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[Prevention of heterotopic ossifications in hip arthroplasty: effectiveness of selective Cox-2 inhibitors (celecoxib) versus ketoprofen].

PURPOSE OF THE STUDY: Peri-prosthetic ossifications are a frequent complication of total hip arthroplasty, which, if effective preventive measures are not taken, occur in 60% of patients. Numerous classic antiinflammatory agents have shown their preventive efficacy. New selective Cox-2 inhibitors offer the possibility of reducing the adverse effects of antiinflammatory drugs but remain to be proven effective in this indication. The purpose of this pilot study was to compare the efficacy of celecoxib versus ketoprofen. MATERIAL AND METHODS: In order to obtain sufficient statistical power to have a 70% chance of detecting a 25% difference between the two treatments with a 5% risk of error, we evaluated the incidence of peri-prosthetic ossifications of the hip in a prospective monocentric series of 52 patients receiving 400 mg celecoxib a day during a week. It was compared with the incidence in a control series of 52 matched patients (same age, gender, diagnosis, operator experience) given 200 mg ketoprofen iv for 48 hr then 300 mg po for 5 days as preventive treatment. Ossifications were studied on the plain AP view of the pelvis at a mean follow-up of more than 11 months (11.4 vs 11.9). The Brooker classification was determined. RESULTS: The percent of patients presenting peri-prosthetic ossifications was equivalent. For the celecoxib group, 60% of the patients were free of ossifications; 28.9% presented stage 1 ossification and 11.1% stage 2 ossification; none of the hip exhibited a higher stage. In the ketoprofen control group, 53.2% of patients were free of ossification, 38.2% had stage 1 ossification, 6.4% stage 2, and 2.1% stage 3; there was no patient with stage 4. Fisher's exact test did not demonstrate a significant difference between the groups (p<0.51). Compared with an older series of patients who were not given preventive treatment, there was a significant reduction in incidence of peri-prosthetic ossification (p=0.014). DISCUSSION: The two study groups were not significantly different for age, gender, or underlying disease. There were an equivalent number of cases of intolerance to treatment in the two groups. CONCLUSION: These findings appear to indicate an equivalent efficacy for celecoxib and ketoprofen for the reduction of peri-prosthetic ossifications. Based on these results, a randomized prospective comparative study can be undertaken without risk of losing effective prevention in one group. This prospective study should enable a more precise evaluation of treatment equivalence and quantify any potential gain in morbidity obtained with celecoxib.

Aged↗

Bone mineral density in patients with ossification of the posterior longitudinal ligament. Minimal decrease of bone mineral density with aging.

STUDY DESIGN: Bone mineral density of individuals with ossification of the posterior longitudinal ligament and that of normal people was determined by dual-energy x-ray absorptiometry. OBJECTIVES: To determine whether bone mineral density in the people with ossification of the posterior longitudinal ligament is higher than that in normal individuals even in body parts other than the spine, and to evaluate the relation between bone mineral density and age in patients with ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: It is unknown whether the bone mineral density of patients with ossification of the posterior longitudinal ligament is greater in body parts other than the spine. If so, it provides a basis for the theory that certain systemic factors are involved in the pathogenesis of ossification of the posterior longitudinal ligament. Because bone mineral density decreases physiologically after middle age, the influence of age must be considered in evaluating bone mineral density. METHODS: In the rib area and upper and lower limb areas, which are not affected by ossification of the spinal ligament, bone mineral density of 45 men with ossification of the posterior longitudinal ligament of the cervical spine was compared with that of 25 men without ossification of the posterior longitudinal ligament (normal group). RESULTS: Bone mineral density was higher in the group with ossification of the posterior longitudinal ligament in each part and significantly higher in the rib and lower limb areas (rib: P < 0.01, lower limb: P < 0.05). The age-related decrease was significantly less in the group with ossification of the posterior longitudinal ligament (rib: P < 0.01, upper limb: P < 0.05, lower limb: P < 0.01). CONCLUSIONS: Systemic factors that increase bone mineral density appear to be involved in the pathogenesis of ossification of the posterior longitudinal ligament, and these factors may be activated after middle age.

