Component alignment and functional outcome following computer assisted and jig based total knee arthroplasty

Background:

Incorrect positioning of the implant and improper alignment of the limb following total knee arthroplasty (TKA) can lead to rapid implant wear, loosening, and suboptimal function. Studies suggest that alignment errors of > 3° are associated with rapid failure and less satisfactory function. Computer navigated systems have been developed to enhance precision in instrumentation during surgery. The aim of the study was to compare component alignment following computer assisted surgery (CAS) and jig based TKA as well as functional outcome.

Materials and Methods:

This is a prospective study of 100 knees to compare computer-assisted TKA and jig-based surgery in relation to femoral and tibial component alignment and functional outcome. The postoperative x-rays (anteroposterior and lateral) of the knee and CT scanogram from hip to foot were obtained. The coronal alignment of the femoral and tibial components and rotational alignment of femoral component was calculated. Knee society score at 24 months was used to assess the function.

Results:

Results of our study show that mean placement of the tibial component in coronal plane (91.3037°) and sagittal planes (3.6058°) was significantly better with CAS. The difference was statistically insignificant in case of mean coronal alignment of the femoral components (90.34210° in navigation group and 90.5444° in jig group) and in case of the mean femoral condylar twist angle (external rotation 2.3406° in navigation group versus 2.3593° in jig group).

Conclusions:

A significantly improved placement of the component was found in the coronal and sagittal planes of the tibial component by CAS. The placement of the components in the other planes was comparable with the values recorded in the jig-based surgery group. Functional outcome was not significantly different.     

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.     

Evaluation of patellofemoral joint in ADVANCE® Medial-pivot total knee arthroplasty

Purpose

ADVANCE® Medial Pivot (MP) (Wright Medical) total knee arthroplasty (TKA) was established to replicate normal tibio-femoral knee joint kinematics, however, its influence on the patello-femoral (PF) joint is unclear. The purpose in this study was to assess the PF joint conditions in Advance MP TKA, via radiography and three-dimensional image-matching software.

Methods

Ten subjects with osteoarthritis were treated with the ADVANCE MP TKA. Pre-operatively and one month after surgery, skyline views at 30, 60, and 90° of flexion were taken, and patella shift and tilt were measured. With 2D–3D registration techniques using software, implant orientations were matched with the pre-operative CT and changes in the anterior part of the femoral prosthesis, condylar twist angle (CTA) for femoral rotation, and tibial rotation were evaluated. The relationships between morphological and rotational changes were evaluated.

Results

There were significant differences in patella tilt at 60° and patella shift at all angles between pre- and post-operation (p < 0.05). No correlation was found between morphological changes in the anterior femur with patella tilt and shift. A positive correlation between postoperative CTA and patella shift at 90° was found (p < 0.05); however, no correlation was found between rotational alignment of the tibial component and patella tilt and shift.

Conclusions

ADVANCE MP TKA changed patello-femoral joint kinematics, compared to that found before surgery. The kinematic features were mainly due to the design concepts for tibio-femoral joint motion, indicating the difficulty to reproduce normal patello-femoral joint kinematics after TKA.     

Total knee arthroplasty after high tibial osteotomy: a comparison of opening and closing wedge osteotomy

Purpose

High tibial osteotomy (HTO) is frequently used to treat varus osteoarthritis in younger patients with the goal of delaying the need for total knee arthroplasty (TKA). While it has been reported that the results of TKA following HTO are worse than those in patients without prior knee surgery, the influence of osteotomy technique (medial opening-wedge versus lateral closing-wedge) has not been explored. The purpose of this study was to evaluate the influence of HTO technique on the performance and results of TKA.

Methods

A total of 141 TKA’s performed in 118 patients with prior HTO (24 opening wedge and 117 closing wedge) were reviewed at a mean follow-up of two years. Reviewed data included intra-operative factors (tourniquet time, the need for additional exposure, and intra-operative complications), clinical results (International Knee Score (IKS)) and radiographic assessment of limb alignment.

Results

The average IKS knee and function scores improved from 54.0 and 60.3 to 87.0 and 79.5 (p <  0.0001). There was no significant difference in IKS scores based on osteotomy technique. There was a trend toward an increased need for tibial tubercle osteotomy in the closing wedge group. There was an increased need for extensive medial release in the opening wedge group and extensive lateral release in the closing wedge group. No differences in tourniquet time, complication rates, or hip-knee-ankle angle were noted between the two groups.

