Omnifit-HA stem in total hip arthroplasty. A 2- to 5-year followup.

Outcomes of the first 60 noncemented Omnifit-HA total hip arthroplasties in 56 patients were studied prospectively for 2 to 5 years. The femoral prosthesis had a proximal third circumferential hydroxyapatite coated surface treatment. The acetabular component was a hemispheric modular, porous, nonhydroxyapatite press fit cup, supplemented with screw fixation. One cup was revised for recurrent dislocation, with no femoral revisions. The mean Harris hip score was 54 (range, 20-76) before surgery and 96 (range, 83-100) at final followup, with all patients having an excellent or good outcome. Mild thigh pain occurred in 6% of hips. Subsidence occurred in 9% of hips (range, 1-2.8 mm); in all cases, subsidence was nonprogressive after 1 year. Stable bone ingrowth fixation was evident at the hydroxyapatite coated portion in 100%. A sclerotic reactive line adjacent to the nonhydroxyapatite portion of the stem occurred in 81% but was not adjacent to the hydroxyapatite coated portion of any stem. Endosteal condensation occurred in 90% and correlated with a higher Harris hip score (mean score, 96 with, 91 without). Endosteal lysis adjacent to or distal to the hydroxyapatite coating did not occur. Lytic lesions at the calcar occurred in 19% and correlated with a greater linear acetabular polyethylene wear rate (mean, 0.30 mm/year with lytic lesions, 0.17 mm/year without). This noncemented stem with proximal third hydroxyapatite coating showed excellent short term clinical and radiographic outcome. Absence of distal endosteal lysis, along with correlation of calcar erosion to polyethylene wear, suggests that early circumferential bony ingrowth afforded by hydroxyapatite coating prevents distal endosteal access to polyethylene debris at short term followup.     

A randomized clinical trial of cementless femoral stems with and without hydroxyapatite/tricalcium-phosphate coating: an 8- to 12-year follow-up study

To evaluate the effect of hydroxyapatite coating on cementless femoral stem, a prospective randomized clinical trial was conducted. A total of 84 hips from 69 patients were assigned to a hydroxyapatite/tricalcium-phosphate-coated group or a noncoated group. Thirty-two patients (37 hips) who received hydroxyapatite/tricalcium-phosphate-coated stems and 31 patients (38 hips) who received noncoated stems were followed for an average of 127 months. Forty-nine patients (78%) were men, and the average age was 45.5 years. Preoperative diagnosis was osteonecrosis in 62 hips (83%). The mean Harris hip score at the time of final follow-up was 91 points in the coated group and 90 points in the noncoated group. Six acetabular components (3 in each group) were revised. One femoral stem in the noncoated group was loose. There was no statistical difference in the survival distributions of the implants between the 2 groups.     

Total hip arthroplasty using an Omniflex modular system: 5 to 12 years followup

We evaluated intermediate-term results of primary cementless Omniflex prostheses. Forty-nine patients (57 hips) with a mean age of 44 years were observed for an average of 8.6 years. The average Harris hip score was 46 points before surgery and 87 points at final followup. Revision was done in five hips (9%) in five patients. Two acetabular components (4%) were revised because of breakage of the polyethylene insert. Three femoral components (5%) were revised because of aseptic loosening. Six femoral components (10%) were radiographically loose. Overall, 11 hips (19%) were considered mechanical failures. Osteolysis was identified around three acetabular components (5%) and around 20 femoral components (35%). Nine hips (16%) had femoral osteolysis around the distal stem tip. The average annual polyethylene liner wear was 0.18 mm. These results were inferior to those using other recent cementless total hip systems.     