Absorptiometry, Photon↗

Variation in the ossification process of the anconeal and medial coronoid processes of the canine ulna.

This morphological and radiographic study investigates the ossification process of the anconeal and medial coronoid processes of the ulna in a sample of 142 dogs ranging in age from neonatal to 44 weeks. The anconeal process was noted to develop by appositional ossification, formation of a separate ossification center, or a combination of both. Several developmental stages of the ossification center of the anconeal process as well as its anatomic position and radiographic appearance are described. Differences have been noted in the shape of this ossification center as well as the ossification process itself. The medial coronoid process develops exclusively by appositional ossification. Unlike ossification of the anconeal process, ossification of the medial coronoid process was completed earlier (p < 0.05) in smaller than in the larger dogs. In smaller dogs, both the medial coronoid and anconeal processes were found to be mature by the age of 16 weeks. In the larger dogs, ossification of the anconeal process was completed not before 14 weeks of age and ossification of the medial coronoid process was completed about 6 weeks later.

Animals↗

The development of centres of ossification of bones forming elbow joints in young swine.

Epiphyseal centres of ossification in the bones forming the elbow joints of pigs between one day and 15 weeks of age were examined radiographically, macroscopically, mesoscopically and microscopically. Thoracic limbs from 39 pigs were perfused with India ink or silicone rubber injection compound and the bones were dissected free of soft tissues. The humerus, ulna and radius were fixed in formalin or ethyl alcohol and then cleared by the modified Spalteholz technique. Bones were radiographed, examined grossly, and then cut into slabs for mesoscopical evaluation. Foci considered to be calcifying within cartilaginous anlage were selected for microscopical examination. It was concluded that the epiphyseal centre of ossification develops at different times in different sites in the bones forming the elbow joint. Centres of ossification are initiated when foci of chondrocytes adjacent to one side of a cartilage canal undergo hypertrophy and the inter-territorial matrix becomes calcified. Osteogenesis then proceeds in the calcified focus, presumably with osteoprogenitor cells that originate within the cartilage canals. Subsequently, each epiphyseal centre of ossification enlarges by one of two methods. Firstly, the layer of cartilage adjacent to the centre undergoes endochondral ossification, thus allowing for the circumferential growth of the epiphyseal centre of ossification. Secondly, foci of calcification develop adjacent to the ends of cartilage canals near the epiphyseal centre of ossification and eventually the focus of calcification coalesces with the developing epiphyseal centre of ossification, thus establishing a new ossification front. Endochondral ossification continues at the periphery of the mass of bone. Mesoscopical examination is more useful than radiographical evaluation for identifying small foci of calcification which precede epiphyseal centres of ossification.

Animals↗

Long term follow-up of diffuse idiopathic skeletal hyperostosis in the cervical spine. Analysis of progression of ossification.

In eleven patients with diffuse idiopathic skeletal hyperostosis who presented with extensive ossification in the cervical spine, progression or regression of ossification during the follow-up period were measured in extent and thickness radiographically. Intervertebral range of motion was also measured and the relation between changes of ossification and intervertebral mobility was analyzed. The range of motion at the segments at which ossification progressed was statistically quite different from those at which no progression was observed. It was found that ossification grew in thickness at mobile segments and no growth of ossification was present at immobile segments. Dysphagia caused by massive ossification was cured by surgical removal in two cases. Recurrent ossifications were detected in them some years after surgery, and one of them complained of dysphagia again. To prevent recurrent ossification and dysphagia, it was considered that immobilization of the concerned segment was necessary by bone grafting or preservation of the continuity of ossification.

Aged↗

[Prevention of para-articular ossifications by radiotherapy after cementless total hip endoprosthesis implantation].

