A simple technique to perform total knee replacement without violating the femoral canal: early clinical results on a cohort of 303 patients

Is Total Knee Arthroplasty Surgical Performance Enhanced Using Augmented Reality? A Single-Center Study on 76 Consecutive Patients

BACKGROUND

Augmented reality (AR) is a powerful multipurpose tool. With a dedicated visor, AR allows the visualization of a series of information and/or images superimposed on the user's field of vision. For this reason, it was recently introduced as a surgical assistant tool. This single-center study aimed to evaluate the intraoperative outcomes of total knee arthroplasties performed with AR assistance in terms of time required and the difference between preplanned and achieved implant positioning (in terms of tibial cut varus and slope angles).

METHODS

A total of 76 consecutive patients was selected. Preplanning was performed according to the AR protocol, and the target varus and slope angles were defined to instruct the device, which subsequently guided the tibial cuts intraoperatively. Surgeries were performed starting from the tibial cut, and the time required to perform the calibration, registration, and fixation of the resection block was recorded. The varus and slope angles achieved were recorded to compare with the preplanned ones to determine the means and SDs of the differences.

RESULTS

The mean usage time of the AR tool was 5 ± 1 minutes. Results showed a mean difference of 0.59 ± 0.55° for varus angles and 0.70 ± 0.75° for the slope. For varus angles, the differences were <1° for 96% of the cases. Concerning the slope, 89% of the cases were <1°.

CONCLUSION

The results showed excellent accuracy of the surgical cuts and a limited increase in surgery duration. Therefore, these outcomes highlighted the potential of this new technology as a valid option for surgical assistance.

Effect of Oral Tranexamic Acid on the Blood Transfusion Rate and the Incidence of Deep Vein Thromboembolism in Patients after TKA

Purpose

To explore the effect of oral tranexamic acid treatment on the blood transfusion rate and the incidence of deep vein thromboembolism after total knee arthroplasty (TKA).

Methods

90 patients undergoing TKA admitted to First People's Hospital of Changshu City from January 2019 to January 2020 were selected and randomized into the control group and the experimental group accordingly (45 cases in each group). The control group intravenously received 20 mL/kg tranexamic acid before the incision was closed. The experimental group was given 1 g of tranexamic acid orally before anesthesia, 6 h and 12 h after the operation.

Results

The experimental group witnessed better perioperative indexes in relation to the control group. The experimental group displayed better postoperative coagulation function indexes as compared to the control group (P < 0.05). Remarkably lower postoperative vascular endothelial function indexes in the experimental group than in the control group were observed. The experimental group experienced a markedly lower incidence of deep vein thromboembolism in comparison with the control group (P < 0.05). The postoperative knee society score (KSS) score of the experimental group was significantly higher than that of the control group. A significantly higher postoperative modified rivermead mobility index (MRMI) score was yielded in the experimental group in contrast to the control group (P < 0.05). The experimental group obtained lower numerical rating scale (NRS) scores at T2 and T3 as compared to the control group.

Conclusion

Oral tranexamic acid is a suitable alternative for patients undergoing TKA in terms of reducing the blood transfusion rate, relieving pain, and accelerating the recovery of the patient's limbs.

Effect of an Innovative Biofeedback Insole on Patient Rehabilitation after Total Knee Arthroplasty

Partial weight bearing is fundamental to rehabilitation in the early stages following lower limb surgery. However, it remains debated as to how to properly achieve partial weight bearing while avoiding complications from excessive or premature load. Of the devices currently on the market, instrumented insoles coupled with force-sensitive resistors (FSRs) are among the best options in today’s clinical practice. Still, although several of these systems have been developed in the last few years, only some have been validated, leaving insufficient information on their application in rehabilitation after total knee replacement (TKR). To address this research gap, we evaluated the performance of an innovative biofeedback insole system featuring an extremely low response time for real-time force feedback. We randomly recruited 30 patients who underwent total knee arthroplasty. All patients used the new programmable insole for partial weight bearing per post-operative rehabilitation protocol. Our results confirm their inability to perform a correct gait with low partial weight bearing (<30–50% of their bodyweight). Partial weight bearing with a correct gait in the post-operative period is not obtainable without a measuring system. This new biofeedback insole is thus one of the most indicated and can improve rehabilitation compliance, therefore allowing continual patient monitoring for faster discharge and fast-track rehabilitation.

The use of mobile bearing TKA in valgus deformities - A clinical study

BACKGROUND

The number of patients presenting valgus deformities undergoing total knee arthroplasty (TKA) represents approximately 10% of the total number of TKAs performed: the presence of valgus deformity requires the implant to have proper alignment, stability and balance to achieve successful clinical outcomes, especially for knees with high coronal deformities, but these have proven to be difficult goals to achieve and therefore the use of constrained prostheses is often recommended for these cases. However, even though the use of unconstrained mobile bearing for severe knee deformities is rare, it has been shown to give successful outcomes and therefore the aim of this study is to evaluate whether this surgical technique can achieve satisfactory clinical results and correct alignment, as well as good patient satisfaction.

METHODS

This study presents the results of 69 TKA performed with cemented mobile bearing implants by a single surgeon on knee affected by valgus deformities. Asymmetric inserts were adopted for all the implants and an alignment surgical tool, dedicated for valgus patients, was used during the operation. Angles of valgus, WOMAC surveys and Numeric Rating Scale for pain were recorded to evaluate the results of the operations.

