D-lactate is a promising biomarker for the diagnosis of periprosthetic joint infection.

Introduction: Reliable biomarkers for the diagnosis of periprosthetic joint infection (PJI) are of paramount clinical value. To date, synovial fluid leukocyte count is the standard surrogate parameter indicating PJI. As D-lactate is almost solely produced by bacteria, it represents a promising molecule in the diagnostic workflow of PJI evaluation. Therefore, the purpose of this study was to assess the performance of synovial fluid D-lactate for diagnosing PJI of the hip and knee. Materials and Methods: These are preliminary results of a prospective multicenter study from one academic center. Seventy-two consecutive patients after total hip arthroplasty (THA) or total knee arthroplasty (TKA) were prospectively included. All patients received a joint aspiration in order to rule out or confirm PJI, which was diagnosed according to previously published institutional criteria. Synovial fluid D-lactate was determined spectrophotometrically at 450 nm. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance. Results: Eighteen patients (25%) were diagnosed with PJI and 54 patients (75%) were classified as aseptic. Synovial fluid D-lactate showed a sensitivity of 90.7% (95% CI: 79.7%-96.9%) and specificity of 83.3% (95% CI: 58.6%-96.4%) at a cut-off of 0.04 mmol/L. The median concentration of D-lactate was significantly higher in patients with PJI than in those with aseptic conditions (0.048 mmol/L, range, 0.026-0.076 mmol/L vs. 0.024 mmol/L, range, 0.003-0.058 mmol/L, p < 0.0001). The predominat microogranisms were staphylococci, followed by streptococci and gram-negative bacteria. Conclusion: D-lactate bears a strong potential to act as a valuable biomarker for diagnosing PJI of the hip and knee. In our study, a cutoff of 0.04 mmol/L showed a comparable sensitivity to synovial fluid leukocyte count. However, its specificity was higher compared to conventional diagnostic tools. The additional advantages of D-lactate testing are requirement of low synovial fluid volume, short turnaround time and low cost.

Quantitative and individualized assessment of the learning curve in preoperative planning of the acetabular cup size in primary total hip arthroplasty.

INTRODUCTION: The aim of the present study was to investigate the learning curves of 2 trainees with different experience levels to reach proficiency in preoperative planning of the cup size based on learning curve cumulative summation (LC-CUSUM) statistics and a cumulative summation (CUSUM) test. MATERIALS AND METHODS: One-hundred-twenty patients who had undergone primary total hip arthroplasty with a cementless cup were selected. Preoperative planning was performed by an experienced orthopedic surgeon. Trainee 1 (student) and trainee 2 (resident) planned the cup size. The trainees were blinded to the preoperative plan and the definitive cup size. Only after a cup size was chosen, the trainees were unblinded to the preoperative plan of the surgeon. LC-CUSUM was applied to both trainees to determine when proficiency in determining the appropriate cup size was reached. A CUSUM test was applied to ensure retention of proficiency. RESULTS: With reference to the preoperative plan of the surgeon, LC-CUSUM indicated proficiency after 94 planning attempts for trainee 1 and proficiency after 66 attempts for trainee 2, respectively. Trainee 1 and 2 maintained proficiency thereafter. With reference to the definitive cup size, LC-CUSUM did not signal competency within the first 120 planning attempts for trainee 1. Trainee 2 was declared competent after 103 attempts and retained competency thereafter. CONCLUSIONS: LC-CUSUM/CUSUM allow for an individualized, quantitative and continuous assessment of planning quality. Based on LC-CUSUM statistics, the two trainees of this study gain proficiency in planning of the acetabular cup size after 50-100 attempts when an immediate feedback is provided. Previous experience positively influences the performance. The study serves as basis for the medical education of students and residents in joint replacement procedures.

Modified Candy-Package technique vs Cerclage technique for refixation of the lesser trochanteric fragment in pertrochanteric femoral fractures. A biomechanical comparison of 10 specimens.

