Patient-reported Outcome Measures of Revision Total Hip Arthroplasty for Prosthetic Joint Infection is not Inferior to Aseptic Revision Total Hip Arthroplasty

Introduction:

This study aims to investigate whether patients undergoing two-stage revision total hip arthroplasty (THA) for prosthetic joint infection (PJI) and one-stage revision THA for aseptic reasons have similar clinical outcomes and patient satisfaction during their post-operative follow-up. We hypothesise that the two-stage revision THA for PJI is associated with poorer outcomes as compared to aseptic revision THA.

Materials and Methods:

We reviewed prospectively collected data in our tertiary hospital arthroplasty registry and identified patients who underwent revision THA between 2001 and 2014, with a minimum of two years follow-up. The study group (two-stage revision THA for PJI) consists of 23 patients and the control group (one-stage revision THA for aseptic reasons) consists of 231 patients. Patient demographics, Western Ontario and McMaster Universities Arthritis Index (WOMAC), Oxford Hip Score (OHS), Short Form-36 (SF-36) scores and patient reported satisfaction were evaluated. Student’s t-test was used to compare continuous variables between the two groups. Statistical significance was defined as p <0.05.

Results:

The pre-operative demographics and clinical scores were relatively similar between the two groups of patients. At two years, patients who underwent revision THA for PJI reported a better WOMAC Pain Score and OHS as compared to aseptic revision THA. A similar proportion of patients were satisfied with their results of surgery in both groups (p=0.093).

Conclusions:

Although patients who underwent revision THA for PJI had poorer pre-operative functional scores (WOMAC function and SF-36 PF), at two years follow-up, these two groups of patients have comparable post-operative outcomes. Interestingly, patients who had revision THA for PJI reported a better clinical outcome in terms of OHS and WOMAC Pain score as compared to the aseptic group. We conclude that the revision THA for PJI is not inferior to aseptic revision THA in terms of patient satisfaction and clinical outcomes.

Manipulation under Anaesthesia for Patient Reported Stiffness after Total Knee Arthroplasty in an Asian Population

Introduction:

Stiffness after Total Knee Arthroplasty (TKA) is a complication that decreases patient satisfaction. Patients in an Asian population have potentially different requirements of knee range of motion. The authors have encountered patients who complain of subjective stiffness post TKA who do not have a severely restricting range of motion (ROM). Some patients have persistent subjective stiffness and undergone Manipulation Under Anaesthesia (MUA). We look at their functional outcomes post MUA.

Materials and Methods:

This is a retrospective study, including 48 patients from a single institution who underwent MUA for stiffness, separated into objective and subjective knee stiffness. Patients with subjective knee stiffness who underwent MUA had failed conservative management. ROM, Oxford Knee Scores (OKS), Knee Society Scores (KSS) and Short Form 36 (SF36) scores were compared at two years post MUA.

Results:

The demographics of the two patient groups were similar. The time interval between index TKA and MUA was higher in the subjective knee stiffness group. Pre-MUA OKS, KS Function Score, KSS and SF36 scores were similar in both patient subgroups. There was no significant difference in the OKS, KSS or SF36 at two year follow-up. The proportion of patients in each group who achieved the Minimum Clinically Important Difference (MCID) improvement in the scores was also similar.

Conclusions:

Patients with subjective knee stiffness can achieve similar functional outcome improvements in Oxford and Knee Society Scores with MUA at two years follow-up.

The influence of obesity on functional outcome and quality of life after total knee arthroplasty: a ten-year follow-up study

Aims

This study investigated the influence of body mass index (BMI) on patients' function and quality of life ten years after total knee arthroplasty (TKA).

Patients and Methods

A total of 126 patients who underwent unilateral TKA in 2006 were prospectively included in this retrospective study. They were categorized into two groups based on BMI: < 30 kg/m² (control) and ≥ 30 kg/m² (obese). Functional outcome was assessed using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), and Oxford Knee Score (OKS). Quality of life was assessed using the Physical (PCS) and Mental Component Scores (MCS) of the 36-Item Short-Form Health Survey.

Results

Results Patients in the obese group underwent TKA at a younger age (mean, 63.0 years, sd 8.0) compared with the control group (mean, 65.6 years, sd 7.6; p = 0.03). Preoperatively, both groups had comparable functional and quality-of-life scores. Ten years postoperatively, the control group had significantly higher OKS and MCS compared with the obese group (OKS, mean 18 (sd 5) vs mean 22 (sd 10), p = 0.03; MCS, mean 56 (sd 10) vs mean 50 (sd 11), p = 0.01). After applying multiple linear regression with the various outcomes scores as dependent variables and age, gender, and Charlson Comorbidity Index as independent variables, there was a clear association between obesity and poorer outcome in KSFS, OKS, and MCS at ten years postoperatively (p < 0.01 in both KSFS and OKS, and p = 0.03 in MCS). Both groups had a high satisfaction rate (97.8% in the control group vs 87.9% in the obese group, p = 0.11) and fulfillment of expectations at ten years (98.9% in the control group vs 100% in the obese group, p = 0.32).

Conclusion

Although both obese and non-obese patients have significant improvements in function and quality of life postoperatively, obese patients tend to have smaller improvements in the OKS and MCS ten years postoperatively. It is important to counsel patients on the importance of weight management to achieve a more sustained outcome after TKA. Cite this article: Bone Joint J 2018;100-B:579-83.

