The Basis CL cemented femoral stem: results after 8.9 years follow-up

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1 Hip Int 2013; 23 ( 2) : DOI: /HIP Original Article The Basis CL cemented femoral stem: results after 8.9 years follow-up Sabine Mai, Matthias Golla, Werner E. Siebert Vitos Orthopaedic Clinic Kassel, Kassel - Germany Abstract: This prospective study was conducted to demonstrate that the matte-finish Basis CL cemented endoprosthetic stem delivers good qualitative results after 10 years. Between January and December 1999, 205 consecutive hips (201 patients; 74.5 ± 6.8 years at surgery) underwent primary total hip arthroplasty with the Basis CL and the same acetabular cup (RM Classic cup) at a single institution. Follow-up data at 10 years was available for 120 hips (average follow-up of 8.9 years, ±2.9). Mean Harris Hip Score improved from 39.5 ± 16.8 at baseline to 75.9 ± 16.7 at 10-year follow-up (p<0.001). Four hips required revision during the study: three for infection and one for pain. There were no cases of aseptic loosening, implant migration, or stem fracture. Cumulative survival at 10 years was 97.4% with the endpoint of revision for any reason. In conclusion, results with the mattefinish cemented Basis CL indicated that it was safe and effective after medium-term follow-up. Key words: Basis CL, Total hip arthroplasty, Cemented, Matte-finish, Survival Accepted: November 21, 2012 INTRODUCTION Although total hip arthroplasty (THA) commonly results in quality medium- and long-term outcomes, the question of whether cemented or uncemented components represent the superior fixation method currently remains unsettled. National registry data have indicated that improved survival can be obtained with cemented components (1, 2), but randomised controlled trials comparing the two fixation methods dispute this (3, 4). Furthermore, the question of whether roughened surfaces are effective for cemented femoral components also remains a topic of debate (5, 6). The Basis CL cemented endoprosthetic stem (Smith & Nephew Orthopaedics AG, Baar, Switzerland) (Fig. 1), formerly known as the Marathon (Smith & Nephew Orthopaedics GmbH), was developed for the treatment of coxarthroses. The surface of this femoral implant is blasted using glass beads, which forms a fine matte finish to create a permanent connection between the subtly roughened stem surface and the cement mantle. This prospective 10-year study was conducted to analyse the safety and efficacy of the Basis CL in consecutive patients undergoing THA. It was hypothesised that the use of this matte-finish cemented femoral stem would lead to good survival and clinical outcomes after a decade of use, with no significant problems encountered upon radiological review. This is the first study to offer results with this system. METHODS Between January and December 1999, 201 consecutive patients (205 hips; Tab. I) underwent primary THA with the Basis CL endoprosthetic shaft performed by multiple surgeons at a single institution in Germany. No exclusion criteria were employed for this analysis. Hips were implanted using the following approaches: transgluteal (180), dorsal (16), or anterolateral (9). Spinal anaesthesia was administered to all patients. 147

2 Basis stem: up to 11-year follow-up TABLE I - PATIENT DEMOGRAPHICS Mean age at surgery, years (range) 74.5 ± 6.8 (61-96) Female patients, N (%) 149 (72.7) Mean body mass index (range) 26.5 ± 4.4 ( ) Mean operating time, minutes (range) 89.7 ± 29.3 (35-240) Operated side, left (%)/right (%) 97 (47.3)/108 (52.7) Diagnosis N % Osteoarthritis 165 (80.5) Inflammation/arthritis 8 (3.9) Fracture 22 (10.7) Dysplasia 5 (2.4) Necrosis 5 (2.4) The acetabulum was prepared with reamers. Additional screws were used to support primary fixation in all cases. Fig. 1 - Basis CL stem. At the time of this study, ethics committee approval was not necessary for observation studies with non-interventional designs. However, all participants signed an informed consent form indicating their willingness to participate. The cemented stems were available in sizes 1 (32 hips), 2 (78 hips), 3 (64 hips), 4 (24 hips), and 5 (seven hips). The femoral ball head was a CoCr Femoral Head ASTM F-799 (Smith & Nephew Orthopaedics AG) in 203 hips