The potential of ultrafast lasers (pico- to femtosecond) in orthopedics-related procedures has been studied extensively for clinical adoption. As compared to conventional laser systems with continuous wave or longer wave pulse, ultrafast lasers provide advantages such as higher precision and minimal collateral thermal damages. Translation to surgical applications in the clinic has been restrained by limitations of material removal rate and pulse average power, whereas the use in surface texturing of implants has become more refined to greatly improve bioactivation and osteointegration within bone matrices. With recent advances, we review the advantages and limitations of ultrafast lasers, specifically in orthopedic bone ablation as well as bone implant laser texturing, and consider the difficulties encountered within orthopedic surgical applications where ultrafast lasers could provide a benefit. We conclude by proposing our perspectives on applications where ultrafast lasers could be of advantage, specifically due to the non-thermal nature of ablation and control of cutting.

We describe the rationale, design, fabrication and performance of a clinical transrectal diffuse optical tomography (TRDOT) system for in vivo monitoring of photothermal therapy (PTT) of localized prostate cancer. The system comprises a 32-channel fiberoptic-based, MRI-compatible transrectal probe connected to a computer-controlled instrument that includes laser diode sources, an optical fiber switch and photomultiplier tube detectors. Performance tests were performed in tissue-simulating phantoms and in ex vivo muscle tissue during PTT treatment. The safety and technical feasibility of in vivo transrectal use were tested in a canine prostate model and in a first-in-human study in a patient before PTT treatment. Limitations of the system are discussed, as well as further developments to translate it into planned clinical trials for monitoring the photocoagulation boundary in the prostate during PTT.

In most developed countries, orthopedic surgery represents one of the most common surgical procedures.¹ The number of patients and procedures will only increase with aging populations. Many surgical procedures have been developed successfully to treat common degenerative conditions, including total knee or hip replacement and spinal fusion, which are the most common hospital discharge procedures in the United States with about 1.5 million cases per year. Other procedures, such as partial and total shoulder replacement, partial hip replacement, kyphoplasty/vertebroplasty, and lumbar decompression, are also regularly performed by orthopedic surgeons as well as other specialists (neurosurgeons and interventional radiologists). Minimally invasive surgery (MIS) and percutaneous techniques have gradually been introduced to reduce complications and improve recovery times:^{2 – 4} examples in spinal surgery include pedicle screw placement, spinal fusion, vertebroplasty/kyphoplasty, and decompression. There has been more recent adoption in total hip arthroplasty, with renewed interest in anterior hip approaches.^{5 – 7} Other hip arthroplasty techniques have included bone resurfacing, which has been controversial with several large registries highlighting concerns over premature wear and metallosis.^8,9

Surgical procedures involving osteotomies pose risks of breaching into critical neurovascular and musculoskeletal structures, often leading to operative morbidity or potential mortality. One related clinical situation involves total hip and knee arthroplasty (THA/TKA) where periprosthetic fracture is considered a major complication that requires revision. Studies found that 40% and 54% of primary THA and TKA patients, respectively, encountered at least one major complication, such as fracture or one minor complication, such as neurovasculature damage, or both.^1,2 Furthermore, with population ageing leading to rapidly growing incidence of primary arthroplasty, the number of revision surgeries will continue to increase substantially due to limited implant survivorship. The advanced surgical complexity and higher rates of associated complications have become a prevalent concern that remains to be improved. Within orthopedics, incidence projections of revision THA/TKA (rTHA/rTKA) to 2030 in the United States alone have indicated an increase of 43% to 70% and 78% to 182%, respectively, relative to the 50,000 rTHA and 72,000 rTKA cases in 2014. In particular, the patient group aged $>55$ years is anticipated to undergo the highest increase, suggesting that multiple revision surgeries would become necessary in the coming decades. Some common causes for rTHA include instability (28%), aseptic loosening (24%), periprosthetic fracture (18%), and prosthetic joint infection (18%).³

Screening programs for prostate cancer (PCa) have increased the detection rate of low- and intermediate-risk disease confined to the prostate (focal tumors), for which treatment options range from active surveillance, with risk of disease progression, to radical therapies (prostatectomy and radiotherapy) that carry significant rates of urinary incontinence and erectile dysfunction.^1,2 Focal ablative therapies, in which treatment is targeted to the dominant (index) lesion rather than the whole gland, aim to minimize morbidity while achieving successful cancer control and preserving the possibility of retreatment. Several focal modalities, including high-intensity focused ultrasound, cryotherapy, irreversible electroporation, and photodynamic therapy, have shown promising results with short- to medium-term follow up.^{3 – 8}