Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems

Background

Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs.

Initial femoral stem position in cementless bipolar hemiarthroplasty for femoral neck fracture in elderly patients is associated with early implant subsidence: A radiographic analysis

BackgroundBipolar hemiarthroplasty is a well-established treatment for displaced femoral neck fracture in elderly patients. Implant subsidence is a potential complication with cementless femoral stems, and smaller canal fill ratio has been reported as a radiographic risk factor. We aimed to determine the risk factors for subsidence, particularly the initial implant position relative to the resected medial calcar of proximal femur.MethodsWe retrospectively reviewed all cementless bipolar hemiarthroplasties performed using a single proximally hydroxyapatite-coated femoral stem in patients with a minimum radiographic follow-up of 12 weeks between January 2017 and December 2018. The amount of subsidence (significant subsidence defined as ≥ 5 mm), canal fill ratio, and implant position relative to the point of resected medial calcar (position A: medial and superior to calcar; position B: lateral and superior to calcar; position C: lateral and inferior to calcar) were measured and analyzed.ResultsOne-hundred eighty patients were identified (mean age: 80.9 years). Significant subsidence was observed in 52 patients (28.9%). On multivariate analysis, older age, lower canal fill ratio, implant position B, C, and less medial overhang of stem were independent risk factors for early implant subsidence. The risk ratio of position B and C to position A was 5.13 (95% confidence interval, 2.23-11.80).ConclusionIn our analysis, older age and lower canal fill ratio were associated with increased risk of subsidence, whereas implant with position A and more medial overhang were less prone to subsidence with the tapered proximally hydroxyapatite-coated implant.     

Impact of Femoral Stem Design on Failure After Anterior Approach Total Hip Arthroplasty

Background

An increased rate of complications related to femoral component failure has been described with less invasive total hip arthroplasty (THA). This study evaluated the incidence of femoral complications associated with the direct anterior approach for THA.

Outcomes of Cerclage Cabling for Intraoperative Calcar Cracks in Cementless Total Hip Arthroplasty Using Broach-Only,Tapered Wedge Stems

BackgroundIntraoperative femoral fractures are well-known but often overlooked complications in total hip arthroplasty (THA). We examined outcomes of cerclage cabling for intraoperative calcar cracks in THA with cementless tapered wedge stems.MethodsIn total, 4928 primary THAs were performed using broach-only, tapered wedge stems between January 2007 and November 2017 in a single institution. Of these, we identified 71 intraoperative calcar cracks (69 patients) managed by 2-mm cerclage cables. Clinical outcomes, amount of stem subsidence, and implant survivorship of the calcar crack group (68 THAs) were compared with those of the matched control group (68 THAs) without intraoperative fractures. Multivariate analysis was performed to identify potential risk factors for stem subsidence >3 mm.ResultsThe mean stem subsidence was greater in the calcar crack group (2.0 vs 1.2 mm, P = .021), whereas revision-free survivorships of THA were similar between groups at 6 years (98.5% vs 98.4%; log-rank, P = .987). In the calcar crack group, a Dorr type C femur and the absence of cabling proximal to the lesser trochanter (LT) were identified as independent risk factors for stem subsidence >3 mm. For the subgroup with 42 calcar cracks managed by a single cable applied proximal to the LT, revision-free survivorship of THA was 100% at 6 years. There was no complete radiolucency to indicate aseptic stem loosening in either group.ConclusionThe application of a single cable proximal to the LT of the femur for intraoperative calcar cracks demonstrated 100% revision-free survivorship with lower stem subsidence in THA with tapered wedge stems.     

