The accelerometer-based navigation system demonstrated superior radiological outcomes in restoring mechanical alignment and component sagittal positioning in total knee arthroplasty

Three-Dimensional Bowing Measurement of Distal Femur at Actual Size and Clinical Implications of Total Knee Arthroplasty

Background and Objectives: To assess femoral shaft bowing (FSB) in coronal and sagittal planes and introduce the clinical implications of total knee arthroplasty (TKA) by analyzing a three-dimensional (3D) model with virtual implantation of the femoral component. Materials and Methods: Sixty-eight patients (average age: 69.1 years) underwent 3D model reconstruction of medullary canals using computed tomography (CT) data imported into Mimics® software (version 21.0). A mechanical axis (MA) line was drawn from the midportion of the femoral head to the center of the intercondylar notch. Proximal/distal straight centerlines (length, 60 mm; diameter, 1 mm) were placed in the medullary canal's center. Acute angles between these centerlines were measured to assess lateral and anterior bowing. The acute angle between the distal centerline and MA line was measured for distal coronal and sagittal alignment in both anteroposterior (AP) and lateral views. The diameter of curve (DOC) along the posterior border of the medulla was measured. Results: The mean lateral bowing in the AP view was 3.71°, and the mean anterior bowing in the lateral view was 11.82°. The average DOC of the medullary canal was 1501.68 mm. The average distal coronal alignment of all femurs was 6.40°, while the distal sagittal alignment was 2.66°. Overall, 22 femurs had coronal bowing, 42 had sagittal bowing, and 15 had both. Conclusions: In Asian populations, FSB can occur in coronal, sagittal, or both planes. Increased anterolateral FSB may lead to cortical abutment in the sagittal plane, despite limited space in the coronal plane. During TKA, distal coronal alignment guides the distal femoral valgus cut angle, whereas distal sagittal alignment aids in predicting femoral component positioning to avoid anterior notching. However, osteotomies along the anterior cortical bone intended to prevent notching may result in outliers due to differences between the distal sagittal alignment and the distal anterior cortical axis.

Midterm Outcomes After Total Knee Arthroplasty With Lateral Approach for Valgus Knee Deformity in Patients With Rheumatoid Arthritis

Background Valgus knee deformity is often seen in rheumatoid arthritis (RA) cases. Usually, the medial approach has been often utilized for total knee arthroplasty (TKA), even in valgus deformity cases; however, the medial approach is feared to induce further instability in the medial side because it could further break the soft tissue structure, including medial collateral ligament (MCL) and medial patellofemoral ligament (MPFL). Consequently, loosening of the implant, recurrence of valgus knee deformity, and pain due to instability might be induced in the early period after surgery. In this study, a lateral approach for TKA against valgus deformity in RA cases was utilized to avoid further damage on the medial side. Methods Eleven valgus knees in 10 patients with RA (mean age, 61.1 years; mean follow-up, 33.1 months) underwent primary TKA with the lateral approach. Iliotibial band (ITB) dissection and/or peroneal nerve release were performed if necessary. Radiological and clinical investigations were evaluated pre- and postoperatively. Results The average operating time was 106 minutes, which was no longer compared with the time after the medial approach described previously. The extension angle was significantly improved from -15.0 ± 10.2 to -5.5 ± 4.2 degrees (P = 0.03), while the flexion angle showed no significant change (from 111.8 ± 15.9 to 115.0 ± 13.2 degrees). The hip-knee-ankle angle (HKA) was also significantly corrected from -9 ± 4.9 to 0.4 ± 1.7 degrees (P < 0.001). The 2011 Knee Score System (KSS) scores were significantly improved from 6.9 ± 3.4 to 21.5 ± 2.9 (P < 0.001) in symptoms, from 15.6 ± 2.7 to 31.1 ± 4.1 (P < 0.001) in satisfaction, and from 31.5 to 59.5 (P < 0.01) in activity. Conclusion Midterm outcomes after lateral approach TKA were good, and knee alignment was significantly improved. The lateral approach TKA for valgus deformity in patients with RA was not complicated and difficult because it required no additional operating time compared with the medial approach. From the perspective of preventing further damage to the soft tissue structure on the medial side, the lateral approach was meaningful for valgus deformity in patients with RA.

An updated meta-analysis comparing complications, functional, clinically relevant and radiological outcomes of accelerometer based portable navigation and conventional technique of total knee arthroplasty

Introduction

Since previous studies, including small-scale meta-analyses comparing accelerometer-based portable navigation (APN-TKA) and conventional techniqueof total knee arthroplasty (CONV-TKA), have reported divergent results, there is a need for an updated meta-analysis to compare complications, functional outcomes, clinically relevant outcomes and radiographic alignment of components.

