Lower limb alignment becomes more varus and hyperextended from supine to bipedal stance in asymptomatic, osteoarthritic and prosthetic neutral or varus knees.

PURPOSE: Knee alignment is a fundamental measurement in the assessment, monitoring and surgical management of patients with osteoarthritis. There is a lack of data regarding how static tibiofemoral alignment varies between supine and standing conditions. This study aimed to quantify the relationship between supine and standing lower limb alignment in asymptomatic, osteoarthritic (OA) and prosthetic (TKA) knees. METHODS: A non-invasive position capture system was used to assess knee alignment for 30 asymptomatic controls and 31 patients with OA both before and after TKA. Coronal and sagittal mechanical femorotibial angles were measured supine with the lower limb in extension and in bipedal stance. Changes between conditions were analysed using paired ttests. Vector plots of ankle centre displacement relative to the knee centre from supine to standing were produced to allow three-dimensional visualisation. RESULTS: All groups showed a trend towards varus and extension when going from supine to standing. Mean change for asymptomatic knees was 1.2° more varus (p = 0.001) and 3.8° more extended (p < 0.001). For OA knees this was 1.1° more varus (p = 0.009) and 5.9° more extended (p < 0.001) and TKA knees 1.9° more varus (p < 0.001) and 5.6° more extended (p < 0.001). CONCLUSION: The observed consistent changes in lower limb alignment between supine and standing positions across knee types suggests the soft tissue envelope restraining the knee may have a greater influence on dynamic alignment changes than the underlying bony deformity. This highlights the importance of quantifying soft tissue behaviour when planning, performing and evaluating alignment dependent surgical interventions of the knee. When routinely assessing any type of knee, clinicians should be aware that subtle consistent alignment changes occur under weightbearing conditions and tailor their treatments accordingly. LEVEL OF EVIDENCE: II.

A comparison of outcomes in morbidly obese, obese and non-obese patients undergoing primary total knee and total hip arthroplasty.

BACKGROUND: Obesity is a growing public health issue with the prevalence of morbid obesity, (Body Mass Index (BMI) ≥ 40 kg/m2) increasing. There is some evidence these patients have more peri- and post-operative complications and poorer outcomes when undergoing arthroplasty procedures. This audit aimed to determine and compare the outcomes of non-obese, obese and morbidly obese patients undergoing arthroplasty at our institution. METHOD: This was a retrospective audit of patients from our institution who had undergone total knee (TKA) or total hip arthroplasty (THA) in 2009. Data collected were: age, gender, BMI, length of stay (LOS), Oxford knee or hip score (OKS/OHS), satisfaction and complications up to two years post operation. Patients were divided into three groups: BMI < 30, BMI 30-40 and BMI > 40. Outcomes for each BMI group were compared. RESULTS: 1014 TKA and 906 THA operations were included. When compared to obese and non-obese patients, morbidly obese patients undergoing TKA had a mean LOS one day longer, a mean OKS four points lower and higher rates of postoperative problems, 37% vs. 21%. For THA patients there was no difference in LOS, OHS score was two points lower for each increasing BMI category and postoperative problems increase from 25% for non-obese to 31% for obese and 38% for morbidly obese patients. CONCLUSION: These results will be useful in informing obese patients of their potential outcomes following TKA or THA. These patients can then make a more informed choice before proceeding with arthroplasty.

Risk Factors for Surgical Site Infection Following Lower Limb Arthroplasty: A Retrospective Cohort Analysis of 3932 Lower Limb Arthroplasty Procedures in a High Volume Arthroplasty Unit.

BACKGROUND: Surgical site infection (SSI) is a debilitating complication of lower limb arthroplasty with significant morbidity and increased costs. Numerous risk factors are associated with SSI. METHODS: In an effort to identify novel risk factors for SSI, we undertook a retrospective cohort study of 1832 primary total hip arthroplasties and 2100 primary total knee arthroplasties performed in our high volume arthroplasty unit over a 2-year period. RESULTS: Two risk factors were identified for SSI following total hip arthroplasty: body mass index ≥30 and peri-operative blood transfusion. Eight risk factors were identified for SSI following total knee arthroplasty: hypertension, peri-operative blood transfusion, skin closure using 2-octyl cyanoacrylate, use of oral steroids, reduced serum mean cell volume, reduced mean cell hemoglobin, elevated serum neutrophil count, and use of warfarin or rivaroxaban for venous thromboembolism prophylaxis. CONCLUSIONS: Our work proposes a number of previously undocumented risk factors in relation to SSI. Further investigation is required to ascertain the magnitude of their effect.