The influence of body mass index on functional outcome and quality of life after total knee arthroplasty

AIMS

This study investigated the influence of body mass index (BMI) on the post-operative fall in the level of haemoglobin (Hb), length of hospital stay (LOS), 30-day re-admission rate, functional outcome and quality of life, two years after total knee arthroplasty (TKA).

PATIENTS AND METHODS

A total of 7733 patients who underwent unilateral primary TKA between 2001 and 2010 were included. The mean age was 67 years (30 to 90). There were 1421 males and 6312 females. The patients were categorised into three groups: BMI < 25.0 kg/m(2) (normal); BMI between 25.0 and 39.9 kg/m(2) (obese); and BMI ≥ 40.0 kg/m(2) (morbidly obese).

RESULTS

Compared with the normal and obese groups, the mean LOS was longer by one day (95% confidence interval (CI) 0 to 2) in the morbidly obese group (p = 0.003 and p = 0.001 respectively). The 30-day re-admisison rate was also higher in the morbidly obese group compared to the obese group (OR 2.323, 95% CI 1.101 to 4.900, p = 0.024); and showed a higher trend compared to the normal group (OR 1.850, 95% CI 0.893 to 3.831, p = 0.100). However, the morbidly obese group had a smaller drop in post-operative Hb level by a mean of 0.5 g/dl (0.3 to 0.6) and 0.3 g/dl (0.1 to 0.5), when compared with the normal and obese groups respectively (both p < 0.001). Furthermore, the mean improvement in Oxford Knee Score (OKS) and Knee Society Knee Score (KSKS) at two years follow-up was three points (two to four) and five points (two to seven) more in the morbidly obese group than in the normal group (both p < 0.001). The mean improvement in Knee Society Function Score, and Physical and Mental Component Scores of Short Form-36 were comparable between the three BMI groups (p = 0.736, p = 0.739 and p = 0.731 respectively). The ten-year rate of survival was 98.8% (98.0 to 99.3), 98.9% (98.5 to 99.2) and 98.0% (95.8 to 100), for the normal, obese and morbidly obese groups, respectively (p = 0.703).

CONCLUSION

Although morbidly obese patients have a longer LOS and higher 30-day re-admission rate after TKA, they have a smaller drop in post-operative Hb level and larger improvement in OKS and KSKS at two years follow-up. The ten-year rate of survival of TKA was also comparable with those with a normal BMI.

TAKE HOME MESSAGE

Morbidly obese patients should not be excluded from the benefits of TKA. Cite this article: Bone Joint J 2016;98-B:780-5.

Quality of cementation in conventional versus minimally invasive total knee arthroplasty

PURPOSE

To review the immediate postoperative radiographs of 108 patients following conventional or minimally invasive total knee arthroplasty (TKA) to assess the quality of cementation in terms of cement voids and retained cement.

METHODS

Records of 20 male and 88 female consecutive patients aged 50 to 83 (mean, 67.5) years who underwent conventional TKA (n=56) or computer-assisted minimally invasive TKA (n=52) for osteoarthritis by a single senior surgeon were reviewed. Immediate postoperative radiographs were assessed by a single blinded assessor for the quality of cementation in terms of cement void and retained cement in different zones of the femoral, tibial, and patellar components along the prosthesis-bone interface using the Knee Society total knee arthroplasty roentgenographic evaluation and scoring system.

RESULTS

The 2 groups were comparable in terms of baseline demographics as well as cement void and retained cement on the femoral, tibial, and patellar components, except that in the minimally invasive group, cement void beneath the anterior flange of the femoral component was wider (0.32 vs. 0 mm, p=0.001), and retained cement in the posterior or lateral aspects of the tibial component was more common (50.0% vs. 28.6%, p=0.018).

CONCLUSION

Minimally invasive TKA resulted in a wider cement void beneath the anterior flange of the femoral component and a higher rate of retained cement around the tibial component.

Inborn Error of Metabolism (IEM) screening in Singapore by electrospray ionization-tandem mass spectrometry (ESI/MS/MS): An 8 year journey from pilot to current program

IEM screening by ESI/MS/MS was introduced in Singapore in 2006. There were two phases; a pilot study followed by implementation of the current program. The pilot study was over a 4 year period. During the pilot study, a total of 61,313 newborns were screened, and 20 cases of IEM were diagnosed (detection rate of 1:3065; positive predictive value (PPV) of 11%). Regular self-review, participation in external quality assessment and the Region 4 Genetic collaborative programs (http://www.region4genetics.org/) had led to the robust development of our current NBS MS/MS program. Overall, from July 2006 to April 2014, we screened a total of 177,267 newborns. The mean age at the time of sampling was 47.9h. Transportation of samples to the testing laboratory averaged 0.92 day. Upon receipt of sample, the NBS result was available within 1.64 days and within 3.8 days if a second tier test was required. Using absolute cut-off values in place of the initial 99th percentile reference range for the analyte markers and the introduction of two 2nd tier tests (MMA and Succinylacetone) had significantly reduced the high recall rate from an initial 1.5% during the period 2006-07 to 0.12% in 2013. The NBS MS/MS program was supported by a centralized confirmatory/diagnostic testing laboratory and a rapid response team of metabolic specialists. The detection rate was 1: 3165 (1:2727 if maternal conditions were also included). There were 23 newborns affected with organic acidemias (incidence: 1:6565), 23 with fatty acid oxidation disorders (incidence: 1:6565), and 10 with amino acidopathies (incidence 1:17,726). The performance metrics for the screening test were acceptable (sensitivity: 95.59%, specificity: 99.85%, PPV: 20%, FPR: 0.15). Participation in the NBS MS/MS program by hospitals was voluntary, and in 2013, the uptake rate was 71% of the annual births. We hope that newborn screening by MS/MS will become a standard of care for all babies in Singapore.

