Posteromedial Approach to Knee

Primary Indications - Trauma

Posteromedial Tibial Plateau Fractures

• Schatzker Type IV: Medial plateau fracture with posteromedial extension
• Coronal split fractures involving posterior medial plateau
• Failed reduction via anteromedial approach (posterior fragment not accessible)
• Bicondylar fractures (Schatzker V, VI) with significant posteromedial component

Posteromedial Corner Injuries

• Avulsion fractures of semimembranosus insertion
• Posterior oblique ligament (POL) repair
• Posteromedial capsular injuries
• Combined ligamentous reconstructions

Secondary Indications

Meniscal Pathology

• Posterior medial meniscus root tear (open repair)
• Peripheral posterior horn tear requiring inside-out repair
• Meniscus transplantation (medial)

Vascular Access

• Popliteal vessel exploration (in combination with vascular surgery)
• Repair of iatrogenic popliteal vessel injury

Contraindications

Absolute

• Active infection overlying incision site
• Severe vascular compromise (requires vascular surgery first)

Relative

• Severe peripheral vascular disease (high vessel injury risk)
• Severe soft tissue injury (compartment syndrome, extensive degloving)
• Obesity (BMI greater than 40) - very difficult exposure

Clinical Assessment

History and Mechanism

• High-energy trauma pattern (MVA, fall from height, pedestrian struck)
• Varus force mechanism (medial plateau fractures)
• Combined injury patterns
• Vascular injury symptoms (pain, pallor, pulselessness)

Physical Examination - CRITICAL

• Neurovascular exam MANDATORY:
  • Dorsalis pedis and posterior tibial pulses
  • Capillary refill
  • Ankle-brachial index (ABI) if pulses diminished
  • Saphenous nerve function (sensation medial leg/foot)
• Compartment assessment (high-energy injuries)
• Soft tissue envelope (open vs closed)
• Knee stability (medial, posterior)

Imaging Protocol

Standard Radiographs

• AP and lateral knee
• Oblique views (posteromedial plateau visualization)
• Traction views if comminuted

CT Imaging - MANDATORY

• Fine-cut (1mm) CT with 3D reconstruction
• Critical assessments:
  • Fracture pattern (coronal split, depression)
  • Posterior extension (need posteromedial approach?)
  • Articular step-off and comminution
  • Safe screw corridors

CT Angiography - Consider If

• Diminished pulses
• High-energy mechanism
• Severe displacement
• Identifies vascular injury before surgery

MRI - Selected Cases

• Ligamentous injury assessment (POL, MCL, PCL)
• Meniscal pathology evaluation

Surgical Planning

Approach Selection

• Isolated posteromedial fracture: posteromedial alone (rare)
• Bicondylar fracture: dual approach (anteromedial + posteromedial, or anterolateral + posteromedial)
• Timing: staged vs same-day dual approach

Fixation Strategy

• Posteromedial buttress plate (most common)
• Lag screws from posteromedial to anterolateral
• Combined with anterior plate for bicondylar patterns

Team Planning

• Vascular surgery on standby (popliteal vessel risk)
• Extensile exposure preparation (may need to extend)

Standard Equipment

Basic Instruments

• Trauma set with heavy retractors
• Self-retaining retractors (bent Hohmann)
• Periosteal elevators
• Pointed reduction forceps
• Electrocautery

Fracture Fixation

• Posteromedial tibial plateau plates (anatomic pre-contour)
• 3.5mm cortical and cannulated screws
• 4.0mm and 6.5mm cannulated screws (lag screw options)
• K-wires (provisional fixation)
• Bone graft instruments (if needed)

Vascular Instruments - HAVE AVAILABLE

• Vascular clamps
• Vessel loops
• Fine vascular instruments

Fluoroscopy

Essential - Large C-Arm

• Must obtain good AP, lateral, and oblique views
• Difficult in prone position (limited angulation)
• Radiolucent table critical

Option 1: Prone Positioning

Advantages

• Direct access to posteromedial corner
• Easier dissection (gravity-assisted)
• Good for isolated posteromedial fractures

Disadvantages

• Cannot combine with anterior approach in same sitting
• Fluoroscopy more difficult
• Patient repositioning needed if conversion to anterior

Positioning Technique

• Standard prone on chest rolls or Wilson frame
• Leg slightly internally rotated
• Bump under distal thigh (knee flexion 20-30 degrees)
• Ensure adequate padding

Option 2: Supine with Leg Hanging

Advantages

• Allows staged anterior and posterior approaches same day
• Easier fluoroscopy
• Easier conversion to anterior if needed

