Management of Knee Dislocations

Transcription

1 Management of Knee Dislocations Thomas J. Gill, MD Chief, Sports Medicine Service Massachusetts General Hospital Associate Professor of Orthopedic Surgery Harvard Medical School Complex Challenging Multi-Ligament Injuries Variable outcomes Can be devastating Easily overlooked Epidemiology» Thought to be rare Knee Dislocation» 14 cases at Mayo from » 26 cases at MGH in 28-year period 1

2 Most common causes» MVA #1» Sports #2» Falls #3 50% reduce spontaneously Knee Dislocations Anterior most common (40%) Knee Dislocation > 2 ligaments injured to dislocate» not necessarily both cruciates» PCL status critical for w/u Lachman Pivot shift Posterior drawer Sag test Valgus stress 0 /30 Varus stress 0 /30 Recurvatum with ER Tibial ER 30 /90 Physical Exam 2

3 Imaging XR MRI? MRA?A Angio LCL rupture MCL rupture Medial side» Superficial MCL» Posterior Oblique Ligament» Deep MCL Anatomy» Semi-membranosis and expansions» Sartorius, gracilis, semi-tendinosis» Medial gastrocnemius Valgus» ER» medial and lateral translation Vascular Anatomy Types of Injury Contusion Stretch Intimal flap tear Rupture Popliteal artery adductor hiatus fascial arch of proximal soleus 3

4 Vascular Injury 14% Vascular injuries» Diagnosis critical» High index of suspicion Detailed neurovascular exam» Manual pulses» Doppler» ABI Devastating complications» Compartment Syndrome» Ischemia Vascular Assessment Angiography - Is it necessary? Physical exam adequate» 8 normal exams 0/8 required surgery» 11 abnormal exams 7/11 required surgery (Hollis et al JOT 2005) Abnormal pedal pulse not sensitive enough» Sensitivity 0.79, Specificty 0.91, PPV 0.75, NPV 0.93 (Barnes et al JOT 2002) ABI has excellent predictive value» Sensitivity, specificity and PPV of ABI < 0.90 is 100%» NPV of ABI > 0.90 is 100% (Mills at al JOT 2004) Functional Anatomy of Lateral Side LCL» Varus, ER» biceps helps tension in flexion PLC» ER, varus, posterior translation Popliteus (popliteofibular lig)» Dynamic IR of tibia» Static restraint to posterior translation, varus, ER 4

5 Peroneal Nerve 14% Peroneal N. injury Nerve Injury Nerve Injuries Incidence: variable (16-40%) 1/3 will recover completely Peroneal nerve Travels around proximal fibula from posterior to anterior Traction injury: Lateral and Posterolateral disruptions Foot drop Tibial nerve less common 19 dislocations» 13 MCL» 6 LCL 19/19 had surgery Lost time (73, 310) NFL Experience

6 DB - 4 N/A - 3 QB - 2 WR - 2 TE - 2 OL - 2 DL - 2 RB - 1 LB - 1 NFL Experience Position Blocked 10» Cut 3 Tackled 7 Non-contact 2 Game 14 Practice 5 4/11 on special teams NFL Experience Activity Grass 12 Turf 7» Field 4» Astro 3 NFL Experience Surface 6

7 Key to success Accurate diagnosis» Understand anatomy» Careful physical exam» Appropriate imaging Treatment options» Conservative» Surgical» Acute» Immediate» Delayed Questions to be Answered Timing of Surgery» Acute vs. delayed (criteria?)» Medial vs. lateral (different?)» Role for non-op treatment of MCL? Repair vs. Reconstruction» Cruciates» Collaterals Peroneal nerve / Vascular exam Rehabilitation philosophy Return to play criteria Surgical Decisions Timing Immediate» Open dislocation» Vascular injury» Repair collaterals» Delay cruciates» Uncontrolled instability» Ex-fix x 5-10 days 7

8 Surgical Decisions Acute <14 days» Lateral side + ACL or PCL» ACL/PCL, PLC or MCL III Allow acute swelling to subside Restore ROM! Give capsule chance to seal Collaterals easier to repair PLC typically tears distally, retracts proximally and scars Surgical Decisions Elective ACL/PCL with MCL grade I, II» Allow MCL to heal» Reconstruct (not repair ) cruciates Grade III MCL» Distal tears can retract» Stenner lesion of knee» Poor healing, chronic instability» Check stability after cruciate reconstruction Autograft» Rare» Usually only for lateral side Allograft» Cruciates» Collaterals» PMC, PLC Chronic cases» Generally poorer results Graft Choices» Compomised secondary restraints» Err on side of more reconstructions ( corners ) 8

