Onishi and Colleagues Wrap Up the Year with Preoperative Ultrasound and Platelet-Rich Plasma Studies

December 8, 2021

Kentaro Onishi, DO, assistant professor in the Departments of Physical Medicine & Rehabilitation and Orthopaedic Surgery at the University of Pittsburgh, collaborated with local and international colleagues to publish two promising studies in the American Journal of Sports Medicine and PLOS ONE in fall 2021. One study addresses morphological evaluation of the quadriceps tendon using preoperative ultrasound in anterior cruciate ligament reconstruction, while the other tackles platelet HMGB1 in platelet-rich plasma (PRP) in the promotion of tendon wound healing. The following include brief overviews of the studies and recognize contributing colleagues.

Morphological Evaluation of the Quadriceps Tendon

An evaluation of quadriceps tendon (QT) morphology preoperatively is an important step when selecting an individually appropriate autograft for anterior cruciate ligament (ACL) reconstruction. However, to the team’s knowledge, there are no studies that have assessed the morphology of the entire QT in an ACL-injured knee preoperatively using ultrasound. In this study, they aimed to investigate the morphological characteristics of the QT using preoperative ultrasound in ACL-injured knees. 

A total of 33 patients (mean age, 26.0 ± 11.5 years) with a diagnosed ACL tear undergoing primary ACL reconstruction were prospectively included. Using ultrasound, short-axis images of the QT were acquired in 10-mm increments from 30 to 100 mm proximal to the superior pole of the patella. The length of the QT was determined by 2 contiguous images that did and did not contain the rectus femoris muscle belly. The width of the superficial and narrowest parts of the QT, the thickness of the central and thickest parts of the QT, and the cross-sectional area at the central 10 mm of the superficial QT width were measured at each assessment location. The estimated intraoperative diameter of the QT autograft was calculated using a formula provided in a previous study.

This study showed no significant relationships between QT morphology and any of the demographic data collected. The length of the QT was less than 70 mm in 45.5% of patients (15/33). The width, thickness, cross-sectional area, and estimated intraoperative diameter of the QT autograft were significantly greater at 30 mm than at 70 mm proximal to the superior pole of the patella.

Preoperative ultrasound may identify a QT that is too small for an all–soft tissue autograft in ACL reconstruction. Furthermore, harvesting a QT with a fixed width may result in autografts that are smaller proximally than they are distally. Assessing the morphology of the QT preoperatively using ultrasound may help surgeons to adequately reconstruct the native length and diameter of the ACL with a QT autograft.

View the full study.

Other Contributors

Satoshi Takeuchi, MD
Department of Orthopaedic Surgery, Toyohashi Medical Center, Toyohashi, Japan

Kevin J. Byrne, MD
Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA

Ryo Kanto, MD, PhD
Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA

Freddie H. Fu, MD, DSc (Hon)
Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA

Platelet HMGB1 in Platelet-Rich Plasma (PRP)

Platelet-rich plasma (PRP) is a widely used autologous treatment for tendon injuries in clinics. Platelets (PLTs) are a major source of high mobility group box1 (HMGB1) that is gaining attention as a chemoattractant that can recruit stem cells to the wound area to enhance healing of injured tissues; however, the contribution of PLT HMGB1 in wounded tendon healing remains unexplored. This study investigated the effect of PLT HMGB1 within PRP on tendon healing using PLT HMGB1 knockout (KO) and GFP mice. 

A window defect was created in the patellar tendons of both groups of mice, and wounds were treated with either saline, PRP isolated from PLT HMGB1-KO mice, or PRP isolated from GFP mice. Seven days post-treatment, animals were sacrificed and analyzed by gross inspection, histology, and immunostaining for characteristic signs of tendon healing and repair.

The team’s results showed that, in comparison to mice treated with PRP from PLT HMGB1-KO mice, wounds treated with PRP from GFP mice healed faster and exhibited a better organization in tendon structure. Mice treated with PRP from PLT HMGB1-KO mice produced tendon tissue with large premature wound areas and low cell densities. However, wounds of PLT HMGB1-KO mice showed better healing with PRP from HMGB1-KO mice compared to saline treatment. Moreover, wounds treated with PRP from GFP mice had increased extracellular HMGB1, decreased CD68, increased stem cell markers CD146 and CD73, and increased collagen III protein expression levels compared to those treated with PRP from PLT HMGB1-KO mice.

They concluded that PLT HMGB1 within PRP plays an important role in tendon wound healing by decreasing inflammation, increasing local HMGB1 levels, and recruiting stem cells to the wound area in the tendon. The team’s findings also suggest that the efficacy of PRP treatment for tendon injuries in clinics may depend on PLT HMGB1 within PRP preparations.

View the full study.

Other Contributors

Jianying Zhang
MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA

Feng Li
MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA

Tyler Augi
MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA

Kelly M. Williamson
MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA

MaCalus V. Hogan
MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA

Matthew D. Neal
Department of Surgery, University of Pittsburgh, Pittsburgh, PA, USA

James H-C. Wang
MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA