The impact of patellar resurfacing in two-stage revision of the infected total knee arthroplasty

Dalí Sign: Characterization and Case Series of Patellar Bony Shell Morphological Changes after Two-Stage Revision for Periprosthetic Joint Infection

The fate of the patella in two-stage revision total knee arthroplasty (TKA) for periprosthetic joint infection (PJI) in which the patella is left as a bony shell is poorly described. The purpose of this case series is to describe a phenomenon we name the Dalí Sign, which is characterized by elongation and curvature of the patella around the lateral edge of the femoral component occasionally observed in patients undergoing two-stage revision without reimplantation of the patellar component.Our institutional surgical database was queried for patients who were treated with two-stage revision arthroplasty for PJI by the two senior authors. All available sequential skyline patellar radiographs were viewed from immediately prior to first-stage explantation to latest image at final outpatient follow-up at our institution and assessed for the abovementioned morphological changes.Included patients underwent a two-stage revision surgery for PJI at our institution, had a patellar component removed during the first stage of their treatment which included implant explantation and insertion of temporary antibiotic spacers, did not have the patellar component reimplanted during their second-stage revision surgery, and demonstrated radiographic patellar morphological changes at final follow-up. Patients' demographic, surgical, and outcome data were recorded.Our review identified six patients meeting these criteria. Mean follow-up after second-stage surgery was 12 months (range 2 to 21 months). At final follow-up, three patients were walking without pain, one patient was exercising to tolerance, one patient was walking with pain, and one was using a wheelchair or a walker for mobility.In this case series, we characterize the Dalí Sign, the elongation and curvature of the patellar bony shell over the femoral component after two-stage revision for PJI. Further comparative cohort studies are necessary to identify the incidence and risk factors for the development of this morphological change and to compare outcomes of patients with and without the Dalí Sign when left with a bony shell after staged revision TKA.

Patellar Reconstruction With a Trabecular Metal-Backed Component and Screw Fixation: A Preliminary Case Series

BACKGROUND

Limited patellar bone stock in revision total knee arthroplasty (TKA) may compromise fixation. Trabecular metal (TM)-backed components have been proposed to obtain long-term fixation. However, current fixation techniques (i.e., sutures) have limitations. Thus, we sought to evaluate survivorship of porous TM-backed patellar components affixed with a novel method of mini fragment screw fixation in the setting of limited patellar bone stock.

METHODS

We conducted a retrospective chart review of all TM-backed patellae affixed with mini fragment screws during revision TKA by the senior authors from March 25, 2020, to May 20, 2022 (22 patellae, 21 patients). Demographics, TM-backed patellae survivorship, radiological status (loosening) of surviving patellae, and TKA reoperations were evaluated. The average follow-up was 3 years (range, one to four).

RESULTS

At the latest follow-up, and despite a high prevalence (82%) of a history of periprosthetic joint infection (PJI), previous revisions (mean, 3.2), and limited preoperative patellar thickness (mean, 7.6 mm), only one TM-backed patella was removed due to infection. All surviving patellae were radiologically stable. There were nine TKAs reoperated: one for supracondylar fracture and PJI; another for patellar subluxation/PJI/ruptured tendon; four for PJI; one for femoral component loosening; another for femoral component loosening and PJI; and one for a defect in the medial parapatellar arthrotomy. Nevertheless, intraoperatively, TM-backed patellar components were deemed well-fixed and were retained.

CONCLUSIONS

The TM-backed patellar components affixed with mini fragment screws have excellent short-term survivorship in the setting of limited bone stock. Further investigations with longer follow-ups and better levels of evidence are needed to ascertain the mid- and long-term outcomes of this particular construct.

Frequent complications of deficient patellae after component removal in 1.5-stage exchange arthroplasty for periprosthetic joint infection

PURPOSE

To compare the complication rates between deficient patellae (remnant patellae after component removal) and non-resurfaced patellae after 1.5-stage exchange arthroplasty for periprosthetic joint infection and identify risk factors for complications of deficient patellae.

