Elderly patients undergoing total hip arthroplasty (THA) present greater challenges than younger patients owing to high perioperative morbidity and poor bone quality.1 It has become the standard to use conventional uncemented femoral stems in younger patients because of the good clinical outcomes.2 However, the best form of femoral fixation in elderly patients remains debatable. Ranawat et al3 cited a higher learning curve, longer recovery time, greater incidence of thigh pain, higher cost, and more difficult revision as reasons to avoid uncemented THA in patients older than 60 years. Conversely, Engh and Leung2 suggested that uncemented THAs are preferred for patients older than 60 years because of their predictable survivorship (95% beyond 10 years) and ease of implantation. Several other studies3–5 suggested that uncemented femoral stems should be avoided in octogenarians owing to an increased risk for aseptic loosening due to poor bone quality, higher prevalence of thigh pain, higher risk of periprosthetic fracture intraoperatively and postoperatively, and more difficulty in revision. Furthermore, several nationwide register-based studies reported that a high incidence of early aseptic loosening of uncemented femoral stems was found in octogenarians.6–8 The Finnish Arthroplasty Registry determined the type of fixation (cemented, hybrid, cementless) and suggested that hybrid fixation (a cemented stem and a cementless cup) had better long-term results than cementless fixation of the stem in octogenarians.8
An ultra-short anatomic uncemented femoral stem was developed to reduce the risk of fat embolism, thigh pain, periprosthetic fracture, stress shielding related to bone resorption, and revision of the components.9,10 It requires less resection of the upper femur and/or less reaming of the femoral shaft. This serves a dual purpose of facilitating future revision while providing a postoperative state closely mimicking that of the originally functioning hip. It has been questioned whether secure fixation of the ultra-short anatomic uncemented femoral stem can be obtained without diaphyseal stem fixation in octogenarians. Older patients may have altered bone quality, as well as decreased bone metabolism and remodeling, Therefore, the fixation and stability of these ultra-short cementless implants are potentially compromised in these patients.
The aim of this study was to determine how ultra-short anatomic vs cemented (uncemented acetabular component) femoral stems affect the survival of primary THAs in octogenarians. Specifically, the authors investigated whether ultra-short anatomic and cemented femoral components would provide similar (1) functional results, (2) radiographic results, (3) revision and survival rates, and (4) complication rates in octogenarians.
Materials and Methods
From January 2001 to December 2004, a total of 155 primary THAs using a cemented stem were performed in 143 consecutive octogenarians. From January 2005 to December 2007, a total of 135 primary THAs using an ultra-short anatomic uncemented stem were performed in 128 consecutive octogenarians. These patients were prospectively followed, and their data were retrospectively analyzed. The study received institutional review board approval, and informed consent was obtained from each patient. In the ultra-short anatomic uncemented stem group, 30 patients were lost to follow-up before 2 years postoperatively and 20 patients died in the interim. In the cemented stem group, 37 patients were lost to follow-up and 13 patients died in the interim. Consequently, the authors evaluated 93 consecutive octogenarians (98 hips) in the ultra-short anatomic uncemented stem group and 78 consecutive octogenarians (92 hips) in the cemented stem group. The octogenarians with an ultra-short anatomic stem cohort consisted of 25 men and 68 women. Their mean age was 86.5±5.3 years (range, 80–89 years), and their average body mass index was 28.1 kg/m2 (range, 24–38 kg/m2). The octogenarians with a cemented stem consisted of 35 men and 43 women. Their mean age was 85.7±5.8 years (range, 80–89 years), and their average body mass index was 28.5 kg/m2 (range, 23–37 kg/m2). The American Society of Anesthesiologists physical status classification system was used to measure the overall health status of each patient. The mean American Society of Anesthesiologists score of the octogenarians in the ultra-short stem group was 3.1, compared with 2.8 in the cemented stem group (P=.368). The predominant diagnoses for THA were osteoarthritis followed by osteonecrosis in both groups (Table 1).
