Comparison of anatomic axes with a navigated functional rotation axis determined by ligament tension for rotational femoral component alignment in cadaver knee arthroplasty.

INTRODUCION: The malimplantation of the total knee arthroplasty (TKA) components is one of the main reasons for revision surgery. For determining the correct intraoperative femoral rotation several anatomic rotational axes were described in order to achieve a parallel, balanced flexion gap. In this cadaveric study prevalent used rotational femoral axes and a navigated functional rotational axis were compared to the flexion-extension axis defined as the gold standard in rotation for femoral TKA component rotation. MATERIALS AND METHODS: Thirteen body donors with knee osteoarthritis (mean age: 78.85 ± 6.09; eight females and five males) were examined. Rotational computer tomography was performed on their lower extremities pre- and postoperatively. Knee joint arthroplasties were implanted and CT diagnostics were used to compare the preoperatively determined flexion-extension axis (FEA). The FEA is the axis determined by our surgical technique and serves as an internal reference. It was compared to other axes such as (i) the anatomical transepicondylar axis (aTEA), (ii) the surgical transepicondylar axis (sTEA), (iii) the posterior condylar axis (PCA) and (iv) the functional rotation axis (fRA). RESULTS: Examination of 26 knee joint arthroplasties revealed a significant angular deviation (p*** < 0.0001) for all axes when the individual axes and FEA were compared. aTEA show mean angular deviation of 5.2° (± 4.5), sTEA was 2.7° (± 2.2), PCA 2.9° (± 2.3) and the deviation of fRA was 4.3° (± 2.7). A tendency towards external rotation was observed for the relative and maximum axis deviations of the aTEA to the FEA, for the sTEA and the fRA. However, the rotation of the posterior condylar axis was towards inwards. CONCLUSIONS: All axes showed a significant angular deviation from the FEA. We conclude that the presented technique achieves comparable results in terms of FEA reconstruction when compared with the use of the known surrogate axes, with certain deviations in terms of outliers in the internal or external rotation.

Evaluation of ostarine as a selective androgen receptor modulator in a rat model of postmenopausal osteoporosis.

Selective androgen receptor modulators (SARMs) have shown beneficial effects on muscle wasting, general physical function and bone properties in male mammals. However, data on the effects of SARMs in postmenopausal osteoporotic bone are scarce. We evaluated the effects of the SARM drug ostarine on postmenopausal osteoporotic bone in a rat osteoporosis model. Ovariectomy was performed on 46 of 56 3-month-old female Sprague-Dawley rats. Eight weeks after ovariectomy, ostarine was orally administered daily for 5 weeks in dosages of 0.04 (low, OVX + Ost. 0.04), 0.4 (intermediate, OVX + Ost. 0.4), and 4 mg/kg (high, OVX + Ost. 4) body weight. Another ovariectomized group received no ostarine. Lumbar vertebrae and femora were removed for biomechanical, gene expression, ashing, and computer tomography analyses. Low dose showed no effects. The effects of intermediate and high doses were comparable overall. Improvements were mainly seen in structural properties such as bone mineral density and bone volume density. However, the effects in femora were superior to effects in vertebrae. Ostarine treatment for 5 weeks did not improve significantly biomechanical properties. mRNA expression of the receptor activator of NF-κB ligand decreased after treatment, and uterine weight increased. Serum levels of phosphorus increased following ostarine treatment in intermediate and high-dose groups. Short-term treatment of osteoporotic bone with ostarine leads to improvement of several microstructural bone indices. While we did not observe changes in biomechanics, it is conceivable that longer treatment may also improve biomechanical properties. Further studies are needed to characterize longer time effects and side effects of ostarine in osteoporosis.

[Revision arthroplasty of the hip: modularity of neck and metaphyseal components]. / Revisionsendoprothetik der Hüfte: Modularität von Hals- und Metaphysenkomponente.

