Early Outcomes of Unicompartmental Knee Arthroplasty in Patients With Preoperative Genu Recurvatum of Non-neurological Origin

BACKGROUND

This study aims to evaluate outcomes of unicompartmental knee arthroplasty (UKA) in patients with preoperative genu recurvatum.

METHODS

From patients who underwent UKA at a tertiary hospital between 2005 and 2012, the study selected 30 patients with genu recurvatum (group A) compared with a matching cohort of 60 without genu recurvatum (group B). Group A was also compared with a matched cohort of 60 patients with genu recurvatum who underwent total knee arthroplasty (group C). Functional outcomes data were prospectively collected at 6-month and 2-year follow-up.

RESULTS

Two years after UKA, group A had poorer Oxford Knee Score of 22 ± 8 compared with group B at 16 ± 3 (P < .001), and the trend is reflected in the Knee Society Score (71 ± 17 vs 87 ± 17, P < .001) and the 36 Item Short Form Health Survey Physical Component Score (47 ± 10 vs 52 ± 6, P = .014). After 2 years, group C had superior Oxford Knee Score (16 ± 2, P < .001), Knee Society Score (82 ± 14, P = .003), and 36 Item Short Form Health Survey Physical Component Score (53 ± 6, P = .005). The hyperextension angle in group A decreased from 6° ± 2° to 2° ± 4° after 2 years with an improvement of 4° ± 4° (P < .001). The hyperextension angle in group C decreased from 7° ± 2° to 1° ± 3° after 2 years with an improvement of 6° ± 3° (P < .001) with a significant difference (P = .002) in hyperextension angle correction between group A and C.

CONCLUSION

Preoperative recurvatum is a predictor of poorer outcome after UKA, and this patient population benefits from better 2-year functional outcomes after total knee arthroplasty.

Age and Preoperative Knee Society Score Are Significant Predictors of Outcomes Among Asians Following Total Knee Arthroplasty

BACKGROUND

The ability to predict patients' functional outcomes will add value to preoperative counseling. The purpose of this study was to evaluate predictors of good outcomes following total knee arthroplasty (TKA) among Asian patients.

METHODS

Registry data from 2006 to 2010 were extracted. The Oxford Knee Score (OKS) and the Short Form (SF)-36 physical component summary (PCS) were used to evaluate outcomes. A "good outcome" was defined as an improvement in scores of greater than or equal to the minimal clinically important difference (MCID) in the primary analysis. The MCID for the OKS was 5, and the MCID for the PCS was 10. For the sensitivity analyses, a "good outcome" was defined as an OKS of <30 and a PCS score of >50. Clinical variables were used to develop a multiple logistic regression model for a good outcome following total knee arthroplasty at 5 years.

RESULTS

Follow-up data were available for 3,062 patients who underwent primary TKA (mean age of 66.4 years; 79.5% female). Eighty-five percent had a good outcome on the basis of the OKS and 83%, on the basis of the SF-36 PCS. Age and preoperative Knee Society score (KSS) were found to be significant predictors. When outcomes were assessed by the MCID, lesser age and lower (worse) preoperative KSS predicted a good outcome at 5 years. When outcomes were assessed by absolute criteria (postoperative scores measured against OKS and PCS thresholds), a higher (better) preoperative KSS predicted a good outcome at 5 years. Body mass index, preoperative flexion range, SF-36 mental component summary (MCS) score, mechanical alignment, sex, education level, ethnicity, operative side, number of comorbidities, type of anesthesia, and type of implant were found not to be significant predictors.

CONCLUSIONS

The majority of Asian patients with osteoarthritis had good outcomes according to the MCID criterion and benefitted from primary TKA. On the basis of our findings, we believe that older patients with a lower (worse) preoperative KSS can be informed that they have a high likelihood of improvement but a lower likelihood of achieving as good a functional outcome as those with better scores.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Obesity and the absence of trochlear dysplasia increase the risk of revision in patellofemoral arthroplasty

PURPOSE

Proper indications and patient selection are of paramount importance in patellofemoral arthroplasty (PFA). Although factors predicting outcomes in total knee arthroplasty (TKA) have been studied, there are no such studies for modern PFA. This retrospective study reports the midterm clinical and radiological outcomes and survivorship of PFA, investigating the risk factors associated with poorer outcomes and higher revision rates.

