Improved clinical outcomes after high-flexion total knee arthroplasty: a 5-year follow-up study

Is high flexion total knee arthroplasty a rewarding procedure? An updated meta-analysis of prospective randomized controlled trials

INTRODUCTION

The aim of this study is to provide an updated meta-analysis comparing the benefits and clinical outcomes between high flexion (HF)-TKA and standard (S)-TKA.

MATERIALS AND METHODS

A detailed database analysis was carried out using Web of Science, PubMed, EMBASE, Cochrane Library, MEDLINE and Clinicaltrial.gov, to identify eligible studies. The meta-analysis and sensitivity analysis were performed using Review Manager 5.3 software and STATA 12.0.

RESULTS

Twenty-two randomized control trials (RCTs), including 2841 patients and 4268 knees, were eligible for the meta-analysis. The pooled results of subgroup analysis reveal that there was significant difference between HF-TKA and S-TKA in each subgroup in terms of postoperative ROM, with a higher degree of knee flexion for HF-TKA than S-TKA. However, no statistical difference was identified between HF-TKA and S-TKA in other clinical outcomes including various functional scores and complications.

CONCLUSIONS

On the basis of this meta-analysis, we can recommended HF-TKA as an alternative choice to S-TKA for patients requiring higher knee flexion in their daily activities.

Subvastus Exposure Compared to Parapatellar Approach in Navigated Sequential Bilateral Total Knee Arthroplasty (SBTKA): A Prospective Randomized Study

Subvastus approach preserves the quadriceps mechanism and may lead to improved early functional outcomes as compared with a parapatellar approach in primary knee arthroplasty. We performed a prospective randomized study to test the hypothesis if subvastus approach improves patient- and physician-reported outcomes in navigated sequential bilateral knee arthroplasty when compared with the standard parapatellar approach. A total of 93 patients were allotted in each group after power analysis and randomization done by computer-generated sequence: group S by subvastus approach and control group P by parapatellar approach. The patient's ability to walk without an aid, range of motion, blood loss, tourniquet time, complications, Knee Society Score (KSS), Knee Society Functional Score (KSFS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), High Flexion Knee Score (HFKS), and visual analog scale (VAS) for pain were recorded preoperatively and postoperatively at 2 and 6 weeks and 3, 6, and 12 months. Final follow-up was done at 2 years. There was no statistical difference in the patient's ability to achieve a straight leg raise (p = 0.88), walk without an aid (p = 0.25), leaving pain medication (p = 0.48), and mean duration of hospital stay (p = 0.58) between both groups. There was no difference in KSS, FS, KOOS, WOMAC, HFKS, and VAS at 2 weeks and later follow-ups. There was no significant difference in range of motion or lateral retinacular release in both groups. Blood loss was significantly less in group S (p < 0.05), but there was a higher rate of proximal wound dehiscence and delayed healing in subvastus group (p = 0.03). Subvastus approach does not improve patient- and physician-reported outcome measures except blood loss in computer-navigated sequential bilateral knee arthroplasty and has an increased incidence of wound healing problems. The Level of evidence for the study is I.

Lower Satisfaction After Adult Spinal Deformity Surgery in Japan Than in the United States Despite Similar SRS-22 Pain and Function Scores: A Propensity-Score Matched Analysis

STUDY DESIGN

A multicenter retrospective case series.

OBJECTIVE

The purpose of this study was to compare the clinical outcomes of a surgical treatment for adult spinal deformity (ASD) in the United States (US) with those in Japan (JP) in a matched cohort.

SUMMARY OF BACKGROUND DATA

Surgical outcomes of thoracic-lumbar-sacral (TLS) spinal fusions in adult spinal deformity ASD patients who live in Asian countries are poorly understood.

METHODS

A total of 300 surgically treated ASDs of age more than 50 years with the lowest instrumented vertebra at the pelvis and a minimum follow-up of 2 years (2y) were consecutively included. Patients were propensity-score matched for age, sex, levels fused, and 2y postop sagittal spinal alignment. Demographic, surgical, and radiographic parameters were compared between the US and JP groups.

