Posterior cruciate-retaining versus posterior stabilising prostheses for primary total knee arthroplasty in treating osteoarthritis: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Total knee replacements (TKRs) are successful operations that utilities several operative techniques including cruciate retaining (CR) and posterior stabilising (PS) prostheses. To date, neither approach has proved superior. Techniques and implants are under constant evolution and new trials are published. The purpose of this meta-analysis is to determine the current risks and benefits of these two approaches so that an up-to-date clinical recommendation can be given as to which approach if any is superior.

METHODS

We searched PubMed, Cochrane, Embase, Scopus, EBCSO, and Google Scholar. Risk of bias was assessed based on the Cochrane risk of bias criteria. Meta-analysisusing the random effects model was performed by the STATA software and results were displayed on forest plots. Sensitivity analysis was performed for possible causes of heterogeneity.

RESULTS

From 1164 studies, 15 eligible trials were included. Meta-analysis showed that the CR approach had significantly lower Range of Motion and HSS scores. There was no significant difference in KSS, OKS, VAS, or WOMAC scores. Blood loss was significantly less in the CR group. However, there was no significant difference in total complications or revisions. Sensitivity analysis did not reveal any differences in the results.

CONCLUSION

Despite inherent limitations, this updated meta-analysis suggests that both CR and PS approaches continue to be equivocal in terms of clinical outcomes. Both patients and surgeons can be confident in selecting either approach.

LEVEL OF EVIDENCE

Level I.

SYSTEMATIC REVIEW REGISTRATION

the protocol of this systematic review has been registered on PROSPERO.

REGISTRATION NUMBER

CRD42023391435.

The Early Clinical Outcomes Following Unrestricted Caliper Verified Kinematic Alignment Using a Medial Stabilized Design Total Knee Arthroplasty With a Cruciate Retaining Insert

Background

Although various total knee arthroplasty (TKA) implant designs are widely used, the ideal TKA design is yet to be agreed upon. Although the benefits of cruciate-retaining (CR) TKA and medial stabilized (MS) TKA have been reported in literature, the early clinical outcomes of an MS TKA with CR inserts have not been reported. This study aims to report on the patient-reported clinical and radiological outcomes of MS-TKA combined with a CR insert.

Methods

A prospective single-surgeon series evaluated the clinical- and patient-reported outcomes of 115 patients implanted with GMK Sphere CR. Patient outcomes were assessed with the Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Scores (KOOS), Forgotten Joint Score, and Visual Analogue Scale for Satisfaction. Radiological assessment for alignment along with active flexion and extension were also assessed.

Results

Improvement in all scores was observed between the preoperative and 1-year follow-up timepoints, with statistical significance seen for Oxford Knee Score as well as KOOS Symptoms, Pain, Sport, quality of life, and activities of daily living subscales. The mean active flexion between the preoperative and both postoperative timepoints at 6 months and 1 year was also statistically significant (P = .021 and P = .001).

Conclusions

MS-TKA with a CR insert can facilitate symptom relief and improve overall function of the knee after surgery. Both the patient and clinical outcomes were comparable to 1-year outcomes utilizing other MS-TKA designs and were superior to those at 1-year follow-up following implantation of CR-TKA. Most notability, the KOOS symptoms and sports score were higher for the MS-TKA with a CR insert than for an MS-TKA design.

Difference in implant design affects midflexion rotational laxity in cruciate-retaining total knee arthroplasty: a computer navigation study

PURPOSE

This study aimed to compare midflexion rotational laxity between two different design concept models of cruciate-retaining total knee arthroplasty: symmetrical surface design of neutral joint line obliquity and asymmetrical surface design of varus joint line obliquity.

METHODS

Sixty-three knees that underwent cruciate-retaining total knee arthroplasty were evaluated. Manual maximum passive rotational stress without acceleration was applied to the knees under navigation monitoring. Pre-operative and post-operative internal and external rotational angles were measured at 30°, 45°, 60°, and 90° knee flexion.

