TKA Group Research Articles

Preoperative Pain and Function: Profiles of Patients Selected for Total Knee Arthroplasty

BackgroundTotal knee arthroplasty (TKA) is an effective treatment to relieve pain and restore function in patients with advanced knee osteoarthritis. TKA utilization is growing rapidly, and the appropriateness of current TKA use is of great interest. We examined patient-reported preoperative pain and function profiles to understand symptom severity at the time of TKA decision. MethodsData were from the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement. We included patients undergoing primary, unilateral TKAs between 2011 and 2014 for osteoarthritis and had data on the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain and Short-Form 36-item Physical Component Summary (PCS) score. We compared patient profiles across groupings by symptoms: (1) little pain and high function (KOOS ≥70, PCS ≥40); (2) little pain but poor function (KOOS ≥70, PCS <40); (3) high pain but high function (KOOS <70, PCS ≥40); and (4) high pain and poor function (KOOS <70, PCS <40). ResultsOf 6936 patients, 77% had high pain and poor function (group 4), 19% had high pain “or” poor function (groups 2-3), and 5% had little pain and high function before TKA (group 1). In group 1, 86% were constantly aware of their knee problem, 48% reported pain daily yet 5% experienced severe or extreme pain on stairs, and 1% pain in bed. Over half had a lot of limitations in vigorous activities. Compared with group 4, group 1 were older, less obese, more educated, and included more men and people reporting being healthy, less disabled, and happy (P < .05 for all). ConclusionMost patients undergoing TKAs had significant pain and/or poor function. Our results provide critical information given the current debate of potentially inappropriate TKA utilization in the United States.

Total Knee Arthroplasty for Posttraumatic Osteoarthritis: Is it Time for a New Classification?

BackgroundTotal knee arthroplasty (TKA) is often the best answer for end-stage, posttraumatic osteoarthritis after intra-articular and periarticular fractures about the knee. Although TKA in this setting is often considered more technically demanding, outcomes are typically worse for patients. This study examines the intraoperative differences and 30-day outcomes in posttraumatic vs primary TKA cohorts. MethodsPatients undergoing TKA were selected from the National Surgical Quality Improvement Program database from 2010 to 2013. Patients were stratified on the basis of concurrent procedures and administrative codes indicating posttraumatic diagnoses. Thirty-day complications were recorded, and multivariate analyses were performed to determine whether posttraumatic arthritis was a risk factor for poor outcomes. ResultsA total of 67,675 primary and 674 posttraumatic TKAs were identified. Posttraumatic TKA patients were on average younger and healthier than the primary TKA population. The posttraumatic TKA group had higher rates of superficial surgical site infections and bleeding requiring transfusion. History of posttraumatic knee osteoarthritis was found to be an independent risk factor for prolonged operative time, increased length of hospital stay, and 30-day hospital readmission. ConclusionWe have demonstrated increased intraoperative times, heightened transfusion requirements and surgical site infections, and higher readmission rates after conversion TKA in the posttraumatic cohort. In contrast to total hip arthroplasty, current diagnosis and reimbursement schemes do not differentiate posttraumatic patients from primary osteoarthritis groups undergoing TKA. We believe that classification reform would improve medical documentation and improve patient care.

Abstract 14779: Soleal Vein Dilatation Assessed by Ultrasonography is an Independent Predictor for Deep Vein Thrombosis After Total Hip Arthroplasty