METHODS

Fifty-one patients (51 knees) with isolated patellofemoral arthritis underwent PFA with a second-generation implant. The mean follow-up duration was 4.1 years (range, 2.2 to 6.1). The cohort was stratified into obese (body mass index (BMI)≥30 kg/m(2), n=16), overweight (BMI 25 to 29.9 kg/m(2), n=20) and control (BMI 18.5 to 24.9 kg/m(2), n=15) groups. The same cohort was stratified based on the presence (n=11) or absence (n=40) of trochlear dysplasia (TD).

RESULTS

The mean Knee Society objective and function scores, the Melbourne Knee score and the Physical Component Score of Short Form 36 improved significantly. Obesity was associated with no significant improvement in the Melbourne Knee score and the Knee Society function score (p>0.05), a higher incidence of radiographic outliers and lower patient satisfaction. There was no significant difference in outcomes between the TD and non-TD groups at two years (p>0.05), with a survivorship of 92.2%. Three revisions for progression of tibiofemoral osteoarthritis were noted in the non-TD and obese or overweight groups.

CONCLUSIONS

Patients with obesity and the absence of TD are at a potentially higher risk of revision surgery to TKA, and they should be counselled that PFA may represent a 'bridging' procedure.

LEVEL OF EVIDENCE

III.

Reducing allograft contamination and disease transmission: intraosseous temperatures of femoral head allografts during autoclaving

INTRODUCTION

The Singapore General Hospital Bone Bank, which exclusively stores femoral head allografts, relies on flash sterilisation to prevent allograft-related disease transmission and wound infection. However, intraosseous temperatures during autoclaving may be lower than required to eliminate human immunodeficiency virus, and hepatitis B and C viruses. The aim of this study is to determine the intraosseous temperatures of femoral head allografts during autoclaving and to assess the adequacy of autoclaving in preventing disease transmission.

METHODS

Six femoral heads were acquired from patients who underwent hip arthroplasty. The specimens were divided into two groups. The first group underwent flash sterilisation with a sterilisation time of 4 min, while a longer sterilisation time of 22 min was used for the second group.

RESULTS

The highest core temperature in the first group was 130°C, while the core temperatures in the second group plateaued at 133°C for all allografts. In the first group, only smaller allografts maintained temperatures sufficient for the inactivation of the clinically relevant viral pathogens. In contrast, all allografts in the second group were terminally sterilised.

CONCLUSION

There is an inverse correlation between the size of allografts and intraosseous temperatures achieved during autoclaving. Therefore, we recommend dividing large allografts into smaller pieces, in order to achieve intraosseous temperatures adequate for the elimination of transmissible pathogens during flash sterilisation. Allografts should not be terminally sterilised, as the resulting allografts will become unusable. Despite modern processing techniques, stringent donor selection remains vital in the effort to prevent allograft-related infections. Autoclaving is an economical and efficacious method of preventing allograft-related disease transmission.

Recovery in knee range of motion reaches a plateau by 12 months after total knee arthroplasty

PURPOSE

The primary aim of this study was to identify the time point at which improvements in knee range of motion reach a plateau, if any. The secondary aim of this study was to investigate the correlation between the improvements in knee range of motion and patient-reported outcomes [Oxford knee score (OKS) and SF-36]. The hypothesis is that there is a time point at which the recovery in the knee range of motion after total knee arthroplasty (TKA) plateaus.

METHOD

A prospective study of 145 patients who underwent TKA was conducted. All TKAs were performed by the same surgeon. OKS and SF-36 scores were measured preoperatively and at 6, 12, and 24 months. Range of motion was measured preoperatively and at 1, 3, 6, 12, and 24 months postoperatively.

