Posterior cruciate substituting versus posterior cruciate retaining total knee arthroplasty prostheses: a meta-analysis

Comparison of clinical outcomes between total hip replacement and total knee replacement

BACKGROUND

Total hip replacements (THR) and total knee replacements (TKR) are effective treatments for severe osteoarthritis (OA). Some studies suggest clinical outcomes following THR are superior to TKR, the reason for which remains unknown. This study compares clinical outcomes between THR and TKR.

AIM

To compare the clinic outcomes of THR anad TKR using a comprehensive range of patient reported outcome measures (PROMs).

METHODS

A prospective longitudinal observational study of patients with OA undergoing THR and TKR were evaluated using a comprehensive range of generic and joint specific PROMs pre- and post-operatively.

RESULTS

A total of 131 patients were included in the study which comprised the THR group (68 patients) and the TKR group (63 patients). Both groups demonstrated significant post-operative improvements in all PROM scores (P < 0.001). There were no significant differences in post-operative PROM scores between the two groups: Hip and Knee Osteoarthritis Outcome scores (P = 0.140), Western Ontario and McMaster Universities Osteoarthritis Index pain (P = 0.297) stiffness (P = 0.309) and function (P = 0.945), Oxford Hip and Knee Score (P = 0.076), EuroQol-5D index (P = 0.386) and Short-Form 12-item survey physical component score (P = 0.106). Subgroup analyses showed no significant difference (P > 0.05) between cruciate retaining and posterior stabilised prostheses in the TKR group and no significant difference (P > 0.05) between cemented and uncemented fixation in the THR group. Obese patients had poorer outcomes following TKR but did not significantly influence the outcome following THR.

CONCLUSION

Contrary to some literature, THR and TKR are equally efficacious in alleviating the pain and disability of OA when assessed using a comprehensive range of PROMs. The varying knee prosthesis types and hip fixation techniques did not significantly influence clinical outcome. Obesity had a greater influence on the outcome following TKR than that of THR.

Cruciate-Retaining Total Knee Arthroplasty: Current Concepts Review

Posterior cruciate-retaining (CR) total knee arthroplasty for osteoarthritis of the knee is a popular implant choice. At present, there is no consensus on whether sacrifice or retention of the posterior cruciate ligament (PCL) offers superior outcomes. This review explores the current literature available on CR total knee arthroplasty (TKA). PubMed was searched by keyword to find relevant articles for inclusion. Additional sources came from article references and joint registry reports. CR design knees have distinct kinematic gait patterns from posterior-stabilizing (PS) knees and exhibit paradoxical anterior femoral movement with less femoral rollback. While CR implants offer less flexion than PS designs, the difference is not clinically detectable as clinical scores are similar in the short and long term. CR implants have better long-term survival compared to PS knees, likely due to lower risk of aseptic loosening. CR total knee arthroplasties also have shorter operating times and lower risk of peri-prosthetic fractures. Because the CR implant is unconstrained, there may be an increased risk of instability compared to PS designs, but the literature is mixed. Overall, the current literature supports the continued use of CR TKAs due to their lower risk of complications, durability, and demonstrated equivalence in function to posterior-substituting models.

Posterior-Stabilized Versus Cruciate-Retaining Prostheses for Total Knee Arthroplasty: An Overview of Systematic Reviews and Risk of Bias Considerations

Background

Numerous systematic reviews have been published comparing the outcomes of patients undergoing posterior stabilized (PS) versus cruciate-retaining (CR) procedures in total knee arthroplasty (TKA), but with some overlaps and contradictions. The objectives of this study were (1) to perform an overview of current systematic reviews comparing PS versus CR in TKA, by evaluating their methodological quality and risk of bias, and (2) to provide recommendations through the best evidence.

Methods

A systematic search of systematic reviews comparing PS and CR in TKA, published until June 2021 was conducted using the MEDLINE, EMBASE, and Cochrane Library databases. Included systematic reviews were assessed for methodological quality and risk of bias by the AMSTAR2 instrument and ROBIS tool, respectively. The choice of best evidence was conducted according to the Jadad decision algorithm.

Results

A total of eight systematic reviews were eligible for inclusion in this study. The Jadad decision algorithm suggested that reviews with the highest AMSTAR2 scores should be selected. According to the ROBIS tool, there were three reviews with a low risk of bias and five with a high risk of bias. Consequently, one systematic review conducted by Verra et al. with the highest AMSTAR2 score and low risk of bias was selected as the best evidence.

