Range of motion of standard and high-flexion posterior cruciate-retaining total knee prostheses a prospective randomized study

Is Highly Cross-Linked Polyethylene Safe for Use in High-Flexion Posterior Stabilized Total Knee Arthroplasty?

BACKGROUND

Application of highly cross-linked polyethylene (HXLPE) to a posterior cruciate-substituting total knee arthroplasty (TKA) might add the risk of fracture and failure of the tibial polyethylene insert. The purpose of this study is to evaluate the long-term (up to 19 years) clinical and radiographic results of posterior cruciate-substituting TKAs with HXLPE or conventional polyethylene.

METHODS

This study analyzed the results of 1,217 patients (444 men and 773 women; mean age of 65 ± 7 years, range, 31-85) (2,434 knees) who had received a NexGen LPS-Flex prosthesis with a conventional tibial insert in one knee and the same prosthesis with an HXLPE tibial insert in the contralateral knee. The mean duration of follow-up was 17 years (range, 15-19).

RESULTS

The 2 groups did not differ significantly (P > .05) with regard to the clinical and radiographic results. No knee in either group had a fracture of the tibial polyethylene post or failure of the locking mechanism of the tibial polyethylene insert or osteolysis. Twenty-eight knees (2.3%) in the HXLPE group and 26 knees (2.1%) in the conventional polyethylene group were revised. The estimated survival rate at 17 years was 97.7% in the HXLPE group and 97.9% in the conventional polyethylene group.

CONCLUSION

The data suggest that clinical and radiographic findings at a mean of 17 years after posterior cruciate-substituting TKA are the same for patients treated with HXLPE and those treated with conventional polyethylene.

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.

No difference of survival between cruciate retaining and substitution designs in high flexion total knee arthroplasty

The aim of this study was to compare the long-term implant survival and outcomes in patients with high-flexion cruciate-retaining (CR) or high-flexion posterior cruciate-substituting (PS) knee implants. A total of 253 knees (CR group: 159 vs. PS group: 94) were available for examination over a mean follow-up of 10 years. Clinical outcomes were assessed including the Hospital for Special Surgery score, Knee Society score and Western Ontario and McMaster Universities Osteoarthritis Index score at the final follow-up. Radiologic measurements were also assessed including the hip-knee-ankle angle and radiolucent lines according to the KSS system at the final follow-up. The survival rate was analyzed using the Kaplan–Meier method. At the final follow-up, the mean total HSS scores were similar between the two groups (p = 0.970). The mean hip-knee-ankle angle at the final follow-up was similar between groups (p = 0.601). The 10- and 15-year survival rates were 95.4% and 93.3% in the CR group and 92.7% and 90.9% in the PS group, respectively, with no significant difference. Similar clinical and radiographic outcomes could be achieved with both the high-flexion CR and high-flexion PS total knee designs without a difference in survival rate after a 10-year follow-up.

20-Year Minimum Outcomes and Survival Rate of High-Flexion Versus Standard Total Knee Arthroplasty

BACKGROUND

There are conflicting reports of early and mid-term results of the high-flexion total knee arthroplasties (TKAs). The purpose of the present long-term follow-up study was to determine the long-term (minimum 20 years) clinical and radiographic and CT scan results, and the survival rates of high-flexion versus standard TKAs.

METHODS

Ninety-five patients (190 knees) were included (mean age, 65 ± 6.5 years). The mean follow-up was 20.3 years (range, 20 to 20.6 years).

RESULTS

Revision of the TKA was performed in 5 knees (5.2%) with high-flexion TKA and in 3 knees (3.2%) with standard TKA. The rate of survival at 20 years was 94.8% (95% CI, 91%-98%) in the high-flexion TKA group and 96.8% (95% CI, 92%-100%) in the standard TKA group with reoperation for any reason. No knee had osteolysis in either group.

CONCLUSIONS

At this length of follow-up, high-flexion TKA has comparable outcomes and survivorship to standard TKA.

Comparison of clinical and radiographic results between total knee arthroplasties using medial pivot and posterior-stabilized prosthesis: A meta-analysis

OBJECTIVE

To evaluate the clinical and radiographic outcomes of total knee arthroplasties (TKA) between using medial-pivot (MP) and posterior-stabilized (PS) prosthesis. Does MP prosthesis and PS prosthesis influence the clinical results of a TKA?

METHODS

An electronic literature search of PubMed Medline and the Cochrane Library was performed from inception to October 1, 2019. A meta-analysis to compare postoperative outcomes of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Knee Society Score (KSS), range of motion (ROM), complications, and radiographic results between MP and PS prosthesis were conducted.

RESULTS

Seven eligible studies involving 934 adult patients (MP group, n = 461; PS group, n = 473) were identified for analysis. This study showed no significant difference between the 2 groups in the WOMAC scores, KSS, ROM, and complications (P > .05). The differences of the femorotibial angle, position of implant, and patellar tilt were also not significant between the 2 groups (P > .05).

CONCLUSION

The present meta-analysis has shown that patients with the MP prosthesis have similar clinical results as patients with PS prosthesis. Furthermore, the radiographic results, especially patella tilt angle, were also similar between the 2 groups. Therefore, surgeons should be aware that the types of prostheses are not a decisive factor to ensure successful operation.

An Assessment of Randomized Controlled Trial Quality in The Journal of Bone & Joint Surgery: Update from 2001 to 2013

BACKGROUND

The quality of reporting of randomized controlled trials (RCTs) published in The Journal of Bone & Joint Surgery (JBJS) from 1988 to 2000 was previously analyzed. The purpose of this current study was to analyze the quality of reporting of RCTs published in JBJS from 2001 to 2013 to identify trends over time and potential areas of improvement for future clinical trials.

METHODS

A manual search of the JBJS database identified RCTs published between January 2001 and December 2013. Quality assessments, using the Detsky quality-of-reporting index (Detsky score), a modified Cochrane risk-of-bias tool, and abstraction of relevant data identifying predictors of quality, were conducted.

RESULTS

A total of 5,780 publications were identified in JBJS from 2001 to 2013, with 285 RCTs (4.9%), representing an increase from the prior 13-year period. The overall mean transformed Detsky score (and standard error) increased significantly (p < 0.001) from 68.1% ± 1.67% to 76.24% ± 0.72%. The percentage of multicenter RCTs decreased from 67% to 31%. The percentage of positive trials also decreased from 80% to 50.5%, as did the mean sample size (212 to 166). Regression analysis indicated that trials with an epidemiologist as the first author and nonsurgical trials were significantly associated (p = 0.001) with a higher overall trial quality score. The categories of the lowest mean methodology scores were randomization and concealment, eligibility criteria, and reasons for patient exclusion, as identified with the Detsky score, and patient and assessor blinding, as identified with the risk-of-bias assessment.

CONCLUSIONS

The quantity and quality of published RCTs in JBJS have increased in the 2001 to 2013 time period compared with the previous time period. Although these improvements are encouraging, trends to smaller, single-center trials were also observed. To efficiently determine the efficacy of orthopaedic treatments and limit bias, high-quality randomized trials of appropriate sample size and rigorous design are needed.

Comparison of Posterior Cruciate-Retaining and High-Flexion Cruciate-Retaining Total Knee Arthroplasty Design

BACKGROUND

High-flexion prostheses have been developed to achieve deep flexion after total knee arthroplasty. The purpose of this study is to compare standard NexGen (CR, cruciate-retaining) and high-flexion NexGen (CR-flex) total knee prostheses in terms of range of motion, clinical and radiologic outcomes, rates of complications, and survivorship in long-term follow-up.