Minimally invasive total knee replacement: techniques and results.

In this review, we outlined the definition of minimally invasive surgery (MIS) in total knee replacement (TKR) and described the different surgical approaches reported in the literature. Afterwards, we went through the most recent studies assessing MIS TKR. Next, we searched for potential limitations of MIS knee replacement and tried to answer the following questions: Are there selective criteria and specific patient selection for MIS knee surgery? If there are, then what are they? After all, a discussion and conclusion completed this article. There is certainly room for MIS or at least less invasive surgery for appropriate selected patients. Nonetheless, there are differences between approaches. Mini-medial parapatellar is easy to master, quick to perform and potentially extendable, whereas mini-subvastus and mini-midvastus are trickier and require more caution related to risk of haematoma and vastus medialis oblique (VMO) nerve damage. Current evidence on the safety and efficacy of mini-incision surgery for TKR does not appear fully adequate for the procedure to be used without special arrangements for consent and for audit or continuing research. There is an argument that a sudden jump from standard TKR to MIS TKR, especially without computer assistance such as navigation, patient-specific instrumentation or robotic, may breach a surgeon's duty of care towards patients because it exposes patients to unnecessary risks. As a final point, more evidence is required on the long-term safety and efficacy of this procedure which will give objective shed light on real benefits of MIS TKR.

Total Hip Arthroplasty Improves Pain and Function but Not Physical Activity.

BACKGROUND: People with hip osteoarthritis are likely to limit physical activity (PA) engagement due to pain and lack of function. Total hip arthroplasty (THA) reduces pain and improves function, potentially allowing increased PA. PA of THA patients was quantified to 12 months postoperation. The hypothesis was that postoperatively levels of PA would increase. METHODS: PA of 30 THA patients (67 ± 7 years) was objectively measured preoperatively and 3 and 12 months postoperation. Harris Hip Score (HHS), Oxford Hip Score (OHS), and 6-minute walk test (6MWT) were recorded. Mixed linear modelling was used to examine relationships of outcomes with time, baseline body mass index (BMI), age, gender, and baseline HHS. RESULTS: Time was not a significant factor in predicting volume measures of PA, including sit-to-stand transitions, upright time, and steps. Notably, baseline BMI was a significant predictor of upright time, steps, largest number of steps in an upright bout, HHS, and 6MWT. Baseline HHS helped predict longest upright bout, cadence of walking bouts longer than 60 seconds, and OHS. The significant effect of participant as a random intercept in the model for PA outcomes suggested habituation from presurgery to postsurgery. CONCLUSION: Volume measures of PA did not change from presurgery to 12 months postsurgery despite improvement in HHS, OHS, and 6MWT. Baseline BMI was a more important predictor of upright activity and stepping than time. Preoperative and postoperative PA promotion could be used to modify apparently habitual low levels of PA to enable full health benefits of THA to be gained.

Patient Factors Associated with Shorter Length of Stay Following Total Hip Arthroplasty-A Retrospective Cohort Study.

INTRODUCTION: Total hip arthroplasty (THA) is an increasingly common procedure in the United Kingdom and incurs vast costs, with a mean length of stay (LOS) of 5.5 days. Reducing LOS plays a key role in improving cost-effectiveness, morbidity, and patient satisfaction following many orthopaedic procedures. The aim of this study was to identify attributes in patients with the shortest LOS following THA, with a view to targeting those with the potential for early discharge. MATERIALS AND METHODS: 1280 THA cases over one year at one institution were reviewed in a retrospective case note study. Of these, 131 patients had LOS=2 days. Various factors (age, gender, American Society of Anesthesiologists (ASA) score, primary diagnosis, body mass index (BMI), socio-economic status) were compared between this group and the rest of the cohort. Further characteristics of the short LOS group were also explored to identify trends for future study. RESULTS: Lower age, male gender, and low ASA grade were significantly associated with the short LOS group (all p<0.001). BMI, primary diagnosis, and socioeconomic status showed no significant differences. Short LOS patients were also noted to have few comorbidities, family at home, and independent transport. CONCLUSION: Younger age, male gender, and lower ASA grade are associated with early discharge following THA, and could be used to identify patients suitable for early discharge.

