The Variation of the Patellar Height in Total Knee Arthroplasties and its Relationship with the Replacement or not of the Patella

Cenni, Marcos Henrique Frauendorf; Pinheiro Junior, Lúcio Flávio Biondi; Oliveira, Mateus Aguilar de; Lago, Augusto Groberio; Rodrigues, Raphael Cardoso

doi:10.1055/s-0041-1736468

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Original Article • Rev. bras. ortop. 58 (1) • Jan-Feb 2023 • https://doi.org/10.1055/s-0041-1736468 copy

The Variation of the Patellar Height in Total Knee Arthroplasties and its Relationship with the Replacement or not of the Patella

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Objective

To compare the measurement of patellar height in the pre- and postoperative period of total knee arthroplasties (TKAs) and its variation in patients with and without patellar replacement.

Methods

Retrospective evaluation of radiographs of patients submitted to TKA between 2014 and 2020. Profile radiographs were evaluated using the modified Caton-Deschamps patellar height index, comparing the pre- and postoperative measurements of 90 patients, with a total of 100 knees. Next, two groups were compared with a different surgical technique, considering the replacement or not of the patella. All patients who had x-rays evaluated had indication of TKA by osteoarthrosis without previous procedures that could interfere at patellar height.

Results

The statistical analysis showed a statistically significant difference, with the preoperative index superior to the postoperative rate, evidencing an overall decrease in patellar height. The Caton-Deschamps index modified for mean preoperative TKA was 1.41 (±0.25), and it was 1.31 (± 0.25), p< 0.001for postoperative TKA.

No significant difference was found in the variation of this index when comparing the groups with and without patellar replacement. The mean difference of the index in the group without patella was 0.11, and 0.08 in the group with patella, and this difference was considered nonsignificant, p= 0.510.

Conclusion

We can conclude that patellar height had significant variation in the total group, with reduction of patellar height in the postoperative period. However, the height did not vary significantly between the postoperative groups with and without patellar replacement, regardless of the choice of the surgeon.

Keywords
patella; knee prosthesis; arthroplasty, replacement, knee

Variables	n	%
Age (mean ± SD)	68.8 ± 7.2
Gender
Male	31	34.4
Female	59	65.3
Operated knee
Right	52	52.0
Left	38	38.0
Both	10	10.0
Type of surgery
No patella	54	54.0
With patella	46	46.0

Variable	n	Pre	Post	Average of differences	95%CI	p-value
		CDM index: mean (±SD)				p-value
CDM index	100	1.41 (±0.25)	1.31 (±0.25)	0.1	0.05-0.15	< 0.001 ^* * Teste T pareado.
Group
No patella	54	1.52 (±0.22)	1.40 (±0.24)	0.12	0.05-0.18	< 0.001 ^* * Teste T pareado.
With patella	46	1.28 (±0.21)	1.20 (±0.21)	0.08	0.01-0.15	0.023 ^* * Teste T pareado.
Average difference		0.24	0.2
95%CI		0.15-0.32	0.11-0.29
*p-value*		< 0.001 ^ Teste T para grupos independents.	< 0.001 ^ Teste T para grupos independents.

Type of surgery		n	Mean	Standard deviation	Standard error of mean
Age	Without patella	54	68.5556	8.00864	1.08984
Age	With patella	46	69.1522	6.21814	.91681

			Type of surgery		Total
			Without patella	With patella	Total
Gender	Female	n	34	30	64
	Female	%	63.0%	65.2%	64.0%
	Male	n	20	16	36
	Male	%	37.0%	34.8%	36.0%
Total		n	54	46	100
Total		%	100.0%	100.0%	100.0%

CDM index		n	Average	Standard deviation	Average difference	95%CI		p-value ^* * T test for independent groups.
Difference from post to pre	Without patella	54	0.11	0.24	0.03	−0.13	0.06	0.510
Difference from post to pre	With patella	46	0.08	0.24		−0.13	0.06	0.510

Sociedade Brasileira de Ortopedia e Traumatologia Al. Lorena, 427 14º andar, 01424-000 São Paulo - SP - Brasil, Tel.: 55 11 2137-5400 - São Paulo - SP - Brazil
E-mail: rbo@sbot.org.br

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[1] Address for correspondence Marcos Henrique Frauendorf Cenni, Rua Felipe dos Santos, 760, apto 602-T2, Lourdes, Belo Horizonte, MG, CEP 30180-160, Brazil (e-mail: cenni14@gmail.com).