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Taperloc femoral component
The Journal
Taperloc
Femoral
of Arthroplasty
Vol. 9 No. 5 1994
Component
A 2-6-Year Study of the First 100 Consecutive Cases William Hozack, MD,*+ Robert Gardiner, MD,* Susan Hearn, MPT,-f Kennenth Eng, MS,+ and Richard Rothman, MD, PhD*t
Abstract: The first 100 consecutive patients who underwent insertion of the Taperloc (Biomet, Warsaw, IN) femoral stem were prospectively studied with a mean followup period of 3.8 years (range, 2-6 years). Two of the original 100 patients were lost, giving a 98% follow-up rate. The diagnoses included osteoarthritis (76 patients), avascular necrosis (19), rheumatoid arthritis (3). chrondrolysis (l), and post-traumatic arthritis ( I). The mean age at surgery was 56 years (range, 2 5-79 years), mean weight was 78 kg (range, 45-127 kg), and the female to male ratio was 29:71. Charnley pain and function scores were 3.0 and 2.8 before surgery and 5.5 and 5.4 after surgery. Thigh pain was present in 2% of the patients at the final follow-up evaluation. There were no revisions. Radiographic signs of bone-ingrowth fixation (calcar atrophy, spot welds) were seen in 92 of 94 components (98%). No component had complete demarcation of the porous-coated zones. Fifty-two of 94 patients were able to be matched for age, sex, weight, diagnosis, and length of follow-up period with a series of patients who received a contemporary cemented total hip. In this matched subset, the Charnley pain and function scores were 5.6 and 5.5 for the cementless Taperloc stem and 5.7 and 5.5 for the cemented control group; this is not a significant difference. These data indicate a clinical performance equivalent to a matched group of contemporary cemented total hip arthroplasties. Key words: hip, arthroplasty, uncemented, prosthesis, follow-up period, arthritis.
At present, controversy still exists concerning the optimal method of fixation for acetabular and femoral components in total hip arthroplasty (THA). Mechanical failure due to wear and aseptic loosening of cemented total hip components constitutes the most frequent cause of long-term failure. Aseptic loosening rates range from 1.5 to 19% in patients followed for 10 years or more.‘--5 Cemented THA in patients under the age of 60 has had even higher rates of loosening and revision.“-’ These findings have gcnerared interest in the use of biologic fixation as an alternative treatment method.
Early clinical trials have shown mixed results with regard to the biologic fixation of cementless femoral components,‘“p’5 and no long-term studies are available. Maloney and HarrisI noted a 24% incidence of pain, a 20% incidence of radiographic loosening, and a 16% incidence of femoral revision with an uncemented THA at 2-4 years. Callaghan ct al.” have shown a 16% incidence of thigh pain in 50 patients with an uncemented system followed for a minimum of 2 years. In a series of 307 uncemented Anatomic Medullary Locking (DePuy, Warsaw, IN) prostheses, Engh et al.18 noted a 14% incidence of thigh pain and a 2 I % incidence of limp. This substantial percentage of postoperative pain has not been reported by all authors, howeveI,.“‘-Jl At our institution, clinical experience with cementless femoral components has been quite favora-
*Pfpartmwt oJ’ Orihop~wd~Szrqfrv. .It~?r.wn Mrdkid Rollhman /nstirm, Philadflphia. Pfnr7svlvnni~7, and *Dickson-Divelfv Orthopfdic Clirlic. Kansas Cirv, Missouri. Reprint requests: William Hnrack. MD, The Rothman ln\titute. 800 Spruce Street. Philadelphia. PA 19107. From
School.
tirr
ti-he
489
490
The Journal
of Arthroplasty
Vol. 9 No. 5 October
ble.” The purpose of this study is to present the results of an initial, consecutive series of patients who were followed for a minimum of 2 years after undergoing a primary THA with an uncemented Taperloc femoral component (Biomet, Warsaw, IN). Second, these results are compared to a seriesof patients who underwent primary, cemented THA using a contemporary cemented system who were matched for age, sex, weight, diagnosis, and length of the follow-up period.
