ACCELEROMETER-BASED NAVIGATION VERSUS CONVENTIONAL TECHNIQUE IN TOTAL KNEE REPLACEMENT. A PROSPECTIVE STUDY IN A TERTIARY CARE MEDIUM VOLUME SETUP IN INDIA.

The iASSIST system is a portable, accelerometer base with electronic navigation used for total knee arthroplasty (TKA) which guides the surgeon to align and validate bone resection during the surgical procedure. The purpose of this study was to compare the radiological outcome between accelerometer base iASSIST system and the conventional system. Method: A prospective study between two group of 36 patients (50 TKA) of primary osteoarthritis of the knee who underwent TKA using iASSIST ™ or conventional method (25 TKA in each group) from January 2018 to December 2019. A single surgeon performs all operations with the same instrumentation and same surgical approach. Pre-operative and postoperative management protocol are same for both groups. All patients had standardized scanogram (full leg radiogram) performed post operatively to determine mechanical axis of lower limb, femoral and tibial component alignment. Result: There was no significant difference between the 2 groups for Age, Gender, Body mass index, Laterality and Preoperative mechanical axis(p>0.05).There was no difference in proportion of outliers for mechanical axis (p=0.91),Coronal femoral component alignment angle (p=0.08),Coronal tibial component alignment angle (p=1.0).The mean duration of surgery, postoperative drop in Hb, number of blood transfusion didn’t show significant difference between 2 groups (p>0.05). Conclusion: Our study concludes that despite being a useful guidance tool during TKA, iASSIST does not show any difference in limb alignment (mechanical axis), Tibial and femoral component alignment when compared with the conventional method.

Efficacy of Portable Accelerometer-Based Navigation Devices versus Conventional Guides in Total Knee Arthroplasty: A Meta-analysis

Various studies have provided different conclusions regarding which component's alignment can be actually improved by a novel portable accelerometer-based navigation device (PAD) compared with the conventional guide (CON); the operative times and clinical outcomes reported by these studies also exhibited incongruity. Thus, this meta-analysis was conducted to evaluate the efficacy of PADs in total knee arthroplasty (TKA). The Web of Science, EMBASE, PubMed, MEDLINE, and Cochrane Library databases were systematically searched. Studies published till July 2018 and comparing PAD with CON in treatment with TKA were identified. Sixteen studies in which 1,551 TKAs were reported were included. Results showed that PAD was significantly superior to CON in reducing tibial component alignment out of ±3 degrees, femoral coronal angle out of ±3 degrees, and overall mechanical alignment out of ±3 degrees. PAD can also help obtain a more accurate result of femoral coronal angle (degree); however, it requires a longer operative time than the CON group. The two groups were comparable in tibial component alignment out of ±2 degrees, tibial component posterior slope out of ±3 degrees, tibial component posterior slope out of ±2 degrees, femoral coronal angle out of ±2 degrees, femoral sagittal angle out of ±3 degrees, femoral sagittal angle out of ±2 degrees, tibial component alignment (degree), tibial component posterior slope (degree), femoral sagittal angle (degree), overall mechanical alignment (degree), blood loss, Knee Society knee score, Knee Society function score, Oxford Knee Score, Short Form-36 physical component score, Short Form-36 mental component score, and range of motion. In conclusion, compared with CON, PAD can help improve the femoral coronal angle as well as decrease the outliers out of ±3 degrees in femoral/tibial coronal angles and overall mechanical alignment. However, PAD did not show significant advantages in tibial and femoral component sagittal angles out of ±3 degrees, various outliers of ±2 degrees, most mean values of component alignments, operative time, and various functional or satisfactory scores.

Effect of Tibial Component Alignment and Posterior Slope on Tibial Coverage in a Chinese Population: A Three-dimensional Anthropometric Study

The standard for rotational alignment and posterior slope of the tibial component in total knee arthroplasty remains controversial. This study aimed to evaluate the effect of tibial component alignment and posterior slope on tibial coverage. Computer tomographic scans of 101 tibial specimens were used to reconstruct three-dimensional tibia models. A virtual surgery was performed to generate a resection plane with different posterior slopes on the proximal tibia. Symmetrical and anatomical tibial components were placed aligning to the medial one-third of tibial tubercle (Insall) and the medial edge of patella tendon (Akagi), respectively. Differences in coverage and mismatch were evaluated and statistically compared across alignments, slope angles, and genders. The tibial coverage increased from 83.21 to 85.96% for Akagi's alignments and from 85.19 to 87.22% for Insall alignments along with the increasing of posterior slope from 0 to 7 degrees. Regardless of the prosthesis design, there was a significant difference between two rotational alignments as the Insall alignment was significantly higher in tibial coverage. With a slope of 7 degrees, more overhang along with less underhang anteromedially were found in males compared with females. The current anatomical tibial design has a tendency of overhang in the anteromedial zone which does not exist in the symmetrical design. The current tibial baseplate design has better tibial coverage when aligning to the medial third of tibial tuberosity with slopes of 5 and 7 degrees. Gender difference should be taken into account and given priority for prosthesis design.