Methods

This meta-analysis was conducted as per PRISMA guidelines. Randomised controlled trials, and non-randomised comparative cohort studies in English language on primary TKA were included. The complications compared were Deep Vein Thrombosis (DVT), Pulmonary Embolism (PE), infection, manipulation under anaesthesia (MUA) for postoperative knee stiffness, re-operation and mortality. The functional outcomes compared were the Knee Society Knee Score, Knee Society Score function, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score and Western Ontario and McMaster Universities Arthritis Index. The evaluated clinically relevant outcomes were surgical time, blood loss, drop in haematocrit, tourniquet time, postoperative knee flexion and complications). The number of radiological outliers; as well as the absolute values of the alignment of the overall prosthesis, femoral and tibial components in both coronal and sagittal planes, was assessed.

Results

Twenty-five studies were included. Both the groups were comparable in terms of preoperative demographic features. There was no difference in complications and functional outcomes. Operation time was longer in APN-TKA (p < 0.00001) but there was no difference in rest of the clinically relevant outcomes. Restoration of the lower limb mechanical axis (p = 0.003) and coronal femoral alignment angle (p = 0.0002) was better with APN. APN also significantly reduced the risk of the odds of outliers of lower limb mechanical axis (p < 0.0001), coronal femoral alignment (p = 0.03), coronal tibial alignment (p < 0.0001) and sagittal tibial alignment (p = 0.0001).

Conclusion

The improvement in the accuracy of implantation by the use of APN-TKA, as determined by the overall alignments of prosthesis, or femoral and tibial components, does not necessarily translate into lesser complications and better functional and clinical outcomes.

Level of evidence

Therapeutic study, Level II.

Comparison of navigation systems for total knee arthroplasty: A systematic review and meta-analysis

Background

Component alignment is a crucial factor affecting the clinical outcome of total knee arthroplasty (TKA). Accelerometer-based navigation (ABN) systems were developed to improve the accuracy of alignment during surgery. This study aimed to compare differences in component alignment, clinical outcomes, and surgical duration when using conventional instrumentation (CONI), ABN, and computer navigation (CN) systems.

Methods

A comprehensive literature search was carried out using the Web of Science, Embase, PubMed, and Cochrane databases. Articles that met the eligibility criteria were included in the study. Meta-analyses were performed using the Cochrane Collaboration Review Manager based on Cochrane Review Method. The variables used for the analyses were postoperative clinical outcome (PCO), surgical duration, and component alignment, including the hip-knee-ankle (HKA) angle, coronal femoral angle (CFA), coronal tibial angle (CTA), sagittal femoral angle (SFA), sagittal tibial angle (STA), and the outliers for the mentioned angles. The mean difference (MD) was calculated to determine the difference between the surgical techniques for continuous variables and the odds ratio (OR) was used for the dichotomous outcomes.

Results

The meta-analysis of the CONI and ABN system included 18 studies involving 2,070 TKA procedures, while the comparison of the ABN and CN systems included 5 studies involving 478 TKA procedures. The results showed that the ABN system provided more accurate component alignment for HKA, CFA, CTA, and SFA and produced fewer outliers for HKA, CFA, CTA, and STA. However, while the ABN system also required a significantly longer surgical time than the CONI approach, there was no statistical difference in PCO for the two systems. For the ABN and CN systems, there was no statistical difference in all variables except for the ABN system having a significantly shorter surgical duration.

Conclusion

There was no significant difference in the accuracy of component alignment between the ABN and CN systems, but the ABN approach had a shorter surgical duration and at lower cost. The ABN system also significantly improved the accuracy of component alignment when compared to the CONI approach, although the surgery was longer. However, there was no significant difference in PCO between the CONI, ABN, and CN systems.

Accelerometer-Based Handheld Navigation Instrumentation in Total Knee Arthroplasty Decrease Blood Loss Compared to Conventional Instrumentation: A Prospective Comparative Study

