hip dislocation

Monday, October 19, 2015

The thrill of victory quickly turned into the agony of defeat in just seconds for Michigan as a blocked punt was returned for a touchdown. And for freshman Jalen Watts-Jackson, who scored that touchdown, his thrill was replaced with agony in just a split second. In the end zone pile that ensued, Mr. Watts- Jackson dislocated his hip and his season, and perhaps his career, came to an abrupt end.

Hip dislocations are rare occurrences in sport. It takes just the right angle of the hip and knee and just the perfect force applied to the leg to have the femoral head (the ball of the hip joint) torn out of the acetabulum, the hip socket located in the pelvis. Often, the posterior portion of the acetabulum fractures as the ball is forced backwards and dislocates posteriorly. It takes plenty of force to damage the joint and for that reason, hip dislocations are most often seen in car wrecks or pedestrians hit by cars. It’s possible for the hip to dislocate anteriorly or to the front, but that is even more rare, and in sports , it is usually seen only in downhill skiing accidents.

scoi-hip 230px-HipdisX

The mechanism of the posterior hip dislocation is almost always the same. The knee and hip are in a sitting position, both flexed at 90 degrees plus the hip has to be turned in just a little (internally rotated). The player then needs to be tackled from behind so that the whole weight lands on the knee, so all the force is driven into the back of the hip socket. Add the weight of the tackler on the back of the tackled player, and the hip socket can’t withstand the force and the hip shatters the back of the socket as it dislocates. Imagine sitting in a car and being hit head on. The dashboard gets pushed into your bent knee and the force drives the ball of your hip back through the hip socket towards the car seat. That’s the leg position, the direction and amount of force needed.

The diagnosis is often made clinically by physical exam because the leg is shortened and the leg is internally rotated (again, turned inward). Xrays are needed to know where the bones are and what may or may not be broken. The initial treatment is to reduce or relocate the femoral head back into the acetabulum. Because there are large muscles that surround the hip that go into almost immediate spasm, intravenous medications are needed to sedate the patient and relax those muscles so that the hip can be pulled back into place. However, the work is not done once the hip is relocated. The bones that make up the acetabulum need to be further assessed and usually a CT or MRI is required to look for bone fragments or hidden breaks that might require surgery to reconstruct the joint.

There is a relative urgency in reducing a hip dislocation to try to avoid a couple of complications.

  • First, the sciatic nerve runs behind the hip and if the hip dislocates posteriorly, the nerve can be stretched. The longer that the nerve is irritated, the increased chance that it can be damaged.
  • Second, the blood supply to the femoral head is fragile and when the hip is dislocated, blood vessels can be stretched or torn. The longer that the hip remains dislocated, the longer that the blood supply may be compromised, potentially resulting in avascular necrosis of the femoral head, the medical way of saying that the bone in the ball will die because it has lost its blood supply. That said, even if the hip is relocated quickly, the risk of avascular necrosis (AVN) remains. For sports historians, Bo Jackson suffered AVN requiring hip replacement surgery.

Once all has been made well, with or without the need for surgery, rehabilitation is measured in weeks and months not days. It takes time for the soft tissues like cartilage and labrum to heal tighten. If the joint remains loose, the risk of another dislocation remains. Physical therapy can be aggressive and the goal is to return the patient, whether an athlete or not, to full function. Every person heals differently and the prognosis for good to excellent results can be found in 50-90% of patients. It’s a wide range but hopefully, with aggressive care and rehab, the number skews closer to the upper end. It all depends upon whether AVN occurs, the sciatic nerve stops working or osteoarthritis develops.

The goal for Jalen Watts-Jackson is to return to playing football. The injury took just a second to occur but return to play will take a much longer commitment. Hopefully, the effort that it took to become an elite athlete will be required to become a rehabilitated athlete. When it comes to hips, the goal is for Jalen to know Jalen, like Bo knows Bo.

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