | 11 | 0–100 | The ASES score is a patient-reported shoulder index running from 0 to 100 in which a single 0–10 pain rating supplies 50 points and ten activities of daily living rated 0–3 supply the other 50, so that 100 represents a pain-free shoulder with no functional difficulty. |
| SPADI | 13 | 0–100 | The SPADI is a 13-item patient-reported questionnaire that measures shoulder pain and disability over the past week on two subscales — 5 pain items and 8 disability items — each rated 0–10 and transformed to a 0–100% score in which a higher score means more pain and greater disability. |
| AO/OTA | 3 | 1–3 | The AO/OTA classification gives every fracture an alphanumeric code in which the first digit is the bone, the second the segment and the letter the fracture type — extra-articular, partial articular or complete articular in an end segment, and simple, wedge or multifragmentary in a shaft — so that 32-A is a simple femoral shaft fracture and 43-C a complete articular pilon fracture. |
Copyright and permitted use
Published openly because it is the question every clinician and researcher asks before using an instrument, and almost nobody answers it.
A published radiographic and clinical classification system. No licence is required.
References
- Tossy JD, Mead NC, Sigmond HM. Acromioclavicular separations: useful and practical classification for treatment. Clinical Orthopaedics and Related Research. 1963.
- Allman FL Jr. Fractures and ligamentous injuries of the clavicle and its articulation. Journal of Bone and Joint Surgery (American Volume). 1967.
- Rockwood CA Jr. Injuries to the acromioclavicular joint. Rockwood and Green’s Fractures in Adults (book chapter), J. B. Lippincott. 1984.
- Beitzel K, Mazzocca AD, Bak K, et al.. ISAKOS upper extremity committee consensus statement on the need for diversification of the Rockwood classification for acromioclavicular joint injuries. Arthroscopy. 2014.
Editorial status
This page has not yet been signed off by a named clinical reviewer. The scoring logic is stated in full above so it can be independently verified, and every threshold is traceable to its source. See our editorial methodology.