FEMORAL STEM FIXATION

The utility of cemented femoral stems in modern THA: a 10-year comparative analysis of the Charnley and Exeter stems

BACKGROUND

Total hip replacement (THR) is one of the most common surgical procedures performed worldwide. The controversy surrounding the relative merits of a cemented composite beam or cemented taper-slip stem in total hip replacement continues. Our aims primarily were to assess the 10-year outcomes of cemented stems using Charnley and Exeter prostheses with regional registry data and secondarily to assess the main predictors of revision.

METHODS

We prospectively collected registry data for procedures performed between January 2005 and June 2008. Only cemented Charnley and Exeter stems were included. Patients were prospectively reviewed at 6 months, 2, 5 and 10 years. The primary outcome measure was a 10-year all-cause revision. Secondary outcomes included 're-revision', 'mortality' and functional 'Western Ontario and McMaster Universities Osteoarthritis Index' (WOMAC) scores.

RESULTS

We recorded a total of 1351 cases in the cohort, 395 Exeter and 956 Charnley stems. The overall all-cause revision rate at 10 years was 1.6%. The revision rate for Charnley stem was 1.4% and 2.3% revision rate for all Exeter stems with no significant difference noted between the two cohorts (p = 0.24). The overall time to revision was 38.3 months. WOMAC scores at 10 years were found to be insignificantly higher for Charnley stems (mean 23.8, σ = 20.11) compared to Exeter stems (mean 19.78, σ = 20.72) (p = 0.1).

CONCLUSION

There is no significant difference between cemented Charnley and Exeter stems; they both perform well above the international average. The decline in the use of cemented THA is not fully supported by this regional registry data.

Outcomes of fixation of Vancouver B periprosthetic fractures around cemented versus uncemented stems

BACKGROUND

The incidence of periprosthetic femur fracture (PPFF) in the setting of total hip arthroplasty (THA) is steadily increasing. We seek to address whether there is a difference in outcomes between Vancouver B fracture types managed with ORIF when the original stem was a press-fit stem versus a cemented stem.

METHODS

In this retrospective cohort study at a level 1 trauma center, we identified 136 patients over 65 years-of-age with Vancouver B-type fractures sustained between 2005 and 2019. Patients were treated by ORIF and had either cemented or press-fit stems prior to their injury. Outcomes were subsidence of the femoral implant, time to full weight bearing, rate of the hip implant revision, estimated blood loss (EBL), postoperative complications, and the one-year mortality rate.

RESULTS

A total of 103 (75.7%) press-fit and 33 (24.3%) cemented patients were reviewed. Patient baseline characteristics, Vancouver fracture sub-types, and implant characteristics were not found to be significantly different between groups. The difference in subsidence rates, postoperative complications, and time to weight bearing were not significantly different between groups. EBL and one-year mortality rate were significantly higher in the cemented group.

CONCLUSIONS

In geriatric patients with Vancouver B type periprosthetic fractures managed with ORIF, patients with an originally press fit stem may have lower mortality, lower estimated blood loss, and similar subsidence and hospital length of stays when compared to those with a cemented stem.

Correlation between shape-closed femoral stem design and bone cement implantation syndrome in osteoporotic elderly femoral neck fracture undergoing cemented hip arthroplasty: A retrospective case-control study in 128 patients

BACKGROUND

Bone cement implantation syndrome (BCIS) is a serious and potentially fatal complication especially in patients with osteoporotic femoral neck fracture (OFNF) undergoing cemented hip arthroplasty (CHA). Recent studies showed that the shape-closed femoral stem profile could lead to a significant increase of the intramedullary pressure during cementation and prosthesis insertion. This study aimed to (1) correlate the use of shaped-closed femoral stem and other perioperative risk factors with severe grade of BCIS grade 2 or 3: BCIS gr2/3, and (2) identify the prevalence of BCIS in the elderly patients with OFNF and treated with CHA.

HYPOTHESIS

Large wedge-shaped (or "shape-closed") femoral stem design would significantly associate with BCIS gr2/3 in the elderly patients who sustained OFNF and underwent CHA.

PATIENTS AND METHODS

A total of 128 OFNF patients, who aged over 75years and underwent CHA were retrospectively reviewed and then allocated into 2 groups: SC Group (use shape-closed femoral stem, n=40) and FC Group (use force-closed femoral stem, n=88). BCIS was grading in all patients according to Donaldson classification. Perioperative data between the patients with BCIS-gr2/3 and those with BCIS grade 0 or 1 (BCIS-gr0/1) were compared. Multiple logistic regression analysis was used to identify predictive factors for BCIS-gr2/3.

RESULTS

The prevalence of overall BCIS and BCIS-gr2/3 was 32.8% (n=42) and 6.2% (n=8), respectively. The total in-hospital and 1-year mortality rates were 2.3% and 4.7%, respectively. The major perioperative complication in patients with BCIS-gr2/3 was significantly higher compared to those in patients with BCIS-gr0/1 (62.5% vs. 10.0%, p=0.001). Multivariate analysis showed that age>90years (OR=9.4, 95% CI: 1.4-62.9, p=0.02), preinjury Parker mobility score<4 (OR=48.8; 95% CI: 2.7-897.2, p=0.008) and shape-closed femoral stem used (OR=19.1; 95% CI: 1.8-204.5, p=0.01) were the significant independent predictors for BCIS-gr2/3 in these patients.

CONCLUSION

BCIS in OFNF patients undergoing CHA is common and associates with a high major perioperative complication rate. Our initial hypothesis is validated as the patients at risk for BCIS-gr2/3 are those whose CHA procedures use a shape-closed femoral stem design and with extreme age, and having poor preinjury ambulatory status. Therefore, we recommended using cementless stem as the first option in OFNF. However, if CHA is needed, strict guideline for cement insertion should be followed with force-closed stem application to avoid the risk of BCIS-gr2/3.

LEVEL OF EVIDENCE

III; retrospective case-control study.

Minimum 10-Year Follow-Up of Total Hip Arthroplasty With a Collarless Triple-Tapered Polished Cemented Stem With Line-to-Line Implantation Using a Direct Anterior Approach

BACKGROUND

The Trilliance stem (B. Braun-Aesculap, Tuttlingen, Germany), a novel collarless triple-tapered polished stem, was introduced in 2009. The aim of this study is to evaluate the long-term clinical and radiological results of the Trilliance stem with line-to-line implantation in primary total hip arthroplasty using a direct anterior approach.

METHODS

A consecutive retrospective series of 130 patients (151 hips) who underwent total hip arthroplasty between February 2009 and August 2011 were evaluated for a minimum of 10 years. Of these, 87.4% had a diagnosis of secondary osteoarthritis based on developmental hip dysplasia. Clinical and radiological results, complications were evaluated and survival analysis was performed.

RESULTS

The mean follow-up was 10.7 years (range, 10.0-12.1). Thirteen hips (13 patients, 6.8%) were lost to follow-up. Adequate cementation (Barrack grade A) was achieved in 136 hips (93.8%) 1 week post-operatively. Nearly all (144 hips, 99.3%) had been inserted within the range of 3°. No significant differences were identified between high- (≥30 procedures/year) and low- (<30 procedures/year) volume surgeons. The Kaplan-Meier survival analysis with revision of the femoral component for aseptic loosening, revision of the femoral component for any reason and revision of either component for any reason as the end points, cumulative survivorship was 100.0%, 97.6% (95% confidence interval (CI) 95.4-100.0) and 96.5% (95% CI 93.8-99.3) at 10 years, respectively.

CONCLUSION

The Trilliance stem with line-to-line implantation using a direct anterior approach has an excellent clinical and radiological outcome at a minimum of 10 years' follow-up.

LEVEL OF EVIDENCE

Level IV, Retrospective cohort study.

Femoral Stem Cementation in Primary Total Hip Arthroplasty

➢

Femoral stem cementation has undergone considerable investigation since bone cement was first used in arthroplasty, leading to the evolution of modern femoral stem cementation techniques.

