A comparison of the outcome of cemented all-polyethylene and cementless metal-backed acetabular sockets in primary total hip arthroplasty

We compared, after a 10-year-minimum follow-up, the outcome of 50 cemented all-polyethylene Charnley acetabular sockets with that of 51 cementless metal-backed sockets in 2 comparable cohorts of young patients. Although the revision rate for the cemented and cementless group was 28% and 35%, respectively, the revision rate for aseptic loosening was 28% for the cemented and 12% for the cementless group. The mean polyethylene wear was 0.112 and 0.114 mm/y, respectively, for the 2 groups. Linear osteolysis was observed in 18 of 50 cemented sockets. Expansile osteolysis presented in 10 of 51 cementless sockets and only in one of the cemented sockets. In conclusion, cementless components had more durable fixation than cemented components. However, they presented more aggressive expansile osteolysis caused by the coexistence of polyethylene and metal debris.     

Cementless hemiarthroplasty for femoral neck fractures in elderly patients

Objectives:

The use of cement is associated with increased morbidity and mortality rate in elderly patients, hence cementless hemiarthroplasty is suggested. We evaluated the results of cementless hemiarthroplasty for femoral neck fractures in elderly patients with high-risk clinical problems.

Materials and Methods:

Forty-eight patients (29 females, 19 males) with a mean age of 88 years (range: 78 to 102 years). having femoral neck fractures were treated with the use of cementless hemiarthroplasty. Porous-coated femoral stems were used in 30 patients (62%) and modular type femoral revision stems in 18 patients (38%). Bipolar femoral heads were used in all patients. Radiological follow-up after operation was done at the one, three, six months and annually.

Results:

The mean follow-up period was 4.2 years (range: 18 months to eight years). None of the patients died during hospitalization. Medical complications occurred in six patients (12%) within the follow-up period and four patients (8%) died within this period. Only two hips were converted to total hip arthroplasty due to acetabular erosion. Femoral revision was planned for one patient with a subsidence of > 3 mm. None of the patients had acetabular protrusion or heterotopic ossification. The mean Harris-hip score was 84 (range: 52 to 92). Dislocation occured in one patient (2%).

Conclusion:

Cementless hemiarthroplasty is a suitable method of treatment for femoral neck fractures in elderly patients with high-risk clinical problems especially of a cardiopulmonary nature. This method decreases the risk of hypotension and fat embolism associated with cemented hemiarthroplasty.     

Second-generation cementless total hip arthroplasty in patients with osteonecrosis of the femoral head

The results of cementless total hip arthroplasties in patients with osteonecrosis have been inferior to those in patients with other diagnoses. Fifty-eight primary total hip arthroplasties with insertion of a femoral stem with a circumferentially proximal porous coating and a cementless acetabular component were followed for a mean of 11.1 years. Fifty-seven (98%) of 58 stems were biologically stable, and one stem was loose. There were acetabular revisions in 18 hips (31%) because of polyethylene wear and osteolysis. One hip (1.7%) underwent revision of both acetabular and femoral components. Osteolysis around the acetabular component was seen on radiographs in 22 hips (37.9%). Femoral osteolysis was seen in 9 hips (15.5%), and there was no osteolysis below the lesser trochanter in any hip. Second-generation femoral prostheses provide excellent fixation in patients with osteonecrosis of the femoral head. However, a high rate of polyethylene wear and osteolysis in these high-risk patients remains a challenging problem.     

In vitro investigation of orthopedic titanium-coated and brushite-coated surfaces using human osteoblasts in the presence of gentamycin

Anti-infective coatings have been developed to protect the surfaces of cementless implants from bacterial colonization that is known to be a prerequisite for device-related infection. The aim of this study is to investigate the effect of brushite-coated arthroplasty surfaces on human osteoblasts and to evaluate the impact of concomitant exposure to gentamycin. We cultured human osteoblasts (hFOB 1.19) on brushite-coated and uncoated titanium alloy in the presence of gentamycin and analyzed cell function and vitality. Our results show that brushite-coated titanium alloy surfaces supported the function of osteoblasts and the expression of extracellular matrix even in the presence of highly dosed gentamycin. Brushite-coated titanium alloy surfaces supported osteogenic function, indicating that this coating could enhance implant osteointegration in vivo. Concomitant exposure to gentamycin slightly decreased osteoblastic activity in vitro, suggesting that there might also be negative effects in vivo. However, in vivo studies are necessary to validate these in vitro findings.     

Reconstruction of major segmental acetabular defects with an oblong-shaped cementless prosthesis: a long-term outcomes study

A retrospective outcomes study was performed on 25 consecutive acetabular reconstructions of major segmental defects by using an oblong-shaped cementless implant. All patients had combined acetabular defects (type III) as defined by the American Academy of Orthopaedic Surgeons classification of acetabular bone deficiency. Long-term follow-up was performed at an average of 11 years postoperatively. Clinical and radiographic outcomes were measured. Failures were defined by component revision or clear radiographic evidence of loosening. Six patients died before final evaluation, and 4 patients did not have complete radiographic data, leaving 14 patients (15 hips) for final analysis. At final follow-up, only 3 of the implants had failed and were revised. There was 1 case of a well-functioning implant with circumferential radiolucency; otherwise, there was no evidence of loosening among the remaining implants.     