RESULTS

The post-operative internal rotational laxity was significantly increased compared with pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 9.7° vs 11.1°, 10.6° vs 11.6°, 11.2° vs 12.9°, and 13.2° vs 14.9°; p = 0.01, 0.04, 0.001, and 0.008, respectively). The post-operative external rotational laxity was significantly decreased compared to pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 10.8° vs 6.8°, 12.5° vs 9.4°, 12.8° vs 10.0°, and 11.3° vs 9.5°; p < 0.0001, < 0.0001, < 0.0001, and 0.0008, respectively). The post-operative total rotational laxity significantly decreased, compared with pre-operative levels, at 30° and 45° flexion among all subjects (mean 20.4° vs 17.9°, and 23.1° vs 21.1°; p = 0.002 and 0.04, respectively). The post-operative total rotational laxity was significantly smaller in asymmetrically designed total knee arthroplasty than in symmetrically designed total knee arthroplasty at 30°, 45°, and 60° flexion (mean 19.3° vs 15.8°, 22.8° vs 18.7°, and 24.4° vs 20.8°; p = 0.03, 0.03, and 0.02, respectively), whereas no significant difference was observed at 90° flexion.

CONCLUSION

Compared to symmetrical surface design, asymmetrical surface design resulted in lower rotational laxity at the midflexion range in cruciate-retaining total knee arthroplasty.

LEVEL OF EVIDENCE

III.

No difference in clinical outcomes between functionally aligned cruciate-retaining and posterior-stabilized robotic-assisted total knee arthroplasty

PURPOSE

To compare the clinical outcomes of subjects undergoing primary robotic-assisted total knee arthroplasty (RA-TKA), following functional alignment (FA) principles, with cruciate-retaining (CR) or posterior-stabilized (PS) bearing designs, at a minimum of 24 months of follow-up.

METHODS

This observational, retrospective study included 167 consecutive patients undergoing RA-TKA with cemented PS and cementless CR implants performed with a CT-base robotic-arm assisted system (Mako, Stryker), following FA principles, between 2017 and 2020. Patients were followed up with a clinical and radiographic assessment and were administered the Forgotten Joint Score-12 (FJS-12), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR), and the 5-level Likert scale (5-LLS).

RESULTS

Three TKA revisions were performed (2 PS, 1 CR); therefore, a total of 164 knees with a mean age of 71.7 years (SD 8.9) were considered (80 cemented PS; 84 cementless CR). No statistically significant differences were recorded between study groups relative to FJS-12, KOOS-JR, and 5-LLS at a minimum of two year follow-up (FJS-12 89.3 ± 9.2 vs 87.5 ± 12.8, p-value 0.46; KOOS-JR 88.8 ± 10.0 vs 86.7 ± 14.0, p-value 0.31; 5-LLS 4.5 ± 0.7 vs 4.5 ± 0.8, p-value 0.34).

CONCLUSION

No significant outcome differences were reported between patients undergoing PS and CR RA-TKA at a minimum of two year follow-up. RA-TKA achieves excellent clinical results and high satisfaction scores, regardless of the implant design used.

Similar rate of return to sports activity between posterior-stabilised and cruciate-retaining primary total knee arthroplasty in young and active patient

PURPOSE

Cruciate-retaining and posterior-stabilised implant designs are available for primary total knee arthroplasty. However, whether the implant design is associated with a difference in the level of activity still remains unclear. This clinical trial compared posterior-stabilised and cruciate-retaining implants in sport-related patient-reported outcome measures, range of motion, rate of return to sport, and weekly time dedicated to sport in active adults. It was also hypothesised that in young and active patients both implants lead to a similar rate of return to sport in terms of hours per week, type of sport, and joint mobility.

METHODS

All patients were evaluated preoperatively and for a minimum of 36 months follow-up. The University of California Los Angeles activity scores, High-Activity Arthroplasty Score, and Visual Analogue Scale were administered preoperatively and at the last follow-up. The range of motion was investigated at admission and the last follow-up. Data concerning the hours per week dedicated to sports and the type of sport practiced were also collected at admission and at the last follow-up. The Kaplan-Meier Curve was performed to compare implant survivorship.

