PLCG1 is required for AML1-ETO leukemia stem cell self-renewal.

In an effort to identify novel drugs targeting fusion-oncogene-induced acute myeloid leukemia (AML), we performed high-resolution proteomic analysis. In AML1-ETO (AE)-driven AML, we uncovered a deregulation of phospholipase C (PLC) signaling. We identified PLCgamma 1 (PLCG1) as a specific target of the AE fusion protein that is induced after AE binding to intergenic regulatory DNA elements. Genetic inactivation of PLCG1 in murine and human AML inhibited AML1-ETO dependent self-renewal programs, leukemic proliferation, and leukemia maintenance in vivo. In contrast, PLCG1 was dispensable for normal hematopoietic stem and progenitor cell function. These findings are extended to and confirmed by pharmacologic perturbation of Ca++-signaling in AML1-ETO AML cells, indicating that the PLCG1 pathway poses an important therapeutic target for AML1-ETO+ leukemic stem cells.

Validity of leg length measurement in the supine and standing position compared with pelvic survey X-ray after total hip arthroplasty.

INTRODUCTION: The correct adjustment of leg length is a major goal in the implantation of total hip replacements (THRs). Differences in leg length can lead to functional impairment and patient dissatisfaction. By determining leg length at an early stage, before the patient is discharged from hospital, compensatory measures such as the production of special insoles or orthopaedic footwear can be initiated promptly if there is a difference in leg length. Due to shortening of the period of time spent in hospital, the traditional measurement of leg length in a standing position may be increasingly subject to error. A protective posture immediately after surgery or the presence of a twisted pelvis, for example, due to scoliotic spinal misalignments, falsifies the measurement result in the standing position. Here, the measurement of leg length in the supine position may prove to be accurate immediately postoperatively, regardless of potential sources of error, and is to be compared with measurement in the standing position versus radiological measurement on the AP pelvic survey. MATERIAL AND METHODS: The present retrospective study included 190 patients who had undergone primary total hip arthroplasty. The leg length difference (LLD) of the patients was determined pre- and postoperatively both in the supine and standing position and compared with the postoperative radiological pelvic survey image. RESULTS: Postoperatively, it was shown that the mean length measured was 0.35 mm too long in the supine position and 0.68 mm too short in the standing position (p value < 0.001). Determination of the average absolute measurement error produces a deviation of 4.06 mm in the standing and 4.51 mm in the supine position (p value 0.126). CONCLUSIONS: It is shown that the postoperative measurement of LLD in the supine and standing position is equally valid and sufficiently accurate, compared with the gold standard of measurement on a radiograph.

C-reactive protein during the first 6 postoperative days after total hip arthroplasty cannot predict early periprosthetic infection.

INTRODUCTION: Periprosthetic joint infection (PJI) after total hip arthroplasty (THA) remains a serious complication in orthopaedic surgery. C-reactive protein (CRP) is widely used as a marker to screen for inflammatory complications. The early postoperative course is well known, but knowledge about the predictive value of CRP in the first 6 postoperative days for detecting an acute postoperative PJI is lacking. METHODS: We retrospectively analyzed the inpatient course of CRP of all primary THA and THA with acute PJI within 28 days in our hospital from 2013 to 2021. A receiver-operating curve (ROC) analysis was performed and the best CRP threshold for detecting an acute PJI based on Youden's-index was calculated and an area-under-the curve (AUC) analysis of the threshold was performed. RESULTS: 33 of 7042 patients included had an acute PJI within 28 days. Patients with acute PJI were older, had a higher BMI and longer operation time and suffered more often from diabetes mellitus. A preoperatively elevated CRP was a risk factor for PJI. CRP was significantly higher in the PJI group on postoperative days 3 and 5. Threshold values were calculated to be 152 mg/l on day 3 and 73 mg/l on day 5. However, these values had a low sensitivity (75%, 76%) and specificity (67%, 61%). CONCLUSION: Especially considering the decreasing length of stay after THA, the question of the usefulness of regular inpatient CRP checks arises. AUC analysis of the ROC showed a poor diagnostic accuracy in almost all cases. Only the dynamic analysis of the maximum CRP value to the lowest CRP value with a decrease of 102.7 mg/l showed a fair accuracy. This calls into question the clinical relevance of CRP in the first postoperative week for detection of acute postoperative PJI.

