Long-term results of Charnley-Kerboull hip arthroplasty in patients younger than 50 years

Larger stem to bone diameter ratio predicts lower cemented endoprosthesis failure

BACKGROUND AND OBJECTIVES

With continued advances in treatment options, patients with endoprosthetic reconstruction are living longer and consequently relying upon their devices for a longer duration. Major causes of endoprosthesis failure include aseptic loosening and mechanical failure. In the setting of tumor resection, loss of bone stock and use of radiation therapy increase the risk for these complications. As such, considerations of remaining native bone and stem length and diameter may be increasingly important. We asked the following questions: (1) What was the overall rate of endoprosthesis failure at a minimum of 5-year follow-up? (2) Does resection length increase implant failure rates? (3) Does implant size and its ratio to cortical width of bone alter implant failure rates?

METHODS

We retrospectively analyzed patient outcomes at a single institution between the years of 1999-2022 who underwent cemented endoprosthetic reconstruction at the hip or knee and identified 150 patients. Of these 150, 55 had a follow-up of greater than 5 years and were used for analysis. Radiographs of these patients at time of surgery were assessed and measured for resection length, bone diameter, stem diameter, and remaining bone length. Resection percentage, and stem to bone diameter ratios were then calculated and their relationship to endoprosthesis failure were analyzed.

RESULTS

Patients in this cohort had a mean age of 55.8, and mean follow-up of 59.96 months. There were 78 distal femoral replacements (52%), 16 proximal femoral replacements (10.7%), and 56 proximal tibial replacements (37.3%). There were five patients who experienced aseptic loosening and six patients who experienced mechanical failure. Patients with implant failure had a smaller mean stem to bone diameter (36% vs. 44%; p = 0.002). A stem to bone diameter of 40% appeared to be a breaking point between success and failure in this series, with 90% of patients with implant failure having a stem: bone ratio less than 40%. Stem to bone ratio less than 40% increased risk for failure versus stems that were at least 40% the diameter of bone (6/19 [31.6%] vs. 0/36 [0%]; odds ratio 0.68; p < 0.001). Resection length did not appear to have an impact on the rates of aseptic loosening and mechanical failure in this series.

CONCLUSIONS

Data from this series suggests a benefit to using stems with a larger diameter when implanting cemented endoprostheses at the hip or knee. Stems which were less than 40% the diameter of bone were substantially more likely to undergo implant failure.

Femoral Stem Cementation in Primary Total Hip Arthroplasty

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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.

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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.

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

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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.

Outcomes of Cemented Distal Femoral Replacement Using "Line to Line" Technique With All-Polyethylene Tibial Implant for Tumors

BACKGROUND

Both cemented and cementless stemmed endoprosthetic implants have been used to reconstruct large skeletal defects after tumor resection with similar outcomes. In this study, we examined the oncologic, clinical, and functional outcomes in patients undergoing distal femur replacement using the French paradox technique.

METHODS

A total of 125 patients who underwent distal femur replacement between 1990 and 2019 using the line-to-line cementation technique were reviewed. Implant failure was recorded as per Henderson's classification. Functional outcomes were analyzed using the Musculoskeletal Tumor Society and Toronto Extremity Salvage Score scoring systems. The mean follow-up was 84 (1-350) months.

RESULTS

Aseptic loosening of the femoral stem was recorded in one patient at 21-years of follow-up. Twenty of 125 patients required bushing exchange for polyethylene wear, all after 10 years. Six tibial bearing component fractures were recorded in four patients while one femoral stem component Morse taper fractured. Two all-polyethylene cemented tibial implants were revised for polyethylene granuloma. Deep surgical site infection occurred in 13 patients, while six patients experienced local recurrence. Kaplan-Meier estimates for implant survival for all-cause revision were 85% at 1 year and 70% at 5 years. These estimates for femur or tibia loosening as an end point were 96% at 10 years and 90% at 15 years. The mean Musculoskeletal Tumor Society and Toronto Extremity Salvage Score scores at the last follow-up were 76% and 74%, respectively. Thirty-five patients died of disease progression.

CONCLUSION

The line-to-line cementation technique, used with all-polyethylene tibial implants, demonstrates low incidence of aseptic loosening at medium and long-term follow-ups.

LEVEL OF EVIDENCE

III.

Historical overview of hip arthroplasty: From humble beginnings to a high-tech future

Surgery of the arthritic hip was not an easy task in the previous centuries, lots of operations being followed very closely by complications and failures. Nowadays, hip arthroplasty is considered "the operation of the century". This review follows the evolution of surgery on the arthritic hip, with emphasis on arthroplasty. Acknowledging the history of this operation, one can better prepare its evolution and future directions of research. The final chapter briefly describes the current trends and future perspectives.

Short vs Standard-Length Femoral Stems Cemented According to the "French Paradox": A Matched Paired Prospective Study Using Ein Bild Roentgen Analyze Femoral Component at Two-Year Follow-Up

BACKGROUND

The purpose of this prospective matched paired study is to compare the in vivo migration patterns using Ein Bild Roentgen Analyze femoral component of shortened vs standard-length stems cemented line-to-line in primary total hip arthroplasty (THA) at 2-year follow-up.

METHODS

We prospectively included the first 50 consecutive primary cemented THAs in 50 patients using a 12% shortened stem (AmisK group) of which design was derived from the original Charnley-Kerboull (CK) femoral components. These 50 patients were matched paired to 50 patients from a historical series of patients who underwent primary THAs using standard-length CK stems (CK group) with available long-term results, including Ein Bild Roentgen Analyze femoral component data at 2-year follow-up.

RESULTS

Body mass index was significantly higher (P = .007) in the AmisK vs the CK group. At the 2-year follow-up, the mean subsidence was 0.65 mm (0-1.40) in the AmisK group vs 0.68 mm (0.07-1.43) in the CK group (P = .73). When using a 1.5-mm threshold, none of the stems in either group was considered to have subsided. Femoral cortical thickening in zones 3 and 5 occurred in 6 of the 50 hips (12%) in the AmisK group vs 20 (40%) of the 50 hips in the CK group (P = .003).

CONCLUSION

Our study showed that a shortened highly polished double-tapered stem cemented line-to-line provided similar results including minimal subsidence as its standard-length counterpart, with significantly less distal femoral cortical thickening. However, longer term survival analysis still needs to be determined.

Inhibitory effect of acetyl-11-keto-β-boswellic acid on titanium particle-induced bone loss by abrogating osteoclast formation and downregulating the ERK signaling pathway

Wear debris-induced osteoclast accumulation around implants plays a crucial role during the progression of periprosthetic osteolysis (PPO). We have confirmed that acetyl-11-keto-β-boswellic acid (AKBA) promotes bone formation and protects against particle-induced bone destruction in vivo. However, the effect of AKBA on titanium-induced bone resorption is unknown. In this study, we detected the inhibitory effect of AKBA on titanium-induced bone erosion in vivo and used RAW264.7 cells and bone marrow macrophages (BMMs) to investigate the effect and underlying mechanism of AKBA on the differentiation and resorptive function of osteoclasts. Our findings revealed that AKBA inhibited particle-induced bone loss and osteoclast formation in vivo. Furthermore, AKBA exerted inhibitory effects on RANKL-induced osteoclastogenesis, osteoclastic ring-dependent resorption and the expression of osteoclast marker genes via the ERK signaling pathway in vitro. Our data further established the protective effect of AKBA on titanium particle-induced bone erosion from a new perspective of bone erosion prevention, strongly confirming that AKBA is an appropriate agent for protection against PPO.

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.