Comparison of porous-coated titanium femoral stems with and without hydroxyapatite coating

BACKGROUND: The purpose of this prospective, randomized study was to evaluate the clinical and radiographic results associated with proximally porous-coated titanium stems that were identical in geometry but differed with regard to proximal surface treatment (with or without hydroxyapatite coating). METHODS: A prospective, randomized study was performed to evaluate fifty patients (100 hips) who had undergone sequential bilateral primary total hip replacement. A proximally porous-coated titanium stem with hydroxyapatite coating was implanted on one side and a proximally porous-coated titanium stem without hydroxyapatite coating was implanted on the other side during the same operative setting in all fifty patients. A cementless acetabular component made of titanium was used in all hips. There were thirty-six men and fourteen women; the mean age at the time of the operation was 45.3 years. The mean duration of follow-up was 6.6 years. Clinical and radiographic evaluations were performed preoperatively; at six weeks; at three, six, and twelve months; and yearly thereafter. RESULTS: The Harris hip scores in the hydroxyapatite-coated group (mean, 94 points) and non-hydroxyapatite-coated group (mean, 92 points) were similar at the final follow-up examination. The prevalence of transient pain in the thigh was 4% in each group. No acetabular or femoral component demonstrated aseptic loosening. Bone-remodeling patterns, including calcar atrophy, were similar in the two groups. No acetabular or femoral osteolysis was seen. CONCLUSIONS: At a mean of 6.6 years postoperatively, the clinical and radiographic results associated with proximally porous-coated femoral prostheses with identical geometries that differed only with regard to the presence or absence of hydroxyapatite coating were similar.     

Revision total hip arthroplasty with a custom cementless stem with distal cross-locking screws. Early results in femora with large proximal segmental deficiencies

BACKGROUND: Revision total hip arthroplasty in the setting of a large proximal segmental femoral deficiency and/or discontinuity between the proximal and distal parts of the femur remains a challenging problem. We describe the use of a cementless stem with distal cross-locking screws to provide stability of the femoral implant in this situation. METHODS: Seventeen custom fully porous and hydroxyapatite-coated titanium femoral stems with distal cross-locking titanium screws were implanted in sixteen patients during revision total hip arthroplasty. Preoperatively, all of the patients had Paprosky grade-IIIB or IV femoral deficiencies. At the time of follow-up, the Harris hip scores were calculated and radiographs were made. A successful result was defined as a postoperative increase in the Harris hip score of >20 points, a radiographically stable implant, and no additional femoral reconstruction. RESULTS: At the time of final follow-up, at a mean of 5.3 years postoperatively, the result was successful in sixteen of the seventeen hips, the mean Harris hip score had improved from 35 to 76 points, and all implants were clinically and radiographically stable. There were no postoperative infections or hip dislocations. CONCLUSIONS: The use of a custom femoral stem with distal cross-locking screws can provide at least intermediate-term clinical and radiographic stability in patients with Paprosky grade-IIIB or IV femoral deficiencies. Longer follow-up will be required to determine the longevity of these implants.     

The effect of adjuvant calcium phosphate coating on a porous-coated femoral stem

A prospective, randomized, double-blind, multicenter trial was done to determine if the addition of hydroxyapatite and tricalcium phosphate to the porous coating of a cementless femoral component would result in improved clinical and radiographic outcomes. Patients were randomized to receive identical porous-coated stems with (n = 159 hips) or without (n = 159 hips) hydroxyapatite and tricalcium phosphate coating. At 2 to 5 years followup (mean, 37 months), no implants were revised for aseptic loosening. There was no difference in clinical function between the two groups with respect to the Harris hip score or Western Ontario and McMaster Universities Osteoarthritis Index scores. Bony ingrowth occurred frequently in both groups with 99% of the hydroxyapatite and tricalcium phosphate group and 98% of the control group showing radiographic evidence of osseointegration. Implants coated with hydroxyapatite and tricalcium phosphate had significantly fewer radiolucencies adjacent to the porous coating, indicative of improved osseointegration. Radiolucencies were present in Gruen Zones 1, 7, 8, or 14 in 25% of the control group and in 7% of the hydroxyapatite and tricalcium phosphate group. This improved osseointegration could serve as an added barrier to particulate debris migration and increase the long-term survivorship of the implant.     