METHODS

From January 2000 to December 2008, 423 consecutive knees underwent total knee arthroplasty using standard CR or CR-flex prostheses. Fifty-three patients were lost to follow-up or declined to participate and 54 died, leaving 290 knees. The minimum duration of follow-up was 8 years (mean 10.1 years). Physical examination and knee scoring of patients were assessed preoperatively, at 6 months and 1 year after surgery, and annually thereafter. Supine anteroposterior and lateral radiographs and standing anteroposterior hip-to-ankle radiographs were obtained preoperatively and at each follow-up.

RESULTS

Mean postoperative range of motions in the standard CR group and the CR-flex group were similar, showing no significant difference between the 2 groups (P = .853). At the time of the final follow-up, mean total Hospital for Special Surgery scores were similar between the 2 groups (P = .118). Mean Knee Society pain (P = .325) and function scores (P = .659) were also comparable between the 2 groups. Western Ontario and McMaster Universities Osteoarthritis Index score showed no intergroup difference either (P = .586). The mean hip-knee-ankle angle at the final follow-up was approximately the same (P = .940). Mean coronal angles of femoral and tibial component at final follow-up were also similar (P = .211 and P = .764, respectively). The prevalence of the radiolucent line was 0.6% in the standard CR group and 0.9% in the CR-flex group. Estimated survival rate according to Kaplan-Meier survival analysis was 97.2% in the standard CR group and 95.6% in the CR-flex group at mean follow-up of 10.1 years.

CONCLUSION

This study suggests that excellent clinical and radiographic outcomes could be achieved with both standard and high-flexion CR total knee designs. High-flexion CR prosthesis did not show any advantages over the standard design.

A Single Surgeon Series Comparing the Outcomes of a Cruciate Retaining and Medially Stabilized Total Knee Arthroplasty Using Kinematic Alignment Principles

BACKGROUND

Total knee arthroplasty (TKA) designs are developed to optimize kinematics and improve patient satisfaction. The cruciate retaining (CR) and medially stabilized (MS) TKA designs have reported good mid-term follow-up outcomes. However, reasons for consistently high rates of patient dissatisfaction following a TKA remain poorly understood. To further investigate this, we compared the short-term functional outcomes and quality of life, using patient-reported outcome measures (PROMs) and range of motion (ROM), between a CR and MS TKA.

METHODS

A prospective comparison was made between 2 groups (44 CR-TKAs vs 46 MS-TKAs). The Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS-12, KOOS-Short form, KOOS-Joint Replacement, Oxford Knee Score, Western Ontario and McMaster Universities Osteoarthritis Index, UCLA Activity Scale, and EuroQuality of life - 5 Dimension were completed preoperatively and 1 year postoperatively. The Forgotten Joint Score (FJS) and Visual Analogue Scale-Satisfaction were completed at 1 year postoperatively. ROM was collected preoperatively and 1 year postoperatively.

RESULTS

Patients who underwent an MS-TKA scored significantly better than the CR-TKA on the FJS (MS = 79.87, CR = 63.8, P = .005), the KOOS-12 Quality of Life subscale (MS = 82.8, CR = 74.4, P = .43), and the KOOS Quality of Life subscale (MS = 82.8, CR = 74.6, P = .44). There was no difference between the groups in all assessed PROMs or ROM, preoperatively and 1 year postoperatively.

CONCLUSION

Patients who underwent the MS-TKA scored significantly better on the FJS and the quality of life subscale of the KOOS and KOOS-12 than those who underwent a CR-TKA. All other assessed PROMs and ROM were comparable between the 2 groups and demonstrated that both implants facilitated symptom relief and improved daily function at 1 year postoperatively. These findings suggest that at short-term follow-up, the MS device is more likely to allow a patient to "forget" that a joint has been replaced and restore their quality of life. Long-term assessment of MS-TKA design outcomes in larger cohorts is recommended.

Biomechanical analysis of a changed posterior condylar offset under deep knee bend loading in cruciate-retaining total knee arthroplasty

BACKGROUND

The conservation of the joint anatomy is an important factor in total knee arthroplasty (TKA). The restoration of the femoral posterior condylar offset (PCO) has been well known to influence the clinical outcome after TKA.

OBJECTIVE

The purpose of this study was to determine the mechanism of PCO in finite element models with conservation of subject anatomy and different PCO of ±1, ±2, ±3 mm in posterior direction using posterior cruciate ligament-retaining TKA.

METHODS

Using a computational simulation, we investigated the influence of the changes in PCO on the contact stress in the polyethylene (PE) insert and patellar button, on the forces on the collateral and posterior cruciate ligament, and on the quadriceps muscle and patellar tendon forces. The computational simulation loading condition was deep knee bend.

RESULTS

The contact stresses on the PE insert increased, whereas those on the patellar button decreased as posterior condylar offset translated to the posterior direction. The forces exerted on the posterior cruciate ligament and collateral ligaments increased as PCO translated to the posterior direction. The translation of PCO in the anterior direction, in an equivalent flexion angle, required a greater quadriceps muscle force.

CONCLUSIONS

Translations of the PCO in the posterior and anterior directions resulted in negative effects in the PE insert and ligament, and the quadriceps muscle force, respectively. Our findings suggest that orthopaedic surgeons should be careful with regard to the intraoperative conservation of PCO, because an excessive change in PCO may lead to quadriceps weakness and an increase in posterior cruciate ligament tension.

Regulation of MMP and TIMP expression in synovial fibroblasts from knee osteoarthritis with flexion contracture using adenovirus-mediated relaxin gene therapy

PURPOSE

The aim of this study was to investigate the effects of relaxin (RLN) expression on fibrosis inhibition in synovial fibroblasts.

MATERIALS AND METHODS

Tissue cells from patients with knee osteoarthritis and >30° flexion contractures were utilised. Synovial fibroblasts were activated by TGF-β1 (two nanograms per millilitre) and then exposed to Ad-RLN as a therapeutic gene, adenovirus-lacZ construct as a marker gene, and SB505124 as an inhibitor for TGF-β1 signal for 48 h. The mRNA expression levels of collagens and MMPs were analysed by reverse transcription-polymerase chain reaction. Also, fibronectin, phosphorylation of Smad2 and ERK1/2, alpha smooth muscle actin, TIMP-1, TIMP-2, MMP-1 and MMP-13 levels were estimated using western blotting, and the total collagen synthesis was assayed.

RESULTS

Ad-RLN-transduced synovial fibroblasts demonstrated 17%, 13%, and 48% reduction in collagen I, III and IV mRNA expression levels, respectively, and a 40% decrease in MMP-3, MMP-8, 20% decrease in MMP-9, MMP-13 mRNA expression, compared to non-Ad-RLN-transduced cells. In protein expression, Ad-RLN-transduced synovial fibroblasts demonstrated 46% increase in MMP-1, 5% decrease in MMP-2, 51% increase in MMP-9, and 22% increase in MMP-13, compared to non-Ad-RLN-transduced cells. Ad-RLN-transduced synovial fibroblasts showed a 25% decrease in TIMP-1 and 65% decrease in TIMP-2 protein expression at 48h, compared to non-Ad-RLN-transduced cells. Ad-RLN-transduced synovial fibroblasts demonstrated a 45% inhibition of fibronectin in protein expression level and 38% decrease in total collagen synthesis at 48h, compared to non-Ad-RLN-transduced cells.

CONCLUSION

Relaxin expression exerted anti-fibrogenic effects on synovial fibroblasts from patients with knee osteoarthritis and flexion contractures. Therefore, relaxin could be an alternative therapeutic agent during the initial stage of osteoarthritis with flexion contracture by exerting its anti-fibrogenic effects.

The Long-Term Results of Simultaneous High-Flexion Mobile-Bearing and Fixed-Bearing Total Knee Arthroplasties Performed in the Same Patients

BACKGROUND

Our study determined the long-term clinical, radiographic, and computed tomography scanning results of high-flexion mobile-bearing and fixed-bearing total knee arthroplasties (TKAs) in the same younger patients. In addition, the survivorship and complication rates of both groups were evaluated.

