Postoperative Mechanical Alignment Research Articles

Robotic-assisted versus conventional total knee arthroplasty: a systematic review and meta-analysis of randomized controlled trials

ObjectivesRobotic knee arthroplasty procedures have emerged as a new trend, garnering attention from orthopedic surgeons globally. It has been hypothesized that the use of robotics enhances the accuracy of prosthesis positioning and alignment restoration. The objective of this study was to provide a high-level, evidence-based comparison between robotic total knee replacements and conventional methods, focusing on radiological and functional outcomes.MethodsWe searched five databases from their inception until June 1, 2022, specifically targeting randomized controlled trials (RCTs) that compared the outcomes of robotic and conventional total knee replacements. We were interested in outcomes such as knee range of motion, clinical and function knee society scores, the Western Ontario and McMaster University score (WOMAC), the Hospital of Special Surgery score, complications, and radiological alignment. This review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes guidelines. We assessed the risk of bias using the revised Cochrane risk-of-bias tool for randomized trials (RoB 2).ResultsOur search returned seven RCTs suitable for our analysis, which included a total of 1942 knees; 974 of these knees were implanted using robotic arms while the remaining 968 utilized jig-based knee systems. Our findings indicated that robotic knees had significantly better post-operative anatomical (OR − 0.82; 95% CI, − 1.027 to − 0.58, p value < 0.00001) and mechanical restoration (OR − 0.95; 95% CI, − 1.49 to − 0.41, p value < 0.0006). While knee range of motion (OR − 2.23; 95% CI − 4.89–0.43, p value 0.1) and femoral prosthesis position (OR − 0.98; 95% CI, − 2.03–0.08, p value 0.07) also favored robotic knees, these differences did not reach statistical significance. Both clinical and functional outcomes, as well as the rate of complications, were found to be statistically similar between the groups undergoing robotic and traditional knee replacement surgeries.ConclusionThis meta-analysis indicates that robotic total knee replacements offer superior post-operative anatomical and mechanical alignment compared to conventional total knee replacements. Despite this, clinical and functional outcomes, as well as complication rates, were similar between the two. These findings should be considered in light of potential confounding factors. More randomized controlled trials with the latest robotic systems are needed to confirm any superior functional and clinical outcomes from robotic-assisted surgeries.Level of evidenceI.

Functional Outcome of Mechanical Alignment in Total Knee Arthroplasty Surgery: A Short-Term Cohort Study at an Indian Tertiary Care Hospital.

In severe arthritis cases, goal of total knee arthroplasty (TKA) management is to attain pain-free joint and restore the overall limb alignment. There are limitedshort-term studies publishedfrom Indian hospitals that investigated the importance of neutral mechanical component alignment in TKA patients. Retrospective and prospective study was conducted at the Department of orthopaedics, Sancheti Institute for Orthopaedics and Rehabilitation, Pune from June 2020 to September 2022. Enrolled patients were assessed preoperatively and postoperatively using clinical examination, radiological assessment and functional outcomes through the Oxford knee score, Knee society score and VAS score. 204 patients enrolled, and 267 knees were evaluated for the study. Osteoarthritis was the commonest diagnosis (254 knees, 95.13%). Pre-operatively, 92.13% knees were varus, 4.87% valgus and 3% neutral while post-operatively, 51.69% were varus, 16.1% were valgus, and 32.32% were with neutral axis. Majority of patients with a pre-operative neutral axis converted to varus axis (62.5%), while most valgus axis cases preoperatively converted to a neutral axis (53.84%). For pre-operative varus subgroup, the majority patients with < 10° pre-operative axis converted to neutral (41.28%). Majority patients with 10°-20° pre-operative axis remained varus (60.53%) and with > 20° pre-operative axis remained varus (78.26%). Functional outcome parameters were significantly improved at follow-up (P < 0.05). Short-term postoperative functional scores were significantly improved in postoperative cases, with the postoperative alignment of 0° ± 3° relative to the mechanical axis was achieved. Thus, postoperative neutral mechanical alignment of 0° ± 3° can be the standard of care for patients undergoing TKA.

Valgus alignment of the femoral component is associated with higher revision rates 10years after TKA.