Modified Metaphyseal‐Loading Anterolaterally Flared Anatomic Femoral Stem: Five‐ to Nine‐Year Prospective Follow‐Up Evaluation and Results of Three‐Dimensional Finite Element Analysis

We have designed a proximal‐fitting, anterolaterally flared, arc‐deposit hydroxyapatite‐coated anatomical femoral stem (FMS‐anatomic stem; KYOCERA Medical, Osaka, Japan) for cementless total hip arthroplasty (THA) for Japanese patients with dysplastic hip osteoarthritis, using a nonlinear three‐dimensional finite element analysis simulating loading conditions. The Anatomic Fit stem was modified in the region of the arc‐sprayed surface, to allow more proximal appearance of spot welds. The aim of the present study was to analyze the clinical and radiographic outcomes of patients who underwent THA using this stem. We reviewed 73 consecutive patients (79 hips; 13 men 16 hips; 60 women 63 hips; age at surgery, 57.6 years, range, 35–78) who underwent cementless THA using the Anatomic Fit stem, at a follow‐up period of 7.1 years (range, 5.1–9.4). Harris Hip score improved from 40.7 ± 17.1 before surgery to 91.0 ± 5.2 points at follow‐up. The 7.1‐year stem survival rate was 100%. Radiographs at follow‐up confirmed the stability of the femoral stems within the femoral canal in all cases, with sufficient bone ingrowth. None of the patients had subsidence of the stem exceeding 2.0 mm within the femoral canal or changes in varus or valgus position of more than 2.0°. The Anatomic Fit stem provided excellent results. The nonlinear three‐dimensional finite element analysis demonstrated that the stem‐bone relative motion was 10 µm at the proximal end of the stem and proximal load transfer. Our analysis confirmed reduced radiolucency around the stem, minimal subsidence, appropriate stress shielding, and promising medium‐term stability within the femoral canal.     

Metaphyseal‐Loading Anterolaterally‐Flared Femoral Stem in Cementless Total Hip Arthroplasty: Five‐ to Eleven‐Year Follow‐Up Evaluation

Using a nonlinear three‐dimensional finite element analysis simulating loading conditions, we designed a new type of proximal‐fitting, anterolaterally‐flared, arc‐deposit hydroxyapatite‐coated anatomical femoral stem (FMS‐anatomic stem; Japan Medical Materials, Osaka, Japan) for cementless total hip arthroplasty (THA) for Japanese patients with dysplastic hip osteoarthritis. The aim of the present study was to analyze the clinical and radiographic outcomes of the new stem. We reviewed 143 consecutive patients (164 hips; 13 men, 14 hips; 130 women, 150 hips; age at surgery, 56.6 ± 7.6 years, mean ± SD, range, 30–74) who underwent cementless THA using the FMS‐anatomic stem at a single institution, with a follow‐up period of 7.6 ± 1.6 years (range, 5.3–11.0). Harris Hip score improved from 46.1 ± 12.6 before surgery to 90.0 ± 8.9 points post‐THA. The 7.6‐year survival rate of the stem was 99.0% after revision for aseptic loosening. Radiographs at follow‐up confirmed the stability of the femoral stems within the femoral canal in all cases, with sufficient bone ingrowth. None of the patients had subsidence of the stem exceeding 2.0 mm within the femoral canal or changes in varus or valgus position of more than 2.0°. The FMS‐anatomic stem provided excellent results in patients with dysplastic hip osteoarthritis. Our analysis confirmed reduced radiolucency around the stem in Gruen zones, minimal subsidence, appropriate stress shielding, and promising medium‐term stability within the femoral canal in our patients.     