The influence of over-reaming on stem stability in reverse shoulder arthroplasty

BackgroundContemporary cementless reverse total shoulder arthroplasty (RSA) systems utilize a range of interference conditions based on the geometric relationships between the system instrumentation and the prosthesis design. The impact of prosthesis/bone interference, however, on the primary stability of the stemmed humeral component has not been characterized. The aim of this study was to evaluate the effect of over-reaming, standard reaming, and use of an upsized stem on stem stability in press fit reverse shoulder arthroplasty.MethodsThree-dimensional humeral models were generated from CT data of 59 non-arthritic shoulders. Each model was prepared following the intended surgical technique, including resection of the humeral head and reaming of the humeral canal, assuming 1 mm spacing in reamer diameters. The appropriate humeral stem (2 mm increments in distal stem diameter) was then placed to represent instances of over-reaming (increased distal clearance between stem and reamed bone), standard reaming, and use of an upsized stem. Finite element analysis was performed to predict the primary stability of the humeral stem subjected to expected loads in RSA.ResultsOver-reaming was associated with both increased stem subsidence as well as stem-bone micromotion, as compared to standard bone preparation (P < 001). No significant differences in stem translation or stem-bone micromotion were found between standard bone preparation and use of an upsized stem. Over-reaming was associated with approximately 50% increased rotation of the stem following functional loading, as compared to stems placed using standard preparation or upsized stems.ConclusionOver-reaming of the humeral canal in cementless reverse shoulder arthroplasty results in increased micromotion and decreased primary stability of the humeral stem when subjected to loading representative of daily activities. Use of an upsized stem can recover the primary stability expected for standard reaming.Level of EvidenceBiomechanical Study     

Results of 3,668 primary total hip replacements for primary osteoarthritis in patients under the age of 55 years

Background and purpose In a previous study based on the Finnish Arthroplasty Register, the survival of cementless stems was better than that of cemented stems in younger patients. However, the survival of cementless cups was poor due to osteolysis. In the present study, we analyzed population-based survival rates of the cemented and cementless total hip replacements in patients under the age of 55 years with primary osteoarthritis in Finland.

Patients and methods 3,668 implants fulfilled our inclusion criteria. The previous data included years 1980–2001, whereas the current study includes years 1987–2006. The implants were classified in 3 groups: (1) implants with a cementless, straight, proximally circumferentially porous-coated stem and a porous-coated press-fit cup (cementless group 1); (2) implants with a cementless, anatomic, proximally circumferentially porous-coated stem, with or without hydroxyapatite, and a porous-coated press-fit cup with or without hydroxyapatite (cementless group 2); and (3) a cemented stem combined with a cemented all-polyethylene cup (the cemented group). Analyses were performed separately for 2 time periods: those operated 1987–1996 and those operated 1997–2006.

Results The 15-year survival for any reason of cementless total hip replacement (THR) group 1 operated on 1987–1996 (62%; 95% CI: 57–67) and cementless group 2 (58%; CI: 52–66) operated on during the same time period was worse than that of cemented THRs (71%; CI: 62–80), although the difference was not statistically significant. The revision risk for aseptic loosening of cementless stem group 1 operated on 1987–1996 (0.49; CI: 0.32–0.74) was lower than that for aseptic loosening of cemented stems (p = 0.001).

Interpretation Excessive wear of the polyethylene liner resulted in numerous revisions of modular cementless cups. The outcomes of total hip arthroplasty appear to have been relatively unsatisfactory for younger patients in Finland.     

Radiographic and Clinical Outcomes of Modular Tapered Fluted Stems for Femoral Revision for Paprosky III and IV Femoral Defects or Vancouver B2 and B3 Femoral Fractures