Charnley femoral cemented stem with a permeable and resorbable cement restrictor and low-viscosity cement - Clinical and radiographical evaluation of 100 cases at a mean follow-up of 6.55 years

INTRODUCTION

In 1979, in his first book dealing with low-friction arthroplasty (LFA), Charnley highlighted the use of a cement restrictor. Breusch and Malchau described in 2005 the "second-generation cementing technique." The main objective of this study was to report on the clinical survival of 100 cases of Charnley femoral component implanted in 2007 and 2008 using a permeable and resorbable cement restrictor and a low-viscosity antibiotic-loaded cement. The secondary objectives were to analyze the complications and side effects and the accuracy of the device positioning.

MATERIAL AND METHODS

This was a monocentric retrospective review of a prospectively compiled database. Diaphyseal restrictor was biodegradable and permeable to gas, blood, and fluids to avoid intramedullary over pression during cementation. The cement was a low-viscosity antibiotic-loaded cement. Among 3555 patients, we selected the first continuous 100 cases of patients where we implanted the device. Survival probability was computed according to Kaplan-Meier method.

RESULTS

Mean follow-up was 6.55 ± 2.6 (range 1-11). Considering femoral component revision as the endpoint, survival rate was 100%. No patients died intraoperatively, none in the first month and the first year after surgery. No early periprosthetic fractures have been reported.

DISCUSSION

As described initially by Charnley, the use of a cement restrictor was highly recommended through the different generations of cementing techniques. Hypotensive episodes and cardiac arrest have been reported during cement insertion. In our series, we did not deplore any adverse effect related to the cementation.

CONCLUSION

Our study demonstrates a 100% survival rate of a cemented femoral component without adverse effects when using routinely a resorbable and permeable cement restrictor and a low-viscosity cement. Bone cement is still a fantastic ally for the surgeon and the patients.

Is cemented revision total hip arthroplasty a reasonable treatment option in an elderly population?

Revision THA is increasingly performed especially in the elderly population. The surgeon’s challenge is to provide a solution that supports immediate full weight-bearing, despite poor bone quality. Shape-closed revision stems facilitate that by combining cement fixation with additional press-fit anchoring. The design tolerates varying cement mantle thickness and inconsistent cancellous bone lining of the femoral canal. Following that philosophy, we present our mid-term results using a long version of a cemented Charnley- Kerboull type stem. From 2010 to 2017, 38 long Charnley-Kerboull revision stems (Centris^®, Mathys European Orthopaedics, Bettlach, Switzerland) were implanted and followed prospectively. Surgery was performed via a Hardinge approach in supine position with a third generation cementing technique. Patients were mobilized using full-weight bearing as early as possible. Survival was determined for stem revision for aseptic loosening and stem and/or cup revision for any reason. 20 stems had a minimum follow-up (f/u) of 2 years and were included for further radiological analysis. Detailed subsidence analysis as an early predictor for later aseptic loosening was performed using EBRA-FCA software. Further, the presence of osteolysis and cement debonding was evaluated. Mean follow- up was 4 years. No patient was lost to f/u.18 died of causes unrelated to THA. Stem survival was 100%. Survival for any re-operation was 82.2% (two early infections, one soft-tissue debridement, one cup exchange for recurrent dislocations). None of the cases revised for septic loosening showed signs of persistent infection at final f/u. EBRA-FCA revealed two oligosymptomatic cases of subsidence of 5mm and 6mm over a course of 2 and 12 months, respectively, with stable implants thereafter. Neither required revision. There was no development of osteolysis or debonding. The stem provides a reliable early fullweight bearing solution for revision THA with excellent mid-term survival in an elderly population. Even in two cases where subsidence was present, mobility was not impaired and re-revision could be avoided.

Biomechanics of a cemented short stem: Standard vs. line-to-line cementation techniques. A biomechanical in-vitro study involving six osteoporotic pairs of human cadaver femurs

BACKGROUND

Short-stem total hip arthroplasty (THA) potentially offers advantages compared to conventional THA, including sparing bone and soft tissue and being a facilitated and less traumatic implantation. However, the indication is limited to patients with sufficient bone quality. Cemented short-stem THA might provide an alternative to conventional cemented THA. To date, no cemented short stem is available on the market.

METHODS

In the present in vitro study, primary stability of a new cemented short stem was evaluated, comparing standard (undersized stem) versus line-to-line (same-sized stem) cementing techniques, using six pairs of human cadaver femurs. Primary stability, including reversible micromotion and irreversible migration, was assessed in a dynamic material-testing machine. Fracture load was tested and fracture pattern analyzed.

FINDINGS

Both cementation techniques (standard vs. line-to-line) displayed comparable results with respect to primary stability without any statistical differences (micromotion: 17.5 μm vs. 9.6 μm (p = 0.063); migration: 9.5 μm vs. 38.2 μm (p = 0.188)). Regarding fracture load, again, no difference was observed (3670 N vs. 3687 N (p = 0.063)). In all cases, proximal fractures of Vancouver type B3 occurred.

INTERPRETATION

The present in vitro study demonstrates that the line-to-line cementation technique, which is favourable regarding the philosophy of short stem THA, can be further pursued in the course of the development of a cemented short stem. Further investigations should address how well the cemented short stem compares to well-established cemented straight-stem designs.

Long-term results of revision total hip arthroplasty with a cemented femoral component

INTRODUCTION

In revision total hip arthroplasty (THA), the cancellous bone is normally completely removed out of the femoral canal during stem extraction. This situation is comparable to primary THA following the shape-closed concept, with some authors advocating to remove the metaphyseal cancellous bone to enhance press-fit stability ("French paradox"). The aim of this study was to investigate the long-term outcome, regarding survival and radiological results, of a cemented straight stem when used for revision THA and to compare these results to the results of the same stem in primary THA.

MATERIALS AND METHODS

178 stem revisions performed between 01/1994 and 08/2008 using the Virtec straight stem were included. The cumulative incidence for re-revision was calculated using a competing risk model. Risk factors for re-revision of the stem were analyzed using an absolute risk regression model. Radiographs analyzed for osteolysis, debonding and subsidence had a minimum follow-up of 10 years.

RESULTS

The cumulative incidence for re-revision due to aseptic loosening of the stem was 5.5% (95% CI, 2.9-10.2%) at 10 years. Aseptic loosening was associated with younger age, larger defect size and larger stem size. After a minimum 10-year follow-up, osteolysis was seen in 39 of 80 revision THA. Compared to the results in primary THA, the survival in revision THA with the same implant was inferior.

CONCLUSIONS

Cemented straight stems used for revision THA showed excellent long-term results regarding survivorship and radiological outcome. This stem therefore offers a valuable and cost-effective option in revision THA.

Inhibitory effects of melatonin on titanium particle-induced inflammatory bone resorption and osteoclastogenesis via suppression of NF-κB signaling

Wear debris-induced peri-implant osteolysis challenges the longevity of implants. The host response to wear debris causes chronic inflammation, promotes bone resorption, and impairs bone formation. We previously demonstrated that melatonin enhances bone formation and attenuates wear debris-induced bone loss in vivo. However, whether melatonin inhibits chronic inflammation and bone resorption at sites of wear debris-induced osteolysis remains unclear. In this study, we examined the potential inhibitory effects of melatonin on titanium particle-induced inflammatory osteolysis in a murine calvarial model and on RANKL-induced osteoclastic formation in bone marrow-derived macrophages. We found that the exogenous administration of melatonin significantly inhibited wear debris-induced bone resorption and the expression of inflammatory cytokines in vivo. Additionally, melatonin inhibited RANKL-induced osteoclast differentiation, F-actin ring formation, and osteoclastic resorption in a concentration-dependent manner in vitro. We also showed that melatonin blocked the phosphorylation of IκB-α and p65, but not IKKα, and significantly inhibited the expression of NFATc1 and c-Fos. However, melatonin had no effect on MAPK or PI3K/AKT signaling pathways. These results provide novel mechanistic insight into the anti-inflammatory and anti-bone resorptive effects of melatonin on wear debris-induced bone loss and provide an evidence-based rationale for the protective effects of melatonin as a treatment for peri-implant osteolysis.