Cementless alumina-on-alumina total hip arthroplasty in patients younger than 50 years: a 5-year minimum follow-up study

Sixty-seven patients (78 hips) who were younger than 50 years underwent cementless total hip arthroplasty using a porous-coated acetabular cup, an alumina liner, a 28-mm alumina head, and a proximally porous-coated femoral stem. One patient (1 hip) died and 2 patients (3 hips) were lost to follow-up. The remaining 64 patients (74 hips) were followed for 5 to 6 years. Their mean age at the index operation was 37 years. The mean Harris hip score was 94 points at the time of final follow-up. Four patients (4 hips) had mild thigh pain. All acetabular and femoral components were bone-ingrown, and neither pelvic nor femoral osteolysis was identified. No fracture of the ceramic liner or head was identified. Wear of the ceramic components was undetectable in 27 hips in which measurement was possible.     

Acetabular micromotion as a measure of initial implant stability in primary hip arthroplasty: An in vitro comparison of different methods of intial acetabular component fixation

Micromotion has been shown to affect bony ingrowth into cementless components. This study was designed both to quantitate initial micromotion at the prosthesis-periacetabular bony interface and to compare different methods of commonly employed acetabular component fixations, ie, a press-fit hemispherical titanium cup, a press-fit hemispherical titanium cup with one and two dome screws, a press-fit titanium hemispherical cup with three spikes, and a cemented chromium-cobalt cup. The press-fit component without screws demonstrated the greatest motion equaling 162 μm at the ilium, 97 μm at the pubis, and 54 μm at the ischium. With one and two screws placed into the dome, the mean ileal displacement decreased by 28 μm (17%) and 36 μm (22%), respectively. Dome screw placement demonstrated a minimal effect at the pubis and ischium. Compared to the press-fit component without augmentation, the tri-spike motion was less at the pubis and ischium. The cemented prosthesis provided the least amount of motion in all three areas tested. This experiment demonstrates that the ilium provides the least amount of support to immediate acetabular fixation, while the pubis (anterior column) and ischium (posterior column) provide more stability. One dome screw does not afect the stability of a hemispherical prosthetic cup significantly. A two dome screw fixation provides an added method of support at the ilium, but fails to decrease motion at the pubis or ischium significantly. The tri-spike fixation does not restrict motion at the ilium to the extent as the dome screws, but its effect at the ischium and pubis is much more pronounced. The obvious difference between initial motion seen with cemented versus uncemented components may suggest that before surgery, patients may need a period of protected weight bearing until ingrowth has occurred.     

Humeral head resurfacing in central bone defects: in vitro stability of different implants with increasing defect size

We examined the rotary motions of two distinct cementless surface replacement arthroplasties of the shoulder that were implanted on humeri with central spherical bone defects of 8%, 17%, and 37% of the head volume (n = 5 each). Rotary motions were measured under a cyclic torque application and translated into relative micromotions. Implant A with a perforated central crown had micromotions < 150 μm in all bony defects and during all simulated shoulder activities. Implant B with a central tapered tri-fin pin had no micromotions > 150 μm in defects of 0% and 8% during a strenuous activity like lifting 10 kg, but did exhibit micromotion > 150 μm in 40% of the experiments in defects of 17% and 37%, which could impair bony ingrowth. Implant B displayed a significant increase in micromotions for defects of 8% and 17% (p < 0.05). Our results suggest that implant A could be used without risk in spherical head defects up to 37% of volume, even in strenuous shoulder activities immediately after its implantation. Implant B, however, is recommended in spherical defects starting from 8% and only during light shoulder activities until bony integration of the implant has occurred.     

A prospective short-term outcome study of a short metaphyseal fitting total hip arthroplasty

The purpose of this study was to determine whether the short, metaphyseal fitting femoral stem would achieve stable fixation without diaphyseal fixation. A total of 126 patients (144 hips) were included in the study, and their mean age was 53.9 years (26-65 years). The mean duration of follow-up was 4.5 years (4-5 years). The predominant diagnosis was osteonecrosis of femoral head (88 of 144 hips, or 61%). The mean preoperative Harris hip score was 45 points, which improved to 96 points by the final follow-up. Western Ontario and McMaster Universities Osteoarthritis score and patient's activity score were improved substantially at the final follow-up. This short, metaphyseal fitting cementless femoral component achieved stable fixation without diaphyseal fixation, and there was minimal stress-shielding bone resorption in the calcar region.     

Cementless hemispheric acetabular components: 2–4-year results

A retrospective clinical and radiographic analysis was performed on 99 patients (106 hips) undergoing total hip arthroplasty with noncemented Harris-Galante (Zimmer, Warsaw, IN) or Optifix (Smith Nephew Richards, Memphis, TN) acetabular components. There were 94 primary and 12 revision procedures with a minimum follow-up period of 24 months (range, 24–52 months). The cups were evaluated for evidence of vertical and horizontal migration, as well as the presence of radiolucencies at the bone-implant interface. Age, sex, component inclination and medialization, cup coverage, and number of fixation screws used were examined to determine the influence of these factors on the incidence of cup migration or radiolucent line formation. A radiolucent line was present in at least one zone in 60% of the Harris-Galante and 45% of the Optifix cups. Progressive radiolucent lines were noted in two of the Optifix and three of the Harris-Galante components. Two Harris-Galante cups (1.9%) were revised. There were no Optifix cup migrations or evidence of instability in the Optifix or remaining Harris-Galante cups. Although there was a trend toward an increased incidence of radiolucencies in those cups lacking complete coverage, no statistically significant radiographic predictors for failure or impending failure could be determined from this short-term follow-up study. With the exception of the two revisions, all acetabular components performed well clinically over the study period.