Robotic-Assisted Patellofemoral Replacement-Correlation of Preoperative Planning with Intraoperative Implant Position and Early Clinical Experience: A Minimum 2-Year Follow-up

Outcomes After Patellofemoral Arthroplasty With the Arthrex iBalance-A Third Generation Implant

Background

Patellofemoral arthroplasty (PFA) is an attractive option for patients who have isolated patellofemoral disease. This study aimed to assess the functional outcomes and revision rates of primary PFA with a third-generation implant with short- to medium-term follow-up.

Methods

We retrospectively reviewed the records of 49 patients (70 knees) undergoing PFA with the iBalance system by a single surgeon at a quaternary center between January 2015 and September 2022 for demographic and surgical data, as well as complications and revision rates. Patient-reported outcome scores were then collected.

Results

The population was majority female (81.6%) with a median age of 50 years. Four knees were revised to a total knee arthroplasty (5.7%) at an average time point of 2.3 years postoperatively (range: 1.3-3.5 years). The median Single Assessment Numeric Evaluation score at the time of follow-up was 82.5, while the median Kujala score was 72. Lower preoperative Kellgren-Lawrence grade was significantly associated with lower Knee Injury and Osteoarthritis Outcome Scores in all 5 domains (P < .05 for all). Additional procedures were required in 17 knees (24.3%), in most cases to improve patella tracking.

Conclusions

This study is, to our knowledge, the first to examine outcomes of the iBalance PFA system. The results show favorable patient-reported outcomes in this cohort consistent with other 2nd and 3rd generation PFA implants, along with a revision rate similar to its prosthetic peers.

[Robotics for patellofemoral joint replacement-a step forward in arthroplasty?]

BACKGROUND

At 0.2% of all knee replacements implanted in Germany, patellofemoral joint arthroplasty (PFA) account for only a small proportion. However, the potential in the population appears to be significantly greater. In recent years, several robotic-assisted surgical procedures have been developed to increase precision in the implantation of endoprostheses. MAKO® SYSTEM: At present, the Mako® system from Stryker is the only system that can implant an isolated patellofemoral joint replacement robotically. It can be used to analyze and adequately address complex anatomies such as trochlear dysplasia. The system provides support by simulating the positioning of the prosthesis and the exact execution of the plan by aligning the saw or reamer with haptic feedback.

STUDY SITUATION

Studies on robotic-assisted PFA are rare but indicate improved precision with a robotic-assisted procedure. Despite that, an improved clinical and radiological outcome could not be demonstrated in a comparative study.

OUTLOOK

A cost-benefit analysis should be discussed here, as should the necessary learning curve. In principle, robotic-assisted implantation of PFA appears to be a promising procedure. However, a superiority of this procedure over conventional methods cannot be postulated at the present time.

Clinical outcomes of patellofemoral arthroplasty: robotic assistance produces superior short and mid-term outcomes

INTRODUCTION

Patellofemoral arthroplasty (PFA) has been shown to provide symptomatic improvement for isolated patellofemoral osteoarthritis (PFOA). The efficacy of robotic-assisted PFA and the most suitable PFA implant design, however, remain ongoing matters of debate. This study sought to compare clinical outcomes between patients who underwent robotic-assisted versus conventional PFAs with inlay and onlay prosthetic designs.

METHODS

A single-center retrospective review found 237 knees (211 patients) which underwent PFA between 2011 and 2021. One hundred eighty-four knees were included in the final analysis after cases were excluded for having indications other than osteoarthritis or having less than one year of follow-up. There were 90 conventional PFAs and 94 robotic-assisted PFAs performed. Inlay components were implanted in 89 knees and onlay components were implanted in 95 knees. Propensity score matching was utilized to address demographic differences between groups.

RESULTS

Overall, there was a revision-free survivorship rate of 89.7% with an average time to follow-up of 4.6 years (range 1.2 to 11.1). Twenty-nine knees (15.8%) required various non-conversion procedures. The conventional matched cohort exhibited a higher all-cause revision rate, accounting for revision PFAs and conversions to TKA, (18.8 vs. 6.4%, p = 0.014) and a shorter mean time to revision than the robotic-assisted cohort (3.1 vs. 5.8 years, p = 0.026). A Kaplan-Meier survivorship curve showed differences between the conventional and robotics cohorts (p = 0.041). All revisions following robotic-assisted PFA were caused by progression of osteoarthritis, whereas conventional PFAs also required revision due to aseptic loosening and patellar maltracking. The rate of infection resulting in irrigation and debridement was higher for conventional cases (4.3 vs. 0%, p = 0.041). No significant differences in clinical outcomes between the inlay and onlay prosthetic design matched cohorts were identified.

CONCLUSION

PFA is an effective treatment for addressing advanced patellofemoral arthritis. Robotic-assisted surgery may lead to improved clinical outcomes.

LEVEL OF EVIDENCE

III.

