Does Choice of Patellar Implant in Total Knee Arthroplasty Matter?: A Randomized Comparative Trial of 3 Commonly Used Designs.

BACKGROUND: There is currently a lack of evidence to identify the optimal patellar implant design in total knee arthroplasty (TKA). The aim of this study was to assess clinical, intraoperative, radiographic, and scintigraphic differences between inlay (IN), onlay round (OR), and onlay oval (OO) patellar implants. METHODS: A parallel-group, double-blinded, randomized trial compared IN, OR, and OO patellar implants using the same posterior-stabilized TKA prosthesis for each. Patient outcomes were prospectively followed for a minimum of 2 years, with survivorship outcomes followed for a mean of 5 years. The primary outcome was the between-group differences in the mean Kujala score change from preoperatively to 2 years postoperatively. The secondary outcomes included differences in other knee-specific and general health outcomes, intraoperative characteristics, radiographic parameters, patellar vascularity, and implant survivorship. RESULTS: A total of 121 participants (40 in the IN group, 41 in OR group, 40 in the OO group) were allocated to 1 of 3 implant designs. At 2 years postoperatively, there were no significant differences in Kujala score changes between groups (p = 0.7; Kruskal-Wallis test). Compared with the IN group, the OR group showed greater improvements in Knee injury and Osteoarthritis Outcome Score (KOOS) Activities of Daily Living and in KOOS Quality of Life compared with the OO group. However, the OO design exhibited better bone coverage and lower lateral facetectomy rates compared with the IN and OR designs. The IN group had more lateral contact compared with the OO group (p = 0.02; Fisher exact test), but the overall value for lateral contact was not significant (p = 0.09; chi-square test). There were no differences in postoperative scintigraphic vascularity (p = 0.8; chi-square test). There was 1 revision for infection at 3 years postoperatively in the OO group, and no revision in the other groups. CONCLUSIONS: Patellar design did not influence patellofemoral outcomes or survivorship. However, OR implants showed improvements in some secondary patient-reported outcome measures, and OO implants exhibited superior bone coverage and improvements in several intraoperative, radiographic, and scintigraphic outcomes. These findings, combined with superior long-term implant survivorship from previous studies, add support for the use of onlay designs in TKA. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

No difference in clinical outcomes between portable navigation and conventional instrumentation in total knee arthroplasty: A randomised trial.

BACKGROUND: Portable accelerometer-based navigation devices (PAD) in total knee arthroplasty (TKA) have been proposed to combine the alignment precision of computer navigation with the efficiency of conventional instrumentation (CON). The aim of this study was to determine if PAD was more effective than CON in TKA in improving clinical outcomes at medium term follow-up. METHODS: Participants undergoing primary TKA were randomly assigned to either PAD or CON. The primary outcome was the mean between-group difference in the four subscales of the Knee injury and Osteoarthritis Outcome Score (∆KOOS4 ) between preoperative status and latest follow-up. Secondary outcomes included analysis of between-group differences in all KOOS subscales, Western Ontario and McMaster Universities Osteoarthritis Index (∆WOMAC) scores, complications and reoperation rates. RESULTS: Of the 178 participants allocated to a treatment arm, 159 (89.3%) completed follow-up at a mean of 4.3 years (range 3.2-5.8 years). There was no statistically significant or clinically meaningful difference in ∆KOOS4 between preoperative status and latest follow-up (PAD = 41, CON = 43; p = 0.5). There was no difference in mean ∆WOMAC scores (PAD = 39, CON = 41; p = 0.9) or ∆KOOS subscales between groups. In addition, there were no differences in complications or reoperations between groups. CONCLUSIONS: PAD was not superior to CON in improving patient-reported outcomes or reducing complications and reoperation rates at medium term follow-up. The use of PAD in TKA to improve clinical outcomes alone cannot be justified based on the results of this study.

Characteristics of three different patellar implant designs in total knee arthroplasty.

