Reconstruction of the Ligaments of the Knee

Reconstruction of the Ligaments of the Knee

Contents ACL reconstruction Evaluation Selection Evolution Graft issues Notchplasty Tunnel issues MCL PCL Posterolateral ligament complex Combined injuries

Evaluation & Imaging Clinical exam Routine xrays: AP/lateral (avulsion fxs) Special xrays: sunrise/tunnel; Rosenberg view MRI: 90% sensitive (acute ACL) Not good for partial tears (<50%) Identify associated injuries Sensitive for PCL except chronic tears

Who is a candidate for ACL reconstruction? Young; athlete Symptoms of instability & pain Risk of further meniscal & articular cartilage injury Presence of degenerative changes

Nonsurgical treatment for ACL deficiency Sedentary patients; knees with advanced degenerative changes Functional bracing Rehab: full ROM, closed kinetic chain strengthening, focus on hamstrings (quads & gastroc), proprioceptive re-ed Behavior modification

Evolution of ACL surgery Direct repair Extraarticular (nonanatomic) reconstruc Prosthetic replacement (40-80% failure) Repair with LAD (no better than repair) Arthroscopically assisted reconstruction Autograft Allograft

Autografts Graft choices Bone-patellar tendon-bone Quadrupled hamstrings (Grac & Semi-T) Quadriceps tendon Allografts Bone-patellar tendon-bone Achilles tendon Hamstrings Quadriceps tendon Fascia lata

Autograft vs. Allograft Viral disease transmission (1:1million) Deep freezing leaves some cells (10%) Freeze-drying & cryo weaken graft; limited self-life Graft incorporation & remodeling is faster with autografts. (graft is weakest @ 8-12wks) Donor site morbidity with autografts?more creep with allografts

Graft selection Graft strength: patellar tendon (150% of ACL); 4-HT (150-200%); auto>allo,early Bone/bone vs. tendon/bone fixation & healing Hamstrings > tunnel widening Hamstring weakness- clinically not a problem Patellar tendon > anterior knee pain (10-40%); fracture risk (2%); 10% decrease in quad strength is usual

Graft Pros & Cons

The notchplasty Improves visualization of femoral tunnel & creates clearance for the graft Current trend is to minimize the plasty Minimizing decreases postop pain, swelling, bleeding, & potential regrowth. Too much may lateralize the femoral insertion & lead to abnormal kinematics. A recent study > histopathologic changes in cartilage @ 6mo c/w early DJD 100 pts > no short-term benefit w/ plasty

Tunnel placement Tibial tunnel @ posteromedial footprint. Femoral tunnel @ 10-11 or 1-2 o clock. Leave 1-2mm of posterior wall.

Tunnel misplacement Tibial tunnel Anterior (most common)> graft impingement, loss of extension Posterior > continued pathokinematics Femoral tunnel Anterior (most common)> high strains in flexion, loss of flexion, inc graft stretching Posterior (over-the-top)> blow-out, tight in extension, inc AP laxity in flexion

Tunnel technique Tibial tunnel @ 45-55degree angle toward footprint; longer grafts (b-pt-b) may need higher angles. Femoral tunnel drilled w/ 100-120degrees of knee flexion to avoid blow-out. Intraop lateral xray

The graft: intraop points Preconditioning (tensioning): 20-80N Decreases up to 30% soon after fixation Excessive > restrict motion; accel arthrosis Inadequate > continued instability Fixation Type > interference screws (tit/bio), endo, transfix Technique > at joint line; avoid divergence (>15*) Rotating graft by 90deg or more increases strength by approx. 20%

Graft fixation Single-incision Double-incision Blunt-threaded bioabsorbable screws allow fixation at the joint line on both sides.

Fixing the graft Snug fit b/w graft and tunnel Underdrill & dilate-up 7mm & 9mm screws Avoid screw divergence Place femoral screw @ 100-120deg flexion Place femoral screw through tibial tunnel? of knee position Slight flexion > least AP laxity, tightest Lachman Full extension > limits risk of flexion contracture

Results of ACL recon. Most series show 88-95% good to excellent results @ 3-5yr f/u. Objectively stable knees Instrumented laxity less than 3mm Pivot shift less than 1+ Subjective success in 80-92% @ 3-5yrs Full return to preinjury activity levels w/o significant symptoms Meniscal resection & cartilage damage adversely effect results. Better rates of meniscal healing w/ ACL surg.

Medial Collateral Lig. Grades: medial opening in 30deg flex 1 = 1-5mm 2 = 6-10mm 3 = 11-15mm Nonsugical rx is the mainstay Bracing & crutches (b/w 2-6wks) Rehab: early quad & hamstring strength Combined injuries (post capsule,cruciate) Nonsurg & surgical rx have been recommended Higher risk of stiffness w/ proximal injuries

Posterior Cruciate Lig. Pt c/o pain rather than instability. Chronic (10-20yr) PCL deficiency Medial & PF compartment arthrosis Cadaver study > inc contact pressures Nonsurg rx focuses on quad strength? true isolated injuries Usually partial tears (do well) Serial bone scans > early cartilage damage? missed combined injuries (60% have posterolat complex)

Surgery for PCL Recommended w/in first 2 weeks Exam > 3+ posterior drawer, increased ER @ 30 & 90deg flexion 20% of athletes go on to reconstruction 2 distinct bundles > not isometric Grafts Achilles tendon allograft Patellar & quad tendon autografts Increasing interest in a 2-bundle technique Postop rehab: much less aggressive than ACL rehab.

Tunnel placement: PCL Anterolateral bundle is the focus of reconstruction. Larger & stronger Taut in flexion

Posterolateral Complex IT band, biceps femoris, LCL, fabello-fibular lig, arcuate lig, popliteus tendon, & posterolateral capsule Spectrum of injury; assoc w/ PCL & bicruciate injury c/o instability, esp. descending stairs >10% incidence of peroneal nerve injury Increased lateral comp translation & medial comp compression (inc adduction moment in varus knees)

Posterolateral complex surgery Direct primary repair for acute injuries avulsion fxs, ie. fibula w/in first few weeks; lateral approach address all injured structures Reconstruction for chronic injuries Traditional procedures (mixed results) Biceps tenodesis (Clancy), arcuate lig advancement Anatomic procedures (results pending) Popliteal lig. & LCL reconstruction (auto & allograft sling) HTO before reconstruction in pts w/ varus thrust

Results of PL complex repair/reconstruction Few reports or series Fanelli et.al. (recent retrospective study) 64% restoration of PL stability w/ arcuate complex bony recession 78% success rate w/ Achilles tendon allograft loop reconstruction of the LCL

Combined injuries MCL & ACL Reconstruct ACL; brace for MCL May need early MCL repair for grade 3 injuries w/ opening in full extension. Increased risk of postop stiffness MCL & PCL Grossly unstable knees Early MCL repair w/ PCL reconstruction May consider bracing x4-6wks, then PCL recon. Tibia must remain reduced in the brace.