BACKGROUND: Modular parts in femoral components used for hip arthroplasty are reported to be predilection sites for mechanical failure. The possible benefit of their use is therefore controversial. PATIENTS AND METHOD: We report the outcome of 97 revision hip arthroplasties using a non-cemented femoral component with a modular metaphyseal part and an interchangeable neck (Profemur). The femoral defects treated included Paprosky types I-III. The average follow-up was 5 years (range 3-10 years). DISCUSSION: No mechanical failure of the modular parts and taper connections has been observed so far. The percentage of patients with a balanced leg length increased from 32% preoperative to 65% postoperative. The mean leg length discrepancy could be reduced from 1.4 cm preoperative to 0.5 cm postoperative. A total of 5 re-revisions were required, including 2 cases of infection. The cumulative survival of the implants due to aseptic loosening was 96.5%. CONCLUSION: Because of the achieved results the use of the modular stem investigated in this study can be classified as safe and effective for revision hip arthroplasty. The interchangeable neck proved to be a useful completion of the revision system.

[Influence of cyclops syndrome after anterior cruciate ligament reconstruction on the functional outcome]. / Einfluss des Zyklops-Syndroms nach vorderer Kreuzbandplastik auf das klinische Ergebnis.

BACKGROUND: A review of recent reports concerning the functional outcome after treatment for Cyclops syndrome can produce contradictory results. Therefore, the purpose of this study was to evaluate the functional outcome of our patients treated for Cyclops syndrome after anterior cruciate ligament reconstruction. METHODS: Between 1998 and 2006 ten patients were followed for the occurrence of a Cyclops syndrome. The Lysholm score, Marshall score and Tegner activity score was used for clinical evaluation at final follow up; in addition, a subjective assessment of knee function and knee pain on a visual analogue scale was registered. Knee stability was measured using the KT-1000 arthrometer. Results were compared with a control group of 24 uneventful ACL reconstructions. RESULTS: Revision arthroscopy for symptomatic extension block was performed after a mean of 6.8 months. After a mean follow-up of 23 months after second surgery all patients' regained full range of motion. The mean Lysholm score and Marshall score was 85 and 41 after Cyclops syndrome and 92 and 46 for the control group. After Cyclops syndrome patients experienced a significantly increased ACL transplant laxity but no significant difference was found concerning patient's subjective rating of knee function and knee pain. CONCLUSION: Although patients subjective rating of knee function and knee pain was nearly identical in both groups objective knee scores disclosed impaired knee function in our patients treated for Cyclops syndrome.

[Promoting Young Talents in Trauma Surgery through Students-On-Call]. / Nachwuchsförderung in der Unfallchirurgie durch studentischen Rufdienst.

BACKGROUND: Due to restrictions on admission to medical school, changing claims to an optimized work-life balance and occupational perspectives, surgical professions in particular are struggling with strategies to motivate young academics. Surgical disziplines aim towards a profound transfer of knowledge and pique student's interest by ensuring a sustainable education at university. OBJECTIVES: The goal of this study was to evaluate a Students-On-Call System (SOCS) and to identify a financial benefit. MATERIALS AND METHODS: In this study the SOCS was compared pre-/postevaluation using questionnaires and the supporting X­rays within a curricular teaching module of orthopedic trauma surgery, with students in the fourth semester of specialism and those in the practical semester at medical school. RESULTS: The students of SOCS showed significantly better results prior to the course and afterwards than the two other groups. By establishing SOCS medical students get involved into the treatment of emergency patients in the trauma resuscitation unit (TRU) and operating room (OR). Students get the chance to enhance their comprehension of diagnostics, therapy and decision making in surgical context. This highly valuable traineeship combines a minimized teaching effort with an effective motivation of young academcis for the surgical profession. A SOCS has reduced the workload of medical colleagues. Establishing SOCS spare the residents being on call and results in reduced costs of 23,659.86 Euro per year. CONCLUSION: The results presented show that the SOCS leads to an excellent cost-benefit balance, which has been established in multiple surgical departments at the medical school of the University of Göttingen. Apart from practice-oriented surgical teaching, the SOCS is a way of promoting successful young talent saving resources in the medical on-call services.

Acute influence of beta-adrenergic antagonists on left ventricular diastolic function: contrasting results after administration of celiprolol and metoprolol.