Materials
and
Methods
One hundred primary, uncemented femoral prostheses were inserted’ between December 1985 and January 1987. All patients received an uncemented, collarless, flat, tapered-wedge femoral component (Taperloc) with a titanium plasma spray circumferentially on the proximal 40%. The stem was used with both a regular and lateral offset design. The acetabular cup consisted of either a cemented, metal plasma-backed cup (70%) or an uncemented, titanium plasma-sprayed hemispheric cup fixed with screws (30%). The femoral head material used in this serieswas titanium alloy, although it has now been supplanted by either cobalt-chromium alloy or zirconium ceramic. The heads were modular, either 22 or 28 mm in size depending on the dimensions of the acetabulum. The average age of the patients was 56 years (range, 25-79 years). There were 7 1 men and 29 women. The preoperative diagnoses were osteoarthritis in 76 patients, avascular necrosis in 19, rheumatoid arthritis in 3, chondrolysis in 1, and posttraumatic arthritis in 1. Of the original 100 patients, 2 were lost and 4 died, leaving 94 patients available for review. The mean weight of these 94 patients was 78 kg (range, 45- 127 kg). The clinical outcome was graded using the Charnley modified scale of D’Aubigne and Postekz3 Before surgery, the mean Charnley pain and function scores were 3.0 (range, 2-5) and 2.8 (range, 2-6) (Table 1).
1994
All hip procedures were performed through either the direct lateral approach to the hip or the transtrochanteric approach, and were either performed or supervised by the senior author (R. R.). Patients were protected after surgery with two crutches for 12 weeks. The average length of the follow-up period was 3.8 years (range, 2-6 years). The immediate postoperative and all subsequent radiographs were reviewed for signs of femoral and acetabular component failure. Since the focus of this study is only on the femoral portion of the arthroplasty, the radiographic evaluation of the acetabular components has not been included. Vertical subsidence of the femoral component was measured by determining the change in distance from a fixed point on the femoral component to a fixed point on the proximal femur (usually the lesser trochanter). A decrease of 3 mm or more in the vertical direction was considered to indicate subsidence. Distal buttresses,radiolucencies about the femoral component, lossof proximal density, rounding of the calcar femoral, and spot welds were determined by studying sequential postoperative radiographs. All of the cemented femoral components were evaluated for loosening according to the criteria of Harris et al.L’ Definite loosening (subsidence 2 5 mm, cement-prosthesis radiolucency, cement fracture, component fracture, or shift in component position of 2 3 “), probable loosening (complete radiolucency of e 1 mm at the bone-cement interface), and possible loosening (> 50% radiolucency at the bone-cement interface) were recorded. In addition, 52 of the 94 patients were able to be matched for age, sex, weight, diagnosis, and length of the follow-up period with a controlled series of patients who underwent cemented THA using COIItemporary cemented femoral and acetabular components. Head sizeswere similar. The cement technique used was modern, with distal plugging of the canal, pulsatile lavage, centrifugation of cement, and pressurization. Surgical technique, postoperative regi-
Table Table
1. Demographics Taperloc
M/F Age (years) Weight (kg) Diagnoses Osteoarthritis Avascular necrosis Rheumatoid arthritis Other Follow-up period (years)
of Patients Stems
2. Demographics
Receiving
71129 68 (range. 78 (range. 76 19 3 2 3.8 (range,
of Patients Series
Cementless: Taperloc 60-74) 45-127)
2-6)
in the Matched
Cemented
k/F
34118 52
34,53 IX
Age (year>) Weight (kg) Follow-up period (years)
62 (range, 4H-7Y) 77 (range, 45-I 13) 3.8 (rang, 2-6)
67 (range, 48-79) 75 (range, 50- 1 13) 3.5 (range, 2-6)
Results Table
of the Taperloc
3. Results of the First 100 Taperloc Prostheses
5.5 5.4 5.6
3.0 2.8 3.1
of motion
men, and follow-up evaluations were identical between the two groups. The demographics of each group are shown in Table 2.
Statistics Student’s f-test was used to compare age, weight, and length of the follow-up period between the two matched groups. Wilcoxon’s two-sample test for nonparametric data was used to analyze the Charnley scores between the two groups.
Results The preliminary consecutive series of 94 patients who received the Taperloc femoral stem had excellent results both clinically and radiographically. The average postoperative Charnley pain and function scores for those patients were 5.5 (range, 2-6) and 5.4 (range, 2-6) (Table 3). Ninety-two (98%) of the 94 patients who received the Taperloc prosthesis reported having either no pain or only slight, occasional discomfort. Only two patients reported mild pain, which was controlled by nonsteroidal antiinflammatories, and no patient had more pain than they had had before surgery. Eightyfour (89%) of the patients who received the Taperloc prosthesis had no limp, while 10 (11%) had a mild or moderate limp. There were no revisions. Radiographic evaluation revealed that all of the femoral components were radiographically stable with no evidence of aseptic loosening or migration. No patient had complete demarcation of the porouscoated zone. Spot welds and calcar atrophy were
Table
Component
Pain Function Range NSD,
3.0 2.7 3.1
of motion no significant
differcncc.
Hozack
et al.