RESULTS

A total of 186 patients were matched by propensity score and were almost identical within these parameters: age (US vs. JP: 66 ± 8 vs. 65 ± 7 yr), sex (females: 90% vs. 89%), levels fused (10 ± 3 vs. 10 ± 2), 2y C7 sagittal vertical axis (C7SVA) (5 ± 5 vs. 5 ± 4 cm), 2y Pelvic incidence minus lumbar lordosis (9 ± 15° vs. 9 ± 15°), and 2y pelvic tilt (PT) (25 ± 10° vs. 24 ± 10°). Oswestry Disability Index (ODI) scores and Scoliosis Research Society patient questionnaire ((SRS-22) function and pain scores were similar at 2y between the US and JP groups (ODI: 27 ± 19% vs. 28 ± 14%, P = 0.72; SRS-22 function: 3.6 ± 0.9 vs. 3.6 ± 0.7, P = 0.54; SRS-22 pain: 3.6 ± 1.0 vs. 3.8 ± 0.8, P = 0.11). However, significantly lower satisfaction was observed in JP than in the US (SRS-22 satisfaction: 4.3 ± 0.9 vs. 4.0 ± 0.8, P < 0.01).

CONCLUSION

Surgical treatment for ASD was similarly effective in patients in the US and in JP. However, satisfaction scores were lower in JP compared with the US. Differences in lifestyle and cultural expectations may impact patient satisfaction following ASD surgery.

LEVEL OF EVIDENCE

3.

Temporal patterns of commonly used clinical outcome scales during a 5-year period after total knee arthroplasty

Background

It is not established beyond doubt whether improvements in functional outcome after total knee arthroplasty (TKA) are maintained in the long term. We therefore investigated the temporal patterns of functional outcome [using range of motion (ROM), American Knee Society (AKS) score, Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, and 36-Item Short Form Health Survey (SF-36) score] over a 5-year period after uncomplicated TKA, and whether these patterns differed by implant type and patient age.

Materials and methods

This prospective study evaluated 138 patients who underwent unilateral TKA with either a mobile-bearing (MB) or fixed-bearing (FB) posterior-stabilized prosthesis. An independent investigator evaluated the functional outcome at five time points: preoperatively and at 6-month, 1-year, 2-year, and 5-year follow-up. Differences in functional outcomes between adjacent time points were evaluated by mixed-effect model repeat measurement (MMRM).

Results

The different functional outcome scores showed improvement till 6 months–2 years, followed by a variable decline. In patients aged ≥ 68 years with an MB implant, most of the functional outcome scores declined between 2 and 5 years after variable initial improvement till 6 months–2 years, whereas the parameters plateaued after 2 years in those aged < 68 years and in older patients with an FB implant.

Conclusions

A decline in function and pain relief occurs 2 years after TKA. This decline is more evident in older patients with an MB prosthesis. Based on these findings, we believe that use of MB implants in older patients (≥ 68 years) requires further investigation.

Level of evidence

Level 3.

Patient Dissatisfaction Following Total Knee Arthroplasty: A Systematic Review of the Literature

BACKGROUND

Dissatisfaction following total knee arthroplasty (TKA) is common. Approximately 20% of patients report dissatisfaction following primary TKA. This systematic literature review explores key factors affecting patient dissatisfaction following TKA.

METHODS

Six literature databases published between 2005 and 1 January 2016 were searched using 3 key search phrases. Papers were included if the study investigated patient dissatisfaction in primary unilateral or bilateral TKA. Information from each article was categorized to the domains of socioeconomic, preoperative, intraoperative, and postoperative factors affecting patient dissatisfaction.

RESULTS

This review found that patient dissatisfaction pertains to several key factors. Patient expectations prior to surgery, the degree of improvement in knee function, and pain relief following surgery were commonly cited in the literature. Fewer associations were found in the socioeconomic and surgical domains.

CONCLUSION

Identifying who may be dissatisfied after their TKA is mystifying; however, we note several strategies that target factors whereby an association exists. Further research is needed to better quantify dissatisfaction, so that the causal links underpinning dissatisfaction can be more fully appreciated and strategies employed to target them.

