K. David Moore

Indomethacin versus radiation therapy for prophylaxis against heterotopic ossification in acetabular fractures: A randomised, prospective study

We report a prospective, randomised, blinded clinical comparison of the use of indomethacin or radiation therapy for the prevention of heterotopic ossification (HO) in 75 adults who had open reduction and internal fixation of acetabular fractures through either a Kocher-Langenbeck, a combined ilioinguinal and Kocher-Langenbeck, or an extended iliofemoral approach. Indomethacin, 25 mg, was given three times daily for six weeks. Radiation with 800 cGy was delivered within three days of operation. Plain radiographs were reviewed and given Brooker classification scores by three independent observers who were unaware of the method of prophylaxis. One patient died from unrelated causes and two were lost to follow-up, leaving 72, 33 in the radiation group and 39 in the indomethacin group, available for evaluation at a mean of 12 months (6 to 48). There was no significant difference in the two groups in terms of age, gender, injury severity score, estimated blood loss, delay to surgery, head injury, presence of femoral head dislocation, or operating time, and no complications due to either method of treatment. The final extent of HO was already present by six weeks in all patients who were followed up. Three patients in the radiation group and five who received indomethacin developed HO of Brooker grade III. Two patients in the indomethacin group developed Brooker IV changes; both had failed to receive proper doses of the drug. Cochran-Armitage analysis showed no significant difference between the two treatment groups as regards the formation of HO. Indomethacin and single-dose radiation therapy are both safe and effective for the prevention of HO after operation for acetabular fractures. Radiation therapy is, however, approximately 200 times more expensive than indomethacin therapy at our institution and has other risks.

Total Hip Arthroplasty with Porous-Coated Prostheses Fixed without Cement in Patients Who Are Sixty-five Years of Age or Older*

We reviewed the results of 212 total hip arthroplasties performed without cement in 203 unselected, consecutive patients who were sixty-five years of age or older. The outcome was known for 196 hips, thirty-seven of which had been followed until the death of the patient and 159 of which had been followed for a minimum of five years. A reoperation was done in 4 percent (seven) of the 196 hips. These reoperations included one revision because of loosening of the stem and five revisions of the cup. Three of the acetabular revisions were done because of fracture due to polyethylene wear; one, because of recurrent dislocation; and one, because of polyethylene wear and a fracture due to lysis. In the seventh reoperation, a cup and stem were exchanged because of infection. The probability that a hip prosthesis would survive twelve years without a reoperation was 0.92 (95 percent confidence interval, 0.85 to 0.99). We evaluated the clinical results for 152 patients who had not had a reoperation and had been followed for at least five years (mean, 8.5 years; range, five to fourteen years). Of these patients, thirteen (9 percent) had pain that limited activity: five (3 percent) had pain in the thigh (four patients) or groin (one patient), and eight (5 percent) had trochanteric pain and tenderness. One hundred and forty-four (95 percent) of the patients noted an improvement in overall function, and 149 (98 percent) reported satisfaction with the outcome. One hundred and thirty-five hips that were not revised were followed radiographically for at least five years (mean, 8.2 years; range, five to fourteen years). In this group, osteolysis was observed in three hips (2 percent); loosening of the cup, in three (2 percent); and loosening of the stem, in one (1 percent). Stress-shielding was seen on the two-year postoperative radiographs of forty-five (26 percent) of the 174 hips that were followed for at least that duration. The prevalence of osteolysis, loosening of a component, and reoperations was no greater in this subgroup than in the overall group. These results indicate that total hip arthroplasty without cement can be successful in older patients. This study also provides a reference for comparison with the results of total hip arthroplasty performed with cement and those of so-called hybrid total hip arthroplasty (an acetabular component fixed without cement and a femoral component fixed with cement) in patients who are sixty-five years of age or older.

Surface crystalline phases and nanoindentation hardness of explanted zirconia femoral heads

One new and nine explanted zirconia femoral heads were studied using glancing angle X-ray diffraction, scanning electron microscopy, and nanoindentation hardness techniques. All starting zirconia implants consisted only of tetragonal zirconia polycrystals (TZP). For comparison, one explanted alumina femoral head was also studied. Evidence for a surface tetragonal-to-monoclinic zirconia phase transformation was observed in some implants, the extent of which was varied for different in-service conditions. A strong correlation was found between increasing transformation to the monoclinic phase and decreasing surface hardness. Microscopic investigations of some of the explanted femoral heads revealed ultra high molecular weight polyethylene and metallic transfer wear debris.

Outcome of hemiresurfacing in osteonecrosis of the femoral head

Hemiresurfacing of the femoral head for treatment of osteonecrosis has been proposed as a reasonable alternative to total hip arthroplasty. The results of 59 patients with Ficat Stage III osteonecrosis done by a single surgeon are reviewed. At an average followup of 4.5 years, 16 patients were considered failures because of conversion to total hip arthroplasty or considerable groin pain requiring medication. Failure did not correlate with age, body mass index, preoperative length of symptoms, acetabular articular cartilage status at the time of surgery, or cause of the underlying disease. The only factor associated with failure was a lower preoperative Harris hip score. Conversion of the failed implants to total hip arthroplasty was straightforward, confirming the conservative nature of the procedure. However, pain relief and recovery after resurfacing are less reliable than that associated with total hip arthroplasty. This procedure may be appropriate for patients younger than 30 years, given the ease of conversion to THR if failure occurs. The patient should be counseled regarding expectations.