RESULTS

This study shows that for surgeon/therapist reported range of motion, a plateau in recovery was reached at 12 months after TKA. It was also found that range of extension is significantly correlated with OKS, whereas range of flexion was not significantly correlated with OKS.

CONCLUSIONS

Knowledge of when patients fully recover after TKA will allow appropriate counseling of patients during preoperative consultation. Also, this knowledge will enable surgeons/therapists to better monitor the rehabilitation progress of TKA patients, and make adjustments to the rehabilitation protocol. In addition, our study shows that objective surgeon-/therapist-measured outcome (range of motion) has a significant correlation with subjective patient-reported outcomes (OKS). Hence, both outcome measures should be employed in the postoperative monitoring of patient progress.

LEVEL OF EVIDENCE

Prospective case series, Level IV.

Association of surgeon factors with outcome scores after total knee arthroplasty

PURPOSE

To identify preoperative factors (including surgeon factors) associated with outcome scores after total knee arthroplasty (TKA).

METHODS

Medical records of 2848 patients (3458 knees) who underwent primary TKA by 27 orthopaedic specialists were retrieved. Three specialty knee surgeons who had one-year fellowship in TKA performed 1930 TKAs, and 24 general orthopaedic surgeons performed 1528 TKAs. Four of them (including all 3 specialty knee surgeons) were ultrahigh- volume (≥ 100 TKAs a year), and 21 of them were senior consultants (≥ 5 years post residency). At 2 years, 2922 (85%) of knees had complete followup data. Oxford Knee Score, Knee Society knee and function scores, and SF-36 quality-of-life score were assessed by independent physiotherapists before and after surgery. Outcomes were compared in terms of dichotomised specialty, seniority, and surgical volume of surgeons.

RESULTS

Comparing ultra-high-volume (≥ 100 TKAs per year) specialty knee surgeons with general orthopaedic surgeons, the former achieved better outcomes in terms of the Oxford Knee Score at 6 months, Knee Society knee and function scores at 2 years, and SF-36 scores at 6 months and 2 years. Comparing lower-volume (<100 TKAs per year) specialty knee surgeons with general orthopaedic surgeons, the former still achieved better outcome and quality-of-life scores, except for SF-36 Mental Component Score at 2 years.

CONCLUSION

Specialty training and clinical research in TKA improved outcome and quality-of-life scores.

Associations of self-report physical function with knee strength and knee range-of-motion in total knee arthroplasty possible nonlinear and threshold effects

This study aims to examine, in patients before and following a total knee arthroplasty (TKA), whether knee extensor strength and knee flexion/extension range-of-motion (ROM) were nonlinearly associated with physical function. Data from 501 patients with TKA were analyzed. Knee extensor strength was assessed preoperatively and 6 months postoperatively. Knee ROM and Short Form-36 (SF-36) physical function data were collected from each patient preoperatively, and at 6 and 24 months postoperatively. Knee strength was measured by handheld dynamometry and knee ROM by goniometry. Restricted cubic spline regression was used to examine possible nonlinear associations. At all assessment points, the associations between knee measures and function were not always linear. Some of the associations revealed distinct threshold points. These findings have potential clinical and research implications.

Joint line changes and outcomes in constrained versus unconstrained total knee arthroplasty for the type II valgus knee

PURPOSE

The objective of this study was to compare the outcome of constrained and unconstrained primary total knee arthroplasty (TKA) in the management of the valgus deformity.

METHODS

This is a retrospective review of patients with type II valgus knee who underwent primary TKA from 1999 to 2011. There were fifty patients in Group 1 who underwent varus-valgus constrained TKA. They were matched with another fifty patients in Group 2 who underwent unconstrained TKA.

