Host parent responses to heterospecific parasite nestling alarm calls are independent of past and current experience with experimental brood parasitism.

Communication between parents and dependent offspring is critical not only during provisioning, but also in antipredator contexts. In altricial birds, a top cause of reproductive failure is nest predation, and alarm calls both by parents and chicks can serve to alert others and increase the likelihood of offspring escaping predation. Understanding the factors that determine the strength of parental antipredator responses to different nestling alarm calls can provide insight into parent-offspring recognition. The prothonotary warbler (Protonotaria citrea), a host of the obligate brood parasite, the brown-headed cowbird (Molothrus ater), never rejects cowbird young and raises the parasite together with its own offspring. To determine whether warbler parents learn cowbird nestling alarm calls, we presented experimentally parasitized or non-parasitized parents with playbacks of conspecific warbler, parasitic cowbird, and a harmless heterospecific control, eastern bluebird (Sialis sialis), nestling alarm calls. We recorded the latency to respond and the number of chips given by members of the resident warbler pair. We found that parents were most likely to respond to warbler nestling alarm calls, least likely to respond to bluebird calls, with a statistically intermediate likelihood of responding to cowbird calls. Critically, current and past parasitism status did not affect the likelihood of response to any playback or the number of chips given, however, currently parasitized parents had greater response latencies to playbacks than non-parasitized parents. These results suggest that warbler parents do not learn cowbird alarm calls from breeding experiences and, in turn, that cowbirds may employ a generalized, bet-hedging alarm call.

Exposure to a mimetic or non-mimetic model avian brood parasite egg does not produce differential glucocorticoid responses in an egg-accepter host species.

Avian obligate brood parasitism, a reproductive strategy where a parasite lays its egg into the nest of another species, imposes significant fitness costs upon host parents and their offspring. To combat brood parasitism, many host species recognize and reject foreign eggs (rejecters), but others are accepters that raise the parasitic progeny. Some accepter hosts may be unable to grasp or pierce parasitic eggs even if they recognize them as foreign eggs in the clutch, whereas other accepters may not have evolved the cognitive skillsets to recognize dissimilar eggs in the nest. Here we assessed the endocrine responses of an accepter host species to model parasitic eggs to address these two alternatives. We experimentally parasitized nests of a locally common host of the brood-parasitic brown-headed cowbird (Molothrus ater), the prothonotary warbler (Protonotaria citrea; a cowbird-egg accepter), with a mimetic or non-mimetic model cowbird-sized egg. Our goal was to determine whether they perceived the non-mimetic egg as a greater stressor by measuring circulating corticosterone levels. We added eggs to nests during the incubation stage and obtained blood plasma samples from females on the nest 2 h later, using females with unmanipulated clutches as controls. Incubating females showed no differences in baseline plasma corticosterone levels between our different treatments. We conclude that exposure to foreign eggs does not activate the hypothalamic-pituitary-adrenal axis of prothonotary warbler hosts in this experimental paradigm.

[The S2k guideline: Indications for knee endoprosthesis : Evidence and consent-based indications for total knee arthroplasty]. / S2k-Leitlinie: Indikation Knieendoprothese : Evidenz- und konsensbasierte Indikationsstellung in der Knie-Endoprothetik (EKIT-Knie).

Total knee arthroplasty (TKA) is one of the most frequent surgical procedures in orthopaedic surgery. Until now there have not been any standardized indication criteria, which might contribute to the large geographical differences in the frequency of TKA. This guideline aims to consent minimal requirements (main criteria), additional important aspects (minor criteria), as well as relative and absolute contraindications for TKA. The following main criteria have been consented: knee pain, radiological confirmation of osteoarthritis or osteonecrosis, inadequate response to conservative treatment, adverse impact of knee disease on the patient's quality of life and the burden of suffering due to the knee disease. Relative contraindications have been consented as severe general disease with reduced life expectancy and a BMI ≥40; absolute contraindications are an active infection and if the patient is not able to undergo major surgery.

[Incidence of knee injuries : Numbers for outpatient and inpatient care in Germany]. / Inzidenz von Kniegelenkverletzungen : Zahlen für die ambulante und stationäre Versorgung in Deutschland.

