[How Does Affect the Type of Instability after Total Hip Arthroplasty the Outcomes? Our Experience between 1999 and 2020]. / Jak ovlivnuje typ luxace TEP kycle výsledek lécby? Analýza souboru pacientu za období 1999­2020.

PURPOSE OF THE STUDY Dislocation is one of the most common early complications of total hip arthroplasty (THA). In this manuscript, 20 years of experience with the management of this complication are presented, particularly in relation to the type of instability. MATERIAL AND METHODS In the period between January 1999 and December 2020, at least one dislocation occurred in 157 of 8 286 (1.9%) THA patients, of which 117 dislocations (1.6%) in primary and 40 (3.4%) in revision THAs. Almost all patients were operated on from the anterolateral approach during the follow-up period. The type of dislocation was evaluated using the modified Dorr classification. In the first dislocations, conservative approach was usually opted for, except for cases with a clear malposition, irreducible or unstable hips after the reduction. The minimum follow-up period was 18 months (18-240). The success rate of the chosen treatment approach was assessed by means of standard statistical methods. RESULTS The total dislocation rate in the follow-up period was 1.6% for primary THAs and 3.4% for revision THAs. The dislocation rate was slightly higher between 1999 and 2009 compared to the following decade (2.1% versus 1.3% for primary THAs; p=0.009). The most common type of dislocation was the positional dislocation (62%), followed by dislocations due to a combination of causes (17%) and component malposition (11%). Treatment of dislocation was successful in a total of 130 patients (130/157; 83%). Even though a stable hip was achieved in 21 patients (13%), the functional outcome was unsatisfactory, and in 6 patients (4%) we failed to achieve a stable hip. In the positional type of dislocation, the success rate of closed reduction following the first-time dislocation was 86.4% and a similar success rate was reported for reoperations in the first-time dislocations due to the malpositioned components (85.7%). In the second-time dislocation, the surgical therapy was significantly more reliable compared to closed reduction regardless of the type of dislocation (78.6% versus 46%). The treatment of dislocations following primary THAs showed comparable outcomes to those of the treatment of dislocations following revision THAs. Overall, the worst outcomes were achieved in patients with a combined type of dislocation. In total, the THA had to be removed in 11.5% of hips (18/157). The probability of final THA removal increased with the increasing order of dislocation. DISCUSSION In our group of patients, the dislocation rate in THA was comparable or lower than the published data. With the use of preventive measures, i.e. dual mobility cup or larger head diameters in high-risk patients, we managed to reduce the dislocation rate over time. The positional type of dislocation prevails in our group of patients just as in the previously published series, followed by instability from malposition of components. The modified Dorr classification is used to guide the treatment since it allows us not only to make good decision about the treatment modality but to some extent also to estimate the final outcome, particularly with respect to restoring a functional and stable hip. CONCLUSIONS The total dislocation rate was 1.6% for primary THAs and 3.4% for revision THAs. The first-time dislocation of the positional type shall be treated conservatively. Conversely, in the other types of dislocations and in recurrent dislocations, surgical treatment is more likely to achieve a good clinical outcome. The worst outcomes are to be expected in an instability due to combination of multiple causes, which leads to the removal of THA more often than in other types of dislocations. Also, the benefit of preventive measures in high-risk patients over time has been confirmed. Key words: total hip arthroplasty, dislocation, Dorr's classification, treatment strategy, outcomes, complications.

Torus obstacle method as a wrapping approach of the deltoid muscle group for humeral abduction in musculoskeletal simulation.