and a Biolox (Biomet Orthopedics, Warsaw, Indiana, USA) in two hips. The head size was 28 mm in 204 hips and 32 mm in one hip. Femoral preparation was undertaken by opening the femoral canal with a box chisel and a blunt medullary reamer and broaching the femur. A trial reduction was performed, after which point the femoral canal was brushed, jet lavaged, and dried. The femoral canal was then filled with vacuum-mixed bone-cements (Palacos, Zimmer, Warsaw, Indiana, USA) applied in a retrograde manner. In all cases the Basis CL stem was paired with a hemispherically designed RM Classic cup (Mathys Medical, Bettlach, Switzerland). Cup sizes ranged from 50 to 62. Clinical analysis Clinical assessments occurred preoperatively and postoperatively at six months, and one, two, five, and 10 years. At each of these time points, Harris Hip Score (7) was recorded for all available patients, who were also asked about their satisfaction with their procedure. Radiological analysis Radiography was performed postoperatively and at six months, and one, two, five, and 10 years. The radiographs were examined independently. Radiolucent lines were defined according to the system of Gruen (8). Possible loosening was defined as the appearance of a radiolucent line 2 mm. Implant alignment was assessed manually directly from the films. The inclination angle of the cup was measured by determining the angle between the line connecting the two tear drops and the line connecting the upper and lower end of the open plane of the cup on the antero-posterior radiograph. Subsidence was measured using a digital ruler, which was calibrated with head diameter (9). Heterotopic ossification was assessed using the grading system of Brooker et al (10). 148

3 Mai et al Statistical analysis Kaplan-Meier survival analysis curves were created utilising 95% confidence intervals (CI) (11). Statistical analysis was undertaken using Statistica 9 (StatSoft, Tulsa, Oklahoma, USA). Two-sided p values of <0.05 were considered to indicate significance. RESULTS Mean follow-up was 8.9 years (±2.9). Clinical follow-up information was available for 204 hips at six months, 199 at one year, 175 at five years, and 120 at 10 years, with x-ray data at 10 years available for 59 hips. Seventy-eight hips (38%) were lost to death prior to 10 years. Four implants (2.0%) required a change of prosthesis during the 10-year period: three due to infection and one due to pain. There was no postoperative loosening or revision of the cup reported. Two (1.0%) patients could not be contacted for follow-up and one (0.5%) refused to further participate. This left 120 hips (58.5%) with follow-up data at 10 years. There were 4 intraoperative complications. In two cases it was observed upon closing of the suture that the cup was improperly seated against the bone, necessitating a reopening of the suture and revision of the cup position within the same anesthesia. In the two other hips, trochanteric fracture occurred and was treated with readaption of the trochanter. Postoperative complications are provided in Table II. Clinical outcomes At 10 years, 115 patients were satisfied with their operation and 5 were not satisfied without giving further explanation; 112 said that they would undergo the procedure again and eight said they would not. Mean Harris Hip Score improved from 39.5 ± 16.8 at baseline to 75.9 ± 16.7 at 10-year follow-up (p<0.001; Tab. III). Radiographic outcomes Of the 59 stems with available data, five had radiolucent lines present in one or more zones (Tab. IV). Average cup inclination was 36.8 (standard deviation, 7.4; range, 20-52). There were no signs of loosening or osteolysis. Fifty-two stems had neutral positioning, with two in varus and five in valgus. At final follow-up, no stems had measurable migration. No stem fractures occurred. Thirty-six patients (61%) did not show any sign of ossification. Heterotopic ossification was noted in 23 hips and rated into the following classes: I (11 hips); II (eight hips); III (three hips); and IV (one hip). Survivorship Cumulative survival at 10 years was 97.4% (95% CI: ) with the endpoint of revision for any reason (Fig. 2). No aseptic loosenings were reported. DISCUSSION Findings with the Basis CL were very encouraging, with a 10-year