By means of a prospective study, concerning the postoperative rate of ossification after cementless total hip replacement, it was due to prove the efficacy of radiotherapy in preventing periarticular ossification. In 1992 arthroplasty was followed by radiotherapy of 50 hip joints as regular therapy. The radiation was performed with a focal dose of 8 Gy. Patients with bilateral cementless total hip replacement and radiotherapy only at one side were of special interest in this study. Within the 24th postoperative week in 28 (56%) of the radiated hip joins no periarticular ossifications were found. In 20 (40%) we found ossifications grade 1, in 1 case ossification grade II and in 1 further case ossification grade III following the classification of Arcq. By 8 patients with former cementless total hip replacement without postoperative radiotherapy, a significant reduction of the ossification rate was found in the contralateral hip joint treated by postoperative radiotherapy. The rate of ossification was reduced by 28%. In correlation to reduction of periarticular ossification the increase on the overall range of motion in the radiated hip joins was 10.9%. By none of the patients treated by radiotherapy we found a disturbed healing process, a deep infection or an early loosening of the endoprosthesis. Postoperative radiotherapy as regular therapy for prophylaxis of periarticular ossification after Cementless total hip replacement can subsequently be recommended.

Adult↗

Response of peripheral lymphocytes from patients with ossification of posterior longitudinal ligament.

The in vitro response of peripheral blood mononuclear cells or enriched CD4+ T cells from patients with ossification of the posterior longitudinal ligament to anti-CD3 monoclonal antibody has been studied. The response in both was significantly lower in patients with the continuous-type ossification than in patients with the segmental-type ossification and in healthy volunteers, and was inversely correlated with the number of vertebral bodies with ossified ligament. In patients with the segmental-type ossification, the response of peripheral blood mononuclear cells was significantly lower than that in healthy volunteers, but that of the enriched T cells was not. B cell proliferation in response to fixed Staphylococcus aureus cells was significantly lower in patients with the continuous-type ossification than in healthy volunteers but was not correlated with the number of vertebral bodies with ossified ligament. The B cell response in patients with the segmental-type ossification was not lower than that in healthy volunteers. Serum concentrations of transforming growth factor-beta1 and basic fibroblast growth factor also were higher in patients with the continuous-type ossification than in patients with the segmental-type ossification and in healthy volunteers. The findings raise the possibility that continuous-type ossification of posterior longitudinal ligament might develop differently from segmental-type ossification.

Aged↗

Ultrastructural observations on the ossification of the supraspinous ligament.

STUDY DESIGN: This study analyzed the process of ossification of spinal ligaments. Supraspinous ligaments excised during surgery were studied by light and scanning electron microscopy. OBJECTIVES: The results were correlated to determine the mechanism of ossification of spinal ligaments. SUMMARY OF BACKGROUND DATA: Ossification of the ligamentum flavum has been described in detail by Hiraoka, Yamaguchi, and others. However, the pathogenesis of ossification of the spinal ligaments remains unclear. Some studies have been performed by light and transmission electron microscopy, but no detailed investigation of the ossification of the spinal ligaments by scanning electron microscopy has been performed. METHODS: Specimens of supraspinous ligament were taken from 41 patients during spinal surgery. Ossification was diagnosed macroscopically and radiologically for 20 patients. The specimens were examined using light and scanning electron microscopy. RESULTS: Collagen fibrils were 700-2000 A in diameter and were arranged in parallel. The ligament insertion divided into four zones and seemed to fit the description of Enthesis histologically. Close to the ossification region, there were a region in which some fibrils were thinner and branchings became slightly stronger, tending to form bridges of minute fibrils between other fibrils. Closer to the region of actual ossification, there was a region in which extra-fibrillar substances completely deposited. In the region of actual ossification, there were medullary spaces of varying sizes, and the surrounding collagen fibers were dense and arranged in a lamellar fashion. Osteocyte lacunae had formed and the cells regarded to be the osteocytes were present on the inside. CONCLUSION: Ossification of the supraspinous ligament possibly occurs as follows. Fibroblasts or chondrocyte-like cells respond to some external stimulus, form an irregular network of fine fibrils, and produce acid mucopolysaccharide. These undergo calcification and capillary invasion. Undifferentiated mesenchymal cells invaded and are transformed into osteoblasts. Then osteogenesis ensues with progressive calcification.

Adolescent↗

Effects of strain distribution in the intervertebral discs on the progression of ossification of the posterior longitudinal ligaments.

