Smoking is associated with higher short-term risk of revision and mortality following primary hip or knee arthroplasty: a cohort study of 272,640 patients from the Dutch Arthroplasty Registry.

BACKGROUND AND PURPOSE: Patients actively smoking at the time of primary hip or knee arthroplasty are at increased risk of direct perioperative complications. We investigated the association between smoking status and risk of revision and mortality within 2 years following hip or knee arthroplasty. METHODS: We used prospectively collected data from the Dutch Arthroplasty Register. All primary total hip arthroplasties (THAs), total knee arthroplasties (TKAs), and unicondylar knee arthroplasties (UKAs) with > 2 years' follow-up were included (THA: n = 140,336; TKA: n = 117,497; UKA: n = 14,807). We performed multivariable Cox regression analyses to calculate hazard risks for differences between smokers and non-smokers, while adjusting for confounders (aHR). RESULTS: The smoking group had higher risk of revision (THA: aHR 1.3, 95% confidence interval [CI] 1.1-1.4 and TKA: aHR 1.4, CI 1.3-1.6) and risk of mortality (THA: aHR 1.4, CI 1.3-1.6 and TKA: aHR 1.4, CI 1.2-1.6). Following UKA, smokers had a higher risk of mortality (aHR 1.7, CI 1.0-2.8), but no differences in risk of revision were observed. The smoking group had a higher risk of revision for infection following TKA (aHR 1.3, CI 1.0-1.6), but not following THA (aHR 1.0, CI 0.8-1.2). CONCLUSION: This study showed that the risk of revision and mortality is higher for smokers than for non-smokers in the first 2 years following THA and TKA. Smoking could contribute to complications following primary hip or knee arthroplasty.

S100A8/A9 drives monocytes towards M2-like macrophage differentiation and associates with M2-like macrophages in osteoarthritic synovium.

OBJECTIVES: Macrophages are key orchestrators of the osteoarthritis (OA)-associated inflammatory response. Macrophage phenotype is dependent on environmental cues like the inflammatory factor S100A8/A9. Here, we investigated how S100A9 exposure during monocyte-to-macrophage differentiation affects macrophage phenotype and function. METHODS: OA synovium cellular composition was determined using flow cytometry and multiplex immunohistochemistry. Healthy donor monocytes were differentiated towards M1- and M2-like macrophages in presence of S100A9. Macrophage markers were measured using flow cytometry and phagocytic activity was determined using pHrodo Red Zymosan A BioParticles. Gene expression was determined using qPCR. Protein secretion was measured using Luminex and ELISA. RESULTS: Macrophages were the dominant leucocyte subpopulation in OA synovium. They mainly presented with a M2-like phenotype, although the majority also expressed M1-like macrophage markers. Long-term exposure to S100A9 during monocyte-to-macrophage differentiation increased M2-like macrophage markers CD163 and CD206 in M1-like and M2-like differentiated cells. In addition, M1-like macrophage markers were increased in M1-like, but decreased in M2-like differentiated macrophages. In agreement with this mixed phenotype, S100A9 stimulation modestly increased expression and secretion of pro-inflammatory markers and catabolic enzymes, but also increased expression and secretion of anti-inflammatory/anabolic markers. In accordance with the upregulation of M2-like macrophage markers, S100A9 increased phagocytic activity. Finally, we indeed observed a strong association between S100A8 and S100A9 expression and the M2-like/M1-like macrophage ratio in end-stage OA synovium. CONCLUSION: Chronic S100A8/A9 exposure during monocyte-to-macrophage differentiation favours differentiation towards a M2-like macrophage phenotype. The properties of these cells could help explain the catabolic/anabolic dualism in established OA joints with low-grade inflammation.

Diagnosing knee osteoarthritis in patients, differences between general practitioners and orthopedic surgeons: a retrospective cohort study.