Midterm Outcomes of Revision Total Hip Arthroplasty Using a Modular Revision Hip System.

BACKGROUND: The growth in hip arthroplasty surgery has meant a corresponding escalating revision burden with increasing challenges for the orthopaedic surgeon. The purpose of this study was to review clinical outcomes of a modular revision hip system within a single institution. METHODS: We retrospectively reviewed a cohort of modular revision hip system stems performed in our institution between January 2005 and October 2012 giving a potential minimum follow-up of 2 years. Clinical outcomes data on complications, Oxford Hip Score (OHS, 0-48) and patient satisfaction were collected. Radiographic outcomes including subsidence were assessed. Implant survival was estimated using Kaplan Meier analysis. RESULTS: 115 stems in 106 patients were identified. All cause survival was 82% (95%CIs: 73%-89%) at 6.1 years; survival excluding infection being 99% (95%CIs: 93%-100%). There was a low incidence of subsidence (seven stems) and no peri-prosthetic fractures. Primary cause of re-revision in this series was re-infection with only one re-revision for mechanical failure. Median Oxford Hip Score at mean follow up 4.1 years (2-9) was 40 (14-48) and 93% of patients reported being satisfied with their revision surgery. CONCLUSION: This study showed good clinical outcomes and survival using a modular revision stem with low mechanical failure and subsidence. Recurrence of infection remains a challenge in revision surgery.

What Do Scottish Patients Expect of Their Total Knee Arthroplasty?

BACKGROUND: The aim of this study was to carry out an in-depth assessment of patient expectations before surgery in a representative sample of the Scottish population undergoing primary total knee arthroplasty and also assess the influence of demographic factors and preoperative functions on expectations. METHODS: This was a prospective cohort study of 200 patients treated in our institution from November 2011 to July 2013. Patients received standard preoperative preparation including consultation with a surgeon, an information booklet and a DVD. Patients completed the Hospital for Special Surgery Knee Replacement Expectation Survey along with the EuroQol EQ-5D-3L health questionnaire on the day of admission. RESULTS: Fifty-nine percent of the cohort were women, mean age 67.7 years (45-84 years), mean body mass index 32.5 (21-50), mean preoperative Oxford Knee Score 17 (1-44). Relief of pain and improved ability to walk were the most important expectations, followed by the ability to use public transport and/or drive, ability to change position, ability to walk down stairs, and the ability to carry out routine daily activities and/or chores. Some expectations were unrealistic. No relationships between expectations and demographics, including preoperative function, were found. CONCLUSION: This study suggests that patients have very high and sometimes unrealistic expectations regarding their improvements after total knee arthroplasty even after detailed preoperative consultation and education. In addition, these expectations cover a wide range of dimensions. We suggest that to effectively manage patients' expectations, it is important to assess each patient individually and reinforce what expectations can realistically be achieved.

Upright Time and Sit-To-Stand Transition Progression After Total Hip Arthroplasty: An Inhospital Longitudinal Study.

BACKGROUND: Although early mobilization in hospital is a key element of post-total hip arthroplasty rehabilitation, it is poorly documented. METHODS: To gain quantitative insight into inhospital mobilization, upright times and sit-to-stand transitions (STS) were measured using a thigh-mounted movement sensor in 44 participants (13 males and 31 females), age 50 to 82 years, in an observational, postsurgery, inhospital, longitudinal study. RESULTS: Some participants performed no activity in the first 24 hours after surgery. However, in the last 24 hours before discharge, participants performed a median of 40 (interquartile range [IQR], 15) STS and spent 134 minutes (IQR, 74 minutes) upright. Activity in rehabilitation constituted 19.4% (IQR, 15.8%) of STS and 13.3% (IQR, 5.5%) of upright time. Females spent longer in hospital (80 hours; IQR, 24) compared to males (54 hours; IQR, 26). CONCLUSION: Although there was considerable activity within rehabilitation periods, a large majority of STS and upright time occurred outside rehabilitation. Within the last 24 hours in hospital, all participants were upright for prolonged periods and completed numerous STS.

