Neck of Femur Fractures - Dynamic Hip Screw and Cannulated Screws

The single decision. For a femoral neck (intracapsular) fracture the choice is between internal fixation and arthroplasty, driven by displacement and patient factors, not by the Garden number in isolation. For an intertrochanteric or subtrochanteric (extracapsular) fracture the choice is between a dynamic hip screw (DHS) and a cephalomedullary nail, driven by stability. Intracapsular (femoral neck) fractures — fix or replace?

Choosing between hemiarthroplasty and THR (when arthroplasty is indicated). Offer THR to independent ambulators with intact cognition, life expectancy greater than 5 years and a healthy acetabulum. Offer hemiarthroplasty to patients with limited mobility, cognitive impairment, significant comorbidity or shorter life expectancy. The HEALTH trial tempers this: in fit patients THR gives at best a marginal functional gain over hemiarthroplasty at the cost of higher dislocation, so it is selected rather than applied routinely. A special case — posterior tilt in undisplaced fractures. Garden I-II does not always mean fix. Posterior tilt of 20 degrees or more on the lateral radiograph (Okike, FAITH secondary analysis) doubles the risk of later conversion to arthroplasty, especially in patients 80 or older — consider primary arthroplasty rather than screws. Extracapsular (intertrochanteric or subtrochanteric) fractures — DHS or nail?

Age and functional framing. - Young patients (under 60): preserve the native femoral head at almost any cost. Demand anatomical reduction (under 2mm displacement), accept the AVN/nonunion risk, and proceed to open reduction if closed reduction is inadequate. The trade-off is worth it because revision arthroplasty is easier after failed fixation than a primary arthroplasty revised in a young patient.

• Elderly patients (over 75): a lower threshold for arthroplasty in displaced intracapsular fractures. Weigh surgical risk against functional outcome — an ASA 4 patient may be better served by a 30-minute percutaneous screw fixation than a 90-minute hemiarthroplasty. Always set expectations using registry data (30-day mortality near 6.7 percent, 1-year near 30 percent). Timing and medical optimisation. NICE guidelines recommend surgery within 36 hours of admission for a patient who is medically fit — earlier surgery reduces complications and mortality. Optimise in parallel, not serially: anaemia (restrictive transfusion, Hb under 80 g/L or under 90 g/L if symptomatic or with cardiac disease); anticoagulation (reverse warfarin with vitamin K and PCC, hold DOACs per half-life); cardiovascular (rate and rhythm control, continue beta-blockers); fluids and urine output. Do not delay surgery indefinitely for perfect optimisation — most patients benefit from early surgery. Consent specifically for: fixation versus arthroplasty and what drives the choice; AVN (15-33 percent) and nonunion (15-30 percent) risk if fixing a displaced neck fracture; cut-out and revision surgery; mobility expectations; and the realistic mortality figures.

The goal is to reduce the fracture and stabilise it so the patient can mobilise on day one. Two operations share this section: the dynamic hip screw through an open lateral approach (for stable extracapsular fractures), and cannulated screw fixation done percutaneously (for intracapsular fractures). Both begin on a fracture table with image-intensifier control, and both live or die by guide-wire position and the tip-apex distance.

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The exposure: the lateral approach to the proximal femur. The DHS is done through a longitudinal lateral incision. The internervous plane lies between vastus lateralis (femoral nerve, anterior compartment) and the posterior compartment muscles, separated by the lateral intermuscular septum. You elevate vastus lateralis anteriorly off the lateral femoral shaft in a subperiosteal plane to expose the lateral cortex for the plate. The structures you must respect, layer by layer:

