Summary Femoral neck fracture nonunion represents a failure of bony healing after fixation of an intracapsular femoral neck fracture. Diagnosis is generally confirmed by radiographs demonstrating residual fracture lines, interval displacement and hardware failure. Treatment is operative ranging from valgus intertrochanteric femoral osteotomy to total hip arthroplasty depending on available bone stock, presence of avascular necrosis and patient age. Epidemiology Incidence occur after 10-30% of femoral neck ORIF Demographics increasing age at higher risk for nonunion Risk factors fracture morphology significant initial displacement vertically oriented fracture pattern (Pauwels type III) posterior comminution fracture malreduction, particularly with varus malalignment older age delay of fracture fixation >24 hours Etiology Pathophysiology mechanism of injury initial femoral neck fracture occurs due to high energy trauma in the younger population, and ground-level falls in the elderly nonunion occurs after fracture displacement and/or hardware failure before bony consolidation pathoanatomy femoral neck fractures are intracapsular, placing them at higher risk for nonunion than other hip fractures lack periosteal or extraosseous blood supply bathed in synovial fluid which deters fracture healing healing is intra-osseous only (no callus formation) achieving and maintaining anatomic reduction is essential Associated conditions orthopaedic conditions avascular necrosis (AVN) femoral neck malunion hardware failure surgical site infection leading to septic nonunion medical conditions or comorbidities low bone mineral density Anatomy Osteology normal proximal femur neck shaft-angle 130 +/- 7° normal proximal femur anteversion 10 +/- 7° proximal femur consists of tensile and compressive trabecular groups Muscles hip abductors important to preserve neurovascular supply and attachments of abductors to avoid abductor lurch and Trendelenburg gait Ligaments iliofemoral, ischiofemoral and pubofemoral ligaments attach to outer hip capsule and help to prevent excessive hip motion Blood Supply a confluence of arteries forms an extracapsular arterial ring that divides into the ascending cervical arteries which supply the femoral neck via perforators main blood supply in adults is the medial femoral circumflex artery (lateral epiphyseal artery) lateral femoral circumflex contributes to anterior arterial ring superior and inferior gluteal arteries give small contributions to arterial ring artery of ligamentum teres comes from obturator or medial femoral circumflex plays insignificant role in blood supply femoral neck fracture with displacement is thought to disrupt the blood supply to the femoral neck Biomechanics in double-leg stance, force vector through hip is vertical in single-leg stance, force vector through hip is parallel to femoral neck compressive load through hip is 4x bodyweight repetitive loading can increase tensile forces and lead to superior femoral neck fracture Classification Primarily descriptive Leighton's classification Type 1 Inadequate fixation or non-anatomic reduction Type 2 Loss of fixation with fracture displacement Type 3 Fibrous nonunion with no displacement and intact fixation Presentation History prior femoral neck fracture evaluation of medical history low bone density metabolic disease nutritional deficiencies tobacco use Symptoms persistent groin/buttock pain pain with weight bearing pain with hip extension pain may radiate down medial thigh/knee Physical exam inspection important to evaluate prior incision for drainage, erythema and to verify approach of prior surgery motion discomfort with active or passive range of motion at hip decreased internal rotation antalgic gait neurovascular evaluate sciatic and femoral nerve function provocative tests pain with log-roll pain with straight leg raise Imaging Radiographs recommended views AP pelvis and hip cross-table lateral hip full length femur optional views traction/internal rotation hip view contralateral hip films for intraoperative templating findings radiolucent fracture lines fracture settling failure of hardware (backing out) perforation of femoral head with hardware change in fracture position by >10mm femoral head collapse (AVN) calcar comminution varus malalignment CT indications most definitive way to diagnose femoral neck nonunion useful if diagnosis uncertain or for surgical planning MRI indications concern for diagnosis of femoral head AVN in the setting of nonunion Bone scan indications may help rule out concomitant femoral head AVN findings may show increased uptake in area of the nonunion Studies Labs indications must rule out infection inflammatory markers CBC with manual diff ESR CRP Hip aspiration indications if high suspicion for infection in the setting of elevated inflammatory markers Intraoperative tissue sample if concerned for infection, can send frozen-section for histology before proceeding with further fixation if positive for infection, staged approach preferred Treatment Nonoperative observation indications only indicated in non-ambulatory patients with comorbid conditions outcomes poor functional outcomes with non-operative management Operative revision ORIF indications not recommended due to: proximal bone loss residual leg length discrepancy high residual failure rates proximal femoral osteotomy indications failure of fracture fixation nonunion >3 months postoperatively varus collapse considerations femoral head viability remaining femoral neck bone quality patient age in younger patients, arthroplasty may be less desirable duration of nonunion longer duration may cause contractures, fibrosis and acetabular wear techniques valgus intertrochanteric osteotomy most commonly used