Aseptic Loosening Of Femoral Component Research Articles

Shall We Not Pressurise It? Effects of Bone Cement Pressurisation on Mortality and Revision Following Hip Hemiarthroplasty for Neck of Femur Fracture Patients: A Comparative Cohort Study.

This study aimed to compare 30-day post-operative mortality, and revision for aseptic femoral component loosening and all-causes following hip hemiarthroplasty performed with or without pressurisation of the bone cement in neck of femur fracture patients. Design: Retrospective cohort study. Level I trauma center. Patients ≥60 years with OTA/AO 31B who underwent a cemented hip hemiarthroplasty from 10th December 2007 (database inception) to 15th November 2023 (search date) were reviewed.Outcome Measures and Comparisons: Comparisons were made between patients who underwent hip hemiarthroplasty with versus without pressurisation of the bone cement for outcomes 30-day post-operative mortality, revision for aseptic femoral component loosening, and revision for all-causes. 406 procedures among 402 patients, and 722 procedures among 713 patients were performed with and without pressurisation of the bone cement respectively. Mean ages were 83.1 and 84.3 years (p=0.018), with 72.2% and 68.6% (p=0.205) females in the pressurised and non-pressurised cement patient groups respectively. There were no differences in 30-day post-operative mortality (7.2% versus 8.2%; HR 0.89, 95%CI 0.46-1.73, p=0.727). There were no differences in all-cause revision (HR 1.04, 95%CI 0.27-4.04, p=0.953). No revisions were performed for aseptic loosening. Survival at 10 years post-operatively was 15.3% (95%CI 11.46-19.64) and 12.6% (95%CI 7.67-18.82) among patients who underwent hemiarthroplasty with and without bone cement pressurisation respectively. There were no differences in 30-day post-operative mortality among patients who underwent hemiarthroplasty with, compared to, without bone cement pressurisation. Bone cement pressurisation did not confer any advantages for revision outcomes which may be attributed in part to patients' high mortality rate and low survival beyond 10 years post-operatively. Level III. See Instructions for Authors for a complete description of levels of evidence.

No Difference in Revision Rates or Patient-Reported Outcome Measures Between Surgical Approaches for Total Hip Arthroplasty Performed for Femoral Neck Fracture: An Analysis of 5,025 Primary Total Hip Arthroplasties From the New Zealand Joint Registry

BackgroundTotal hip arthroplasty (THA) for femoral neck fracture (FNF) can be performed through different surgical approaches. This study compared the revision rates and patient-reported outcome measures by surgical approach. MethodsData from the New Zealand Joint Registry were analyzed for patients undergoing primary THA for FNF from January 2000 to December 2021. A total of 5,025 THAs were performed for FNF; the lateral approach was used in 2,499 (49.7%), the posterior in 2,255 (44.9%), and the anterior in 271 (4.3%). The primary outcome measure was the all-cause revision rate. Secondary outcome measures included revision rates for: dislocation, aseptic femoral component loosening, periprosthetic fracture, and infection. Oxford Hip Scores (OHS) were also collected. Age, sex, body mass index, American Society of Anesthesiologists score, femoral head size, dual mobility use, femoral fixation, and surgeon experience were assessed as potential confounding variables. ResultsThere was no difference in the revision rates between lateral and posterior (P = .156), lateral and anterior (P = .680), or posterior and anterior (P = .714) approaches. There was no difference in the reasons for revision between the lateral and posterior approaches or 6-month OHS (P = .712). There was insufficient data to compare the anterior approach. ConclusionsThere is no difference in the overall revision rates, reasons for revision, or OHS between the lateral and posterior surgical approaches for THA performed for FNF. Insufficient data on the anterior approach is available for an accurate comparison. Level of EvidenceLevel III.

