- hip fusions acn occur spontaneously following childhood sepsis or after ORIF of acetabular fractures (secondary to heterotopic bone).
- they also occur spontaneously due to ankylosing spondylitis;
- surgical fusions are performed for young adults with advanced arthritis;
- desire to return to near-normal physical activity with manual labor;
- 20 yrs years after surgery, 80% of pts w/ hip arthrodesis performed at relatively young age were working & satisfied w/ their results;
- relief of pain;
- young male;
- normal contralateral hip, ipsilateral knee, and a low back are prerequisites in preoperative planning;
- pain and instability of the ipsilateral knee may also occur in pts w/ a fused hip;
- pts w/ long-standing hip fusion may develop progressive nonradicular pain in the low back that worsens with activity;
- no cardiovascular pathology:
- rate of oxygen consumption is 32% greater than normal;
- average walking speed was 84% of normal gait velocity;
- Surgical Considerations:
- position of hip fusion:
- neutral abduction, exteran rotation of 0-30 deg &, 20-25 deg of flexion;
- avoid abduction and internal rotation;
- this position is design to minimize excessive lumbar spine motion and opposite knee motion which helps minimize pain in these regions;
- may use either an anterior or posterior approach inorder to dislocate the hip and to remove the joint surfaces;
- AO Cobra Plate: stable but disrupts abductors:
- trans-articular sliding hip screw:
- lag screw is inserted across the joint and just superior to the dome of the acetabulum;
- disadvantage of this technique includes poor fixation (due to large lever arm and the resulting torque on the lever arm) and need
for postoperative hip spica casting;
- some authors advocate supra-acetabular osteotomy or subtrochanteric osteotomy for improved positioning;
- Combined hip fusion and subtrochanteric osteotomy allowing early ambulation.
- Osteotomy as an aid to arthrodesis of the hip.
- contra-lateral epiphysiodesis:
- limb-length discrepancy resulting from disruption of the proximal femoral epiphysis has a negative effect on gait mechanics;
- consider epiphysiodesis of the distal femoral epiphysis (at the appropriate age) inorder to equalize leg length descrepancy;
- expect that most patients will have complications which are either major or minor;
- malposition (most common)
- leg length descrepancy (common and can be severe enough to require lift);
- DJD or instability of ipsilateral knee, back, and contralateral hip;
- low back pain is present in over 50% of patients with hip fusion;
- in the study, by Karol LA, et al (2000), the authors performed gait analysis on hip fusion patients;
- gait analysis showed excessive motion in the lumbar spine and the ipsilateral knee in all nine patients;
- abnormal motion led to pain as the duration of follow-up increased, and all patients who had been followed for four or more years
after the arthrodesis complained of back pain;
- excessive hip flexion may cause excessive compensatory lumbar lordosis (leads to back pain);
- more than 10 deg of hip adduction or abduction may lead to varus/valgus knee instability;
- Gait and function after intra-articular arthrodesis of the hip in adolescents.
- Conversion of Fused Hip to THR
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