Disadvantages

• Gravity works against you (medial structures sag away)
• Requires assistant to hold leg
• Cramped working space

Positioning Technique

• Supine on OR table
• Leg hanging off side of table at knee level
• Knee flexed 90 degrees
• Assistant holds leg or use leg holder

Tourniquet Considerations

Advantages

• Bloodless field for dissection
• Better visualization of posterior capsule

Disadvantages

• Can miss vascular injury (don't deflate until before closure)
• Limits working time (2 hours max)

Recommendation

• Use tourniquet but deflate periodically to check for bleeding
• Have low threshold to deflate if vascular injury suspected

Bony Landmarks

Palpable Posterior Medial Anatomy

• Medial femoral epicondyle (proximal landmark)
• Adductor tubercle (posterior superior medial femur)
• Posteromedial tibial margin (palpable border)
• Medial tibial plateau (target area)

Neurovascular Anatomy - CRITICAL

Popliteal Artery and Vein

• Location: In the floor of the popliteal fossa, immediately deep and posterior to the popliteus and the posterior capsule of the proximal tibia. The artery lies deepest (closest to bone), the vein superficial to it, with the tibial nerve most superficial of the three
• At risk: Dissection carried lateral to the gastrocnemius-semimembranosus interval, aggressive deep retraction, and a drill or screw exiting the far (anterior) cortex into the fossa
• Course: Descends through the popliteal fossa and divides into anterior tibial artery and tibioperoneal trunk at the inferior border of popliteus
• Protection: Retract the medial head of gastrocnemius laterally so it interposes between the field and the bundle, stay strictly subperiosteal on the posterior tibial cortex, avoid blind deep dissection toward the floor of the fossa, and control screw length

Tibial Nerve

• Runs in the floor of the popliteal fossa, superficial to the popliteal vein and artery
• Shielded when the medial head of gastrocnemius is retracted laterally
• Usually safe provided the gastrocnemius-semimembranosus interval is respected and lateral dissection is avoided

Saphenous Nerve

• Superficial nerve running with great saphenous vein
• Exits adductor canal posteromedial to knee
• At risk: Proximal skin incision, subcutaneous dissection
• Injury: Medial leg and foot numbness

Common Peroneal Nerve

• Wraps around fibular neck laterally
• Not at risk with posteromedial approach (too lateral)

Ligamentous and Capsular Anatomy

Posteromedial Corner Structures

• Posterior oblique ligament (POL): Thickening of posteromedial capsule
• Semimembranosus tendon: Inserts on posteromedial tibia
  • Five arms: direct, reflected, popliteal, capsular, oblique
• Posterior horn medial meniscus: Attached to posterior capsule

Superficial Medial Collateral Ligament

• Anterior to surgical interval
• Usually not encountered unless injury extends anteriorly

Muscular Anatomy

Medial Head of Gastrocnemius

• Lateral boundary of approach
• Origin: Posterior medial femoral condyle
• Protects tibial nerve posteriorly

Semimembranosus

• Medial boundary of approach
• Insertion: Posteromedial tibia (five-arm complex)
• Posterior to pes anserinus

Popliteus

• Originates lateral femoral condyle
• Inserts posterior proximal tibia
• Forms floor of popliteal fossa
• Overlies popliteal vessels

Step 1: Skin Incision

Incision Planning

• Longitudinal incision over posteromedial tibia
• Proximal extent: Medial femoral epicondyle
• Distal extent: 6-8cm distal to joint line
• Length: 8-12cm depending on exposure needs

Skin Incision

• Curvilinear, slightly posterior to medial midline
• Sharp dissection through skin and subcutaneous tissue
• Identify and protect saphenous vein and nerve if encountered

Hemostasis

• Electrocautery for subcutaneous vessels
• Preserve saphenous vein if possible (collateral drainage)

Step 2: Identify Anatomic Interval

Palpate Key Structures

• Medial head of gastrocnemius (lateral, feels like muscle belly)
• Semimembranosus tendon (medial, feels cord-like)
• Interval between them (natural plane)

Superficial Dissection

• Incise fascia overlying gastrocnemius and semimembranosus
• Develop plane between muscles using blunt dissection
• Separate muscles with retractors

Deep Dissection

• Continue dissection toward posterior capsule
• Stay on bone (subperiosteal) to avoid vascular structures
• Posterior capsule becomes visible

Step 3: Capsular Exposure and Opening

Expose Posterior Capsule

• Retract gastroc laterally (tibial nerve protected behind it)
• Retract semimembranosus medially
• Posterior capsule exposed

