POSTERIOR DISLOCATION OF THE HIP

What does this radiograph show and how would you manage this in the emer gency department?

This is an AP radiograph of the pelvis, demonstrating a posterior fracture dislocation of the hip. There is an associated fracture of the posterior wall of the acetabulum. As this is a highenergy injury, I would assess and manage the patient as per ATLS guidelines. I would assess the neurovascular status of the limb, particu larly the sciatic nerve, and provide analgesia. The patient requires emergent reduc tion of the hip in order to reduce tension on the sciatic nerve and reduce the risk of AVN, and I would perform this in theatre to ensure the patient can be fully anaes thetised with general anaesthesia and muscle relaxant in order to minimise trauma to the femoral head when performing the reduction. Following reduction and my assessment of the stable range, I would expect the hip to be unstable in flexion, so I would immobilise the patient in a soft Thackray knee splint to limit hip flexion.

 

Describe how you perform a closed reduction?

I would perform Bigelow’s manoeuvre. This requires an assistant to stabilise the pel vis via the anterior superior iliac spines. I would then apply traction, adduction and internal rotation. Reduction is usually associated with an audible ‘clunk’ and would be confirmed using the image intensifier. I would then assess stability of the hip as this may determine the need for further operative intervention. I would do this

 

 

under image intensifier as I would not want to redislocate the hip and risk further cartilage damage.

What would your postoperative management consist of following a closed reduc tion of the hip?

I would confirm and record the stable range of movement of the hip once reduced. I would assess the neurovascular status of the patient in theatre recovery, particu larly the sciatic nerve. I would want to obtain a CT scan of the hip urgently in order to rule out any intraarticular bony fragments in addition to obtaining a better appreciation of the posterior wall fracture.

 

What are the indications for fixing a posterior wall fracture in association with a hip dislocation?

Surgery is required if there is instability of the hip (best confirmed in theatre follow ing closed reduction) or a lack of joint congruity.

 

How would you proceed if the hip would not reduce closed?

Failed closed reduction necessitates an open reduction through a posterior approach to the hip, extended proximally into a Kocher–Langenbeck approach if there was a posterior wall fracture in need of fixation. I would take particular care not to dam age the sciatic nerve as it may be displaced due to the dislocated hip. I would be careful to stay away from quadratus femoris in order to avoid damage to the medial circumflex femoral artery (MCFA), and would incise the short external rotators at least 1.5 cm from their insertions to again avoid damage to the MCFA.

 

What would you use to fix the posterior wall fracture?

There are several constructs available depending on the size of the fragment and the degree of comminution. I would assess the fragment intraoperatively and then use either large fragment lag screws +/– buttress plate using a 3.5 mm reconstruction plate, or create a hook plate by breaking a small fragment onethird tubular plate through a hole at the tip and bending the ends such that the hooks are perpendicular to the plate.

 

What clinical and radiographic findings would you see in an anterior dislocation of the hip, and what is the usual mechanism of injury for this?

Anterior dislocations of the hip are rare and they occur when the hip is in a posi tion of abduction and external rotation. Clinically, the leg may be shortened and generally held in flexion, abduction and external rotation, compared to a posterior dislocation where the leg is held in flexion, adduction and internal rotation.