Topical vancomycin powder does not affect patella cartilage degeneration in primary total knee arthroplasty and conversion rate for secondary patella resurfacing.

INTRODUCTION: Vancomycin powder (VP) is an antibiotic first introduced in pediatric spinal surgery to prevent surgical site infections (SSI). Recently its topical application was expanded to total hip and knee arthroplasty (THA, TKA) and anterior cruciate ligament reconstruction (ACLR). Toxicity to cartilage is the subject of current research. The aim of this study was to prove the hypothesis that topical application of VP in TKA does not result in a degeneration of patella cartilage. We propagate that the conversion rate for secondary patella resurfacing is not influenced by its use. MATERIALS AND METHODS: Between 2014 and 2021, 4292 joints were included in this monocentric retrospective cohort study. All patients underwent TKA without primary patella resurfacing. After a change of the procedure in the hospital, one group (VPG) was administered VP intraoperatively. The other group (nVPG) received no VP during surgery (nVPG). The remaining perioperative procedure was constant over the investigation period. Conversion rates for secondary patella resurfacing for both groups were determined without making distinctions in the indication. A second cohort was composed of patients presenting for follow-up examination 12 months after TKA and included 210 joints. Retrospective radiographic evaluations were performed preoperatively, before discharge and at follow-up examination. Patella axial radiographs were analyzed for patella tracking (lateral patellar tilt, patellar displacement) and patella degeneration (Sperner classification, patellofemoral joint space). RESULTS: There was no significant difference in the conversion rate for secondary patella resurfacing (4.24% VPG, 4.97% nVPG). Patella tracking and patella degeneration did not differ significantly between both groups. CONCLUSIONS: The topical application of VP does not influence the conversion rate for secondary patella resurfacing. Moreover, it does not result in a degeneration of patella cartilage in TK. LEVEL OF EVIDENCE: Retrospective case series, Level III.

"Koehlers teardrop is not a reliable landmark for assessing the centre of rotation after Total hip arthroplasty" - a retrospective radiological study.

PURPOSE: Various anatomical landmarks have become established in radiography for the assessment of cup positioning after total hip arthroplasty (THA). The most important one is Koehler's teardrop figure (KTF). However, there is a lack of data on the validity of this landmark, which is widely used clinically for assessing the centre of rotation of the hip. METHOD: A retrospective measurement of the lateral and cranial distance of the KTF to the centre of hip rotation was performed on the basis of 250 X-ray images of patients who had undergone THA. In addition, the dependence of these distances on pelvic tilt was determined in 16 patients by means of virtual X-ray projections based on pelvic CTs. RESULTS: It was shown that the distance of the KTF from the centre of hip rotation in the horizontal plane is gender-dependent (men: 42.8 ± 6.0 mm vs. women: 37.4 ± 4.7 mm; p < 0.001) and age-dependent (Pearson correlation - 0.114; p < 0.05). Furthermore, the vertical and horizontal distances are subject to variation depending on height (Pearson correlation 0.14; p < 0.05 and 0.40; p < 0.001, respectively) and weight (Pearson correlation 0.158; p < 0.05). The distance between the KTF and the centre of hip rotation varies slightly depending on pelvic tilt. CONCLUSION: The KTF is not a sufficiently valid landmark for assessing the centre of rotation after THA. It is influenced by many different disturbance variables. However, it is largely robust against changes in pelvic tilt, so that it can be used as a reference point when comparing different intraindividual radiographs to assess the change in the centre of rotation due to implantation or to detect cup migration.

