Introduction. Mechanical properties of irradiated Ultra High Molecular Weight Polyethylene (UHMWPE) after aging have been well documented. However there was no sufficient data for the dimensional change due to irradiation and aging. This change may have adverse effects to the implant modular locking mechanism. The purpose of this study was to characterize the dimensional change of UHMWPE after irradiation and aging. Materials and Method. Total (30) ø15mm × 50mm virgin GUR 1050 UHMWPE rods were cleaned, dried, inspected, vacuum packaged and stored in 20°C environment for 2 days. Among them, (20) samples were measured along the 50mm length at 20°C +/-2°C before and after two conditions: 1, (10) were submerged in 40°C DI water for 2 hours and dried in 40°C to simulate the cleaning process and 2, (10) were soaked in 37°C saline for 14 days to simulate initial in-vivo environment. Remaining (10) samples were measured in the same way after irradiation of 30KGy dosage and then measured again after soaking in 37°C saline for 14 days to simulate the actual radiation sterilization and in-vivo soaking conditions. Same samples were measured once more after accelerated aging per ASTM-1980-07 for 80 days to simulate the 3 year in vivo life. The differences in measurements between virgin and end conditions were documented as the percentage dimensional change. After the measurements, in the groups of DI water, saline soaking and radiation + aging, (3) samples were randomly selected for DSC measurements. The results were compared with dimensional measurements. Statistical analysis was performed by the student t test to compare virgin condition and the conditions after each treatment. 95% significance level was assumed. Results. As shown in Table 1, after water wash and saline soaking, the average dimensions increased but not statistically significant. Radiation alone caused the net decrease in sample dimensions and remained in negative after a saline soaking. Further significant dimensional decrease (P<0.05) occurred after aging. Increased DSC % crystallinity was found in the aged samples. Discussion. Study showed the net dimensional change of UHMWPE was shrinkage under simulated in-vivo enviroment.
Highly cross linked polyethylenes have been shown to be substantially wear resistant. Typically, crosslinking is achieved by radiation in a low oxygen environment. While the early wear-simulation data is encouraging, concerns remain about the potential for aging and oxidative damage on exposure to oxygen during storage or in the body. This study measured wear rates in highly crosslinked liners that had been exposed to room air for up to 4 years. Polyethylene liners were divided into four groups: two groups of highly crosslinked liners, XL (freshly opened) and XL-Aged (aged); and two groups of nominally crosslinked liners, N (freshly opened) and N-Aged (aged). The highly crosslinked liners were crosslinked with 9.5 Mrad of warm electron-beam irradiation, treated to a post-cross linking heat treatment to quench free radicals (WIAM), followed by ethylene oxide sterilization. The nominally cross linked liners were sterilized with 2.5 Mrad. The aged liners (XL-Aged and N-Aged) were stored in saline (at 37°C) exposed to room air for 4 years. Three liners from each group were tested in a hip-wear simulator (90% bovine serum) for 5 million cycles. Gravimetric wear measurements were made at 500,000 cycle intervals. The N and N-Aged groups wore at rates of 14.76 ±3.1 and 15.58 ±1.21 mg/million cycles, respectively. The wear in both XL and XL-Aged groups was not measurable, resulting in weight gains of 2.73±0.5 and 2.17 ±1.1 mg/million cycles, respectively. WIAM cross linked polyethylene has been reported to generate the least free radicals and has the least potential for oxidative damage. There have been concerns regarding the validity of artificial aging by the high-temperature oxidation.
