Comparison between computer-assisted-navigation and conventional total knee arthroplasties in patients undergoing simultaneous bilateral procedures: a randomized clinical trial

Computed tomography evaluation in total knee arthroplasty: computer-assisted navigation versus conventional instrumentation in patients with advanced valgus arthritic knees

Arthritic knees with advanced valgus deformity present with soft tissue and osseous anomalies that make total knee arthroplasty (TKA) difficult. We conducted a retrospective chart review of 41 patients (51 knees) to determine whether computer-assisted surgery-TKA (CAS-TKA) is superior to TKA using conventional guiding systems. A significantly higher rate of lateral retinaculum release as well as outlier of sagittal mechanical axes and position of the femoral component (femoral flexion and femoral rotational angle) was recorded in the conventional TKA group versus the CAS-TKA group. Both groups had significant postoperative improvement in clinical performance, but results did not differ significantly between groups. Despite its radiographic benefit, CAS-TKA showed no significant benefit over TKA in short-term clinical functional outcomes when performed by an experienced surgeon.

Does imageless computer-assisted TKA lead to improved rotational alignment or fewer outliers? A systematic review

BACKGROUND

Computer-assisted surgery (CAS) has been developed to enhance prosthetic alignment during primary TKAs. Imageless CAS improves coronal and sagittal alignment compared with conventional TKA. However, the effect of imageless CAS on rotational alignment remains unclear.

QUESTIONS/PURPOSES

We conducted a systematic and qualitative review of the current literature regarding the effectiveness of imageless CAS during TKA on (1) rotational alignment of the femoral and tibial components and tibiofemoral mismatch in terms of deviation from neutral rotation, and (2) the number of femoral and tibial rotational outliers.

METHODS

Data sources included PubMed, MEDLINE, and EMBASE. Study selection, data extraction, and methodologic quality assessment were conducted independently by two reviewers. Standardized mean difference with 95% CI was calculated for continuous variables (rotational alignment of the femoral or tibial component and tibiofemoral mismatch). To compare the number of outliers for femoral and tibial component rotation, the odds ratio and 95% CI were calculated. The literature search produced 657 potentially relevant studies, 17 of which met the inclusion criteria. One study was considered as having high methodologic quality, 15 studies had medium, and one study had low quality.

RESULTS

Conflicting evidence was found for all outcome measures except for tibiofemoral mismatch. Moderate evidence was found that imageless CAS had no influence on postoperative tibiofemoral mismatch. The measurement protocol for measuring tibial rotation varied among the studies and in only one of the studies was the sample size calculation based on one of the outcome measures used in our systematic review.

CONCLUSIONS

More studies of high methodologic quality and with a sample size calculation based on the outcome measures will be helpful to assess whether an imageless CAS TKA improves femoral and tibial rotational alignment and tibiofemoral mismatch or decreases the number of femoral and tibial rotational outliers. To statistically analyze the results of different studies, the same measurement protocol should be used among the studies.

Clinical alignment variations in total knee arthroplasty with different navigation methods

BACKGROUND

We compared the resulting alignment in 90° of flexion and in full extension after total knee arthroplasty (TKA) with two navigation systems using different techniques: a measured resection (MR) system and a gap - balancing (GB) system.

METHODS

Varus and valgus alignment in extension and flexion was compared in 100 consecutive patients who had TKA with an MR distal-femoral-cut-first technique at one institution and 100 consecutive patients in whom a GB tibial-cut-first technique was used at another institution. Alignment deviation of three degrees or more from neutral was considered an outlier.

RESULTS

No significant difference between the groups in coronal alignment in extension or flexion was found, but there were three times the number of outliers for clinical alignment in flexion for the MR group compared to the GB group.

CONCLUSIONS

The use of the GB tibial-cut-first computer-assisted TKA navigation may provide a more consistent clinical alignment in flexion than systems using an MR technique.

LEVEL OF EVIDENCE

Therapeutic study. Level 2.

Soft tissue laxity should be considered to achieve a constant polyethylene thickness during total knee arthroplasty

INTRODUCTION

In total knee arthroplasty (TKA), the gap expansion effect by soft tissue laxity and bone resection amount influence directly on the proper gap size and ideal polyethylene insert thickness. In this study, we hypothesized if bone resection level could be controlled lesser as gap expansion effect resulted in the effects on gap expansion of the collateral release and lax lateral structure, appropriate gap size would be attained without extensive medial soft tissue release even in severe varus deformed knee. The purpose of this study was to show the usefulness of preoperative calculation of soft tissue laxity for determining the appropriate gap size for the targeted PE thickness in TKA.

METHODS

The preoperative varus stress view was used to estimate the effect of soft tissue release on extension gap expansion after primary bone resection. The amount of bone resection was determined with a parallel bone resection device used in our institution. Lateral laxity amount was applied into the device. This study was a retrospective review of 850 TKAs [451 with <10º varus deformity of the mechanical femoro-tibial angle (group 1); 399 with ≥10º varus deformity (group 2)] with a minimum follow-up of 1 year. We compared the range of motion (ROM), the knee society score (KSS), and the incidence of surgical complications at postoperative 1 year between the two groups.

RESULTS

The mean PE thickness was 10.8 ± 1.1 in group 1 and 10.9 ± 1.1 in group 2. The proportion of patients with appropriate PE thickness (i.e., 10-12 mm) was 97.6 % in group 1 and 97.2 % in group 2. The ROM and KSS did not differ significantly between groups.

CONCLUSION

This study showed the usefulness of preoperative calculation of soft tissue laxity for appropriate gap size for targeted polyethylene thickness and possibility to attain constant extension gap regardless of preoperative varus deformity.

No difference in accuracy between pinless and conventional computer-assisted surgery in total knee arthroplasty

PURPOSE

Many studies have demonstrated higher precision and better radiological results in Total knee arthroplasty (TKA) with computer-assisted surgery (CAS). On the other hand, studies revealed a lengthening of operation time up to 20 min for this technique and demonstrated rare additional complications as fractures and neurovascular injuries caused by the array pins and any intraoperative array dislocation leads to abortion of CAS. To combine the advantages and eliminate the disadvantages of standard CAS, we evaluated the accuracy of a so-called pinless CT-free version of knee navigation (pinless CAS) abandoning the reference pins and reducing the necessary workflow to a minimum.

METHOD

The present study compares the accuracy of the reference methods of two different CT-free knee navigation software versions (Brainlab Knee 2.1 and Brainlab Knee Express 2.5). Thirty patients received TKA assisted by standard CAS. Intraoperatively, the proposed bony resections of standard CAS were matched with the new pinless CAS. Postoperatively, the results were checked by evaluating the radiographs concerning leg axis, femoral flexion and tibial slope.

RESULTS

All results concerning precise cuts (femoral as well as tibial coronal/varus-valgus alignment, femoral flexion alignment and tibial slope, resection height) were comparable between both groups (n.s.). In femoral, we found a mean deviation of coronal alignment of 0.3° (SD 0.7) and flexion of 0.2° (SD 0.8). In tibial, we found a mean deviation of coronal alignment of 0.2° (SD 0.5) and slope of 0.2° (SD 0.6). The mean additional operation time for the pinless CAS was below 2 min. The postoperative mechanical leg axis was within the threshold of 3° in all patients, tibial slope and femoral flexion matched with CAS values.

CONCLUSION

In clinical routine, pinless CAS can comprise the advantages of CAS leaving the disadvantages aside. It reduces surgical time and avoids complications associated with the tracking pins of conventional CAS.

Sagittal component alignment is less reliable than coronal component alignment in a Chinese population undergoing navigated TKA

BACKGROUND

The purpose of our study was to determine whether postoperative sagittal component alignments of primary total knee arthroplasty (TKA) using the conventional and navigated technique differed significantly. Additionally, we determined whether the use of navigation systems resulted in hyperextension of the femoral components in Chinese patients.