Appropriate positioning and alignment of tibial and femoral component in primary total knee arthroplasty (TKA) are factors of major importance directly related to patient satisfaction and implant survival. Most literature works elaborate on overall post-operative alignment and its correlation to implant survival. However, less is known about the impact of individual component alignment. The purpose of this study was to investigate the effect of undercorrection of overall alignment as well as the effect of individual tibial and femoral component alignment on the post-operative failure rate after total knee arthroplasty. Clinical and radiographic data of primary TKA cases from 2002 to 2004, with a minimum of 10-year follow-up, were retrospectively reviewed. The pre- and post-operative hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA) were measured on weight-bearing, full-length antero-posterior lower limb radiographs. Statistical analysis was performed to establish the correlation between both overall and implant alignment and revision rate. In total, 379 primary TKA cases were evaluated. The mean time of follow-up was 12.9years (range 10.3-15.9years, SD = 1.8). Nine out of 379 cases were revised due to aseptic loosening; the mean time to revision was 5.5years (range 1.0-15.5years, SD = 4.6). Varus undercorrection of overall alignment was not associated with a higher rate of revision (p = 0.316). Post-operative valgus femoral alignment (mLDFA < 87°) contributed to a significant decreased prosthesis survival in contrast to neutral femoral alignment (revision rate valgus group: 10.7% and neutral group: 1.7%; p = 0.003). Post-operative tibial mechanical alignment was not identified as a significant predictor for implant survival (revision rate varus group: 2.9% and neutral group: 2.4%; p = 0.855). Primary TKA showed significantly higher revision rates when the femoral component was placed in > 3° of valgus (mLDFA < 87°). In contrast, postoperative overall residual varus alignment (HKA) and varus alignment of the tibial component were not related to higher revision rates at a minimum 10-year follow-up after TKA. These findings should be considered when choosing component position in individualised TKA. III.

Radiological Evaluation of OrthAlign-A Novel Handheld Navigation System used in Total Knee Replacement.

The goal of this research is to determine how well OrthAlign, a novel portable navigation system for total knee replacement, helps surgeons make accurate incisions. When comparing OrthoAlign, a portable accelerometer-based technique, to the gold standard of extramedullary jigs, the results are promising. This study aimed to evaluate the accuracy of distal femoral and proximal tibial cuts in total knee arthroplasty. This research analyzed data from a prospective cohort study. Participants in the study all had resections of the proximal tibia and distal femur using the OrthAlign portable navigations device. Total knee arthroplasty (TKA) patients throughout the same time period who used traditional medullary alignment jigs were included as a control group. Before and after surgery, full-length standing stitch radiographs of the patient's lower limbs were acquired so that the alignment of their knees could be assessed. In the mechanical alignment exam done following the surgery, the OrthAlign group performed substantially better than the control group, although the difference was not statistically significant. Patients treated with OrthoAlign had considerably improved alignment of the tibial components in the coronal plane compared to those treated manually. When comparing the OrthAlign cohort to the conventional cohort, average sagittal plane alignment of tibial components was significantly different. Yet, when comparing femoral alignment after surgery, neither the mechanical alignment nor the OrthAlign groups fared better. Furthermore, there was no statistically significant difference between the two groups when it comes to the occurrence of outliers with postoperative mechanical axis alignment >3 degrees or tibial alignment in the coronal plane >2 degrees. Compared to OrthAlign, conventional alignment methods resulted in a higher percentage of postoperative tibial alignment in the sagittal plane (greater than 2 degrees). Patients whose femurs were misaligned by more than 2 degrees after surgery favored the OrthAlign method, albeit this was not statistically different from the control group. There was a significant reduction in tourniquet time for patients using OrthoAlign compared to those using mechanical alignment devices.

The influence of radiologic bone transparency after hybrid total knee arthroplasty on clinical outcomes: Minimum 6-year follow up of 214 cases

BackgroundThis study aimed to investigate how bone transparency affects loosening of the cementless femoral component by serially analyzing radiologic images in hybrid total knee arthroplasty (TKA). MethodsA total of 214 cases of TKA performed using the hybrid technique that were followed up for at least 6 years were retrospectively investigated. Bone transparency around the femoral component during the follow up period was evaluated. All TKA cases were divided into two groups and compared: those with radiologic bone transparency (bone transparency group, n = 51) and those without radiologic bone transparency (no bone transparency group, n = 163). ResultsThe incidence of revision TKA in all patients was 6.1%, and obesity, preoperative and postoperative mechanical alignment did not affect surgical outcomes. All bone transparency cases were asymptomatic, and only 8/51 cases (15.7%) of bone transparency spontaneously resolved. Between the bone transparency and no bone transparency groups, there was no difference found in the preoperative and postoperative radiologic parameters and clinical outcomes. During the follow up period, there were four (1.9%) cases with a definite radiolucent line in the femoral component, all of which belonged to the bone transparency group. ConclusionsThe bone transparency around the femoral component that appears on radiography after hybrid TKA could be an early sign of aseptic loosening; therefore, follow up serial radiography is essential.

