Is TKA femoral implant stability improved by pressure applied cement? a comparison of 2 cementing techniques.

BACKGROUND: The majority of knee endoprostheses are cemented. In an earlier study the effects of different cementing techniques on cement penetration were evaluated using a Sawbone model. In this study we used a human cadaver model to study the effect of different cementing techniques on relative motion between the implant and the femoral shaft component under dynamic loading. METHODS: Two different cementing techniques were tested in a group of 15 pairs of human fresh frozen legs. In one group a conventional cementation technique was used and, in another group, cementation was done using a pressurizing technique. Under dynamic loading that simulated real life conditions relative motion at the bone-implant interface were studied at 20 degrees and 50 degrees flexion. RESULTS: In both scenarios, the relative motion anterior was significantly increased by pressure application. Distally, it was the same with higher loads. No significant difference could be measured posteriorly at 20°. At 50° flexion, however, pressurization reduced the posterior relative motion significantly at each load level. CONCLUSION: The use of the pressurizer does not improve the overall fixation compared to an adequate manual cement application. The change depends on the loading, flexion angle and varies in its proportion in between the interface zones.

Transversal Malalignment and Proximal Involvement Play a Relevant Role in Unilateral Cerebral Palsy Regardless the Subtype.

Classification of gait disorders in cerebral palsy (CP) remains challenging. The Winters, Gage, and Hicks (WGH) is a commonly used classification system for unilateral CP regarding the gait patterns (lower limb kinematics) solely in the sagittal plane. Due to the high number of unclassified patients, this classification system might fail to depict all gait disorders accurately. As the information on trunk/pelvic movements, frontal and transverse planes, and kinetics are disregarded in WGH, 3D instrumented gait analysis (IGA) for further characterization is necessary. The objective of this study was a detailed analysis of patients with unilateral CP using IGA taking all planes/degrees of freedom into account including pelvic and trunk movements. A total of 89 individuals with unilateral CP matched the inclusion criteria and were classified by WGH. Subtype-specific differences were analyzed. The most remarkable findings, in addition to the established WGH subtype-specific deviations, were pelvic obliquity and pelvic retraction in all WGH types. Furthermore, the unclassified individuals showed altered hip rotation moments and pelvic retraction almost throughout the whole gait cycle. Transversal malalignment and proximal involvement are relevant in all individuals with unilateral CP. Further studies should focus on WGH type-specific rotational malalignment assessment (static vs. dynamic, femoral vs. tibial) including therapeutic effects and potential subtype-specific compensation mechanisms and/or tertiary deviations of the sound limb.

GMFCS Level-Specific Differences in Kinematics and Joint Moments of the Involved Side in Unilateral Cerebral Palsy.

A variety of gait pathologies is seen in cerebral palsy. Movement patterns between different levels of functional impairment may differ. The objective of this work was the evaluation of Gross Motor Function Classification System (GMFCS) level-specific movement disorders. A total of 89 individuals with unilateral cerebral palsy and no history of prior treatment were included and classified according to their functional impairment. GMFCS level-specific differences, kinematics and joint moments, exclusively of the involved side, were analyzed for all planes for all lower limb joints, including pelvic and trunk movements. GMFCS level I and level II individuals most relevantly showed equinus/reduced dorsiflexion moments, knee flexion/reduced knee extension moments, reduced hip extension moments with pronounced flexion, internal hip rotation and reduced hip abduction. Anterior pelvic tilt, obliquity and retraction were found. Individuals with GMFCS level II were characterized by an additional pronounced reduction in all extensor moments, pronounced rotational malalignment and reduced hip abduction. The most striking characteristics of GMFCS level II were excessive anterior pelvic/trunk tilt and excessive trunk obliquity. Pronounced reduction in extensor moments and excessive trunk lean are distinguishing features of GMFCS level II. These patients would benefit particularly from surgical treatment restoring pelvic symmetry and improving hip abductor leverage. Future studies exploring GMFCS level-specific compensation of the sound limb and GMFCS level-specific malalignment are of interest.

Femoral Head and Liner Exchange in Patients with Atraumatic Dislocation. Results of a Retrospective Study with 6 Years Follow-Up.

