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Femoral Neck Fracture - Dynamic Hip Screw (DHS) Fixation

Surgical technique guide for Femoral Neck Fracture - Dynamic Hip Screw (DHS) Fixation - FRCS exam preparation

Core Procedure
intermediate
By OrthoVellum Medical Education Team

Reviewed by OrthoVellum Editorial Team

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High-yield overview

Watson-Jones (anterolateral) or direct lateral approach to proximal femur - internervous plane between tensor fascia lata (superior gluteal nerve, L4-S1) and gluteus medius (superior gluteal nerve) in Watson-Jones, or through gluteus medius splitting in direct lateral | intermediate

Critical Danger Structures - 5 Specific Anatomical Zones

Danger Zone 1: Sciatic Nerve

Location: 12-15cm posterior to greater trochanter at level of lesser trochanter, travels deep to gluteus maximus

Protection: Stay anterior and lateral during dissection, avoid posterior retractor placement beyond 2-3cm posterior to GT

Danger Zone 2: Superior Gluteal Nerve

Location: Exits pelvis above piriformis, 5cm proximal to GT tip, runs between gluteus medius and minimus

Protection: Limit proximal dissection to 5cm above GT tip, incise fascia directly lateral not posterolateral

Danger Zone 3: Femoral Neurovascular Bundle

Location: Anteromedial, 8-10cm anterior to greater trochanter in femoral triangle beneath inguinal ligament

Protection: Stay lateral on femoral shaft, avoid anterior dissection beyond vastus ridge, careful with medial cortical screw measurement

Danger Zone 4: Lateral Femoral Cutaneous Nerve

Location: Subcutaneous, crosses ASIS 2-3cm medial, runs 3-4cm anterior to standard lateral incision

Protection: Keep incision directly lateral centered on GT, avoid anterior extension, meralgia paresthetica if injured

Danger Zone 5: Superior Gluteal Vessels

Location: Exit pelvis with superior gluteal nerve above piriformis, course between gluteal muscles 4-5cm proximal to GT

Protection: Control bleeding immediately if encountered, avoid aggressive proximal dissection, bipolar cautery at low setting

Mnemonic

C-PLATEC-PLATE: DHS Placement Essentials

Mnemonic

SCREW-ITSCREW-IT: DHS Fixation Failure Prevention

Primary Indications for DHS Over Cannulated Screws

Basicervical Femoral Neck Fractures

  • Definition: Fracture at base of femoral neck, immediately proximal to (extracapsular at) the intertrochanteric line
  • Biomechanics: Little/no medial metaphyseal buttress and a short rotationally unstable proximal fragment - behaves between a true femoral neck and an intertrochanteric fracture
  • Failure mechanism: Rotational instability and varus collapse if fixed with cannulated screws alone
  • DHS advantage: Lateral plate provides a buttress against varus collapse; the FAITH RCT (Lancet 2017) found that base-of-neck fractures and smokers were the subgroups most likely to benefit from a sliding hip screw over cancellous screws
  • Caveat: Many surgeons now use a cephalomedullary nail for basicervical patterns because the short, unstable proximal fragment behaves like an unstable trochanteric fracture; DHS remains a valid, widely-taught option

Garden I Fractures in Elderly (Age >65)

  • Rationale: Undisplaced incomplete fractures, alternative to 3 parallel cannulated screws
  • Consideration: DHS if bone quality poor or concern for displacement during screw insertion
  • Evidence: No superiority shown in randomized trials, surgeon preference

Garden II Valgus Impacted Fractures

  • Indication: If choosing fixation over arthroplasty in elderly
  • DHS role: Provides stable fixation with compression for impacted fracture pattern
  • Alternative: Cannulated screws equally effective for true valgus impaction

Failed Previous Screw Fixation

  • Scenario: Cut-out or non-union after cannulated screw fixation
  • DHS use: If adequate bone stock remains and head viable
  • Alternatives: More commonly proceed to arthroplasty if failure occurred

Femoral Neck Fracture with Subtrochanteric Extension

  • Pattern: Combined neck and subtrochanteric component
  • DHS advantage: Long side plate provides fixation for subtrochanteric extension
  • Note: May require additional cerclage wiring or longer plate

Garden Classification Review

Critical Yield Data
Incomplete/Impacted
Complete Undisplaced
Complete Partial Displacement
Complete Total Displacement

Pauwels Classification (Biomechanical)

  • Pauwels I: Angle <30 degrees from horizontal - stable, primarily compression forces
  • Pauwels II: Angle 30-50 degrees - intermediate, mixed compression/shear forces
  • Pauwels III: Angle >50 degrees - unstable, primarily shear forces, high failure risk

Clinical significance: Higher Pauwels angle increases shear forces across fracture, increasing non-union and cut-out risk with any fixation method

Step-by-Step Operative Technique

Step 1: Patient Positioning and Traction Table Setup

Position patient supine on fracture table with well-padded perineal post (check pulse and ensure adequate padding to prevent pudendal nerve injury). Uninjured leg flexed 90 degrees at hip/knee in stirrup holder, abducted to allow C-arm access from opposite side. Injured leg in slight abduction 10-15 degrees, neutral or slight internal rotation (5-10 degrees to correct posterior tilt of femoral head). Apply gentle longitudinal traction to restore length - typically 10-20kg. Image under C-arm AP and lateral to confirm reduction quality before prepping. Arms across chest on arm boards.

