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. 2015 Jun 13;12(4):197-204.
doi: 10.1016/j.jor.2015.05.015. eCollection 2015 Dec.

Effects of fat pad excision on length of the patellar tendon after total knee replacement

Sanjay S Chougule  1 , Georgios Stefanakis  1 , Stefania C Stefan  1 , Soumen Rudra  1 , George Tselentakis  2
Affiliations

Effects of fat pad excision on length of the patellar tendon after total knee replacement

Sanjay S Chougule et al. J Orthop. .

Abstract

Purpose: We report our results of the effect that total fat pad excision has on patellar tendon length following total knee replacement.

Method: We retrospectively reviewed radiographs of the knees of 133 patients who had Depuy LCS uncemented TKR between January 2009 to December 2009. We excluded patients who had patella resurfacing, lateral release, knee replacement for other than osteoarthritis and who had other implants used. We measured the length of the patellar tendon using the Insall-Salvati ratio.(.) Changes in the length of the tendon were calculated both as an absolute evaluation and as a percentage of the original length.

Results: We effect of fat pad excision on patellar tendon length at 1 year and 5 years following surgery. At one year we observed no change in patellar tendon length in 81.1%, patella infera in 17.3% and patella alta in 1.6% of these 133 patients. We manage to follow up 50 of these patients at 5 years following surgery. In comparison to pre-operative length, at one year 86% showed no change, 14% had patella infera and none had patella alta. At 5 years we observed no change in 98% and patella infera in 2% of patients. Forty nine percent of our patients with patella infera developed anterior knee pain, mean flexion in those patients was 95.625° and mean oxford score was 52.31.

Conclusions: In our patients following single implant design used patella infera developed in up to 18% at one year following surgery. Two percent of fifty patients who had five years follow up showed further shortening of patellar tendon after one year. We conclude that complete fat pad excision during total knee replacement does affect patellar tendon length. Level of evidence IV.

Keywords: Fat pad; Patellar tendon length; Total knee replacement.

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Figures

Fig. 1
Fig. 1
The proportionate change in the length of the patellar tendon −1 Year after operation – 50 patients.
Fig. 2
Fig. 2
The proportionate change in the length of the patellar tendon between 1 Year and 5 years Postoperative – 50 patients.
Fig. 3
Fig. 3
Length of patellar tendon (LOPT) Preoperative vs. Length of patellar tendon (LOPT) at 1 year after operation (133 patients). Scatter plot of the length of patellar tendon Preoperative vs. length of patellar tendon (LOPT) at 1 year after operation with a linear regression line. The size of the plot marker (circle) indicates the number of patients. The horizontal and vertical Histograms show the distribution of the length of patellar tendon preoperative and 1 year postoperative respectively.
Fig. 4
Fig. 4
Length of patellar tendon (LOPT) Preoperative vs. Length of patellar tendon (LOPT) at 1 year after operation for the 50 patients with a 5 years follow-up. Scatter plot of the length of patellar tendon Preoperative vs. length of patellar tendon (LOPT) at 1 year after operation with a linear regression line for the 50 patients with a 5 years follow-up. The size of the plot marker (circle) indicates the number of patients. The horizontal and vertical Histograms show the distribution of the length of patellar tendon preoperative and 1 year postoperative respectively.
Fig. 5
Fig. 5
Diameter of Femoral Shaft Preoperative vs. Diameter of Femoral Shaft Postoperative. Scatter plot of the Diameter of Femoral Shaft Preoperative vs. Diameter of Femoral Shaft Postoperative with a linear regression line. The size of the plot marker (circle) indicates the number of patients. The horizontal and vertical Histograms show the distribution of the Diameter of Femoral Shaft Preoperative vs. Diameter of Femoral Shaft Postoperative respectively. An estimate of accuracy of the measurements of the length of patellar tendon and of the diameter of femoral shaft was made by comparison of the length of patellar tendon and the diameter of femoral shaft on a series of ten knees re-measured on the same radiographs, using the same method, by the same operator, the percent of error being established at 0.44.
Fig. 6
Fig. 6
Length of patellar tendon (LOPT) at 1 year vs. Length of patellar tendon (LOPT) at 5 years after operation. Scatter plot of the length of patellar tendon (LOPT) at 1 year vs. length of patellar tendon (LOPT) at 5 years after operation with a linear regression line. The size of the plot marker (circle) indicates the number of patients. The horizontal and vertical Histograms show the distribution of the length of patellar tendon (LOPT) at 1 year and 5 years postoperative respectively.
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Further readings

    1. Dandy D.J., Desai S.S. Patellar tendon length after anterior cruciate ligament reconstruction. J Bone Jt Surg Br. 1994;76-B:198–199. - PubMed
    1. Scuderi G.R., Windsor R.E., Insall J.N. Observations on patellar height after proximal tibial osteotomy. J Bone Jt Surg Am. 1989;71-A:245–248. - PubMed
    1. Bryan R.S. Patella infra ant fat pad hypertrophy after TKR. Tech Orthop. 1988;3:29–33.
    1. Aho K., Sainio K., Kianta M., Varpanen E. Pneumatic tourniquet paralysis: case report. J Bone Jt Surg Br. 1983;65-B:441–443. - PubMed
    1. Mariani P.P., Del Signore S., Perugia L. Early development of patella infera after knee fractures. Knee Surg Sports Traumatol Arthrosc. 1994;2:166–169. - PubMed

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