Coronal tibiofemoral subluxation in patients with osteoarthritis was corrected after total knee arthroplasty.

The objective of this study was to investigate the effect of preoperative coronal tibiofemoral subluxation (CTFS) on postoperative mechanical alignment in patients undergoing total knee arthroplasty (TKA) for primary knee osteoarthritis (OA) and to investigate whether TKA can correct preoperative CTFS. We hypothesized that TKA would correct CTFS in patients with knee OA. A retrospective analysis of 102 patients with knee OA who underwent TKA was performed. The preoperative and postoperative CTFS and mechanical alignment were measured and compared. At the same time, the baseline values of CTFS and mechanical alignment in “normal” patients were measured and compared with those in the operation group. Eighty patients were eventually enrolled in the study. Mechanical alignment was corrected from 7.3 ± 5.2°, preoperatively, to 1.6 ± 2.3° postoperatively, while the tibiofemoral subluxation was corrected from 5.3 ± 2.6 mm, preoperatively, to 2.3 ± 2.7 mm postoperatively. There was no significant correlation between preoperative CTFS and gender (r = 0.03), BMI (r = −0.09), age (r = 0.05), or preoperative mechanical alignment (r = 0.09). In addition, there was no correlation between the degree of correction of CTFS and the degree of correction of overall mechanical alignment (r = 0.14). The difference between the value for CTFS in the “normal” patients and the preoperative value for arthritis cohorts were statistically significant (P = .004). However, no significant difference was appreciated between the value for CTFS in the “normal” patients and the postoperative value for TKA cohorts (P = .25). Preoperative CTFS does not affect postoperative mechanical alignment. Excellent TKA can correct preoperative CTFS in OA patients to reduce prosthesis wear and improve postoperative patient satisfaction.

Effect of body mass index on postoperative mechanical alignment and long-term outcomes after total knee arthroplasty: a retrospective cohort study of 671 knees.

BackgroundA high body mass index (BMI) is associated with increased rates of complications after total knee arthroplasty (TKA). However, no study has examined the effect of BMI on lower limb alignment using the World Health Organization’s (WHO) BMI classification. We believe that the WHO’s BMI classification allows a uniform standard worldwide. We sought to investigate the potential association between a high BMI and the incidence of postoperative misalignment. We also evaluated whether a higher BMI is associated with worse clinical function.MethodsWe retrospectively reviewed the data of 671 patients who underwent primary TKA for varus osteoarthritis between January 2010 and December 2015. The patients were divided into the following 5 groups based on their BMI: normal weight (<25.0 kg/m2), overweight (25.0–29.9 kg/m2), class I obese (30.0–34.9 kg/m2), class II obese (35–39.9 kg/m2), and class III obese (>40 kg/m2). Both weight and height were measured by nurses on admission. Patients’ preoperative HKA, gender, age, and side of surgery were collected as baseline. All the patients underwent standing, weight-bearing, full-length radiography before and after surgery to measure the mechanical hip-knee-ankle angle (HKA). We followed up patients by telephone. Among the BMI subgroups, we compared the knee function scores, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Knee Society-Knee Score (KS-KS), Knee Society-Function Score (KS-FS), Forgotten Joint Score (FJS), and range of motion (ROM). A multivariate linear regression analysis and a logistic regression was conducted to examine the outcomes.ResultsThe study had a mean follow-up period of 8.16 years. The multivariate and logistic regression analyses revealed that preoperative alignment (P=0.002) and a higher BMI (P=0.015) were associated with a higher risk of postoperative misalignment. The WOMAC scores were higher in the normal and overweight groups than the other groups (P=0.022). The FJS and KS-KS gradually decreased as BMI increased.ConclusionsA higher BMI is associated with a greater risk of misalignment and worse long-term clinical outcome after TKA. When treating patients with high BMI, we should pay more attention to the adjustment of lower limb alignment intraoperatively.