Clinical Pearl

Critical Exam Statement: "I position the patient supine on a fracture table with the uninjured leg flexed and abducted in a leg holder to allow C-arm access. The injured leg is in slight abduction and neutral rotation with gentle traction. I obtain AP and lateral fluoroscopic images BEFORE prepping to confirm acceptable reduction - Garden alignment index should show parallel trabeculae on AP (170-180°) and central-neck axis 160-180° on lateral. I ensure the perineal post is well-padded and check distal pulses."

Dangers at this step

  • Perineal post pressure causing pudendal nerve injury or skin breakdown - check pulses, ensure adequate padding, limit traction time
  • Excessive traction causing distraction of fracture or femoral nerve palsy - use minimum traction needed for reduction
  • Lithotomy leg causing peroneal nerve injury on post - pad fibular head well, check foot dorsiflexion
  • Inadequate reduction accepted before prepping - leads to fixation failure, always confirm Garden index first

Step 2: Closed Reduction Assessment

Before prepping, assess reduction quality on AP and lateral fluoroscopy. Apply GARDEN ALIGNMENT INDEX: On AP view, compression trabeculae of head should be parallel to medial cortex of femoral neck (170-180 degrees normal). On lateral view, angle between central axis and neck axis should be 160-180 degrees. Any valgus >180 degrees or varus <160 degrees indicates malreduction. Posterior tilt (Garden lateral angle <160 degrees) is the MOST COMMON malreduction and predicts failure - correct with internal rotation of leg 5-10 degrees. If reduction inadequate, adjust traction/rotation/abduction before starting. Acceptable fracture gap <2-3mm.

Clinical Pearl

Critical Exam Statement: "I assess reduction quality using the Garden alignment index before starting the procedure. On the AP view, the compressive trabeculae should be parallel to the medial cortex showing an angle of 170-180 degrees. On the lateral view, the central trabecular axis to neck axis should be 160-180 degrees. Posterior tilt is the most common malreduction and significantly increases failure risk - I correct this by internally rotating the leg. An acceptable anatomic reduction is absolutely essential before fixation."

Dangers at this step

  • Accepting malreduction (varus <160° or posterior tilt <160°) - increases failure rate to 30-50% vs. 5-10% with anatomic reduction
  • Excessive attempts at closed reduction causing further soft tissue damage - if unable to reduce closed after 3-4 attempts, consider open reduction
  • Not checking lateral view thoroughly - posterior tilt is most commonly missed malreduction
  • Over-distraction with excessive traction - creates gap, prevents compression

Step 3: Skin Incision and Vastus Lateralis Elevation

Make lateral thigh incision centered 2-3cm distal to tip of greater trochanter, 8-10cm long extending distally along femoral shaft axis. Incise skin, subcutaneous tissue sharply. Incise fascia lata/iliotibial band in line with skin incision. Identify vastus lateralis muscle anteriorly - appears as thick muscle belly with longitudinal fibers. Using Cobb elevator or periosteal elevator, elevate vastus lateralis origin from greater trochanter and proximal lateral femur anteriorly - this creates subvastus pocket for DHS barrel plate. Exposure should extend 4-5cm distal to GT tip along lateral femoral shaft. Ensure vastus completely elevated or plate will be proud.

Clinical Pearl

Critical Exam Statement: "I make a lateral incision centered on the greater trochanter, extending 8-10cm distally along the femoral shaft. I incise the fascia lata sharply and identify the vastus lateralis muscle anteriorly. I elevate the vastus lateralis completely off the lateral femur using a Cobb elevator to create a subvastus pocket for the DHS barrel plate. Complete vastus elevation is essential - any soft tissue between the plate and bone will result in the plate sitting proud, creating varus malalignment and patient discomfort."