RESULTS

The mean joint line shift was significantly higher in Group 1 (+8 mm, SD 6 mm) than in Group 2 (+2 mm, SD 3 mm) (p = 0.03). At 2 years, there was no difference in anterior-posterior stability and mediolateral stability according to the Knee Society Score, and patients in Group 2 reported significantly better mean function score of 66.2 (SD 9.3) (mean 48, SD 7.1 in Group 1) (p = 0.002). Two patients (6 %) in Group 1 underwent revision surgery--one for a broken central peg and the other for aseptic loosening. Three patients (2 %) in Group 2 underwent revision surgery--two for global instability and one for poly wear. The estimated survivorship time was 8.3 years for constrained TKA and 12.0 for unconstrained TKA.

CONCLUSION

Constrained TKA was associated with more significant joint line changes for the management of valgus arthritic knee, when compared with unconstrained TKA.

LEVEL OF EVIDENCE

Retrospective study, Level III.

Comparison of the responsiveness of the SF-36, the Oxford Knee Score, and the Knee Society Clinical Rating System in patients undergoing total knee replacement

OBJECTIVES

To compare the responsiveness of the Knee Society (KS) Clinical Rating System, the general health status measure Short Form 36 (SF-36), and both the raw and Rasch-based scores of the condition-specific Oxford Knee Score (OKS) in patients undergoing total knee replacement (TKR) METHODS: Data were prospectively collected as part of routine care from adult patients who underwent TKR between 2001 and 2006. OKS data fit the Rasch partial credit model after removing items regarding limping and kneeling. Responsiveness was assessed using effect size (ES), standardised response mean (SRM), and relative validity (RV).

RESULTS

Among 702 patients with complete data at baseline and two follow-ups, the pain subscale of the KS (KS-P), raw-OKS, and Rasch-OKS consistently had higher levels of responsiveness than all eight SF-36 and the other KS subscales. At 6-month follow-up, Rasch-OKS had the largest ES and KS-P had the largest SRM (2.7 and 2.0, respectively). When compared to raw-OKS, the RVs of KS-P, Rasch-OKS, SF-36 bodily pain, and SF-36 physical functioning were 1.1, 0.66, 0.49, and 0.36, respectively. A similar ordering of responsiveness was observed at 24-month follow-up.

CONCLUSION

The OKS and KS-P are more responsive than most SF-36 subscales in TKR patients. Raw-OKS and Rasch-OKS have comparable responsiveness. Different responsiveness indices may give different results.

Knee extension range of motion and self-report physical function in total knee arthroplasty: mediating effects of knee extensor strength

Background

Knee extensor strength and knee extension range of motion (ROM) are important predictors of physical function in patients with a total knee arthroplasty (TKA). However, the relationship between the two knee measures remains unclear. The purpose of this study was to examine whether changes in knee extensor strength mediate the association between changes in knee extension ROM and self-report physical function.

Methods

Data from 441 patients with a TKA were collected preoperatively and 6 months postoperatively. Self-report measure of physical function was assessed by the Short Form 36 (SF-36) questionnaire. Knee extensor strength was measured by handheld dynamometry and knee extension ROM by goniometry. A bootstrapped cross product of coefficients approach was used to evaluate mediation effects.

Results

Mediation analyses, adjusted for clinicodemographic measures, revealed that the association between changes in knee extension ROM and SF-36 physical function was mediated by changes in knee extensor strength.

Conclusions

In patients with TKA, knee extensor strength mediated the influence of knee extension ROM on physical function. These results suggest that interventions to improve the range of knee extension may be useful in improving knee extensor performance.

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.

An exploratory study of response shift in health-related quality of life and utility assessment among patients with osteoarthritis undergoing total knee replacement surgery in a tertiary hospital in Singapore

OBJECTIVE

To investigate the influence of response shift (RS) on health-related quality of life (HRQOL) and utility assessment among patients undergoing total knee replacement.