survival rate of 97.4% with revision for any reason TABLE II - COMPLICATIONS NOTED AT CLINICAL FOLLOW- UP POINTS Follow-up point Intraoperative complications Complications Trochanteric fracture 2 Cup revisions: 2 Discharge Seroma: 1 Dislocation: 10 Hematoma: 6 Nerve damage: 2 (femoralis) Wound healing disorder: 15 Discharge General complications Death: 3 Thrombosis: 4 Pneumonia: 2 Embolism:1 6 months Dislocation: 2 Periprosthetic fracture: 1 Thrombosis: 2 Operation of bursa and tractus: 1 Removal of periarticular ossification: 1 year Dislocation: 1 Reoperation including head exchange due to pain: 1 (same patient who had a bursitis at 6 months) 2 years Removal ofossification 5 year Dislocation (patient with dementia): 1 Revison: 2 10 years Revison: 2 149

4 Basis stem: up to 11-year follow-up TABLE III - HARRIS HIP SCORE DATA AT BASELINE (n = 204) AND AT THE 1-YEAR (n = 199), 5-YEAR (n = 175), AND 10-YEAR (n = 120) FOLLOW-UP VISITS Outcome Baseline Mean, 1 Year Mean, 5 Year Mean, 10 Year Mean, P value (dependent t-test) o Baseline to 1 year o Baseline to 10 year o 1 year to 10 year Pain 9.8 ± 11 (0-44) 37.2 ± 9.7 (10-44) 38.2 ± 10.9 (0-44) 38.4 ± 9.6 (0-44) o 0.0 o 0.4 Gait 16.5 ± ± ± ± 10 o 0.05 Activities 8.5 ± 2.9 (0-14) 10.8 ± 2.9 (0-14) 10.2 ± 3.4 (0-14) 10.4 ± 2.8 (2-14) o 0.39 Function 24.9 ± 10 (0-46) 34.7 ± 10.7 (0-47) 31.8 ± 13.3 (0-47) 31.9 ± 12.3 (5-47) o 0.08 Total Harris Hip Score 39.5 ± 16.8 (8-90) 77.4 ± 17 (17-98) 75.6 ± 19.6 (7-98) 75.9 ± 16.7 (10-98) o 0.5 SD = standard deviation. TABLE IV - RADIOLUCENT LINES (MM) SURROUNDING THE STEM (n = 59) Zone Stable Progressive New , 1.1 Fig. 2 - Kaplan-Meier survival curve for the endpoint of revision for any reason. as the endpoint. This is higher than that observed in the published reports of national THA registries, which indicate a 10-year survival for cemented prostheses within the range of 88% to 95% (1). The high rate of dislocations occurring before discharge has a few possible explanations. A posterior approach was initially used by one of the surgeons, but after being noted to have a possible (yet not statistically significant) association with dislocation, it was thereafter discontinued. Additionally, all but one of the 10 dislocations occurred in patients receiving a 28 mm femoral ball head, which was in line with common practices at the start of this study; however, today 32 mm heads are mostly used. As the surgeons became more experienced with this product, the dislocation rate may also have been favourably impacted. Clinical data were also highly supportive of the Basis CL, with all outcomes showing significant increases from baseline. Clinical outcome measures have been shown to peak 2-to-5 years after THA and gradually decline thereafter 150

5 Mai et al (12). That outcome scores in our analysis were nearly identical at five and 10 years is therefore an encouraging sign that this clinical performance can be maintained. Poor outcomes were routinely noted for early-generation cemented THA (13). In the intervening years, however, improvements in implant designs and cement techniques have significantly reduced the risk of aseptic loosening and led to robust survival with up to three decades of follow-up (14-17). Jet lavage cement retrograde application of vacuummixed cement and cement pressurization, as employed with the Basis CL, is one such enhanced cementing technique that potentially leads to improvement in femoral implant survival (18). The stability of the Basis CL s cementing technique would appear to be reinforced by the current results, particularly the notable lack of migration at final follow-up, although available long-term data in this area were limited. Cemented stems are thought to most likely fail after late migration (19), and therefore the risk of aseptic loosening will have to be monitored past the decade threshold. The question of which is the best surface finish for cemented femoral components, polished or roughened, also remains controversial (5, 6). In general, polished (smooth) and roughened (matte or grit blasted) surfaces are designed to either minimise or enhance interfacial sheer strength, respectively, with resulting prevention of cement abrasion damage and component loosening (20). Randomised survival analyses have revealed