Differences in Trochlear Surface Damage and Wear Between Three Different Total Knee Arthroplasty Designs

Secondary Patellar Resurfacing Following Primary Unresurfaced Total Knee Arthroplasty: Beware of the Incidence of Late Patellar Erosion

BACKGROUND

The primary aim of this study was to evaluate secondary patellar resurfacing (SPR) indications and rates in a single-surgeon series utilizing a modern TKA design and additionally, to review the functional outcomes of patients after undergoing SPR.

METHODS

A retrospective review of a prospectively collected institutional database was performed. All patients undergoing primary TKA by a single surgeon between 2013 and 2021 were included. During this time, the senior surgeon resurfaced the patella selectively. Patients were divided into the primary resurfaced (PR) and the primary unresurfaced (UR). All patients undergoing SPR in the UR group were identified, their radiographs reviewed, and their clinical outcomes assessed. During the study period, 1,511 TKAs were performed, with 73.1% (1,105 TKAs) being unresurfaced.

RESULTS

The all-cause revision rate was 1.2% in the PR group and 3.6% in the UR group. The rate of SPR in the UR group was 2.0% (22 of 1,105 TKAs). No patient in the PR group underwent revision surgery for a patellar complication. The mean age at primary TKA for those undergoing SPR was 65 years (range, 50 to 78). The average time for SPR from primary TKA was 3.4 years (range, 1.1 to 8.8). Postoperative radiographic progression of patellar erosion, in combination with new onset anterior knee pain, was the indication for SPR in 14 of the 22 (63.7%) SPR cases. After SPR, the Western Ontario and McMaster University Osteoarthritis Index score (P < .001) and Knee Society Score (P < .001) improved from pre-SPR.

CONCLUSIONS

Secondary patellar resurfacing (SPR) was the most common (55%) reason for revision surgery after primary UR TKA in this series. An SPR improved clinical outcomes in symptomatic patients. Surgeons should consider patellar resurfacing for all patients undergoing primary TKA to reduce the burden of revision surgery post-TKA. Additionally, the paradigm that late SPR does not improve clinical outcomes needs to be revisited.

Management of patella maltracking after total knee arthroplasty: a systematic review

PURPOSE

Patella maltracking is among the most frequent causes of poor outcomes and early failure after total knee arthroplasty (TKA), with an incidence that ranges from 1 to 20%. Even if there is agreement between authors regarding the preoperative and intraoperative management of patella maltracking in TKA, less clear are postoperative conducts. The purpose of this systematic review is to summarize and compare surgical techniques used to treat patella maltracking after TKA.

METHODS

A systematic review of the literature was performed with a primary search on Medline through PubMed. The PRISMA 2009 flowchart and checklist were used to edit the review. Screened studies had to provide clinical, functional and radiological results and complications of the proposed treatment to be included in the review.

RESULTS

A total of 21 articles were finally included. Three main types of surgical procedures and other minor techniques have been identified to manage patella maltracking after TKA. The choice of the proper technique to use in the specific case depends on several factors, first of all the malpositioning of the prosthetic components.

CONCLUSION

Patella maltracking after TKA represents a frequent and challenging problem for orthopedic surgeons. Treatments described in the literature are often able to correct an abnormal patellar tracking; nevertheless, authors report variable percentages of residual knee pain and dissatisfaction in re-treated patients. Therefore, it would be desirable to prevent the maltracking condition at the time of primary arthroplasty, using proper surgical precautions.

Understanding the patellofemoral joint in total knee arthroplasty

Total knee arthroplasty (TKA) is one of the most successful procedures in orthopedic surgery. Nevertheless, postoperative patellofemoral complications remain a challenging problem, affecting a substantial proportion of patients. Complications involving the patellofemoral joint (PFJ) can occur in both resurfaced and nonresurfaced patellae. Types of PFJ complications include anterior knee pain, maltracking, fracture, avascular necrosis and patellar clunk. The causes of patellofemoral complications can be categorized into patient-, surgeon- and implant-related factors. Patient characteristics such as female sex, young age, depression and increased body mass index have been linked with increased complications. Important technical considerations to avoid complications include achieving appropriate rotational alignment of the femoral and tibial components, maintaining joint line height, medializing the patellar button and avoiding “overstuffing” the PFJ. Component design features such as conformity, shape and depth of the femoral trochlea have also been shown to be important. Although the cause of patellofemoral complications after TKA may sometimes be unknown, it remains important to minimize errors that can lead to these complications.

Sagittal radius of curvature, trochlea design and ultracongruent insert in total knee arthroplasty

Multi radius (MR) total knee arthroplasty (TKA) has been associated with mid-flexion instability.

Single radius (SR) TKA may provide better anteroposterior stability through single flexion axis and biomechanical advantage for quadriceps function.

Medial pivot (MP) TKA and gradually reducing (GR) radius TKA produce better knee kinematics.

Clinical outcomes are equivalent for SR, MR and MP TKA.

Short-term studies have shown better clinical outcomes and kinematics for GR TKA.

Thinner and narrow anterior flange, deeper trochlea groove and more anatomical trochlea design reduces patellofemoral complications in TKA

Ultracongruent inserts provide comparable clinical outcomes to posterior-stabilized TKA and cruciate retaining TKA.

Cite this article: EFORT Open Rev 2019;4:519-524. DOI: 10.1302/2058-5241.4.180083