BACKGROUND: Despite debate over the role of patellar resurfacing in total knee arthroplasty, many surgeons feel it decreases re-operation rates and anterior pain, and an increasing number are adopting resurfacing. This study compares intra-operative characteristics of different patellar implants to assist surgeons in gaining better understanding of these implants. METHODS: The three most commonly used patellar implants (inset, onlay round and onlay oval) were allocated randomly to 120 patients undergoing total knee arthroplasty. We compared the groups in terms of implant size, bone coverage, lateral underhang (uncovered lateral facet) and need for partial lateral facetectomy. We also compared the patient-reported outcome measures between the groups at 6 months post-operatively. RESULTS: The inset, onlay round and onlay oval designs had bone coverage of 48.5%, 65.9% and 85.9%, respectively (P < 0.01). Similarly, the onlay-oval implant was found to have the smallest lateral underhang of all three designs (inset 11.6 mm; onlay round 6.9 mm, onlay oval 1.6 mm, P < 0.01). The onlay-oval design was the largest implant with a median size of 35 mm, compared to 23 mm for the inset and 32 mm for the onlay round (P < 0.01). In addition, patellae using onlay-oval implants required significantly fewer lateral facetectomies due to improved bone coverage (inset 95%; onlay round 87%; onlay oval 3%; P < 0.01). Finally, comparison of patient-reported outcome measures between the groups showed no difference at an early assessment of 6 months. CONCLUSION: Onlay-oval design allows for the use of a larger implant, improving bone coverage and reducing the need for partial lateral facetectomy; however, early assessment of outcomes shows no difference between the three designs.

Guidelines for the orthopedic surgeon in the era of COVID-19.

Amid the current pandemic of coronavirus disease 2019 (COVID-19), orthopaedic surgery was one of the fewer specialties that remained active managing emergent and urgent orthopaedic and trauma cases. On the other hand, with the continued spread of this pandemic and its associated socioeconomic confinement and unpredictability of the pandemic curve; many health care facilities were forced into halting all elective and non-urgent activities including orthopaedic specialties. This in part was to help in reallocation of required resources and focusing on the proper management of COVID-19 patients, and to prevent the transmission of infection among health care workers and patients. In this article we analyzed developments and recommendations of international reports about the current outbreak and its impact on the practice of orthopaedic surgery. Our aim was to provide comprehensive and easy guidelines for the management of urgent and emergent cases in hot zones and for the process of returning to usual orthopaedic work flow in a balanced strategy to assure safe practice and providing quality care without the risk of exhausting institutional resources or the risk of COVID- 19 transmission among health care workers or patients.

How Accurately Can Soft Tissue Balance Be Determined in Total Knee Arthroplasty?

BACKGROUND: Soft tissue balance is believed to be a major determinant of improved outcomes in total knee arthroplasty (TKA). We conducted this study to assess the accuracy of surgeon-defined assessment (SDA) of knee balance compared to pressure sensor data. We also assessed for any association between experience (learning curve) and accuracy of SDA. METHODS: A total of 308 patients undergoing 322 mechanically aligned TKA were prospectively analyzed. Femoral and tibial trial implants were inserted before performing knee balancing. We compared the surgeon determination on knee balance at 10°, 45°, and 90° of flexion to sensor data at the same flexion angles. RESULTS: Accuracy of SDA was 63%, 57.5%, and 63.8% at 10°, 45°, and 90°, respectively, when compared to sensor data. SDA had an overall sensitivity of 81% and specificity of 37.7%. Capacity to determine an unbalanced knee worsened at higher knee flexion angles with SDA test specificity of 53.5%, 34.8%, and 24.8% at 10°, 45°, and 90°, respectively (P = .0004 at 10° vs 45°, P < .0001 at 10° vs 90°). Cohen's kappa coefficient was 0.29 at 10° indicating fair agreement, and 0.14 and 0.12 at 45° and 90°, respectively, indicating poor agreement. The use of sensor had no time-based learning effect on capacity to determine knee balance. CONCLUSION: SDA is a poor predictor of the true soft tissue balance when compared to sensor data, particularly in assessing whether a knee is unbalanced. In addition, increased use of sensors did not improve surgeon capacity to determine knee balance.