Conclusions

Radiographic limb alignment, patient-reported outcomes, and complication rates are equal in patients undergoing TKA after opening and closing wedge HTO.     

Impact of the tibial slope on range of motion after low-contact-stress,mobile-bearing,total knee arthroplasty

Purpose

The aim of this study was to analyse a possible correlation between the tibial slope and range of motion (ROM) after implantation of the low-contact-stress (LCS), mobile-bearing, total knee arthroplasty (TKA) after a minimum follow-up of ten years.

Methods

Eighty-three TKAs in 66 patients were investigated in this retrospective correlation analysis at a minimum follow up of ten years. Out of these 66 patients, 50 were women (76 %) and 16 (24 %) were men. The average age of these patients at the time of the examination was 76 years [standard deviation (SD) 11 years, range 37–95 years]. A lateral X-ray was taken at follow-up in order to analyse the tibial slope with respect to inter- and intra-observer agreement. ROM was measured and correlated with the tibial slope.

Results

The mean active ROM was 96.1° (SD 18.8) and the mean tibial slope after four measurements was 7.65° (SD 4.23), with substantial inter- and intra-observer agreement. We found no significant correlation between tibial slope and ROM in patients with a minimum follow-up of ten years [correlation 0.196 (p > 0.05) and 0.152, (p > 0.05), respectively].

Conclusions

Alteration of the tibial slope does not significantly influence ROM after implantation of the LCS TKA at a minimum follow-up of ten years. We conclude that the tibial slope is not the primary influencing factor for ROM in patients ten years after primary TKA and believe that it should not substantially be altered during surgery.     

Are MRI-based,patient matched cutting jigs as accurate as the tibial guides?

Purpose

The aim of this study is to evaluate the accuracy of VISIONAIRE (Smith & Nephew Inc., Memphis, TN, USA) Patient Matched cutting tibial jigs in comparison with extramedullary (EM) tibial instrumentation by analysing data as detected by intra-operative use of VectorVision knee navigation software from BrainLAB (Redwood City, CA, USA).

Methods

Twelve patients were selected for unilateral total knee replacement (TKR). They underwent a full-length weight-bearing anteroposterior (AP) radiograph and magnetic resonance imaging (MRI). During surgery, once the EM guides were placed and fixed on the tibia, the orientation in the coronal and sagittal planes was checked by the navigator and then compared with the data obtained by measuring the orientation of VISIONAIRE Patient Matched cutting tibial jigs. An unsatisfactory result was considered an error ≥2° in both coronal and sagittal planes for the tibial component as a possible error of 4° could result.

Results

In the coronal plane the mean deviation of the EM tibial guides from the ideal alignment (0°) was 0.7 ± 0.39° and of the VISIONAIRE was 129 ± 1.55° (P = 0.22). In the sagittal plane the mean deviation of the EM tibial guides from 3° of posterior slope was −1.62 ± 1.78° and of the VISIONAIRE was +1.16 ± 4.29° (P < 0.05). Negative values indicate a more posterior slope from the ideal and positive values an anterior slope.

Conclusions

This preliminary study documented only a fair accuracy of the method with a consistent risk of error of more of 3° especially in the sagittal plane. We could speculate that the problem in the sagittal plane was due to the fact that the pre-operative protocol does not include a lateral X-ray projection of the knee and only includes an AP standing X-ray of the straight leg and MRI.     

Accuracy of Individualized Custom Tibial Cutting Guides in UKA

Background

Component malposition is one of the major reasons for early failure of unicompartmental knee arthroplasty (UKA).

Questions/Purposes

It was investigated how reproducibly patient-specific instrumentation (PSI) achieved preoperatively planned placement of the tibial component in UKA specifically assessing coronal alignment, slope and flexion of the components and axial rotation.

Patients and Methods

Based on computer tomography models of ten cadaver legs, PSI jigs were generated to guide cuts perpendicular to the tibial axis in the coronal and sagittal planes and in neutral axial rotation. Deviation ≥3° from the designed orientation in a postoperative CT was defined as outside the range of acceptable alignment.

Results

Mean coronal alignment was 0.4 ± 3.2° varus with two outliers. Mean slope was 2.8 ± 3.9° with six components in excessive flexion. It was noted that the implants were put in a mean of 1.7 ± 8.0° of external rotation with seven outliers

Conclusions

PSI helped achieve the planned coronal orientation of the component. The guides were less accurate in setting optimal tray rotation and slope.

