Comparison of hydroxyapatite-coated and non-hydroxyapatite-coated noncemented total hip arthroplasty in same patients

The comparison between standard blasted and hydroxyapatite (HA)-coated cementless femoral stems (CLS stem) was made in the same patients who have bilateral late-stage osteonecrosis. Clinical and radiographic evaluations were performed in 20 patients (among 29 patients) with the minimum follow-up of 10 years (range, 123-168 months). Endosteal bone formation was found in all patients of both stems, and no radiolucent line was observed. The mean of initial stem subsidence was 1.27 +/- 0.95 mm with the standard stem and 0.59 +/- 0.56 mm with the HA-coated stem. Other results, such as hip score, endosteal bone formation, cortical hypertrophy, osteolysis, and heterotopic ossification showed no statistical differences. These have suggested that the fixation obtained by the cementless stem with a corundum-blasted surface is stable enough to get excellent clinical and radiographic results without the HA coating.     

Alendronate inhibits periprosthetic bone loss around uncemented femoral components

Periprosthetic bone loss can be severe around the femoral component after uncemented arthroplasty. This study investigated the inhibitory effect of alendronate on periprosthetic bone loss. Seventeen patients underwent arthroplasty with an uncemented femoral component. Among them, 8 patients were given alendronate 5 mg once daily for 1 year (ALN group) and 9 patients received no pharmacotherapy (control group). Bone mineral density was measured in six periprosthetic zones by dual-energy X-ray absorptiometry at 1, 6, and 12 months after surgery. The average periprosthetic bone mineral density was 0.674–0.920 g/cm² at 1 month after surgery. From 6 months onward, the absolute bone mineral density and the ratio relative to the 1-month value were significantly decreased in the proximal zones of the femur in the control group (the ratio decreased from 0.817 to 0.769; P = 0.0040–0.0353). In the ALN group, however, the absolute and relative bone mineral density of the proximal femur remained unchanged for 12 months. In the other femoral zones, the absolute and relative bone mineral density remained unchanged throughout the study in both groups. We concluded that alendronate significantly inhibited the decrease of periprosthetic bone mineral density in the proximal femur after uncemented arthroplasty.     

Cementless Total Hip Arthroplasty Using a Spongy Metal Surface Hip Prosthesis With a Collarless,Proximally Porous-Coated Stem

A collarless, proximally porous-coated type of Spongiosa Metal II hip prosthesis was used for cementless total hip arthroplasty in 52 hips, and 48 hips were followed and assessed during a mean follow-up period of 6.3 years (minimum 5 years). There were 8 hips (16.7%) that had stress shielding, and 2 hips (4.2%) that had thigh pain. In terms of stability, the stem was bony stable in 39 hips, fibrous stable in 6, and unstable in 3. The stability of the stem was significantly correlated with the stem canal filling ratio. It was suggested that the much more proximal transfer of loading stress by a collarless, proximally porous-coated stem is not suitable for the Spongiosa Metal II series because it may unacceptably reduce the stability of the stem.     

Bone Remodeling Around Porous Metal Cementless Acetabular Components

Bone remodeling around cementless acetabular components after total hip arthroplasty has not been well characterized. A randomized, prospective study of total hip arthroplasty was performed comparing 2 cementless acetabular implants: a solid titanium and a more elastic porous tantalum design. Seventeen hips (9 porous tantalum, 8 titanium) underwent quantitative computed tomography at mean of 7.7 years, and adjacent bone mineral density (BMD) was calculated. The absolute and relative decrease in BMD from preoperative level was less in zones 9 to 15 mm adjacent to the porous tantalum compared to the titanium component (P ≤ .02) and predominated posterosuperiorly. The relative BMD increased in all regions adjacent to the porous tantalum component from 5% to 40% over the control. This data demonstrates stress-shielding likely occurs less around a highly porous metal implant of material with an elastic modulus similar to bone.     

Total Hip Arthroplasty Using a Cylindrical Cementless Stem in Patients With a Small Physique

We performed total hip arthroplasty using an anatomic medullary locking cementless stem for small-physique patients from 1988 to 1995. We conducted a retrospective study of 50 joints in 44 cases, including 40 developmentally dysplastic hips followed for 12 to 20 years (average, 15.1 years). Average height and body weight were 152 cm and 56 kg (5.0 ft and 124 lb), respectively, with an average body mass index of 24.2. Twelve joints (24%) were revised for acetabular-sided failures. Forty-eight stems (96%) showed bone ingrowth fixation, and there were no unstable stems. The simple cylindrical shape of the distal portion of the AML stem was less affected by deformity of the proximal femur of developmental dysplasia of the hip in patients with a small physique, and both clinically and radiologically good results were confirmed at long-term follow-up.     

Results of cementless total knee arthroplasty in an older rheumatoid arthritis population

Fifty-five total knee arthroplasties (TKAs) in thirty-nine adult (mean age, 62 years) patients with rheumatoid arthritis were studied prospectively for a period of 1-7 years. All of the procedures were performed using cementless fixation of the tibial and femoral components. The Knee Society clinical rating system mean knee scores increased 56 points after operation (mean, 88 points), and the mean functional scores increased 28 points (mean, 64 points). Two revisions (4%) have been required, one for secondary late infection and one for failure of a cementless metal-backed patellar component. Good bone stock was retained in both, allowing for uneventful cementless revision. Forty-two arthroplasties (76%) were completely pain-free, twelve (22%) had mild, occasional discomfort with weight-bearing, and one (2%) had moderate pain at last examination. In this older rheumatoid population, cementless TKA offers good or excellent early clinical results and excellent preservation of bone stock should revision become necessary.     