Capsular Incision

• Incise posterior capsule longitudinally
• Stay directly on bone (avoid anterior dissection)
• Expose posterior aspect of medial tibial plateau

Joint Assessment

• Visualize posteromedial articular surface
• Assess fracture pattern (coronal split, depression)
• Palpate for posterior meniscus tear

Step 4: Fracture Reduction

Assess Fracture Pattern

• Coronal split (most common posteromedial pattern)
• Posterior depression
• Comminution

Reduction Techniques

Option 1: Direct Manipulation

• Use reduction forceps to compress split fragments
• Pry depressed fragments upward from posterior

Option 2: Anterior Approach First

• If combined with anterior approach, reduce from anterior first
• Then secure posterior fragment from posteromedial

Option 3: Joystick Technique

• Place K-wire or small Schanz pin in posterior fragment
• Use as joystick to manipulate fragment

Provisional Fixation

• K-wires to hold reduction
• Verify on fluoroscopy (AP, lateral, oblique)

Critical Point: Screw Direction

• Screws from a posteromedial plate aim anterolaterally to capture the opposite cortex and support the articular fragment
• Control screw length so the drill and screw do not plunge uncontrolled through the far cortex
• Confirm trajectory and length on fluoroscopy before committing each screw

Step 5: Definitive Fixation

Posteromedial Buttress Plate

• Select appropriate posteromedial plate (anatomic pre-contour)
• Position plate on posteromedial tibia
  • Proximal: Just distal to joint line
  • Aligned with posterior tibial border
• Confirm position with fluoroscopy

Screw Insertion

• Proximal screws (subchondral support):
  • Aim anterolaterally (NOT anterior)
  • Locking screws preferred
  • Measure carefully (fluoroscopy confirmation)
  • Bicortical ONLY if absolutely safe trajectory
• Distal screws (diaphyseal purchase):
  • Bicortical screws
  • 3-4 screws distal to fracture

Alternative: Lag Screws Only

• If simple coronal split fracture
• Lag screws from posteromedial to anterolateral
• Typically 6.5mm partially threaded cannulated screws
• Compression across split

Ligamentous Repair (If Needed)

• Repair avulsed semimembranosus if present
• Repair POL capsular tears
• Suture meniscal root tears

Step 6: Final Assessment

Fluoroscopic Verification

• AP, lateral, oblique views
• Confirm reduction (less than 2mm step-off)
• Confirm no anterior cortex penetration
• Assess alignment

Stability Testing

• Gentle ROM through flexion/extension
• Assess varus/valgus stability
• Check for gapping

Step 7: Closure

Capsular Repair

• Re-approximate posterior capsule with 0 or #1 Vicryl
• Watertight closure (reduce hemarthrosis)

Muscular Layer

• Allow gastrocnemius and semimembranosus to fall back together
• No need to suture muscles (interval approach)

Fascial Closure

• Close fascia with #1 Vicryl

Drain Placement

• Consider deep drain (10Fr Blake)
• Remove when output less than 30mL/24hrs

Subcutaneous and Skin

• 2-0 Vicryl subcutaneous
• 3-0 nylon or staples for skin

Intraoperative Complications

Popliteal Vessel Injury (Most Feared - rare in reported series but catastrophic)

• Mechanism:
  • Uncontrolled drill plunge or over-long screw breaching the far cortex into the fossa
  • Direct injury during deep or lateral dissection toward the floor of the fossa
  • Retractor injury to the bundle
• Recognition: Sudden hemorrhage, expanding hematoma, loss of distal pulses
• Management:
  • Direct pressure
  • Call vascular surgery IMMEDIATELY
  • Proximal and distal control if possible
  • Repair vs bypass depending on injury

Tibial Nerve Injury (Less than 1%)

• Lateral retraction of gastrocnemius
• Prevention: Gentle retraction, identify nerve course
• Management: Release retraction, document

Saphenous Nerve Injury (5-10%)

• Subcutaneous dissection
• Result: Medial leg/foot numbness
• Prevention: Careful superficial dissection
• Often unavoidable - counsel patient preoperatively

Early Postoperative Complications

Compartment Syndrome (5-10% in high-energy injuries)

• High index of suspicion
• Frequent neuro-vascular checks
• Management: Immediate fasciotomy if suspected

Occult Vascular Injury

• May not be apparent intraoperatively if tourniquet used
• Present postop with ischemia, delayed hematoma
• Prevention: Deflate tourniquet before closure, check pulses
• Management: CT angiography, vascular surgery consult

