DePuy International Research Articles

Clinical, Functional, and Midterm Survival Analysis on Sigma Curved Plus Ultracongruent Polyethylene Insert in Primary Total Knee Arthroplasty: A Retrospective Study.

Background: Posterior-stabilized (PS) total knee arthroplasty (TKA) poses problems such as the need for intercondylar notch bone resection as well as cam and post wear and patella clunk. Owing to its heightened anterior profile, an ultracongruent polyethylene insert prevents the excessive posterior translation of tibia in the case of a deficient or scarified posterior cruciate ligament (PCL). This study aimed to determine whether an ultracongruent insert provides satisfactory clinical and functional outcomes and midterm survival benefits.Methods: Based on the reviewed medical records of 200 patients, 240 primary TKA cases involving the use of Sigma Curved Plus (DePuy International, Ltd., Leeds, UK) ultracongruent insert were retrospectively enrolled in this study. Follow-up data were used to evaluate the clinical and radiological outcomes and to conduct a Kaplan-Meier survival analysis.Results: The mean follow-up duration for 224 knees was 5.8 years (range 5-6.5 years). A revision was made due to infection in two patients and due to periprosthetic fractures in two other patients. The mean knee flexion improved from 101.97° ± 9.43° (range 85°-125°) to 125.75° ± 9.58° (range 100°-140°) at the final follow-up. The mean Knee Society score improved from 43.1 ± 9.76 to 88.3 ± 3.2, and the function score improved from 44.95 ± 7.26 to 90.16 ± 3.71. None of the patients showed radiographic loosening of either insert component, but 22 (5%) patients showed radiolucent lines (<2 mm). The Kaplan-Meier analysis showed that the five-year survival of the insert with an endpoint of revision for any reason was 98.1% (confidence interval, CI, 95.7-99.6%).Conclusion: The Sigma Curved Plus insert showed a low failure rate with good clinical, functional, and midterm survival outcomes in comparison to standard outcomes reported in earlier studies. Further follow-up studies are warranted to determine whether the insert’s performance is maintained in the long term.

Periprosthetic fracture morphology of a femoral neck prosthesis: An in vitro study.

Femoral neck prostheses have been developed for the treatment of osteoarthritis in young and active patients. The concept combines a bone-conserving and minimal invasive technique with proximal load transferring by metaphyseal anchoring, which results in a more physiological loading pattern. However, little is known about the morphology of periprosthetic fractures. Thus, the aim of this study was to describe fracture patterns and to determine patient-specific factors favoring periprosthetic fracture. This study was performed as a biomechanical experimental study using 10 fresh frozen femora and 10 Silent-Hip femoral neck implants (DePuy International Ltd., Leeds, UK). In order to simulate physiological loading, a static muscle reconstruction (abductor muscles and iliotibial band) and a dynamic simulation of the gait cycle were applied. During biomechanical testing (50% and 100% of normal weight-bearing), three periprosthetic fractures with two different morphologies occurred. The first pattern corresponds to an abrupt breakaway. The second type was of spiral configuration extending to the diaphyseal region and emerging from an initial fissure. Specimen-specific factors favoring periprosthetic fracture were body mass index and varus angle of the implant. Periprosthetic fractures may extend to the subtrochanteric/diaphyseal region and may be of spiral configuration. According to the finding of this study, body mass index and varus/valgus position of the implant are important factors influencing the risk of periprosthetic fractures. Furthermore, partial weight-bearing as part of the postoperative regimen may be favorable.

A prospective evaluation of a largely cementless total knee arthroplasty cohort without patellar resurfacing: 10-year outcomes and survivorship

BackgroundThe theoretical benefits of a mobile bearing design in Total Knee Arthroplasty (TKA) include increased articular surface conformity with a reduction in both polyethylene wear and implant interface shear. However, to date these theoretical advantages have not been translated into published evidence of superior survivorship. This paper presents the results of a prospective, non-comparative study evaluating the performance of the mobile bearing Low Contact Stress LCS Complete Rotating Platform TKA in a largely cementless cohort without patellar resurfacing.Methods237 consecutive patients (240 knees) undergoing primary TKA were prospectively recruited. All received the LCS Complete Rotating Platform TKA (DePuy International, Leeds, UK). Clinical and radiographic assessments were performed at 3, 12, 60 and 120 months post-operatively. Radiographic evaluation was performed by an independent external surgeon.ResultsThe mean age was 70.3 years. 77.5% of cases were cementless. Radiographic assessment suggested excellent femoral component fixation. 22 tibial radiolucent lines (RLLs) > 1 mm were observed in 12 knees. No RLLs were progressive. There have been two revisions; one for late infection and one for aseptic loosening. No patients underwent secondary patellar resurfacing. The cumulative implant survivorship, using component revision for any reason as the endpoint, was 98.9% (95% CI, 95.6 to 99.7%) at 10 years.ConclusionsThe excellent survivorship at a minimum 10-year follow-up supports the use of uncemented porous coated fixation without patellar resurfacing with the non-posterior stabilized LCS Complete Rotating Platform TKA.