STATEMENT OF SIGNIFICANCE

Wear debris-induced chronic inflammation, osteoclastic activation and osteoblastic inhibition have been identified as critical factors of peri-implant bone loss. We previously demonstrated that melatonin, a bioactive indolamine secreted mainly by the pineal gland, activates Wnt/β-catenin signaling pathway and enhances bone regeneration at osteolytic site in vivo. In the current study, we further demonstrated that melatonin significantly suppresses wear debris-induced bone resorption and inflammatory cytokine expression in vivo. In addition, melatonin inhibits receptor activator of nuclear factor kappa-B ligand induced osteoclast formation and osteoclastic bone resorption in vitro. Meanwhile, we found that melatonin mediates its anti-inflammation and anti-bone resorption effects by abrogating nuclear factor kappa-B activation. These results further support the protective effects of melatonin on wear debris-induced peri-implant bone loss, and strongly suggest that melatonin could be considered as a potential candidate for the prevention and treatment of wear debris-induced osteolysis and subsequent aseptic loosening.

A case control study of cemented acetabular total hip arthroplasty components in patients less than 50 with 5-year minimum follow-up

BACKGROUND

This study investigates the outcomes of cemented sockets in young patients (<50 years) requiring a total hip replacement (THR) compared to older patients (>50 years) having the same procedure, under the same surgeon between June 2005 and May 2009.

METHODS

Prosthesis survivorship rates, patient outcomes and radiological findings were compared between a consecutive series of 56 young patients (mean 42, range 25-49) and 56 older patients (mean 69, range 53-81) that underwent a primary THR using a cemented Stryker® Exeter™ Contemporary™ flanged cup. The minimum follow-up was 5 years.

RESULTS

No significant difference was observed between the groups' Oxford Hip Scores (p = 0.078) or satisfaction scores (p = 0.67). Worst case scenario analysis for revision, failure or lost to follow-up showed 94.6% survival in the <50 year olds and 92.9% survival in the >50 year olds at 5 years. This study demonstrates no significant difference in patient outcomes, survivorship or radiographic findings at a minimum of 5 years between patients <50 years old and those >50 years old undergoing THR with a cemented socket.

CONCLUSIONS

We believe the current trend towards uncemented cups may be driven by marketing rather than by evidence of improved outcomes. Cemented sockets provide very good outcomes for patients of all ages.

Bousquet dual mobility socket for patient under fifty years old. More than twenty year follow-up of one hundred and thirty one hips

PURPOSE

The aim of this study was to analyze dual mobility cup survival rate on young patients under 50 years old at more than 20 years of follow up.

METHODS

One hundred thirty seven hips with a first generation of dual mobility Bousquet cup (Serf) were included. The mean age at the time of the surgery was 41 years and the mean follow-up was 21.9 years.

RESULTS

Twenty year follow-up cup survival rate was 77%. No dislocation occurred, 44 hips were revised (including 21 cup aseptic loosenings isolated, 15 Intra Prosthetic Dislocations), seven hips were lost to follow-up, 11 patients died, and 75 hips were still in situ.

CONCLUSION

First generation dual mobility cup survival on young patient was comparable with literature results. The main complications, cup aseptic loosening and intra prosthetic dislocation, were wear-related. With improvements of the defects of first generation dual mobility, we might expect an even better survival rate with contemporary DM cups.

Low friction arthroplasty and dual mobility cup: a new gold standard

INTRODUCTION

Low friction arthroplasty (LFA) introduced by Sir John Charnley was the gold standard for many years. Dislocation and infection are the first causes for early revision. Late failures are polyethylene (PE) wear and loosening. Due to dislocation risk we slowly switched to the use of LFA with dual mobility cups (DMC). The purposes of this study are (1) to assess whether our changes have improved outcomes and (2) what is the new gold standard?

MATERIAL AND METHODS

We selected from an observational registry of 1,091 cases of hybrid Charnley total hip arthroplasty (THA). The acetabular component was either DMC in 455 cases or fixed cup (FC) in 636 cases.

RESULTS

Three dislocations (0.6%) occurred in the DMC group (none revised). In the FC group 54 dislocated (8.49%) and 20 were recurrent and underwent revision (revision rate 3.14%). In the DMC group, five acetabular and three femoral revisions were performed (revision rate for loosening 1.7%). In the FC group 19 cases underwent acetabular revision, and five cases had femoral component revised (revision rate for loosening 3.7%).

DISCUSSION

Charnley's LFA has proven over 50 years of excellent survivorship. To decrease dislocation risk, one suggested increasing femoral head diameter. Gilles Bousquet proposed another way, namely, the DMC concept. Dislocation is no longer a critical issue with DMC as demonstrated in our series and main series. DMC in primary THA is still a subject of debate. Mid-term results do not demonstrate a higher rate of wear than LFA. What is the current gold standard? LFA was and is our current gold standard in association with a DMC.

Dual-mobility cup in total hip arthroplasty in patients less than fifty five years and over ten years of follow-up : A prospective and comparative series

PURPOSE

We report clinical and radiological outcome of a dual mobility cup (DMC) of 2nd generation after a minimum of ten year-follow-up (FU). The goal of this work was to compare the results of this DMC in patients aged less than 55 years and in patients aged more than 55 years.

METHODS

From 2000 to 2005, a prospective and consecutive series of 119 THAs with a cementless DMC of 2nd generation (GIROS) were performed in patients aged less than 55 years and 444 in patients aged more than 55 years.

RESULTS

The mean FU was 11 years (8 to 15 years). Survivorships (failure of both components or cup loosening) were not different between patients aged less than 55 years and patients aged more than 55 years. There was no dislocation. DEVANE classification, Harris, PMA and Oxford scores improved after THA but no difference could be found between between < 55 years and > 55 years patients.

CONCLUSION

These results are better than those of first generation (BOUSQUET) DMC (77 % of survival rate at 20 years of FU). These results are in the same agreement than those of the literature: 99 % of survival rate at 14.2 years of FU for KERBOULL with a low friction arthroplasty and 96.5 % at ten years of FU for ceramic/ceramic bearing (R CHANA). The DMC for young patient is a relevant surgical option with no dislocation and excellent clinical results and survival rate at more than ten years of FU.

Cementless Total Hip Arthroplasty With Metasul Bearings Provides Good Results in Active Young Patients: A Concise Followup

BACKGROUND

A primary concern of younger, more active patients who have undergone total hip arthroplasty (THA) is the longevity of the implant. Cementless fixation and hard-on-hard bearings are recognized as options to enhance THA durability. Earlier, we published a series of 83 cementless primary THAs using 28-mm metal-on-metal (MoM) bearings in patients aged 50 years or younger; here we provide concise followup on that same group after an additional 8-year survey period.

QUESTIONS/PURPOSES

(1) What is the long-term survivorship of cementless primary THA using 28-mm MoM bearings in patients aged 50 years or younger? (2) What are the clinical and radiographic results of cementless THA in this active patient population? (3) Can any of the observed implant failures or adverse events be attributed to the metallic nature of the bearing couple?