RESULTS

Data from 227 procedures (cruciate-retaining: 109, posterior-stabilised: 118) were prospectively collected. At the last follow-up, no difference was reported in The University of California Los Angeles activity scores (p = 0.6), High-Activity Arthroplasty Score (p = 0.1), Visual Analogue Scale (p = 0.9), flexion (p = 0.7) and extension (p = 0.4). No difference was found in the rate of return (p = 0.1) and weekly hours dedicated to sport (p = 0.3). The Kaplan-Meier curve evidenced no statistically significant difference in implant survivorship (p = 0.6).

CONCLUSIONS

At approximately five years of follow-up, no difference was reported between cruciate-retaining and posterior-stabilised implants in active adults in sport-related patient-reported outcomes measures, range of motion, pain, weekly time dedicated to sport, rate of return to sport, and implant survivorship.

LEVEL OF EVIDENCE

Level II, prospective study.

Fluoroscopic and radiostereometric analysis of a bicruciate-retaining versus a posterior cruciate-retaining total knee arthroplasty: a randomized controlled trial

AIMS

The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthroplasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinematics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA).

METHODS

A total of 40 patients with end-stage osteoarthritis were included in this randomized controlled trial. All patients performed a step-up and lunge task in front of a monoplane fluoroscope one year postoperatively. Femorotibial contact point (CP) locations were determined at every flexion angle and compared between the groups. RSA images were taken at baseline, six weeks, three, six, 12, and 24 months postoperatively. Clinical and functional outcomes were compared postoperatively for two years.

RESULTS

The BCR-TKA demonstrated a kinematic pattern comparable to the natural knee's screw-home mechanism in the step-up task. In the lunge task, the medial CP of the BCR-TKA was more anterior in the early flexion phase, while laterally the CP was more posterior during the entire movement cycle. The BCR-TKA group showed higher tibial migration. No differences were found for the clinical and functional outcomes.

CONCLUSION

The BCR-TKA shows a different kinematic pattern in early flexion/late extension compared to the CR-TKA. The difference between both implants is mostly visible in the flexion phase in which the anterior cruciate ligament is effective; however, both designs fail to fully replicate the motion of a natural knee. The higher migration of the BCR-TKA was concerning and highlights the importance of longer follow-up.Cite this article: Bone Joint J 2023;105-B(1):35-46.

Prospective sequential comparison of femoral roll-back between cruciate-retaining and posterior-stabilized total knee arthroplasty using an intra-operative sensor

BACKGROUND

Implant design and surgical techniques affect postoperative knee kinematics in total knee arthroplasty (TKA). This study aimed to compare femoral roll-back between cruciate-retaining (CR) and posterior-stabilized (PS) TKA in the same knee by objectively quantifying the contact point kinematics of the tibiofemoral joint using a sensor.

METHODS

In the present prospective study, we used an intraoperative sensor to compare medial and lateral roll-back during 0-120° knee flexion in 33 knees that underwent CR and PS TKA. We also examined the relationship between mediolateral balance and the lateral-to-medial roll-back ratio. We defined the contact percentage position as the vertical length to the contact point divided by the anteroposterior length of the tibial plate.

RESULTS

The roll-back percentage following PS TKA (19.8 ± 5.1%) was significantly higher than that after CR TKA in both the medial (19.8 ± 5.1% versus 7.1 ± 2.5%, P < 0.001) and lateral (26.8% ± 3.8% versus 18.7 ± 3.8%, P < 0.001) compartments. The medial contact pressure at 90° was significantly correlated with the increased lateral-to-medial roll-back ratio in both CR and PS TKA (both P < 0.001).

CONCLUSION

PS TKA resulted in a higher percentage of femoral roll-back in the medial and lateral compartments than CR TKA. CR TKA caused a higher lateral-to-medial roll-back ratio compared to PS TKA. To reproduce medial pivot knee motion similar to that of a normal knee, the medial soft tissue needed to be balanced more tightly than the lateral soft tissue during TKA. These findings provide some clinical evidence of TKA design selection and proper mediolateral balancing for successful TKA.