➢

Although there is a worldwide trend toward the use of cementless components, cemented femoral stems have shown superiority in some studies and have clear indications in specific populations.

➢

There is a large evidence base regarding cement properties, preparation, and application techniques that underlie current beliefs and practice, but considerable controversy still exists.

➢

Although the cementing process adds technical complexity to total hip arthroplasty, growing evidence supports its use in certain cohorts. As such, it is critical that orthopaedic surgeons and investigators have a thorough understanding of the fundamentals and evidence underlying modern cementation techniques.

Comparison of the functional outcomes after treatment of periprosthetic hip fractures with femoral stem loosening: Locking plate fixation with or without femoral stem revision

INTRODUCTION

Periprosthetic fractures have become one of the main reasons for revision of total hip arthroplasty, with the treatment strategy guided by the Vancouver and SOFCOT classification systems. The main objective of this work was to compare the functional outcomes and mortality rate in patients who suffered a periprosthetic hip fracture with femoral stem loosening and who were treated either by internal fixation with locking plate only, or in combination with revision of the existing femoral stem with a cemented stem. The secondary objective was to compare the blood loss, procedure duration, length of hospital stay, living arrangements, time to weight bearing and major complications between these two treatment strategies. The starting hypothesis was that there is no difference in the functional outcomes between these two groups.

MATERIALS AND METHODS

This was a single center, retrospective study of patients treated between 2013 and 2019. Thirty-six patients (54%) underwent femoral stem revision (FSR group) and 31 patients (46%) were treated by locking plate fixation only (ORIF group). In this population, 19 of the patients had been residing at a nursing home before the surgical treatment: 12 (33%) in the FSR group and 7 (23%) in the ORIF group (p=0.33). The mean preoperative Parker score was 7.03 (± 1.48) in the FSR group versus 5.19 (± 1.92) in the ORIF group. The functional outcomes at the final review were evaluated using the Parker score, HHS (Harris Hip score), WOMAC (Western Ontario and McMaster Arthritis Index) and Oxford score. Fracture healing was determined on radiographs centered over the hip joint with the entire femur visible on AP and lateral views. All patients were reviewed at a minimum of 1 year for clinical and radiological assessments.

RESULTS

At a mean follow-up of 28 months [12-85], the Oxford score was 40.4 (± 10.6) in the FSR group versus 37.1 (± 13.5) in the ORIF group (p=0.34), WOMAC of 45.5 (± 26.9) versus 50.5 (± 32.4) (p=0.56), and HHS of 62.7 (± 25.5) versus 60.3 (± 28.6) (p=0.79). The Parker score at the final assessment was 5.14 (± 1.96) in the FSR group versus 4.64 (± 2.17) in the ORIF group (p=0.33). In the FSR group, 10 patients were at a nursing home (34%), 6 of whom were not there initially, versus 6 in the ORIF group (43%), 5 of whom were not there initially (p=0.59). The mean operating time was 152±41.4 minutes (minimum: 85; maximum: 254) in the FSR group versus 89.2 (± 44.1) minutes (minimum: 39; maximum: 280) in the ORIF group (p<0.001). Resumption of full weight bearing occurred at 6 weeks in 21 patients (58%) in the FSR group versus 14 patients (47%) in the ORIF group (p=0.023). There were 5 major complications (14%) in the FSR group versus 7 (23%) in the ORIF group (p=0.35). Among the reviewed patients, the union rate was 86% on the latest radiographs in the FSR group versus 78% in the ORIF group.

DISCUSSION

There was no statistically significant difference between groups in the various functional scores, confirming our study hypothesis. Internal fixation with a locking plate appears to be an acceptable solution for treating periprosthetic hip fractures in which the femoral stem has loosened.

LEVEL OF EVIDENCE

III, comparative retrospective study.

The influence of calcar collar and surface finish in the cemented femoral component on the incidence of postoperative periprosthetic femoral fracture at a minimum of five years after primary total hip arthroplasty

INTRODUCTION

Cemented femoral component design including its mechanical behavior in total hip arthroplasty (THA) has influenced the occurrence of postoperative periprosthetic femoral fracture (PPFF). The main aim of this study was to investigate the influence of the calcar collar and surface finish in the cemented femoral component on the risk of PPFF.

MATERIALS AND METHODS

This retrospective review was undertaken of 1082 primary THAs in 912 patients using cemented femoral components followed for a minimum of five years (mean, 9.4 years; range, 5-24 years). The incidence of PPFF, patients' demographics and surgical details were evaluated. Kaplan-Meier survivorship analysis was performed for four different outcomes: any PPFF, revision of the femoral component for PPFF, aseptic loosening, and for any reason.

RESULTS

The overall incidence of PPFFs was 1.0% (n = 11): 1.4% (n = 10) in the collarless polished (CLP) group, none in the collared polished (CP) group and 0.6% (n = 1) in the collared non-polished (CNP) group (p > 0.05). Kaplan-Meier survival analysis for the femoral component at 12 years with PPFF as the end point was 97.4% (95% confidence interval [CI], 94.9 to 99.8) in the collarless group and 99.7% (95% CI, 99.1 to 100) in the collared group (p = 0.048). With revision of the femoral component for aseptic loosening as the end point, survivorship was 100.0% in the CLP and CP groups, and 98.1% (95% CI, 95.9 to 100) in the CNP group (CLP vs CP, p > 0.999; CLP vs CNP, p = 0.001; CP vs CNP, p = 0.112).

CONCLUSION

This study demonstrated that the calcar collar in the cemented femoral component could play an important role to reduce the incidence of PPFF. The surface finish in the cemented femoral components influenced the incidence of femoral component revision for aseptic loosening over 5-12 years. Surgeons should consider not only the geometry and the mechanical function of the femoral components based on different design philosophies, but also potential complications associated with different designs that may require revision arthroplasty.

Survivorship of the C-Stem total hip replacement using the "French Paradox" technique

BACKGROUND

This study evaluates the survivorship of the C-Stem total hip replacement, using the "French Paradox" method, at medium-term follow-up.

METHODS

321 cemented total hip replacements in 307 patients were performed, using the canal-filling technique for the femoral stem. Survival analysis was performed for all-cause revision. The secondary outcome was aseptic loosening of the stem.

RESULTS

Revision rate for all reasons was 2%. Overall ten-year survival was 95%. There were no revisions for femoral stem aseptic loosening.

CONCLUSION

This is a unique study demonstrating successful outcomes of total hip replacement using the "French Paradox" technique with a triple-tapered stem.

Selected Vancouver B2 periprosthetic femoral fractures around cemented polished femoral components can be safely treated with osteosynthesis

AIMS

We aimed to compare the implant survival, complications, readmissions, and mortality of Vancouver B2 periprosthetic femoral fractures (PFFs) treated with internal fixation with that of B1 PFFs treated with internal fixation and B2 fractures treated with revision arthroplasty.

METHODS

We retrospectively reviewed the data of 112 PFFs, of which 47 (42%) B1 and 27 (24%) B2 PFFs were treated with internal fixation, whereas 38 (34%) B2 fractures underwent revision arthroplasty. Decision to perform internal fixation for B2 PFFs was based on specific radiological (polished femoral components, intact bone-cement interface) and clinical criteria (low-demand patient). Median follow-up was 36.4 months (24 to 60). Implant survival and mortality over time were estimated with the Kaplan-Meier method. Adverse events (measured with a modified Dindo-Clavien classification) and 90-day readmissions were additionally compared between groups.

RESULTS

In all, nine (8.01%) surgical failures were detected. All failures occurred within the first 24 months following surgery. The 24-month implant survival was 95.4% (95% confidence interval (CI) 89.13 to 100) for B1 fractures treated with internal fixation, 90% (95% CI 76.86 to 100) for B2 PFFs treated with osteosynthesis-only, and 85.8% (95% CI 74.24 to 97.36) for B2 fractures treated with revision THA, without significant differences between groups (p = 0.296). Readmissions and major adverse events including mortality were overall high, but similar between groups (p > 0.05). The two-year patient survival rate was 87.1% (95% CI 77.49 to 95.76), 66.7% (95% CI 48.86 to 84.53), and 84.2% (95% CI 72.63 to 95.76), for the B1 group, B2 osteosynthesis group, and B2 revision group, respectively (p = 0.102).