METHODS

Complications in 76 deficient patellae (group D) and 41 non-resurfaced patellae (group N), with a minimum follow-up of 2 years after 1.5-stage exchange arthroplasty were retrospectively analyzed. Demographic characteristics and mean follow-up period did not differ between the groups. The incidences of patellar maltracking, erosion, and fractures were investigated. Factors affecting each patellar complication in group D were investigated in terms of age, sex, body mass index, postoperative hip-knee-ankle angle (HKA), remnant patellar thickness, and change in joint line height.

RESULTS

The incidence of patellar maltracking and erosion was significantly higher in group D than in group N [maltracking: 16 (21.1%) vs. 0 cases (0%), p = 0.001; erosion: 30 (39.5%) vs. 2 cases (4.9%), p < 0.001]. The incidence of patellar fractures tended to be higher in group D [6 (7.8%) vs. 0 cases, p = 0.090]. In group D, postoperative valgus limb alignment and younger age were identified as significant factors that affected patellar maltracking (odds ratio of postoperative HKA = 1.628, p = 0.005) and erosion (odds ratio of age = 0.909, p = 0.009), respectively.

CONCLUSION

Close observation of the complications of deficient patellae is required after 1.5-stage exchange arthroplasty. Valgus limb alignment should be avoided to reduce the risk of complications. Early second-stage revision with patellar reconstruction can be considered in younger patients with deficient patellae.

LEVEL OF EVIDENCE

III.

Management of Bone Loss in Revision Total Knee Arthroplasty: An International Consensus Symposium

The evaluation, classification, and treatment of significant bone loss after total knee arthroplasty (TKA) continue to be a complex and debated topic in revision TKA (rTKA). Despite the introduction of new evidence and innovative technologies aimed at addressing the approach and care of severe bone loss in rTKA, there is no single document that systematically incorporates these newer surgical approaches. Therefore, a comprehensive review of the treatment of severe bone loss in rTKA is necessary. The Stavros Niarchos Foundation Complex Joint Reconstruction Center Hospital for Special Surgery, dedicated to clinical care and research primarily in revision hip and knee replacement, convened a Management of Bone Loss in Revision TKA symposium on June 24, 2022. At this meeting, the 42 international invited experts were divided into groups; each group was assigned to discuss questions related to 1 of the 4 topics: (1) assessing preoperative workup and imaging, anticipated bone loss, classification system, and implant surveillance; (2) achieving durable fixation in the setting of significant bone loss in revision TKA; (3) managing patellar bone loss and the extensor mechanism in cases of severe bone loss; and (4) considering the use of complex modular replacement systems: hinges, distal femoral, and proximal tibial replacements. Each group came to consensus, when possible, based on an extensive literature review and interactive discussion on their group topic. This document reviews each these 4 areas, the consensus of each group, and directions for future research.

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-analysis and Trial Sequential Analysis of 50 Randomized Controlled Trials

OBJECTIVE

During total knee arthroplasty, femur and tibia parts are regularly replaced, while resurfacing the patellar or not is an ongoing discussion. To compare revision rate, anterior knee pain rate, patient-reported outcome measures, complication, radiographic, and clinical outcomes after patellar resurfacing versus non-resurfacing in total knee arthroplasty.

METHODS

PubMed, Medline, EMBASE, CENTRAL, and CINAHL databases were searched on 25 April 2021 to enroll randomized controlled trials that compared patellar resurfacing versus non-resurfacing. We used the grading of recommendations assessment, development and evaluation (GRADE) framework to assess the certainty of evidence. Our primary outcome was revision rate and secondary outcomes was anterior knee pain rate. Outcomes were pooled using the random-effect model and presented as risk ratio (RR), or mean difference (MD), with 95% confidence interval (CI).

