[Preoperative management in fast-track arthroplasty]. / Prästationäres Management in der Fast-Track-Endoprothetik.

BACKGROUND: Preoperative management of patients following fast-track arthroplasty protocols includes comprehensive patient information and risk stratification. IMPLEMENTATION: Fast-track protocols have implemented interdisciplinary patient seminars to explain the disease, operation, pain management, early mobilisation and each step of the patient pathway, as well as the role of a friend or relative as a "coach" during the whole process of treatment and rehabilitation to support and encourage the patient. There is strong evidence that preoperative anxiety is reduced. Digital apps can provide further information, practical tips and instructional videos to improve functional outcomes and to reduce pain levels. RISK FACTORS: Risk factors such as malnutrition, obesity, smoking, alcohol abuse, uncontrolled diabetes, and poor dental health are associated with a higher morbidity, mortality, complication rate and a longer length of stay and have to be assessed preoperatively and optimized if possible.

[Battle: Total hip arthroplasty or spine surgery first in patients with hip-spine-syndrome? : The arthroplasty surgeon's point of view]. / Battle: Operationsindikation beim Hip-Spine-Syndrom ­ Die Hüfte oder die Wirbelsäule zuerst? : Die Sicht des Endoprothetikers.

BACKGROUND: Frequently, patients with hip complaints also report lower back pain, and elective surgery may be indicated due to end-stage hip osteoarthritis and degenerative disc disease. Thus, we aim to answer the question of whether total hip arthroplasty (THA) or lumbar spine surgery should be performed first in patients with hip-spine-syndrome, from an arthroplasty surgeon's point of view. DECISION-MAKING: The present review demonstrates that in patients with an acute neurological deficit, lumbar spine surgery should be performed first. However, in patients without these symptoms, several arguments favour performing THA first, especially the increased risk of dislocation when performing THA after lumbar spine fusion (LSF) in comparison to "THA first" (4.6 vs. 1.7% after 2 years; p < 0,001). However, the risk of dislocation after THA remains increased in both scenarios, independent of surgical order. Consequently, arthroplasty surgeons should pay great attention to optimum component positioning, reconstruction of the hip anatomy, leg length and soft-tissue tension, while considering using large prosthesis heads or dual mobility cups when performing primary THA in patients with an increased risk of dislocation. In complex cases, we would encourage arthroplasty and spine surgeons working in cooperation on highly individual treatment concepts.

Different injury patterns after snowboard in children and adolescents.

BACKGROUND: Snowboarding is a very common sport especially among young adults. Common injuries are hand, wrist, shoulder and ankle injuries. PURPOSE: of this study was to analyze different injury pattern in children and young adults comparing with adults. METHODS: Patients who were admitted for ambulant or stationary treatment as a result of injury practicing snowboard received a questionnaire and were divided into three groups (children, young adults and adults) according to their age. Between october 2002 and may 2007 1929 injured snowboard sportsmen were included in the study. Data such as location, date and time of accident as well as information about the slope were carried out. In addition snowboard skills were classified and patients were questioned whether they wore special protectors. RESULTS: 32.5% of injured patients were female (n = 626) and 67.5% male (n = 1303) with a mean age of patients of 21.9 (7-66) years. 13% of all patients were in group I (children), 19.2% in group II (young adults) and 67.8% in group III (adults).Most common injuries with 60% of all accidents were injuries of the hand wrist especially in children beginning with snowboard sports. Injuries on the regular track were most common followed by jumps in the kicker park and rails in the fun-park. 20.6% in group I, 13.6% in group II and 12.8% group III did not wear any protectors. CONCLUSION: Children and adolescents presented different injury patterns than adults. Young participants of up to 14 years of age are endangered especially during the first days of learning this sport. Further development of protectors with regard to biomechanical characteristics is important to achieve an optimal protective effect. LEVEL OF EVIDENCE: 2b.

[Challenges of fast-track arthroplasty in Germany]. / Herausforderungen der Fast-Track-Endoprothetik in Deutschland.

