PURPOSE To analyze the impact of different body mass index (BMI) as a surrogate marker for heterotopic ossification (HO) in patients who underwent surgical repair (SR) for displaced acetabular fractures (DAF) followed by radiation therapy (RT). METHODS AND MATERIALS This is a single-institution retrospective study of 395 patients. All patients underwent SR for DAF followed by RT ± indomethacin. All patients received postoperative RT, 7 Gy, within 72 h. The patients were separated into four groups based on their BMI:<18.5, 18.5-24.9, 25-29.9, and >30. The end point of this study was to evaluate the efficacy of RT ± indomethacin in preventing HO in patients with different BMI. RESULTS Analysis of BMI showed an increasing incidence of HO with increasing BMI:<18.5,(0%) 0/6 patients; 18.5-24.9 (6%), 6 of 105 patients developed HO; 25-29.9 (19%), 22 of 117;>30 (31%), 51 of 167. Chi-square and multivariate logistic regression analysis showed that the correlation between odds of HO and BMI is significant, p < 0.0001. As the BMI increased, the risk of HO and Brooker Classes 3, 4 HO increased. The risk of developing HO is 1.0× (10%) more likely among those with higher BMI compared with those with lower BMI. For a one-unit increase in BMI the log odds of HO increases by 1.0, 95% CI (1.06-1.14). Chi-square test shows no significant difference among all other factors and HO (e.g., indomethacin, race, gender). CONCLUSIONS Despite similar surgical treatment and prophylactic measures (RT ± indomethacin), the risk of HO appears to significantly increase in patients with higher BMI after DAF. Higher single-fraction doses or multiple fractions and/or combination therapy with nonsteroidal inflammatory drugs may be of greater benefit to these patients.

OBJECTIVE: To evaluate the in vivo therapeutic efficacy of N-iminoethyl-L-lysine (L-NIL), a selective inhibitor of inducible nitric oxide synthase (iNOS), on the progression of lesions in an experimental osteoarthritis (OA) dog model. The effect of L-NIL on metalloprotease activity, levels of interleukin-1beta (IL-1beta), prostaglandin E2 (PGE2), and nitrite/nitrate in synovial fluid was determined. METHODS: The OA model was created by sectioning the anterior cruciate ligament of the right stifle joint of mongrel dogs by a stab wound. Dogs were separated into experimental groups: Group 1 was made up of unoperated dogs that received no treatment, group 2 were operated dogs with no treatment, and group 3 were operated dogs that received oral L-NIL (10 mg/kg/twice daily) starting immediately after surgery. The OA dogs were killed at 10 weeks after surgery. RESULTS: Experiments showed that dog OA cartilage explants in culture produced an increased amount of NO (nitrite). Immunohistochemical study demonstrated that this was due to an increased level of iNOS in chondrocytes. OA dogs treated with L-NIL showed a reduction in the incidence of osteophytes compared with the untreated OA dogs (58% versus 92%) as well as in their size (mean +/- SEM 1.92 +/- 0.58 mm versus 5.08 +/- 0.66 mm). Macroscopically, L-NIL decreased the size of the cartilage lesions by approximately 50% both on condyles and plateaus. The histologic severity of both the cartilage lesions and synovial inflammation was significantly decreased in the L-NIL-treated dogs. Treatment with L-NIL also significantly decreased both collagenase and general metalloprotease activity in the cartilage and the levels of IL-1beta, PGE2, and nitrite/nitrate in synovial fluid. CONCLUSION: This study demonstrated the effectiveness of a selective inhibitor of iNOS, L-NIL, in attenuating the progression of experimental OA. The data suggest that L-NIL may act by reducing the activity of metalloproteases in cartilage and the production of IL-1beta by synovium, both of which are known to play a major role in the pathophysiology of OA structural changes.

Patients who had total hip arthroplasty were categorized according to the risk of development of ectopic bone. Radiation therapy was administered after operation to those considered to be at high risk of formation of ectopic bone. The dosage used was 2,000 rads given in ten fractions (875 rets). Forty-eight hips in forty-two patients were treated from 1970 to 1977. Massive formation of ectopic bone did not occur in any hip when the radiation was given relatively early after operation. Thus, we believe that radiation aids in the prevention of formation of ectopic bone. Radiation was found to be of doubtful value, however, hence the ectopic bone was visible on radiography.

