The following imaging investigations should be performed in patients with suspected lesion of the PT: X-ray, ultrasound and MRI.

Radiographs must be performed in both the anteroposterior and lateral views. It is important to pay attention to the evaluation of the location of the patella. In case of PT rupture, the patella is dislocated proximally respect to the knee joint line (Fig. 27.2).

In case of dubious images, or especially in patients with “patella alta”, it can be useful to perform the X-ray of the contralateral knee. Moreover, radiographs show any avulsion fractures of both patella and anterior tuberosity of the tibia (Fig. 27.3).

With ultrasound it is possible to appreciate the extension, shape and location of the PT rupture (Phillips and Costantino 2014). Furthermore, ultrasound allows the visualization of the haemorrhagic spreading into the surrounding soft tissues. However, there is no agreement on the use of ultrasound in case of partial and chronic tears of the PT, as well as in obese patients (Swamy et al. 2012).

The MRI is the most sensible imaging investigation for the diagnosis of PT rupture: the tendon is represented by a low-intensity homogeneous signal, and in case of rupture, the signal becomes inhomogeneous with interruptions of the tendon structure or within the osteotendinous junction (Fig. 27.4).

The MRI should be performed in case of dubious ultrasound imaging or to diagnose intra-articular and extra-articular associated lesions.

The PT ruptures can be classified into acute and chronic.

With acute lesion we mean a lesion usually treated within 2 weeks of injury (Siwek and Rao 1981).

Chronic lesions are seen by the surgeon some weeks after the injury, especially in patients who present associated osseous and ligamentous lesions of the knee. Patients with initial diagnosis of partial tears of the PT turned into total lesion or with early failure of surgery or with septic complications are assigned to this category. Some cases of incomplete rupture of the PT, which are not associated with functional impairment, could be managed conservatively, using knee brace locked in extension for 4–6 week, followed by progressive physiotherapy based on gradual knee flexion (Rauh and Parker 2009).

Surgical management in acute PT rupture is indicated in complete lesions of the PT or in patients with partial lesions associated with functional impairment (loss of active knee extension). Surgical repair in the acute setting significantly influences tendon healing (Lee et al. 2013).

The first step in surgical treatment of acute lesions of the proximal or distal portion of the PT is to reinsert the tendon to the bone; the reinsertion can be done with transosseous sutures or through the execution of transosseous tunnels like modified Krakow technique (Fig. 27.5) or with suture anchors (Capiola and Re 2007).

The goal of surgery is to restore the osteotendinous continuity and replace the patella at the original position.

Several authors proposed the use of reinforcement with autologous or homologous grafts (Larson and Simonian 1995) or synthetic materials (Kasten et al. 2001).

In case of acute lesions of the middle part of the PT, the first step consists in an end-to-end suture of the tendon to restore the tendon continuity.