Electronic supplementary material

The online version of this article (doi:10.1007/s11420-014-9410-z) contains supplementary material, which is available to authorized users.     

Posterior hemivertebra resection and monosegmental fusion in the treatment of congenital scoliosis

INTRODUCTION

Posterior hemivertebra resection combined with multisegmental or bisegmental fusion has been applied successfully for congenital scoliosis. However, there are several immature bones and their growth can be influenced by long segmental fusion in congenital patients. Posterior hemivertebra resection and monosegmental fusion was therefore suggested for treatment of congenital scoliosis caused by hemivertebra.

METHODS

Between June 2001 and June 2010, 60 congenital scoliosis patients (aged 2–18 years) who underwent posterior hemivertebra resection and monosegmental fusion were enrolled in our study. A standing anteroposterior x-ray of the whole spine was obtained preoperatively, postoperatively and at the last follow-up appointment to analyse the Cobb angle in the coronal and sagittal planes as well as the trunk shift.

RESULTS

The mean preoperative coronal plane Cobb angle was 41.6º. This was corrected to 5.1º postoperatively and 5.3º at the last follow-up visit (correction 87.3%). The compensatory cranial curve was improved from 18.1º preoperatively to 7.1º postoperatively and 6.5º at the last follow-up visit while the compensatory caudal curve was improved from 21.5º to 6.1º after surgery and 5.6º at the last follow-up visit. The mean sagittal plane Cobb angle was 23.3º before surgery, 7.3º after surgery and 6.8º at the last follow-up visit (correction 70.1%). The trunk shift of 18.5mm was improved to 15.2mm.

CONCLUSIONS

Posterior hemivertebra resection and monosegmental fusion seems to be an effective approach for treatment of congenital scoliosis caused by hemivertebra, allowing for excellent correction in both the frontal and sagittal planes.     

Revision knee arthroplasty with a rotating-hinge design in elderly patients with instability following total knee arthroplasty

Background

Revision knee arthroplasty with a rotating-hinge design could be an option for the treatment of instability following total knee arthroplasty (TKA) in elderly patients.

Purpose

To evaluate the clinical and radiographic results of revision arthroplasties in TKAs with instability using a rotating-hinge design in elderly patients.

Methods

We retrospectively reviewed 96 rotating-hinge arthroplasties. The average age of the patients was 79 years (range, 75–86 years); the minimum follow-up was 5 years (mean, 7.3 years; range, 5–10 years). Patients were evaluated clinically (Knee Society score) and radiographically (position of prosthetic components, signs of loosening, bone loss).

Results

At a minimum followup of 5 years (mean, 7.3 years; range, 5–10 years), Knee Society pain scores improved from 37 preoperatively to 79 postoperatively, and function scores improved from 34 to 53. ROM improved on average from −15° of extension and 80° of flexion before surgery to −5° of extension and 120° of flexion at the last followup (p = 0.03). No loosening of implants was observed. Nonprogressive radiolucent lines were identified around the femoral and tibial components in 2 knees. One patient required reoperation because of a periprosthetic infection.

Conclusions

Revision arthroplasty with a rotating-hinge design provided substantial improvement in function and a reduction in pain in elderly patients with instability following TKA.

Level of evidence

Level IV, therapeutic study.     

CT- versus MRI-based patient-specific instrumentation for total knee arthroplasty: A systematic review and meta-analysis

Background

To determine whether computed tomography (CT) or magnetic resonance imaging (MRI) is more suitable for the patient-specific instrumentation (PSI) systems for total knee arthroplasty (TKA).

Functional Impairment Is a Risk Factor for Knee Replacement in the Multicenter Osteoarthritis Study

Background

Debilitating pain associated with knee osteoarthritis (OA) often leads patients to seek and complete total knee arthroplasty (TKA). To date, few studies have evaluated the relation of functional impairment to the risk of TKA, despite the fact that OA is associated with functional impairment.

Questions/purposes

The purpose of our study was to (1) evaluate whether function as measured by WOMAC physical function subscale was associated with undergoing TKA; and (2) whether any such association varied by sex.

