Salvage Hip Surgery in Skeletally Mature Neuromuscular Patients



Salvage Hip Surgery in Skeletally Mature Neuromuscular Patients


Brian Snyder



Pathophysiology of Hip Subluxation



  • Pathophysiology and pathoanatomy differs from developmental hip dysplasia


  • Hips are normal at birth


  • Muscle imbalance → bony deformity→ hip dysplasia


  • The lateral and posterolateral acetabulum is most often deficient


  • Natural history = increasing dysfunction with remaining growth and progressive subluxation


  • Progressive subluxation adversely affects hygiene, sitting, upright posture ± gait


  • Leads to pain in early adolescence


Surgical Considerations



  • Coexisting hip and spine pathology (hip/spine syndrome)



    • Fixed deformities (contractures, instability, and dysplasia) of the hip joint result in pelvic obliquity with subsequent development of secondary lumbar scoliosis


  • “Windswept” hips



    • Adduction one hip, abduction of the other


    • Pelvic obliquity ± torsion/rotation (torsional dystonia)


  • Presence of scoliosis and significance?



    • Chicken versus egg


    • ↑ Pelvic obliquity → compensatory lumbar scoliosis


    • ↑ Lumbar curve → pelvic obliquity → “windswept” hips


  • Salvage surgery is designed to help reduce pain, but pain can be present after surgery for 6 to 12 months, and this needs to be communicated to the families preoperatively


Physical Examination



  • Assess hip range of motion—symmetric adduction contracture = loss of hip abduction ± flexion contracture; internal and external rotation with hips in extension = femoral version


  • Asymmetric abduction = windswept hip deformity, pelvic obliquity, scoliosis


  • + Galeazzi, Ortolani signs = hip instability (subluxation/dislocation)


  • Look for skin problems in deep creases and assess prominence of dislocated hip


  • Assess scoliosis and upper extremity contractures and consider access issues for time of surgery



Decision-Making for Hip Salvage Surgery



  • Total hip replacement



    • Reserved for Gross Motor Function Classification System (GMFCS) I/II patients with severe femoral head deformity


  • Chiari pelvic osteotomy



    • Consider for GMFCS III/IV with moderate femoral head deformity but reducible head


  • Femoral head resection (Castle procedure)



    • Consider for our medically complex children, supine positioning, quick surgery <1 hour, prophylax with radiation to prevent heterotopic ossification


  • McHale valgus subtrochanteric osteotomy and Castle procedure



    • Consider for GMFCS III/IV children who enjoy standing to create a pelvic support osteotomy to facilitate standing post-op


  • “Schoenecker” Girdlestone procedure through a surgical dislocation approach



    • Most common surgical approach for GMFCS IV/V children with minimal standing and significant pain


Preoperative Medical Considerations



  • Pulmonary assessment—look for presence of restrictive lung disease



    • Forced vital capacity (FVC) < 25%—higher risk of complications


    • Upper airway obstruction—tonsillectomy/adenoidectomy


  • Nutrition—poor nitrogen balance = poor wound healing



    • Absolute neutrophil count >1200, serum albumin >3


    • G-tube—often helps with postoperative course


  • Seizure control—be mindful of medications which increase bleeding and delay clotting


  • Gastrointestinal (GI) disorders—dysphagia, constipation—make sure clean out preoperatively


  • Osteopenia—poor purchase bone implants



    • Dual-energy x-ray absorptiometry (DEXA) scan to measure bone density


    • Vitamin D supplement ± bisphosphonates (if previous fragility fractures)


Perioperative Management



  • Epidural anesthesia intraoperatively, 2 to 3 days postoperatively


  • Antifibrinolytic tranexamic acid administered to decrease intraoperative blood loss


  • Diazepam for postoperative muscle spasms


  • Hinged hip abduction brace or A-frame short leg cast for 3 weeks



    • NO SPICA


    • Be vigilant for skin breakdown, pressure ulcers


Chiari Osteotomy


Operative Indications



  • Chiari osteotomy is a “salvage” osteotomy for acetabular dysplasia in the painful, unstable hip


  • Indicated for hips where congruous reduction is not possible because of arthrosis or femoral head asphericity that prevents use of more standard rotational periacetabular osteotomies


  • Indicated for household ambulators (GMFCS III/IV)