Revision total knee arthroplasty for flexion instability : a concise follow-up of a previous report

AIMS

We have previously reported the mid-term outcomes of revision total knee arthroplasty (TKA) for flexion instability. At a mean of four years, there were no re-revisions for instability. The aim of this study was to report the implant survivorship and clinical and radiological outcomes of the same cohort of of patients at a mean follow-up of ten years.

METHODS

The original publication included 60 revision TKAs in 60 patients which were undertaken between 2000 and 2010. The mean age of the patients at the time of revision TKA was 65 years, and 33 (55%) were female. Since that time, 21 patients died, leaving 39 patients (65%) available for analysis. The cumulative incidence of any re-revision with death as a competing risk was calculated. Knee Society Scores (KSSs) were also recorded, and updated radiographs were reviewed.

RESULTS

The cumulative incidence of any re-revision was 13% at a mean of ten years. At the most recent-follow-up, eight TKAs had been re-revised: three for recurrent flexion instability (two fully revised to varus-valgus constrained implants (VVCs), and one posterior-stabilized (PS) implant converted to VVC, one for global instability (PS to VVC), two for aseptic loosening of the femoral component, and two for periprosthetic joint infection). The ten-year cumulative incidence of any re-revision for instability was 7%. The median KSS improved significantly from 45 (interquartile range (IQR) 40 to 50) preoperatively to 70 (IQR 45 to 80) at a mean follow-up of ten years (p = 0.031). Radiologically, two patients, who had not undergone revision, had evidence of loosening (one tibial and one patellar). The remaining components were well fixed.

CONCLUSION

We found fair functional outcomes and implant survivorship at a mean of ten years after revision TKA for flexion instability with a PS implant. Recurrent instability and aseptic loosening were the most common indications for re-revision. Components with increased constraint, such as a VVC or hinged, should be used in these patients in order to reduce the risk of recurrent instability.Cite this article: Bone Joint J 2022;104-B(10):1126-1131.

Evaluation of double-high insert mid-term outcomes in cruciate-retaining medial-pivotal total knee arthroplasty - a propensity score-matched analysis with averaged 8-year follow-up

BACKGROUND

This study aimed to compare the mid-term clinical and radiographic outcomes between medial-pivotal (MP) insert and double-high (DH) insert used under the cruciate-retaining condition in ADVANCE® total knee arthroplasty (TKA).

METHODS

The follow-up was conducted for 158 consecutive patients who underwent unilateral ADVANCE® TKA from January 2011 to April 2014. Eighty-four MP inserts and 74 DH inserts were used under cruciate-retaining conditions. A 1:1 propensity score matching (PSM) analysis was performed between MP inserts and DH inserts to compare the clinical and radiographic outcomes.

RESULTS

After a 1:1 PSM, 120 patients (60 pairs) were matched between the MP and DH inserts groups. The baseline demographic parameters and clinical scores were comparable between the two groups. The postoperative clinical outcomes at an averaged 8-year follow-up of both groups were significantly improved. The range of motion (ROM) of the DH group was better than that of the MP group, and equivalent Knee Society Function Score (KSFS) between the two groups was found. However, the Knee Society Score (KSS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, and Forgotten Joint Score (FJS) of the MP group were found to be significantly superior to those of the DH group. Comparable complication and revision rates were observed between the two groups. The radiographic results were also equally good between MP and DH groups.

CONCLUSIONS

Although the mid-term clinical and radiographic outcomes of the DH inserts are fairly good, the clinical scores of the DH group were worse than those of the MP group.

No clinical differences at the 2-year follow-up between single radius and J-curve medial pivot total knee arthroplasty in the treatment of neutral or varus knees

PURPOSE

Modern total knee arthroplasty (TKA) systems are designed to reproduce the normal knee kinematics and improve patient outcome. The authors compared two different third-generation medial pivot TKA implants, having a single-radius or a J-curve design in their sagittal plane, hypothesizing no clinical differences.

METHODS

Two cohorts of 50 patients who underwent primary TKA were first preoperatively matched by sex, deformity, body mass index (BMI), Oxford Knee Score (OKS), Knee society score (KSS) and range of motion (ROM) and then statistically analyzed at a minimum follow-up (FU) of 2 years. An identical surgical technique, which aimed to reproduce a slightly tighter medial than lateral compartment, was used in all knees.