Impact of total knee replacement practice: cost effectiveness analysis of data from the Osteoarthritis Initiative

Objectives To evaluate the impact of total knee replacement on quality of life in people with knee osteoarthritis and to estimate associated differences in lifetime costs and quality adjusted life years (QALYs) according to use by level of symptoms.Design Marginal structural modeling and cost effectiveness analysis based on lifetime predictions for total knee replacement and death from population based cohort data.Setting Data from two studies-Osteoarthritis Initiative (OAI) and the Multicenter Osteoarthritis Study (MOST)-within the US health system.Participants 4498 participants with or at high risk for knee osteoarthritis aged 45-79 from the OAI with no previous knee replacement (confirmed by baseline radiography) followed up for nine years. Validation cohort comprised 2907 patients from MOST with two year follow-up.Intervention Scenarios ranging from current practice, defined as total knee replacement practice as performed in the OAI (with procedural rates estimated by a prediction model), to practice limited to patients with severe symptoms to no surgery.Main outcome measures Generic (SF-12) and osteoarthritis specific quality of life measured over 96 months, model based QALYs, costs, and incremental cost effectiveness ratios over a lifetime horizon.Results In the OAI, total knee replacement showed improvements in quality of life with small absolute changes when averaged across levels of confounding variables: 1.70 (95% uncertainty interval 0.26 to 3.57) for SF-12 physical component summary (PCS); -10.69 (-13.39 to -8.01) for Western Ontario and McMaster Universities arthritis index (WOMAC); and 9.16 (6.35 to 12.49) for knee injury and osteoarthritis outcome score (KOOS) quality of life subscale. These improvements became larger with decreasing functional status at baseline. Provision of total knee replacement to patients with SF-12 PCS scores <35 was the optimal scenario given a cost effectiveness threshold of $200 000/QALY, with cost savings of $6974 ($5789 to $8269) and a minimal loss of 0.008 (-0.056 to 0.043) QALYs compared with current practice. These findings were reproduced among patients with knee osteoarthritis from the MOST cohort and were robust against various scenarios including increased rates of total knee replacement and mortality and inclusion of non-healthcare costs but were sensitive to increased deterioration in quality of life without surgery. In a threshold analysis, total knee replacement would become cost effective in patients with SF-12 PCS scores ≤40 if the associated hospital admission costs fell below $14 000 given a cost effectiveness threshold of $200 000/QALY.Conclusion Current practice of total knee replacement as performed in a recent US cohort of patients with knee osteoarthritis had minimal effects on quality of life and QALYs at the group level. If the procedure were restricted to more severely affected patients, its effectiveness would rise, with practice becoming economically more attractive than its current use.

Is High-Flexion Total Knee Arthroplasty a Valid Concept? Bilateral Comparison With Standard Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to determine whether the high-flexion total knee prosthesis significantly improves knee flexion in vivo.

METHODS

Forty-four patients undergoing same-day bilateral total knee arthroplasty for primary osteoarthritis of both knees were randomized to receive a standard posterior-stabilized knee prosthesis (P.F.C. Sigma; DePuy Johnson & Johnson, Warsaw, IN) in one knee and a high-flexion concept posterior-stabilized knee prosthesis (LOSPA; Corentec, Inc, Seoul, Korea) in the other knee and were followed up for 2 years postoperatively.

RESULTS

The mean postoperative range of motion was 128.8° (range, 100°-144°) in the LOSPA group and 128.5° (range, 100°-142°) in the P.F.C. Sigma group (P = .744). There were no significant differences in the postoperative mean Knee Society score and Western Ontario and McMaster Universities Osteoarthritis Index score between the LOSPA and P.F.C. Sigma groups (P = .839 and P = .972, respectively).

CONCLUSION

Despite theoretical range of motion advantages of high-flexion prosthesis, there were no group differences with regard to range of motion, clinical outcomes, and the incidence of radiolucent lines at final follow-up assessment.

Performing high flexion activities does not seem to be crucial in developing early femoral component loosening after high-flexion TKA

Background

It is still unclear whether high flexion (HF) activities correlated with the early loosening of the femoral component and whether HF activities are possible. We investigated what is the capability for performing various HF activities, and whether high flexion activities increase the chance of aseptic loosening after HF-TKA.