The escalating demand for medical resources to address spinal diseases as society ages is an issue that requires careful evaluation. However, few studies have examined trends in spinal surgery, especially unscheduled hospitalizations or surgeries performed after hours, through large databases. Our study aimed to determine national trends in the number of spine surgeries in Japan. We also aimed to identify trends in after-hours surgeries and unscheduled hospitalizations and their impact on complications and costs. We retrospectively investigated data extracted from the Diagnosis Procedure Combination database, a representative inpatient database in Japan. The data from April 2010 to March 2020 were used for this study. We included all patients who had undergone any combination of laminectomy, laminoplasty, discectomy, and/or spinal arthrodesis.Aims
Methods
The A newly developed Raman microprobe-assisted indentation method was applied to evaluate and compare surface fracture toughness mechanisms operative in Si3N4 (Amedica Corporation, Salt Lake City, UT, USA), Al2O3 and ZTA (BIOLOX® Introduction
Materials
31 consecutive patients (mean 54.7 years) were examined mean follow-up time of 47 months. Patients were evaluated clinically; using Lysholm, Cincinnati, IKDC and Tegner Activities Scores. Objective assessments were made with KT1000 Arthrometer and Isokinetic strength testing. Lysholm scores improved from 62 preoperatively to 93 at review; Cincinnati 48 to 89; Tegner 3.6 to 5.2. 81 percent of knees were considered normal or nearly normal to IKDC, 6 abnormal, none severely abnormal. KT1000 manual max difference 2.9mm; Isokinetic flexion strength 102 percent; extension strength 95 percent. Poor results were mainly associated with advanced articular cartilage degenerative changes at time of surgery. This also correlated with increased time from injury to surgery, and increased preoperative injury rates. This study demonstrates that the anterior cruciate ligament can be reliably reconstructed in patients over the age of 50 years with good symptomatic relief, restoration of function and return to activity.
The suggestion of a meniscal tear produces a pavlovian response in the orthopaedic surgeon. However, meniscal signal anomalies and associated changes become common with age in symptom free knees. T he issue for the IME requested to assess workers with painful knees is to determine if the MRI changes represent a painful injury and if the treatment planned (usually arthroscopy) may, in fact, be harmful. MRI signal changes are assessed on the likelihood they predict for unstable meniscal tears. Some patterns of meniscal tears are benign. Associated changes such as baker's cyst and ligament thickening are also common but are poor predictors of symptomatic tears. Preclinical osteoarthritis has a high incidence of associated meniscal change and arthroscopic menisectomy may accelerate osteoarthritis progression. Clinical tests have variable specificity and sensitivity but in combination with an understanding of the patterns of MRI signal can be combined to predict which meniscal tears would benefit from arthroscopic surgery, which injuries would do as well with non-operative treatment and which patterns predict deterioration after surgery. As the views of the IME are often contrary to the surgeon, a comprehensive bibliography is provided for any who need to argue their case. As the topic is information and image dense, a CD ROM will be distributed.
Vitamin E (alpha-tocopherol) is a free-radical stabilizing agent used to maintain oxidative stability in radiation crosslinked UHMWPE for total joint replacements. Diffusion of vitamin E into UHMWPE after irradiation is one method of incorporation, while an alternative is blending vitamin E with UHMWPE resin powder and subsequently irradiating the consolidated mixture. With the latter method, it is possible for the antioxidant properties of Vitamin E to be exhausted in blends during irradiation, leading to oxidation. We report on the relative oxidative resistance of both irradiated (100kGy, 150kGy, 200kGy) vitamin E blends (0.02 wt%, 0.05 wt% and 0.1wt%) and post-irradiation vitamin E-diffused UHMWPE after three years of real-time aging in an aqueous environment at 40°C. Blocks of each type, including irradiated virgin UHMWPE, were also accelerated aged per ASTM F2003. Oxidation was measured with FTIR per ASTM F2102. Oxidation potential was determined through nitric oxide staining of hexane extracted thin sections, FTIR analysis and calculated using the height of the nitrate peak (1630 cm^-1). Our results showed that unstabilized samples exhibited substantial oxidation and oxidation potential throughout the surface and bulk with both types of aging. Post-irradiation diffused UHMWPE showed no detectable oxidation and decreasing oxidation potential with both aging methods. The vitamin E concentration at the surface of the diffused blocks decreased and the initial non-uniform profile with high surface concentration (3.4 wt%) shifted towards a uniform profile, equilibrating at an index of 0.1 or 0.7 wt% vitamin E. Samples showed a reduction in their initial vitamin E content by 47%– 61% over 36 months, but oxidative stability was not compromised. The non-uniform profile presumably created a driving force for elution into the aqueous environment, while the difference in solubility of vitamin E at 40°C, compared to the initial diffusion temperature at 120°C, may have also contributed. After six months of real-time aging, all irradiated blends showed surface oxidation, while 0.02 wt% blends additionally showed subsurface oxidation potential. However, oxidation was not induced by accelerated aging Methods: in any blended, irradiated samples. In conclusion, real-time aging resulted in greater differentiation in the relative oxidative stability of vitamin E-stabilized, radiation crosslinked UHMWPEs than accelerated aging. Irradiated blends with vitamin E concentrations as high as 0.1 wt% showed surface oxidation after 3 years; higher vitamin E concentrations cannot address this shelf oxidation as that will also reduce the crosslinking efficiency and increase wear. Post-irradiation diffused UHMWPE, which was not limited by the amount of incorporated vitamin E, showed oxidative resistance up to 3 years with a reduction in oxidative potential.