RESULTS

At a minimum follow-up of 2 years (range 24-34 months) there were no statistically significant differences in OKS and KSS between the two implant groups. The final ROM differed statistically between the two groups: the average maximum active flexion was 123° in the J-curve femoral design group with an adapted "medially-congruent" polyethylene insert, and 116° in the single radius femoral design with a medial "ball-in-socket" articulation.

CONCLUSION

No clinical and radiological differences were found when the two cohorts of patients were compared. This study showed that the implant design played a minor role in the final outcome as opposed to a precise surgical technique.

LEVEL OF EVIDENCE

Retrospective case-control study, Level III.

Pigmented villonodular synovitis does not influence the outcomes following cruciate-retaining total knee arthroplasty: a case-control study with minimum 5-year follow-up

BACKGROUND

Pigmented villonodular synovitis (PVNS) is a rare synovial disease with benign hyperplasia, which has been successfully treated with total knee arthroplasty (TKA). The purpose of this study was to investigate the middle-term follow-up outcomes of cruciate-retaining (CR) TKA in patients with PVNS.

METHODS

From January 2012 to December 2014, a retrospective study was conducted in 17 patients with PVNS who underwent CR TKA as PVNS group. During this period, we also selected 68 patients with osteoarthritis who underwent CR TKA (control group) for comparison. The two groups matched in a 1:4 ratio based on age, sex, body mass index, and follow-up time. The range of motion, Knee Society Score, revision rate, disease recurrence, wound complications, and the survivorship curve of Kaplan-Meier implant were assessed between the two groups.

RESULTS

All patients were followed up at least 5 years. There was no difference in range of motion and Knee Society Score between the two groups before surgery and at last follow-up after surgery (p > 0.05). In the PVNS group, no patients with the recurrence of PVNS were found at the last follow-up, one patient underwent revision surgery due to periprosthetic fracture, and three patients had stiffness one year after surgery (17.6% vs 1.5%, p = 0.005; ROM 16-81°), but no revision was needed. At 7 years, the implant survivorship was 90.0% in the PVNS group and 96.6% in the control group (p = 0.54).

CONCLUSIONS

This study demonstrated that the function of patients with PVNS who underwent CR TKA had been significantly improved, and the survival rate of implants in these patients was similar to the patients with OA. Consequently, the patients with PVNS who underwent CR TKA might be an achievable option. However, these patients should pay more attention to the occurrence of postoperative stiffness complications.

A surgical reduction technique for posterior cruciate ligament avulsion fracture in total knee arthroplasty: a comparison study

Background

Posterior cruciate ligament (PCL) avulsion fracture of the tibia is an uncommon but serious complication during primary cruciate-retaining total knee arthroplasty (TKA). The first objective of this report was to conduct a retrospective cohort study to investigate the incidence and potential risk factors of PCL avulsion fracture in primary cruciate-retaining TKA. The second objective was to assess the functional outcomes of the knee after reduction of PCL avulsion fracture.

Methods

From January 2014 to January 2016, 56 patients who experienced PCL avulsion fracture of the tibia in primary cruciate-retaining TKA were included in the study group. Patients in this group underwent reduction of avulsion fracture. In this period, we selected 224 patients (control group) for comparison. Patients in this group also underwent the same TKA, but no PCL avulsion fracture occurred. The range of motion of the knee and Knee Society Scores were assessed. The Forgotten Joint Score was used to analyze the ability to forget the joint. Differences were considered statistically significant at p < 0.05.

Results

In our series, the incidence of PCL avulsion fracture was 4.6%. There were no significant differences (p > 0.05) with regard to the preoperative or postoperative range of motion of the knee, final 4-year mean clinical score in the study and control groups 92.4 ± 2.7 and 93.6 ± 1.9, respectively, and mean functional scores of 85.1 ± 1.8 and 87.1 ± 1.2, respectively.

Conclusions

The incidence of PCL avulsion fracture of the tibia is relatively high. Older age and female gender were the two risk factors of fracture in primary cruciate-retaining TKA. Reduction of PCL avulsion fracture with a high-strength line can achieve good stability and function of the knee.