Methods

We retrospectively analysed 260 patients who underwent HF-TKA using the NexGen LPS Flex between 2001 and 2009. The mean follow-up was 6.7 years (range, 5–13). We evaluated range of motion, Knee Society scores, WOMAC, and serial radiographs for aseptic loosening. Responses to questions on individual HF activities were recorded on 5-point Likert scales based on difficulty (0–4). Patients were divided two groups based on their responses to squatting and kneeling, which were important weight-bearing HF activities in Asian population (HF group vs. non-HF group) for comparisons of aseptic loosening and clinical outcomes.

Results

More than 80 % of patients positively responded for various HF activities. The capability of HF activities showed that cross-legged sitting, squatting, and kneeling were 97.7, 51.1 and 52.7 % at the latest follow-up, respectively. Aseptic loosening was identified in two tibial components (0.8 %) but none in femoral components in non-HF group. There was no significant difference of aseptic loosening based on HF activities (0.8% vs. 0%, p = 0.063).

Conclusions

The results of this study suggest that HF activities do not seem to be associated with aseptic loosening of femoral component after HF-TKA.

Clinical outcomes after high-flex versus conventional total knee arthroplasty

PURPOSE

To compare clinical outcomes after high-flex versus conventional total knee arthroplasty (TKA).

METHODS

A systematic review and meta-regression were performed to compare post-operative outcomes between the two types of prostheses. Relevant randomized controlled trials were identified from MEDLINE and Scopus up to November, 2014.

RESULTS

Fourteen of 369 studies were eligible; 14, 7, 6, 5, 3, 12 and 7 studies were included in the pooling of maximum knee flexion, Knee Society Knee Score (KS), Knee Society Function Score (FS), Hospital for Special Surgery score (HSS), short-form (SF) physical activity score, post-operative complications (DVT, fractures, infection) and revision TKA, respectively. The high-flex TKA had 1.97° [95% confidence interval (CI) 0.37, 3.57], -0.86 (95% CI -1.65, 0.07) and -1.34 (-2.57, -0.11) higher mean maximum knee flexion, KS and FS when compared to conventional TKA. However, there were non-significant differences in HSS, SF-36 (physical), complications and revision TKA.

CONCLUSION

This study suggests that there are improvements in post-operative knee range of motion and knee scores in high-flex TKA implants when compared to conventional TKA implants; however, the difference was very small and therefore might not have any clinical impact. Therefore, conventional TKA can be used as a substitute. However, cost-effective analysis should be performed to make appropriate selections in the future. There are no statistically significant differences in terms of HSS, quality of life, complications and revisions between the groups.

LEVEL OF EVIDENCE

I.

No Superiority of High-Flexion vs Standard Total Knee Arthroplasty: An Update Meta-Analysis of Randomized Controlled Trials

This meta-analysis was performed using a Cochrane systematic review approach to examine published data with an aim to clarify whether standard or high flexion prostheses increase the range of knee motion and clinical outcomes. 1778 patients from 17 randomized controlled trials were identified. No significant differences in the range of motion, weight-bearing flexion and hip functions scores were found between treatment groups. We also found no significant differences in complications with regard to revision, component loosening, deep infection, anterior knee pain, stiffness, post-operative bone fracture and post-operative patella clunk syndrome, but the high flexion prostheses group had a higher incidence of deep venous thrombosis. The results do not support the proposition that high flexion knee prostheses provide substantial clinical advantages over standard knee prostheses.

Patients achieved greater range of movement when using high-flexion implants

PURPOSE

NexGen Legacy Posterior Stabilized high-flexion prostheses (LPS-Flex) have been popularized as an alternative to NexGen standard prostheses (LPS) in total knee arthroplasty (TKA). Advocates of this new generation prosthesis suggest improved postoperative knee flexion. The purpose of this study was to summarize the best evidence for comparing the range of motion (ROM) and functional outcomes of LPS-Flex prostheses and LPS in TKA.

METHODS

Electronic databases were systematically searched to identify relevant randomized controlled trials (RCTs). The last date for our research was July 2014. Our search strategy was followed the requirements of the Cochrane Library Handbook. The methodological quality was assessed, and the data were extracted independently by two authors.