METHODS

This retrospective study reviewed 36 consecutive patients (72 knees) who underwent simultaneous bilateral primary TKAs at our hospital from February 2011 to March 2012. One knee was replaced using a computer-assisted navigation system, and the contralateral knee was replaced with the conventional technique. The radiographic and clinical results of both groups were compared. The relationship between preoperative anatomic angles and component alignments in conventional TKA and navigated TKA was examined.

RESULTS

The radiographic results showed statistically significant differences only between the navigated and conventional groups for individual femoral coronal and sagittal component alignment. Femoral sagittal component alignment showed less deviation and tended to have hyperextension using the navigated technique (-0.35°) compared with the conventional technique (2.77°). There was no significant difference observed for the Knee Society Score (KSS) between the two groups at 2 years postoperatively.

CONCLUSIONS

The sagittal component alignment of primary TKA obtained using the conventional and navigated techniques differed significantly. Navigated TKAs resulted in a higher risk of hyperextension of the femoral components in Chinese patients.

[Update on navigation in total knee arthroplasty. Where are we today and what lies in the future?]

BACKGROUND

The implantation of an artificial knee is one of the most common operative interventions in German hospitals. Navigation procedures have developed into an integral component of such interventions in the operating theatres of many clinics.

METHODS

For orthopedic surgeons who want to implement an as exact as possible reconstruction of the mechanical leg axis and require intraoperative control of the three dimensional positioning of components and/or the capsular ligament situation, navigation is a well-proven intraoperative tool. The immediate intraoperative control possibility of bone resection and capsular ligament soft tissue balancing means that navigation is a valuable instrument for the biomechanical fundamental understanding in training operations for further education of orthopedic surgeons in training.

DEVELOPMENTS

The greater precision obtained by the implementation of the procedure has not yet been conclusively reflected in an improved postoperative knee function or an increased durability of prostheses. New developments in navigated knee prostheses are pinless navigation and navigation kinematics. In pinless navigation the conventional reference marker system fixed in the femur and shin bones is replaced by a non-invasive reference system. With the aid of navigation kinematics it is possible to image the tibiofemoral and patellofemoral movement dynamics, intraoperatively.

PERSPECTIVE

The aim of the next generation navigation systems for computer-assisted knee prosthetics is implant positioning aligned to the individual anatomy of patients with high and stable range of movement for optimum patellar guidance and kinematics of the artificial joint.

Easy identification of mechanical axis during total knee arthroplasty

PURPOSE

We devised an intraoperatively identifiable mechanical axis (IIMA) as a reference of alignment in total knee arthroplasty (TKA).

MATERIALS AND METHODS

Between February 2010 and January 2011, primary TKAs were consecutively performed on 672 patients (1007 knees) using an IIMA as a reference in the coronal plane.

RESULTS

The alignment of the lower extremity improved from a mean of 11.4±6.7° (-10.3-34.4°) of varus preop. to 0.7±3.5° (-5.2-8.6°) immediately after surgery. Mean alignment of the femoral component in the coronal plane was 89.3±2.3° (83.4-97.2°) postop. and mean alignment of the tibial component was 90.4±2.2° (85.1-94.2°) postop.

CONCLUSION

This study showed that IIMA could be of considerable value as a new guider of alignment that is easily accessible and highly effective during total knee arthroplasty.

Are navigation systems accurate enough to predict the correction angle during high tibial osteotomy? Comparison of navigation systems with 3-dimensional computed tomography and standing radiographs

BACKGROUND

Unpredicted overcorrection of the mechanical axis can occur during navigation-assisted high tibial osteotomy (HTO). It is not clear whether the erroneous overcorrection stems from the navigation system itself or from other causes.