Robotic-assisted patellofemoral arthroplasty provides excellent implant survivorship and high patient satisfaction at mid-term follow-up

PURPOSE

Robotic adoption in knee surgery has yielded several benefits, but its application in patellofemoral arthroplasty (PFA) remains barely reported. The purpose of this study was to determine implant survival, patient satisfaction, and functional outcomes after robotic-assisted PFA at an intermediate follow-up.

METHODS

This prospective analysis targeted 18 knees of 16 consecutive patients who underwent robot-aided PFA with three-year minimum follow-up (range, 3 to 6 years). Each patient was evaluated collecting pre-operative and post-operative medical record data, including range of motion, radiographic images, and multiple scores, such as VAS, APKS, and OKS.

RESULTS

At surgery, the mean age was 55.4 years ± 14.4 (range, 32 to 78 years), and the mean BMI was 26.8 kg/m² ±5.2 (range, 20 to 36). Etiologies of patellofemoral osteoarthritis included idiopathic degeneration (28%), post-traumatic (33%), and dysplasia (39%). Pre-implantation scores were VAS 7.9 ± 1.4, AKPS 34.6 ± 23.3, and OKS 17.3 ± 10.3. One implant was revised with primary total knee arthroplasty for osteoarthritis progression. Clinical and radiographic follow-up showed no signs of loosening or infection. The maximum flexion reached an average of 131.1°±10.5° (range, 110° to 145°), accompanied by significantly improved score results (P-value < 0.01): VAS 1.1 ± 1.4, AKPS 90.2 ± 8.6, and OKS 46.3 ± 1.8.

CONCLUSIONS

At 3 years after robotic assisted patellofemoral arthroplasty, excellent implant survival and patient satisfaction rates can be expected along with significantly improved functional and pain control outcomes. Although the limitations imposed by the restricted cohort, these findings indicate that robotic assistance in PFA is both safe and effective at intermediate follow-up.

Current outcomes of patellofemoral arthroplasty for isolated patellofemoral arthritis - A narrative review

Patellofemoral (PFJ) arthritis can be primary, or secondary to underlying trochlea dysplasia and patellofemoral malalignment. Although primary PFJ osteoarthritis affects an older patient population, just like tibiofemoral arthritis, it is common for younger patients to present with isolated PFJ arthritis secondary to an abnormal PFJ. PFJ arthroplasty (PFJA) has many benefits including being less invasive, associated with lower blood loss, is more cost-effective, and leaves the kinematics of the tibiofemoral joint undisturbed. As a result, there are arguably better functional outcomes associated with PFJA, however the historical revision rate of this procedure is high. Although registry outcome data associated with the first generation of PFJ implants shows a higher revision rate compared to TKA, the comparison of PFJ outcomes with TKA is not always age-matched and there is limited comparison on functional and patient-reported outcomes, something which is more important and relevant in a younger patient cohort. Improvements in implant design, instrumentation, surgical technique, and better patient selection has now resulted in outcomes which are comparable to that of TKA, and in some cases even better. This narrative review outlines the current outcomes of PFJA including highlighting factors which need to be considered in optimising outcomes, as well as discussing advanced techniques of robotic assisted PFJA.

Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) as a treatment option for isolated patellofemoral disease continues to evolve. Enhancement in patient selection, surgical technique, implant design, and technology has led to improved short-term and midterm outcomes. Furthermore, in the setting of a younger patient with isolated patellofemoral arthritis, PFA represents an option for improved function with faster recovery times, bone preservation, maintenance of ligamentous proprioception, and the ability to delay total knee arthroplasty (TKA). The most common reason for revising PFA to a TKA is progression of tibiofemoral arthritis. In general, conversion of PFA to TKA leads to successful outcomes with minimal bone loss and the ability to use primary TKA implants and instrumentation. PFA seems to be a cost-effective alternative to TKA in appropriately selected patients with 5-, 10-PFA survivorships of 91.7% and 83.3%, respectively, and an annual revision rate of 2.18%; however, more long-term clinical studies are needed to determine how new designs and technologies affect patient outcomes and implant performance.

Patellofemoral Arthroplasty Is an Efficient Strategy for Isolated Patellofemoral Osteoarthritis with or without Robotic-Assisted System

There is relative paucity in the literature concerning outcomes after robotic-assisted Patellofemoral Arthroplasty (PFA). The aims were (1) to evaluate outcomes in patients undergoing PFA with inlay or onlay components, with or without robotic arm assistance and (2) to identify risk factors of poor outcomes after PFA. This retrospective study included 77 PFA for isolated patellofemoral joint osteoarthritis, assigned to three groups (18 conventional technique, 17 image-free robotic-assisted system and 42 image-based robotic-assisted system). The demographic data were comparable between the three groups. The clinical outcomes assessed were: Visual Analogue Scale, Knee Society Score, Kujala score and satisfaction rate. The radiological measures were: Caton Deschamps index, patellar tilt and frontal alignment of the trochlea. Functional outcomes, satisfaction rate and residual pain were comparable between the three groups. Patellar tilt improvement was superior when a robotic device was used (either image-based or image-free) compared to the conventional technique. There were three revisions (3.9%) at the last follow-up related to femorotibial osteoarthritis progression. Multivariate analysis found no significant risk factors for poor outcomes, with respect to the surgical technique or implant design. Functional outcomes and revisions rate after PFA were comparable between the surgical techniques and implants. Robotic-assisted systems were associated with a superior improvement of the patellar tilt compared to the conventional technique.