RESULTS

Nine studies that included 978 knees met our inclusion criteria for review. The results showed that there was larger postoperative ROM (1.62, 95% CI 0.52-2.72) in the LPS-Flex group than in the LPS group. There was not a statistically significant difference in the clinical functional scores and complications between the LPS-Flex group and the LPS group in TKA. The pooled mean differences were as follows: total KSS, -0.64 (95% CI -1.41 to 0.13); functional KSS, -0.53 (95% CI -1.51 to 0.45); HSS, 0.23 (95% CI -0.87 to 1.33); complications, 0.49 (95% CI 0.20-1.24); and radiolucent lines, 1.56 (95% CI 0.68-3.55).

CONCLUSIONS

The preliminary results indicate that the NexGen LPS-Flex prosthesis provides an alternative to the NexGen LPS prosthesis, with greater range of motion and without severe complications or radiographic outcomes. The clinical advantages were not shown in the KSS or the HSS. Thus, the selection of a high-flexion prosthesis should depend on the characteristics of the patient, particularly high motivation and poor preoperative ROM. The potential benefits in the medium- and long-term outcomes require confirmation by larger, multicenter and well-conducted RCTs.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

No clinical benefit of high-flex total knee arthroplasty. A meta-analysis of randomized controlled trials

The application of high-flex prosthesis in total knee arthroplasty (TKA) is an area of continuing debate. Thus, we conducted a meta-analysis of randomized controlled trials (RCTs). A literature search was performed in PubMed, EMBASE and the Cochrane database. 10 trials involving 1230 knee joints were eligible for our meta-analysis. No significant difference was observed between the two designs regarding postoperative range of flexion, clinical scores, quality of life outcomes, or complication rate. Moreover, the advantage of high-flex implants for patients with high preoperative range remained not statistically significant and high-flex design in NexGen system showed a marginal improvement in the postoperative range of flexion. Based on current findings, high-flex prosthesis did not appear to confer any benefit as compared to standard prosthesis.

Do patients really gain outcome benefits when using the high-flex knee prostheses in total knee arthroplasty? A meta-analysis of randomized controlled trials

The purpose of this study was to undertake a meta-analysis to evaluate whether patients really gain outcome benefits when using the high-flex (HF) prostheses in total knee arthroplasty (TKA) compared with standard (STD) implants. Only randomized controlled trials were included in this meta-analysis. After searching PubMed, Embase, Wed of Science and Cochrane Library, 1042 papers were identified and 18 trials were finally eligible for meta-analysis including 2069 knees (1906 patients). We found no statistically significant difference between the two designs in terms of ROM, knee scores (KSS, HSS, WOMAC, and SF-36), patients' satisfaction and complications. Hence there is currently no evidence to confirm that the use of high-flex prostheses in short-term is superior to the standard prostheses after total knee arthroplasty.

Standard versus high-flexion posterior stabilized total knee prostheses

This meta-analysis compared clinical outcomes between standard and high-flexion posterior-stabilized total knee prostheses to evaluate which type of total knee prosthesis was superior. Randomized, controlled trials published until October 2013 comparing standard and high-flexion posterior-stabilized total knee prostheses were reviewed. Methodologic quality was assessed with the Physiotherapy Evidence Database scale. After data extraction, the authors compared results with fixed effects or random effects models, depending on the heterogeneity of the included studies. Eight randomized, controlled trials involving 660 patients met the predetermined inclusion criteria. No statistically significant differences between patients undergoing standard and high-flexion posterior-stabilized total knee prostheses were noted in postoperative range of motion (ROM) (weighted mean difference, -1.43; 95% confidence interval [CI], -4.52 to 1.67; P=.37); flexion angle (weighted mean difference, 0.54; 95% CI, -3.75 to 4.84; P=.80); Knee Society Score (weighted mean difference, 0.92; 95% CI, -0.64 to 2.48; P=.25); Hospital for Special Surgery knee score (weighted mean difference, 0.57; 95% CI, -0.42 to 1.55; P=.26); or Knee Society function score (weighted mean difference, 1.00; 95% CI, -1.49 to 3.49; P=.43). No statistical difference was found between the 2 prosthesis types in complications, involving 21 cases in the standard group and 14 cases in the high-flexion group. The current findings confirm that high-flexion posterior-stabilized total knee prostheses are not superior to standard prostheses in terms of ROM, flexion angle, knee scores, or complications with 5 years or less of follow-up.

