Degeneration alters the biomechanical properties and structural composition of lateral human menisci.

OBJECTIVE: Because the literature relating to the influence of degeneration on the viscoelasticity and tissue composition of human lateral menisci remains contradictory or completely lacking, the aim of this study was to fill these gaps by comprehensively characterising the biomechanical properties of menisci with regard to the degree of degeneration. DESIGN: Meniscal tissue from 24 patients undergoing a total knee replacement was collected and the degeneration of each region classified according to Pauli et al. For biomechanical characterisation, compression and tensile tests were performed. Additionally, the water content was determined and infrared (IR) spectroscopy was applied to detect changes in the structural composition, particularly of the proteoglycan and collagen content. RESULTS: With an increasing degree of degeneration, a significant decrease of the equilibrium modulus was detected, while simultaneously the water content and the hydraulic permeability significantly increased. However, the tensile modulus displayed a tendency to decrease with increasing degeneration, which might be due to the significantly decreasing amount of collagen content identified by the IR measurements. CONCLUSION: The findings of the current study may contribute to the understanding of meniscus degeneration, showing that degenerative processes appear to mainly worsen viscoelastic properties of the inner circumference by disrupting the collagen integrity.

Difficult to treat: are there organism-dependent differences and overall risk factors in success rates for two-stage knee revision?

OBJECTIVES: Failure after two-stage procedure for periprosthetic joint infection (PJI) is a rare, but devastating complication. Some authors assume a correlation of underlying organisms and recurrence rate. Methicillin-resistant Staphylococci (MRS) and other organisms (quinolone-resistant Gram-negative bacteria, rifampicin-resistant Staphylococcus, Enterococcus, and Candida) are meant to be "difficult to treat" (DTT) with an inferior outcome for two-stage revision. In addition to the type of bacteria, some more risk factors seem to be present. The aim of this study was (1) to detect a difference of reinfection rates between reinfection-causing groups of bacteria ["difficult to treat" (DTT), "easy to treat" (ETT) and methicillin-resistant staphylococci (MRS)] after a two-stage procedure, and (2) find overall risk factors for reinfection in a standardized long (spacer insertion for at least 6 weeks) two-stage procedure for periprosthetic knee infection. METHODS: One hundred and thirty-seven two-stage revisions for periprosthetic knee infection were performed at one tertiary referral center. Finally, 96 patients could be included for analyses. Possible risk factors (comorbidities, prior surgery, etc.) and the types of organisms were documented. Quinolone-resistant Gram-negative bacteria, rifampicin-resistant Staphylococcus, Enterococcus, and Candida were classified as "difficult to treat" (DTT). Methicillin-resistant Staphylococci were summarized as "MRS", all other organism are summarized as "easy to treat" (ETT). Statistical analyses included univariate analysis (t test, Fisher's exact test, Chi square test) and logistic regression analysis. RESULTS: There were no statistical significant differences in recurrent infection rates between organism groups (DTT vs. ETT, p = 0.674; DTT vs. MRS, p = 0.705; ETT vs. MRS, p = 0.537). Risk factors seem to be "need of revision after first stage" (p = 0.019, OR 5.62) or completed second stage (p = 0.000, OR 29.07), numbers of surgeries (p = 0.028) and alcohol abuse (p = 0.019, OR 5.62). CONCLUSIONS: Revision needed during or after a two-stage exchange, numbers of surgeries and alcohol abuse are risk factors for recurrence, a different recurrence rates between organism-groups cannot be shown. The absence of significant differences in recurrence rates points to the importance of the individuality of each periprosthetic infection case: a reduction of necessary surgeries (with a thorough debridement, appropriate antibiotic addition to spacers) and the control of comorbidities (alcohol abuse) appear to be essential components of a two-stage exchange.

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.

[Measurement of acetabular cup inclination in anteroposterior pelvic radiogram : An indicator of quality after primary total hip arthroplasty?] / Die Pfanneninklinationsmessung in der Beckenübersichtsaufnahme : Ein Qualitätsindikator nach Hüft-TEP-Primärimplantation?