Femoral offset found not to affect metal ion levels in metal-on-metal total hip arthroplasty.

Failure to restore femoral offset in metal on polyethylene total hip arthroplasty (THA) causes polyethylene wear and aseptic loosening. To our knowledge, no study to date has investigated the relationship between femoral offset and wear in metal-on-metal (MOM) THA. In this study, we investigated the relationship between femoral offset and wear by measuring circulating metal ion levels in MOM THA. In this retrospective study, we identified patients who had undergone MOM THA with the ASR XL system (DePuy International Ltd., Leeds, UK). Femoral offset was measured using anteroposterior radiographs, and circulating metal ion levels (cobalt and chromium) were recorded. In total, 95 patients were included (68 males and 27 females). The mean age at the time of surgery was 64.9. Mean time from surgery to blood sampling was 15.4months. No statistically significant relationship was found between femoral offset and cobalt (p = 0.313) or chromium (p = 0.401) ions. It is known that failure to restore femoral offset during THA can lead to high rates of wear in metal-on-polyethylene articulations. In our study, no statistically significant relationship was found between femoral offset and serum cobalt or chromium ions. This study adds to the information available to surgeons regarding factors that increase wear in metal-on-metal total hip arthroplasty.

ONE STEP FORWARD AND TWO STEPS BACK IN PRODUCT LIABILITY: THE SEARCH FOR CLARITY IN THE IDENTIFICATION OF DEFECTS

PRODUCT liability law has struggled to develop a test for identifying when products are defective under the Consumer Protection Act 1987 (“CPA”). In Wilkes v Depuy International Ltd. [2016] EWHC 3096 (QB), Hickinbottom J. offered the most prolonged reflection on product defect since A v National Blood Authority [2001] EWHC 446 (QB), and rejected much of the framework of NBA. However, Wilkes provides little guidance regarding when products should be identified as being defective, reinforcing the need for a more deeply grounded approach.

Product liability in prosthetics

The Consumer Protection Act (1987) (CPA) makes a producer strictly liable for personal injury, death or damage caused by a defective product. Although fault is not a requirement, the consumer (patient) must prove the defect, the injury and a causal link between them. This was tested in the medical field in the case of A vs National Blood Authority (NBA) in 2001.1 A total of 117 claimants brought an action for damages under the Act arising from their infection with hepatitis C as a result of blood transfusions received after March 1988. It was claimed that the infected blood was a “defective” product within the meaning of the Act and that they were entitled to receive blood that was free from infection. The NBA argued that as there was no test for hepatitis C until April 1991, the presence of the virus in the blood could not have been expected to be detected before that time. The court found in favour of the claimants in what was perceived to be a harsh decision at the time. In an 82-page judgement, it was argued under the Act and the European Union product liability safety directive, that the blood products were defective and that the public was entitled to expect that transfused blood should be free of infection, even though there was no reasonable means that the NBA could have used to identify the infection. After this case, it was generally accepted that it was much easier for patients to prove that a product was defective, and more difficult for manufacturers to escape liability by showing that they had done all that could be expected of them. This brings us on to consideration of the case of Wilkes vs DePuy International Ltd,2 a matter in the field of orthopaedics that …

Comparative study of metacarpophalangeal joint arthroplasty effectiveness in patients with rheumatoid hand