Conclusions

Although current systematic reviews demonstrated some statistical differences in clinical presentation and functional outcomes between PS and CR, the current outcome indicators cannot be taken to provide recommendations for undergoing PS or CR. The decision for prosthesis selection could be made mostly based on the surgeon's preference, indications and other indicators.

Does posterior cruciate ligament sacrifice influence dynamic balance after total knee arthroplasty? Comparison of cruciate-retaining and cruciate-substituting designs in bilaterally operated patients

PURPOSE

This study aimed to evaluate whether the posterior cruciate ligament sacrifice during total knee arthroplasty (TKA) has any effect on postoperative standing balance or not.

METHODS

The patients who underwent bilateral TKA with either CR or PS design were analyzed. 30 patients (10 PS, 20 CR) were included for the final analysis. TKA designs were compared in terms of Lysholm score, range of motion, and balance characteristics including somatosensorial, vestibular, and visual balance scales, adaptation, limits of stability, and weight-bearing/squat tests by computerized dynamic posturography.

RESULTS

The mean follow-up time was 59 months for CR, 49 months for PS group. The average Lysholm score values were 94 for CR and 95 for PS group, indicating functionally similar patient groups. The average knee flexion was found significantly higher in PS group (114°) compared to CR group (102°) (p = 0.009). In the CR group, motor adaptation tests (toes up/toes down) were found to be better (p = 0.034). In the on-axis velocity parameter (linear goal orientation) of limits of stability test, PS group patients were found to be more successful (p = 0.035).

CONCLUSIONS

The use of CR implants can be recommended in patients with a high risk of falling since they provide better motor adaptation providing rapid reactions to rapid surface changes. Better linear goal orientation in PS group, providing a faster movement in an intended direction, should be considered when planning the ideal implant for the patients with relevant activities.

Tibiofemoral subluxation in the coronal plane does not affect WOMAC and KOOS after total knee arthroplasty

PURPOSE

To investigate the effect of preoperative coronal tibiofemoral subluxation (CTFS) on functional outcome, prosthesis type, insert thickness and revision rates in patients who underwent total knee arthroplasty (TKA).

METHODS

A total of 224 knees of 186 patients were included. Patients were divided into two groups as either with (Group 1, 114 knees of 86 patients) or without (Group 2, 124 knees of 100 patients) coronal lateral tibiofemoral subluxation. The mean follow-up period was 71.3 ± 7.3 (range 60-84) months in group 1 and 69.4 ± 6.6 (range 61-79) months in group 2 (n.s.). Coronal tibiofemoral subluxation degree was measured in degrees on standing anteroposterior knee radiographs. Group 1 was divided into three subgroups according to amount of subluxation (< 5 mm, 6-10 mm and > 10 mm). Functional outcome was evaluated using the Western Ontario and McMaster Osteoarthritis Index (WOMAC) score and Knee Injury and Osteoarthritis Outcome Score (KOOS) preoperatively and at the last follow-up visit. Prosthesis type, insert thickness and revision rates were compared between the two groups.

RESULTS

There were no significant differences between the two groups regarding patient demographics, prosthesis type, and revision rates (n.s.). The insert thickness was found significantly higher in group 1 (p < 0.001). The preoperative and postoperative WOMAC and KOOS scores were found no significantly different between the two groups (n.s.). Among subluxation (+) subgroups, there was no significant difference in functional outcome scores and revision rates (n.s.). However, prosthesis type and insert thickness were significantly associated with the amount of subluxation (p = 0.009 and p = 0.001, respectively). There was no significant correlation between the degree of lower extremity deformity and coronal tibiofemoral amount of subluxation (n.s.).

CONCLUSION

Preoperative CTFS does not adversely affect the WOMAC score, KOOS and revision rates after TKA. In the clinical practice, surgeons should be aware of the need for a posterior cruciate stabilizing prosthesis and a thicker insert in the presence of CTFS, especially with subluxation greater than 10 mm and to consider a spared bony resection on the tibia in patients suffering from CTFS.

LEVEL OF EVIDENCE

IV.

Does contralateral knee range of motion predict postoperative knee range of motion after total knee arthroplasty?

Purpose

The aim of this study was to determine if contralateral knee range of motion is associated with postoperative range of motion in the operative knee after total knee arthroplasty.

Methods

Contralateral (nonoperative) knee range of motion was compared to postoperative knee range of motion after total knee arthroplasty using linear regression models in 59 patients who had undergone primary total knee arthroplasty with a minimum of 4 months postoperative follow-up data (range 4–13 months).

