Post septic arthritis with arthritis in the young patient is not an uncommon condition in India and Asia. The characteristic feature of a post septic arthritis is the small size of the femoral head due to the damage undergone during the phase of the infection. What in not readily apparent on the x-rays are the soft tissue contracture which occurs as a consequence of the infective process. This stiffness and contracture makes the hip reconstruction very complex. Appropriate releases have to be done to regain movement and length. The sciatic nerve is also at risk with the surgery.
Appropriate releases must be done Restoration of biomechanics is critical.
The hip must be balanced accurately.
Limb length must be achieved without over lengthening.
In post septic sequealae it is very critical to restore the biomechanics of the hip and not just do a THR. As the head of the femur is small and ill-developed a routine technique will not suffice in this situation. We employ a specialised technique by which the femoral head is converted to the femoral neck to make up for the deficiency of the femora l neck. This restores the normal biomechanics completely.
The various steps of the surgical procedure are given below. The preop x-ray given below shows the deficient neck. The post op x-ray given below illustrates how a portion of the head is converted in to the neck to restore the biomechanics.
At times when the post septic situation with associated with gross shortening, a sub trochanteric shortening is required to bring down the hip without compromising the sciatic nerve.
Soft tissue contracture can be so stiff that the hip is framed without movement in any direction. In this situation a conventional trochanteric osteotom is the only way to mobilise the hip as in the example shown below.
Rarely the hip infection is also co-existent with infection in the canal of the upper femur (osteomyelits). Here it is difficult to put in a stem. Further it is better to stay away from the infected focus if possible. Here the best reconstructive option is a Birmingham Hip Resurfacing. The postop x-ray is a 9 yrs follow-up film of the patient.
Our unit has a large experience in dealing with post TB hip. The guidelines for treatment of a post TB hip have been evolved in our unit and we have seen more than 99 % success with post TB hip.
Surgical steps of the procedure - sub trochanteric osteotomy if required
Immediate postop x-rays
4 Months postop x-rays showing full union of the osteotomy