RESULTS

Fifty studies (5586 knees) were included. Significant reductions in patellar revision rate (RR 0.41, 95% CI [0.19, 0.88]; P = 0.02; I²  = 24.20%) and non-patellar revision rate (RR 0.64, 95% CI [0.55, 0.75]; P < 0.001; I²  = 0%) were seen after patellar resurfacing. Patellar resurfacing significantly reduced the anterior knee pain rate than nonresurfacing (RR 0.72, 95% CI [0.57, 0.91]; P = 0.006; I²  = 69.5%). Significant differences in patient-reported outcome measures were found. However, these differences were inconsistent and lacked clinical importance. Patellar resurfacing resulted in a significant lower rate of patellar clunk (RR 0.58, 95% CI [0.38, 0.88]; P = 0.01; I²  = 0%), a higher patellar score (MD 1.24, 95% CI [0.67, 0.81]; P < 0.001; I²  = 73.8%), but prolonged surgical time (MD 8.59, 95% CI [5.27, 11.91]; P < 0.001; I²  = 88.8%).

CONCLUSIONS

The clear relationship is that patellar resurfacing reduces revisions, anterior knee pain, and patellar clunk. It will be interesting to compare the initial cost with the revision cost when required and cost-utility analysis with long-term results in future studies.

The Fate and Relevance of the Patella in Two-Stage Revision Total Knee Arthroplasty for Periprosthetic Joint Infection

BACKGROUND

It remains unclear whether reimplantation of a patellar component during a two-stage revision for periprosthetic total knee arthroplasty infection (PJI) affects patient reported outcome measures (PROMs) or implant survivorship. The purpose of this study was to evaluate whether patellar resurfacing during reimplantation confers a functional benefit or increases implant survivorship after two-stage treatment for PJI.

METHODS

Two-stage revisions for knee PJI performed by three surgeons at a single tertiary care center were reviewed retrospectively. All original patellar components and cement were removed during resection and the patella was resurfaced whenever feasible during reimplantation. PROMs, implant survivorship, and radiographic measurements (patellar tilt and displacement) were compared between knees reimplanted with a patellar component versus those without a patellar component.

RESULTS

A total of 103 patients met the inclusion criteria. Forty-three patients (41.7%) underwent reimplantation with, and 60 patients (58.3%) without a patellar component. At a mean follow-up of 33.5 months, there were no significant differences in patient demographics or PROMs between groups (P ≥ .156). No significant differences were found in the estimated Kaplan-Meier all-cause, aseptic, or septic survivorship between groups (P ≥ .342) at a maximum of 75 months follow-up. There was no significant difference in the change (pre-resection to post-reimplant) of patellar tilt (P = .504) or displacement (P = .097) between the groups.

CONCLUSION

Patellar resurfacing during knee reimplantation does not appear to meaningfully impact postoperative PROMs or survivorship. Given the risk of potential extensor mechanism complications with patellar resurfacing, surgeons may choose to leave the patella without an implant during total knee reimplantation and expect similar clinical outcomes.

LEVEL OF EVIDENCE

Level III.

Patellar Rebar Augmentation in Revision Total Knee Arthroplasty

BACKGROUND

In revision total knee arthroplasty, osteolysis, mechanical abrasion, and infection may leave patellar bone stock severely attenuated with cavitary and/or segmental rim deficiencies that compromise fixation of patellar implant pegs. The purpose of this study was to retrospectively review the use of cortical "rebar" screws to augment cement fixation in revision patelloplasty.

METHODS

From 2006 to 2018, dorsal patellar rebar technique was used for patellar reconstruction in 128 of 1037 revision total knee arthroplasty cases (12.3%). Follow-up was achieved with serial radiographs and prospective comparison of Knee Society Scores (KSSs) for clinical outcome. Complications and implant failures requiring reoperation or modified rehabilitation were also assessed.

RESULTS

Of the 128 patellar revisions performed using the rebar technique, 69 patients were women and 59 patients were men. The average age of the group was 69.5 years (range, 32-83 years). The mean follow-up of the cohort was 37 months (range, 13-109 months). The most common causes for revision were kinematic conflict, periprosthetic joint infection, and aseptic loosening. The median number of rebar screws used was 5 (range, 1-13). Preoperative KSSs for the study cohort averaged 50 (range, 0-90) At latest follow-up, mean KSS was 85 (range, 54-100). There were 4 patellar-related complications (3.1%) with no implant failures at study conclusion. Retrieval analysis revealed rigid fixation of the reconstructed patellar component in all cases.