Introduction: Deep vein thrombosis (DVT) develops after lower limb arthroplasty despite the current use of prohylaxis. Thus, accurate risk stratification is warranted to establish new prophylactic strategies. Soleal vein (SV) dilatation is often found by ultrasonography, which is performd for the screeing of the DVT. However, if the SV dilatation is usable for prediction of the DVT after the lower limb arthroplasty remains unclear. Hypothesis: We aimed to examine whether the SV dilatation assessed by ultrasonography predicts the DVT after the lower limb arthroplasty. Methods: Ultrasonography was performed pre- (mean 5 days) and postoperatively (mean 8 days) in 135 osteoarthritic patients (age 66+/-13 years, 76% women) who underwent total hip arthroplasty (THA; n = 99) or knee arthroplasty (TKA; n = 36). The patients with preoperative DVT were excluded. Presence of DVT was diagnosed by ultrasonography, which was performed from the bilateral femoral to lower limb. Increased diameter of SV (&gt;10 mm) assessed by ultrasonography was defined as the SV dilatation. Results: Thirty seven patients (27%) developed the DVT, which was proximal in one (3%) and distal in 36 (97%), after the lower limb arthroplasty. SV dilation was observed in 14 patients (10%). Of these, 11 (79%) had the postoperative DVT. Multivariate logistic regression analysis indicated that age (odds ratio [OR] 1.1, 95% CI 1.01 to 1.11, p=0.016), female (OR 4.9, 95% CI 1.18 to 19.9, p=0.028), TKA (OR 2.7, 95% CI 1.01 to 7.37, p=0.047), and SV dilatation (OR 18.8, 95% CI 4.0 to 88.8, p&lt;0.001), but not presence of comorbidities, medications, operative time, plasma D-dimer value, independently predict postoperative DVT in the whole studied patients. Subgroup analyses according to the operation site demonstrated that the SV dilation was an independent predictor of postoperative DVT in the THA group (OR 11.1, 95% CI 2.1 to 59.0, p&lt;0.01), however, not in the TKA group. Conclusions: In addtion to well-known risk factors for postoperative DVT, the SV dilatation assessed by ultrasonography is an independent predictor of the DVT after the THA. Assessment of the SV diameter by ultrasonography is useful for identfying patients with high risk for the postoprtative DVT after the THA.

Clinical improvement and satisfaction after total joint replacement: a prospective 12-month evaluation on the patients' perspective.

To determine short-term improvements, satisfaction rates and the patient acceptable symptom state (PASS) after total joint replacement (TJR) for different patient-reported outcome measures (PROMs). This prospective cohort study included 426 consecutive patients undergoing total hip (n=193) or knee arthroplasty (n=233). The following PROMs were completed before TJR, and at 3, 6 and 12months after surgery, respectively: WOMAC, Oxford Hip or Knee Score, Lower Extremity Functional Scale, University of California at Los Angeles (UCLA) activity scale and EuroQol-5 dimension (EQ-5D). Satisfaction rates and the PASS thresholds were also assessed. THA patients improved quicker and achieved higher outcome scores than TKA patients. Comorbidities according to the Sangha score were moderately correlated with all PROM values in an inverse direction at all time points (r=-0.27 to -0.47, p<0.01) in both groups. Satisfaction with the result of surgery improved over time. At 12months, more than 90% of the patients were satisfied or very satisfied with the achieved result. The THA group showed a higher proportion of very satisfied patients than the TKA group at all time points. PASS thresholds increased over time for all PROMs except for the UCLA and the EQ-5D in TKA patients. More than 90% of the patients will be satisfied 1year after TJR. THA patients recover faster than TKA patients, i.e., they achieve higher PROM values at earlier follow-up time points. Cutoff values defining a successful result in terms of the PASS could be defined for all PROMs at different time points and can serve as reference for future studies and patient-oriented follow-ups.

The risk of revision in total knee arthroplasty is not affected by previous high tibial osteotomy

Background and purpose — Previous studies have found different outcomes after revision of knee arthroplasties performed after high tibial osteotomy (HTO). We evaluated the risk of revision of total knee arthroplasty with or without previous HTO in a large registry material.Patients and methods — 31,077 primary TKAs were compared with 1,399 TKAs after HTO, using Kaplan-Meier 10-year survival percentages and adjusted Cox regression analysis.Results — The adjusted survival analyses showed similar survival in the 2 groups. The Kaplan-Meier 10-year survival was 93.8% in the primary TKA group and 92.6% in the TKA-post-HTO group. Adjusted RR was 0.97 (95% CI: 0.77–1.21; p = 0.8).Interpretation — In this registry-based study, previous high tibial osteotomy did not appear to compromise the results regarding risk of revision after total knee arthroplasty compared to primary knee arthroplasty.

Effect of donor age on the proportion of mesenchymal stem cells derived from anterior cruciate ligaments.