BACKGROUND AND OBJECTIVE: Acetabular cup orientation, consisting of pelvic positioning, version and inclination, can influence short-term and long-term results after total hip arthroplasty (THA). The radiographic measurement of acetabular cup inclination represents an indicator of quality for the EndoCert certification in Germany. The purpose of this study was to determine the intrarater and interrater reliability of radiographic measurements of acetabular cup inclination after THA. MATERIAL AND METHODS: In this study four independent investigators with different levels of expertise retrospectively performed measurements on radiograms (anteroposterior pelvic radiogram) from 99 patients. The intraclass correlation coefficient (ICC) and Pearson's correlation coefficient were determined and were considered statistically significant with r > 0.8 and p < 0.05. RESULTS AND CONCLUSION: A high correlation was found for both intrarater and interrater reliability based on determination of Pearson's correlation coefficient and the ICC with r > 0.9 and p < 0.001 for all measurements. Based on these results the radiographic measurement of acetabular cup inclination can be considered as a simple measuring tool with high intrarater and interrater reliability. As cup orientation consists of inclination, version and positioning, the exclusive measurement of cup inclination for radiological quality assessment needs to be discussed critically.

[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.

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.

[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.

[Accuracy of hip stem migration measurement on plain radiographs: reliability of bony and prosthetic landmarks]. / Erkennung von Hüftschaftsinterungen am Röntgenbild: Reliabilitätsuntersuchung knöcherner und prothetischer Landmarken.

BACKGROUND: In Germany, more than 150,000 total hip arthroplasties (THA) are performed annually. Early implant migration is supposed to be the best indicator for mechanical failure of femoral stems. Therefore, radiological evaluation of hip stems is routinely done by analyzing plain radiographs of THA. OBJECTIVES: The purpose of this study was to evaluate the accuracy of implant migration measurement on plain radiographs. MATERIAL AND METHODS: Two observers analyzed 44 anterior-posterior radiographs of the pelvis in 22 pain-free patients at least 2 years after implantation of an anatomical hip stem. The evaluation was performed on digital as well as conventional plain radiographs. Intraobserver reliability was analyzed by double measurements of each radiograph and the evaluation of the consecutive series of each patient. The anatomical structures of interest were the greater trochanter and the minor trochanter. Furthermore, the tip of the prosthesis, the shoulder of the implant, and the center of rotation were determined. RESULTS: The conventional measurement technique proved higher accuracy compared to the digital measurement technique. The best anatomical structure was the greater trochanter in the conventional technique and the minor trochanter in the digital technique. The best reference structure with regard to the implant was the shoulder of the prosthesis for both techniques. CONCLUSION: The recommended reference structures for the evaluation of implant migration on plain radiographs are the greater trochanter and the shoulder of the implant for the conventional measurement technique and the minor trochanter and the shoulder of the implant for the digital technique. Migration of an implant should not assumed before a determined difference of 2 mm.

[Treatment of extensor mechanism rupture after total knee arthroplasty]. / Behandlung der Strecksehnenruptur bei liegender Knietotalendoprothese.

Disruption of the extensor mechanism is one of the most devastating complications in knee arthroplasty with a reported incidence between 0.17 and 2.5 %. Due to a high rate of subsequent complications and poor clinical results, every effort should be made to avoid extensor mechanism disruption. In cases of disruption however, the orthopaedic surgeons must be aware of non-operative and surgical treatment options and their indications, timing, outcome and limitations. Non-operative treatment is feasible in cases of incomplete disruption of the quadriceps tendon with an extension deficit of less than 20°. Complete disruption of the quadriceps tendon or rupture of the patellar tendon should be treated operatively. Therapeutic strategies include direct repair of the tendon in acute disruption without retraction. Retraction as well as soft tissue damage necessitates augmentation of the tendon. Frequently used endogenous augments are the semitendinosus tendon as well as the gastrocnemius muscle. Exogenous options are allografts of the Achilles tendon or structured extensor mechanism grafts and synthetic augments to support endogenous tendon repair. The clinical results after extensor mechanism failure following total knee arthroplasty are less favourable compared to ruptures in native knee joints. The most common complications are postoperative stretching and the maintenance of an active extensor lag.