Musculoskeletal models of the shoulder complex are valuable research aids to investigate tears of the supraspinatus and the resulting mechanical impact during abduction of the humerus. One of the major contributors to this motion is the deltoid muscle group and for this, an accurate modeling of the lines of action is indispensable. The aim of this work was to utilize a torus obstacle wrapping approach for the deltoids of an existing shoulder model and assess the feasibility of the approach during humeral abduction. The shoulder model from the AnyBody™ modeling system was used as a platform. The size of the tori is based on a magnetic resonance imaging (MRI) approach and several kinematic couplings are implemented to determine the trajectories of the tori during abduction. To assess the model behavior, the moment arms of the virtual muscle elements and the resultant glenohumeral joint reaction force (GHJF) were compared with reference data from the literature during abduction of the humerus in the range 20°-120°. The root mean square error for the anterior, lateral and posterior part between the simulated muscle elements and reference data from the literature was 3.9, 1.7 and 5.8 mm, respectively. The largest deviation occurred on the outer elements of the muscle groups, with 12.6, 10.4 and 20.5 mm, respectively. During abduction, there is no overlapping of the muscle elements and these are in continuous contact with the torus obstacles, thus enabling a continuous force transmission. This results in a rising trend of the resultant GHJF. The torus obstacle approach as a wrapping method for the deltoid muscles provides a guided muscle pathing by simultaneously approximating the curvature of the deltoid muscle. The results from the comparison of the simulated moment arms and the resultant GHJF are in accordance with those in the literature in the range 20°-120° of abduction. Although this study shows the strength of the torus obstacle as a wrapping approach, the method of fitting the tori according to MRI data was not suitable. A cadaver study is recommended to better validate and mathematically describe the torus approach.

[Local Application of Tranexamic Acid in Total Hip Arthroplasty Decreases Blood Loss and Consumption of Blood Transfusion]. / Lokální aplikace kyseliny tranexamové u TEP kycle snizuje krevní ztráty a spotrebu krevních transfuzí.

PURPOSE OF THE STUDY The primary aim of our study was to identify the effects of local application of tranexamic acid (TXA, Exacyl) on the amount of postoperative blood loss and blood transfusion requirement in primary total hip arthroplasty. We also recorded the levels of postoperative haemoglobin and its drop in early period after surgery. In each patient, we monitored in detail the incidence of early complications (haematoma, wound exudate). Lastly, the economic aspect of TXA administration was also taken into account. MATERIAL AND METHODS The prospective study included a total of 312 patients (122 men and 190 women) undergoing primary total hip arthroplasty (THA) at our department between January 2012 and November 2015. The patients enrolled in the study were divided into the intervention group with local (intra-articular) application of TXA and the control group without using TXA. Each group had 156 patients. The mean age of patients in the group with TXA was 65.6 years and the most frequent indication for THA surgery was primary osteoarthritis (59.0 %). The groups did not show any differences in basic characteristics, which was statistically verified. In each patient the volume of postoperative drainage, total blood loss, including the hidden loss, was recorded. In postoperative period, we monitored the haemoglobin levels and haematocrit. On discharge of each patient from the hospital, the size and site of a haematoma, wound exudate if still present even after postoperative day 4 and early surgical revision were evaluated. RESULTS In the group with TXA the blood losses from drains were significantly lower compared to the control group (493.4 ± 357.1 ml vs. 777.3 ± 382.5 ml; p < 0.0001). The median value for total blood loss (i.e. drainage volume and hidden loss) in the group with TXA was by 29.5 % lower than the median in the group without TXA (689.2 vs. 977.1 ml). The mean total blood loss (intraoperative + postoperative) was 783.8 ± 478.6 ml (mean ± standard deviation) in the patients with TXA and 1079.7 ± 487.1 ml in the second group without TXA. The difference in the total blood loss volume was significant (p < 0.0001). In the group with TXA the consumption of blood transfusion was significantly lower by 50 % (20 vs. 40 units), (p = 0.0004). The patients with TXA also reported a significantly lower consumption of allogeneic blood (p = 0.004), a higher level of postoperative haemoglobin (p < 0.0001) and a lower mean drop of haemoglobin (p < 0.0001). We did not observe any significant differences in the incidence of haematomas (p = 0.644). No higher volume of wound drainage and joint swelling after postoperative day 4 in patients with TXA was found (p = 0.565; p = 0.242). The TXA group did not show a higher rate of surgical revision (p = 1.000). The total economic costs of blood transfusion requirements were significantly lower in the TXA group than in the control group (p = 0.004), including consumption of autologous transfusions and blood salvage (p < 0.0001). DISCUSSION The main effect of the local application of TXA is to reduce bleeding which should result in lower postoperative blood loss and consumption of allogenic blood transfusion. The advantage of the local application of TXA is its easy application and maximum concentration of TXA at the surgical site. In addition, a potential harm associated with a systemic administration of a higher TXA dose is reduced because of only minimal TXA resorption into the circulation. According to a number of recent studies, the local application of TXA achieves comparable results to its intravenous application. The economic benefit of TXA intervention is also worth considering. CONCLUSIONS The local application of TXA is an effective and, simultaneously, safe method to reduce perioperative blood loss and consumption of blood transfusions and also to decrease the costs of hospital stay in the patients after THA. Another advantage of the local application is the need to administer one dose only, whereas at least two doses need to be administered intravenously in order to achieve the same effect. No significant complications were observed in the patients with TXA. According to the recent literature, it is therefore appropriate to include the local application of TXA among the recommended procedures for THA, as is the case in total knee arthroplasty. Key words: tranexamic acid, local application, blood loss, hidden blood loss, THA, total hip arthroplasty, complications.