The use of a hydroxyapatite-coated primary stem in revision total hip arthroplasty

Proximal ingrowth of femoral components in total hip arthroplasty (THA) is desirable because it minimizes proximal stress shielding associated with distal ingrowth stems and maximizes bone stock. This is a retrospective evaluation of initial results of revision THA using a proximally hydroxyapatite-coated femoral stem nominally designed for primary use. Patients requiring femoral stem revision were included if they had sufficient femoral bone stock to support a proximally fixed prosthesis (n = 33). This represents 53% of the femoral revisions performed during the period of the study. The average follow-up was 5 years (range 48-88 months). The mean Harris hip and Oxford hip scores were 86.5 and 25.2, respectively. Radiographically, 100% of the stems demonstrated bone ingrowth fixation. These results are superior to previous reports of primary cementless stems for revision THA. The use of a cementless nonmodular implant provides a viable option in some patients undergoing revision THA.     

Cementless Spotorno tapered titanium stems: excellent 10-15-year survival in 141 young patients

We evaluated the clinical and radiographic results of the first consecutive 154 implantations of a cementless, double-tapered straight femoral stem (cementless Spotorno (CLS), Sulzer Orthopedics) in 141 patients under the age of 55 (mean 47 (13-55)) years. After a mean follow-up of 12 (10-15) years, 11 patients (11 hips) had died and 7 (7 hips) could not be located. 5 patients (5 hips) underwent femoral revision-1 for infection, 1 for periprosthetic fracture and 3 for aseptic loosening of the stem. The overall survival rate of the stem was 97% at 12 years (95% confidence limits, 93%-100%), and survival with femoral revision for aseptic loosening as an end point 98 (95-100)%. The survival rate of the acetabular components was 78 (71-85)% after 12 years. The median Harris hip score at follow-up was 84 points. None of the patients had thigh pain. Radiolucent lines in Gruen regions 1 and 7 were present in 21 hips (17%). 2 hips had radiolucent lines in regions 2-6 on anteroposterior (AP) radiographs. No femoral osteolysis was detected. The mid- to long-term survival with this type of femoral component is excellent and compares favorably with cemented stems in this age group. However, the high rate of cup loosening and the low Harris hip scores are a concern in this subgroup of young patients.     

Contemporary total hip arthroplasty with and without cement in patients with osteonecrosis of the femoral head: a concise follow-up, at an average of seventeen years, of a previous report

We previously evaluated ninety-eight consecutive patients (148 hips) at mean of 9.3 years after total hip arthroplasty; the mean age at the time of the index surgical procedure was 47.3 years. Fifty patients (100 hips) had simultaneous bilateral arthroplasty with a cemented stem in one hip and a cementless stem in the contralateral hip. Forty-eight patients (forty-eight hips) had unilateral hip arthroplasty with a cementless stem. All patients had a cementless acetabular component. In our first report, we found no difference in clinical results, as measured with the Harris hip score and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), between the cementless and cemented stems. One hip (2%) in the hybrid group (a cementless cup and a cemented stem) had revision because of infection and two hips (2%) in the fully cementless group had revision of the femoral component because of a periprosthetic fracture. Between the time of follow-up in that study (at a mean of 9.3 years) and the time of follow-up in the present study (at a mean of 17.3 years), twenty-two revisions of acetabular components were performed, with eight in the hybrid group and fourteen in the fully cementless group. There was no difference in clinical results, as measured with the Harris hip score and the WOMAC, between the hybrid and fully cementless groups. At the time of the present review, forty (83%) of forty-eight acetabular components in the hybrid group and eighty (85%) of ninety-four acetabular components in the fully cementless group were intact. Most of the femoral components (98%) in both groups were intact. Wear and periacetabular osteolysis were the causes of failure in the hips requiring revision.     

