No Need to Immobilize Knee After ACL RepairShould a knee immobilizer or some other type of brace be worn after ACL repair? This is a question that remains unanswered despite many studies on the topic. Maybe only certain patients need immobilization. But is that's the case, then who should it be? And what kind of knee brace should be worn?
One way to get to the bottom of this issue is to study one aspect of the problem at a time. In this study, the authors specifically look at the effect of a soft, unhinged brace or immobilizer on knee pain. The effect of wearing the immobilizer versus no immobilizer was measured based on patientsâ reports of pain.
The immobilizer is different from a hinged brace. The immobilizer is a one-piece, soft, wrap-around piece of foam-lined canvas. It has three vertical metal bars for support and is strapped on with VelcroÂ®. A hinged brace is sometimes called a functional brace. It allows joint motion in flexion (bending) and extension (straightening). It is made of stiffer material than the immobilizer and has thin metal bars on either side of the knee to allow joint movement but prevent rotation.
Functional bracing is used to provide a derotation (prevents rotation) force. It is believed that this type of protection is needed during activities that require planting the foot on the ground and pivoting (twisting or turning while changing directions). The soft knee immobilizer just limits knee range-of-motion. It doesn't allow for functional movement.
Two groups of patients were compared. All patients were between the ages of 18 and 40 and had an ACL repair using a hamstring tendon graft. One group wore the soft immobilizer continuously during the first two weeks post-operatively. Patients were allowed to remove the immobilizer only for bathing and to perform their exercises. The other group did not get an immobilizer or brace of any kind. Everyone in both groups followed the same rehab program for the first two weeks post-op.
Pain level along with amount of pain medications used was measured for 14 days. The patients kept a daily logbook to record their pain levels and analgesic (pain relievers) use. Type of pain reliever and amount used were also recorded. Any complications that occurred were noted. Knee range-of-motion was recorded for the first three weeks after surgery.
The main measure used to evaluate the use of an immobilizer was pain during the first two days after surgery. The reason they used this as the key factor was because surgeons reported pain control as the primary reason for using a knee immobilizer. No one really knows whether or not the immobilizer is needed or if it even helps with pain.
In the end, it turned out that there were no differences in outcomes between the two groups. Patients in both groups had the same pain levels, used the same amount of pain relievers, and regained motion in the same amount at the same time. The researchers then took a look at the patients' characteristics to see if there were any differences in age, gender, or type of anesthetic used. It turns out that there were no statistically significant differences among those variables either.
Taking a closer look at the pain patterns (based on medication use), most of the pain relievers were taken on the first day. That was true for all patients in both groups. And the most common drug used was an antiemetic for nausea and vomiting, not for pain relief.
In general, complications were minimal and equal between the two groups. There were reports of skin numbness, wound scabbing, and knee joint swelling. Patient compliance was also reviewed. Overall, patients wore the brace as directed 76 to 100 per cent of the time. Everyone was very diligent to wear the immobilizer during the first two days. But entries in the logbook made it clear that compliance decreased over time. By the end of the study, only about one-quarter of the group wore the immobilizer more than 75 per cent of the time.
Some patients didn't like wearing the brace because it slid down or was uncomfortable. A few reported it was inconvenient putting it on and taking it off. At the same time, there were patients in the nonimmobilized group who wished they could wear a brace to protect their knees.
Based on the evidence from this study, the authors could not recommend an unhinged knee immobilizer for ACL repairs with a hamstring graft. It's possible that some other type of immobilization would be more effective. Perhaps using a hinged knee brace would appeal to patients more and improve compliance. The authors suggest trying a hinged knee brace next time. Patients could lock it at night to protect joint motion and wear it hinged during the day to allow motion.
Laurie A. Hiemstra, MD, PhD, FRCS(C), et al. Knee Immobilization for Pain Control After a Hamstring Tendon Anterior Cruciate Ligament Reconstruction. In The American Journal of Sports Medicine. January 2009. Vol. 37. No. 1. Pp. 56-64.
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