Porous Tantalum Tibial Metaphyseal Cones in Revision Total Knee Arthroplasty: Excellent 10-Year Survivorship

BackgroundHighly porous metal tibial metaphyseal cones (TMCs) are commonly utilized in revision total knee arthroplasty (TKA) to address bone loss and obtain biologic fixation. Mid-term (5 to 10 year) studies have previously demonstrated excellent survivorship and high rates of osseointegration, but longer-term studies are lacking. We aimed to assess long-term (≥ 10 year) implant survivorship, complications, and clinical and radiographic outcomes after revision TKA with TMCs. MethodsBetween 2004 and 2011, 228 revision TKAs utilizing porous tantalum TMCs with stemmed tibial components were performed at a single institution and were retrospectively reviewed. The mean age at revision was 65 years, the mean body mass index was 33, and 52% were women. Implant survivorship, complications, and clinical and radiographic outcomes were assessed. The mean follow-up was 6.3 years. ResultsThe 10-year survivorship free of aseptic loosening leading to TMC removal was 97%, free of any TMC removal was 88%, free of any re-revision was 66%, and free of any reoperation was 58%. The most common indications for re-revision were periprosthetic joint infection, instability, and aseptic femoral component loosening. The 10-year nonoperative complication rate was 24%. The mean Knee Society scores increased from 38 preoperatively to 69 at 10 years. There were 8 knees that had evidence of partial, progressive tibial radiolucencies at 10 years. ConclusionsPorous tantalum TMCs demonstrated persistently durable longer-term survivorship with a low rate of implant removal. The rare implant removals for component loosening or instability were offset by those required for periprosthetic joint infection, which accounted for 80% of cone removals. Porous tantalum TMCs provide an extremely reliable tool to address tibial bone loss and achieve durable long-term fixation in revision TKA. Level of EvidenceIV.

High femoral offset as a risk factor for aseptic femoral component loosening in cementless primary total hip arthroplasty

PurposeLateralized stems in primary cementless total hip arthroplasty (THA) showed to be associated with aseptic femoral loosening. However, femoral head length also affects femoral offset but was not considered so far. This study analyzed the impact of high femoral offset (hFO) combinations, formed by lateralized stems or large femoral head lengths, on aseptic femoral component loosening.MethodsRetrospective cohort study was performed including all patients that underwent primary cementless THA at our institution between July 2004 and December 2016. Patients were screened for aseptic femoral component loosening and grouped in aseptic loosening (AL) and non-aseptic loosening (nAL) group. Medical records were screened; implant details were noted and classified in hFO and standard femoral offset (sFO) combinations. Supposed risk factors for aseptic loosening were analyzed.ResultsTwo thousand four hundred fifty-nine THA could be included, containing 14 THA (0.6%) with aseptic femoral component loosening. The AL group contained 11 hFO combinations (78.6%), whereas in the nAL group, 1315 hFO combinations (53.8%) were used. Subgroup analysis showed significant difference between two groups for hFO combinations (p = 0.014), age (p = 0.002), NSAR (p = 0.001), and bilateral THA on same day (p = 0.001). The multiple logistic regression analysis showed that hFO combination was the only variable for increased probability of aseptic loosening (OR, 3.7; p = 0.04).ConclusionHigh femoral offset combinations, formed by lateralized stems or large femoral head lengths in our collective of standard straight stems implanted by an anterior approach, show a 3.7-fold increased probability for aseptic femoral component loosening. Adjustment of the postoperative protocol may be considered in these cases to ensure proper stem ingrowth.

Revision Total Hip Arthroplasty with Primary Stem or Full-Porous-Coated Long Stem for Aseptic Femoral Component Loosening: A Matched-Pair Study.