Defining the canal for ischial and pubic screws in cup revision surgery.

PURPOSE: When revising acetabular cups, it is often necessary to provide additional stabilisation with screws. In extensive defect situations, the placement of screws caudally in the ischium and/or pubis is biomechanically advantageous. Especially after multiple revision operations, the surgeon is confronted with a reduced bone stock and unclear or altered anatomy. In addition, screw placement caudally is associated with greater risk. Therefore, the present study aims to identify and define safe zones for the placement of caudal acetabular screws. METHODS: Forty-three complete CT datasets were used for the evaluation. Sixty-three distinctive 3D points representing bone landmark of interests were defined. The coordinates of these points were then used to calculate all the parameters. For simplified visualisation and intra-operative reproducibility, an analogue clock was used, with 12 o'clock indicating cranial and 6 o'clock caudal. RESULTS: A consistent accumulation was found at around 4.5 ± 0.3 hours for the ischium and 7.9 ± 0.3 hours for the pubic bone. CONCLUSIONS: The anatomy of the ischium and pubis is sufficiently constant to allow the positioning of screws in a standardised way. The interindividual variation is low - regardless of gender - so that the values determined can be used to position screws safely in the ischium and pubis. The values determined can provide the surgeon with additional orientation intra-operatively when placing caudal acetabular screws.

The use of acetabular screws in total hip arthroplasty and its influence on wear and periacetabular osteolysis in the long-term follow-up.

PURPOSE: The cementless implantation of hip replacement cups may be performed with and without the additional use of acetabular screws. If the surgeon uses screws or not depends on variable factors. In general, the use of screws is intended to increase the primary stability of the cup. Whether screws increase the initial stability of the cup construct, or even reduce it in part, is the subject of considerable debate in the literature. It is also unclear whether the additional screws lead to increased wear or increased periacetabular osteolysis over the long-term course. METHODS: Two hundred eleven patients from a previous study with a minimum follow-up of 10.7 years were included. Of these, 68 patients with 82 total hip arthroplasties (THA) were given clinical and radiological follow-up examinations. Of these, 52 had been fitted without screws and 30 with screws. On the basis of radiographs, annual wear and osteolysis were quantified. The clinical results were recorded by means of VAS, HHS, and WOMAC scores. RESULTS: Significantly more periacetabular osteolysis was found if additive acetabular screws had been used. No difference was found in relation to the volumetric wear per year. Likewise, no difference was found with regard to the clinical scores. CONCLUSIONS: The use of additive acetabular screws leads to increased osteolysis in the periacetabular bone stock. Insofar as the primary stability of the cementless cup construct allows it, no additional acetabular screws should be used.

Cone beam-navigated core decompression of bone marrow edema syndrome.

INTRODUCTION: The aim of the study was to compare decompression of bone-marrow edema or osteonecrosis of the proximal femur by means of a cone beam-based imaging and navigation system (cone beam-navigated decompression, CBND) with decompression by the conventional technique of drilling using fluoroscopy (FD). MATERIALS AND METHODS: The data of patients with bone-marrow edema syndrome treated between 2016 and 2018 by drilling of the proximal femur in CBND or FD technique were compared retrospectively. RESULTS: Each treatment group included 20 patients. The mean operating time for CBND was 16.4 ± 5.8 min, compared with 29.1 ± 20.8 min for FD (p = 0.018). The lesion was definitely reached by CBND in 19/20 patients. Eighteen of the 20 patients in the CBND group reported that their pain decreased after the treatment, compared with 12/20 patients in the FD group (p = 0.065). The radiation dosage was significantly higher (p < 0.001) for CBND than for FD. CONCLUSION: Decompression by CBND can be carried out safely and without complications. The advantages of CBND over FD are the minimally invasive access and the ability to address the affected area precisely with only one drilling maneuver. The high radiation dose of CBND can be reduced using low-dose protocols.