Early Failure of a Cross-Linked Polyethylene Acetabular Liner: A Case Report

The use of highly cross-linked ultra-high molecular weight polyethylene in total hip arthroplasty has become a popular alternative to the use of conventional polyethylene. Evaluations with use of hip simulator tests1-4 and clinical evaluations of total hip replacements5-10 have independently shown that polyethylene materials processed with gamma irradiation followed by melting or annealing have extremely low wear rates. However, it also has been demonstrated that such cross-linking processes may reduce the fracture toughness and resistance to fatigue crack propagation of polyethylene11-16. Bradford et al.14 found that retrieved cross-linked polyethylene acetabular liners exhibited surface cracking that had not been predicted by in vitro hip simulator studies. Tower et al.17 observed fatigue failure at the superior aspect of the rim of four retrieved highly cross-linked acetabular bearings. They concluded that the factors contributing to these failures included thin polyethylene at the cup rim, a relatively vertical cup alignment, and compromised material properties of the cross-linked polyethylene in comparison with conventional polyethylene. In the current case report, we describe the failure of a highly cross-linked polyethylene acetabular liner less than three years after implantation. We believe that the mechanisms of failure were fracture of the cross-linked polyethylene where it was thin along the locking groove and abnormal loading of the cup because of improper seating of the liner in the shell at the time of the original procedure. This study was conducted with institutional review board approval and in compliance with HIPAA (Health Insurance Portability and Accountability Act) requirements at our institution. A seventy-four-year-old woman underwent a primary right total hip replacement through a posterior minimally invasive approach. The femoral component was a VerSys Advocate cemented stem (Zimmer, Warsaw, Indiana) with a satin surface finish, a 34-mm neck length, and a …

Titanium Prosthetic Wear Debris in Remote Bone Marrow. A Report of Two Cases

We report the cases of two patients who had a severely worn total joint implant. In each case, histological analysis of bone marrow from the iliac crest revealed macrophages that contained deep black, angular areas of pigmentation. Energy-dispersive x-ray analysis revealed the pigmentation to be titanium, aluminum, and vanadium. We are not aware of any reports that have conclusively documented the presence of metallic wear debris in bone marrow that is remote from the site of a severely worn total joint implant. The findings of the present study demonstrate that techniques other than light microscopy are needed to identify and characterize wear debris at sites that are remote from a total joint implant. Our findings also support the hypothesis that wear particles can be systemically transported to and deposited at remote sites. CASE 1. A fifty-five-year-old woman who had degenerative joint disease was managed with a right total hip arthroplasty without cement in 1990. A titanium metal-backed acetabular component and a proximally porous-coated cobalt-chromium femoral component were used. Six months later, the patient reported clicking and subluxation of the right hip. In February 1992, during the preoperative evaluation for a left total hip arthroplasty, the patient complained of migraine headaches. Laboratory studies revealed that the patient had borderline anemia. The patient reported, in June 1995, that the right hip had dislocated and then had reduced spontaneously. She complained of intermittent fever and chills, gastrointestinal cramps, intermittent epistaxis, intermittent swelling of the lower extremities, and fatigue. The patient was mildly anemic (hemoglobin, 10.8 grams per deciliter [108 grams per liter]; normal range, 12.0 to 16.0 grams per deciliter [120 to 160 grams per liter]) and leukopenic (white blood-cell count, 3.6 x 103 per microliter [3.6 x 109 per liter]; normal range, 4.5 to 11.0 x 103 per microliter …

Custom Triflange Acetabular Components for Large Acetabular Defects: Minimum 10-Year Follow-up

Compromise of bony support presents a difficult problem in acetabular revision surgery. Although various methods have been proposed to cope with this problem, they have had variable results and little long-term follow-up. The authors reviewed the results of 37 patients undergoing custom triflange revision surgery. Two patients were lost to follow-up, leaving 35 patients with minimum 10-year clinical and radiographic follow-up. Thirty-two (91%) of 35 components were unrevised and functioning well at minimum 10-year follow-up. One component placed for pelvic discontinuity loosened at 12 years after surgery but was converted to a conventional total hip. One component had failure of 3 ischial screws at 6 months; however, at 11 years, the patient had no additional clinical or radiographic evidence of loosening. The average Harris hip score was 28 preoperatively and 90 postoperatively. Two components (6%) were removed for infection. There were no dislocations, fractures, or nerve injuries. Revision of large acetabular defects with a custom triflange component resulted in reliably good to excellent results at minimum 10-year follow-up. [Orthopedics. 2018; 41(3):e316-e320.].