2017 ISAKOS Biennial Congress ePoster #1120

 

The Dynamics of Infrapatellar Fat Pad Decreases after Anterior Cruciate Ligament Reconstruction

Takashi Kitagawa, PT, MSc, Kanazawa, Ishikawa JAPAN
Junsuke Nakase, MD, PhD, Kanazawa, Ishikawa JAPAN
Takeshi Oshima, MD, PhD, Kanazawa, Ishikawa JAPAN
Yasushi Takata, MD, Kanazawa, Ishikawa JAPAN
Hiroyuki Tsuchiya, Kanazawa, Ishikawa JAPAN

Department of Rehabilitation, Kanazawa Red Cross Hospital, Kanazawa city, Ishikawa, JAPAN

FDA Status Not Applicable

Summary

The thickness at a knee flexion of 90° and thickness change ratio of the IPFP decreased after ACLR.

Abstract

Background

Infrapatellar fat pad (IPFP) is one of the knee fat pads and is richly innervated and, therefore, one of the sources of anterior knee pain. Because surgical treatment has the possibility to affect anterior knee structures, the anterior knee pain after anterior cruciate ligament reconstruction (ACLR) may be caused by abnormality of IPFP. The shape and dynamics of the IPFP might be changed after ACLR, but few studies have investigated these changes objectively. In the present study, we aimed to compare the dynamics of the IPFP in a reconstructed knee with those in the contralateral knee by examining the knee joints of patients who underwent ACLR.

Material And Method

Fourteen patients (average age 27.3 ± 11.5 years; 7 male and 7 female) provided informed consent to evaluate their IPFP by ultrasound 6 months post-operatively. Inclusion criteria were as follows: anatomic single-bundle reconstruction with a hamstring tendon grafts, and a knee flexion range of motion of 90° to 10°. Exclusion criteria were as follows: previous ligament reconstruction, bilateral ACL injuries. Patients were examined by an experienced physiotherapist at a knee flexion of 90° and 10°. Longitudinal ultrasonographic images of the anterior part of the knees were taken at the center of the patellar tendon, along the tendon fiber, in order to capture the IPFP and the patellar apex. The IPFP in the images were divided into superficial and deep parts. The superficial part of the IPFP was defined as a low echo intensity area of the upper layer of IPFP, and the thickness was measured 10 mm away from the patellar apex. The thickness was measured by using Image J. Differences between injured and uninjured knees were examined.

Results

At a knee flexion of 90°, we found a significant difference in the mean thickness of the superficial area of the IPFP between uninjured (12.4 ± 0.5 mm) and injured (11.6 ± 0.8 mm) knees (p < 0.001), as well as in the thickness change ratio of the superficial area of the IPFP before and after surgery between uninjured (256 ± 84%) and injured (182 ± 64%) knees (p < 0.001). We did not find a significant difference in the mean thickness of the superficial part of the IPFP between uninjured (5.3 ± 3.0 mm) and injured (6.9 ± 4.5 mm) knees (p = 0.49) at a flexion of 10°.

Discussion

The thickness at a knee flexion of 90°and thickness change ratio of the superficial part of the IPFP decreased after ACLR. The superficial part of the IPFP denotes the area of the IPFP above the vertical cleft and separates the IPFP into the central body and the superior tag areas. When the IPFP is resected during an operation, adhesions across the IPFP develop, decreasing mobility of the IPFP. Dysfunction of the IPFP may subsequently cause complications. Further studies are needed to determine the relationship between the IPFP and knee function.

Conclusion

The thickness at a knee flexion of 90° and thickness change ratio of the IPFP decreased after ACLR.