Irradiation cross-linking of UHMWPE has been shown to reduce wear while generating free radicals that oxidise in the presence of oxygen or oxidising species. Various methods have been used to minimise or eliminate the effect of these free radicals including below-melt annealing, remelting, Vitamin E infusion, or the use of other antioxidants. Each method has benefits and drawbacks with respect to wear properties, mechanical properties, and chemical properties. Accelerated aging techniques are used to evaluate the efficacy of new methods in stabilising free radicals in highly cross-linked UHMWPE. Various procedures have been described for aging standard gamma-air sterilised UHMWPE to produce oxidation levels that represent shelf-aged bearings. An important factor in evaluating and comparing these aging techniques is validating that they reproduce the profile of oxidation (depth and magnitude) seen both in gamma-air, shelfaged polyethylene and in clinical retrievals. Moreover, the resulting oxidation level in the aged UHMWPE should predict the fatigue and/or wear damage seen in retrieved gamma-air inserts and liners. The present study compared clinically relevant UHMWPE samples aged with ASTM 2003-00, (Method B: 70°C, 5 atm O2, 14 days) and a published lower temperature, lower oxygen-pressure environment (63° C, 3 atm O2, 28 days). Longer aging times (35 to 42 days) were also tested to examine oxidation rate and time to onset of mechanical degradation. Both published methods result in oxidation of gamma-air and gamma-barrier sterilised polyethylene, but have little effect on remelted or antioxidant stabilised crosslinked polyethylene. These aging protocols, however, did not bring standard polyethylene to the critical oxidation level necessary for the fatigue damage that is seen in retrieved inserts and liners. Oxidation of gamma-air and gamma-barrier sterilised UHMWPE increases exponentially with time on the shelf or in the two aging environments. Of note, longer aging times (35 to 42 days) that bring standard UHMWPE to sufficiently high oxidation levels for fatigue to occur also cause increased oxidation levels in remelted UHMWPE. Oxidation increases were the smallest in antioxidant UHMWPE, though still detectable. While this oxidation is not high enough in remelted material or antioxidant material to cause the fatigue damage seen in gamma-air sterilised UHMWPE, it does raise concerns about the published aging techniques and the long term stability of the new materials in vivo. Relying on artificial aging techniques that do not adequately challenge even gamma-air polyethylene may conceal unforeseen weaknesses of new materials. Using longer aging times for existing techniques or novel aging approaches may be necessary to effectively evaluate the long term stability of new bearing materials.
The purpose of this study was to examine the interactive effects of diet and the aging process on the mechanical and material properties of bone. We investigated how an ad libitum (AL) diet and 40% caloric restriction (CR) with nutrient supplementation, beginning at 3.5 months of age, interacted with the aging process to influence bone development. Diet effects were determined by measuring changes in bone geometry and bone mechanics of the tibia in young adult and senescent Fischer 344 X Brown-Norway Rats (F344 BN) rats. Male F344 BN rats were divided into two dietary groups, AL or CR. CR commenced at 14 weeks of age, with 40% restriction and micronutrient supplementation. The AL group represented young adult (8 mo) and senescent (30–35 mo) rats. The CR group represented 8 mo and 35–40 mo rats. AL and CR groups were matched together for comparison based on the percentage survival rate. Tibiae were assessed using microcomputed tomography, mechanical testing, and ash analysis. The results showed that a CR diet resulted in a significant decrease in total body mass when compared to the AL diet group across all ages. With aging, both AL and CR diet groups showed a general increase in structural properties and a decrease in material properties. Furthermore, material and structural properties changed proportionately between both diet groups. Comparisons between diet groups based on percentage survival rate revealed a significant decrease in most structural properties, but no significant changes in material properties with CR. After normalization to body mass, structural properties were significantly greater in the CR group when compared to the AL group. The significantly greater CR structural properties over the AL diet group after normalization, with no significant changes in material properties, indicated that CR did not adversely affect the appendicular skeleton in F344 BN rats. Therefore, a CR diet with 40% restriction at fourteen weeks, with nutrient supplementation did not negatively impact tibial geometrical and mechanical properties in young and senescent male F344 BN rats.