Reproduction of Hip Offset and Leg Length in Navigated Total Hip Arthroplasty: How Accurate Are We?

This study assesses how accurately we can restore hip offset and leg length in navigated total hip arthroplasty (THA). 152 consecutive patients with navigated THA formed the study group. The contra-lateral hip formed control for measuring hip offset and leg length. All radiological measurements were made using Orthoview digital software. In the normal hip offset group, the mean is 75.73 (SD- 8.61). In the reconstructed hip offset group, the mean is 75.35 (SD - 7.48). 95.39% had hip offset within 6 mm of opposite side while 96.04% had leg length restored within 6 mm of contra-lateral side. Equivalence test revealed that the two groups of hip offsets were essentially the same. We conclude that computer navigation can successfully reproduce hip offset and leg length accurately.

Hip-Knee-Ankle Radiographs Are More Appropriate for Assessment of Post-Operative Mechanical Alignment of Total Knee Arthroplasties than Standard AP Knee Radiographs.

Weight-bearing hip-knee-ankle (HKA) radiographs are the gold standard for measuring lower limb alignment after total knee arthroplasty (TKA), however the majority of UK units use standardised anteroposterior (AP) knee radiographs. This study aimed to determine whether standardised AP knee radiographs adequately assess lower limb alignment after TKA. HKA radiographs from 50 post-operative TKAs were cropped to the size of a standardised AP knee radiograph allowing comparison of mechanical and anatomical alignment measurements between the two views. Repeatability of alignment measurements was significantly better for HKA radiographs, however, there was poor agreement of the mechanical alignment measured between the two views. Standardised AP knee radiographs are insufficient to assess the mechanical alignment of post-operative TKA and we recommend routinely using HKA radiographs.

Discovery of novel irreversible inhibitors of interleukin (IL)-2-inducible tyrosine kinase (Itk) by targeting cysteine 442 in the ATP pocket.

IL-2-inducible tyrosine kinase (Itk) plays a key role in antigen receptor signaling in T cells and is considered an important target for anti-inflammatory drug discovery. In order to generate inhibitors with the necessary potency and selectivity, a compound that targeted cysteine 442 in the ATP binding pocket and with an envisaged irreversible mode of action was designed. We incorporated a high degree of molecular recognition and specific design features making the compound suitable for inhaled delivery. This study confirms the irreversible covalent binding of the inhibitor to the kinase by x-ray crystallography and enzymology while demonstrating potency, selectivity, and prolonged duration of action in in vitro biological assays. The biosynthetic turnover of the kinase was also examined as a critical factor when designing irreversible inhibitors for extended duration of action. The exemplified Itk inhibitor demonstrated inhibition of both TH1 and TH2 cytokines, was additive with fluticasone propionate, and inhibited cytokine release from human lung fragments. Finally, we describe an in vivo pharmacodynamic assay that allows rapid preclinical development without animal efficacy models.

Repeatability and accuracy of a non-invasive method of measuring internal and external rotation of the tibia.

PURPOSE: The ability to quantify rotational laxity of the knee would increase understanding of functional rotatory instability, identify the best treatment methods for soft tissue injury, and have a role in diagnosis of soft tissue injury. This study aimed to report the reliability, repeatability and precision of a non-invasive adaptation of image-free navigation technology by comparing with a validated invasive system used for computer-assisted surgery. METHODS: Twelve cadaveric lower limbs were tested with a commercial image-free navigation system using passive trackers secured by bone screws. They were then tested a non-invasive fabric-strap system. Manual application of torque was used consistent with clinical examination to rotate the tibia to the end of internal rotation and external rotation range. Measurements were taken at 10° intervals from full extension to 90° flexion, and protocol was repeated twice using each system. Intraclass correlation coefficient (ICC) was used to reflect reliability of measurements. At each flexion interval, coefficient of repeatability (CR) was calculated for each system, and limits of agreement (LOA) were used to reflect agreement between the systems. RESULTS: The results for internal and external rotation were combined throughout flexion: ICC invasive; 0.94 (0.86-0.99), non-invasive; 0.92 (0.7-0.99), CR invasive; 2.4° (1.3-4.8°), non-invasive; 3.5° (1.8-6.6), LOA; 8.2° (4.3-13.5). CONCLUSION: Non-invasive optical tracker fixation gives improved agreement with a validated method of measurement compared with devices measuring tibial rotation by foot position. This system gives the added possibility of dynamic, weight-bearing testing in the clinically important range of 0°-30° knee flexion without the need for any limb restraint.