BACKGROUND: knee complaints are one of the most common reasons to consult the general practitioners in the Netherlands and contribute to the increasing burden on general practitioners. A proportion of patients that are referred to orthopedic outpatient clinics are potentially referred unnecessarily. We believe osteoarthritis is not always considered by general practitioners as the cause of atraumatic knee complaints. This may impede early recognition and timely care of osteoarthritis complaints and lead to unnecessary referrals. METHODS: the aim of this study was to compare the frequency of (differential) diagnosis of osteoarthritis mentioned in referral letters of general practitioners with the frequency of osteoarthritis mentioned as orthopedic diagnosis at the outpatient clinic. Therefore we conducted a retrospective cohort study based on data collected from referral letters and the corresponding outpatient clinic reports of patients with atraumatic knee complaints of 45 years or older referred to a regional hospital in Nijmegen, The Netherlands in the period from 1-6-2019 until 1-01-2020. RESULTS: a total of 292 referral letters were included. In the younger aged patients (45-54 years) osteoarthritis was mentioned less frequent and meniscal lesions were mentioned more frequent in referral letters when compared to diagnoses made at the outpatient clinic. Differences in differential diagnosis of osteoarthritis as well as meniscal lesions between orthopedic surgeon and general practitioners were found (both p < 0.001, McNemar). Matching diagnoses were present in 58.2% when all referral letters were analyzed (n = 292) and 75.2% when only referrals containing a differential diagnosis were analyzed (n = 226). Matching diagnoses were present in 31.6% in the younger age categories (45-54 years). A linear trend showing fewer matching diagnoses in younger patient categories was observed (p < 0.001). CONCLUSIONS: Osteoarthritis was less frequently mentioned in general practitioner referral letters among the differential diagnosis then it was diagnosed at the outpatient clinic, especially in younger patients (45-54 years). Also matching diagnoses in younger patients were evidently lower than in older patients, partly explained by underdiagnosing of osteoarthritis in younger patients in this cohort. Better recognition of osteoarthritis in younger patients and changing the diagnostic approach of general practitioners might improve efficacy in knee care. Future research should focus on the effectiveness of musculoskeletal triage, the need for multidisciplinary educational programs for patients and promotion of conservative treatment modalities among general practitioners.

Epidemiology of Injuries during Judo Tournaments.

Objective: To determine the injury incidence proportion, distribution of injuries by anatomical location; injury type; injury severity, time loss; mechanism and situations of injuries; and the relative risk of injuries by gender, age, and weight categories during judo tournaments. Study Design. It is a systematic review. Data Sources. A systematic review of the literature was conducted via searches in PubMed, EMBASE, Web of Science, CINAHL, SPORTDiscus, Google Scholar, and PEDro. Eligibility Criteria. All original studies on the incidence of injuries during judo tournaments were included. Results: Twenty-five studies were included out of the 1979 studies. Using the modified AXIS tool score for quality assessment, seven were rated as having good quality, nine were rated as having fair quality, and four were rated as having poor quality. The injury incidence proportion during tournaments ranged from 2.5% to 72.5% for injuries requiring medical evaluation and 1.1% to 4.1% for injuries causing time loss (i.e., inability to continue game participation). The most commonly reported injury location was the head, followed by the hand, knee, elbow, and shoulder. The most frequent types of injury were sprains, followed by contusions, skin lacerations, strains, and fractures. In judo tournaments, injuries were more often sustained during standing fights (tachi-waza) than in ground fights (ne-waza). Conclusion: The tournament injury incidence proportion ranged from 2.5% to 72.5% for injuries requiring medical attention and 1.1% to 4.1% for injuries causing time loss. The head was the most frequently injured body part, and sprain was the most frequent injury type. However, current reports on injuries during judo tournaments are heterogeneous and inconsistent, limiting our understanding of in-match injury risks. Future studies should utilize the guidelines of the International Olympic Committee consensus meeting statement on the methodological approach to injury reporting. We recommend a judo-specific extension of this statement to fit the unique features of judo sports practice.

Post-traumatic knee osteoarthritis; the role of inflammation and hemarthrosis on disease progression.