Results

A strong linear relationship was observed between contralateral knee ranges of motion of 115° or greater and postoperative knee ranges of motion after total knee arthroplasty (slope 0.93, 95% CI 0.58–1.29, P < 0.0001), with a mean difference of −7.44° (95% CI −10.3 to −4.63, P < 0.0001). However, there was no association between contralateral knee range of motion and postoperative knee range of motion when contralateral knee range of motion was less than 115°.

Conclusion

Contralateral knee range of motion of 115° or greater correlates linearly with postoperative range of motion after total knee arthroplasty, and thus may be predictive in such cases.

Comparison of Contact Kinematics in Posterior-Stabilized and Cruciate-Retaining Total Knee Arthroplasty at Long-Term Follow-Up

BACKGROUND

There is controversy regarding the superiority of posterior-stabilizing (PS) total knee arthroplasty (TKA) and cruciate-retaining (CR) TKA. Substantial work has made comparisons between PS and CR TKA at follow-ups of less than 5 years. It was the goal of the present study to compare the kinematics at greater than 5 years postoperatively between CR and PS TKA, with a secondary goal of comparing patient function.

METHODS

A total of 42 knees were investigated, with equal representation in the PS and CR TKA groups. Patients underwent radiostereometric analysis imaging at 0°, 20°, 40°, 60° 80°, and 100° of flexion. Contact position, magnitude of excursion, and condylar separation on each condyle were measured. A Timed-Up-and-Go functional test was also performed by patients, with the total test time being measured. Preoperative and postoperative clinical outcome scores were also collected.

RESULTS

There were differences in contact position on both the medial and lateral condyles at multiple angles of flexion (P < .05). There was no difference (P = .89) in medial excursion; however, PS TKA had greater lateral excursion than CR TKA (P < .01). No difference (P > .99) was found in frequency of condylar separation. PS TKA was associated with faster (P = .03) total Timed-Up-and-Go test times. There were no differences in clinical outcome scores between the groups preoperatively or postoperatively.

CONCLUSION

We found kinematic and functional differences that favor PS TKA. Our results suggest posterior cruciate ligament insufficiency in CR TKA, indicating that perhaps the cam/post systems in PS TKA better maintain knee kinematics and function long term.

Posterior-stabilized versus cruciate-retained implants for total knee arthroplasty: a meta-analysis of clinical trials

AIM

A meta-analysis comparing the outcomes of patients undergoing cruciate retaining (CR) versus posterior stabilized (PS) in primary total knee arthroplasty was performed. The outcomes of interest were the Knee Society Rating System, clinical (KSCS) and functional (KSFS) subscales, joint range of motion (ROM), surgical duration and further complications (anterior knee pain, instability and revision rate).

MATERIALS AND METHODS

The search was conducted in July 2018, accessing the following databases: Cochrane Systematic Reviews, Scopus, PubMed, EMBASE, CINAHL, AMED and Google Scholar. We included only clinical trials level of evidence I and II. During the statistical analysis, we excluded all the studies that affect negatively the I² test, in order to achieve more reliable results. For the methodological quality assessment we referred to the PEDro score. The risk of publication's bias was evaluated by the funnel plots across all the comparisons.

RESULTS

The PEDro score reported a good methodological quality assessment. The funnel plot detected a very low risk of publication's bias. We included in this study 36 articles, counting a total of 4052 patients and 4884 procedures. The mean follow-up term for both groups was 3.39 years. The ROM resulted in an overall estimate effect of 2.18° in favor of the PS group. The overall WOMAC showed a result in favor of the PS group. The overall estimate effect of the KSCS was 0.02% higher in the CR group. The KSFS showed an overall estimate effect of 2.09% in favor of the PS group. Concerning the surgical duration, the estimate effect resulted in 6.87 min shorter in the CR group. No differences were reported across the two groups regarding anterior knee pain, knee joint instability or revision rate.

CONCLUSION

Both the prosthetic implants provided to be a safety and feasible solution to treat end-stage knee joint degeneration. The PS implants reported improvements in the knee range of motion and a prolongation of the surgical time. No clinically relevant dissimilarities concerning the analyzed scores were evidenced. No statistically significant relevant differences in complications were detected.