Radiographic evaluation of tibial component alignment in total knee arthroplasty following extramedullary and intramedullary tibial referencing

<p class="abstract"><strong>Background:</strong> Long term survivorship of total knee arthroplasty (TKA) is significantly dependant on prostheses alignment. The debate on optimal referencing for femoral component is largely resolved with Intra-medullary jigs reproducing superior alignment. However there is still a contention about whether intramedullary or extramedullary jigs are better for tibial referencing. This study aims to compare the accuracy of tibial component alignment in TKA using intramedullary and extramedullary tibial referencing jigs.</p><p class="abstract"><strong>Methods:</strong> Between December 2012 and September 2014, 66 primary conventional cemented TKAs were performed using Nexgen-LPS Flex (Zimmer) implants in 55 patients, 50-80 y old (mean 65.54 y) with osteoarthritis/rheumatoid arthritis. Intramedullary and extramedullary tibial referencing was used in alternate patients undergoing TKA after excluding patients with BMI <span style="text-decoration: underline;">&gt;</span>35 kg/m², knee deformity <span style="text-decoration: underline;">&gt;</span>15⁰,excessive tibial bowing, previous fractures/surgeries/retained metalwork around knee. Postoperatively, tibial component alignment (TCA) in coronal plane was assessed using AP radiograph of leg. A 3^º cutoff from neutral mechanical axis (i.e., 90^o±3^o) was considered acceptable.<strong></strong></p><p class="abstract"><strong>Results:</strong> The intramedullary group (n=33) had 4 outliers (TCA &gt;93^º or &lt;87^º) whereas the extramedullary group (n=33) had 7 outliers (p=0.511). The difference in mean TCA between intramedullary and extramedullary groups was not statistically significant [90.70±2.43 and 90.55±2.17 (p=0.790)]. There were no significant per-operative/post-operative complications in either group.</p><p><strong>Conclusions:</strong> We conclude that both intramedullary and extramedullary tibial referencing guides can be used to achieve desired tibial component alignment (90±3^º) in TKA. However the surgeon should appreciate the benefits and deficiencies of either types of tibial referencing and use whichever is suited in a particular case. </p>

Pedobarographic Analysis in Total Knee Arthroplasty

Pedobarographic gait analysis is a useful tool for the determination of loading distributions and alterations on the lower extremity and their reflection on the foot sole after many orthopaedic surgical applications. To date, there have been no studies evaluating the relationship between component alignment and changes of pedobarographic gait analysis in total knee arthroplasty (TKA). We aimed to investigate the effects of TKA and prosthetic alignment on the distribution of pedobarographic parameters. Quantitative gait patterns of 47 patients were prospectively evaluated by using pedobarography 1 week before surgery and at the seventh month, on average, postoperatively. Component positions were assessed, and all applications were divided into three groups according to tibial component position as varus, neutral, and valgus. Pedobarographic results were compared between pre- and postoperative values for all applications and compared among the groups. Mean postoperative tibiofemoral angle was 5.4 degrees in valgus, and preoperative knee scores were markedly improved postoperatively. The range of tibial component alignment changed between 1 and 4 degrees in the varus and valgus groups. Plantar loading parameters (force and pressure) were significantly decreased in all operated knees, especially in forefoot and midfoot. In varus tibial components, plantar loading values decreased in midfoot and hindfoot. However, in the neutral and valgus groups, similar alterations of plantar loadings were obtained, which included decreasing in forefoot and midfoot with significant increase in hindfoot. Plantar loading distribution changed statistically significantly after TKA despite good clinical and radiographic results. Tibial component alignment was also responsible for plantar loading distribution. Tibial components in varus position create different foot loading characteristics compared with neutral and valgus aligned components. Pedobarographic evaluation in TKA allows clinicians to obtain a proper understanding of abnormal gait caused by component malposition.