5-year review of second-generation acetabular cup with dome screws

A total of 197 modular cementless acetabular cups with central screw fixation were followed an average of 60 months. Four metal shells were revised (2%), including 2 for dislocations, 1 for pain and osteolysis, and 1 for loosening. An additional 2 cup liners were exchanged for dislocations. The 5-year survivorship of the metal shell was 98.0%. Two different types of polyethylene were used for the liners. Polyethylene wear and osteolysis were associated with the use of Hylamer liners and higher preoperative patient activity levels. Cementless acetabular cups with dome screw fixation can provide excellent clinical results. Hylamer liners sterilized with gamma radiation in air should not be used.     

Clinical experience with a proximally porous-coated second-generation cementless total hip prosthesis: minimum 5-year follow-up

This study reports the minimum 5-year follow-up of our experience with the Porous-Coated Anatomic E (PCA-E) series femoral stem and the modular acetabular cup. A total of 115 consecutive total hip replacements using PCA-E series (Howmedica, Rutherford, NJ) were performed in 108 patients. Six patients whose hips were performing well clinically died before 5-year follow-up and were excluded from the final evaluation. The remaining 109 hips (102 patients) were assessed at a mean follow-up of 72 months (range, 60-84 months). The hip diagnoses were osteoarthritis in 73, osteonecrosis in 31, rheumatoid arthritis in 2, and hip dysplasia in 3. The mean age was 56 years (range, 24-83 years). Three hips were revised: 1 because of late hematogenous infection, 1 because of aseptic loosening of the femoral component, and 1 because of postoperative loosening of an acetabular component. The Harris hip scores improved from a mean of 50 points (range, 20-66 points) preoperatively to a mean of 92 points (range, 64-100 points) at final follow-up. The score differed in each Charnley functional class, with a mean of 93 points (range, 72-100 points) in 57 hips of class A (no other joint involvement); 90 points (range, 58-100 points) in 26 hips of class B (opposite hip involvement); and 85 points (range, 37-100 points) in 26 hips of class C (multiple joint involvement or severe systemic disease). Out of 106 hips that had a full radiographic evaluation performed, 103 femoral components revealed stable bony ingrowth, 2 revealed stable fibrous ingrowth, and 1 showed migration with progressive loosening. This patient with radiographic loosening has minimal symptoms and has not required or been offered further surgery (Harris hip score of 86 points). The low aseptic loosening rate (2%) at minimum 5-year follow-up compares favorably with any cemented or cementless series. The osteolysis that was seen was focal and localized. The short follow-up does not allow determination of progression. There were no cases of distal osteolysis. We attribute the improved results from reported first-generation experience to multiple factors, including increased number of sizes (9 vs 6), increased proportional metaphyseal size, improved polyethylene manufacture (ram extruded vs machined), improved acetabular locking mechanism, and change to 26-mm from 32-mm femoral heads.     

Total Knee Arthroplasty in Patients Less Than 50 Years of Age: Results at a Mean of 13 Years

BackgroundPatients between 45 and 54 years old will be the fastest-growing cohort seeking total knee arthroplasty (TKA) over the next 15 years. The purpose of this investigation is to determine the clinical outcomes of TKA in patients less than 50 years old at a minimum of 10 years. We hypothesized that this patient population would have a high rate of survivorship that is similar to that of older patients.MethodsWe reviewed 298 consecutive TKAs on 242 patients at a minimum of 10 years postoperatively. Twenty patients died and 30 TKAs were lost to follow-up leaving 248 TKAs in 202 patients (91 male, 111 female) with a mean age of 45.7 years (range, 26-49) at the time of surgery. Patient-reported outcomes, survivorship, causes of reoperation, and initial postoperative radiographic parameters were collected.ResultsAt a mean of 13.0 years, there were 9 revisions for tibial loosening (3.6%), 8 for deep infection (3.2%), 7 for polyethylene wear (2.8%), and 3 for failed ingrowth of a cementless femoral component (1.2%). Kaplan-Meier analysis demonstrated 92.0% survivorship with failures defined as aseptic component revision and 83.9% survivorship for all-cause reoperation at 13 years. Patients with tibial alignment of 4° or more of varus or 10° or more of posterior slope were found to have increased rate of failure.ConclusionWhile overall durability was good in this young patient population, tibial fixation and deep infection were relatively common causes of failure. In addition, increased tibial varus and slope were found to increase the rate of failure. Furthermore, the nearly 3% risk of revision for wear suggests that the use of more wear-resistant bearing surfaces may reduce the risk of failure in this patient population.     

Two- to 12-year evaluation of cementless Buechel-Pappas total hip arthroplasty

A unique, straight-stemmed, proximally porous-coated, modular hip arthroplasty system, coated with thin-film (5- to 9-microm), titanium-nitride ceramic, was used clinically in 130 hip arthroplasties in 117 patients who were followed over a 2- to 12-year interval (mean, 6.45 years). Harris Hip Scores demonstrated 82.3% excellent, 15.4% good, 2.3% fair, and 0% poor results. Thigh pain that limited activities of daily living was seen in 0.8% (1 of 130) hips. Kaplan-Meier survival estimates using an endpoint of revision of any component for any reason demonstrated an overall survival of 95.5% during the 12-year interval. Cementless fixation survivorship of the acetabular and femoral components was 98.5% during the 12-year interval.