Satisfactory Short-Term Results of Navigation-Assisted Gap-Balancing Total Knee Arthroplasty Using Ultracongruent Insert

Favorable outcomes of posterior cruciate-stabilized inserts over ultracongruent inserts in total knee arthroplasty

OBJECTIVE

Posterior cruciate-stabilized (PS) and ultracongruent (UC) inserts are used during total knee arthroplasty (TKA), but superiority in gaining postoperative knee flexion and functionality remains contested. Therefore, this study compared postoperative outcomes between PS and UC inserts.

METHODS

A retrospective review evaluated unilateral or bilateral TKAs with PS or UC inserts from August 2011 to March 2020. Nonparametric statistics were performed to evaluate differences in patient demographics, pre- and postknee flexion and Knee Society Knee (KSS-K) and Function Score (KSS-F). Univariate and multivariable regressions were performed to evaluate the influence on postoperative knee flexion ≥ 120°, presented as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Patient demographics were not significantly different between the 577 PS and 399 UC knees evaluated. Postoperatively, a larger proportion of UC knees demonstrated knee flexion < 120° (36.0% vs. 18.6%, p < 0.001) and lower KSS-K (91.0 ± 8.7 vs. 91.6 ± 10.3, p < 0.001) and KSS-F (76.8 ± 21.6 vs. 79.9 ± 21.6, p = 0.007) than the PS group. The PS group had greater improvement in flexion angle (4.9° ± 14.9° vs. 1.0° ± 15.6°, p < 0.001) and KSS-F (27.3 ± 23.3 vs. 23.1 ± 25.3, p = 0.007) as compared to that of UC patients. Patients with preoperative flexion < 120° (OR 2.787, CI 2.066-3.761; p < 0.001), higher body mass index (OR 1.033, CI 1.006-1.061; p = 0.017) and UC insert (OR 2.461, CI 1.832-3.307; p < 0.001) were less likely to achieve flexion ≥ 120°.

CONCLUSION

Favorable clinical and functional outcomes were noted in the PS group as compared to UC inserts in TKA. The greater improvement in overall knee flexion may suggest the PS insert may be especially appropriate for patients with lower preoperative range of motion.

LEVEL OF EVIDENCE

III, retrospective comparative study.

The knee position at tourniquet inflation does not affect the gap balancing during total knee arthroplasty

INTRODUCTION

The relationship between gap balancing and clinical outcome of total knee arthroplasty (TKA) has been researched. Tourniquet is widely used by most surgeons; however, there are little quantitative data about the gap depending on the tourniquet usage. We aimed to investigate whether the knee position at tourniquet inflation affected the gap measurement intra-operatively.

METHODS

TKA was performed for 104 knees and the tourniquet was inflated with the knee at full flexion and extension. The gap was measured in each static knee flexion status (0°, 30°, 45°, 60°, 90°, 120°, and in full flexion) using a tensor. We measured the gap twice; under the tourniquet inflation and release. The gap difference at each static knee flexion status was calculated by subtracting the gap under release from that under inflation.

RESULTS

When the tourniquet was inflated with the knee at full flexion, the mean gap differences were < 1 mm and < 1° in each static knee flexion status. When the tourniquet was inflated with the knee at full extension, the mean gap differences were < 1 mm and < 1°, respectively. All values of the gap difference were minimum, and were not affected by the tourniquet, whether the knee position at the tourniquet inflation was flexed or extended.

CONCLUSIONS

We postulated that the knee position at tourniquet inflation would affect the gap, which was refuted by our results. This shows that we can measure the gap without considering the knee position at tourniquet inflation.

No differences in clinical outcomes or isokinetic performance between cruciate-substituting ultra-congruent and posterior stabilized total knee arthroplasties: a randomized controlled trial

PURPOSE

Whether ultra-congruent (UC) or posterior cruciate ligament-stabilized (PS) inserts should be used in posterior cruciate ligament (PCL)-sacrificing total knee arthroplasty (TKA) remains debatable. Therefore, the aim of this prospective randomized controlled study was to compare the isokinetic performance and clinical outcomes of these inserts in PCL-sacrificing TKA.