A comparison of variable angle versus fixed angle distal femoral resection in primary total knee arthroplasty.

This study assessed whether using a variable distal valgus resection angle improved post-operative coronal lower limb alignment in total knee arthroplasty (TKA). Two groups were compared: Fixed (n = 124), where a fixed distal valgus resection angle of 7° was used; Variable (n = 87), where the resection angle was adjusted to the measured femoral mechanical anatomical (FMA) angle of the patient. FMA and mechanical femoro-tibial (MFT) angles were measured on pre-operative and post-operative hip-knee-ankle radiographs. 85% of patients in the Variable group had a post-operative MFT angle within 0° ± 3°compared to 69% in the Fixed group (P = 0.006). The use of a fixed distal femoral resection angle for all patients is not appropriate. Setting the resection to an individual patient's FMA angle can significantly improve the post-operative MFT angle.

Standardising the clinical assessment of coronal knee laxity.

Clinical laxity tests are used for assessing knee ligament injuries and for soft tissue balancing in total knee arthroplasty. This study reports the development and validation of a quantitative technique of assessing collateral knee laxity through accurate measurement of potential variables during routine clinical examination. The hypothesis was that standardisation of a clinical stress test would result in a repeatable range of laxity measurements. Non-invasive infrared tracking technology with kinematic registration of joint centres gave real-time measurement of both coronal and sagittal mechanical tibiofemoral alignment Knee flexion, moment arm and magnitude of the applied force were all measured and standardised. Three clinicians then performed six knee laxity examinations on a single volunteer using a target moment of 18 Nm. Standardised laxity measurements had small standard deviations (within 1. 1 degree) for each clinician and similar mean values between clinicians, with the valgus laxity assessment (mean of 3 degrees) being slightly more consistent than varus (means of 4 degrees or 5 degrees). The manual technique of coronal knee laxity assessment was successfully quantified and standardised, leading to a narrow range of measurements (within the accuracy of the measurement system). Minimising the subjective variables of clinical examination could improve current knowledge of soft tissue knee behaviour.

Reduction of blood loss in primary hip arthroplasty with tranexamic acid or fibrin spray.

BACKGROUND AND PURPOSE: Previous studies have shown that either fibrin spray or tranexamic acid can reduce blood loss at total hip replacement, but the 2 treatments have not been directly compared. We therefore conducted a randomized, controlled trial. PATIENTS AND METHODS: In this randomized controlled trial we compared the effect of tranexamic acid and fibrin spray on blood loss in cemented total hip arthroplasty. 66 patients were randomized to 1 of 3 parallel groups receiving (1) a 10 mg/kg bolus of tranexamic acid prior to surgery, (2) 10 mL of fibrin spray during surgery, or (3) neither. All participants except the surgeon were blinded as to treatment group until data analysis was complete. Blood loss was calculated from preoperative and postoperative hematocrit. RESULTS: Neither active treatment was found to be superior to the other in terms of overall blood loss. Losses were lower than those in the control group, when using either tranexamic acid (22% lower, p = 0.02) or fibrin spray (32% lower, p = 0.02). INTERPRETATION: We found that the use of tranexamic acid at induction, or topical fibrin spray intraoperatively, reduced blood loss compared to the control group. Blood loss was similar in the fibrin spray group and in the tranexamic acid group. ClinicalTrials.gov identifier: NCT00378872. EudraCT identifier: 2006-001299-19. Regional Ethics Committee approval: 06/S0703/55, granted June 6, 2006.

Kinetic assay for characterization of spleen tyrosine kinase activity and inhibition with recombinant kinase and crude cell lysates.