Comparison of intraoperative soft tissue balance measurement between two tensor systems in total knee arthroplasty

BACKGROUND

Differences in measurement outcomes using different tensors in total knee arthroplasty (TKA) remain unknown. This study aimed to compare intraoperative soft tissue balance between two measurement systems in TKA.

METHODS

This study included 24 cruciate-retaining (CR) and 27 posterior-stabilized (PS) TKAs for varus-type osteoarthritis. All TKAs were performed with the measured resection technique. Intraoperative soft tissue balance was assessed with femoral component placement and patellofemoral joint reduction throughout the range of motion. Measurements were performed using the Offset Repo-Tensor (Zimmer) and Ligament Sensor Tensor (Depuy). Joint component gaps and varus/valgus ligament balance were compared statistically in CR and PS TKAs.

RESULTS

Joint component gaps with the Offset Repo-Tensor were significantly larger at 0°, 10°, 30°, and 60° of knee flexion in CR TKA and at all knee flexion angles, except 0° and 135°, in PS TKA than those with the Ligament Sensor Tensor (P < .05). Varus balance with the Offset Repo-Tensor was significantly larger at 0°, 10°, and 30° of knee flexion in CR TKA and at 10°, 30°, 60°, 90°, and 120° of knee flexion in PS TKA than that with the Ligament Sensor Tensor (P < .05).

CONCLUSION

Surgeons should consider the discrepancy in assessing intraoperative soft tissue balance depending on the tensor used. The Ligament Sensor Tensor tended to underestimate soft tissue balance in CR and PS TKAs compared with the Offset Repo-Tensor, especially in PS TKA. Thus, surgeons should know the difference in values between the offset-type tensor with consistent distraction force and a spring-loaded tensor.

Joint distraction force changes the three-dimensional articulation of the femur and tibia in total knee arthroplasty: a cadaveric study

PURPOSE

The purpose of this study was to test the hypotheses that the joint distraction force changes the three-dimensional articulation between the femur and the tibia and that the presence of posterior cruciate ligament (PCL) affects the three-dimensional articulation during joint gap evaluation in total knee arthroplasty (TKA).

METHODS

Cruciate-retaining TKA procedures were performed on 6 cadaveric knees using a navigation system. The joint center gap and varus ligament balance were measured using Offset Repo-Tensor^® with the knee at 90° of flexion before and after PCL resection for joint distraction forces of 89, 178, and 266 N. The three-dimensional location of the tibia relative to the femur and the axial rotational angle of the tibia were also assessed.

RESULTS

Regardless of PCL resection, the joint center gap became larger (p = 0.002, p = 0.020) and varus ligament balance became more varus (p = 0.002, p = 0.002) with increasing joint distraction force, whereas the tibia was more internally rotated (p = 0.015, p = 0.009) and more anteriorly located (p = 0.004, p = 0.009). The tibia was more internally rotated (p = 0.015) and more posteriorly located (p = 0.026) after PCL resection than before resection.

CONCLUSIONS

Joint distraction force changed three-dimensional articulation regardless of PCL preservation. PCL function was revealed as a factor restraining both tibial posterior translation and internal rotation. Surgeons should recognize that joint gap evaluation using a tensor device is subject to three-dimensional changes depending on the magnitude of the joint distraction force.

Genesis 1 posterior cruciate-retaining total knee arthroplasty with asymmetric tibial tray: An 18-to-26-year long-term clinical outcome study

BACKGROUND

To present the long-term clinical and radiological outcomes of the Genesis I posterior cruciate-retaining total knee arthroplasty (TKA) (Smith & Nephew Orthopaedics, Memphis, TN, USA) (one of the first designed with an asymmetric tibial tray).

METHODS

Prospectively collected data from 117 cemented TKAs performed on 95 patients were evaluated using this design, with a mean follow-up of 21.5 years (range, 18-26). Failures, complication rates, and clinical (both subjective and objective) and radiological outcomes were assessed for all patients.

