Hydroxyapatite-Coated Total Hip Femoral Components in Patients Less Than Fifty Years Old: Clinical and Radiographic Result after Five to Eight Years of Follow-up

By William N. Capello, M.D., Indianapolis, James A. D'Antonio, M.D., Moon Township, Pennsylvania, Judy R. Feinberg, Ph.D., Indianapolis, Indiana, and Michael Manley, Ph.D., Franklin Lakes, New Jersey

The Journal of Bone and Joint Surgery Vol. 79-A, no. 7, pp. 1023-1029, July 1997

Abstract: One hundred and thirty-three patients (152 hips) who were an average of thirty-nine years old (range, sixteen to forty-nine years old) received proximally hydroxyapatite-coated femoral prosthesis as part of a total hip arthroplasty and were followed for a minimum of fives years (average, 6.4 years; range, five to 8.3 years) or until revision. The average Harris hip score was 47 points (range, 22 to 77 points) preoperatively and 93 points (range, 49 to 100 points) at the time of the latest clinical evaluation. Two patients who have a well fixed femoral implant had activity-limiting pain in the thigh at the time of the most recent examination. Radiographic changes consistent with bone-remodeling (cortical hypertrophy and bone condensation) typically were seen around the mid-part of the shaft of the prosthesis. Forty-eight (32 per cent) of the 148 hips that were included in the radiographic analysis demonstrated a small amount of erosive scalloping in either zone 1 or zone 7 of Gruen et al. and intramedullary osteolysis was suspected in only one hip. All stems were radiographically osseointegrated according to a modification of the criteria described by Engh et al. Four stems were revised, but none of the revisions were performed because of mechanical failure (two stems were revised in conjunction with a revision of the cup because of pain; one, because of an infection; and one, after a traumatic femoral fracture that occurred six years postoperatively). Thus, threats of aseptic and mechanical failure were both 0 per cent. The combined rate of failure with included the two stems that were revised because of pain and the two stems that were associated with pain that limited activity, was 2.6 per cent (four of 152 stems). The overall clinical results associated with hydroxyapatite-coated femoral components were excellent in this group of young patients after intermediate-term follow-up. A review of serial radiographs showed mechanically stable implant with osseous ingrowth, evidence of stress transmission at the middle part of the stem, and minimum endosteal osteolysis.

Host-Bone Response to Porous-coated Cobalt-Chrome and Hydroxyapatite-coated Titanium Femoral Components in Hip Arthroplasty

By David F. Scott, MD, and William L. Jaffe, MD

The Journal of Arthroplasty Vol. 11 No. 4 1996

Dual-energy X-ray Absorptiometry Analysis of Paired Bilateral Case at 5 to 7 Years

Biomechanical and histological analysis of an HA coated, arc deposited CPTi canine hip prosthesis

By Matthew T. Walenciak, Mark C. Zimmerman, Robert D. Harten, John L. Ricci, and David T. Stamer Laboratories for Orthopaedic Research, Department of Orthopaedics, New Jersey Medical School, Newark, New Jersey 07103; Hospital for Joint Disease Orthopaedic Institute, Department of Bioengineering,New York, New York 10003

Journal of Biomedical Materials Research, Vol. 31, 465-474 (1996)

The interfacial shear strength and bone tissue response was investigated for an arc deposited (AD) commercially pure titanium implant surface, with (AD/HA) and without (AD) plasma-sprayed hydroxyapatite (HA) coating. Ten purpose bred coonhounds received bilateral femoral stem implantation (AD and AD/HKA) in the proximal femurs (hemiarthroplasty). The femoral prosthesis consisted of a modular CoCr alloy head; modular Ti-6A1-4V femoral stem. The AD surface had 30-35% greater surface roughness than the AD/HA surface. The HA coating had a purity greater than 90% and a crystallinity greater than 65%. After 6, 12, and 24 weeks, the implants were retrieved and analyzed with mechanical testing, qualitative and quantitative histology, and electron microscopy.The AD/HA implants had equivalent interfacial shear strengths to the AD implants at the time periods. The AD/HA implant had significantly greater linear bone contact than the AD implants. The 6-week implants had significantly thicker cortical bone than the 12- and 24-week implants. The HA coating was very stable in vivo, evidence by no thickness reduction at any time period. Qualitatively, the AD/HA implants primarily had bone contacting the implant surface with little fibrous tissue present, and the AD implants had bone and fibrous tissue contacting the implant surface. The electron microscopy analysis showed that the mechanically tested implants exhibited a mixed failure mode at the bone, HA coating, and titanium interfaces.