Various beta-adrenergic receptor antagonists have different effects on myocardial function. A clinical study was performed in 30 patients with symptomatic coronary artery disease and systemic hypertension to compare the effects of single intravenous doses of 0.15 mg/kg celiprolol (n = 16) (third generation beta-blocking agent) and metoprolol (n = 14) (second generation) on left ventricular diastolic function. Parameters derived from pressure, volume, flow, time intervals and their combination were used to characterise diastolic function. After celiprolol administration, parameters of diastolic myocardial function improve (dp/dtip-; relaxation time constant T1, peak filling rate PFR; first-third filling rate FF1/3 or diastolic wall stress-time integral Sigdiasc) or remain unchanged. In contrast, after metoprolol administration parameters of diastolic function seem to be deteriorated (dp/dtip-, T1; Sigdiasc). This indicates an improvement in myocardial relaxation and filling under the influence of celiprolol but not under metoprolol. The left shift of the pressure-volume loops after celiprolol (n = 13), in contrast to metoprolol, supports this interpretation. Celiprolol did not show any deterioration of diastolic function in patients with coronary heart disease and arterial hypertension under these acute conditions.

[Evaluation of regional wall motion abnormalities of the heart--comparison with doppler tissue echocardiography, MR-tagging and levocardiography]. / Beurteilung regionaler Wandbewegungsstörungen des Herzens--Vergleich von Gewebe-Doppler-Echokardiographie, MR-Tagging und Lävokardiographie.

PURPOSE: To compare the visual analysis of magnetic resonance imaging (MRI) with the tagging technique and Doppler tissue echocardiography with invasive ventriculography in detecting and quantifying regional left ventricular wall motion abnormalities. MATERIALS AND METHODS: Sixteen patients with coronary artery disease and a history of prior myocardial infarction underwent invasive ventriculography, Doppler tissue echocardiography and MR-tagging within one week. Regional wall motion abnormalities (WMA) were detected in all patients. WMA were graded as normal = 1; hypokinetic = 2; akinetic = 3; or dyskinetic = 4. For agreement between MRI, echocardiography, and ventriculography the kappa coefficient (kappa) according to Cohen was calculated. RESULTS: The kappa coefficient (kappa) was 0.962 for agreement between MRI and echocardiography and 0.602 for agreement between MRI and ventriculography as well as between echocardiography and ventriculography. CONCLUSION: Reliable analysis of regional left ventricular wall motion abnormalities is feasible using visual analysis of MR-tagging. MRI and Doppler tissue echocardiography detect more WMA than invasive ventriculography and grade them as more severe.

Diastolic heart function--pathophysiology, characterization, and therapeutic approaches.

In recent years diastolic cardiac function has attracted increasing attention since parameters of diastolic function were found to be altered earlier or more specifically than parameters of systolic function. Diastolic cardiac function is determined by both active (muscular relaxation, redistribution of calcium, synchronization, etc.) and passive (myocardial structure, fibrosis, etc.) factors. As a consequence, a comprehensive assessment of diastolic cardiac function cannot be based on one single parameter. For a complete analysis of diastolic function it is necessary to perform invasive diagnostic procedures involving the measurement of atrial and ventricular pressures, as well as the registration of volume changes with a high time resolution. In addition, it is necessary to measure wall thickness and ventricular configuration, so that apart from filling parameters the stress-strain relationship can be obtained. Noninvasive techniques (Doppler echocardiography, radionuclear ventriculography, apexcardiography) may suggest alterations in diastolic function as well. They ought to be complemented by additional diagnostic procedures (pulmonary pressure, stress testing, etc.). Therapy must consider potentially harmful effects on diastolic function parameters, particularly if changes in myocardial oxygen consumption may result (heart rate, parietal wall stress). Calcium antagonists (verapamil, diltiazem, nifedipine), phosphodiesterase inhibitors (milrinone), beta-adrenergic agonists and antagonists with vasodilating effects (e.g., celiprolol) all have beneficial effects on diastolic myocardial function. A range of diastolic function parameters is being reviewed in the following paper. Their role in the estimation of cardiac function and their responsiveness to therapy in hypertrophy, cardiomyopathy, and coronary heart disease is being discussed.