Patient Obesity Influences Pelvic Lift During Cup Insertion in Total Hip Arthroplasty Through a Lateral Transgluteal Approach in Supine Position.

BACKGROUND: Movement of the pelvis during implantation of total hip arthroplasty (THA) has a major influence on the positioning of the acetabular cup. Strong traction caused by retractors leads to iatrogenic pelvic lift and can thus be partly responsible for cup malpositioning. The objective of this study was to investigate such factors that influence pelvic lift. METHODS: The dynamic movement of the pelvis was measured during implantation of THA in 67 patients. This was done by measuring the acceleration using the SensorLog app on a smartphone. RESULTS: At its maximum, the pelvis was lifted by an average of 6.7°. When impacting the press-fit cup, the surgical side was raised by 4.4° compared with the time of skin incision. This lift at the time of cup implantation correlates significantly with the body mass index and the patient's abdominal and pelvic circumference. CONCLUSION: Every surgeon performing THA must be aware of the pelvic lift during an operation. Especially in patients with a high body mass index, a large abdominal circumference, or a large pelvic circumference, there is an increased risk of malpositioning of the acetabular cup. When impacting the cup, we recommend releasing the traction of the retractor, so that the pelvis can tilt back into its natural position, and thus, the anticipated cup positioning can be implemented as exactly as possible.

Patient-Specific Contact Stress Does Not Predict Polyethylene Wear Rate in a Specific Pressfit Cup.

BACKGROUND: The most common reason for revision total hip arthroplasty remains polyethylene wear. Development dysplasia of the hip and revision situations requires a conscious compromise of implant position. The surgeon should know about the consequence on wear via a possible change in hip contact force. The objective of this study is to investigate whether annual wear is dependent on hip contact force. METHODS: Forty-five inserts (DuraLoc, DePuy) that were explanted in our department were included. Three-dimensional gravimetric determination of the wear was performed by fluid displacement. Then, the hip contact force was determined using radiographs according to the Blumentritt model. RESULTS: No correlation was found between patient-specific factors and the annual wear. The hip contact force estimated by the Blumentritt model also showed no correlation between hip contact force and annual wear. Two single model parameters correlated significantly with wear: VRECAB as a ratio of the lever length of the spinocrural and the pelvitrochanteric muscles and the angle Alpha as a measure of the position of the center of rotation in relation to the greater trochanter. The greater the ratio spinocrural/pelvitrochanteric lever arm (R = 0.408, P = .005) and the greater the Alpha angle (more valgus the femoral neck) (R = 0.377, P = .011) were, the greater was the wear. CONCLUSION: These results lead to the conclusion that neither patient-specific factors nor the estimated hip contact force have a major influence on annual wear in the case of DuraLoc cups. Only a coxa valga and a small femoral offset contribute in a limited amount to an increase in wear.

Effects of Kinesio taping compared to arterio-venous Impulse System™ on limb swelling and skin temperature after total knee arthroplasty.

PURPOSE: It is an established fact that post-operative (p.o.) soft-tissue swelling and lymphoedema after total knee arthroplasty (TKA) have a major influence on the p.o. early functional outcome. Kinesio taping has a proven clinical effect in increasing lymph drainage. Despite the decades of experience gained and the assumed positive effects, hardly any investigations have been conducted to date on the influence of Kinesio taping on the p.o. healing process after TKA. The objective of the present study was to test the hypothesis that Kinesio taping used as a lymph application leads to a reduction of p.o. soft-tissue swelling. As a secondary objective, it was to be tested whether there is an effect on skin temperature as a surrogate parameter for dermal micro-circulation. METHODS: In this prospective study with a historical control (A-V Impulse System™ group), 42 subjects were included and treated with Kinesio taping after implantation of a TKA. The patients of the study group were treated immediately p.o. with Kinesio® Tex Gold™ fan cut tape as a lymph application with a common base. A thermographic temperature determination of the knee joint operated on was performed on each patient in the supine position every day from the first to the seventh p.o. day. The leg circumference was documented daily at eight specified measuring points on both lower limbs. As a statistical analytical approach, the so-called principal component analysis was used. An analysis of variance was performed. The significance level was set at p < 0.001. RESULTS: The course of soft-tissue swelling of the study group did not differ from that of the control group at any point in time. For the temperature course of the medial wound aspect, no difference was seen between the Kinesio taping study group and the A-V Impulse System™ group. In contrast, the temperature course of the lateral wound aspect showed a reproducibly higher temperature in the Kinesio tape group than in the control group (0.6 °C (0.5-0.8), p < 0.001). CONCLUSION: The hypothesis of the study that Kinesio taping as a lymph application induces a reduction of soft-tissue swelling after TKA must be rejected on the basis of the present data. Solely the temperature of the lateral wound aspect was higher in the Kinesio taping group than in the control group, so that an increased blood circulation can be assumed here. Considering that the actively working A-V Impulse System™ used in the control group also increases local blood circulation, the effect of the passive Kinesio tape is surprising. However, this was not reflected in a quicker wound healing, as the day of last wound secretion was the same in both groups. Kinesio taping as a lymph application represents an equivalent alternative to the A-V Impulse System™ for therapy after total knee arthroplasty with regard to soft-tissue swelling and wound healing.

A Simple Procedure for the Evaluation of Bone Vitality by Staining with a Tetrazolium Salt.

Presently, no intra-operative method for a direct assessment of bone vitality exists. Therefore, we set out to test the applicability of tetrazolium-based staining on bone samples. The explanted femoral heads of 37 patients were used to obtain either cancellous bone fragments or bone slices. Samples were stained with 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (thiazolyl blue, MTT) at different times (one to twelve hours) after explantation. Staining was quantified either spectrophotometrically after extraction of the dyes or by densitometric image analysis. TTC-staining of cancellous bone fragments and bone slices, respectively, indicated the detectability of vital cells in both types of samples in a window of up to six hours after explantation. Staining intensity at later time-points was indistinguishable from the staining of untreated samples or sodium azide treated samples, which represent dead cells. In contrast, MTT-staining of bone slices revealed intense unspecific staining, which obscured the evaluation of the vitality of the samples. The lack of a detectable increase of colour intensity in TTC-stained bone samples, which were treated more than six hours after explantation, corresponds to reduced fracture healing. The described simple procedure could provide a basis for an intraoperative decision by the orthopaedic surgeon.

Course of pelvic lift during total hip arthroplasty.

INTRODUCTION: The position of the cup makes a major contribution to the success of total hip arthroplasty (THA). In conventional implantation of the prosthesis without navigation, the surgeon relies on the spatial position of the pelvis. However, iatrogenic manipulation of the pelvis during different surgical steps constantly changes the position of the pelvis during the operation. The position of the pelvis is substantial for the correct placement of the cup. The objective of this study was to investigate and visualize the course of this pelvic lift and correlate it to certain surgical steps. MATERIALS AND METHODS: Pelvic lift was measured in 67 patients during implantation of a THA. This was done by measuring acceleration using the SensorLog app on a smartphone. It was placed on the patient's contralateral anterior superior iliac spine and recorded the movement of the pelvis throughout the whole surgical procedure. The position of the pelvis was allocated to each of eight relevant surgical steps during the operation. These surgical steps were normed over the time axis and transferred to a diagram. RESULTS: We found an average pelvic lift displacement of up to 14.9° upon placement in the figure-of-four position. This lift is particularly critical when exposing the acetabulum, as the true cup position can be unconsciously influenced. Average values of between 5.6° and 6.9° were found here. CONCLUSIONS: When implanting a THA in supine position, the pelvis is not fixed on the operating table. Rather, the side to be operated on is lifted to a greater or lesser degree, depending on the surgical step to be performed. The retractor traction immediately before cup implantation should be minimized. Nevertheless, it should be taken into account that anteversion of the cup implant in relation to the table plane is systematically higher than in relation to the pelvic entry plane.