491
Discussion One of the most successful operations performed by orthopedic surgeons has been cemented THA. Yet, it has become apparent with longer follow-up periods that this procedure has imperfect durability. ‘,3~L’.15--17 Unfortunately, no method of stabilizing the bone-cement interface over long periods of time has been developed, in spite of considerable re-
4. Results of the Matched Series
Preoperative ‘raperloc
l
identified in 92 of 94 components (989/o), indicating excellent fixation. For the 52 patients who were matched, the mean Charnley pain and function scores at the most recent follow-up evaluation were 5.6 and 5.5 for the Taperloc group and 5.7 and 5.5 for the cemented control group (no significant difference) (Table 4). Fifty-one (98%) of the 52 patients who received the Taperloc prosthesis reported either no pain or only slight, occasional discomfort. Only one patient reported mild pain, which was controlled with nonsteroidal antiinflammatory medication, and no patient had more pain than they had had before surgery. Of the 52 patients who received the cemented prosthesis, only 1 (2%) had mild pain. There were no revisions in either group. Forty-six (88%) of the patients who received the Taperloc prosthesis had no limp, while six (12%) had a mild or moderate limp. Similarly, 47 (90%) of the patients who received the cemented prosthesis had no limp, while 5 (10%) had a mild or moderate limp. Radiographic evaluation also revealed that all of the femoral components in the Taperloc group were radiographically stable with no evidence of aseptic loosening or migration. No patient had complete demarcation of the porous-coated zone. Spot welds and calcar atrophy were identified in 5 1 of 52 (98%) components. Eight patients ( 15%) had a radiolucent line that involved less than 50% ot’ the porous surface. No component had a 100% radiolucent line. Radiographic evaluation of the cemented group was similarly benign, revealing all components to be stable with no evidence of aseptic loosening or migration.
CharnleyScore Preoperative Postoperative Pain Function Range
Femoral
Postoperative Cemented 3.0 2.9 3.2
NSD NSD NSD
Taperloc 5.6 5.5 5.5
Cemented 5.7 NSD 5.5 NSD 5.6 NSD
492
The Journal
of Arthroplasty
Vol. 9 No. 5 October
search into the biologic and mechanical causes of failure. Advancements in cementing techniques, such as pressurization, use of cement restrictors, and cement centrifugation, have lowered the failure rate, but there appears to be an irreducible minimum of failure. For a responsible hip surgeon to move away from using a cemented femoral component for THA, it is incumbent that they demonstrate enhanced results in terms of effectiveness and durability. Effectiveness is defined as relief of pain, restoration of function, and restoration of motion. Durability is delineated through the use of survivorship as defined radiographically, clinically, or by revision. We have demonstrated the effectiveness of the Taperloc stem equal to that of the cemented control group. The remaining burden is to prove long-term durability. It has been demonstrated by Engh and Massin,7x with substantial clinical support, that a stable biologic interface, once established, is not lost. That observation, together with the high level of effectiveness, in terms of pain relief and restoration of function, shown in this series, support the use of the biologically fixed Taperloc stem, while longer-term durability is being evaluated. While encouraging short-term data have been found,‘“,“,‘“,” the proof of permanent fixation has yet to be established. Imperfect relief of pain has been a problem commonly noted in cementlessseries.Several seriescomparing cemented and cementless implants have found lower hip scores, a higher incidence of pain, and higher loosening and revision rates with cementless implants.‘h,2’-3’ In contrast, other series have found no differences. 31p3hIn this series of both the initial 100 and matched patients, we found that the incidence of thigh pain, limp, and aseptic loosening were no greater with an uncemented Taperloc component than with a conventional cemented component fixed with modern cement techniques. These results may be related to several design features that are unique in this stem compared to most contemporary designs. These include a flat tapered wedge configuration that makes no effort to achieve anteroposterior fit and fill. Biomechanical studies in our laboratory indicate excellent axial and rotational stability with this design. 3h The lack of a collar is noteworthy and felt to enhance rotational stability. Similar flat-wedge shaped implants have been shown to be effective in both Europe” and the United States.“’ The overall rate of radiographic osseointegration was extremely high with this uncemented femoral component, which relies totally on mediolateral wedging, while disregarding proximal anteroposterior fit and fill. Although the follow-up period of the patients who
1994
received the uncemented Taperloc femoral component has been short, the results have been encouraging. No femoral component failed in either group, and there was no radiographic evidence of loosening. When low revision and failure rates are described in an implant seriessuch as this, it is incumbent to present a consecutive serieswith a high retrieval rate. By presenting the first 100 caseswith a 98% follow-up rate, substantial credence is given to the observed high durability within this time frame. On the basis of these data, we believe that the use of the uncemented Taperloc femoral stem has allowed us to achieve our two short-term goals: patient satisfaction and femoral implant osseointegration without cement. Studies with longer follow-up periods will be necessary to determine if, after achieving the short-term goals, a more enduring arthroplasty will result.