All of the operations were performed by the senior author (Y.-H.K.) using a posterolateral approach. Uncemented Duraloc 100 or 1200 series of acetabular component (DePuy, Warsaw, Indiana) was press-fitted. The 28-mm BIOLOX Forte ceramic liner (CeramTec AG, Polchingen, Germany) was used in the ultra-short stem group, and a 22-mm conventional polyethylene liner was used in the cemented group. The cup sizes ranged from 48 to 58 mm. The authors intended to fix the cup between 35° and 45° abduction and between 20° and 30° anteversion. A ceramic-on-ceramic bearing was chosen for this elderly group. Although these patients had a low activity level, they were doing excessive squatting and sitting on the floor during daily activity, which was causing excessive impingement between the femoral neck and the rim of the acetabular polyethylene liner. This excessive impingement potentially leads to excessive wear of the polyethylene liner. A total of 93 patients received an ultra-short anatomic uncemented femoral stem (Proxima; DePuy) with a 28-mm BIOLOX Forte ceramic modular head (CeramTec AG). A total of 78 patients received an Elite Plus cemented femoral stem (DePuy) with a 22-mm zirconia ceramic modular head. A 22-mm zirconia ceramic modular head was used because a 28-mm ceramic head was not available at the time of the operation. The ultra-short stem is made of titanium alloy. It is entirely porous coated with sintered titanium beads having a mean pore size of 250 µm, to which a 30-µm–thick hydroxyapatite coating is applied, except for the distal tip. The design features include a longer proximomedial portion of the stem, a highly pronounced lateral flare, and preservation of the femoral neck. The Charnley Elite-Plus stem (Ortron 90; DePuy) is straight and has a smooth surface.
The first generation of cephalosporin antibiotics was administered for 24 hours for prophylaxis of infection. A mechanical compression device was applied for 14 days for thromboprophylaxis.
On the second postoperative day, patients in both groups started walking with full weight bearing using crutches or a walker. They used crutches or a walker for 4 to 6 weeks and a cane thereafter as needed.
Follow-up examinations of the patients were conducted at 3 months and 1 year postoperatively and 2 or 3 years thereafter. The Harris hip score11 and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score12 were assessed preoperatively and at each follow-up visit. Thigh pain was scored on a 10-point visual analog scale, with 0 meaning no pain and 10 meaning severe pain. The University of California, Los Angeles (UCLA) activity score was used to assess activity level at each follow-up visit.13 A research associate who was not part of the surgical team analyzed all of these data. The average follow-up was 8.1 years (range, 5–12 years) for the patients with an ultra-short stem and 7.8 years (range, 5–11 years) for the patients with a cemented stem.
Anteroposterior and cross-table lateral radiographs in supine position were obtained at 7 or 8 days postoperatively and at each follow-up examination. The morphology of the femur was assessed before surgery according to Dorr's classification system.14 The position of the femoral component was assessed in the anteroposterior and lateral planes of radiographs. Neutral position of the ultra-short stem was defined as the angle of the stem neck with the femoral shaft and that of the stem neck with the stem being equal or ±3°. Varus of the ultra-short stem was defined as the angle of the stem neck with the femoral shaft being smaller than the angle of the stem neck with the stem. Valgus of the ultra-short stem was defined as the angle of the stem neck with the femoral shaft being larger than the angle of the stem neck with the stem. Anteverted ultra-short stem was defined as the angle of the stem neck with the femoral shaft being smaller than the angle of the stem neck with the stem on cross-table lateral radiograph. Neutral position of the cemented stem was defined as the angle of the longitudinal axis of the stem and the femoral canal being less than ±3°. Varus of the cemented stem was defined as the angle of the longitudinal axis of the stem and the femoral shaft being greater than 3° medially. Valgus of the cemented stem was defined as the angle of the longitudinal axis of the stem and the femoral shaft being greater than 3° laterally.