BackgroundExtensive femoral bone loss poses a challenge in revision total hip arthroplasty (rTHA). Many techniques have been developed to address this problem including fully porous cylindrical stems, impaction bone grafting, and cementation of long stems, which have had varied success. Modular tapered fluted femoral stems (MTFS) show favorable results. We sought to determine the minimum 2-year radiographic and clinical performance of MTFS in rTHA in a population with extensive proximal femoral bone loss.MethodsOur clinical database was queried retrospectively for all patients who underwent rTHA with an MTFS. We included patients with Paprosky 3 and 4 femoral bone loss and patients with Vancouver B2 and B3 periprosthetic femur fractures. Patients without 2-year follow-up were invited to return to clinic for X-ray evaluation and to complete clinical questionnaires. We assessed distance of stem subsidence and presence of stem fixation on final X-ray. We recorded all-cause revision and survival of the stem at final follow-up.ResultsOne hundred twenty-nine patients were available for follow-up. Average follow-up time was 3.75 years. One hundred twenty-two stems (95%) remained in place at final follow-up. Median subsidence was 1.4 mm (range 0-21). All-cause revision rate was 16.3% (21 patients). Of the hips revised, 10 were for instability, 6 for infection, 1 for aseptic loosening, and 1 for periprosthetic femur fracture. Three were revised for other reasons. The stem was revised in 7 patients (5.4%), and the most common reason for stem revision was infection (5 patients). The other 2 stems were revised for aseptic loosening in a Paprosky 4 femur and periprosthetic femur fracture. Survival of tapered modular fluted stems with aseptic failure as an endpoint was 98.4%. The mean Hip disability and Osteoarthritis Outcome Score, Joint Replacement score at final follow-up was 73, and mean Veterans Rand 12 item health survey physical and mental scores were 32.8 and 52.2, respectively.ConclusionIn patients with Paprosky 3, 4 femoral defects or Vancouver type B2, B3 fractures, modular tapered fluted stems for femoral revision show excellent outcomes at minimum 2-year follow-up.     

Clinical and radiographic analysis of the Mallory-Head femoral component in revision total hip arthroplasty. A minimum 8.8-year and average eleven-year follow-up study

BACKGROUND: Although many designs of cementless femoral stems are available for revision hip arthroplasty, there is no consensus about which design features are required to achieve an optimal clinical outcome and maximum preservation of bone. The purpose of this study was to report the clinical and radiographic results for a specific design. METHODS: A selected series of 107 revision total hip arthroplasties with use of the Mallory-Head calcar-replacement prosthesis was reviewed with clinical and radiographic evaluation. The study group consisted of sixty-six hips (sixty patients), with an average follow-up of 11.5 years (range, 8.8 to 14.5 years). All revisions in this series were performed because of failure of a cemented or cementless femoral component of standard length. All revision stems were 220 mm long. RESULTS: Three of the 107 original stems demonstrated subsidence of 3, 7, and 9 mm. Two stems had definite loosening, resulting in a 1.9% rate of mechanical failure. The rate of survival was 94% with revision for any reason as the end point and 97.1% with revision because of mechanical failure (aseptic loosening) as the end point. The Harris clinical score was 49 points preoperatively and 80 points postoperatively. Radiographic analysis demonstrated that the average percentage of the diaphysis filled by the prosthesis was 86%. Fifty-four (88.5%) of the sixty-one hips with complete radiographic follow-up showed no stress-shielding on final radiographs, whereas seven hips (11.4%) showed some stress-shielding. CONCLUSIONS: This proximal load-bearing calcar-replacement design achieves reliable fixation and stability at intermediate-term follow-up. There is no deterioration in the clinical outcome or radiographic findings at an average of eleven years of follow-up. The prevalence of disuse osteopenia from stress-shielding is very low. Proper surgical technique includes maximum fill of the diaphysis of the femur, with contact of the collar on part of the proximal aspect of the femoral shaft.     

The Influence of Dorr Type and Femoral Fixation on Outcomes Following Total Hip Arthroplasty for Acute Femoral Neck Fractures: A Multicenter Study