[The treatment of patellar dislocation: a systematic review]. / Die Therapie der Patellaluxation: eine systematische Literaturanalyse.

AIM: The diagnosis and treatment of patellar dislocation is very complex. The aim of this study is to give an overview of the biomechanics of the patellofemoral joint and to point out the latest developments in diagnosis and treatment of patellar dislocation. METHOD: The authors electronically searched Medline, Cochrane and Embase for studies on the biomechanics of the patellofemoral joint and for conservative and surgical treatments after patellar dislocation. We extracted baseline demographics, biomechanical, conservation and surgical details. RESULTS: Understanding the biomechanics of the patellofemoral joint is necessary to understand the pathology of patellar dislocation. The patellofemoral joint consists of a complex system of static, active and passive stabilising factors. Patellar instability can result from osseous and soft-tissue abnormalities, such as trochlear dysplasia, patella alta, a high tibial tuberosity trochlear groove (TTTG) distance, weaknesses of the vastus medialis obliquus or a lesion of the medial retinaculum. Recent studies have focused on the medial patellofemoral ligament (MPFL) and have shown that the MPFL is the most significant passive stabiliser of the patella. Following patellar dislocation, an MRI should be standard practice to detect an MPFL rupture, osteochondral lesions or other risk factors for redislocation. An acute first-time patellar dislocation without osteochondral lesions and without severe risk factors for a redislocation should follow a conservative treatment plan. If surgical treatment is required, the best postoperative results occur when the MPFL is reconstructed, leading to a redislocation rate of 5%, this includes cases that have a dysplastic trochlea. Duplication of the medial retinaculum show very inconsistent results in the literature, possibly due to the fact that the essential pathomorphology of patellar dislocation is not addressed. Addressing the exact location of the rupture of the MPFL with a suture is possibly more convenient, especially after first-time dislocation with associated risk factors for a redislocation. Recent literature does not encourage the use of lateral release, since this can increase patellar instability. Indications for lateral release include persistent patellar instability or pain reduction in an older arthritic subject. For correcting a patellofemoral malalignment, the TTTG distance should be measured and a medial transposition of the anterior tibial tubercle hinged on a distal periosteal attachment should be considered. Cartilage lesions on the medial facet of the patella are a contra-indication for medial tubercle transposition. For cartilage lesions of the lateral facet, antero-medialization of the tibial tubercle can be successful. A tubercle osteotomy can be efficiently combined with MPFL reconstruction. We believe that patients with open epiphyseal plates should be treated with duplication of the medial retinaculum. In the presence of patellar maltracking, an additional subperiostal soft tissue release with medialisation of the distal part of the patellar tendon can be performed. CONCLUSION: It seems that the predominating factors for patellar dislocation are heterogenic morphology in combination with individual predisposition. Non-surgical treatment is typically recommended for primary patellar dislocation without any osteochondral lesions and in the absence of significant risk factors for redislocation. If surgical treatment is deemed necessary, addressing the essential pathomorphology has become the primary focus.

[Mid-term clinical and MRI results after refixation of osteochondral fractures with resorbable implants]. / Mittelfristige klinische und kernspintomografische Ergebnisse nach Refixation osteochondraler Fragmente mit resorbierbaren Implantaten.

AIM: Refixation of osteochondral fractures with resorbable implants is a common surgical treatment. There are almost no studies that prove good clinical outcomes. Hence, the aim of the study was to evaluate the mid-term results after refixation of osteochondral fractures. METHODS: The results of 12 patients were recorded 6.5 (±1) years after refixation of osteochondral fractures measuring 3.4 cm (2) (±2.5) of the knee (8 ×) or the ankle joint (4 ×) with resorbable inplants. Clinical scores and a modified MRI score based on that of Henderson et al. were used. RESULTS: The clinical scores showed good to excellent results after 6.5 (±1) years (VAS pain: 1.9 [±2.4], Tegner: 5.0 [±1.7], Lysholm: 84.8 [±14.3], McDermott: 91.3 [±7.9], Knee Society: 189.4 [±12.1]). MRI showed with one exception good integration of the fractures. In 3 cases subchondral cysts could be found. In 7 cases changes in the chondral outline occurred. The effect of this was a modified Henderson score of 12.6 (±3.7). The MRI results did not correlate with the clinical outcome. CONCLUSION: Because of its good clinical results the refixation with resorbable implants can be recommended to treat osteochondral fractures.