Cruciate-Retaining vs Posterior-Stabilized Primary Total Arthroplasty. Clinical Outcome Comparison With a Minimum Follow-Up of 10 Years

BACKGROUND

Controversy continues regarding whether the posterior cruciate ligament should be retained or removed during total knee arthroplasty (TKA) procedure. The objective was to compare the clinical outcomes with a minimum follow-up of 10 years between patients who received contemporary cruciate-retaining or posterior-stabilized primary TKA.

METHODS

Case-control study of 268 patients who underwent cruciate-retaining TKA vs 211 to posterior-stabilized design, with the same arthroplasty system, and a minimum follow-up of 10 years. Clinical assessment was performed by Knee Society scores, Western Ontario and MacMasters Universities and Short-Form 12 questionnaires, range of motion, and patient satisfaction.

RESULTS

Successful outcomes were found for both designs. No significant differences in functional scores, range of motion, patient-related scores, or patient satisfaction. Between the 5-year and last postoperative follow-up, there were a significant decrease of all clinical scores in both groups. In addition, complication rate and implant survival were similar between groups.

CONCLUSION

The superiority of one design over the other was not found. Both designs can be used expecting long-term successful outcomes and high survival. The choice of the design depended on the status of the posterior cruciate ligament and surgeon preference.

Prospective Randomized Comparison of Posterior-Stabilized Versus Condylar-Stabilized Total Knee Arthroplasty: Final Report of a Five-Year Study

BACKGROUND

This report presents the minimum 5-year results of a prospective, randomized, Level of Evidence I study that evaluated cruciate-sacrificing total knee arthroplasty using either a posterior-stabilized (PS) device or a condylar-stabilized (CS) device. We hypothesized that the clinical outcomes of both groups would be equivalent and that there would be differences in operative time and/or blood loss parameters.

METHODS

One-hundred eleven patients undergoing total knee arthroplasty were randomized to receive either a post-cam style tibial insert (PS, n = 56) or a more congruent anterior-lipped tibial insert (CS, n = 55). All posterior cruciate ligaments were sacrificed.

RESULTS

Comparison of the clinical scores and radiographic results between both groups were essentially equivalent with no statistically significant differences at the final 5-year evaluation, although the CS knee group had significantly fewer incidences of postoperative mechanical sensations (P = .01).

CONCLUSION

These results demonstrate that the CS knee provides excellent clinical, functional, and radiographic outcomes that are comparable to the results achieved with the PS knee, with a lower incidence of mechanical sensations, and support the use of a CS device as an alternative to the PS device.

A Randomized Clinical Trial Comparing Posterior Cruciate-Stabilizing vs Posterior Cruciate-Retaining Prostheses in Primary Total Knee Arthroplasty: 10-Year Follow-Up

BACKGROUND

This 10-year follow-up compares health-related quality of life (HRQL) and reoperations in 100 subjects who were randomized to receive posterior cruciate ligament substituting (PS) or posterior cruciate ligament retaining (CR) total knee arthroplasty. We previously reported 2-year results.

METHODS

Subjects were enrolled preoperatively and randomized at surgery. Subjects completed HRQL questionnaires at all evaluation points. Subjects were re-evaluated at 2 and 10 years with reoperations determined through regional medical record review and patient report.

RESULTS

Over 10 years, 25 (25%) subjects died, 2 subjects were revised and withdrew, and 11 (11%) subjects were lost to follow-up. Of survivors, 62 of 75 (83%) were evaluated at 10 years. Twenty-eight (37%) subjects provided HRQL, radiographic, and reoperation status, 28 (37%) subjects completed HRQL evaluations and reoperation status only, and 6 (8%) subjects provided radiographic and reoperation follow-up. Both groups retained good HRQL between 2 and 10 years with no group differences noted (P > .35). One revision (CR subject), secondary to deep joint infection, occurred within 2 years with 1 further revision (PS subject) occurring at 3 years postoperatively. One subject (PS subject) required manipulation under anesthesia within 3 months of surgery. Four subjects required late patellar resurfacing (1 CR subject, 3 PS subjects) but were retained in the 10-year evaluation. Overall, reoperations were not significantly different between groups (P = .26).

CONCLUSION

Over 10 years postoperatively, both the PS and CR total knee arthroplasty performed well with subjects reporting acceptable levels of HRQL up to 10 years postoperatively; low levels of revision or reoperation were reported in both groups.