no significant differences between these surfaces in components with a similar geometry (6, 21). Nonetheless, there appears to be a preference towards polished cemented stems in the literature (20, 22, 23), which is due in part to past clinical experience with the Exeter femoral stem (Stryker, Warsaw, Indiana, USA). The original design of the Exeter utilised a polished surface and produced generally encouraging long-term results (24, 25). In 1976, the Exeter transitioned to a matte-finish surface and notably high rates of loosening and revision were observed (26-29). This was attributed to the matte surface s negative impact on load transmission as well as the production of debris when the surface fretted against the cement mantle (28, 29). Results with the Exeter improved considerably following the return to a polished surface design in 1986 (26), and polished surfaces are now considered by many to be the superior option in cemented THA. In particular, cemented collarless polished tapered stems have been offered as a reference standard against which other femoral components should be compared (30). The Exeter Universal (Stryker Inc, Newbury, UK), a pol- ished, double-tapered stem, has performed as well as any published cemented implant in recent years, with stem survivorship rates of approximately 94.9% and 100% noted with the endpoints of revision for any reason or revision for aseptic loosening, respectively, after approximately 12 years of use (31, 32). Although these studies do not offer an exact overlap of follow-up periods with the current analysis, they nonetheless show that the Basis CL produces medium-term outcomes comparable with the best cemented femoral components. Our results are in line with other studies with matte-surface stems at follow-up times of more than a decade (15-17). Although derived from a limited patient cohort, the fact that our radiographic analysis revealed no signs of migration or subsidence further indicates the viability of this surface. This challenges the assumption that matte-surface femoral stems are inferior and indicates that additional factors such as patient selection and cementing technique may prove more important for determining long-term performance (6). This study has several limitations. Firstly, patients were operated upon by multiple surgeons, creating a potential bias by mixing different surgical modalities with a possible impact on the results. The fact that all patients received identical components, however, nullifies the cup as a source of potential bias. Secondly, radiographic data were available for only 59 patients at 10 years. Information from a larger cohort of patients is likely necessary to fully gauge the impact of this prosthesis system on our chosen radiographic endpoints. The high number of patients un available for radiographic analysis was somewhat unavoidable given the average age at surgery in our cohort (74.5 years; range 61-96). This is an accurate reflection of current practices, as cemented stems are more commonly used in elderly patients than uncemented stems. However, it also led to an unfortunately elevated rate of death at 10-year followup, and an increased likelihood that elderly patients would abstain from undergoing x-rays given their general health, personal preference, or because the observational nature of this study allowed them to undergo follow-up at separate locations. Lastly, it must be noted that subsidence was measured using a digital ruler, although superior methods for measuring this variable have since become available. In conclusion, 10-year outcomes with the matte-finish Basis CL attest to the safety and utility of this device, with survival rates well within the range noted for other highperforming cemented prostheses. Although derived from a limited number of patients, the lack of implant migration 151