Conventional: UHMWPE gamma sterilized in inert, SXL: sequentially irradiated and annealed UHMWPE irradiated to a cumulative dose of 100kGy (33 kGy irradiation + 8 hour annealing in air, repeated 3 times) and gas plasma sterilized, and E-Poly: UHMWPE irradiated to 100kGy, stabilized with α-tocopherol, and gamma sterilized in inert. Four specimens from each group were subjected to a reciprocating mechanical stress of 10 MPa at a frequency of 0.5 Hz in an environmental chamber maintained at 80°C. Control samples were placed in the chamber but not subjected to cyclic mechanical stress. When a visible crack was observed on a sample’s surface or when a sample fractured, it and its corresponding control sample were analyzed by FTIR to quantify oxidation.
Exercise deters systemic diseases such as osteoporosis, sarcopenia, diabetes and obesity. Brief daily periods of low intensity vibration (LIV; <0.4g) is anabolic to bone and muscle, an adaptive response achieved in part by biasing mesenchymal stem cell (MSC) fate selection towards forming higher order connective tissues. In the clinic, LIV has protected the musculoskeletal system even under severe challenges such as Crohn Disease, Cerebral Palsy, and end-stage renal disease. Low magnitude mechanical signals also suppress adipogenesis in the mouse, with reductions in subcutaneous and visceral fat. The starkly distinct response of these tissues (augment bone & muscle; suppress fat) suggests that LIV influences the differentiation pathway of MSCs. Extending this diet induced obesity model to 7 months increased total adiposity, accelerated age-related loss of trabecular bone and severely reduced B & T-cell number in the marrow and blood, shifting hematopoietic stem cells (HSC) towards the myeloid lineage. LIV introduced at 4 months rescued bone and B-cells to those levels measured in regular diet controls. These data emphasise why inactivity can promote osteoporosis, diabetes and obesity, and why a sedentary individual is predisposed to disease sequelae. Protection of MSC and HSC populations by mechanical signals may represent a unique strategy by which adiposity can be suppressed, the immune system protected, and a musculoskeletal system enhanced.
Both total joint arthroplasty (TJA) and Alzheimer's Disease (AD) are prevalent in elderly populations. It is the goal of this study to determine if the presence of implant metals originating from TJA correlates with the onset with higher implant metal content in the brain and AD pathology. Tissue samples from four brain regions of 701 (229 with TJA) participants from an ongoing longitudinal cohort study (Rush Memory and
Osteoporosis accounts for a leading cause of degenerative skeletal disease in the elderly. Osteoblast dysfunction is a prominent feature of age-induced bone loss. While microRNAs regulate osteogenic cell behavior and bone mineral acquisition, however, their function to osteoblast senescence during age-mediated osteoporosis remains elusive. This study aims to utilize osteoblast-specific microRNA-29a (miR-29a) transgenic mice to characterize its role in bone cell aging and bone mass. Young (3 months old) and aged (9 months old) transgenic mice overexpressing miR-29a (miR-29aTg) driven by osteocalcin promoter and wild-type (WT) mice were bred for study. Bone mineral density, trabecular morphometry, and biomechanical properties were quantified using μCT imaging, material testing system and histomorphometry. Aged osteoblasts and senescence markers were probed using immunofluorescence, flow cytometry for apoptotic maker annexin V, and RT-PCR. Significantly decreased bone mineral density, sparse trabecular morphometry (trabecular volume, thickness, and number), and poor biomechanical properties (maximum force and breaking force) along with low miR-29a expression occurred in aged WT mice.