Objective - to determine the optimal implant for metacarpophalangeal joint arthroplasty in patients with rheumatoid hand. Materials and methods. 24 patients with rheumatoid hand were operated in Vreden Russian Research Institute of Traumatology and Orthopedics (St.-Petersburg, Russia). 37 MCPJ arthroplasties were performed with 129 implants of 3 types. First group consisted of 11 patients with 43 implanted NeuFlex “DePuy International Ltd.” silicone implants on 12 hands. Second group - 6 patients with 26 implants Daphne “TECRES S.p.A.” on 7 hands. Third group - 16 patients with 60 implants RM Finger “MATHYS AG Bettlach” on 17 hands. Criteria for treatment effectiveness were estimated taking into account hand function, complications and also relapse of deformation. We compared movement amplitude in MCP joins, angle of ulnar drift, strength of hand and also subjective assessment by patients with DASH. Results were fixed before surgery and 3, 6 and 12 months after. Results. Complications were recorded in I and II of patient groupsin 50% of cases:fracturesof components, dislocations of construction, relapse of ulnar drift. Complications in III group of patients were not detected. Range of motion and function improvement were increased in all groups (p>0,05), as well as strength of hand. But the most stable growth of hand strength was fixed only in III group (p<0,05). Relapse of ulnar drift occurred in I group of patients. Conclusion. RM Finger “MATHYS AG Bettlach” is more reliable for metacarpophalangeal joint arthroplasty since it provides stable long-term results of treatment.

Fracture of a Cemented, Highly Polished, Collarless, Triple-Tapered, High-Nitrogen Stainless Steel Femoral Stem: A Case Report.

Early cemented forged stainless steel and casted cobalt-chromium femoral components were susceptible to gross material failure1-7. Proposed risk factors include type of implant, surgical technique, and patient variables1-16. Advances in implant materials and design as well as surgical and cementing techniques have rendered implant fracture increasingly rare8. Modern high-nitrogen stainless steel (HNSS) alloys, such as ORTRON 90 (DePuy International, Leeds, United Kingdom), which is used in the C-STEM (DePuy, Warsaw, Indiana), are mechanically superior to previously used stainless steel alloys17. Although HNSS femoral stems are weaker than forged cobalt-chromium stems, they are widely used because of excellent clinical results and a dramatically lower cost16. Fractures of both types of stems are extremely rare but have recently been reported in the literature10,16. To our knowledge, this is the second reported case of a stem fracture in a C-STEM, a collarless, triple-tapered, highly polished cemented HNSS femoral stem16. The patient was informed that data concerning the case would be submitted for publication, and he provided consent. A sixty-nine-year-old man presented to one of the senior authors (A.S.) with pain in the left hip and thigh. Eleven years prior to presentation, he had undergone left total hip arthroplasty with a Duraloc 100 series (DePuy) titanium cementless acetabular shell (60-mm outer diameter) with an Enduron (DePuy) polyethylene liner (28-mm inner diameter, neutral, +4 mm offset) and a cemented C-STEM (size 6) femoral stem with an Elite (DePuy) zirconia head (28 mm, standard offset). A cement restrictor as well as an end cap and centralizer for the C-STEM had been used (Fig. 1). The patient also had undergone right total hip arthroplasty with a similar prosthesis ten years prior to this presentation. He was 5′10′′ …

Nitric oxide‐dependent long‐term depression but not endocannabinoid‐mediated long‐term potentiation is crucial for visual recognition memory

Synaptic plasticity in perirhinal cortex is essential for recognition memory. Nitric oxide and endocannabinoids (eCBs), which are produced in the postsynaptic cell and act on the presynaptic terminal, are implicated in mechanisms of long-term potentiation (LTP) and long-term depression (LTD) in other brain regions. In this study, we examine these two retrograde signalling cascades in perirhinal cortex synaptic plasticity and in visual recognition memory in the rat. We show that inhibition of NO-dependent signalling prevented both carbachol- and activity (5 Hz)-dependent LTD but not activity (100 Hz theta burst)-dependent LTP in the rat perirhinal cortex in vitro. In contrast, inhibition of the eCB-dependent signalling prevented LTP but not the two forms of LTD in vitro. Local administration into perirhinal cortex of the nitric oxide synthase inhibitor NPA (2 μm) disrupted acquisition of long-term visual recognition memory. In contrast, AM251 (10 μm), a cannabinoid receptor 1 antagonist, did not impair visual recognition memory. The results of this study demonstrate dissociation between putative retrograde signalling mechanisms in LTD and LTP in perirhinal cortex. Thus, LTP relies on cannabinoid but not NO signalling, whilst LTD relies on NO- but not eCB-dependent signalling. Critically, these results also establish, for the first time, that NO- but not eCB-dependent signalling is important in perirhinal cortex-dependent visual recognition memory.

Failure analysis of cemented metal-on-metal total hip replacements from a single centre cohort

This paper presents the failure analysis of cemented metal on metal (MoM) total hip replacements (THR) from a single centre cohort. In this paper all retrieved femoral stems were implanted and revised at the Norfolk and Norwich University hospital by three specialist hip surgeons. All patients were subjected to the same combination of metallic implants, operative and follow up procedure. Between 1997 and 2008, 652 Ultima TPS™ femoral stems with the Ultima MoM articulation (DePuy International, Leeds) were implanted. At 2–9 years follow up, 90 revisions had been performed. Upon removal extensive fretting-corrosion of the cemented portions of the femoral stems was seen, resulting in high metal ion levels. In order to fully understand the factors resulting in failure of these cemented MoM THR optical light microscopy, Scanning Electron Microscopy with integrated Energy Dispersive X-ray spectroscopy (SEM/EDX) and X-ray Photo-electron spectroscopy (XPS) were utilised in order to assess the surface morphology and chemistry of retrieved MoM THR and surface chemistry of the films found on the surface. Gross slip, plastic deformation and directionality of the surface were extensively seen on the proximal surfaces of the retrievals. A more corrosive phenomenon was in the distal regions of the stem, demonstrating a seemingly inter-granular attack. SEM/EDX analysis demonstrated that black films present commonly seen on the highly worn regions of the cemented portions of the femoral stem were a complex mixture of chromium oxide, protein and amorphous carbon. XPS demonstrated films were Cr, O rich, mixed with organic material.

Influence of interface condition and implant design on bone remodelling and failure risk for the resurfaced femoral head

Resurfacing of the femur has experienced a revival, particularly in younger and more active patients. The implant is generally cemented onto the reamed trabecular bone and theoretical remodelling for this configuration, as well as uncemented variations, has been studied with relation to component positioning for the most common designs. The purpose of this study was to investigate the influence of different interface conditions, for alternative interior implant geometries, on bone strains in comparison to the native femur, and its consequent remodelling. A cylindrical interior geometry, two conical geometries and a spherical cortex-preserving design were compared with a standard implant (ASR, DePuy International, Ltd., UK), which has a 3° cone. Cemented as well as uncemented line to line and press-fit conditions were modelled for each geometry. A patient-specific finite element model of the proximal femur was used with simulated walking loads. Strain energy density was compared between the reference and resurfaced femur, and input into a remodelling algorithm to predict density changes post-operatively. The common cemented designs (cylindrical, slightly conical) had strain shielding in the superior femoral head (>35% reduction) as well as strain concentrations (strain>5%) in the neck regions near the implant rim. The cortex-preserving (spherical) and strongly conical designs showed less strain shielding. In contrast to the cemented implants, line to line implants showed a density decrease at the centre of the femoral head, while all press-fit versions showed a density increase (>100%) relative to the native femur, which suggests that uncemented press-fit implants could limit bone resorption.

Trunnion Fracture of the Anatomic Medullary Locking A Plus Femoral Component

Fracture of the neck of the femoral component after total hip arthroplasty is an infrequent complication. We present a report of 2 cases of trunnion fractures of fully porous-coated femoral stems (AML A Plus, DePuy International, Leeds, England), which had been implanted for 6 and 7 years after the index procedures. In both cases, failure emanated from a region where the trunnion had been intentionally grooved; and in both cases, the diameter of the trunnion was small, and evidence of corrosion contributing to the initiation of the failure was noted. Although this is the first report of trunnion fractures in this particular implant design, a close monitoring of prostheses with this specific trunnion should be considered. In addition, further analysis of clinical results and complications with this implant is warranted.