Twenty-four patients were evaluated and diagnosed, between August 1975 and July 1989, as having probable osteoid-osteoma. Fifteen patients had operative treatment (twelve immediate and three delayed); all fifteen had complete relief of pain. The remaining nine patients were treated with non-steroidal anti-inflammatory medications; all nine had complete relief of pain, and six had resolution of the symptoms without using non-steroidal anti-inflammatory drugs, after an average of thirty-three months (range, thirty to forty months) of treatment. Thus, long-term administration of non-steroidal anti-inflammatory drugs can often be as effective as excision for the treatment of osteoid-osteoma, without the morbidity that is associated with the operation, especially in patients in whom operative treatment would be complex or might lead to disability.

The potential for regeneration and repair of bone is well known. This article conveys the current progress in the realm of bone morphogenetic proteins and their potential for initiating fracture repair cascade. Demineralized bone matrix induces bone formation and has served as a model for the bone repair cascade. A family of bone morphogenetic proteins has been identified, isolated, and cloned from the demineralized bone matrix. Bone morphogenetic proteins are pleiotropic regulators of chemotaxis, mitosis, and differentiation. The bone morphogenetic protein receptors, Types I and II, bind bone morphogenetic proteins and act in collaboration to transduce the phosphorylation of Smad 1 and Smad 5, which enter the nucleus in partnership with Smad 4 to initiate bone morphogenetic protein responses including fracture healing. The accumulated information on bone morphogenetic proteins may aid in accelerating fracture repair and the potential use of bone morphogenetic protein antibodies to inhibit heterotopic bone formation and fibrodysplasia ossificans progressiva.

We studied the effect of indomethacin on the prevention of formation of heterotopic bone after total hip replacement. In a randomized, double-blind clinical trial involving 201 patients, 102 patients received twenty-five milligrams of indomethacin three times daily for the first six postoperative weeks, and the other ninety-nine patients received a placebo. One year after the operation, eighty-nine of those who had received indomethacin had no sign of heterotopic ossification, and the remaining thirteen had a grade-I lesion. In the group that had received a placebo, twenty-seven had no heterotopic ossification; twenty-four, a grade-I lesion; thirty, a grade-II lesion; and eighteen, a grade-III lesion. Significantly fewer patients who had received indomethacin had formation of heterotopic bone compared with those who had been given a placebo (chi-square test, p less than 0.0005). Only patients who had grade-III formation of heterotopic bone had a significant reduction in movement of the hip.

A prospective study was done to evaluate the efficacy of treatment with 1,000 rads of radiation in the prevention of heterotopic ossification after total hip arthroplasty in patients who are at high risk. In a previous prospective study, patients who were at high risk for heterotopic ossification after total hip arthroplasty were identified and an effective regimen for its prevention was established. It was demonstrated that treatment with 2,000 rads of radiation that was initiated within four days after the total hip arthroplasty was highly effective in the prevention of heterotopic ossification and in the prevention of recurrence after resection of existing ossification. In the present study, 1,000 rads of radiation was administered in increments of 200 rads over a period of five to seven days and was as effective as treatment with 2,000 rads. The protocol of 1,000 rads is preferable because it reduces the risk of malignancy and the duration of hospitalization.

We evaluated the results in 177 patients with 200 total hip arthroplasties that had been performed for primary osteoarthritis. Severe postoperative heterotopic-bone formation (grades III and IV according to the classification of Brooker et al.) was found in thirty-six hips (18 per cent). The incidence of heterotopic bone formation was found to be slightly higher in the patients who had received diphosphonate than in the control group of patients who had received either a placebo or no drug therapy. The postoperative range of motion of the hips as well as ratings for pain, walking, and function did not differ significantly between the treated and untreated groups. The results of this study were consistent with those of previously published reports that demonstrated that while diphosphonates did not prevent heterotopic bone formation in laboratory animals they did result in a delay of mineralization of osteoid. This delay did not, as was hoped, significantly improve the range of motion of the involved hips in our series.