Introduction Total Knee Arthroplasty (TKA) can be associated with significant peri- and post-operative blood loss necessitating blood transfusion. The blood loss may be relatively less when the accelerometer-based handheld navigation system (HHNS) is used, as there is neither a need for intramedullary breach nor additional pin insertions. The primary hypothesis was that HHNS instrumentation reduced perioperative blood loss when compared with conventional instrumentation, and to prove this, we compared the perioperative parameters like tourniquet time, hemoglobin loss, and estimated blood loss between patients undergoing total knee arthroplasty using conventional instrumentation with handheld navigation instrumentation. Methods This prospective comparative study involves 40 patients in the HHNS group and 40 patients in the conventional group based on the instrumentation used, respectively. Tourniquet was used in all the cases. Patient characteristics like age, sex, body mass index (BMI), American Society of Anaesthesiologists (ASA) grade, and Charlson Comorbidity Index (CCI) were recorded. The perioperative parameters like tourniquet time, the estimated blood loss, hemoglobin loss, blood transfusions, and the number of units transfused were recorded and compared between the groups. Results There was no significant difference in age, BMI, ASA grade, or CCI between the two groups. The tourniquet time was 83.7 ± 9.6 in the navigation and 73.9 ± 10.3 in the conventional group. The estimated Hb loss was lower at 2.5 ± 1.6 in the HHNS group compared to 3.0 ± 1.8 in the conventional group (p<0.001). Similarly, estimated blood loss was also lower at 830 ± 285ml for the HHNS group compared to 1088 ± 228 in the conventional group. Two patients in the navigation group had a total of four units transfused, whereas three patients in the conventional group had five units of blood transfusion. Conclusions The primary hypothesis that HHNS reduced perioperative blood loss was confirmed by the results of our study. We demonstrated that HHNS instrumentation significantly decreased the estimated blood loss, drain volume, and hemoglobin loss compared to conventional instrumentation with similar operating times. Though blood transfusions were seen in fewer patients, there was no significant reduction in blood transfusions by HHNS instrumentation.

Alignment accuracy and functional outcomes between hand-held navigation and conventional instruments in TKA: a randomized controlled trial

Background

This study assessed surgical accuracy and functional outcomes using hand-held accelerometer-based navigation following total knee arthroplasty (TKA). Question: (1) Does hand-held navigation (the iAssist system) improve surgical accuracy (assessed with five parameters commonly used to evaluate surgical alignment: the hip-knee-ankle angle (HKA), femoral coronal angle (FCA), tibial coronal angle (TCA), femoral sagittal angle (FSA), and tibial slope angle (TSA)) compared to conventional instruments in TKA? (2) Which surgical alignment parameters among HKA, FCA, TCA, FSA, and TSA can obtain the most advantage from the iAssist system? (3) Does the iAssist system lead to better functional outcomes at two years of follow-up after TKA?

Methods

This parallel-group double-blinded randomized controlled trial recruited 60 patients (30 patients each in the iAssist and conventional group) with osteoarthritis who underwent primary TKA by a single surgeon at Siriraj Hospital. There was no loss to follow-up in the study. All procedures in both groups were performed using similar surgical exposure, prosthesis implant, perioperative and postoperative protocols. Participants in the iAssist group received the iAssist system as an assistive technique, while those in the conventional group only had conventional instruments. Surgical alignments (HKA, FCA, TCA, FSA, and TSA) were recorded using CT scan at six weeks post-operation. Functional outcomes were assessed with knee ROM, KSS, and EQ-5D at 6 months, 1 year and 2 years post-operation. Baseline characteristics including age, sex, the affected knee side, and body mass index were comparable between the two groups, similar to preoperative ROM, KSS, and EQ-5D.

Results

The mean operative time was relatively longer in the iAssist than the conventional group, although not statistically significant (88.1 ± 13.7 versus 83.4 ± 21.3; p = 0.314). Among the surgical alignment parameters evaluated, FCA was the only radiographic parameter with a statistically significant difference between the two groups and was closer to 90º in the iAssist group (89.4 ± 2.2 in the iAssist versus 87.2 ± 2.1 in the conventional group; p = 0.003). Also, there was a higher proportion of outliers in the conventional than the iAssist group (23.3% versus 10%; p = 0.086). Nonetheless, HKA and TCA did not differ between the two groups (p = 0.25 and 0.096, respectively), although the percentages of outliers were higher in the conventional than the iAssist group (HKA: 26.7% vs. 13.3%; p = 0.101 and TCA: 6.7% versus 0%; p = 0.078). Likewise, we observed other radiographic parameters had no significant group differences, including FSA and TSA. Furthermore, at two years post-operation, we found no differences between the iAssist and the conventional group in knee ROM (106.7 ± 14.6 versus 108.2 ± 12.7; p = 0.324), KSS (82.5 ± 6.4 versus 83.8 ± 3.4; p = 0.324), and EQ-5D (0.9 ± 0.2 versus 1.0 ± 0.1; p = 0.217). All functional outcomes were also comparable at 6 months and 12 months of follow-up postoperatively.

Conclusion

The iAssist technology increase surgical precision by allowing for a more precise FCA with fewer outliers than conventional equipment. iAssist had longer operative time. Functional outcomes and quality of life were not different.