Knee injuries such as anterior cruciate ligament ruptures and meniscal injury are common and are most frequently sustained by young and active individuals. Knee injuries will lead to post-traumatic osteoarthritis (PTOA) in 25-50% of patients. Mechanical processes where historically believed to cause cartilage breakdown in PTOA patients. But there is increasing evidence suggesting a key role for inflammation in PTOA development. Inflammation in PTOA might be aggravated by hemarthrosis which frequently occurs in injured knees. Whereas mechanical symptoms (joint instability and locking of the knee) can be successfully treated by surgery, there still is an unmet need for anti-inflammatory therapies that prevent PTOA progression. In order to develop anti-inflammatory therapies for PTOA, more knowledge about the exact pathophysiological mechanisms and exact course of post-traumatic inflammation is needed to determine possible targets and timing of future therapies.

Dutch Guideline on Knee Arthroscopy Part 2: non-meniscus intra-articular knee injury: a multidisciplinary review by the Dutch Orthopaedic Association.

Background and purpose - A guideline committee of medical specialists and a physiotherapist was formed on the initiative of the Dutch Orthopedic Association (NOV) to update the Guideline Arthroscopy of the Knee: Indications and Treatment 2010. This next Guideline was developed between June 2017 and December 2019. In part 1 we focused on the meniscus; this part 2 addresses all other aspects of knee arthroscopy.Methods - The guideline was developed in accordance with the criteria of the AGREE instrument (AGREE II: Appraisal of Guidelines for Research and Evaluation II) with support of a professional methodologist from the Dutch Knowledge Institute of Medical Specialists. The scientific literature was searched and systematically analyzed. Conclusions and recommendations were formulated according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. Recommendations were developed considering the balance of benefits and harms, the type and quality of evidence, the values and preferences of the people involved, and the costs.

Dutch Guideline on Knee Arthroscopy Part 1, the meniscus: a multidisciplinary review by the Dutch Orthopaedic Association.

Background and purpose - A guideline committee of medical specialists and a physiotherapist was formed on the initiative of the Dutch Orthopedic Association (NOV) to update the guideline Arthroscopy of the Knee: Indications and Treatment 2010. This next guideline was developed between June 2017 and December 2019. In this Part 1 we focus on the meniscus, in Part 2 on all other aspects of knee arthroscopy.Methods - The guideline was developed in accordance with the criteria of the AGREE instrument (AGREE II: Appraisal of Guidelines for Research and Evaluation II) with support of a professional methodologist from the Dutch Knowledge Institute of Medical Specialists. The scientific literature was searched and systematically analyzed. Conclusions and recommendations were formulated according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. Recommendations were developed considering the balance of benefits and harms, the type and quality of evidence, the values and preferences of the people involved, and the costs.

Complications of a self-centering sliding tibial tubercle osteotomy for patellofemoral complaints; low incidence of non-union and fracture.

BACKGROUND: A tibial tubercle osteotomy (TTO) is a commonly performed procedure in young and active patients with patellofemoral complaints. Previous small patient series demonstrated a relatively high risk of complications, which appear to be technique dependent. The purpose of this large case series is to quantify the risk of procedure specific postoperative complications related to a uniform self-centering TTO technique in a large cohort, performed by two different surgeons in one center. HYPOTHESIS: We hypothesize that non-union or fracture occurs in less than 1% of the procedures. PATIENTS AND METHODS: Five hundred and twenty-nine knees in four hundred and forty-seven patients who underwent a self-centering TTO with at least one year of follow-up were included. We performed a retrospective cohort review. Tibial fracture, osteotomy non-union, neurovascular complications, infection and wound complications that required surgical intervention were defined as major complications, miscellaneous complications were defined minor. RESULTS: The major finding in this study is the low incidence of non-union (0.6%) and tibial fracture (0.4%). In total 9 (1.7%) major complications were reported. Minor complications included superficial wound infection in five patients, two patients had a venous thrombo-embolism (VTE). CONCLUSION: A self-centering TTO is a relatively safe technique with a low number of non-union and fracture. LEVEL OF EVIDENCE: Level IV, retrospective cohort study.