Dangers at this step

  • Incision too anterior - risks lateral femoral cutaneous nerve (3-4cm anterior to standard incision), causes meralgia paresthetica
  • Incision too proximal/posterior - risks superior gluteal nerve exiting 5cm above GT tip
  • Inadequate vastus elevation - plate won't sit flush, will be proud, causes varus and hardware prominence
  • Excessive posterior dissection beyond 2-3cm - risk to superior gluteal vessels, unnecessary bleeding

Step 4: Guide Wire Placement - MOST CRITICAL STEP

This is the SINGLE MOST IMPORTANT step determining success or failure. Use 135-degree guide (standard DHS angle) with sharp trocar. Entry point on lateral cortex is 2-3cm distal to vastus ridge (vastus tubercle), directly lateral on AP view. Under biplanar fluoroscopy, advance guide wire across fracture into femoral head. Target position: CENTER-CENTER or INFERIOR-CENTER on AP view (within central 'T' formed by head/neck trabecular lines) and CENTER-CENTER on LATERAL view (NEVER posterior). Aim for wire to end 5mm from subchondral bone. Measure tip-apex distance (TAD): sum of distances from tip of guide wire to apex of femoral head on AP and lateral views after correcting for magnification. TAD MUST be <25mm (Baumgaertner criterion). If TAD >25mm or position suboptimal, remove wire and reposition.

Clinical Pearl

Critical Exam Statement: "Guide wire placement is the most critical step - it determines whether the fixation will succeed or fail. I use a 135-degree guide and aim for the INFERIOR-CENTER or CENTER-CENTER position on the AP view, and CENTER-CENTER on the lateral view. Superior or posterior positions dramatically increase cut-out risk. I confirm the tip-apex distance is less than 25mm - Baumgaertner's landmark JBJS study showed that TAD greater than 25mm increases cut-out risk 3-fold. The wire should end within 5mm of subchondral bone but not breach the articular surface."

Dangers at this step

  • Posterior wire position on lateral view - MOST COMMON ERROR, creates eccentric loading, lag screw backs out, cut-out inevitable
  • Superior wire position on AP view - increases cut-out risk 2-4 fold compared to inferior-center position
  • TAD >25mm - 3x increased risk of screw cut-out, unacceptable, must reposition wire
  • Wire too short (<60mm into head) - inadequate purchase in femoral head, cut-out
  • Breach of femoral head articular surface - articular damage, risk of AVN, painful hip
  • Entry point too proximal on lateral cortex - wire trajectory won't reach ideal position in head

Step 5: Length Measurement and Triple Reaming

Measure guide wire length using calibrated measuring device placed over wire (account for magnification). Typical lag screw length 85-100mm depending on femoral head size. Calculate lag screw length: measured wire length minus 5-10mm (to end 5mm from subchondral bone). Use triple reamer over guide wire to create channel for lag screw barrel and threads. Triple reamer has three cutting surfaces: outer reamer for lateral cortex opening, middle reamer for smooth barrel track, inner reamer for distal threads. Ream to depth of measured screw length minus 10mm to protect subchondral bone. Advance reamer steadily watching fluoroscopy. Stop 10mm before planned screw depth. Remove reamer carefully to avoid dislodging guide wire.

Clinical Pearl

Critical Exam Statement: "I measure the guide wire length with a calibrated measuring device, accounting for magnification, then select the appropriate lag screw length - typically 85-100mm to end 5mm from the subchondral surface. I use the triple reamer over the guide wire to create the track for the lag screw. I ream to 10mm less than the measured screw length to protect the subchondral bone - this prevents inadvertent penetration during reaming. I advance the reamer steadily while watching fluoroscopy and maintaining guide wire position."

Dangers at this step

  • Reaming too deep - subchondral breach causing articular damage, AVN risk, lag screw will be too deep
  • Not reaming deep enough - lag screw threads won't fully engage bone, compression inadequate, screw won't advance fully
  • Wire migration or dislodgement during reaming - loss of ideal position, must reposition (common if wire not secure)
  • Eccentric reaming if wire bent - creates oval hole, poor lag screw seating, rotational instability
  • Excessive force during reaming - fracture displacement, wire cut-through

Step 6: Lag Screw Insertion

Remove trocar from guide wire, leaving smooth guide wire in place. Insert DHS lag screw over guide wire using T-handle or power driver with torque limitation. Lag screw has distal threads (engage femoral head/neck bone) and proximal smooth cylindrical shaft (slides in barrel allowing compression). Advance lag screw to measured depth - should end 5mm from subchondral bone on both AP and lateral fluoroscopy. Ensure screw fully seated against lateral cortex - if not flush, may need to ream lateral cortex slightly. Check final position on AP and lateral fluoroscopy: CENTER-CENTER both views, 5mm from subchondral bone, TAD <25mm confirmed. Remove guide wire once lag screw fully inserted and position confirmed satisfactory.

Clinical Pearl

Critical Exam Statement: "I insert the lag screw over the guide wire to the measured depth using a T-handle or low-torque power driver. The lag screw should end within 5mm of the subchondral bone on both AP and lateral views. The distal threads of the lag screw purchase the femoral head and neck bone, while the smooth proximal shaft slides in the barrel to allow compression across the fracture. I confirm ideal position on biplanar fluoroscopy - center-center both views, appropriate depth, TAD confirmed <25mm - before removing the guide wire."