BackgroundThe American Academy of Orthopaedic Surgeons guidelines report moderate evidence for cementing femoral stems for hip fractures, mainly derived from hemiarthroplasty literature. This is the first large, nonregistry study examining the influence of femoral fixation, implant type, patient characteristics, and radiographic factors on outcomes after total hip arthroplasty (THA) for acute femoral neck fractures.MethodsA multicenter retrospective study was performed of 709 THA cases (199 cemented, 510 cementless) for femoral neck fractures from 2006 to 2020 at three large academic institutions. Demographics, perioperative characteristics, and radiographs were reviewed. Kaplan-Meier survivorship curves were generated for multiple outcomes. Univariate and multivariate analyses were performed with P ≤ .05 denoting significance.ResultsCementless stems had a higher all-cause aseptic femoral revision rate (5.1 versus 0.5%, P = .002) and periprosthetic femoral fracture rate (4.3 versus 0%, P = .001). Each successive Dorr type had a higher fracture rate with cementless implants: 2.3%, 3.7%, and 15.9% in Dorr A, B, and C, respectively (P < .001). Logistic regression analyses confirmed that cementless stems (P = .02) and Dorr C bone (P = .001) are associated with periprosthetic fractures; collared implants and prophylactic cables did not protect against fractures. There was no difference in rates of dislocation, septic revision, or mortality between groups.ConclusionCementless stems during THA for femoral neck fractures have a higher aseptic femoral revision rate, specifically for periprosthetic fractures. Dorr C bone was particularly prone with an alarmingly high fracture rate. All fractures occurred in cementless cases, suggesting that cemented stems may minimize this complication.Level of EvidenceIII.     

Subsidence of Hydroxyapatite-Coated Femoral Stem in Dorr Type C Proximal Femoral Morphology

BackgroundGood bone quality and proper proximal femoral morphology are thought to be necessary for tapered design, cementless femoral stems to resist subsidence. Using tapered, cementless stem for patients with stovepipe morphology or Dorr type C is controversial. The purpose of this study is to analyze (1) subsidence of the fully hydroxyapatite (HA)-coated, tapered, cementless stem in different morphology according to Dorr classification, (2) subsidence of the stem related to radiographic canal-fill ratio.MethodsThe digitized radiographs of 311 consecutive cementless primary total hip arthroplasty with fully HA-coated, tapered stem were retrospectively reviewed. Subsidence and the canal-fill ratio at 4 locations were evaluated postoperatively after a minimum of 2 years of follow-up. The threshold of subsidence >3 mm was considered as a clinically significant migration.ResultsA multivariate regression analysis of subsidence across Dorr type, controlling for age, gender, and intraoperative calcar fracture, demonstrated 0.40 mm (P = .28) and 0.18 mm (P = .51) greater subsidence in Dorr type C and B when compared to Dorr type A. Age, gender, and calcar fracture had no influence on subsidence, whereas greater canal-fill ratio at 2 cm below lesser trochanter resulted in significantly less subsidence (P = .02). Additionally, all variables did not affect the risk of having subsidence >3 mm.ConclusionThe proximal femoral morphology has no statistically significant effect on the subsidence of fully HA-coated stem. Therefore, this stem type might be a viable option for Dorr type C. Increasing the canal-fill ratio at metadiaphyseal junction may ensure the stability of the stem.     

Oblique femoral osteotomy in cementless total hip arthroplasty: Prospective consecutive series with a 3-year minimum follow-up period

Success of total hip arthroplasty using cementless implants is dependent on intimate contact of the prostheses with viable host—bone and achievement of optimal fit and rigid implant fixation. A technique of oblique femoral osteotomy has been used to correct proximal femoral deformity and to facilitate difficult revision surgery in selected cases. This prospective study included 26 osteotomies performed in 25 consecutive patients with a minimum follow-up period of 3 years. The median follow-up period was 50 months. Eighty-four percent of the reconstructions remained in situ at the final follow-up examination, with 81% of them rated clinically excellent or good. Three stems were revised for aseptic loosening at a mean interval of 46 months. One additional femoral revision was necessary for nonunion of the osteotomy. Two of the remaining stems were classified as radiographically loose. Although oblique femoral osteotomy serves as a useful adjunct surgical technique in difficult femoral reconstructions, nearly 25% of the hips in this study either failed or were loose at the medium-term follow-up examination. Long-term success of this technique with cementless prostheses remains to be defined.     