A detaching, V-shaped tibial tubercle osteotomy is a safe procedure with a low complication rate.

INTRODUCTION: In patients with recurrent patellar dislocations, a tibial tubercle osteotomy (TTO) can be indicated to correct patella alta or an increased trochlear groove-tibial tubercle distance. Several surgical techniques are described. Previous studies emphasize that detaching osteotomies results in devascularisation, which can lead to non-union and tibial shaft fractures. The aim of this study was to report the complication rates directly related to the surgical technique of a V-shaped TTO, where the tubercle is completely released from its periosteum using a step-cut osteotomy. METHODS: The retrospective case series comprised a large cohort of 263 knees with patella alta in 203 patients who underwent a V-shaped TTO, with or without additional realignment procedures, between March 2004 and October 2017. Data were obtained from available patient files. Complications were defined as minor or major. RESULTS: Thirteen major complications were registered (4.9%) including two tibial fractures (0.75%) and one non-union (0.37%). Five complications (1.9%) were defined as minor. Removal of the screws because of irritation or pain was seen in 22 cases (8.2%). CONCLUSION: A V-shaped TTO is a safe procedure. The presumed higher risk for tibial fractures or pseudo-arthrosis could not be confirmed.

Dutch translation and validation of the Norwich Patellar Instability score and Banff Patella Instability Instrument in patients after surgery for patellar instability.

Recently, two new English specific patient reported outcome measures (PROMs) to evaluate treatment of patients with patellofemoral complaints have been developed : the Banff Patella Instability Instrument (BPII) and the Norwich Patellar Instability (NPI) score. This study was designed to translate and validate the BPII and NPI in Dutch patients after surgical treatment for patellar instability. Forward and backward translation of the outcome measures was performed. Patients who had been surgically treated for patellar instability filled out the NPI and BPII together with the Kujala Knee Score, numeric rating scales, Knee disability and Osteoarthritis Outcome Score (KOOS) and SF- 36. We assessed internal consistency and construct validity. We evaluated the presence of ceiling and floor effects. Ninety-seven patients completed the online questionnaires. The internal consistency of the NPI and BPII score was excellent for both outcome measures. The BPII and NPI had good correlations with other PROMs. For the BPII we found no floor nor ceiling effect. For the NPI we found a floor effect but no ceiling effect. Our results indicate that the Dutch version of the BPII and the NPI can be used for patients with patellar instability. Both PROMs have specific (dis) advantages.

Patellar height measurements: Insall-Salvati ratio is most reliable method.

PURPOSE: Patella alta is a risk factor for patellofemoral pain and instability. Several measurement methods and imaging modalities are in use to measure patellar height. The first aim of this study was to determine the intra- and interrater reliability of different patellar height measurement methods on conventional radiography (CR), CT and MRI. The second aim was to examine the applicability of patellar height measurement methods originally designed for CR on CT and MRI. METHODS: Forty-eight patients who were treated for patellar instability were included. All patients had undergone a pre-operative conventional radiograph, CT scan and MRI. Five methods for measuring patellar height were performed on radiographs, CT and MRI by four observers. For each measurement, the intra- and interrater reliability was determined by calculating the intra-class correlation coefficient (ICC). A Bland-Altman analysis was performed for measurements with an ICC ≥ 0.70. RESULTS: The Insall-Salvati (IS) ratio was the only measurement that showed good intra- and inter-observer reliability on CR, CT and MRI. The intra- and inter-observer reliability of the patellotrochlear index (PTI) for MRI was good to excellent for all observers. The IS ratio showed a moderate to good reliability for comparison of all three imaging modalities with the best agreement between radiography and MRI. The other patellar height measurements showed only poor to moderate inter-method agreement. CONCLUSION: In this study, the Insall-Salvati ratio shows better intra- and inter-observer reliability than the Blackburne-Peel ratio, the Caton-Deschamps ratio and the modified Insall-Salvati ratio on all imaging modalities. Radiography and CT seem to have better reliability than MRI. The patellotrochlear index, however, shows good inter- and intra-observer reliability on MRI. Only for the IS method was there acceptable agreement between CR and MRI. This means that the established Insall-Salvati normal values could be used for MRI as well. This study shows that the most reliable method to measure patella height is the Insall-Salvati ratio measured on conventional radiographs or the patellotrochlear index on MRI. LEVEL OF EVIDENCE: Level II diagnostic.