BACKGROUND: While fast-track arthroplasty has been already established in many European countries and the United States, Germany still struggles to introduce appropriate programs. This is due to a variety of reasons. REASONS: From an organizational and medical scope, the fear of alteration, the adherence to restrictions rooted in historical tradition, the reluctance to interdisciplinary cooperation, and the lack of a willingness to implement externally-guided process analysis tools, stand in the foreground. This is system related, and especially the DRG-system with the continuous devaluation of lump compensation rates in primary hip and knee arthroplasty, also in 2020, hinders the implementation. The resulting fears and concerns that an additional reduction of the length-of-stay by fast-track programs is leading to a consistent reduction of the DRG returns, are understandable. On the other hand, the disconnectedness of the ambulatory, inpatient and rehabilitation sector in Germany inhibits the introduction of fast-track programs. SOLUTIONS: A well-thought-out change-management is the basic requirement for the successfull establishment of a Fast-Track-Program. Perspectively, a rethinking towards sector-comprehensive care strategies for the implantation of a total hip or knee replacement, including the required rehabilitation procedures, has to be demanded.

[Fast-track arthroplasty-intra- and post-operative management]. / Fast-Track-Endoprothetik ­ intra- und postoperatives Management.

Fast-track concepts in hip and knee arthroplasty focus on an early and safe mobilisation after surgery using a multi-modal pain concept with local infiltration anaesthesia. No drains, femoral nerve blocks or urinary catheters are used. Tranexamic acid reduces blood loss and transfusion rates. Cortisone is helpful in reducing pain, PONV and postsurgical stress response. Minimal invasive surgical techniques and the renouncement of a tourniquet lead to a better functional result and less pain. Restrictions and precautions are not evidence-based and should, therefore, be abandoned.

Instrumented gait analysis in patients with medial osteoarthritis of the knee after mobile-bearing unicompartmental knee arthroplasty.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) is an effective treatment for patients with medial osteoarthritis of the knee joint. Instrumented gait analysis provides an objective measure to quantify and qualify postoperative changes of gait. The purpose of this study was to evaluate standardized instrumented gait analysis for functional recovery and gait as an outcome of mobile-bearing UKA in patients with medial osteoarthritis of the knee. METHODS: Twenty-one patients with isolated medial osteoarthritis of the knee joint received mobile-bearing UKA. They were examined by a gait analysis before surgery and after an average follow-up time of seven months. Gait analysis was performed on a treadmill with six infrared-cameras to identify changes of gait characteristics (e.g., velocity, stride time, stride length, knee adduction and hip abduction). RESULTS: Mean velocity (chosen by individuals) increased from 0.61 to 0.76m/s and further significant advancements, particularly in the knee adduction and the hip abduction were detected. Time and length of strides improved significantly as well as the clinical scores American Knee Society Score (AKSS), Oxford-12, Hannover Functional Ability Questionnaire for Osteoarthritis (FFbH-OA) Score and Devane Score. CONCLUSION: Mobile-bearing UKA can restore physiological axis of the leg and improve gait and function of the knee joint. The combination of instrumented gait analysis with clinical scores constitutes an eligible measuring instrument to quantify and qualify changes in patients' gait patterns.

Mid-term results of lateral unicondylar mobile bearing knee arthroplasty: a multicentre study of 363 cases.