Background and Objectives: Femoral head and liner exchange is an established treatment for polyethylene wear but has had a more limited role in the treatment of other conditions including dislocation, because of concerns about an increased postoperative dislocation rate. Some authors have considered dislocation associated with polyethylene wear to be a contraindication for this procedure. Materials and Methods: Our retrospective review evaluated the outcome of head and liner exchange in a small consecutively operated heterogeneous cohort of 20 patients who presented with dislocation unrelated to trauma, component malposition or component loosening. Of this group, 12 had prior primary total hip arthroplasty, and 8 had prior revision total hip arthroplasty, and included 4 patients with prior revision for dislocation. Mean follow-up was 6 ± 3.5 years (range 1-145 months). Results: Kaplan-Meier analysis revealed a revision-free implant survival from any cause of 80% (confidence interval 95%:64.3-99.6%) at 5 years after head and liner exchange (index surgery). At final follow-up, 83.3% of patients (n = 10) with prior primary total hip arthroplasty and 62.5% of patients (n = 5) with prior revision total hip arthroplasty, had not required subsequent revision for any cause. None (0%) of the primary total hip arthroplasty group and 3 (38%) of the revision arthroplasty group had required revision for further dislocation. Of the eight revision arthroplasty patients, four had a prior revision for dislocation and three of these four patients required further revision for dislocation after index surgery. The fourth patient had no dislocation after index surgery. One additional patient who had prior revision surgery for femoral component fracture suffered dislocation after index surgery, but was successfully treated with closed reduction. Conclusions: In our study population, femoral head and liner exchange was an effective treatment option for patients with prior primary total hip arthroplasty and also for a highly select group of revision total arthroplasty patients with no prior history of dislocation. Femoral head and liner exchange does not appear to be a viable treatment option for patients who have had revision total arthroplasty after prior dislocations.

Primary Stability in Hip Revision Arthroplasty: Comparison of the Stability of Cementless Fixed Augments on a Modular Acetabular Cage System with and without Cranial Straps.

The goal of this study is to evaluate the primary stability of a cementless augment-and-modular-cage system with and without the addition of cranial straps in a standardized in vitro setting. As the surrogate parameter for the evaluation of primary stability, the measurement of relative motion between the implant components themselves and the bone will be used. Acetabular revision components with a trabecular titanium augment in combination with a large fourth-generation composite left hemipelvis were assembled. These constructs were divided into two groups with (S) and without cranial straps (nS). A total of 1000 cycles was applied at each of three load levels. Relative movements (RM) between the components were measured. Load levels display a significant effect on the amount of RM at all interfaces except between shell/augment. The group assignment appears to have an effect on RM due to significantly differing means at all interfaces. Between bone/shell RM increased as load increased. NS displayed significantly more RM than S. Between shell/augment RM remained constant as load increased. Between shell/cup S showed more RM than nS while both groups' RM increased with load. We conclude a significant increase of primary stability between the shell and the bone through the addition of cranial straps. Relative motion between components (shell/cup) increases through the addition of cranial straps. A clinical impact of this finding is uncertain and requires further investigation. Finally, the cementless fixation of the augment against the rim-portion of the shell appears stable and compares favorably to prior investigation of different fixation techniques.

Is Negative Pressure Wound Therapy with Instillation Suitable for the Treatment of Acute Periprosthetic Hip Joint Infection?