METHODS

Sixty-six patients diagnosed with primary knee osteoarthritis were randomly assigned to either the UC or the PS group. There were no significant differences between the groups in terms of age, body mass index or sex. The Knee Society score (KSS) and isokinetic performance results for each patient were recorded preoperatively and at 3, 6 and 12 months postoperatively. The physiatrist that performed the isokinetic tests and the patients were blinded to the study groups.

RESULTS

There were no significant differences between the groups in terms of the preoperative KSS or isokinetic performance. Gradual improvement in the KSS was observed in both groups, but no significant differences were detected between the groups during the whole follow-up period. The UC and PS groups exhibited similar peak extension and flexion torque values normalized to body weight at 3, 6 and 12 months postoperatively (p > 0.05).

CONCLUSION

The use of UC or PS inserts in TKA did not affect the clinical outcomes or isokinetic performance.The clinical relevance of this study is that the potential differences in clinical outcomes and isokinetic performance between UC and PS inserts do not need to be considered when sacrificing the PCL in TKA.

LEVEL OF EVIDENCE

I.

Increased external rotation of the osteoarthritic knee joint according to the genu varum deformity

PURPOSE

To evaluate the rotational profile of the lower extremity using computed tomography (CT) in accordance with the degree of varus deformity in medial condyle-affected knee joint osteoarthritis (OA).

METHODS

This retrospective study included 1036 patients (872 lower extremities) with end-stage knee OA. The coronal alignment of the lower extremity was measured using standing anteroposterior radiography. The CT parameters of femoral anteversion and tibial torsion were assessed in relation to the knee joint. The axes were the femoral neck axis; the distal femoral axis, which was composed of the anterior trochlear axis, the clinical transepicondylar axis, and the posterior condylar axis; the axis of the proximal tibial condyles; and the bimalleolar axis.

RESULTS

There was a tendency for increased external rotation of the knee joint parameters in relation to the hip and ankle joints as varus deformity of the lower extremity increased. The relative external rotational deformity of the knee joint in relation to the hip joint had a positive value with a good correlation. The relative external rotational deformity of the knee joint in relation to the ankle joint also demonstrated a positive value with a good correlation.

CONCLUSION

The distal femur and proximal tibia (knee joint) tended to rotate externally in relation to the hip and ankle joint, respectively, as the degree of varus deformity increased. This study identified the relationship between lower extremity varus deformity and rotational deformity of knee joints with OA.

LEVEL OF EVIDENCE

III.

Implant design affects walking and stair navigation after total knee arthroplasty: a double-blinded randomised controlled trial

BACKGROUND

Dissimilar total knee arthroplasty implant designs offer different functional characteristics. This is the first work in the literature to fully assess the Columbus ultra-congruent mobile (UCR) system with a rotating platform.

METHODS

This is a double-blinded randomised controlled trial, comparing the functional performance of the low congruent fixed (CR DD), ultra-congruent fixed (UC) and UCR Columbus Total Knee Systems. The pre-operative and post-operative functional performance of twenty-four osteoarthritic patients was evaluated against nine control participants when carrying out everyday tasks. Spatiotemporal, kinematic and kinetic gait parameters in walking and stair navigation were extracted by means of motion capture.

RESULTS

The UC implant provided better post-operative function, closely followed by the UCR design. However, both the UC and UCR groups exhibited restricted post-operative sagittal RoM (walking, 52.1 ± 4.4° and 53.2 ± 6.6°, respectively), whilst patients receiving a UCR implant did not show an improvement in their tibiofemoral axial rotation despite the bearing's mobile design (walking, CR DD 13.2 ± 4.6°, UC 15.3 ± 6.7°, UCR 13.5 ± 5.4°). Patients with a CR DD fixed bearing showed a statistically significant post-operative improvement in their sagittal RoM when walking (56.8 ± 4.6°).

CONCLUSION

It was concluded that both ultra-congruent designs in this study, the UC and UCR bearings, showed comparable functional performance and improvement after TKA surgery. The CR DD group showed the most prominent improvement in the sagittal RoM during walking.

TRIAL REGISTRATION

The study is registered under the clinical trial registration number: NCT02422251 . Registered on April 21, 2015.