OBJECTIVES: Separation of the lesser trochanteric fragment in pertrochanteric 3-part fractures leads to a significant weakening of the medial cortical wall. Because of the attachment of the Iliopsoas muscle to this structure, the lesser trochanteric fragment tends to cranial dislocation along this muscle's action direction. Refixation of these fractures using an intramedullary nail and an additional wiring osteosynthesis can be considered an operative standard. Based on an intramedullary osteosynthesis procedure, the question was raised whether a 2-point fixation method was favourable over a 1-point method regarding the pull-out resistance of the lesser trochanteric fragment against the Iliopsoas muscle's force. METHODS: Based on an intramedullary osteosynthesis (PFNA, DePuy/Synthes/SUI), two groups á five human femora were defined depending on the refixation technique of the lesser trochanteric fragment (1-point supertrochanteric "Cable" vs 2-point super/subtrochanteric fixation "Candy-Package" performed with a 1.25-mm steel cerclage). The specimens were tested using a novel traction setup, simulating the activity pattern of the Iliopsoas muscle. The target value was the resistance of the refixated lesser trochanteric fragment against a defined pull-out force produced by the Iliopsoas muscle. The main parameters considered were the peak traction force (Fmax) and the maximum summative work (WFmax) at construct failure. RESULTS: The Fmax and WFmax displayed a significant difference in favour of the Candy-Package (2-point super/subtrochanteric fixation) group (822 N vs. 476 N, 13.8 k Nmm vs 4.4 k Nmm, respectively; P = 0.01). CONCLUSIONS: The Candy-Package technique is a method that displays significantly more resistance than a single cerclage osteosynthesis regarding fragment loosening under the application of a simulated Iliopsoas muscle force in the course of a biomechanical proximal femoral 3-part fracture model.

Outcome of Irrigation and Debridement after Failed Two-Stage Reimplantation for Periprosthetic Joint Infection.

INTRODUCTION: Two-stage revision is the gold standard for the treatment of deep implant infection after knee or hip arthroplasty. Irrigation and debridement may be a treatment option for failed 2-stage revisions in cases where a reinfection occurs within 30 days or the symptoms exist not longer than 3 weeks and is appealing because of its low morbidity. We determined the incidence of recurrent infections following irrigation and debridement for failed two-stage revision hip and knee arthroplasty. METHODS: We performed a single center retrospective review of periprosthetic hip and knee infections treated with a two-stage procedure from 2002 to 2010. All patients that subsequently underwent irrigation and debridement for a subsequent infection were selected for the current study. RESULTS: 440 two-stage revisions were performed between 2002 and 2010. Fifty-one two-stage revisions failed (11.6%). Nineteen failed two-stage revisions were treated with irrigation and debridement; 12 (63.2%) patients remained free of infection at follow-up (mean follow-up: 39 months; range, 24-90 months), infection persisted in 6 patients (31.6%), and 1 patient died (5.3%). CONCLUSIONS: Success rates of irrigation and debridement for failed two-stage procedures are similar to the success rates of irrigation and debridement in primary implant infections. According to the current paper, irrigation and debridement are an acceptable treatment for acute reinfections after failed two-stage revision if performed within the first 30 postoperative days after failed two-stage procedure or if symptoms are present for less than 3 weeks in the presence of a susceptible organism.

Does the tibia component design affect the need for offset stems in revision total knee arthroplasty?

INTRODUCTION: The stem/keel location varies between anatomic and symmetric revision tibial baseplates. The current study investigates the impact of an anatomic versus symmetric stem location on the need for offset couplers in revision total knee arthroplasty. MATERIALS AND METHODS: Hip to ankle standing radiographs and lateral radiographs of 75 patients were analyzed using digital templating software. The offset in the anterior-posterior as well as medial-lateral plane between the center of the tibial diaphysis and the stem of the tibial baseplate were determined for an anatomic and symmetric tibial baseplate, respectively. Measurements were repeated for 4 resection levels: tip of fibular head (0), 10 mm (1), 15 mm (2) and 20 mm (3) below the tip of the fibula head. RESULTS: Anatomic tibial baseplates require less offset for resection levels up to the tip of the fibula: total offset 2.28 versus 5.44 mm (p < 0.001). However, for defects that result in resection levels below the tip of the fibula symmetric tibial baseplates require less offset: resection level 1: 3.18 versus 2.4 mm (p = 0.008), 2: 4.81 versus 1.67 mm (p < 0.001) and resection level 3: 5.66 versus 1.52 mm (P < 0.001). CONCLUSION: The current study suggests that while asymmetric anatomic tibial baseplates have benefits for revisions with minimal bone loss, symmetric tibial baseplates require less offset when larger bone defects are encountered.