Uncemented total hip arthroplasty using the CLS stem: A titanium alloy implant with a corundum blast finish: Results at a mean 6 years in a prospective study

An uncemented titanium alloy stem with a corundum blast finish and an uncemented titanium fibermetal mesh socket were implanted in a series of 57 hips. These prostheses were selected for use in the youngest, most active, and/or heaviest candidates for total hip arthroplasty. Fifty hips were available for study at a minimum 60 months. At a mean 6 years, 92% of the hips were rated good or excellent. The mean Harris hip score was 92. One patient experienced mild thigh pain. The corundum blast finish was associated with reliable implant stability. Survival analysis predicted a 96% rate of implant survival at 92 months. Loss of bone density was rated mild, minimal, or none in 88% of the hips. Three hips developed severe bone loss due to systemic disease. Polyethylene wear was measurable in 86% of the hips. Twenty hips developed focal proximal femoral bone erosions. One hip had endosteal cavitation distal to zone 7. The presence of proximal femoral erosions or endosteal cavitation correlated positively with the presence of measurable polyethylene wear. The limited and proximal distribution of femoral bone erosion despite evidence of extensive polyethylene wear suggested that bone apposition to the corundum blast finish resulted in a barrier to migration of wear debris.     

Cementless revision of total hip arthroplasty using the anatomic porous replacement revision prosthesis

This study reports the results of revision total hip arthroplasty with the Anatomic Porous Replacement Revision Hip System (Intermedics Orthopedics, Austin, TX) to investigate the value of cementless fixation. Sixty-six hips in 65 patients were followed for a mean of 4.7 years in patients with a mean age of 56 years. Thirty-six patients were categorized as Charnley class A, 16 as class B, and 13 as class C. Forty (61%) of the femurs were classified before surgery as having loss of bone distal to the intertrochanteric line. Thirty-two (48%) of the femurs required augmentation with demineralized strut cortical allografts, 5 (8%) required bulk femoral allografts, and 12 hips (18%) required acetabular allografts. Overall, 4 stems (6%) and 2 acetabular components (4%) required further revision surgery. The reason for further revision in 1 stem and both acetabular components was allograft failure. Fifty-six (85%) hips had excellent or good Harris hip scores. Ninety percent of hips had no or slight pain, and 90% allowed patients to walk with no or slight limp. Those hips that had hydroxyapatite coating added to the porous coating had statistically improved Harris hip scores for both pain and limp. Stable fixation was present in 95% of stems. Demineralized strut grafts healed in 30 of 32 hips. Thirty-nine of 44 noncemented revision sockets had no radiolucent lines and there were no loose components. Cementless fixation was effective for these hips.     

Cementless Spotorno tapered titanium stems

We evaluated the clinical and radiographic results of the first consecutive 154 implantations of a cementless, double-tapered straight femoral stem (cementless Spotorno (CLS), Sulzer Orthopedics) in 141 patients under the age of 55 (mean 47 (13-55)) years. After a mean follow-up of 12 (10-15) years, 11 patients (11 hips) had died and 7 (7 hips) could not be located. 5 patients (5 hips) underwent femoral revision—1 for infection, 1 for periprosthetic fracture and 3 for aseptic loosening of the stem. The overall survival rate of the stem was 97% at 12 years (95% confidence limits, 93%-100%), and survival with femoral revision for aseptic loosening as an end point 98 (95-100)%. The survival rate of the acetabular components was 78 (71-85) % after 12 years. The median Harris hip score at follow-up was 84 points. None of the patients had thigh pain. Radiolucent lines in Gruen regions 1 and 7 were present in 21 hips (17%). 2 hips had radiolucent lines in regions 2-6 on anteroposterior (AP) radiographs. No femoral osteolysis was detected.

The mid- to long-term survival with this type of femoral component is excellent and compares favorably with cemented stems in this age group. However, the high rate of cup loosening and the low Harris hip scores are a concern in this subgroup of young patients.     