BackgroundRevision total hip arthroplasty (RTHA) for loosening the femoral stem is a technical challenge. Distally fixed, full-porous-coated long stems are widely accepted as the standard selection for these revisions. However, the success of primary stems in RTHA is not well known.MethodsThis study enrolled 24 patients with aseptic loosening of the femoral stem who underwent RTHA using primary stems. Another 72 patients with aseptic loosening who underwent RTHA using full-porous-coated long stems were matched in terms of operation date, proximal femoral bone stock (Paprosky classification), sex, and age. The primary and secondary outcomes of failure were the need for revision for any reason and the radiographic change in the stem respectively.ResultsIn the primary stem group, one patient had a periprosthetic fracture and received a second RTHA 2 years after the previous one. The primary outcome’s 5-and 10-year survival rates were both 95.8%. For the matched comparison group, one patient had an immediate periprosthetic fracture of the femoral shaft requiring further open reduction internal fixation surgery. Another patient had a full-porous-coated long stem breakage 6 years postoperatively, which required a second RTHA. The primary outcome’s 5-and 10-year survival rates were 98.6% and 97.2%, respectively.ConclusionPrimary stems can achieve non-inferior clinical success compared to a full-porous-coated long stem for aseptic stem loosening RTHA in patients with adequate proximal femoral bone stock.

Clinical Results of Revision Hip Arthroplasty for Neck-Taper Corrosion and Adverse Local Tissue Reactions Around a Modular Neck Stem

BackgroundAdverse local tissue reactions (ALTRs) around a modular neck stem at our institution lead to a 13.5% rate of revision. The purpose of this study was to report the clinical results of revision total hip arthroplasty (THA) in this patient population. MethodsWe identified 80 hips in 77 patients who underwent revision THA due to neck-stem corrosion. Intraoperative and postoperative complications, clinical outcomes, re-revision rates, and the postoperative ion levels were recorded. ResultsThe mean follow-up period after revision was 45.3 ± 16.3 months (range 24-81 months). There were no intraoperative mechanical complications during the revision surgery. Eight hips (10%) had postoperative complications related to the revision implant, of which 6/8 came to re-revision: postoperative implant dislocation in 4 hips—2 treated nonsurgically, aseptic loosening of femoral component in 2 hips, and periprosthetic femoral fracture in 2 hips. No patients had recurrence of ALTR nor the recurrence of groin pain within the follow-up period. With 2 exceptions, ion levels normalized within one year of the revision surgery. The survival rate was 94% (95% confidence interval 84-98) at 32 months and 82% (95% confidence interval 56-93) at 63 months after revision THA (using re-revision THA due to any reason as the endpoint). ConclusionIntraoperative complication, postoperative complication, and re-revision rates are equivalent to femoral revision surgeries for other causes (infection, fracture, loosening). We recommend selecting revision-type stems to minimize the risk of femoral loosening or periprosthetic fracture, and larger femoral heads or dual mobility bearings to minimize the risk of dislocation.

Long-term results of Zweymüller SLL femoral stem in revision hip arthroplasty for stage II and IIIA femoral bone defect: a 9-15-year follow-up study.

Loosening of femoral stem can be associated with a wide spectrum of bone loss that represents the most important factor for choosing the most appropriate revision implant. Positive outcomes in femoral revision were already observed with Zweymüller Alloclassic® SLL stem in short- and medium-term follow-up. The aim of the study is to analyse the clinical results of 31 patients who underwent prosthetic revision for aseptic loosening of femoral component with Zweymüller femoral stem and long follow-up. The series included 10 men and 21 women with a mean age of 66.24years at the time of revision surgery and a mean follow-up of 12.25years. Clinical and radiological evaluation was performed at 2months, 6months and yearly, using Harris Hip Score (HHS) and Engh's criteria and Brooker classification for heterotopic ossifications. At the last follow-up, the survival of the stem was observed in all patients (32 hips). The mean HHS was 77.83 ± 20.90. Clinical results were stated as excellent in 14 cases, good in 5 cases, fair in 4 cases and poor in 9 cases. Radiographic stability with fixation by bone ingrowth was observed in 15 cases and with fibrous ingrowth in 17 cases. Heterotopic ossifications grade III was observed in 4 cases and grade II in 3 cases. Zweymüller Alloclassic® SLL stem showed excellent or good results in about 59% of revision surgery for aseptic loosening. The survival rate of the stem at 9-15years of follow-up was satisfactory.