Comparative Analysis of Diaphyseal versus Metaphyseal tracker Placement in Imageless Navigation Systems for Total Knee Arthroplasty

This work was designed to compare the intraoperative parameters and clinical and radiologic outcomes of total knee arthroplasty (TKA) during a minimum follow-up period of 2 years and to discuss the pros and cons of two different tracker placement (diaphyseal and metaphyseal) navigation systems. The null hypothesis was that there would be no clinical or radiologic difference between the two different systems. Primary TKA was performed in a total of 100 knees using the two different image-free navigation systems (group 1: diaphyseal tracker placement and group 2: metaphyseal tracker placement) with the strict gap balancing technique. Symptom severity was assessed at preoperative and at 3, 6, 12, and 24 months after surgery using the Knee Society Score (KSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. Possible adverse issues (major and minor) associated with TKA procedure were observed. Careful assessments were also made of the screw insertion site for infection, stress fractures, and any other related adverse effects. The follow-up periods for groups 1 and 2 were 38 ± 8 months and 38 ± 7 months, respectively. The minimum follow-up period was 24 months. The mechanical alignment improved to 0.1 (valgus) ± 2.2 (group 1) and 0.2 (valgus) ± 2.1 (group 2). There were no radiologic differences between the groups (p > 0.05). In both groups, the KSS and WOMAC improved from before surgery to 24 months after surgery (p < 0.0001). However, the total operation time was 50 ± 5 minutes for group 1, compared to 65 ± 13 minutes for group 2 (p < 0.0001). The metaphyseal tracker navigation system resulted in increased operation time.

Anterior-stabilized TKA is inferior to posterior-stabilized TKA in terms of postoperative posterior stability and knee flexion in osteoarthritic knees: a prospective randomized controlled trial with bilateral TKA

PURPOSE

To determine whether knee stability, range of motion (ROM) and clinical scores differ between anterior-stabilized (AS) and posterior-stabilized (PS) total knee arthroplasty (TKA).

METHODS

This prospective randomized controlled trial included 34 patients with severe bilateral knee osteoarthritis who underwent bilateral TKA between June 2010 and July 2011 using AS and PS designs of a single-implant system. AS TKA with ultracongruent inserts was performed in one knee and PS TKA with a cam-post mechanism was performed in the other knee in each patient. Clinical and radiological data from a mean follow-up period of 5 years, including ROM, clinical scores, peak knee torque determined by isokinetic test, knee joint laxity determined by Telos stress views, tourniquet time and subjects' preference were analyzed.

RESULTS

The mean postoperative knee flexion angle did not differ between groups until 1 year. Beginning 2 years postoperatively, the knee flexion angle decreased slightly in the AS group and was smaller than that in the PS group (p = 0.004). The mean Knee Society knee score was higher in the PS group than in the AS group after 2 years. The quadriceps strength did not differ between groups. The mean posterior laxity after TKA was 6-8 mm greater in the AS group than in the PS group. No radiological loosening was observed in either group. More subjects preferred PS knees to AS knees. However, this difference was not significant.

CONCLUSION

AS primary TKA was inferior to PS TKA in terms of posterior knee stability, postoperative knee flexion and clinical scores after 2 years.

LEVEL OF EVIDENCE

Therapeutic study, Level 1.

Sagittal radius of curvature, trochlea design and ultracongruent insert in total knee arthroplasty

Multi radius (MR) total knee arthroplasty (TKA) has been associated with mid-flexion instability.

Single radius (SR) TKA may provide better anteroposterior stability through single flexion axis and biomechanical advantage for quadriceps function.

Medial pivot (MP) TKA and gradually reducing (GR) radius TKA produce better knee kinematics.

Clinical outcomes are equivalent for SR, MR and MP TKA.

Short-term studies have shown better clinical outcomes and kinematics for GR TKA.

Thinner and narrow anterior flange, deeper trochlea groove and more anatomical trochlea design reduces patellofemoral complications in TKA

Ultracongruent inserts provide comparable clinical outcomes to posterior-stabilized TKA and cruciate retaining TKA.

Cite this article: EFORT Open Rev 2019;4:519-524. DOI: 10.1302/2058-5241.4.180083