Shielding of the hip prosthesis during radiation therapy for heterotopic ossification is associated with increased failure of prophylaxis

Low-dose Preoperative Unshielded Radiation Is Effective in Heterotopic Ossification Prophylaxis and Does Not Affect Porous Fixation in Total Hip Arthroplasty at 2 Years Minimum Follow-up: A Radiographic Study

BACKGROUND

Heterotopic ossification (HO) is a frequent complication of total hip arthroplasty (THA). HO can cause pain, limitation of range of motion, and instability. Radiation therapy (RT) for HO prophylaxis is well established but may interfere with early porous ingrowth and pullout strength of implants, as suggested by two animal studies. Although shielding of the bone from irradiation may theoretically protect ingrowth, it has been found to reduce RT effectiveness. Despite the popularity of porous implants in THA, the frequency of HO, and use of RT in its prophylaxis, the effect of RT on porous implant fixation in THA has not been previously reported. At our institution, we use unshielded, single-dose, preoperative 700 to 800 centigrays RT for HO prophylaxis in high-risk patients. We hypothesize that this RT protocol is effective and the press-fit technique protects porous implants during early ingrowth; therefore, long-term implant fixation is not compromised.

METHODS

This was a retrospective study aiming to determine fixation of porous THA implants, healing of trochanteric osteotomies, and efficacy of HO prophylaxis with this RT protocol.

RESULTS

Thirty-nine patients with follow-up of 24 to 144 months (average 59.7 months) were included. All 26 porous-coated femoral implants (11 revisions and 15 primary) were well fixed. There were 33 porous-coated acetabular implants (18 revisions and 15 primary). Thirty (91%) were well fixed, and three revision implants (9%) demonstrated radiolucent lines in two zones, but patients were clinically asymptomatic. All nine trochanteric osteotomies healed uneventfully. RT provided effective HO prophylaxis in 33 of 39 hips (85%).

CONCLUSIONS

Single, low-dose, preoperative RT without shielding does not increase aseptic loosening of porous implants manufactured with plasma porous spray or nonunion of extended trochanteric osteotomies. This protocol provides effective HO prophylaxis in high-risk patients undergoing primary and revision THA.

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

Numerous nonmalignant diseases can be treated with radiation therapy (RT). Among them, Heterotopic Ossification (HO) is a benign condition resulting from several causes that can be successfully managed with ionizing radiation. More often seen in the hip area after major surgical procedures, HO is of major concern as it can lead to functional disorders, pain and even to joint ankylosis. We retrospectively analyzed the outcome of therapeutic irradiation for the prevention of HO in 14 patients treated in our hospital between 2005 and 2011. All patients were irradiated with a dose ranging from 7 to10 Gy in a single fraction for prevention of HO after surgery. After a median follow up of 126 months (range 96 – 156 months) none of our patients developed HO. Impaired wound healing or other post surgery complications like trochanteric nonunion were not observed. A single fraction of RT seems to be a sufficient, cost effective and safe treatment regimen. In our study we report excellent results as none of our patients developed HO.

Heterotopic Ossification Prophylaxis After Total Hip Arthroplasty: Randomized Trial of 400 vs 700 cGy

BACKGROUND

Heterotopic ossification (HO) is a known complication following total hip arthroplasty. Radiation is an effective prophylaxis, but an optimal protocol has yet to be determined. We performed a randomized, double-blinded clinical trial in high-risk patients to determine the efficacy of 400 vs 700 cGy doses of radiation.

METHODS

One hundred forty-seven patients undergoing total hip arthroplasty and at high risk for HO at an urban medical center were randomized to receive either a single 400 or 700 cGy dose of radiation postoperatively. High risk was defined as a diagnosis of diffuse idiopathic skeletal hyperostosis, hypertrophic osteoarthritis, ankylosing spondylitis, or history of previous HO. Radiation was administered on the first or second postoperative day. A single blinded reviewer graded radiographs taken immediately postoperatively and at a minimum of 6 months postoperatively using the Brooker classification. Progression was defined as an increase in Brooker classification. Operative data including surgical approach, implant fixation, revision surgery, and postoperative range of motion data were also collected.

RESULTS

A significantly greater portion of patients who received the 400 cGy dose demonstrated progression of HO than patients who received the 700 cGy dose. There were no wound complications. No preoperative factors were associated with a higher rate of progression. Patients who progressed had less flexion on physical examination than patients who did not progress, but this was not clinically significant.

CONCLUSION

Seven hundred centigray was superior to 400 cGy in preventing HO formation following total hip arthroplasty in high-risk patients and may be the more effective treatment in this population. Further studies comparing 700 cGy to dosages between 400 and 700 cGy may help to clarify if a more optimal dose can be identified.