[Influence of Enhanced Recovery Regime on Early Outcomes of Total Knee Arthroplasty]. / Vliv intenzifikovaného pooperacního rezimu na casné výsledky TEP kolena.

PURPOSE OF THE STUDY Our study compared early outcomes of total knee arthroplasty performed in conventional and enhanced perioperative care regimes, i.e. without the use of Redon drain, with intensified perioperative analgesia and more frequent and intensive rehabilitation regime in the latter. MATERIAL AND METHODS The prospective study included 194 patients (76 men and 118 women) implanted with primary knee endoprosthesis. The mean age was 68.8 (44.7 - 88.0 years). The patients were divided into two groups - the "enhanced" and "conventional" procedures. In the first group, Redon suction drain was not inserted at the end of the surgery, and the patients commenced passive knee mobility exercise of the operated knee immediately after being brought back from the operating theatre. The general anaesthesia was supplemented by a combined femoral nerve block and wound infiltration with local anaesthetics. The second group comprised the patients who underwent conventional surgery, i.e. with the use of drain, without femoral nerve block, with no wound infiltration with local anaesthetics, and without immediate post-operative mobilization of the joint. The evaluation was carried out using regular clinical tools (subjective evaluation, objective examination, questionnaire and Knee Society Score (KSS)). Standard statistical methods were applied to data processing. RESULTS The patients under the "conventional regime" showed a significantly sharper drop in haemoglobin and haematocrit levels, higher consumption of blood transfusion and analgesics during the first three days after the surgery. The patients under the "enhanced regime" showed a better range of joint motion at hospital discharge, flexion in particular (p = 0.001). During the hospital stay no frequent swelling, secretion or wound reddening was reported in any of the monitored groups. In the "conventional" group, however, haematomas were more frequently present. The postoperative checks did not reveal any differences in satisfaction of the patients with the surgery. At the first follow-up examination at the outpatient department the "conventional" group patients more often reported knee pain and a feeling of a swollen knee. Nonetheless, their statements did not correspond with the VAS score. In the period between the 6th and 12th months following the surgery, the differences in the range of motion disappeared. The KSS showed a noticeable improvement in both the groups as against the preoperative values. In the "enhanced" group patients, the score increased dramatically at the beginning, whereas in the "conventional" group, the score was growing slowly and gradually until the last follow-up check after the surgery. The "conventional" group patients more frequently reported infectious complications (surface and deep wound infections: 4 vs. 2 patients) requiring a revision surgery (p = 0.024). DISCUSSION Recently, attention has been drawn to the rapid recovery approach, which eliminated postoperative immobilization and enabled the patient to start exercising already on the day of the surgery, with some patients even walking independently. The individual enhanced recovery regimes differ in details but mostly result in achieving the aim much sooner when compared to the conventional approaches. The patients under the enhanced recovery regimes can accomplish better functional outcomes in the first few months after the surgery than the patients undergoing the surgery under the conventional regime. The routine use of Redon drains in TKA is obviously unnecessary; it tends to be associated with a higher blood loss and a higher risk of prosthetic joint infection. CONCLUSIONS The TKA implant without suction drains combined with intensified perioperative analgesia and intensive postoperative rehabilitation is a safe way to earlier recovery of the function of the operated knee, or, by extension, the lower limb. The described approach is not associated with a higher risk of perioperative complications (bleeding, healing disorders or early infections). Patients also benefit from lower blood losses. Based on the results of our study, we recommend performing the TKA surgeries routinely without drains, with perioperative analgesia and immediate postoperative joint mobilization. Key words: total knee arthroplasty; perioperative care; rapid recovery; drainage; active movement; postoperative outcomes; pain; infection.