Mild Coronal Stem Malalignment Does Not Negatively Impact Survivorship or Clinical Results in Uncemented Primary Total Hip Arthroplasties With Dual-Tapered Implants

BackgroundProper component positioning in total hip arthroplasty (THA) is crucial for implant fixation and hip stability. The purpose of this study is to assess if neutral coronal stem alignment (0° ± 3°) improved long-term survivorship in uncemented femoral components. MethodsBetween 2005 and 2010, 1028 primary THAs were performed with 2 contemporary dual-tapered, proximally coated uncemented stem types. Alignment was measured immediately postoperatively and at most recent follow-up. In total, 978 femoral stems (95%) were within 0° ± 3° of the neutral anatomic coronal axis, and the 50 stems (5%) outside that range were considered outliers (3.1° of valgus to 4.8° of varus). Outcomes analyzed included implant survivorship, Harris Hip Scores, and incidence of dislocation. Mean follow-up was 5 years. ResultsSurvivorship free of aseptic femoral component loosening was 99.3% and 98.2% at 5 and 8 years in the neutral group vs 100% at 5 and 8 years in the outlier group (P = .98). Survivorship free of femoral component revision for any reason was 99.1% and 97.3% at 5 and 8 years vs 100% at 5 and 8 years, respectively (P = .80). Harris Hip Scores were similar (89 in both groups; P = .84) at most recent follow-up. The incidence of mild to moderate thigh pain was also similar in both groups (6.1% vs 6%, P = .85). The incidence of dislocation was 1.5% at 8 years, and similar between both groups (P = .77). ConclusionSlight malalignment of contemporary dual-tapered uncemented THA femoral components does not appear to negatively impact survivorship or clinical outcomes, which is in contrast to cemented femoral components. Level of evidence IIICase-control study.

Do High-Flexion Total Knee Designs Increase the Risk of Femoral Component Loosening?

BackgroundThe purpose of our prospective, randomized, long-term investigation is to compare the aseptic loosening rate of the femoral component of the total knee prosthesis and clinical and radiographic results of high-flexion posterior cruciate-substituting knee prosthesis or standard posterior cruciate-substituting knee prosthesis in the same patients. MethodsThere were 960 patients (mean age 71.3 years). The mean follow-up period was 13.2 years (range 10-14). The patients were assessed clinically and radiographically with rating systems of the Knee Society. Furthermore, Western Ontario and McMaster Universities Osteoarthritis questionnaire and ranges of knee motion were determined in both groups. ResultsIn the high-flexion knee group, 2 knees (0.2%) had aseptic loosening of both femoral and tibial components. In the standard knee group, 2 knees (0.2%) had aseptic loosening of the femoral component only. The mean postoperative knee scores (97 vs 97 points), Western Ontario and McMaster Universities Osteoarthritis scores (19 vs 19 points), and range of knee motion (128° vs 129°) were not significantly different between the 2 groups. Two knees (0.2%) in the high-flexion knee group underwent a revision of both femoral and tibial components and 2 knees (0.2%) in the standard knee group had a revision of the femoral component only. ConclusionAfter a mean of 13.2 years of follow-up, this study did not show increased incidence of femoral component loosening in the high-flexion knee group. Furthermore, we found no significant differences between the 2 groups with regard to clinical or radiographic parameters or range of knee motion.

Aseptic loosening of uncemented femoral components in long-term hemodialysis patients: a systematic review of the literature

Background: The purpose of this study was to determine if reliable cementless fixation in hip arthroplasty can be achieved in patients on long-term hemodialysis. Methods: A systematic review was conducted with an emphasis on aseptic loosening of femoral components in total hip arthroplasty and hemiarthroplasty. Studies were analyzed using the Methodological Index for Nonrandomized Studies (MINORS) instrument and the Center for Evidence-Based Medicine’s Levels of Evidence Scale. Six lower-quality cases series were included. Results: Rates of radiographic evidence of loosening and revision caused by aseptic loosening ranged from 0% to 100%. Data pooling could not be performed because of heterogeneity of the studies included. Conclusions: It appears that patients with end-stage renal disease have bone stock suitable for cementless fixation. However, the varying outcomes reported in the literature reflect that the factors leading to early loosening of femoral components in dialyzed patients still remain unclear.