METHODS

Consenting patients undergoing total knee replacement were interviewed to determine their HRQOL by using the six-dimensional health state short form, derived from SF-36, and the EuroQol five-dimensional questionnaire at baseline (pretest 1) and the six-dimensional health state short form, derived from SF-36, at 6 (pretest 2) and 18 months after surgery (post-test). RS was studied by using a "then-test" approach by contacting participants 18 months after surgery and asking them to evaluate their HRQOL at baseline (then-test 1) and at 6 (then-test 2) and 18 months after surgery. RS was calculated as the score difference between pretest and then-test scores for a given time point. Relationships between RS and external variables were explored by using univariate and multiple liner regression analyses.

RESULTS

In 74 subjects (63% response rate, median age 68 years), median (interquantile range) six-dimensional health state short form, derived from SF-36, scores for then-tests at baseline (0.48 [0.42-0.49]) and at 6 months (0.72 [0.66-0.79]) after surgery were significantly different from respective pretest scores (0.61 [0.58-0.68] at baseline, P = 0.000; 0.69 [0.63-0.72] at 6 months, P = 0.000), showing RS at both time points. RS at baseline (0.14 [0.08-0.20]) was significantly larger than that at 6 months (-0.05 [0.14 to 0.00], P = 0.000). EuroQol five-dimensional questionnaire pretest and then-test scores at baseline also differed significantly (0.69 [0.17-0.73] vs. -0.18 [-0.23 to 0.00], P = 0.000). RS at baseline was not affected by assessed demographic or medical variables. RS at 6 months was greater in subjects with more years of education (16% of variance in multiple liner regression, P < 0.01).

CONCLUSION

RS was present and impacted HRQOL and utility assessment among patients undergoing total knee replacement before and 6 months after surgery.

Computer-assisted gap balancing technique improves outcome in total knee arthroplasty, compared with conventional measured resection technique

PURPOSE

The objective of this prospective study was to compare the functional outcome of conventional measured resection technique and computer-assisted gap balancing technique in TKA.

METHODS

140 patients were randomized into two groups. The conventional measured resection technique without computer navigation was performed in Group 1 and the computer-assisted gap balancing technique in Group 2. Range of motion, clinical laxity assessment with KT-1000 arthrometer, postoperative radiological films and various functional knee scores were documented at 6 months and 2 years.

RESULTS

At 2 years, there were significantly more patients (five patients, 7%) in the Group 1 with flexion contractures of more than 5° (P = 0.05). There were significantly more outliers in the Group 1 (eight patients, 11%), who demonstrated anterior tibial translation >5 mm, than Group 2 (two patients, 3%) (P = 0.041). The total excursion at 20° was significantly higher in Group 1 at 6 months (P = 0.012) and after 2 years (P = 0.031). Group 2 was able to demonstrate significantly better limb alignment with fewer outliers (more than 3° varus/valgus) than Group 1. At 6-month follow-up, Group 2 demonstrated better outcomes in Function Score (P = 0.040) and Total Oxford Score (P = 0.031). At 2-year review, Group 2 had better outcome in the Total Oxford Score (0.030).

CONCLUSION

Computer-assisted gap balancing technique was able to achieve more precise soft tissue balance and restoration of limb alignment with better knee scores as compared to the conventional measured resection technique in total knee arthroplasty.

Health-related quality of life after total knee replacement or unicompartmental knee arthroplasty in an urban asian population

OBJECTIVE

To examine health-related quality of life (HRQoL) after total knee replacement (TKR) or unicompartmental knee arthroplasty (UKA).

METHODS

Asian adult patients undergoing either TKR or UKA in a hospital in Singapore between 2001 and 2006 were interviewed before surgery and 6 and 24 months postoperatively to obtain demographic information and HRQoL scores using the Short Form-36 Health Survey (SF-36) and the Oxford Knee Score (OKS).