Accuracies of bone resection, implant position, and limb alignment in robotic-arm-assisted total knee arthroplasty: a prospective single-centre study

ObjectiveThis study assessed the accuracy of robotic-arm-assisted total knee arthroplasty (RATKA) for bone resection, component size prediction, implant placement, and limb alignment.MethodsThis prospective cohort study included 36 patients. All procedures were performed by a single experienced surgeon, using an identical approach and implant designs. The MAKO RIO Robotic Interactive Orthopaedic Arm (Stryker, Mahwah, NJ, USA) system was used. The actual bone resection, implant placement, component size, and postoperative mechanical alignment were recorded, then compared with the preoperative plan.ResultsThe mean absolute differences from the plan for the distal (medial and lateral) and posterior (medial and lateral) femoral cuts were 0.39 mm (0.62), 0.49 mm (0.70), 0.62 mm (0.79), and 0.65 mm (0.81), respectively, with 0.57° (0.65) varus. The mean absolute differences in the medial and lateral tibial cuts were 0.56 mm (0.75) and 0.58 mm (0.76), with 0.48° (0.16) varus and 0.54° (0.25) anterior/posterior slope. Of 192 bone resections, 176 (91.7%) were within ≤ 1 mm of the preoperative plan. The accuracies of femoral and tibial component size prediction were 100% and 97.22%, respectively. The mean absolute difference in final limb coronal alignment was 0.92° (0.65). Of the alignments, 18 (75.0%) were within ≤ 1.00° of the plan, and 100% were within ≤ 3.00° of the plan.ConclusionRATKA could accurately predict the component size and execute a preoperative plan to achieve precise bone resection, and implant placement, thereby reducing alignment outliers.

Effect of Limb Alignment in Medial Unicompartmental Knee Arthroplasty on Functional Outcomes and Patient Satisfaction

Background: Unicompartmental knee arthroplasty (UKA) is effective in the treatment of symptomatic unicompartmental knee osteoarthritis. However, ideal limb alignment and acceptable changes of alignment remains contentious. Purpose: The purpose of this study is to look at the impact of post-operative mechanical limb alignment on short term functional outcomes in an Asian population. Methods: We performed a retrospective review of all mobile bearing, Oxford UKAs performed from July 2016 to January 2019 by a single-surgeon (43 patients, 47 knees). Pre- and post-operative weight bearing radiographic parameters were measured, as well as functional assessments via Oxford knee society (OKS) scores and the original Knee society score (KSS). Results: The post-operative mechanical axis mean was varus 4.3° (range valgus 2° to varus 10°), with a mean correction of 4.4° towards valgus. All our patients had an improvement in functional scores and range of movement post-operatively, however, patients with pre-operative alignment of varus 15° did not meet the cut off for minimal important change (MIC) in OKS scores. More varus pre-operative alignment resulted in a larger degree of change in limb alignment post-operatively. A larger change in alignment was also associated with higher satisfaction scores in patients. Conclusion: Post-operative limb alignment of up to 10° varus does not compromise short term functional outcome scores in medial UKA. Caution is advised when selecting patients with varus 15° and above for UKA as they may not be able to achieve a minimal important change in functional scores post-operatively.

Accelerometer-Based Navigation versus Conventional Total Knee Arthroplasty for Posttraumatic Knee Osteoarthritis.

Posttraumatic osteoarthritis (PTOA) frequently comprises femoral or tibial deformity, which makes it difficult to perform total knee arthroplasty (TKA). Accelerometer-based navigation (ABN) could be effective in restoring a neutral mechanical axis (MA) in TKA, but a limited number of studies have been reported in association with PTOA. Therefore, we aimed to compare the lower limb MA between ABN-assisted TKA (ABN-TKA) and conventional TKA in patients with PTOA. We conducted a retrospective analysis of 28 PTOA patients who underwent TKA using a conventional system (cTKA group, n = 16) and the ABN system (iTKA group, n = 12). Standing long-leg radiographs were assessed for MA and prosthesis alignment as primary outcomes. A postoperative MA deviating beyond ± 3° was defined as an outlier. Perioperative outcomes, Oxford Knee Score (OKS) at 2-year follow-up, and complications were also assessed. The cTKA group and the iTKA group had a mean age of 63.07 years and 65.25 years, respectively. The iTKA group had significantly better MA accuracy when compared to the cTKA group (1.60° ± 2.09° vs. 3.59° ± 1.34°, p = 0.01). The iTKA group showed significantly less MA outlier than the cTKA group (78.6% vs. 25.0%, p = 0.02). The prosthesis alignment and OKS were comparable between the groups. There were 2 periprosthetic joint infections in the cTKA group and 1 periprosthetic fracture of the distal femur in the iTKA group. For PTOA of the knee, both conventional TKA and ABN-TKA significantly improved the postoperative mechanical alignment and functional outcomes. The ABN-TKA seemed to offer higher accuracy and less MA outlier when compared to conventional TKA, and thus ABN could be a good alternative option.

Increased patellar bone tracer uptake in preoperative SPECT/CT before medial opening high tibial osteotomy correlates with inferior clinical outcome

PurposeThe purpose of this study was to investigate whether specific bone tracer uptake (BTU) patterns on preoperative SPECT/CT could predict which patients with varus alignment and medial overload would particularly benefit from medial opening-wedge high tibial osteotomy (MOWHTO). It was the hypothesis that an increased preoperative BTU relative to the reference BTU of the femur on SPECT/CT in the lateral and patellar compartments of the knee are predictive factors for inferior clinical outcome and that the clinical outcome correlates with the extent of alignment correction.MethodsTwenty-three knees from 22 patients who underwent MOWHTO for medial compartment overload were investigated preoperatively using Tc-99m-SPECT/CT. BTU was quantified and localised to specific joint areas according to a previously validated scheme. Pre- and postoperative mechanical alignment was measured. Clinical outcome was assessed at a median of 24 months (range 11–30) after MOWHTO by collecting the WOMAC score.ResultsSignificant correlations between BTU in the patellar area and the total WOMAC score and its subcategories pain and stiffness were found. Thus, BTU in the 1sPat area (superior lateral patellar compartment) correlated with total WOMAC (rho = 0.43, p = 0.04), pain subcategory (rho = 0.43, p = 0.04), and stiffness subcategory (rho = 0.59, p = 0.003). No significant correlations were found between alignment correction, age, gender and WOMAC.ConclusionThis study highlights the role of preoperative SPECT in modern knee surgery to obtain information about the loading pattern on different compartments of the knee. Despite the limited number of participants, the present study shows that a preoperative SPECT/CT scan can help the treating surgeons to identify patients who may be at risk of inferior clinical outcome if an MOWHTO is considered, as an elevated BTU in the patellar region on preoperative SPECT/CT appears to be a potential risk factor for postoperative pain and stiffness.Level of evidenceLevel III.

Association of HSS score and mechanical alignment after primary TKA of patients suffering from constitutional varus knee that caused by combined deformities: a retrospective study

For pre-operative osteoarthritis (OA) patients with varus knee, previous studies showed inconsistent results. Therefore, we conducted this study to better identify the association of Hospital for Special Surgery (HSS) score and mechanical alignment. 44 patients (51 knees) with constitutional varus knee caused by combined deformities (LDFA (lateral distal femoral angle) > 90°and MPTA (medial proximal tibial angle) < 85°)) were selected and analyzed with a mean follow-up period of 14 months after total knee arthroplasty (TKA). From January 2015 to December 2016, patients were collected consecutively after primary TKA. After filtering, fifty-one knees (44patients) were analyzed with a mean follow-up period of 14 months. All patients were divided into two groups based on post-operative hip-knee-ankle (HKA) acute angle: varus mechanical alignment (VMA) group (HKA < − 3°) and neutral mechanical axis (NMA) group (− 3° ≤ HKA ≤ 3°). 30 knees were included in the NMA group, and 21 knees in the VMA group. Comparisons of HSS between NMA group and VMA group were performed. After adjusting for age and Body Mass Index (BMI) confounders, Compared with NMA group, the HSS score in VMA group decreased by 0.81 units (95% CI, − 3.37 to 1.75) p = 0.5370). For pre-operative constitutional varus knee caused by combined deformities in chinese populations, no significant association between post-operative lower limb mechanical alignment and HSS score was found.

Tibial Cut Accuracy in Mechanically Aligned Total Knee Arthroplasty Using Extensor Hallucis Longus Tendon to Determine Extramedullary Tibial Guide Position.