Dangers at this step

  • Screw too long - penetrates subchondral bone, cut-through into joint, articular damage
  • Screw too short - inadequate purchase in femoral head (<60mm), cut-out risk
  • Screw advancement beyond measured depth - can penetrate head if measurement error or reaming too deep
  • Lag screw not fully seated on lateral cortex - proud hardware, barrel won't seat properly, loss of compression
  • Stripping threads during insertion - apply steady pressure, don't over-torque, use T-handle not power driver for final seating

Step 7: Barrel Plate Application

Select appropriate DHS barrel plate - standard has 135-degree barrel angle, side plate typically 4-hole (2-hole or longer variants available). Slide barrel plate over the smooth shaft of lag screw until barrel fully engages lag screw. Plate must sit completely flush on lateral femoral cortex without ANY gap - even 1-2mm gap creates varus moment and stress concentration. If plate proud, further elevate vastus lateralis or remove soft tissue from under plate. Ensure plate aligned parallel to femoral shaft axis. Hold plate firmly against femur with bone-holding forceps or plate-holding clamp. Insert provisional Kirschner wire through distal locking hole to stabilize plate position. Check plate position on AP and lateral fluoroscopy - plate should be centered on lateral cortex, parallel to shaft, barrel fully seated on lag screw.

Clinical Pearl

Critical Exam Statement: "I slide the barrel plate over the lag screw and ensure it sits completely flush on the lateral cortex - any gap will result in varus malalignment, stress concentration, and plate prominence. The barrel must fully engage the smooth shaft of the lag screw to allow the sliding compression mechanism to function. I provisionally fix the plate with a K-wire through the distal hole and confirm position on fluoroscopy before inserting definitive cortical screws. The plate should be parallel to the femoral shaft axis on both AP and lateral views."

Dangers at this step

  • Plate proud (not flush) on lateral cortex - creates varus malalignment, stress riser, prominent hardware, patient discomfort
  • Plate not aligned with femoral shaft axis - creates deformity, abnormal biomechanics
  • Barrel not fully engaged on lag screw shaft - loss of sliding compression mechanism, lag screw can't compress fracture
  • Soft tissue interposition between plate and bone - prevents flush seating, must remove all soft tissue
  • Plate extends too distal - unnecessary stress riser, use shorter plate if able

Step 8: Plate Fixation with Cortical Screws

Insert 4.5mm cortical screws through distal plate holes into femoral shaft. Standard 4-hole DHS plate requires minimum 2 bicortical screws (4 cortices fixation), ideally 3-4 screws. For each screw: (1) Drill both cortices with 3.2mm drill bit, (2) Measure screw length with depth gauge, (3) Tap far cortex if needed (newer screws self-tapping), (4) Insert screw. Screw should engage far cortex fully but not protrude excessively (max 2-3mm beyond far cortex acceptable). Tighten screws sequentially, alternating holes to avoid plate rotation. Hold plate firmly against bone during screw insertion to prevent plate lifting. Verify all screws bicortical on fluoroscopy. Minimum 4 cortices required for adequate stability, prefer 6-8 cortices (3-4 screws).

Clinical Pearl

Critical Exam Statement: "I insert cortical screws through the distal plate holes to secure the plate to the femoral shaft. I use bicortical screw fixation for maximum stability - drill, measure, tap if needed, and insert screws sequentially. At least 4 cortices of fixation are required, but I prefer 3-4 bicortical screws for 6-8 cortices. I check on fluoroscopy to ensure each screw is appropriate length, engages both cortices, and doesn't excessively protrude past the medial cortex. I hold the plate firmly during screw insertion to prevent it lifting off the bone."

Dangers at this step

  • Unicortical screws only - grossly inadequate fixation, plate will fail, varus collapse
  • Screws too long - penetrate medial soft tissues, risk to profunda femoris vessels and perforators (8-10cm anterior/medial to GT)
  • Screws too short - only unicortical purchase, inadequate stability
  • Not tapping hard cortical bone - bone fracture during screw insertion, screw stripping
  • Plate not held firmly during screw insertion - plate lifts off cortex, screws don't compress plate to bone
  • Excessive screw protrusion medially (>5mm) - soft tissue irritation, vascular injury risk

Step 9: Compression Screw Application

Insert compression screw through barrel plate into the back of the lag screw using hexagonal screwdriver. The compression screw is a set screw that advances the lag screw further into the femoral head while the barrel (which is now fixed to the femoral shaft by the plate screws) stays stationary. This creates INTERFRAGMENTARY COMPRESSION across the fracture site. Turn compression screw clockwise while watching fluoroscopy - should see fracture gap progressively close. Typically 2-3 full turns of compression screw achieves adequate compression. Watch for: (1) Fracture gap closure on fluoroscopy, (2) Lag screw advancing 2-3mm further into head, (3) No over-compression causing distraction or head impaction. Stop when fracture gap closed and adequate compression achieved. Do NOT over-tighten.