Optimized functional femoral rotation in navigated total knee arthroplasty considering ligament tension.

Femoral malrotation in total knee arthroplasty is correlated to an increased number of revisions. Anatomic landmarks such as Whiteside line, posterior condyle axis and transepicondylar axis are used for determining femoral component rotation. The femoral rotation achieved with the anatomical landmarks is compared to the femoral rotation achieved by a navigated ligament tension-based tibia-first technique. Ninety-three consecutive patients with gonarthritis were prospectively enrolled. Intraoperatively the anatomical landmarks for femoral rotation and the achieved femoral rotation using a navigated tension-based tibia-first technique were determined and stored for further comparison. A pre- and postoperative functional diagram displaying the extension and flexion and varus or valgus positions was also part of the evaluation. Using anatomical landmarks the rotational errors ranged from 12.2° of internal rotation to 15.5° of external rotation from parallel to the tibial resection surface at 90° flexion. A statistical significant improved femoral rotation was achieved using the ligament tension-based method with a rotational error ranged from 3.0° of internal rotation to 2.4° of external rotation. The functional analyses demonstrated statistical significant lower varus/valgus deviations within the flexion range and an improved maximum varus deviation at 90° flexion using the ligament tension-based method. Compared to the anatomical landmarks a balanced, almost parallel flexion gap was achieved using a navigation technique taking the ligament tension of the knee joint into account. As a result the improved femoral rotation was demonstrated by the functional evaluation. Unilateral overloading of the polyethylene inlay and unilateral instability can thus be avoided.

Magnetic resonance imaging analysis of the bioabsorbable Milagro interference screw for graft fixation in anterior cruciate ligament reconstruction.

Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years. The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro interference screw (Mitek, Norderstedt, Germany). The Milagro interference screw is made of 30% ss-TCP (TriCalcium phosphate) and 70% PLGA (Poly-lactic-co-glycolic acid). In the period between June 2005 and February 2006, 38 patients underwent graft fixation with Milagro screws in our hospital. Arthroscopic ACL reconstruction was performed using hamstring tendon grafts in all the patients. MR imaging was performed on 12 randomly selected patients out of the total of 38 at 3, 6 and 12 months after surgery. During the examination, the volume loss of the screw, tunnel enlargement, presence of osteolysis, fluid lines, edema and postoperative screw replacement by bone tissue were evaluated. There was no edema or signs of inflammation around the bone tunnels. At 3, 6 and 12 months, the tibial screws showed an average volume loss of 0, 8.1% (+/-7.9%) and 82.6% (+/-17.2%, P < 0.05), respectively. The femoral screws showed volume losses of 2.5% (+/-2.1%), 31.3% (+/-21.6%) and 92.02% (+/-6.3%, P < 0.05), respectively. The femoral tunnel enlargement was 47.4% (+/-43.8%) of the original bone tunnel volume after 12 months, and the mean tunnel volume of the tibial tunnel was -9.5% (+/-58.1%) compared to the original tunnel. Bone ingrowth was observed in all the patients. In conclusion, the resorption behaviour of the Milagro screw is closely linked to the graft healing process. The screws were rapidly resorbed after 6 months and, at 12 months, only the screw remnants were detectable. Moreover, the Milagro screw is biocompatible and osteoconductive, promoting bone ingrowth during resorption. Tunnel enlargement is not prevented in the first months but is reduced by bone ingrowth after 12 months.

The Nottingham health profile-experiences after hip revision arthroplasty.