CONCLUSION

Implant survival in Vancouver B2 PFFs treated with internal fixation was similar to that of B1 fractures treated with the same method and to B2 PFFs treated with revision arthroplasty. Low-demand, elderly patients with B2 fractures around well-cemented polished femoral components with an intact bone-cement interface can be safely treated with internal fixation. Cite this article: Bone Joint J 2021;103-B(7):1222-1230.

Relationship between the Surface Roughness of Material and Bone Cement: An Increased "Polished" Stem May Result in the Excessive Taper-Slip

Although some reports suggest that taper-slip cemented stems may be associated with a higher periprosthetic femoral fractures rate than composite-beam cemented stems, few studies have focused on the biomaterial effect of the polished material on the stem–cement interface. The purpose of this study was to investigate the relationship between surface roughness of materials and bone cement. Four types of metal discs—cobalt-chromium-molybdenum alloy (CoCr), stainless steel alloy 316 (SUS), and two titanium alloys (Ti-6Al-4V and Ti-15Mo-5Zr-3Al)—were prepared. Five discs of each material were produced with varying degrees of surface roughness. In order to evaluate surface wettability, the contact angle was measured using the sessile drop method. A pin was made using two bone cements and the frictional coefficient was assessed with a pin-on-disc test. The contact angle of each metal increased with decreasing surface roughness and the surface wettability of metal decreased with higher degrees of polishing. With a surface roughness of Ra = 0.06 μm and moderate viscosity bone cement, the frictional coefficient was significantly lower in CoCr than in SUS (p = 0.0073). In CoCr, the low adhesion effect with low frictional coefficient may result in excessive taper-slip, especially with the use of moderate viscosity bone cement.

Risk factors influencing fracture characteristics in postoperative periprosthetic femoral fractures around cemented stems in total hip arthroplasty : a multicentre observational cohort study on 584 fractures

Aims

This study evaluates risk factors influencing fracture characteristics for postoperative periprosthetic femoral fractures (PFFs) around cemented stems in total hip arthroplasty.

Methods

Data were collected for PFF patients admitted to eight UK centres between 25 May 2006 and 1 March 2020. Radiographs were assessed for Unified Classification System (UCS) grade and AO/OTA type. Statistical comparisons investigated relationships by age, gender, and stem fixation philosophy (polished taper-slip (PTS) vs composite beam (CB)). The effect of multiple variables was estimated using multinomial logistic regression to estimate odds ratios (ORs) with 95% confidence intervals (CIs). Surgical treatment (revision vs fixation) was compared by UCS grade and AO/OTA type.

Results

A total of 584 cases were included. Median age was 79.1 years (interquartile range 72.0 to 86.0), 312 (53.6%) patients were female, and 495 (85.1%) stems were PTS. The commonest UCS grade was type B1 (278, 47.6%). The most common AO/OTA type was spiral (352, 60.3%). Metaphyseal split fractures occurred only with PTS stems with an incidence of 10.1%. Male sex was associated with a five-fold reduction in odds of a type C fracture (OR 0.22 (95% CI 0.12 to 0.41); p < 0.001) compared to a type B fracture. CB stems were associated with significantly increased odds of transverse fracture (OR 9.51 (95% CI 3.72 to 24.34); p < 0.001) and wedge fracture (OR 3.72 (95% CI 1.16 to 11.95); p = 0.027) compared to PTS stems. Both UCS grade and AO/OTA type differed significantly (p < 0.001 and p = 0.001, respectively) between the revision and fixation groups but a similar proportion of B1 fractures underwent revision compared to fixation (45.3% vs 50.6%).

Conclusion

The commonest fracture types are B1 and spiral fractures. PTS stems are exclusively associated with metaphyseal split fractures, but their incidence is low. Males have lower odds of UCS grade C fractures compared to females. CB stems have higher odds of bending type fractures (transverse and wedge) compared to PTS stems. There is considerable variation in practice when treating B1 fractures around cemented stems.

Cite this article: Bone Jt Open 2021;2(7):466–475.

The Effect of a Distal Centralizer on Cemented Femoral Stems in Arthroplasty Shown on Radiographs and SPECT/CT: A Case Report

CASE

A 70-year-old female patient underwent total hip arthroplasty (HA) using a stem cemented line-to-line without centralizer. Postoperatively, she complained of load-dependent thigh pain. Conventional radiographs identified cortical overload because of a distal cement mantle discontinuity at the level of the stem's tip, confirmed by single-photon emission computed tomography/computed tomography scan (SPECT/CT). After cement-in-cement revision using a stem with centralizer, pain ceased rapidly. The cortical overload disappeared, as confirmed on a following SPECT/CT performed for low back pain.

CONCLUSION

In HA, the stem's tip may cause overload on the bone's cortex if the cement mantle is incomplete. Implanting a stem with centralizer avoids or cures this.

Temporal subsidence patterns of cemented polished taper-slip stems: a systematic review

The literature was reviewed to establish the levels of stem subsidence for both double and triple-tapered implants in order to determine whether there were any differences in subsidence levels with regard to the methods of measurement, the magnitude and rate of subsidence and clinical outcomes.

All studies reporting subsidence of polished taper-slip stems were identified. Patient demographics, implant design, radiological findings, details of surgical technique, methods of measurement and levels of subsidence were collected to investigate which factors were related to increased subsidence.

Following application of inclusion and exclusion criteria, 28 papers of relevance were identified. The studies initially recruited 3090 hips with 2099 being available for radiological analysis at final follow-up. Patient age averaged 68 years (42–70), 60.4% were female and the average body mass index (BMI) was 27.4 kg/m² (24.1–29.2).

Mean subsidence at one, two, five and 10 years was 0.97 mm, 1.07 mm, 1.47 mm and 1.61 mm respectively. Although double-tapered stems subsided more than triple-tapered stems at all time points this was not statistically significant (p > 0.05), nor was the method of measurement used (p > 0.05).

We report the levels of subsidence at which clinical outcomes and survivorship remain excellent, but based on the literature it was not possible to determine a threshold of subsidence beyond which failure was more likely.

There were relatively few studies of triple-tapered stems, but given that there were no statistically significant differences, the levels presented in this review can be applied to both double and triple-tapered designs.

Cite this article: EFORT Open Rev 2021;6:331-342. DOI: 10.1302/2058-5241.6.200086

Femoral Stem Cementation in Hip Arthroplasty: The Know-How of a "Lost" Art

PURPOSE OF REVIEW

To describe the (1) indications, (2) preoperative precautions, and (3) stepwise technical details of modern femoral stem cemented fixation.

RECENT FINDINGS

Femoral stem cementation provides excellent implant longevity with a low periprosthetic fracture rate among patients with compromised bone quality or aberrant anatomy. Unfamiliarity with the details of modern cementation techniques among trainees who may lack frequent exposure to cementing femoral stems may preclude them from offering this viable option to suitable patients in later stages of their careers. As such, maximizing benefit from cemented femoral stem fixation among suitable candidates is contingent upon the meticulous use of modern cementation techniques. In addition to proper patient selection, modern cementation techniques emphasize the use of (1) pulsatile lavage of the femoral canal, (2) utilization of epinephrine-soaked swabs, (3) vacuum cement mixing, (4) retrograde cement introduction, (5) cement pressurization, and (6) the use of stem centralizers. Furthermore, identifying and optimizing the preoperative status of at-risk patients with pre-existing cardiopulmonary compromise, in addition to intraoperative vigilance, are essential for mitigating the risk of developing bone cement implantation syndrome. Further research is required to assess the utility of cemented femoral stem fixation among younger patients.