PURPOSE

To evaluate the accuracy of the navigation system in HTO by comparing the change in the femorotibial angle provided by the navigation system with the bony correction angle of the proximal tibia on 3-dimensional computed tomography (3D CT) and with the change in mechanical femorotibial alignment on standing whole-leg radiographs.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

A total of 16 knees underwent navigation-assisted HTO, and their alignment data were obtained before and after correction. For comparison, preoperative and follow-up standing whole-leg anteroposterior radiographs, lateral knee radiographs, and preoperative and postoperative 3D CT scans were taken. The medial proximal tibial angle (MPTA), posterior tibial slope, and mechanical femorotibial angle (mFTA) were measured in these images, and the 3 coronal and 3 sagittal correction angles were compared with each other.

RESULTS

In the coronal plane, the mean correction angle of the navigation system was 9.3° ± 2.0° valgus (range, 6°-13°), and the mean MPTA on 3D CT increased 9.7° ± 2.0° (range, 6.7°-13.8°) after correction. The mean correction angle of the mFTA on standing radiographs was 11.9° ± 3.2° valgus (range, 6.9°-16.5°). There was no statistical significance between the navigation system and 3D CT (P = .187), but there was a statistically significant difference between the navigation system and standing radiographs (P = .001). The results of the correction angle in the sagittal plane were similar to those in the coronal plane.

CONCLUSION

The correction of the femorotibial angle by the navigation system was not different from the bony correction angle on 3D CT. There was a discrepancy between the correction angle of the navigation system and that of the standing radiograph.

CLINICAL SIGNIFICANCE

Surgeons must be cautious about the tension of soft tissue, even when using the navigation system during HTO.

Patient-specific instrumentation does not shorten surgical time: a prospective, randomized trial

The primary purpose of this prospective, randomized study was to determine if patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) shortened surgical time. Secondarily the number of instrument trays and alignment were also compared to cases performed with traditional instrumentation (TI). Fifty-two cases (26 per group) were randomized and videotaped to measure the length of surgery, as well as each individual surgical step. Component alignment and mechanical axis was measured radiographically for each patient. Total surgical time was over 4 minutes shorter for patients in the TI group (57.4 minutes vs. 61.8 minutes; P<0.01). More instrument trays were used in the TI group (7.3 vs. 2.5; P<0.001). There was no significant difference in mechanical alignment between groups on postoperative long alignment radiographs (P=0.77). In conclusion, PSI did not shorten surgical time or improve alignment compared with TI in this prospective, randomized trial, but did reduce the required number of trays.

Customized knee arthroplasty and the role of preoperative imaging

OBJECTIVE

The purpose of this article is to review advances in customized knee arthroplasty, highlighting advances in the use of preoperative imaging for component placement and design.

CONCLUSION

Total knee arthroplasty is a highly successful surgical procedure. Although implant survivorship is generally excellent, failures do occur, and suboptimal component positioning is an important factor in implant failure. Surgical advances have focused on the use of advanced imaging and associated computer-assisted navigation to optimize component positioning.

Does computer-assisted total knee arthroplasty improve the overall component position and patient function?

PURPOSE

There remains controversy as to whether computer-navigated total knee replacement (TKR) improves the overall prosthesis alignment and patient function. The aim of this study was to determine whether computer-assisted total knee arthroplasty provides superior prosthesis positioning when compared to a conventional jig-assisted total knee replacement and whether this affected the functional outcome.

METHODS

This prospective, randomised controlled study compared computer navigated and conventional jig-assisted total knee replacement in 37 patients who underwent bilateral TKR. A quantitative assessment of the spatial positioning of the implant in the 74 total knee replacements was determined using a low-dose dual-beam CT scanning technique. This resulted in six parameters of alignment that were compared. Functional outcomes using the high activity arthroplasty score and Knee Society score were assessed pre-operatively, postoperatively, at three years and at five years. Patients also indicated which knee they felt was subjectively the best.