BACKGROUND: Periprosthetic joint infection (PJI) can be devastating for the patient and demanding for the surgeon. In acute PJI, attempts are made to retain the prosthesis by debridement of the infected tissue, targeted antibiotic therapy and an exchange of modular components with implant retention (DAIR). There has been sparse research with adjunctive negative pressure wound treatment with wound irrigation (NPWTI) on the treatment outcome. QUESTIONS/PURPOSES: The goal was to assess the efficacy of our protocol of DAIR with adjunctive NPWTI in acute PJI and to reduce the need for later additional DAIR and Irrigation and Debridement (I and D). PATIENTS AND METHODS: Our cohort of 30 patients (31 hips) with acute PJI was divided into two groups based on symptom presentation up to 6 weeks or >6 weeks from prior (index) surgery (acute early or acute late groups, respectively). All received DAIR with an exchange of modular components and NPWTI with polyhexanide instillation, with the goal of bacterial elimination and biofilm elimination. Postoperatively, the patients were followed up clinically and radiographically for a mean of 4.3 years. RESULTS: Of the 31 PJI hips, 19 were early acute and 12 were late acute. In total, 21 hips had no evidence of residual infection, 10 required further surgical revision: 1 due to dislocation and 9 due to infection. Of these nine, seven had a removal of all the components and two were treated with irrigation and debridement (I and D), with the demise of one patient from pneumonia shortly after the procedure. The Kaplan-Meier 60-month revision free implant survival from infection was 73.2% (CI: 58.9-91.0%) and at the final follow up, the mean Harris Hip Score (HHS) was 81.1 ± 11.8 and the mean WOMAC score was 33.3 ± 20.1. CONCLUSIONS: Our results are in line with those reported in prior studies. However, the utility of our protocol is inconclusive and needs further evaluation based on our small cohort and the lack of a control group. LEVEL OF EVIDENCE: IV.

Sialendoscopy and Sjogren's Disease: A Systematic Review.

OBJECTIVES/HYPOTHESIS: This study is a systematic review of the literature which seeks to estimate the expected treatment outcomes of a patient with Sjogren's syndrome (SS) undergoing therapeutic sialendoscopy. STUDY DESIGN: Systematic Review. METHODS: PubMed, Scopus, and Cochrane library databases were used to search for studies published as of August 2020 regarding the treatment outcomes of SS with sialendoscopy. The key search terms included "Sjogren's syndrome" and "sialendoscopy." Only studies in the English language involving more than one human patient were included. PRISMA guidelines were followed in study inclusion and data extraction. The primary outcome assessed was improvement in patient symptoms. RESULTS: Six studies met criteria and were analyzed in this review, including 125 patients undergoing sialendoscopy of parotid and/or submandibular glands as well as 25 controls. Of these patients, 90% were female with an age range of 18 to 79 years. There was significant diversity in outcome reporting tools. The outcomes of symptom improvement were pooled qualitatively based on improvement noted in each study. Outcomes were defined as partial improvement if the measured outcomes improved and complete improvement if measured outcomes resolved entirely. Despite the limited number of studies on this topic, this meta-analysis suggests that a similar study of therapeutic sialendoscopy could expect to provide at least temporary improvement of symptoms 90% to 99% of the time. CONCLUSIONS: This review provides support for the application of sialendoscopy in the treatment of SS salivary disease. Larger studies with consistent outcome reporting tools and control groups are needed to validate these results and provide a consistent therapy protocol. Laryngoscope, 131:1474-1481, 2021.

Hip Spacers with a Metal-on-Cement Articulation Did Not Show Significant Surface Alterations of the Metal Femoral Head in Two-Stage Revision for Periprosthetic Joint Infection.

Two-stage revision is considered the gold standard treatment for chronic periprosthetic joint infection (PJI). During the interim period, between explantation of the infected hip endoprosthesis and revision arthroplasty, individually formed articulating hip spacers made of polymethylmethacrylate (PMMA) bone cement can be used to provide better soft tissue preservation, local antibiotic release, and improved postoperative mobilization. If effective prevention from luxation is achieved, hip function and hence overall patient satisfaction is improved. Zirconium oxide particles inside conventional PMMA bone cement, however, are known to enhance third-body wear, which may cause alterations of the metal head in the articulating spacer and hence become a serious risk for the patient. Therefore, the aim of our study was to analyze whether the articular surface of cobalt-chrome (CoCr) femoral heads is significantly altered in the setting of a metal-on-cement articulation during the interim period of two-stage revision for PJI. We analyzed a consecutive series of 23 spacer cases and compared them with femoral heads from two series of conventional hip arthroplasty revisions with metal-on-polyethylene articulations and different time intervals in situ. To investigate metallic wear, the femoral heads were thoroughly examined, and their surface roughness was measured and analyzed. We found no significant differences between the two conventional hip arthroplasty groups, despite their very different times in situ. Furthermore, the individually different times in situ within the spacer group had no significant impact on surface roughness, either. Compared with the spacer group, the surface roughness of the metal femoral heads from both conventional hip arthroplasty groups were even higher. Within the spacer group, roughness parameters did not show significant differences regarding the five predefined locations on the metal head. We conclude that metal-on-cement articulations do not cause enhanced surface alterations of the metal femoral head and hence do not limit the application in articulating hip spacers in the setting of two-stage revision for PJI.