Predictive values of WOMAC, KOOS, and SF-12 score for knee arthroplasty: data from the OAI.

PURPOSE: A number of validated scores are available to monitor clinical outcome after knee arthroplasty. The current study examines whether WOMAC, KOOS, or SF-12 scores have a predictive value to identify patients that require total knee arthroplasty within 1 year. METHODS: The Osteoarthritis Initiative includes 4684 patients in two groups: incidence subcohort (Group A, n = 3284) and progression subcohort (Group B, n = 1400). A total of 278 patients reached the endpoint "unilateral knee replacement" (Group A = 96; Group B = 182). WOMAC, KOOS, and SF-12 scores at the maximum of 12 months prior to surgery were used to analyse predictive values. ROC analysis and the diagnostic accuracy for these scores were reported. RESULTS: Group A: WOMAC and KOOS score as well as the "physical component summary" of SF-12 showed an area under the curve (AUC) between 0.8 and 0.9 (high diagnostic evidence) to predict total knee replacement. The KOOS "symptoms" (0.67) and SF12 "function" (0.79) showed lower values. The KOOS QoL score showed the highest predictive value with an AUC of 0.84 (CI 95% 0.77-0.91, p < 0.001) resulting in a sensitivity of 0.88 and a specificity of 0.72. Similar numbers were achieved by the total WOMAC score with an AUC of 0.85 (CI 95% 0.82-0.88, p < 0.001) resulting in a sensitivity of 0.77 and a specificity of 0.82. The SF-12 physical component score had an AUC of 0.83 (CI 95% 0.79-0.87, p < 0.001) resulting in a sensitivity of 0.87 and a specificity of 0.68. Different combinations of scores increase the positive likelihood ratio (up to 18) and specificity (up to 0.97). Group B scores showed lower AUCs, sensitivities and specificities. CONCLUSIONS: Combinations of WOMAC, KOOS, or SF-12 scores accurately predict patients that require knee arthroplasty within 1 year. In addition to other clinical parameters (physical examination, radiographs), they can guide patient and surgeon during the treatment of arthritis of the knee. LEVEL OF EVIDENCE: II.

[Acetabular Osteolysis in Total Hip Replacement - When to Retain the Cup?]. / Azetabuläre Osteolysen bei Hüfttotalendoprothese - wann kann die Pfanne belassen werden?

Periacetabular osteolysis is a frequent long-term complication of cementless total hip arthroplasty. The decision whether to retain or to revise a cup in the presence of osteolysis remains a challenge. The options are regular clinical and radiological check-ups, isolated liner exchange with and without bone grafting, and complete cup revision. Thorough preoperative diagnostics, including a medical history, examination and imaging, are mandatory for correct decision making. In most patients, computed tomography is useful to assess periacetabular osteolysis. If the cup is well-fixed and positioned in an asymptomatic patient without progressive osteolysis and no implant defect or higher grade polyethylene wear and no signs of infection, continuous clinical and radiological monitoring is preferred. If imaging reveals cup loosening, malposition, osteolysis localised in a weight-bearing area, imminent or present periprosthetic fractures, rapid progressive osteolysis, implant defects or massive inlay wear, surgical treatment may be preferred. Cup revision is usually performed in such patients. If the cup is well-positioned and well-fixed in the X-ray, the procedure has to be discussed with the patient individually. Apart from patient-specific risk factors, the risk of further progression has to be assessed. Isolated liner exchange can be performed if the patient is asymptomatic and the cup proves to be stable intraoperatively. It is still unclear whether filling osteolyses through screw holes or osseous windows is of long-term benefit.