Center of rotation of the femoral head was measured. A horizontal line was constructed to connect the inferior margin of both teardrops on the anteroposterior pelvic radiograph. Vertical lines were constructed to bisect the teardrops and extend superiorly. The centers of the femoral heads were located, and the horizontal and vertical distances from the teardrops to the center of the femoral head were determined. The horizontal and vertical coordinates provided a recording of the center of rotation of the hip. Femoral offset was measured. The perpendicular distance from the neutral long axis of the femur and the center of the femoral head was determined. Abductor moment arm was estimated by drawing a line between the anterior–superior and posterior–superior iliac spine. A line was drawn from a point one-third of the distance between the posterior–superior to the anterior–superior iliac spine to the tip of the greater trochanter. This approximated the line of the pull of the abductor muscles. A perpendicular line was then constructed from the center of rotation of the femoral head to this line, and its length represented the abductor moment arm (Figures 1–2).
Postoperative anteroposterior (left) and lateral (right) radiographs assessing the position of the implant. The position of the stem in the anteroposterior plane was determined by comparing the angle of the anteroposterior prosthetic neck–femoral shaft (a) with the angle of the prosthetic neck–stem (b) (130°). In neutral position, a equals b (or they are within 3° of each other). In varus position, a is less than b. In valgus position, a is greater than b. The position of the stem in the lateral plane was determined by comparing the angle of the lateral prosthetic neck–femoral shaft (c) with the angle of the lateral prosthetic neck–shaft (d) (5°). In anatomical position, c equals d (or they are within 3° of each other). In anteverted position, c is less than d.
Postoperative anteroposterior (left) and lateral (right) radiographs. The cup inclination angle is the angle between the plane through the opening of the cup and the horizontal plane (A–C). The cup anteversion angle is the angle formed by the bottom of the radiographic plate, representing the posterior plane of the condyles, and the opening plane of the cup (Fa,b,c). The stem position is the angle formed by the central axis of the femoral shaft and the central axis of the femoral stem (E). Neutral position is when the angle is 0°. The stem anteversion angle is the angle formed by the bottom of the radiographic plate, representing the posterior plane of the condyles, and the axis of the prosthesis neck (G). The cup offset is the distance from the center of rotation of the femoral head to the teardrop (B). The stem offset is the distance from the center of rotation of the femoral head to the central axis of the femur (A). The height of hip rotation center is the distance from the center of rotation of the femoral head to a perpendicular line to the femoral axis at the tip of the greater trochanter (D). The radiographic leg length is the distance from the interischial line to the apex of the lesser trochanter.
A research associate who was not involved in the operation assessed radiographic stability of the components. The stability of the femoral component was classified for the ultra-short uncemented stem according to the criteria of Engh et al15 as osseointegrated, fibrous stable, or unstable. Definite loosening was defined as a progressive axial subsidence of the femoral stem of more than 3 mm or varus or valgus shift of more than 3°.16 Subsidence of the femoral component was measured as previously described.16 The criteria used to define loosening of the cemented femoral component have been reported,17 but only definite evidence of loosening was considered in this study. Definite loosening was defined as either subsidence of the stem or the mantle of the cement, bending or breakage of the stem, or a crack in the mantle of the cement. Debonding of the cement–metal interface, as indicated by a radiolucent line of any width at this interface, was considered to indicate subsidence of the stem, which was then classified as loose. The intraclass correlation coefficient was used to measure the intraobserver error after 3 repeated measurements at intervals of 3 days. It was 0.95 (95% confidence interval, 0.93–0.98), indicating excellent reproducibility.