Clinical Pearl

Critical Exam Statement: "I insert the compression screw through the barrel plate into the lag screw, which creates interfragmentary compression across the fracture site. I watch on fluoroscopy as I turn the compression screw - typically 2-3 turns is adequate. I see the fracture gap close and the lag screw advance slightly further into the femoral head. Compression improves biomechanical stability and promotes healing by converting shear forces to compression forces. I'm careful not to over-compress, which could drive the lag screw through the femoral head or cause distraction."

Dangers at this step

  • Over-compression - can cause excessive lag screw advancement, drive screw through femoral head, or create distraction if comminution present
  • Inadequate compression - fracture gap remains, increased non-union risk, shear forces not converted to compression
  • Compression screw not fully engaged in lag screw - loss of compression mechanism, screw backs out
  • Compression applied before plate firmly fixed to shaft - plate shifts position during compression
  • Compression causing fracture displacement - stop immediately, may indicate comminution or malreduction

Step 10: Anti-Rotation Screw (For Basicervical Fractures)

For basicervical fractures specifically, consider adding an ANTI-ROTATION SCREW to prevent rotation of femoral head fragment on the lag screw. Use 6.5mm or 7.3mm partially threaded cancellous screw. Place second guide wire parallel to lag screw, positioned 1-1.5cm superior or inferior (superior preferred if room). Ensure anti-rotation wire also in center-center position on lateral view. Measure wire length (should match lag screw depth - 5mm from subchondral bone). Drill, measure, and insert anti-rotation screw to same depth as lag screw. Critical: Anti-rotation screw must NOT block the lag screw sliding mechanism - ensure adequate spacing (1-1.5cm minimum). Anti-rotation screw increases rotational stability, particularly important in basicervical patterns. Confirm position on final fluoroscopy.

Clinical Pearl

Critical Exam Statement: "For basicervical femoral neck fractures specifically, I add an anti-rotation screw parallel to the lag screw to prevent rotation of the femoral head fragment. This is a 6.5mm or 7.3mm cancellous screw placed 1-1.5cm superior to the lag screw. The anti-rotation screw significantly increases rotational stability, which is the key concern in basicervical fracture patterns. I ensure the anti-rotation screw doesn't block the lag screw sliding mechanism by maintaining adequate spacing and confirming both screws can slide independently."

Dangers at this step

  • Anti-rotation screw too close to lag screw - blocks sliding mechanism, defeats entire DHS principle
  • Poor positioning of anti-rotation screw (posterior or superior) - ineffective rotational control or increased AVN risk
  • Over-convergence of screws - crowding femoral head, increased AVN risk, inadequate bone between screws
  • Anti-rotation screw too long - penetrates femoral head articular surface
  • Anti-rotation screw in posterior position - eccentric loading, same problems as posterior lag screw

Step 11: Final Fluoroscopic Assessment and Traction Release

Obtain final high-quality AP and true lateral fluoroscopy images. Systematically verify: (1) Lag screw position CENTER-CENTER both views, within 5mm of subchondral bone, not penetrating. (2) Tip-apex distance confirmed <25mm. (3) Plate completely flush on lateral cortex, parallel to femoral shaft. (4) All cortical screws bicortical with appropriate length. (5) Compression achieved - fracture gap closed or <2mm. (6) No penetration of femoral head on any view. (7) Reduction maintained - Garden alignment index 160-180° on both views. (8) If anti-rotation screw used, confirm parallel to lag screw and adequate spacing. Release traction slowly while maintaining reduction with bone hook if needed. Recheck reduction on fluoroscopy after traction release - should be maintained. Save final images for documentation.

Clinical Pearl

Critical Exam Statement: "I obtain final fluoroscopic images in orthogonal AP and true lateral views to systematically verify the key quality indicators: lag screw position in the center of the femoral head on both views within 5mm of subchondral bone, tip-apex distance confirmed under 25mm, plate flush on lateral cortex, all screws bicortical, compression achieved, and maintenance of acceptable reduction with Garden alignment index 160-180°. TAD less than 25mm is the single most important predictor of fixation success according to Baumgaertner's landmark study. I release traction slowly and recheck the reduction to ensure it's maintained."