CONCLUSIONS

Patellar rebar screw augmentation is a useful technique when there are significant cavitary deficiencies and limited segmental rim deficiencies. This technique allows the surgeon to extend indications for patellar revision arthroplasty.

Impact of Tibial Tubercle Osteotomy on Final Outcome in Revision Total Knee Arthroplasty: Our Experience and Technique in Pakistan

Backgroud

Due to extensive fibrosis during revision surgery, adequate exposure is essential and it can be achieved with several extensile approach options, such as tibial tubercle osteotomy. Information regarding surgical exposure during revision arthroplasty is limited in developing countries, such as Pakistan, due to the lack of adequate data collection and follow-up. Therefore, the purpose of this study was to evaluate the impact of tibial tubercle osteotomy on final outcome of revision total knee arthroplasty (TKA).

Methods

A total of 231 revision TKAs were performed between January 2008 and December 2017. Twenty-nine patients underwent tibial tubercle osteotomy for adequate exposure during revision surgery. Of these, 27 patients with complete follow-up were included in our study. Factors examined include age at the time of revision surgery, gender, comorbidities, arthroplasty site (right or left), body mass index (BMI), and primary indications for the tibial tubercle osteotomy during revision TKA. Functional outcome was measured by using Knee Society score (KSS) at 3 months and the final follow-up. All statistical analysis was done using SPSS version 20.0 with a p-value < 0.05 considered significant.

Results

Out of 27 patients, 6 patients (22.2%) were men and 21 patients (77.7%) were women. Right knee revision arthroplasty was performed in 15 patients (55.5%), left knee revision arthroplasty was performed in 12 patients (44.4%), and bilateral revision surgery was performed in only 1 patient (3.7%). The mean BMI was 29.2 kg/m². We used a constrained condylar knee in 20 patients (74%), a rotating hinge knee in 5 patients (18.5%), and mobile bearing tray plus metaphyseal sleeves in 2 patients (7.4%). The KSS was 52.21 ± 4.05 preoperatively, and 79.42 ± 2.2 and 80.12 ± 1.33 at 3 months and 12 months, respectively. Radiological union was achieved in all patients at 3 months. Of 27 patients, only 1 patient (3.7%) had proximal migration of the osteotomy site at 6 months: the patient was asymptomatic and union was also achieved and, therefore, no surgical intervention was performed.

Conclusions

Tibial tubercle osteotomy during revision TKA can be a safe and reliable technique with superior outcomes and minimal complication rates.

A classification-based approach to the patella in revision total knee arthroplasty

Background

There is a paucity of data to guide management of the patella in revision total knee arthroplasty (RTKA). The purpose of this study was to review our experience with patellar management in RTKA.

Methods

We retrospectively reviewed 422 consecutive RTKAs at a minimum of 2 years (mean, 42 months). Patellar management was guided by a classification that considered stability, size, and position of the implanted patellar component, thickness/quality of remaining bone stock, and extensor mechanism competence.

Results

Management in 304 aseptic revisions included retention of a well-fixed component in 212 (69.7%) and revision using an all-polyethylene component in 46 (15.1%). Patella-related complications included 5 extensor mechanism ruptures (1.6%), 3 cases of patellar maltracking (1.0%), and 2 periprosthetic patellar fractures (0.7%). Of 118 2-stage revisions for infection, an all-polyethylene component was used in 88 (74.6%), patelloplasty in 20 (16.9%), and patellectomy in 7 (5.9%). Patella-related complications included 4 cases of patellar maltracking (3.4%), 3 extensor mechanism ruptures (2.5%), and 1 periprosthetic patellar fracture (0.8%).

Conclusions

Septic revisions required concomitant lateral releases more frequently (38.1% vs 10.9%; P < .02) but had a similar rate of patellar complications (6.8% vs 3.3%; P = .40). No cases required rerevision specifically for failure of the patellar component. Patients who had a patelloplasty had worse postoperative Knee Society functional scores than those with a retained or revised patellar component. In most aseptic RTKAs, a well-fixed patellar component can be retained. If revision is required, a standard polyethylene component is sufficient in most septic and aseptic revisions. Rerevisions related to the patellar component are infrequent.