Methods

The National Institutes of Health-funded Multicenter Osteoarthritis Study (MOST) is an observational cohort study of persons aged 50 to 79 years with or at high risk of symptomatic knee OA who were recruited from the community. All eligible subjects with complete data were included in this analysis. Our study population sample consisted of 2946 patients with 5796 knees; 1776 (60%) of patients were women. We performed a repeated-measures analysis using baseline WOMAC physical function score to predict the risk of TKA from baseline to 30 months and WOMAC score at 30 months to predict risk of incident TKA from 30 months to 60 months. We used generalized estimating equations to account for the correlation between two knees within an individual and across the two periods. We calculated relative risk (RR) of TKA over 30 months by WOMAC function using a score of 0 to 5 as the referent in multiple binomial regressions with log link.

Results

Those with the greatest functional impairment (WOMAC scores 40–68; 62 TKAs in 462 knee periods) had 15.5 times (95% confidence interval [CI], 7.6–31.8; p < 0.001) the risk of undergoing TKA over 30 months compared with the referent group (12 TKAs in 3604 knee periods), adjusting for basic covariates, and 5.9 times (95% CI, 2.8–12.5; p < 0.001) the risk after further adjusting for knee pain severity. At every level of functional limitation, the RR for TKA for women was higher than for men, but interaction with sex did not reach significance after adjustment for covariates including ipsilateral pain (p = 0.138).

Conclusions

Baseline physical function appears to be an important element in patients considering TKA. Future studies should examine whether interventions to improve function can reduce the need for TKA.

Level of Evidence

Level III, observational cohort study.     

Computer-assisted FluoroGuide navigation of unicompartmental knee arthroplasty

Background

Most authorities recognize minimally invasive unicompartmental knee arthroplasty (UKA) as technically demanding with concerns regarding loss of implantation accuracy. We have previously reported on the potential inaccuracy of femoral intramedullary guides in UKA leading to poor component positioning. Our 3-dimensional analysis of alignment error showed that a short, narrow intramedullary rod inserted according to the manufacturer’s specifications did not accurately find the direction of the anatomic axis, with errors occurring in both the coronal and sagittal planes. We sought to evaluate whether a fluoroscopic computer-assisted minimally invasive UKA procedure would improve the accuracy and precision in the placement of the femoral component in the coronal and sagittal planes compared with conventional surgery.

Methods

We performed a prospective study involving cohorts of 45 conventional versus 53 navigated UKAs. A single surgeon performed all surgeries over a 4-year period.

Results

Pain and knee function significantly improved in both surgical groups at 1 and 2 years after surgery. At a minimum of 1-year follow-up, radiographic evaluation revealed significant improvements in coronal alignment precision of the tibial component (p = 0.026) and sagittal alignment precision of the femoral component for the navigated group (p = 0.037). The use of a fluoroscopic computer-assisted technique did not significantly improve the accuracy of any of the alignment angles.

Conclusion

We cannot justify the additional expense and complexity imposed by fluoroscopic navigation despite the observed improvements in alignment precision. Improved positioning precision may translate into a greater number of long-term functional results, but larger, longer-term studies are needed.     

Comparison of the major intraoperative and postoperative complications between unilateral and sequential bilateral total knee arthroplasty in a high-volume community hospital

Background

Total knee arthroplasty (TKA) is a common surgical treatment for arthritis. In the event of bilateral knee symptoms, a patient may elect for bilateral TKA (BTKA) under 1 anesthetic or 2 separate unilateral TKAs (UTKA). Controversy exists in the literature regarding the safety of BTKA versus UTKA. We compared the rate of major intraoperative and postoperative complications for BTKA versus UTKA at a high-volume community hospital.

Methods

We compared 373 patients who underwent BTKA with 966 who underwent UTKA between May 2008 and May 2011. Health records were used to determine patient characteristics and major intraoperative and postoperative complications. The BTKA and UTKA cohorts were matched for demographic characteristics and comorbidities with the exception of previous transient ischemic attack and previous knee surgery (UTKA > BTKA).

Results

Rates of intraoperative and postoperative complications, including cardiovascular, thromboembolic and neurologic complications; deep wound infections; and mortality, did not differ significantly between groups. Bilateral TKA was associated with a greater proportion of patients requiring blood transfusion than UTKA (29.8% v. 8.9%, p < 0.001). Among those transfused, there was no significant difference between the groups in the mean number of units required (1.72 ± 0.77 v. 1.53 ± 0.85 units, p = 0.68).