References I. JohnssonR, Thompson FG, PerssonBM: Revisionof total hip replacement for primary osteoarthritis. J Bone Joint Surg 70B:56, 197I 2. Salvati EA, Wilson PD Jr, Jolley MN et al: A ten-year follow-up study of our first one hundred consecutive Charnley total hip replacements.J Bone Joint Surg 63A:753, 1981 3. Stauffer RN: Ten-year follow-up study of total hip replacement: with particular reference to roentgenographic loosening of the components.J Bone Joint Surg 64A:983, 1982 4. Sutherland CJ, Wilde AH, Borden LS, Marks KE: A ten-year follow-up of one hundred consecutiveMiller curved-stem total hip replacement arthroplasties.J Bone Joint Surg 64A:970, 1982 5. Johnston RC, Crowninshield RD: Roentgenologicresults of total hip arthroplasty: a ten-year follow-up study. Clin Ortohp 181:92, 1983 6. Chandler HP, ReineckFT, Wixson RL, McCarthy JC: Total hip replacementin patientsyounger than thirty years old: a five-year follow-up study. J Bone Joint Surg 63A:1426, 1981 7. CollisDK: Cementedtotal hip replacementin patients who are lessthan fifty years old. .J Bone .Joint Surg 66A:353, 1984 8. Dorr LD, Takei GK, Conaty JP: Total hip arhtroplasties in patientslessthan forty-five years old. J BoneJoint Surg 65A:474, 1983 9. Ranawat CS, Atkinson RE, Salvati EA. Wilson PD Jr: Conventional total hip arthroplasty for degenerative joint diseasein patientsbetweenthe agesof forty and sixty years. J Bone Joint Surg 66A:745, 1984 10. Bobyn JD, Pilliar RM, Cameron HU, Weatherly GC: The optimum pore sizefor the fixation of porous-surfaced metal implants by the ingrowth of bone. Clin Orthop 150:263, 1980
Results
of the Taperloc
11. Cameron HU, Pilliar RM, MacNab I: The rate of bone ingrowth into porous metal. J Biomed Mater Res 10: 295, 1976 12. Engh CA: Hip arthroplasty with a moore prosthesis with porous coating: a five-year study. Clin Orthop 176:52, 1983 13. Galante J, Rostoker W, Lueck R, Ray RD: Sintered fiber metal composites as a basis for attachment of implants to bone. J Bone Joint Surg 53A:lOl, 1971 14. Lord G, Bancel P: The Madreporic cementless total hip arthroplasty: new experimental data and a seven-year clinical follow-up study. Clin Orthop 176:67, 1983 15. Ranawat C: Techniques in orthopaedics: bone ingrowth hip arthroplasty. Vol. 1. Aspen, Rockville, 1986 16. Maloney WJ, Harris WH: Comparison of a hybrid with an uncemented total hip replacement: a retrospective matched-pair study. J Bone Joint Surg 72A:134Y, 1990 17. Callaghan JJ, Dysart SH, Savory CG: The uncemented porous-coated anatomic total hip prosthesis: two-year results of a prospective consecutive series. J Bone Joint Surg 70A:337, 1988 18. Engh CA, Bobyn JD, Glassman AH: Porous-coated hip replacement: the factors governing bone ingrowth, stress shielding, and clinical results. J Bone Joint Surg 69B:45, 1987 19. Haddad RJ, Cook SD, Brinker MR: A comparison of three varieties of noncemented porous-coated hip replacements. J Bone Joint Surg 72B:2, 1990 20. Heiner JP, Evarts CM: Total knee arthroplasty: biological fixation, A preliminary report. Proceedings of the 54th Annual Meeting of the American Academy of Orthopaedic Surgeons. San Francisco, CA, January 1987 2 1. Rothman RH, Cohn JC: Cemented versus cementless total hip arthroplasty: a critical review. Clin Orthop 254: 153, 1990 22. Zweymuller KA, Lintner FK, Semlitsch MF: Biologic fixation of a press-fit titanium. Clin Orthop 235: 195, 1988 23. Charnley J: The long-term results of low friction arthroplasty of the hip performed as a primary intervention. J Bone Joint Surg 54B:61, 1972 24. Harris WH, McCarthy JC, O’Neill DA: Femoral com-
25.
26.
27.
28.
29.
30.
3 1.
32.
33.
34.
35.
36.
Femoral
Component
l
Hozack
et al.