The characteristics of anterior cruciate ligament (ACL)-derived mesenchymal stem cells (MSCs), such as proportion and multilineage potential, can be affected by donor age. However, the qualitative and quantitative features of ACL MSCs isolated from younger and older individuals have not yet been compared directly. This study assessed the phenotypic and functional differences in ACL-MSCs isolated from younger and older donors and evaluated the correlation between ACL-MSC proportion and donor age. Torn ACL remnants were harvested from 36 patients undergoing ACL reconstruction (young: 29.67 ± 10.92 years) and 33 undergoing TKA (old: 67.96 ± 5.22 years) and the proportion of their MSCs were measured. The mean proportion of MSCs was slightly higher in older ACL samples of the TKA group than of the younger ACL reconstruction group (19.69 ± 8.57% vs. 15.33 ± 7.49%, p = 0.024), but the proportions of MSCs at passages 1 and 2 were similar. MSCs from both groups possessed comparable multilineage potentiality, as they could be differentiated into adipocytes, osteocytes, and chondrocytes at similar level. No significant correlations were observed between patient age and MSC proportions at passages 0–2 or between age and MSC proportion in both the ACL reconstruction and TKA groups. Multiple linear regression analysis found no significant predictor of MSC proportion including donor age for each passage. Microarray analysis identified several genes that were differentially regulated in ACL-MSCs from old TKA patients compared to young ACL reconstruction patients. Genes of interest encode components of the extracellular matrix (ECM) and may thus play a crucial role in modulating tissue homeostasis, remodeling, and repair in response to damage or disease. In conclusion, the proportion of freshly isolated ACL-MSC was higher in elderly TKA patients than in younger patients with ACL tears, but their phenotypic and multilineage potential were comparable.

Do surgical patellar interventions restore patellar kinematics in fixed-bearing, cruciate-retaining total knee arthroplasty?: An in vitro study

Despite different surgical patellar interventions, the decision how to treat the patella during TKA remains controversial. The purpose of this study was to quantify the effect of different reconstructive patellar interventions on patellar kinematics during TKA using optical computer navigation. We implanted ten navigated TKAs in full body specimens. During passive motion, the effect of different surgical patellar interventions on patellar kinematics was analysed. A contrarily tilt behaviour was observed in the TKA group without patellar intervention compared to the natural knee. Lateral release led to similar tilt values (P<0.05). All surgical interventions led to a 3 to 5mm medial shift of the patella (P<0.05). None of the analysed surgical patellar interventions could restore natural patellar kinematics after TKA.

A prospective study concerning the relationship between metal allergy and post-operative pain following total hip and knee arthroplasty.

A prospective study was conducted to detect whether a relationship exists between metal allergy and post-operative pain in total hip and knee arthroplasty patients. We postulated that to some extent a relationship does exist between them. Patients who had undergone total hip and knee arthroplasty surgery because of hip and knee disease were included. The exclusion criteria were patients who were treated with immunosuppressor two weeks pre-operatively, skin conditions around the patch testing site, and other uncontrollable factors. Each patient agreed to patch testing for three days before surgery. Photographic images before patch testing, two and three days after patch testing were obtained to evaluate the final incidence of metal allergy. The patch tests contained 12 metal elements; chromium, cobalt, nickel, molybdenum, titanium, aluminium, vanadium, iron, manganese, tin, zirconium, and copper. Two independent observers evaluated the images. The results were divided into a non-metal allergy group and a metal allergy group. Pre-operative and postoperative VAS score, lymphocyte transforming test, and X-rays were collected to detect the relationship between metal allergy and post-operative pain following total hip and knee arthroplasty. There were 96 patients who underwent pre-operative patch testing. The overall metal allergy rate was 51.1% (49/96) in our study. Nickel, cobalt, manganese, and tin were the most common allergic metal elements in our study. Nine inappropriate cases were excluded, and 87 patients were finally included in our study. There were 36 metal allergy and 26 non-metal allergy patients in the THA group, while 11 metal allergy and 14 non-metal allergy patients were found in the TKA group. We found no relationship existed between metal allergy and post-surgery pain in total hip and knee arthroplasty. Pain caused by metal allergy usually presents as persistent and recurrent pain. The white cell count, C-reactive protein, erythrocyte sedimentation rate and postoperative radiographs were not affected. Currently, patch testing and lymphocyte transforming tests are used for metal allergy diagnosis. We deemed that a relationship between post-surgery pain and metal allergy in total hip and knee patients may exist to some extent. Larger samples and longer follow-up time are essential for further study.