Fracture fixation versus revision arthroplasty in Vancouver type B2 and B3 periprosthetic femoral fractures: a systematic review

INTRODUCTION

Hip arthroplasty (HA) is commonly performed to treat various hip pathologies. Its volume is expected to rise further due to the increasing age of the population. Complication rates are low; however, periprosthetic femoral fractures (PFF) are a rare, albeit serious, complication with substantial economic impact. While current guidelines propose revision with long-stemmed prostheses for all Vancouver B2 and B3 PFF, some recent research papers suggest that open reduction with internal fixation (ORIF) could lead to an equivalent outcome. Our aim was to summarize the evidence, elucidating under which circumstances ORIF leads to a favorable outcome after B2 and B3 PFF compared with revision surgery.

MATERIALS AND METHODS

A systematic literature search was performed to identify studies on patients treated with ORIF and with stem revision after B2 and/or B3 fractures. Extracted information included initial pathology, stem fixation mechanism, bone quality and stem stability at the time of PFF, clinical outcomes, and mortality. Results of individual studies were summarized in a table in lieu of a quantitative data synthesis due to a lack of standardized information.

RESULTS

We identified 14 original research articles including both patients treated with ORIF and with stem revision after B2 and/or B3 PFF. Five studies included statistical comparisons, all were in favor of ORIF or indeterminate. The common lack of rigorous statistical analyses and significant methodological weaknesses made identification of outcome predictors impossible.

CONCLUSION

The choice of treatment modality for PFF depends on fracture, implant, and bone characteristics. Recent data show that successful outcome can be achieved without revising loose stems. ORIF may be a viable option if bone stock is adequate around uncemented or tapered polished stems with an intact cement mantle and the fracture geometry allows stable anatomic reconstruction. Conceptional considerations support this idea, but more data are needed to identify outcome predictors.

Periprosthetic fractures of the proximal femur: beyond the Vancouver classification

The majority of periprosthetic femoral fractures are treated surgically.

Surgical treatment may be revision only, revision in combination with open reduction and internal fixation (ORIF), or ORIF only.

The treatment decision is dependent on whether the stem is loose or not, but loose stems are not always identified, resulting in unsatisfactory treatments.

This article presents an algorithmic approach to identifying loose stems around proximal femoral periprosthetic fractures, taking patient history, stem design, and plain radiographs into consideration. This approach may help identifying loose stems and increase the probability of effective treatments.

Cite this article: EFORT Open Rev 2020;5:449-456. DOI: 10.1302/2058-5241.5.190086

Undersizing the Exeter stem in hip hemiarthroplasty increases the risk of periprosthetic fracture

INTRODUCTION

Whether under- or oversizing of the femoral component of cemented hip hemiarthroplasties impacts the risk of periprosthetic fractures (PPF) has only been examined experimentally. This study was carried out to add more knowledge about the risks of PPF in cemented polished tapered hemiarthroplasties.

METHODS

20 patients with PPF following hip hemiarthroplasty with cemented Exeter V40 stems were compared to 50 controls who never suffered PPF having received the same type of Exeter hemiprosthesis for the same indication. The difference between stem size and post-hoc radiographic ideal templated size was investigated as a predictor of PPF.

RESULTS

Cases had a median size difference to post-hoc templating of -2, while controls had a median size difference of -1 (p = 0.09). An ROC curve constructed to find an optimal cutoff point in size difference between cases and controls arrived at an area under curve of 63%, with -1.5 as the cutoff. Patients with size differences exceeding -1.5 had a statistically significant increased PPF risk (odds ratio = 3.8, 95% confidence interval, 1.1-13.3, p < 0.05). This group covered 55% of all cases.

CONCLUSION

An implanted femoral component that is 2 or more sizes smaller than the template that is shown to be appropriate will increase the risk of PPF in Exeter hip hemiarthroplasties.

Postoperative migration of the anatomical and functional anteversion angle following total hip arthroplasty with a well-fixed cemented femoral component with line-to-line implantation

INTRODUCTION

Little is known about the association between well-fixed polished tapered cemented stems (PTCS) implanted by the line-to-line technique and changes of stem migration, or the change of functional anteversion of the femur after total hip arthroplasty (THA).

MATERIALS AND METHODS

This retrospective study included 422 two-stage bilateral primary THAs performed using PTCS implanted by the line-to-line technique. CT scans were made on both the target side (first postoperative CT) and on the contralateral side (second postoperative CT) 1 week postoperatively. The mean follow-up was 7.8 months. CT data for each scan were transferred to 3D template software (Zed hip, Lexi, Japan). The postoperative changes of anatomical stem anteversion (ASA), functional femoral anteversion (FFA), and stem subsidence were evaluated.

RESULTS

A total of 20 THAs with CT scans were available on 3D template software. The ASA and the FFA had migrated - 0.68° ± 0.62° and - 5.5° ± 9.7°, respectively, over the follow-up period. A significant positive correlation was observed between the change of subsidence and ASA (r² = 0.34, p = 0.007), between the FFA on the second postoperative CT and ASA on the first postoperative CT (r² = 0.26, p = 0.02) and between the FFA on the second postoperative CT and FFA on the first postoperative CT (r² = 0.52, p = 0.0003).

CONCLUSION

This study indicates that the change in axial rotation of a PTCS implanted by the line-to-line technique was less than that reported by other studies and the preoperative external rotation contracture was substantially improved after THA.

Current concepts and outcomes in cemented femoral stem design and cementation techniques: the argument for a new classification system

Cemented implant fixation design principles have evolved since the 1950s, and various femoral stem designs are currently in use to provide a stable construct between the implant-cement and cement-bone interfaces.Cemented stems have classically been classified into two broad categories: taper slip or force closed, and composite beams or shaped closed designs. While these simplifications are acceptable general categories, there are other important surgical details that need to be taken into consideration such as different broaching techniques, cementing techniques and mantle thickness.With the evolution of cemented implants, the introduction of newer implants which have hybrid properties, and the use of different broaching techniques, the classification of a very heterogenous group of implants into simple binary categories becomes increasingly difficult. A more comprehensive classification system would aid in comparison of results and better understanding of the implants' biomechanics.We review these differing stem designs, their respective cementing techniques and geometries. We then propose a simple four-part classification system and summarize the long-term outcomes and international registry data for each respective type of cemented prosthesis. Cite this article: EFORT Open Rev 2020;5:241-252. DOI: 10.1302/2058-5241.5.190034.

The effects of patient characteristics and stem alignment on distal femoral cortical hypertrophy after cemented polished tapered stem implantation

BACKGROUND

The objective of this study was to evaluate the results of over 10 years of total hip arthroplasty (THA) practice with Exeter^TM stems and the clinical relevance of distal femoral cortical hypertrophy (DFCH).

METHODS

We retrospectively reviewed 127 hips (120 patients) that had undergone THA with Exeter^TM stems between 2004 and 2007. Kaplan-Meier survival analyses for the stem of all 127 hips were performed using different endpoints. Of 127 hips, 100 (94 patients) had complete 10-year follow-up data, including the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) as the patient-reported outcomes, and the clinical relevance of DFCH was analyzed using multivariable logistic regression analysis.

RESULTS

The survival of the stem with the endpoint of re-operation for loosening, > 5-mm subsidence, and re-operation for any reason were 100%, 99.1% (95% CI 97.5-100%), and 98.3% (95% CI 96.0-100%), respectively. Of 100 hips followed completely for 10 years, DFCH occurred in 20 hips (20%). The satisfaction and pain visual analog scale of JHEQ revealed high satisfaction and less pain in patients with DFCH. By multivariate logistic regression analysis, body weight > 55 kg (odds ratio: 2.88, p = 0.035) and varus stem alignment (odds ratio: 6.56, p = 0.003) were found to be predictors for DFCH.

CONCLUSIONS

The incidence of DFCH with the Exeter^TM stem was 20%. A body weight > 55 kg and varus stem alignment are predictors for future DFCH. DFCH with the Exeter^TM stem indicates a good outcome with less hip pain.