Conclusion

Bilateral TKA was not associated with statistically greater rates of intra-operative and postoperative complications than UTKA, barring the proportion of patients requiring transfusion. Our results support the use of BTKA to treat bilateral knee arthritis in a high-volume community hospital setting.     

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.

Electronic supplementary material

The online version of this article (doi:10.1007/s11999-014-3688-5) contains supplementary material, which is available to authorized users.     

Anterolateral approach using tibial tubercle osteotomy for total knee arthroplasty: can we predict failure?

Purpose

The purpose of this study was to identify predictive factors for the occurrence of complications in a consecutive series of patients who underwent step-cut tibial tubercle osteotomy (TTO) and subsequent screw refixation in primary total knee arthroplasty (TKA).

Methods

Using standardised conventional radiographs, critical parameters including TTO length and depth, proximal abutment width (OT), and orientation and placement of fixation screws were measured in 422 patients (mean age of 71 years and a follow-up time range of one to five years) with two screw fixations.

Results

Medial spatial orientation in the distal screw (11 %, p=0.046), the TTO length (<55.4 mm, p=0.013), the OT width (<14 mm, p=0.002) and the distance of the distal refixation screw from the TKA (<51.7 mm, p=0.003) were significant factors for the occurrence of complications.

Conclusions

Age, gender, comorbidities, height, weight and/or the body mass index had no significant influence on the occurrence of complications. The TTO-related complication rate was 3 %. Consideration of these key surgical factors leads to improved outcomes.     

Risk of Anterior Femoral Notching in Navigated Total Knee Arthroplasty

Background

We retrospectively investigated the prevalence of femoral anterior notching and risk factors after total knee arthroplasty (TKA) using an image-free navigation system.

Methods

We retrospectively reviewed 148 consecutive TKAs in 130 patients beginning in July 2005. Seventy knees (62 patients) underwent conventional TKA, and 78 knees (68 patients) received navigated TKA. We investigated the prevalence of femoral anterior notching and measured notching depth by conventional and navigated TKA. Additionally, the navigated TKA group was categorized into two subgroups according to whether anterior femoral notching had occurred. The degree of preoperative varus deformity, femoral bowing, and mediolateral suitability of the size of the femoral component were determined by reviewing preoperative and postoperative radiographs. The resection angle on the sagittal plane and the angle of external rotation that was set by the navigation system were checked when resecting the distal femur. Clinical outcomes were compared using range of motion (ROM) and the Hospital for Special Surgery (HSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAX) scores between the two groups.

Results

The prevalence of anterior femoral notching by conventional TKA was 5.7%, and that for navigated TKA was 16.7% (p = 0.037). Mean notching depth by conventional TKA was 2.92 ± 1.18 mm (range, 1.8 to 4.5 mm) and 3.32 ± 1.54 mm (range, 1.55 to 6.93 mm) by navigated TKA. Preoperative anterior femoral bowing was observed in 61.5% (p = 0.047) and both anterior and lateral femoral bowing in five cases in notching group during navigated TKA (p = 0.021). Oversized femoral components were inserted in 53.8% of cases (p = 0.035). No differences in clinical outcomes for ROM or the HSS and WOMAX scores were observed between the groups. A periprosthetic fracture, which was considered a notching-related side effect, occurred in one case each in the conventional and navigated TKA groups.

Conclusions

Surgeons should be aware of the risks associated with anterior femoral notching when using a navigation system for TKA. A modification of the femoral cut should be considered when remarkable femoral bowing is observed.     

Reliable and reproducible technique to mark center of ankle in total knee arthroplasty

Aim

Bony and soft tissue landmarks have been used in the past to determine the center of the ankle to facilitate the tibial cut using an extramedullary guide in total knee arthroplasty. However literature reports are scanty in regards to the most ideal method available and its reproducibility in marking the center of the ankle intra-operatively.

Methods

We describe a method of using an electrocardiogram (ECG) lead in determining the center of the ankle, thus facilitating the alignment of the extramedullary guide for the tibia. Results: Using this technique, in our study the mean lateral tibial component angle was 90.09(84.2°–94.3°). The number of knees in the range of 88°–92.4° were 120 out of 122 knees (98.40%).

Conclusion

The described method is reliable and cheap, with reproducibility in determining the tibial cut in total knee arthroplasty.