Purpose. Back pain is the primary cause of disability worldwide yet surprisingly little is known of the underlying pathobiology. We conducted a genome-wide association study (GWAS) meta-analysis of chronic back pain (CBP). Adults of European ancestry from 15 cohorts in the Cohorts for Heart and
Introduction. NF-κB transcription factors regulate a number of genes that are activated under stress conditions. Blockage of the the canonical NF-κB pathway has been emerged as a possible strategy to cure osteoarthritis and rheumatoid arthritis. However, the roles of κNF-B in normal skeletal physiology are largely unknown owing to the lack of suitable animal models. Here, we investigated the function of canonical κNF-B pathway in the cartilaginous skeleton by ablating Nemo (NF-κB essential modulator) in chondrocytes using the Col2a1 transgene. Methods. Mice were analyzed by skeletal staining, histology, proliferation and apoptosis assays at various stages. Histochemistry, GAG assay and immunohistochemistry were utilized to assess the impact of NEMO-deficiency in cytokine-induced cartilage degradation of hip explants. To identify genes regulated through the canonical NF-κB pathway in response to injury, an ex vivo hip avulsion model was applied. 24 genes known to be induced early following cartilage injury were assessed in wildtype and mutant hips by RT-PCR. Time lapse photography was used to investigate chondrocyte migration in vitro. Atomic force microscopy (AFM) was applied to assess biomechanical properties of the cartilage. Pathological changes of articular cartilage were scored in aged joints. Results. Mutant mice exhibited moderate dwarfism postnatally characterized by disorganized growth plate, abnormal chondrocyte proliferation, apoptosis and migration. AFM indentation experiments showed no changes in biomechanical properties of the mutant growth plate compared with control. Exposure of aggrecan degradation neoepitopes and release of GAGs were less pronounced in mutant hip explants stimulated by cytokines. Of the 24 genes regulated 4h following injury in wildtype hips, only Arginase-1 was suppressed in the mutant hips, while the expression levels of most other inflammatory response genes e.g. TSG-6, NOS2, COX2, IL6 and IL1b were unaffected. A small number of genes, IL-18, MMP-3 and Has-2 were further upregulated upon injury in Nemo-deficient compared with wildtype hips.
The February 2023 Hip & Pelvis Roundup360 looks at: Total hip arthroplasty or internal fixation for hip fracture?; Significant deterioration in quality of life and increased frailty in patients waiting more than six months for total hip or knee arthroplasty: a cross-sectional multicentre study; Long-term cognitive trajectory after total joint arthroplasty; Costal cartilage grafting for a large osteochondral lesion of the femoral head; Foley catheters not a problem in the short term; Revision hips still a mortality burden?; How to position implants with a robotic arm; Uncemented stems in hip fracture?
Purpose: Until now no experimental study has evaluated the effect of orthopedic immobilizations of the lower right limb on driving performances. Clinicians and legislators therefore cannot appropriately advise patients with this type of treatment on their driving capabilities and put forth recommendations for road safety. Method: An experimental study of the effect of orthopedic immobilizations of the lower right limb on driving performances has been conducted at the Research Center on
Introduction. In total hip arthroplasty ceramic on ceramic bearing couples are used more and more frequently and on a wordwide basis. The main reason of this choice is reduction of wear debris and osteolysis. The tribological properties and the mechanical behaviour of the implanted ceramic must remain the same throughout the patient's life. The aim of this study was to evaluate the resistance of Alumina Matrix Composite to environmental degradation. Material and method. The alumina matrix composite or BIOLOX ® delta is manufactured in Germany by CeramTec. It is made up of 80 vol.% Al2O3, 17 vol.% Yttria Stabilized ZrO2 and 3vol.% strontium aluminate platelets. The zirconia grains account for 1.3 mol.% of the Yttria content. Accelerated aging tests in water steam at 142°C, 134°C, 121°C, and 105°C were performed to evaluate the aging kinetics of the composite. X-ray diffraction was used to determine the monoclinic phase content on the material surface. Phase transformation is associated with weakness and increase in roughness of zirconia ceramic implants. Results. The data below shows average monoclinic contents before and after aging in water vapour according to the ISO standard test (134°C, 2 bars water steam, 10 h) on the surface and inside the 28 mm taper(12/14 taper) femoral ball heads manufactured in alumina ceramic composite. There are precisions concerning the roughness and the load to failure before and after aging concerning 28mm diameter heads. Before