BACKGROUND: Musculoskeletal illnesses and injuries are among the most common ailments in the Federal Republic of Germany. In 2008 they generated costs of nearly 29 billion euros. Figures about their incidence and prevalence are necessary for a demand-oriented planning of future patient-centred care. METHOD: Pseudonymised data of 3.8 million people insured by AOK Baden-Württemberg between 2008 and 2013 were evaluated. The diagnoses were assigned to nine injury groups. For outpatient care confirmed diagnoses were considered, and for inpatient care both primary and secondary diagnoses were considered. For all patients with structural knee injuries, it was evaluated whether they made use of one of five eligible treatment paradigms either in the quarter in which they were injured or in the following quarter. RESULTS: 418,257 patients were treated in 2013 for at least one new-onset injury (10.9 % of all insurees); 86,783 insurees (2.3 % of all insurees) had a newly occurring knee injury. The vast majority of the patients were treated by specialist doctors. While magnetic resonance imaging clearly increased during the observation period, the incidence of surgical therapy did not change. Striking are the different age distributions regarding the types of injuries, with a high injury incidence amongst young men and a significant increase in injuries between 2008 and 2013, especially amongst women. CONCLUSION: For the first time, the data quantify the knee injury incidences of a large cohort in Germany. They show which inpatient and outpatient health care services have been claimed and that an age- and gender-adapted prevention and an increased awareness are needed.

Preservation of the PCL when performing cruciate-retaining TKA: Is the tibial tuberosity a reliable predictor of the PCL footprint location?

PURPOSE: Reconstruction of the joint line is crucial in total knee arthroplasty (TKA). A routine height of tibial cut to maintain the natural joint line may compromise the preservation of the PCL. Since the PCL footprint is not accessible prior to tibial osteotomy, it seems beneficial to identify a reliable extraarticular anatomic landmark for predicting the PCL footprint and being visible within standard TKA approach. The fibula head predicts reliably the location of PCL footprint; however, it is not accessible during TKA. The aim of this study now was to analyze whether the tibial tuberosity can serve as a reliable referencing landmark to estimate the PCL footprint height prior to tibial cut. METHODS: The first consecutive case series included 216 CR TKA. Standing postoperative lateral view radiographs were utilized to measure the vertical distance between tibial tuberosity and tibial osteotomy plane. In the second case series, 223 knee MRIs were consecutively analyzed to measure the vertical distance between tibial tuberosity and PCL footprint. The probability of partial or total PCL removal was calculated for different vertical distances between tibial tuberosity and tibial cutting surface. RESULTS: The vertical distance between the tibial tuberosity and tibial cut averaged 24.7 ± 4 mm. The average vertical distance from tibial tuberosity to proximal and to distal PCL footprint was found to be 22 ± 4.4 and 16 ± 4.4 mm, respectively. Five knees were considered at 50% risk of an entire PCL removal after CR TKA. CONCLUSIONS: Current surgical techniques of tibial preparation may result in partial or total PCL damage. Tibial tuberosity is a useful anatomical landmark to locate the PCL footprint and to predict the probability of its detachment pre-, intra-, and postoperatively. This knowledge might be useful to predict and avoid instability, consecutive pain, and dissatisfaction after TKA related to PCL insufficiency. LEVEL OF EVIDENCE: III.

[Dorsal sagittal knee joint stability after endoprosthetic knee arthroplasty : Influence of preoperative joint stability and the type of implanted prosthesis]. / Dorsale sagittale Kniegelenkstabilität nach endoprothetischem Kniegelenkersatz : Einfluss der präoperativen Gelenkstabilität und des implantierten Prothesentyps.

BACKGROUND: Anterior knee pain is a known complication after implantation of a prosthesis and a possible reason is a posterior knee joint instability; however, the influence on postoperative stability is just as unknown as the possible influence of the type of prosthesis on postoperative stability. AIM: This study investigated two possible preoperative and intraoperative influencing factors by determination of the preoperative joint stability and type of prosthesis.

Determination of total cadmium, lead, arsenic, mercury and inorganic arsenic in mushrooms: outcome of IMEP-116 and IMEP-39.