Modern Revision Femoral Stem Designs Have No Difference in Rates of Subsidence

BackgroundBoth modular and monoblock tapered fluted titanium (TFT) stems have gained popularity over fully porous-coated cylindrical (FPCC) femoral stem designs, but limited data exist comparing subsidence rates following revision total hip arthroplasty (THA). The purpose of this study is to determine differences in subsidence and clinical outcomes among 3 revision femoral stem designs.MethodsWe reviewed a consecutive series of 335 patients who underwent femoral component revision to a cementless modular TFT (n = 225), monoblock TFT (n = 63), or FPCC (n = 47) stem between 2012 and 2019. We evaluated radiographic subsidence rates, re-revision rates, and patient-reported outcomes between the 3 stems. A multivariate regression analysis was performed to determine the independent effect of stem type on the risk of subsidence >5 mm.ResultsAt an average follow-up of 39 months (range, 12 to 96 months), there were no differences in mean subsidence rates (3.5 vs 2.4 vs 2.1 mm, P = .14), HOOS Jr scores (78 vs 74 vs 64 points, P = .15), or aseptic re-revision rates (4% vs 3% vs 0%, P = .29) between modular TFT, monoblock TFT, and FPCC stems. Although modular TFT stems were more often used in patients with extensive femoral bone loss (Paprosky III and IV), there were no differences in subsidence rates >5 mm among the 3 stems (P > .05) in multivariate analysis.ConclusionModular TFT, monoblock TFT, and FPCC femoral stem designs all perform well in revision THA with no difference in clinical outcomes or subsidence rates. Surgeons should select the stem which they feel is the most clinically appropriate.     

Direct anterior approach hip arthroplasty: How to reduce complications - A 10-years single center experience and literature review

BACKGROUNDThe direct anterior approach for total hip arthroplasty (DAA-THA) is increasing in popularity due to some advantages such as less surgical trauma, minimal dissection of soft tissues, shorter rehabilitation times, faster return to daily activities, lower incidence of dislocation. On the other hand, the literature reports a high rate of intraoperative complications, with many different rates and complication types in the published papers. AIMTo analyze our complications comparing results with the literature; to report measures that we have taken to reduce complications rate.METHODSAll DAA-THA patients with one year minimum follow up who were operated at a single high-volume centre, between January 2010 and December 2019 were included in this retrospective study. All surgeries were performed using cementless short anatomical or straight stems and press fit cups. Patients’ follow-up was performed, at 6 wk, 3 mo, then annually post-surgery with clinical and radiological evaluation. Primary outcomes were stem revision for aseptic loosening and all-cause stem revision. Second outcome was intra-operative and post-operative complications identification.RESULTSA total of 394 patients underwent DDA-THA from January 2010 and December 2019, for a total of 412 hips; twelve patients lost to follow-up and one patient who died from causes not related to surgery were excluded from the study. The average age at the time of surgery was 61 years (range from 28 to 78 years). Mean follow-up time was 64.8 mo (range 12-120 mo). Seven stems were revised. One cortical perforation, one trochanteric and lateral cortical wall intraoperative fracture, one diaphyseal fracture, three clinically symptomatic early subsidence and one late aseptic loosening. We also observed 3 periprosthetic fractures B1 according to the Vancouver Classification. Other minor complications not requiring stem revision were 5 un-displaced fractures of the calcar region treated with preventive cerclage, one early infection, one case of late posterior dislocation, 18 case of asymptomatic stem subsidence, 6 cases of lateral cutaneous femoral nerve dysesthesia.CONCLUSIONDAA is associated to good outcomes and lower incidence of dislocation. Complication rate can be reduced by mindful patient selection, thorough preoperative planning, sufficient learning curve and use of intraoperative imaging.     