This study aimed to determine the tibial cut (TC) accuracy using extensor hallucis longus (EHL) tendon as an anatomical landmark to position the total knee arthroplasty (TKA) extramedullary tibial guide (EMTG), and its impact on the TKA mechanical alignment (MA). We retrospectively studied 96 TKA, performed by a single surgeon, using a femoral tailored intramedullary guide technique. Seventeen were prior to the use of the EHL and 79 used the EHL tendon to position the EMTG. We analyzed preoperative and postoperative standing total lower extremity radiographs to determine the tibial component angle (TCA) and the correction in MA, comparing pre-EHL use and post-EHL technique incorporation. Mean TCA was 88.89 degrees and postoperative MA was neutral in 81% of patients. Pre- and postoperative MAs were not correlated. As a conclusion of this study, using the EHL provides a safe and easy way to determine the position of EMTG.

Effect of Coronal Alignment on 10-Year Survivorship of a Single Contemporary Total Knee Arthroplasty.

Debate remains regarding the utility of mechanical axis alignment as a predictor of durability after total knee arthroplasty (TKA). Our study aimed to assess the effects of coronal alignment on implant durability, clinical outcomes, and radiographic results with a single fixed-bearing TKA design. All patients undergoing primary cemented TKA of a single design (Stryker Triathlon) from 2005–2007 with >10 years of follow-up and available pre-operative and post-operative hip–knee–ankle radiographs were included (n = 89). Radiographs were measured to determine coronal alignment and assessed for loosening. Mean preoperative mechanical axis alignment was −6° ± 6.7° (varus, range, −16°–23°), while mean post-operative alignment was −1° ± 2.7° (varus, range, −3°–15°). The aligned group was defined as knees with a post-operative mechanical axis of 0° ± 3° (n = 73) and the outlier group as those outside this range (n = 16). No patients underwent revision. Ten-year survivorship free from any reoperation was 99% and 100% in the aligned and outlier groups, respectively (p = 0.64). Knee Society scores improved significantly in both groups (p < 0.001) and did not differ at final follow-up (p = 0.15). No knees demonstrated radiographic evidence of loosening. Post-operative mechanical axis alignment within 3° of neutral was not associated with improved implant durability, clinical outcomes, or radiographic results at 10 years following primary TKA.

Postoperative alignment in revision total knee arthroplasty, a comparison between intra and extra-medullary tibial alignment

BackgroundRevision total knee arthroplasty commonly involves stemmed components. If the diaphysis is engaged, this technique may be problematic for mechanical alignment (MA) in cases of tibial bowing, which are not infrequent (up to 30%).The aim of this study is to compare an intra-medullary(IM) and extra-medullary(EM) alignment method. We hypothesized that IM technique and canal-filling stems may result more frequently in valgus MA. On the other hand, an EM technique could produce less valgus knees but is at risk of creating MA outliers. MethodA retrospective radiographic analysis of revision TKAs was performed. The patients were divided to either the EM or IM alignment group and compared on the overall post-operative MA. The following parameters were measured on standing, long leg x-rays: Hip-knee-Ankle angle (HKA), mechanical lateral distal femoral angle and mechanical medial proximal tibial angle (mMPTA). Results119 cases of revision TKAs were included (EM = 80, IM = 39). There was a difference between the EM and IM group for the mean mMPTA (89.94° vs 90.92°, effect size = 0.45, p = 0.013) and HKA angle (1.64° vs 0.05°, effect size = 0.52, p = 0.0064). A higher proportion of IM patients were in overall valgus alignment (16/39, 41%) vs EM group (16/80, 20%, p = 0.0134). Both techniques showed the same proportion of outliers, defined as HKA angle more than 5 degrees from neutral mechanical alignment (11/80 vs 5/39, p = 0.286). ConclusionThe extra-medullary alignment method with short cemented stems creates less valgus mechanical alignment than the intra-medullary technique with press-fit stems, without creating more MA outliers.

Comparison of Clinical, Functional, and Radiological Outcomes of Total Knee Arthroplasty Using Conventional and Patient-Specific Instrumentation.