Remodeling of Bone around Hydroxyapatite-Coated Femoral Stems

By James A. D'Antonio, M.D., Moon Township, Pennsylvania, William N. Capello, M.D., Indianapolis, Indiana, and Michael T. Manley, Franklin Lakes, New Jersey

The Journal of Bone and Joint Surgery Vol. 78-A, no. 8, pp. 1226-1234, August 1996

Abstract: Two hundred and twenty-four total hip arthroplasties were performed in 201 patients with use of a femoral component with hydroxyapatite coating of the proximal portion of the stem. The mean duration of follow-up was seventy-one months (range, fifty-eight to eighty-seven months). Of the 224 arthroplasties, 208 (93 per cent; 190 patients) yielded a good or excellent clinical result. Four patients (2 per cent) reported mild-to-moderate activity-related pain in the thigh, and two (1 per cent) had aseptic loosening. The radiographic findings of progressive new-bone formation (cancellous condensation and cortical hypertrophy) throughout the zones adjacent to the middle and digital portions of the stem were evidence of early, extensive proximal fixation of the implant, with distal stress transfer through the implant, which is stiffer than the surrounding bone. Remodeling of the femur began early, was predictable, and progressed throughout the follow-up period. Cortical hypertrophy about the middle and distal portions of the stem occurred predominantly in the the mediolateral plane (in 105 hips {47 per cent}, compared with thirteen hips {6 per cent} in the anteroposterior plate), and it was more common in patients who had had poorer bone quality preoperatively. Intramedullary osteolysis was present in one femur (0.4 per cent) at five years; the osteolytic area was less than five millimeters in its greatest dimension and had not progressed at the time of the six- year follow-up evaluation. This low rate of osteolysis suggests that a circumferential coating of hydroxyapatite may effectively minimize migration of wear debris along the femoral stem. The progressive remodeling of the femur about the middle and distal portions of the stem, as evidence by cancellous condensation and cortical hypertrophy, has not, to our knowledge, been described previously to this magnitude in association with proximally coated (porous or hydroxyapatite-coated) femoral implants.

Current Concepts Review: Total Hip Arthroplasty with Hydroxyapatite-Coated Prostheses

By William L. Jaffe, MD and David F. Scott, MD, New York, NY

Total Hip Arthroplasties in Patients Less than Forty-Five Years Old

By Lawrence D. Dorr, M.D., and J. Pierce Conaty, M.D. Downey, California

From the Department of Orthopedics, Division of Arthritis, Ranch Los Amigos Hospital, Downey

The Journal of Bone and Joint Surgery, Vol. 65-A, No. 9, April 1983

Abstract: We studied the cases of eighty-one patients (108 total hip arthroplasties), ranging in age from fourteen to forty-five years, at an average of 4.5 years after the index operation and evaluated them with regard to six major factors: age, disease, Charnley category, prior operations, length of time since arthroplasty, and quality of the arthroplasty with regard to cementing technique and component position. After two to five years 78 per cent were satisfactory, but after five years or more only 72 per cent were satisfactory. Patients who were less than thirty years old had poorer results. Good technique yielded 93 per cent satisfactory clinical results.

The patients in this study with the worst prognosis for success following total hip arthroplasty were less than thirty years old, had osteonecrosis or osteoarthritis as the primary disease, and had a less than optimum reconstruction. Patients who were alcohol-abusers or who had had a prior hip infection or a prior acetabular cup or femoral hemiarthroplasty also had a poor prognosis. Patients who had the arthroplasty for collagen disease or were thirty years old or older, or both, and had a good technical reconstruction had the best prognosis.

