Combined ACL, PCL and collateral/corner reconstruction following knee dislocation | advanced
Surgical Imaging
The trap: Assuming a palpable dorsalis pedis pulse excludes popliteal injury — intimal flaps or partial tears can present with normal distal pulses initially but progress to thrombosis within hours.
The fix: Perform ankle-brachial index (ABI) in every suspected knee dislocation. ABI less than 0.9 or asymmetric pulses mandate immediate CT angiography. Hard signs (expanding haematoma, pulsatile bleeding, absent pulse) require immediate vascular surgery consultation before any ligament work.
Location: The common peroneal nerve courses around the fibular neck, 1-2 cm distal to the fibular head, and is tethered at the fibular tunnel — vulnerable to stretch in varus and hyperextension injuries.
Risk: Up to 25 percent of KD-III-L injuries have clinical peroneal palsy at presentation. Document sensation in the first dorsal web space and ankle dorsiflexion/eversion strength before and after reduction. If deficit present, plan exploration or later tibialis posterior transfer.
Location: The PCL tibial tunnel (anteromedial tibial plateau) and the posterolateral corner fibular tunnel (posterior fibular head) can converge or fracture the proximal fibula if not carefully planned.
Risk: Intraoperative fluoroscopic confirmation of tunnel position and adequate bone bridges (greater than 1 cm) is mandatory. Use outside-in drilling for the PLC fibular tunnel to control trajectory and avoid convergence with the PCL tunnel.
KD-III: One cruciate plus both collaterals or both cruciates plus one collateral — single-stage combined reconstruction is standard when soft tissues permit.
KD-IV: Both cruciates plus both medial and lateral structures — often requires staged reconstruction (PCL first) to reduce operative time and arthrofibrosis risk; single-stage only in selected low-swelling cases with experienced team.
Acute (less than 3 weeks): Allows primary repair of collaterals and corners but carries higher arthrofibrosis risk if swelling is severe; vascular assessment is easier before chronic scarring.
Delayed (greater than 3 weeks): Permits resolution of swelling, better tissue quality for reconstruction, and staged approach; however, chronic PCL sag and secondary meniscal/chondral damage may develop if instability persists.
The trap: Fixing the ACL at 90 degrees flexion or the PCL in extension creates permanent extension loss or posterior sag respectively.
The fix: Tension and fix PCL at 90 degrees flexion with anterior drawer force; fix ACL near full extension with posterior drawer to restore step-off; fix PLC at 30 degrees flexion and MCL at 20-30 degrees flexion under varus/valgus stress.
S.C.H.E.N.C.K.SCHENCK — KD Classification for Multiligament Injury
F.I.X.A.T.I.O.N.FIXATION — Sequence and Tensioning Angles
V.A.S.C.U.L.A.R.VASCULAR — Assessment Algorithm in Knee Dislocation
Surgical Indications
Absolute Indications
- Knee dislocation with confirmed or suspected vascular injury requiring repair (popliteal artery disruption)
- Multiligament injury with gross instability preventing weight-bearing or threatening skin envelope (KD-III or KD-IV)
- Peroneal nerve deficit with suspected nerve transection or entrapment requiring exploration
- Open knee dislocation or associated tibial plateau fracture requiring staged or combined fixation
Relative Indications
- KD-III or KD-IV injury in a young active patient with high functional demand
- Chronic symptomatic instability after failed non-operative management of multiligament injury
- Recurrent giving-way episodes with secondary meniscal or chondral damage
- Patient preference for surgical reconstruction after informed discussion of staged versus single-stage options
Contraindications
Absolute:
- Unreconstructed popliteal artery injury or ongoing vascular compromise
- Active infection or open wound at planned surgical sites
- Medical comorbidities precluding prolonged anaesthesia or major reconstruction
Relative:
- Severe arthrofibrosis or limited pre-injury range of motion (consider staged arthroscopic release first)
- Low-demand elderly patient with acceptable braceable stability
- Ongoing substance abuse or inability to comply with post-operative rehabilitation protocol
Evidence for Timing and Approach
Acute versus Staged Reconstruction
- Acute single-stage reconstruction (less than 3 weeks) allows primary repair of collateral structures and reduces chronic instability but carries higher arthrofibrosis rates (up to 30-40 percent in some series) when swelling is severe.
- Staged reconstruction (PCL first, then ACL plus collaterals at 6-12 weeks) reduces operative time and arthrofibrosis risk in severely swollen or polytrauma patients; allows resolution of soft-tissue envelope and better graft incorporation.
- A systematic review by Levy et al. (2013) demonstrated comparable functional outcomes between acute and delayed approaches when vascular status is addressed promptly; delayed surgery showed lower reoperation rates for stiffness.
Single-Stage versus Staged Decision Factors
- Favourable for single-stage: low swelling, experienced surgical team, no vascular injury, young patient with high demand.
- Favourable for staged: polytrauma, severe swelling, skin compromise, need for vascular repair, surgeon preference for reduced operative time.
Graft Selection and Outcomes Evidence
Allograft versus Autograft
- Allograft (Achilles, tibialis anterior, peroneus longus) is preferred for PCL and PLC reconstruction to reduce donor-site morbidity and allow early aggressive rehabilitation; autograft hamstring or bone-patellar tendon-bone remains standard for ACL.
- A 2022 systematic review by Woodmass et al. reported no significant difference in failure rates between allograft and autograft in multiligament reconstruction when appropriate tensioning and fixation angles are used.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 28-year-old motorcyclist is brought in after a high-speed collision. The knee was dislocated on arrival but reduced in the field. Pulses are palpable but the ABI is 0.85 on the injured side versus 1.1 on the contralateral limb. There is a 2 cm difference in calf circumference and pain on passive stretch. How do you proceed?”
“You are planning single-stage reconstruction for a 32-year-old with a Schenck KD-IV knee dislocation (both cruciates plus MCL and PLC). The swelling has settled and vascular status is normal. Walk me through your graft choice, tunnel planning, and fixation sequence.”
“A 35-year-old with a KD-III-L knee dislocation (ACL, PCL, and PLC) undergoes single-stage reconstruction. At 8 weeks post-operatively he has only 5 degrees of active dorsiflexion and numbness in the first web space. How do you manage this?”