Anteversion of the acetabular component was measured on a true lateral radiograph of the hip as the angle between a horizontal line and a second line marking the plane of the socket. To measure cup inclination, a line joining the inferior margins of the 2 acetabular teardrops was drawn on the anteroposterior pelvic radiograph. The intersection of that line, which marked the plane of opening of the socket, determined the angle of inclination. A linear change of 2 mm or an angular change of 5°, bead shedding, and increased circumferential lucency were considered signs of loosening of the cup. To determine a vertical change of the cup position, measurement was done between the inferior margin of the acetabular component and the inferior margin of the ipsilateral teardrop. To assess a horizontal change of the acetabular component, measurement was done between the Köhler line and the center of the outer shell of the acetabular component. The intracorrelation coefficient was 0.96 (95% confidence interval, 0.94–1.0). Stress shielding was graded on the radiographs at the final follow-up according to the classification of Engh et al.15
On the basis of the power analysis, the authors estimated that a sample of 80 hips was needed in each group to detect a 3-point difference in Harris hip score with 80% power. A dependent t test was used to evaluate the changes in Harris hip score, WOMAC score, and UCLA activity score. The Student's paired t test and the Pearson nonparametric chi-square test were used to evaluate the differences between the groups regarding Harris hip score, WOMAC score, and UCLA activity score. To compare complication rates and radiographic data between the groups, nonparametric chi-square tests were used. Using revision for any cause or aseptic loosening as the end point, Kaplan–Meier survival analysis was performed. SPSS version 14.0 software (SPSS Inc, Chicago, Illinois) was used for all statistical analyses. Statistical significance was set at P<.05.
The Harris hip score, WOMAC score, and UCLA activity score were significantly (P<.0001) improved after the operation in both groups. Mean preoperative (39 vs 37 points) and postoperative (81 vs 83 points) Harris hip scores were similar (P=.131 and .128, respectively) between the 2 groups. The incidence of pain in the thigh was 0% (0 of 93 and 78 patients, respectively) in both groups. At the latest follow-up, the mean WOMAC score was 18 points (range, 11–31 points) in the ultra-short stem group and 14 points (range, 7–29 points) in the cemented stem group (P=.139). Mean postoperative UCLA activity score was low in both groups (4.3 vs 4.5 points, P=.217) (Table 2). The kappa coefficient of intraobserver agreement regarding the Harris hip scores and WOMAC scores was 0.88 to 0.96. At the final follow-up, the range of motion of the hips was more than 120° flexion, 60° abduction, 60° adduction, 60° external rotation, and 60° internal rotation in both groups. A ceramic-on-ceramic bearing is not necessary to improve range of motion of the hip joint in octogenarians.
Rigid fixation of the ultra-short anatomic cementless stems was obtained in all hips. Cemented femoral stems were fixed rigidly in all but 1 hip (Figures 3–4). The Dorr bone type was not significantly different between the 2 groups (P=.159, .125, and .169, respectively). Dorr type C bone was 63% (62 of 98 hips) in the ultra-short stem group and 59% (54 of 92 hips) in the cemented stem group (P=.169). No significant differences were found between the 2 groups in the femoral stem alignment (P=.793), center of rotation of the femoral head (P=.232 and .189), femoral offset (P=.736), abductor moment arm (P=.879), acetabular component position (P=.851 and .868), radiolucent line around the femoral component (P=.512), and radiolucent line around the acetabular component (P=.179). Stress shielding was of minor degree9 in both groups (Table 3).
Anteroposterior radiograph 6 years postoperatively of an 85-year-old man with osteoarthritis of both hips. The ultra-short anatomic femoral stem (right hip) and the profile cementless femoral stem (left hip) are rigidly fixed in a satisfactory position in both hips.
Anteroposterior radiograph 7 years postoperatively of an 87-year-old woman with osteoarthritis of both hips. The cemented stem is solidly fixed in a satisfactory position in both hips. The femoral head is in eccentric position owing to polyethylene wear in both hips.
There were no significant differences between the 2 groups in the revision and survival rates of the acetabular and femoral components. In the ultra-short stem group, 1 femoral stem (1%) was revised for periprosthetic fracture and 2 femoral stems (2%) were revised for infection. One acetabular component (1%) was revised for infection. In the cemented stem group, 1 femoral component (1%) was revised for aseptic loosening and 2 femoral stems (2%) were revised for infection. The survival rates of the implants were similar between the 2 groups. With revision as the end point, Kaplan–Meier survivorship of the femoral stem was 97.3% (95% confidence interval, 0.94–1.0) at 8.1 years in the ultra-short stem group and 97.9% (95% confidence interval, 0.95–1.0) at 7.8 years in the cemented stem group (P=.136). The survival rate of the acetabular component was 98.2% (95% confidence interval, 0.94–1.0) in the ultra-short stem group and 98.4% (95% confidence interval, 0.95–1.0) in the cemented stem group.
In this series, the 1-year mortality rate was 0.
Dislocation occurred in 2 hips in each group, and they were treated successfully with closed reduction and the use of an abduction brace for 3 months. No further dislocation occurred in these 4 hips.
One hip (0.9%) in each group had an undisplaced fracture of the calcar region intraoperatively during impaction of the component. One displaced fracture of the calcar femorale in the ultra-short stem group was revised, but 17 hips (12%) in the cemented stem group had undisplaced periprosthetic calcar fractures intraoperatively. All of these fractures were treated successfully using 1 or 2 cables. None of these hips had an aseptic loosening of the femoral stem.
Two hips in each group had a deep infection. These 4 hips underwent 2-stage revision. No knee in either group had a recurrence of infection.
The authors investigated whether ultra-short anatomic cementless and cemented (uncemented acetabular component) femoral stems would provide similar functional results, radiographic results, revision and survival rates, and complication rates in octogenarians.
This study had some limitations. First, because follow-up was short, sufficient conclusions cannot be drawn, as most of these 2 types of implants had good results at 8.1 and 7.8 years postoperatively, respectively. However, it has been reported that if a femoral component is secure at 5 years postoperatively, it is likely to have long-term stable fixation.15,16 Second, more precise methods of radiosterophotogrammetric analysis were not used for stem subsidence. Third, the authors did not perform interobserver variability studies of the radiographic measurement to confirm the measurement by the single observer. This may have led to bias in interpreting the radiographic data, in turn leading to errors of either underestimation or overestimation. Fourth, the bearing surface as well as the femoral head size differed between the 2 groups. This may have led to different outcomes for these 2 stems. Fifth, this was single-center and retrospective, but not randomized, study. Sixth, potential confounding factors, including short stem vs a traditional longer stem and ceramic liner vs polyethylene liner, make these study results more speculative. Seventh, a substantial number of patients in each group died or were lost to follow-up. Finally, this retrospective cohort study of an earlier period had a relatively low level of evidence.
The Finnish Arthroplasty Registry suggested that hybrid fixation (a cemented stem and a cementless cup) had better long-term results than cementless fixation of the stem in octogenarians.8 However, cemented femoral stems have some disadvantages. Surgeons who perform a small volume of surgery may be more comfortable using an uncemented stem because when complications, including hip instability or leg length inequality, occur with a cemented stem, they are a little more disastrous because of the difficulty with revision. Furthermore, there are problems of fat embolism when using cement in the elderly population. On the other hand, several investigators advocate that uncemented implants be avoided in octogenarians because these individuals require a longer recovery time, have more difficult revisions, and have an increased risk for subsidence, fracture, and loosening.3–5 On the contrary, a few studies have reported excellent survivorship of uncemented tapered femoral stems in octogenarians.18,19
An ultra-short anatomic uncemented femoral stem was developed to reduce the risk of fat embolism, thigh pain, subsidence, loosening, periprosthetic fracture, stress shielding, and revision of the stem. Initially, this ultra-short stem was used for younger patients with good bone quality. The results of this stem were rewarding in younger patients; thus, it was gradually expanded to elderly patients. It has been questioned whether secure fixation of the ultra-short anatomic cementless femoral stems can be obtained in octogenarians. The aim of this study was to investigate how ultra-short anatomic and cemented femoral stems affect the survival of primary THAs in octogenarians.
The current results related to postoperative Harris hip score, WOMAC score, thigh pain, UCLA activity score, and radiographic findings confirm previously published data.5,8,10,15,16,20–26 Keisu et al20 reported on uncemented proximally coated tapered femoral components in 86 patients older than 80 years. They reported a mean improvement in Harris hip scores of 42 points at an average follow-up of 5 years. They additionally reported that 4 patients had mild pain in the thigh, but their activity was not limited by this. Stroh et al25 reported similar functional improvements in octogenarian and younger patient groups after proximally coated tapered cementless THA. Although functional outcomes determined by Harris hip score tended to be slightly better in the younger patient group, good Harris hip scores were achieved and maintained in most of the octogenarians during the study. Pettine et al24 showed that mean Harris hip scores after cemented THAs were not different between octogenarian and younger patient groups. Furthermore, Wurtz et al26 reported similar Harris hip scores after cemented THAs between octogenarian and younger patient groups. In the current study, the mean improvement in Harris hip score was 47 points in the ultra-short stem group and 50 points in the cemented stem group. These findings indicated that most of the octogenarians achieved and maintained good Harris hip scores during the study in both groups.
Thigh pain is sometimes associated with the use of uncemented femoral stems.15,16 The absence of thigh pain in the patients with an ultra-short stem may be attributable to the rigid axial and torsional stability of the component in the proximal femur and an absence of contact between the distal femur and the femoral cortex. No patient with a cemented stem had thigh pain.
Secure fixation of the ultra-short anatomic cementless stem was obtained in all hips. Secure fixation of the cemented femoral component was obtained in all but 1 hip. These findings are consistent with the results reported for conventional uncemented femoral components and other short uncemented femoral stems.3–5,10 In the current study, rigid fixation of the ultra-short anatomic femoral component was obtained in octogenarians with osteoporotic bone. This was reported by McAuley et al23 with their extensively porous-coated femoral stem. The current authors believe that stable fixation of the ultra-short uncemented femoral stem without diaphyseal stem fixation in octogenarians is attributable to optimal preparation of the proximal femur, preservation of the femoral neck, presence of the lateral flare of the femoral components, and osseointegration of the components. In addition, rigid fixation of the cemented stem was obtained via good cementing technique. This finding is consistent with the results reported for the cemented femoral stem.8,22
Previous studies of uncemented femoral stems in octogenarians reveal revision rates and survivorship of the femoral stems similar to those of the current study. Kolisek et al21 found a 0.3% revision rate for proximally coated tapered uncemented femoral components at 7-year follow-up. In addition, Bourne27 reported a 1% revision rate at 10-year follow-up for tapered cementless stems. Stroh et al25 reported a 3% revision rate for tapered femoral stems at 4 years. Keisu et al20 reported, at an average follow-up of 5 years, no revision of the proximally coated tapered cementless stem. Previous studies of cemented femoral stems in octogenarians reported revision rates and survivorship of the cemented femoral stems similar to those of the current study. Ogino et al8 reported a 5-year Kaplan–Meier survivorship of 95% for cemented femoral components in octogenarians. In the current study, in both groups, the prevalence of revision for a diagnosis of aseptic loosening was low, possibly because of the lower physical demands and shorter lifespan of these patients.
Although various retrospective, single-center studies20,21,25,27 have reported good or excellent short- and mid-term results with cementless THA in octogenarians, registry data1,7,8 continue to suggest superior outcomes in terms of lower revision risk when cemented fixation is compared with uncemented fixation of the femoral stem in older age groups. This may be explained by the major statistical power of registry data in identifying complications. On the other hand, it could represent a bias related to the heterogeneity of the uncemented implants evaluated.
The frequency of complications occurring after THA varies from 24%20 to 42.5%26 in octogenarians compared with 8% in the general population.28–30 Perioperative mortality in octogenarians is between 0.4%30 and 3.7%.31 In the current study, there were no perioperative deaths. The authors believe that low comorbidity in their patients in both groups led to absent perioperative mortality.
In this study, dislocation rates were similar between the 2 groups (2% vs 1%). However, it has been shown that, compared with younger patients, octogenarians are at increased risk for dislocation.32,33 Hummel et al34 reported that patients who received a 32-mm femoral head with capsular repair had a dislocation rate of 2.7% compared with 10.6% in patients who received a 28-mm femoral head without capsular repair. The current authors believe that the lower dislocation rate in both groups was attributable to optimal position of the components and posterior capsular repair.
The reason for the higher incidence of periprosthetic calcar fracture in the cemented group appeared to be the pressurization of the cement to obtain thigh fit in the soft bone.
Ultra-short uncemented anatomic and cemented femoral stems obtained rigid fixation in octogenarians. However, undisplaced periprosthetic calcar fracture intraoperatively was significantly higher (P=.003) in the cemented stem group. Furthermore, revision was much more difficult in the cemented group compared with the cementless group. On the basis of the findings of this study, the authors suggest that ultra-short uncemented stems can be used in octogenarians to reduce periprosthetic calcar fracture and make revision for infection easier. However, these conclusions are slightly speculative because several different factors could lead to the observed results.
- Gavaskar AS, Tummala NC, Subramanian M. Cemented or cementless THA in patients over 80 years with fracture neck of femur: a prospective comparative trial. Musculoskelet Surg. 2014; 98(3):205–208. doi:10.1007/s12306-013-0296-6 [CrossRef]
- Engh CA Sr, Leung S. Cementless stems in patients aged >60 years: justified use. Orthopedics. 2003; 26(9):921, 948.
- Ranawat CS, Rasquinha VJ, Ranawat AS. Cementless stems in patients aged >60 years: just say no. Orthopedics. 2003; 26(9):920, 922.
- Jämsen E, Eskelinen A, Peltola M, Mäkelä K. High early failure rate after cementless hip replacement in the octogenarian. Clin Orthop Relat Res. 2014; 472(9):2779–2789. doi:10.1007/s11999-014-3641-7 [CrossRef]
- Moritz N, Alm JJ, Lankinen P, Mäkinen TJ, Aro HT. Quality of intertrochanteric cancellous bone as predictor of femoral stem RSA migration in cementless total hip arthroplasty. J Biomech. 2011; 44(2):221–227. doi:10.1016/j.jbiomech.2010.10.012 [CrossRef]
- Australian Orthopaedic Association National Joint Replacement Registry. Hip and knee arthroplasty: annual report 2012. https://aoanjrr.sahmri.com/documents/10180/60142/Annual%20Report%202012?version=1.3&t=1361226543157. Accessed December 31, 2013.
- National Joint Registry for England and Wales. 9th annual report 2012. http://www.njrcentre.org.uk/njrcentre/Portals/0/Documents/England/Reports/9th_annual_report/NJR%209th%20Annual%20Report%202012.pdf. Accessed December 31, 2011.
- Ogino D, Kawaji H, Konttinen L, et al. Total hip replacement in patients eighty years of age and older. J Bone Joint Surg Am. 2008; 90(9):1884–1890. doi:10.2106/JBJS.G.00147 [CrossRef]
- Kim YH, Kim JS, Joo JH, Park JW. A prospective short-term outcome study of a short metaphyseal fitting total hip arthroplasty. J Arthroplasty. 2012; 27(1):88–94. doi:10.1016/j.arth.2011.02.008 [CrossRef]
- Kim YH, Kim JS, Park JW, Joo JH. Total hip replacement with a short metaphyseal-fitting anatomical cementless femoral component in patients aged 70 years or older. J Bone Joint Surg Br. 2011; 93(5):587–592. doi:10.1302/0301-620X.93B5.25994 [CrossRef]
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- Zahiri CA, Schmalzried TP, Szuszczewicz ES, Amstutz HC. Assessing activity in joint replacement patients. J Arthroplasty. 1998; 13(8):890–895. doi:10.1016/S0883-5403(98)90195-4 [CrossRef]
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- Kim YH, Kim VE. Early migration of uncemented porous coated anatomic femoral component related to aseptic loosening. Clin Orthop Relat Res. 1993; 295:146–155.
