Incomplete ruptures of the patellar tendon with intact function of the extensor apparatus may be treated nonoperatively. The period of immobilization in full extension has to be 2–3 weeks, followed by progressive range of motion with active flexion and extension for 4 weeks; strengthening has to be started after 6 weeks [11]. If the incomplete lesion is associated to functional deficits, or in cases of complete patellar tendon rupture, the surgical treatment is indicated regardless of age and physical activity. It should be performed as soon as possible: acute repair has the best chance to achieve a tension-free tendon apposition [7]. When treating acute patellar tendon injuries, isolated suture repair is generally not recommended because of the high rate of re-rupture. Most of lesions occur closed to the osteotendinous junctionalong the inferior pole of the patella: this localization facilitates transosseous sutures [25–27]. The surgical approach normally suggested for a patellar tendon repair is the anterior one with a midline incision. After a careful dissection, the peritenon is longitudinally split, the retinacular tears are dissected out, and the tendon ends are debrided. Then, the inferior pole of the patella, the most common site of injury, is decorticated with a curette or a burr to improve bleeding. This is made in order to improve the healing process. A pair of continuous, locking heavy (No. 2 or 5) nonabsorbable sutures is then placed in the tendon using a Krackow or similar suture technique. Three parallel bone tunnels are drilled with a 2.5 mm drill from distal to proximal in the patella; a suture passer is used to pass the free suture ends in the bone tunnels, with the central one containing two sutures.

Some authors proposed to create the tunnels using an ACL tibial guide [28]. The suture ends are temporarily fixed to check patellar tracking and to avoid a patella infera. Once the correct position and tracking of the patella have been checked, the strands are tensioned with the knee fully extended to approximate the tendon to the inferior pole of the patella. The retinacula are now closed with an absorbable suture, and the knee is flexed at 90° to test the repair [11]. As well as for quadriceps tendon ruptures, suture anchors can be used for patellar tendon acute repair [29]. Some authors described a technique using three suture anchors incorporated into a six-stranded Krackow technique. Some authors concluded that this technique could result into a low-profile construct, with better recreation of the tendon’s insertion into the inferior pole of the patella. This minimizes the possibilities of loosening through bone tunnels and abnormal stress forces [30]. Other authors demonstrated that with suture anchors, compared to trans-patellar sutures, there were less gap formations after cyclic loading [31, 32]. If the rupture occurs in the mid-substance of the tendon and there is enough proximal and distal substance, it can be repaired with continuous locking stitches; a Krackow or similar repair can be used [33]. In these cases, bone tunnels can be used in the patella to hold the proximal fragment [9]. Alternatively, a neutralization nonabsorbable wire or heavy sutures can be placed transversely through the patella and through another bone tunnel in the proximal tibia; this technique have been used to provide additional stability to the primary repair [33, 34]. When the primary repair is tenuous, it can be augmented using different surgical techniques. McLaughlin et al. described a technique of primary repair augmented with a tension wire anchored to the patella [35]. Kasten et al. describe their results comparing an augmentation with a metal wire or a strenuous PDS one, reporting no differences in terms of clinical results [36]. Other authors described an augmentation using semitendinosus autograft, nonabsorbable vascular graft, or nonabsorbable tape [37–40]. The augmentation using semitendinosus or gracilis autograft is one of the most commonly described in literature. The tendon is isolated and stripped, maintaining its tibial insertion. A tibial tunnel is normally drilled from medial to lateral to the anterior tibial tuberosity, and the tendon is passed through it. A second tunnel is then drilled in the patella, and the tendon is passed through it from lateral to medial. At this point, the end of the tendon is sutured back to its tibial insertion with nonabsorbable stitches [41]. Figure 12.2 shows some steps of this technique. However, the need for an augmentation in primary patellar tendon repair is still debated in literature. Some authors demonstrated better biomechanical resistance in augmented repair; other clinical studies showed similar results in patients with or without augmentation during the primary repair [42–44].

In the chronic setting, primary repair is difficult because of tendon retraction, tendon quality, and adhesion formation [11]. Some authors described a primary repair with fascia lata or hamstrings augmentation; sometimes, reconstruction is the only surgical option [45, 46]. In chronic patellar tendon rupture or re-rupture, the hamstrings can be used with techniques similar to the one described for augmentation. The tendons are normally left inserted, the tibial tunnel is then drilled, and the tendons are passed all around the patella in a circular or figure-of-eight fashion and then sutured back to their insertion [47–50]. Some authors also described a percutaneous technique with good clinical results, but in a small case series [51]. Other authors described a technique using hamstrings passed through a longitudinal bone tunnel and then fixed to the superior pole of the patella with an Endobutton® (Smith & Nephew) [52]. However, in cases of chronic rupture, the augmentation is always suggested, even in cases in which a primary repair is possible.

Some authors suggest the use of the contralateral central third of the patellar tendon with proximal and distal bone plugs for the reconstruction of chronic patellar tendon rupture [7, 53]. Wiegand et al. proposed their technique using a Y-shaped flap folded back from the vastus lateralis fascia with good clinical and functional results [54]. Recently, different surgical techniques have been proposed using allograft tissue in patellar tendon reconstruction. Probably, the most commonly used allograft is the Achilles tendon [55]. The bone plugs of the allograft are normally fixed to the tibial tubercle after a squared trench is performed. The tendon is split into three parts: the central one is passed through a longitudinal patellar tunnel and sutured to the superior pole of the patella, and the other two parts are sutured to the lateral and medial retinaculum with nonabsorbable stitches.

In chronic settings, also synthetic grafts have been used. Naim et al. in a case report described a surgical technique using LARS ligament for the reconstruction of a patellar chronic tendon rupture in a low-demand patient [56]. However, because of the low biological profile of synthetic grafts, they are normally indicated in low-demanding patients.