BACKGROUND Calcific aortic valve disease is the most common indication for surgical valve replacement in the United States. The cellular mechanisms of valve calcification are not well understood. We have previously shown that cellular proliferation and osteoblastogenesis are important in the development of valvular heart disease. Lrp5, a known low-density receptor-related protein, plays an essential role in cellular proliferation and osteoblastogenesis via the beta-catenin signaling pathway. We hypothesize that Lrp5 also plays a role in aortic valve (AV) calcification in experimental hypercholesterolemia. METHODS AND RESULTS We examined the effects of cholesterol and atorvastatin in Watanabe rabbits (n=54). Group I (n=18) received a normal diet, group II (n=18) a 0.25% cholesterol diet, and group III (n=18) a 0.25%(w/w) cholesterol diet with atorvastatin for the development of calcification. The AVs were examined for cellular proliferation, Lrp5/beta-catenin, and bone matrix markers. Bone formation was assessed by micro-computed tomography, calcein injection, and osteopontin expression. Low-density lipoprotein with and without atorvastatin was also tested in AV myofibroblasts for cellular proliferation and regulation of the Lrp5/beta-catenin pathway. Our results demonstrate that the cholesterol diet induced complex bone formations in the calcified AVs with an increase in the Lrp5 receptors, osteopontin, and p42/44 expression. Atorvastatin reduced bone formation, cellular proliferation, and Lrp5/beta-catenin protein levels in the AVs. In vitro analysis confirmed the Lrp5/beta-catenin expression in myofibroblast cell proliferation. CONCLUSIONS Hypercholesterolemic AV calcification is attenuated by atorvastatin and is mediated in part by the Lrp5/beta-catenin pathway. This developmental pathway may be important in the signaling pathway of this disease.

In a retrospective review of thirty-seven patients who had operative treatment for thirty-eight complex acetabular fractures, postoperative low-dose irradiation was administered to seventeen patients (eighteen fractures) to suppress heterotopic ossification. All of the patients had been operated on through either an extended iliofemoral incision or a modified extended iliofemoral incision. The prophylactic radiation was administered using a low-dose protocol; most of the patients received 1,000 rads in 200-rad increments, starting on the third post-operative day. The incidence of heterotopic ossification in the eighteen irradiated limbs was much lower than in the twenty patients who comprised the control group (50 per cent compared with 90 per cent). Only two of the irradiated limbs had Class-3 heterotopic ossification as described by Brooker et al., and no patient had Class-4 (ankylosis of the hip). Of the twenty control-group patients, ten had severe heterotopic ossification: Class 3 in seven and Class 4 in three. The difference in the incidence of severe (Class-3 or 4) heterotopic ossification between the two groups of patients was significant (p less than 0.01).

Sixty-two hips in fifty-five patients who were considered to be at risk for postoperative heterotopic ossification were randomly divided into two groups: one received a single 800-centigray dose of limited-field radiation and the other, 1000 centigray of limited-field radiation in divided doses. The risk for heterotopic-bone formation was identified on the basis of previously described criteria, which included previous heterotopic ossification after an operation about the hip, hypertrophic osteoarthritis or post-traumatic osteoarthrosis characterized by formation of extensive osteophytes, radiographic evidence of diffuse idiopathic skeletal hyperostosis, ankylosing spondylitis, and male sex. The treatment portals excluded prosthetic surfaces that were intended for biological fixation by ingrowth of bone. At a minimum six-month follow-up, progression of heterotopic ossification had occurred in seven (21 per cent) of thirty-four hips in the first group and in six (21 per cent) of twenty-eight hips in the second group. The ossification had advanced more than one grade in only one hip. Extra-field ossification occurred in fifteen (43 per cent) of thirty-five hips that had not had previous heterotopic ossification. Since the time of the study, the treatment portal has been modified to include the lateral aspect of the greater trochanter, so that the risk of bursitis associated with ossification in this area is minimized. Single-dose limited-field radiation is effective for the prevention of heterotopic ossification, without compromise of early fixation of an uncemented implant.