RESULTS

A total of 67 pre-op WOMAC questionnaire surveys were collected, with the mean result of this evaluation being 15.9 points. The Numeric Rating Scale for pain had an average of 2.2 for 68 tests. The deformities were corrected from a mean total preoperative valgus angle of 12.5° to a postoperative valgus deformity average of 0.6°. During follow-up, only one patient had serious complications due to the rupture of the extensor apparatus following a domestic accident involving falling. Further 10 patients have mild complications related to injuries such as pain of varying intensity, burning, or swelling of the knee. The level of satisfaction from 0 to 10 (0 not at all satisfied and 10 perfectly satisfied) had an average score of 7.7.

CONCLUSIONS

The surgical approach presented, involving a less constrained model if compared to the ones usually chosen, allowed to achieve correct alignment and high patient satisfaction using mobile bearing implants on valgus knee deformities; further patient follow-up will be performed to evaluate long-term outcomes, but the results achieved already represent a significative finding.

A ligament tensor-guided extramedullary alignment technique for distal femoral cut in total knee replacement: results at a minimum 3 years follow-up

BACKGROUND

Femoral intramedullary canal referencing is used by most knee arthroplasty systems for distal femoral cut; to avoid the opening of the femoral canal different solutions have been presented such as navigation, patient-specific instruments (PSI) or the use of an extramedullary device. The FuZion^® system is a tensor device, created to merge the two main techniques for performing a total knee arthroplasty: the ligament balancing and measured resection techniques. Our idea was to use the tensor as an extramedullary cutting guide for the distal femoral cut, based on a 90° tibial resection.

METHODS

A total of 110 patients were operated on with this technique. Patients were evaluated with weight-bearing long-standing X-rays, knee a-p and lateral views, validated PROMs (Oxford Knee Score, EQ-5D and EQ-VAS), the Knee Society Scoring System (KSS) and the Forgotten Joint Score (FJS). Minimum follow up was 3 years (range 38-50 months).

RESULTS

Complete results were available for 104 patients (5 were lost in follow up and 1 died). Significant improvements were registered for all the evaluated scores from pre-op to the final follow up. Pre-op long-standing X-rays showed 21 valgus knees (20%) with a mean HKA of 187.6° (± 3.2°), 70 varus knees (62%) with a mean 172.2° (± 3.7°) HKA and 19 neutrally aligned knees, with a mean HKA of 179.5° (0 ± 2°). The radiographic evaluation at 3 months post-op showed 20 valgus knees (mean HKA 183.7° ± 1.5°), 67 varus knees (mean HKA 176.1° ± 1.8°) and 23 neutrally aligned knees with a mean HKA of 179.3° (0 ± 2°). At final follow up the survival rate was 100% for revision of the implant as the endpoint. With any reoperation as the endpoint Kaplan-Meier survival estimate showed a survival rate of 95.1% at 3 years.

CONCLUSIONS

This technique for performing a ligament driven alignment in total knee arthroplasty showed encouraging clinical outcomes at mid-term follow up leaving a residual deformity on the coronal plane.

Extramedullary femoral alignment system in total knee arthroplasty: Accuracy in relation of severity and different types of varus

Objectives

We assessed the accuracy of an extramedullary guide system for femoral component alignment in TKA.

Methods

We retrospectively analysed 87 total knee arthroplasties using a newly developed extramedullary guide system.

Results

Correct postoperative coronal plane femoral component, with deviation from neutral alignment by 3° or less, was found in 87% of the study population. The percentages were 100%, 91% and 79% for HKA of 0-3°, 3-10° and >10°respectively.

Conclusion

The correct use of the extramedullary guide system allows the restoration of the neutral mechanical axes of the lower limb, especially in cases of limited varus deformity.

Experimental and clinical analysis of the use of asymmetric vs symmetric polyethylene inserts in a mobile bearing total knee arthroplasty

Purpose

This study compared the effects of symmetric and asymmetric designs for mobile bearing polyethylene insert for total knee arthroplasty (TKA), both clinically and biomechanically through experimental cadaver tests.

Methods

303 patients implanted with a mobile bearing TKA were retrospectively analyzed up to 2-year follow-up with relative scores. The same femoral and tibial components were used for all the patients; 151 patients received a Symmetric Design (SD) insert and 152 an Asymmetric Design (AD). A biomechanical experimental test was performed to improve the comprehension of the clinical results, analyzing passive squat on 5 cadaveric knee specimens: internal-external rotations of femur and tibial insert respect to the tibia tray were analyzed in native and implanted configurations (with both symmetrical and asymmetrical inserts for each specimen).

Results

After surgery, patients' average flexion improved from 105° (with preoperative extension deficit of 5°), to 115° (SD-group) and 120° (AD-group) at the 2-year follow-up. There was no postoperative extension deficit. AD-group presented better ability to perform certain routines and wasn't affected by any pain, while antero-lateral pain was reported in some SD-group patients. The experimental tests returned no statistically relevant difference in tibio-femoral flexion-extension and internal-external rotations among all the three configurations tested; a statistically significant difference is found for insert-tray internal-external rotations between SD and AD configurations; in details, the AD insert showed insert-tray angles comparable to the ones found for femoral component-tibial tray, while the SD insert returned lower angular values.

Conclusion

Clinically and biomechanically, an asymmetric mobile bearing insert could represent a valid alternative to symmetric mobile bearing insert.

Level of evidence

III, Case-control study Retrospective comparative study.