STUDY DESIGN: Strain distribution in the intervertebral discs was evaluated biomechanically using an engineering true strain calculation formula. OBJECTIVES: This study was performed to clarify the involvement of dynamic factors in the progression of ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: In patients with ossification of the posterior longitudinal ligament of the cervical spine, ossification frequently progresses after laminectomy. This suggests the involvement of dynamic factors in the progression of ossification. However, these factors have not yet been clarified. METHODS: The analysis was performed on 101 patients with ossification of the posterior longitudinal ligament by employing dynamic lateral x-ray films of the cervical spine. The x-ray films were digitized and used as computer data for calculating the strain distribution. X-ray films were obtained again 5 years later, and the strain distribution and the presence or absence of progression of ossification were evaluated. RESULTS: The progression of ossification of the posterior longitudinal ligament was highly correlated with abnormal strain distribution in the intervertebral discs. Progression of ossification was frequently observed in areas having disc distortion in tension and extension on the posterior longitudinal ligament. CONCLUSIONS: In this study, the area of progression of ossification corresponded to the area showing uneven strain distribution and resultant concentration of dynamic stress. These results suggest an important role for dynamic factors in the progression of ossification of the posterior longitudinal ligament.

Adult↗

Radiculopathy due to ossification of the yellow ligament at the lower lumbar spine.

STUDY DESIGN: A case report. OBJECTIVES: To report a rare case of a 27-year-old female with ossification of yellow ligament at the lower lumbar spine presenting radiculopathy with a drop foot. SUMMARY OF BACKGROUND DATA: The majority of cases of ossification of yellow ligament occur at the lower third of the thoracic or the thoracolumbar spine. There are only a few reports of ossification of yellow ligament in the lumbar spine and radiculopathy due to ossification of yellow ligament at L4-L5 and L5-S1 levels is very uncommon. METHODS: A 27-year-old female with a prior fracture of posterior ring apophysis of L5 presented with leg pain and a drop foot. Magnetic resonance imaging demonstrated stenosis with compression of the cauda equina at the L4-L5 and L5-S1 levels. RESULTS: Decompressive laminectomy of L5 and removal of the ossified yellow ligaments were performed. Histologic examination of en bloc specimen of ossification of yellow ligament revealed degenerative changes of the elastic fibers in the yellow ligament with adjacent chondrosis and ossification. The patient's severe leg pain disappeared completely, although the extent of the drop foot had not fully recovered at the final follow-up examination. CONCLUSIONS: The mechanism of ossification of yellow ligament in the present case was unclear. The patient did not have any previous generalized disorders besides the history of a ring apophysial fracture or any family history of treatment for ossification of the posterior longitudinal ligament or ossification of yellow ligament. Therefore, localized mechanical stress might have influenced the development of ossification of yellow ligament at lower lumbar spine.

Adult↗

Development of adjacent-level ossification in patients with an anterior cervical plate.

BACKGROUND: It has been our experience that ossification occurs adjacent to anterior cervical plates. Our hypothesis was that the closer the plate is to the adjacent disc space, the greater the ossification. METHODS: We retrospectively reviewed the lateral radiographs of the cervical spine of 118 patients who had a solid fusion following an anterior cervical arthrodesis with a plate for the treatment of a degenerative cervical condition; none of the patients had had cervical spine surgery prior to the index arthrodesis. The plate-to-disc distance was measured on the postoperative lateral radiograph and was used to divide the patients into two groups for each of the two adjacent disc spaces. In group A the plate-to-disc distance was <5 mm, and in group B it was >/=5 mm. The mean duration of follow-up was 25.7 months. The severity of the ossification at the two adjacent disc spaces was classified on a scale ranging from grade 0 (no ossification) to grade 3 (complete bridging). Eighteen patients were excluded from the measurement of the severity of the caudal ossification because overlapping by the bone of the shoulder precluded adequate visualization of the caudal level. RESULTS: Ossification developed in seventy (59%) of the 118 cephalad adjacent disc spaces and twenty-nine (29%) of the 100 caudal adjacent disc spaces (p < 0.001). The mean cephalad plate-to-disc distance was shorter than the mean caudal plate-to-disc distance (p < 0.001). The rate of ossification was higher in group A than in group B, both at the cephalad adjacent disc spaces (67% compared with 24%) and at the caudal adjacent disc spaces (45% compared with 5%) (both p < 0.001). In addition, 93% (twenty-six) of the twenty-eight cases of moderate-to-severe ossification developed in group A. CONCLUSIONS: We found a positive association between adjacent-level ossification following anterior cervical plate procedures and the plate-to-disc distance. We now strive to place anterior cervical plates at least 5 mm away from the adjacent disc spaces in order to decrease the likelihood of moderate-to-severe adjacent-level ossification.