METHODS

Bilateral simultaneous sequential TKAs were performed in 164 patients (328 knees). There were 142 women and 22 men with a mean age of 63 ± 9 years (range 41-65), who received a high-flexion mobile-bearing prosthesis in one knee and a high-flexion fixed-bearing prosthesis in the other. The mean follow-up was 16.9 years (range 15-18).

RESULTS

At the latest follow-up, the mean Knee Society knee scores (94 ± 8 vs 95 ± 9 points, P = .7), Western Ontario and McMaster Universities Osteoarthritis Index (20 ± 11 vs 20 ± 11 points, P = 1.0), range of knee motion (125° ± 10° vs 127° ± 9°, P = .8), and University of California, Los Angeles activity scores (7.8 vs 7.8 points, P = 1.0) were below the level of clinical significance between the 2 groups. Survival rate of high-flexion mobile-bearing TKA was 98.2% and that of high-flexion fixed-bearing TKA was 97% at 16 years. No osteolysis was identified in either group.

CONCLUSION

After a minimum duration of follow-up of 13 years, we found no significant difference between these 2 groups with regard to functional outcome, knee motion, prevalence of osteolysis, or survivorship. This study does not clearly direct the surgeon toward either arm of treatment. Longer term follow-up is needed to prove the superiority of one type of implant over the other one.

How prosthetic design influences knee kinematics: a narrative review of tibiofemoral kinematics of healthy and joint-replaced knees

INTRODUCTION

To improve the total knee arthroplasty (TKA) prosthesis design, it is essential to study the kinematics of the tibiofemoral joint. Many studies have been conducted in this area; however, conflicting results and incomparable testing methods make it difficult to draw definitive conclusions or compare research from studies. The goal of this article is to introduce what is known about both healthy and prosthetic tibiofemoral joint kinematics.

AREAS COVERED

Healthy tibiofemoral joint kinematics are reviewed in vivo by different activities, and the kinematics of existing knee prosthetic design features are considered separately. These features include but are not limited to cruciate retaining, posterior cruciate substituting, mobile-bearing, and high flexion.

EXPERT COMMENTARY

The type of activity that is being performed has a great influence on the kinematics of healthy knees, and the influences of different TKA prosthetic design features on the kinematics are complex and varied. Moreover, the TKA postoperative functional performance is influenced by many factors, and prosthetic design is among them, but not the only one that defines the performance.

Influence of Posterior Tibial Slope on Kinematics After Cruciate-Retaining Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to investigate the influence of posterior tibial slope (PTS) on knee kinematics after cruciate-retaining total knee arthroplasty (CR-TKA). These influences were evaluated using a prosthesis designed with high geometric conformity to the medial articular surface under the weight-bearing condition of deep knee bending.

METHODS

We evaluated 71 knees (52 patients) after CR-TKA using 2- to 3-dimensional registration techniques. All patients were categorized into 2 groups: group A (PTS ≤ 7°) and group B (PTS ≥ 8°). We compared in vivo knee kinematics during deep knee bending under weight-bearing conditions between the 2 groups. The anteroposterior position of the nearest points, flexion angles, and external rotation angles of the femoral components relative to the tibial components were evaluated. Additionally, the knee flexion angles of the femur relative to the tibia obtained from the installation angles of the components were evaluated.

RESULTS

PTS did not affect the external rotation angles and anteroposterior position. The postoperative maximum flexion angle and range of motion between the femur and tibia in group B were significantly greater than those in group A.

CONCLUSION

PTS of 8° or more in CR-TKA using prosthetics designed with high geometric conformity to the medial articular surface did not affect the anteroposterior position and external rotation, but increased the postoperative maximum flexion angle and range of motion.

Comparison of High-Flexion Fixed-Bearing and High-Flexion Mobile-Bearing Total Knee Arthroplasties-A Prospective Randomized Study

BACKGROUND

There is none, to our knowledge, about comparison of high-flexion fixed-bearing and high-flexion mobile-bearing total knee arthroplasties (TKAs) in the same patients. The purpose of this study was to determine whether clinical results; radiographic and computed tomographic scan results; and the survival rate of a high-flexion mobile-bearing TKA is better than that of a high-flexion fixed-bearing TKA.

METHODS

The present study consisted of 92 patients (184 knees) who underwent same-day bilateral TKA. Of those, 17 were men and 75 were women. The mean age at the time of index arthroplasty was 61.5 ± 8.3 years (range 52-65 years). The mean body mass index was 26.2 ± 3.3 kg/m² (range 23-34 kg/m²). The mean follow-up was 11.2 years (range 10-12 years).

RESULTS

The Knee Society knee scores (93 vs 92 points; P = .531) and function scores (80 vs 80 points; P = 1.000), WOMAC scores (14 vs 15 points; P = .972), and UCLA activity scores (6 vs 6 points; P = 1.000) were not different between the 2 groups at 12 years follow-up. There were no differences in any radiographic and CT scan parameters between the 2 groups. Kaplan-Meier survivorship of the TKA component was 98% (95% confidence interval, 93-100) in the high-flexion fixed-bearing TKA group and 99% (95% confidence interval, 94-100) in the high-flexion mobile-bearing TKA group 12 years after the operation.

CONCLUSION

We found no benefit to mobile-bearing TKA in terms of pain, function, radiographic and CT scan results, and survivorship. Longer-term follow-up is necessary to prove the benefit of the high-flexion mobile-bearing TKA over the high-flexion fixed-bearing TKA.

Do High-Flexion Total Knee Designs Increase the Risk of Femoral Component Loosening?

BACKGROUND

The purpose of our prospective, randomized, long-term investigation is to compare the aseptic loosening rate of the femoral component of the total knee prosthesis and clinical and radiographic results of high-flexion posterior cruciate-substituting knee prosthesis or standard posterior cruciate-substituting knee prosthesis in the same patients.

METHODS

There were 960 patients (mean age 71.3 years). The mean follow-up period was 13.2 years (range 10-14). The patients were assessed clinically and radiographically with rating systems of the Knee Society. Furthermore, Western Ontario and McMaster Universities Osteoarthritis questionnaire and ranges of knee motion were determined in both groups.

RESULTS

In the high-flexion knee group, 2 knees (0.2%) had aseptic loosening of both femoral and tibial components. In the standard knee group, 2 knees (0.2%) had aseptic loosening of the femoral component only. The mean postoperative knee scores (97 vs 97 points), Western Ontario and McMaster Universities Osteoarthritis scores (19 vs 19 points), and range of knee motion (128° vs 129°) were not significantly different between the 2 groups. Two knees (0.2%) in the high-flexion knee group underwent a revision of both femoral and tibial components and 2 knees (0.2%) in the standard knee group had a revision of the femoral component only.

CONCLUSION

After a mean of 13.2 years of follow-up, this study did not show increased incidence of femoral component loosening in the high-flexion knee group. Furthermore, we found no significant differences between the 2 groups with regard to clinical or radiographic parameters or range of knee motion.

Simplified Chinese version of the Forgotten Joint Score (FJS) for patients who underwent joint arthroplasty: cross-cultural adaptation and validation

BACKGROUND

The Forgotten Joint Score (FJS) is a newly developed health-related quality of life (HRQoL) questionnaire designed to evaluate the awareness after total knee arthroplasty (TKA). This study cross-culturally adapted and psychometrically validated a simplified Chinese version of the FJS (SC-FJS).

METHODS

Cross-cultural adaptation was performed according to the internationally recognized guidelines. One-hundred and fifty participants who underwent primary TKA were recruited in this study. Cronbach's α and intra-class correlations were used to determine reliability. Construct validity was analyzed by evaluating the correlations between SC-FJS and the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the short form (36) health survey (SF-36).