Performing high flexion activities does not seem to be crucial in developing early femoral component loosening after high-flexion TKA.

BackgroundIt is still unclear whether high flexion (HF) activities correlated with the early loosening of the femoral component and whether HF activities are possible. We investigated what is the capability for performing various HF activities, and whether high flexion activities increase the chance of aseptic loosening after HF-TKA.MethodsWe retrospectively analysed 260 patients who underwent HF-TKA using the NexGen LPS Flex between 2001 and 2009. The mean follow-up was 6.7 years (range, 5–13). We evaluated range of motion, Knee Society scores, WOMAC, and serial radiographs for aseptic loosening. Responses to questions on individual HF activities were recorded on 5-point Likert scales based on difficulty (0–4). Patients were divided two groups based on their responses to squatting and kneeling, which were important weight-bearing HF activities in Asian population (HF group vs. non-HF group) for comparisons of aseptic loosening and clinical outcomes.ResultsMore than 80 % of patients positively responded for various HF activities. The capability of HF activities showed that cross-legged sitting, squatting, and kneeling were 97.7, 51.1 and 52.7 % at the latest follow-up, respectively. Aseptic loosening was identified in two tibial components (0.8 %) but none in femoral components in non-HF group. There was no significant difference of aseptic loosening based on HF activities (0.8% vs. 0%, p = 0.063).ConclusionsThe results of this study suggest that HF activities do not seem to be associated with aseptic loosening of femoral component after HF-TKA.

A new design of cemented stem using functionally graded materials (FGM).

One of the most frequent complications of total hip replacement (THR) is aseptic loosening of femoral component which is primarily due to changes of post-operative stress distribution pattern with respect to intact femur. Stress shielding of the femur is known to be a principal factor in aseptic loosening of hip replacements. Many designers show that a stiff stem shields the surrounding bone from mechanical loading causing stress shielding. Others show that reducing stem stiffness promotes higher proximal interface shear stress which increases the risk of proximal interface failure. Therefore, the task of this investigation is to solve these conflicting problems appeared in the cemented total hip replacement. The finite element method and optimization technique are used in order to find the optimal stem material which gives the optimal available stress distribution between the proximal medial femoral bone and the cement mantle interfaces. The stem is designed using the concept of functionally graded material (FGM) instead of using the conventional most common used stem material. The results showed that there are four feasible solutions from the optimization runs. The best of these designs is to use a cemented stem graded from titanium at the upper stem layer to collagen at the lower stem layer. This new cemented stem design completely eliminates the stress shielding problem at the proximal medial femoral region. The stress shielding using the cemented functionally graded stem is reduced by 98% compared to titanium stem.

Material tailoring of the femoral component in a total knee replacement to reduce the problem of aseptic loosening

Aseptic loosening of femoral components is a significant problem affecting the life of current total knee replacements. To help reduce the problem of aseptic loosening, a new metal–ceramic poros functionally graded biomaterial (FGBM) has been designed to replace the existing metal alloy material normally used. In order to investigate the effect of using a FGBM on distal femur stresses compared to using standard material in a femoral component, a three-dimensional finite element model of the knee prosthesis has been developed. The results of the modeling and subsequent analysis indicate that by using the new FGBM compared to the existing material in a femoral component, higher levels of stress can be realized in the adjacent bone area of the femur and as a consequence reduce harmful atrophy effects. Also, by a judicious choice of material combinations and variation of porosity in the FGBM, the surface properties can be tailored to improve wear resistance at the articular interface and bone anchorage at the femoral end, as well as varying the stiffness in the core of the femoral component. Therefore, the use of the new FGBM improves the performance of knee prostheses by addressing concurrently the three current leading causes of failure; stress-shielding of the bone by the implant, wear of the articular surfaces, and the development of soft tissue at the bone/prosthesis interface as a result of relative implant motion.

Aseptic loosening of femoral components – Materials engineering and design considerations

Aseptic loosening is one of the main reasons for the revision of a total knee replacement (TKR). The design of the key component of a TKR, the femoral component, is particularly problematic because its failure can be the result of different causes. This makes the development of new biomaterials for use in the femoral component a challenging task. This paper focuses on the engineering design aspects in order to understand the limitations of current materials and design deficiencies. The paper describes the introduction of a new biomaterial for a femoral component and justifies the recommendation to use multi-functional materials as a possible solution to aseptic loosening. The potential advantages of applying functionally graded biomaterials (FGBMs) in prosthetic femur are explained by reducing the leading causes of failure including wear, micro-motion and stress-shielding effect. The ideas presented in this paper can be used as the basis for further research on the feasibility and advantages of applying FGBM in other superior implant designs.

Aseptic loosening of femoral components – A review of current and future trends in materials used

The variety of new biomaterials and different surface treatments being applied to existing materials all intended for total knee replacement (TKR) are self-evident of the demand for longer lasting knee prostheses. Aseptic loosening is one of the main reasons for the revision of TKR components including the femoral component, which has more challenging problems because of the different causes of failure. This paper therefore, focuses on aseptic loosening of femoral components and materials options available. Several current and promising new metallic, ceramic and polymeric biomaterials are discussed to highlight their advantages and their shortcomings. It is concluded that current materials have their limitations and there is a need for more sophisticated multi-functional materials to be developed in order to match the biological and mechanical complexity of the prosthetic femur.

High Early Failure Rate of the Columbus® Posterior Stabilized High-flexion Knee Prosthesis

Most studies report high survivorship rates for TKAs, however, we observed higher than anticipated rates of dislocation and femoral component loosening after implanting a Columbus posterior stabilized prosthesis. We therefore determined (1) the incidence of dislocation and aseptic loosening that occurred after implantation of posterior stabilized high-flexion prostheses in TKAs, (2) the causative factors of dislocation and aseptic femoral component loosening when comparing two designs of prostheses, and (3) the mechanisms of dislocation. We retrospectively reviewed 319 patients who underwent 384 TKAs from May 2007 to July 2008. These patients had been assigned alternately to receive a Scorpio posterior stabilized knee prosthesis (Group I, 158 patients, 187 knees) or a Columbus posterior stabilized knee prosthesis (Group II, 161 patients, 197 knees). We followed the patients with clinical and radiographic evaluations for a minimum of 24 months (mean, 26 months; range, 24-38 months). Ten retrieved prostheses were examined visually. Ten dislocations (5.1%; 10 of 197 knees) and seven aseptic loosenings of femoral components (3.6%; seven of 197 knees) occurred in Group II at a mean of 10.9 months postoperatively. However, no dislocation or loosening occurred in patients in Group I. Most dislocations were associated with varus flexion or flexion rotation movements during normal daily activities. The cam jump distance at 90º flexion for the Columbus prosthesis was lower than for the Scorpio prosthesis. We observed a high rate of early failure during short-term followup after implantation of a Columbus posterior stabilized prosthesis. It appears that early failures of the Columbus design were related to a different cam-post design attributable to a low jump distance during knee flexion. We no longer recommend using this device. Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

The Long-Term Results of the Original Exeter Polished Cemented Femoral Component: A Follow-up Report

We present a long-term follow-up report of the results of the original Exeter polished cemented stems inserted between November 1970 and the end of 1975 at our institution by surgeons of widely differing experience using crude cementing techniques. The results of this series were reported in 1988 (Fowler et al. Orthopaedic Clinics of North America. 1988;19:477) and again in 1993 (Timperley et al. Journal of Bone and Joint Surgery. 1993;75-B:33). There have been no failures from aseptic femoral component loosening since the 1993 report. From the original series of 433 hips, there were, at the end of 2003, 26 living patients with 33 hips. Of the latter, there were 25 hips in 20 patients with their original femoral components still in situ. Twenty-eight (6.46%) hips from the original series have been lost to follow-up, although none since 1992. With the end point reoperation for aseptic stem loosening, the survivorship is 93.5% (95% confidence interval, 90.0%-97.0%). The reoperation rate for aseptic femoral component loosening is 3.23% into the 33rd year of follow-up.