Prospective, comparative study of cemented, smooth-surfaced titanium stems and polish-surfaced, stainless steel stems at a minimum follow-up of 10 years

BACKGROUND

Excellent results have been reported with cemented total hip arthroplasty (THA) using both smooth-surfaced and polished-surfaced stems. However, the superiority of polished-surfaced over smooth-surfaced in cemented THA, or vice versa, is still debated.

MATERIALS AND METHODS

Forty-six smooth-surfaced, triple-tapered, titanium-alloy stem (Group C) and 46 Exeter stems (Group T) have been fixed consecutively at different periods at our institute and prospectively evaluated clinically and radiologically. The area and location demonstrating cortical hypertrophy (CH) was measured in the serial radiograph and compared.

RESULTS

The mean postoperative follow-up period was 12.4 years for group C and 10.8 years for group T. No significant difference of clinical results was found between both groups. CH was observed in 8 hips (18.6%) of group C and in 7 hips (17.1%) of group T (NS). Among the hips in which distribution of CH was observed at the medial side, a significantly low proportion belonged to group C (adjusted standardized residual = - 2.3) and a significantly high proportion belonged to group T (adjusted standardized residual = 2.3). The largest area of CH found in each group was 166.1 mm² in group C and 227.6 mm² in group T (NS). The peak location of CH was 100.4% in group C and 84.3% in group T (p = 0.02).

CONCLUSION

Medium-term results of both stems were excellent. CH was observed medially and proximally in group T and laterally and distally in group C.

Long-term outcome of cemented total hip arthroplasty with the Charnley-type femoral stem made of titanium alloy

BACKGROUND

Total hip arthroplasty is a successful treatment for hip diseases including osteoarthritis, osteonecrosis of the femoral head, and rheumatoid arthritis. Various designs of cemented femoral stems made of stainless steel and titanium alloy have been used. Among them, Charnley-type femoral stems made of stainless steel have often been reported to have good long-term outcome. However, the long-term outcome of the Charnley-type femoral stem made of Ti alloy is yet to be reported. We conducted a retrospective study to assess the long-term outcome of cemented primary total hip arthroplasty with the Charnley-type femoral stem made of Ti alloy.

METHODS

Between October 1988 and February 1997, 341 cemented primary total hip arthroplasties with the Charnley-type femoral stem made of Ti alloy were consecutively performed in our hospital. Among these, 164 patients (211 hips) who underwent this procedure were followed up for more than 12 years, and the surgical hips were analysed clinically and radiologically. The mean follow-up period was 20.6 years. Kaplan-Meier survival analyses were performed to assess femoral component survival. Factors affecting stem revision for aseptic loosening were also investigated using log-rank tests.

RESULTS

In the functional assessment, the preoperative Japanese Orthopaedic Association score significantly improved from 47.2 points preoperatively to 79.0 points at the final follow-up. Eventually, 33 femoral stems were revised, of which 12 were revised for aseptic loosening. In the Kaplan-Meier survival analysis, the 20-year survival rates with stem revision for aseptic loosening and radiological stem loosening at the end points were 95.9% and 97.1%, respectively. Original diagnosis (non-osteoarthritis) was the only significant factor for aseptic loosening of the femoral stem.

CONCLUSIONS

Cemented primary total hip arthroplasty with the Charnley-type femoral stem made of Ti alloy showed excellent outcomes for more than 20 years.

Peri-prosthetic bone remodeling and change in bone mineral density in the femur after cemented polished tapered stem implantation

OBJECTIVE

We examined longitudinal changes in bone mineral density (BMD) around the femur for 5 years after total hip arthroplasty (THA) using cemented collarless polished double-tapered stem implantation and investigated the influence of BMD changes on radiological remodeling of the femur.

MATERIALS AND METHODS

Sixty hips from 56 patients who underwent cemented THA with a collarless polished double-tapered stem were included. BMD was measured 2 weeks postoperatively (baseline), 3 months, 6 months, 1 year and annually thereafter until 5 years after surgery using dual-energy X-ray absorptiometry on the lumbar spine and proximal femur of the operated side according to the Gruen's zone classification. We analyzed predictable factors for BMD preservation in the proximal femur and compared radiological remodeling of the femur and changes in BMD.

RESULTS

BMD at 5 years in zone 7 decreased less than 10%, whereas BMD in zone 1 increased to over the baseline (+ 1.9%). Multiple linear regression analyses revealed that body weight was a predictor for positive BMD change in the proximal femur. The frequency of radiolucency of the femur was significantly lower in patients who exhibited an increase in BMD at 5 years compared with BMD at 2 weeks in zone 7.

CONCLUSION

BMD preservation of the proximal femur after cemented collarless polished double-tapered stem implantation was more effective in heavier patients. Furthermore, the frequency of radiolucency around the stem was significantly lower in patients who exceeded 100% of the baseline BMD in zone 7 at 5 years.

Cemented Femoral Component Use in Hip Arthroplasty

Elderly patients undergoing both elective and nonelective hip arthroplasty contribute markedly to health care spending, and the current aging population is likely to require even more resources. Several national joint replacement registries show a lower risk of revision surgery in patients older than 75 years who received cemented femoral components compared with cementless implants for primary total hip arthroplasty. Despite a higher incidence of early periprosthetic femoral fracture, noncemented femoral components are being used with increasing frequency in elderly patients worldwide. Improvements in cementing technique and modifications to cemented stem design over several decades allow surgeons to obtain femoral component fixation in poor-quality bone with a relatively low risk of complications. Achieving durable cemented stem fixation requires the surgeon to understand the basic handling properties of cement, how to prepare the femoral bone, and differences in stem design and surface finish.

More reoperations for periprosthetic fracture after cemented hemiarthroplasty with polished taper-slip stems than after anatomical and straight stems in the treatment of hip fractures

Aims

The aim of this large registry-based study was to compare mid-term survival rates of cemented femoral stems of different designs used in hemiarthroplasty for a fracture of the femoral neck.

Patients and Methods

From the Norwegian Hip Fracture Register (NHFR), 20 532 primary cemented bipolar hemiarthroplasties, which were undertaken in patients aged > 70 years with a femoral neck fracture between 2005 and 2016, were included. Polished tapered stems (n = 12 065) (Exeter and CPT), straight stems (n = 5545) (Charnley, Charnley Modular, and Spectron EF), and anatomical stems (n = 2922) (Lubinus SP2) were included. The survival of the implant with any reoperation as the endpoint was calculated using the Kaplan–Meier method and hazard ratios (HRs), and the different indications for reoperation were calculated using Cox regression analysis.

Results

The one-year survival was 96.0% (95% confidence interval (CI) 95.6 to 96.4) for the Exeter stem, 97.0% (95% CI 96.4 to 97.6) for the Lubinus SP2 stem, 97.6% (95% CI 97.0 to 98.2) for the Charnley stem, 98.1% (95% CI 97.3 to 98.9) for the Spectron EF stem, and 96.4% (95% CI 95.6 to 97.2) for the Charnley Modular stem, respectively. The hazard ratio for reoperation after one year was lower for Lubinus SP2 (HR 0.77, 95% CI 0.60 to 0.97), Charnley (HR 0.64, 95% CI 0.48 to 0.86), and Spectron EF stems (HR 0.44, 95% CI 0.29 to 0.67) compared with the Exeter stem. Reoperation for periprosthetic fracture occurred almost exclusively after the use of polished tapered stems.

Conclusion

We were able to confirm that implant survival after cemented hemiarthroplasty for a hip fracture is high. Differences in rates of reoperation seem to favour anatomical and straight stems compared with polished tapered stems, which had a higher risk of periprosthetic fracture.

The Exeter V40 cemented femoral component at a minimum 10-year follow-up: the first 540 cases

Aims

The aim of this study was to report the initial results of the Exeter V40 stem, which became available in 2000.

Patients and Methods

A total of 540 total hip arthroplasties (THAs) were performed in our unit using this stem between December 2000 and May 2002. Our routine protocol is to review patients postoperatively and at one, five, and ten years following surgery.