An electronically instrumented internal fixator for the assessment of bone healing.

OBJECTIVES: The monitoring of fracture healing is a complex process. Typically, successive radiographs are performed and an emerging calcification of the fracture area is evaluated. The aim of this study was to investigate whether different bone healing patterns can be distinguished using a telemetric instrumented femoral internal plate fixator. MATERIALS AND METHODS: An electronic telemetric system was developed to assess bone healing mechanically. The system consists of a telemetry module which is applied to an internal locking plate fixator, an external reader device, a sensor for measuring externally applied load and a laptop computer with processing software. By correlation between externally applied load and load measured in the implant, the elasticity of the osteosynthesis is calculated. The elasticity decreases with ongoing consolidation of a fracture or nonunion and is an appropriate parameter for the course of bone healing. At our centre, clinical application has been performed in 56 patients suffering nonunion or fracture of the femur. RESULTS: A total of 39 cases of clinical application were reviewed for this study. In total, four different types of healing curves were observed: fast healing; slow healing; plateau followed by healing; and non-healing. CONCLUSION: The electronically instrumented internal fixator proved to be valuable for the assessment of bone healing in difficult healing situations. Cost-effective manufacturing is possible because the used electronic components are derived from large-scale production. The incorporation of microelectronics into orthopaedic implants will be an important innovation in future clinical care.Cite this article: B. Kienast, B. Kowald, K. Seide, M. Aljudaibi, M. Faschingbauer, C. Juergens, J. Gille. An electronically instrumented internal fixator for the assessment of bone healing. Bone Joint Res 2016;5:191-197. DOI: 10.1302/2046-3758.55.2000611.

Can the frontal tibiofemoral alignment be assessed on anteroposterior knee radiographs?

BACKGROUND: The aim of total knee arthroplasty is, amongst others, the reconstruction of a physiological axis of the leg with a tibiofemoral angle in the frontal plane of an average of 6°. The aim of this study is to clarify how much of the bone length on the femur and tibia has to be reproduced on anteroposterior (AP) knee radiographs in order to determine the leg's alignment after a total knee arthroplasty. MATERIALS AND METHODS: We analyzed the postoperative hip-to-ankle (HTA) radiographs of 100 patients who had undergone a total knee arthroplasty at our institution. RESULTS: There were strong correlations between the measured values on HTA and 20 cm bone length [lateral distal femur angle (LDFA) r = 0.887, medial proximal tibial angle (MPTA) r = 0.874, tibiofemoral angle (TFA) r = 0.888], but not between the measurements on HTA and 10 cm (LDFA r = 0.267, MPTA r = 0.102, TFA r = 0.161). There were significant differences between all measurements both on HTA and 20 cm and on HTA and 10 cm, with the exception of the LDFA between HTA and 10 cm (p = 0.085) and of the MPTA between HTA and 20 cm (p = 0.227). The intra- and inter-observer correlations were both high. CONCLUSION: If preoperatively crude axis deviations are excluded, the tibiofemoral angle on AP knee radiographs can be determined with an accuracy of ±2.6° if at least 20 cm length of bone is reproduced (measured from the femoral and tibial joint line). Due to the high 95 % confidence intervals and bearing in mind that deviations greater than 3° may lead to inferior clinical results, however, it appears inappropriate to determine lower limb alignment with anteroposterior radiographs. LEVEL OF EVIDENCE: Level 2.

Complications associated with 133 static, antibiotic-laden spacers after TKA.