[Intra-Articular Application of Tranexamic Acid Significantly Reduces Blood Loss and Transfusion Requirement in Primary Total Knee Arthroplasty]. / Lokální aplikace kyseliny tranexamové významne snizuje mnozství krevních ztrát a spotrebu krevních transfuzí po primární TEP kolena.

PURPOSE OF THE STUDY The aim of this prospective study was to investigate the effect of topical application of tranexamic acid (TXA, Exacyl) on the amount of post-operative blood loss, and blood transfusion requirement in patients undergoing primary total knee arthroplasty (TKA). Attention was paid to early complications potentially associated with TXA administration, such as haematoma, wound exudate, or knee swelling. In addition, the economic benefit of TXA treatment was also taken into account. MATERIAL AND METHODS The study included 238 patients (85 men and 153 women) who underwent primary total knee arthroplasty (TKA) at our department between January 2013 and November 2015. A group of 119 patients (41 men and 78 women) received intraarticular TXA injections according to the treatment protocol (TXA group). A control group matched in basic characteristics to the TXA group also consisted of 119 patients. The average age in the TXA group was 69.8 years, and the most frequent indication for TKA surgery was primary knee osteoarthritis (81.5%). In each patient, post-operative volume of blood lost from drains and total blood loss including hidden blood loss were recorded, as well as post-operative haemoglobin and haematocrit levels. On discharge of each patient from hospital, the size and site of a haematoma; wound exudate, if present after post-operative day 4; joint swelling; range of motion and early revision surgery, if performed, were evaluated. Requirements of analgesic drugs after surgery were also recorded. RESULTS In the TXA group, blood losses from drains were significantly lower than in the control group (456.7 ± 270.8 vs 640.5 ±448.2; p = 0.004). The median value for blood losses from drains was lower by 22% and the average value for total blood loss, including hidden losses, was also lower than in the control group (762.4 ± 345.2 ml vs 995.5 ± 457.3 ml). The difference in the total amount of blood loss between the two groups was significant (p = 0.0001), including hidden blood loss (p = 0.030). The TXA patients had significantly fewer requirements for allogeneic blood transfusion (p < 0.0004), higher post-operative haemoglobin levels (p = 0.014), lower incidence of haematomas (p = 0.0003), and a significantly higher flexion degree on discharge from hospital (p < 0.0001). No higher volume of wound drainage was found (p = 1.000). Only one patient of the TXA group underwent revision surgery due to wound healing disturbance. The total costs of blood transfusion requirements were significantly lower in the TXA group than in the control group (p = 0.0004). DISCUSSION Topical administration allows the antifibrinolytic effect of TXA to act directly at a bleeding site. Its advantages involve easy application, maximum TXA concentration at the site of application, no danger associated with administration of a higher TXA dose and minimal TXA resorption into the circulation. On the other hand, there are no exact instructions for an effective and safe topical application of TXA and some authors are concerned that a coagulum arising after TXA application might affect soft tissue behaviour (healing, swelling, rehabilitation) or result in infection. CONCLUSIONS The study showed the efficacy and safety of topical TXA administration resulting in lower peri-operative bleeding, fewer blood transfusion requirements and higher haemoglobin levels after TKA. The patients treated with TXA had less knee swelling, lower incidence of haematomas and used fewer analgesic drugs in the early post-operative period. The economic benefit is also worth considering. In agreement with the recent literature, it is suggested to add topical TXA application to the recommended procedures for TKA surgery. Key words: tranexamic acid, Exacyl, topical application, intra-articular application, blood loss, hidden blood loss, total knee arthroplasty, complications.

[Cementless Plasmacup-Bicontact total hip arthroplasty. Results of a minimum of ten-year follow-up]. / TEP kycle Plasmacup-Bicontact: výsledky s minimálne 10letým sledováním.