Wound Complications

• Hematoma: Common due to posterior approach
• Infection: Less than 2%
• Prevention: Drain placement, hemostasis

Late Complications

Post-traumatic Arthritis (20-30%)

• Despite anatomic reduction
• Risk factors: articular comminution, meniscectomy

Malunion

• From inadequate reduction
• Causes varus instability, medial pain

Hardware Prominence

• Posteromedial plate palpable
• May require removal (10-15% of cases)

Chronic Pain and Stiffness

• Extensive soft tissue dissection
• Prolonged immobilization

Immediate Care (0-48 hours)

Neurovascular Monitoring - CRITICAL

• Check pulses, capillary refill, sensation every 1-2 hours
• Compartment checks (pain, tightness, passive stretch pain)
• Have low threshold for CT angiography if any concern

Positioning

• Leg elevated
• Knee immobilizer or hinged brace locked in extension

Pain Management

• Multimodal analgesia
• Avoid femoral nerve block (masks compartment syndrome)
• Regional anesthesia OK but monitor closely

Drain Management

• Remove when output less than 30mL/24hrs (typically 48hrs)

Weight-Bearing Protocol

Simple Fractures (Isolated Posteromedial)

• Toe-touch weight-bearing (TTWB) 6-8 weeks
• Progressive weight-bearing 8-10 weeks
• Full weight-bearing 10-12 weeks

Complex/Bicondylar Fractures

• Non-weight-bearing (NWB) 8-12 weeks
• Very gradual progression based on healing

ROM Protocol

Week 0-2

• Knee immobilizer, gentle passive ROM to 60 degrees
• Avoid varus stress (protects medial fixation)

Week 2-6

• Progress ROM to 90 degrees
• Active-assisted ROM

Week 6+

• Unrestricted ROM exercises
• Strengthening (quad, hamstrings)

Radiographic Follow-up

2 Weeks: AP, lateral, oblique - assess reduction, hardware 6 Weeks: Repeat films before increasing weight-bearing 12 Weeks: Assess union (3 of 4 cortices healed) 6 Months, 1 Year: Long-term assessment for arthritis

Physical Therapy

Phase 1 (0-6 weeks): Protection, gentle ROM Phase 2 (6-12 weeks): Progressive strengthening, weight-bearing advancement Phase 3 (12+ weeks): Functional restoration, sport-specific training

Return to Activity

Sedentary Work: 8-12 weeks Light Labor: 12-16 weeks Heavy Labor: 4-6 months Contact Sports: 6-9 months Full Activities: 6-12 months

The posteromedial (Lobenhoffer) approach is a specialised, high-risk exposure reserved for surgeons experienced in periarticular trauma, and the principles below are consistent across major global trauma bodies. There is no single national standard exam candidates are expected to quote; the convergent message is CT-driven planning, fragment-specific exposure and a posterior buttress for the unstable posteromedial fragment.

CT-based, column/segment-driven planning

Registry and outcome context

Plateau fractures are predominantly a fracture/ORIF problem rather than an implant-survivorship one, so national arthroplasty registries (NJR, AJRR, AOANJRR, SHAR, NZJR) are most relevant for the downstream end-point of post-traumatic arthritis. Registry and cohort data consistently report that high-energy bicondylar plateau fractures carry a substantial long-term risk of post-traumatic osteoarthritis and a measurable conversion rate to total knee arthroplasty, with younger trauma patients over-represented among early TKA conversions. This underpins the emphasis on anatomic articular reduction (2mm or less step/gap) at the index operation.

Areas of genuine practice variation

• Staging: For bicondylar patterns many units stage fixation (temporary spanning external fixation first, definitive plating once the soft-tissue envelope recovers, often 7 to 14 days), an approach popularised to reduce wound complications; some centres perform same-sitting dual plating in favourable soft tissues.
• Tourniquet: Practice is split between avoiding a tourniquet (to detect vascular injury intra-operatively) and intermittent inflation with periodic deflation; either is defensible if pulses are checked before closure.
• Plate choice: Small-fragment 3.5mm antiglide/buttress plates (radial T-plate, one-third tubular as antiglide, or LCP) are all used; the unifying principle is true posterior buttressing to resist caudal displacement in flexion.

Universal safety standards (not country-specific)

• Vascular surgery support available for any planned posteromedial exposure (popliteal neurovascular bundle proximity).
• Weight-based first-generation cephalosporin prophylaxis at induction with intra-operative redosing for prolonged or high-blood-loss cases, per WHO surgical-site-infection principles.
• Protocolised post-operative neurovascular and compartment monitoring after high-energy plateau fractures.