493
ponem loosening using contemporary techniques of femoral cement fixation. J Bone Joint Surg 64A: 1064, 1982 Goodman SB, Schatzker J: Intermediate results of a straight-stem prosthesis in primary total hip arthroplasty. Clin Orthop 2 18: 1 11, 1987 Harris WH, McCann WA: Loosening of the femoral components after use of the medullary-plug cementing technique: follow-up note with a minimum five-year follow-up. J Bone Joint Surg 68A:1064, 1986 Ritter MA, Campbell ED: Long-term comparison of the Charnley, Miller, and Trapazoidal-28 total hip prosthesis: a survival analysis. J Arthroplasty 2:299, 1987 Engh CA, Massin P: Cementless total hip arthroplasty using the anatomic medullary locking stem. Clin Orthop 249:141, 1989 Knessel J, Gshwend N, Scheier H, Munzinge U: Comparative study of cemented and cementless hip prosthesis in the same patient. Arch Orthop Trauma Surg 108:276, I 989 Wixson RL, Stulberg SD, Mehlhoff M: Total hip replacement with cemented, uncemented, and hybrid prosthesis. J Bone Joint Surg 73A:257, 1991 Wykman A, Olsson E, Axdorph G, Goldie I: Total hip arthroplasty: a comparison between cemented and press fit noncemented fixation. J Arthroplasty 6:19, 1991 Eyb R, Schiller G, Feldner-Busztin H et al: Cemented and cementless total hip replacement in older patients. p. 98. Transactions of the American Academy of Orthopaedic Surgeons, Anaheim, CA, February 1991 Laupacis A, Bourne R, Rorabeck C et al: The effect of elective total hip replacement on health related quality of life. J Bone Joint Surg 75A: 1619, 1993 Rorabeck CH, Bourne RB, Nott L: Cemented versus non-cemented total hip: a preliminary report. J Bone Joint Surg 69B:508, 1987 Turula KB: Comparison of cemented and cementless total hip arthroplasty: a survivorship analysis. Acta Orthop Stand Suppl 60:231, 1989 Sharkey PF, Albert TJ, Hume EL, Rothman RH: Initial stability of a collarless wedge-shaped prosthesis in the femoral canal. Semin Arthroplasty 1:87, 1990
Taperloc
Femoral
of Arthroplasty
Vol. 9 No. 5 1994
Component
A 2-6-Year Study of the First 100 Consecutive Cases William Hozack, MD,*+ Robert Gardiner, MD,* Susan Hearn, MPT,-f Kennenth Eng, MS,+ and Richard Rothman, MD, PhD*t
Abstract: The first 100 consecutive patients who underwent insertion of the Taperloc (Biomet, Warsaw, IN) femoral stem were prospectively studied with a mean followup period of 3.8 years (range, 2-6 years). Two of the original 100 patients were lost, giving a 98% follow-up rate. The diagnoses included osteoarthritis (76 patients), avascular necrosis (19), rheumatoid arthritis (3). chrondrolysis (l), and post-traumatic arthritis ( I). The mean age at surgery was 56 years (range, 2 5-79 years), mean weight was 78 kg (range, 45-127 kg), and the female to male ratio was 29:71. Charnley pain and function scores were 3.0 and 2.8 before surgery and 5.5 and 5.4 after surgery. Thigh pain was present in 2% of the patients at the final follow-up evaluation. There were no revisions. Radiographic signs of bone-ingrowth fixation (calcar atrophy, spot welds) were seen in 92 of 94 components (98%). No component had complete demarcation of the porous-coated zones. Fifty-two of 94 patients were able to be matched for age, sex, weight, diagnosis, and length of follow-up period with a series of patients who received a contemporary cemented total hip. In this matched subset, the Charnley pain and function scores were 5.6 and 5.5 for the cementless Taperloc stem and 5.7 and 5.5 for the cemented control group; this is not a significant difference. These data indicate a clinical performance equivalent to a matched group of contemporary cemented total hip arthroplasties. Key words: hip, arthroplasty, uncemented, prosthesis, follow-up period, arthritis.
At present, controversy still exists concerning the optimal method of fixation for acetabular and femoral components in total hip arthroplasty (THA). Mechanical failure due to wear and aseptic loosening of cemented total hip components constitutes the most frequent cause of long-term failure. Aseptic loosening rates range from 1.5 to 19% in patients followed for 10 years or more.‘--5 Cemented THA in patients under the age of 60 has had even higher rates of loosening and revision.“-’ These findings have gcnerared interest in the use of biologic fixation as an alternative treatment method.