AIMS: The aim of this independent multicentre study was to assess the mid-term results of mobile bearing unicondylar knee arthroplasty (UKA) for isolated lateral osteoarthritis of the knee joint. PATIENTS AND METHODS: We retrospectively evaluated 363 consecutive, lateral UKAs (346 patients) performed using the Oxford domed lateral prosthesis undertaken in three high-volume knee arthroplasty centres between 2006 and 2014. Mean age of the patients at surgery was 65 years (36 to 88) with a mean final follow-up of 37 months (12 to 93) RESULTS: A total of 36 (10.5%) patients underwent revision surgery, giving a survival rate of 90.1% at three years (95% confidence intervals (CI) 86.1 to 93.1; number at risk: 155) and 85.0% at five years (95% CI 77.9 to 89.9; number at risk: 43). Dislocation of the mobile bearing occurred in 18 patients (5.6%) at three years (95% CI 1.0 to 16.4; number at risk: 154) and in 20 patients (8.5%) at five years (95% CI 1.0 to 27.0; number at risk: 42). There were no significant differences in the dislocation rate between the participating centres or the surgeons. We were not able to identify an effect of each surgeon's learning curve on the dislocation rate of the mobile bearing. The clinical outcome in patients without revision surgery at final follow-up was good to excellent, with a mean Oxford knee score of 40.3 (95% CI 39.4 to 41.2), a mean Tegner activity score of 3.2 (95% CI 3.1 to 3.3) and a mean University of California, Los Angeles score of 5.7 (95% CI 5.5 to 5.9). CONCLUSION: Our data, which consists of a high number of patients treated with mobile bearing UKA in the lateral compartment, indicates a high revision rate of 15% at five years with dislocation of the mobile bearing being the main reason for implant failure. Despite the good functional and clinical results and the high patient satisfaction in our study group, we therefore discontinued using mobile-bearing lateral UKA in favour of a fixed-bearing component. Cite this article: Bone Joint J 2018;100-B:42-9.

Change of gait in patients with lateral osteoarthritis of the knee after mobile-bearing unicompartmental knee arthroplasty.

PURPOSE: Patients with lateral osteoarthritis of the knee suffer not only from pain but also impaired gait and limited mobility. Common treatment options are total knee replacement and lateral unicompartmental knee arthroplasty (UKA). The domed lateral mobile-bearing Oxford Uni is a new treatment option for patients with isolated osteoarthritis of the lateral compartment of the knee joint. We used instrumented gait analysis and clinical scores to study patients before and after lateral UKA. METHODS: Nineteen patients suffering from lateral osteoarthritis underwent implantation of a mobile-bearing lateral UKA. They were examined in a gait analysis before the operation and after an average follow-up time of 7 months. Gait analysis was performed on a treadmill with six infrared cameras to identify gait characteristics (e.g. velocity, stride time, stride length, knee abduction or hip adduction). RESULTS: Mean velocity changed from 0.58 to 0.73 m/s. Significant advancements were also found in knee abduction and hip adduction. Time and length of strides improved significantly as well as the clinical scores American Knee Society Score, Oxford-12, FFb-H-OA and Devane Score. CONCLUSION: Patients with lateral osteoarthritis of the knee showed an impaired gait with an increased knee abduction and hip adduction angle. Implantation of a lateral mobile UKA can restore normal axis of the leg and improve gait and function of the knee. Instrumented gait analysis is a suitable measuring instrument to quantify and qualify the post-operative change of gait. LEVEL OF EVIDENCE: II.

[Revision after unicompartmental knee arthroplasty]. / Revision nach unikondylärer Knieprothese.

Unicompartmental arthroplasty is an efficient and approved treatment option of unicompartmental arthritis of the knee, being performed with increasing frequency worldwide. Compared to total knee replacement, there are several advantages such as faster recovery, lower blood loss, better functional outcome and lower infection rates. However, higher revision rates are a frequent argument against the use of unicompartmental arthroplasty. The following article gives an overview of failure mechanisms and strategies for revision arthroplasty. This article is based on a selective literature review including PubMed and relevant print media. Our own clinical experience is considered as well.

[The UniSpacer™: correcting varus malalignment in medial gonarthrosis. Preliminary results]. / UniSpacer™: corrección de la desalineación en varo en la gonartrosis medial. Resultados preliminares.

While options for operative treatment of leg axis varus malalignment in patients with medial gonarthrosis include several established procedures, such as unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA), or high tibial osteotomy (HTO), so far there has been little focus on a less invasive option introduced more recently: the UniSpacer™ implant, a modern, self-centering, metallic interpositional device for the knee. This study evaluates whether alignment correction can be achieved by UniSpacer™ arthroplasty as well as alignment change in the first 5 postoperative years is evaluated. Antero-posterior long leg stance radiographs of 15 legs were digitally analyzed to assess alignment change: two relevant angles and the deviation of the mechanical axis of the leg were analyzed before and after surgery. Additionally, the change of the postoperative alignment was determined one and five years postoperatively. Analyzing the mechanical tibiofemoral angle, a significant leg axis correction was achieved, with a mean valgus change of 4.7±1.9°; a varus change occurred in the first postoperative year, while there was no significant further change of alignment seen five years after surgery. The UniSpacer™ corrects malalignment in patients with medial gonarthrosis; however, a likely postoperative change in alignment due to implant adaptation to the joint must be considered before implantation.