Evaluation of the relationship between anteroposterior translation of a posterior cruciate ligament-retaining total knee replacement and functional outcome

The success of total knee replacement (TKR) depends on optimal soft-tissue balancing, among many other factors. The objective of this study is to correlate post-operative anteroposterior (AP) translation of a posterior cruciate ligament-retaining TKR with clinical outcome at two years. In total 100 patients were divided into three groups based on their AP translation as measured by the KT-1000 arthrometer. Group 1 patients had AP translation < 5 mm, Group 2 had AP translation from 5 mm to 10 mm, and Group 3 had AP translation > 10 mm. Outcome assessment included range of movement of the knee, the presence of flexion contractures, hyperextension, knee mechanical axes and functional outcome using the Knee Society score, Oxford knee score and the Short-Form 36 questionnaire. At two years, patients in Group 2 reported significantly better Oxford knee scores than the other groups (p = 0.045). A positive correlation between range of movement and AP translation was noted, with patients in group 3 having the greatest range of movement (mean flexion: 117.9° (106° to 130°)) (p < 0.001). However, significantly more patients in Group 3 developed hyperextension > 10° (p = 0.01). In this study, the best outcome for cruciate-ligament retaining TKR was achieved in patients with an AP translation of 5 mm to 10 mm.

Single-dose periarticular steroid infiltration for pain management in total knee arthroplasty: a prospective, double-blind, randomised controlled trial

INTRODUCTION

Post total knee replacement pain control using parenteral opioids results in significant side effects like nausea and vomiting. Periarticular injections are used to control pain without these side effects. This study aimed to evaluate the safety and efficacy of periarticular steroid injection in patients undergoing total knee arthroplasty, as well as assess the patient's functional outcomes over a period of two years.

METHODS

A total of 100 patients who underwent total knee arthroplasty were randomised into two groups. The treatment group received periarticular infiltration with triamcinolone acetonide, bupivacaine and epinephrine. The control group received only bupivacaine and epinephrine. The postoperative analgesic regime was standardised for all patients. The immediate postoperative outcomes evaluated included pain score, morphine consumption, time to ambulation, straight leg raise, range of motion and duration of hospital stay. Longer-term outcomes were assessed at 1, 3, 6 and 24 months using the SF-36 questionnaire and Oxford Knee Score.

RESULTS

Patients in the treatment group had significantly lower pain scores, reduced morphine consumption and earlier discharge. They also had better range of knee motion and were able to regain muscular strength earlier. There was no increase in major complications such as infection or tendon rupture in the treatment group. There was no difference between the groups with regard to the medium-term outcomes of up to two years.

CONCLUSION

This modality of pain control is safe and efficacious for post total knee replacement pain control.

Rasch analysis of the Oxford Knee Score

OBJECTIVES

Use Rasch analysis to examine the psychometric properties of the Oxford Knee Score (OKS), particularly in respect to unidimensionality, and consistency of item functioning before and after total knee replacement and across age and gender groups.

METHODS

The 12-item OKS was administered to 1,712 patients before the surgery, and 1,322 and 855 patients were administered the instrument repeatedly at the 6-month and 2-year postoperative assessments, respectively. Data were fitted to the Rasch partial credit model with the Winsteps program. Differential item functioning (DIF) analysis was performed, and fit statistics in combination with principal components analysis of the residuals were used to test the unidimensionality assumption. The fit criteria were set at 1.5 and 2.0 for infit mean-square (MNSQ) and outfit MNSQ, respectively.

RESULTS

At baseline, item difficulty ranged from -1.86 to 1.78 logits, and person measures had a mean+/-SD of -0.01+/-0.89. Misfit items were "limping" and "night pain" in preoperative data and "limping" and "kneeling" in postoperative data. After removing items limping and kneeling and recoding item night pain, none of the items misfit at each of the time points and there was stability of item difficulty ordering across time. In the modified OKS set, five items displayed DIF by age and three by gender.

CONCLUSION

The original OKS had adequate targeting and good coverage of knee severity levels in preoperative patients. The modified 10-item OKS data fit the Rasch model and had stable item difficulty ordering over time.

Thromboembolic prophylaxis for total knee arthroplasty in Asian patients: a randomised controlled trial

PURPOSE

To compare the efficacy and safety of different modes of thromboembolic prophylaxis for elective total knee arthroplasty (TKA) in Asian patients.

METHODS

440 low-risk patients undergoing TKA were randomised into 4 equal groups: (1) no prophylaxis (control), (2) graduated compression stockings (GCS), (3) intermittent pneumatic compression (IPC), and (4) low-molecular-weight heparin (enoxaparin). Duplex ultrasonography was used as an assessment tool.

RESULTS

The deep vein thrombosis point prevalence was highest in the control group (22%), which was significantly higher than in patients receiving IPC (8%, p=0.032) or enoxaparin (6%, p=0.001). One patient each in the control and GCS groups developed a non-fatal pulmonary embolism. Patients on enoxaparin received more blood transfusions and 2 of them had major bleeding complications.

CONCLUSION

IPC is the preferred method of thromboprophylaxis for TKA in Asian patients.

Does computer-assisted surgical navigation total knee arthroplasty reduce venous thromboembolism compared with conventional total knee arthroplasty?

INTRODUCTION

The study aims to show that total knee arthroplasty using computer-assisted surgical navigation without intramedullary rodding is safer than conventional intramedullary techniques in preventing venous thromboembolism.

