- See: Ossification of Soft Tissues:
and Myositis Ossificans
- occurence and formation of mature bone in non-osseous tissue;
- may present w/ signs of localized inflammation or pain, elevated skin temp, ect.
- tends to occur after thr, spinal injury
, head injury
, bruises, elbow trauma, total hip replacement;
- ref: Osteoblasts Have a Neural Origin in Heterotopic Ossification.
- Events leading to HO;
- mesenchymal cell (XRT prevents induced differentiation)
- matrix (EHDP)
- HIP HO:
- HO following THR:
- IM Nailing:
- Heterotopic ossification about the hip after intramedullary nailing for fractures of the femur.
- Heterotopic ossification around the hip with intramedullary nailing of the femur
- HO following acetabular fracture
- Heterotopic ossification as a complication of acetabular fracture. Prophylaxis with low-dose irradiation
- Heterotopic ossification following operative treatment of acetabular fracture. An analysis of risk factors
- Heterotopic ossification prophylaxis following operative treatment of acetabular fracture
- Extended iliofemoral versus triradiate approaches in management of associated acetabular fractures
- Prophylaxis with indomethacin for heterotopic bone. After open reduction of fractures of the acetabulum.
- Heterotopic Ossification following acetabular fixation: Incidence and risk factors: 10-year experience of a tertiary centre.
- HO of the elbow:
- Early excision of heterotopic ossification about the elbow followed by radiation therapy.
- HO following spinal cord trauma:
- radiographically develops in 3-5% of patients, 1-4 mo (or upto 18 mo) after injury;
- it occurs below the level of the injury, usually at major joints;
- incidence is 40% (1/2 of these are clinically significant);
- after transection of spinal cord, ossification often takes place in soft tissues adjacent to large joints;
- lower extremities are particularly suseptible & most dramatic changes are seen in Knee > Pelvis > Hip;
- characteristic finding is a bilateral accretion of well defined bone which encircle the joints;
- Resection of heterotopic ossification in patients with spinal cord injuries
- Resection of heterotopic ossification in the adult with head trauma
- Clinical observations on fractures and heterotopic ossification in the spinal cord and traumatic brain injured populations
- Surgical approaches for resection of heterotopic ossification in traumatic brain-injured adults
- Periarticular heterotopic ossification in head-injured adults. Incidence and location.
- Heterotopic ossification around the hip in spinal cord-injured patients. A long-term follow-up study
- Radiographic Studies:
- x-rays: soft tissue ossification usually does not appear in 1st mo
- bone scans
may reveal incr isotopic intake by the second weak;
- alkaline phosphatase
activity correlates w/ bone scans;
- Non Operative Treatment:
25 mg PO tid for 3-6 months;
- Prophylaxis with indomethacin for heterotopic ossification after Chiari osteotomy of the pelvis.
- theoretically works by delaying mineralization of osteoid
- diphosphonates do not prevent heterotopic bone formation in lab animals but they do delay of mineralization of osteoid.
- delay in mineralization caused by diphosphanates are reversed when the disphosphonates are discontinued;
- Radiation Therapy:
- single does of 600 to 800 centgray of radiation given within 24 hours of surgery preoperatively or 72 hours postoperatively;
- a relative contra-indication of XRT may be posterior hip dislocation
w/ femoral head frx, since there is a theoretical risk of
contributing to AVN or non-union;
- cost: $ 2,000 to 2,500;
- Preoperative irradiation versus the use of nonsteroidal anti-inflammatory drugs for prevention of heterotopic ossification following total hip replacement: the results of a randomized trial.
- Radiotherapy vs. nonsteroidal anti-inflammatory drugs for the prevention of heterotopic ossification after major hip procedures: a meta-analysis of randomized trials.
- Prevention of heterotopic ossification in high-risk patients by radiation therapy.
- The use of radiation to discourage ectopic bone. A nine-year study in surgery about the hip.
- Operative Resection:
Botulinum Toxin-induced Muscle Paralysis Inhibits Heterotopic Bone Formation
- main disadvantage is risk of recurrence heterotopic ossification;
- operative timing:
- if HO has caused the loss of motion, some recommend allowing process to mature (sharp cortical and trabecular markings)
before operative resection;
- some recommend waiting 12 months before operative resection;
- once serial radiographs have shown that the ossification is mature w/ sharp peripheral edges and no indication of expansion,
resection is considered;
- bone scans and alkaline phosphatase may not be helpful in predicting maturity of the ossification;
- What Risk Factors Predict Recurrence of Heterotopic Ossification After Excision in Combat-related Amputations?
- in the study by Genet, et al., a consecutive series of 143 patients w/ traumatic brain injury and spinal cord injury;
- some patients had complete ankylosis, and some had severe limitation of motion;
- patients with ankylosis had improvement from an average of 0° to 90° of hip flexion but had only 63° of motion;
- patients without ankylosis had improvement from an average of 38° to 95° of motion, with 83° of motion;
- authors noted the importance of estimating bone mineral density prior to surgery to assess the risk of intraoperative fracture;
- delayed surgery can increase in intra-articular pathology and osteoporosis;
- Impact of late surgical intervention on heterotopic ossification of the hip after traumatic neurological injury.
A clinical perspective on common forms of acquired heterotopic ossification.
Keeping Bugs Bunny on the Move
Heterotopic ossification in complex orthopaedic combat wounds: quantification and characterization of osteogenic precursor cell activity in traumatized muscle.
Original Text by Clifford R. Wheeless, III, MD.