See: Posterior Frx Dislocations of the Hip
- irreducible dislocation:
- due to soft tissue interposition (ligamentum teres, capsule, labrum, piriformis, ect.);
- incongruent joint:
- due to intra-articular bone and cartilage fragments;
- often interposed fragments will reside on the side opposite of the dislocation;
- unstable reduction:
- often due to large posterior wall fracture;
- Open Reduction: Indications and Goals;
- to remove loose fragments of bone & cartilage from joint space
- to ensure accurate reduction of the dislocation;
- to prevent osteoarthritis by reducing any articular step off to less than 2 mm;
- to restore joint stability & joint congruity by ORIF of large posterior wall fragments;
- hips with > 40-50% involvement of posterior wall (as determined by CT scan) or with posterior subluxation will be unstable and will require ORIF to restore acetabular wall;
- Surgical Approach:
- depends on the presence, location, and size of the femoral head fragment as well as the posterior wall fragment;
- may use either the anterior or posterior approach;
- w/ large posterior wall fragment and small infra-foveal fragment consider posterior approach w/ non operative treatment of femoral head fragment;
- w/ good posterior stability and a large femoral head fracture fragment, consider anterior approach for fixation of the femoral head fragment and non operative treatment of the posterior wall fragment;
- historical concerns:
- there might be a greater occurance of AVN w/ anterior approach because most of blood supply to the hip joint is damaged at time of posterior dislocation; (see blood supply to femora head);
- anterior approach:
- according to the report by Swiontkowski et al 1992, there was significant decreases in operative time, estimated blood loss, and improved visualization and fixation with the anterior approach;
- there were no cases of AVN with the anterior approach;
- the only disadvantage was increased HO, which is most likely due to stripping of the abductors off the ilium;
- posterior approach:
- if femoral head fragment is above the fovea, then attached ligamentum teres prevents reduction of the femoral head fracture;
- with small infrafoveal fragments, a posterior approach may allow fixation or debridement of the femoral head fragment;
- once joint is exposed carefully irrigate - remove all loose fragments;
- if hip has not reduced previously, it can then be reduced w/o traumatizing the articular cartilage.
- care is taken not to remove any soft tissue - avoid further devasulcarization;
- frx fragments can then be repositioned to provide anatomical reduction of acetabular fracture;
- this is most easily accomplished when there is a single large fragment, as in a type II injury;
- fixation is obtained by cancellous screws;
- avoid penetration the acetabular floor;
- either multiple pin fixation or fixation w/ small malleable plate to ensure stability is satisfactory when there are several large fragments to provide a bony butress;
- Heterotopic Ossification
- may occur in the majority of patients with Pipkin III and IV frx;
- a relative contra-indication of XRT may be posterior hip dislocation w/ femoral head frx, since there is a theoretical risk of contributing to AVN or non-union;
- AVN after Hip Dislocation:
- incidence of AVN is 15% in posterior dislocation;
- incidence of AVN is approx 4% in anterior dislocation
Hip Dislocation: Current Treatment Regimens.
Biomechanical consequences of fracture and repair of the posterior wall of the acetabulum.
Fractures of the femoral head.
Computed tomography evaluation of stability in posterior fracture dislocation of the hip.
Stability of posterior fracture-dislocations of the hip. Quantitative assessment using computed tomography.
Operative management of displaced femoral head fractures: case-matched comparison of anterior versus posterior approaches for Pipkin I and Pipkin II fractures.
Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis.