title: A prospective cohort study on the short collum femoris-preserving (CFP) stem using RSA and DXA Reproducibility of femoral offset following short stem and straight stem total hip arthroplasty. Bone remodelling around the Metha short stem in total hip arthroplasty: a prospective dual-energy X-ray absorptiometry study Maintenance of bone mineral density after implantation of a femoral neck hip prosthesis The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials No Increased Migration in Cups with Ceramic-on-Ceramic Bearing: An RSA Study Bone remodelling after femoral short stem implantation in total hip arthroplasty: 1-year results from a randomized DEXA study Lower periprosthetic bone loss and good fixation of an ultra-short stem compared to a conventional stem in uncemented total hip arthroplasty Changes in the bone mineral density in the acetabulum and proximal femur after cementless total hip replacement: alumina-on-alumina versus alumina-on-polyethylene articulation. A new short uncemented, proximally fixed anatomic femoral implant with a prominent lateral flare: design rationals and study design of an international clinical trial Stepwise introduction of a bone-conserving osseointegrated hip arthroplasty using RSA and a randomized study: I. Preliminary investigations—52 patients followed for 3 years Comparison of two hydroxyapatite-coated femoral stems: clinical, functional, and bone densitometry evaluation of patients randomized to a regular or modified hydroxyapatite-coated stem aimed at proximal fixation. Comparison of Bone Remodeling Between an Anatomic Short Stem and a Straight Stem in 1-Stage Bilateral Total Hip Arthroplasty. Changes in bone mineral density in the proximal femur after cementless total hip arthroplasty. A five-year longitudinal study. Hydroxyapatite-coated Femoral Components: 15-Year Minimum Followup No Difference in Periprosthetic Bone Loss and Fixation Between a Standard-Length Stem and a Shorter Version in Cementless Total Hip Arthroplasty. A Randomized Controlled Trial. Ultrashort versus Conventional Anatomic Cementless Femoral Stems in the Same Patients Younger Than 55 Years Primary Total Hip Arthroplasty with a Second-Generation Cementless Total Hip Prosthesis in Patients Younger Than Fifty Years of Age Second-generation Extensively Porous-coated THA Stems at Minimum 10-year Followup
abstract: Background and purpose Short femoral stems have been introduced in total hip arthroplasty in order to save proximal bone stock . We hypothesized that a short stem preserves periprosthetic bone mineral density ( BMD ) and provides good primary stability . Methods We carried out a prospect i ve cohort study of 30 patients receiving the collum femoris-preserving ( CFP ) stem .  Preoperative total hip BMD and postoperative periprosthetic BMD in Gruen zones 1–7 were investigated by dual-energy x-ray absorptiometry ( DXA ) , stem migration was analyzed by radiostereometric analysis ( RSA ) , and the Harris hip score ( HHS ) was determined . Results 2 patients were excluded intraoperatively and 1 patient was revised due to a deep infection , leaving 27 patients for analysis . The mean HHS increased from 49 ( 24–79 ) preoperatively to 99 ( 92–100 ) after 2 years . DXA after 1 year showed substantial loss of BMD in Gruen zone 7 ( –31 % ) , zone 6 ( –19 % ) , and zone 2 ( –13 % , p < 0.001 ) compared to baseline BMD determined immediately postoperatively . The bone loss in these regions did not recover after 2 years , whereas the more moderate bone loss in Gruen zones 1 , 3 , and 5 partially recovered . There was a correlation between low preoperative total hip BMD and a higher amount of bone loss in Gruen zones 2 , 6 and 7 . RSA showed minor micromotion of the stem : mean subsidence was 0.13 ( 95 % CI : –0.28 to 0.01 ) mm and mean rotation around the longitudinal axis was 0.01º ( 95 % CI : –0.1 to 0.39 ) after 2 years . Interpretation We conclude that substantial loss in proximal periprosthetic BMD can not be prevented by the use of a novel type of short , curved stem , and forces appear to be transmitted distally . However , the stems showed very small migration — a characteristic of stable uncemented implants Bone stock-preserving short stem prostheses have gained importance in  total hip arthroplasty ( THA ) with the use of minimally invasive surgical procedures . Because of their metaphyseal fixation and their dependency on the calcar radius , it is unknown whether the femoral offset can be reproduced with the same accuracy following short stem vs st and ard stem THA . This study clarifies whether it is possible to restore the femoral offset using a short stem prosthesis ( Fitmore ; Zimmer , Warsaw , Indiana ) compared with a conventional straight stem prosthesis ( CLS ; Zimmer ) following minimally invasive implantation using an anterolateral approach . In a prospect i ve , r and omized , double-blinded study , 80 patients underwent THA using a short stem ( SS group ; n=40 ) or CLS implant ( control group ; n=40 ) . Follow-up examinations were conducted 6 weeks postoperatively . Radiological and functional outcomes were measured . Subjective assessment of quality of life was evaluated using the Harris Hip Score ( HHS ) , the Short Form 36-item health survey ( SF-36 ) , and the Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) . Pre- and postoperative comparison of the groups ' change in offset showed no significant differences ( SS group difference from pre- to postoperative , 6.1±6.5 mm ; control group difference from pre- to postoperative , 6.5±7.1 mm ; P=.93 ) . Group comparison after 6 weeks revealed no significant differences in HHS , SF-36 , or WOMAC . Based on these data , an equivalent reproducibility of the femoral offset was demonstrated following short stem and straight stem THA using a minimally invasive anterolateral approach . If the long-term results of short stems show a comparable survival , they represent a sensible alternative to st and ard stems Purpose On the basis of positive clinical results with mid- and long-term follow-up using the Mayo short stem , the Metha neck-preserving stem ( BBraun , Aesculap , Tuttlingen , Germany ) was introduced . The purpose of this study was to vali date the implant design by direct acquisition of bone remodelling data from total hip arthroplasty ( THA ) recipients using dual-energy X-ray absorptiometry ( DEXA ) . Methods After power analysis , 25 patients were included in this prospect i ve study . Patients were examined clinical ly and underwent DEXA examinations preoperatively and postoperatively at one week , six months and one and two years after THA . Gruen zones were adapted to the short stem design ( R1–R7 ) . Results The Harris Hip Score ( HHS ) increased significantly by 31 points . No stem had to be revised . Bone mineral density ( BMD ) in the greater trochanter decreased significantly from 0.78 g/cm2 postoperatively to 0.72 g/cm2 two years after surgery . Marginal changes were seen in the lateral distal regions ( R4–R5 ) . In the minor trochanter region , BMD increased significantly after two years by 12.9 % . In the calcar region , BMD exceeded the baseline value by 6.1 % two years after implantation . Conclusions Stress shielding seems to occur at the greater trochanter due to the vast cross-section of the implant . However , the aim of proximal load transfer of the Metha stem seems to be partially achieved . DEXA analysis revealed a concentrated load distribution on the medial portion of the femur , which is an important region to guarantee long-term implant survival Background Stress shielding of the proximal femur has been observed in a number of conventional cementless implants used in total hip arthroplasty .  Short femoral-neck implants are cl aim ing less interference with the biomechanics of the proximal femur . The goal of this study was to investigate the changes of bone-mineral density in the proximal femur and the clinical outcome after implantation of a short femoral-neck prosthesis . Methods We prospect ively assessed the clinical outcome and the changes of bone mineral density of the proximal femur up to one year after implantation of a short femoral neck prosthesis in 20 patients with a mean age of 47 years ( range 17 to 65 ) . Clinical outcome was assessed using the Harris Hip Score . The WOMAC was used as a patient-relevant outcome -measure . The bone mineral density was determined using dual energy x-ray absorptiometry , performed 10 days , three months and 12 months after surgery . Results The Harris Hip Score improved from an average preoperative score of 46 to a postoperative score at 12 months of 89 points , the global WOMAC index from 5,3 preoperatively to 0,8 at 12 months postoperatively . In contrast to conventional implants , the DEXA-scans overall revealed a slight increase of bone mineral density in the proximal femur in the 12 months following the implantation . Conclusion The short femoral neck stem lead to a distinct bone reaction . This was significantly different when compared to the changes in bone mineral density reported after implantation of conventional implants Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more Ceramic-on-ceramic hip replacements might stress the bone interface more than a metal-polyethylene because of material stiffness , microseparation , and sensitivity to impingement . To ascertain whether this potentially increased stress caused an increased cup migration we compared a ceramic-on-ceramic with a metal-on-polyethylene implant for cup migration . Sixty one patients ( 61 hips ) undergoing THA for osteoarthritis were  r and omized to ceramic on ceramic ( Ce/Ce ) or cobalt-chromium on cross-linked polyethylene bearings ( PE ) in the same uncemented cup shell . Migration was followed with RSA . At 2 years we observed similar mean cup translations in the 3 directions ( 0.07 - 0.40 mm vs. 0.05 - 0.31 mm , Ce/Ce vs. PE ) , as well as similar rotations around the 3 axes ( 0.31 - 0.92 ° vs. 0.57 - 1.40 ° ) . WOMAC and SF-36 scores were also similar and no radiolucent lines or osteolysis found . The large migration seen in some cups in both implant groups will require close monitoring to ascertain the reasons . Mean proximal wear of the polyethylene liners measured 0.016 mm between 2 and 24 months . Our data suggest there is no increased cup migration in the ceramic-on-ceramic implant compared with the metal-on-polyethylene , and they seem an equally safe choice . However , the low wear measured with the more versatile and less expensive cross-linked polyethylene makes it a strong contender . Levels of Evidence : Therapeutic Level I. See the Guidelines for Authors for a complete description of levels of evidence Introduction Short stem prostheses have been developed to preserve proximal femoral bone stock . This prospect i ve , r and omized study compared periprosthetic bone remodelling following short and straight stem implantation 1 year after surgery . Material s and methods One hundred and forty-four consecutive patients undergoing total hip arthroplasty were r and omized to either a Fitmore short or a cementless straight stem ( both Zimmer , Winterthur , Switzerl and ) . Periprosthetic bone mineral density ( BMD ) was measured using dual-energy X-ray absorptiometry performed the day before surgery and at 7 days , 3 months and 1 year postoperatively . Furthermore , the HHS and the WOMAC were obtained . Results One hundred and thirty-eight patients completed 1-year follow-up . Periprosthetic BMD changes at 1 year were most pronounced in the proximal medial region of interest ( ROI ) 7 with −17.2 % after short stem and −16.7 % after straight implantation ( p = 0.67 ) . However , there was significantly less BMD reduction in ROI 6 following short ( −4.7 % ) versus straight stem ( −10.8 % ) implantation ( p = 0.01 ) . There were no significant differences between the two groups in terms of the HHS and the WOMAC either before or after surgery . Conclusion One year after surgery , both stems showed an implant-specific periprosthetic bone remodelling . Nevertheless , proximal load transfer was more pronounced after short stem implantation than with a straight stem Background and purpose — We hypothesized that an ultra-short stem would load the proximal femur in a more physiological way and could therefore reduce the adaptive periprosthetic bone loss known as stress shielding . Patients and methods — 51 patients with primary hip osteoarthritis were r and omized to total hip arthroplasty ( THA ) with either an ultra-short stem or a conventional tapered stem . The primary endpoint was change in periprosthetic bone mineral density ( BMD ) , measured with dual-energy x-ray absorptiometry ( DXA ) , in Gruen zones 1 and 7 , two years after surgery . Secondary endpoints were change in periprosthetic BMD in the entire periprosthetic region , i.e. Gruen zones 1 through 7 , stem migration measured with radiostereometric analysis ( RSA ) , and function measured with self-administered functional scores . Results — The periprosthetic decrease in BMD was statistically significantly lower with the ultra-short stem . In Gruen zone 1 , the mean difference was 18 % ( 95 % CI : −27 % to −10 % ) . In zone 7 , the difference was 5 % ( CI : −12 % to −3 % ) and for Gruen zones 1–7 the difference was also 5 % ( CI : −9 % to −2 % ) . During the first 6 weeks postoperatively , the ultra-short stems  migrated 0.77 mm more on average than the conventional stems . 3 months after surgery , no further migration was seen . The functional scores improved during the study and were similar in the 2 groups . Interpretation — Up to 2 years after total hip arthroplasty , compared to the conventional tapered stem the ultra-short uncemented anatomical stem induced lower periprosthetic bone loss and had equally excellent stem fixation and clinical outcome Our aim in this prospect i ve study was to compare the bone mineral density ( BMD ) around cementless acetabular and femoral components which were identical in geometry and had the same alumina modular femoral head , but differed in regard to the material of the acetabular liners ( alumina ceramic or polyethylene ) in 50 patients ( 100 hips ) who had undergone bilateral simultaneous primary total hip replacement .  Dual energy X-ray absorptiometry scans of the pelvis and proximal femur were obtained at one week , at one year , and annually thereafter during the five-year period of the study . At the final follow-up , the mean BMD had increased significantly in each group in acetabular zone I of DeLee and Charnley ( 20 % ( 15 % to 26 % ) , p=0.003 ) , but had decreased in acetabular zone II ( 24 % ( 18 % to 36 % ) in the alumina group and 25 % ( 17 % to 31 % ) in the polyethylene group , p=0.001 ) . There was an increase in the mean BMD in zone III of 2 % ( 0.8 % to 3.2 % ) in the alumina group and 1 % ( 0.6 % to 2.2 % ) in the polyethylene group ( p=0.315 ) . There was a decrease in the mean BMD in the calcar region ( femoral zone 7 ) of 15 % ( 8 % to 24 % ) in the alumina group and 14 % ( 6 % to 23 % ) in the polyethylene group ( p<0.001 ) . The mean bone loss in femoral zone 1 of Gruen et al was 2 % ( 1.1 % to 3.1 % ) in the alumina group and 3 % ( 1.3 % to 4.3 % ) in the polyethylene group ( p=0.03 ) , and in femoral zone 6 , the mean bone loss was 15 % ( 9 % to 27 % ) in the alumina group and 14 % ( 11 % to 29 % ) in the polyethylene group compared with baseline values . There was an increase in the mean BMD on the final scans in femoral zones 2 ( p=0.04 ) , 3 ( p=0.04 ) , 4 ( p=0.12 ) and 5 ( p=0.049 ) in both groups . There was thus no significant difference in the bone remodelling of the acetabulum and femur five years after total hip replacement in those two groups where the only difference was in the acetabular liner Background Anatomic short femoral prostheses with a prominent lateral flare have the potential to reduce stress-shielding in the femur through a more physiological stress distribution to the proximal femur . We present the design rationale of a new short uncemented , proximally fixed anatomic femoral implant and the study design of a prospect i ve multi-centre trial to collect long-term patient outcome and radiographic follow up data . Methods A prospect i ve surveillance study ( trial registry NCT00208555 ) in four European centres ( UK , Italy , Spain and Germany ) with a follow up period of 15 years will be executed . The recruitment target is 200 subjects , patients between the ages of 18 and 70 admitted for primary cementless unilateral THA will be included . The primary objective is to evaluate the five-year survivorship of the new cementless short stem .  The secondary objectives of this investigation are to evaluate the long term survivorship and the clinical performance of the implant , the impact on the subjects health related Quality of Life and the affect of the prosthesis on bone mineral density . Peri- and postoperative complications will be registered . Clinical and radiographic evaluation of prosthesis positioning will be done post-operatively and at 3 , 6 , 12 , 24 , 60 , 120 and 180 months follow up . Discussion Shortening of the distal stem can maximise bone and soft tissue conservation . New stem types have been design ed to improve the limitations of traditional implants in primary THA . A new , uncemented femoral short stem is introduced in this paper . A long-term follow up study has been design ed to verify stable fixation and to research into the clinical outcome . The results of this trial will be presented as soon as they become available Background We developed a total hip system using osseointegration guidelines , a metaphyseal-loading proximal femoral replacement in the retained neck and a dual-geometry titanium shell in the acetabulum . Patients and methods A r and omized controlled clinical trial was undertaken in 52 patients ( 53 hips ) , using the cemented Spectron stem and cementless Harris-Galante II cup as control implants  ( 24 patients in experimental group , 29 control patients ) . Clinical measures of Harris Hip Score ( HHS ) , pain score and radiostereometric analysis ( RSA ) at regular intervals for up to three years were used to monitor progress . Results No statistically significant differences were found in HHS and pain score ; the stability of the cementless experimental implant was also comparable to that of the cemented controls by RSA . 3 revisions were required for migration in the experimental group and 1 was required for component dislocation in the control group . Interpretation Our findings indicate the practicality of osseointegration of titanium implants , but suggest that current performance is inadequate for clinical introduction . However , the stable fixation achieved in the retained neck in the majority of patients is indicative of osseointegration . This finding will encourage technical and design improvements for enhancement of clinical osseointegration and should also encourage further study . Periprosthetic osteolysis might be avoided by the establishment and maintenance of direct implant-bone connection : “ osseointegration ” Clinical function , bone mineral density ( BMD ) , and radiographs of 80 r and omly allocated , hydroxyapatite-coated femoral stems of two differing lengths  were studied for 2 years . The short stem was optimized for proximal fixation . The predictive value of bone densitometry was also studied . After 2 years , significantly more bone apposition and a higher BMD percentage were observed in Gruen zone 7 of the short stem . We conclude that stem design can be enhanced to achieve more proximal fixation . However , we found a higher incidence of pain with the short stem , indicating a trade-off between increased proximal fixation and diminished overall mechanical stability . No strong correlations between clinical function and radiographic evaluation of remodeling were found with BMD , suggesting that dual-energy x-ray absorptiometry has no predictive value for short-term clinical outcome BACKGROUND Femurs of dysplastic hips exhibit specific abnormalities , and use of modular or specially design ed components is recommended . An anatomic short stem was previously design ed specifically for dysplastic hips using 3-dimensional data acquired from dysplastic patients . To investigate effects of stem geometry on bone remodeling , we undertook a prospect i ve , r and omized study of patients who had undergone 1-stage bilateral total hip arthroplasty ( THA ) with the anatomic short stem on one side and a conventional straight stem on the other . METHODS The study included 36 patients who underwent the above THA procedure . We assessed bone mineral density as well as the presence of cancellous condensation or bony atrophy due to stress shielding based on the analysis of Gruen 's zones and newly defined equal-interval zones , at an average follow-up period of 9.2 years . RESULTS All stems were bone ingrown stable . Cancellous condensation was observed more proximally , and areas of bone atrophy were narrower on the anatomic short stem side than on the straight stem side . Bone mineral density values reflected results of cancellous condensation and stress shielding and were higher in more proximal zones on the anatomic short stem side than on the straight stem side . CONCLUSION Although radiographic results indicated good midterm outcomes of THA with both stems , the loading pattern differed . The anatomic short stem achieved its design purpose in terms of proximal fixation and load transfer and led to better preservation of the proximal femur We investigated prospect ively the bone mineral density ( BMD ) of the proximal femur after implantation of a tapered rectangular cementless stem  in 100 patients with a mean age of 60 years ( 16 to 87 ) . It was determined using dual energy x-ray absorptiometry , performed one week after surgery and then every six months until the end-point of five years . The BMD increased significantly in Gruen zones 2 , 4 and 5 by 11 % , 3 % and 11 % respectively , and decreased significantly in Gruen zones 1 , 6 and 7 by 3 % , 6 % and 14 % respectively , over the five-year period . The net mean BMD did not change over this time period . The changes in the BMD were not confined to the first 12 months after surgery . This investigation revealed no change in the overall periprosthetic BMD , but demonstrated a regional redistribution of bone mass from the proximal to distal zones Hydroxyapatite-coated femoral components were introduced to enhance fixation , but concerns were raised about whether the coating would be maintained over time . We therefore determined the long-term clinical and radiographic results of a proximally hydroxyapatite-coated femoral component and compared the mechanical failure rate to other fixation methods at similar lengths of followup . The study group , culled from a large , multicenter prospect i ve study population , consisted of 146 patients ( 166 hips ) with followup of 15 to 18 years . Average age at time of the index procedure was 51 years , and the most common diagnoses were osteoarthritis ( 71 % ) and osteonecrosis ( 11 % ) . Average Harris hip scores were 42.7 preoperatively and 91.5 at most recent followup . Radiographically , one stem showed stable fibrous fixation , and all other unrevised stems were bony stable . Of 13 stem revisions in the study population , only one stem has been revised for aseptic loosening . Forty-nine percent of hips have an osteolytic lesion in proximal areas of Gruen Zones 1 , 7 , 8 , or 14 only . Both the femoral aseptic revision and mechanical failure rates are 0.6 % at 15-year minimum followup . The data demonstrate excellent long-term survivorship of this hydroxyapatite-coated femoral component used in a relatively young patient group . Level of Evidence : Level IV , therapeutic study . See the Guidelines for Authors for a complete description of levels of evidence BACKGROUND Cementless femoral stems in total hip arthroplasty provide dependable clinical and radiographic results in the treatment of osteoarthritis . Stem length might affect the preservation of proximal bone stock and stability . We hypothesized that a shorter stem decreases proximal bone loss without affecting implant stability . METHODS We r and omly assigned 60 patients aged between 50 and 70 years to either a st and ard cementless femoral stem or a 35-mm shorter version . Patients were followed with dual-energy X-ray absorptiometry , radiostereometric analysis , Harris hip score , Western Ontario and McMaster Universities Osteoarthritis Index score , and clinical follow-up at 3 , 6 , 12 , and 24 months . The trial is registered on Clinical Trials.gov/. RESULTS After 24 months , short stems had on average 3.8 % ( 95 % confidence interval , 1.2%-8.9 % ) more bone loss in zone 1 compared to st and ard stems ( P = .14 ) . In zone 7 , the bone loss was on average 6.5 % ( 95 % confidence interval , 6.6%-19.7 % ) higher compared to st and ard stems ( P = .33 ) . After 24 months , st and ard stems had migrated 0.93 mm ( range , 0.25 - 4.66 mm ) and short stems 0.93 mm ( range , 0.17 - 2.96 mm ; Student t-test after log transformation , P = .3 ) . Patient-reported outcome measures were similar in both groups . One patient in the st and ard stem group was diagnosed with infection , one with a posterior dislocation , and one with a deep venous thrombosis . No stems were revised . CONCLUSION There were no statistically significant differences in periprosthetic bone loss or fixation between the stems at 24 months Background Because the clinical and radiographic performance of an ultrashort anatomic cementless stem has been investigated in only two r and omized controlled studies , well- design ed trials should aim for a thorough comparison of the outcomes of ultrashort anatomic cementless and conventional anatomic cementless stems . Questions / purpose sThe purpose s of this study were to compare ( 1 ) the clinical results , including Harris hip score , thigh pain , and WOMAC index score , ( 2 ) radiographic results , ( 3 ) bone mineral density ; and ( 4 ) proportions of patients undergoing revision of a THA using an ultrashort anatomic cementless stem versus a conventional anatomic cementless stem  in the same patients who underwent bilateral sequential THAs under the same anesthetic . Methods Two hundred patients ( mean age , 53 years ; range , 26–54 years ) who underwent bilateral sequential THAs received an ultrashort anatomic cementless stem in one hip and a conventional anatomic cementless stem in the contralateral hip . From January 2004 to December 2005 , we performed 524 same-day bilateral short and conventional anatomic cementless THAs  in 262 patients , of whom 212 ( 81 % ) participated in this study . Five patients were lost to followup before 2 years , five were lost between 2 to 10 years , and two were lost between 10 to 13 years , leaving 200 patients . Patients who had end-stage bilateral hip disease and were younger than 55 years were selected for inclusion . The predominant diagnoses were osteonecrosis ( 118 patients , 59 % ) and osteoarthritis ( 44 patients , 22 % ) . One hundred thirty-eight were men and 62 were women . At the time of each followup , the patients were assessed clinical ly and radiographically . In addition , each patient completed the WOMAC and the University of California Los Angeles ( UCLA ) activity scores . The minimum followup was 10 years ( mean , 11.8 years ; range , 10–13 years ) . Followups were done in person , with all images and followup clinic notes . Based on the power analysis , we estimated a sample size of 178 hips was needed in each group to detect a 3-point difference in the Harris hip score with 80 % power . Results At the latest followup , there were no differences between the two groups regarding the mean Harris hip scores ( 94 versus 94 points ; p = 0.189 ) , mean WOMAC scores ( 17 versus 16 points ; p = 0.191 ) , or mean UCLA activity scores ( 9 versus 9 points ; p = 0.381 ) . Two patients in the ultrashort stem group and one patient in the conventional stem group had severe ( 9 points ) thigh pain , and 30 patients ( 15 % ) in the conventional stem group had mild thigh pain ( 2 or 3 points ) after vigorous exercise . Bone mineral density in the ultrashort and conventional stem groups , respectively , was greater in the ultrashort stem group than in the conventional stem group . Bone mineral density in Zone 1 at 12 years was 3.29 versus 1.88 g/cm2 ( p = 0.021 ) , and 2.97 versus 0.91 g/m2 in Zone 7 ( p = 0.001 ) . With the numbers available , there were no differences between the stem design s in terms of the proportion undergoing revision ( one hip , 0.5 % , in the short-stem group versus one hip , 0.5 % , in the conventional group ; p = 1.881 ) . Conclusions At followup into the second decade , ultrashort stems showed no differences from conventional cementless stems in terms of vali date d outcomes scores or fixation , although less stress shielding was observed . Reduction of stress shielding may reduce the long-term risk of periprosthetic fracture , but this was not shown in our study .Level of Evidence Level I , therapeutic study Background : The early experience with cementless total hip replacement led to design modifications to increase the initial press-fit and stability of the femoral component , to reduce the diameter of the femoral head , and to improve the acetabular component , including the locking mechanism of the shell and the quality of the polyethylene liner . We performed a prospect i ve study to assess the results in young patients who had been followed for a minimum of eight years after treatment with a primary total hip arthroplasty with a second-generation cementless prosthesis . Methods : Eighty patients ( 118 hips ) were included in the study . There were fifty-eight men and twenty-two women ; the mean age at the time of the operation was 46.8 years ( range , twenty-one to forty-nine years ) . We used a cementless Duraloc series-100 or 1200 acetabular component with or without screw fixation , a polyethylene liner with a 22-mm inner diameter , and a cementless Profile femoral component in all hips . The average duration of follow-up was 9.8 years ( range , eight to eleven years ) . Clinical follow-up ( with use of the Harris hip score ) and radiographic follow-up were performed at six weeks ; at three , six , and twelve months ; and yearly thereafter . Linear and volumetric wear were measured , and bone-remodeling and osteolysis were assessed . Results : The average Harris hip score improved from 48.8 points preoperatively to 92 points at the final follow-up examination . The prevalence of transitory thigh pain was 10 % ( twelve of 118 hips ) . There was no aseptic loosening . One hip was revised because of recurrent dislocation . The average amount of linear wear was 1.18 mm , and the average wear rate was 0.12 mm/yr . Fourteen hips ( 12 % ) had osteolysis in the calcar femorale and eleven hips ( 9 % ) had acetabular osteolysis , but all of the osteolytic lesions were < 1 cm 2 . Conclusions : The mechanical fixation of the anatomic fit cementless Profile stem was excellent in this study of young patients who were particularly difficult to treat because of a high prevalence of osteonecrosis and developmental dysplasia . Although there was no aseptic loosening of the components and a relatively low prevalence of osteolysis , there was a high rate of linear wear of the polyethylene liner . Level of Evidence : Therapeutic study , Level IV ( case series [ no , or historical , control group ] ) . See p. 2 for complete description of levels of evidence The relatively high prevalence of thigh pain and stress shielding associated with the AML porous-coated cementless femoral component led to the development of the Prodigy ® , a femoral component with more extensive porous-coating and a distal polished bullet tip with medial diaphyseal relief to potentially decrease the flexural rigidity . We prospect ively evaluated a cohort of 100 consecutive cementless total hip arthroplasties performed using this device . The minimum followup was 10 years ( mean , 11.4 years ; range , 10–12 years ) . At 10-year followup , 69 of the 86 patients ( 82 hips ) were living , 14 patients with 15 hips were deceased , and three patients with three hips were lost to followup . No hips required a stem revision . Two patients ( two hips ) complained of thigh pain . All hips were bone ingrown . Distal tip radiolucencies and osteolysis occurred in 13 hips ( 17 % ) and none , respectively . Twenty-one hips ( 28 % ) demonstrated moderate or severe stress shielding . Only further followup will determine if this could be a clinical problem or one with revision surgery . These results encourage the authors to continue using second-generation extensively coated stems in their primary total hip arthroplasty constructs . Level of Evidence : Level III , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence
target: Our results suggest that compared with CS , SS may provide superior bone remodelling and similar survival rates and clinical outcomes .
  However , the short-term follow-up of the included studies was inadequate to determine the long-term performance of SS
background: OBJECTIVE Cementless total hip arthroplasty (  THA ) is associated with reliable clinical results and high patient satisfaction .
  Short-stem prostheses ( SS ) were design ed to achieve superior preservation of proximal bone stock and stability compared with those of conventional-stem prostheses ( CS ) .
  This meta- analysis was conducted to determine the proximal bone remodelling , revision rate , Harris Hip Score , radiolucent line and maximum total point motion values of both SS and CS for primary THA .