Predicting revision risk for aseptic loosening of femoral components in total hip arthroplasty in individual patients—A finite element study

Advances in surgical procedure, prosthesis design, and biomaterials performance have considerably increased the longevity of total joint replacements. Preoperative planning is another step in joint replacement that may have the potential to improve clinical outcome for the individual patient, but has remained relatively consistent for a long time. One means of advancing this aspect of joint replacement surgery may be to include predictive computer simulation into the planning process. In this article, the potential of patient-specific finite element analysis in preoperative assessment is investigated. Seventeen patient-specific finite element models of cemented Charnley reconstructions were created, of which six were early (<10 years) revisions. Creep was simulated using a Maxwell model, and fatigue damage was simulated using an anisotropic continuum damage formulation. Account was taken of the relationship between annual loading cycles and age, and stair-climbing loads were included using a walking to stair-climbing cycle ratio of 9:1. Simulations for the equivalent of 10 years of loading were performed. Accumulated damage, inducible displacement, and migration were computed. Five of the six early revisions had the highest migration indicating that migration could have been used to identify early failures of these prostheses. Resultant migration showed the most significant difference between the early revised and unrevised groups (p = 0.0024). Furthermore, this trend was apparent from 1 year postimplantation (p = 0.0052). This ability to differentiate early revisions shows that computational simulation of aseptic loosening in cemented prostheses could prove clinically useful in helping surgeons optimize the preoperative plan for individual patients.

Peri-prosthetic bone density after implantation of a custom-made femoral component

Peri-prosthetic bone loss caused by stress shielding may be associated with aseptic loosening of femoral components. In order to increase primary stability and to reduce stress shielding, a three-dimensional, cementless individual femoral (Evolution K) component was manufactured using pre-operative CT scans. Using dual energy x-ray absorptiometry, peri-prosthetic bone density was measured in 43 patients, three months, six months, 3.6 and 4.6 years after surgery. At final follow-up there was a significant reduction in mean bone density in the proximal Gruen zones of -30.3% (zone 7) and -22.8% (zone 1). The density in the other zones declined by a mean of between -4% and -16%. We conclude that the manufacture of a three-dimensional, custom-made femoral component could not prevent a reduction in peri-prosthetic bone density.

Diagnostic accuracy and interobserver variability of plain radiography, subtraction arthrography, nuclear arthrography, and bone scintigraphy in the assessment of aseptic femoral component loosening

Plain radiography, subtraction arthrography, nuclear arthrography, and bone scintigraphy are imaging techniques commonly used to identify aseptic femoral component loosening. Controversy exists about the relative utility of these techniques. We evaluated the diagnostic accuracy and interobserver reliability of the four techniques in 78 consecutive patients (mean age 70 years, range 29-88 years) referred for evaluation of their femoral hip prostheses. The standard evaluation protocol consisted of plain radiography followed by subtraction arthrography, nuclear arthrography, and bone scintigraphy. Surgery or the subsequent clinical course of the patient was used as gold standard. Overall, plain radiography had a sensitivity and specificity of 81 and 74%, respectively. Subtraction arthrography had a sensitivity of 47% and a specificity of 78%. Nuclear arthrography had a sensitivity of 69% and a specificity of 76%, and bone scintigraphy had a sensitivity of 88% with a specificity of 50%. We found considerable interobserver variability in all four techniques. Multivariate regression analysis revealed that bone scintigraphy and nuclear arthrography together made a significant contribution to the diagnosis when used in combination with plain radiography and are, when plain radiography is inconclusive, useful additional diagnostic techniques for the detection of femoral component loosening.