Level of evidence:

I

[Future implications of navigation in total knee arthroplasty]

BACKGROUND

After more than two decades of experience with computer-assisted knee arthroplasty, extensive experience and study data are available, allowing a profound evaluation. Undoubtedly, computer-assisted knee arthroplasty has been proven to achieve excellent results for implant positioning and long-leg axis reconstruction. Thus, computer-assisted knee arthroplasty represents the current gold standard to avoid unintended malpositioning of total knee components for neutrally aligned implants and individualized implant alignment (kinematic alignment, adjusted mechanical alignment, and others). Previous studies could not show significant differences in functional outcomes and patient satisfaction. However, recent meta-analyses showed relevant advantages of computer-assisted knee arthroplasty. These results could be based on further developments in software-assisted soft tissue balancing and more sensitive evaluation methods of follow-up examinations.

LONG-TERM OUTCOME

Further, international registries show advantages of computer-assisted knee arthroplasty regarding long-term outcomes. In particular, the Australian arthroplasty registry describes a significantly lower revision rate due to aseptic loosening/osteolysis in the computer-assisted knee arthroplasty group, analyzing a period of up to 17 years. These positive effects can already be proven six months following surgery.

FUTURE PROSPECTS

However, despite demonstrated benefits, computer-assisted knee arthroplasty has not yet become established in daily routine, and wide regional variations in its use are observed. Newer developments such as robotic-assisted knee arthroplasty, primarily based on navigation techniques, are currently being heavily promoted. However, this new technology must justify its enormous additional costs and prove its advantages compared to computer-assisted knee arthroplasty. In the backdrop of the development of computer-assisted knee arthroplasty, this might be a difficult task.

Navigated and Robot-Assisted Technology in Total Knee Arthroplasty: Do Outcome Differences Achieve Minimal Clinically Important Difference?

BACKGROUND

In total knee arthroplasty (TKA), computer-assisted navigation (N-TKA) and robotic-assisted methods (RA-TKA) are intended to increase precision of mechanical and component alignment. However, the clinical significance of published patient-reported outcome measure (PROM) differences in comparison to conventional TKA (C-TKA) is unknown.

METHODS

A systematic review was performed to identify all studies reporting perioperative PROMs for either primary N-TKA or RA-TKA with a C-TKA comparison cohort with a minimum 1-year follow-up. Relative improvements in PROMs for the two cohorts were compared to published minimal clinically important difference (MCID) values.

RESULTS

After systematic review, 21 studies (N = 3,214) reporting on N-TKA and eight studies (N = 1,529) reporting on RA-TKA met inclusion criteria. Eighteen of 20 studies (90%) reported improved radiographic outcomes with N-TKA relative to C-TKA; five of five studies reported improved radiographic outcomes with RA-TKA relative to C-TKA. Five of 21 studies (24%) reported statistically significant greater improvements in clinical PROMs for N-TKA relative to C-TKA, whereas only two (10%) achieved clinical significance relative to MCID on a secondary analysis. One of 8 studies (13%) reported statistically significant greater improvements in PROMs for RA-TKA relative to C-TKA, whereas none achieved clinical significance relative to MCID on a secondary analysis. No studies reported a significant difference in revision rates.

CONCLUSION

While most studies comparing RA-TKA and N-TKA with C-TKA demonstrate improved radiographic alignment outcomes, a minority of studies reported PROM differences that achieve clinical significance. Future studies should report data and be interpreted in the context of clinical significance to establish patient and surgeon expectations for emerging technologies.

Accelerometer-based, hand-held navigation for improved knee alignment in total knee arthroplasty: An observational study

BACKGROUND

Malalignment in total knee arthroplasty has been associated with poor implant longevity and clinical outcomes. The aim of this study was to investigate the accuracy of accelerometer-based navigation in restoring the mechanical axis.

METHODS

106 primary total knee arthroplasties performed during February 2016 to September 2017 at a tertiary care centre in India were enrolled in this observational study. We noted the intra-op tourniquet time. Two separate blinded observers measured the preoperative mechanical axis and the post operative radiological results (mechanical axis, coronal and sagittal alignment of femoral and tibial components) and the mean value was taken as final data. Interclass correlation was done to look for variability between the two observers.

RESULTS

The mean pre operative mechanical axis was 13.74 ± 10.44. The mean tourniquet time was 53.14 ± 7.42 min 91.5% (96/106) knees were within ±3° of neutral mechanical axis with a mean of 1.00° ± 2.68°. The femoral and tibial components with coronal alignment within ±3° perpendicular to the mechanical axis were 93.39% (99/106) and 89.62% (95/106) respectively. In the sagittal plane 89.62% of the femoral components and 87.73% of the tibial components were within ±3° perpendicular to the axis of tibia.

CONCLUSION

The Accelerometer based portable navigation system effectively reduces the coronal and sagittal alignment outliers in total knee arthroplasty and has no role in rotational alignment of components.