Direct repair has a very limited indication. In acute settings, direct repair is still possible; however, in chronic injury where the tendon is retracted or when the soft tissue is not sufficient to perform a good repair, direct repair with augmentation may be a better option [11].

The tendon may be repaired or reattached to the bone with nonabsorbable suture, anchor, or staple. Caution needs to be implemented to position the patella in its normal height. After direct repair, the suture will be protected with cerclage wire that spans from the patella to tibia (transosseous anchor) [11, 20]. Patients’ knees are placed in extension with locked brace for 6 weeks postoperative. Afterward, initiate gradual increase in knee flexion while still maintaining mobilization in extension for another 6 weeks.

Studies have shown that direct repair outcomes were less than satisfactory with high failure rate [4, 11]. Therefore, unless the intraoperative result was very convincing, soft tissue augmentation should be considered.

Surrounding soft tissues that are commonly used to augment the extensor repair are semitendinosus, gracilis and a turned down quadriceps tendon. Several papers have described techniques of augmentation in details (Fig. 20.2) [21–23]. Cadambi and Engh [21] harvested the semitendinosus tendon from the ipsilateral leg using tendon stripper and sparing the distal insertion. Then, a 6-mm tunnel was created on the distal third of the patella bone. The semitendinosus tendon was passed from the medial to lateral through the tunnel and sutured to itself. If the patella bone was too thin or too fragile and not possible for creation of a tunnel, then the semitendinosus tendon would be passed through the quadriceps tendon on top of the patella bone. However, quadriceps turndown would be performed to maintain patellar tilt in this technique. In this case, series with follow-up range from 12 to 48 months; all patients had extension lag less than 20°.

Another variation described by Jarvela [22] was to secure the semitendinosus tendon to the tibia on the lateral side. In a short semitendinosus tendon, gracilis or quadriceps tendon might be added to complete the procedure. Utilization of quadriceps tendon was to detach the middle third of the tendon from muscle junction and turn it down to be secured either at the distal end of the patellar tendon or drilled into tibial tuberosity. A case report by Lin et al. described a patient who underwent a quadriceps tendon augmentation showed good result with no extension lag [24].

Another hamstring tendon augmentation used similar technique, except the graft was crossed in the middle to create a figure-of-eight form. Result after average follow-up of 5 years showed no extension lag nor revision [23].

A biomechanical study [25] showed that augmentation of patellar tendon repair with either cable wire or polydioxanone (PDS™, Ethicon, Somerville, NJ, USA) cord provided higher stability than suture anchor alone. It had higher load to failure and less elongation.

In patients with poor soft tissue conditions, augmentation with synthetic material must be included as one of the treatment options. As in any other ligament/tendon reconstruction, use of synthetic material has the advantages of no donor site morbidity, no additional surgery time for harvesting the donor, free from possible transmitted infection, and no regulatory restriction. However, the disadvantages are the material not being readily available in all countries and prone to infection [26–28].

Leeds-Keio is a scaffold-type artificial ligament. It is expected to work as a ligament until biological tissue is induced around the implant and then subsequently becomes ligamentous tissue and assumes the role of the original artificial ligament [29]. It has been used for different knee ligament reconstructions. Fujikawa and Ohtani, in a retrospective review of Leeds-Keio usage in extensor mechanism injury, found that 19 knees of 18 patients had almost full knee flexion (range of full flexion 140°–160°) with extension lag less than 10° for years after the procedures [30]. No revision was performed.

The procedure was to create a figure-of-eight artificial ligament with distal attachment passing through tibial tunnel posterior to the tibial tuberosity and secured with double staples on the lateral tibial condyle for patellar tendon rupture, or proximal end was sutured to each other and to quadriceps tendon for quadriceps rupture (Fig. 20.3). No drilling was performed on the patella bone, only crossing on top of the patella to prevent fracture of the patella. The artificial graft was passed above (for patellar tendon rupture) or below (for quadriceps tendon rupture) the patella bone [30].

Another synthetic ligament that has been used for extensor mechanism injury is LARS (Ligament Augmentation and Reconstruction System, Orthomedic, Quebec, Canada). This system has been used in other ligament injury, for example, cruciate or collateral ligaments. LARS has advantages as follows: [1] avoidance of donor site morbidity, [2] allowance of early mobilization and quicker rehabilitation due to its mechanical properties, [3] no evidence of tissue intolerance to the artificial material, [4] allowance of fibroblast ingrowth around the artificial ligament bundles, and [5] the possibility of repeating the reconstruction in case of failure [32]. One paper by Naim et al. [33] reported the results of LARS extensor reconstruction in elderly patient, but postoperative range of motion was not stated, and the follow-up time was short (1 year). Another paper by Talia and Tran [34] reported the result of reconstruction on a 26-year-old high-functioning ex-Olympic gymnast who suffered from bilateral patellar tendon rupture and was treated with LARS in figure-of-eight configuration. After 4 years of follow-up, the range of motion was 0–130°, and there was no extension lag. Early rehabilitation started on day 1 for this patient. Although the results were promising, none of these patients were post-arthroplasty patients. Therefore, further studies with large population and longer follow-up are needed.

A technique gaining popularity in the United States and Europe is one standardized by Browne and Hanssen [31] using polypropylene mesh (Marlex mesh, C.R. Bard, Murray Hill, New Jersey) (Fig. 20.4a–c). The mesh is a knitted monofilament polypropylene heavyweight mesh commonly used for hernia and urological procedure. The mesh is folded into several layers measuring 2–2.5 cm wide, and then it is stitched in place with nonabsorbable suture.

The distal graft is secured into tibial intramedullary slightly medial to the longitudinal axis of the anterior tibial crest. It is incorporated with cement if revision was performed on the tibial stem or fixated with screw and washer. Then, a layer of fibrous tissue is inserted between the graft and the tibial plateau to prevent abrasion of the graft. The graft is passed through the lateral retinaculum and attached to the quadriceps tendon and lateral vastus. Medial vastus is immobilized and positioned on top of the graft. Thus, the graft is located anteriorly from the lateral vastus and posteriorly from medial vastus. The result showed mean postoperative extensor lag of 2.8°, excluding three failure cases [31]. This technique is widely used in the world due to easy access and reasonably priced compared to allograft.