Inflammatory Pseudotumor Associated with Femoral Nerve Palsy Following Metal-on-Metal Resurfacing of the Hip

Metal-on-metal resurfacing arthroplasty of the hip has been used increasingly in Europe over the last ten years for the treatment of osteoarthritis of the hip in younger (<65 years of age), active patients. In 2005, 6,153 procedures were performed in England and Wales1. Marketing of the Birmingham hip replacement for resurfacing arthroplasty was approved by the United States Food and Drug Administration in May 2006. Metal-on-metal resurfacing of the hip is known to be associated with elevated concentrations of metal ions within the hip joint and systemically, but, to our knowledge as of this writing, no adverse effects of this process have been identified. However, the United Kingdom Medicines and Healthcare Products Regulatory Agency (MHRA) issued an alert in June 2007 about the Ultima metal-on-metal bearing total hip arthroplasty prosthesis (DePuy International, Leeds, United Kingdom) following reports of the need for early revision due to periprosthetic soft-tissue necrosis2. The bearing in question was a cobalt-chromium-molybdenum alloy similar to that used in the Birmingham hip replacement. We report the development of an ipsilateral mass associated with markedly elevated intralesional cobalt and chromium levels and a femoral nerve palsy in a patient who underwent a Birmingham metal-on-metal resurfacing arthroplasty of the hip one year previously. Our patient was informed that data concerning the case would be submitted for publication, and she consented. A sixty-three-year-old woman presented to another institution with painful idiopathic osteoarthrosis of the right hip. She had undergone a total abdominal hysterectomy, oophorectomy, and lysis of bowel adhesions five years previously but had no other contributory medical history. She underwent metal-on-metal resurfacing arthroplasty of the hip with the Birmingham hip replacement (Smith and Nephew Orthopaedics, Warwick, United Kingdom) in June 2005 (Fig. 1). The surgery and the early postoperative recovery were uncomplicated. Fig. 1 Pelvic radiograph made one …

Use of Carboxymethylcellulose/Polyethylene Oxide Gel in Microdiscectomy With Interlaminectomy

A consecutive, case series comparison. To compare safety, long-term pain, and disability scores with and without use of carboxymethylcellulose/polyethylene oxide (CMC/PEO) gel after microdiscectomy with interlaminectomy. Patient outcomes after microdiscectomy for lumbar disc herniation are frequently complicated by adhesions and fibrotic scars. Present management is controlled by good surgical technique as adhesion-reduction agents to date, have either proved ineffective or toxic. In 2002 a 100% synthetic combination of CMC/PEO, which reduces adhesions and fibrosis, became available across Europe as a gel application, (OXIPLEX/SP adhesion barrier gel FzioMed, Inc., San Luis Obispo, CA) and distributed under the trade names OXIPLEX/SP adhesion barrier gel (DePuy International, Ltd., Leeds, United Kingdom) and MEDISHIELD adhesion barrier gel (Medtronic International Trading SARL, Tolochenaz, Switzerland). A consecutive series of 70 patients with lumbar disc herniation undergoing microdiscectomy with interlaminectomy by the same surgeon were treated at the end of surgery with either CMC/PEO gel (N = 35) or no gel (N = 35). Treatments were allocated by an independent investigator. At presurgery and regular intervals over 3 years postsurgery, Oswestry disability index (ODI) and leg and back pain scores determined by visual analog scales (VAS), were assessed by a member of the surgical team blinded to the initial treatment allocation. Three years postsurgery reduction in disability as measured by the decrease in ODI compared with presurgery (mean +/- SD) was significantly (P < 0.05) greater with CMC/PEO than controls (-49.4 +/- 12.7 vs. -41 +/- 17.8). CMC/PEO treatment also resulted in significantly more patients having no disability as measured by reaching 0% ODI scores (15 CMC/PEO [43%] vs. 0 control group [0%]) (P < 0.01). Leg and back pain as measured by the decrease in VAS scores 3 years postsurgery were reduced with CMC/PEO compared with controls(leg -6.8 +/- 1.7 vs. -5.6 +/- 1.6, back -0.4 +/- 1.5 vs. -0.1 +/- 2.0), P < 0.05 for leg pain. Importantly there were no safety issues and no differences in complications between the 2 treatment groups during the 30 day postoperative period. CMC/PEO gel after microdiscectomy with interlaminectomy appears safe to use and in a 3-year follow-up significantly reduces disability and leg pain scores compared with our conventional treatment.