Dangers at this step

  • Accepting TAD >25mm on final films - 3x increased cut-out risk, should revise if identified
  • Missing subchondral penetration on lateral view - will cause early failure and pain
  • Not obtaining true lateral view - posterior malposition missed
  • Releasing traction before confirming final satisfactory position - may lose reduction
  • Not checking for loss of reduction after traction release - fracture can displace when traction released
  • Inadequate final image quality - can't assess TAD or screw position accurately

Step 12: Wound Closure and Dressing

Thoroughly irrigate wound with minimum 3 liters normal saline using pulsatile lavage. Achieve meticulous hemostasis with bipolar electrocautery. Close in layers: (1) Repair vastus lateralis to its origin over the plate when possible using absorbable suture - reduces plate prominence and protects hardware. (2) Close fascia lata/ITB securely with strong absorbable suture (e.g., No. 1 Vicryl) using interrupted or running locked technique - this is load-bearing layer. (3) Subcutaneous layer with 2-0 or 3-0 absorbable suture to eliminate dead space. (4) Skin closure with staples or 3-0 nylon interrupted sutures. Apply sterile absorbent dressing. Drain not routinely required for DHS unless significant oozing despite hemostasis - if used, place 10-12Fr closed suction drain deep to fascia, exit posteriorly.

Clinical Pearl

Critical Exam Statement: "I irrigate the wound copiously with at least 3 liters of normal saline and achieve meticulous hemostasis. I close in layers, repairing the vastus lateralis over the plate when possible to reduce hardware prominence and provide soft tissue coverage. I close the fascia lata securely as this is the load-bearing layer. Skin closure with staples or interrupted sutures. A drain is not routinely required for DHS fixation unless there's significant ongoing bleeding despite hemostasis. Post-operatively, the patient can mobilize touch weight-bearing or partial weight-bearing depending on fracture pattern, bone quality, and stability of fixation."

Dangers at this step

  • Inadequate fascial closure - wound dehiscence, plate prominence, abductor weakness
  • Skin closure under tension - skin necrosis, wound breakdown (consider delayed closure if severe swelling)
  • Hematoma formation from inadequate hemostasis - infection risk, wound complications
  • Dead space not eliminated - seroma formation, infection risk
  • Not repairing vastus over plate - prominent hardware, patient discomfort

Complications - Recognition and Management

DHS Fixation Complications - Comprehensive Management

Post-operative Care Protocol

Immediate Post-operative (0-2 weeks)

  • Radiographs: Immediate post-op AP and lateral pelvis/hip to document hardware position and reduction
  • DVT prophylaxis: LMWH (e.g. enoxaparin 40mg SC daily) is standard; most major guidelines (NICE, AAOS, ACCP) recommend extended pharmacological prophylaxis after hip fracture surgery, commonly continued for up to 28-35 days
  • Analgesia: Multimodal - paracetamol 1g QDS regular, oxycodone 5-10mg Q4-6H PRN, avoid NSAIDs first 6 weeks (impair fracture healing)
  • Mobilization: Day 1 with physiotherapy - sit out of bed, transfer to chair
  • Weight-bearing: TOUCH weight-bearing (foot flat on ground, no push-off) for 6-8 weeks with walking frame

Early Post-operative (2-6 weeks)

  • Review: Clinic at 2 weeks - wound check, radiographs AP/lateral, assess mobilization
  • Weight-bearing: Continue touch weight-bearing with frame, progress to partial weight-bearing (20-30kg) at 4-6 weeks if radiographic healing progressing
  • Physiotherapy: Hip ROM exercises (avoid forced internal rotation/adduction initially), abductor strengthening, gait re-education
  • DVT prophylaxis: Continue LMWH until 6 weeks post-op

Intermediate Post-operative (6-12 weeks)

  • Review: Clinic at 6 weeks with radiographs
  • Radiographic assessment: Look for callus formation, no loss of reduction, hardware position maintained, no AVN signs
  • Weight-bearing: Progress to weight-bearing as tolerated (WBAT) if callus visible, no pain with partial WB
  • For basicervical fractures: May allow earlier progression due to better stability from DHS
  • Physiotherapy: Progress to full ROM, strengthening, ambulation without aids

Late Post-operative (3-6 months)

  • Review: Clinic at 3 months with radiographs
  • Union assessment: Bridging callus on 3 cortices, no pain with full weight-bearing, fracture line fading
  • Weight-bearing: Full unrestricted weight-bearing typically by 10-12 weeks if radiographic union
  • Return to activities: Progress as tolerated based on bone quality and healing

Long-term Follow-up (6-24 months)

  • Review: 6 months, 12 months, then discharge if healed
  • AVN surveillance: MRI at 12-24 months if any symptoms (groin pain, limited ROM) - AVN can present up to 3 years post-injury
  • Radiographs: AP/lateral at each visit to assess for late AVN, hardware issues
  • Osteoporosis management: DEXA scan, bisphosphonates (alendronate 70mg weekly) or denosumab (60mg SC 6-monthly) per endocrine guidelines
  • Hardware removal: Only if symptomatic prominence after confirmed union (>12 months)

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"Walk me through your decision-making for a 68-year-old with a basicervical femoral neck fracture. Why would you choose DHS over cannulated screws?"

