Selective Patella Resurfacing in Contemporary Cruciate Retaining and Substituting Total Knee Arthroplasty: A Matched Cohort Analysis

Outcomes of Selectively Unresurfaced Patellae With a Partial Lateral Facetectomy in Primary Total Knee Arthroplasty

BACKGROUND

Not resurfacing the patella during primary total knee arthroplasty (TKA) has steadily increased as implants and techniques have improved. However, limited data exist on the acceptable arthritis severity to leave the patella unresurfaced and the subsequent effect on patient-reported outcome measures (PROMs). This study evaluated PROMs in matched cohorts of unresurfaced and resurfaced patellae, accounting for patellar osteoarthritis (OA) severity and lateral patellar facetectomies.

METHODS

A consecutive series of primary TKAs was retrospectively reviewed. There were 871 patellae selectively unresurfaced, of which 667 (76%) had an aggressive lateral facetectomy. The remaining 1,064 patellae were resurfaced. The TKAs with unresurfaced patellae were matched to TKAs with resurfaced patellae based on demographics and patellar OA severity. There were 140 TKAs in each matched group, which did not differ by demographics (P ≥ 0.33) or OA severity (P ≥ 0.99). The PROMs were compared between groups at a mean of 2.7 years (range, one to 10) at a significance level of 0.05.

RESULTS

The matched groups did not differ by postoperative knee-specific PROMs (P ≥ 0.23) nor improvement from the preoperative baseline score (P ≥ 0.19). A greater percentage of patients who had unresurfaced patellae and a lateral facetectomy achieved minimal clinically important differences for the Knee Injury and Osteoarthritis Outcome Score (94, 89, 86%) and pain with stairs (88, 85, 81%) compared to patella groups without a lateral facetectomy, despite lacking statistical significance (P ≥ 0.30). The change in PROMs for patients who had moderate to severe patello-femoral arthritis grade ≥ 2 was not different between patella groups (P ≥ 0.38).

CONCLUSIONS

Study results show that patients who had unresurfaced and resurfaced patellae have similar PROMs after TKA regardless of patello-femoral OA severity. An aggressive lateral facetectomy when leaving the patella unresurfaced may help achieve minimal clinically important differences in PROMs more frequently.

Cementless Total Knee Arthroplasty Using an Ultraconforming Tibial Bearing: Outcomes at Minimum 5-Year Follow-Up

BACKGROUND

Cementless fixation for primary total knee arthroplasty (TKA) continues to increase in the United States. However, compared to cemented TKA, reports on revision rates have been mixed. A confounding variable may include the tibial insert design. This study aimed to assess the minimum 5-year survivorship and outcomes of a cementless TKA using an ultracongruent (UC) articulation.

METHODS

A consecutive series of 242 cementless TKAs were implanted at two institutions between 2017 and 2019 using an UC kinematic tibial insert. Of the patients, 56% were men. The average age was 60 years. Patients were followed using Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and Knee Society clinical and radiographic scores. Preoperative and postoperative radiographs were classified according to the Coronal Plane Alignment of the Knee (CPAK) type. The average follow-up was 5.6 years (range, five to 7.5).

RESULTS

At the final follow-up, KOOS-JR scores averaged 84.0. Knee Society scores averaged 94. Flexion averaged 116°. There were seven manipulations (2.9%), one patella fracture, and no deep infections. There were seven knees (2.9%) revised (three for flexion instability, one for pain, one for femoral fibrous ingrowth, one for distal femur fracture, and one for arthrofibrosis). At 5 years, survivorship free from aseptic loosening was 99.6%. Change in CPAK type did not correlate with final KOOS-JR, pain, University of California Los Angeles activity score, or satisfaction scores.

CONCLUSIONS

Cementless TKA using this conforming design has provided excellent clinical results out to 5 years. Once initial component stability is achieved, the UC nature of this articulation does not appear to adversely influence the durability of implant fixation, regardless of whether the CPAK type was changed.

New evidence on patella resurfacing in modern total knee arthroplasty for all inflammatory arthritis in a mixed Asian population

Background

Traditional teaching advocates for routine patella resurfacing (PR) during total knee arthroplasty (TKA) in patients with inflammatory arthritis. However, evidence on this topic remains limited in the Asian population. This study aims to evaluate the postoperative outcomes and complication of patella resurfacing (PR) during primary total knee arthroplasty (TKA) in Asian patients with inflammatory arthritis.

Methods

A retrospective analysis was conducted using registry data from our institution. Patients with inflammatory arthritis who underwent primary TKA from August 2017 to December 2021 were included in the study. Patients were divided into two groups - patella resurfaced (PR, n = 25) and non-resurfaced patella (PNR, n = 31) groups. Demographics, operative data, patient reported outcome measures, and complications were compared.