Total Hip Arthroplasties for Hartofilakidis Type C1 and C2 High Hip Dislocations Demonstrate Similar Survivorship and Clinical Function at Minimum 10-year Follow-up With Cementless Implants

BackgroundThis study aimed to determine the differences in survivorship, clinical function, and complications among patients who have Hartofilakidis Type C1 or C2 developmental dysplasia of the hips and underwent total hip arthroplasty (THA) with cementless implants.MethodsThis retrospective study identified 84 Hartofilakidis Type C hips that underwent THA between 2002 and 2011 with a minimum 10-year follow-up (mean, 13 years, range, 10 to 19 years). Survivorship, latest Harris Hip Scores and satisfaction levels, radiographic outcomes (eg, implant stability, rate and length of subtrochanteric shortening transverse osteotomy, leg-length discrepancy, cup position, and orientation), as well as complications (eg, dislocation, periprosthetic fracture, periprosthetic joint infection) were compared to analyze the differences between Hartofilakidis C1 and C2 hips.ResultsBetween C1 and C2 hips, no difference existed in the 15-year cumulative Kaplan-Meier survivorship, with the endpoint defined as any reoperation (93.1 versus 90.8%), aseptic loosening combined with periprosthetic joint infection (93.1 versus 96.2%), or aseptic loosening (94.8 versus 96.2%), latest Harris Hip Score (87.1 versus 86.1%), vertical (6.1 versus 6.0 mm) and horizontal (11.5 versus 10.3 mm) distance to the anatomic center of rotation, postoperative leg length discrepancy (11.2 versus 15.5 mm), dislocation (5.2 versus 11.5%), stem aseptic loosening (6.9 versus 7.7%), periprosthetic fracture (3.4 versus 7.7%), and intraoperative femoral fracture (32.8 versus 23.1%). However, Type C2 hips demonstrated more severe preoperative leg length discrepancy (66.9 versus 42.5 mm) and required a higher percentage of subtrochanteric shortening transverse osteotomies (84.6 versus 36.2%) that were longer (33.7 versus 26.47 mm) than the Type C1 hips.ConclusionWith cementless cups positioned near the anatomic acetabular center and cementless stems combined with subtrochanteric shortening transverse osteotomies, THAs for the Hartofilakidis Type C1 and C2 hips demonstrated similar survivorship, clinical function, and complications.     

Loosening pattern in a cementless custom-made hip stem: X-ray analysis, finite-elements and photoelasticity measurements

Thirty-three X-press cementless stems (Depuy) manufactured according to standardized X-rays were inserted from 1992 to 1994. The patients' mean age was 49 (range 15-79) years with a mean follow-up of 32 (+/-6) months. A characteristic radiographic pattern of aseptic loosening with erosion of the medial cortex by the tip of the stem occurred in 28 patients and a valgus shift of the implant in 14 cases. A radiolucent line with increased sclerosis below the tip (zone Gruen 4) was observed in 17 cases. Four stems were revised due to histologically confirmed aseptic loosening. Biomechanical investigation of one of the revised stems with the typical pattern of valgus angulation and medial cortex erosion included photoelasticity and finite-element analysis. The intertrochanteric fit and fill obviously resulted in an unfavorable distribution of contact areas, including peaks of high stress on the medial tip of the stem. These experimental findings are even evident for a postulated rotational stability. The clinical and radiographic results of the cementless X-press stems do not seem to support the fixation concept of intertrochanteric fit and fill of femoral components.     

Metaphyseal‐Loading Anterolaterally‐Flared Femoral Stem in Cementless Total Hip Arthroplasty: Five‐ to Eleven‐Year Follow‐Up Evaluation