Results

A total of 145 patients (26.9%) died before ten years and of the remaining 395 stems, 374 (94.7%) remain in situ. A total of 21 well-fixed stems (5.3%) were revised. Ten were exchanged using a cement-in-cement technique to facilitate acetabular revision. Three were revised for infection, one for instability, one for fracture of the stem, and six following a periprosthetic fracture. An additional 16 acetabular components (4.1%) were revised; five for aseptic loosening and 11 for instability. There were no revisions for aseptic loosening of the stem, and no evidence of aseptic loosening in any hip. The fate of every stem is known and all patients remain under review. Survivorship, with revision of the stem for aseptic loosening as the endpoint, was 100%. At 13.5 years, the Kaplan-Meier survival rate for all-cause revision of the stem was 96.8% (95% confidence interval (CI) 94.8 to 98.8) and all-cause revision (including acetabular revision, infection, and instability) was 91.2% (95% CI 88.3 to 94.1).

Conclusion

Conclusion No stem was revised for aseptic loosening in this series. The contemporary Exeter V40 stem continues to perform well, and survival has remained comparable with that of the Exeter Universal stem. Cite this article: Bone Joint J 2018;100-B:1002-9.

Biomechanical behaviour of a French femoral component with thin cement mantle: The 'French paradox' may not be a paradox after all

Objective

Cement thickness of at least 2 mm is generally associated with more favorable results for the femoral component in cemented hip arthroplasty. However, French-designed stems have shown favorable outcomes even with thin cement mantle. The biomechanical behaviors of a French stem, Charnley-Marcel-Kerboull (CMK) and cement were researched in this study.

Methods

Six polished CMK stems were implanted into a composite femur, and one million times dynamic loading tests were performed. Stem subsidence and the compressive force at the bone-cement interface were measured. Tantalum ball (ball) migration in the cement was analyzed by micro CT

Results

The cement thickness of 95 % of the proximal and middle region was less than 2.5 mm. A small amount of stem subsidence was observed even with collar contact. The greatest compressive force was observed at the proximal medial region and significant positive correlation was observed between stem subsidence and compressive force. 9 of 11 balls in the medial region moved to the horizontal direction more than that of the perpendicular direction. The amount of ball movement distance in the perpendicular direction was 59 to 83% of the stem subsidence, which was thought to be slip in the cement of the stem. No cement defect and no cement breakage were seen.

Conclusion

Thin cement in CMK stems produced effective hoop stress without excessive stem and cement subsidence. Polished CMK stem may work like force-closed fixation in short-term experiment.

Cite this article: Y. Numata, A. Kaneuji, L. Kerboull, E. Takahashi, T. Ichiseki, K. Fukui, J. Tsujioka, N. Kawahara. Biomechanical behaviour of a French femoral component with thin cement mantle: The ‘French paradox’ may not be a paradox after all. Bone Joint Res 2018;7:485–493. DOI: 10.1302/2046-3758.77.BJR-2017-0288.R2.

Outcomes following osteosynthesis of periprosthetic hip fractures around cemented tapered polished stems

We retrospectively reviewed outcomes of 79 patients with periprosthetic hip fractures around cemented tapered polished stem (CTPS) implants treated with osteosynthesis between January 1997 and July 2011. All patients underwent open reduction and fixation using a broad dynamic compression plate (DCP). Seventy two (91%) of fractures united. There were seven (9%) non-unions with failure of metal work, three (4%) as a result of infection and four (5%) due to mechanical failure. Significant subsidence (>5mm) of the implant was seen in seven (9%) of cases. Ten (13%) cases developed post-operative infection. Non-anatomic reduction and infection were identified as predictors of poor outcome. This is the largest series of a very specific group of periprosthetic fractures treated with osteosynthesis. Open reduction internal fixation with a broad dynamic compression plate for patients with periprosthetic hip fractures around the tip of cemented tapered polished stems is a suitable treatment provided there is no bone loss and the fracture can be precisely, anatomically, reduced and adequately fixed.

Ten-year RSA-measured migration of the Exeter femoral stem

The Exeter femoral stem is a double-tapered highly polished collarless cemented implant with good long-term clinical results. In order to determine why the stem functions well we have undertaken a long-term radiostereometric analysis (RSA) study. A total of 20 patients undergoing primary Exeter total hip replacement for osteoarthritis using the Hardinge approach were recruited and followed with RSA for ten years. The stems progressively subsided and internally rotated with posterior head migration. The mean subsidence was 0.7 mm (95% confidence interval (CI) 0.5 to 0.9) at two years and 1.3 mm (95% CI 1.0 to 1.6) at ten years. The mean posterior migration of the head was 0.7 mm (95% CI 0.5 to 0.9) at two years and 1.2 mm (95% CI 1.0 to 1.4) at ten years. There was no significant cement restrictor migration. The Exeter stem continues to subside slowly into the cement mantle in the long term. This appears to compress the cement and the cement bone interface, contributing to secure fixation in the long term.

Surface finish of the Exeter Trauma Stem

Recent guidance recommends the use of a well-proven cemented femoral stem for hemiarthroplasty in the management of fractures of the femoral neck, and the Exeter Trauma Stem (ETS) has been suggested as an example of such an implant. The design of this stem was based on the well-proven Exeter Total Hip Replacement stem (ETHRS). This study assessed the surface finish of the ETS in comparison with the ETHRS. Two ETSs and two ETHRSs were examined using a profilometer with a precision of 1 nm and compared with an explanted Exeter Matt stem. The mean roughness average (RA) of the ETSs was approximately ten times higher than that of the ETHRSs (0.235 μm (0.095 to 0.452) versus 0.025 μm (0.011 to 0.059); p < 0.001). The historical Exeter Matt stem roughness measured a mean RA of 0.973 μm (0.658 to 1.159). The change of the polished Exeter stem to a matt surface finish in 1976 resulted in a high stem failure rate. We do not yet know whether the surface differences between ETS and ETHRS will be clinically significant. We propose the inclusion of hemiarthroplasty stems in national joint registries.

Cite this article: Bone Joint J 2013;95-B:173–6.

Clinical and radiological results of the collarless polished tapered stem at 15 years follow-up

We prospectively followed 191 consecutive collarless polished tapered (CPT) femoral stems, implanted in 175 patients who had a mean age at operation of 64.5 years (21 to 85). At a mean follow-up of 15.9 years (14 to 17.5), 86 patients (95 hips) were still alive. The fate of all original stems is known. The 16-year survivorship with re-operation for any reason was 80.7% (95% confidence interval 72 to 89.4). There was no loss to follow-up, with clinical data available on all 95 hips and radiological assessment performed on 90 hips (95%). At latest follow-up, the mean Harris hip score was 78 (28 to 100) and the mean Oxford hip score was 36 (15 to 48). Stems subsided within the cement mantle, with a mean subsidence of 2.1 mm (0.4 to 19.2). Among the original cohort, only one stem (0.5%) has been revised due to aseptic loosening. In total seven stems were revised for any cause, of which four revisions were required for infection following revision of the acetabular component. A total of 21 patients (11%) required some sort of revision procedure; all except three of these resulted from failure of the acetabular component. Cemented acetabular components had a significantly lower revision burden (three hips, 2.7%) than Harris Galante uncemented components (17 hips, 21.8%) (p < 0.001). The CPT stem continues to provide excellent radiological and clinical outcomes at 15 years following implantation. Its results are consistent with other polished tapered stem designs.

First-time revision using impacted morsellised allograft bone with a cemented Exeter stem

Previously, radiostereometric analysis following hip revision performed using impacted morsellised allograft bone and a cemented Exeter stem has shown continuous subsidence of the stem for up to five years. It is not known whether the subsidence continues thereafter. In our study, 17 of 25 consecutive osteo-arthritic patients with aseptically loose stems who underwent first-time revision using impacted morsellised allograft bone and a cemented Exeter stem were followed by yearly radiostereometric examinations for nine years. The mean subsidence at six weeks was 1.1 mm (0.1 to 2.3), from six weeks to one year 1.3 mm (0 to 2.6), from one to five years 0.7 mm (0 to 2.0), and from five to nine years 0.7 mm (0.1 to 3.1). That from six weeks to nine years was 2.7 mm (0 to 6.4) (95% confidence interval 2.0 to 3.5). The Charnley pain score significantly improved after revision, and was maintained at nine years, but walking ability deteriorated slightly as follow-up extended. Of the eight patients who were not followed for nine years, two had early subsidence exceeding 11 mm.