RESULTS

There was no statistically significant difference in the prosthesis alignment between both groups and the number of outliers was not decreased with navigation. All function scores improved from pre-operative to postoperative but there was no statistically significant difference between the groups at five years. At five years, 40.6% of patients thought their jig-assisted knee was the better knee compared with 21.9% their computer assisted knee and 37.5% of patients who felt they were the same.

CONCLUSION

Computer-assisted implantation of total knee replacements does not offer a significant advantage in prosthesis alignment. There was no difference in functional outcome or subjective "best knee" between the computer-assisted or jig-assisted knee.

Robot-Assisted Navigation versus Computer-Assisted Navigation in Primary Total Knee Arthroplasty: Efficiency and Accuracy

Background. Since the introduction of robot-assisted navigation in primary total knee arthroplasty (TKA), there has been little research conducted examining the efficiency and accuracy of the system compared to computer-assisted navigation systems. Objective. To compare the efficiency and accuracy of Praxim robot-assisted navigation (RAN) and Stryker computer-assisted navigation (CAN) in primary TKA. Methods. This was a retrospective study consisting of 52 patients who underwent primary TKA utilizing RAN and 29 patients utilizing CAN. The primary outcome measure was navigation time. Secondary outcome measures included intraoperative final mechanical axis alignment, intraoperative robot-assisted bone cut accuracy, tourniquet time, and hospitalization length. Results. RAN navigation times were, on average, 9.0 minutes shorter compared to CAN after adjustment. The average absolute intraoperative malalignment was 0.5° less in the RAN procedures compared to the CAN procedures after adjustment. Patients in the RAN group tended to be discharged 0.6 days earlier compared to patients in the CAN group after adjustment. Conclusions. Among patients undergoing TKA, there was decreased navigation time, decreased final malalignment, and decreased hospitalization length associated with the use of RAN when compared to CAN independent of age, BMI, and pre-replacement alignment.

Applications of computer navigation in sports medicine knee surgery: an evidence-based review

Computer-assisted surgery (CAS) has been investigated in a number of sports medicine procedures in the knee. Current barriers to its widespread introduction include increased costs, duration, and invasiveness of surgery. Randomized trials on the use of CAS in anterior cruciate ligament reconstruction have failed to demonstrate a clinical benefit. Data on CAS use in high tibial osteotomy are more promising; however, long-term studies are lacking. CAS has a number of research applications in knee ligament surgery, and studies continue to explore its use in the treatment of osteochondral lesions. This article reviews the applications of CAS in sports medicine knee surgery and summarizes current literature on clinical outcomes.

Accuracy of image-free computer navigated total knee arthroplasty is not compromised in severely deformed varus knees

In severe varus knee deformity, image-free computer navigated total knee arthroplasty (TKA) may result in a malaligned knee. The aim of this study was to compare the results of 17 severe varus knees (≥ 20°) and 81 varus knees (< 20°) that underwent image-free computer navigated TKA and analyze postoperative malalignment. Computer navigated TKA was performed according to standard protocol, and component angles and mechanical axes were evaluated postoperatively with weight bearing full-length standing radiographs. All severe varus knees were corrected to within 3° of neutral lower limb alignment despite having a mean preoperative varus deformities of 22.4°. Neutral alignment was obtained in 88.9% of the varus group (mean preoperative varus deformity of 11.7°), without significant difference between the two groups. No significant difference was found in either the femoral or tibial component angles, or in the frequency of complications. Severity of varus deformity did not affect the accuracy of image-free computer navigated TKA.

Research status and application prospects of digital technology in orthopaedics

In the last 10 years, basic and clinical research in orthopaedics has developed rapidly. Understanding of orthopaedic disorders involves not only routine diagnosis, but also the pursuit of highly efficient and accurate three-dimensional imaging of the intra- and extra-medullary distribution, form and structure of orthopaedic disorders, thus allowing scientific evaluation of the indications for surgery, drawing up of the best surgical plan, minimization of operative trauma and the earliest possible restoration of limb function. Meanwhile, the most important type of basic research, which was previously biomechanical research, has gradually become computational biomechanics based on in vitro cadaver experiments. This review aims to summarize the research status and application prospects of digital technology in orthopaedics, including virtual reality technology, reverse engineering and rapid prototyping techniques, computational biomechanics, computer navigation technology and management of digitization of medical records.