The heidelberg sports activity score - a new instrument to evaluate sports activity.

OBJECTIVE: An appropriate measuring instrument for assessing if sports activity changes after a surgical treatment is not available yet. We hypothesised that the Heidelberg Sport Activity Score is a valid and adequate instrument for measuring sport activity in patients before and after operative treatment. DESIGN: This retrospective study presents a new score (Heidelberg Sports Activity Score - HAS) for measuring the sport activity in 11 selected sports. Validity, sensitivity and test-retest-reliability have been assessed. SETTING: The score includes importance of the sports for patients, impairment of the corresponding joint, and frequency and duration of the sporting activities undertaken. The HAS was validated using 3 criteria: external validation, internal comparison of groups and correlation with the Tegner Score. PATIENTS: A total of 655 patients were recruited for this study. The inclusion criterion was a planned or already received reconstruction (such as a high tibial osteotomy or implantation of a hip or knee prosthesis). The sport activity of these patients was evaluated before and after treatment. MAIN OUTCOME MEASUREMENT: The mean HAS was 32.1 points preoperatively and 37.0 postoperatively (p=0.017). RESULTS: A high correlation was found between the HAS and the Tegner Score (TS) (r=0.729; p=0.010). The Test-Retest- Reliability was performed within a time interval of 2 weeks and a significant correlation of r=0.752 was found (p<0.01). Sensitivity was analysed using a sample of patients before and after high tibial osteotomy. CONCLUSIONS: The HAS is a new, easy to use, effective and valid measuring instrument for the assessment of sports activity in patients before and after operative treatment.

UniSpacer™: corrección de la desalineación en varo en la gonartrosis medial. Resultados preliminares / The UniSpacer™: correcting varus malalignment in medial gonarthrosis. Preliminary results

Aunque entre las opciones del tratamiento operatorio de la desalineación en varo del eje de la pierna en pacientes con gonartrosis medial se incluyan varios procedimientos consolidados como, por ejemplo, la artroplastia unicompartimental de rodilla (AUR), la artroplastia total de rodilla (ATR) o la osteotomía tibial valguizante (OTV), hasta ahora no se ha prestado demasiada atención a una opción menos invasiva de reciente introducción: el implante UniSpacer™, un dispositivo interposicional, autocentrador y metálico para la rodilla. En el presente estudio (14 pacientes, 15 rodillas) nos dedicamos a evaluar si es posible corregir la alineación realizando una artroplastia con el UniSpacer™, así como el cambio de alineación que se produce en los 5 años posteriores a la intervención quirúrgica. Se han analizado digitalmente las radiografías anteroposteriores en carga de 15 rodillas para calcular el cambio de alineación: se analizaron 2 ángulos relevantes y la desviación del eje mecánico de la pierna antes y después de la intervención quirúrgica. Además, se determinó el cambio de la alineación posoperatoria transcurridos entre uno y 5 años. Al analizar el ángulo tibiofemoral mecánico, observamos que se logró una corrección significativa del eje de la pierna, con una media de cambio en valgo de 4,7±1,9°. Durante el primer año posterior a la intervención quirúrgica se produjo un cambio en varo, aunque no se detectó ningún cambio adicional significativo de alineación durante los 5 años posteriores a la intervención quirúrgica. El UniSpacer™ corrige eficientemente la desalineación de algunos pacientes con gonartrosis medial. No obstante, antes de proceder a la implantación deberá tenerse en cuenta la posibilidad de que se produzcan cambios posoperatorios adicionales no inmediatos de la alineación como consecuencia de la adaptación del implante (AU)