C-reactive protein course during the first 5 days after total knee arthroplasty cannot predict early prosthetic joint infection.

INTRODUCTION: Periprosthetic joint infection (PJI) is one of the most devastating major complications after total knee arthroplasty (TKA). The laboratory value C-reactive protein (CRP) is the inflammatory biomarker most suitable for detecting a potential postoperative (p.o.) early infection in orthopaedic surgery. However, on the basis of multiple receiver operating characteristic (ROC) analyses, CRP only has limited sensitivity and specificity. The objective of the present study was to test the hypothesis that, besides the absolute preoperative CRP value, also the absolute postoperative CRP value and its course over the first 5 days after TKA are valid indicators of periprosthetic early infection. MATERIALS AND METHODS: A total of 1068 subjects who had been treated with a unilateral primary cemented total knee replacement due to primary osteoarthritis of the knee were included in the study. Retrospectively, for all patients, the preoperative CRP value, the p.o. CRP course and a history of the medical course, including any superficial surgical site infection (SSI) or deep PJI of the knee joint operated on, were recorded; further, any follow-up operations (septic revision) were documented. Using receiver operating characteristic (ROC) analysis, an optimum preoperative CRP cutoff value for the positive prediction of a PJI was determined. RESULTS: 34 of 1068 patients developed an SSI or a PJI that had to be revised. After TKA implantation, the CRP value increased significantly and achieved its maximum between the second and third p.o. day. At no p.o. day was there a difference in CRP between patients who developed an SSI or a deep PJI and patients with a normal complication-free p.o. COURSE: In contrast, the preoperative CRP value proved to be a reliable predictor for septic revision due to an SSI or a PJI: the ROC analysis showed the optimum preoperative CRP cutoff value for a positive prediction of PJI to be 5 mg/L. CONCLUSION: The most important finding of the present study is that neither the absolute p.o. CRP value nor its course in the first 5 days after TKA is suitable for detecting an early infection. In contrast, an increased preoperative CRP value proved to be a valid predictor for septic revision due to an SSI or a PJI after TKA.

Changes of posterior condylar offset results in midflexion instability in single-radius total knee arthroplasty.

INTRODUCTION: There is no algorithm for the management of joint stability in midflexion up to now. Change in the joint line (JL) is considered to be the primary cause, although it only determines the extension gap. The purpose of this study was to determine the influence of the posterior condylar offsets (PCO), which defines the flexion gap, on midflexion instability. MATERIALS AND METHODS: Forty-two knee joints (38 patients) were included in this study, patients undergoing navigated total knee arthroplasty due to primary osteoarthritis of the knee. Changes in the JL and the PCO were determined from the navigation data. A gap tensioning device was used to determine the width of the joint gap at -5°, 0°, 30° and 60° intraoperatively. RESULTS: Within a range between 5 mm proximalization and 2 mm distalization, the JL had no influence on stability in midflexion. In contrast to this, both an increase and a decrease in PCO led to midflexion instability (R = 0.361, p = 0.019). In 16 cases (38%), the PCO was changed by more than 2 mm. This led to a midflexion instability of more than 2 mm in seven of these cases (44%). CONCLUSIONS: Whereas the joint line can be displaced by up to 5 mm without measurable changes in joint stability, reconstruction of the posterior offset within a tight range of 2 mm is necessary to avoid midflexion instability.

The C-reactive protein level after total knee arthroplasty is gender specific.