METHODS

30 patients were grouped into groups of 10. Groups A and B had conventional intramedullary rodding of the femur and/or tibia. Group C had no rodding of the femur and tibia using computer-assisted surgical navigation. The degree, duration and size of the embolic shower were captured by a transoesophageal echocardiography probe. The echogenic emboli were graded according to the Mayo Clinic score. Haemodynamic parameters such as pulse oximetry oxygen saturation, end-tidal carbon dioxide, heart rate and mean arterial pressure were also recorded.

RESULTS

There was a significant difference in the size of the emboli and the Mayo Clinic score when comparing the groups with intramedullary rodding and those without. There was also a significant difference in the pulse oximetry oxygen saturation and heart rate when the group without intramedullary rodding was compared with groups with rodding.

CONCLUSION

Surgical navigation total knee arthroplasty may be safer than conventional total knee replacement with intramedullary rodding in preventing venous thromboembolism.

Cross-cultural adaptation and validation of Singapore English and Chinese Versions of the Oxford Knee Score (OKS) in knee osteoarthritis patients undergoing total knee replacement

OBJECTIVE

To cross-culturally adapt and validate Singapore English and Chinese versions of the Oxford Knee Score (OKS) in patients with knee osteoarthritis (OA) undergoing total knee replacement (TKR) surgery.

METHODS

Singapore English and Chinese OKS versions were cross-culturally adapted from the source English version following standard guidelines (including cognitive debriefing), and validated by interviewing patients in English or Chinese using an identical, pretested questionnaire containing the OKS, Short Form 36, and EQ-5D. Reliability was assessed using Cronbach's alpha, dimensionality using principal component factor analysis and item-total correlations, convergent and divergent construct validity by assessing six and three a priori hypotheses, respectively.

RESULTS

The Singapore English and Chinese OKS were well accepted by patients in pilot testing. When administered to a consecutive sample of 127 English and 131 Chinese-speaking Singaporeans with knee OA (mean age 66 years, 83% female, mean duration of OA 6 years, Chinese:Malay:Indian:Others=78:7.9:11:3.1% for English version), Cronbach's alpha exceeded 0.8 and factor analysis yielded three factors for both versions. Hypothesized item-total correlations (Spearman's rho > or = 0.4) were observed for all items except limping, kneeling, and night knee pain in both versions. Convergent construct validity was supported by the presence of hypothesized moderate/strong correlations (rho=0.37-0.73) for six and five a priori hypotheses in English and Chinese versions, respectively. Divergent construct validity was supported by the presence of weak correlations (rho=0.09-0.30) for all three a priori hypotheses in both versions.

CONCLUSION

Singapore English and Chinese OKS demonstrated good patient acceptability and psychometric properties (including construct validity) among multiethnic Asian patients with knee OA undergoing TKR.

Cross-cultural adaptation and validation of Singapore English and Chinese versions of the Lequesne Algofunctional Index of knee in Asians with knee osteoarthritis in Singapore

OBJECTIVE

To cross-culturally adapt and validate Singapore English and Chinese versions of the Lequesne Algofunctional Index of knee in patients with knee osteoarthritis (OA) in Singapore.

METHODS

Singapore English and Chinese versions were cross-culturally adapted from the source English version following standard guideline (including cognitive debriefing). Patients were asked to complete an identical, pretested questionnaire containing the Lequesne index, Short Form 36 Health Survey (SF-36), and EQ-5D twice within 6 days. Reliability was assessed using Cronbach's alpha and intraclass correlation coefficients (ICC). Dimensionality was assessed by principal component factor analysis. Construct validity was tested by item-to-scale correlations and 12 and six a priori hypotheses for convergent and divergent construct validities, respectively.

RESULTS

Singapore English and Chinese Lequesne indices were well accepted by patients in pilot testing and were therefore administered to a consecutive sample of 127 English- and 131 Chinese-speaking Singaporeans with knee OA. Acceptable internal consistency was observed for activities of daily living and the global index (alpha=0.72-0.82), and the good test-retest reliability for all scales in both versions (ICC=0.66-0.94). Expected item-to-scale correlations were presented only in activities of daily living in both versions. Factor analysis yielded two factors for both versions. Convergent and divergent construct validities were supported by the presence of hypothesized correlations between the Lequesne index and SF-36 and EQ-5D scales.

CONCLUSION

Both versions of the Lequesne index demonstrated acceptable reliability and validity among multiethnic Asian patients with knee OA, which suggests that it could be used as a global index in the health-related quality of life (HRQoL) measurements in Singapore and possibly other Asian countries.

Cross-cultural adaptation and validation of Singapore English and Chinese versions of the Knee injury and Osteoarthritis Outcome Score (KOOS) in Asians with knee osteoarthritis in Singapore

OBJECTIVE

To cross-culturally adapt and validate Singapore English and Chinese versions of the Knee injury and Osteoarthritis Outcome Score (KOOS) in patients with knee osteoarthritis (OA) in Singapore.

METHODS

Singapore English and Chinese versions were cross-culturally adapted from the source English KOOS following standard guidelines (including cognitive debriefing). Patients were asked to complete identical questionnaires containing the KOOS, Short Form 36 Health Survey, and EQ-5D twice within 6 days. Reliability was assessed using Cronbach's alpha and intraclass correlation coefficients (ICC), dimensionality using item-to-domain correlations and convergent and divergent construct validity using 14 and 13 a priori hypotheses, respectively.

