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Pseudo-patella baja after total knee arthroplasty.

Kazemi SM, Daftari Besheli L, Eajazi A, Miniator Sajadi MR, Okhovatpoor MA, Farhang Zanganeh R, Minaei R - Med. Sci. Monit. (2011)

Bottom Line: The average follow-up was 27.5 months.KSS was lower in groups B and C compared with group A, but this difference was not statistically significant.Furthermore, KSS in the PPB group was less than in patients without PPB, although the difference was not statistically meaningful.

View Article: PubMed Central - PubMed

Affiliation: Akhtar Orthopaedic Research Center, Shahid Beheshti Medical University, Tehran, Iran.

ABSTRACT

Background: One of the complications of total knee arthroplasty (TKA) which has not yet been directly addressed is pseudo-patella baja (PPB). True patella baja (PB) is present when the length of the patellar tendon becomes shorter. PPB is present when the patella tendon is not shortened, but the level of the joint line is elevated. This study was conducted to assess PPB in TKA.

Material/methods: Sixty patients who had had a primary TKA at our center between 1995 and 2005 were included. The average follow-up was 27.5 months. The Knee Society Scoring (KSS), lateral knee x-rays and the Blackburne-Peel index were used for assessments.

Results: Out of the 60 patients, 43 (72%) demonstrated no joint line elevation or patellar tendon shortening (group A). Fifteen patients (25%) had joint line elevation (group B), and both PB and PPB were present in 2 (3%) patients (group C). KSS was lower in groups B and C compared with group A, but this difference was not statistically significant. The average range of motion (ROM) in group A was significantly higher compared with either group B or C, and patients in groups B and C showed significantly more severe pain compared with group A (P<0.001).

Conclusions: PPB is not an uncommon finding after TKA and is associated with a statistically significant decrease in ROM and an increase in pain. Furthermore, KSS in the PPB group was less than in patients without PPB, although the difference was not statistically meaningful.

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Related in: MedlinePlus

Insall-Salvati index, the ratio of the length of patellar tendon (a) to the longest (diagonal) length of patella (b).
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f1-medscimonit-17-5-cr292: Insall-Salvati index, the ratio of the length of patellar tendon (a) to the longest (diagonal) length of patella (b).

Mentions: In this study we chose to use the Insall Salvati ratio (ISR) for the diagnosis of patella baja. The basic pathology in patella baja is a shortened infra-patellar tendon; therefore, we devised a ratio that takes the length of this tendon into account, enabling us to differentiate between a normally placed patella and one that is inferiorly placed (patella baja). This is the ratio of the patellar tendon length to the length of the patella as judged on the lateral X-ray taken in 30° of flexion (patellar tendon length/patellar length) (Figure 1). ISR <0.8 was defined as PB (the normal ISR is 1±0.2) [2,15].


Pseudo-patella baja after total knee arthroplasty.

Kazemi SM, Daftari Besheli L, Eajazi A, Miniator Sajadi MR, Okhovatpoor MA, Farhang Zanganeh R, Minaei R - Med. Sci. Monit. (2011)

Insall-Salvati index, the ratio of the length of patellar tendon (a) to the longest (diagonal) length of patella (b).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539587&req=5

f1-medscimonit-17-5-cr292: Insall-Salvati index, the ratio of the length of patellar tendon (a) to the longest (diagonal) length of patella (b).
Mentions: In this study we chose to use the Insall Salvati ratio (ISR) for the diagnosis of patella baja. The basic pathology in patella baja is a shortened infra-patellar tendon; therefore, we devised a ratio that takes the length of this tendon into account, enabling us to differentiate between a normally placed patella and one that is inferiorly placed (patella baja). This is the ratio of the patellar tendon length to the length of the patella as judged on the lateral X-ray taken in 30° of flexion (patellar tendon length/patellar length) (Figure 1). ISR <0.8 was defined as PB (the normal ISR is 1±0.2) [2,15].

Bottom Line: The average follow-up was 27.5 months.KSS was lower in groups B and C compared with group A, but this difference was not statistically significant.Furthermore, KSS in the PPB group was less than in patients without PPB, although the difference was not statistically meaningful.

View Article: PubMed Central - PubMed

Affiliation: Akhtar Orthopaedic Research Center, Shahid Beheshti Medical University, Tehran, Iran.

ABSTRACT

Background: One of the complications of total knee arthroplasty (TKA) which has not yet been directly addressed is pseudo-patella baja (PPB). True patella baja (PB) is present when the length of the patellar tendon becomes shorter. PPB is present when the patella tendon is not shortened, but the level of the joint line is elevated. This study was conducted to assess PPB in TKA.

Material/methods: Sixty patients who had had a primary TKA at our center between 1995 and 2005 were included. The average follow-up was 27.5 months. The Knee Society Scoring (KSS), lateral knee x-rays and the Blackburne-Peel index were used for assessments.

Results: Out of the 60 patients, 43 (72%) demonstrated no joint line elevation or patellar tendon shortening (group A). Fifteen patients (25%) had joint line elevation (group B), and both PB and PPB were present in 2 (3%) patients (group C). KSS was lower in groups B and C compared with group A, but this difference was not statistically significant. The average range of motion (ROM) in group A was significantly higher compared with either group B or C, and patients in groups B and C showed significantly more severe pain compared with group A (P<0.001).

Conclusions: PPB is not an uncommon finding after TKA and is associated with a statistically significant decrease in ROM and an increase in pain. Furthermore, KSS in the PPB group was less than in patients without PPB, although the difference was not statistically meaningful.

Show MeSH
Related in: MedlinePlus