PURPOSE: Laboratory diagnostics are part of the routine before and after operations. In all specialist surgical disciplines, including orthopaedic surgery, the acute-phase protein CRP is used to detect inflammatory processes, especially infections. The potential influence of patient gender on the postoperative course of CRP after TKA implantation is still unclear. In order to achieve a more precise evaluation of the complication-free general CRP course after TKA, the objective of the present study is to test the hypothesis that the p.o. course and level of CRP is gender specific in the first 10 days after TKA. METHODS: A total of 1068 consecutive patients who had been treated with a unilateral primary cemented total knee replacement due to primary osteoarthritis of the knee over a 36-month period were retrospectively included in the study. For all patients, the preoperative CRP value and the postoperative course of CRP from postoperative days 1-10 were recorded and tested for gender specificity. RESULTS: On days 2-5 and 7-8 after surgery, men had significantly higher CRP values than women. The maximum difference was 45 mg/L on the fourth p.o. day (men 170 mg/L, women 125 mg/L, p = 0.019). CONCLUSION: The present study was able to show, for the first time, that the complication-free course of CRP in the first 10 days after TKA implantation is gender specific. The impact of the finding on diagnostic is that the gender-specific CRP course provides a more precise evaluation of the complication-free course of CRP after TKA. These results have clinical relevance to the interpretation of postoperative CRP values in order to avoid unnecessary investigations such as puncture or surgical care in female and male patients with uncomplicated TKA. Level of evidence Diagnostic study, III.

The reversed gap technique produces anatomical alignment with less midflexion instability in total knee arthroplasty: a prospective randomized trial.

PURPOSE: No surgical technique is capable of controlling the stability of the joint in midflexion. The purpose of the present study was to present and evaluate a surgical technique that aims to reduce the need for soft-tissue release and optimize stability in midflexion. METHODS: Sixty knee joints were included in this prospective randomized study. Surgery was performed either according to a classical gap (GT) technique or using the reversed gap (RG) technique. In the RG, the femoral component was positioned parallel to the surgical transepicondylar axis using a preoperative MRI and a navigation system. The frontal alignment of the tibia was then selected to produce a symmetric flexion gap. Then, the frontal alignment of the femoral component was adjusted to produce a symmetric extension gap. Soft-tissue release was defined to be extensive if more than two steps or stabilizing structures were involved. Joint stability was measured at different flexion angles (-5° to 120°) using a gap tensioning device and the trial femoral implant. RESULTS: In the GT group, 16 knee joints (53 %) showed an instability of more than 2 mm at 5°, 30° or 60°, compared with 8 knee joints (27 %) in the RG group (p = 0.035). The RG did not lead to a reduction in the number of soft-tissue releases, but they were less extensive. CONCLUSION: RG reduced midflexion instability and the number of extensive soft-tissue releases. It may simplify the operation by reducing the extent of soft-tissue releases and avoid instability-related problems of knee arthroplasty. Nevertheless, it should only be performed under controlled conditions until long-term clinical data are available. LEVEL OF EVIDENCE: I.

Regional differences in temperature course after knee arthroplasty.

PURPOSE: During wound healing after surgery, physiological inflammation leads to an increase in soft tissue perfusion. This is reflected by a characteristic temperature course in the skin. Although local surgical trauma also influences soft tissue perfusion, no data have been available on the regional temperature distribution after knee arthroplasty to date. This study aims at testing the hypothesis that the greatest regional difference in the temperature course is on the site of the maximum surgical trauma (medially) after knee arthroplasty implantation. This is to our knowledge the first study to present regional differences in the temperature course after TKA which would limit the diagnostic value of thermography. METHODS: Forty-two subjects who were to receive a surface replacement of the knee joint due to primary varus gonarthrosis were included in the study. In all cases, a medial parapatellar approach was chosen. Patients who underwent lateral release or a release of the lateral ligament structures were excluded. In all patients, a thermographic temperature determination was carried out on the operated knee joint every day up to the seventh post-operative day. RESULTS: On the medial side, there was no significant change in temperature between day one 34.9° ± 0.2° (34.6-35.3 °C) and seven after surgery. Thereafter, the temperature remained constant here up to the seventh day after the operation. In contrast to this, on the lateral side there was an increase in skin temperature from the second 35.0 ± 0.2 °C (34.7-35.4 °C) to the fifth 34.6° ± 0.2° (34.1-34.9 °C) post-operative day (p = 0.002). Thereafter, the temperature remained constant here up to the seventh day after the operation. CONCLUSION: This study refutes the hypothesis that the greatest regional difference in the temperature course is on the site of maximum surgical trauma (medially) after knee arthroplasty implantation. It is shown to the contrary that there is the least regional difference in the temperature course on the site of maximum surgical trauma (medially) after total knee arthroplasty implantation. It is on the site of the minimal trauma (laterally) where marked differences in the temperature course appeared. The normal temporary temperature increase typical of physiological wound healing could only be shown at a distance from the site of soft tissue preparation. This may be the result of a local compromise of perfusion. Consequently, the post-operative diagnostic application of thermography remains limited to regions distant from the surgical site. This may prevent misinterpretation of post-operative thermographic measurements for scientific or clinical reasons. LEVEL OF EVIDENCE: II.