Preliminary investigation of rate of torque development deficits following total knee arthroplasty

BackgroundTo assess changes in maximal strength and rate of torque development (RTD) following TKA, and examine the relationships between these measures and physical function. MethodsThirty-five TKA patients and 23 controls completed isometric knee extensor torque testing preoperatively, 1, and 6months after surgery. Maximal strength was calculated as the peak torque during a maximal voluntary isometric contraction (MVIC) of the knee extensor muscles, peak RTD (RTDpeak) was calculated as the maximum value from the 1st derivative of the isometric knee extension torque data, RTD25% and RTD 50% were calculated as the change in force over the change in time from force onset to 25% and 50% MVIC. Physical function was measured using a timed-up-and-go (TUG) and stair climbing test (SCT). ResultsRTD was significantly lower in the TKA group, at all-time points, compared to the Controls. MVIC and RTD significantly decreased 1-month following surgery (p=0.000 for all measures). RTDpeak measures added to linear regressions with strength improved the prediction of TUG scores (p=0.006) and the SCT scores (p=0.015) 1-month post-surgery. Adding RTD50% to the regression model, following MVIC, improved predicting both TUG (p=0.033) and SCT (p=0.024). At 6-months, the addition of RTD25% to the regression model, following MVIC, improved the prediction of TUG (p=0.037) and SCT (p=0.036). ConclusionFollowing TKA, physical function is influenced by both the maximal strength and the rate of torque development of the knee extensors, and the prediction of function is improved with the addition of RTD compared to that of maximal strength alone.

Comparison of Postoperative Morbidity Between Simultaneous Bilateral and Staged Bilateral Total Knee Arthroplasties: Serological Perspective and Clinical Consequences

The present study compared simultaneous and two-staged (stages 1 and 2 with 8-month interval on average) bilateral TKAs in terms of postoperative serological status and clinical consequences. The decrease in hemoglobin over 2 weeks postoperatively was similar between groups. C-reactive protein levels and creatine phosphokinase index peaking on day 2 were significantly higher in the simultaneous group than in either staged group (P<0.05). Incidence of DVT on day 7 tended to be higher in the simultaneous group, but the difference was not significant. Considering the approximately 8-month interval and 2-month earlier functional recovery with stage 2 TKAs, 6 months were saved with the simultaneous bilateral TKA group. Collectively, simultaneous bilateral TKA is likely to offer a safe and effective procedure in appropriate clinical settings involving anti-bleeding and anti-venous thromboembolism prophylaxis.

The accuracy of component alignment in custom cutting blocks compared with conventional total knee arthroplasty instrumentation: Prospective control trial

BackgroundThe purpose of this study was to assess whether custom cutting blocks improve accuracy of component alignment compared to conventional TKA instrumentation. MethodsEighty primary TKA patients were enrolled in an open-label randomized prospective clinical trial and were divided into two groups, 40 custom cutting blocks and 40 conventional TKA instrumentations. The primary outcome was prosthetic alignment with respect to mechanical axis and epicondylar axis. Secondary outcomes included operative time, 24-hour postoperative blood loss and hemoglobin at discharged. ResultsThere were no statistical significant differences in the postoperative mechanical axis between the custom cutting blocks group and conventional TKA group, (95% vs. 87.5% within 3° of neutral mechanical alignment, p=0.192). The average rotational alignment was statistically significantly different in the custom cutting blocks group (1.0°±0.6° vs. 1.6°±1.8° external rotation from epicondylar axis, p<0.001). There were statistical significant differences in operation time between custom cutting blocks group and conventional group, skin to skin [57.5±2.3min vs. 62.1±1.5,p<0.001]. We found an improvement in group 1 compared with group 2 regarding the proportion of patients with postoperative blood loss within 24h. ConclusionsCustom cutting blocks technique was a surgical procedure which provided better accuracy in rotational alignment but no statistical differences in mechanical axis, less operative time and reduced blood loss than the conventional TKA instrumentation in the majority of patients.