Adult↗

Mechanobiology and joint conformity regulate endochondral ossification of sesamoids.

Sesamoid bones form by the endochondral ossification of sesamoid cartilages. This ossification process is thought to be similar to that responsible for the formation of secondary ossific nuclei in long-bone epiphyses. Sesamoids ossify much later in development than do epiphyses, however, and bone formation within sesamoids often begins by way of multiple ossific nuclei. Endochondral growth and ossification in the formation of secondary ossific nuclei have previously been correlated with distributions of the octahedral shear and hydrostatic stresses generated in vivo within cartilage anlagen. In this study, we used two-dimensional finite element analysis to predict the distributions of octahedral shear and hydrostatic stresses in an idealized model of a sesamoid cartilage subjected to in vivo loading. We examined the influence of sesamoid joint conformity. The distribution of an osteogenic stimulus was calculated with an approach similar to that used to predict epiphyseal ossification. The results suggest that, compared with conforming joints, nonconformity between the sesamoid cartilage and its articulating surface, which arises during early development, produces higher contact pressures within the sesamoid and leads to a thicker articular cartilage layer. For a nonconforming joint surface, the results suggest that ossification is favored anywhere within a broad internal region of the sesamoid, whereas a layer at the articular surface will remain cartilaginous. These findings highlight the subtle differences between ossification processes in epiphyses and sesamoids, indicating that the mechanical stress environment in sesamoids produces a diffuse stimulus leading to the onset of ossification and that the degree of joint nonconformity may influence the thickness of the articular cartilage layer.

Cartilage↗

Ossification sequence in infants who die during the perinatal period: population-based references.

PURPOSE: To determine population-based references for the relationships between the presence of ossification centers and gestational age and skeletal length measurements among infants who die during the perinatal period, as well as to evaluate the possible influence of intrauterine growth restriction on ossification stage. MATERIALS AND METHODS: During an 11-year period, nearly all infants who died perinatally in a well-defined geographic area routinely underwent radiography with a standardized technique. The presence of visible secondary ossification centers in the singletons (n = 495) was evaluated. Cluster analysis was used to identify stages of ossification; a sequential appearance of secondary ossification centers was assumed. Comparisons were made with Wilks lambda between male and female infants and between infants who were presumed to have growth restriction and those who were not. Reference ranges for the presence of ossification centers were calculated for interquartile ranges of femur length and gestational age. RESULTS: Eight clusters of ossification defining different stages of ossification of the pelvis, hindfeet, and knees were identified. The sequential clusters outlined well-defined intervals of femur length and gestational age. Bone lengths, birth weight, and gestational age within ossification clusters did not differ between the sexes (Wilks lambda = 0.989, P =.532) or according to whether growth restriction was presumed to exist (Wilks lambda = 0.958, P =.481). CONCLUSION: The reference diagrams calculated with this method indicate relationships between ossification sequence and both gestational age and skeletal length measurements.

Birth Weight↗

Fetal ossification centers as predictors of gestational age in normal and abnormal pregnancies.