Evaluation of early wound leakage as a risk factor for prosthetic joint infection.

BACKGROUND AND PURPOSE: Prosthetic joint infection (PJI) is a serious complication resulting from total knee arthroplasty (TKA) or total hip arthroplasty (THA). In this study, patients with a PJI are compared with patients with an uncomplicated postoperative course to identify relevant risk factors for PJI. METHODS: A matched case-control study was performed with patients undergoing fast-track, elective unilateral TKA or THA. The following data were collected: demographics, surgery-related characteristics (perioperative blood loss, use of cement, body temperature), and postoperative characteristics (hematoma formation, wound leakage, blood transfusion, length of stay [LOS]). CONCLUSIONS: When the PJI group was compared with the control group, there was significantly more wound leakage during hospital stay (88% vs. 36%, p = .001) and early wound dressing changes in the first 3 days after surgery (88% vs. 40%, p = .002). Hematoma formation was observed more in the PJI patients group (44% vs. 10%, p = .005). A trend test revealed a significant association between the total number of wound dressing changes and development of PJI (p < .001); 72% of PJI patients had a length of stay of ≥4 days compared with 34% of controls (odds ratio 10.5; 95% CI [2.1-52.3]; p = .004). IMPLICATIONS FOR PRACTICE: Early postoperative wound drainage and hematoma formation directly correlate with PJI. This resulted in a significantly higher number of dressing changes and longer LOS. The nurse practitioner has a central role in postoperative care and is the first to recognize signs of an adverse postoperative clinical course.

Most Important Frequently Asked Questions From Patients With Hip or Knee Osteoarthritis: A Best-Worst Scaling Exercise.

OBJECTIVE: To collect and prioritize the frequently asked questions (FAQs) that patients with hip or knee osteoarthritis (OA) and health care professionals consider to be the most important; to identify informational needs that go beyond guideline recommendations. METHODS: FAQs were collected among health care professionals and from the arthritis helpline of the Dutch Arthritis Foundation. After deleting overlapping FAQs, the remaining FAQs were prioritized by patients and health care professionals using a maximum difference scaling method. A hierarchical Bayesian method was used to calculate relative importance scores. Differences between health care professionals and patients were analyzed using independent t-tests. RESULTS: A total of 28 health care professionals and the arthritis helpline provided 192 FAQs. After deleting overlapping FAQs, 60 FAQs were prioritized by 94 patients (57 [60.6%] women, mean age 67.3 years) and 122 health care professionals (67 [54.9%] women, mean age 45.7 years). The FAQ "What can I do myself to decrease symptoms and to prevent the OA from getting worse?" was prioritized as the most important by both patients and professionals. FAQs that were highly prioritized by patients but significantly different from professionals were more directed toward treatment options offered by health care professionals, whereas highly prioritized FAQs of professionals were more often focused on treatment options involving self-management. CONCLUSION: The health care professionals' perspective on informational needs differs from that of OA patients. These differences are important to address in order to achieve more active involvement of patients in their own treatment process.

Assessing the Efficacy of an Educational Smartphone or Tablet App With Subdivided and Interactive Content to Increase Patients' Medical Knowledge: Randomized Controlled Trial.