METHODS

We retrospectively reviewed 83 cementless THAs performed in three institutions over a decade (1995-2004) in 68 patients with 28-mm MoM articulation. All patients (15 bilateral) had a median age of 42 years (range, 24-50 years) at the time of the index procedure and 56 of them (82% [70 hips]) had activity level graded Devane 4 or 5 before significant hip pain. A 28-mm Metasul™ articulation was used with an Alloclassic-SL™ cementless stem in all cases paired with three different cementless titanium acetabular components (one threaded and two press-fit cups) from the same manufacturer. Survivorship analysis was calculated according to Dobbs life table, patient clinical results were evaluated with use of the Postel-Merle d'Aubigné scoring system, radiographic analysis was performed by independent observers, and cobalt level was determined in whole blood.

RESULTS

The 15-year survivorship (33 hips at risk) for revision for any reasons (four hips) and for aseptic loosening (one hip) was 96% (95% confidence interval [CI], 81%-99%) and 99% (95% CI, 85%-99.9%), respectively. The median Merle d'Aubigné-Postel score remained stable at 17 points (range, 10-18). Thus far, we have not observed pseudotumors or other adverse reactions to metallic debris. Eight hips have undergone reoperation: trochanteric suture removal (one), psoas tendon impingement (two), and five revisions for periprosthetic fracture (one), late infection (two), acetabular osteolysis (one, as a result of polyethylene backside wear), and one hydroxyapatite-coated cup for aseptic loosening. None of the complications, failures, or revisions observed so far could directly be related to the metallic nature of the 28-mm Metasul bearings used in this selected group of patients.

CONCLUSIONS

The current survey at 13-year median followup has not yet indicated any long-term deleterious effects related to dissemination of metallic ions. Two senior authors continue to use 28- or 32-mm Metasul™ bearings with cementless THA components in young and active patient populations. Longer followup with a more sophisticated imaging study is necessary to confirm this so far positive report.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Allergy in total knee arthroplasty: a review of the facts

We explored the literature surrounding whether allergy and hypersensitivity has a clinical basis for implant selection in total knee arthroplasty (TKA). In error, the terms hypersensitivity and allergy are often used synonymously. Although a relationship is present, we could not find any evidence of implant failure due to allergy. There is however increasing basic science that suggests a link between loosening and metal ion production. This is not an allergic response but is a potential problem. With a lack of evidence logically there can be no justification to use 'hypoallergenic' implants in patients who have pre-existing skin sensitivity to the metals used in TKA.

Similar effect of stem geometry on radiological changes with 2 types of cemented straight stem: The Müller stem and the Virtec stem compared in 711 hips

BACKGROUND AND PURPOSE

There are 2 basic principles in cemented stem fixation: shape-closed and force-closed. We investigated 2 shape-closed straight stems, the Müller (MSS) and the Virtec (VSS), which differ only in geometrical cross section, to determine whether the difference in stem shape would affect the radiological results or long-term survival.

PATIENTS AND METHODS

We included 711 hips (in 646 patients) that were operated on between July 1996 and July 2003. Patients randomly received either an MSS (n = 356) or a VSS (n = 355) and were followed prospectively. Radiographs taken at a follow-up of > 10 years were analyzed for osteolysis. Kaplan-Meier (KM) survival analysis was performed using various endpoints. We also performed Cox regression analysis to identify risk factors for aseptic loosening and osteolysis of the stem.

RESULTS

After 10 years, KM survival with "revision of any component for any reason" was 92% (95% CI: 88-95) for the MSS and 95% (CI: 92-97) for the VSS (p = 0.1). With "revision for aseptic loosening of the stem" as the endpoint, KM survival was 96% (CI: 9-98) for the MSS and 98% (CI: 97-100) for the VSS (p = 0.2). Cox regression showed that none of the risk factors analyzed were independent regarding aseptic loosening of the stem or regarding osteolysis.

INTERPRETATION

The MSS and the VSS showed excellent survival for aseptic loosening after 10 years. For the 2 different stem designs, we did not find any independent risk factors for aseptic loosening or development of osteolysis.

Do oxidized zirconium femoral heads reduce polyethylene wear in cemented THAs? A blinded randomized clinical trial

BACKGROUND

Charnley low-friction torque total hip arthroplasty (THA) remains the gold standard in THA. The main cause for failure is wear of the socket. Highly crosslinked polyethylene (HXLPE) has been associated with reduced wear rates. Also, oxidized zirconium has shown in vitro reduced wear rates. However, to our knowledge, there are no data comparing oxidized zirconium femoral heads with metal heads against HXLPE or ultrahigh-molecular-weight polyethylene (UHMWPE) when 22.25-mm bearings were used, which was the same size that performed so well in Charnley-type THAs.

QUESTIONS/PURPOSES

We hypothesized that after a minimal 4-year followup (1) use of HXLPE would result in lower radiographic wear than UHMWPE when articulating with a stainless steel head or with an oxidized zirconium head; (2) use of oxidized zirconium would result in lower radiographic wear than stainless steel when articulating with UHMWPE and HXLPE; and (3) there would be no difference in terms of Merle d'Aubigné scores between the bearing couple combinations.

METHODS

One hundred patients were randomized to receive cemented THA with either oxidized zirconium or a stainless steel femoral head. UHMWPE was used in the first 50 patients, whereas HXLPE was used in the next 50 patients. There were 25 patients in each of the four bearing couple combinations. All other parameters were identical in both groups. Complete followup was available in 86 of these patients. Femoral head penetration was measured using a validated computer-assisted method dedicated to all-polyethylene sockets. Clinical results were compared between the groups using the Merle d'Aubigné score.

RESULTS

In the UHMWPE series, the median steady-state penetration rate from 1 year onward was 0.03 mm/year (range, 0.003-0.25 mm/year) in the oxidized zirconium group versus 0.11 mm/year (range, 0.03-0.29 mm/year) in the metal group (difference of medians 0.08, p < 0.001). In the HXLPE series, the median steady-state penetration rate from 1 year onward was 0.02 mm/year (range, -0.32 to 0.07 mm/year) in the oxidized zirconium group versus 0.05 mm/year (range, -0.39 to 0.11 mm/year) in the metal group (difference of medians 0.03, p < 0.001). The Merle d'Aubigné scores were no different between the groups with a median of 18 in each of the groups (range, 16-18).

CONCLUSIONS

This study demonstrated femoral head penetration was reduced by oxidized zirconium when compared with metal on both UHMWPE and HXLPE. However, apart the metal-UHMWE group, all other groups had a steady-state penetration rate well below the osteolysis threshold with a low difference between groups that might not be clinically important at this point. Longer-term followup is needed to warrant whether wear reduction will generate less occurrence of osteolysis and aseptic loosening.

LEVEL OF EVIDENCE

Level II, therapeutic study.

A randomised controlled trial comparing highly cross-linked and contemporary annealed polyethylene after a minimal eight-year follow-up in total hip arthroplasty using cemented acetabular components

Most published randomised controlled trials which compare the rates of wear of conventional and cross-linked (XL) polyethylene (PE) in total hip arthroplasty (THA) have described their use with a cementless acetabular component.

We conducted a prospective randomised study to assess the rates of penetration of two distinct types of PE in otherwise identical cemented all-PE acetabular components.

A total of 100 consecutive patients for THA were randomised to receive an acetabular component which had been either highly XL then remelted or moderately XL then annealed.