6 Basis stem: up to 11-year follow-up and relatively small percentage of progressive radiolucent lines also support the use of this implant design in THA. Further follow-up will be needed to track the development of these outcomes in the long term. Financial support: No financial support. Conflict of interest: The authors do not have any conflict of interest. Address for correspondence: Dr. Sabine Mai Vitos Orthopädische Klinik Kassel Wilhelmshöher Allee 345 D Kassel, Germany REFERENCES 1. Corbett KL, Losina E, Nti AA, Prokopetz JJ, Katz JN. Population-based rates of revision of primary total hip arthroplasty: a systematic review. PLoS One. 2010;5(10):e Hailer NP, Garellick G, Kärrholm J. Uncemented and cemented primary total hip arthroplasty in the Swedish Hip Arthroplasty Register. Acta Orthop. 2010;81(1): Corten K, Bourne RB, Charron KD, Au K, Rorabeck CH. Comparison of total hip arthroplasty performed with and without cement: a randomized trial. A concise follow-up, at twenty years, of previous reports. J Bone Joint Surg Am. 2011;93(14): Corten K, Bourne RB, Charron KD, Au K, Rorabeck CH. What works best, a cemented or cementless primary total hip arthroplasty?: minimum 17-year followup of a randomized controlled trial. Clin Orthop Relat Res. 2011;469(1): Firestone DE, Callaghan JJ, Liu SS, et al. Total hip arthroplasty with a cemented, polished, collared femoral stem and a cementless acetabular component. A follow-up study at a minimum of ten years. J Bone Joint Surg Am. 2007;89(1): Lachiewicz PF, Kelley SS, Soileau ES. Survival of polished compared with precoated roughened cemented femoral components. A prospective, randomized study. J Bone Joint Surg Am. 2008;90(7): Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fracture: treatment by mold arthroplasty. J Bone Joint Surg Am. 1969;51(4): Gruen TA, McNeice GM, Amstutz HC. Modes of failure of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop Relat Res. 1979;(141): Loudon JR, Charnley J. Subsidence of the femoral prosthesis in total hip replacement in realtion to the design of the stem. J Bone Joint Surg Br. 1980;62(4): Brooker AF, Bowerman JW, Robinson RA, Riley LH Jr. Ectopic ossification following total hip replacement: incidence and a method of classification. J Bone Joint Surg Am. 1973;55(8): Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc. 1958;53: Röder C, Parvizi J, Eggli S, Berry DJ, Müller ME, Busato A. Demographic factors affecting long-term outcome of total hip arthroplasty. Clin Orthop Relat Res. 2003;(417): Yamada H, Yoshihara Y, Henmi O, et al. Cementless total hip replacement: past, present, and future. J Orthop Sci. 2009;14(2): Barrack RL, Mulroy RD Jr, Harris WH. Improved cementing techniques and femoral component loosening in young patients with hip arthroplasties: a 12-year radiographic review. J Bone Joint Surg Br. 1992;74(3): Callaghan JJ, Liu SS, Firestone DE, et al. Total hip arthroplasty with cement and use of a collared matte-finish femoral component: nineteen to twenty-year follow-up. J Bone Joint Surg Am. 2008;90(2): Sanchez-Sotelo J, Berry DJ, Harmsen S. Long-term results of use of collared matte-finished femoral component fixed with second-generation cementing techniques: a fifteen-year-median follow-up study. J Bone Joint Surg Am. 2002;84(9): Skutek M, Bourne RB, Rorabeck CH, Burns A, Kearns S, Krishna G. The twenty to twenty-five-year outcomes of the Harris design-2 matte-finished cemented total hip replacement: a concise follow-up of a previous report. J Bone Joint Surg Am. 2007;89(4): Breusch SJ, Norman TL, Schneider U, Reitzel T, Blaha JD, Lukoschek M. Lavage technique in total hip arthroplasty: Jet lavage produces better cement penetration than syringe lavage in the proximal femur. J Arthroplasty. 2000;15(7): Kroell A, Beaulé P, Krismer M, Behensky H, Stoeckl B, Biedermann R. Aseptic stem loosening in primary THA: migration analysis of cemented and cementless fixation. Int Orthop. 2009;33(6): Iesaka K, Jaffe WL, Kummer FJ. Integrity of the stem-cement interface in THA: effects of stem surface finish and cement porosity. J Biomed Mater Res B Appl Biomater. 2008;87(1): Vail TP, Goetz D, Tanzer M, Fisher DA, Mohler CG, Callaghan JJ. A prospective randomized trial of cemented femoral components with polished versus grit-blasted surface finish and identical stem geometry. J Arthroplasty 2003;18(7 Suppl 1): Mirza SB, Dunlop DG, Panesar SS, Naqvi SG, Gangoo S, Salih S. Basic science considerations in primary total hip replacement arthroplasty. Open Orthop J. 2010;4: Scheerlinck T, Casteleyn PP. The design features of cemented femoral hip implants. J Bone Joint Surg Br. 2006; 88(11):

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