Heterotopic Ossification

 

Heterotropic Bone Brooker 2Heterotropic Bone Brooker 3

 

Definition

 

Formation of lamellar bone / osteoid matrix in soft tissue

 

Types

 

Acquired / traumatic - fractures, total joint arthroplasty

Neurogenic - head injury, spinal injury

Genetic - fibrodysplasia ossificans progressiva

 

Incidence

 

Zhu et al Arch Orthop Trauma Surg 2015

- systematic review of 6500 cases THA

- incidence of HO 30%

- increased with male / cemented implants / ankylosing spondylitis

 

Risk factors

 

Male

Ankylosing spondylitis

Cemented femoral stems

History of HO

 

Surgical approach

 

Herzberg et al Eur J Orthop Surg Traumatol 2024

- systematic review of 26 studies and 6500 THA

- increased risk of HO with lateral approach

 

Brooker Classification: Type III and Type IV clinically relevant

 

Brooker classfication

 

Type I:  Isolated islands of bone

Heterotropic Bone Brooker 1

 

Type II:  Bony spurs from pelvis and proximal femur, gap > 1 cm

Heterotropic Bone Brooker 2THR HO Brooker 4 Poster Excision

 

Type III:  Gap < 1 cm

THA HO

 

Type IV:  Apparent ankylosis

HO THA preHeterotropic Bone Brooker 3

 

Clinical

 

Usually asymptomatic

 

Brooker III / IV - stiffness

 

Other

- pain

- sciatic nerve irritation

- dislocation secondary to impingement

 

Natural history

 

Willburger et al J Orthop Surg Res 2022

- 75 THA followed for 10 years

- took up to 3 years for all HO to mature

 

Prevention 

 

Indications

 

High risk patients

- Ankylosing Spondylitis

- previous HO

- Pagets / DISH

 

Options

 

NSAIDS

Radiotherapy

 

Results

 

Shapira et al Hip Int 2022

- systematic review of NSAIDS versus radiotherapy in high risk THA

- severe HO with radiotherapy: 0 - 12%

- severe HO with NSAIDS: 0 - 2%

 

Anti-inflammatories / NSAIDS

 

Indomethacin / Ibuprofen

 

Schneider et al Sci Rep 2023

- 1200 patients post THA

- no patient with indomethacin or ibuprofen developed Brooker III or IV

 

Diclofenac

 

Haffer et al Hip Int 2022

- meta-analysis of diclofenac in 6 RCTs and 1000 THA

- diclofenac effective

- no clinically significant HO (Brooker III and IV)

 

COX-2 inhibitors

 

Zhu et al Medicine 2018

- meta-analysis of 8 RCTs and 1600 THA

- selective COX2 inhibitors as effective as non selective NSAIDS

- reduced gastrointestinal effects with selective COX2 inhibitors

 

Radiotherapy

 

Indication

 

Very high risk patients

- previous HO 

- NSAIDS contraindicated

- post surgical excision of HO

 

Dosing

 

Milakovic et al Radiother Oncol 2015

- systematic review

- no difference low dose (<25Gray) versus high dose (>25Gray)

- typically single dose of 7Gy

 

Timing

- within 3 hours before or 3 days after

 

Results

 

Hu et al Med Dosim 2021

- meta-analysis of 10 RCTs and 1200 patients

- efficacy of both pre- and postoperative radiotherapy at prevention

- multiple fractions more effective than single fractions

 

Sheybani et al Int J Radiat Oncol Biol Phys 2014

- case control of 3500 patients

- no evidence of increase malignancy with radiotherapy for HO prevention

 

Biphosphonates

 

Doesn't prevent osteoid formation

- delays calcification and xray appearance of bone 

- calcification occurs once drug stopped

- no longer used

 

Surgical Excision

 

THA HOTHA HO excision

 

Indications

 

Significant symptoms / reduced ROM

Brooker III / IV

 

Timing

 

Mature HO

- cold bone scan

- serum ALP normal

 

Prophylaxis

 

Radiotherapy postoperatively as high risk 

 

Technique

 

Vumedi arthroscopic technique

 

Results

 

Lachiewicz et al J Arthroplasty 2022

- systematic review of 7 studies and 4 patients with grade III/IV HO

- good improvement in ROM

- inconsistent improvement in pain

- irradiation prevented recurrence

 

HO THA preHO THA post