Surgical Cutting and Ablation by Energy Based Devices: Principles and Applications

Advances in ultrasound, radiofrequency, and water jet systems are facilitating their increased use in new medical ablation or cutting applications in fields as diverse as cardiology, orthopaedics, ophthalmology, dermatology, oncology and neurosurgery. These methods involve controlled alteration or destruction of tissues via the application of thermal, electrical or kinetic energy. This market segment is characterised by advanced devices capable of heating or cooling tissue from -200°C to 400°C, or inducing vibrations of up to 60 kHz to cause tissue damage. The medical conditions targeted primarily pertain to chronic and age-related diseases, but elective and cosmetic procedures are also addressed. Medical ablation research has the potential for significant clinical and commercial gains. New capabilities in terms of tissue ablation technologies can enable new medical procedures, affording opportunities for design creativity and entrepreneurship and ultimately delivering a health dividend

High Power, Low Frequency Ultrasound: Meniscal Tissue Interaction and Ablation Characteristics

Abstract—This study evaluates high power low frequency ultrasound transmitted via a flat vibrating probe tip as an alternative technology for meniscal debridement in the bovine knee. An experimental force controlled testing rig was constructed using a 20 kHz ultrasonic probe suspended vertically from a load cell. Effect of variation in amplitude of distal tip displacement (242–494 mm peak-peak) settings and force (2.5–4.5 N) on tissue removal rate (TRR) and penetration rate (PR) for 52 bovine meniscus samples was analyzed. Temperature elevation in residual meniscus was measured by embedded thermocouples and histologic analysis. As amplitude or force increases, there is a linear increase in TRR (Mean: 0.9 to 11.2 mg/s) and PR (Mean: 0.08 to 0.73 mm/s). Maximum mean temperatures of 84.6C and 52.3C were recorded in residual tissue at 2 mm and 4 mm from the ultrasound probe-tissue interface. There is an inverse relationship between both amplitude and force, and temperature elevation, with higher settings resulting in less thermal damage.

Total Hip Arthroplasty in Patients With Neurological Conditions: A Systematic Review

Background: As operative techniques and implant design have evolved over time, total hip arthroplasty (THA) is increasingly being carried out for patients with neurological impairment. This patient group places unique surgical challenges to the arthroplasty surgeon, which may include contractures, instability, and altered muscular tone. The purpose of this systematic review is to report the patient outcomes, complications, and implant survival following THA for patients with neurological conditions affecting the hip. Thus, we aim to support orthopaedic surgeon decision-making when considering and planning THA for these patients. Methods: A systematic review was performed as per Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using the PubMed/Medline OVID, Cochrane, and Embase databases. All studies reporting the outcomes of THA in the neurological population which met defined inclusion criteria were included. Results: From an initial screen of 1820 studies, 45 studies with a total of 36,251 THAs were included in the final selection. All 45 studies reported complication rates, with controls included in 16 for comparison. High complication rates were observed following THA in the neurologically impaired population, most notably dislocation with observed rates up to 10.6%. An improvement was noted in all 36 studies (1811 THAs) which reported upon patient-reported outcomes. Conclusions: THA may be beneficial in the selected patients with neurological conditions, to reduce pain and improve function. There is an increased risk of complications which require careful consideration when planning the operation and open discussion with prospective patients and caregivers before proceeding with surgery

Total Hip Arthroplasty in the Setting of Post-traumatic Arthritis Following Acetabular Fracture: A Systematic Review

Background: Acetabular fractures are frequently associated with post-traumatic arthritis (PTA), for which total hip arthroplasty (THA) has emerged as the established procedure. The purpose of this systematic review is to report the patient outcomes, complications, and implant survival of delayed THA for patients with PTA following acetabular fracture. Methods: A systematic review was performed in December 2021 as per Preferred Reporting Items for Systematic Review and Meta-Analysis Guidelines to identify all studies reporting outcomes of delayed THA performed for PTA with a history of acetabular fracture. From an initial screen of 893 studies, 29 studies which met defined inclusion criteria including minimum 12 months of follow-up and minimum 10 THA were included in the final review. Results: A total of 1220 THA were reported across 29 studies, with 1174 THA completing a minimum of 1-year follow-up at a mean of 86 months. All 29 studies reported upon complications, with a control included in 6 for comparison. Higher complication rates were observed both in patients who had prior open reduction internal fixation and conservative treatment, most notably infection which was observed following 3.6% THA. The total joint revision rate was 9.7%. An improvement was noted in all 25 studies which recorded patient-reported outcomes, with a mean rise in the Harris hip score from 45 to 86 across 18 studies. Conclusions: THA may reduce reported pain levels and improve functional outcomes in selected patients experiencing PTA following acetabular fractures. There is an increased risk of complications, necessitating careful consideration when planning the operation and open discussion with prospective patients and caregivers

High-power Low-frequency Ultrasound: a Review of Tissue Dissection and Ablation in Medicine and Surgery

High-power low-frequency ultrasound in the range 20–60 kHz has wide ranging clinical applications in surgical and medical instruments for biological tissue cutting, ablation or fragmentation, and removal. Despite widespread clinical application and common device operating characteristics, there is an incomplete understanding of the mechanism of tissue failure, removal and damage. The relative contribution of cavitation, direct mechanical impact and thermal effects to each process for specific tissue types remains unclear. Different and distinct mechanisms and rates of tissue removal are observed for interaction with soft and hard tissue types. Device operating parameters known to affect the interaction include frequency, peak–peak tip amplitude, suction and application time. To date, there has been little analysis of the effect of variations in, and interactions of, these parameters on tissue removal and damage for individual biological tissue types. Potential controllable damage mechanisms occurring in tissues include alteration in global biomechanical properties, histomorphological changes, protein denaturation and tissue necrosis. This paper presents a critical review of the literature on the clinical application, mechanism of tissue interaction, removal and residual tissue damage. It describes known mechanisms for distinct tissue types

High Power, Low Frequency Ultrasound: Meniscal Tissue Interaction and Ablation Characteristics

Abstract—This study evaluates high power low frequency ultrasound transmitted via a flat vibrating probe tip as an alternative technology for meniscal debridement in the bovine knee. An experimental force controlled testing rig was constructed using a 20 kHz ultrasonic probe suspended vertically from a load cell. Effect of variation in amplitude of distal tip displacement (242–494 mm peak-peak) settings and force (2.5–4.5 N) on tissue removal rate (TRR) and penetration rate (PR) for 52 bovine meniscus samples was analyzed. Temperature elevation in residual meniscus was measured by embedded thermocouples and histologic analysis. As amplitude or force increases, there is a linear increase in TRR (Mean: 0.9 to 11.2 mg/s) and PR (Mean: 0.08 to 0.73 mm/s). Maximum mean temperatures of 84.6C and 52.3C were recorded in residual tissue at 2 mm and 4 mm from the ultrasound probe-tissue interface. There is an inverse relationship between both amplitude and force, and temperature elevation, with higher settings resulting in less thermal damage.