Study: Patellar resurfacing during TKA is safe in patients with thin patellae
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GRAPEVINE, Texas — Patients with a thin native patella who underwent patellar resurfacing during primary total knee arthroplasty had 98% survivorship free of patellar revision at median 10-year follow-up, according to a presenter.
At the American Association of Hip and Knee Surgeons Annual Meeting, here, Jacob M. Wilson, MD, presented results of a study he and his colleagues at the Mayo Clinic conducted to determine whether resurfacing a thin patella is a safe practice during primary TKA. The rationale for the study was the fact inadequate native patella thickness has been cited as a reason to resurface the patella, he said.
“There was good survivorship and clinical outcomes achieved in resurfacing the thin native patella. That being said, we had three nonoperative periprosthetic patella fractures and one aseptic failure with patellar clunk, and, therefore, we feel the need should actually be weighed against the known risk of leaving the patella un-resurfaced in this known cohort,” Wilson said.
Measured patellar thickness
Wilson and his colleagues identified 11,333 patients in the Mayo Clinic total joint registry who underwent primary TKA with patellar resurfacing from 2000 to 2010. Of those patients, 200 (2.7%) had a thin patella that measured less than or equal to 19-mm thick before resection. These patients also had post-resection patellar measurements available.
Using calipers, patients had their patellar thickness measured pre-resection and post-resection. The median thickness was 19 mm (range 2 mm to 9 mm) and 12.5 mm (range 10 mm to 17 mm), respectively, according to the abstract.
The designs of resurfaced patellae used were cemented, all-polyethylene with a median diameter of 32 mm. In addition, 93% of the patients were women. The mean age was 69 years, and the BMI was 31 kg.m2, Wilson said.
“The 10-year survivorship free of patellar-related complications was 96.5% at 10 years. We then specifically looked at survivorship free of periprosthetic patellar fracture at 10 years and this was 98.9%,” Wilson said.
Overall, there were seven patellar-related complications in the cohort with three periprosthetic fractures, all of which occurred in female patients with an intact extensor mechanism and a well-fixed component. These patients underwent nonoperative management, according to Wilson. “[Patients had] a pre-resection thickness of 16 [mm] to 19 mm and post-resection thickness of 12 [mm] to 14 mm, but these fractures occurred in patients who were not overly thin.”
In addition, researchers identified one case of patellar aseptic loosening.
Knee Society Scores improved
“Regarding the clinical outcomes, the preoperative Knee Society Score (KSS) was low with a mean of 36. It did improve significantly postoperatively at 2, 5 and 10 years. At 10 years, the mean KSS was 81,” Wilson said.
The study received the AAHKS Surgical Techniques and Technologies Award, which recognizes outstanding surgical innovation advancements in reconstructive surgery.
“We were honored to receive the AAHKS Surgical Techniques and Technologies Award for our paper on resurfacing the thin native patella. Patients with a thin patella often have significant patellofemoral arthritis, and prior data from our institution found higher revision rates in similar patients who were left un-resurfaced. For this reason, we sought to determine whether resurfacing was safe in this patient population. Our results suggest that this is a safe practice, and we hope these data will be useful to surgeons when encountering this clinical situation,” Wilson said in a press release from AAHKS.
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Wilson JM, et al. Resurfacing the thin native patella: Is it safe? Presented at: American Association of Hip and Knee Surgeons Annual Meeting; Nov. 3-6, 2022; Grapevine, Texas.
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