PRACTICAL APPROACH
A basicervical femoral neck fracture is a specific fracture pattern that occurs at the base of the femoral neck, just proximal to the intertrochanteric line. This fracture has NO metaphyseal support because it's essentially at the neck-shaft junction. Biomechanically, basicervical fractures behave more like unstable intertrochanteric fractures than typical femoral neck fractures - they're subjected to high varus forces and shear stresses. For this fracture pattern, I would choose a DHS over cannulated screws for several key reasons: First, BIOMECHANICAL SUPERIORITY: The DHS provides a lateral buttress plate that resists varus collapse. Basicervical fractures have no medial calcar support, making them prone to varus deformity if fixed with screws alone. The side plate of the DHS directly resists this varus moment. Second, CLINICAL EVIDENCE: In the FAITH randomised controlled trial (Lancet 2017), the sliding hip screw showed no overall reoperation advantage over cancellous screws across all hip fractures, BUT the pre-specified subgroups of base-of-neck (basicervical) fractures and smokers were the ones that appeared to benefit from the sliding hip screw - which is exactly the pattern in front of us. The trade-off to disclose is that avascular necrosis was slightly more common with the sliding hip screw in that trial. Third, SLIDING MECHANISM: The DHS allows controlled compression across the fracture site as the patient loads the hip, converting shear forces into compression forces which promote healing. Fourth, ROTATION CONTROL: I would add an anti-rotation screw parallel to the lag screw, positioned 1-1.5cm superior, to prevent rotation of the proximal fragment - this is particularly important in basicervical patterns. The key technical points for DHS in basicervical fractures are: (1) Anatomic reduction - Garden alignment index 160-180 degrees on both views, (2) Guide wire position inferior-center or center-center on AP, center-center on lateral, (3) Tip-apex distance <25mm - Baumgaertner criterion, (4) Plate flush on lateral cortex, (5) Anti-rotation screw for added stability, and (6) Adequate compression with the compression screw. For this 68-year-old patient, if the fracture is displaced (Garden III/IV), I would actually consider arthroplasty (hemiarthroplasty or THA) as an alternative, but if we're proceeding with fixation for an undisplaced basicervical pattern, DHS is clearly superior to cannulated screws.
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"Explain tip-apex distance. Why is it important and how do you achieve TAD less than 25mm?"

PRACTICAL APPROACH
Tip-apex distance, or TAD, is the single most important technical predictor of DHS fixation success or failure. It was defined and validated by Baumgaertner in his landmark JBJS study in 1995. TAD is calculated as follows: It's the SUM of two distances - the distance from the tip of the lag screw to the apex of the femoral head on the AP view PLUS the distance from the tip to the apex on the lateral view, after correcting for magnification. Both measurements are made on the same radiograph using the calibration marker. Baumgaertner's study analyzed 198 peritrochanteric fractures treated with sliding hip screws. The mean TAD was 24mm in the fractures that healed successfully compared with 38mm in those where the screw cut out, and most strikingly NONE of the 120 screws with a TAD of 25mm or less cut out. The relationship between increasing TAD and cut-out held regardless of all other fracture and patient variables. Subsequent studies have validated TAD as a key predictor of failure. The reason TAD is so critical relates to BIOMECHANICS: A higher TAD means the lag screw tip is further from the center of the femoral head. The femoral head loads eccentrically during weight-bearing - forces concentrate at the superior and posterior aspects. If the screw tip is too far from the apex (high TAD), these eccentric forces create a moment arm that tends to rotate and migrate the screw superiorly out of the head - this is the cut-out mechanism. To achieve TAD less than 25mm, I focus on GUIDE WIRE POSITION: First, on the AP VIEW: I place the wire in the INFERIOR-CENTER or CENTER-CENTER position. Superior position dramatically increases TAD and cut-out risk. The ideal is inferior-center because this provides the lowest TAD while maintaining adequate purchase. Second, on the LATERAL VIEW: The wire MUST be CENTER-CENTER. Posterior position is the most common error - this increases TAD and creates eccentric loading leading to screw back-out. Third, DEPTH: The wire should advance to within 5mm of the subchondral bone - not breaching the articular surface but close enough to maximize purchase and minimize TAD. Fourth, I MEASURE TAD intraoperatively using the fluoroscopy calibration before reaming. If my guide wire position would result in TAD greater than 25mm, I remove the wire and reposition it before proceeding. It's much easier to correct at the wire stage than after the lag screw is inserted. Finally, VERIFICATION: On final fluoroscopy, I confirm TAD is under 25mm by measuring on the saved images. If it's above 25mm, I would strongly consider revising the fixation because the failure risk is unacceptably high.
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"Describe the Garden alignment index. What does it assess and what are acceptable values?"