Evaluation of the patellofemoral joint in total knee arthroplasty: Validation of the weight bearing merchant radiographic view.

BACKGROUND: Standard radiographic views for patellofemoral joint assessment do not reflect loading at which TKA patients may describe post-operative anterior symptoms. A novel weight bearing (WB) Merchant view has been described and demonstrated a number of tracking changes that correlated with clinical outcomes. In this study, we aim to validate the WB Merchant view and assess relationships with patient outcome scores. METHODS: Patients were randomly allocated to receive one of the three commonly used patellar implants with a single TKA prosthesis. Patients were evaluated at six months post-operatively using both NWB and WB Merchant views. Indicators of patellar tracking were correlated with improvement in KOOS, WOMAC and Kujala scores. For reliability assessment, radiographs were assessed twice by two readers. RESULTS: The WB Merchant view showed a reduction in the percentage of outliers of tracking indices in comparison to the NWB view (Congruence angle: NWB = 37%, WB = 24%; Displacement: NWB = 2%, WB = 0%; Tilt angle: NWB = 60%, WB = 56%). There was an increase in the lateral contact state with the WB Merchant view (Type I: NWB = 19%, WB = 28%; Type II: NWB = 3%, WB = 4%). The state of lateral contact had a consistent and statistically significant correlation with the improvement in KOOS, WOMAC and Kujala scores (p value = 0.01, 0.01 and 0.03, respectively). All radiographic indices had good reliability with accepted variability. CONCLUSION: The WB Merchant radiograph is an easy to perform and reliable view for the evaluation of patellar tracking and may provide additional information to the routinely used NWB view.

Soft tissue balancing in total knee arthroplasty using sensor-guided assessment: is there a learning curve?

BACKGROUND: Sensor-guided assessment for soft tissue balance in total knee arthroplasty (TKA) has been reported to improve patient satisfaction and self-reported outcome scores. As more surgeons adopt this technology in TKA, we performed this study to identify if there is a learning curve with its use. METHODS: Analysis of a total of 90 consecutive cases was performed in this study. Initial and final intercompartmental pressure differences were recorded before and after knee ligament balancing. The first 45 patients (group 1) were compared to the last 45 patients (group 2) in terms of operative time and the final state of knee balance. A balanced knee was defined as pressure difference between medial and lateral compartments of ≤15 pounds. RESULTS: Group 1 had 10 unbalanced knees in the final pressure difference assessment, while all cases in group 2 were balanced (P < 0.001). There was no statistically significant difference in mean operative time between the two groups. A scatter plot of intercompartmental pressure difference identified that after 30 cases, the capacity to achieve knee ligament balance improved. CONCLUSION: This study suggests that there is a learning curve with the use of sensor-guided assessment in TKA in achieving knee balance; however, the differences noted between initial and final groups were small and may not be of clinical significance.

Accelerometer-Based, Portable Navigation (KneeAlign) vs Conventional Instrumentation for Total Knee Arthroplasty: A Prospective Randomized Comparative Trial.

BACKGROUND: Accelerometer-based, portable navigation devices have been introduced as a less invasive and simpler technique to perform navigated surgical implantation of knee prostheses. They have been postulated to have better accuracy than conventional instruments in restoration of alignment in total knee arthroplasty. METHODS: A total of 190 patients were enrolled in this prospective, randomized controlled trial and underwent total knee arthroplasty using either the KneeAlign or conventional guides. Multiplanar alignment was evaluated with a CT imaging protocol. RESULTS: A total of 86.5% of portable navigation device and 82.2% of conventional group had a postoperative hip-knee angle within 3° of neutral alignment (P = .54). There was no significant difference between the 2 groups for component coronal and sagittal plane alignment. Portable navigation device did not significantly increase the time to perform the surgery. CONCLUSION: Portable navigation device demonstrates accurate restoration of alignment; however, there was no statistically significant difference when compared with conventional guides.