There are three aspects of the treatment procedure that need special attention. The first is tenderness point localization. The surface of the total knee joint should be pressed to mark the location of the patient's pain response through the patient's complaint and the doctor's palpation. Peroneal collateral ligament and iliotibial band point, patellar lateral retinaculum point, quadriceps tendon and suprapatellar bursa point, patellar medial retinaculum point, tibial collateral ligament point, pes anserinus bursa point are frequent sites of pain and can be focused on.
The second is ultrasound localization. When observing the knee using musculoskeletal ultrasound, the fixation point is mainly observed by the following methods. Scanning was performed along the short axis and the long axis of the quadriceps tendon with an 8-15 MHz linear array probe, and the scanning depth was 1-4 cm. The common pathological manifestations of fixation sites were tendon thickening, hypoechoic, and loss of layered structure. Scanning was performed along the long axis of the medial and lateral collateral ligaments using an 8-12 MHz high-frequency linear array probe with a scanning depth of less than 3 cm. The common pathological manifestations of the fixation site were ligament thickening, local hypoechoic changes, irregular cortical bone of the lateral femoral condyle, and/or expansion of the bursal sac, low to anechoic effusion in the bursal sac, and septation in the bursal sac. A 10-12 MHz linear array probe was used to scan the sagittal section at a depth of 2-3 cm along the long axis section of the patellar tendon, and the sonographic findings were verified on the short axis section. The fixation point showed local thickening and hypoechoic, which was best located in the deep proximal part of the patellar tendon.
Finally, there is the method of interventional needle entry. When the ultrasound probe was positioned along the pathological images, the syringe needle and knife were inserted from the probe edge, and the needle direction was parallel to the direction of muscle and ligament fibers to avoid cutting muscle and ligament fibers. In the ultrasound field, it was determined that the needle entered the target position, avoiding contact with blood vessels and nerves.
During the course of treatment, the operator can improve the method or troubleshoot problems in the following ways. If the patient's tender point cannot be found, it can be replaced by the point where the patient complains of soreness and distention. Clinically, there may also be a large area of pain in the whole knee, but at this time, the pain is preferred to the more serious position, in principle, with no more than 15 treatment points. If the ultrasound image is blurred, it can be checked whether the ultrasound frequency selection is appropriate, or the depth of the observation position can be adjusted by changing the intensity of the probe pressing the skin.
The pathogenesis of KOA involves several factors and complex mechanisms that still need to be fully elucidated. The knee joint is composed of the inferior end of the femur, the superior end of the tibia, and the patella and is the most complex trochlear joint in the human body. Under the action of the muscles and ligaments, the knee joint maintains a normal alignment and balance of the lower limb force line. However, when pathological factors affect the knee joint, the knee muscles and ligaments are partially contracted, and local stress on the articular cartilage increases, which leads to poor joint alignment. In severe cases, the lower limb force line is unbalanced, and the string around the knee joint is stressed abnormally. It often leads to stress changes at the bowstring junction, that is, adhesion and contracture of the soft tissues around the knee, and further development will lead to bone hyperplasia, that is, the occurrence of KOA23,24,25,26.
The therapeutic mechanism of acupotomy27 involves the regulation of the dynamic balance of the soft tissues by releasing adhesions. This can increase the local pain threshold in patients with myofascitis. Entrapment of the cutaneous nerve can be relieved by reducing the tension and decompressing the soft tissue at the point of tenderness. Clinical studies have concluded that the treatment of KOA with acupotomy, alone or in combination with other treatments, can significantly reduce intra-articular inflammation, improve bone metabolism, promote joint repair, improve knee joint function, and enhance patients' quality of life28. Animal experimental studies have shown that acupotomy can not only effectively improve the degree of fatigue of the anterior tibial muscle of rabbits with KOA and adjust the physiological and mechanical behavior of the tendons of the anterior tibial muscle29 but also greatly improve the strength of the collateral ligament of the knee of animals with KOA and improve the mechanical properties of the soft tissues around the knee. Thus, the mechanical balance of the knee joint can be restored to achieve a therapeutic effect in KOA.
Currently, most clinical uses of autonomy still adopt the blind acupuncture method, that is, without the aid of imaging, only by the experience of the surgeon and the patient's feedback during the operation. Needle-knife treatment without ultrasound increases the requirement for surgeons to have technical experience and also increases the surgical risk and pain to patients, which is not conducive to the promotion of needle-knife treatment of KOA. Therefore, visualization during acupotomy with modern imaging techniques has become a trend in promoting acupotomy use.
Musculoskeletal ultrasound, which refers to the ultrasonic diagnosis and evaluation technique applied to the musculoskeletal system, was used in this study. It plays an important role in the monitoring and diagnosis of soft tissue injury and soft tissue lesions30. Musculoskeletal ultrasound can accurately display the anatomical position, adjacency, shape, and size of muscles, tendons, and ligaments and can also dynamically help observe the movement of muscles and tendons in real time, accurately guiding the location of needle-knife operations and accurately evaluate the site after a procedure31.
In this study, VAS, HSS, WOMAC, synovial thickness of suprapatellar bursae, and adverse reactions were used to evaluate the efficacy and safety of ultrasound-guided autonomy for KOA. VAS evaluated the severity of pain by visual simulation. HSS evaluated knee joint function in five aspects: pain, function, range of motion, muscle strength, flexion deformity, and stability. WOMAC evaluated the structure and function of the knee joint in terms of pain, stiffness, and physical function. Musculoskeletal ultrasound can measure the synovial thickness of suprapatellar bursae. Adverse effects include fainting, nausea, vomiting, infection, swelling and pain around the pinhole, and an increase in pain during treatment.
The results indicate that the synovial thickness of the suprapatellar bursae in the treatment group was significantly lower (p < 0.05), HSS was significantly higher (p < 0.05), and WOMAC osteoarthritis index score was significantly lower than that in the control group (p < 0.05). Although there was 1 case of adverse reaction, the symptoms were mild and did not affect treatment and follow-up.
It is necessary to acknowledge the limitations of this study. Although many studies31,32,33 have proposed using the synovial thickness of suprapatellar bursae as diagnostic and evaluation criteria for KOA, there is still no consensus or guidelines. As a self-controlled study, this study lacks efficacy in comparison with other treatment methods, and the follow-up time and sample size need to be increased, which may have affected the generalizability and accuracy. In the future, more randomized, controlled, double-blind trials are needed to demonstrate the advantage of ultrasound-guided acupotomy for KOA.
In summary, ultrasound-guided acupotomy can display the location of the acupotomy and the anatomical structure of the lesion in real-time to achieve accurate release of adhesions and reduce operational injuries. This study showed that ultrasound-guided acupotomy had a curative effect on KOA, which significantly reduced synovial thickness, relieved pain, and improved knee joint function. At the same time, ultrasound-guided acupotomy has the advantages of low side effects and high safety, which is worthy of popularization and application.