Hydroxyapatite Coated Implants
Total Hip Arthroplasty in the Young Patient and Patients With Avascular Necrosis

By James A. D’Antonio, MD; William N. Capello, MD; Michael T. Manley, PhD; and Judy Feinberg, PhD

Clinical Orthopaedics, November, 1997, Volume 344

Two high risk groups for total hip arthroplasty, 136 patients (155 hips) younger than 50 years of age (average age, 38 years) and 44 patients (53 hips) with the diagnosis of avascular necrosis, have a minimum follow-up of 5 years and a mean follow-up of 6.8 years. The average Harris Hip Score at last follow-up totaled 93 and 90, respectively, and thigh pain was reported in 1.3% and 3.8%, respectively. All patients in both groups received the same hydroxyapatite coated femoral stem and the mechanical failure was 0%. No stem was revised for aseptic loosening, 100% of stems were bony stable by radiographic criteria, new bone formation was progressive about the femoral stem, and 0% endosteal lysis was found. The acetabular components had a mechanical failure rate of 10% and 7.5%, respectively, without osteolysis, and an additional 7% and 7.5% failed as a direct result of progressive osteolysis. The results with the porous press fit and hydroxyapatite threaded sockets were far superior to that of the smooth hydroxyapatite press fit sockets and socket failure was associated with thin polyethylene liners and the use of 32-mm head diameters. These findings show a high success rate with a nonporous hydroxyapatite coated titanium femoral stem. However, hydroxyapatite on a smooth acetabular component yielded less predictable results indicating that for long term fixation of the acetabulum an interlock of bone is preferred.

Total Hip Replacement in Patients Younger than Thirty Years Old
A Five-Year Follow-up Study

By Hugh P. Chandler, M.D., F. Timothy Reineck, M.D., Richard L. Wixson, M.D., and Joseph C. McCarthy, M.D., Boston, Massachusetts

The Journal of Bone and Joint Surgery, Vol. 63-A, No. 9, December 1981

Abstract: Twenty-nine young patients with thirty-three arthritic hips had total hip replacement. Follow-up at ten months showed that they were doing well, but at five years 57 per cent showed evidence of actual or potential loosening of at least one component of the prosthesis. Factors that seemed to adversely affect the results were an initial diagnosis of avascular necrosis, a previous mold arthroplasty, heavy activity on the part of the patient, a unilateral arthroplasty, and weight of more than eighty-two kilograms (180 pounds). Acetabular loosening occurred more than twice as frequently as femoral loosening.

A Critical Review of Hydroxylapatite-Coated Hip Implants

By James A. D'Antonio, MD; William N. Capello, MD; Michael T. Manley, PhD; Judy Feinberg, PhD.

Presented at the 1998 AAOS, New Orleans, LA

Arc Deposited CP Titanium with and without Hydroxylapatite Coating

By M. Hawkins, Ph.D and J. L. Ricci, Ph.D.

Options for Primary Fixation in Total Hip Arthroplasty: Hydroxyapatite*

By William N. Capello, M.D., James A. D'Antonio, M.D.

The Hip Society, 25th Open Scientific Meeting, February 16, 1997, San Francisco, CA

Evaluation criteria for efficacy of total hip arthroplasty include ease of implantation, predictable fixation to the skeleton, utility in a variety of age, diagnostic, and bone type groups, and maintenance of fixation with minimization of bone loss. These data are from a multicenter study of a proximally HA-coated femoral component. Of the 370 hips implanted during the study period, 324 have a five year minimum follow-up. The average Harris Hip Score is 96, with one case of activity-limiting thigh pain. The mechanical failure rate for the total group is 0.3% (one revision for aseptic loosening, no loose stems). Included in this study group are two high risk groups, 155 under the age of 50 and 53 with a diagnosis of AVN. Within these challenging subgroups the mechanical failure rate is 0.0%.

On latest radiographic evaluation, 100% of stems are bony ingrown with 61% of hips demonstrating cortical hypertrophy and all with midstem cancellous condensation in at least one Gruen zone. There were no cases of intramedullary osteolysis. These findings are corroborated by DEXA results in another study group of 28 hips implanted with the same femoral component . An average bone loss of 4% at 24 months was seen in the proximal zones.

Should these excellent results with this stem continue, the gold standard of cemented femoral fixation in young patients may need to be reconsidered.

*Note: This reprint is not yet available. Look for this article to appear in a future issue of the Journal of Bone and Joint Surgery.