Prosthetic component relationship of the reverse Delta III total shoulder prosthesis in the transverse plane of the body

The Delta III (DePuy International Ltd, Leeds, UK) reverse total shoulder prosthesis has provided a successful functional outcome in cuff tear arthropathy (CTA); however, internal and external rotation remain compromised. Positioning of the prosthetic components in the transverse plane has theoretically been suggested to affect rotation. Twenty-seven patients who received a Delta III reversed total shoulder prosthesis for CTA were analyzed (mean follow-up, 43 months) using standard radiographs and computed tomography. The position of the prosthetic components and the possible influence of scapular rotation was analyzed using a uniform spatial reference system using axes in reference to the sagittal or coronal plane. We assessed impingement of the humeral component on the glenoid neck in neutral and internal rotation. An increase in the anterior divergence of the glenoid and humeral prosthetic components correlates with an increase in radiologically measured internal rotation (r = 0.932, P < .001). The uniformity of the reference system used seems to allow accurate positioning of the components intraoperatively and can be useful for analysis of the prosthetic component relationship postoperatively.

Glenosphere Disengagement

Implant failure is a serious complication in reverse shoulder arthroplasty. We determined the incidence of glenosphere disengagement in a cohort of 479 reverse shoulder prostheses (468 Delta III [DePuy International Ltd, Leeds, UK], 11 Aequalis [Tornier, Grenoble, France]). We also determined whether disengagement adversely affected clinical outcomes. The minimum followup was 12 months (mean, 28.6 months; range, 12-72 months). Disengagement of the glenosphere occurred in 16 of 479 shoulders (3.2%). In 13 patients, the disengagement was partial (clear step-off between the baseplate and the glenosphere) and was not associated with a poor functional outcome with this short-term followup. In three patients, the disengagement led to a fracture of the central screw, leading to a complete disengagement of the glenosphere from the baseplate, necessitating revision in two; the third refused revision. Partial disengagement was seen in five of 11 Aequalis prostheses (45.4%) and eight of 468 Delta III prostheses (1.7%). The three total disengagements with central screw breakage all occurred in Delta III prostheses. We believe differences in the type of locking screws may explain the differences observed between the two types of reverse prostheses. Level III, retrospective study. See the Guidelines for Authors for a complete description of levels of evidence.

Erratum: Tibiofemoral force following total knee arthroplasty: Comparison of four prosthesis designs in vitro

AbstractThe authors have inadvertently left out several acknowledgments and wish to add them hereThis study was supported by DePuy International, the University of Western Australia, the Fremantle Hospital, and Mrs. Huggler.We would like to thank Dr. Hilaire Jacob for his help with the development of the mini‐force platform.We would also like to thank the Australian Orthopaedic Association (AOA) for the financial support of Dr. Jeffcote.

The premature failure of the Charnley Elite-Plus stem

The Journal of Bone and Joint Surgery. British volumeVol. 88-B, No. 12 CorrespondenceFree AccessThe premature failure of the Charnley Elite-Plus stemG. H. ISAACG. H. ISAACSenior Engineering FellowSearch for more papers by this authorPublished Online:1 Dec 2006https://doi.org/10.1302/0301-620X.88B12.18855AboutSectionsPDF/EPUB ToolsDownload CitationsTrack CitationsPermissionsAdd to Favourites ShareShare onFacebookTwitterLinked InRedditEmail Sir,I read with interest the article by Hauptfleisch et al.1 DePuy International Ltd has to date not commented on the data presented by the authors, in various publications, on the performance of the Elite-Plus system. However, we consider that the publication of the above paper requires a response because firstly, the conclusions may cause unnecessary concern to surgeons who have used the Elite-Plus system and the many thousands of patients who have been the recipients of this device. Secondly, information pertinent to the conclusions of this paper was omitted by the authors in the original publication.The results presented in the above publication were derived from a research study which was designed by the Oxford group and grant-funded by DePuy International Ltd. The outcome of this RSA-like study was followed closely. The results were openly shared and discussed between our research groups. When the two-year follow-up data became available, this was reviewed. It appeared that the posterior migration/rotation of the Elite-Plus stems was greater than that of the comparator system. An examination of the data showed that the difference in posterior migration was not a normal distribution and that four outliers were the principle cause of the difference. If these were excluded then the two cohorts had similar levels of posterior migration. In an attempt to explain these differences a representative of DePuy (GHI), who had no prior access to the outcome data for individual patients, was invited to review 14 sets of Elite-Plus radiographs from the study. A number of factors were reviewed, including stem position, orientation, cement mantle thickness, and cement mantle quality.A notable observation was that nine of ten patients in the stable group were registered as having a good cement mantle (as opposed to satisfactory), whilst only one of four was recorded in the unstable group. A further observation was that three patients were identified as having inadequate proximomedial cement support (“virtually no cement mantle”, “very little cement”, and “low neck resection”). When these patients were matched with the RSA data it was found that they were contained within the group of four that had higher than average posterior migration. These observations (together with others) on the appearance of the cement mantle were communicated, verbally and in writing, to the authors who concluded “none of your measurements have a significant relationship to posterior head migration”. A further communication was sent to the authors highlighting the relevant observations and concluding, “whilst not proven, these small numbers hint that the quality of the cement mantle may be a factor which influences stability”, and that the majority of stems with high posterior movement had “radiographic features which would make instability more likely”. Further comments were sought, however,not only the current paper1 but also a previous publication on this study2 completely ignored these issues, and the relationship to radiographic appearance was not discussed.Given the radiographic appearance it is not entirely surprising that these high posterior migration components subsequently went on to fail. Furthermore, it reinforces the belief that the performance of cemented stems is as much dependent upon the quality of cementation as it is on stem design. References 1 Hauptfleisch J, Glyn-Jones S, Beard DJ, Gill HS, Murray DW. The premature failure of the Charnley Elite-Plus stem: a confirmation of RSA predictions. J Bone Joint Surg [Br] 2006;88-B:179–83. Link, Google Scholar2 Alfaro-Adrian J, Gill HS, Murray DW. Should total hip arthroplasty femoral components be designed to subside? A radiostereometric analysis study of the Charnley and Exeter stems. J Arthroplasty 2001;16:598–606. Crossref, Medline, ISI, Google ScholarFiguresReferencesRelatedDetails Vol. 88-B, No. 12 Metrics History Published online 1 December 2006 Published in print 1 December 2006 InformationCopyright © 2006, The British Editorial Society of Bone and Joint Surgery: All rights reservedPDF download