RESULTS

Singapore English and Chinese KOOS versions were well accepted by patients in pilot testing and were therefore administered to a consecutive sample of 127 English and 131 Chinese-speaking Singaporeans with knee OA. Cronbach's alpha exceeded 0.7 for all domains except for Chinese pain and symptoms domains. ICC exceeded 0.7 for all domains except for English sport and recreation and Chinese knee-related QoL domains. Hypothesized item-to-domain correlations (Spearman's rho>or=0.4) were observed for 38 items in English and 29 in Chinese versions. Convergent construct validity was supported by the presence of hypothesized moderate/strong correlations (rho=0.37-0.65) for 13 and 11 a priori hypotheses in the English and Chinese KOOS, respectively. Divergent construct validity was supported by the presence of weak correlations (rho=0.02-0.34) for 12 and 11 a priori hypotheses in the English and Chinese KOOS, respectively.

CONCLUSION

The Singapore English and Chinese KOOS were well accepted and demonstrated acceptable reliability and validity in Asian patients with knee OA in Singapore.

Clinical outcome of unicompartmental knee arthroplasty and influence of alignment on prosthesis survival rate

INTRODUCTION

Various factors that affect the longevity of unicompartmental knee arthroplasty (UKA) include patient activity level, habitus, competence of cruciate ligaments, postoperative alignment, implant positioning and ligament balancing. The purpose of this study was to evaluate the clinical outcome of the open standard UKA and establish the influence of radiological alignment on the survivorship of the prosthesis.

METHODS

We consecutively reviewed the results of 20 open standard UKAs performed in 17 patients between 1996 and 2000. A single implant type, the Press Fit Condylar Unicompartmental Knee System (DePuy, Leeds, UK), was used in all patients. All patients were evaluated clinically using the Knee Society Rating. Implant positioning and limb alignment were recorded in the standing long leg anteroposterior and lateral radiographs, and various angles were measured.

RESULTS

The alignment of the prosthesis was found to be good in 19 out of 20 operated knees. One knee with malalignment of prosthesis had to be revised at 23 months follow-up. There was a significant increase in Knee Society Rating of all patients, at a follow-up of 4-8 years. The Kaplan-Meier survival rate using revision to total knee arthroplasty as an endpoint was 91.7 percent.

CONCLUSION

The long-term outcome of UKA is influenced by positioning and alignment of the prosthesis. With proper patient selection and surgical technique, the outcome of UKA can be definitely improved.

Are they relevant? A critical evaluation of the international classification of functioning, disability, and health core sets for osteoarthritis from the perspective of patients with knee osteoarthritis in Singapore

OBJECTIVES

To determine the extent to which health items identified from the perspective of patients with knee osteoarthritis can be linked with the International Classification of Functioning, Disability and Health (ICF); and to evaluate critically the content validity of ICF comprehensive and brief core sets for osteoarthritis.

METHODS

Items identified from a focus group study were linked independently by two researchers based on the 10 a priori linking rules. Both percentage agreement and kappa statistics were calculated to measure interobserver agreement. Any disagreements were resolved by reaching a consensus among the researchers. The categories linked with all items were compared with the comprehensive core set, while the categories linked with those items reported as important by over 30% of subjects within each of three local ethnic groups (Chinese, Malay, and Indian) were compared with the brief core set. Both comparisons were made only at the second level of the ICF.

RESULTS

In all, 74 items were linked with 44 different ICF categories through 105 linkages with generally good interobserver agreement. The 69 items were linked with the ICF at the third or fourth levels. Both commonalities and disparities were found through comparison between the categories linked with these items and both core sets.

CONCLUSIONS

All items could be successfully linked with the ICF. The comprehensive core set showed good content validity, while the brief core set needs to be supported by more empirical evidence in various sociocultural contexts. This study specifically complemented the development and refinement of both core sets from the perspective of patients with knee osteoarthritis.

What health domains and items are important to patients with knee osteoarthritis? A focus group study in a multiethnic urban Asian population

OBJECTIVES

To determine important health-related quality of life (HRQoL) domains and items within each domain affected by knee osteoarthritis (OA), identify ethnic variations in the importance of these domains and items among three ethnic groups, and determine how identified domains and items mapped onto selected OA-specific HRQoL instruments.

METHODS

Focus groups were conducted among subjects with knee OA stratified by gender, ethnicity, and language spoken. All focus groups were audio-taped and transcribed verbatim, with subsequent translation into English for groups conducted in other languages. Data analysis was performed by combining the key elements of grounded theory and content analysis with the assistance of the qualitative software ATLAS/ti 5.0.

RESULTS

Five domains (pain, physical disability, other symptoms of OA, mental health, and social health) were identified from the 74 items reported as important by at least one subject. These domains were important for subjects from all ethnic groups with the exception of social health, which was more often important for Malay subjects. Items more commonly reported as important in the pain, physical disability, and other symptoms of OA domains were generally similar across ethnic groups. In contrast, important items in the mental and social health domains differed among ethnic groups.

CONCLUSIONS

The impact of knee OA on HRQoL is broadly similar in both Asian and Western socio-cultural contexts. Both similarities and differences in important domains and items were identified among subjects with knee OA from three major Asian ethnic groups.