Posterior cruciate-substituting total knee replacement recovers the flexion arc faster in the early postoperative period in knees with high varus deformity: a prospective randomized study

INTRODUCTION

Posterior cruciate retention (CR) and substitution (PS) has been controversial in knee replacement surgery. Satisfactory medium and long-term results have been reported in knees with and without deformity but there are limited studies about early functional comparison in terms of recovery of flexion arc, stair activity, walking ability and straight leg raising, especially, in early postoperative period in knees with deformity. Therefore, we aimed to compare the flexion arc in CR and PS knees in postoperative first year including early postoperative days prospectively.

METHODS

Consecutive patients with a deformity of >10° were included and allocated to CR and PS groups randomly. KSS and Feller-patella scores were recorded both preoperatively and postoperatively (1st, 2nd, 3rd and 12th months). Flexion and extension were measured both preoperatively and postoperatively (1st, 2nd, 3rd day and discharge day as well as 1st, 2nd, 3rd and 12th months). Visual analog scale (VAS) was recorded postoperatively at the 1st, 2nd, 3rd and discharge day and at 1st, 2nd, 3rd and 12th months. The walking ability, stair activity and straight leg raising were recorded. Patients were also examined at the last visit with minimum 7-year follow-up with KSS, Feller-patella and VAS scores. Their mean flexion arcs were measured and recorded.

RESULTS

There were 61 TKR evaluated. KSS knee and function scores at the 3rd month and KSS Knee Score at 1st year were superior in PS knees (p = 0.029, p = 0.046, p = 0.026). Flexion arc was found larger on day 1, 2, 3 and discharge day, and at 1st, 2nd, 3rd and 12th month in PS group (p = 0.048, p = 0.002, p = 0.027, p = 0.043, p = 0.014, p = 0.003, p = 0.002, p = 0.018). Walking and stair activity showed no difference but straight leg raising was better in CR knees (p = 0.02). Mean flexion arc was larger in PS knees at the last visit after 7 years (119.0° ± 7.5° in PS and 113.8° ± 8.7° in CR, p = 0.02). There was no revision required in that time interval. The other parameters were similar between groups.

CONCLUSIONS

PS knees gained active flexion arc faster and larger. But straight leg raising activity recovered early in CR knees. Both types of prosthesis produced satisfactory outcome. PS and CR TKRs can be performed with the same performance in osteoarthritic knees even with high varus deformity.

LEVEL OF EVIDENCE

Prospective Randomized Controlled Trial, Level II.

Posterior Cruciate Ligament Retention versus Posterior Stabilization for Total Knee Arthroplasty: A Meta-Analysis

Introduction

Although being debated for many years, the superiority of posterior cruciate-retaining (CR) total knee arthroplasty (TKA) and posterior-stabilized (PS) TKA remains controversial. We compare the knee scores, post-operative knee range of motion (ROM), radiological outcomes about knee kinematic and complications between CR TKA and PS TKA.

Methods

Literature published up to August 2015 was searched in PubMed, Embase and Cochrane databases, and meta-analysis was performed using the software, Review Manager version 5.3.

Results

Totally 14 random control trials (RCTs) on this topic were included for the analysis, which showed that PS and CR TKA had no significant difference in Knee Society knee Score (KSS), pain score (KSPS), Hospital for Special Surgery score (HSS), kinematic characteristics including postoperative component alignment, tibial posterior slope and joint line, and complication rate. However, PS TKA is superior to CR TKA regarding post-operative knee range of motion (ROM) [Random Effect model (RE), Mean Difference (MD) = -7.07, 95% Confidential Interval (CI) -10.50 to -3.65, p<0.0001], improvement of ROM (Fixed Effect model (FE), MD = -5.66, 95% CI -10.79 to -0.53, p = 0.03) and femoral-tibial angle [FE, MD = 0.85, 95% CI 0.46 to 1.25, p<0.0001].

Conclusions

There are no clinically relevant differences between CR and PS TKA in terms of clinical, functional, radiological outcome, and complications, while PS TKA is superior to CR TKA in respects of ROM, while whether this superiority matters or not in clinical practice still needs further investigation and longer follow-up.

Retrospective comparative study shows no significant difference in postural stability between cruciate-retaining (CR) and cruciate-substituting (PS) total knee implant systems

PURPOSE

Modified postural stability after retaining the posterior cruciate ligament (PCL) in total knee arthroplasty is still discussed controversially. The objective of this study was to evaluate whether a PCL-retaining implant design should be preferred over a PCL-substituting implant design regarding postural stability in one-leg stance and clinical outcome.

METHODS

Forty patients underwent total knee arthroplasty, 20 of them with a cruciate-retaining (CR) and 20 of them with a cruciate-substituting (PS) implant system. Postural stability was analysed 6 months postoperatively in one-leg stance using the Biodex Balance System. In addition, the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Knee Society Score were completed.

RESULTS

This study shows that there is no significant difference in postural stability between CR and PS) implant systems with PS implants showing better results in WOMAC score.

CONCLUSIONS

In case it is necessary to use a PS implant, no negative influence on postural stability is to be expected compared to a CR implant.

Cruciate retaining versus posterior stabilized total knee arthroplasty after previous high tibial osteotomy

PURPOSE

This study aimed to investigate the clinical outcome of total knee arthroplasty (TKA) after previous high tibial osteotomy (HTO) using cruciate retaining (CR) versus posterior stabilized (PS) prostheses.

METHODS

Between 2001 and 2010, 133 patients who underwent TKA after previous HTO were included in this study and prospectively followed up for two years. Two independent assessors recorded the range of motion of the operated knee, anterior-posterior (AP) laxity, medial-lateral (ML) laxity, Oxford Knee Score (OKS), Knee Society Function Score (KSFS) and Knee Society Knee Score (KSKS).

RESULTS

Thirty-three patients received CR prostheses, while 100 patients received PS prostheses. The median (inter-quartile range) knee flexion at 6 months and 2 years post-TKA was 101° (90, 116) and 110° (90, 118), respectively for the CR group, compared to 115° (100, 121) and 118° (108, 125) for the PS group (p = 0.010 and p = 0.009, respectively). AP and ML laxities were comparable in both groups of patients. While both groups of patients showed improvement in OKS, KSFS and KSKS at 6 months and 2 years post-TKA, there was no significant difference in these clinical scores between the two groups at both time points of follow-up. None of the 133 patients required revision surgery.

CONCLUSIONS

Although PS prostheses offer better knee flexion in TKA after previous HTO, the knee stability, clinical scores and revision rate at 6 months and 2 years post-TKA are comparable between CR and PS prostheses. The authors conclude that CR is an alternative to PS prostheses in patients undergoing TKA after previous HTO.

LEVEL OF EVIDENCE

III.

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.

Does cruciate retention primary total knee arthroplasty affect proprioception, strength and clinical outcome?

PURPOSE

It remains unclear what the contribution of the PCL is in total knee arthroplasty (TKA). The goal of this study was to investigate the influence of the PCL in TKA in relationship to clinical outcome, strength and proprioception.

METHODS

Two arthroplasty designs were compared: a posterior cruciate-substituting (PS) and a posterior cruciate-retaining (CR) TKA. A retrospective analysis was performed of 27 CR and 18 PS implants with a minimum of 1 year in vivo. Both groups were compared in terms of clinical outcome (range of motion, visual analogue scale for pain, Hospital for Special Surgery Knee Scoring system, Lysholm score and Knee Injury and Osteoarthritis Outcome Score), strength (Biodex System 3 Dynamometer(®)) and proprioception (balance and postural control using the Balance Master system(®)). Each design was also compared to the non-operated contralateral side in terms of strength and proprioception.

RESULTS

There were no significant differences between both designs in terms of clinical outcome and strength. In terms of proprioception, only the rhythmic weight test at slow and moderate speed shifting from left to right was significant in favour of the CR design. None of the unilateral stance tests showed any significant difference between both designs. There was no difference in terms of strength and proprioception between the operated side and the non-operated side.

CONCLUSION

Retaining the PCL in TKA does not result in an improved performance in terms of clinical outcome and proprioception and does not show any difference in muscle strength.

LEVEL OF EVIDENCE

III.

Similar outcome after retention or sacrifice of the posterior cruciate ligament in total knee arthroplasty

BACKGROUND AND PURPOSE

To retain or to sacrifice the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) remains a matter of discussion. In this systematic review, we wanted to find differences in functional and clinical outcome between the 2 methods.

METHODS

We conducted a systematic review and meta-analysis including all randomized controlled trials (RCTs) and quasi-RCTs that have compared PCL retention with PCL sacrifice in TKA with a minimum of 1-year follow-up. Primary outcome was range of motion. Secondary outcomes were knee pain and clinical scoring systems that were preferably validated. Quality of evidence was graded using the GRADE approach. All outcomes available for data pooling were used for meta-analysis.

RESULTS

20 studies involving 1,877 patients and 2,347 knees were included. In meta-analysis, the postoperative flexion angle had a mean difference of 2 degrees (95% CI: 0.23-4.0; p = 0.03) and the KSS functional score was 2.4 points higher in favor of PCL sacrifice (95% CI: 0.41-4.3; p = 0.02). There were no statistically significant differences regarding other measured clinical outcomes such as WOMAC, KSS pain, clinical and overall score, HSS score, SF-12, radiolucencies, femoro-tibial angle, and tibial slope. The quality of the studies varied considerably. Risk of bias in most studies was unclear; 5 were judged to have a low risk of bias and 5 to have a high risk of bias.

INTERPRETATION

We found no clinically relevant differences between retention and sacrifice of the PCL in TKA, in terms of functional and clinical outcomes. The quality of the studies ranged from moderate to low. Based on the current evidence, no recommendation can be made as to whether to retain or to sacrifice the PCL.

Posterior stabilized versus cruciate retaining total knee arthroplasty designs: conformity affects the performance reliability of the design over the patient population

Commercially available fixed bearing knee prostheses are mainly divided into two groups: posterior stabilized (PS) versus cruciate retaining (CR). Despite the widespread comparative studies, the debate continues regarding the superiority of one type over the other. This study used a combined finite element (FE) simulation and principal component analysis (PCA) to evaluate "reliability" and "sensitivity" of two PS designs versus two CR designs over a patient population. Four fixed bearing implants were chosen: PFC (DePuy), PFC Sigma (DePuy), NexGen (Zimmer) and Genesis II (Smith & Nephew). Using PCA, a large probabilistic knee joint motion and loading database was generated based on the available experimental data from literature. The probabilistic knee joint data were applied to each implant in a FE simulation to calculate the potential envelopes of kinematics (i.e. anterior-posterior [AP] displacement and internal-external [IE] rotation) and contact mechanics. The performance envelopes were considered as an indicator of performance reliability. For each implant, PCA was used to highlight how much the implant performance was influenced by changes in each input parameter (sensitivity). Results showed that (1) conformity directly affected the reliability of the knee implant over a patient population such that lesser conformity designs (PS or CR), had higher kinematic variability and were more influenced by AP force and IE torque, (2) contact reliability did not differ noticeably among different designs and (3) CR or PS designs affected the relative rank of critical factors that influenced the reliability of each design. Such investigations enlighten the underlying biomechanics of various implant designs and can be utilized to estimate the potential performance of an implant design over a patient population.

High-flexion posterior-substituting versus cruciate-retaining prosthesis in total knee arthroplasty: functional outcome, range of motion and complication comparison

PURPOSE

Currently, a high-flexion cruciate-retaining knee prosthesis has been designed to allow greater advantage after total knee arthroplasty (TKA). The present study was conducted to compare functional outcome, range of motion (ROM) as well as complications in subjects who underwent either a high-flexion cruciate-retaining (HFCR, Group I) or a high-flexion posterior-substituting (HFPS, Group II) prosthesis TKA.

METHODS

Thirty-four subjects which had TKA with HFCR prosthesis and thirty-three subjects which had TKA with HFPS prosthesis were enrolled in our study and were assessed preoperatively and at 24 months postoperatively. For functional outcome comparison, Hospital for Special Surgery Score (HSSS), Knee Society Score (KSS, including the Mean Knee Score and the Mean Function Score) as well as SF12 Score (including Mental Health Score and Physical Health Score) were measured. For ROM comparison, the arcs of maximal non-weight-bearing passive flexion and weight-bearing flexion were detected, and the number of knees which allowed patients to kneel and sit cross-legged in comfort was determined. For complication comparison, wound necrosis/discharge, anterior knee pain, dislocation, radiolucent lines as well as osteolysis were investigated.

RESULTS

At 24-month follow-up, no significant difference in functional outcome between the two groups was detected. The average maximal non-weight-bearing flexion was 136.2° for the knees in Group I and 135.1° for the knees in Group II (P > 0.05). The average weight-bearing flexion was 123.2° for the knees in Group I and 129.8° for the knees in Group II (P > 0.05). No significant difference, with regard to the number of knees that allowed kneeling and sitting cross-legged, was detected. Comparisons of postoperative complications between the two groups did not yield a significant difference.

CONCLUSIONS

Our study demonstrated no advantage of the high-flexion cruciate- retaining TKA over high-flexion posterior-substituting TKA with regard to functional outcome, range of motion as well as complications at short-term follow-up. However, longer follow-up is necessary to confirm whether these results are sustained.