9 My (Current) PCL Preference Trans-tibial tunnel Single bundle Achilles allograft Achilles Graft Preparation Operative Approach 9

10 Establish PM Portal Expose Posterior Tibia Effect of Surgical Approach 5 human cadaveric knees Posterior capsulotomy for reconstruction Additional 1mm laxity at all flexion angles p < 0.05 (Park, Gill et al, AJSM, 2004) 10

11 Influence of Tibial Tunnel Position Just lateral to midline 10mm distal to joint surface 70 degree angle Knee center Medial tunnel Lateral tunnel Placement of Tibial Guide Drilling Tibial Tunnel 11

12 Drilling Tibial Tunnel PCL Femoral Tunnel Femoral tunnel» 2-incision avoids killer angle» Half-way from medial trochlea to epicondyle» Stay proximal» 6mm posterior to articular surface» 12:30pm Femoral Guide Placement 12

13 Suture Passer Passing Graft Graft Fixation: Does Location Matter? 5 human cadaveric Achilles tendons 3 different lengths studied» 75mm (long) = mid-tunnel fixation for TTT» 48mm (medium) = inlaytibia tibia, mid-femur» 34mm (short) = articular fixation (DeFrate, AJSM, 2004) 13

14 Optimal Graft Length MTS Preconditioned Displaced at 100 mm/min 400N load applied Force-displacement data Linear stiffness at each length Clamp Crosshead Bone Cement Graft Optimal Graft Length Increasing length caused decrease in stiffness of 29±30% Long graft 85±28% less stiff than short graft All diffs p<0.05 Consider your fixation site! (N) Force ( Long Medium Short Elongation (mm) Figure 2. Force-elongation curve Linear Stiffness of Grafts Linear Stiffness s (N/mm) * * 0 Short Medium Long 14

15 Clinical Significane Two tibial screws to shorten effective length Composite screw posteriorly (60mm) Metal screw anteriorly? Need for Inlay Single Bundle Patellar tendon allograft ACL degree angle 2 cm bone bridge ACL Tibial Tunnel Medial on anterior tibia Just posterior to AHLM 15

16 ACL Femoral Tunnel Anatomic position Low on notch (10 o clock) 2-pin passer Composite screw LCL Approach depends on location of tear Usually avulsed with biceps Primary repair preferred LCL / PLC Repair LCL and biceps form V Tag peroneal nerve Whipstich tendon 3 drill holes (2.0mm) Popliteus Capsule!!» Arcuate ligaments 16

17 LCL / PLC Reconstruction Mid-substance tear Split Achilles allograft Drill hole (5mm) in fibular head Popliteal by-pass LCL / PLC Reconstruction Docking procedure (Asnis technique) Tibialis anterior allograft Pass P to A through fib head Dock free ends into 8mm tunnel Interference screw Tie free ends medially over bridge < 2-3 weeks Femoral avulsion MCL Repair» Beware stiffness Tibial avulsion» Beware laxity Bone screw Suture anchors Don t forget PM Corner / POL!! 17

18 MCL Reconstruction Check after other procedures done Rare Be prepared Isometry Capsule Stiffness Order and Method of Fixation Pass PCL» Fix femoral side with composite screw Pass ACL» Fix femoral side with composite screw Fix PCL tibial tunnel» 90 degrees, anterior drawer» Composite screw posteriorly (60-65mm)» Metal screw anteriorly Fix ACL tibial tunnel» Full extension (!)» Metal screw Order and Method of Fixation LCL with valgus stress» #2 fiberwire» Composite screw and medial bridge 18

19 Order and Method of Fixation MCL» Check isometry» Anterior limb to tibia» Posterior limb to POL Ten Commandments of Knee Dislocations (modified from Schenk, 2001) Thou Shalt 1. treat all traumatic PCL + collateral ligament injuries as potential knee dislocations 2. classify by anatomy rather than direction 3. use angiography appropriately 4. use MRI for preoperative planning 5. apply external fixators liberally in polytrauma 6. repair collateral ligamentous avulsions 7. use allografts liberally 8. fix what s torn 9. restore ROM pre-operatively when possible 10. individualize rehabilitation program Rehabilitation Brace in full ext / quad rehab 2-4 wks Protected ROM 4-8 wks Crutches 6-8 wks PREs 8 wks Sports 9-12 mo 19

20 Conclusions Multi-Ligament Injuries» Complex cases» Very challenging» Fraught with pitfalls and complications» Understand the anatomy» Fix what s torn» Have a plan» Don t rush rehab!!» 1 year to return 20