PURPOSE OF THE STUDY: The aim of the study was to analyse the long-term clinical and radiographic results of total hip arthroplasty (THA) with the Bicontact-Plasmacup prosthesis, MATERIAL AND METHODS: In this retrospective observational study, 34 consecutive patients undergoing Bicontact-Plasmacup THA between August 1998 and July 2000 were evaluated. The group included 15 women and 19 men with an average age of 56 years (30 to 67 years). The mean ± SD of follow-up was 132 ± 9 months (122 to 149 months). Patients' satisfaction with the treatment outcome and selected clinical and radiographic features were evaluated. The data were analysed using the concordance test, Spearman's correlation coefficient and chi-square test. RESULTS: At the final follow-up, 94% of the interviewed patients reported satisfaction with the surgery outcome. The mean Harris score was 93 (67 to 98) points, with excellent or very good results in 91% of the patients. Compared with the post-operative radiographs, the mean ± SD value for vertical migration of the acetabular cup was 2.43 ± 3.21 mm (0 to 12 mm) and that for horizontal migration was 0.35 ± 1.0 mm (0 to 4.3 mm). The mean stem subsidence was by 3.87 mm (range, 0.36 to 21.11 mm; SD 4.03). At the final follow-up, all implants showed radiographic stability and absence of radiolucent lines. Early acetabular osteolysis was detected in two patients (5.9 %). In 19 patients (56%) a change in bone architecture, similar to alterations due to weight-bearing adaptation, was seen around the cup following surgery. The stress shielding effect of the femoral component was recorded in 79%, bypass phenomenon in 41 % and pedestal formation under the apex of the stem in 18% of the patients. The mean rate of polyethylene wear measured by the Dorr and Wan method was 0.106 mm per year (range, 0.00 to 0.267 mm) or it was 0.078 mm per year (0.00 to 0.19 mm) when assessed by a modification of the method described by Kang et al. DISCUSSION: The clinical and radiographic findings presented here are in accordance with the relevant literature data. This implant design is associated with a relatively infrequent osteolysis around the cup probably due to a low wear rate of polyethylene and a stable polyethylene liner-metal cup interface. Based on this work and some other studies it can be concluded that a post-operative migration of several millimetres is compatible with a long-term, stable cementless THA. CONCLUSIONS: The Bicontact-Plasmacup THA meets the National Institute for Health and Clinical Excellence (NICE) criteria for a very good implant (ten-year survival rate of over 90%). At 10 years after surgery, however, the first signs of complaints about surgery outcome // dissatisfaction with surgery outcomes were recorded. This may, at least partly, be related to aseptic loosening which is one of the symptoms of particle disease.

Sensory and textural attributes and fatty acid profiles of fillets of extensively and intensively farmed Eurasian perch (Percafluviatilis L.).

Sensory attributes, texture and fatty acid profiles of fillets of Eurasian perch (Percafluviatilis L.) reared under two conditions were compared. Perch were reared either in an extensive pond-based (EC) system in polyculture with carp, or intensively cultured (IC) in a recirculation system. Attributes of raw and cooked fillets of marketable perch (120-150g) were compared. No significant differences were found between groups for odour, flavour, aftertaste, or consistency in subjective evaluation of cooked fillets. The texture profile analysis (TPA) showed raw fillets from the EC group to exhibit higher values of hardness, springiness, cohesiveness, and gumminess than the IC group. Fish from the IC group had a lower content of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) and a higher content of monounsaturated fatty acids (MUFA) in comparison to EC perch. The proportion of iso- and anteiso-SFAs was 2.6% in the EC group and 0.75% in the IC group. The content of n-3 PUFA was lower in IC than in EC, while the content of n-6 PUFA was higher in IC than in EC. The ratio of n-3:n-6 PUFA was 1.42 for the IC group and 2.85 for the EC group.

[Surgical therapy of osteolysis around stable cementless hip arthroplasty]. / Operacní lécba osteolýzy kolem stabilní necementované TEP kycelního kloubu.