BACKGROUND: Modern health care focuses on shared decision making (SDM) because of its positive effects on patient satisfaction, therapy compliance, and outcomes. Patients' knowledge about their illness and available treatment options, gained through medical education, is one of the key drivers for SDM. Current patient education relies heavily on medical consultation and is known to be ineffective. OBJECTIVE: This study aimed to determine whether providing patients with information in a subdivided, categorized, and interactive manner via an educational app for smartphone or tablet might increase the knowledge of their illness. METHODS: A surgeon-blinded randomized controlled trial was conducted with 213 patients who were referred to 1 of the 6 Dutch hospitals by their general practitioner owing to knee complaints that were indicative of knee osteoarthritis. An interactive app that, in addition to standard care, actively sends informative and pertinent content to patients about their illness on a daily basis by means of push notifications in the week before their consultation. The primary outcome was the level of perceived and actual knowledge that patients had about their knee complaints and the relevant treatment options after the intervention. RESULTS: In total, 122 patients were enrolled in the control group and 91 in the intervention group. After the intervention, the level of actual knowledge (measured on a 0-36 scale) was 52% higher in the app group (26.4 vs 17.4, P<.001). Moreover, within the app group, the level of perceived knowledge (measured on a 0-25 scale) increased by 22% during the week within the app group (from 13.5 to 16.5, P<.001), compared with no gain in the control group. CONCLUSIONS: Actively offering patients information in a subdivided (per day), categorized (per theme), and interactive (video and quiz questions) manner significantly increases the level of perceived knowledge and demonstrates a higher level of actual knowledge, compared with standard care educational practices. TRIAL REGISTRATION: International Standard Randomized Controlled Trial Number ISRCTN98629372; http://www.isrctn.com/ISRCTN98629372 (Archived by WebCite at http://www.webcitation.org/73F5trZbb).

The incidence of mild hypothermia after total knee or hip arthroplasty: A study of 2600 patients.

Hypothermia is associated with a higher risk of perioperative complications and occurs frequently after total joint arthroplasty (TJA). The incidence of hypothermia following total joint arthroplasty was assessed with its risk factors and its correlation with PJI. Correlation of hypothermia with age, gender, BMI, type of arthroplasty surgery, type of anesthesia, operation time, blood loss, date of surgery and PJI was evaluated in 2600 patients. Female gender and spinal anesthesia increased the risk for hypothermia whereas an increased BMI and surgery duration correlated decreased the risk of hypothermia. The incidence of hypothermia decreased over time without a correlation with PJI.

Preliminary effects of a regional approached multidisciplinary educational program on healthcare utilization in patients with hip or knee osteoarthritis: an observational study.

BACKGROUND: Providing relevant information on disease and self-management helps patients to seek timely contact with care providers and become actively involved in their own care process. Therefore, health professionals from primary care, multiple hospitals and health organisations jointly decided to develop an educational program on osteoarthritis (OA). The objective of the present study was to determine preliminary effects of this OA educational program on healthcare utilization and clinical outcomes. METHODS: We developed an educational group-based program consisting of 2 meetings of 1.5 h, provided by a physiotherapist, a general practitioner (GP) and orthopaedic surgeon or specialized nurse. The program included education on OA, (expectations regarding) treatment options and self-management. Patients were recruited through searching the GPs' electronic patients records and advertisements in local newspapers. At baseline and at 3 months follow-up participating OA patients completed questionnaires. Paired-sample t-tests, McNemar's test and Wilcoxon Signed-Rank test were used to estimate the preliminary effects of the program. RESULTS: A total of 146 participants in 3 districts attended the sessions, of whom 143 agreed to participate in this study; mean age 69.1 years (SD10.2).107 (75%) participants completed both baseline and follow up assessments. The proportion of participants who had visited their GP in the 3 months after the program was lower than 3 months previous to the program (40% versus 25%, p-value 0.01). Also, we observed a decrease in proportion of patients who visited the physio- and exercise therapist, (36.1% versus 25.0%, p-value 0.02). Both illness perceptions and knowledge on OA and treatment options changed positively (Δ-1.8, 95%CI:0.4-3.4, and Δ2.4, 95%CI:-3.0 - -1.6 respectively). No changes in BMI, pain, functioning and self-efficacy were found. However, a trend towards an increase in physical activity was observed. CONCLUSIONS: Our results show that a multidisciplinary educational program may result in a decrease in healthcare utilization and has a positive effect on illness perceptions and knowledge on OA due to clear and consistent information on OA and it treatment options. TRIAL REGISTRATION: Netherlands Trial Register ( NTR5472 ). Registered 22 September 2015.

