The patello-femoral joint is biomechanically very stressed when the knee is loaded. Any compromise of the joint surface is likely to lead to degenerative joint disease. It is, therefore, highly desirable, in patellar fractures to strive for anatomical reduction of the joint surface and stable fixation.
Combination of techniques
In fragmentary partial articular sagittal fractures, cerclage wiring may be used alone, or in combination with lag screw fixation of the major fragments.
If this surgical technique is used alone, it must be supplemented with a period of splintage or hinged knee bracing.
Verification of reduction
Anatomical reduction of the articular surface is monitored by palpating the joint from inside, as neither inspection nor the x-ray will reveal a minor step off. This will require creation of a small arthrotomy.
Nevertheless, an image intensifier or X-ray should always be available, so that the reduction can be checked in the AP and lateral planes if needed.
4. Aftercare following cerclage wiring of patellar fractures
Active knee function requires an intact knee extensor mechanism, a mobile patella, a well-preserved patello-femoral joint and muscle strength. Knee stiffness and muscle weakness can become a problem after the necessary period of splinting. Once deemed to be healed, a regimen of progressive knee mobilization and muscle strengthening must be supervised closely by the rehabilitation team.
Cerclage wire fixation alone may not be completely stable. A period of splinting with the knee in extension, may be required. Early active knee flexion and mobilization of the patient may be started with caution immediately after surgery. Static isometric quadriceps exercises should be started on postoperative day 1 with the knee extension splint in place. At a later stage (3 to 6 weeks), special emphasis should be given to active knee and hip movement.
A removable knee splint is applied postoperatively and worn until full quadriceps control is regained. Full weight bearing may be performed using crutches, or a walker, from postoperative day 1. A brace is usually used until 3 weeks after surgery.
Wound healing should be assessed regularly within the first two weeks. X-rays should be taken at 2, 6 and 12 weeks. A longer period may be required if fracture healing is delayed.
Implant removal may be required, as the wires may be prominent under the skin. Implant removal should not be undertaken until a minimum of 1 year postoperatively. Patients should be warned that cerclage wires may break during the healing process and may need to be removed somewhat earlier.
Consideration should be given to thrombo-embolic prophylaxis, according to local treatment guidelines.