Early clinical trials have shown mixed results with regard to the biologic fixation of cementless femoral components,‘“p’5 and no long-term studies are available. Maloney and HarrisI noted a 24% incidence of pain, a 20% incidence of radiographic loosening, and a 16% incidence of femoral revision with an uncemented THA at 2-4 years. Callaghan ct al.” have shown a 16% incidence of thigh pain in 50 patients with an uncemented system followed for a minimum of 2 years. In a series of 307 uncemented Anatomic Medullary Locking (DePuy, Warsaw, IN) prostheses, Engh et al.18 noted a 14% incidence of thigh pain and a 2 I % incidence of limp. This substantial percentage of postoperative pain has not been reported by all authors, howeveI,.“‘-Jl At our institution, clinical experience with cementless femoral components has been quite favora-
*Pfpartmwt oJ’ Orihop~wd~Szrqfrv. .It~?r.wn Mrdkid Rollhman /nstirm, Philadflphia. Pfnr7svlvnni~7, and *Dickson-Divelfv Orthopfdic Clirlic. Kansas Cirv, Missouri. Reprint requests: William Hnrack. MD, The Rothman ln\titute. 800 Spruce Street. Philadelphia. PA 19107. From
School.
tirr
ti-he
489
490
The Journal
of Arthroplasty
Vol. 9 No. 5 October
ble.” The purpose of this study is to present the results of an initial, consecutive series of patients who were followed for a minimum of 2 years after undergoing a primary THA with an uncemented Taperloc femoral component (Biomet, Warsaw, IN). Second, these results are compared to a seriesof patients who underwent primary, cemented THA using a contemporary cemented system who were matched for age, sex, weight, diagnosis, and length of the follow-up period.
Materials
and
Methods
One hundred primary, uncemented femoral prostheses were inserted’ between December 1985 and January 1987. All patients received an uncemented, collarless, flat, tapered-wedge femoral component (Taperloc) with a titanium plasma spray circumferentially on the proximal 40%. The stem was used with both a regular and lateral offset design. The acetabular cup consisted of either a cemented, metal plasma-backed cup (70%) or an uncemented, titanium plasma-sprayed hemispheric cup fixed with screws (30%). The femoral head material used in this serieswas titanium alloy, although it has now been supplanted by either cobalt-chromium alloy or zirconium ceramic. The heads were modular, either 22 or 28 mm in size depending on the dimensions of the acetabulum. The average age of the patients was 56 years (range, 25-79 years). There were 7 1 men and 29 women. The preoperative diagnoses were osteoarthritis in 76 patients, avascular necrosis in 19, rheumatoid arthritis in 3, chondrolysis in 1, and posttraumatic arthritis in 1. Of the original 100 patients, 2 were lost and 4 died, leaving 94 patients available for review. The mean weight of these 94 patients was 78 kg (range, 45- 127 kg). The clinical outcome was graded using the Charnley modified scale of D’Aubigne and Postekz3 Before surgery, the mean Charnley pain and function scores were 3.0 (range, 2-5) and 2.8 (range, 2-6) (Table 1).
1994
All hip procedures were performed through either the direct lateral approach to the hip or the transtrochanteric approach, and were either performed or supervised by the senior author (R. R.). Patients were protected after surgery with two crutches for 12 weeks. The average length of the follow-up period was 3.8 years (range, 2-6 years). The immediate postoperative and all subsequent radiographs were reviewed for signs of femoral and acetabular component failure. Since the focus of this study is only on the femoral portion of the arthroplasty, the radiographic evaluation of the acetabular components has not been included. Vertical subsidence of the femoral component was measured by determining the change in distance from a fixed point on the femoral component to a fixed point on the proximal femur (usually the lesser trochanter). A decrease of 3 mm or more in the vertical direction was considered to indicate subsidence. Distal buttresses,radiolucencies about the femoral component, lossof proximal density, rounding of the calcar femoral, and spot welds were determined by studying sequential postoperative radiographs. All of the cemented femoral components were evaluated for loosening according to the criteria of Harris et al.L’ Definite loosening (subsidence 2 5 mm, cement-prosthesis radiolucency, cement fracture, component fracture, or shift in component position of 2 3 “), probable loosening (complete radiolucency of e 1 mm at the bone-cement interface), and possible loosening (> 50% radiolucency at the bone-cement interface) were recorded. In addition, 52 of the 94 patients were able to be matched for age, sex, weight, diagnosis, and length of the follow-up period with a controlled series of patients who underwent cemented THA using COIItemporary cemented femoral and acetabular components. Head sizeswere similar. The cement technique used was modern, with distal plugging of the canal, pulsatile lavage, centrifugation of cement, and pressurization. Surgical technique, postoperative regi-
Table Table
1. Demographics Taperloc
M/F Age (years) Weight (kg) Diagnoses Osteoarthritis Avascular necrosis Rheumatoid arthritis Other Follow-up period (years)
of Patients Stems
2. Demographics
Receiving
71129 68 (range. 78 (range. 76 19 3 2 3.8 (range,
of Patients Series
Cementless: Taperloc 60-74) 45-127)
2-6)
in the Matched
Cemented
k/F
34118 52
34,53 IX
Age (year>) Weight (kg) Follow-up period (years)
62 (range, 4H-7Y) 77 (range, 45-I 13) 3.8 (rang, 2-6)
67 (range, 48-79) 75 (range, 50- 1 13) 3.5 (range, 2-6)
Results Table
of the Taperloc
3. Results of the First 100 Taperloc Prostheses
5.5 5.4 5.6
3.0 2.8 3.1
of motion
men, and follow-up evaluations were identical between the two groups. The demographics of each group are shown in Table 2.