Intermediate and long-term quality of life after total knee replacement: a systematic review and meta-analysis

BACKGROUND

Total knee replacement is a highly successful and frequently performed operation. Technical outcomes of surgery are excellent, with favorable early postoperative health-related quality of life. This study reviews intermediate and long-term quality of life after surgery.

METHODS

A systematic review and meta-analysis of all studies published from January 2000 onward was performed to evaluate health-related quality of life after primary total knee replacement for osteoarthritis in patients with at least three years of follow-up. Key outcomes were postoperative quality of life, function, and satisfaction compared with the preoperative status. Strict inclusion and exclusion criteria were applied. Quality appraisal and data tabulation were performed with use of predefined criteria. Data were synthesized by narrative review and random-effects meta-analysis utilizing standardized mean differences. Heterogeneity was assessed with the tau(2) and I(2) statistics.

RESULTS

Nineteen studies were included in the review. Intermediate and long-term postoperative quality of life was superior to the preoperative level in qualitative and quantitative analyses. The pooled effect in combined WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) and KSS (Knee Society Score) outcomes was a marked improvement from baseline with respect to the total score (2.17; 95% CI [confidence interval], 1.13 to 3.22; p < 0.0001) and the pain (1.72; 95% CI, 0.97 to 2.46; p < 0.00001) and function (1.26; 95% CI, 0.87 to 1.64; p < 0.00001) domains. Most patients were satisfied with the surgery and derived substantial benefits for daily functional activities. Tau(2) (0.20 to 1.10) and I(2) (90% to 98%) values implied significant clinical and statistical heterogeneity.

CONCLUSIONS

Total knee replacement confers significant intermediate and long-term benefits with respect to both disease-specific and generic health-related quality of life, especially pain and function, leading to positive patient satisfaction. Recommendations for necessary future studies are provided.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Postoperative range of motion does not correlate with patient reported outcome scores in Asians after total knee arthroplasty

Activities in Asian cultures require greater knee flexion. However, this study hypothesized that post-operative range of motion (ROM) does not correlate with patient reported outcome scores at 2years. 292 TKAs were evaluated at a public hospital in Singapore from January 2006 to May 2009. The relationship between ROM and outcome scores was examined using a multiple linear regression model with Generalized Estimating Equation (GEE) allowing adjustment for confounders and repeated TKAs within a patient. Analysis did not yield statistically significant results when patients' post-op ROM was correlated with outcome scores at 2years. Lack of post op ROM does not translate into poorer outcome scores and dissatisfaction. Doctors can now counsel patients who are concerned about a lack of ROM after TKA.

Design modifications may improve range of motion following posteriorly stabilized total knee replacement: a matched pair study

BACKGROUND

Our institution's latest knee implant design modifications aimed to decrease anterior knee pain, reduce the amount of bone that is resected in the femoral box, and improve range of motion.

QUESTIONS/PURPOSES

Does this new knee design achieve desired clinical improvement in our patient population? This study was designed to compare our new design to that of its predecessor in a matched pair analysis.

METHODS

A consecutive group of 100 knees underwent total knee arthroplasty using the newer box reamer (BR) posterior-stabilized design was matched by age, gender, and body mass index (BMI) to patients with the classic posterior-stabilized (PS) component. Average follow-up was 29.6 months (range 21-47) in the new group. Preoperative range of motion (ROM) and clinical scores, such as Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Knee Society Scores, were obtained and compared to the patients' most recent follow-up. Manipulation under anesthesia (MUA) and revision of the implant for any reason were also analyzed. Ability to attain ROM of >120°, >130°, and >140° was also determined in each cohort.

RESULTS

At 2-year follow-up, 41% of BR knees achieved >130° flexion compared with 19% in the PS design group. WOMAC improved from pre-op 47 to 80 at 1 year in the newer BR design group and 48 to 80 in the classic PS design group. There were 9 MUAs in the newer BR design group compared with 14 in the classic PS design group. There were three revisions in the PS group and none in the BR group.

CONCLUSIONS

Design improvements to this newer knee allowed more patients to achieve greater flexion and appear to have achieved clinical and design goals of the engineering modifications.

