Orthopedics

Feature Article 

Ultra-Short Versus Conventional Uncemented Stems for Hip Replacement in Octogenarians

Young-Hoo Kim, MD; Jang-Won Park, MD; Jun-Shik Kim, MD

Abstract

The aim of this study was to determine how an ultra-short anatomic uncemented stem vs a diaphyseal filling five-eighths porous coated uncemented femoral stem (conventional stem) affects the survival of primary total hip arthroplasties in octogenarians. The current study consisted of 52 patients (55 hips) in the ultra-short stem group (mean age, 85.5±5.3 years) and 61 patients (72 hips) in the diaphyseal (conventional) stem group (mean age, 84.1±4.8 years). The predominant diagnosis was osteoarthritis, followed by osteonecrosis of the femoral head, in both groups. Average follow-up was 6.1 years (range, 5–8 years) in the ultra-short stem group and 6.3 years (range, 5–9 years) in the conventional stem group. Pre- (41 vs 39 points) and postoperative (85 vs 86 points) Harris hip scores were similar between groups (P=.131 and .129, respectively). The incidence of thigh pain was 0% (0 of 52 patients) in the ultra-short stem group and 15% (9 of 61 patients) in the conventional stem group. The revision rate was 1.8% (1 hip) in the ultra-short stem group and 1.4% (1 hip) in the conventional stem group. Survivorship of the femoral stem was 98.2% in the ultra-short stem group at 6.1 years and 98.6% in the conventional stem group at 6.3 years. Ultra-short anatomic and diaphyseal filling uncemented stems obtained osseointegration in all hips. However, the prevalence of thigh pain and periprosthetic fracture were significantly higher in the patients with a conventional stem than in those with an ultra-short stem. [Orthopedics. 2018; 41(1):28–34.]

Abstract

The aim of this study was to determine how an ultra-short anatomic uncemented stem vs a diaphyseal filling five-eighths porous coated uncemented femoral stem (conventional stem) affects the survival of primary total hip arthroplasties in octogenarians. The current study consisted of 52 patients (55 hips) in the ultra-short stem group (mean age, 85.5±5.3 years) and 61 patients (72 hips) in the diaphyseal (conventional) stem group (mean age, 84.1±4.8 years). The predominant diagnosis was osteoarthritis, followed by osteonecrosis of the femoral head, in both groups. Average follow-up was 6.1 years (range, 5–8 years) in the ultra-short stem group and 6.3 years (range, 5–9 years) in the conventional stem group. Pre- (41 vs 39 points) and postoperative (85 vs 86 points) Harris hip scores were similar between groups (P=.131 and .129, respectively). The incidence of thigh pain was 0% (0 of 52 patients) in the ultra-short stem group and 15% (9 of 61 patients) in the conventional stem group. The revision rate was 1.8% (1 hip) in the ultra-short stem group and 1.4% (1 hip) in the conventional stem group. Survivorship of the femoral stem was 98.2% in the ultra-short stem group at 6.1 years and 98.6% in the conventional stem group at 6.3 years. Ultra-short anatomic and diaphyseal filling uncemented stems obtained osseointegration in all hips. However, the prevalence of thigh pain and periprosthetic fracture were significantly higher in the patients with a conventional stem than in those with an ultra-short stem. [Orthopedics. 2018; 41(1):28–34.]

Potential concerns about performing total hip arthroplasty (THA) in elderly patients are the high perioperative morbidity and the failure of implants owing to poor bone quality.1 It has been suggested that use of conventional uncemented femoral stems should be avoided in octogenarians because there is an increased risk of aseptic loosening due to poor bone quality, a higher prevalence of thigh pain, a higher cost, a higher risk of periprosthetic fracture intra- and postoperatively, and more difficult revisioning.2–7

An ultra-short anatomic uncemented femoral stem was developed to reduce the risk of fat embolism, thigh pain, periprosthetic fracture, stress shielding related bone resorption, and component revision.8,9 It is debated whether secure fixation of the ultra-short anatomic uncemented femoral stem can be obtained without diaphyseal stem fixation in octogenarians.

The aim of the current investigation was to determine how an ultra-short anatomic uncemented stem vs a diaphyseal filling five-eighths porous coated uncemented femoral stem (conventional stem) affects the survival of primary THAs in octogenarians. Specifically, the authors questioned whether ultra-short stems vs conventional stems 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 2005 to March 2007, sixty-three primary THAs using a diaphyseal stem were performed in 58 consecutive octogenarians. From April 2007 to December 2009, seventy-eight primary THAs using ultra-short stems were performed in 67 consecutive octogenarians. Patients were prospectively followed and their data were retrospectively analyzed. The study was approved by the authors' institutional review board, and informed consent was obtained from all patients.

In the ultra-short stem group, 3 patients were lost to follow-up before 2 years postoperatively and 3 patients died in the interim. In the conventional stem group, 4 patients were lost to follow-up and 2 patients died in the interim. Consequently, the authors evaluated 52 consecutive octogenarians (55 hips) in the ultra-short stem group and 61 consecutive octogenarians (72 hips) in the conventional stem group. The ultra-short stem group consisted of 14 men and 38 women. Mean age was 85.5±5.3 years (range, 80–89 years), and mean body mass index (BMI) was 26 kg/m2 (range, 22–36 kg/m2). The conventional stem group consisted of 27 men and 34 women. Mean age was 84.1±4.8 years (range, 80–89 years), and mean BMI was 26.9 kg/m2 (range, 23–35 kg/m2). The American Society of Anesthesiologist (ASA) physical status classification system was used to measure the overall health status of each patient. Mean ASA score was 3 in the ultra-short stem group and 2 in the conventional stem group. The predominant diagnosis for THAs was osteoarthritis, followed by osteonecrosis, in both groups (Table 1).

Patient Demographics

Table 1:

Patient Demographics

All operations were performed by a senior author (Y.-H.K.) using a posterolateral approach. An uncemented Pinnacle cup (DePuy, Warsaw, Indiana) was press-fitted and either a 32- or 36-mm Biolox delta ceramic liner (CeramTec AG, Polchingen, Germany) was used in all hips in both groups. The cup sizes ranged from 48 to 58 mm. The cup position was targeted between 35° and 45° abduction and between 20° and 30° anteversion. A total of 52 patients received an ultra-short anatomic femoral stem (Proxima; DePuy, Leeds, UK) with a 32- or 36-mm Biolox delta ceramic modular head (CeramTec AG)10 and 61 patients received an anatomic medullary locking diaphyseal filling five-eighths porous coated uncemented femoral stem (AML; DePuy, Warsaw, Indiana) with a 32- or 36-mm Biolox delta ceramic modular head. The ultra-short stem has rasp only, whereas the longer stem needs intramedullary reaming and rasping. The reason for using a ceramic-on-ceramic bearing was that a 32- or 36-mm metallic femoral head was not available during the study period.

On the second postoperative day, patients in both groups started walking with full-weight bearing using crutches or a walker, which were used for 4 to 6 weeks; thereafter, a cane was used as needed.

Follow-up examinations of the patients were performed at 3 months and 1 year postoperatively and 2 or 3 years thereafter. The Harris hip score (HHS)11 and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score12 were assessed preoperatively and at each follow-up. Thigh pain was scored on a 10-point visual analog scale, where 0=no pain and 10=severe pain. The University of California, Los Angeles (UCLA) score was used to assess activity level at each follow-up.13 A research associate who was not part of the surgical team analyzed all of these data. Average follow-up was 6.1 years (range, 5–8 years) in the ultra-short stem group and 6.3 years (range, 5–9 years) in the conventional stem group.

The authors obtained anteroposterior and cross-table lateral radiographs in the supine position at the seven or eighth postoperative day and at each follow-up examination. The morphology of the femur was assessed before the operation according to Dorr's classification system.14 The position of the femoral component was assessed in the anteroposterior and lateral plane of radiographs.

A research associate who was not involved in the operation assessed the radiographic stability of the components. The stability of the femoral component was classified as osseointegrated, fibrous stable, or unstable, according to criteria of Engh et al.15 When a progressive axial subsidence of the femoral stem more than 3 mm or a varus or valgus shift of more than 3° occurred, it was defined as definite loosening.10,16 Subsidence of the femoral component was measured as previously described.10,16 The intraclass correlation coefficient was used to measure the intraobserver error after repeated measurements 3 times at intervals of 3 days. The intraclass correlation coefficient was 0.95 (95% confidence interval [CI], 0.93–0.98), indicating excellent reproducibility. Signs of loosening of the cup were considered when a linear change of 2 mm or an angular change of 5°, bead-shedding, and increased circumferential lucency occurred. The criteria of Engh et al15,17 was used to grade stress-shielding on the radiographs at the final follow-up.

A clinically relevant difference in HHS of 5 points and a standard deviation of 6 points were used for power calculations. Calculations revealed that 47 patients would be required in each group, with α=0.05 and ß=0.95. Ten percent more patients were recruited for possible dropouts.

A paired t test was used to evaluate the changes in HHS, WOMAC, and UCLA activity scores. The chi-square test with Yate's correction was used to analyze radiographic data and complication rates. 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.

Results

Harris hip score, WOMAC score, and the UCLA activity score were substantially improved in both groups. Pre- (41 vs 39 points) and postoperative HHSs (85 vs 86 points) were similar (P=.131 and .129, respectively) between the 2 groups. The incidence of pain in the thigh (activity related) was 0% (0 of 52 patients) in the ultra-short stem group and 15% (9 of 61 patients) in the conventional stem group at final follow-up (P=.001). At the latest follow-up, mean WOMAC score was 16 points (range, 12–30 points) in the ultra-short stem group and 15 points (range, 8–28 points) in the conventional stem group (P=.151). Mean postoperative UCLA activity score was low in both groups (4.6 vs 4.8 points, P=.129) (Table 2). The κ coefficient of intraobserver agreement regarding the hip scores and the WOMAC scores was 0.87 and 0.95, respectively.

Clinical Results

Table 2:

Clinical Results

Osseointegration of the ultra-short anatomic stem and the diaphyseal filling five-eighths porous coated femoral stem was obtained in all hips (Figures 12). The Dorr bone type was not significantly different between the 2 groups (P<.05). Dorr type C bone was 64% (35 of 55 hips) in the ultra-short stem group and 58% (42 of 72 hips) in the conventional stem group. No significant differences were found between the 2 groups in the femoral stem alignment (P=.723), center of rotation of femoral head (P=.238 and .191), femoral offset (P=.793), abductor moment arm (P=.879), acetabular component position (P=.923 for inclination and P=.893 for anteversion), radiolucent line around femoral component (P=.521), and radiolucent line around the acetabular component (P=.181) (Table 3).

Radiographs of an 85-year-old man with osteoarthritis of both hips. Preoperative anteroposterior radiograph of both hips revealing complete loss of cartilaginous space of the right hip and sclerotic change of the left femoral head, consistent with osteonecrosis of both femoral heads. Type of bone is Dorr type A in both femurs (A). Anteroposterior radiograph of both hips obtained 6 years postoperatively showing that the ultra-short anatomic femoral stems are rigidly fixed in a satisfactory position in both hips (B).

Figure 1:

Radiographs of an 85-year-old man with osteoarthritis of both hips. Preoperative anteroposterior radiograph of both hips revealing complete loss of cartilaginous space of the right hip and sclerotic change of the left femoral head, consistent with osteonecrosis of both femoral heads. Type of bone is Dorr type A in both femurs (A). Anteroposterior radiograph of both hips obtained 6 years postoperatively showing that the ultra-short anatomic femoral stems are rigidly fixed in a satisfactory position in both hips (B).

Radiographs of an 85-year-old man with osteoarthritis of the left hip. Preoperative antero-posterior radiograph of the left hip showing complete loss of cartilaginous space of the left hip with deformed femoral heads and dysplastic acetabulum. Type of bone is Dorr type A in left femur (A). Anteroposterior radiograph of the left hip obtained 6 years after surgery revealing that the AML cementless stem (DePuy, Warsaw, Indiana) and acetabular component are solidly fixed in a satisfactory position in the left hip (B).

Figure 2:

Radiographs of an 85-year-old man with osteoarthritis of the left hip. Preoperative antero-posterior radiograph of the left hip showing complete loss of cartilaginous space of the left hip with deformed femoral heads and dysplastic acetabulum. Type of bone is Dorr type A in left femur (A). Anteroposterior radiograph of the left hip obtained 6 years after surgery revealing that the AML cementless stem (DePuy, Warsaw, Indiana) and acetabular component are solidly fixed in a satisfactory position in the left hip (B).

Radiographic Results

Table 3:

Radiographic Results

No significant differences were found between the 2 groups for the revision and survival rates of the acetabular and femoral components. In the ultra-short stem group, 1 (1.8%) femoral stem was revised for periprosthetic fracture and no acetabular component was revised. In the conventional stem group, 1 (1.4%) femoral component was revised for periprosthetic fracture, and no acetabular component was revised.

With revision as the end point, Kaplan–Meier survivorship of the femoral stem was 98.2% (95% CI, 0.94–1.0) at 6.1 years in the ultra-short stem group and 98.6% (95% CI, 0.95–1.0) at 6.3 years in the conventional stem group. Survival rate of the acetabular component was 100% (95% CI, 0.95–1.0) in both groups.

Dislocation occurred in 1 hip 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 2 hips.

One (1.8%) hip with an ultra-short stem and 9 (13%) hips with a conventional stem had an undisplaced fracture of the calcar region intraoperatively during impaction of the component. One displaced fracture in each group was revised. The remaining 8 hips with a calcar fracture in the conventional stem group were treated with cerclage cables.

Discussion

Several investigators advocate that uncemented implants should be avoided in octogenarians because they have an increased risk for subsidence, fracture, and loosening.3–5 Conversely, other studies have demonstrated excellent survivor-ship in octogenarians who have femoral stems.18,19 An ultra-short anatomic femoral stem was developed to reduce the risk of fat embolism, thigh pain, periprosthetic fracture, and stress shielding. The aim of the current study was to investigate how ultra-short anatomic stems and conventional uncemented femoral stems affect the survival of primary THAs in octogenarians.

The current study had some limitations. First, the follow-up period was short; thus, sufficient conclusions cannot be drawn because most of the implants reveal good results at 10 years postoperatively. However, it has been reported that if a femoral component is secure at 5 years postoperatively, a long-term stable fixation of the femoral component is likely to be maintained.15,16 Second, the analysis of the stem subsidence did not use more precise methods of radio stereophotogrammetric analysis. Third, the authors performed no interobserver variability studies of the radiographic measurement to confirm the measurement by the single observer, which may lead to bias in interpreting the radiographic data and to errors of either under- or overestimation.

In 86 patients older than 80 years, Keisu et al20 reported using uncemented proximally coated tapered femoral components. A mean improvement in HHSs of 42 points at a mean of 5-year follow-up was reported. They additionally reported that there were 4 patients who had mild pain in the thigh. Patients' activity was not limited by this mild thigh pain.20 Stroh et al21 reported similar functional improvements in octogenarian and younger patient groups. Although functional outcomes determined by HHS tended to be slightly higher in the younger patient group, good HHSs were achieved and maintained in most of the octogenarians during the study period.21

Pettine et al22 demonstrated that mean HHSs were not different between octogenarian and younger patient groups. Furthermore, Wurtz et al23 reported similar HHSs between the octogenarian and younger patient groups. In the current study, mean HHS improvement was 44 points in the ultra-short stem group and 47 points in the conventional stem group. These findings indicated that most octogenarians in both groups achieved and maintained good HHSs during the study period.

Thigh pain is sometimes associated with the use of uncemented femoral stems.15,16 The absence of thigh pain in 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. The high incidence of thigh pain in the conventional group may be attributable to the use of a stiff femoral stem (cobalt-chrome made) in osteoporotic bone. Furthermore, intramedullary reaming and rasping may be one of causes of the excessive thigh pain.

In all hips in both groups, secure fixation of the ultra-short stem and the conventional stem was obtained. These findings are consistent with the reported results of diaphyseal filling five-eighths porous coated femoral components and other short uncemented femoral stems.3–5,9,24 The authors believe that stable fixation of the ultra-short femoral stem without diaphyseal stem fixation in octogenarians is attributable to the optimal preparation of the proximal femur, preservation of the femoral neck, the presence of the lateral flare of the femoral components, and osseointegration of the components. In addition, rigid fixation of the AML uncemented stem was also obtained by using a five-eighths porous coated femoral stem with tight diaphyseal stem fixation.

Previous studies for uncemented femoral stems in octogenarians reveal similar revision rates and survivorship of the femoral stems to the current study. Kolisek et al25 found a 0.3% revision rate for proximally coated tapered uncemented femoral component at 7-year follow-up. In addition, Sinha and Bourne26 demonstrated a 1% revision rate at 10-year follow-up for tapered cementless stems. Stroh et al21 found a 3% revision rate of tapered femoral stems at 4 years. Keisu et al20 reported no revision of the proximally coated tapered cementless stem at a mean follow-up of 5 years. Ogino et al27 found a 5-year Kaplan–Meier survivorship of 95% for octogenarian patients with uncemented femoral components.

Perioperative mortality20,28–30 in octogenarians is between 0.4%30 and 3.7%.31 In the current study, the authors did not observe any perioperative deaths. The authors believe that low comorbidity in both groups led to absent perioperative mortality.

Dislocation rates in the current study were similar between the 2 groups. The authors believe that factors contributing to the low dislocation rates include the use of larger head sizes and repairing the posterior capsule with the posterior approach,32–34 which was performed in this study.

One (1.8%) hip with an ultra-short stem and 9 (13%) hips with a conventional stem had an undisplaced fracture of the calcar region intraoperatively during impaction of the component. One patient with a displaced fracture in each group was revised for the loose femoral component. The remaining 8 hips with calcar fracture were treated with cerclage cables without further sequelae. The intraoperative fracture rate of 1.8% in the ultra-short stem group is within the reported range of 1% to 6%, in the literature for elective THA as a whole.35,36 However, the intraoperative fracture rate of 13% in the conventional stem group exceeds the published incidence rate. In the current series, 58% to 64% of the hips were classified as Dorr type C bone. For the AML, this would require a large size implant that may have a mismatch proximally, resulting in fracture. Currently, the hips with Dorr type C bone would likely be treated with uncemented tapered stems that may or may not require reaming.

Conclusion

Ultra-short uncemented anatomic stems and diaphyseal filling five-eighths porous coated uncemented femoral stems obtained rigid fixation in octogenarians. However, the prevalence of thigh pain and periprosthetic fracture was significantly higher in the patients with a conventional stem than in those with an ultra-short stem.

References

  1. 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]
  2. Engh CA Sr, Leung S. Cementless stems in patients aged >60 years: justified use. Orthopedics. 2003; 26(9):921–948.
  3. 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]
  4. Moritz N, Alm JJ, Lankinen P, Mäkinen TJ, Mattila K, 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]
  5. Ranawat CS, Rasquinha VJ, Ranawat AS. Cementless stems in patients aged >60 years: just say no. Orthopedics. 2003; 26(9):920, 922.
  6. Australian Orthopaedic Association National Joint Replacement Registry. Hip and knee arthroplasty: annual report2012. https://aoanjrr.sahmri.com/documents/10180/60142/Erratum%20for%20printed%20version%20of%202012%20Annual%20Report?version=1.4&t=1361226578293. Accessed February 30, 2013.
  7. National Joint Registry for England and Wales. 9th annual report2012. http://www.njrcentre.org.uk/njrcentre/Portals/0/Documents/England/Reports/9th_annual_report/NJR%209th%20Annual%20Report%202012.pdf. Accessed October 25, 2012.
  8. 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]
  9. 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]
  10. Kim YH, Kim VE. Uncemented porous-coated anatomic total hip replacement: results at six years in a consecutive series. J Bone Joint Surg Br. 1993; 75(1):6–13.
  11. Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of results evaluation. J Bone Joint Surg Am. 1969; 51(4):737–755. doi:10.2106/00004623-196951040-00012 [CrossRef]
  12. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW. Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol. 1988; 15(12):1833–1840.
  13. 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]
  14. Dorr LD. Total hip replacement using APR system. Tech Orthop. 1986; 1:22–34. doi:10.1097/00013611-198610000-00007 [CrossRef]
  15. Engh CA, Bobyn JD, Glassman AH. Porous-coated hip replacement: the factors governing bone ingrowth, stress shielding, and clinical results. J Bone Joint Surg Br. 1987; 69(1):45–55.
  16. 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.
  17. Engh CA, McGovern TF, Bobyn JD, Harris WH. A quantitative evaluation of periprosthetic bone-remodeling after cementless total hip arthroplasty. J Bone Joint Surg Am. 1992; 74(7):1009–1020. doi:10.2106/00004623-199274070-00007 [CrossRef]
  18. Purtill JJ, Rothman RH, Hozack WJ, Sharkey PF. Total hip arthroplasty using two different cementless tapered stems. Clin Orthop Relat Res. 2001; (393):121–127. doi:10.1097/00003086-200112000-00014 [CrossRef]
  19. Sakalkale DP, Eng K, Hozack WJ, Rothman RH. Minimum 10-year results of a tapered cementless hip replacement. Clin Orthop Relat Res. 1999; (362):138–144.
  20. Keisu KS, Orozco F, Sharkey PF, Hozack WJ, Rothman RH, McGuigan FX. Primary cementless total hip arthroplasty in octogenarians: two to eleven-year follow-up. J Bone Joint Surg Am. 2001; 83(3):359–363. doi:10.2106/00004623-200103000-00007 [CrossRef]
  21. Stroh DA, Zywiel MG, Johnson AJ, Mont MA. Excellent survivorship with the use of proximally coated tapered cementless stems for total hip arthroplasty in octogenarians. Geriatr Orthop Surg Rehabil. 2011; 2(3):100–104. doi:10.1177/2151458511406267 [CrossRef]
  22. Pettine KA, Aamlid BC, Cabanela ME. Elective total hip arthroplasty in patients older than 80 years of age. Clin Orthop Relat Res. 1991; (266):127–132.
  23. Wurtz LD, Feinberg JR, Capello WN, Meldrum R, Kay PJ. Elective primary total hip arthroplasty in octogenarians. J Gerontol A Biol Sci Med Sci. 2003; 58(5):M468–M471. doi:10.1093/gerona/58.5.M468 [CrossRef]
  24. McAuley JP, Moore KD, Culpepper WJ II, Engh CA. Total hip arthroplasty with porous-coated prostheses fixed without cement in patients who are sixty-five years of age or older. J Bone Joint Surg Am. 1998; 80(11): 648–1655. doi:10.2106/00004623-199811000-00012 [CrossRef]
  25. Kolisek FR, Issa K, Harwin SF, Jaggard C, Naziri Q, Mont MA. Minimum 5-year follow-up for primary THA using a tapered, proximally coated cementless stem. Orthopedics. 2013; 36(5):e633–e636. doi:10.3928/01477447-20130426-27 [CrossRef]
  26. Sinha RK, Bourne R. Cementless femoral design. Hip Replacement: Curr Trends Controversies. 2002; 2:47.
  27. 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]
  28. Rittmeister M, Peters A. Comparison of total hip arthroplasty via a posterior mini-incision versus a classic anterolateral approach [in German]. Orthopade. 2006; 35(7):716, 718–722. doi:10.1007/s00132-006-0963-5 [CrossRef]
  29. Sharkey PF, Shastri S, Teloken MA, Parvizi J, Hozack WJ, Rothman RH. Relationship between surgical volume and early outcomes of total hip arthroplasty: do results continue to get better?J Arthroplasty. 2004; 19(6):694–699. doi:10.1016/j.arth.2004.02.040 [CrossRef]
  30. Williams O, Fitzpatrick R, Hajat S, et al. National Total Hip Replacement Outcome Study Steering Committee. Mortality, morbidity, and 1-year outcomes of primary elective total hip arthroplasty. J Arthroplasty. 2002; 17(2):165–171. doi:10.1054/arth.2002.29389 [CrossRef]
  31. Whittle J, Steinberg EP, Anderson GF, Herbert R, Hochberg MC. Mortality after elective total hip arthroplasty in elderly Americans: age, gender, and indication for surgery predict survival. Clin Orthop Relat Res. 1993; (295):119–126.
  32. Goel A, Lau EC, Ong KL, Berry DJ, Malkani AL. Dislocation rates following primary total hip arthroplasty have plateaued in the Medicare population. J Arthroplasty. 2015; 30(5):743–746. doi:10.1016/j.arth.2014.11.012 [CrossRef]
  33. Meek RM, Allan DB, McPhillips G, Kerr L, Howie CR. Epidemiology of dislocation after total hip arthroplasty. Clin Orthop Relat Res. 2006; (447):9–18. doi:10.1097/01.blo.0000218754.12311.4a [CrossRef]
  34. Hummel MT, Malkani AL, Yakkanti MR, Baker DL. Decreased dislocation after revision total hip arthroplasty using larger femoral head size and posterior capsular repair. J Arthroplasty. 2009; 24(6)(suppl):73–76. doi:10.1016/j.arth.2009.04.026 [CrossRef]
  35. Christensen CM, Seger BM, Schultz RB. Management of intraoperative femur fractures associated with revision hip arthroplasty. Clin Orthop Relat Res. 1989; (248):177–180.
  36. Kavanagh BF. Femoral fractures associated with total hip arthroplasty. Orthop Clin North Am. 1992; 23(2):249–257.

Patient Demographics

ParameterUltra-Short Stem GroupConventional Stem GroupP
Patients (hips), No.52 (55)61 (72)N/A
Male/female ratio, No.14/3827/34.129a
Age, mean±SD (range), y85.5±5.3 (80–89)84.1±4.8 (80–89).135b
Weight, mean±SD (range), kg64.9±7.8 (50–98)64.7±11.1 (45–102).131b
Height, mean±SD (range), cm158.1±8.5 (145–185)161.3±9.1 (141–183).519b
Body mass index, mean (range), kg/m226.1 (22–36)26.9 (23–35).512b
Diagnosis (hips), No. (%)
  Osteoarthritis28 (51)35 (49).168b
  Osteonecrosis12 (22)24 (33).178b
  Femoral neck fracture10 (18)6 (8)N/A
  Traumatic arthritis3 (5)4 (6)N/A
  Childhood septic arthritis2 (4)3 (4)N/A
Follow-up, mean (range), y6.1 (5–8)6.3 (5–9).323b

Clinical Results

ParameterUltra-Short Stem GroupConventional Stem GroupPa



PreoperativeFinal Follow-upPreoperativeFinal Follow-upPreoperativeFinal Follow-up
Harris hip score, mean (range), points41 (17–51)85 (65–100)39 (12–49)86 (67–100).131.129
WOMAC score, mean±SD (range), points63±13.1 (45–91)16±5.9 (12–30)61±12.9 (48–94)15±4.9 (8–28).121.151
Thigh pain, No.N/A0 patient (0%)N/A9 patients (15%)N/A.001
UCLA activity score, mean (range), pointsN/A4.6 (3–6)N/A4.8 (3–7)N/A.129
Revision, No.N/A1 hip (1.8%)N/A1 hip (1.4%)N/A.129
Complications, No.
  DislocationN/A1 hip (1.8%)N/A1 hip (1%)N/A.329
  Periprosthetic fractureN/A1 hip (1.8%)N/A9 hips (13%)N/A.003

Radiographic Results

ParameterUltra-Short Stem GroupConventional Stem GroupPa
Dorr bone type
  A14 hips (25%)22 hips (31%).157
  B6 hips (11%)8 hips (11%).131
  C35 hips (64%)42 hips (58%).229
Femoral component position
  Neutral52 hips (95%)68 hips (95%).723
  Varus3 hips (5%)3 hips (4%)N/A
  Valgus0 hip (0%)1 hip (1%)N/A
Center of rotation, mean (range), mm
  Horizontal41.2 (36–49)40.8 (35–47).238
  Vertical15.1 (11–23)14.8 (33–49).191
Femoral offset, mean (range), mm42.3 (35–51)41.9 (36–49).793
  Abductor moment arm, mean (range), mm45.7 (38–86)47.1 (37–83).879
  Femoral neck length, mean (range), mm35.1 (28–43)34.7 (29–41).728
  Limb length discrepancy, mean±SD (range), cm0.2±0.3 (−1.4–0.9)0.5±0.4 (−1.3–1.2).678
Radiolucent (>1 mm) (femoral)1 hip (1%)1 hip (1%).521
Position of the acetabular component, mean (range)
  Inclination43° (35°–50°)41° (38°–51°).923
  Anteversion26° (21°–29°)24° (20°–31°).893
  Radiolucent line (<1 mm)3 hips (5%)4 hips (6%).181
Authors

The authors are from The Joint Replacement Center, SeoNam Hospital (Y-HK) and Ewha Womans University, MokDong Hospital (J-WP, J-SK), Seoul, Republic of Korea.

The authors have no relevant financial relationships to disclose.

Correspondence should be addressed to: Young-Hoo Kim, MD, The Joint Replacement Center, SeoNam Hospital, #20, Sinjeongipen 1-ro, YangCheon-Gu, Seoul 08040, Republic of Korea ( younghookim@ewha.ac.kr).

Received: May 24, 2017
Accepted: September 14, 2017
Posted Online: November 14, 2017

10.3928/01477447-20171106-01

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