Dislocation of the hip is a serious condition that may have significant complications. pure hip dislocation with or without fracture of the acetabulum or femoral head can cause complications. the worse complication associated with dislocation of the hip is avascular necrosis due to damage to the blood supply. AVN is death of a segment of the bone in the femoral head. Avascular necrosis may occur if the dislocation is not reduced in a reasonable period of time. Emergency reduction of dislocations is needed in less than 8 hours of injury. Although xray is helpful a CT scan clearly outlines the bony injury.
Other complications associated with dislocation of the hip is injury to the sciatic nerve and arthritis of the hip joint. Injury to the sciatic nerve is about 1020% of the cases involving posterior dislocation. The sciatic nerve starts in the lower back and runs through the buttock and lower limb. In the lower thigh, just above the back of the knee, the sciatic nerve divides into two nerves, the tibial and peroneal nerves, which innervate different parts of the lower leg. The common peroneal nerve then travels anteriorly around the fibular neck, dividing into superficial and deep peroneal nerves. The deep peroneal nerve gives innervation to the tibialis anterior muscle of the lower leg which is responsible for dorsiflexion of the ankle. When injury occurs to the sciatic nerve due to posterior hip dislocation, the common peroneal nerve is usually affected, causing weakness in dorsiflexion of the ankle and loss of toe extension can also occur. Movement of the toes may appear as dorsiflexion, however, this really is the result of plantar flexion.
Documenting the injury is important to avoid medical legal problems. Injury to the sciatic nerve typically occurs from the dislocation and not from the reduction. The longer the wait for reduction of the dislocation, the more the patient is predisposed to sciatic nerve injury. The length of time a hip remains dislocated influences the incidence and severity of major sciatic nerve injury. The patient may require antifoot drop splint.
Treatment of peroneal nerve injury/foot drop
•Physical therapy
•Wait for recovery
•Study the condition of the muscles with EMG and nerve studies
•Condition may take a long time for recovery
•Usually partial recovery of the nerve in majority of the cases.
•If no recovery is achieved, explore the nerve for repair, graft or tendon transfer.
•Sciatic nerve palsy could occur from surgery due to retractors or from traction usually in posterior hip surgery.
•Preoperative partial injury of the nerve could deteriorate after surgery.
•Preoperative documentation of the nerve injury is important.