Using a nonlinear three‐dimensional finite element analysis simulating loading conditions, we designed a new type of proximal‐fitting, anterolaterally‐flared, arc‐deposit hydroxyapatite‐coated anatomical femoral stem (FMS‐anatomic stem; Japan Medical Materials, Osaka, Japan) for cementless total hip arthroplasty (THA) for Japanese patients with dysplastic hip osteoarthritis. The aim of the present study was to analyze the clinical and radiographic outcomes of the new stem. We reviewed 143 consecutive patients (164 hips; 13 men, 14 hips; 130 women, 150 hips; age at surgery, 56.6 ± 7.6 years, mean ± SD, range, 30–74) who underwent cementless THA using the FMS‐anatomic stem at a single institution, with a follow‐up period of 7.6 ± 1.6 years (range, 5.3–11.0). Harris Hip score improved from 46.1 ± 12.6 before surgery to 90.0 ± 8.9 points post‐THA. The 7.6‐year survival rate of the stem was 99.0% after revision for aseptic loosening. Radiographs at follow‐up confirmed the stability of the femoral stems within the femoral canal in all cases, with sufficient bone ingrowth. None of the patients had subsidence of the stem exceeding 2.0 mm within the femoral canal or changes in varus or valgus position of more than 2.0°. The FMS‐anatomic stem provided excellent results in patients with dysplastic hip osteoarthritis. Our analysis confirmed reduced radiolucency around the stem in Gruen zones, minimal subsidence, appropriate stress shielding, and promising medium‐term stability within the femoral canal in our patients.     

Anthropometric measurements to design best-fit femoral stem for the Indian population

Background:

The standard commercially available marketed prostheses sometimes may not be the best fit to Indian patients because of the large anatomic variation. Orthopedic surgeons always stress the need for a proper implant–patient match in hip joint replacements, in particular, for a cementless femoral stem. The complications of mismatch are aseptic loosening, improper load distribution, and discomfort. The present study was undertaken to compare the differences in dimensions between femurs of elderly Indians and those of populations from other regions in order to solve the problem of a possible geometric mismatch between a selected implant and the hip joint as far as Indian patients are concerned.

Materials and Methods:

Measurements were made using computer aided design techniques on computed tomography (CT) scanned images of 98 femurs (56 left and 42 right). The software used to convert the CT images into solid models was MIMICS^® (Materialize, Inc., Leuven, Belgium). The geometrical parameters, viz., the femoral head offset, femoral head center (HC), femoral head diameter, femoral head relative position, position of shaft isthmus, neck-shaft angle, bow angle, femoral neck length, canal flare index, femoral length, and canal width at various locations, were chosen to design best-fit standard femoral stems for cementless insertion. These data were compared with the published data of other countries.

Results:

A difference of 16.8% was found in the femoral head offset between Indian and Swiss populations, which can affect soft tissue tension and range of motion. At a distance of 20 mm above the lesser trochanter (LT), the anteroposterior (AP) canal width was found to differ by 45.4%, when compared with a French population which can affect the mechanical stability of femoral stem. Femoral dimensions of Indian male and female subjects have also been compared and differences evaluated. At the LT, the aspect ratio (ratio of mediolateral canal width and AP canal width) in case of males (1.198) is approximately13% higher than that of females (1.059).

Conclusions:

This study indicates a need for redesign of femoral stems. The obtained anthropometric femoral dimensions can be used to design and develop indigenous hip joint prosthesis in India. The results of this study can also be used in forensic anthropometric studies.     

Total hip arthroplasty using cementless grit-blasted femoral component: a minimum 10-year follow-up study

The grit-blasted cementless Spotorno (CLS) stem, which has excellent survival rates up to 10 years, is widely used in total hip arthroplasty (THA). We investigated the survivorships of CLS stems in THA at a minimum follow-up of 10 years and sought to identify factors that influence outcomes. A total of 227 hips of 191 patients who underwent cementless THA with a CLS stem were retrospectively reviewed at a mean follow-up of 12.3 years. All patients were evaluated clinically and radiographically according to implant type and surgery-related and patient-related factors. Survivorship was 97.2% when femoral revision for any reason was defined as the end point. Femoral revisions were performed in 3 hips because of periprosthetic fractures. Survivorship for all hips, using revision for any reason as the end point, was 92.6%. Two metal-on-metal THAs were revised because of aseptic loosening or osteolysis around the cup. No significant differences were evident for type of stem, type of bearing surface, stem alignment, or patient-related factors. However, a canal fill index of 80% or less was found to affect cortical remodeling, subsidence, and a change in stem position of 5° or more, which indicates that care must be taken not to undersize stems. In addition, in view of the revisions performed, bearing surfaces appear to importantly influence THA survivorship.