Intra-operative results and radiological outcome of conventional and patient-specific surgery in total knee arthroplasty: a multicentre, randomised controlled trial

This prospective, double-blind, randomised controlled trial was designed to address the following research questions: firstly, is there a significant difference in outliers in alignment in the frontal and sagittal plane between PSG TKA and conventional TKA. Secondly, is there a significant difference in operation time, blood loss and length of hospital stay between the two techniques. We hypothesise that there will be fewer outliers with PSG TKA and that operation time, blood loss and length of hospital stay can be significantly reduced with PSG. A total of 180 patients were randomised for PSG TKA (group 1) or conventional TKA (group 2) in two centres. Patients were stratified per hospital. Alignment of the mechanical axis of the leg and flexion/extension and varus/valgus of the individual prosthesis components were measured on digital, standing, long-leg and standard lateral radiographs by two independent outcome assessors in both centres. Percentages of outliers (>3°) were determined. We compared blood loss, operation time and length of hospital stay. There was no statistically significant difference in mean mechanical axis or outliers in mechanical axis between groups. No statistically significant difference was found for the alignment of the individual components in the frontal plane nor for the percentages of outliers. There was a statistically significant difference in outliers for the femoral component in the sagittal plane, with a higher percentage of outliers in the group 1 (p = 0.017). No such significant result was found for the tibial component in that plane. All interclass correlation coefficients were good. Blood loss was 100 mL less in group 1 (p < 0.001). Operation time was 5 min shorter in group 1 (p < 0.001). Length of hospital stay was identical with a mean of 3.6 days (p = 0.657). The results in terms of obtaining a neutral mechanical axis and a correct position of the prosthesis components did not differ between groups. A small reduction in operation time and blood loss was found with the PSG system. Future research should especially focus on cost-effectiveness analysis and functional outcome of PSG TKA. I.

Trabecular Metal in Total Knee Arthroplasty Associated with Higher Knee Scores: A Randomized Controlled Trial

Porous tantalum is an option of cementless fixation for TKA, but there is no randomized comparison with a cemented implant in a mid-term followup. We asked whether a tibial component fixed by a porous tantalum system might achieve (1) better clinical outcome as reflected by the Knee Society Score (KSS) and WOMAC Osteoarthritis Index, (2) fewer complications and reoperations, and (3) improved radiographic results with respect to aseptic loosening compared with a conventional cemented implant. We randomized 145 patients into two groups, either a porous tantalum cementless tibial component group (Group 1) or cemented conventional tibial component in posterior cruciate retaining TKA group (Group 2). Patients were evaluated preoperatively and 15 days, 6 months, and 5 years after surgery, using the KSS and the WOMAC index. Complications, reoperations, and radiographic failures were tallied. At 5-year followup the KSS mean was 90.4 (range, 68-100; 95% CI, ± 1.6) for Group 1, and 86.5 (range, 56-99; 95% CI, ± 2.4) for Group 2. The effect size, at 95% CI for the difference between means, was 3.88 ± 2.87. The WOMAC mean was 15.1 (range, 0-51; 95% CI, ± 2.6) for the Group 1, and 19.1 (range, 4-61; 95% CI, ± 2.9) for Group 2. The effect size for WOMAC was -4.0 ± 3.9. There were no differences in the frequency of complications or in aseptic loosening between the two groups. Our data suggest there are small differences between the uncemented porous tantalum tibial component and the conventional cemented tibial component. It currently is undetermined whether the differences outweigh the cost of the implant and the results of their long-term performance.

A nested case–control analysis of self-reported physical functioning after total knee replacement surgery in the 45 and Up Study Cohort

ObjectivesThe rate of total knee arthroplasty surgery (TKA) is rising in Australia despite varying impacts of TKA on physical function (PF) in population-based studies. There are potentially modifiable risk factors...

Beneficial effects of a brace for patellofemoral OA: results of a randomised trial

