One of the most common postoperative complications following ACL reconstruction is loss of range of motion, particularly loss of knee extension. Recent studies have shown that up to 25% of all ACL reconstructions will have a loss of knee extension range of motion postoperatively. That seems like a pretty significant amount of people to me.
Biomechanically, loss of knee extension range of motion has some fairly serious implications. In addition to increased patellofemoral issues and potential wear and tear to the articular cartilage, loss of knee extension creates an environment that does not allow the knee to lock into the “screw home” mechanism. In turn, you can’t lock out your knee and your quadriceps has to fire at all times to stabilize the knee. Over time, these patients tend to struggle with quadriceps strength gains and return to functional activities.
All this considered, as rehabilitation specialists, one of our prime concerns when working with ACL reconstructions patients has to be restoring full passive knee extension as soon as possible. People familiar with my protocols will know that this is emphasized immediately after surgery (newsletter subscribers get a copy of my accelerated ACL reconstruction protocol for free).
Understanding risk factors that are associated with loss of motion following ACL reconstruction will allow us to identify specific patients that are at great risk.
It has been documented that preoperative range of motion is highly correlated with postoperative range of motion, meaning that the more motion you have going into surgery, the more you’ll have after surgery. This has led to a trend of delaying surgery to allow the knee to “quite down,” so to say, and allow for the reduction of effusion and inflammation.
A new study set to be published in an upcoming issue of the American Journal of Sports Medicine has also identified that the presence of a bone bruise also correlates with loss of motion. In this study, 75% of patients with preoperative loss of motion and 46% of patients with a bone bruise on the lateral femoral condyle and lateral tibial plateau presented with delayed range of motion recovery. Considering that past studies have shown bone bruises to be present in 70-80% of ACL injuries, this is a significant finding.
Clinical Implications
My personal belief is not that one has to wait a certain amount of days before they have surgery, but rather that they have to wait until they are “ready” for surgery. What does that mean to me? Well, here is my criteria of a knee that is “ready” for surgery:
- Minimal effusion and inflammation
- Full knee extension and good flexion range of motion
- Volitional control of the quadriceps – i.e. they can actively contract the muscle with out an extension lag
- Normal gait without an antalgic limp or quad-avoidance pattern
Patients with bone bruises tend to have more pain, swelling, and inflammation. These patients may require a little longer preoperative period to assure that their knee is “ready.” Again, I feel that he duration should be individualized. But, the results of this study make sense to me.
I would also recommend trying to find out if your patient had a bone bruise. Ask the surgeon or even the patient. Try to get a copy of the operative note and MRI radiology report. This is valuable information as you will know what to expect if your patient appears to be struggling postoperatively. We should be extra cautious that these patients restore extension range of motion as soon possible after surgery. Perhaps these are the patients that get a few more visits scheduled during the early phases of rehabilitation or get prescribed more frequent stretching as part of their home exercise program.
What do you think? How would you treat someone with a bone bruise differently?