Outcome and range of motion using a high-flexion cruciate-retaining TKA

Increased knee flexion after total knee arthroplasty (TKA) may contribute to patients' increased satisfaction and more active lifestyles. This study evaluated a TKA component designed for high flexion (more than 125°). The design features an anatomic sagittal femoral radius with short, flared femoral condyles to allow for femoral rollback. Fifty TKA procedures in 47 patients were evaluated prospectively regarding clinical outcomes using Knee Society knee and function scores, Short Form 12 physical component scores, and flexion measured clinically and by digital lateral supine active flexion radiographs. Preoperative and 1-year postoperative radiographs were analyzed by an independent observer. Mean maximum flexion measured clinically was 115° preoperatively and 120° one year postoperatively, with 76% of TKAs achieving more than 120° and 44% achieving more than 125°. Sex, body mass index, and preoperative flexion were not predictors of postoperative flexion. Mean flexion by radiograph was 108° preoperatively and 111° one year postoperatively, with 31% of knees achieving more than 120° and 14% more than 125°. Mean Knee Society knee and function scores and the Short Form 12 physical component scores were 52, 55, and 32 preoperatively, respectively, and 89, 77, and 40 one year postoperatively, respectively. Of the 50 knees, 84% had improvement in their Knee Society function scores, and 76% had improvement in their Short Form 12 physical component scores. The study revealed evidence of increased early postoperative flexion with the use of a cruciate-retaining high-flexion TKA design.

High-flexion prosthesis improves function of TKA in Asian patients without decreasing early survivorship

BACKGROUND

Two previous studies recently raised the possibility of a high risk of early femoral components loosening with high-flexion (HF) prostheses in Asian populations and suggested that the high failure rate of HF TKAs was associated with HF ability. However, these findings are controversial given other studies reporting a low incidence of aseptic failures in HF prostheses.

QUESTIONS/PURPOSES

We therefore determined (1) the rate of achieving postoperative HF after HF TKA; (2) whether the aseptic loosening rate of HF prostheses is high; and (3) whether the survivorship was worsened in patients who achieved postoperative deep knee flexion in our cohort of Korean patients.

METHODS

We retrospectively reviewed 488 patients who had 698 primary TKAs using the NexGen(®) Legacy Posterior-Stabilized Flex system implanted from 2003 to 2010. There were 40 men and 448 women with a mean age of 68 years. We obtained Hospital for Special Surgery scores, maximal flexion, and radiographs. The minimum followup for functional and radiographic evaluations was 2 years (median, 4.8 years; range, 2-8.7 years). We performed a survival analysis on all patients for aseptic loosening.

RESULTS

Three hundred sixty knees (52%) could achieve ≥ 135° maximum flexion. Six of the 698 knees (0.9%) developed aseptic loosening (three femoral and three tibial). The survival at 5 years for aseptic loosening was 99.1%. The overall survival for aseptic failure did not differ between knees that achieved HF and those that did not.

CONCLUSIONS

We observed a low incidence of early aseptic loosening of HF designs in this series. Our findings suggest HF TKAs have high survival in Asian patients at 5 years although half of the patients attained maximum flexion more than 135° postoperatively.

Outcomes of the different types of total knee arthroplasty with the identical femoral geometry

Purpose

There are controversies around the role of the posterior cruciate ligament and the effect of design modifications for high flexion in total knee arthroplasty (TKA). So, we compared the clinical outcomes of the cruciate retaining (CR), posterior stabilized (PS), and high flexion posterior stabilized (F-PS) designs in TKA with identical femoral geometry.

Materials and Methods

One hundred seventy nine knees with 3 different types of prostheses after a minimum 5-year follow-up were enrolled in this retrospective study: 45 with CR, 40 with PS and 94 with F-PS. The mean ages of these groups were 65.7, 67.2, and 67.5, and the mean durations of follow-up were 8.1, 8.0, and 6.8 years, respectively. We compared the range of motion, functional outcomes, and radiographic measurements at the 2-year follow-up and last follow-up.

Results

The maximal flexion angle was significantly lower in the CR group than the F-PS group at the 2-year follow-up. However, there was no significant difference at the last follow-up. Functional outcomes and survival rate of the three groups were similar at the last follow-up.

Conclusions

Three different types of TKAs (CR, PS and F-PS) with identical femoral geometry showed similar mid-term outcomes with regard to the range of motion, functional outcomes and survival rate.