Our findings show that in osteo-arthritic patients who undergo revision for aseptic loosening of the stem using impacted morsellised allograft bone and a cemented Exeter stem, migration of the stem continues over nine years at a slower rate after the first year, but without clinical deterioration or radiological loosening.

Randomised controlled trial comparing early migration of two collarless polished cemented stems using radiostereometric analysis

This was a safety study where the hypothesis was that the newer-design CPCS femoral stem would demonstrate similar early clinical results and micromovement to the well-established Exeter stem. Both are collarless, tapered, polished cemented stems, the only difference being a slight lateral to medial taper with the CPCS stem. A total of 34 patients were enrolled in a single-blinded randomised controlled trial in which 17 patients received a dedicated radiostereometric CPCS stem and 17 a radiostereometric Exeter stem. No difference was found in any of the outcome measures pre-operatively or post-operatively between groups. At two years, the mean subsidence for the CPCS stem was nearly half that seen for the Exeter stem (0.77 mm (−0.943 to 1.77) and 1.25 mm (0.719 to 1.625), respectively; p = 0.032). In contrast, the mean internal rotation of the CPCS stem was approximately twice that of the Exeter (1.61° (−1.07° to 4.33°) and 0.59° (0.97° to 1.64°), respectively; p = 0.048). Other migration patterns were not significantly different between the stems. The subtle differences in designs may explain the different patterns of migration.

Comparable migration with the Exeter stem suggests that the CPCS design will perform well in the long term.

Revision of the cemented femoral stem using a cement-in-cement technique

The removal of well-fixed bone cement from the femoral canal during revision of a total hip replacement (THR) can be difficult and risks the loss of excessive bone stock and perforation or fracture of the femoral shaft. Retaining the cement mantle is attractive, yet the technique of cement-in-cement revision is not widely practised. We have used this procedure at our hospital since 1989. The stems were removed to gain a better exposure for acetabular revision, to alter version or leg length, or for component incompatibility.

We studied 136 hips in 134 patients and followed them up for a mean of eight years (5 to 15). A further revision was required in 35 hips (25.7%), for acetabular loosening in 26 (19.1%), sepsis in four, instability in three, femoral fracture in one and stem fracture in one. No femoral stem needed to be re-revised for aseptic loosening.

A cement-in-cement revision of the femoral stem is a reliable technique in the medium term. It also reduces the risk of perforation or fracture of the femoral shaft.

Subsidence of the stem after impaction bone grafting for revision hip replacement using irradiated bone

Loss of bone stock is a major problem in revision surgery of the hip. Impaction bone grafting of the femur is frequently used when dealing with deficient bone stock. In this retrospective study a consecutive series of 68 patients (69 hips) who had revision of a hip replacement with femoral impaction grafting were reviewed. Irradiated bone allograft was used in all hips. Radiological measurement of subsidence of the stem, incorporation of the graft and remodelling was carried out and showed incorporation of the graft in 26 of 69 hips (38%). However, there was no evidence of trabecular remodelling. Moderate subsidence of 5 mm to 10 mm occurred in ten hips (14.5%), and massive subsidence of > 10 mm in five (7.2%). The results of this study are less favourable than those of others describing studies of revision of the femoral stem using impaction bone grafting. The absence of the characteristic changes of graft remodelling noted in other series raises the question as to whether irradiated bone graft may be a significant factor influencing the post-operative outcome.

The use of the cemented Exeter Universal femoral stem in a District General Hospital

We describe the survivorship of the Exeter femoral component in a District General Hospital. Between 1994 and 1996, 230 Exeter Universal cemented femoral components were implanted in 215 patients who were reviewed at a mean of 11.2 years (10 to 13). We used one acetabular implant, the Elite Ogee component, in 218 of the 230 hips.

During the period of this study 76 patients (79 hips) died. Of the remaining 139 patients (151 hips), 121 were able to attend for radiological analysis at a minimum of ten years. One patient was lost to follow-up.

No femoral component was revised for aseptic loosening. Three hips were revised for deep infection and six acetabular components required revision, four for loosening and two for recurrent dislocation. Taking the ‘worst-case scenario’ including the one patient lost to follow-up, the overall survival rate was 94.4% at 13 years.

Our results confirm excellent medium-term results for the Exeter Universal femoral component, implanted in a general setting. The excellent survival of this femoral component, when used in combination with the Ogee acetabular component, suggests that this is a successful pairing.

Cemented total hip replacement for primary osteoarthritis in patients aged 55 years or older: results of the 12 most common cemented implants followed for 25 years in the Finnish Arthroplasty Register

We have analysed from the Finnish Arthroplasty Register the long-term survivorship of the 12 most commonly-used cemented implants between 1980 and 2005 in patients aged 55 years or older with osteoarthritis. Only two designs of femoral component, the Exeter Universal and the Müller Straight femoral component had a survivorship of over 95% at ten years with revision for aseptic loosening as the endpoint. At 15 years of the femoral and acetabular component combinations, only the Exeter Universal/Exeter All-poly implant had a survival rate of over 90% with revision for aseptic loosening as the endpoint. In the subgroup of patients aged between 55 and 64 years, survivorship overall was less than 90% at ten years. The variation in the long-term rates of survival of different cemented hip implants was considerable in patients aged 55 years or older. In those aged between 55 and 64 years, none of the cemented prostheses studied yielded excellent long-term survival rates (> or = 90% at 15 years).

Collarless polished tapered stem: clinical and radiological results at a minimum of ten years' follow-up

We retrospectively reviewed 175 patients (191 hips) who had undergone primary cemented total hip replacement between November 1992 and November 1995 using a collarless polished double-tapered femoral component after a minimum of ten years (mean 11.08; 10 to 12.8). All stems were implanted using contemporary cementing techniques with a distal cement restrictor, pressurised lavage, retrograde cementing with a gun and proximal pressurisation. Clinical outcome was assessed using the Harris Hip score. Radiological analysis was performed on calibrated plain radiographs taken in two planes. Complete radiological data on 110 patients (120 hips) and clinical follow-up on all the surviving 111 patients (122 hips) was available. The fate of all the hips was known. At final follow-up, the mean Harris Hip score was 86 (47 to 100), and 87 of 116 patients (75%) had good or excellent scores. Survival with revision of the stem for aseptic loosening as the endpoint was 100%; and survival with revision of the stem for any reason was 95.9% (95% confidence interval 87.8 to 96.8) at ten years. All the stems subsided vertically at the stem-cement interface in a predictable pattern, at an overall mean rate of 0.18 mm per year (0.02 to 2.16), but with a mean rate of 0.80 mm (0.02 to 2.5) during the first year. The mean total subsidence was 1.95 mm (0.21 to 24). Only three stems loosened at the cement-bone interface. There was excellent preservation of proximal femoral bone stock. There was a high incidence of Brooker III and IV heterotopic ossification affecting 25 patients (22%). The collarless polished tapered stem has an excellent clinical and radiological outcome at a minimum of ten years' follow-up. The pattern and magnitude of subsidence of the stem within the cement mantle occurred in a predictable pattern, consistent with the design philosophy.