Comparison of the Primary Stability of Porous Tantalum and Titanium Acetabular Revision Constructs.

Adequate primary stability of the acetabular revision construct is necessary for long-term implant survival. The difference in primary stability between tantalum and titanium components is unclear. Six composite hemipelvises with an acetabular defect were implanted with a tantalum augment and cup, using cement fixation between cup and augment. Relative motion was measured at cup/bone, cup/augment and bone/augment interfaces at three load levels; the results were compared to the relative motion measured at the same interfaces of a titanium cup/augment construct of identical dimensions, also implanted into composite bone. The implants showed little relative motion at all load levels between the augment and cup. At the bone/augment and bone/cup interfaces the titanium implants showed less relative motion than tantalum at 30% load (p < 0.001), but more relative motion at 50% (p = n.s.) and 100% (p < 0001) load. The load did not have a significant effect at the augment/cup interface (p = 0.086); it did have a significant effect on relative motion of both implant materials at bone/cup and bone/augment interfaces (p < 0.001). All interfaces of both constructs displayed relative motion that should permit osseointegration. Tantalum, however, may provide a greater degree of primary stability at higher loads than titanium. The clinical implication is yet to be seen.

Comparison of Different Locking Mechanisms in Total Hip Arthroplasty: Relative Motion between Cup and Inlay.

The resulting inflammatory reaction to polyethylene (PE) wear debris, which may result in osteolysis, is still considered to be a main reason for aseptic loosening. In addition to the primary wear in hip joint replacements caused by head-insert articulation, relative motions between the PE liner and the metal cup may cause additional wear. In order to limit this motion, various locking mechanisms were used. We investigated three different locking mechanisms (Aesculap, DePuy, and Zimmer Biomet) to address the resulting relative motion between the acetabular cup and PE liner and the maximum disassembly force. A standardized setting with increasing load levels was used in combination with optically based three-dimensional measurements. In addition the maximum disassembly forces were evaluated according to the ASTM F1820-13 standard. Our data showed significant differences between the groups, with a maximum relative motion at the maximum load level (3.5 kN) of 86.5 ± 32.7 µm. The maximum axial disassembly force was 473.8 ± 94.6 N. The in vitro study showed that various locking mechanisms may influence cup-inlay stability.

Trimodal embolization of juvenile nasopharyngeal angiofibroma with intracranial extension.

OBJECTIVES/PURPOSE: 1. Understand three different techniques for embolization of juvenile nasal angiofibroma (JNA) and assess their combined efficacy. 2. Perform successful endoscopic intralesional embolization of highly vascular sinonasal neoplasms. METHODS: In this study, we present the case of a 10-year-old male patient diagnosed with juvenile nasal angiofibroma (JNA) who successfully underwent trimodal embolization and resection at a tertiary academic medical center after failed coil embolization in his home country. We examine the clinical details of the case and a review of pertinent literature. RESULTS: Preoperative embolization is common in the treatment of JNA, but there is little consensus as to the proper timeframe and techniques utilized. In our case, preoperative imaging revealed a vascular tumor with intracranial extension consistent with UPMC Stage V JNA. Diagnostic angiogram revealed significant arborization from the internal and external carotid systems. A trimodal embolization technique, utilizing transarterial, percutaneous, and direct endoscopic intralesional injection of n-Butyl Cyanoacrylate (n-BCA) was performed. A two-staged endoscopic and open resection was subsequently performed one week later with minimal blood loss. In our case, combining intralesional embolization with traditional transarterial techniques resulted in an improved operative field and a successful clinical result. CONCLUSION: Embolization of highly vascular sinonasal tumors with n-BCA is not limited to endovascular techniques, but can be safely combined with percutaneous and endoscopic intralesional embolization up to one week prior to surgical resection.