RESULTS

Data were collected from 2243, 1715, and 1113 patients at baseline and at 6 and 24 months, respectively. TKR patients had a lower preoperative OKS than UKA patients and lower preoperative scores on four subscales of the SF-36 (P < 0.01). Both TKR and UKA patients' OKS and SF-36 subscale scores improved 6 months postoperatively except in the general health domain. SF-36 role physical and bodily pain scores showed the most improvement (40.9 and 33.0 points in TKR and 36.9 and 31.4 points in UKA patients, respectively). Two years after surgery, TKR patients' SF-36 scores and OKSs were not significantly different from those of UKA patients except for physical functioning scores. Multiple regression analysis adjusting for demographics showed that baseline scores were a significant predictor of the postoperative OKSs and scores on all SF-36 subscales (P < 0.01), whereas the type of surgery was not associated with the postoperative scores.

CONCLUSIONS

Both TKR and UKA patients experienced significant improvements in HRQoL, particularly in the role physical and pain domains. After controlling for potential confounding variables, the type of surgery was not a significant predictor of patients' postoperative HRQoL scores.

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.

Use of a disease-specific instrument in economic evaluations: mapping WOMAC onto the EQ-5D utility index

OBJECTIVE

To map the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) onto the EuroQol 5 Dimension (EQ-5D) utility index in patients with knee osteoarthritis (OA).

METHODS

A consecutive sample of patients (n=258) diagnosed with knee OA completed both the WOMAC and the EQ-5D. Regression models with the ordinary least squares (OLS) or the censored least absolute deviations as the estimator were used to establish the mapping function. The WOMAC was represented as explanatory variables in four ways: 1) total score; 2) domain scores (i.e., pain, stiffness, and physical function); 3) domain scores plus pair-wise interaction terms to account for possible nonlinearities; and 4) individual item scores. Goodness-of-fit criteria included the mean absolute error (the primary criterion) and the root mean squared error, and were obtained using an iterative random sampling procedure. Prediction precision was evaluated at individual patient level and at the group level.

RESULTS

The model using the OLS estimator and the WOMAC domain scores as explanatory variables had the best fit and was chosen as the preferred mapping model. The prediction error at the individual level exceeded the maximal tolerance value (i.e., the minimally important difference of the EQ-5D) in about 16% of the patients. At the group level, the width of the 95% confidence interval of prediction errors varied from 0.0176 at a sample size of 400 to 0.0359 at a sample size of 100.

CONCLUSIONS

EQ-5D scores can be predicted using WOMAC domain scores with an acceptable precision at both individual and group levels in patients with mild to moderate knee OA.

Evaluation of health outcomes in osteoarthritis patients after total knee replacement: a two-year follow-up

Objectives

To quantify the improvement in health outcomes in patients after total knee replacement (TKR).

Methods

This was a two-year non-randomized prospective observational study in knee osteoarthritis (OA) patients undergone TKR. Patients were interviewed one week before, six months after, and two years after surgery using a standardized questionnaire including the SF-36, the Oxford Knee Score (OKS), and the Knee Society Clinical Rating Scale (KSS). A generalized estimating equation (GEE) model was used to estimate the magnitudes of the changes with and without the adjustment of age, ethnicity, BMI, and years with OA.

Results

A total of 298 (at baseline), 176 (at six-months), and 111 (at two-years) eligible patients were included in the analyses. All the scores changed significantly over time, with the exception of SF-36 social functioning, vitality, and mental health. With the adjustment of covariates, the magnitude of changes in these scores was similar to those without the adjustment.

Conclusions

Both general and knee-specific physical functioning had been significantly improved after TKR, while other health domains have not been substantially improved after the surgery.

Total or partial knee replacement? Cost-utility analysis in patients with knee osteoarthritis based on a 2-year observational study