PRACTICAL APPROACH
The Garden alignment index is a radiographic assessment tool used to evaluate the QUALITY OF REDUCTION of a femoral neck fracture before and after fixation. It was described by Garden in 1961 and remains the gold standard for assessing reduction quality. The Garden index recognizes that anatomic reduction is essential for successful fixation - malreduction is one of the most common preventable causes of fixation failure. The Garden alignment index is assessed on TWO orthogonal views: On the AP VIEW: I assess the alignment of the compressive trabeculae. The compressive trabeculae are the trabecular lines that run from the medial cortex of the femoral neck up into the femoral head - these are the primary weight-bearing trabeculae. In anatomic reduction, these trabeculae should be PARALLEL to the medial cortex of the femoral neck. The angle formed is measured as the Garden alignment angle - normal is 170 to 180 degrees. Varus malreduction shows an angle less than 160 degrees. Valgus malreduction shows an angle greater than 180 degrees. Either deviation from 160-180 degrees indicates malreduction. On the LATERAL VIEW: I assess the alignment between the central trabecular line of the femoral head and the axis of the femoral neck. In anatomic reduction, this angle should be 160 to 180 degrees. The most common malreduction on the lateral view is POSTERIOR TILT, where the femoral head is tilted posteriorly relative to the neck - this shows as an angle less than 160 degrees on the lateral view. The clinical significance is profound: Studies have shown that malreduction (Garden index outside 160-180 degrees on either view) increases the failure rate to 30-50%, compared to 5-10% with anatomic reduction. This is because malreduction creates eccentric loading and abnormal forces across the fixation, promoting cut-out and non-union. POSTERIOR TILT is the most commonly MISSED malreduction because surgeons often focus on the AP view and neglect the lateral. Posterior tilt is corrected by INTERNALLY ROTATING the leg on the fracture table 5-10 degrees before fixation. I assess the Garden alignment index BEFORE I start the procedure - on the initial fluoroscopy after applying traction to the fracture table. If the Garden index is not 160-180 degrees on both views, I adjust the traction, rotation, and position BEFORE prepping and starting the case. Accepting malreduction is a preventable error that dramatically increases failure risk. After fixation, I recheck the Garden alignment index on final fluoroscopy to confirm anatomic reduction has been maintained throughout the procedure. Sometimes reduction can be lost during fixation, particularly when inserting the guide wire or applying compression.

DHS Femoral Neck Fixation - Exam Day Summary

Clinical summary

References

  1. Baumgaertner MR, Curtin SL, Lindskog DM, Keggi JM. The value of the tip-apex distance in predicting failure of fixation of peritrochanteric fractures of the hip. J Bone Joint Surg Am. 1995;77(7):1058-1064. doi:10.2106/00004623-199507000-00012

  2. Garden RS. Low-angle fixation in fractures of the femoral neck. J Bone Joint Surg Br. 1961;43-B:647-663.

  3. Haidukewych GJ, Rothwell WS, Jacofsky DJ, Torchia ME, Berry DJ. Operative treatment of femoral neck fractures in patients between the ages of fifteen and fifty years. J Bone Joint Surg Am. 2004;86(8):1711-1716. doi:10.2106/00004623-200408000-00015 (PMID 15292419)

  4. Palm H, Gosvig K, Krasheninnikoff M, Jacobsen S, Gebuhr P. A new measurement for posterior tilt predicts reoperation in undisplaced femoral neck fractures: 113 consecutive patients treated by internal fixation and followed for 1 year. Acta Orthop. 2009;80(3):303-307. doi:10.3109/17453670902967281 (PMID 19634021)

  5. Garden RS. Reduction and fixation of subcapital fractures of the femur. Orthop Clin North Am. 1974;5(4):683-712. (Garden alignment index)

  6. Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) Investigators. Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial. Lancet. 2017;389(10078):1519-1527. doi:10.1016/S0140-6736(17)30066-1 (PMID 28262269)

  7. Matre K, Havelin LI, Gjertsen JE, Vinje T, Espehaug B, Fevang JM. Sliding hip screw versus IM nail in reverse oblique trochanteric and subtrochanteric fractures. A study of 2716 patients in the Norwegian Hip Fracture Register. Injury. 2013;44(6):735-742. doi:10.1016/j.injury.2012.12.010 (PMID 23305689)

  8. National Institute for Health and Care Excellence (NICE). Hip fracture: management. NICE guideline NG124. London: NICE.

  9. American Academy of Orthopaedic Surgeons (AAOS). Management of Hip Fractures in Older Adults: Evidence-Based Clinical Practice Guideline. Rosemont, IL: AAOS.