[Cost-effectiveness of a local bone bank based on thermodisinfection according to § 20 b and c AMG and alternatives]. / Zulassung einer lokalen Knochenbank nach § 20 b und c AMG und Einführung einer Thermodesinfektion: Lohnt sich der Aufwand?

INTRODUCTION: The German tissue law creates a different and more difficult situation for German musculoskeletal tissue banks. The objective aim of the new regulations was an increased safety and a reduction of viral and non-viral disease transmissions. In the authors' case, the government officials demanded a thermodisinfection for human femur heads. As a consequence of the requirements we aimed at an analysis of the cost-effectiveness of an admission according to § 20 b and c "Arzneimittelgesetz" (AMG) and implementation of the "lobator bonebank system™". METHOD: We calculated the working hour requirements for all medical staff involved in the tissue procedure. Additional costs were the current consumptions of two freezers (cooling power - 80 °C) for one year, the current consumption of one thermodisinfection process, the material cost of one disinfection and documentation set, expenses for laboratory examinations and the non-recurrent expenses for the admission according to § 20 b and c AMG and the "lobator bonebank system". Non-recurrent expenses were calculated for five years according to 610 tissue donations. We compared the overall costs for one processed femur head with the charges of an industrial chemical treating and irradiation. RESULTS: Expenses for medical doctors were 14.13 € and for nurses 3.71 €. Energy costs were 15.20 € for each stored femur head. Costs for the disinfection and documentation sets were 105.15 €, laboratory expenses were 107.25 €. The non-recurring fee for the admission according to § 20 b and c AMG was 2650 €, the cost for the lobator-sd2 was 12 495 €. The overall expenses for one disinfected femur head were 274.82 € compared to 535.23 € in a tissue service. CONCLUSION: To comply with legal requirements, operating expenses of the new tissue act increased. Nevertheless we could still prove the cost-effectiveness of a local bone bank in Germany.

[Does the body mass index influence the results of revision total knee arthroplasty?]. / Hat der Body-Mass-Index Einfluss auf das Ergebnis nach Knieendoprothesenwechseln?

BACKGROUND: Revision total knee arthroplasty (TKA) is one of the most demanding as well as increasing orthopaedic operations. The influence of a higher body weight or body mass index (BMI) on the results of revision TKA is not evident so far. We therefore hypothesised that obesity as well as a high body weight could influence the results of revision TKA. PATIENTS: 75 consecutive revision TKA in 75 patients were included and stratified according to a BMI greater or smaller than 30 kg/m2 and a body weight greater or smaller than 90 kg. The Knee Society score (KSS), the function and the knee subscales were analysed pre- and postoperatively as well as the pre- to postoperative improvement. The duration of the procedure, the occurrence of complications, the blood loss and the length of hospital stay were collected. RESULTS: All patients showed a significant improvement of the KSS and function score (p < 0.05). There was a tendency to superior results in patients with a smaller BMI and a lower body weight. This tendency was most pronounced in the function subscale which depicted significant differences in favour of a BMI smaller 30 kg/m2. No significant differences were observed in the other analysed factors. CONCLUSION: BMI greater than 30 kg/m2 as well as a higher body weight seem to negatively influence the function of revision TKA. However, all patients significantly improved after revision TKA and no differences were found according to the occurrence of complications. Therefore, revision TKA should not be refused to obese or heavy patients.

[Validity of digital templating in total hip arthroplasty: impact of stem design and planner's experience]. / Validität der computergestützten Hüfttotalendoprothesenplanung: Einfluss von Schaftdesign und Untersuchererfahrung.