RESULTS

Each of the 12 items was properly responded and correlated with the total items. SC-FJS had excellent reliability [Cronbach's α = 0.907, intra-class correlation coefficient (ICC) = 0.970, 95% CI 0.959-0.978). Elimination of any one item in all did not result in a value of Cronbach's α of <0.80. SC-FJS had a high correlation with symptoms (0.67, p < 0.001) and pain (0.60, p < 0.001) domains of KOOS and social functioning (0.66, p < 0.001) domain of SF-36, and it also moderately correlated with function in daily living (0.53, p < 0.001) and function in sport and recreation (0.40, p < 0.001) domains of KOOS, and physical subscale of SF-36 (0.49-0.53, p < 0.001) but had a low (r = 0.20) or not significant (p > 0.05) correlation with mental subscale of SF-36.

CONCLUSIONS

SC-FJS demonstrated excellent acceptability, internal consistency, reliability, and construct validity, which can be recommended for patients who underwent joint arthroplasty in Mainland China.

Good validity and reliability of the forgotten joint score in evaluating the outcome of total knee arthroplasty

Background and purpose - When evaluating the outcome after total knee arthroplasty (TKA), increasing emphasis has been put on patient satisfaction and ability to perform activities of daily living. To address this, the forgotten joint score (FJS) for assessment of knee awareness has been developed. We investigated the validity and reliability of the FJS. Patients and methods - A Danish version of the FJS questionnaire was created according to internationally accepted standards. 360 participants who underwent primary TKA were invited to participate in the study. Of these, 315 were included in a validity study and 150 in a reliability study. Correlation between the Oxford knee score (OKS) and the FJS was examined and test-retest evaluation was performed. A ceiling effect was defined as participants reaching a score within 15% of the maximum achievable score. Results - The validity study revealed a strong correlation between the FJS and the OKS (intraclass correlation coefficient (ICC) = 0.81, 95% CI: 0.77-0.85; p < 0.001). The test-retest evaluation showed almost perfect reliability for the FJS total score (ICC = 0.91, 95% CI: 0.88-0.94) and substantial reliability or better for individual items of the FJS (ICC? 0.79). We found a high level of internal consistency (Cronbach's? = 0.96). The ceiling effect for the FJS was 16%, as compared to 37% for the OKS. Interpretation - The FJS showed good construct validity and test-retest reliability. It had a lower ceiling effect than the OKS. The FJS appears to be a promising tool for evaluation of small differences in knee performance in groups of patients with good clinical results after TKA.

A Comparison of 5 Models of Total Knee Arthroplasty in Young Patients

BACKGROUND

Several different total knee implants were introduced in an attempt to potentially improve outcomes of total knee arthroplasty in young patients. The object of this study was to compare the clinical outcomes of 5 models of total knee implants.

METHODS

We compared 172 patients who received posterior substituting knee implants with an average 13.2-year follow-up, 182 patients who received high-flex knees with an average 11.8-year follow-up, 190 patients who received mobile-bearing knees with an average 13.9-year follow-up, 170 patients who received gender-specific knees with an average 10.8-year follow-up, and 192 patients who received oxidized zirconium knees with an average 13.5-year follow-up. There were 186 men and 720 women (mean age, 53.3 years; range, 40-60). The mean follow-up was 12.6 years.

RESULTS

We found similar postoperative Knee Society knee and function scores (P = .693 and P = .698, respectively), postoperative Western Ontario MacMaster Universities Osteoarthritis Index score (P = .523), University of California, Los Angeles activity score (P = .651) and range of knee motion (P = .417), radiographic results (P > .05), revision rates (P = .241), and survivorship (P = .981) of the implants.

CONCLUSIONS

Range of knee motion, prevalence of polyethylene wear, osteolysis, revision rates, and survivorship of 5 models of total knee arthroplasties were similar. We believe that good designs with a good quality of polyethylene and defined surgical techniques provided good clinical and radiographic outcomes of these 5 models of total knee arthroplasties at this length of follow-up.

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.

Does knee awareness differ between different knee arthroplasty prostheses? A matched, case-control, cross-sectional study

Background

Low knee awareness after Total Knee Arthroplasty (TKA) has become the ultimate goal in trying to achieve a natural feeling knee that meet patient expectations. To accommodate this manufacturers of TKAs have developed new prosthetic designs that potentially could give patients a more natural feeling knee during activities.

The purpose af this study was to compare the Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) of patients treated with a previous generation standard Cruciate Retaining (CR) TKA to the scores obtained by patients treated with a newer generation CR TKA or a mobile bearing CR TKA.

Methods

We identified all patients receiving a new generation CR TKA or mobile bearing TKA at our institution between 2010 and 2012. These were matched to a population of patients receiving a standard CR TKA regarding age, gender, year of surgery, Kellgren-Lawrence (KL) grade and pre- and postoperative knee alignment. Patients were asked to complete the FJS and OKS questionnaires. Of the 316 patients completing the survey 64 standard CR TKAs to 35 new generation CR TKAs and 121 standard CR TKAs to 68 mobile bearing TKAs were matched. The FJS and OKS scores of the three TKA designs were compared.

Results

When comparing the new generation CR TKAs to the standard CR TKAs we found statistically significant higher OKS and FJS scores (6 (p = 0.04) and 16 (p = 0.03) points respectively) for the new generation CR TKAs. When comparing the mobile bearing TKAs to the standard CR TKAs we found a statistically significant higher OKS score (3 points, p = 0.04), and a higher but non-significant FJS score (4 points, p = 0.48) for the mobile bearing TKAs.

Conclusions

Patients receiving the new generation CR TKA obtained higher FJS and OKS scores when compared to patients receiving a standard CR TKA, indicating that the use of this newer prosthetic design facilitate less knee awareness and better function after TKA.

Preservation of the PCL when performing cruciate-retaining TKA: Is the tibial tuberosity a reliable predictor of the PCL footprint location?

PURPOSE

Reconstruction of the joint line is crucial in total knee arthroplasty (TKA). A routine height of tibial cut to maintain the natural joint line may compromise the preservation of the PCL. Since the PCL footprint is not accessible prior to tibial osteotomy, it seems beneficial to identify a reliable extraarticular anatomic landmark for predicting the PCL footprint and being visible within standard TKA approach. The fibula head predicts reliably the location of PCL footprint; however, it is not accessible during TKA. The aim of this study now was to analyze whether the tibial tuberosity can serve as a reliable referencing landmark to estimate the PCL footprint height prior to tibial cut.

METHODS

The first consecutive case series included 216 CR TKA. Standing postoperative lateral view radiographs were utilized to measure the vertical distance between tibial tuberosity and tibial osteotomy plane. In the second case series, 223 knee MRIs were consecutively analyzed to measure the vertical distance between tibial tuberosity and PCL footprint. The probability of partial or total PCL removal was calculated for different vertical distances between tibial tuberosity and tibial cutting surface.

RESULTS

The vertical distance between the tibial tuberosity and tibial cut averaged 24.7 ± 4 mm. The average vertical distance from tibial tuberosity to proximal and to distal PCL footprint was found to be 22 ± 4.4 and 16 ± 4.4 mm, respectively. Five knees were considered at 50% risk of an entire PCL removal after CR TKA.

CONCLUSIONS

Current surgical techniques of tibial preparation may result in partial or total PCL damage. Tibial tuberosity is a useful anatomical landmark to locate the PCL footprint and to predict the probability of its detachment pre-, intra-, and postoperatively. This knowledge might be useful to predict and avoid instability, consecutive pain, and dissatisfaction after TKA related to PCL insufficiency.

LEVEL OF EVIDENCE

III.