PURPOSE: Periprosthetic infection after total knee arthroplasty (TKA) is a devastating complication, with a two-stage revision currently the 'gold standard' treatment for chronic infections. There is, however, a lack of information about mechanical complications during this treatment. The purpose of this study was to determine: (1) the rate and type of mechanical complications encountered during a two-stage exchange revision for periprosthetic infection of the knee and (2) possible factors of influence. METHODS: Between 2000 and 2011, 133 patients received an antibiotic-laden cement spacer as part of a two-stage protocol. The overall frequency and types of complication were recorded (fissure/fracture of the tibia or femur, spacer fracture, subluxation of the patella, peroneus affection, wound healing disorder and mobilization under anaesthesia based on a constricted ROM). Also analysed were potential influencing factors (BMI, ASA classification, length of the interval with the enclosed spacer, revision needed after explantation, revision needed after reimplantation, complications after primary TKA, service life of the primary prosthesis) in terms of the overall outcome (possibility of reimplantation, complications during the two-stage protocol). RESULTS: The mean age at the time of the first stage operation was 70.1 ± 9.9 years. Overall, 20 of 133 patients suffered one of the complications mentioned above (15 %). Fracture/fissure of the tibia occurred in nine cases (6.8 %) and fracture/fissure of the femur in three (2.3 %). There were also three mobilizations under anaesthesia after TKA reimplantation, two affections of the peroneus nerve, one spacer fracture, one subluxation of the patella and one wound healing disorder. The influencing factors on the overall outcome were revision after reimplantation (reinfection, p = 0.002), revision after explantation (reinfection, p = 0.044), prior aseptic revision after primary TKA (reimplantation, p = 0.019), and prior two-stage revision (reimplantation, p = 0.002). CONCLUSION: A two-stage revision arthroplasty using a static cement spacer is an effective therapy for infected TKAs. The complication rate of 15 % (including restricted ROM after reimplantation) is acceptable. Influencing factors (revision needed after reimplantation, revision needed after explantation) can be demonstrated and should be avoided during the two-stage protocol.

Are lateral compartment osteophytes a predictor for lateral cartilage damage in varus osteoarthritic knees?: Data from the Osteoarthritis Initiative.

We studied whether the presence of lateral osteophytes on plain radiographs was a predictor for the quality of cartilage in the lateral compartment of patients with varus osteoarthritic of the knee (Kellgren and Lawrence grade 2 to 3). The baseline MRIs of 344 patients from the Osteoarthritis Initiative (OAI) who had varus osteoarthritis (OA) of the knee on hip-knee-ankle radiographs were reviewed. Patients were categorised using the Osteoarthritis Research Society International (OARSI) osteophyte grading system into 174 patients with grade 0 (no osteophytes), 128 grade 1 (mild osteophytes), 28 grade 2 (moderate osteophytes) and 14 grade 3 (severe osteophytes) in the lateral compartment (tibia). All patients had Kellgren and Lawrence grade 2 or 3 arthritis of the medial compartment. The thickness and volume of the lateral cartilage and the percentage of full-thickness cartilage defects in the lateral compartment was analysed. There was no difference in the cartilage thickness or cartilage volume between knees with osteophyte grades 0 to 3. The percentage of full-thickness cartilage defects on the tibial side increased from < 2% for grade 0 and 1 to 10% for grade 3. The lateral compartment cartilage volume and thickness is not influenced by the presence of lateral compartment osteophytes in patients with varus OA of the knee. Large lateral compartment osteophytes (grade 3) increase the likelihood of full-thickness cartilage defects in the lateral compartment.

Traumatic Rupture of the Distal Triceps Tendon (A Series of 7 Cases).

Even non-traumatic ruptures of the triceps tendon are rare, surgical therapy should be recommended in all cases, because of poor results after non-operative treatment. A golden standard for the surgical procedure is not established. A small series of traumatic distal tendon ruptures was treated surgical in our hospital and was followed up after 12 months concerning their function. Very good and good results could be found with a strong reintegration of the tendon by using transosseus sutures with non resorbable suture material. The refixation with suture anchors showed disappointing results with early pull-outs of the anchor. Revision with screw augmentation with a washer had to be performed. Concerning the biomechanical forces, which show up on the olecranon (up to 40 NM), the refixation of the triceps tendon has proved to be extremely resistant against pull out forces. The good results by using non absorbable transosseus sutures led to a standardized procedure in our trauma center, even the rupture is not traumatic.