The effect of cross-sectional stem shape on the torsional stability of cemented implant components

Stability of a cemented implant, once the stem-cement interface has debonded, is reliant upon stem geometry and surface finish. There are relatively few studies addressing the effect of cross-sectional stem shape on cemented implant fixation. The purpose of this investigation was to compare the torsional stability of five different stem cross-sectional shapes-circular, oval, triangular, rectangular with rounded edges, and rectangular with sharp edges-under monotonically increasing and cyclic loading conditions. Seven samples of each stem geometry were tested. Stems were potted in bone cement and loaded to 5 deg of rotation. For monotonic loading, torque was applied at a constant rate of 2.5 deg/min. For cyclic loading, a sine wave torque pattern was applied, with a maximum magnitude that began at 4.5 Nm for 1500 cycles and then increased by 2.25 Nm every 1500 cycles until 5 deg of rotation. The rectangular stem with the sharp edges always provided the greatest resistance to torque, followed by the rectangular with rounded edges, triangular, oval, and circular. These results, including the effects of sharp corners, may differ for modes of loading other than torsion. These experimental results support the findings of earlier finite element models, indicating stem shape has a significant effect on resistance to torsional loading.

The design features of cemented femoral hip implants

We undertook a review of the literature relating to the two basic stem designs in use in cemented hip replacement, namely loaded tapers or force-closed femoral stems, and the composite beam or shape-closed designs. The associated stem fixation theory as understood from in vitro studies and finite element modelling were examined with reference to the survivorship results for each of the concepts of fixation.

It is clear that both design principles are capable of producing successful long-term results, providing that their specific requirements of stem metallurgy, shape and surface finish, preparation of the bone and handling of the cement are observed.

Total hip arthroplasty with satin finish, tapered stems

Subsidence of femoral hip prostheses with a rough surface has been associated with osteolysis and loosening. However, recent evidence has suggested that smooth-finish tapered stems may not incur these problems. An experimental monobloc satin finish, tapered femoral component was designed to subside within the cement. There were 49 femoral components implanted, and patients averaged a 1.8-mm subsidence at the prosthesis-cement interface with a follow-up of 6.76 years. There were no failures attributable to aseptic loosening at the cement-bone interface. This study supports the use of a satin finish, tapered femoral component in cemented total hip arthroplasty.

Movement patterns of the C-stem femoral component

We used roentgen stereophotogrammetric analysis to follow 33 C-stem femoral components for two years after primary total hip arthroplasty. All components migrated distally and posteriorly within the cement mantle. The mean distal migration was 1.35 mm (sd 0.62) at two years and the mean posterior migration was 1.35 mm (sd 0.69) at two years. All the femoral components rotated into retroversion with a mean rotation at two years of 1.9° (sd 1.1). For all other directions, the prosthesis was stable up to two years. Compared with other tapered prostheses, the distal migration of the C-stem is the same, but posterior rotation and posterior migration are greater.

The cemented femoral stem: selecting the ideal patient

A woman who is elderly, lightweight, and low demand has traditionally been considered an ideal candidate for a cemented femoral stem. Patients who are young, heavy, and high demand have been considered higher risk for failure and, therefore, better suited for cementless femoral stems. However, modern cement techniques and implants have improved outcomes in high-risk cohorts, and stress shielding, thigh pain, and osteolysis have emerged as long-term challenges for cementless femoral stems. Recently reported positive bone remodeling around a cemented, triple-tapered, polished, collarless stem behaving according to the taper-slip philosophy of femoral stem fixation may widen the traditional indications for cemented femoral stems. Paradoxically, patients initially thought to be poor candidates for cemented fixation may benefit most from the long-term bone preservation and positive loading characteristics of this new generation of cemented stem technology.

Evolution of cemented stems

John Charnley was responsible for pioneering successful cemented hip arthroplasty. Changes in stem design were made in response to early complications such as stem fracture. Various philosophies of stem biomechanics emerged, namely stems performing in the taper slip mode and stems performing as a composite beam. Both stem designs may be successful, although it is important not to mix biomechanical philosophies. Later evolutions have occurred in response to surgical flexibility, specifically modularity and offset options. These attributes can impart new demands on the stem and, in some cases, retrograde developments have occurred. Cemented stems may yield excellent long-term results and have the potential to limit fixation to the proximal femur and establish a metaphyseal-loading regimen. The latest design of taper slip stems, such as the C-stem (DePuy Orthopaedics, Warsaw, Ind), may have advantages in maintaining proximal bone stock and preserving host bone. The historical developments and evolution of the cemented stem in total hip arthroplasty (THA) are discussed.

A rough surface finish adversely affects the survivorship of a cemented femoral stem

To assess the role of surface finish in the survivorship of a cemented femoral stem, we evaluated the midterm clinical and radiographic performances of a cohort of patients who had total hip arthroplasties with two cemented femoral stems that differed only in surface finish. One hundred seventy-five patients [64 total hip arthroplasties with rough, textured stems (radius, 1.75-2.5 microm) and 138 total hip arthroplasties with satin finish, textured stems (radius, 0.5 microm)] were followed up clinically and radiographically for 4-8 years. All surgeries were done by one surgeon using the same surgical technique, acetabular cup, cement type, and cementing technique. The groups had similar demographics, diagnoses, preoperative clinical scores, cement mantle qualities, alignments, and lengths of followup. Seven hips in the rough surface group and none in the satin surface group had aseptic loosening. The femoral bone-cement interface showed progressive radiolucent lines or osteolysis in eight of 64 rough stems and in three of 138 satin stems. A rough, textured stem of this design is more likely to fail at intermediate followup than a satin surface stem. We recommend that the surface of cemented stems should be satin or polished with a radius less than 0.5 microm.

LEVEL OF EVIDENCE

Therapeutic study, Level III-1 (case-control study). See the Guidelines for Authors for a complete description of levels of evidence.

Small stem Exeter total hip replacement: clinical and radiological follow-up over a minimum of 2.5 years

PURPOSE

To evaluate the clinical and radiological outcome in patients undergoing small stem Exeter total hip replacement.

METHODS

A total of 46 small stem Exeter total hip replacements were performed on 44 consecutive patients (18 men and 26 women) attending the University of Malaya Medical Centre. The mean age at the time of operation was 58 years (range, 24-81 years). Of the 46 procedures performed, 35 were primary total hip replacements and 11 were revision operations, with aseptic loosening of the original implant being the main indication for revision. The main indications for surgery in primary cases were avascular necrosis and rheumatoid arthritis. Clinical and radiographic outcomes were assessed at 6 weeks', 12 weeks', 6 months' follow-up, and annually thereafter. Postoperative cementing technique was also assessed.

RESULTS

The mean follow-up period was 4 years. The mean Oxford Hip Score improved from 46 points preoperatively to 17 points at the final follow-up examination. There were no revision operations, no implant breakages, and no excessive migration of the implants. The potential complications of implant failure due to smaller implant size and increased patient activity were not observed.

CONCLUSION

Due to the smaller size of Asian femora, the small stem Exeter implant is a very useful development. This study suggests that it will perform as well as its larger counterparts.

The Frank Stinchfield Award. Influence of cement technique on the interface strength of femoral components

The optimal surface finish for polymethylmethacrylate cemented femoral components remains controversial. Concerns about early debonding of the prosthesis-cement interface have led surgeons to use roughened surfaces to enhance the cement-prosthesis bond. However, loosening of roughened stems is associated with the generation of excessive wear debris. The purpose of the current study was to determine whether the time to cementation influenced the cement-prosthesis bond of four roughened cobalt chrome surfaces (60 grit-blasted, 10 grit-blasted, 10 grit-blasted with polymethylmethacrylate precoating, glass bead-blasted) and one polished cobalt chrome surface. Fixation strength was assessed using mechanical pushout and tensile testing. Roughened and polymethylmethacrylate precoated surfaces had significantly greater tensile and shear strengths at early cementation times compared with polished surfaces. However, roughened components had significant decreases in tensile and shear strengths as cementation time increased from 2 to 4 minutes and 2 to 6 minutes. In contrast, tensile and shear strengths for the polished surface were significantly lower than for the roughened surfaces and did not change with longer cementation times. When using a roughened or precoated cemented femoral component, the surgeon should consider cementing earlier with wetter cement to maximize the cement-prosthesis bond. When implanting a polished femoral component, it is preferable that the cement is doughy, because the cement-prosthesis bond is not influenced by the wetness of the cement and it is easier to maintain the orientation of the femoral component.