Recently, patient-specific instrumentation (PSI) systems have been developed in order to increase the accuracy of component positioning during total knee arthroplasty (TKA); however, the findings of previous studies are controversial in this regard. In the current randomized clinical study, the outcomes of computer tomography (CT)-based PS (patient specific)-guided TKA were compared to the results of conventional instrumentation (CVI) TKA. The guides were designed on the basis of distal femoral and proximal tibial pin orientation of the conventional related guides. The present study was carried out on 24 TKA candidates randomly assigned to two PSI (n=12) and CVI (n=12) groups. The patients were postoperatively followed for 2 years. Then, the hip-knee-ankle angle (HKAA), femoral component flexion, and orientation of components in the coronal plane were measured. In addition, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index and Knee Society Score (KSS) questionnaire were completed for all the patients. The rate of the outliers of the HKAA was higher in the CVI group (41.7% and 8.3%; P=0.077); nevertheless, the difference was not significant in this regard. The rate of the outliers of other radiographic measurements and operational time were similar in both groups. Furthermore, there was no significant difference between the two groups in terms of the WOMAC and KSS. The CT-based PS-guided TKA may result in the improved postoperative mechanical alignment of the limb and should be considered in complicated TKAs. However, future studies should investigate whether the results of PSI TKA support the considerably higher costs of this technique.

L’alignement frontal après prothèse totale du genou a une influence significative sur la survie contrairement à l’incurvation frontale de la diaphyse fémorale

BackgroundFemoral coronal bowing (FCB) has been reported to be a risk factor for mechanical malalignment after total knee arthroplasty (TKA). However, the effects of FCB on the long-term survivorship (when postoperative mechanical alignment (MA) is neutral after TKA) have not been determined. HypothesisThe effects of FCB on the cumulative survivorship after TKA may be significantly smaller compared with those of MA. Patients and methodsConsecutive 328 knees of 211 patients (10 males, 201 females) who underwent TKA between 1995 and 2009 (mean age of 64.2±6.7 years at the time of TKA, mean follow-up period of 11.9±2.5 years) were retrospectively evaluated. FCB and MA were evaluated using preoperative and immediate postoperative whole-leg anteroposterior radiographs, respectively. The patients were grouped according to FCB and postoperative MA, which included group A (FCB≤5°, MA≤3°), B (FCB>5°, MA≤3°), C (FCB>5°, MA>3°), and D (FCB≤5°, MA>3°). Primary end-point was defined as aseptic mechanical failures requiring revision TKA. Survivorship was assessed using the Kaplan–Meier method and compared using log-rank tests. Factors associated with the risk of aseptic mechanical failures were analyzed by Cox regression analysis. Preoperative and final follow-up clinical outcomes were assessed using Hospital for Special Surgery (HSS) scores. ResultsGroup A, B, C, and D included 190, 73, 40, and 25 knees, respectively. The 10-year survivorship was similar between group A and B (96.3±1.4 vs. 98.6±1.4%; p=0.733) and group C and D (87.3±5.3 vs. 87.6±6.7%; p=0.974); however, it was significantly higher in group B than in group C (p=0.036) and in group A than in group D (p=0.005). Age (OR=0.991; 95% CI 0.906–1.085; p=0.002) and MA>3° (OR=3.645; 95% CI 1.744–7.604; p=0.001) were associated with the risk of aseptic mechanical failures. The mean preoperative and final HSS scores in the four groups were not significantly different. DiscussionMarked FCB was not associated with long-term survivorship for knees with neutral alignment after TKA. However, non-neutral postoperative alignment reduced long-term survivorship for knees with marked FCB. Level of evidenceIII, Retrospective comparative cohort study.

Clinical and Radiological Outcomes in Robotic-Assisted Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BackgroundThe aim of this systematic review is to determine if robotic-assisted total knee arthroplasty (RATKA) results in improved clinical and radiological outcomes, and to elucidate the breadth and depth of studies conducted on this topic. MethodsA Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review was conducted using 4 databases (MEDLINE, EMBASE, Cochrane, and Web of Science) to identify all clinical studies that investigate clinical or radiological outcomes using RATKA. The Critical Appraisal Skills Program checklist for cohort studies was employed for critical appraisal and evaluation of all 22 studies that met the inclusion criteria. ResultsAll studies reviewed determined that knee arthroplasty improved clinical outcomes. Twelve studies found statistically better clinical outcomes with RATKA compared with conventional TKA, whereas 9 studies found no difference. One study did not assess clinical outcomes. When assessing radiological outcomes, 14 studies reported that RATKA resulted in more consistent and accurate postoperative mechanical alignment, whereas 2 studies reported no difference. Six studies did not assess radiological outcomes. ConclusionAlthough knee arthroplasty is one of the most commonly performed orthopedic operations, the level of patient satisfaction varies. The meta-analyses conducted in our systematic review shows that RATKA results in greater improvements in postoperative Hospital for Special Surgery score and Western Ontario and McMaster Universities scores compared to conventional TKA. Furthermore, it shows that RATKA results in more accurate postoperative alignment of prostheses. These together can explain the improved postoperative outcomes. More randomized controlled trials must be conducted before this technique is integrated into routine clinical practice.