The objective of this study was to evaluate incremental cost-utility of total knee replacement (TKR) versus unicompartmental knee arthroplasty (UKA) in patients with knee osteoarthritis (OA) of the medial compartment. A 2-year non-randomised prospective observational cohort study was conducted in unicompartmental knee osteoarthritis patients scheduled for TKR (n = 431) or UKA (n = 102). Costs were identified using administrative databases and health outcomes were measured using the SF-36 and the Oxford knee score (OKS) 1 week before, 6 months after, and 2 years after surgery. The incremental cost-utility ratio (ICUR) for TKR versus UKA was calculated and its 95% confidence interval estimated using a nonparametric bootstrapping technique. Cost-effectiveness acceptability curves were constructed from different perspectives. On average, from the societal perspective, the ICUR was US $65,245 per quality-adjusted life-year (QALY). In the scenario with costs calculated from the perspective of patients, the ICUR was $60,382/QALY. This value decreased to $4,860/QALY in the scenario with costs calculated from the governmental perspective. However, the 95% confidence interval of ICURs cannot be defined because more than 5% bootstrapped samples fell into the upper left quadrant of the cost-effectiveness plane from all three perspectives. Based on the 2-year data, TKR gained more QALYs at higher costs compared to UKA. A long-term prospective study is necessary to determine cost-effectiveness of TKR and UKA.

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.

A study on indirect and intangible costs for patients with knee osteoarthritis in Singapore

OBJECTIVES

To estimate indirect costs through human capital approach and intangible costs through willingness-to-pay (WTP), and identify factors potentially affecting these costs in multiethnic Asian patients with knee osteoarthritis (OA).

METHODS

Data were collected through face-to-face interviews among knee OA patients. Human capital approach was used to estimate indirect costs by multiplying: 1) days of absence from work because of OA, with average earnings per capita per day for working patients; or 2) productivity loss with the market price of housekeeping for retirees/homemakers. A closed-ended iterative bidding contingent valuation method was used to elicit willingness-to-pay for a hypothetical cure of OA as a proxy for intangible costs. Mann-Whitney U or Kruskal-Wallis H-tests were performed in univariate analyzes, and linear regression in multivariate analyses.

RESULTS

Indirect costs per year and intangible costs were estimated at US$1008 and US$1200, accounting for 2.8% and 3.3% of annual household income, respectively. The indirect costs were significantly higher for male or working patients, while intangible costs were higher for Chinese, working patients, with higher income, or worse global well-being.

CONCLUSION

This study demonstrated that eliciting indirect costs through human capital approach and intangible costs through WTP are acceptable and feasible in Asian patients with knee OA. Besides the direct costs, the indirect and intangible costs for the OA patients could be substantial.

Computer-assisted minimally invasive total knee arthroplasty compared with standard total knee arthroplasty. A prospective, randomized study

BACKGROUND

There is little information on the feasibility of computer navigation when using a minimally invasive approach for total knee arthroplasty, during which the anatomic landmarks for registration may be obscured. The purpose of the present study was to determine the radiographic accuracy of this technique and to compare the rate of functional recovery between patients who underwent computer-assisted minimally invasive arthroplasty and those who underwent conventional total knee arthroplasty.

METHODS

One hundred and eight consecutive patients were randomized to undergo computer-assisted minimally invasive total knee arthroplasty or conventional total knee arthroplasty. Perioperative pain management was standardized. The clinical parameters, long-leg radiographs, and functional assessment scores were evaluated for six months postoperatively.

RESULTS

Patients who underwent computer-assisted minimally invasive total knee arthroplasty had a significantly longer operative time (by a mean of twenty-four minutes) and a significantly shorter inpatient stay (3.3 compared with 4.5 days) in comparison with those who underwent conventional arthroplasty (p </= 0.001). Significantly more patients in the computer-assisted minimally invasive total knee arthroplasty group were able to walk independently for more than thirty minutes at one month (p = 0.04). The percentage of patients with a coronal tibiofemoral angle within +/-3 degrees of the ideal was 92% for the computer-assisted minimally invasive total knee arthroplasty group, compared with 68% for the conventional total knee arthroplasty group (p = 0.003).

CONCLUSIONS

Although specific clinical parameters reflect an early increased rate of functional recovery in association with computer-assisted minimally invasive total knee arthroplasty within the first postoperative month, the main advantage of this technique over conventional total knee arthroplasty is improved postoperative radiographic alignment without increased short-term complications.