Can rotational alignment of total knee arthroplasty be measured on MRI?

BACKGROUND AND PURPOSE: The aim of this study was to investigate the potential of MRI to determine rotational alignment after TKA in comparison to the gold standard, CT. METHODS: Rotational alignment was measured in the transverse plane on CT and MR-images in 14 patients prior to TKA revision. Differences between CT and MRI measurements were analysed. RESULTS: There was a strong correlation between CT and MRI measurements for both the tibial (r = 0.929) and femoral (r = 0.942) components with a mean difference of 0.47 ± 1.3 and 0.13 ± 3.2 degrees, respectively. INTERPRETATION: Despite artefact formation, it can be concluded that the rotational alignment of metallic TKA components can be measured by MRI as accurately as by CT.

[Retention of the prosthesis in early periprosthetic infection after total hip arthroplasty]. / Gelenkerhalt bei Frühinfektion nach Hüfttotalendoprothese.

BACKGROUND: The rate of periprosthetic infection after total hip arthroplasty (THA) without patient-specific risk factors is about 1 %. The therapeutic challenges are control of infection, restoration of hip function and prevention of reinfection. In early infection, "irrigation and debridement" (I&D) with exchange of mobile components and retention of the prosthesis remains an attractive alternative to one- or two-stage revision. However, variable results have been reported in the literature. Recent studies have shown new algorithms of treatment for early infection and acute haematogenous infection after THA. PATIENTS AND METHODS: Recent therapeutic algorithms for early infections after THA and an overview of the literature are presented. We conducted a retrospective analysis of 73 patients with early postoperative infection or acute haematogenous infection (symptoms shorter than 4 weeks) after THA who were treated with I&D, exchange of mobile components and retention of the prosthesis at our hospital between 2002 and 2011. RESULTS: RESULTS from the recent literature have shown that the treatment concept of prosthetic retention can only be successful within a maximum time of symptoms of 3 weeks in cases of haematogenous infection and a maximum time span of 4 weeks after index operation in cases of early infection. In our retrospective study with 73 patients, the treatment was successful (free of infection) in 46 patients (63 %). A persistence of infection occurred in 27 patients (37 %). "Difficult to treat" bacteria were present in 28.8 % of the patients. CONCLUSION: The concept of irrigation and debridement with retention of the prosthesis is a valuable alternative to one- or two-stage revision THA, if a maximum time of 4 weeks after index operation in early infections and a maximum time of symptoms of 3 weeks in haematogenous infections are not exceeded. However, reinfection rates after I&D are higher than after two-stage procedures. Prerequisites for success of the I&D algorithm are a stable prosthesis, operable soft tissues, and germs susceptible to antibiotic treatment.

[The clinical outcome after occipitocervical fusion due to metastases of the upper cervical spine: a consecutive case series and a systematic review of the literature]. / Das klinische Outcome okzipitozervikaler Stabilisierungen bei Metastasen der oberen Halswirbelsäule: Eine konsekutive Fallserie mit systematischem Review der Literatur.