Total knee arthroplasty with a computer-navigated saw: a pilot study

BACKGROUND

Computer-aided surgery aims to improve implant alignment in TKA but has only been adopted by a minority for routine use. A novel approach, navigated freehand bone cutting (NFC), is intended to achieve wider acceptance by eliminating the need for cumbersome, implant-specific mechanical jigs and avoiding the expense of navigation.

QUESTIONS/PURPOSES

We determined cutting time, surface quality, implant fit, and implant alignment after NFC of synthetic femoral specimens and the feasibility and alignment of a complete TKA performed with NFC technology in cadaveric specimens.

METHODS

Seven surgeons prepared six synthetic femoral specimens each, using our custom NFC system. Cutting times, quality of bone cuts, and implant fit and alignment were assessed quantitatively by CT surface scanning and computational measurements. Additionally, a single surgeon performed a complete TKA on two cadaveric specimens using the NFC system, with cutting time and implant alignment analyzed through plain radiographs and CT.

RESULTS

For the synthetic specimens, femoral coronal alignment was within ± 2° of neutral in 94% of the specimens. Sagittal alignment was within 0° to 5° of flexion in all specimens. Rotation was within ± 1° of the epicondylar axis in 97% of the specimens. The mean time to make cuts improved from 13 minutes for the first specimen to 9 minutes for the fourth specimen. TKA was performed in two cadaveric specimens without complications and implants were well aligned.

CONCLUSIONS

TKA is feasible with NFC, which eliminates the need for implant-specific instruments. We observed a fast learning curve.

CLINICAL RELEVANCE

NFC has the potential to improve TKA alignment, reduce operative time, and reduce the number of instruments in surgery. Fewer instruments and less sterilization could reduce costs associated with TKA.

Computer-assisted total knee arthroplasty is currently of no proven clinical benefit: a systematic review

BACKGROUND

Navigated total knee arthroplasty (TKA) may improve coronal alignment outliers; however, it is unclear whether navigated TKA improves the long-term clinical results of TKA.

QUESTIONS/PURPOSES

Does the literature contain evidence of better long-term function and lower revision rates with navigated TKA compared with conventional TKA?

METHODS

A systematic literature review was conducted of navigated TKA reviewing articles related to coronal alignment, clinical knee and function scores, cost, patient satisfaction, component rotation, anteroposterior and mediolateral stability, complications, and longer-term reports.

RESULTS

Coronal plane alignment is improved with navigated TKA with fewer radiographic outliers. We found limited evidence of improvements in any other variable, and function was not improved. The duration of surgery is increased and there are unique complications related to navigated TKA. The long-term benefits of additional increase in accuracy of alignment are not supported by any current evidence.

CONCLUSIONS

The findings in reports of navigated TKA should be interpreted with caution. There are few short- and medium- and no long-term studies demonstrating improved clinical outcomes using navigated TKA. Despite substantial research, contradictory findings coupled with reservations about the cost and efficacy of the technology have contributed to the failure of computer navigation to become the accepted standard in TKA. Longer-term studies demonstrating improved function, lower revision rates, and acceptable costs are required before navigated TKA may be widely adopted. In the future, with improvements in study design, methodology, imaging, navigation technology, newer functional outcome tools, and longer-term followup studies, we suspect that navigated TKA may demonstrate yet unrecognized benefits.

Conventional or navigated total knee arthroplasty affects sagittal component alignment

PURPOSE

Navigation systems have recently been developed to achieve highly reliable prosthetic alignment in total knee arthroplasty (TKA). However, component alignment in the sagittal plane is less reliable than that in the coronal plane even when navigation systems are used. Previous reports examining men showed differences in targeted sagittal prosthetic alignments of TKA achieved using the conventional technique and various navigation systems. However, there have been few studies examining the use of this technique in women, who are the primary candidates for TKA.

METHODS

Radiographs of the entire lower extremity were obtained from 20 elder women while standing and sagittal prosthetic alignments in TKA were planned using the conventional technique as well as three navigation approaches to establish reference frames, and the observations were compared.

RESULTS

Sagittal alignments simulated using the radiographs for the conventional technique and navigation systems differed within a mean of 3.2° ± 1.7° (mean ± SD) to 6.3° ± 2.0°. The use of different reference points on the distal femoral condyles (insertion point of the intramedullary rod, center of the anteroposterior direction of the femoral condyles, and most distal point of the femoral condyles) for each navigation system resulted in differences in the sagittal plane up to 3.0° ± 1.5°. The use of navigation systems resulted in a more hyperextended position between the femoral and tibial components compared to that for the conventional technique.

CONCLUSIONS

Targeted sagittal prosthetic alignments of TKA achieved using the conventional technique and various navigation systems differed in elderly women. The use of different reference points on the distal femoral condyle for navigation systems resulted in different alignment in the sagittal plane. This study showed that alignment tendencies are similar in men and women.

LEVEL OF EVIDENCE

Prognostic studies, IV.

Systematic review of computer-navigated total knee arthroplasty

BACKGROUND

Conventional total knee arthroplasty (TKA) and the more recently available computer-navigated total knee arthroplasty (CNTKA) use alternative methods to achieve correct limb alignment. This systematic review was undertaken to assess the safety and effectiveness of CNTKA compared with conventional TKA.

METHODS

A systematic search of multiple databases identified relevant randomized controlled trials published to August 2012. Study inclusion was established through application of a predetermined protocol, with independent assessment by two reviewers.

RESULTS

Thirty randomized controlled trials were included. The majority of adverse events associated with CNTKA were minor and comparable with those seen with conventional TKA. Conversion to conventional TKA was required in 1% of patients undergoing CNTKA. Thirteen trials reporting on satisfactory post-operative radiological alignment of the mechanical axis in the frontal plane were suitable for meta-analysis, which showed a significant total odds ratio (non-event) of 2.32 (95% confidence interval: 1.77-3.04) in favour of CNTKA (P < 0.00001). Clinical outcomes were comparable between the two techniques, with longer-term follow-up suggesting that CNTKA provided no benefit over conventional TKA in terms of sustained functional improvements.

CONCLUSIONS

At present, it is unclear whether the significant improvements shown in radiological outcomes after CNTKA translate to measurable clinical benefits. Although an assumption could be made that an improvement in post-operative alignment should lead to an improvement in patient-related outcomes, the available literature did not clearly show this. Further, long-term trials are required to address this issue.

MODERN TRENDS IN ORTHOPEDICS: THE KNEE ARTHROPLASTY

Using PubMed the authors analyzed publications dedicated to knee arthroplasty that were published in 2011. The modern trends of knee joint replacement include improvement of implants and instruments; partial knee replacement as alternative to TKA; reducing of surgical trauma due to less-invasive approaches; achieving of deep flexion after TKA; using of computer navigation and individual cutting blocks to make surgery more precise; optimization of rehabilitation process in pre-, intra-and postoperative period; including multimodal pain control; development of complex strategies for prevention of intra- and postoperative complications. In this review the attention was attracted to the most discussed in 2011 subjects: development of new designs and materials of knee implants; navigation, robotics and individualized resection blocks; partial knee replacement; infection, blood loss and venous thromboembolism after TKA; influence of different factors on arthroplasty outcomes, especially components and leg alignment, patella resurfacing, PCL retention or substitution, uncemented fixation, mobility of PE insert, severe pre-op deformities or stiffness, previous intra-articular fractures and tibia or femur osteotomies, soft tissue deficit etc.