Reduced operating time but not blood loss with cruciate retaining total knee arthroplasty

Background

There is no consensus regarding the use of retaining or replacing cruciate implants for patients with limited deformity who undergo a total knee replacement. Scope of this paper is to evaluate whether a cruciate sparing total knee replacement could have a reduced operating time compared to a posterior stabilized implant.

Methods

For this purpose, we performed a randomized study on 50 subjects. All procedures were performed by a single surgeon in the same conditions to minimize bias and only knees with a less than 20 varus deviation and/or maximum 15° fixed flexion contracture were included.

Results

Surgery time was significantly shorter with the cruciate retaining implant (P = 0.0037). The mean duration for the Vanguard implant was 68.9 (14.7) and for the NexGen II Legacy was 80.2 (11.3). A higher range of motion, but no significant Knee Society Scores at 6 months follow-up, was used as controls.

Conclusions

In conclusion, both implants had the potential to assure great outcomes. However, if a decision has to be made, choosing a cruciate retaining procedure could significantly reduce the surgical time. When performed under tourniquet, this gain does not lead to reduced blood loss.

EUROP total knee prosthesis with or without posterior cruciate ligament retention? Comparative study at mid-term follow-up

INTRODUCTION

The aim of the present study was to compare mid-term clinical and functional results of two fixed-bearing EUROP total knee arthroplasties (TKA) with the same design, one in which the posterior cruciate ligament was retained (CR) and the other with posterior-stabilization (PS).

HYPOTHESIS

Mid-term results are similar.

MATERIALS AND METHODS

In this prospective, single centre, comparative study, 104 patients (mean age 76) received 114 cemented fixed-bearing posterior cruciate-retaining or posterior-stabilized EUROP TKA. Only patients in whom the medial pivot and ligaments were intact received a CR prosthesis. The final decision to retain or not the posterior cruciate ligament was made if the flexion gap was well balanced above 90°. Clinical evaluation was performed using the International Knee Society (IKS) score at a mean follow-up of 54 months.

RESULTS

The preoperative IKS function score improved from 30 points in both groups, to 75 points in the CR group and to 65 points in the PS group postoperatively. The preoperative IKS knee score improved from 29 and 25 points in the CR and PS groups, respectively, to 87 points in both groups postoperatively. There was no significant difference in the pre- or postoperative scores between the two groups. Four prostheses underwent surgical revision, three CR and one PS. With revision for any reason as the end point, seven-year overall implant survival was 94.8% in the CR group and 97.5% in the PS group. There was no significant difference between the CR and PS groups.

DISCUSSION

When the indications were followed, our study shows similar mid-term results for both types of TKA.

LEVEL OF EVIDENCE

Level IV, prospective study.

A prospective, randomized comparison of posterior stabilized versus cruciate-substituting total knee arthroplasty: a preliminary report with minimum 2-year results

We compared 56 patients who received a PS post/cam tibial insert and 55 patients who received a more congruent anterior-lipped tibial insert. We hypothesized that clinical outcomes would be equivalent and that tourniquet time and intraoperative blood loss would differ. The mean follow-up is 45 months (30-57 months). Clinical and radiographic outcomes were equivalent for both groups, except that male PS patients received significantly more transfusions than male CS patients (P<.039) and tourniquet time was significantly longer for all patients in the PS group (P<.015). At the minimum 2-year follow-up in this ongoing study, the results demonstrate equivalent functional and radiographic outcomes of the 2 devices, and significant differences in the perioperative findings of transfusion rates and tourniquet times.

Long-term follow-up of cemented fixed-bearing total knee arthroplasty in a Chinese population: a survival analysis of more than 10 years

The aims of this study were to evaluate the long term clinical outcomes and survival rate of total knee arthroplasty (TKA) in Chinese population and the risk factors for failure. Between 1985 to 2001, 297 patients underwent primary TKAs with cemented fixed bearing platform in our center. Survival rate was 92.7% at 10 years, with reoperation of the implant as the endpoint, and 90.4% at 15 years. Main reasons for failure were infection and aseptic loosening. Clinical evaluation of 96 knees with HSS knee score showed the mean scores increased from 56.58 ± 11.05 preoperatively to 92.29 ± 10.95 postoperatively. RA patients had lower long-term survivorship compared with OA patients. Younger patients had better HSS scores. Patella strategy and posterior-cruciate-ligament (PCL) strategy had no effect on implant survivorship and clinical outcome. In conclusion, this was one of first studies showing valid long-term outcomes of primary TKA in Chinese.