Patellar resection during total knee arthroplasty: effect on bone strain and fracture risk

Patellae in small knees, or after severe patellar erosion, may be vulnerable to fracture after resection during arthroplasty. The patellar remnant may be thin, while the polyethylene component has a standard thickness. Anterior patellar bone strain was measured in cadaver knees loaded via the quadriceps, from 0 to 90 degrees flexion, with the patella intact, and after resections to 16, 13 and 11 mm thick and replacement by an 8-mm-thick polyethylene component. Strain increased significantly with knee flexion with constant 500 N quadriceps tension. Resection caused significant changes from intact values in knee flexion and extension and no significant effect at 30 degrees flexion. In flexion, bending caused the anterior surface to become more convex, with high tensile bone strains. In extension, resection caused negative anterior strains, representing bending in the opposite direction, with large tensile strains on the cut posterior surface. For normal activities, such as rising from a chair (1.8 kN quadriceps tension) the patella appears safe against fracture with a minimal resection to 16 mm thick. An eroded patella resected to 11 mm thickness may be at risk of fracture with that loading.

Minimally invasive unicondylar versus total condylar knee arthroplasty--early results of a matched-pair comparison

Fifty consecutive patients with isolated medial compartmental osteoarthritis of the knee were treated with minimally invasive unicompartmental knee arthroplasty (UKA). An equal number of patients with total knee arthroplasty (TKA) performed in the same period were selected and matched with respect to age, pre-operative range of motion and radiological grade of knee arthrosis. Both groups of patients were prospectively followed up. Comparison of the two groups at six months show that patients with minimally invasive UKA have less blood loss, quicker rehabilitation, earlier ambulation, shorter hospitalisation stay and better post-operative range-of-motion with reduced hospitalisation cost. Reflecting on a six-month follow-up and immediate post-operative events, we conclude that minimally invasive UKA is a relatively more cost effective procedure than TKA for these patients.

Respiratory syncytial virus infection induces matrix metalloproteinase-9 expression in epithelial cells

Increased gelatinolytic activity was observed in respiratory syncytial virus (RSV)-infected HEp-2 cells by using zymography. The anti-matrix metalloproteinase-9 (MMP-9) antibody specifically reduced the gelatinolytic activity suggesting that the increased gelatinolytic activity was due to the MMP-9. It was also supported by the results from immunofluorescent staining, treatment of MMP inhibitors, and RSV infection of the cell clones that were transfected with plasmids to express more MMP-9 and tissue type inhibitor of metalloproteinase-1 (TIMP-1). The gelatinolytic activity of extracellular MMP-9 in RSV-infected HEp-2 cells increased 1.5 +/- 0.2 fold compared with the control (p < 0.01). Cell surface MMP-9 expression was also clearly detected by immunofluorescent staining. Treatment with 1,10-phenanthroline (0.05 mM), ethylenediamine-tetraacetate (EDTA) (1.5 mM), and penta-O-galloyl-beta-D-glucose (PGG) (3.3 microM) inhibited RSV multiplication as well as syncytia formation. Furthermore, the average syncytia size increased when the cells expressing more MMP-9 were infected by RSV. In contrast, syncytia formation was inhibited in the cells manipulated to express TIMP-1. Thus, this study concludes that although RSV infection induces MMP-9, which can enhance the syncytia formation leading to RSV multiplication and spread it can be inhibited by MMP inhibitors.

Influence of patellar thickness on results of total knee arthroplasty: does a residual bony patellar thickness of <or=12 mm lead to poorer clinical outcome and increased complication rates?

With patellar thickness averaging 24.0 mm and 21.9 mm in Singapore men and women undergoing total knee arthroplasty, achievement of precut thickness is difficult if the recommended residual bony thickness of 15 mm is maintained. We retrospectively compared the clinical outcome of 56 patellae resurfaced <or=12 mm (mean residual thickness, 10.4 mm) with 56 patellae resurfaced >12 mm (mean residual thickness, 13.7 mm). Both groups were comparable in terms of demographic characteristics, presentation, precut patellar thickness, and operative details (P> .05). Knee scores (P= .627), extensor mechanism function (P= .625), and postoperative range of motion (P= .344) were comparable. Differences in the overall (P= .167) and patellar (P= .061) complication rates as determined by chi-square test on the SPSS 10.0 program were not significant, although there were 4 patella-related complications in group 2. Increased patella-related complications may be associated with an excessive patellar composite of the patellofemoral articulation. A residual patellar thickness of <12 mm did not appear to affect the clinical outcome in this series.

Total knee arthroplasty in diabetic patients: a study of 109 consecutive cases

The outcome of 109 consecutive total knee arthroplasties in 86 diabetic patients was studied. There were 73 women and 13 men, with a mean age of 69 years (range, 56-84 years). All the patients were followed for at least 36 months. The mean follow-up period was 42 months (range, 36-60 months). In the early postoperative period (< or =1 month), the overall wound infection rate was 7.3% (8 knees). The risk of deep joint infection was 5.5% (6 knees). Of the patients, 15% (17 knees) developed a urinary tract infection after the operation. The superficial and deep infection rates were higher when compared with a similar study in the general population. Maximum precautions should be taken for diabetic patients undergoing total knee arthroplasties.

Deep vein thrombosis after total knee replacement

INTRODUCTION

The prevalence of deep vein thrombosis after total knee replacement has been quoted to be between 46% and 84% in the Western literature. The aims of this study were to determine its prevalence in the Singapore population and to assess the need for prophylaxis against deep vein thrombosis.

MATERIALS AND METHODS

We examined data on 100 consecutive patients undergoing total knee replacement at the Adult Reconstructive Service, Department of Orthopaedic Surgery, Singapore General Hospital and assessed the possible risk factors: age, sex, weight, previous surgery, unilateral or bilateral surgery, postoperative rehabilitation, tourniquet and operating time. Functional and knee scores based on the Knee Society Clinical Rating System were also assessed. No prophylaxis was given to these patients. These patients underwent a duplex scan of both lower limbs on the seventh postoperative day. Treatment was instituted only if proximal deep vein thrombosis was detected.