PURPOSE OF THE STUDY: The article presents results of surgical treatment of osteolysis around stable cementless THA. MATERIAL AND METHODS: The authors evaluated 18 operated on cases of osteolysis around stable THA of ABG 1 type with a minimal follow-up of 4 years (49-70 months). The group included 6 men and 12 women who were at the time of revision 47 years old (36-56, SD 6.52). The average period between the primary and revision surgery was 45 months (23-66, SD 13.84), the average size of the original cup was 49.6 mm (44-54, SD 3.03), the median thickness of polyethylene was 7.5 mm (4.9-8.9). The average HHS prior to reoperation was 68.5 points (10-98, SD 18.3) and only three hips were completely asymptomatic (3/18, 17%). Polyethylene inlay was replaced twice, both acetabular components in twelve cases, the acetabular and femoral components in four cases. In 16 cases radical debridement and treatment of defects by bone grafting was an important part of surgery. OUTCOMES: By the time of the latest check, in total three revision surgeries were performed (3/18, 17%). Neither of them was necessitated by loosening of the revision cup or use of bone grafts. Revised were both hips after the replacement of polyethylene cup inlay. Stable bone fixation and healing of bone defect was achieved in 15 hips in which the implant replacement was combined with bone grafting (15/16, 94%). The revision cup was on average by 3.16 mm bigger than the original cup (p = 0.001). The average HHS during the latest check was 79 points (p = 0.056). DISCUSSION: In osteolysis around a stable implant, many North-American authors prefer the replacement of polyethylene cup inlay in case of an undamaged well-oriented metal cup with a functional lock. By contrast, the authors of this study in such indication replace the whole acetabular component. This discrepancy may be explained by the ABG 1 THA which often triggers an extensive osteolysis and fails relatively soon. CONCLUSION: Despite a small number of cases the study has proved that the bone bed damaged by osteolysis is able to accommodate a new cementless implant. A necessary part of the surgery is radical debridement and in more extensive defects also bone grafting.

[Is osteolysis associated with a stable total hip replacement asymptomatic?]. / Je osteolýza kolem stabilní TEP kycelního kloubu asymptomatická?

PURPOSE OF THE STUDY: It has been reported that periprosthetic osteolysis in a stable cementless total hip prosthesis is often free from symptoms. The aim of this study is to check this assumption and provide details on the clinical presentation of this troublesome and worrying complication of hip arthroplasty. MATERIAL: Between March 1999 and June 2002, 76 hips in 72 patients underwent revision arthroplasty for periprosthetic osteolysis associated with stable ABG I prostheses. This patient group included 53 females and 19 males. The average age at the time of revision was 49 years (range, 32 to 63). The average time between the primary and revision surgery was 54.6 months (range, 23 to 85). The average cup size was 49.7 mm (range, 44 to 60), the modular 28-mm CoCr head was used in 69 hips, 28-mm ceramic head in six hips, and 22-mm CoCr head in one patient. METHODS: The following characteristics were recorded: gender, age, type of patient, height, weight, symptoms, diagnosis, ERS, CRP, Harris hip score, cup size, abduction angle and extent of bony defects. The data of symptomatic and asymptomatic patients were compared by parametric or non-parametric tests. RESULTS: Before revision, 61 hips (80%) were symptomatic. The patients complained of pain or signs of instability or both, and these complaints were taken as indications for revision surgery. The remaining 15 hips (20%) were asymptomatic. The average period from the primary surgery to the appearance of the first symptoms was 43 months (range, 5 to 80). The average Harris hip score before revision was 68 points (range, 37 to 90) and 82 points (range, 10 to 98) in the symptomatic and asymptomatic patients, respectively (p = 0.002). There were no other significant differences between these patients. DISCUSSION: The results of our study are in agreement with the findings of Hozack et al., but not with those of Maloney et al. and others who have reported that the progression of osteolysis developing in association with hip arthroplasty can be without symptoms. CONCLUSIONS: Osteolysis developing around a stable cementless hip prosthesis is generally symptomatic, with pain being the most frequent symptom. Even without a periprosthetic fracture, osteolysis may seriously impair the function of a joint and comfort of the patient. Since symptomatic patients are likely to see their attending physicians, it is emphasized that attention should also be paid to asymptomatic patients who have prostheses with unsuitable designs or pairings.

[Validity of bone scintigraphy for the diagnosis of periprosthetic complications in hydroxyapatite-coated total hip arthroplasty]. / Prínos trífázové kostní scintigrafie k diagnostice periprotetických komplikací u protézy s hydroxyapatitovým povrchem.