DEXA - Dual Energy Xray Absorptiometry Analysis of Five-Year Femoral Remodeling of Uncemented Hip Prostheses

By David F. Scott, M.D., Ken Shubin Stein, B.S., William L.Jaffe, M.D. Fredrick Jaffe, M.D.

Paper No. 384, February 20, 1995, American Academy of Orthopaedic Surgeons Meeting, Orlando, FL

Eighty-seven matched patients with two fundamentally different uncemented femoral components were evaluated retrospectively by dual energy x-ray absorptiometry (DEXA). The patients were implanted with either a proximal-fitting hydroxyapatite-coated titanium stem (Howmedica Osteonics Omnifit-HA), or a distal fitting, porous-coated cobalt-chromium stem (DePuy AML). There were eight time groups from immediately postoperative to five-years postoperative. There were significantly different patterns of bone loss observed with the two groups. DEXA evaluation of different implant designs and correlation with long-term clinical results will be required to optimize uncemented femoral implant design.

Percent BMD change in Gruen zones in two implanted types. Differences between stem statistically significant in all zones except zone 4.

Long-Term Results of Use of the Anatomic Medullary Locking Prosthesis in Total Hip Arthroplasty

By C. Anderson Engh, Jr., M.D., William J. Culpepper, II, M.D., and Charles A. Engh, M.D., Arlington, Virginia

The Journal of Bone and Joint Surgery, Vol. 70-A, No. 2, February 1997

Investigation performed at the Anderson Orthopaedic Research Institute, Arlington

Abstract: A total hip arthroplasty was performed, with use of the anatomic medullary locking hip system, in 223 consecutive, non-selected hips in 215 patients. The mean age of the patients at the time of the operation was fifty-five years (range, sixteen to eighty-seven years). Twenty-one patients (twenty-two hips) were lost to follow-up and twenty-seven patients (twenty-seven hips) died less than ten years postoperatively. The remaining 167 patients (174 hips) were followed for a minimum of ten years (mean, eleven years; maximum, thirteen years). There were twenty reoperations involving a component. The rate of survival at twelve years was 0.97 ± 0.02 (mean and standard error) for the stem and 0.92 ± 0.03 for the cup. Patients who had osteolysis were younger than those who did not have osteolysis (mean age, forty-seven compared with fifty-six years; p < 0.01). Similarly, patients who had a reoperation were younger than those who did not have a reoperation (mean age, forty-six compared with fifty-four years; p < 0.01). the radiographic appearance of progressive wear that, in our opinion, was severe enough to cause the femoral head to completely penetrate the polyethylene liner was the most frequent reason for reoperation.

Prospective Evaluation of Bone Mineral Density Changes in the Femur after Uncemented Total Hip Arthroplasty: Five Year Followup

By David F. Scott, MD, Steven C. Choung, MD, Jeffrey Kaufman, MD, Frank S. Chen, MD, William L. Jaffe, MD, Fredrick F. Jaffe, MD

Investigation performed at the Hospital for Joint Diseases Orthopaedic Institute, New York, NY.

Abstract: Femoral remodeling occurs after implantation of an uncemented hip stem, with varying degrees of proximal bone loss and distal hypertrophy, depending upon the design of the stem and other factors. This study was designed to evaluate prospectively the bone mineral density (BMD) changes in the femur after uncemented total hip arthroplasty (THA) with two different stem designs - Howmedica Osteonics Omnifit and Depuy AML. ANOVA tests revealed that he percent BMD decreases postop were significantly different between the two stem groups in 6 of the 7 Gruen zones (except zone 4), and 11 of the 14 2cm zones (all but medial zones F & G, and lateral zone G). Implant design has a significant impact upon bone density loss in the femur after uncemented THA. Different implant designs cause significantly different BMD changes following uncemented THA; the Omnifit stem was associated with minimal bone loss, while the AML caused more substantial bone loss. The ramifications of substantial bone loss after THA could include periprosthetic fractures, increased morbidity during revision, and aseptic loosening. Prospective Dual Energy X-ray Absorptiometry (DEXA) studies allow accurate assessment of postoperative bone density changes after THA, and will allow the correlation between BMD changes and long-term outcome.