The use of imageless navigation to quantify cutting error in total knee arthroplasty

The Role of Imageless Computer-Assisted Navigation During Total Knee Arthroplasty on Femoral Component Sagittal Alignment and Outcomes

Background

While total knee arthroplasty (TKA) is highly successful, 15%-20% of patients are not satisfied postoperatively, which may be due to alignment of the TKA components. Imageless computer navigation was developed to increase implant alignment accuracy and precision, but controversy surrounds the patient benefit of this technology. The target of femoral sagittal alignment and its role in patient-reported outcomes (PROMs) after TKA using assistive technology has not been well-defined.

Methods

Femoral sagittal alignment, 30-day complications, and PROMs through 1 year were collected retrospectively from unilateral elective TKA patients who underwent surgery between July 2020 and February 2023. Two surgeons equally versed in conventional and imageless navigation techniques participated in patient record identification. Students t-tests and chi-square tests of proportion were used to compare outcomes, 30-day complications, and alignment.

Results

Completed PROMs were available for 387 patients; 181 in the computer navigation group and 206 in the conventional arthroplasty group. PROMs were statistically significantly different between groups, favoring computer navigation (P = .014 at 12 months). Lateral femoral angle measurements were greater in females who underwent TKA with computer navigation (P < .001). Of note, 14 patients in the conventional technique group returned to the emergency department within 30 days, as compared to 4 in the navigation group (P = .033).

Conclusions

PROMs are improved in the navigation group compared to the conventional technique group. Fewer patients in the navigation group returned to the emergency department. Navigation appeared to provide a small benefit compared to conventional techniques, though final lateral femoral angle was not predictive of outcomes. Additional surgical characteristics may need to be examined to determine the reasons for the differences in outcomes between these techniques.

Technology in Total Knee Arthroplasty in 2023

Over the past few decades, instrumentation and techniques for total knee arthroplasty have evolved from conventional manual tools to a wide range of technologies, including calibrated guides for accurate bone cuts and alignment, smart tools, dynamic intraoperative sensors for soft tissue balancing, patient-specific guides, computer navigation, and robotics. This review is intended to provide an overview of the latest advancements in total knee arthroplasty technology, address potential challenges and solutions related to the application of these technologies, and explore their limitations.

Computer-assisted revision total knee arthroplasty does not improve postoperative knee prosthesis alignment compared to the conventional technique

Purpose

Computer-assisted surgery (CAS) during primary total knee arthroplasty (TKA) prosthesis alignment. However, literature on its use during revision TKA (rTKA) is scarce. Moreover, the effect of CAS during rTKA on rotational alignment of the prosthesis has not been described yet. The purpose of this study was to assess the effect of CAS during rTKA, focusing on the number of outliers and coronal, sagittal and rotational prosthetic alignment compared to conventional rTKA.

Methods

A prospective cohort study comparing CAS-rTKA with a historical control group (CON-rTKA). The CAS-rTKA group (54 patients/62 knees) underwent rTKA using imageless CAS between 2012 and 2017. The CON-rTKA group (13 patients/23 knees) was operated using the conventional technique between 2002 and 2012. Postoperative alignment was measured using the EOS-2D/3D system (coronal and sagittal planes) and computed tomography scan (rotation).

Results

No significant differences between the CAS-rTKA and CON-rTKA groups were found for coronal and sagittal alignment regarding the mechanical angle of the leg (p = 0.08), mechanical lateral distal femoral angle (p = 0.87), mechanical medial proximal tibial angle (p = 0.40), anatomical proximal posterior tibial angle (p = 0.43) nor femoral (p = 0.80) and tibial rotation (p = 0.15). For the proportions of coronal, sagittal and rotational outliers, no significant differences were found either.

Conclusion

This study showed no evidence that use of CAS during rTKA leads to improved coronal, sagittal or rotational alignment of knee prostheses or a difference of outliers between the groups.

Level of Evidence

Level III, therapeutic.

