Heterotopic bone formation after joint replacement.

Bone formation outside the skeleton, heterotopic ossification (HO), is a common finding on radiographs from patients who have undergone arthroplasty of the hip, knee, shoulder, or elbow. Only a minority (5%-10%) of the patients with HO suffer from any consequence of the condition. However, because of the great number of joint replacements performed, the number of patients with decreased function that can be attributed to HO is significant. The risk for severe HO after total hip arthroplasty is increased in 1) patients who have developed HO after previous surgery, 2) men with hypertrophic osteoarthrosis and, 3) in patients with ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis. The same risk factors are probably valid for other joints as well. Two preventive treatments for HO after hip arthroplasty, nonsteroidal anti-inflammatory drugs and local radiation, are effective and reasonably well documented but are associated with potential side effects. Thus, a treatment protocol to prevent HO must identify the patients at risk for severe HO and recommend them treatment with one of these two modalities. Based on the current literature, we suggest that the patients at risk for severe HO be treated with 1) nonsteroidal anti-inflammatory drugs from the day of surgery for 7-10 days or 2) preoperative (or postoperative) radiation in a single dose.

Preventive effects of ibuprofen on periarticular heterotopic ossification after total hip arthroplasty. A randomized double-blind prospective study of treatment time.

We determined the efficacy and the minimum treatment time necessary for prophylaxis with nonsteroidal anti-inflammatory drugs (NSAIDs) for periarticular heterotopic ossification (HO) after total hip arthroplasty (THA). Using a double-blind placebo controlled design, 144 patients operated on with total hip arthroplasty for primary arthrosis were treated postoperatively with (1) ibuprofen for 3 weeks, (2) ibuprofen for 1 week and placebo for the next 2 weeks or (3) placebo for 3 weeks. Radiographic occurrence of periarticular heterotopic ossification and complications of the treatment were recorded for the first year. Both ibuprofen-treated groups showed significantly less HO than the placebo-treated group. There was no difference in HO between the patients treated for 8 or 21 days postoperatively. Both 8 and 21 days of treatment with ibuprofen following THA effectively prevents clinically significant degrees of HO. No serious short-term complications of the treatment were noted.

Heterotopic new bone formation causes resorption of the inductive bone matrix.

The bone matrix of growing rats was labeled by multiple injections of 3H-proline, and demineralized bone matrix (DBM) was prepared. The DBM was allotransplanted heterotopically into growing rats. New bone formation was induced in and around the implants. The new bone formation was accompanied by a decrease in the content of 3H; 20 and 30 days after implantation, 72% and 46%, respectively, of the activity remained in the implants. Daily injections of indomethacin (2 mg/kg) inhibited calcium uptake by about 20% at 20 and 30 days and inhibited the release of 3H from the DBM to a similar degree. Heterotopic bone induction by DBM is accompanied by matrix resorption, and inhibition of the new bone formation decreases the resorption of DBM.

Nonsteroid anti-inflammatory drugs prevent the recurrence of heterotopic ossification after excision.

The prophylactic effect of nonsteroid anti-inflammatory drugs on the recurrence of high-grade periarticular heterotopic ossification after resection was studied in ten patients operated on for loosening of one or both components of a cemented total hip prosthesis. These drugs, given at a standard dosage for 1-3 weeks after surgery, prevented the recurrence of heterotopic ossification. In some patients the range of motion of their joint increased following surgery, while it remained unaffected in the majority. At follow-up 2-5 years after surgery, all patients walked well and there were no clinical or radiographs signs of loosening of the prosthetic components. It is concluded that treatment with NSAIDs following resection of periarticular heterotopic ossification prevents recurrence.

Tears of the medial meniscus associated with increased radionuclide activity of the proximal tibia. Report of three cases.

Three patients who presented with longstanding medial knee pain and normal radiographs had an isotope bone scan in an attempt to arrive at a diagnosis. In each case there was a well-defined area of increased uptake over the medial tibial condyle and arthroscopy subsequently revealed meniscal damage. After arthroscopic menisectomy each patient became asymptomatic and the bone scan returned to normal. We suggest that patients with incapacitating knee pain, normal radiographs and a positive bone scan undergo an arthroscopy even in the absence of clinical signs of meniscal damage.

Periarticular heterotopic ossification after total hip arthroplasty for primary coxarthrosis.

Periarticular heterotopic ossification (PHO) is a common roentgenographic finding, occurring in more than two-thirds of patients after total hip arthroplasty (THA) for coxarthrosis. In the present study, 56 patients treated with bilateral THA were analyzed to determine the correlation between heterotopic ossification on the two sides. A strong correlation was found between the grade of PHO on the two sides: patients who developed severe PHO after the first THA invariably developed considerable PHO after surgery on the other side. The incidence and grade of PHO were higher in men than in women.

Prevention of heterotopic ossification by nonsteroid antiinflammatory drugs after total hip arthroplasty.

The effect of three weeks of postoperative treatment with indomethacin or ibuprofen on the development of periarticular heterotopic ossification (PHO) after bilateral total hip arthroplasty (THA) was investigated. Widespread PHO did not occur in 31 patients who had been treated with indomethacin or ibuprofen after both operations. Thirty-eight patients had been treated after one but not the other THA. Widespread PHO occurred in 14 of 38 untreated THA, but was not found after THA on the treated side. These findings are indicative of an inhibitory effect of nonsteroid antiinflammatory drugs on the development of PHO, since the development of severe heterotopic ossification is strongly correlated between the two sides after bilateral THA.

Prevention of periarticular heterotopic ossification following total hip arthroplasty. Clinical experience with indomethacin and ibuprofen.

Prophylactic treatment with indomethacin or ibuprofen to prevent periarticular heterotopic ossification (PHO) was investigated in a consecutive series of 200 total hip replacements (THR) performed for primary coxarthrosis in 170 patients. No widespread PHO (grades III and IV) occurred in 166 THR treated with indomethacin or ibuprofen from the 1st to the 21st postoperative day. Only one patient exhibited moderate (grade-II) ossification. In contrast, the incidence of PHO grades III and IV was found to be high (23%) in the 35 THR for which the patients did not receive prophylaxis according to intention. It was concluded that 3 weeks' postoperative treatment with indomethacin or ibuprofen is sufficient to prevent the development of clinically significant heterotopic ossification.