RESULTS

The overall incidence of deep vein thrombosis was 14% with 64.3% of it occurring distally. Deep vein thrombosis was more common in bilateral total knee replacement (22.2%) compared to unilateral total knee replacement (13.2%). Partial thrombosis was present in 71.4% and occurred predominantly in the ipsilateral leg. There was no evidence of propagation. Only 1 patient developed pulmonary embolism and was treated successfully but there was no evidence of deep vein thrombosis on duplex scan in this patient.

CONCLUSION

There was no significant difference in the risk factors between patients who did and those who did not develop deep vein thrombosis.

Use of low molecular weight heparin for prevention of deep vein thrombosis in total knee arthroplasty--a study of its efficacy in an Asian population

INTRODUCTION

The aims of this paper were to study the incidence of deep vein thrombosis following total knee replacement in an Asian population and to evaluate the role of low molecular weight heparin for deep vein thrombosis in this setting.

MATERIALS AND METHODS

We prospectively studied two groups of 100 consecutive patients undergoing total knee replacement separately. Group 1 did not receive any low molecular weight heparin and group 2 received low molecular weight heparin, nodraparin calcium (Fraxiparine) according to body weight. The sex distribution, age group, weight, preoperative knee and function scores, and postoperative rehabilitation were similar for both groups. A single ultrasound technician performed ultrasound duplex scan of both lower limbs on the seventh postoperative day.

RESULTS

The incidence of deep vein thrombosis in group 1 was 14% (14 patients, 5 proximal vein thromboses and 9 distal vein thromboses) while in group 2, no patients developed deep vein thrombosis. There was no increased incidence, either local or systemic, of major bleeding complications with the use of low molecular weight heparin.

CONCLUSION

While the incidence of deep vein thrombosis following total knee replacement in an Asian population appears lower compared to Western populations, the use of low molecular weight heparin for thromboprophylaxis appears to further reduce the incidence without major bleeding complications.

Characterization of Borrelia burgdorferi strains isolated from Korea by 16S rDNA sequence analysis and PCR-RFLP analysis of rrf (5S)-rrl (23S) intergenic spacer amplicons

Haenam strains of Borrelia burgdorferi, which had been isolated from Ixodes granulatus and Apodemus agrarius in Haenam, Korea, were characterized by PCR-RFLP analysis of rrf (5S)-rrl (23S) intergenic spacer amplicons and by sequence analysis of the 16S rRNA gene (rDNA). The Msel and Dral restriction patterns of the 5S-23S intergenic spacer amplicons of Haenam strains differed from those of other B. burgdorferi sensu lato strains. Furthermore, in the phylogenetic tree based on the 16S rDNA sequences, Haenam strains formed a distinctive cluster, clearly separated from the other members of B. burgdorferi sensu lato. These results suggest that, apart from Borrelia garinii and Borrelia afzelii, other genotypes of B. burgdorferi sensu lato exist in Korea and the Haenam strain is a newly identified one.

Sp1 mediates constitutive and transforming growth factor beta-inducible expression of urokinase type plasminogen activator receptor gene in human monocyte-like U937 cells

Urokinase type plasminogen activator receptor (uPAR) is known to be involved in conversion of plasminogen into plasmin and its expression can be regulated by a variety of biological agents including transforming growth factor beta (TGF-beta). In the present study, we cloned the promoter region of the human uPAR (huPAR) gene (-653 to +61) and investigated the transcription regulatory mechanism of the expression of the huPAR gene upon treatment with TGF-beta in human monocyte-like U937 cells. By deletion and point mutational analysis of the huPAR gene promoter, it was found that the sequence positioned at -70 is required for both constitutive and TGF-beta-inducible expression of the huPAR gene in U937 cells. Using electrophoretic mobility shift assay, we could observe that Sp1 formed a DNA-protein complex at the -70 sequence. In addition, antisense oligonucleotide against human Sp1 blocked both constitutive and TGF-beta-inducible expression of the luciferase reporter gene driven by the huPAR gene promoter in U937 cells. These results led us to conclude that Sp1 transcription factor mediates constitutive and TGF-beta-inducible expression of the huPAR gene in U937 cells through binding to the sequence located at -70.

Results of revision total knee arthroplasty

BACKGROUND/AIM OF STUDY

The results of primary total knee arthroplasties have improved over the years but some still fail, requiring revision. Revision total knee arthroplasty is technically more difficult and has not enjoyed the same success rates as the index operation. The aim of this retrospective study was to review the results of revision total knee arthroplasties carried out at our centre. This is the first study in Singapore on revision total knee arthroplasty.

METHODS

A retrospective study where 17 patients (18 knees) had been followed up since their revision operations were clinically assessed. Based on the Knee Society Clinical Scoring System, they were assigned separate knee and function scores (each having a maximum possible 100).

RESULTS

The mean knee score was 76 (range 35-93), which rates as good. Of the 18 knees, 67% had excellent or good knee scores. By comparison, the mean function score was 56 (range 0-90) which rates as poor and 33% had excellent or good function scores.

CONCLUSION

Revision total knee arthroplasty achieves good and excellent results in spite of technical difficulties often associated with the revision operation. The difference in mean knee and function scores emphasises that many other factors such as physical strength and stamina affect function. Nevertheless, 15 patients were able to walk out of their house and around their neighbourhood for varying distances. This satisfied their expectations and the poor mean function score may reflect different expectations of patients overseas from whence this scoring system originated.