PURPOSE OF THE STUDY: To evaluate the efficacy and usefulness of 99Tc-MDP bone scans for the diagnosis of complications associated with hydroxyapatite- coated total hip prostheses. MATERIAL AND METHODS: 99Tc-MDP bone scans of 42 hips were taken before revision surgery in 41 patients with ABG 1 prostheses. Of these, 26 patients (27 hips) were included in our study on the basis of the following criteria: at least 23 months between the index surgery and scintigraphic examination and the availability of good quality bone scans. The average patients' age at the time of index and revision operations was 45.3 years (range, 32-57; SD, 6.02) and 50.2 years (36-61; SD, 6.01), respectively. The average time between the index surgery and bone scintigraphy was 50.3 months (23-84; SD, 15.9). Two experienced specialists in nuclear medicine, who were unaware of any clinical conclusions, participated in the study. RESULTS: Pre- and intra-operative findings showed aseptic loosening in three cups (3/27, 11 %) and one stem (1/27, 4 %). Four hips were suspected to have an infection on the basis of the positive results of intra-operative culture. In the diagnosis of aseptic loosening, sensitivity, specificity, accuracy, and positive and negative predictive values of bone scintigraphy were 100 %, 57 %, 62 %, 23 %, and 100 %, respectively, for the ABG I cup and 100 %, 52 %, 54 %, 8 %, and 100 %, respectively, for the ABG I stem. These characteristics were 67 %, 96 %, 93 %, 67 %, and 96 %, respectively, for the ABG I cup, when plain X-ray was used for evaluation of aseptic loosening. Specificity, accuracy and negative predictive value of plain X-ray for ABG I stem aseptic loosening were 100 %, 96 %, and 96 %. Bone scintigraphy gave one false positive result of sepsis; on the other hand, none of the four hips with positive intraoperative culture was diagnosed as septic. DISCUSSION: The fact that 99Tc-MDP bone scintigraphy as a method of diagnosing periprosthetic complications has a high sensitivity and a relatively low specificity has often been discussed in the literature. Currently, there are only a few studies on bone scintigraphy investigations of hydroxyapatite-coated prostheses. Some authors report that a slight increase in peri-prosthetic radionuclide activity may persist for up to 8 years which can explain the problematic accuracy of the technique. CONCLUSIONS: 99Tc-MDP bone scintigraphy is an intermediate useful tool for detecting complications of total hip arthroplasty with hydroxyapatite- coating. A negative bone scan almost always suggested the absence of aseptic loosening. However, the value of a positive result was regarded as controversial for the diagnosis of both aseptic and septic complications.

Interaction between two adapter proteins, PAG and EBP50: a possible link between membrane rafts and actin cytoskeleton.

Phosphoprotein associated with GEMs (PAG), also known as Csk-binding protein (Cbp), is a broadly expressed palmitoylated transmembrane adapter protein found in membrane rafts, also called GEMs (glycosphingolipid-enriched membrane microdomains). PAG is known to bind and activate the essential regulator of Src-family kinases, cytoplasmic protein tyrosine kinase Csk. In the present study we used the yeast 2-hybrid system to search for additional proteins which might bind to PAG. We have identified the abundant cytoplasmic adapter protein EBP50 (ezrin/radixin/moesin (ERM)-binding phosphoprotein of 50 kDa), also known as NHERF (Na(+)/H(+) exchanger regulatory factor), as a specific PAG-binding partner. The interaction involves the C-terminal sequence (TRL) of PAG and N-terminal PDZ domain(s) of EBP50. As EBP50 is known to interact via its C-terminal domain with the ERM-family proteins, which in turn bind to actin cytoskeleton, the PAG-EBP50 interaction may be important for connecting membrane rafts to the actin cytoskeleton.

Structural and functional dissection of the cytoplasmic domain of the transmembrane adaptor protein SIT (SHP2-interacting transmembrane adaptor protein).

SIT (SHP2-interacting transmembrane adaptor protein) is a recently identified transmembrane adaptor protein, which is expressed in lymphocytes. Its structural properties, in particular the presence of five potential tyrosine phosphorylation sites, suggest involvement of SIT in TCR-mediated recruitment of SH2 domain-containing intracellular signaling molecules to the plasma membrane. Indeed, it has recently been demonstrated that SIT inducibly interacts with the SH2-containing protein tyrosine phosphatase 2 (SHP2) via an immunoreceptor tyrosine-based inhibition motif (ITIM). Moreover, SIT is capable to inhibit TCR-mediated signals proximal of activation of protein kinase C. However, inhibition of T cell activation by SIT occurs independently of SHP2 binding. The present study was performed to further characterize the molecular interaction between SIT and intracellular effector molecules and to identify the protein(s) mediating its inhibitory function. We demonstrate that SIT not only interacts with SHP2 but also with the adaptor protein Grb2 via two consensus YxN motifs. However, mutation of both Grb2-binding sites also does not influence the inhibitory function of SIT. In contrast, mutation of the tyrosine-based signaling motif Y(168) ASV completely abrogates the ability of SIT to inhibit T cell activation. Co-precipitation experiments revealed that the tyrosine kinase p50(csk) could represent the negative regulatory effector molecule that binds to this motif.