Hip-spine relationships should be better investigated in THP as lumbo-sacral orientation in the sagittal plane plays a critical role in the function of the hip joints. Lateral X-rays showing spine and hips together in standing, sitting or squatting positions characterize the adaptations of the sagittal balance and the functionnal interactions between hips and spine. Acetabular cup implantation has to be planned for frontal inclination, axial anteversion, and sagittal orientation. The later refers to the sacro-acetabular angle, key-point in the spine – hip relationships, and that is redefined by the surgeon at the time of implantation. Usual standard CT-sections are biased for evaluating acetabular anteversion. The conventional CT procedure does not refer to the pelvic bony frame and. the measured anteversion is a projected angle on a transverse plane, depending on the pelvic adaptation in lying position. This measured angle is often considered as anatomical anteversion, leading to some confusion. Therefore this angle is only a “functional” supine anteversion, reflecting the anterior opening angle of the acetabulum in a specific position. According to the sagittal orientation of the pelvis, the true functional acetabular orientation can virtually be assessed in various postures from adjusted CT-scan sections. The EOS. ™. low irradiation 2D-3D X-ray scanner is an innovative technology already used for global evaluation of the spine. This technology allows simultaneously “full body” frontal and lateral X-rays with the patient in standing, sitting or squatting positions; a tridimensionnal patient specific bone recontruction can be performed and the cup anteversion can be directly assessed according to the position. We investigated the lumbo-pelvic parameters influencing the tridimensionnal orientation of the acetabulum. We compared the data obtained for real postural situations using the EOS. ™. system and the measures from plane X Rays and classical CT scan cuts replicating standing, and sitting positions.368 patients with cementless THP were involved in a prospective follow-up protocol. Sacral slope and pelvic tilt, incidence angle, acetabular frontal and sagittal inclination were evaluated on AP and lateral standard XRays. Functionnal anteversion of the cup has been measured using a previously described protocol with CTscan cuts oriented according to standing and sitting sacral slope. The mean difference between CTscan and EOS. ™. system was 4,4° with comparable accuracy and reproductibility. Sacral slope decrease in sitting position was linked to anteversion increase (38,8° SD 5,4°). Sacral slope increase in standing position was linked to lower ante-version (31,7° SD 5,6°). The anatomical acetabular anteversion, the frontal inclination, and the sagittal inclination were functional parameter which significantly varied between the standing, sitting, and lying positions. We noticed that the acetabular parameters in lying position highly correlated to the one in standing position, while poorly correlated with the one in sitting position. The difference between the lying and the sitting positions was about 10°, 25°, and 15° for the cup anteversion (CA) and the frontal and sagittal inclinations (FI,SI) respectively. The poor correlation between the lying and sitting positions suggests that the usual CT scan protocol is biased and not fully appropriate for investigating the cases of posterior THP dislocation and subluxation, which happen in sitting position. On the contrary, a strong correlation was observed between lying and standing measurements with all the acetabular parameters (CA,FI, SI), suggesting that the classical CT assessment of the cup anteversion remains an interesting source of information in case of anterior THP. Each patient is characterized by a morphological parameter, the incidence angle. High incidence angle is linked to low acetabular anteversion, increasing the instability risk and anterior impingement in sitting and squatting position; higher anteversion angles are observed in low incidence angle patients, leading to more internal rotation of the hip in any position. Lumbo-sacral orientation in the sagittal plane influences the tridimensionnal orientation of the acetabulum, especially for anteversion.