Hydroxyapatite does not improve the outcome of a bipolar hemiarthroplasty

In a one-surgeon study the clinical and radiographic results of 30 cementless bipolar hip prostheses in 24 patients younger than 55 years were evaluated. Eleven noncoated prostheses (Noncoated Group) and 19 hydroxyapatite-coated prostheses (Hydroxyapatite Group) were compared after a mean followup of 10.4 years. The Harris hip score increased from a preoperative average of 41 points to 76 points at final followup (Noncoated Group, 70 points; Hydroxyapatite Group, 80 points). Thigh or groin pain was present in 15 patients (16 hips) (Noncoated Group, 55%; Hydroxyapatite Group, 53%). Radiographically, subsidence was the major problem at the noncoated prostheses (Noncoated Group, 91%; Hydroxyapatite Group, 5%), whereas osteolysis mainly was seen at the hydroxyapatite-coated prostheses (Noncoated Group, 18%; Hydroxyapatite Group, 89%). The obtained aseptic revision rate of 27% (Noncoated Group, 27%; Hydroxyapatite Group, 26%) is too high to use this implant in young patients. The large amounts of polyethylene wear debris generated by the bipolar system play an important role in this limited success. In the initially well-fixed hydroxyapatite-coated prostheses the sealing effect of a hydroxyapatite coating creates high concentrations of polyethylene in the limited joint space, resulting in massive proximal femoral osteolysis. Consequently, a hydroxyapatite coating introduces a new failure mechanism. Therefore, hydroxyapatite does not improve the outcome of a cementless bipolar hemiarthroplasty in the long-term.     

Minimum 10-year results of a tapered cementless hip replacement.

Seventy-one total hip arthroplasties with a cementless, wedge fit, cobalt chrome femoral component were reviewed in 60 patients at a minimum 10-year followup (mean, 11.5 years). For the femoral component, the mechanical failure rate was 5% and the revision rate for aseptic loosening was 0%. The mean Charnley scores for pain, function, and motion changed from preoperative mean values of 3.0, 2.7, and 3.2 to followup mean values of 5.7, 5.5, and 5.2, respectively. The followup mean Harris hip Score was 91. The incidence of thigh pain was 1.4% at 10-year followup. Ninety-five percent of femoral components showed radiologic evidence of stable, bone ingrowth fixation, whereas loosening was seen in 5% of stems. Despite the high incidence of acetabular osteolysis, no osteolysis was seen on the femoral side distal to the lesser trochanter. Nonmodularity of the femoral component led to unavoidable revision of stably fixed femoral components in seven (9.8%) hips during the revision of a loose socket. Design features (collarless, tapered, wedge fit, and circumferentially porous coated) were thought to be crucial to the superlative results with the cobalt chrome femoral component.     

Cementless revision total hip arthroplasty without allograft in severe proximal femoral defects

This study evaluates the difficult reconstructive challenge of severe proximal femoral bone loss. We present intermediate-term results of 46 hips with extensive proximal femoral bone loss that underwent revision total hip arthroplasty using cementless distal fixation without supplemental allograft. All were evaluated with the Harris hip score at a minimum of 2 years. Radiographs were assessed using the Engh fixation scale. At a mean of 6.4 (range 2-12) years, 43 of the 46 prostheses were functioning well. Two patients required revision for symptomatic loosening, and 1 prosthesis remains radiographically loose with a fair clinical score. Mean Harris hip score was 77 at last follow-up. There were 6 intraoperative femur fractures, 9 dislocations, 10 cases of severe stress shielding, and no infections.     

Second- and third-generation Omniflex modular femoral stem: results 3 to 8 years after surgery

Primary cementless total hip arthroplasty (THA) using the Omniflex modular femoral stem was conducted on 73 hips in 70 patients. The arc deposition (AD)-type stem was used in 26 hips, and the hydroxyapatite (HA)-type stem was used in 47 hips. The mean follow-up period of patients in the AD group was 78 (range, 61-96) months and that of patients in the HA group was 52 (range, 36-61) months. Clinically, improvement in the Harris hip score occurred in all cases. Thigh pain was reported in 3 (11.5%) AD hips and in 1 (2.1%) HA hip. Radiologically, bone ingrowth fixation was seen in 88.5% of the AD group and in 97.9% of the HA group. No subtrochanteric stress shielding, stem migration of > 2 mm, or revision THA occurred. The second- and third- generation Omniflex stems are useful cementless devices resulting in favorable initial biologic fixation and little bone atrophy at mid-term follow-up.