INTRODUCTION: Preoperative planning in total hip arthroplasty decreases the risk of implant oversizing and facilitates intraoperative orientation. The size of the acetabular and femural components can be estimated. The aim of the present study was to determine the validitiy of digital templating. Furthermore, we compared the accuracy of three planners with different clinical experience and the effect of two different femoral component designs on planning accuracy. METHODS: On 60 a. p. pelvis radiographs, 60 unilateral, non-cemented total hip arthroplasties using the planning tool "AGFA-Orthopaedic-Tools Version V2.10®" (Fa. Agfa Health Care, Mertsel, Belgium) were repeatedly planned by three orthopaedic surgeons (planner A fifth year, planner B third year, planner C second year of training). All 60 patients received pressfit acetabular components, a straight stem was implanted in 28 (CLS-Spotorno™, Fa. Zimmer) and a short stem (Fitmore™, Fa. Zimmer) in 32 patients. The planned sizes of the components and the offset-variations were compared to the implanted sizes. RESULTS: The percental accuracy and ICC planning for the straight stem were 42.9 %/0.906 for planner A, 39.3 %/0.833 for planner B, and 28.6 %/0.836 for planner C. Planning the short stem, the percental accuracy and ICC were 34.4 %/0,886 for planner A, 21.9 %/0.708 for planner B, and 12.5 %/0.681 for planner C. The accuracy and ICC of templating the acetabular components were 35 %/0.796 for planner A, 30 %/0.725 for planner B, and 26.8 %/0.511 for planner C. Planning the sizes of both femoral components showed significant differences between planner A and C and planner B and C in Wilcoxon's signed-rank test. CONCLUSION: A lower level of experience showed no effect on the planning results of the acetabular components, but there were considerable and significant differences on planning the femoral components. Furthermore, the design of the femoral component had an impact on planning accuracy.

[Current role of minimally invasive total knee arthroplasty. A meta-analysis]. / Aktueller Stellenwert der minimalinvasiven Knieendoprothetik : Eine Metaanalyse.

Minimally invasive approaches are increasingly being used in total knee arthroplasty. By means of a review of the literature the pros and cons of minimally invasive approaches for total knee arthroplasty were analyzed. The potential advantages of reduced postoperative pain and improved early range of motion and mobility are opposed by the risks of malpositioning of the prosthetic components and impaired wound healing. Long-term improvement of knee function and quality of life should not be compromised by techniques promising temporary or secondary advantages.

[Minimally invasive total hip arthroplasty - trend or state of the art?: A meta-analysis]. / Minimalinvasive Hüftendoprothetik - nur Trend oder schon Standard?: Eine Metaanalyse.

Minimally invasive approaches in total hip arthroplasty are being used worldwide and continue to grow in popularity. Despite early reports of catastrophic failures, both the number of scientific publications as well as the number of orthopaedic surgeons practicing minimally invasive techniques in total hip arthroplasty are steadily increasing. By means of a systematic review of the literature, the current article weighs the potential advantages and disadvantages of minimally invasive techniques. A shorter skin incision, potentially less muscle damage, a faster rehabilitation and a clinically irrelevant lower blood loss may support the use of minimally invasive techniques. However, the potential impairment of wound cosmetics, the increased risk of periprosthetic fractures, implant malpositioning and lack of long-term results contradict the use of minimally invasive total hip arthroplasty as a standard treatment.

Successful treatment of an acquired haemorrhagic diathesis due to factor X deficiency with chemotherapy.

A 70-yr-old woman presented with a severe haemorrhagic diathesis due to an acquired factor X deficiency. A plasma infusion study showed that exogenous factor X was eliminated very effectively from the patient's circulation. A bone marrow biopsy was consistent with plasma cell dyscrasia. Neither an abdominal fat biopsy nor the bone marrow biopsy confirmed an amyloidosis, although clinically no other diagnosis seemed possible. Treatment with intermittent chemotherapy, consisting of vincristine, cytoxan and prednisone, yielded definite clinical and laboratory improvement.

A 73-year-old man with chronic lymphocytic leukaemia and a haemorrhagic pleural effusion.

A 73-year-old man presented with haemorrhagic pleural effusion, having been diagnosed with chronic lymphocytic leukaemia (CLL). The differential diagnosis of haemorrhagic pleural effusion is considered. Tuberculosis and pleural infiltration of CLL are considered most likely. Pleural biopsy confirms the diagnosis of pleural involvement of CLL in this case. Although pleural involvement of CLL has been reported several times the presentation of pleural effusion as the first symptom of CLL has not previously been described.