Titanium Acetabular Component Deformation under Cyclic Loading.

Acetabular cup deformation may affect liner/cup congruency, clearance and/or osseointegration. It is unclear, whether deformation of the acetabular components occurs during load and to what extent. To evaluate this, revision multi-hole cups were implanted into six cadaver hemipelvises in two scenarios: without acetabular defect (ND); with a large acetabular defect (LD) that was treated with an augment. In the LD scenario, the cup and augment were attached to the bone and each other with screws. Subsequently, the implanted hemipelvises were loaded under a physiologic partial-weight-bearing modality. The deformation of the acetabular components was determined using a best-fit algorithm. The statistical evaluation involved repeated-measures ANOVA. The mean elastic distension of the ND cup was 292.9 µm (SD 12.2 µm); in the LD scenario, 43.7 µm (SD 11.2 µm); the mean maximal augment distension was 79.6 µm (SD 21.6 µm). A significant difference between the maximal distension of the cups in both scenarios was noted (F(1, 10) = 11.404; p = 0.007). No significant difference was noted between the compression of the ND and LD cups, nor between LD cups and LD augments. The LD cup displayed significantly lower elastic distension than the ND cup, most likely due to increased stiffness from the affixed augment and screw fixation.

Obesity, depression and hip pain.

INTRODUCTION: Up to 64% of the general population reports experiencing chronic pain, with the hip being one of the most frequent sites. An association has been shown between chronic back pain, obesity and depression. To date, a similar association has not been investigated with chronic hip pain. METHODS: A total of 2,515 subjects were chosen as a representative cross-section of the German population. Each was provided with a questionnaire that included the Regional Pain Scale, European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), Beck Depression Inventory-Primary Care and Winkler social class index. Participant height and weight values were obtained from self-reports. Using logistic regression methodology, we analysed the association between hip pain, obesity and increased depression scores. RESULTS: A total of 124 (4.9%) subjects reported chronic hip pain and an additional 39 (1.5%) reported chronic hip pain that was disabling. Hip pain affected 1-5 sites (oligolocular) in 47% of cases, and was widespread (6-19 sites) in 50%. Obesity and increased values on the depression scale were associated with an increased likelihood of chronic hip pain (odds ratio [OR] 2.55 and 8.53, respectively) compared with subjects without pain. Increased values on the depression scale (OR 28.22) increased the likelihood of experiencing disabling chronic hip pain in comparison with pain free individuals. CONCLUSIONS: Hip pain is rarely the sole site of pain. Obesity and increased values on the depression scale are associated with chronic hip pain. Increased values on the depression scale are associated with disabling chronic hip pain.

Long-Term Results of Acetabular Reconstruction Using Ganz Acetabular Rings.

BACKGROUND: Our study examines the long-term results of acetabular reconstruction using the Ganz acetabular reinforcement ring (GRR) in total hip arthroplasty. METHODS: Between 1998 and 2001, 135 hips (119 revision and 16 primary arthroplasties) were consecutively implanted with a GRR at our hospital. The average age was 65 years (range, 26-90). Clinical and radiographic evaluations were carried out. Long-term survivorship was estimated using a competing risks analysis, and multivariate survivorship using Cox regression model was used to identify risk factors for implant failure. RESULTS: At a mean follow-up of 16 years (range, 15-18), 3 patients were lost to follow-up and 19 had implant failure: 4 aseptic loosenings without re-revision, 4 septic, and 11 aseptic re-revisions. Survival was estimated at 86% after 16 years (95% confidence interval [CI], 78.5%-90.9%) using radiographic loosening or revision for any reason as the end point. Using aseptic loosening as the end point, the survival was estimated at 91.2% after 16 years (95% CI, 84.5%-95.0%). Multivariate analysis revealed that age at surgery was a significant risk factor for failure of the GRR. With acetabular revision or loosening as the end point, patients ≤60 years had 71.6% (95% CI, 53%-82.8%) and older patients had 92.2% (95% CI, 84%-96.2%) probability of implant survival after a mean 16-year follow-up. The median Harris Hip Scores and Western Ontario and McMaster Universities Osteoarthritis Index scores were 77 and 64.5, respectively, and mean Numerical Pain Rating Scale score was 1.6 at final follow-up. CONCLUSION: Our long-term study showed acceptable survival and functional results using the GRR in older patients, while young patients had less favorable survival.