Equal surface dose compensation.

This paper investigates a method of designing and producing an unusual class of compensators. Through use of these compensators one can deliver an even dose to dmax when one is irradiating a sloping contour with a single megavoltage photon field. These compensators are designed not to provide an even dose at midplane in a patient but instead to produce what may conceptually be described as an equal surface dose. (A more accurate but less descriptive term would be equal dmax dose compensator.)

Separating output factor into collimator factor and phantom scatter factor for megavoltage photon calculations.

Output factor has been used in megavoltage dosage calculations because collimator factor and backscatter factor are considered individually indeterminable. Output factor reflects the normalized product of backscatter factor and collimator factor for the most common treatment geometry. A method has been found for independently measuring collimator factors for megavoltage photons. Using a build-up cap of high density tissue equivalent material, we have measured the relative collimator factors for various units with photon energies up to 15 MV. Utilizing measured values for output factor and collimator factor relative backscatter factors have been determined.

Polyethylene-lead tissue compensators for megavoltage radiotherapy.

Tissue compensators afford one the opportunity of producing idealized dose distributions in radiotherapy. We have developed a technique which may be used to produce fast, accurate and inexpensive compensators within a few minutes and requires minimal patient involvement. Three dimensional contour data is acquired using a moire fringe photograph taken at the time of simulation. The photograph is projected to the size needed for the actual compensator and a sketch of the compensator is made. The sketch is placed in a specially designed small portable pantographic unit and the design is traced while the unit cuts the compensator from an indexed polyethylene-lead blank which is premounted on an acrylic tray. The polyethylene-lead material proves to have an ideal combination of properties for compensator construction including relatively high density, ease of machining, good handling characteristics and low cost.

Practical aspects of transmission cord blocks in radiotherapy.

We present the advantages of using partial transmission cord blocks throughout treatment, as opposed to adding full-thickness blocks near the end. Such blocks reduce the risk of block omission or mispositioning and require less total time for construction. We also present an argument for the existence of an optimal width for cord blocks used in mediastinal treatments. A figure of merit has been derived which quantifies the tradeoff between narrow blocks, which increase the variation in dose across the block shadow and the risk of positioning errors, and wide blocks, which may unnecessarily shield potential tumor sites. For 60Co, 4- and 10-MV beams, the figure of merit peaks at block widths of 2.0-2.5 cm at the level of the cord. Effective transmission data for cord blocks constructed of cerrobend are given for those three beams. Quality assurance studies show that transmission through cerrobend blocks can be controlled to the required precision.

Transmission blocks: clinical and biological rationales.

This paper describes the clinical and biological rationales for the use of transmission blocks. Clinical advantages over the use of full-thickness blocks applied part way through the course of therapy include the use of only one set of fields, blocks, and beam calculations, and less complex chart recording. There is a net saving in time required for the preparation and treatment of the patient. There is also a quality assurance advantage since the impact of a potential error in block positioning is reduced. In terms of biological advantages, it is demonstrated that the linear-quadratic iso-effect model can be applied to predict an improvement of up to 10% in the therapeutic ratio if transmission blocks are used instead of full-thickness blocks.

Lung corrections in photon beam treatment planning: are we ready?

This paper reviews reasons cited for and against the use of lung corrections. It is suggested that all the reasons cited for not making corrections are no longer viable. A phantom has been designed to simulate the thorax region of a patient at both CT and radiotherapy radiation energies. With this phantom, lung correction factors for the calculation of tumor dose have been measured for a typical lung cancer treatment regimen, and these results are shown to compare favorably with correction factors computed by all the commonly employed correction algorithms. Some algorithms are better than others, and one of the best is the readily hand-calculable generalized power-law TAR method. It is shown that failure to correct for lung transmission can severely limit the integrity of many interinstitutional studies, especially cooperative clinical trials. It is concluded that lung corrections for the calculation of tumor doses in the thorax region should be gradually introduced over the next several years.