A Strategy for Repair, Augmentation, and Reconstruction of Knee Extensor Mechanism Disruption: A Retrospective Review

Background: The loss of extensor mechanism continuity that occurs with patellar and quadriceps tendon rupture has devastating consequences on patient function. Purpose: To describe a treatment strategy for extensor mechanism disruption and evaluate the outcomes of 3 techniques: primary repair, repair with semitendinosus tendon autograft augmentation, and reconstruction with Achilles tendon allograft. Study Design: Case series; Level of evidence, 4. Methods: The authors reviewed surgeries for extensor mechanism disruption performed by a single surgeon between 1999 and 2019. Patient characteristics, imaging studies, surgical techniques, and outcomes were recorded. Primary ruptures with robust tissue quality were repaired primarily, and first-time ruptures with significant tendinosis or moderate tissue loss were repaired using quadrupled semitendinosus tendon autograft augmentation. Patients with failed previous extensor mechanism repair or reconstruction and poor tissue quality underwent reconstruction with Achilles tendon allograft. The primary outcome was extensor mechanism integrity at a minimum 1-year follow-up, with extensor mechanism lag defined as >5° loss of terminal, active knee extension. Secondary outcomes included postoperative knee range of motion, International Knee Documentation Committee (IKDC) and Tegner activity scores, and the radiographic Caton-Deschamps Index. Results: Included were 22 patellar tendon and 21 quadriceps tendon surgeries (patients: 82.5% male; mean age, 48.1 years; body mass index, 31). Seventeen (39.5%) cases underwent primary tendon repair, 13 (30.2%) had repair using semitendinosus tendon autograft augmentation, and 13 (30.2%) underwent reconstruction using an Achilles tendon allograft. Seventeen (39.5%) cases had at least 1 prior failed extensor mechanism surgery performed at an outside facility. At the last follow-up, 4 (9.3%) cases had an extensor mechanism lag, no cases required additional extensor mechanism surgery, and all cases were able to achieve >90° of knee flexion. Postoperative IKDC scores were significantly improved with all methods of extensor mechanism surgery, and postoperative Tegner activity scores were significantly improved in patients who underwent primary repair and Achilles tendon allograft reconstruction ( P < .05 for all). Conclusion: Primary repair alone, repair using quadrupled semitendinosus tendon autograft augmentation, and reconstruction using Achilles tendon allograft were all effective methods to restore extensor mechanism and knee function with the proper indications. Persistent knee extensor lag was more common in chronic extensor mechanism injuries after failed surgery, although patients still reported significantly improved postoperative functional outcomes.

Achilles Tendon Allograft with Semitendinosus Autograft Reinforcement Is a Successful Treatment for Chronic Patellar Tendon Rupture: Report of Two Cases

Rupture of the patellar tendon must be diagnosed urgently because reconstruction of the extensor mechanism produces better results when it is performed in acute conditions. Reconstruction of chronic extensor mechanism rupture on the contrary is very challenging. Several surgical techniques have been described using a variety of graft choices and fixation methods, but the optimal approach is still under debate. We report our experience of two cases of chronic patellar tendon rupture reconstruction using an Achilles tendon allograft reinforced by a vascularized ipsilateral semitendinosus tendon frame. The rapid functional recovery of the range of motion, only three months postoperatively, showed us that this reconstruction technique was effective.

Patellar Tendon Allograft Reconstruction

Background: Chronic patellar tendon injuries can cause significant functional deficits due to anterior knee pain, extension weakness, and extensor lag. With chronic injuries, the tissue is inadequate and of poor quality. Chronic injuries require autograft or allograft for augmentation or reconstruction. We present reconstruction of a chronic patellar tendon injury with Achilles tendon allograft. Indications: Chronic patellar tendon injuries causing functional deficits, including knee extension weakness, extensor lag, and anterior knee pain. Technique Description: A longitudinal incision is made over the patellar tendon, and the patellar tendon is excised. Two guide pins are drilled in a retrograde fashion through the patella and are overdrilled with a reamer. A trough is made at the tibial tubercle using an oscillating saw. The Achilles allograft calcaneal bone block is contoured to the appropriate size, and then press fit into the trough. Two 4.0-mm fully threaded cannulated screws with washers are used to secure the bone block. The fresh frozen Achilles allograft is doubled over, and a double Krackow running locking suture is placed. A V-Y advancement of the quadriceps tendon is performed to ensure adequate advancement of the patella. The limbs of the Krackow suture are pulled through the patella drill holes and tied with knee in full extension. Results: At 1 year, patients can expect near full range of motion with minimal extensor lag. Reconstruction results in improved pain and function as compared with preoperatively, as well as return to activities. Conclusion: Achilles tendon allograft is a good option for reconstructing chronic patellar tendon injuries. Advantages of the Achilles allograft include the bone-to-bone healing at the tibia, lack of donor site morbidity, and the large amount of tissue available for reconstruction.