Results

Preoperative range of motion (ROM) (PR:95.3 ± 23.6° vs PNR:105 ± 19.5°, p = 0.106), Knee Society Scoring System Knee score (KS-KS) (PR:44.6 ± 17.4 vs PNR:49.3 ± 17.7, p = 0.331) and Knee Society Function Score (KS-FS) (PR:40.9 ± 27.3 vs PNR:47.7 ± 27.0, p = 0.325) and Oxford Knee Score (OKS) (PR:25.0 ± 7.8 vs PNR:23.3 ± 10.3, p = 0.525) were similar in both groups. Outcomes between PR and PNR groups at the one-year mark in terms of ROM (PR:112.7 ± 18.1 vs PNR:114.6 ± 16.5, p = 0.455), OKS (PR:41.5 ± 3.9 vs PNR:41 ± 4.7, p = 0.954), KS-KS (PR:84.5 ± 13.2 vs PNR:89.2 ± 9.3, p = 0.095) and KS-FS (PR:73.6 ± 18.3 vs PNR:78.7 ± 19.3, p = 0.173) were also similar. Intraoperative complication (PR:0/25 vs PNR: 3/31 (9.6 %), p = 0.245) and re-operation rates (PR: 1/25 (4 %) vs PNR: 1/31 (3.2 %), p = 0.877) were also similar in both groups.

Conclusion

This study conducted on a mixed Asian population with inflammatory arthritis demonstrated that the one-year postoperative ROM and functional outcomes, complication, and re-operation rates between PR and PNR groups were similar. Hence, routine patella resurfacing on all Asian patients with inflammatory arthritis undergoing TKA may not be necessary.

The Fate of Unresurfaced Patellae in Contemporary Total Knee Arthroplasty: Early to Midterm Results

BACKGROUND

Leaving the patella unresurfaced in total knee arthroplasty (TKA) has increased significantly over the past decade in the United States, likely due to modern patella-friendly implants, complications with resurfacing, and the knowledge that historical studies were scientifically confounded. This study evaluated revision-free survivorship out to 8.5 years in a cohort of contemporary primary TKAs with patella-friendly femoral components and unresurfaced patellae.

METHODS

A total of 1,053 consecutive primary TKAs with unresurfaced patellae were retrospectively reviewed. A selective patellar nonresurfacing protocol was used for all cases. Kaplan-Meier survivorship estimates were calculated based on patellar revision and the latest follow-up. An aggressive lateral patellar facetectomy was performed in 78% (823 of 1,053) of cases. The cohort was 62% women and 43% American Society of Anesthesiologists physical status classification I or II with a mean age and body mass index of 65 years (range, 35 to 94) and 35 kg/m2 (range, 18 to 65), respectively.

RESULTS

A total of 4 (0.4%, 4 of 1,053) unresurfaced patellae were revised. Three were resurfaced as part of other procedures: 2 for global instability and one for aseptic loosening at a mean of 1.6 years; and one patella was resurfaced by an outside surgeon for unexplained pain. The all-cause revision-free survivorship estimate specifically related to the patella was 98.9% (95% confidence interval, 98 to 100) out to 8.5 years. No significant difference in survivorship was related to patellae with or without a lateral patellar facetectomy (99.5 versus 98.1%, P ≥ .191); however, 3 of 4 patellar revisions occurred in TKAs without a lateral patellar facetectomy (P = .035).

CONCLUSIONS

The results of this study demonstrate excellent revision-free survivorship related to unresurfaced patellae, particularly when a lateral facetectomy was performed. These early to midterm results using modern patella-friendly femoral components are promising and comparable to resurfaced patellae in the literature.

LEVEL OF EVIDENCE

IV.

Cementless Total Knee Arthroplasty: Is it Safe in Demineralized Bone?

There is concern for cementless total knee arthroplasty (TKA) in patients with decreased bone mineral density (BMD) due to the potential increase in complications, namely failed in-growth or future aseptic loosening. Some data suggest that advances in cementless prostheses mitigate these risks; however this is not yet born out in long-term registry data. It is crucial to expand our understanding of the prevalence and etiology of osteoporosis in TKA patients, survivorship of cementless implants in decreased BMD, role of bone-modifying agents, indications and technical considerations for cementless TKA in patients with decreased BMD. The purpose of this study is to review current literature and expert opinion on such topics.

Development of application and surgical technique of total knee arthroplasties: a systematic comparative analysis using worldwide registers

PURPOSE

The aim was to compare total knee arthroplasty (TKA) between countries with regard to epidemiologic data and surgical technique by the use of worldwide registers and compare findings with a previous report after one decade.

METHODS

A systematic search was carried out in November 2022 and compared to previous reports from 2010. We extracted data regarding implanted TKAs, patients' age distribution, procedure types, fixation and revision rates. After identification of 28 national arthroplasty registers, 8of them, namely Australia, Canada, Denmark, England and Wales, New Zealand, Norway, Scotland and Sweden, offered sufficient data and were included in final analysis.

RESULTS

A large variation was found in the annual number of implantations per 100,000 inhabitants with a range from 77 to 210.2 (mean 132.8). The fixation type varied strongly as well, e.g. over 95% of totally cemented TKAs in Sweden versus 61.2% cemented fixation in Denmark. Another significant difference was the use of patellar resurfacing in TKA, ranging from 47.3% (Canada) using a patellar button in TKA to less than 5% (Sweden). Within the period of one decade, the mean overall number of annual implantations increased (10%), whilst relative number of revisions decreased, the use of cemented TKA decreased from 87 to 74%, and the use of patella button remained largely inhomogeneous.

CONCLUSION

Comparison of arthroplasty registers revealed large differences regarding the annual number of primary TKAs per inhabitant as well as primary TKA procedure types with an increase of annual implantations, decrease of relative number of revisions, and a decrease of the use of cemented systems over the period of one decade.