Postoperative alignment but not femoral coronal bowing is a significant longevity factor after total knee arthroplasty

BackgroundFemoral coronal bowing (FCB) has been reported to be a risk factor for mechanical malalignment after total knee arthroplasty (TKA). However, the effects of FCB on the long-term survivorship (when postoperative mechanical alignment (MA) is neutral after TKA) have not been determined. HypothesisThe effects of FCB on the cumulative survivorship after TKA may be significantly smaller compared with those of MA. Patients and methodsConsecutive 328 knees of 211 patients (10 males, 201 females) who underwent TKA between 1995 and 2009 (mean age of 64.2±6.7 years at the time of TKA, mean follow-up period of 11.9±2.5 years) were retrospectively evaluated. FCB and MA were evaluated using preoperative and immediate postoperative whole-leg anteroposterior radiographs, respectively. The patients were grouped according to FCB and postoperative MA, which included group A (FCB≤5°, MA≤3°), B (FCB>5°, MA≤3°), C (FCB>5°, MA>3°), and D (FCB≤5°, MA>3°). Primary end-point was defined as aseptic mechanical failures requiring revision TKA. Survivorship was assessed using the Kaplan-Meier method and compared using log-rank tests. Factors associated with the risk of aseptic mechanical failures were analyzed by Cox regression analysis. Preoperative and final follow-up clinical outcomes were assessed using Hospital for Special Surgery (HSS) scores. ResultsGroup A, B, C, and D included 190, 73, 40, and 25 knees, respectively. The 10-year survivorship was similar between group A and B (96.3±1.4% vs. 98.6±1.4%; p=0.733) and group C and D (87.3±5.3 vs. 87.6±6.7%; p=0.974); however, it was significantly higher in group B than in group C (p=0.036) and in group A than in group D (p=0.005). Age (OR=0.991; 95% CI 0.906–1.085; p=0.002) and MA>3° (OR=3.645; 95% CI 1.744–7.604; p=0.001) were associated with the risk of aseptic mechanical failures. The mean preoperative and final HSS scores in the four groups were not significantly different. DiscussionMarked FCB was not associated with long-term survivorship for knees with neutral alignment after TKA. However, non-neutral postoperative alignment reduced long-term survivorship for knees with marked FCB. Level of evidenceIII, Retrospective comparative cohort study.

Convincing long-term results independent from the postoperative leg alignment following cementless total knee arthroplasty

BackgroundCementless primary total knee arthroplasty shows numerous advantages compared with cemented implants (e.g., shorter operation time, preservation of the bone stock). Up to now an increasing number of clinical long-term studies exist. Despite this fact, there is no evidence about the influence of the postoperative leg alignment on the results of cementless knee arthroplasty. There is no work on the clinical outcome of the specific implant, which was used in this study (VANGUARD®, ZimmerBiomet). The purpose of this study was to assess the clinical and radiological long-term results after cementless knee arthroplasty in relation to the postoperative mechanical leg alignment. MethodsClinical and radiological results were retrospectively assessed in 83 patients at 10.3 years (ranging from 9.6 to 11.8 years) after implantation. Hip-knee-ankle angle (HKA) was measured, and the patients were separated into a corrected (HKA between three degrees of varus and three degrees of valgus, n = 60) and a varus/valgus (HKA > 3° of varus and valgus, n = 23) group. ResultsUp to the time of the clinical follow-up, three out of 83 patients already underwent a revision surgery due to a deep infection (3.6%). Tegner–Lysholm Knee scale was 89.1 in the corrected group and 88.8 in the varus/valgus group (p = .94). The mean Knee Injury and Osteoarthritis Outcome score (KOOS) was 81.2 in the corrected group and 82.4 in the varus/valgus group (p = .63). ConclusionsResults of this study showed convincing clinical and radiological results after primary cementless knee arthroplasty. Under- or overcorrected postoperative mechanical leg alignments did not influence the long-term clinical results.