The Institute for Reference Materials and Measurements (IRMM) of the Joint Research Centre (JRC), a Directorate General of the European Commission, operates the International Measurement Evaluation Program (IMEP). IMEP organises inter-laboratory comparisons in support of European Union policies. This paper presents the results of two proficiency tests (PTs): IMEP-116 and IMEP-39, organised for the determination of total Cd, Pb, As, Hg and inorganic As (iAs) in mushrooms. Participation in IMEP-116 was restricted to National Reference Laboratories (NRLs) officially appointed by national authorities in European Union member states. IMEP-39 was open to all other laboratories wishing to participate. Thirty-seven participants from 25 countries reported results in IMEP-116, and 62 laboratories from 36 countries reported for the IMEP-39 study. Both PTs were organised in support to Regulation (EC) No. 1881/2006, which sets the maximum levels for certain contaminants in food. The test item used in both PTs was a blend of mushrooms of the variety shiitake (Lentinula edodes). Five laboratories, with demonstrated measurement capability in the field, provided results to establish the assigned values (Xref). The standard uncertainties associated to the assigned values (uref) were calculated by combining the uncertainty of the characterisation (uchar) with a contribution for homogeneity (ubb) and for stability (ust), whilst uchar was calculated following ISO 13528. Laboratory results were rated with z- and zeta (ζ)-scores in accordance with ISO 13528. The standard deviation for proficiency assessment, σp, ranged from 10% to 20% depending on the analyte. The percentage of satisfactory z-scores ranged from 81% (iAs) to 97% (total Cd) in IMEP-116 and from 64% (iAs) to 84% (total Hg) in IMEP-39.

[What do patients in Germany expect from their total knee arthroplasty?]. / Was erwarten Patienten in Deutschland von ihrer Knieendoprothese?

INTRODUCTION: Only 84 % of patients are satisfied with the operative result after total knee arthroplasty. A relevant reason is non-fulfilled preoperative expectations. Non-fulfilled preoperative expectations cannot be influenced postoperatively. So a knowledge of preoperative expectations and their influential factors is essential. The following study analyses the expectations and influential factors in patients before total knee arthroplasty in Germany. MATERIAL AND METHODS: On the day before total knee replacement in 104 patients the following data were collected: school leaving level, comorbidities, articular knee function, psychological mood, health-related quality of life, and preoperative expectations. Statistical evaluation was done by factor analyses of expectations and independent variables, and correlation and regression analyses. RESULTS: The following 4 factors of expectations resulted from the factor analyses: (i) relief of pain, (ii) increase of range of motion of the knee, (iii) better mobility, and (iv) better integration in social activities. In general patient expectations on the effects of a total knee replacement are high. Age and better integration in social activities correlate negatively, as also do age and better mobility. Body mass index and better integration in social activities correlate positively. The following formula analyses the expectations of better integration in social life: social expectations = 116-0.991 × age. DISCUSSION: For the first time this study determines expectations and influential factors of patients who undergo a total knee replacement in Germany. By knowing the interaction of satisfaction and preoperative expectations, this knowledge is an essential condition to increase satisfaction after total knee replacement in the German population. Collecting the preoperative expectations of patients has to be an indispensable feature of the clinical practice in orthopaedic surgery.

Alteration of the patellar height following total knee arthroplasty.

INTRODUCTION: Patellofemoral related complications after total knee arthroplasty (TKA) remain clinically relevant. The hypothesis of the present study was that the patellar height changes more than 10% of its preoperative height after TKA. Possible influences of age, gender, side and navigation system on patellar height were evaluated separately in subgroups. MATERIALS AND METHODS: A total of 107 knees were enrolled after primary TKA. The patellar height was determined for each patient preoperatively, 1 week and 1 year postoperatively on routinely performed standing lateral view radiographs at 30° knee flexion. Insall-Salvati index (ISI), modified Insall-Salvati index (MIS) as well as Miura-Kawamura index (MKI) were determined for the whole cohort. RESULTS: One week after TKA the ISI, MIS and MKI changed by more than 10% in 24 (22%), 33 (30%) and 54 (50%) cases, respectively. Moreover, the 1 year follow-up revealed a decrease or increase of ISI in 30 (28%), MIS in 47 (44 %) and MK in 65 (61%) knees. The frequency of patella alta, norma and baja preoperatively as well as 1 week and 1 year postoperatively were not significantly different. Significant differences of patellar height changes were not noted between the defined subgroups. CONCLUSIONS: The present study demonstrates that TKA leads, at 1 week and 1 year follow-up, to patellar height alteration more than 10% in a significant number of knee joints. However, with the use of ISI and MIS the changes of patellar height did not exceed the defined thresholds to be classified as patella alta or baja.

Joint line changes after primary total knee arthroplasty: navigated versus non-navigated.