The main fetal ossification centers appear ultrasonically as egg-shaped echo-rich areas. The calcaneal and talar ossification centers are seen at the level of the tarsus osseus, and the distal femoral epiphyseal and proximal tibial epiphyseal ossification centers are found at the level of the knee. Examination of 312 normal pregnancies between 20 and 40 weeks of gestation showed that the calcaneal ossification center was detectable for 24 weeks of gestation, the talar ossification center from 26 weeks, and the distal femoral epiphyseal and proximal tibial epiphyseal ossification centers, from 32 and 36 weeks, respectively. Corresponding figures found for 36 pregnancies showing intrauterine growth retardation (IUGR), examined between 34 and 40 weeks of gestation, were similar for the calcaneal and talar ossification centers but showed delays in the development of the epiphyseal ossification centers, which were particularly striking in cases of symmetrical IUGR. The amniotic fluid lecithin/sphingomyelin ratio was also evaluated in 51 normal pregnancies between 31 and 38 weeks of gestation and was found to be greater than or equal to 2 in every case where the distal femoral epiphyseal ossification center was greater than or equal to 6 mm in diameter. Evaluation of fetal ossification centers may be another useful means to evaluate gestational age in late pregnancy

Calcaneus↗

C-reactive protein as an early indicator of the formation of heterotopic ossifications after total hip replacement.

The formation of heterotopic ossifications after total hip endoprosthesis implantation is a well-known complication. During the postoperative course laboratory parameters are subject to partial change due to the development of heterotopic ossifications. However, these changes occur relatively late at a time when the application of prophylactic precautions is usually already decided. Any meaningful prophylactic treatment, however, has to be initiated immediately after surgery. In a prospective study we assessed the postoperative C-reactive protein (CRP) levels in 95 patients twice after total hip replacement surgery. The initial assessment took place on the 1st day following surgery and again between the 5th and 7th day. All patients received three doses of 50 mg diclofenac daily for 7 days starting on the 1st postoperative day. Average CRP values on the 1st postoperative day were 6.33 +/- 2.28 mg/dl for ossification grade Brooker 0, 7.04 +/- 1.8 mg/l for Brooker 1 and 7.65 +/- 3.7 mg/dl for Brooker grades 2-4. At the time of the second CRP assessment (postoperative day 5-7), CRP values in the groups of patients showing ossifications were higher. Whereas patients without ossifications (A) exhibited an average level of 4.22 +/- 3.13 mg/dl, in patients with ossification grade 1 (B) CRP was 5.57 +/- 2.78 mg/dl and in the group with ossification grades 2-4 (C) was 6.38 +/- 4.48 mg/dl. The differences between group A on the one hand and the combined groups B and C values on the other were significant (P = 0.036). We are able to assert that after total hip replacement, significantly higher CRP levels can be recorded immediately after surgery in those patients who will eventually develop heterotopic ossifications, as compared with those who do not. Hence, the postoperative rise of CRP levels should be introduced as a further risk factor for the formation of heterotopic ossifications since its recording at such an early stage still allows for the timely initiation of prophylactic treatment.

Anti-Inflammatory Agents, Non-Steroidal↗

The role of post-operative radiation in the prevention of heterotopic ossification in patients with post-traumatic acetabular fracture.

Heterotopic ossification (HO) with subsequent pain and limitation of motion of the lower extremity is a common and significant problem for patients who suffer traumatic acetabular fracture (TAF). The incidence of heterotopic ossification is markedly increased for patients requiring surgical repair depending on the degree of trauma and the type of surgical repair necessary. Radiation therapy (RT) has proven to be the most effective surgical adjunct for the prevention of heterotopic ossification in patients undergoing total hip replacement (THR), but has not been reported in patients with traumatic fracture and repair. This report details an experience with patients treated at a Shock Trauma Center with extensile repair and immediate (within 48 hr) post-operative radiation therapy given as 5 daily fractions of 2 Gy in 5 to 7 days to a total dose of 10 Gy using megavoltage radiation therapy. A total of 30 consecutive patients (RT group) have been treated at our institution since June 1985. The last 20 patients treated with surgery only (non-RT group) prior to initiation of this study were used as a control group. Heterotopic ossification was seen to some degree in 50% of all radiation therapy patients, but was severe in only three of 30 (10%) of cases [three (10%) had Brooker III HO and no patients had ankylosis (Brooker IV HO)]. In contrast, some degree of heterotopic ossification was seen in 90% of the non-radiation therapy patients, and was severe in 10 of 20 (50%) of patients [seven (35%) had Brooker III HO whereas three (15%) had ankylosis (Brooker IV)]. This difference is significant for both total incidence and incidence of severe cases (p less than 0.01). This reduction in heterotopic ossification incidence approaches the magnitude reported for high-risk patients with total hip replacement. Even though the incidence of severe heterotopic ossification after radiation therapy for total hip replacement is approximately 5% and for traumatic acetabular fracture patients it is double (10%), the actual incidence of heterotopic ossification without radiation therapy is different in the two conditions. For total hip replacement, the incidence is about 30% and for traumatic acetabular fracture it is 50%. Radiation therapy has again proven itself to be an excellent surgical adjunct to prevent heterotopic ossification, this time in traumatic acetabular fracture patients.