RESULTS

Seven failures occurred (wear and structural failure of the polyethylene insert) and six revision surgeries were performed at a mean of 10 years (range, three to 14) from the index operation. No revision of either the femoral or tibial components for aseptic loosening was performed. Survivorship analysis showed a cumulative success rate of 93.53% (95% CI, 92.75-94.32%) at 20 and 25 years, with revision for any reason as an end point. All patients showed a statistically significant improvement (P = 0.001) in the Knee Society and Oxford knee rating scores.

CONCLUSIONS

This study demonstrated satisfactory long-term clinical outcomes for this TKA design, with revisions being related to polyethylene wear structural failure.

Total knee arthroplasty using ultra-congruent inserts can provide similar stability and function compared with cruciate-retaining total knee arthroplasty

PURPOSE

Recently, ultra-congruent (UC) inserts have shown successful outcomes following total knee arthroplasty (TKA). It was hypothesized that patients in the UC group would not show significantly different in vivo stability or functional outcomes from those in the cruciate-retaining (CR) group.

METHODS

The prospective study enrolled patients who had been treated with either CR or UC TKAs (38 cases in each group), after a minimum 3-year follow-up. The same surgical technique was used with the same femoral components in both groups except for the polyethylene inserts (CR or UC). The clinical outcome measures were knee range of motion (ROM), Hospital for Special Surgery (HSS) score, Knee Society (KS) score, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscale score. The mediolateral laxity at full extension and anteroposterior laxity at 90° flexion were measured in stress radiographs and compared between the two groups.

RESULTS

Both the CR and UC groups showed significant improvements in post-operative ROM, HSS, KS, and WOMAC scores without inter-group differences between two groups. Moreover, there were no differences in mediolateral or anteroposterior laxity between the two groups (p > 0.05).

CONCLUSION

TKA with posterior cruciate ligament (PCL) resection using the UC design showed comparable functional outcomes with those of CR TKA and provided similar in vivo stability. Therefore, UC inserts can be a good option in TKA without bony box cut when the PCL is damaged during an operation.

LEVEL OF EVIDENCE

II.

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.

Simultaneous posterior dislocation of primary total knee arthroplasty with ipsilateral tibial shaft fracture: A case report and review of literature

Dislocation following total knee arthroplasty (TKA) is a rare but serious complication. Here, a 74-year-old woman with posterior dislocation of her right cruciate-retaining TKA and ipsilateral tibia diaphysis fracture was presented. She only slipped down on the ground with a quick twist of her right leg. She underwent revision semiconstrained TKA and osteosynthesis of tibial fracture with plate and screw. Her partially avulsed patellar tendon was repaired as well. She was ambulatory with a cane and satisfied with revision operation at last control. Extensor mechanism and functional posterior cruciate ligament is especially important in patients receiving cruciate-retaining TKA. As far as we know, simultaneous dislocation of TKA with fracture of tibia diaphysis has never been reported before.

Mid-term Results of Single-Radius Cruciate Retaining Total Knee Arthroplasty: Minimum 5 Year Follow-up

Purpose

The single-radius design of the knee implant was introduced to improve the results of total knee arthroplasty (TKA) by reducing maximum extensor forces, and it also represents more physiologic quadriceps force pattern, which could have a positive effect on knee function after TKA. We studied mid-term results of single-radius designed cruciate retaining (CR) TKA.

Materials and Methods

We analyzed the functional improvement and radiological osteolytic pattern after TKA using the single-radius Scorpio CR prosthesis. TKA was performed on 102 knees. The mean follow-up period was 73.8 months. For clinical assessment, the range of motion (ROM), Harris hip score, and functional outcome score were obtained preoperatively and at last follow-up.

Results

The average ROM was 100.2° preoperatively and 121.7° at last follow-up. The average knee score was 59.2 points preoperatively and 92.9 points at last follow-up. The average functional outcome score was improved from 51.9 points preoperatively to 85.4 points at last follow-up. Radiolucency was observed in four knees but all were non-progressive lesions smaller than 2 mm.

Conclusions

The clinical outcome of TKA using the single-radius CR prosthesis was good during the mid-term follow-up and the incidence of osteolysis was very rare.