did not. Methods: 50 patients with moderate medial compartment knee OA underwent gait analysis at baseline. Ground reaction forces (sampled at 1000 Hz) and segment motions (sampled at 100 Hz) were recorded during self-selected walking. Three-dimensional knee angles and moments were calculated using inverse dynamics. All waveforms were time-normalized to percent of gait cycle, and moment waveforms were amplitude-normalized to body mass. Amplitude and temporal waveform characteristics were determined using Principal Component Analysis (PCA) for each waveform separately (6 in total). During follow up phone interviews 5-8 years later, 25 patients reported undergoing TKA surgery. Unpaired Student's t-tests were used to test for differences in all baseline demographic and waveform characteristics (PC scores) between the group that had TKA and the group that did not (a1⁄40.05). Results: There were no between-group differences in age (59 years in TKA group vs. 57 years in no-TKA group), mass (93.5 kg vs. 93.8 kg), body mass index (30.6 kg/m2 vs. 30.8 kg/m2), and gait speed (1.23 m/s vs. 1.27 m/s), with similar radiographic disease severity (KellgrenLawrence score) distribution at baseline. The mean time between baseline and follow up was 7.8 yrs for each group. The group that progressed to TKA had a significantly higher overall magnitude of the KAM (Fig 1, PC1, p < 0.05), less of a difference between the first peak KAM and the mid-stance KAM (Fig 1, PC2, p < 0.05), more tibial external rotation during mid-stance (PC4, p<0.05), and a trend toward reduced early stance knee flexion and late stance knee extension moments (PC2, p1⁄40.073) than the no-TKA group at baseline. Conclusions: The KAM findings suggest that the group that went on to TKA had higher overall medial compartment loading throughout the gait cycle at baseline (PC1), and a reduced ability to unload the medial compartment during mid-stance (PC2). These results support a cumulative rather than an impulse loading mechanism for progression. Furthermore, increased tibial external rotation (PC4) and a trend toward altered sagittal plane moment characteristics (PC2) were found in those that progressed. Together these findings indicate that dynamic frontal, transverse, and sagittal plane mechanical features are related to knee OA progression and should be considered in future prediction models of progression.

What Are the Causes of Revision Total Knee Arthroplasty in Japan?

There is limited information regarding the cause of revision TKA in Asia, especially Japan. Owing to differences in patient backgrounds and lifestyles, the modes of TKA failures in Asia may differ from those in Western countries. We therefore determined (1) causes of revision TKA in a cohort of Japanese patients with revision TKA and (2) whether patient demographic features and underlying diagnosis of primary TKA are associated with the causes of revision TKA. We assessed all revision TKA procedures performed at five major centers in Hokkaido from 2006 to 2011 for the causes of failures. Demographic data and underlying diagnosis for index primary TKA of the revision cases were compared to those of randomly selected primary TKAs during the same period. One hundred forty revision TKAs and 4047 primary TKAs were performed at the five centers, indicating a revision burden of 3.3%. The most common cause of revision TKA was mechanical loosening (40%) followed by infection (24%), wear/osteolysis (9%), instability (9%), implant failure (6%), periprosthetic fracture (4%), and other reasons (8%). The mean age of patients with periprosthetic fracture was older (77 versus 72 years) and the male proportion in patients with infection was higher (33% versus 19%) than those of patients in the primary TKA group. There was no difference in BMI between primary TKAs and any type of revision TKA except other causes. The revision burden at the five referral centers in Hokkaido was 3.3%, and the most common cause of revision TKA was mechanical loosening followed by infection. Demographic data such as age and sex might be associated with particular causes of revision TKA.

Influence of bilateral sequential total knee arthroplasty on functional recovery

Background:Main concerns of patients undergoing bilateral surgery is the quantum of pain and the progress of functional recovery. We studied functional recovery in terms of pain, range of motion (ROM), SF12, WOMAC scores and a unique TUG (timed up and go) test for patients undergoing unilateral total knee arthroplasty (U/L-TKA) and sequential bilateral total knee arthroplasty (B/L-TKA).Materials and Methods:Three groups of 77 consecutive patients (91 knees) were retrospectively compared. They were B/L TKA group (28 knees: 14 patients), Unilateral TKA group with contralateral knee nonoperated i.e., U/L-TKA group (42 knees) and Unilateral TKA with contralateral TKA already done i.e., U/L + C/L TKA group (21 knees). Patients were assessed preoperatively and on postoperative days 3, 5, 14, 42, 90 and 1 year.Results:The WOMAC score was statistically better preoperatively in the U/L + C/L TKA group, and SF12 MCS score was statistically better preoperatively in the B/L-TKA group. The TUG test time in the B/L-TKA group was statistically longer on days 3 and 5 as compared to other groups and became comparable by day 14. The TUG score became better than the preoperative value by day 42 in the B/L-TKA group, which took 90 days in other groups.Conclusion:The early functional recovery of bilateral TKA patient lags behind that of unilateral TKA patient for the first 5 days, becomes equal by the 14th day and remains equal till 1 year after surgery. Bilateral TKA patients regain their preoperative functional status by 6 weeks against 3 months for unilateral TKA. The operative status of the contralateral knee makes no difference to early functional recovery after unilateral TKA. With bilateral TKA, there is no difference in pain and ROM parameters.