BACKGROUND: Increasing incidences of osseous metastatic malignancies and higher life expectancy in patients are resulting in a raise of occipitocervical metastases. Those patients with infaust prognosis have a significantly reduced quality of life. In Germany, between 800 and 1680 new cases per year are expected. Treatment algorithms include the evaluation of the general condition, the operability of visceral metastases, the tumor localization, the sensitivity to chemo-/radiotherapy, the fracture risk and the extent of neurological deficits and myelopathies. MATERIAL/METHODS: A systematic review on clinical studies or case series in posterior occipitocervical fusions due to metastases to the craniocervical transition yielded nine publications with 48 patients without neurological deficit. The mean survival time in the given follow-up was 6.44 months (n = 26; SD: 5,28; 95 % CI: 4.3-8.57). When measured, the clinical outcome was improved towards the VAS, the DENIS Pain Scale and the quality of life through the activities of daily living (ADL). We searched our clinical database for occipitocervical stabilizations in patients with craniocervical metastases. The prospectively collected data included the preoperative Tokuhashi score, SIN score, neurological status, length of hospitalization, perioperative course/loss of blood/complication rate, as well as the Karnofsky- index and pain measured by VAS preoperatively and in follow-up. RESULTS: Six patients were treated in this consecutive case series. The median age was 72 years (min./max.: 65/82), the average BMI 31.75 (min./max.: 19.3/38.1). The mean preoperative Karnofsky-index was 35 % (min./max.: 23.99/46.01; 95 % CI: 8.39) the mean preoperative Tokuhashi-score 7 (min./max.: 4/10), the mean preoperative VAS7 (min./max.: 4.8/9.2; 95 % CI: 1.68). There were no perioperative complications. In the follow-up, one patient showed a loosening of the screws in the osteolytic massae laterales and one patient suffered from a construct failure after fall. DISCUSSION: Metastases of the craniocervical transition are rare. The initial treatment of instability includes the application of a rigid Miami-J-collar or a Halo fixator. The decision for an operative procedure must accurately assess the individual patient characteristics to provide him a balanced concept between operational risk and clinical benefit. The assessment should be based on the life expectation and the expected quality of life in dependency of the respective therapeutic concept and its risks. The sole posterior stabilization of craniocervical instability through occipitocervical fusion leads to a reduction of pain, has a low perioperative risk, and may prevent a hospitalization. It is justified for selected patients to receive this treatment to help alleviate pain and to improve their quality of life. From our experience, rare cases of pain without instability should undergo conservative treatment in the first line. Due to the low availability of data on the manifestation and the clinical course of craniocervical metastases, there is a need for the collection of both the descriptive patient data include the radiographic findings as well as the clinical outcome and socio-economic factors using appropriate scoring systems.

Biomechanical methods for the assessment of fracture repair.

The progress of fracture healing is directly related to an increasing stiffness and strength of the healing fracture. Similarly the weight bearing capacity of a bone directly relates to the mechanical stability of the fracture. Therefore, assessing the progress of fracture repair can be based on the measurement of the mechanical stability of the healing fracture. However, fracture stability is difficult to assess directly due to various obstacles of which shielding of the mechanical properties by the fracture fixation construct is the most relevant one. Several assessment methods have been proposed to overcome these obstacles and to obtain some sort of mechanical surrogate describing the stability of the fracture. The most direct method is the measurement of the flexibility of a fracture under a given external load, which comprises the challenge of accurately measuring the deformation of the bone. Alternative approaches include the measurement of load share between implant and bone by internal or by external sensors. A direct 3 dimensional measurement of bone displacement is provided by radiostereometric analysis which can assess fracture migration and can detect fracture movement under load. More indirect mechanical methods induce cyclic perturbations within the bone and measure the response as a function of healing time. At lower frequencies the perturbations are induced in the form of vibration and at higher frequencies in the form of ultrasonic waves. Both methods provide surrogates for the mechanical properties at the fracture site. Although biomechanical properties of a healing fracture provide a direct and clinically relevant measure for fracture healing, their application will in the near future be limited to clinical studies or research settings.

Can the tibial slope be measured on lateral knee radiographs?

PURPOSE: The posterior tibial slope influences both the natural knee stability as well as the stability and kinematics after total knee arthroplasty (TKA). Exact definition of the posterior tibial slope (PTS) requires lateral radiographs of the lower limb. Only lateral knee radiographs are routinely obtained after TKA, however. The purpose of the present study therefore was to analyse the relationship between PTS measurement results on short and expanded lateral knee radiographs. METHODS: The PTS was measured on 100 consecutive lateral radiographs of the lower limb using the mechanical and three diaphyseal axes with various distances below the tibial plateau. RESULTS: Significant differences between PTS results were found for all three diaphyseal axes, with the smallest differences and the strongest correlation for a diaphyseal axis at 16 and 20 cm below the tibial plateau. Using short distances below the tibial plateau (6 and 10 cm) resulted in an overestimation of the PTS of 3°, on average. CONCLUSION: The PTS measurements in long lateral knee radiographs are more accurate compared to short radiographs. On short lateral knee radiographs, only a estimation of the PTS can be carried out. LEVEL OF EVIDENCE: Diagnostic study, Level II.