Rehabilitation — weight-bearing and recovery | Fixation | Weight-bearing | Milestones | |----------|----------------|------------| | Extracapsular (DHS or nail) | Weight-bearing as tolerated from day 1 | Independent mobilisation before discharge; full function by 3 months | | Intracapsular, elderly | Weight-bearing as tolerated from day 1 | As above | | Intracapsular, young (under 60) | Partial (toe-touch to 50 percent) for 6 weeks, then progress | Protects fixation while the head revascularises; full load by 10-12 weeks | | Arthroplasty | Weight-bearing as tolerated from day 1 (unless perioperative fracture) | As above | Mobilise on day 0 or day 1 — early mobilisation reduces pneumonia, DVT, delirium and pressure sores. Use a multimodal analgesia plan built around scheduled paracetamol and a fascia iliaca block, minimising the opioids that drive delirium in the elderly. Aim for discharge once the patient is medically stable, pain is controlled on oral analgesia, and mobility and a safe home environment (occupational therapy assessment, equipment) are in place. Follow-up. At 2 weeks review the wound and mobility. At 6 weeks take an AP pelvis and lateral hip to assess healing, hardware position and early AVN in intracapsular fractures (advance the young intracapsular patient from partial to full weight-bearing if healing is progressing). At 3 months assess union and watch for AVN (MRI is more sensitive than radiograph). At 12 months confirm union and functional outcome. For every patient, treat the underlying osteoporosis: DEXA, a bisphosphonate (alendronate 70mg weekly or zoledronic acid 5mg yearly, which cuts re-fracture risk by about 40 percent), calcium 1200mg plus vitamin D 800IU daily, and a falls-prevention programme. Venous thromboembolism prophylaxis is mandatory. Give LMWH (enoxaparin 40mg subcutaneously daily) or a DOAC (rivaroxaban 10mg daily, apixaban 2.5mg twice daily) starting 6-12 hours post-op once haemostasis is adequate, continuing for a minimum of 35 days (NICE), alongside mechanical prophylaxis until the patient is mobile. Aspirin alone is inadequate. Complications

Epidemiology. Hip fracture is one of the most common serious injuries of older adults, with a strong female predominance and a peak in the eighth decade and beyond. The major hip-fracture and arthroplasty registries — the UK National Hip Fracture Database (NHFD) and National Joint Registry (NJR), the American Joint Replacement Registry (AJRR), the Australian AOANJRR, and the Swedish (SHAR) and Norwegian registers — consistently report 30-day mortality of roughly 6-8 percent and 1-year mortality of roughly 25-30 percent, and a far lower reoperation rate after hemiarthroplasty than after internal fixation for displaced intracapsular fractures. Garden classification (intracapsular fractures). Garden I and II are undisplaced; III and IV are displaced. It is the displacement — not the stage number — that drives treatment and prognosis, and some Garden I fractures with marked posterior tilt behave as unstable.

AO/OTA classification (extracapsular fractures). 31-A1 is a stable intertrochanteric fracture (intact medial cortex and lesser trochanter) — suit a DHS. 31-A2 is intertrochanteric with posteromedial comminution (a large fragment makes it unstable). 31-A3 is reverse-obliquity or intertrochanteric with subtrochanteric extension — unstable, suit a nail. Subtrochanteric fractures are AO/OTA 32-A, B and C. Pathoanatomy — why the blood supply governs everything. The femoral head is perfused by retinacular arteries that ascend along the neck within the capsule, arising mainly from the medial femoral circumflex artery (about 80 percent) with a contribution from the lateral femoral circumflex (about 20 percent); they enter the head at the head-neck junction, and the artery of the ligamentum teres is a minor contributor in adults. A displaced intracapsular fracture tears these vessels (AVN 15-33 percent); an undisplaced one only kinks them (5-10 percent); an extracapsular fracture leaves them intact (AVN essentially zero). Capsular tamponade from haematoma may compound the ischaemia — the theoretical rationale for capsulotomy, though a clear benefit is unproven. The neck-shaft angle is 125-135 degrees (reducing with age) with 10-15 degrees of anteversion; the calcar femorale is the dense medial buttress whose integrity marks a fracture as stable, and Ward's triangle is an area of relative weakness inferior to the head. Key evidence. The FAITH trial (2017) found no overall difference in 24-month reoperation between sliding hip screw and cannulated screws for femoral neck fractures in patients 50 or older, though AVN was more frequent with the sliding hip screw and selected subgroups (smokers, displaced, base-of-neck) trended toward it. The HEALTH trial (2019) found THR offered at best a marginal functional gain over hemiarthroplasty in fit patients at the cost of higher dislocation. The Norwegian Hip Fracture Register (Gjertsen, 2010) showed reoperation far higher after screw fixation than hemiarthroplasty (22.6 percent versus 2.9 percent) with no mortality difference, cementing arthroplasty as the standard for displaced neck fractures in the elderly. Okike's FAITH secondary analysis (2019) showed posterior tilt of 20 degrees or more doubled conversion to arthroplasty in Garden I-II fractures. Baumgaertner (1995) established the tip-apex distance, the single most important modifiable technical factor in DHS fixation.