Complications associated with the use of a titanium tibial nail

Intramedullary nailing is the treatment of choice for unstable or displaced tibial fractures. Titanium nails have been advocated for their improved biocompatibility and biomechanical properties but concerns are held about increased complications. We present results of 225 tibial fractures in 221 patients (90% follow-up) treated with the ACE titanium tibial nail (DePuy International Limited, Leeds, UK) inserted between 1995 and 2003 in one hospital department, which show no increased complications compared with the published literature. Eighty-two percent of the patients were male with a median age of 33 years. The mechanism of injury was RTA (52%), Sport (22%) and other (26%). Forty-one percent of the fractures were open. The general complication rate represents the published literature whereas only 32% patients developed knee pain compared with the 40-57% previously reported. Median union time was unaffected by open injury, reaming or age. Ninety (43.3%) patients required re-operation of which 23 (11%) had a second re-operation. In total 43 (20.7%) nails were removed, without any complication as previously reported for this nail.

Preclinical Testing of Femoral Hip Components: An Experimental Investigation With Four Prostheses

Existing standards for the preclinical testing of femoral hip implants have been successful in the objective of guaranteeing the implant's fatigue strength. There is a need for an experimental test which could ensure prostheses were not susceptible to aseptic loosening. In this study we measure the relative movement between the prosthesis and the bone of four different cemented femoral component designs in in vitro tests. The aim is to determine if differences can be distinguished and whether the differences correlate with clinical performance. The four designs are the Charnley (DePuy International Ltd., UK), the Exeter (Stryker Osteonics Howmedica Corp., USA), the Lubinus SPII (Waldemar-Link GmbH, Germany), and the Miiller Curved (JRI Ltd, UK). Five tests were carried out for each femoral component type, giving a total of 20 tests, and their permanent relative displacement (termed migration) and recoverable (i.e., elastic) relative displacement (termed inducible displacement) monitored over one million loading cycles. Considerable variation occurred in the tests. Nonetheless, most femoral components migrated medially, posteriorly, and distally. Most also rotated into varus. Translations of the Charnley (64 microns) and Lubinus (67 microns) implants were less than the Müller (72 microns) and Exeter (94 microns) implants, but this difference is not statistically significant. Most of the femoral components had rapid early migration followed by slower steady-state migration. With regard to the steady state inducible displacements of the prostheses, those of the Charnley, Exeter, and Lubinus decreased or were stable with respect to time, whilst those of the Müller typically increased with respect to time. It is concluded that migration is not a suitable basis for in vitro comparison of prosthesis designs. However inducible displacement trends provide a clinically comparable performance ranking.