salvage procedure primary issue is mechanical orientation of fracture in this group technique reorients vertical fracture to a horizontal fracture to achieve compression at the nonunion site improves abductor function by restoring femoral length and abductor lever arm patients may still describe persistent limp due to abductor weakness contraindications significant bone loss joint incongruity age > 65 (relative) outcomes 80-90% union rates high percentage of associated femoral head AVN but only small percentage remain symptomatic after osteotomy bone grafting indications failed prior fixation attempts nonunion remains well aligned with loss of posterior bone stock techniques quadratus femoris-vascularized pedicle graft free vascularized fibular grafting outcomes may not be as beneficial when fracture malalignment is primary cause of nonunion union rates up to 90% hip hemiarthroplasty indications low physical demand and more comorbidities cognitive decline techniques cemented vs. uncemented outcomes less extensile than THA lower dislocation rate compared with THA contraindications significant acetabular erosion total hip arthroplasty indications salvage operation of choice in older patients with femoral neck fracture nonunion prior femoral bony defect poor acetabular bone quality outcomes excellent 10-year survivorship (~90%) improved for patients greater than 65 complications dislocation rates may be decreasing with advent of new implant technologies trochanteric nonunion thromboembolic complication loosening infection hip arthrodesis indications young patients with nonviable femoral heads heavy manual laborers outcomes arthroplasty becoming favored over arthrodesis, even at young age Technique Observation bedrest, non-weightbearing on affected extremity complications may increase risk for other systemic complications Revision ORIF approach through initial incision when appropriate technique removal of hardware, adequate reduction of fracture new stable bony fixation with bone grafting complications very high failure rates residual leg length discrepancy Valgus intertrochanteric osteotomy approach direct lateral approach to proximal femur technique goal is to convert vertically oriented fracture to about 30 degrees in order to create compression can use blade plate or sliding hip screw for ultimate fixation complications femoral malrotation excessive medialization of femoral shaft can decrease offset cause abductor efficiency a longer blade can avoid medialization of shaft Bone grafting approach lateral incision just anterior to greater trochanter between 10-15cm long technique quadratus femoris-vascularized pedicle graft insertion of quadratus taken down off the greater trochanter with a bony flap that is transplanted to the posterior femoral neck and sutured or fixed into place with screws free vascularized fibular grafting complications donor site morbidity may need to be combined with mechanical realignment Hip hemiarthroplasty approach posterior anterolateral direct anterior technique unipolar vs. bipolar recent studies have not shown bipolar femoral heads to provide any benefit over unipolar heads cemented shows superior outcomes, fewer complications than uncemented complications results of failed hip hemiarthroplasty when converted to THA are worse than primary THA. Total hip arthroplasty approach similar to hip hemiarthroplasty technique there may be residual bony defects in proximal femur from old hardware may have to bypass this area with longer stems may increase risk for intraoperative fracture while reaming the canal poor acetabular bone quality can make cup placement difficult and increase risk for fracture avoid overly aggressive acetabular component impaction augment cup with screws complications dislocation use of larger diameter heads and new implant technology (i.e dual mobility) may be helpful in decreasing dislocation rates increased rates of aseptic loosening risks include patient age < 65 and BMI >30. Hip arthrodesis approach lateral approach with trochanteric osteotomy technique optimal positioning of hip joint: 20-35° hip flexion 0-5° adduction 5-10° external rotation complications adjacent joint arthrosis/pain low back pain Complications Concomitant femoral head AVN incidence up to 40% in setting of nonunion around 15% appear to be symptomatic risk factors initial fracture displacement poor reduction treatment hip arthroplasty Acetabular cartilage degeneration risk factors associated femoral head AVN or chondral wear treatment total hip arthroplasty Trendelenburg gait risk factors loss of femoral offset secondary to abductor inefficiency in nonunion/malunion or valgus producing osteotomy treatment avoiding loss of femoral offset or damage to abductors during salvage operations Prosthetic dislocation incidence 10-20% in salvage total hip arthroplasty group compared to <10% in primary arthroplasty group after femoral neck fracture risk factors abductor insufficiency abnormal hip joint kinematics after nonunion posterior hip approach treatment larger femoral heads, dual mobility implants may decrease risk choose surgical approach to optimize stability Prognosis Natural history typically, patients present with pain and difficulty with ambulation months after fixation persistent pain with radiographic lack of healing at 3 months signifies likely nonunion. revision surgery should be considered at this point. Prognostic variables (poor) unfavorable fracture patterns malreduction poor bone quality Survival with treatment valgus intertrochanteric osteotomy eventual union rates of 80-90% hip arthroplasty approximately 90% implant survivorship at 10 years, 75% at 20 years. higher rate of dislocation (up to 10-20%), compared to primary hip arthroplasty