Robotic Assisted Patellofemoral Joint Replacement: Surgical Technique, Tips and Tricks

In this article we wish to provide MAKO robotic knee users a surgical guide including tips and tricks on performing MAKO robotic-assisted patellofemoral joint replacements. The senior authors in this paper from the Exeter Knee Reconstruction Unit, United Kingdom are highly experienced MAKO users who have been performing MAKO assisted Patellofemoral joint replacements since 2017.

Knee arthroplasty utilization trends from 2010 to 2019

BACKGROUND

Interest in partial knee arthroplasty procedures including unicompartmental arthroplasty (UKA), patellofemoral arthroplasty (PFA), and bicompartmental knee arthroplasty (BKA) has increased due to their bone and ligament preservation compared to total knee arthroplasty (TKA). Implant designs, changing thoughts on appropriate indications for partial knee arthroplasty, and availability of navigation also impacted the field over the last decade. The aims of this study were to evaluate trends over the last decade in utilization of 1) partial and total knee arthroplasty; and 2) computer-assistance in knee arthroplasty.

METHODS

A retrospective cohort analysis was conducted using the PearlDiver database. Patients who underwent PFA, UKA, BKA, and TKA for an indication of osteoarthritis (OA) were identified using Current Procedural Terminology (CPT) codes. Trends analysis from 2010 to 2019 was conducted to compare utilization based on procedure type and computer-assistance. Statistical analysis was conducted using Compounded Annual Growth Rates (CAGR) and linear regression.

RESULTS

From 2010 to 2019, there was a significant decrease in utilization of PFA (CAGR: -5.73 %; p = 0.011) and BKA (CAGR: -10.49 %; p = 0.013), but no significant difference in that of UKA (p = 0.224) and TKA (p = 0.421). There was a significant increase in the utilization of computer assistance for both UKA (CAGR: +19.81 %; p = 0.002) and TKA (CAGR: +3.90 %; p = 0.038), but there was no significant difference for computer-assisted PFA (p = 0.724) and BKA (p = 0.951).

CONCLUSIONS

TKA is still the most common arthroplasty procedure for OA. Decreased utilization of PFA and BKA may be explained by reported failure and revision rates for PFA and BKA compared to TKA.

Patellofemoral arthroplasty: expert opinion

Isolated patellofemoral osteoarthritis (PFOA) is a common cause of anterior knee pain in patients over the age of 40 years. Patellofemoral arthroplasty (PFA) is an option to address PFAO when the non-operative or joint preserving management has failed.The goals of PFA are to reduce pain and increase function of the knee in a bone and ligament preserving fashion while maintaining or optimizing its kinematics. Over the last decades advances have been made in optimizing implants designs, addressing complications and improving functional and patient reported outcomes. Appropriate patient selection has proven to be imperative. Proper surgical technique and knowledge of pearls and pitfalls is essential.The indications and surgical technique for patellofemoral arthroplasty will be reviewed here.Level of evidence: Therapeutic Level V.

Measuring appropriate need for unicompartmental knee arthroplasty: results of the MANUKA study

PURPOSE

Indications for unicompartmental knee arthroplasty (UKA) are controversial. Studies based solely on radiographic criteria suggest up to 49% of patients with knee osteoarthritis (OA) are suitable for UKA. In contrast, the 'Appropriate use criteria' (AUC), developed by the AAOS, apply clinical and radiographic criteria to guide surgical treatment of knee OA. The aim of this study was to analyze patient suitability for TKA, UKA and osteotomy using both radiographic criteria and AUC in a cohort of 300 consecutive knee OA patients.

METHODS

Included were consecutive patients with clinical and radiographic signs of knee OA referred to a specialist clinic. Collected were demographic data, radiographic wear patterns and clinical findings that were analyzed using the AUC. A comparison of the radiographic wear patterns with the treatment suggested by the AUC as well as the Surgeon Treatment Decision was performed.

RESULTS

There were 397 knees in 300 patients available for analysis. Median age was 68 [IQR 15], BMI 30 [6] with 55% females. Excellent consistency for both the radiographic criteria and the AUC criteria was found. Based on radiological criteria, 41% of knees were suitable for UKA. However, when using the AUC criteria, UKA was the appropriate treatment in only 13.3% of knees. In 19.1% of knees, no surgical treatment was appropriate at the visit, based on the collected data.

CONCLUSION

Application of isolated radiologic criteria in patients with knee OA results in a UKA candidacy is misleadingly high. AUC that are based on both radiological and clinical criteria suggest UKA is appropriate in less than 15% of patients.

LEVEL OF EVIDENCE

III retrospective study.