Accuracy of Advanced Active Robot for Total Knee Arthroplasty: A Cadaveric Study

Although the accuracy of other types of robotic systems for total knee arthroplasty (TKA) has been assessed in cadaveric studies, no investigations have been performed to evaluate this newly advanced active robotic system. Therefore, the authors aimed to analyze the accuracy of bone resection in terms of thickness and alignment in a cadaveric study. Three cadaveric specimens (six knees) and an active robotic system (CUVIS Joint, CUREXO) were used in the study. Three surgeons with different experiences in robotic TKAs performed this cadaveric study using the same robotic protocol with two different implant designs. The thickness and angle of bone resection planes obtained from the optical tracking system and the difference between resection planes and the planning data were assessed to determine accuracy. With respect to the overall resection accuracy compared to the plan, the cutting depth accuracy was within 1.0 mm mean of root mean square (RMS), and the resection angle accuracy in terms of sagittal, coronal, and axial planes was within 1.0 degree mean RMS. In contrast, no significant differences were observed between the planned and measured values in terms of the resection angles and cutting thickness. The hip-knee-ankle angle at postoperative evaluation was 0.7 degrees ± 0.7 degrees (RMS 1.0 degrees). This in vivo study suggests that the use of this newly advanced active robotic system for TKA demonstrates a high degree of accuracy in terms of resection thickness and alignment. This finding supports the clinical application of this advanced robotic system. LEVEL OF EVIDENCE:  Cadaveric study, Level V.

Predictors of Recurrent Flexion Contracture after Total Knee Arthroplasty in Osteoarthritic Knees with Greater Than 15° Flexion Contracture

Background

This study aimed to analyze the risk factors that predict recurrent flexion contracture (FC) after total knee arthroplasty (TKA) in osteoarthritic knees with FC ≥ 15°.

Methods

Data from a consecutive cohort comprising 237 TKAs in 187 patients with degenerative osteoarthritis, preoperative FC ≥ 15°, and a minimum follow-up period of 2 years were retrospectively reviewed. Preoperative FC was corrected intraoperatively from 0° to 5°. The incidence of recurrent FC (FC ≥ 10°) at 2 years postoperatively was investigated. Potential risk factors predicting recurrent FC including age, sex, body mass index, unilateral TKA, severity of preoperative FC, 3-month postoperative residual FC, γ angle, change in posterior femoral offset ratio, and lumbar degenerative kyphosis (LDK) were analyzed using logistic regression analysis. The post-hoc powers for the identified factors were then determined.

Results

Forty-one knees (17.3%) with recurrent FC were identified. Risk factors with sufficient power for recurrent FC were unilateral TKA, severity of preoperative FC, residual FC at 3 months postoperatively, and LDK (odds ratios of 3.579, 1.115, 1.274, and 3.096, respectively; p < 0.05; power ≥ 86.1).

Conclusions

Recurrent FC can occur in TKAs with the risk factors including unilateral TKA, severe preoperative FC, residual FC at 3 months postoperative, and LDK despite appropriate intraoperative correction. Surgical strategies and rehabilitation protocols used in managing FC should be applied in TKA cases with risk factors for recurrent FC.

Learning curve of robot-assisted total knee arthroplasty and its effects on implant position in asian patients: a prospective study

BACKGROUND

Robot-assisted total knee arthroplasty (r-TKA) can reportedly achieve more accurate implant positioning than conventional total knee arthroplasty (c-TKA), although its learning curve is controversial. Moreover, few studies have investigated r-TKA in Asians, who have different anatomical characteristics. This study aimed to determine the learning curve for r-TKA and compare implant positions between r-TKA and c-TKA according to the learning curve in Asian patients.

METHODS

This prospective study included 50 consecutive c-TKAs (group C), followed by 50 consecutive r-TKAs conducted using the MAKO robotic system (Stryker, USA). Cumulative summation analyses were performed to assess the learning curve for operative time in r-TKA. Accordingly, the r-TKA cases were divided into the initial (group I) and proficiency cases (group P). The femoral and tibial component positions in the coronal, sagittal, and axial planes and lower limb alignment were compared among the three groups.

RESULTS

r-TKA was associated with a learning curve for operative time in 18 cases. The operative time was significantly shorter in groups C and P than that in group I, with no significant difference between groups C and P. Groups I and P demonstrated fewer outliers with respect to lower limb alignment, femoral component coronal position, axial position, and tibial component sagittal position than those in group C, with no significant difference between groups I and P.

CONCLUSION

The operative time did not differ significantly between r-TKA and c-TKA after the learning curve. Surgeons could expect more accurate and reproducible lower limb alignment and implant positioning with r-TKA in Asian patients, irrespective of the learning curve.

Effects of Severe Varus Deformity on Soft Tissue Balancing in Total Knee Arthroplasty

This study aimed to establish the effect of severe varus deformity on soft tissue balance in total knee arthroplasty (TKA), which is not yet well established. We retrospectively enrolled 205 patients (270 knees) who underwent primary TKA using the measured resection technique. Four intraoperatively measured TKA gaps and gap differences were compared between the severe varus deformity group (Hip-knee-ankle [HKA] varus angle ≥ 10°) and the mild varus deformity group (HKA varus angle < 10°). Pearson’s correlation analysis and multiple linear regression analysis were used to investigate the factors affecting flexion and extension gap differences (FGD and EGD). A receiver operating characteristic curve was applied to assess the cut-off value of the HKA varus angle to discriminate the rectangular gap. The FGD (1.42 ± 1.35 mm vs. 1.05 ± 1.16 mm, p = 0.019) and the EGD (1.45 ± 1.32 mm vs. 0.97 ± 1.53 mm, p = 0.006) were significantly larger in severe varus deformity group than in mild varus deformity group. The HKA varus angle was positively correlated with both FGD (r = 0.264, p < 0.001) and EGD (r = 0.319, p < 0.001) and was an influencing factor for FGD (β = 0.232, p = 0.040) and EGD (β = 0.229, p = 0.037). A preoperative HKA angle of 12.4° was selected as the cutoff value to discriminate between rectangular and trapezoidal gaps. Thus, the severity of varus deformity (HKA varus angle) was found to be a significant factor affecting the mediolateral gap difference in TKA. When performing TKA in a knee with an HKA varus angle ≥ 12.4°, a trapezoidal gap is more likely to be expected. Level of evidence III, case−control study.

Comparison of Survival Rate and Outcomes Between Conventional and Navigation-Assisted Primary Total Knee Arthroplasty in Severe Varus Knees: A Minimum 10-Year Follow-Up

BACKGROUND

This study aimed to compare the long-term clinical and radiographic outcomes and survival rates between navigation-assisted (NAV) total knee arthroplasty (TKA) and conventional (CON) TKA in patients with preoperative severe varus deformity.

METHODS

From January 2005 to December 2011, 152 TKAs and 62 TKAs with preoperative hip-knee-ankle (HKA) angles more than 15° were enrolled in the CON-TKA and NAV-TKA group with 135.7 months follow-up. Clinical outcomes (Western Ontario and McMaster University Osteoarthritis Index and Knee Society Scores), radiographic outcomes (HKA, α, β, γ, and δ angles), and survivorship were compared between the groups.

RESULTS

The mean value of radiographic outcomes was not statistically different; however, outliers of the HKA angle were significantly higher in the CON-TKA group (18.4% versus 8.1%, P = .04). However, long-term clinical outcomes were similar between both groups. The cumulative survival rate was 96.1% in the CON-TKA group and 96.8% in the NAV-TKA group, with no difference between the groups (P = .962).

CONCLUSION

NAV-TKA showed fewer outliers in the HKA angle for severe preoperative varus deformity compared with CON-TKA. The long-term clinical outcomes and survival rates were similar between the 2 techniques. A survival rate of more than 96% was observed in both groups.

STUDY DESIGN

Level III, retrospective comparative study.

Mid- to Long-Term Outcomes After Medial Open-Wedge High Tibial Osteotomy in Patients With Radiological Kissing Lesion

Background:

Although medial open-wedge high tibial osteotomy (MOWHTO) is the treatment of choice for patients with mild to moderate osteoarthritis with varus malalignment, concerns about inferior outcomes in patients with preoperative radiological kissing lesion (RKL) remain.