INTRODUCTION: Considering patients after hip revision arthroplasty postoperative quality controls allows an evaluation of the individual implant situation as well as the achieved postoperative quality of life. With regard to a possible loss of data reliable statements about the used implant system with special consideration to the implant survival rate could not be received. In this connection standardized self-assessment questionnaires like the Nottingham Health Profile (NHP) are in the centre of interest. The main focus of this study was to demonstrate a correlation between the Nottingham Health Profile and the Merle d'Aubigne (MDA) Score. PATIENTS AND METHODS: Fifty-one patients after femoral stem revision were re-examined. All patients received a written appointment for an ambulatory re-examination together with the NHP 4 weeks before. The clinical evaluation was carried out by using the MDA Score. Correlations between the NHP and the MDA were calculated. RESULTS: Overall the data of 39 patients could be evaluated completely. Three patients (5.9%) did not appear to the ambulatory re-examination, four patients (7.8%) deceased in the meantime. With further five patients (9.8%) the NHP questionnaire could not be rated due to an incorrect treatment. The mean follow-up after revision was 5.8 years. Correlations between the category 'Pain' NHP/MDA as well as to the combination of the NHP-categories 'Pain' + 'Physical Mobility' and the total MDA-Score could be demonstrated. CONCLUSION: Out of our personal experiences the use of the NHP makes an individual follow-up evaluation after revision hip arthroplasty possible. Patient-referred changes can lead to direct re-examinations. Correlation coherences between the NHP and the MDA could be demonstrated equivalent to already published results. In what way a survival rate analysis of an implant by using the NHP is possible could not be answered clearly. It has to be included that wrong answered questionnaires lead to an additional drop-out rate beneath the lost to follow-up rate.

[Determination of pressure-volume relations from ventriculographs using catheter tip manometers]. / Darstellung von Druck-Volumen-Beziehungen aus Ventrikulographien mit Hilfe von Katheter-Tipmanometern.

The evaluation of cardiac function alone from pressure and volume data can lead to misinterpretations. By linking of pressure and volume data a variety of new parameters can be calculated. Computer techniques allow the evaluation not only of cardiac work, but also of acceleration work and the efficiency of heart power. As an example of double blind study with CHD patients the measurement of such parameters under invasive diagnostics is demonstrated, facilitating a detailed evaluation of cardiac function.

[Acute changes of coronary and global hemodynamics in patients with angina pectoris and arterial hypertension caused by celiprolol and metoprolol]. / Akute Veränderungen der koronaren und globalen Hämodynamik bei Patienten mit Angina pectoris und arterieller Hypertonie durch Celiprolol und Metoprolol.

In 30 hypertensives with angina pectoris the acute action of beta-blockers Celiprolol and Metoprolol on the global and coronary haemodynamics was tested within cardiac catheter diagnostics. In accordance with no long-term effects Metoprolol acts negatively inotrope, chronotrope as well as pre- and post-load increasing. Celiprolol lowered the pre- and postload, and increased the cardiac output, but did not influence the heart rate. Both medicaments increased coronary flow and myocardiac oxygen consumption. From the mentioned effects important conclusions for therapy with both Beta-blockers can be derived.

[The effect of ionic and nonionic contrast media (amidotrizoate, iopromide) on cardiac function (contractility, relaxation, perfusion)]. / Einfluss von ionischem und nichtionischem Kontrastmittel (Amidotrizoat, Iopromid) auf die Herzfunktion (Kontraktilität, Relaxation, Perfusion).

In 30 patients the influence of ionic (Amidotrizoate) and non-ionic (Iopromide) contrast agents on the heart parameters contractility, relaxation, perfusion and the rate of extrasystoles was investigated. They were significantly less influenced by Iopromide than by Amidotrizoate. A negative inotropic action was detectable only for Amidotrizoate. It is concluded that non-ionic contrast media should be used especially for critical patients.

Fiber-laser-pumped continuous-wave singly resonant optical parametric oscillator.

We report on what is to our knowledge the first continuous-wave (cw) optical parametric oscillator (OPO) that is pumped by a tunable fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled LiNbO(3) crystal in a four-mirror ring cavity. At a pump power of 8.3 W provided by the wavelength-tunable Yb-doped fiber laser, the singly resonant OPO generates 1.9 W of 3200-nm cw idler radiation. The singly resonant OPO was tuned from 1515 to 1633 nm (signal) and from 3057 to 3574 nm (idler) by means of the crystal temperature and poling period. We obtained a wide idler tuning range, from 2980 to 3700 mn, by tuning the wavelength of the fiber laser from 1032 to 1095 nm.