Spleen tyrosine kinase (Syk) is involved in the activation of cells implicated in allergic or autoimmune diseases and certain cancers. Therefore, Syk inhibitors may prove to be effective in treating diseases where Syk activity or expression is increased or deregulated. We developed a continuous and direct (noncoupled) fluorescence intensity assay for measuring Syk activity using purified recombinant enzyme or crude lysates generated from anti-immunoglobulin M (IgM) antibody-treated RAMOS cells. The assay is based on the chelation-enhanced fluorophore 8-hydroxy-5-(N,N-dimethylsulfonamido)-2-methylquinoline (referred to as Sox), which has been incorporated into a peptide substrate selected for robust detection of Syk activity. This homogeneous assay is simple to use, provides considerably more information, and has been adapted to a 384-well, low-volume microtiter plate format that can be used for the high-throughput identification and kinetic characterization of Syk inhibitors. The assay can be performed with a wide range of adenosine triphosphate (ATP) concentrations and, therefore, can be used to analyze ATP-competitive and ATP-noncompetitive/allosteric kinase inhibitors. Measurement of Syk activity in RAMOS crude cell lysates or immunoprecipitation (IP) capture formats may serve as a physiologically more relevant enzyme source. These Sox-based continuous and homogeneous assays provide a valuable set of tools for studying Syk signaling and for defining inhibitors that may be more effective in controlling disease.

A new landmark for measuring tibial component rotation after total knee arthroplasty.

BACKGROUND: Existing methods for assessment of total knee arthroplasty (TKA) component rotation on computed tomography (CT) scans are complex, especially in relation to the tibial component. Anecdotal evidence from our practice pointed towards a potential new landmark. The study aims were to check the prevalence of this landmark, define tibial component rotation in relation to it and demonstrate its reliability. METHODS: Two hundred and eleven CTs undertaken following TKA were reviewed for presence of the landmark. A protocol to measure tibial component rotation in relation to this landmark was developed and the rotation measured using this method and Berger's protocol. Thirty one of the 211 CT scans were measured twice by two observers. Reliability was calculated using the Intraclass Correlation Coefficient (ICC). RESULTS: The new landmark of a flat area on the lateral cortex of the tibia inferior to the tibial component was identified on all scans. Median tibial component rotation measured using our protocol was 0.0°â€¯±â€¯5.4° and -9.2°â€¯±â€¯5.5° using Berger's protocol. Intra-observer reliability with the new method was excellent (ICCs of 0.899 and 0.871) and inter-observer reliability was good (ICCs of 0.734 and 0.836). CONCLUSIONS: The new landmark had a very high prevalence and could be used to define tibial component rotation. This measurement of tibial component rotation had acceptable reliability. This landmark has potential for use in the radiological assessment of tibial component rotation following TKA. Further work is required to determine its relationship to anatomical structures and symptoms of tibial component mal-rotation.

Fulfilment of preoperative expectations and postoperative patient satisfaction after total knee replacement. A prospective analysis of 200 patients.

BACKGROUND: In total knee arthroplasty (TKA), the association between preoperative patient expectations, their postoperative fulfilment, and satisfaction is not well understood. The aim of this study was to quantify these relationships in a cohort of TKA patients with differing socio-economic backgrounds from across Scotland. METHODS: Expectations of 200 patients undergoing TKA were assessed using the Hospital for Special Surgery Knee Replacement Expectation Score. Postoperatively, expectation fulfilment was assessed at six weeks and one year. Satisfaction was measured using a five-point Likert scale. Preoperative and postoperative scores were compared across satisfaction groups. Relationships between individual and overall expectation fulfilment, satisfaction, and demographics were analysed. RESULTS: At six weeks, 30% of expectations were fulfilled, increasing to 48% at one year. Corresponding satisfaction rates were 84% and 89%. Higher fulfilment scores were associated with greater satisfaction. Fulfilment of pain and mobility expectations were most predictive of satisfaction. Expectations of kneeling, squatting, paid work and sexual function went unfulfilled. Preoperative expectations were not related to postoperative satisfaction. Males had higher postoperative fulfilment scores. CONCLUSIONS: This study showed a clear association between fulfilment of preoperative expectations and patient satisfaction following TKA. However, less than 50% of patient expectations were completely fulfilled. While higher fulfilment scores were predictive of greater satisfaction, low overall fulfilment score did not preclude satisfaction. The high correlation of pain and function expectation fulfilment with satisfaction emphasises the need to relate these as appropriate preoperative expectations, while awareness of unfulfilled expectations may allow engagement with and resolution of ongoing concerns and disappointments.