Using ultrasound contrast agents to assess tendon healing

Abstract

ObjectiveTo describe the role of vascularity in assessing bone tendon healing and describe the application of ultrasound contrast agents in quantitative and visual assessment of the vascular following repair with attention to the rotator cuff.SummaryRotator cuff tears are common, having been described in up to 20.7% of the general population and accounting for approximately 75,000 operations in the United States per year. The reported prevalence of failure of rotator cuff repairs has varied in the literature, ranging from 19-94%. Various factors are thought to account for poor healing of the repair, including intrinsic tendon degeneration, fatty infiltration of the muscle and tendon, muscle atrophy, poor bone quality, and weak tendon-to-bone fixation.Experimental studies have shown that bone-tendon healing begins with the formation of fibrovascular scar tissue between the tendon and bone, followed by gradual bone ingrowth into this fibrous interface extending into the native tendon. Tendon repair therefore involves multiple phases: an inflammatory phase, reparative phase and finally remodeling phase. These phases are linked to a variety of growth factors that appear most active in a temporal sequence. Consequently, an area of active investigation is to determine methods to augment bone-tendon and tendon-tendon healing using endogenous growth factors, such as those derived from platelet rich aggregates to promote bone tendon healing.The role of imaging in this scenario is to provide a non-invasive means to potentially determine various phases of healing and to assess the outcomes of either primary repair or interventions meant to augment healing. In the current talk, we briefly describe the sequence of events associated with tendon degeneration, tearing and subsequent bone-tendon healing, following repair. In particular we review the role of contrast enhanced ultrasound in depicting the temporal changes in vascularity following rotator cuff repair. To describe the role of vascularity in assessing bone tendon healing and describe the application of ultrasound contrast agents in quantitative and visual assessment of the vascular following repair with attention to the rotator cuff. Rotator cuff tears are common, having been described in up to 20.7% of the general population and accounting for approximately 75,000 operations in the United States per year. The reported prevalence of failure of rotator cuff repairs has varied in the literature, ranging from 19-94%. Various factors are thought to account for poor healing of the repair, including intrinsic tendon degeneration, fatty infiltration of the muscle and tendon, muscle atrophy, poor bone quality, and weak tendon-to-bone fixation. Experimental studies have shown that bone-tendon healing begins with the formation of fibrovascular scar tissue between the tendon and bone, followed by gradual bone ingrowth into this fibrous interface extending into the native tendon. Tendon repair therefore involves multiple phases: an inflammatory phase, reparative phase and finally remodeling phase. These phases are linked to a variety of growth factors that appear most active in a temporal sequence. Consequently, an area of active investigation is to determine methods to augment bone-tendon and tendon-tendon healing using endogenous growth factors, such as those derived from platelet rich aggregates to promote bone tendon healing. The role of imaging in this scenario is to provide a non-invasive means to potentially determine various phases of healing and to assess the outcomes of either primary repair or interventions meant to augment healing. In the current talk, we briefly describe the sequence of events associated with tendon degeneration, tearing and subsequent bone-tendon healing, following repair. In particular we review the role of contrast enhanced ultrasound in depicting the temporal changes in vascularity following rotator cuff repair.