PURPOSE: Navigation has been introduced to achieve more accurate positioning of the implants after TKA. The scientific attention was mainly paid on limb alignment rather than restoration of the natural joint line. The aim of our study was to compare the accuracy of the joint line restoration in primary TKA with and without navigation. We hypothesized that joint line reconstruction in navigated TKA is more accurate. METHODS: A total of 493 primary TKAs operated in a single medical centre were consecutively selected and divided into two groups. 206 cases were performed computer assisted (BrainLab CI-System), whereas 287 knees were implanted conventionally. For both groups, the joint line position of the knee was determined on standardized calibrated standing pre- and postoperative digital radiographs in ap view by a modified method of Kawamura et al. A joint line shift of more than 8 mm was defined as outlier. RESULTS: In the conventional group, the joint line shift averaged 0.7 mm (±4.4 mm), whereas the findings in the computer-assisted cases were in average 0.6 mm (±4.5 mm). The joint line was located above 8 mm in 6 % of non-navigated versus 6.8 % of navigated primary TKAs. There were no statistically significant differences of joint line shift between the different component types. A statistically significant relation was not found between joint line shift and leg alignment changes. CONCLUSIONS: Conventional surgical technique allows a precise joint line reconstruction in primary TKA. Navigation did not improve the joint line reconstruction. LEVEL OF EVIDENCE: Diagnostic study, Level III.

[Satisfaction after total knee arthroplasty. Comparison of 1990-1999 with 2000-2012]. / Zufriedenheit nach Knietotalendoprothesenimplantation. Vergleich 1990-1999 mit 2000-2012.

Total knee arthroplasty (TKA) is one of the most common operations in orthopedic surgery worldwide but despite being mainly successful only 81 % of patients are satisfied with the final result. The following systematic review compared patient satisfaction and analyzed the causal connections and influencing factors after TKA between 1990-1999 and 2000-2012. From 1990 to 1999 a total of 81.2 % of patients were satisfied after TKA and in the period 2000-2012 patient satisfaction increased to 85 %. Influencing factors on postoperative satisfaction derived from the 25 publications included in the study were consistently body-mass index, patient expectations, pain, joint function and mental factors. A lack of satisfaction scores and different designs resulted in difficulties in comparing the studies and were subsequently limitations of this study.

Precision of Ci-navigated extension and flexion gap balancing in total knee arthroplasty and analysis of potential predictive variables.

INTRODUCTION: The aim of this study was to evaluate the accuracy of final limb alignment and flexion-extension and medial-lateral gap balancing in computer navigated total knee arthroplasty and to analyze various possible predictive variables that may affect the gaps in computer navigated knee arthroplasty. MATERIALS AND METHODS: The DePuy Ci system, a nonimage-based passive optical computer navigation system, was used in 225 patients with knee osteoarthritis to assist for the total knee arthroplasty. From the raw data the Ci-verified pre- and postoperative leg axis in extension, angle of tibia and femur resection, the flexion and extension angle, the medial and lateral extension and flexion gaps were extracted; and differences in gaps were calculated and subjected to statistical analysis. Leg alignment and implant position were determined only by the navigation system. Preoperative variables were evaluated for their impact on the final flexion/extension and medial/lateral gaps achieved. RESULTS: Though the preoperative femoro-tibial coronal alignment had a large variance, postoperatively 98.22% of the knee was found to be between -3° and +3° in the coronal limb alignment axis. The Ci-verified femoral and tibial cuts in the coronal plane showed a good accuracy. The sagittal alignment of the femoral cut ranged from 8.20° flexion to 3.20° of extension. Rectangular extension and flexion gaps were achieved with ≤3 mm of difference in gaps on medial and lateral sides in 98 and 93% of knees, respectively. Difference between extension and flexion gaps on the medial side was ≤3 mm in 83% and on the lateral side in 84% of the knees. Of all the possible predictive variables analyzed, Pearson correlation and multiple regression analysis showed significant correlation only between the medial-lateral gap difference in extension and the Ci-verified femoral cut, tibial cut and limb axis, all in the coronal plane. CONCLUSION: Computer-assisted navigated total knee replacement allows for accurate gap balancing that is not dependent on the various pre- and intraoperative factors mentioned, including age, sex, Range of motion preoperative deformity and grade of osteoarthritis. The Ci-calculated and verified tibial, and femoral cuts are the only possible factors affecting the extension gap.

Scintigraphic evaluation of rhBMP-2-biocoated implants reveals no ectopic bone formation.

The main objectives of the study described below were of two-fold nature: (1) to examine if rhBMP-2-biocoated implants in a pig model could lead to ectopic bone formation and (2) if quantitative and/or qualitative differences could be found between adhesively and covalently bonded BMP II using the scintigraphic method. In order to examine these central questions, 26 Göttingen minipigs were allocated to three groups with a control group (n=7) and two study groups (n=9 each) receiving one of three implant types: (a) chromosulfuric acid treated titanium surface as control, (b) non-covalently bonded BMP-2, and (c) covalently bonded and immobilized rhBMP-2. Each animal received four barbell-shaped implants, one in the proximal and distal metaphysis of each femur. The scintigraphic analyses were conducted after four, eight, and 12 weeks postoperatively. The visual (qualitative) analysis failed to show ectopic bone formation in any of the three groups. The statistical analysis of the relative values for bone formation yielded no significant differences between the groups, although the limitation in the applied methods do not enable one to draw conclusions regarding the histomophometric results.

[Biochemical analysis of the synovial fluid of the shoulder joint in patients with and without rotator cuff tears]. / Biochemische Analyse der Synovialflüssigkeit bei Patienten mit und ohne Rotatorenmanschettendefekt.

AIM: The biochemical changes associated with rotator cuff tearing are still unclear. The aim of this study is to assess whether concentrations of matrix metalloproteinase in the synovial fluid are specifically altered in shoulders with torn rotator cuff tendons. PATIENTS AND METHOD: Synovial fluid was extracted via arthroscopy in 21 patients with complete rotator cuff tears (RCTs). The control group was composed of 21 patients without complete tears. The catabolic cartilage metabolism markers MMP-1 (collagenase), MMP-3 (stromelysin1) and MMP-13 (collagenase3) were quantified by an ELISA test and these results were then statistically analysed using SAS. RESULTS: The mean concentration of the 21 samples with rotator cuff tears shows a higher concentration of MMP 3 (2601.73 ng/mL vs. 1775.67 ng/mL) and MMP 13 (2.69 ng/mL vs. 2.35 ng/mL) as well as a significantly higher concentration of MMP 1 (p=0.0047) in the control group. CONCLUSIONS: A significant variation in the concentration of catabolic cartilage enzymes in the synovial fluid in patients with and without rotator cuff tears could not be found. Nonetheless, there is a bias for the MMP-3 and MMP-13 values, which makes a conductive influence in the aetiology of osteoarthritis probable.

[Knee arthroplasty revision]. / Endoprothesenwechsel am Kniegelenk.

The number of knee arthroplasties in Germany increases about 6.8% annually. Parallel to the increasing number of primary total knee arthroplasties (TKA) the frequency of TKA revision surgery also goes up and is a growing challenge for orthopedic surgeons. The main reason for revision arthroplasty is aseptic or septic mechanical loosening of the implant. Other reasons are persisting pain, instability or limited range of motion. The aim of preoperative evaluation by examination, x-ray control and serum tests is to understand the mechanism of implant failure. Besides the stable mechanical fixation of the new implant, reconstruction of limb alignment, joint line and balanced extension and flexion gaps must be achieved. Bone defects also need to be reconstructed. Modular revision implants and bone grafts support the surgeon in restoring a pain-free knee function.

[Osteoathritis after SLAP Lesion? Clinical and arthro-MRI evaluation after arthroscopic SLAP refixation]. / Die SLAP-Läsion als Präarthrose? Klinische und MR-Arthrografie-Ergebnisse nach arthroskopischer Refixation einer SLAP-II-Läsion.