- Barrack RL, Mulroy RD Jr, Harris WH. Improved cementing technique and femoral component loosening in young patients with hip arthroplasty: a 12-year radiographic review. J Bone Joint Surg Br. 1992; 74(3):385–389. doi:10.1302/0301-620X.74B3.1587883 [CrossRef]
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|Characteristic||Ultra-short Stem Group||Cemented Stem Group||P|
|Patients (hips), No.||93 (98)||78 (92)||.129a|
|Male:female ratio, No.||25:68||35:43||.129a|
|Age, mean±SD (range), y||86.5±5.3 (80–89)||85.7±5.8 (80–89)||.135b|
|Weight, mean±SD (range), kg||64.9±7.8 (45–98)||64.7±11.1 (45–102)||.128b|
|Height, mean±SD (range), cm||155.5±9.2 (137–179)||161.2±9.1 (141–183)||.519b|
|Body mass index, average (range), kg/m2||28.1 (24–38)||28.5 (23–37)||.512b|
|Diagnosis, hips, No.||.396a|
| Osteoarthritis||50 (51%)||45 (50%)|
| Osteonecrosis||20 (21%)||29 (31%)|
| Femoral neck fracture||18 (18%)||7 (8%)|
| Traumatic arthritis||6 (6%)||5 (5%)|
| Childhood septic arthritis||4 (4%)||5 (5%)|
|Follow-up, average (range), y||8.1 (5–12)||7.8 (5–11)||.323b|
|Parameter||Ultra-short Stem Group||Cemented Stem Group||P (Student's t Test)|
|Preoperative||Final Follow-up||Preoperative||Final Follow-up||Preoperative||Final Follow-up|
|Harris hip score, mean (range), points||39 (16–49)||81 (67–91)||37 (11–51)||83 (69–88)||.131||.128a|
|WOMAC score, mean±SD (range), points||63±13.1 (45–91)||18±6.1 (11–31)||61±12.9 (48–94)||14±5.9 (7–29)||.121||.139a|
|Thigh pain, No. of patients||N/A||0 (0%)||N/A||0 (0%)||N/A||.331a|
|UCLA activity score, mean (range), points||2.1 (0–3)||4.3 (3–6)||2.3 (0–3)||4.5 (3–6)||N/A||.217a|
|Revision, No. of hips||N/A||3 (3%)||N/A||3 (3%)||N/A||.132b|
|Complication, No. of hips|
| Dislocation||2 (2%)||1 (1%)||N/A||.313b|
| Periprosthetic fracture||1 (1%)||11 (12%)||N/A||.003b|
| Infection||2 (2%)||2 (2%)||N/A||.329b|
|Parameter||Ultra-short Stem Group||Cemented Stem Group||P (Fisher's Exact Test)|
|Dorr bone type, No. of hips|
| A||25 (26%)||23 (25%)||.159|
| B||11 (11%)||14 (16%)||.125|
| C||62 (63%)||54 (59%)||.169|
|Femoral component position, No. of hips|
| Neutral||92 (94%)||86 (95%)||.793|
| Varus||6 (6%)||4 (4%)||.891|
| Valgus||0 (0%)||1 (1%)||.818|
|Center of rotation, mean (range), mm|
| Horizontal||41.2 (36–49)||40.8 (35–47)||.232|
| Vertical||15.1 (11–23)||14.8 (33–49)||.189|
|Femoral offset, mean (range), mm||42.3 (35–51)||41.9 (36–49)||.736|
|Abductor moment arm, mean (range), mm||45.7 (38–86)||47.1 (37–83)||.879|
|Femoral neck length, mean (range), mm||35.1 (28–43)||34.7 (29–41)||.731|
|Limb length discrepancy, mean (range), cm||0.2±0.3 (−1.4–0.9)||0.5±0.4 (−1.3–1.2)||.675|
|Radiolucent (>1 mm) (femoral), No. of hips||2 (2%)||1 (1%)||.512|
|Position of the acetabular component, mean (range)|
| Inclination||43° (35°–50°)||41° (38°–51°)||.851|
| Anteversion||26° (21°–29°)||24° (20°–31°)||.868|
|Radiolucent line (< 1 mm), No. of hips||3 (3%)||4 (4%)||.179|