After a minimum of eight years follow-up, 38 hips in the XL group and 30 hips in the annealed group had complete data (mean follow-up of 9.1 years (7.6 to 10.7) and 8.7 years (7.2 to 10.2), respectively). In the XL group, the steady state rate of penetration from one year onwards was -0.0002 mm/year (sd 0.108): in the annealed group it was 0.1382 mm/year (sd 0.129) (Mann–Whitney U test, p < 0.001). No complication specific to either material was recorded.

These results show that the yearly linear rate of femoral head penetration can be significantly reduced by using a highly XLPE cemented acetabular component.

Cite this article: Bone Joint J 2015;97-B:1458–62.

Clinical and radiological outcomes with the Durom™ acetabular cup for large-diameter total hip arthroplasty: 177 implants after a mean of 80 months

BACKGROUND

Large-diameter metal-on-metal hip prostheses are no longer used, but their outcomes after more than 5 years are unknown. We conducted a retrospective study with a 6.8-year mean follow-up to assess clinical outcomes after Durom™ cup implantation, including the dislocation rate, comparatively to the reference metal-on-polyethylene bearing. We determined the rate of failure ascribable to Durom™ cup use. We also looked for a sharp drop in the implant survival curve during the follow-up period and for factors associated with adverse reactions to metal debris (ARMDs).

HYPOTHESIS

We hypothesised that clinical outcomes after Durom™ cup implantation were similar to those seen with a metal-on-polyethylene bearing, except for a lower rate of dislocation.

PATIENTS AND METHODS

We included 177 consecutive THA procedures that were performed between 2005 and 2008 in 165 patients with a mean age of 57.6 ± 9.4 years (range, 31-76 years) and involved the implantation of a Durom™ cup, a femoral head greater than 36mm in diameter, and a PF(®) femoral stem (Zimmer, Etupes, France). The mini-posterior approach was used, with 2mm of acetabular overreaming in 82% of cases, a short femoral neck in 75% of cases, and a mean cup inclination of 34 ± 5° (range, 21-50°).

RESULTS

Outcomes were assessed for 156 THA procedures in 146 patients after a mean follow-up of 6 years 8 months. The mean Postel-Merle d'Aubigné score improved from 9.7 ± 2.7 (range, 4-14) to 17.4 ± 1.7 (range, 15-18) and the mean Harris hip score from 45.2 ± 15.3 (range, 9-83) to 96.3 ± 7 (75-100). No episodes of dislocation were recorded. We identified 7 failures ascribable to the Durom™ cup including 6 due to ARMD and 1 to aseptic loosening. Implant survival after a mean of 80months was 95.5% (95% CI, 93.1-99.2), with no sharp drop in the survival curve.

CONCLUSION

The Durom™ cup eliminates the risk of hip dislocation and produces similar functional outcomes to those seen with metal-on-polyethylene bearings after a mean follow-up of 80 months. Nevertheless, given the difficulty in predicting ARMD and hypersensitivity reactions, the Durom™ cup has been discarded and patients carrying it are monitored closely.

Is cemented metal-polyethylene 22.2mm hip arthroplasty a gold standard? Results of a series of 105 primary arthroplasties at a minimum of ten years follow-up

INTRODUCTION

Although Charnley-Kerboull metal-on-polyethylene 22.2mm cemented total hip arthroplasty (THA) is considered to be the gold standard in France, results with this prosthesis are conflicting, in particular in relation to Scandinavian registers. The goal of this retrospective study was to confirm the validity of this prosthesis at a minimum of 10years follow-up.

HYPOTHESIS

Survival of this type of THA would fulfill NICE conditions (survival at 10 years of at least 90%).

MATERIALS AND METHODS

One hundred and five primary THA were performed in 93 patients (30 men and 63 women) mean age 72.6 years old (60-86) between January 1998 and March 2001. After a mean follow-up of 10.6 years (10-13 years), 21 patients (23 THA) were lost to follow-up and 32 (35 THA) had died leaving 40 patients (47 THA) for clinical analysis (Merle d'Aubigné and Oxford scores) and X-ray assessment. Survival was calculated with revision for any cause and radiological loosening with or without revision as end-points.

RESULTS

The mean Oxford score at the final follow-up was 22/60 (13-45), the PMA score was 14.2 (11-17). Eight patients underwent revision surgery after a mean 7.5 years (2-11) (1 early dislocation and 7 acetabular cup loosenings). Survival at 10 years was 89.4% (CI95%: 78-95) for all causes of revision and 78% (CI95%: 61-91) for loosening with (n=7) or without (n=3) revision. No cases of septic or femoral loosening were observed. Twelve of the 47 revised hip replacements (25.5%) presented wear≥2mm.

DISCUSSION

Although functional results were acceptable for this elderly population, survival did not reach the NICE value and was lower than results in the literature for this type of implant. Cup loosening and wear were the main causes of revision.

LEVEL OF EVIDENCE IV

retrospective.

Alternative bearings in total hip arthroplasty in the young patient

Total hip arthroplasty is an effective treatment option for advanced hip arthritis in elderly patients. Studies in young patients have traditionally shown less durable results. With current implants, surgical technique, and cementless fixation methods, the durability of total hip arthroplasty may now be related to the wear performance of the bearing surfaces. To improve implant longevity, there are several bearing surface choices currently available for this demanding group of patients. Alternatives must be evaluated in terms of the risks and benefits associated with each articulation, and all new technologies must be carefully monitored over the long term.

Charnley-Kerboull total hip arthroplasty combining zirconia on polyethylene. A minimum eight-year follow-up prospective study

PURPOSE

Zirconia was introduced in the 1980s for total hip arthroplasty (THA) with the expectation of lower polyethylene wear. The purpose of this prospective study was to evaluate the results of a continuous series of total hip arthroplasties combining a zirconia head with polyethylene socket at a minimum eight-year follow-up.

METHODS

We performed an open prospective clinical trial in 1997. Our study involved 51 consecutive patients (55 hips) with a mean age of 52.5 ± 12 years (range, 25-76 years). All patients had a Charnley-Kerboull all-cemented hip replacement. A 22-mm stabilised yttrium tetragonal polycrystalline zirconia head (Y-TZP) was used in association with moderately cross-linked and annealed polyethylene. Clinical and radiological outcomes were assessed yearly. A survival analysis was performed using revision for any reason as the end-point.

RESULTS

At a minimum eight-year follow-up, 12 patients (13 hips) were lost to follow-up (mean 26.8 months), two patients (two hips) had died, and six patients (six hips) were revised. The remaining 31 patients (34 hips) were alive and had not been revised on either the femoral or acetabular side at a mean follow-up of 117.1 months (range, 96-150 months). Mean functional score at last follow-up was 17.7. Mean linear head penetration was 0.23 mm/year. More than 90% of the remaining hips had signs of periprosthetic osteolysis. Five stems were loosened. The survival at eight years was 87.3% (95% IC: 76.7-97.8).

CONCLUSION

This study confirms earlier short-terms results, and demonstrates that zirconia should no longer be used in THA.

Risk factors for revision of primary total hip arthroplasty: a systematic review

BACKGROUND

Numerous papers have been published examining risk factors for revision of primary total hip arthroplasty (THA), but there have been no comprehensive systematic literature reviews that summarize the most recent findings across a broad range of potential predictors.

METHODS

We performed a PubMed search for papers published between January, 2000 and November, 2010 that provided data on risk factors for revision of primary THA. We collected data on revision for any reason, as well as on revision for aseptic loosening, infection, or dislocation. For each risk factor that was examined in at least three papers, we summarize the number and direction of statistically significant associations reported.