[Infections after reconstructive spinal interventions : How do I deal with them?] / Infektionen nach rekonstruktiven Wirbelsäuleneingriffen : Wie gehe ich damit um?

BASICS: Postoperative surgical site infections of the spine have been described in up to 20% of patients and can result in serious consequences for the patient and substantial treatment costs. Typical bacteria often arise from skin or fecal flora. Various risk factors for infection have been described, including obesity, diabetes, high ASA scores, as well as intraoperative factors such as heavy blood loss, dural tears, or several revision procedures. Consequently, the prophylaxis with pre- and postoperative risk minimization is of particular importance. TREATMENT: When an infection has developed, it is important to carry out early operative revision involving tissue debridement, lavage and acquiring microbiological samples for culture. If the infection presents early, the instrumentation can often be retained. Adjuvant measures such as negative pressure wound treatment may improve the outcome. In late-onset infections, due to the biofilm production on the instrument surface or in cases of implant loosening, one should attempt to remove the instrumentation, and in cases of instability replace it. This article deals with the current literature on the subject and provides an overview of the data with regard to peri- and postoperative infections.

Treatment of High-Grade Acetabular Defects: Do Porous Titanium Cups Provide Better Stability Than Traditional Titanium Cups When Combined With an Augment?

BACKGROUND: Revision total hip arthroplasty frequently faces challenges associated with deficient bone stock. Porous metal implants were developed to meet the challenge, but require rapid osseointegration for ultimate success. This study aims to assess relative motion as an indicator for primary stability and osseointegration of two different titanium cups each combined with a titanium augment. METHODS: In 14 cadaver hemipelvises, 2 types of titanium acetabular cups, a traditional sintered-bead cup (POROCOAT Acetabular Cup [PAC]) and a newer porous-coated cup (GRIPTION Acetabular Cup [GAC]) each associated with a porous augment, were subjected to 3-dimensional varying loads, replicating 30% of loads experienced during normal gait. Relative motion was measured at the cup/bone, augment/bone, and cup/augment interfaces. RESULTS: Only at the cup/bone interface was there a statistically significant difference in relative motion between the traditional PAC and the newer GAC, with PAC showing less relative motion (P = .0037). Bone mineral density (BMD) had a significant effect on relative motion (P = .0019) at the cup/bone interface of both cup types, with low BMD specimens showing more relative motion. CONCLUSION: Both cup types combined with augments displayed minimal relative motion that was within the accepted range thought to allow osseointegration, although the traditional surface proved superior to the newer surface. This difference was more pronounced at low BMD, with the well-established PAC cup displaying less relative motion than the more porous GAC cup, consistent with better osseointegration than the more porous cup. This suggests that the more porous implant may be less advantageous than traditional PAC cups, particularly in cases with poorer bone stock.

Comparison of the Primary Stability of a Porous Coated Acetabular Revision Cup With a Standard Cup.

BACKGROUND: The number of revision hip arthroplasty procedures has been increasing substantially, with the acetabular component requiring component revision in over half of the cases. New porous implant designs attempt to improve outcomes due to improved osseointegration; however, sufficient primary stability is paramount for good osseointegration. METHODS: We compared 2 revision cups of the same geometry, yet different surface properties in an in vitro scenario: a porous titanium surface and a conventional sintered-bead titanium surface. These were tested in 10 cadaveric pelvises under a physiologic cyclic partial weight-bearing scenario. Each side was randomly implanted with one of the implants. Relative motion between the bone and cup was measured using an optical measuring device. Statistical evaluation was carried out descriptively using a covariance analysis with repeated measures and a test of fixed effects, with significance determined as P < .05. RESULTS: The conventional cup displayed an average relative motion of 28.02 µm; and the porous implant displayed an average relative motion of 33.42 µm. There was no statistically significant difference between the two with regard to the resultant relative motion (P = .2649). The bone mineral density does have a significant influence on resultant relative motion (P = .0406), with higher bone mineral density correlating with less relative motion in both implants. CONCLUSION: The porous implant provides similar primary stability to the conventional implant in the tested scenario; the motion of both implants relative to the bone was within safe limits for osseointegration. Bone stock must be considered when choosing implant type and postoperative care.