High failure rate of a new pressfit cup in mid-term follow-up.

BACKGROUND: Unacceptably high rates of loosening of a novel cementless cup system (Mathys, SeleXys TH+) have been reported. In this study, our mid-term-results with the SeleXys TH+ cup are compared with an established pressfit cup (Ceraver, Cerafit-R). METHODS: Between 2008 and 2011, a total of 407 implantations, 19 of them bilaterally, were conducted on 388 patients with the implants in question. A total of 280 cups were available for follow-up. Of these, 160 SeleXys TH+ cups and 120 Cerafit-R cups had been used. RESULTS: The mean follow-up period was 48.6 months (min. 28, max. 75). A total of 18 cases of loosening were found in the SeleXys TH+ group. Of these, one was of a traumatic nature and one was of septic origin. This left 16 cases of aseptic, atraumatic loosening (10% loosening rate). In the Cerafit-R group, only two cases (1.7%) of loosening were seen over the same period. Both were of traumatic origin. No cases of aseptic, atraumatic loosening were seen in the follow-up period. Further, significantly more cases of loosening were observed in women than in men with the SeleXys cup. CONCLUSIONS: The SeleXys TH+ cup shows an unacceptably high failure rate after six years. The time of revision is not limited to the first months after implantation, which means that close clinical and radiological controls will continue to be necessary in future in patients treated with SeleXys TH+ cups. Level of Evidenve: III (retrospective cohort study).

A biomechanical comparison of fixed angle locking compression plate osteosynthesis and cement augmented screw osteosynthesis in the management of intra articular calcaneal fractures.

PURPOSE: The purpose of this study was to investigate whether cement-augmented screw osteosynthesis results in stability comparable to conventional fixed-angle locking plate osteosynthesis using cadaveric bones to model a Sanders type 2B fracture. METHODS: Seven pairs of fresh frozen human calcanei and the corresponding tali were used. The specimens were assigned pairwise to two study groups in a randomised manner. In order to determine the initial quasi-static stiffness of the bone-implant construct, testing commenced with quasi-static compression ramp loading; subsequently, sinusoidal cyclic compression loading at 2 Hz was performed until construct failure occurred. Initial dynamic stiffness (cycle 1), range of motion (ROM), cycles to failure and load to failure were determined from the machine data during the cyclic test. In addition, at 250-cycle intervals, Böhler's angle and the critical angle of Gissane were determined on mediolateral X-rays shot with a triggered C-arm; 5° angle flattening was arbitrarily defined as a failure criterion. RESULTS: Bone mineral density was normally distributed without significant differences between the groups. The augmented screw osteosynthesis resulted in higher stiffness values compared to the fixed-angle locking plate osteosynthesis. The fracture fragment motion in the locking plate group was significantly higher compared to the group with augmented screw osteosynthesis. CONCLUSIONS: The results of this study indicate that in our selected test set-up augmented screw osteosynthesis was significantly superior to the conventional fixed-angle locking plate osteosynthesis with respect to primary stability and ROM during cyclic testing.