Influenza A virus infection modulates the expression of type IV collagenase in epithelial cells

We investigated the effect of influenza A/Beijing/353/89 (H3N2) virus infection on the expression of type IV collagenase in two different types of epithelial cell. Depending on the cell line infected, the viral infection caused changes in the expression of type IV collagenase. The expression of matrix metalloproteinase-9 (MMP-9; 92 kDa) but not of matrix metalloproteinase-2 (MMP-2; 72 kDa) was stimulated in Vero cells. In MDCK cells, the MMP-2 production increased with the virus infection. According to the enzymatic activity revealed with zymography, the MMP-9 promoter activity rose by a factor of over 1788 in influenza A virus-infected Vero cells but not in MDCK cells. The tissue inhibitor of metalloproteinase, TIMP-1, had increased slightly (2.3-fold) in Vero cells 48 hours after the infection, but in MDCK cells, influenza A virus had no effect on the TIMP-1 expression. In conclusion, the MMP-9 and -2 expression by influenza A virus infection are modulated at transcriptional level, depending on the epithelial cell line.

Isolated metal-backed patellar component revision following total knee arthroplasty

BACKGROUND

Twenty-two consecutive revisions for failed metal-backed patellar components following total knee arthroplasty in 17 patients were retrospectively reviewed. All had similar total condylar knee prosthesis inserted with retention of the posterior cruciate ligament and resurfacing of the patella with a metal-backed component. There were 3 male and 14 female patients.

RESULTS

The mean time to failure of the patellar component was 60 months (range 26 to 93 months). The majority of patients presented with metallic crepitus (86.4%) and knee pain (72.7%). At surgery, full thickness polyethylene wear exposing the metal-backing was present in 81.8% with surface damage of the femoral components present in 40.9%. All 22 cases underwent successful isolated patellar component revision with all polyethylene patellar components.

CONCLUSION

Resurfacing of the patella in total knee arthroplasty with metal-backed patellar components carries a significant risk of early failure and the use of these components is no longer practised at our institution.

Anterior cruciate ligament reconstruction using patellar tendon autografts--a review of results

AIM

The aim of this retrospective study was to review the results of anterior cruciate ligament reconstruction using patellar tendon autografts.

METHODS

Forty-one knees were available for evaluation at a minimum of 24 months follow-up. Objective, subjective, functional and KT-1000 arthrometric tests were performed.

RESULTS

92.7% had a negative or trace pivot shift at follow-up. None of the patients had rupture of the autografts at review. The mean post-operative single-legged hop was 81%. The KT-1000 arthrometric evaluation post-operatively revealed a mean maximum manual difference of 0.5 mm; 90.2% of these patients had a maximum manual difference of less than 4 mm. Five patients (12.2%) had a "tighter" reconstructed knee (a negative mean maximum manual difference). More than 70% of the patients in this series had good to excellent results on functional, subjective and objective evaluation scores.

CONCLUSION

Excellent motion recovery, reliable stabilisation rates, good arthrometric results and encouraging post-operative functional, subjective and objective evaluation scores can be expected in patients undergoing anterior cruciate ligament reconstruction with patellar tendon autografts.

Nonoperative treatment of metatarsophalangeal joint synovitis

The results of nonoperative treatment of metatarsophalangeal (MP) joint synovitis in 13 patients without known rheumatologic conditions (15 joints) were reviewed. Average duration of forefoot pain was 4 +/- 3 months (range 0.5-12 months), except for one patient who had pain for 30 months. The second MP joint was involved in nine cases (60%), and the third was involved in six cases (40%). Examination revealed tenderness and palpable fullness of the MP joint in all cases; painful dorsal drawer sign was present in 10 cases (67%), adjacent interdigital tenderness in six cases (40%), and hammertoe deformity in eight cases (53%). Treatment included intra-articular corticosteroid injection and rocker-sole show modification to limit MP joint dorsiflexion. At follow-up evaluation (18 +/- 9 months, range 4-26 months), the involved MP joint was asymptomatic in nine joints (60%), improved or almost asymptomatic in five joints (33%), and operated in one (7%) joint. Two of seven (29%) joints not initially associated with hammertoe developed a mild hammertoe deformity from time of diagnosis to follow-up. In conclusion, nonoperative treatment can be effective for MP joint synovitis, and the incidence of progressive hammertoe deformity in successfully treated cases is low.

Interphalangeal joint arthrodesis with oblique placement of an AO lag screw

A damaged interphalangeal (IP) joint may be treated by fusion. Arthrodesis should leave the joint at the most functional angle and give sound bony union in the shortest possible time, maintaining maximum proximal and distal joint motion. The lateral oblique placement of a single AO lag screw, proximal to distal, achieves these aims. This method gives sufficient proximal bone for screw purchase and better control of the desired angle of fusion. This technique has led to fusion in 22 of 23 joints (96%), taking an average of 8.2 weeks.

Clinical experience with automated percutaneous discectomy

This study was performed to evaluate a group of patients undergoing automated percutaneous lumbar discectomy. All patients had disc pathology at L4/L5 and L5/S1 documented on CT scan and/or MRI. The range of follow-up was between 3 months and 20 months. The average hospital stay was 2 days (range 1-3 days). A total of 21 patients underwent the procedure and 18 were available for assessment. Of these, 12 patients improved. Of the patients that did not, two subsequently underwent surgical discectomy. There was one failed procedure but no other intra- or post-operative complications. The results of the study indicate that percutaneous discectomy has a demonstrable low morbidity and can be performed under local anaesthesia. However, proper patient selection is important for successful results.