Patellar Autograft Disadvantages Harvest Site Morbidity

The main disadvantage of the patellar tendon graft is the harvest site morbidity. The problems produced by the harvest are patellar ten-donitis, quadriceps weakness, persistent tendon defect, patellar fracture, patellar tendon rupture, patellofemoral pain syndrome, patellar entrap ment, and arthrofibrosis. The common long-term problem is kneeling pain.

Kneeling Pain

The most common complaint after patellar tendon harvest is kneeling pain. This can be reduced by harvesting through two transverse incisions. This reduces the injury to the infrapatellar branch of the saphe-nous nerve.

Patellar Tendonitis

Pain at the harvest site will interfere with the rehabilitation program. The strength program may have to be delayed until this settles. The problem is usually resolved in the first year, but it can prevent some high performance athletes from resuming their sport in that first year.

Quadriceps Weakness

The quads weakness may be the result of pain and the inability to participate in a strength program. If significant patellofemoral symptoms develop, the athlete may be unable to exercise the quads.

Persistent Tendon Defect

If the defect is not closed, there may be a persistent defect in the patellar tendon. This results in a weaker tendon.

Patella Entrapment

If the defect is closed too tight, the patella may be entrapped, and patellar infera may result. This will certainly result in patellofemoral pain, because of an increase in patellofemoral joint compression.

Patella Fracture

The fracture may occur during the operation or in the early postoperative period. Intraoperative patella fracture may be the result of the use of osteotomes. If the saw cuts are only 8-mm deep and 25-mm long, and the base is flat to avoid the deep V cut, an intraoperative fracture is rare. The late fractures are produced by the overruns of the saw cuts. The overruns may be prevented by cutting the proximal end in a boat shape.

The left X-ray (Fig. 5.2) shows a displaced transverse patellar fracture, at three months postoperative. The right X-ray (Fig. 5.3) shows the postoperative internal fixation with cannulated AO screws and figure-of-eight wire.

Figure 5.2. X-ray of displaced transverse patellar fracture at three months postoperative.
Figure 5.3. X-ray of postoperative internal fixation with cannulated AO screws and figure-of-eight wire.
Figure 5.4. The method of cutting the patellar bone plug to avoid a late fracture.

The proximal transverse saw cut is critical (Fig. 5.4). The stress risers that go beyond the edge of the bone block should be avoided. An overrun of 2 mm may cause a late transverse patellar fracture. If there are overruns, the burr may be used at the corner to round these cuts. The fracture is usually sustained by muscular contraction. Change to making the proximal cuts boat shaped to prevent the stress risers (Fig. 5.5). The graft is usually cut to this shape to pass into the joint; now it is just cut in that shape before removing it.

Tendon Rupture

This may occur if a very large graft is taken from a small tendon. The standard is a 10-mm graft, measured with a double-bladed knife. The bone blocks are trimmed to 9 mm to make the graft passage easier.

Figure 5.5. Boat-shaped proximal cuts.

Patellofemoral Pain

This topic is controversial in the literature. The older literature reported a high incidence of patellofemoral pain associated with ACL reconstruction. However, most of the disability could be blamed on rehabilitation programs that consisted of immobilization. There is no doubt that some patients will develop pain, some will develop crepitus, and some will have tendonitis, but results have improved with more aggressive rehabilitation programs with early motion and weight bearing. To prevent the patella from being bound down, the patella should be mobilized daily by the physiotherapist.

Arthrofibrosis

This severe problem is rarely seen now in ACL reconstructions. The true condition is idiopathic and is probably the result of fibroblastic proliferation. As a result, very little can be done to prevent it. It may be more common in the patient who forms keloid.

The more common condition of loss of range of motion may be the result of incorrect tunnel placement or postoperative immo bilization. In the mid-1980s, a limited range of motion hinge cast (preventing 30° of extension) was used for six weeks postoperatively, thereby causing problems in regaining extension. Many of these cases required arthroscopic debridement (10-18%, in the first year). The loss of extension was almost completely eliminated by changing to an extension splint. The acceptance of aggressive physiotherapy to regain extension eliminated the problem. This problem of postoperative stiffness made the use of a synthetic ligament, with no immobilization, very attractive. The reoperation for loss of range of motion is now very uncommon.

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