Statistics Student’s f-test was used to compare age, weight, and length of the follow-up period between the two matched groups. Wilcoxon’s two-sample test for nonparametric data was used to analyze the Charnley scores between the two groups.
Results The preliminary consecutive series of 94 patients who received the Taperloc femoral stem had excellent results both clinically and radiographically. The average postoperative Charnley pain and function scores for those patients were 5.5 (range, 2-6) and 5.4 (range, 2-6) (Table 3). Ninety-two (98%) of the 94 patients who received the Taperloc prosthesis reported having either no pain or only slight, occasional discomfort. Only two patients reported mild pain, which was controlled by nonsteroidal antiinflammatories, and no patient had more pain than they had had before surgery. Eightyfour (89%) of the patients who received the Taperloc prosthesis had no limp, while 10 (11%) had a mild or moderate limp. There were no revisions. Radiographic evaluation revealed that all of the femoral components were radiographically stable with no evidence of aseptic loosening or migration. No patient had complete demarcation of the porouscoated zone. Spot welds and calcar atrophy were
Table
Component
Pain Function Range NSD,
3.0 2.7 3.1
of motion no significant
differcncc.
Hozack
et al.
491
Discussion One of the most successful operations performed by orthopedic surgeons has been cemented THA. Yet, it has become apparent with longer follow-up periods that this procedure has imperfect durability. ‘,3~L’.15--17 Unfortunately, no method of stabilizing the bone-cement interface over long periods of time has been developed, in spite of considerable re-
4. Results of the Matched Series
Preoperative ‘raperloc
l
identified in 92 of 94 components (989/o), indicating excellent fixation. For the 52 patients who were matched, the mean Charnley pain and function scores at the most recent follow-up evaluation were 5.6 and 5.5 for the Taperloc group and 5.7 and 5.5 for the cemented control group (no significant difference) (Table 4). Fifty-one (98%) of the 52 patients who received the Taperloc prosthesis reported either no pain or only slight, occasional discomfort. Only one patient reported mild pain, which was controlled with nonsteroidal antiinflammatory medication, and no patient had more pain than they had had before surgery. Of the 52 patients who received the cemented prosthesis, only 1 (2%) had mild pain. There were no revisions in either group. Forty-six (88%) of the patients who received the Taperloc prosthesis had no limp, while six (12%) had a mild or moderate limp. Similarly, 47 (90%) of the patients who received the cemented prosthesis had no limp, while 5 (10%) had a mild or moderate limp. Radiographic evaluation also revealed that all of the femoral components in the Taperloc group were radiographically stable with no evidence of aseptic loosening or migration. No patient had complete demarcation of the porous-coated zone. Spot welds and calcar atrophy were identified in 5 1 of 52 (98%) components. Eight patients ( 15%) had a radiolucent line that involved less than 50% ot’ the porous surface. No component had a 100% radiolucent line. Radiographic evaluation of the cemented group was similarly benign, revealing all components to be stable with no evidence of aseptic loosening or migration.
CharnleyScore Preoperative Postoperative Pain Function Range
Femoral
Postoperative Cemented 3.0 2.9 3.2
NSD NSD NSD
Taperloc 5.6 5.5 5.5
Cemented 5.7 NSD 5.5 NSD 5.6 NSD
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search into the biologic and mechanical causes of failure. Advancements in cementing techniques, such as pressurization, use of cement restrictors, and cement centrifugation, have lowered the failure rate, but there appears to be an irreducible minimum of failure. For a responsible hip surgeon to move away from using a cemented femoral component for THA, it is incumbent that they demonstrate enhanced results in terms of effectiveness and durability. Effectiveness is defined as relief of pain, restoration of function, and restoration of motion. Durability is delineated through the use of survivorship as defined radiographically, clinically, or by revision. We have demonstrated the effectiveness of the Taperloc stem equal to that of the cemented control group. The remaining burden is to prove long-term durability. It has been demonstrated by Engh and Massin,7x with substantial clinical support, that a stable biologic interface, once established, is not lost. That observation, together with the high level of effectiveness, in terms of pain relief and restoration of function, shown in this series, support the use of the biologically fixed Taperloc stem, while longer-term durability is being evaluated. While encouraging short-term data have been found,‘“,“,‘“,” the proof of permanent fixation has yet to be established. Imperfect relief of pain has been a problem commonly noted in cementlessseries.Several seriescomparing cemented and cementless implants have found lower hip scores, a higher incidence of pain, and higher loosening and revision rates with cementless implants.‘h,2’-3’ In contrast, other series have found no differences. 31p3hIn this series of both the initial 100 and matched patients, we found that the incidence of thigh pain, limp, and aseptic loosening were no greater with an uncemented Taperloc component than with a conventional cemented component fixed with modern cement techniques. These results may be related to several design features that are unique in this stem compared to most contemporary designs. These include a flat tapered wedge configuration that makes no effort to achieve anteroposterior fit and fill. Biomechanical studies in our laboratory indicate excellent axial and rotational stability with this design. 3h The lack of a collar is noteworthy and felt to enhance rotational stability. Similar flat-wedge shaped implants have been shown to be effective in both Europe” and the United States.“’ The overall rate of radiographic osseointegration was extremely high with this uncemented femoral component, which relies totally on mediolateral wedging, while disregarding proximal anteroposterior fit and fill. Although the follow-up period of the patients who
1994
received the uncemented Taperloc femoral component has been short, the results have been encouraging. No femoral component failed in either group, and there was no radiographic evidence of loosening. When low revision and failure rates are described in an implant seriessuch as this, it is incumbent to present a consecutive serieswith a high retrieval rate. By presenting the first 100 caseswith a 98% follow-up rate, substantial credence is given to the observed high durability within this time frame. On the basis of these data, we believe that the use of the uncemented Taperloc femoral stem has allowed us to achieve our two short-term goals: patient satisfaction and femoral implant osseointegration without cement. Studies with longer follow-up periods will be necessary to determine if, after achieving the short-term goals, a more enduring arthroplasty will result.
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Results
of the Taperloc
11. Cameron HU, Pilliar RM, MacNab I: The rate of bone ingrowth into porous metal. J Biomed Mater Res 10: 295, 1976 12. Engh CA: Hip arthroplasty with a moore prosthesis with porous coating: a five-year study. Clin Orthop 176:52, 1983 13. Galante J, Rostoker W, Lueck R, Ray RD: Sintered fiber metal composites as a basis for attachment of implants to bone. J Bone Joint Surg 53A:lOl, 1971 14. Lord G, Bancel P: The Madreporic cementless total hip arthroplasty: new experimental data and a seven-year clinical follow-up study. Clin Orthop 176:67, 1983 15. Ranawat C: Techniques in orthopaedics: bone ingrowth hip arthroplasty. Vol. 1. Aspen, Rockville, 1986 16. Maloney WJ, Harris WH: Comparison of a hybrid with an uncemented total hip replacement: a retrospective matched-pair study. J Bone Joint Surg 72A:134Y, 1990 17. Callaghan JJ, Dysart SH, Savory CG: The uncemented porous-coated anatomic total hip prosthesis: two-year results of a prospective consecutive series. J Bone Joint Surg 70A:337, 1988 18. Engh CA, Bobyn JD, Glassman AH: Porous-coated hip replacement: the factors governing bone ingrowth, stress shielding, and clinical results. J Bone Joint Surg 69B:45, 1987 19. Haddad RJ, Cook SD, Brinker MR: A comparison of three varieties of noncemented porous-coated hip replacements. J Bone Joint Surg 72B:2, 1990 20. Heiner JP, Evarts CM: Total knee arthroplasty: biological fixation, A preliminary report. Proceedings of the 54th Annual Meeting of the American Academy of Orthopaedic Surgeons. San Francisco, CA, January 1987 2 1. Rothman RH, Cohn JC: Cemented versus cementless total hip arthroplasty: a critical review. Clin Orthop 254: 153, 1990 22. Zweymuller KA, Lintner FK, Semlitsch MF: Biologic fixation of a press-fit titanium. Clin Orthop 235: 195, 1988 23. Charnley J: The long-term results of low friction arthroplasty of the hip performed as a primary intervention. J Bone Joint Surg 54B:61, 1972 24. Harris WH, McCarthy JC, O’Neill DA: Femoral com-
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