Infection of the hip joint that is undiagnosed and therefore untreated can lead to a condition known as septic arthritis. In young children, dislocation of the septic hip can be a challenge.
For one thing, the hip that is not fully formed can look like it is dislocated when, in fact, it’s not. If the growth center of the hip (called the capital femoral epiphysis) is not fully ossified (turned to bone and connected to the femur or thigh bone to form the round femoral head), it can give the hip the appearance of being dislocated.
Before a treatment plan can be determined, the surgeon must know for sure whether the child’s hip is truly dislocated or just not fully formed yet with an intact capital femoral epiphysis still in place. X-rays are not enough so that MRI, ultrasound, and/or arthrogram are required.
This article was written to aid surgeons in the management of late presenting cases of septic hip dislocation. Mini-summaries of treatment results from small case studies are reviewed. Treatment reported ranged from no reconstructive surgery called closed reduction with full (spica) cast immobilization to open reduction.
The goals of stabilizing the hip versus restoring normal anatomy depend on knowing whether the capital femoral epiphysis is present or the hip is dislocated. Treatment decisions are also influenced by the age of the child. For example, children under the age of two may be successfully treated with closed reduction. Open reduction is recommended for children older than that.
Treatment may include preoperative traction to pull the dislocated hip down to the level of the acetabulum (hip socket). Some surgeons prefer to shorten (or lengthen) the femur to accomplish this same alignment. Soft tissue structures may be needed such as lengthening of the psoas (hip flexor) muscle or tendon.
Sometimes the surgeon must do a bony osteotomy (remove a wedge-shaped piece of bone from the femur) to correct a problem with the angle of the hip. A shelf procedure may be needed to extend the bone and form a cover around the femoral head. This keeps it from migrating upward and dislocating again.
The following treatment recommendations were offered based on results reported in the literature and the authors’ own experience. Relocation of the hip is not always the best idea. It can result in chronic hip stiffness, leg shortening, and a definite lurch in the gait (walking) pattern. Patients with oddly shaped femoral heads and poor (thin) articular cartilage from the infection often end up with degenerative arthritis and chronic pain even with hip relocation.
Patients should be selected carefully for open reduction and surgical restoration of the hip. A nice, round femoral head of good size is important. Healthy cartilage is a good prognostic factor (meaning surgical treatment is more likely to yield good results). Children older than six years old are not likely to benefit from open reduction. And finally, the patient who does NOT have stiffness before surgery has a better chance of good recovery and positive outcomes.
The authors do provide an algorithm (flow chart) to aid surgeons in making treatment decisions for patients with postseptic hip dislocation. Starting with a proper diagnosis based on imaging studies, the chart flows first according to age (under two or over two years of age).
As mentioned, closed reduction with soft tissue releases and hip cast can be followed by open reduction if the conservative care is unsuccessful in the younger child. Surgery (if performed at all) is for selective patients as described.