Purpose:

To compare the mid- to long-term clinical and radiological results and survivorship after MOWHTO in patients with versus without preoperative RKL.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included were 122 knees in patients who underwent MOWHTO with a medial locked plate and had minimum 5-year follow-up data. The mean age at surgery was 55.9 years (range, 38-65 years), and the mean follow-up was 7.5 years (range, 5-12.8 years). All patients had undergone second-look arthroscopy around 2 years after MOWHTO. The knees were divided into an RKL group (n = 17) and no-RKL group (n = 105) based on preoperative standing radiographs. The authors compared postoperative American Knee Society (AKS) knee and function scores, range of motion, and improvements in AKS scores between groups, as well as hip-knee-ankle angle, medial proximal tibial angle, and joint-line convergence angle from preoperatively to postoperatively. Also compared were the degree of cartilage regeneration between first- and second-look arthroscopy and the survival rate after index surgery.

Results:

Preoperative AKS scores were significantly lower in the RKL group versus the no-RKL group (AKS knee, 79.6 ± 7.5 vs 83.8 ± 3.9, P = .037; AKS function, 68.8 ± 9.3 vs 76.0 ± 5.1, P = .006). Likewise, postoperative AKS scores were significantly lower in the RKL group versus the no-RKL group (AKS knee: 91.3 ± 4.2 vs 94.4 ± 1.6, respectively, P = .008; AKS function: 90.0 ± 10.0 vs 97.6 ± 4.5, respectively, P = .007). However, all patients had excellent postoperative AKS knee and function scores (>80). Moreover, there were no between-group differences in pre- to postoperative improvement in AKS scores, postoperative radiological changes, or grade of cartilage regeneration. The survival rates in the RKL and no-RKL groups were 100% and 97.1%, respectively (P ≥ .999).

Conclusion:

Although the latest clinical scores were lower in the RKL group than in the no-RKL group, comparable results in postoperative clinical improvement, cartilage regeneration, and survivorship were observed in patients with RKL at mid- to long-term follow-up.

Intra-articular Injection of Mesenchymal Stem Cells After High Tibial Osteotomy in Osteoarthritic Knee: Two-Year Follow-up of Randomized Control Trial

Intra-articular injection of adipose-derived mesenchymal stem cell (ADMSC) after medial open-wedge high tibial osteotomy (MOWHTO) would be a promising disease-modifying treatment by correcting biomechanical and biochemical environment for arthritic knee with varus malalignment. However, there is a paucity of clinical evidence of the treatment. This randomized controlled trial (RCT) was aimed to assess regeneration of cartilage defect, functional improvement, and safety of intra-articular injection of ADMSCs after MOWHTO compared with MOWHTO alone for osteoarthritic knee with varus malalignment. This RCT allocated 26 patients into the MOWHTO with ADMSC-injection group (n = 13) and control (MOWHTO-alone) group (n = 13). The primary outcome was the serial changes of cartilage defect on periodic magnetic resonance imaging (MRI) evaluation using valid measurements until postoperative 24 months. Secondary outcomes were the 2-stage arthroscopic evaluation for macroscopic cartilage status and the postoperative functional improvements of patient-reported outcome measures until the latest follow-up. Furthermore, safety profiles after the treatment were evaluated. Cartilage regeneration on serial MRIs showed significantly better in the ADMSC group than in the control group. The arthroscopic assessment revealed that total cartilage regeneration was significantly better in the ADMSC group. Although it was not significant, functional improvements after the treatment showed a tendency to be greater in the ADMSC group than in the control group from 18 months after the treatment. No treatment-related adverse events, serious adverse events, and postoperative complications occurred in all cases. Concomitant intra-articular injection of ADMSCs with MOWHTO had advantages over MOWHTO alone in terms of cartilage regeneration with safety at 2-year follow-up, suggesting potential disease-modifying treatment for knee OA with varus malalignment.