Incidence and Risk Factors of Postoperative Urinary Retention and Bladder Catheterization in Patients Undergoing Fast-Track Total Joint Arthroplasty: A Prospective Observational Study on 371 Patients.

BACKGROUND: Postoperative urinary retention (POUR) appears to be a common complication in lower limb joint arthroplasty; however, reports on its incidence vary. There is no general consensus on its definition and there is no scientific evidence on treatment principles. We performed a prospective observational study to establish the incidence of POUR and its risk factors, including the preoperative postvoid residual urine volume and the perioperative fluid balance, in fast-track total joint arthroplasty (TJA). The preoperative residual urine volume and the perioperative fluid balance have not been studied in previous literature in the context of TJA and POUR. METHODS: Three hundred eighty-one patients who underwent TJA of the lower limb were observed on developing POUR according to our local treatment protocol. Data on possible risk factors for POUR were collected including the perioperative fluid balance and the preoperative residual urine volume. RESULTS: In total, 46.3% of patients were catheterized. A preoperative postvoid urine retention is a significant predictor of catheterization for postoperative residual urine (P = .03). Spinal anesthesia was correlated with urinary retention (P = .01). There was no cause-effect relationship between POUR and the perioperative fluid balance. CONCLUSION: This study underlines POUR as a common complication in fast-track lower limb arthroplasty, with spinal anesthesia as a risk factor. A higher preoperative residual urine volume leads to higher postoperative residual volume, but not to a higher change in urinary retention. Increased perioperative fluid administration is not correlated with the incidence of POUR. Furthermore, there seems to be little rationale for monitoring residual urine volume both preoperatively and postoperatively.

Kneeling and standing up from a chair as performance-based tests to evaluate knee function in the high-flexion range: a randomized controlled trial comparing a conventional and a high-flexion TKA design.

BACKGROUND: We compared the functional outcome between conventional and high-flexion total knee arthroplasty (TKA) using kneeling and sit-to-stand tests at 1 year post-operative. In addition, the patient's daily functioning, pain and satisfaction were quantified using questionnaires. METHODS: We randomly assigned 56 patients to receive either a conventional or a high-flexion TKA. Primary outcomes were maximum flexion angle and maximum thigh-calf contact measured during kneeling at 1 year post operatively. Secondary outcomes were the angular knee velocity and ground reaction force ratio measured during sit-to-stand performance tests, and questionnaires. RESULTS: At one year post-operative, maximum knee flexion during kneeling was higher for the high-flexion TKA group (median 128.02° (range 108-146)) compared to the conventional TKA group (119.13° (range 72-135)) (p = 0.03). Maximum thigh-calf contact force was higher for the high flexion TKA group (median 17.82 N (range 2.98-114.64)) compared to the conventional TKA group (median 9.37 N (range 0.33-46.58))(p = 0.04). The sit-to-stand tests showed a significantly higher angular knee velocity in the conventional TKA group (12.12 rad/s (95%CI 0.34-23.91); p = 0.04). There were no significant differences between groups in ground reaction force ratios and patient-reported outcome scores. CONCLUSION: Although no differences were found in patient-reported outcome scores, differences in performance-based tests were clearly apparent. Standing up from a chair at 90° of knee flexion appeared to be easier for the conventional group. The kneeling test revealed significantly higher weight-bearing knee flexion for the high-flex group. Hence, if kneeling is an important activity for a patient a high-flex design may be recommendable. TRIAL REGISTRATION: The study was retrospectively registered in ClinicalTrials.gov under identifier NCT00899041 (date of registration: May 11, 2009).