Heterotopic Ossification: A Challenging Complication of Total Hip Arthroplasty: Risk Factors, Diagnosis, Prophylaxis, and Treatment

Abstract

Background. This review is intended to summarize the risk factors, classification, diagnosis, and treatment of heterotopic ossification (HO) of previously published studies. Results. Heterotopic ossification is a common complication of total hip arthroplasty. Its prevalence is not the same in all of the patient groups. Frequency of HO varies from 15 to 90%. Hip ankylosis, male gender, and previous history of HO are said to be risk factors with a significant level. Diagnosis is based on a single AP radiograph: the Brooker classification that divides HO into four grades is the most commonly used. The confirmation test that can be used is a bone scan. A great amount of bone metabolic turnover markers have been tested, but none of them seems to be relevant in case of prevention or diagnosis of HO. The most effective prophylactic treatment is radiotherapy or administration of nonsteroidal anti-inflammatory drugs. Over the years a lot of different RT protocols have been tested. Nowadays the most often used regimen is 7 Gy given postoperatively in a single dose. The most commonly prescribed drug in prophylaxis of HO is indomethacin. Also, the efficacy of ibuprofen and diclofenac was proven. Recently researchers focused on selective COX-2 inhibitors. They appear to be as effective as nonselective NSAIDs having less side effects. The one and only treatment of HO is a revision arthroplasty.

Clinical and radiological outcomes of total hip arthroplasty in patients affected by Paget’s disease: a combined registry and single-institution retrospective observational study

“…The observed incidence of HO in the institutional cohort was 52%, similar to previous published research [ 28 , 29 ]. It is unclear how the surgical approach can affect HO incidence, and there are no unequivocal opinions concerning the best procedure to prevent HO in terms of radiation therapy (single 7–8 Gy dose) [ 36 , 37 ] or chemoprophylaxis (including indomethacin, diclofenac or ibuprofen) [ 38 – 41 ].…”

Evaluation of the Impact of Different Pain Medication and Proton Pump Inhibitors on the Osteogenic Differentiation Potential of hMSCs Using 99mTc-HDP Labelling

“…Thus, there is evidence, supported by our results, that diclofenac supports in vitro osteogenic differentiation but the mechanism remains unknown. It is known, that BM-MSCs have compensatory mechanism to restore PEG2 synthesis as an intrinsic regulation of osteogenic differentiation if these cells are treated with NSAIDs [ 26 ] while the inhibition of the prostaglandin synthesis in vivo result is a limitation of pathologic bone growth, which makes these drugs very popular to avoid heterotopic ossifications after total hip replacement [ 10 , 11 ]. However, recent systematic reviews confirmed the absence of robust in vitro or clinical data regarding NSAIDs and their impact on bone formation, and encouraged researchers to perform further basic science and clinical studies to clarify the risks and benefits of NSAIDs in patients with musculoskeletal disorders [ 19 ].…”

“…The anti-inflammatory potential of these drugs reduces symptoms caused by the inflammatory component in pathologies like activated arthrosis and post-surgical inflammatory response [ 7 ]. An additional feature of NSAIDs (e.g., diclofenac and ibuprofen) is their ability to reduce heterotopic ossifications after total hip arthroplasty and acetabular fracture treatment [ 8 , 9 , 10 , 11 , 12 ]. Non-selective NSAIDs inhibit COX-1 and COX-2, while selective NSAIDs only inhibit COX-2.…”

Radiation therapy for the prevention of heterotopic ossification: Efficacy and toxicity of single fraction radiotherapy

“…Single fraction RT of 7 Gy postoperatively and indomethacin were the two most common used regimens with equal effectiveness. 38 Finally, three meta-analysis of randomizes clinical trials (RCTs) have compared RT to other treatment options mainly NSAIDs. In the two meta-analysis from Vanken et al , there was not any statistically significant difference, although Grade 3 and 4 HO was less often seen after radiation therapy while NSAIDs were considerably more cost effective as a treatment modality.…”