Infection of a total joint replacement (TJR) is considered a devastating complication, necessitating its complete removal and thorough debridement of the site. Usually at least two surgical interventions and antibiotic treatment within a period of several months are estimated being required for a favourable outcome. It is undoubted that one stage exchange, if successful, would provide the best benefit both for the patient and the society. Still the fear of re-infection dominates the surgeons’ decisions and directs them to multiple stage protocols. However, there is no scientifically based argument for that practice. Successful eradication of infection with two stage procedures is reported to average 80% to 98%, whereas there are no significant differences between revisions with or without antibiotic loaded cement, with short or long term antibiotic therapy, with or without the use of spacers and other differences. On the other hand a literature review of Jackson and Schmalzried (CORR 200) summarizing the results of 1,299 infected hip replacements treated with direct exchange (almost exclusively using antibiotic loaded cement), reports of 1,077 (83%) having been successful. For total knee replacement Jaemson et al. (Acta 2009) could show that the overall success rate in eradication of infection was 73–100% after one-stage revisions. It may be calculated, that adding a second one stage procedure for treating the failed cases the overall result with two operations may improve to >
95%, an outcome which is at least as good as the best results after two stage revisions, while requiring only one surgical intervention for the majority of cases. Spacers have been proven to be useful for improving final functional results compared to temporary resection; however, concerning infection control no benefit could be shown. Dead space management is performed comparably effective by a new prosthesis as with a spacer. In addition a definitive prosthesis is providing increased stability, which a spacer does not. As long as protection against colonization is granted by high local antibiotic concentrations a prostheses is likely to provide better functional results than a spacer. These results suggest, that the major factor for a successful outcome with traditional approaches may be found in the quality of the surgical debridement and dead space management. Failures in all protocols seem to be caused by small fragments of bacterial colonies remaining after debridement, whereas neither systemic antibiotics nor antibiotic loaded bone cement (PMMA) have been able to improve the situation significantly. One stage exchange provides marked reduction of patients discomfort and costs but is performed only rarely due to a multitude of risks and disadvantages, related to the mandatory use of antibiotic loaded cement for fixation. Cemented revisions generally show inferior long term results compared to uncemented techniques; the addition of antibiotics to cement reduces its biomechanical properties. The release of antibiotics from cement is too short-lived and concentrations are too low for reliable eradication of eventually remaining pathogens, especially when they are embedded within biofilms. PMMA has been shown to be the ideal substrate for bacterial attachment and replication of sessile bacterial phenotypes.
Osteoarthritis (OA) is an important cause of
pain, disability and economic loss in humans, and is similarly important in
the horse. Recent knowledge on post-traumatic OA has suggested opportunities
for early intervention, but it is difficult to identify the appropriate
time of these interventions. The horse provides two useful mechanisms
to answer these questions: 1) extensive experience with clinical
OA in horses; and 2) use of a consistently predictable model of
OA that can help study early pathobiological events, define targets
for therapeutic intervention and then test these putative therapies.
This paper summarises the syndromes of clinical OA in horses including
pathogenesis, diagnosis and treatment, and details controlled studies
of various treatment options using an equine model of clinical OA.
The records of patients aged 50 years or over who underwent primary reconstruction of the anterior cruciate ligament between 1990 and 2002 were reviewed. There were 35 knees in 34 patients that met the inclusion criteria. The mean age of the patients was 57 years (50 to 66) and the mean clinical follow-up was for 72 months (25 to 173). A total of 23 knees were reconstructed with patellar tendon allograft, and 12 with patellar tendon autograft. The mean pre-operative knee extension was 1° (−5° to 10°) and flexion was 129° (125° to 150°) and at follow-up these values were 0° (−5° to 5°) and 135° (120° to 150°), respectively. Pre-operatively there were 31 knees (89%) with a Lachman grade 2+ or 3+. Post-operatively, 33 knees (94%) were Lachman grade 0 or 1+. The mean pre- and post-operative International Knee Documentation Committee scores were 39 (23 to 72) and 90 (33 to 100) respectively. The mean pre- and post-operative Lysholm scores were 50 (18 to 68) and 92 (28 to 100) respectively and the mean University of California Los Angeles activity scores were 8.5 before injury (4 to 10), 4.3 (3 to 6) after injury and 8.3 (4 to 10) post-operatively. There were three graft failures (8.6%) requiring revision. We conclude that reconstruction of the anterior cruciate ligament in carefully-selected patients aged 50 years or over can achieve similar results to those in younger patients, with no increased risk of complications.