RESULTS

Eighty-six papers were included in our review. Factors found to be associated with revision included younger age, greater comorbidity, a diagnosis of avascular necrosis (AVN) as compared to osteoarthritis (OA), low surgeon volume, and larger femoral head size. Male sex was associated with revision due to aseptic loosening and infection. Longer operating time was associated with revision due to infection. Smaller femoral head size was associated with revision due to dislocation.

CONCLUSIONS

This systematic review of literature published between 2000 and 2010 identified a range of demographic, clinical, surgical, implant, and provider variables associated with the risk of revision following primary THA. These findings can inform discussions between surgeons and patients relating to the risks and benefits of undergoing total hip arthroplasty.

Biomechanical concept and clinical outcome of dual mobility cups

Dual mobility cup systems in total hip arthroplasty consist of a metal back with a non-constrained liner, in which a constrained standard head articulates. While superior stability of such implants in comparison with standard total hip replacements is assumed, it is the purpose of this study to outline the biomechanical concept of dual mobility cups and to describe implant survival and dislocation rate based on the series published in the English-speaking and Francophone literature. A growing body of evidence indicates reduced dislocation rates in primary and revision total hip arthroplasty and in selected tumour cases. The limited availability of studies evaluating long-term implant survival and existing concerns with regard to increased wear rates and aseptic loosening, leads to the conclusion that such implants have to be used with prudence, particularly in standard primary hip arthroplasty and in young patients.

Bearing surface considerations for total hip arthroplasty in young patients

Bearing selection for total hip arthroplasty in young patients is important because of the likely long service life of the implant. Careful consideration of the next operation is recommended when choosing components. No prospective, randomized studies exist that document the clear superiority of any bearing couple in young, active patients. Modern metals, ceramics, and polyethylenes all hold promise. Further long-term data on modern bearings are needed to determine the clinical performance of these bearings. This article summarizes the available data on various bearing couples in patients aged younger than 50 years.

Modern total hip arthroplasty in patients younger than 21 years

Total hip arthroplasty (THA) is not commonly performed in adolescents. However, it may be the only option for pain control with continued mobility for advanced disease. We report our experience with modern alternative-bearing THA in patients younger than 21 years. Twenty-one THAs (18 patients) were followed. Preoperative and postoperative Harris hip scores were recorded, and radiographs were reviewed. Average follow-up was 49 months (range, 25-89). Underlying etiology was chemotherapy-induced osteonecrosis (33%), steroid-induced osteonecrosis (29%), sickle cell disease (24%), and chronic dislocation (14%). Articulation bearings were ceramic/ceramic (67%), metal/highly cross-linked polyethylene (29%), and metal resurfacing (5%). Mean age was 18 years (range, 13-20). Harris hip scores improved from 43.6 to 83.6 (P < .001). At final follow-up, there was no radiographic loosening; 1 THA was revised for a cracked ceramic liner. At intermediate-term follow-up, clinical and radiographic results are favorable after alternative-bearing THA in patients younger than 21 years.

Total hip arthroplasties in young patients under 50 years: limited evidence for current trends. A descriptive literature review

We examined all reported outcomes of uncemented and cemented total hip arthroplasty in patients younger than 50 years of age listed in Medline (1966- 1 January 2009) and PubMed, and scrutinised reference lists of relevant papers. In addition, we evaluated relevant data in the Swedish hip arthroplasty register. 109 relevant articles were identified, 37 of which had a mean follow-up longer than 10 years. Although uncemented implants are widely used in patients under 50 years of age, there are only 2 reports that fulfil the criteria published by the National Institute for Clinical Excellence (NICE) in the United Kingdom (follow-up of >10 yrs and survival of =90%). Current trends relating to implant selection remain unsupported by survival data, and additional information about the long-term results of newer implants is essential. As matters stand, the most reliable results relate to cemented implants.

Risk factors for revision of hip arthroplasties in patients younger than 30 years

BACKGROUND

Numerous reports of THAs in patients younger than 30 years indicate a high risk of revision. Although risk factors for revision have been reported for older patients, it is unclear whether these risk factors are the same as those for patients younger than 30 years.

QUESTIONS/PURPOSES

We therefore (1) determined function and survivorship of revision THAs performed in patients younger than 30 years, and (2) assessed the risk factors for revision THAs in this younger population by comparison with a group of patients younger than 30 years who did not undergo revision.

PATIENTS AND METHODS

We retrospectively reviewed the clinical records and radiographs of 55 patients younger than 30 years (average age at revision, 24.3 years; range, 14-30 years) who underwent 77 hip revisions. Revision was performed, on average, 4.6 years (range, 0.4-12 years) after the primary THA. The results for these 55 patients (77 revision THAs) were compared with results for a nonrevised group, including 819 THAs in patients younger than 30 years. Minimum followup of the revision group was 1 year (mean, 6.2 years; range, 1-15 years).

RESULTS

At followup after the revision, the Merle d'Aubigné-Postel score improved from 12.2 to 14.6. The rates of dislocation, neurologic lesions, and fractures were 15%, 7.8%, and 14%, respectively. The 10-year survival rate was 36% (95% confidence interval [CI], 21%-51%). Compared with the nonrevised group, the independent revision risk factors were young age at primary THA (OR 1.14 [1.07-1.19]), high number of previous surgeries (OR 5.41 [2.67-10.98]), and occurrence of at least one dislocation (OR 3.98 [1.74-9.07]). Hard-on-soft bearings had a higher risk (OR 3.42 [1.91-6.1]) of revision compared with hard-on-hard bearings.

CONCLUSIONS

Revision THAs are likely in patients younger than 30 years, and the complication rate is high. The survivorship of hip revision in this population is low and alternative solutions should be advocated whenever possible.

LEVEL OF EVIDENCE

Level III, therapeutic study, case control study. See the Guidelines for Authors for a complete description of levels of evidence.

Treatment of femoral neck fractures in elderly patients over 60 years of age - which is the ideal modality of primary joint replacement?

BACKGROUND

Femoral neck fractures in the elderly are frequent, represent a great health care problem, and have a significant impact on health insurance costs. Reconstruction options using hip arthroplasty include unipolar or bipolar hemiarthroplasty (HA), and total hip arthroplasty (THA). The purpose of this review is to discuss the indications, limitations, and pitfalls of each of these techniques.

METHODS

The Pubmed database was searched for all articles on femoral neck fracture and for the reconstruction options presented in this review using the search terms "femoral neck fracture", "unipolar hemiarthroplasty", "bipolar hemiarthroplasty", and "total hip arthroplasty". In addition, cross-referencing was used to cover articles eventually undetected by the respective search strategies. The resulting articles were then reviewed with regard to the different techniques, outcome and complications of the distinct reconstruction options.

RESULTS

THA yields the best functional results in patients with displaced femoral neck fractures with complication rates comparable to HA. THA is beneficially implanted using an anterior approach exploiting the internervous plane between the tensor fasciae latae and the sartorius muscles allowing for immediate full weight-bearing. Based on our findings, bipolar hemiarthroplasty, similar to unipolar hemiarthroplasty, cannot restorate neither anatomical nor biomechanical features of the hip joint. Therefore, it can only be recommended as a second line of defense-procedure for patients with low functional demands and limited live expectancy.

CONCLUSIONS

THA is the treatment of choice for femoral neck fractures in patients older than 60 years. HA should only be implanted in patients with limited life expectancy.