Bone remodelling around the Metha® short stem implant - Clinical and dual-energy x-ray absorptiometry (DXA) results.

OBJECTIVE: Bony ingrowth of short stems is under investigation. METHOD: Over one year bony reactions around the Metha® stem were investigated using the DXA method in a standardized zonal system (19 ROIs). Clinical results were documented using the HHS. RESULTS: HHS significantly improved from 46 points to 97 points. After one year bone marrow density (BMD) increased in the lateral distal and lateral proximal areas as well as in the mid medial area. BMD decreased in the proximal medial and mid lateral areas. CONCLUSION: The concept of metaphyseal ingrowth was confirmed, but distal bony reactions need further investigation.

Cementing a polyethylene cup into a well fixed acetabular metal-on-metal resurfacing component? An experimental investigation.

INTRODUCTION: Adverse reactions to metal debris often indicate revision surgery in metal-on-metal (MoM) hip arthroplasty and an exchange of the MoM bearing into either a metal on polyethylene or a ceramic-on-polyethylene articulation. At the moment the removal of the entire implant system is the most reasonable method. In order to avoid bone loss caused by the removal of a well-fixed acetabular component, the purpose of this study was to measure the stability of a cemented polyethylene (PE) cup in an acetabular hip resurfacing component and to examine if such a method could be suitable for clinical use. METHODS: PE cups were cemented into 2 different hip resurfacing components and biomechanical tests were applied to measure failure torques under lever out and rotational load. RESULTS: In all cases failure of the interface between the resurfacing components and the cement layer occurred at a very low load (0.14 Nm-61.50 Nm). DISCUSSION: The early failure occurred due to lacking interdigitation of cement and the polished metal surface. Thus we warn against cementing a PE cup into acetabular hip resurfacing components for clinical use.

The Penrod score: a prognostic instrument to balance an increasing geriatric fracture caseload with diminishing health care resources?

INTRODUCTION: Geriatric hip fracture patients are a highly heterogeneous collective, what distinctly aggravates the best possible treatment. Consequently, it is becoming more important to identify selection criteria that can distinguish those patients who can benefit the most from treatment in a geriatric fracture center. In our pilot study, we assessed the 2007 published Penrod score for its utility as a useful selection tool by prospectively comparing our own patient's outcome with the Penrod study. METHODS: 77 patients treated for geriatric hip fracture were preoperatively classified according to the Penrod score. Patients were divided into three clusters by age (1: <75 years, 2: 75-84 years, 3: ≥85 years). Clusters 2 and 3 were then classified according to their ability to perform activities of daily living (ADL's) and cognitive status (presence or absence of dementia). In 51 out of these 77 patients, the ability to perform ADLs could be assessed 6 months postoperatively and was compared with the Penrod scores. RESULTS: 58 % of cluster 1 patients were able to perform 4 ADLs independently 6 months postoperatively (52.9 % Penrod study). In clusters 2A and 3A, 48 and 50 %, respectively, were able to perform 4 ADLs independently, compared with 40.6 and 31.5 % (Penrod collective). 22 % of our patients in 2B performed all ADLs independently (3.6 % Penrod) and 25 % in cluster 3B (9.4 % Penrod). CONCLUSION: Our preliminary results support the prognostic value of the Penrod score in the treatment of geriatric hip fracture patients. With the help of the Penrod score, it may be possible to identify patients, who are expected to significantly profit from an intensified treatment in a geriatric fracture center (clusters 2B, 3A, and 3B). By utilizing this score, improved outcomes and simultaneously a more effective utilization of valuable health care resources could be achieved.