Lay the patient supine with the knee flexed 20–30°. Place the probe longitudinally on the midline superior pole of the patella. From deep to superficial, visualize the femur, prefemoral fat pad, hypoechoic suprapatellar joint space, suprapatellar fat pad, and quadriceps tendon inserting onto the patella. Rotate the probe 90° to the axial (transverse) plane. From deep to superficial, view the femur, prefemoral fat pad, hypoechoic suprapatellar and parapatellar joint spaces, suprapatellar fat pad, and quadriceps tendon. Glide medial and lateral here to assess for fluid in the medial and lateral parapatellar recesses. Milking or compressing those areas may help delineate the joint space (Fig. 6.1).

Patient positioning: Lay the patient supine, knee flexed 20–30°. Place a towel or pillow underneath the knee.

Probe positioning: Place the probe axial (transverse) over the distal thigh, superior to the patella (Fig. 6.2a). Suprapatellar joint fluid may be visualized directly under the quadriceps tendon or deep to the suprapatellar fat pad.

Markings: Identify the quadriceps tendon and muscles, periosteum, and fat pads to avoid these structures when injecting.

Needle position: Insert the needle in-plane from lateral to medial in the superolateral region of the knee.

Safety considerations: Identify and avoid any obvious vessels.

Pearls:

Equipment needed:

Patellar tendinosis or “jumper’s knee” is a common source of focal anterior knee pain for active, high-impact activity individuals [3]. Treating chronic patellar tendinosis is challenging given the low capacity for tendons to heal [4]. It is not clear why tendinosis develops. Histologically, there is evidence of tissue degeneration with failed reparative response and absence of inflammatory cells. Research on patellar tendinopathy does not support any one treatment as the most effective. Patellar tendon needling has been described using no injectate (needle alone), with sclerosing agents, autologous blood or platelet-rich plasma (PRP), and corticosteroids [10–13].

Pes anserine bursitis is a common source of medial-sided knee pain, frequently associated with worsening knee OA, overuse, or repetitive trauma [17]. It typically presents with pain with walking and climbing or descending stairs [18]. Patients typically have tenderness to palpation over the conjoined tendon insertion of the sartorius, gracilis, and semitendinosus. Treatment typically consists of rest, nonsteroidal anti-inflammatory medications, physical therapy, and corticosteroid injections. The literature describes varying benefit from injections; however, prior injections were performed with an anatomical (blind) method. Finnoff et al. injected the pes anserine bursae under ultrasound guidance with an accuracy of 100 % compared to 50 % unguided [19]. It is not clear how well this translates to clinical improvement, however (Table 6.4).

The proximal tibiofibular joint (PTFJ) is an arthrodial sliding joint with great morphological variability. The PTFJ has been categorized into two main types by anatomic orientation: horizontal, with increased joint surface area and rotary mobility, and oblique, with less joint surface area and mobility. The joint supports 1/6 of the axial load of the leg. It is often overlooked as a potential cause of lateral knee pain, frequently mistaken for a lateral collateral ligament injury [20, 21]. Symptoms are nonspecific; patients may complain of joint instability or anterolateral knee and lateral calf pain that can be referred proximally or distally. Exacerbating factors may include stair climbing, hamstring pain or tightness, and knee and ankle movements [22]. Physical examination including manual pressure or grading laxity of the PTFJ did not correlate with the degree of arthritis seen in one study [23, 24].Therefore, an injection may provide both diagnostic and therapeutic benefits (Table 6.5).