INTRODUCTION: The development of glenohumeral osteoarthritis is sufficiently described after instability and rotator cuff pathologies. The purpose of this work was to evaluate a coherency between glenohumeral osteoarthritis and SLAP lesions by means of MR arthrography which has not been described up to now in the literature. MATERIAL AND METHODS: 20 patients with a SLAP lesion type II were treated with arthroscopic SLAP repair. MR arthrography was performed after intra-articular administration of diluted gadolinium (after positive vote of the ethics committee) after a mean FU of 36 months (26 to 54 months). The MR arthrography data were analysed by 3 investigators (two radiologists, one orthopaedic surgeon) in consensus. Osteoarthritis was graded according to the modified Outerbridge classification for MRI. Besides image quality and artifacts, adhesions from the tendon to the bone and the rotator cuff were evaluated. Intraoperative documented findings were used for comparison. The clinical investigation encompassed Roweand Constant score, clinical investigation of instability and SLAP lesion (O'Brian test, SLAP apprehension test) as well as the subjective contentment. The statistical evaluation was performed with SAS reverse. RESULTS: In 12 of 20 cases an increase of glenohumeral osteoarthritis was seen, in 4 cases a circumscribed entire cartilage defect appeared in the MRI. Osteoarthritis did not correlate with the subjective and objectively collected clinical results or the aetiology of the SLAP lesion at the time of the re-examination. Results of the MR arthrography revealed that, in six cases, the biceps anchor did not show proper bony ingrowth. Nonetheless, these cases do not correlate with a poorer clinical result. CONCLUSION: Due to the small case number a correlation between SLAP lesion and osteoarthritis cannot be postulated statistically, however, the results still indicate a trend which should be pursued in the long-term course.

[Determining the indication for primary total hip and knee replacement. Results of external quality assurance of over 270,000 primary total hip and knee replacements]. / Indikationsstellung in der primären Hüft- und Kniegelenkendoprothetik. Ergebnisse der externen Qualitätssicherung von über 270.000 primären Hüft- und Kniegelenkendoprothesen.

BACKGROUND: The German mandatory quality assurance programme collects data from all primary total hip and knee replacements. The quality of the indication is measured by clinical and radiological criteria. The results were analysed in terms of differences in establishing the indication subject to patient and hospital characteristics. MATERIALS AND METHODS: Data on more than 270,000 primary total hip and knee replacements that were operated in 2006 in Germany were analysed concerning differences in the quality of the indication subject to age, gender, hospital volume and density of population and hospitals (metropolitan vs rural areas). The statistical analysis was done by exact Fisher's test. RESULTS: The quality of the indication was statistically significantly better in men, patients 60 and older, in rural areas and in high volume hospitals (50 and more joint replacements per year). DISCUSSION: Data of this mandatory German quality assurance programme are useful to describe differences in medical care. The results are valid and complete. An exact analysis of the reasons for these differences is difficult though. Data focus is on quality assurance and represent only in-hospital results. CONCLUSION: Further analyses are necessary to ascertain whether the differences in quality of care are deficits or only variances in medical care.

[Shoulder injuries in overhead athletes: utility of MR arthrography]. / Schulterverletzungen des Uberkopfsportlers: Wertigkeit der MR-Arthrografie.

INTRODUCTION: The goal of this work was to assess the accuracy of the MR-Arthrografie in the evaluation of over head athletes injuries in comparison with athroscopy. MATERIAL AND METHODS: In 29 patients (middle age: 30 years, 21 male, 8 female, age 16 - 53 years) with persistent pain after conservative therapy an Arthro-MRI with intraarticular application of gadolinum was performed prior to arthroscopic surgery. The MRI was retrospectivly analysed of three examiners independently from one another. The result were compared to the results of the Arthroscopy. Interrater Reliability was calculated by using of Cohens Kappa. RESULTS: The MR-Arthrography could demonstrate 8 of 9 (88.9 %) partial tears of he rotator cuff. All SLAP (Superiores Labrum from Anterior to Posterior) Lesions as well as all bankart type Lesions were recognized through the MR-Arthrography. However, dependent upon the experience of the examiner in a span between 33.3 % (fellow radiologist) and 93.3 % (consultant radiologist). We found a high agreement between consultant radiologist and shoulder surgeon with Kappa of 0.79 for rotator cuff tear-, 0.86 for Bankart- and 0.82 for SLAP-Läsionen.

On the outcome of computer-assisted total knee replacement.

A number of studies have reported a significant improvement of the postoperative alignment, when computer-navigated total knee arthroplasty (TKA) was compared with conventional techniques. However, no studies are available on the functional and patient-relevant outcomes after computer-assisted knee replacement. In a prospective, randomized trial comparing 27 computer-assisted TKAs with 25 conventional implantations, the Knee Society Score was used to assess functional status, and the WOMAC questionnaire was used to record the disease-specific, patient-relevant outcome. At a twelve-month follow-up no significant difference was detected between the two patient groups in either the scores or the number of complications and range of postoperative knee flexion. The results are in agreement with those reported in other studies on the effect of conventional TKA. With the patient group of this size it can be concluded that computer-navigated TKA gives short-term resuits comparable with those achieved by conventional methods of implantation.