Acetabulum↗

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.

PURPOSE: Previous studies showed the effectiveness of early preoperative (4 h before operation) irradiation for prevention of heterotopic ossification (HO) after total hip replacement. This procedure can result in logistic problems, if there is a great distance between the department of radiotherapy and the orthopedic clinic. To avoid these organizational problems a prospective study was undertaken to analyze the effectiveness of preoperative irradiation on the day preceding surgery (16-20 h before operation). METHODS AND MATERIALS: Between 1995 and 1996, 100 patients were randomized to receive a prophylactic therapy for prevention of heterotopic ossification. Forty-six patients were irradiated with 7 Gy single dose within 16-20 h before operation. Fifty-four patients were treated with nonsteroidal anti-inflammatory drugs (NSAID) (Voltaren resinat 2 x 75 mg/day for 2 weeks). Heterotopic ossification was scored according to the Brooker Grading system. One hundred patients receiving no prophylactic therapy after total hip arthroplasty between 1988 and 1992 were analyzed and defined as the historical control group. RESULTS: Incidence of heterotopic ossification was 47.8% in the 7 Gy preoperative group (Brooker Score I: 36.9%; II: 8.7%; III: 2.2%; IV: 0%) and 11.1% in the NSAID group (Brooker Score I: 9.3%; II: 1.8%; III: 0%; IV: 0%). Regarding overall heterotopic ossification there was a significant difference between the NSAID group and the 7 Gy group (p < 0.01). Analyzing the clinically significant heterotopic ossification (Brooker Score III and IV) there was no significant difference between the two treatment arms (p > 0.05). In the untreated historical control group the incidence of heterotopic ossification was 65% (Brooker Score I: 26%; II: 15%; III: 19%; IV: 5%). Referring to overall and to clinically relevant heterotopic ossification the incidence of HO was greater in the control group than in the prophylactically treated groups (p < 0.05). CONCLUSION: Irradiation within 16-20 h before operation and use of NSAID (Voltaren resinat) can reduce the incidence of clinically relevant heterotopic ossification after total hip replacement.

Aged↗

Heterotopic ossification after revision total knee arthroplasty.

A consecutive series of revision total knee arthroplasties done at two centers was evaluated for the presence of heterotopic ossification on radiographs taken before and after revision using the classification system of Harwin et al. Knee Society scores were obtained preoperatively and at annual intervals postoperatively. The patients' demographics and clinical scores were correlated with the incidence and grade of heterotopic ossification. Minimum 2-year followup was obtained in 135 of 151 patients who had revision total knee arthroplasty during this period (89%). The incidence of heterotopic ossification before revision surgery was 23%, which increased to 56% at most recent followup (mean, 30 months; range, 24-48 months). The only risk factor identified for the development of heterotopic ossification was the presence of infection (76%), which was significantly higher than the 47% incidence of heterotopic ossification in patients who did not have an infection. The average postoperative Knee Society score was lower in patients with heterotopic ossification compared with patients without heterotopic ossification (129 points versus 148 points). Patients with heterotopic ossification had significantly lower functional scores particularly on stair climbing but did not have a significantly decreased range of motion. Parameters not associated with subsequent development of heterotopic ossification included gender (males), patient size (body mass index), surgical time, operative approach, or number of prior knee procedures.

Arthroplasty, Replacement, Knee↗