Prophylactic radiotherapy against heterotopic ossification following internal fixation of acetabular fractures: a comparative estimate of risk

OBJECTIVE

Radiotherapy (RT) is effective in preventing heterotopic ossification (HO) around acetabular fractures requiring surgical reconstruction. We audited outcomes and estimated risks from RT prophylaxis, and alternatives of indometacin or no prophylaxis.

METHODS

34 patients underwent reconstruction of acetabular fractures through a posterior approach, followed by a 8-Gy single fraction. The mean age was 44 years. The mean time from surgery to RT was 1.1 days. The major RT risk is radiation-induced fatal cancer. The International Commission on Radiological Protection (ICRP) method was used to estimate risk, and compared with a method (Trott and Kemprad) specifically for estimating RT risk for benign disease. These were compared with risks associated with indometacin and no prophylaxis.

RESULTS

28 patients (82%) developed no HO; 6 developed Brooker Class I; and none developed Class II-IV HO. The ICRP method suggests a risk of fatal cancer in the range of 1 in 1000 to 1 in 10,000; the Trott and Kemprad method suggests 1 in 3000. For younger patients, this may rise to 1 in 2000; and for elderly patients, it may fall to 1 in 6000. The risk of death from gastric bleeding or perforation from indometacin is 1 in 180 to 1 in 900 in older patients. Without prophylaxis risk of death from reoperation to remove HO is 1 in 4000 to 1 in 30,000.

CONCLUSION

These results are encouraging, consistent with much larger series and endorse our multidisciplinary management. Risk estimates can be used in discussion with patients.

ADVANCES IN KNOWLEDGE

The risk from RT prophylaxis is small, it is safer than indometacin and substantially overlaps with the range for no prophylaxis.

Risk of radiation-induced malignancy with heterotopic ossification prophylaxis: a case-control analysis

PURPOSE

To determine the risk of radiation-induced malignancy after prophylactic treatment for heterotopic ossification (HO).

METHODS AND MATERIALS

A matched case-control study was conducted within a population-based cohort of 3489 patients treated either for acetabular fractures with acetabular open reduction internal fixation or who underwent total hip arthroplasty from 1990 to 2009. Record-linkage techniques identified patients who were diagnosed with a malignancy from our state health registry. Patients with a prior history of malignancy were excluded from the cohort. For each documented case of cancer, 2 controls were selected by stratified random sampling from the cohort that did not develop a malignancy. Matching factors were sex, age at time of hip treatment, and duration of follow-up.

RESULTS

A total of 243 patients were diagnosed with a malignancy after hip treatment. Five patients were excluded owing to inadequate follow-up time in the corresponding control cohort. A cohort of 238 cases (control, 476 patients) was included. Mean follow-up was 10 years, 12 years in the control group. In the cancer cohort, 4% of patients had radiation therapy (RT), compared with 7% in the control group. Of the 9 patients diagnosed with cancer after RT, none occurred within the field. The mean latency period was 5.9 years in the patients who received RT and 6.6 years in the patients who did not. Median (range) age at time of cancer diagnosis in patients who received RT was 62 (43-75) years, compared with 70 (32-92) years in the non-RT patients. An ad hoc analysis was subsequently performed in all 2749 patients who were not matched and found neither an increased incidence of malignancy nor a difference in distribution of type of malignancy.

CONCLUSION

We were unable to demonstrate an increased risk of malignancy in patients who were treated with RT for HO prophylaxis compared with those who were not.

Heterotopic ossification after total hip arthroplasty: our experience

Heterotopic ossification is a condition characterized by the presence of mature lamellar bone and often bone marrow in soft tissues surrounding a major joint. It represents a common complication after total hip arthroplasty (THA). The etiology and predisposing factors are not completely known, but some authors reported that the implant of a non-cemented prosthesis seems to be associated with a greater incidence of HO. Two hundred and two non-cemented total hip arthroplasties were performed between October 1997 and February 2002. The mean age was 70.2 years. The average follow-up for 181 hips included in the study was 96 months (range, 72-120 months). A standard lateral approach (Hardinge) was performed for the implant of a non-cemented femoral component and a non-cemented acetabular component. Radiographs were done before and after surgery, at 1, 4 and 12 months postop, then every year. The incidence of HO was assessed in the antero-posterior view at each interval and graded according to Brooker classification. Out of 181 implants, HO was observed in 52 hips (28,7%). Heterotopic bone was graded as class I in 32 (17.7%) hips, class II in 14 (7.73%) hips, class III in 6 (3,3%) hips and class IV in none (0%). The mean preoperative Harris hip score was 48; at the last follow-up, the mean postoperative score was preoperatively to a mean of 89 points (range, 76-97 points) in HO Hip and of 91 points (range, 78-100 points) in the other Hip. In our experience, non-cemented THA led to a higher incidence of class I and II HO according to Brooker Classification, the incidence of HO is comparable to the rates reported in recent studies about the HO finding after a non-cemented THA, the importance of clinical symptoms in the presence of HO is very low.