Morbidity of urinary tract infection after urodynamic examination of hospitalized SCI patients: the impact of bladder management.

STUDY DESIGN: Non-interventional, descriptive-observational cohorts study. OBJECTIVES: To assess the incidence of urinary tract infection (UTI) after urodynamic examination in patients with spinal cord injury (SCI) according to bladder management. SETTING: Level 1 trauma center. METHODS: Between January and December 2010 a total of 133 consecutive, hospitalized SCI patients were included and classified according to their bladder management. Urine specimen was obtained at the beginning of the urodynamic studies (UDS) and 3-5 days thereafter. 'Significant bacteriuria' (SBU) is defined by a CBU per ml level ≥10(5) in a urine culture. UTI thus is defined as a combination of a SBU and ≥100 leukocytes per µl in urine analysis. RESULTS: The overall incidence of UTI post UDS was 15.79%. In patients with sterile urine prior to urodynamics UTI was ascertained in 8.6% (de-novo-UTI). In contrast, 32.5% of the patients with SBU prior to UDS showed UTI 3 days later. There were only minor differences in the incidence of de-novo-UTIs in SCI patients who emptied their bladder by intermittent self catheterization or intermittent catheterization by attendant (8.82% and 6.67%, respectively). In SCI patients with reflex voiding however, the frequency of de-novo-UTIs was twice as high (14.28%). CONCLUSION: The recommendation of antibiotic prophylaxis for all SCI patients undergoing urodynamic examination is not commonly accepted and according to our data not justified. However, the analysis of subgroups revealed that SCI patients with unsuspected SBU prior to UDS and patients with reflex voiding are possibly at higher risk to acquire post-UDS infection.

[Osteoporotic fractures of the distal radius. What is new?]. / Osteoporotische Frakturen des distalen Radius. Was ist neu?

The demographic development will result in an increase of up to 30 % of distal radius fractures. There are various therapy options but what is new? Conservative therapy: conservative therapy is reserved for stable fractures only. Osteosynthesis by K-wires: due to low biomechanical stability in older patients, insufficient functional and radiological results were achieved. External fixator: external fixators are used in compound and complex fractures and show better results than K-wire osteosynthesis. Angular stable plate osteosynthesis: with angular stable plates it is possible to achieve good results with complex fractures and they are currently the method of choice. Intramedullary osteosynthesis: intramedullary nails result in a faster functional improvement than angular stable plates but have limitations. New is that 90% of osteoporotic distal radial fractures are treated with angular stable plates which have shown good results in single study groups.

Telemetric assessment of bone healing with an instrumented internal fixator: a preliminary study.

In an interdisciplinary project involving electronic engineers and clinicians, a telemetric system was developed to measure the bending load in a titanium internal femoral fixator. As this was a new device, the main question posed was: what clinically relevant information could be drawn from its application? As a first clinical investigation, 27 patients (24 men, three women) with a mean age of 38.4 years (19 to 66) with femoral nonunions were treated using the system. The mean duration of the nonunion was 15.4 months (5 to 69). The elasticity of the plate-callus system was measured telemetrically until union. Conventional radiographs and a CT scan at 12 weeks were performed routinely, and healing was staged according to the CT scans. All nonunions healed at a mean of 21.5 weeks (13 to 37). Well before any radiological signs of healing could be detected, a substantial decrease in elasticity was recorded. The relative elasticity decreased to 50% at a mean of 7.8 weeks (3.5 to 13) and to 10% at a mean of 19.3 weeks (4.5 to 37). At 12 weeks the mean relative elasticity was 28.1% (0% to 56%). The relative elasticity was significantly different between the different healing stages as determined by the CT scans. Incorporating load measuring electronics into implants is a promising option for the assessment of bone healing. Future application might lead to a reduction in the need for exposure to ionising radiation to monitor fracture healing.