Anterior cruciate ligament (ACL) reconstruction with bone-patella tendon-bone autograft is a common procedure seen in the operating room of a sports surgeon. While this procedure is highly successful, there are many complications that may arise at each stage of the reconstruction. The following chapter presents a review to improve recognition of the differences and alterations in patient anatomy that can prepare and allow the surgeon to avoid potential intraoperative complications with graft harvest and graft fixation. This chapter also discusses donor site morbidity and potential complications that are associated with bone-patella tendon-bone graft harvest.
KeywordsACL, Bone-patella tendon-bone, graft harvest, patella alta, patella baja
KeywordsACL, Bone-patella tendon-bone, graft harvest, patella alta, patella baja
Anterior cruciate ligament (ACL) injuries are common in the active population and ACL reconstruction is one of the most commonly performed orthopaedic procedures today, with more than 200,000 cases in the United States annually. With a high success rate and excellent biomechanical properties, patellar tendon autograft harvested from the central third of the patellar tendon is a popular graft choice for ACL reconstruction, particularly in young and active patients. Despite high success rates, complications can arise and have been reported to occur in 1%–5% of ACL reconstructions using bone–patella tendon–bone (BPTB) grafts. In the majority of these cases, technical error during the procedure is the cause, and error most often involves graft harvest and preparation. Additionally, some patients report both short- and long-term morbidity related to the BPTB graft harvest site. It is important to recognize and prepare for issues that can affect the length and quality of the graft, such as patella alta, patella baja, Osgood-Schlatter disease, Larsen-Johansson disease, chronic patella tendonitis, and presence of open physis, all of which increase the risk of intraoperative complications. Other complications can arise intraoperatively during graft harvest and include patella fracture, harvesting undersized bone blocks or an undersized tendon, excessive damage to the donor site, and loss of sterility. While prevention of these technical errors is the goal of every surgeon, options must be available to manage these problems when they arise. The goal of this chapter is to identify the complications that can arise with the harvest and use of BPTB autograft for ACL reconstruction and to propose methods to avoid and manage these complications.
Complications During Bone–Patella Tendon–Bone Graft Harvest
The two most common pitfalls leading to complications in the use of BPTB autograft for ACL reconstruction are (1) the failure to recognize, in the preoperative planning phase, scenarios that can have negative effects on the length and quality of the graft and (2) being ill-prepared for these scenarios when they arise.
The presence of patella alta results in a longer graft that can lead to graft-tunnel mismatch, and the presence of patella baja results in a shorter graft that can lead to inadequate intra-articular length. These conditions can be observed and quantified on a preoperative lateral x-ray of the knee. The Insall-Salvati and Blackburne-Peel methods can be used to diagnose these conditions and prepare the surgeon for potential issues with graft length. With patella alta, the harvested graft can be too long and present problems with graft-tunnel mismatch, fixation, and graft tension ( Fig. 26.1 ).
In this situation, the tibial fixation is compromised by either too little bone plug in the tibial tunnel, or none at all. If the surgeon is aware of this condition preoperatively, another graft source can be considered. If encountered intraoperatively, the presence of too long of a graft can be addressed in several ways. First, the femoral tunnel may be lengthened and the graft advanced and fixed deeper within the femoral tunnel. Tunnel length and graft advancement are limited by the lateral cortex. The femoral bone plug may be folded onto itself to shorten the graft, but this method requires trimming down the bone plug or using a larger tunnel. If necessary, a two-incision outside-in technique can be used. On the tibial side, a longer tibial tunnel can be created by increasing the angle of the tibial drill guide and starting more distally on the tibia to accommodate a longer graft. The tibial bone plug can be excised completely and soft-tissue fixation performed with a spiked washer, soft-tissue screw, and/or sutures tied over a post. Another option is to secure the femoral plug and rotate the tibial plug within the tibial tunnel, effectively shortening the graft. Biomechanical studies have illustrated similar failure loads of grafts for in vitro study, with up to 540 degrees of rotation of the graft.
With patella baja, the tendinous portion of the graft may be too short, and the surgeon may consider other graft sources. The average ACL length is approximately 38 mm, and this represents the minimum intra-articular graft length needed for reconstruction. The length of the patellar tendon should be measured on preoperative lateral x-ray to determine if there will be sufficient length to the tendinous portion of the harvested graft.
The surgeon should check for the presence of Osgood-Schlatter disease ( Fig. 26.2 ) or Larsen-Johansson ( Fig. 26.3 ) disease, where bony projections and intratendinous ossicles are present and can result in an inadequate patellar tendon graft. A false tendon insertion to bone can be débrided during graft preparation, but one must be aware of this possibility so that an adequate bone block remains during harvest and after débridement ( Fig. 26.4 ).
Additionally, the chronic condition of patellar tendinopathy can lead to diseased tissue at the tendon-bone junction ( Fig. 26.5 ). This can compromise the quality and strength of the graft. In this situation, the graft can be débrided until healthy tissue is encountered.
In skeletally immature patients, a bone block harvested from the tibial tubercle can contain a portion of cartilaginous tissue from the open physis of the proximal tibia. This is addressed using a combination of tendon-securing Krakow sutures in the tendon and cartilage portions of the graft and sutures through drill holes in the tibial tubercle portion of the graft.
With its ease of exposure and simple approach, harvesting patellar tendon autograft is usually a straightforward part of the procedure. Poor surgical technique can lead to intraoperative complications, and a meticulous attention to detail is required to avoid these complications. Potential intraoperative complications during BPTB graft harvest include patellar fracture, undersized bone block harvest, undersized tendon harvest, and loss of sterility.
Fracture of the patella is a rare complication during patellar tendon harvest for ACL reconstruction. Risk factors associated with patellar fracture include a hypoplastic patella, large bone plug harvest, excessive levering with an osteotome, and overly long or deep cuts into the patella that may act as stress risers. Careful and meticulous surgical technique can help prevent this complication. A skin incision allowing adequate exposure and visualization of the entire patellar tendon is important. The oscillating saw is used to create parallel and slightly beveled vertical cuts in the patella, creating a bone block that is 8–10 mm deep, around 20 mm long, and 9–10 mm wide. The depth of the vertical parallel cuts can be controlled by keeping 2–3 mm (one to two teeth) of a 10-mm-wide saw blade visible at all times while making the cuts ( Fig. 26.6 ). Care is taken not to overly bevel these cuts and create a triangular rather than the desired trapezoidal bone plug. While making the proximal transverse cut, a “double cut” technique removes a thin wafer of bone and creates room for placement of an osteotome. The osteotome is then used to gently free the bone block from the harvest site, alternating from side to side, focusing on freeing the corners, and working the osteotome in line with the saw cut rather than a levering motion. If patella fracture occurs intraoperatively, it should be repaired with immediate internal fixation using standard fracture fixation techniques.