Total hip arthroplasty in inflammatory arthritis in patients under 35 years. A 7 to 19 year follow-up

Total hip arthroplasty in patients with inflammatory arthritis is compromised by the young age of patients at presentation, intake of non-steroidal anti-inflammatory drugs, steroid use and autoimmune diseases which negatively affect bone quality. This study evaluates the survival of total hip arthroplasties (THA) in 32 patients with inflammatory hip disease who were under the age of 35 at the index operation and on which 57 primary total hip arthroplasties were performed between 1989 and 2001. Polished straight tapered cemented stems were used in all 57 hips. There were 10 cemented and 47 uncemented cups. The average follow-up was 12.2 years (range 7-19). Forty-seven hips had more than 10 years follow-up. There were 3 revisions of cemented metal-backed cups for aseptic loosening at 11, 13 and 16 years post-operatively. No uncemented cups and no stems needed revision. Heterotopic ossifications occured in 3 hips with Brooker type-I ossification in 1 hip and Brooker type-II in 2 hips. Cemented polished tapered straight stems demonstrate excellent survival in young patients suffering from inflammatory arthritis.

Dual mobility hip arthroplasty wear measurement: Experimental accuracy assessment using radiostereometric analysis (RSA)

INTRODUCTION

The use of dual mobility cups is an effective method to prevent dislocations. However, the specific design of these implants can raise the suspicion of increased wear and subsequent periprosthetic osteolysis.

HYPOTHESIS

Using radiostereometric analysis (RSA), migration of the femoral head inside the cup of a dual mobility implant can be defined to apprehend polyethylene wear rate.

STUDY OBJECTIVES

The study aimed to establish the precision of RSA measurement of femoral head migration in the cup of a dual mobility implant, and its intra- and interobserver variability.

MATERIAL AND METHODS

A total hip prosthesis phantom was implanted and placed under weight loading conditions in a simulator. Model-based RSA measurement of implant penetration involved specially machined polyethylene liners with increasing concentric wear (no wear, then 0.25, 0.5 and 0.75mm). Three examiners, blinded to the level of wear, analyzed (10 times) the radiostereometric films of the four liners. There was one experienced, one trained, and one inexperienced examiner. Statistical analysis measured the accuracy, precision, and intra- and interobserver variability by calculating Root Mean Square Error (RMSE), Concordance Correlation Coefficient (CCC), Intra Class correlation Coefficient (ICC), and Bland-Altman plots.

RESULTS

Our protocol, that used a simple geometric model rather than the manufacturer's CAD files, showed precision of 0.072mm and accuracy of 0.034mm, comparable with machining tolerances with low variability. Correlation between wear measurement and true value was excellent with a CCC of 0.9772. Intraobserver reproducibility was very good with an ICC of 0.9856, 0.9883 and 0.9842, respectively for examiners 1, 2 and 3. Interobserver reproducibility was excellent with a CCC of 0.9818 between examiners 2 and 1, and 0.9713 between examiners 3 and 1.

DISCUSSION

Quantification of wear is indispensable for the surveillance of dual mobility implants. This in vitro study validates our measurement method. Our results, and comparison with other studies using different measurement technologies (RSA, standard radiographs, Martell method) make model-based RSA the reference method for measuring the wear of total hip prostheses in vivo.

LEVEL OF EVIDENCE

Level 3. Prospective diagnostic study.

Hip resurfacing and osteonecrosis: results from an independent hip resurfacing register

INTRODUCTION

Single surgeon studies from specialized centers have suggested that metal-on-metal hip resurfacing in patients with osteonecrosis of hip joint provides good implant survival and function.

METHOD

We tested the hypothesis that multicenter results of hip resurfacing, in terms of function and survival, are similar between patients with osteoarthritis and osteonecrosis.

PATIENTS

192 patients (202 hips) underwent metal-on-metal hip resurfacing at different centers around the world. We compared the revision risks in 95 patients (101 hips) with osteonecrosis and 97 patients (101 hips) with osteoarthritis.

RESULTS

The mean age at operation was 42 and 43 years and the preoperative and postoperative Harris hip scores were 62 and 96 and 58 and 95 for osteonecrosis and osteoarthritis groups. Survival with revision for any reason as the end point at last follow-up was 97.7% for osteonecrosis and 95.0% for osteoarthritis.

CONCLUSION

We conclude that hip resurfacing can be offered to patients with osteonecrosis.

The posterior approach reduces the risk of thin cement mantles with a straight femoral stem design

BACKGROUND AND PURPOSE

The properties of the cement mantle around a prosthesis are important. We investigated whether the surgical approach to the hip influences the quality and thickness of the cement mantle when using a straight femoral stem design.

METHODS

In a consecutive multi-surgeon series, we reviewed the radiographs of 270 patients after cemented Exeter total hip arthroplasty. 135 stems were introduced using an antero-lateral (transgluteal) approach and 135 stems were introduced using a posterior approach. Anterior-posterior and lateral radiographs were reviewed and cement mantle thickness was measured in Gruen zones 1-14. We graded cement mantle quality according to the Barrack classification.

RESULTS

Barrack grading did not reveal any difference in cement mantle quality between the two groups. AP and lateral radiographs showed no difference in stem alignment between the groups. The risk of a thin cement mantle (< 2 mm) was lower with a posterior approach (OR = 1.8, 95% CI: 1-3; p = 0.03). The greatest risk of a cement mantle thickness of < 2 mm occurred in Gruen zones 8-9 regardless of the surgical approach used.

INTERPRETATION

With a straight femoral stem design, the posterior approach to the hip joint appears to give a lower risk of a thin cement mantle. Irrespective of the approach, there was a risk of thin cement mantles in Gruen zones 8 and 9, which highlights the importance of lateral radiographs in the postoperative radiographic assessment of total hip replacements.

Good results with cemented total hip arthroplasty in patients between 40 and 50 years of age

BACKGROUND AND PURPOSE

Total hip arthroplasties in young patients have lower long-term survival rates than in older patients. We evaluated the use of a unique treatment protocol in patients aged between 40 and 50 years. In all cases we used a cemented THA, and for acetabular deficiencies we also used impacted bone grafts together with a cemented cup.

METHODS

In 140 consecutive patients who were between 40 and 50 years of age at index surgery, 168 cemented total hip prostheses were evaluated after a mean follow-up time of 10 (2-19) years. Acetabular deficiencies were reconstructed with wire meshes and impacted bone grafts with a cemented cup (70 hips). During follow-up, 18 patients died (27 hips); in this group 3 hips (3 patients) had been revised. None of the patients were lost to follow-up. In all surviving patients, clinical assessment was performed with hip-score questions and all radiographs were evaluated.

RESULTS

All clinical questionnaires showed an improved clinical hip score. 29 hips (17%) were revised after a mean of 8 (0.3-18) years. Kaplan-Meier survival analysis showed a survival of 88% (95% CI: 82-94) after 10 years with revision of either component for any reason. Survival with endpoint revision for aseptic loosening of either component was 94% (95% CI: 90-99) after 10 years.

INTERPRETATION

Cemented implants in young patients have satisfying long-term results. Reconstruction of acetabular deficiencies with impacted bone grafts show promising results.

Is the so-called 'French paradox' a reality?: long-term survival and migration of the Charnley-Kerboull stem cemented line-to-line

We have evaluated the in vivo migration patterns of 164 primary consecutive Charnley-Kerboull total hip replacements which were undertaken in 155 patients. The femoral preparation included removal of diaphyseal cancellous bone to obtain primary rotational stability of the stem before line-to-line cementing. We used the Ein Bild Roentgen Analyse femoral component method to assess the subsidence of the femoral component. At a mean of 17.3 years (15.1 to 18.3) 73 patients were still alive and had not been revised, eight had been revised, 66 had died and eight had been lost to follow-up. The mean subsidence of the entire series was 0.63 mm (0.0 to 1.94). When using a 1.5 mm threshold, only four stems were considered to have subsided. Our study showed that, in most cases, a highly polished double-tapered stem cemented line-to-line does not subside at least up to 18 years after implantation.

Anatomic stem design reduces risk of thin cement mantles in primary hip replacement

PURPOSE

To analyse the influence of femoral stem design in the lateral plane (anatomic vs. straight) on the cement mantle quality.

METHOD

In this consecutive multi-surgeon radiographic study we determined, Dorr grading, cement mantle quality (Barrack) and mantle thickness using Gruen zones 1–14 in 280 primary cemented total hip replacements, divided into two groups (140 anatomic Biomet Olympia, 140 straight Exeter Universal Series).

RESULTS

Twenty-three per cent of the straight Exeter Universal stems had a cement mantle of <2 mm thickness in Gruen zone 8 and 25% in Gruen zone 9, compared to 0.7% of the anatomical Olympia stems in Gruen zone 8 and 1.4% in Gruen zone 9. The difference between the two groups was statistically significant (P < 0.001). In all other zones no significant differences were found.

CONCLUSION

This radiological study confirms that femoral stems with an anatomical curve in the lateral plane carry a lower risk of thin cement mantles (especially in Gruen zones 8 and 9) than straight stems. Cement mantle analysis in one radiographic plane only is insufficient.

A review of the biologic effects of spine implant debris: Fact from fiction

BACKGROUND

Biologic-reactivity to implant-debris is the primary determinant of long-term clinical performance. The following reviews: 1) the physical aspects of spinal-implant debris and 2) the local and systemic biologic responses to implant debris.

METHODS

Methods included are: 1) gravimetric wear analysis; 2) SEM and LALLS; 3) metal-ion analysis; 4) ELISA, toxicity testing, patch testing; and 5) metal-lymphocyte transformation testing (metal-LTT).

RESULTS

Wear and corrosion of spine-implants produce particles and ions. Particles (0.01-1000 μm) are generally submicron ( <1 µm). Wear rates of metal-on-polymer and metal-on-metal disc arthroplasties are approximately 2-20 and 1 mm(3)/yr, respectively. Metal-on-metal total disc replacement components have significant increases in circulating metal (less than 10-fold that of controls at 4 ppb-Co and 3 ppb-Cr or ng/mL). Debris reactivity is local and systemic. Local inflammation is caused primarily by ingestion of debris by local macrophages, which produce pro-inflammatory cytokines TNFα, IL-1β, IL-6, and PGE2. Systemic responses associated with implant-debris have been limited to hypersensitivity reactions. Elevated amounts of in the liver, spleen, etc of patients with failed TJA have not been associated with remote toxicological or carcinogenic pathology to date. Implant debris are differentially bioreactive. Greater numbers are pro-inflammatory; the smaller-sized debris are more bioreactive by virtue of their greater numbers (dose) for a given amount of implant mass loss (one 100-μm-diameter particle is equivalent in mass to 1 million 1-μm-diameter particles). Elongated particles are pro-inflammatory (ie, aspect ratio of greater than 3). Metal particles are more proinflammatory than polymers, ceteris paribus.

CONCLUSION

Spinal arthroplasty designs have been in use for more than 20 years internationally; therefore, concerns about neuropathology, toxicity, and carcinogenicity are mitigated. Debris-induced inflammation still depends on the individual and the type of debris. The consequence of debris-induced inflammation is continued; vigilance by physicians is recommended monitoring of spinal implants using physical exams and testing of metal content and bioreactivity, as is planning for the likelihood of revision in younger individuals.

Similar survival of eccentric rotational acetabular osteotomy in patients younger and older than 50 years

Pelvic osteotomy for middle-aged patients with hip dysplasia remains controversial. We asked whether pelvic osteotomy would yield lower Harris hip scores and survivorship in older patients than in younger patients. We compared patients younger than 50 years (n = 123) with patients 50 years or older (n = 41). At last followup, the mean Harris hip scores improved similarly in both groups: from 60 to 89 points in the older group and from 63 to 92 points in the younger group. However, in patients with bilateral surgery, the older group tended to have lower mean scores than the younger group (86 versus 93 points, respectively). Fifteen-year survivorship with a Harris hip score less than 80 points as the end point was similar in the two groups (71% in older patients and 81% in younger patients). In patients with bilateral surgery, the 15-year survivorship was lower in the older group (66% in older patients and 83% in younger patients). The data suggest eccentric rotational osteotomy for older patients can provide lasting function in most patients. However, prudent selection of patients is required for older patients with bilateral osteoarthritis.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Finite element analysis of the effect of cementing concepts on implant stability and cement fatigue failure

BACKGROUND AND PURPOSE

Two contradictory cementing techniques (using an undersized stem versus a canal-filling stem) can both lead to excellent survival rates, a phenomenon known as the "French paradox". Furthermore, previous studies have indicated that the type of bone supporting the cement mantle may affect implant survival. To further evaluate the mechanical consequences of variations in cementing technique, we studied the effect of implant size and type of bone supporting the cement mantle on the mechanical performance of cemented total hip arthroplasty, using finite element analysis.

METHODS

In a generic 2-dimensional plane-strain finite element model of a transverse section of a cemented total hip arthroplasty with a Charnley-Kerboull stem, we varied implant size and type of bone supporting the cement mantle. The models were subjected to 2 x 106 cycles of an alternating loading pattern of torque and a transverse load. During this loading history, we simulated cement fatigue crack formation and tracked rotational stability of the implant.

RESULTS

Canal-filling stems produced fewer cement cracks and less rotation than undersized stems. Cement mantles surrounded by trabecular bone produced more cement cracks and implant rotation than cement mantles surrounded by cortical bone.

INTERPRETATION

Our investigation provides a possible explanation for the good clinical results obtained with canal-filling Charnley-Kerboull implants. Our findings also indicate that inferior mechanical properties are obtained with these implants if the cement is supported by trabecular bone, which may be minimized by an optimal cementing technique.

Impaction grafting in association with the Charnley-Kerboull cemented femoral component

We describe 129 consecutive revision total hip replacements using a Charnley-Kerboull femoral component of standard length with impaction allografting. The mean follow-up was 8.2 years (2 to 16). Additionally, extramedullary reinforcement was performed using struts of cortical allograft in 49 hips and cerclage wires in 30.

There was one intra-operative fracture of the femur but none later. Two femoral components subsided by 5 mm and 8 mm respectively, and were considered to be radiological failures. No further revision of a femoral component was required. The rate of survival of the femoral component at nine years, using radiological failure as the endpoint, was 98%. Our study showed that impaction grafting in association with a Charnley-Kerboull femoral component has a low rate of subsidence. Reconstruction of deficiencies of distal bone with struts of cortical allograft appeared to be an efficient way of preventing postoperative femoral fracture for up to 16 years.

Fixation of the cemented stem: clinical relevance of the porosity and thickness of the cement mantle

The aim of this review paper is to define the fixation of the cemented stem. Polymethyl methacrylate, otherwise known as “bone cement”, has been used in the fixation of hip implants since the early 1960s. Sir John Charnley, the pioneer of modern hip replacement, incorporated the use of cement in the development of low frictional torque hip arthroplasty. In this paper, the concepts of femoral stem design and fixation, clinical results, and advances in understanding of the optimal use of cement are reviewed. The purpose of this paper is to help understanding and discussions on the thickness and the porosity of the cement mantle in total hip arthroplasty. Cement does not act as an adhesive, as sometimes thought, but relies on an interlocking fit to provide mechanical stability at the cement–bone interface, while at the prosthesis– cement interface it achieves stability by optimizing the fit of the implant in the cement mantle, such as in a tapered femoral stem.