Originally designed for after THA / around hip. Poor system, unreliable, poor consistency, poor correlation with patient outcomes. HO commonly occurs between muscle and joint capsule, and is an abnormal pattern of behaviour from fibroblasts, not from ectopic or metastatic calcification. More common in men (2:1), in patients with spinal cord injuries / stroke / traumatic brain injuries / prolonged coma, high injury severity score (ISS) for poly-trauma, after total hip / total knee, large surgical approaches, sites of previous HO
Prevention
- Only evidence-based method is peri-operative radiation (700 centi-gray) either <24hrs pre- or <48hrs post-operatively.
- Commonly used methods incl NSAID and bisphosphonate

Grade	Description
1	Isolated islands of bone
2	Bone spurs from femur / ilium, >1cm gap
3	Bone spurs, <1cm gap
4	Bone spurs with apparent bony ankylosis

Charcot foot, Brodsky classification

The Brodsky classification is a classification system for location and distribution of pathology throughout a Charcot Foot.

The Eichenholtz classification is a radiographic and clinical assessment score for activity of Charcot pathology within the foot.

Stage	Phase	Description
0	Early	Joint oedema present, bone-scan positive, normal radiographs
1	Fragmentation	Maximal oedema, osseous fragmentation and joint dislocation
2	Coalescence	Oedema reducing, fragment coalescence and resorption of fine bone debris
3	Reconstruction	Oedema resolved, radiographic evidence of remodelling and consolidation of bone fragments

Cerebral palsy, Gross Motor Function Classification System (GMFCS)

GMFCS is a functional assessment, based on function of the patient, being their degree of activity, gait aid requirements and independence.

Level	Description
1	Speed / balance and coordination are impaired, but patient is able to walk, play and climb stairs without need for railings
2	Speed, balance, coordination are all significantly impaired, patients may use gait aids (hand-held or wheelchair) depending on terrain and distance, will use railings for stairs and will have very limited running and jumping
3	Patients will utilise hand-held gait aids for most indoor movement, with wheeled mobility for outdoors and long distances, may self-propel for shorter distances.
4	Children use methods of mobility that require physical assistance or powered mobility in most settings. They may walk for short distances at home with physical assistance or use powered mobility or a body support walker when positioned. Outdoors / community mobility is in a manual wheelchair or powered mobility.
5	Totally dependent on assistance, wheelchair bound in all settings, limited ability to maintain antigravity head and trunk postures or control leg and arm movements

No score is an absolute predictor of need for amputation, but only acts as a guide. As such it is better to use in conjunction with sensible assessment of the plantar foot & reconstruction needed. Memory aid, “VISA gives you double points after 6 hours”

Component	Finding	Points
Vascularity	Poor pulse	1
	Pulseless & poor capillary refill	2
	Totally avascular	3
	Double this score if ischaemia >6 hours
Injury (skeletal / soft tissue)	Low energy	1
	Medium energy	2
	High energy	3
	Very high energy	4
Shock	Systolic BP > 90mmHg	0
	Hypotensive transiently	1
	Persistent hypotension	2
Age	< 30 years	0
	30-50 years	1
	> 50 years	2

Helfet et al in 1990 used the MESS score to prospectively evaluate for management and outcomes. They found that the MESS as an objective criteria can predict amputation after lower-extremity trauma. MESS was used in 26 lower-extremity open fractures with vascular injury. Average score for the 14 salvaged limbs was 4.00, while average score for the 12 amputated limbs was 8.83 (p < 0.01). MESS > 7 was 100% predictive for final amputation

Poly-trauma, Injury Severity Score (ISS)

The ISS has been developed primarily as a research tool. It was not constructed to guide individual patient management, as it does not take into account the specifics of any one injury. It can be used to guide overall prognostication, but this is not its primary purpose. Injuries are classified by body regions, and severity. The score is obtained as ISS = A^2 + B^2 + C^2, where A, B and C are the three worst body-region injuries. However, if any injury is scored 6 (unsurvivable), the overall patient is scored 75 (unsurvivable).
Body regions are head and neck, face, thorax, abdomen, pelvis and extremity

cerebralpalsy.com.au
orthobullets.com
Togawa S, Yamami N, Nakayama H, Mano Y, Ikegami K, Ozeki S. The validity of the mangled extremity severity score in the assessment of upper limb injuries. J Bone Joint Surg Br. 2005;87(11):1516‐1519.
Baker SP, O’Neill B, Haddon W Jr, Long WB. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma. 1974;14(3):187‐196.

Sean Griffiths, WH Resident, 2020

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.