Fluoroscopic motion study confirming the stability of a medial pivot design total knee arthroplasty

BACKGROUND

The ideal total knee arthroplasty should provide maximum range of motion and functional stability for all desired daily activities. The SAIPH™ (MatOrtho; UK) knee has a medial pivot knee kinematic pattern designed to achieve medial stability and an asymmetric posterior translation of the lateral femoral condyle during knee flexion and in this way attempts to mimic the natural knee motion. This study aims to analyze knee kinematics of the SAIPH™ total knee arthroplasty (TKA) by videofluoroscopy during four different weightbearing activities.

METHODS

Fourteen consecutive patients operated on by a single surgeon, with a minimum follow-up of 24 months were included in this IRB-approved study. There were no exclusions based on patient's functional level. A medially conforming knee was implanted in all cases. Participants in the study were asked to perform the clinically relevant functional activities of pivoting, kneeling, lungeing and step-up/down activities while their knee motion was recorded by videofluoroscopy.

RESULTS

Maximum knee flexion during the kneeling activity mean 127° (100°-155°). An asymmetric posterior translation of the lateral femoral condyle (LFC) was observed during pivoting, kneeling, lungeing and stepping. No paradoxical anterior translation of the femoral condyles was observed in any activity.

CONCLUSION

The kinematics observed in this implant are similar in pattern, although smaller in magnitude, to normal functional knees, showing a posterior translation of the lateral femoral condyle during knee flexion, with internal rotation of the tibia, and no paradoxical anterior motion in any of the four weight bearing activities.

In vivo length change patterns of the medial and lateral collateral ligaments along the flexion path of the knee

PURPOSE

The knowledge of the function of the collateral ligaments-i.e., superficial medial collateral ligament (sMCL), deep medial collateral ligament (dMCL) and lateral collateral ligament (LCL)-in the entire range of knee flexion is important for soft tissue balance during total knee arthroplasty (TKA). The objective of this study was to investigate the length changes of different portions (anterior, middle and posterior) of the sMCL, dMCL and LCL during in vivo weightbearing flexion from full extension to maximal knee flexion.

METHODS

Using a dual fluoroscopic imaging system, eight healthy knees were imaged while performing a lunge from full extension to maximal flexion. The length changes of each portion of the collateral ligaments were measured along the flexion path of the knee.

RESULTS

All anterior portions of the collateral ligaments were shown to have increasing length with flexion except that of the sMCL, which showed a reduction in length at high flexion. The middle portions showed minimal change in lengths except that of the sMCL, which showed a consistent reduction in length with flexion. All posterior portions showed reduction in lengths with flexion.

CONCLUSIONS

These data indicated that every portion of the ligaments may play important roles in knee stability at different knee flexion range. The soft tissue releasing during TKA may need to consider the function of the ligament portions along the entire flexion path including maximum flexion.

LEVEL OF EVIDENCE

III.

Comparison of High-Flexion and Conventional Implants in Total Knee Arthroplasty: A Meta-Analysis

Background

The purpose of this study was to evaluate whether high-flexion prostheses are superior to conventional prostheses after total knee arthroplasty (TKA).

Material/Methods

We searched the PubMed and Embase databases for randomized trials and cohort studies comparing high-flexion with conventional knee implants. The heterogeneity across studies was examined by I² and Cochran’s Q-tests. Then the overall weighted mean differences of range of motion (ROM) and knee functional scores were evaluated.

Results

A total of 16 trials involving 2643 knees met our inclusion criteria. The results revealed that high-flexion implants were superior to conventional implants in the improvement of range of motion (weighted mean difference, 2.92; 95% CI, 1.63–4.22; p<0.0001). The clear advantage of high-flex PS (posterior stabilized) as well as high-flex CR (cruciate retaining) implants was found in ROM when compared to PS implants (2.73; 95% CI, 1.27–4.20; p=0.0003) and CR implants (3.24; 95% CI, 0.28–6.20; p=0.003), respectively. However, there was no difference in Knee Society Scores (0.42; 95% CI, −0.60–1.43; p=0.42), Knee Society function (0.37; 95% CI, −1.48–2.22; p=0.70) and Hospital for Special Surgery scores (0.26; 95% CI, −0.47–1.00; p=0.48) between high-flexion and conventional groups.

Conclusions

The current meta-analysis revealed that high-flexion implants were superior to conventional implants in the improvement of ROM but not in functional outcome scores.

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.

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.

Variations in morphological characteristics of prostheses for total knee arthroplasty leading to kinematic differences

BACKGROUND AND PURPOSE

The aim of this study is to compare kinematics during weight-bearing deep knee-bending motion in patients after bilateral total knee arthroplasty (TKA) of two types: 1) a conventional ScorpioFlex prosthesis and 2) a contemporary redesigned non-restrictive-geometry (NRG) prosthesis installed by the same surgeon.

METHODS

We enrolled 15 patients who underwent conventional ScorpioFlex posterior-stabilised TKA in one knee and contemporary NRG TKA on the contralateral side (the same surgeon). During fluoroscopic examination, each patient performed weight-bearing deep knee bending. Motions among all components were analysed using a two- to three-dimensional registration technique.

RESULTS

The mean maximum flexion was 108° (SD 8) and 120° (SD 9) after ScorpioFlex and NRG TKAs, respectively; there were statistically significant differences between the groups. From extension to maximal flexion, the medial condyle translated by 4.8mm (SD 1.2) and 5.4mm (SD 2.4) posteriorly after ScorpioFlex TKA and NRG TKA, respectively. The lateral femoral condyle moved 8.4mm (SD 1.5) and 12.2mm (SD 2.1) posteriorly after ScorpioFlex TKA and NRG TKA, respectively. There were no significant differences in medial condyle translation between the groups except for the lateral condyle. The total amount of tibial axial rotation during extension to flexion was 5.1° (SD 1.8) after ScorpioFlex and 13.2° (SD 3.4) after NRG TKAs; there were statistically significant differences between the groups.

CONCLUSIONS

NRG resulted in much better maximum flexion, lateral condyle movement and tibial internal rotation than did ScorpioFlex TKAs. The observed kinematic differences are most likely caused by variations in the morphological characteristics of the two implants.

Is range of motion after cruciate-retaining total knee arthroplasty influenced by prosthesis design? A prospective randomized trial

Improvement in knee flexion is a major expectation for many patients undergoing total knee arthroplasty (TKA). One hundred and twenty two patients were randomized to receive a cruciate-retaining standard or high-flexion TKA. Range of motion (ROM) and functional outcomes were assessed. The high flexion implants had a greater intraoperative ROM than standard implants. The mean flexion preoperatively, intraoperatively and at the one year follow-up was 107.4°, 123.0° and 108.9° in the standard group and 109.9°, 129.1° and 109.7° in the high-flexion TKA group. These differences were not significant preoperatively and at follow-up, but intraoperatively (P < 0.001). In multivariate analysis preoperative knee flexion was the only significant factor influencing knee flexion at follow-up. No differences in the Knee Society Score or SF 36 were observed.

Do tibiofemoral contact point and posterior condylar offset influence outcome and range of motion in a mobile-bearing total knee arthroplasty?

PURPOSE

The posterior condylar offset (PCO) and the tibiofemoral contact point (CP) have been reported as important factors that can influence range of motion and clinical outcome after total knee arthroplasty. A mobile-bearing knee implant with an anterior posterior gliding insert would in theory be more sensitive for changes in PCO and CP. For this reason, we analysed the PCO and CP and the relation with outcome and range of motion in 132 patients from a prospectively documented cohort in this type of implant.

METHODS

The prosthesis used was a posterior cruciate retaining AP gliding mobile-bearing total knee replacement (SAL II Sulzer Medica, Switzerland). In 132 knees, the pre- and postoperative PCO and postoperative CP were evaluated. Measurements were made on X-rays of the knee taken in approximately 90° of flexion and with less than 3-mm rotation of the femur condyles. The outcome parameters, range of motion (ROM) and the knee society score (KSS), for each knee were determined preoperatively and at 5-year follow-up.

RESULTS

The mean KSS improved from 91 to 161 at 5-year follow-up (p < 0.001) and the mean ROM from 102 to 108 (p < 0.05). The mean PCO difference (postoperative PCO-preoperative PCO) was--0.05 mm (SD 2.15). The CP was on average 53.9% (SD 5.5%). ROM was different between the 3 PCO groups (p = 0.05): patients with 3 or more mm decrease in PCO had the best postoperative ROM (p = 0.047). There was no statistical difference between the postoperative ROM between patients with a stable PCO and those with an increased PCO. There was no correlation between the difference in PCO and the difference in ROM; R Pearson = -0.056. There was no difference in postoperative ROM or postoperative total KSS between CP <60% and CP >60%: p = 0.22, p = 0.99, for ROM and KSS, respectively. Scatter plots showed uniform clouds of values: increase or decrease in PCO and CP had no significant influence on ROM or KSS.

CONCLUSION

The hypotheses that a stable PCO and a more natural CP increase postoperative ROM and improve clinical outcome could not be confirmed. On the contrary, a decreased PCO seemed to improve knee flexion. Furthermore, a relationship between PCO and CP could not be found.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Does cruciate-retaining total knee arthroplasty enhance knee flexion in Western and East Asian patient populations? A meta-analysis

INTRODUCTION

This study analyzed the published data to examine if CR TKAs can enhance the flexion and functional outcomes of the knee in the Western and East Asian populations using a meta-analysis approach.

MATERIALS AND METHODS

A systematic review of literature published through Medline and EMBASE was conducted. The inclusion criteria were: primary TKA, follow up duration greater than one year, a fixed bearing CR prosthesis, and data for maximum pre- and post-operative flexion along with standard deviations or errors. We estimated the weighted mean differences between pre- and post-operative flexion, extension and knee scores (KSS and HSS) via a random effect model.

RESULTS

Seventeen articles were selected and reviewed among 1229 studies that included 1090 knees of the Western and 516 knees of the East Asian. No significant difference was noted in maximal knee flexion pre- and post-operatively, when all the studies were pooled together (-0.17°, p=0.93, post-operative<pre-operative). The mean difference in flexion was -1.87° (p=0.2) and 2.03° (p=0.17), respectively in the both populations. However, the extension angle was significantly improved by -5.49° and -13.05° (p<0.05), respectively. KSS scores were significantly improved by 46.39 and 51.63, and HSS scores by 36.65 and 30.67 (p<0.05), respectively in the both populations.

CONCLUSION

The meta-analysis indicated that contemporary CR TKAs have not been shown to enhance post-operative flexion capability in the Western and East Asian. The extension angles of the knee and the knee scores were significantly improved in both populations.

Fibula head is a useful landmark to predict the location of posterior cruciate ligament footprint prior to total knee arthroplasty

PURPOSE

The hypothesis of our study is that a routine tibial cut during cruciate retaining TKA may result in a partial or a total removal of the PCL footprint. Therefore providing a reliable landmark is essential to estimate the probability of PCL damage with a tibial cut and to enable the surgeon to decide pre-operatively whether a cruciate retaining implant design is suitable.

METHODS

In a case series of 175 cruciate retaining TKA, the routinely made standing postoperative AP-view radiographs were evaluated to determine the distance between fibula head and tibial cutting plane. In a second case series knee MRI of 223 subjects were consecutively used to measure the vertical distance between tibial attachment of PCL and fibula head. The probability of partial or total PCL damage was calculated for different vertical distances between tibial cut and fibula head.

RESULTS

The vertical distance between the tibial cut and the most proximal point of the fibula head averaged 6.1 mm ±4.8 mm. The mean vertical distance from fibula head to proximal and to distal PCL footprint revealed to be 11.4 mm ±3.7 mm and 5.4 mm ±2.9 mm, respectively. The location of the insertion was not significantly different between subgroups such as age (<50 or >50 years), gender and side. Based on our results 11 (7%) knees were considered at high risk of an entire PCL removal after implantation of a cruciate retaining TKA design.

CONCLUSIONS

Currently available routine tibial preparation techniques result in partial or total posterior cruciate ligament detachment. Fibula head as a landmark aids to predict the PCL location and to estimate its disruption pre- and postoperatively on AP-view radiographs.

Do patients care about higher flexion in total knee arthroplasty? A randomized, controlled, double-blinded trial

Background

Little information exists to support that patients care about flexion beyond what is needed to perform activities of daily living (ADL) after Total knee arthroplasty (TKA). The purpose of this study was to investigate if the achievement of a higher degree of knee flexion after TKA would result in a better patient perceived outcome.

Methods

The study is a randomized, double-blinded, controlled trial in which 36 patients (mean age: 67.2 yrs) undergoing one-stage bilateral TKA randomly received a standard cruciate-retaining (CR) TKA in one knee and a high-flex posterior-stabilized (PS) TKA in the contra lateral knee. At follow-up ROM, satisfaction, pain, “feel” of the knee and the abilities in daily activities were assessed.

Results

At 1-year follow-up we found an expected significantly higher degree of knee flexion of 7° in the high-flex knees (p = 0.001). The high-flex TKA’s showed a mean active flexion of 121°. In both TKA’s the median VAS pain score was 0, the median VAS satisfaction score was 9, and the median VAS score of the patient “feel” of the knee was 9 at 1-year follow-up. Further, there were no significant differences between the knees in the performance of daily activities.

Conclusions

As expected the high-flex TKA showed increased knee flexion, but no significant differences in the patient perceived outcomes were found. This suggests little relevance to the patients of the difference in knee flexion – when flexion is of this magnitude – as pain free ROM and high patient satisfaction were achieved with both TKA’s.

Trial registration

ClinicalTrials.gov: NCT00294528

The Posterior Condylar Offset Ratio

INTRODUCTION

Posterior Condylar Offset is an area of interest in knee arthroplasty research and clinical outcome. The aim of the study is to define a quantifiable Posterior Condylar Offset Ratio, a normal value for this ratio and to confirm its reproducibility on pre-operative radiographs.

METHOD

We propose a new Posterior Condylar Offset Ratio which is defined as the maximal thickness of the posterior condyle projecting posteriorly to a straight line drawn as the extension of the posterior femoral shaft cortex, divided by the maximal thickness of the posterior condyle projecting posterior to a straight line drawn as the extension of the anterior femoral shaft cortex on a true lateral radiograph of the distal quarter of the femur. We have measured this on 100 true lateral radiographs (50 females, 50 males, and mean age 65 years).

RESULTS

The mean ratio was 0.44 (SD 0.02) and was shown to have good reproducibility (intra-observer error 0.899 and inter-observer error 0.882. The ratio was also very consistent between male and female patients (0.44 (SD 0.02) for the males and 0.45 (SD 0.02) for the females). Adjusting the ratio for reported posterior condyle articular cartilage thickness increased the ratio to 0.47 (SD 0.02).

CONCLUSION

We suggest our Posterior Condylar Offset Ratio is a useful tool to aid further research in this area of knee arthroplasty and propose a normal value of 0.44 on radiographs and 0.47 on post-operative knee arthroplasty radiographs.

High-flexion total knee arthroplasty: survivorship and prevalence of osteolysis: results after a minimum of ten years of follow-up

BACKGROUND

We are aware of no information about the mid-term performance of the high-flexion total knee arthroplasty, although early results have been reported. The purpose of this study was to evaluate the mid-term results of high-flexion and conventional knee prostheses.

METHODS

We prospectively compared the results of 100 patients with osteoarthritis who had received a NexGen Legacy Posterior Stabilized (NexGen LPS) prosthesis in one knee and a NexGen Legacy Posterior Stabilized-Flex (NexGen LPS-Flex) prosthesis in the other. Seventy-five patients (150 knees) were women and twenty-five (fifty knees) were men. The mean age was sixty-five years (range, forty-eight to eighty-five years) at the time of the index procedure. The mean duration of follow-up was 10.3 years (range, ten to 10.6 years). The patients were assessed with radiographs, with the rating system of the Knee Society, and with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at three months, one year, and annually thereafter.

RESULTS

Total knee scores, knee function scores, pain scores, WOMAC scores, knee motion, and activity scores did not differ significantly between the two designs of the implants, on the basis of the numbers studied, either preoperatively or at the time of final follow-up. One knee in the NexGen LPS-Flex group was revised because of recurrent infection. No knee in either group had aseptic loosening of the components. The Kaplan-Meier survivorship at ten years postoperatively, with revision defined as the end point, was 100% (95% confidence interval, 94 to 100) for the NexGen LPS prosthesis and 99% (95% confidence interval, 93 to 100) for the NexGen LPS-Flex prosthesis.

CONCLUSIONS

After a minimum duration of follow-up of ten years, there were no significant differences between the two groups with regard to implant survivorship, functional outcome, knee motion, or prevalence of osteolysis.

How much of the PCL is really preserved during the tibial cut?

PURPOSE

There are two different techniques for retaining the posterior cruciate ligament (PCL) in total knee arthroplasty. The attachment of the PCL can be spared during resection of the tibial plateau, so that a small posterior bone block remains. In contrast to this, many surgeons resect the tibial plateau completely and detach a part of the tibial PCL attachment from the resected material. The objective of this study was to determine how big this part is in an anatomical resection of the tibial plateau with 0° and 7° slope and whether it is gender-dependent.

METHODS

Two hundred consecutive patients who had undergone MRI of a knee joint were included. Patients were excluded if they were younger than 18 years or had dysplasia of the knee joint or injuries of the posterior cruciate ligament. The MRIs of 182 knees that fulfilled the inclusion criteria were analysed. For each knee, an anatomical tibial resection with 0° and 7° posterior slope was simulated, and the parts of the tibial PCL attachment that were resected and retained were determined.

RESULTS

Given a measured tibial resection with 0° slope, 45 ± 28% of the tibial PCL attachment was removed in the men, compared with 46 ± 30% in the women (n.s.). Given a resection with 7° slope, 69 ± 24% of the tibial PCL attachment was removed in the men and 67 ± 25% in the women. This corresponded to a complete resection in 19 men (20%) and 16 women (24%).

CONCLUSIONS

Independently of gender, the anatomical resection of the tibia leads to the removal of a considerable part of the tibial PCL attachment, if this is not spared in the form of a bone block during resection. This becomes increasingly relevant with higher posterior slope of the resection plane. In the case of a cruciate-retaining surgical technique, the retention of the posterior tibial cortical bone in the area of attachment of the PCL is therefore strongly recommended.

LEVEL OF EVIDENCE

II.

The Columbus Knee System: 4-Year Results of a New Deep Flexion Design Compared to the NexGen Full Flex Implant

The Columbus knee system is designed as a standard knee implant to allow high flexion without additional bone resection. Between August, 2004 and March, 2010 we performed 109 total knee arthroplasties of the Columbus knee system in 101 consecutive patients suffering from primary arthrosis of the knee. Mean age was 72.4 years in women and 70.3 years in men. Mean followup was 47.3 months. The 4-year results of a group of patients who received the NexGen Full Flex implant operated by the same surgeon were used for comparison. Mean total knee score was Columbus: 175.6 and NexGen Flex: 183.4; P = 0.037. Mean operation time was 53 min for Columbus and 66 min for NexGen Flex; P < 0.001. With new streamlined instruments operative time became 60 min for the Columbus; P > 0.05. Radiological assessment showed no signs of loosening for both groups. Therefore, the Columbus knee system can be recommended for flexion angles up to 140°.

Comparison of outcomes after bilateral simultaneous total knee arthroplasty using gender-specific and unisex knees

The clinical and radiologic results of a gender-specific total knee arthroplasty design were compared with those of a conventional unisex design in 50 female patients with bilateral osteoarthritis and a minimum follow-up of 2 years. Total knee arthroplasty was performed using a conventional unisex implant in one knee and a gender-specific implant in the other. Clinical outcomes, which included range of motion, Hospital for Special Surgery scores, and Western Ontario and McMaster Universities Osteoarthritis Index scores, were compared. In addition, patients' subjectively preferred sides were noted, and radiologic results based on implant positions, posterior offsets, anterior offsets, and patellofemoral alignments were evaluated. No significant differences were observed between range of motion, Hospital for Special Surgery score, or Western Ontario and McMaster Universities Osteoarthritis Index scores. Patient subjective preferences and radiologic results were also similar for both sides. In conclusion, gender-specific knees in female total knee patients showed no advantages over standard unisex knees in terms of clinical or radiologic outcomes.

Can a high-flexion total knee arthroplasty relieve pain and restore function without premature failure?

BACKGROUND

High-flexion TKA prostheses are designed to improve flexion and clinical outcomes. Increased knee flexion can increase implant loads and fixation stresses, creating concerns of premature failure. Whether these goals can be achieved without premature failures is unclear.

QUESTIONS/PURPOSES

We assessed pain relief, knee motion, function, incidence of premature failure, and radiographic appearance in patients with a mobile-bearing high-flexion TKA and determined whether preoperative knee flexion affects postoperative knee flexion.

PATIENTS AND METHODS

We prospectively followed all 142 patients implanted with 154 mobile-bearing high-flexion TKAs between 2004 and 2007. We obtained Knee Society scores (KSS) and assessed radiographs for loosening. Minimum followup was 24 months (mean, 46 months; range, 24-79 months).

RESULTS

Average knee flexion improved from 123° to 129°. Patients with preoperative flexion of 100° to 120° had a greater postoperative flexion increase (mean, 13°; range, 114°-126°) than patients with preoperative flexion of greater than 120° (mean, 3.0°; range, 128°-131°). The mean KSS improved from 41 to 95 postoperatively. Patients with preoperative flexion of less than 120° had a greater improvement in KSS (62 versus 48). Posterior femoral radiolucent lines were observed in 43% without evidence of prosthetic loosening.

CONCLUSIONS

Our data were similar to those reported in patients implanted with traditional and other designs of high-flexion TKA. We found no increased incidence of premature failure, although a higher than expected incidence of posterior femoral radiolucent lines merit continued observation. Patients with less preoperative motion were more likely to benefit from a high-flexion TKA.

High-flexion vs conventional prostheses total knee arthroplasty: a meta-analysis

Whether high-flexion prostheses are superior to conventional prostheses after total knee arthroplasty (TKA) remains controversial. Therefore, this meta-analysis was conducted to evaluate the effects of these 2 different designs. After a comprehensive search, 11 trials with 1204 knees were eligible for data extraction and pooled analysis. The results demonstrated that there were no differences in range of motion of high-flexion posterior-stabilized vs standard posterior-stabilized TKA (weighted mean improvement, 0.93°; 95% confidence intervals, -0.75° to 2.60°; P = .28), range of motion of high-flexion cruciate-retaining vs cruciate-retaining TKA (2.06°; 0.06°-4.17°; P = .06), weight-bearing flexion (2.05°; 0.99°-5.08°; P = .19), Knee Society Scores (1.59 points; 0.42-3.60 points; P = .12), and Hospital for Special Surgery Scores (0.84 points; 0.37-2.04 points; P = .17) with at least 1-year follow-up. No infection, loosening, and osteolysis were found. The current evidences cannot confirm that high-flexion prostheses are superior to conventional prostheses.

In vivo knee kinematics in patients with bilateral total knee arthroplasty of 2 designs

Many younger and highly active patients desire to achieve high flexion after total knee arthroplasty. This study's purpose was to determine if a contemporary total knee arthroplasty design improved functional knee flexion compared with a traditional total knee arthroplasty in patients living a Western lifestyle. Ten patients with bilateral total knee arthroplasty of 2 types were studied during weight-bearing lunge, kneeling, and stair activities using fluoroscopic imaging. There were no differences in maximum knee flexion during lunging or kneeling. Statistically significant differences in tibial rotation and condylar translation were observed during the 3 activities. Although several joint kinematic differences were observed, no important functional differences were observed in clinically excellent, high performing subjects with bilateral total knee arthroplasty of 2 types.

High-flexion total knee arthroplasty improves flexion of stiff knees

PURPOSE

High-flexion knee prosthesis designs are generally thought to be of benefit only in patients with a satisfactory preoperative flexion angle. The aim of the study was to evaluate whether high-flexion designs were indeed worthless in osteoarthritis patients with severe preoperative flexion limitation.

METHODS

The postoperative maximum flexion was compared in osteoarthritis patients with a preoperative maximum flexion of 100° or less, using LPS and LPS-flex implants (NexGen®; Zimmer, Warsaw, IN) in total knee arthroplasties. Data on 39 knees in the LPS group and 41 in the LPS-flex group, with a minimum of 2 years of follow-up, were reviewed retrospectively, focused on the postoperative maximum flexion.

RESULTS

Two years after operation, the LPS-flex group had a mean postoperative maximum flexion of 131±10° (range, 105-140°), which was significantly higher than the 121±12° (range, 95-140°) in the LPS group (P<0.001). In the LPS-flex group, about half of the knees (n=18, 44%) could achieve a maximum flexion of 140° postoperatively, but in the LPS group only five knees (13%) achieved a maximum flexion of 140°.

CONCLUSION

Despite a different period of the operation between groups, this study suggested that osteoarthritis patients with severe preoperative flexion limitation could achieve more postoperative gain in flexion when a high-flexion prosthesis was used, compared to the flexion obtained using a standard prosthesis.

Current surgical treatment of knee osteoarthritis

Osteoathritis (OA) of the knee is common, and the chances of suffering from OA increase with age. Its treatment should be initially nonoperative-and requires both pharmacological and nonpharmacological treatment modalities. If conservative therapy fails, surgery should be considered. Surgical treatments for knee OA include arthroscopy, cartilage repair, osteotomy, and knee arthroplasty. Determining which of these procedures is most appropriate depends on several factors, including the location, stage of OA, comorbidities on the one side and patients suffering on the other side. Arthroscopic lavage and débridement is often carried out, but does not alter disease progression. If OA is limited to one compartment, unicompartmental knee arthroplasty or unloading osteotomy can be considered. They are recommended in young and active patients in regard to the risks and limited durability of total knee replacement. Total arthroplasty of the knee is a common and safe method in the elderly patients with advanced knee OA. This paper summarizes current surgical treatment strategies for knee OA, with a focus on the latest developments, indications and level of evidence.

Can high-flexion tibial inserts improve range of motion after posterior cruciate-retaining total knee arthroplasty?

Interest in high-flexion total knee arthroplasty (TKA) prostheses designed to provide better postoperative range of motion (ROM) is widespread. We sought to determine whether changes in surface geometry of the tibial polyethylene insert could improve postoperative ROM in a consecutive series of patients undergoing TKA with retention of the posterior cruciate ligament (PCL). Two cohorts with Smith & Nephew (Memphis, Tennessee) Posterior Cruciate-Retaining Genesis II total knee prostheses were compared, 79 knees (65 patients) using standard tibial inserts and 85 knees (72 patients) using high-flexion inserts. The standard insert has a slightly raised posterior lip, whereas the high-flexion insert is recessed downward at the posterior margin to facilitate femoral rollback in flexion and eliminate impingement of the femoral component on the back of the polyethylene during rollback. Mean ROM 1 year postoperatively was 112.0° in patients receiving the standard insert and 119.3° in patients receiving the high-flexion insert. Preoperative ROM was similar in both groups. Flexion improvement in the high-flexion group over the standard insert group was statistically significant (P<.001). Final Knee Society Scores did not differ amongst patients receiving the standard and high-flexion inserts. Our study demonstrates that improved postoperative flexion can be achieved without changing surgical technique, bony cuts, or metallic prosthetic parts. This is the first report that we are aware of that documents improvement in ROM after PCL-retaining TKA through the use of high-flexion inserts.

Comparison of a standard and a gender-specific posterior cruciate-substituting high-flexion knee prosthesis: a prospective, randomized, short-term outcome study

BACKGROUND

Recently, much debate has focused on the effect of gender-specific total knee arthroplasty. The purpose of the present study was to compare clinical and radiographic results as well as femoral component fit in patients receiving either a standard posterior cruciate-substituting LPS-Flex or gender-specific posterior cruciate-substituting LPS-Flex total knee prosthesis.

METHODS

Sequential simultaneous bilateral total knee arthroplasty was performed for eighty-five patients (170 knees). Eighty-five women (mean age, 69.7 years) received a standard LPS-Flex prosthesis in one knee and a gender-specific LPS-Flex prosthesis in the contralateral knee. The mean duration of follow-up was 2.13 years. At each follow-up, the Knee Society score, the Hospital for Special Surgery knee score, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score, and radiographs were evaluated. The aspect ratio of the distal part of the femur was compared with those of the standard LPS-Flex prosthesis and the gender-specific LPS-Flex prosthesis.

RESULTS

The mean postoperative Knee Society scores (95.5 points in the standard implant group, compared with 96.5 points in the gender-specific implant group) and Hospital for Special Surgery knee scores (90.7 points in the standard implant group, compared with 91.2 points in the gender-specific implant group) were similar in both groups. The mean postoperative WOMAC score was 36.6 points. Postoperatively, the mean ranges of knee motion in the supine position (125 degrees in the standard implant group, compared with 126 degrees in the gender-specific implant group), patient satisfaction (8.3 points in the standard implant group, compared with 8.1 points in the gender-specific implant group), and radiographic results were similar in both groups. The femoral component in the standard implant group fit significantly better than that in the gender-specific implant group (p < 0.0001).

CONCLUSIONS

The present study did not show any clinical benefits of a gender-specific LPS-Flex total knee prosthesis at the time of short-term follow-up. Longer follow-up is needed to determine whether there will be an advantage in terms of longer-term function.

LEVEL OF EVIDENCE

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

The Bi-Surface total knee arthroplasty: minimum 10-year follow-up study

The Bi-Surface Knee System (Japan Medical Material, Kyoto, Japan), which has a unique ball-and-socket joint and whose femoral component is made from alumina ceramic, was designed to improve deep knee flexion and long-term durability after total knee arthroplasty. The purpose of this study was to review the clinical results of a minimum 10-year follow-up. Between 1989 and 1997, 507 total knee arthroplasties were carried out in 371 patients. Forty three patients (56 knees) were lost to follow-up. The mean age of the patients at operation was 68.5 years, and the patients were followed up for a mean of 11.7 years. The knees were evaluated on the basis of Knee Society knee score and functional score, radiographs, and Kaplan-Meier survivorship analysis. The knee score was improved from 38.9+/-17.4 points preoperatively to 93.3+/-7.8 points at the latest follow-up (p<0.001). The functional score was improved from 34.9+/-19.3 points to 52.7+/-24.1 points (p<0.001). The mean range of flexion was improved from 118.7+/-21.7 degrees to 124.2+/-20.8 degrees (p<0.001). The critical angle, which means the border to gain more range of flexion postoperatively, was 130.1 degrees. Kaplan-Meier survivorship at 10-year was 95.9% with any operation or radiographic failure as the end point. The corresponding rate was 97.4% with revision of any component as the end point. No ceramic component fracture occurred. The present study demonstrates that good range of flexion was maintained for a long time after total knee arthroplasty with excellent durability. The Bi-Surface Knee System appears to have achieved its design objectives.