Thrombosis Incidence in Unilateral vs. Simultaneous Bilateral Total Knee Arthroplasty with Compression Device Prophylaxis

This study compares the incidence of venous thromboembolic event (VTE) in 55 patients (110 knees) undergoing simultaneous bilateral TKA with 287 patients (287 knees) undergoing unilateral TKA using a mobile compression device as monotherapy prophylaxis in both groups. All patients were clinically evaluated 3months after surgery with symptomatic confirmed VTE as an endpoint. Deep venous thrombosis (DVT) was documented by duplex ultrasound and pulmonary embolism (PE) was documented by spiral CT. The simultaneous bilateral TKA group had 6 VTEs (10.9%) with 2 PEs (3.6%). The unilateral TKA group had 9 VTEs (3.1%), and 0 PE. Patients undergoing simultaneous bilateral TKA yielded more than twice the rate of VTE compared with patients undergoing unilateral TKA using a mobile compression device as sole thromboprophylactic modality.

A performance based patient outcome score for active patients following total knee arthroplasty

The aim of this study was to develop and validate a user friendly performance based knee outcome score for use in active patients undergoing TKA surgery. We prospectively studied a cohort of 50 subjects without any knee symptoms, and 50 patients who underwent TKA for osteoarthritis (OA). The patients were assessed pre- and postoperatively. SF-36 and WOMAC were concurrently administered for comparison. Patients completed seven physical tasks of the finalised outcome instrument which were objectively assessed and scored. The mean functional score was 31.7 in the normal subjects. The mean functional score improved postoperatively from 10.0 to 17.7 (P < 0.001) in the TKA group. Our results confirm that the performance based score has a high test-retest reliability (intra-class correlation coefficient (ICC) of 0.89), internal consistency (Cronbach's alpha 0.84) and construct validity showing expected correlations with relevant components of the WOMAC and SF-36 scores. The responsiveness as measured by the effect size compared favourably with the same relevant components of the SF-36 and WOMAC. Our performance based knee function score is a reliable dimension specific tool to detect change in musculoskeletal function after TKA. It complements existing self-reported outcome tools in facilitating a comprehensive assessment of patients following TKA.

Femoral Lateral Bowing and Varus Condylar Orientation Are Prevalent and Affect Axial Alignment of TKA in Koreans

Coronal alignment is considered key to the function and longevity of a TKA. However, most studies do not consider femoral and tibial anatomical features such as lateral femoral bowing and the effects of these features and subsequent alignment on function after TKA are unclear. We therefore determined (1) the prevalence of lateral femoral bowing, varus femoral condylar orientation, and severe tibia plateau inclination in female Koreans undergoing TKA; (2) whether postoperative alignments are affected by these anatomical features and improved by the use of navigation; and (3) whether postoperative coronal alignments are associated with function. We measured alignment in 367 knees that underwent TKA and 60 sex- and age-matched normal knees (control group). We determined patterns and degrees of femoral bowing angle, femoral condylar orientation, and tibial plateau inclination on preoperative full-limb radiographs. Postoperatively, coronal alignment of limbs and of femoral and tibial components was measured. We compared American Knee Society scores, WOMAC scores, and SF-36 scores in aligned knees and outliers (beyond ± 3° or ± 2°) at 1 year. The prevalence of lateral femoral bowing was 88% in the TKA group and 77% in the control group. Mean femoral condylar orientation angle was varus 2.6° in the TKA group and valgus 1.1° in the control group, and mean tibial plateau inclination was varus 8.3° in the TKA group and varus 5.4° in the control group. Femoral lateral bowing and varus femoral condylar orientation were associated with postoperative alignments. Several clinical outcome scales were inferior in the outliers in mechanical tibiofemoral angle, anatomical tibiofemoral angle, and tibial coronal alignment but not in femoral coronal alignment outliers. Lateral femoral bowing, varus condylar orientation, and severe varus inclination of the tibia plateau should be considered when performing TKA in Korean patients or patients with otherwise similar anatomical features.