While options for operative treatment of leg axis varus malalignment in patients with medial gonarthrosis include several established procedures, such as unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA), or high tibial osteotomy (HTO), so far there has been little focus on a less invasive option introduced more recently: the UniSpacer™ implant, a modern, self-centering, metallic interpositional device for the knee. This study evaluates whether alignment correction can be achieved by UniSpacer™ arthroplasty as well as alignment change in the first 5 postoperative years is evaluated. Antero-posterior long leg stance radiographs of 15 legs were digitally analyzed to assess alignment change: two relevant angles and the deviation of the mechanical axis of the leg were analyzed before and after surgery. Additionally, the change of the postoperative alignment was determined one and five years postoperatively. Analyzing the mechanical tibiofemoral angle, a significant leg axis correction was achieved, with a mean valgus change of 4.7±1.9°; a varus change occurred in the first postoperative year, while there was no significant further change of alignment seen five years after surgery. The UniSpacer™ corrects malalignment in patients with medial gonarthrosis; however, a likely postoperative change in alignment due to implant adaptation to the joint must be considered before implantation (AU)

The effect of bone lavage on femoral cement penetration and interface temperature during Oxford unicompartmental knee arthroplasty with cement.

BACKGROUND: Aseptic loosening is the most common cause for revision unicompartmental knee arthroplasty and is associated with failure of the bone-cement or cement-implant interface. The purpose of the present study was to analyze different bone lavage techniques for the bone-cement and cement-implant interfaces of the femoral component and to study the effect of these techniques on cement penetration and on interface temperature. METHODS: In an experimental cadaver study, Oxford unicompartmental knee arthroplasty was performed in twenty-four matched-paired knees to study the effect of pulsed lavage compared with syringe lavage on femoral cement penetration and interface temperature. Interface temperature, cement penetration pressure, and ligament tension forces were measured continuously during the procedure, and cement penetration was determined by performing sagittal bone cuts. RESULTS: Cleansing the femoral bone stock with use of pulsed lavage (Group B) led to increased femoral cement penetration (mean, 1428 mm²; 95% confidence interval, 1348 to 1508 mm²) compared with syringe lavage (Group A) (mean, 1128 mm²; 95% confidence interval, 1038 to 1219 mm²) (p < 0.001). Interface temperature was higher in Group B (mean 22.6°C; 95% confidence interval, 20.5°C to 24.1°C) than in Group A (mean, 21.0°C; 95% confidence interval, 19.4°C to 23.0°C) (p = 0.028), but temperatures never reached critical values for thermal damage to the bone. CONCLUSIONS: Pulsed lavage leads to an increased femoral cement penetration without the risk of heat necrosis at the bone-cement interface.

Treatment of periprosthetic tibial plateau fractures in unicompartmental knee arthroplasty: plates versus cannulated screws.

INTRODUCTION: Periprosthetic tibial plateau fractures (TPF) are rare but represent a serious complication in unicompartmental knee arthroplasty. The most common treatment for these fractures is osteosynthesis with cannulated screws or plates. The aim of this study was to evaluate two different treatment options for periprosthetic fractures. The hypothesis was that angle-stable plates show significantly higher fracture loads than fixation with cannulated screws. MATERIALS AND METHODS: Twelve matched, paired fresh-frozen tibiae with periprosthetic TPF were used for this study. In Group A, osteosyntheses with cannulated screws were performed, whereas in Group B plates fixated the periprosthetic fracture. DEXA bone density measurement and standard X-rays (AP and lateral) were performed before loading the tibiae under standardised conditions with a maximum load of up to 10.0 kN. After the specimens had been loaded, fracture patterns and fracture loads were analysed and correlated with BMD, BMI, bodyweight (BW), age and size of the tibial implant. RESULTS: In the plate group all tibiae fracture occured with a median load of F (max) = 2.64 (0.45-5.68) kN, whereas in the group with cannulated screws fractures occurred at a mean load of F (max) = 1.50 (0.27-3.51) kN. The difference was statistically significant at p < 0.05. DISCUSSION: Angle-stable plates showed significantly higher fracture loads than fixation with cannulated screws. Cannulated screws show a reduced stability of the tibial plateau. Therefore in periprosthetic TPF, osteosyntheses with angle-stable plates should be recommended instead of cannulated screws.