  • Goals are improved femoral head coverage, stable articulation


Contraindications



  • Severe arthrosis


  • Significant proximal femoral head migration


  • Cannot perform this bilaterally at 1 surgical setting for fear of creating pelvic discontinuity




Equipment



  • Standard retractors for hip and pelvic surgery, cerebellar retractors or Charnley if available


  • A series of angled osteotomes including Ganz and Mast chisels


  • Radiolucent retractors


  • Large fragment long pelvic screws or Steinman pins and Kirschner wires (K-wires) can be used for osteotomy fixation


Positioning



  • The patient is positioned supine on the operating room table


  • Sloppy lateral with a bump can also be helpful if possible


  • Free drape the operative extremity from the costophrenic margin superiorly, medially to the ipsilateral border of the perineum, and laterally to the border of the buttocks


Surgical Approach



  • The ilioinguinal approach is the exposure of choice for this osteotomy


  • The incision begins approximately 1 to 2 cm below the iliac crest and extends medially 1.5 to 2 cm distal and medial to the anterior superior iliac spine (ASIS)


  • The lateral fibers of the external oblique muscle overhang the lateral ilium and are reflected off the ilium with electrocautery or a #15 blade. Care is taken to clear the iliac apophysis of soft tissue and maintain meticulous hemostasis


  • Distally the interval between the sartorius and tensor fascia lata (TFL) is identified. The TFL fascial compartment is opened, and muscle is stripped directly off the intermuscular septum with a Cobb or periosteal elevator (Figure 39.1)


  • The TFL is retracted laterally, and the intermuscular septum and sartorius muscle are retracted medially


  • At this level, the lateral femoral cutaneous nerve of the thigh lies within the sartorial muscle compartment and is not visualized; however, the nerve lies under the fascia between the two muscles and care must be taken to avoid injury during the approach and when closing to avoid a painful neuroma


  • Blunt dissection of TFL is continued proximally to the ilium and to the level of the anterior inferior iliac spine (AIIS)


  • Continue subperiosteal dissection anteriorly from ASIS inferiorly to the AIIS. Identify the direct head of the rectus femoris inserting into the AIIS, and locate the bifurcation of the indirect head


  • At this point, the iliac apophysis is split in the midline, the gluteal muscles are subperiosteally dissected off the outer table ilium and the iliacus muscle is dissected subperiosteally off the inner table of the ilium, and a moist sponge is packed tightly between the ilium and dissected muscles to aid in retraction and hemostasis








  • Now the outer table is dissected away subperiosteally from the abductor musculature inferiorly until firm resistance is met. This resistance indicates the insertion of the indirect head of the rectus femoris on the lateral aspect of the hip capsule


  • Return back to the bifurcation of the direct and indirect heads of the rectus femoris tendon. Ligate the indirect head at the bifurcation and follow it posterolaterally to the suspected inserted into the lateral hip capsule


  • Dissect posteriorly along the outer and inner tables of the ilium to the level of the greater sciatic notch. Use a lane retractor to subperiosteally elevate the superior gluteal artery and sciatic nerve away from the apex and anterior margin of the notch


  • Incise the periosteum along the superior border of the indirect head of rectus femoris. This will allow subsequent release of the abductor minimus off the superior capsule to allow for proper chisel placement for the Chiari osteotomy (Figure 39.2)


  • At this point, use fluoroscopy to ensure that you have not been misled by a pseudoacetabulum and your dissection has carried you down to the acetabular margin. Visualization at this point of the operation is paramount


Techniques in Steps


Creating the Osteotomy



  • Essentially, the osteotomy is creating a transverse acetabular “fracture” where both the anterior and posterior acetabular columns are cut and the ilium is displaced posterolaterally over the hip joint capsule forming a shelf


  • The osteotomy is a curvilinear in the supra-acetabular region. It begins at the anterior ilium at the level of the AIIS and traverses the capsular edge of the acetabulum to terminate at the sciatic notch (Figure 39.3)


  • We use a modification advocated by John Hall where the osteotomy is truly curvilinear. The posterior limb of the osteotomy is curved distally aiming a centimeter below the apex of the sciatic notch to increase posterior coverage, thus making the osteotomy more dome-like in appearance (Figure 39.4)


  • The start of the osteotomy is determined anatomically and radiographically


  • Anatomically, the osteotomy is started anteriorly at the capsular margin; this point is double-checked with fluoroscopy to ensure that we are not within the false acetabulum