Mobile-bearing lateral unicompartmental knee replacement with the Oxford domed tibial component: an independent series.

The Oxford mobile-bearing unicompartmental knee replacement (UKR) is an effective and safe treatment for osteoarthritis of the medial compartment. The results in the lateral compartment have been disappointing due to a high early rate of dislocation of the bearing. A series using a newly designed domed tibial component is reported. The first 50 consecutive domed lateral Oxford UKRs in 50 patients with a mean follow-up of three years (2.0 to 4.3) were included. Clinical scores were obtained prospectively and Kaplan-Meier survival analysis was performed for different endpoints. Radiological variables related to the position and alignment of the components were measured. One patient died and none was lost to follow-up. The cumulative incidence of dislocation was 6.2% (95% confidence interval (CI) 2.0 to 17.9) at three years. Survival using revision for any reason and aseptic revision was 94% (95% CI 82 to 98) and 96% (95% CI 85 to 99) at three years, respectively. Outcome scores, visual analogue scale for pain and maximum knee flexion showed a significant improvement (p < 0.001). The mean Oxford knee score was 43 (SD 5.3), the mean Objective American Knee Society score was 91 (SD 13.9) and the mean Functional American Knee Society score was 90 (SD 17.5). The mean maximum flexion was 127° (90° to 145°). Significant elevation of the lateral joint line as measured by the proximal tibial varus angle (p = 0.04) was evident in the dislocation group when compared with the non-dislocation group. Clinical results are excellent and short-term survival has improved when compared with earlier series. The risk of dislocation remains higher using a mobile-bearing UKR in the lateral compartment when compared with the medial compartment. Patients should be informed about this complication. To avoid dislocations, care must be taken not to elevate the lateral joint line.

[Cemented total hip arthroplasty in Germany - update 2010]. / Stand der zementierten Hüftendoprothetik in Deutschland 2010.

BACKGROUND: The results of a national survey from 1998 showed that only around 10 % of orthopaedic surgeons in Germany had strictly implemented modern third-generation cementing techniques in total hip arthroplasty (THA). A 2005 update showed an improvement up to 29.4 %. The study was repeated in 2010 in order to evaluate the current situation and to determine whether modern cementing techniques have become more popular. MATERIAL AND METHODS: A detailed, slightly modified questionnaire regarding cement and bone preparation, cementing techniques on acetabulum and femur, and implant types was sent to 492 German orthopaedic and trauma hospitals, as well as to visiting surgeons with an interest in THA. The survey was conducted over 6 months. The response rate was 51.8 %, 255 questionnaires were available for evaluation and statistical analysis. RESULTS: Palacos R+G bone cement remained the most widely used cement (52.2 %). The mixing times given varied significantly. Vacuum mixing systems have again become more popular (85.2 %). In the femur 78.6 % of the surgeons attempted to preserve cancellous bone and 77.8 % used pulsatile (jet) lavage. Retrograde cement application via a cement gun was done in 85.8 %. Cement restrictors were used in more than 98 %. Only 72.7 % of the surgeons implemented sustained cement pressurisation and preferred a cement mantle thickness over 2 mm (55.2 %). Only 18.1 % drilled multiple small acetabular keyholes and 66.5 % used jet lavage. In 67.9 % no cement gun was used and in 70.7 % the cement was applied at high viscosity. Cement pressurisation was done manually in 89.1 %. The Müller straight stem device remained the most popular implant. Only 7.4 % of the centres implanted less than 20 and 40.3 % more than 100 cemented stems per year, whereby higher THA volumes correlated with better cementing technique. CONCLUSION: The results of this survey demonstrate that, in comparison to 2005, the current state of cemented THA, in particular cementing technique has generally significantly improved. Future emphasis should focus on continued surgeon education and training, as the cementing techniques are of utmost importance for long-term durability.

Extended sagittal saw cut significantly reduces fracture load in cementless unicompartmental knee arthroplasty compared to cemented tibia plateaus: an experimental cadaver study.

PURPOSE: Periprosthetic tibial plateau fractures represent a rare but serious complication in unicompartmental knee arthroplasty and are associated with extended sagittal tibial bone cuts. These can occur during the surgery, weaken the posterior cortex of the tibia and are associated with periprosthetic tibial plateau fractures. Although excellent long-term results have been reported with cemented unicompartmental knee arthroplasty, there is high interest in cementless fixation. The aim of the study was to compare fracture loads of cementless and cemented unicompartmental knee arthroplasty. METHODS: Tibial components of the Oxford Uni were implanted in six paired fresh-frozen tibiae with a defined extended saw cut (10°) at the dorsal cortex of each specimen. In one set, surgery was performed with cement fixation, and in the other, cementless components were implanted. Vertical loads were then applied under standardised conditions to fracture the specimens. RESULTS: Median loads of 3.7 (0.7-6.9) kN led to fractures in the cemented group, whereas cementless fixated tibiae fractured with a median load of 1.6 (0.2-4.3) kN (P = 0.02). CONCLUSION: The loading capacity in tibiae with cementless components is significantly less compared to cemented fixation. The results show that in case of an extended sagittal bone cut patients especially those with poor bone quality who are treated with a cementless unicompartmental knee arthroplasty are at higher risk for periprosthetic tibial fractures.

The importance of pulsed lavage on interface temperature and ligament tension force in cemented unicompartmental knee arthroplasty.

BACKGROUND: Mechanical loosening is the most common cause of revision in unicompartmental knee arthroplasty. We determined the effect of bone lavage on tibial cement penetration and interface temperature with controlled ligament tension forces. We presumed pulsed lavage would allow increased cement penetration compared with syringe lavage. METHODS: Cemented unicompartmental knee arthroplasty was performed in 12 pairs of fresh-frozen knees. Lavage was performed using pulsed lavage on one side (A) and syringe lavage on the other (B). Cement penetration pressure, interface temperature, and ligament tension forces were continuously monitored during the operation. Screened radiographs were taken and cement penetration under the tibial plateau was measured. FINDINGS: The pulsed lavage group showed a mean cement penetration area of 187.24 (SD 36.37) mm², whereas 144.29 (SD 35.74) mm(2) was measured in the group with syringe lavage. Cement penetration pressure was 13.29 (SD 8.69) kPa in Group A and 20.21 (SD 7.78) kPa in Group B. Maximum interface temperatures of 46.99°C were observed in Group A and 45.02°C in Group B. INTERPRETATION: Our data showed pulsed lavage cleansing of the cancellous tibial bone substantially improved cement penetration compared with syringe lavage without reaching the temperature threshold for bone necrosis. We recommend the routine use of pulsed lavage to improve long-term fixation.

Late peri-prosthetic femoral fracture as a major mode of failure in uncemented primary hip replacement.

Peri-prosthetic femoral fracture after total hip replacement (THR) is associated with a poor outcome and high mortality. However, little is known about its long-term incidence after uncemented THR. We retrospectively reviewed a consecutive series of 326 patients (354 hips) who had received a CLS Spotorno replacement with an uncemented, straight, collarless tapered titanium stem between January 1985 and December 1989. The mean follow-up was 17 years (15 to 20). The occurrence of peri-prosthetic femoral fracture during follow-up was noted. Kaplan-Meier survival analysis was used to estimate the cumulative incidence of fracture. At the last follow-up, 86 patients (89 hips) had died and eight patients (eight hips) had been lost to follow-up. A total of 14 fractures in 14 patients had occurred. In ten hips, the femoral component had to be revised and in four the fracture was treated by open reduction and internal fixation. The cumulative incidence of peri-prosthetic femoral fracture was 1.6% (95% confidence interval 0.7 to 3.8) at ten years and 4.5% (95% confidence interval 2.6 to 8.0) at 17 years after the primary THR. There was no association between the occurrence of fracture and gender or age at the time of the primary replacement. Our findings indicate that peri-prosthetic femoral fracture is a significant mode of failure in the long term after the insertion of an uncemented CLS Spotorno stem. Revision rates for this fracture rise in the second decade. Further research is required to investigate the risk factors involved in the occurrence of late peri-prosthetic femoral fracture after the implantation of any uncemented stem, and to assess possible methods of prevention.