Knee Ligament Injuries

common multi-ligament injuries

ACL+MCL, posterolateral corner + PCL

structures in the posterolateral corner (PLC)

lateral head of gastroc, popliteus tendon, popliteofibular ligament, LCL, arcuate ligament

function of PLC

restraint to varus and ER forces

type 2 PLC injury

PCL and PFL rupture

type 3 PLC injury

PCL, PFL, and partial LCL rupture

type 4 PLC injury

PCL, PFL, LCL, and other structures

most common cause of PLC instabilities/injuries

high impact (vehicle trauma, athletic injury)

typical treatment of PLC injury

surgical fixation followed by period of NWB

isolated ligament injuries from most to least common

ACL, PCL, LCL, MCL

MOI of ACL

deceleration and acceleration with noncontact valgus force near full extension

clinical presentation of ACL

“giving way”, positive lachman, positive pivot shift, quad MVIC less than 80

MOI of PCL

posterior directed force on proximal tibia (flexed knee)

clinical presentation of PCL

positive posterior drawer, posterior sag, localized posterior knee pain with kneeling

MOI of MCL

valgus and/or rotational trauma

MOI of LCL

varus trauma

examples of patient reported outcome measures

KOOS, tegner scale, ACL-RSI

examples of performance measures

single leg hop, baseline pain/function, global knee function, side-to-side asymmetries

examples of impairment measures

knee laxity/stability, coordination, effusion, thigh strength

rehab time line for various MCL sprain

I: 2 weeks, II: 4 weeks, III: 6 weeks

characteristics of LCL injury rehab

early quad activation and swelling management, proprioception, plyometrics

components of pre or non-operative rehab

address swelling, quad strengthening, dynamic stability, unloading brace

post-op rehab principles

progressive WB, quad strength, anterior joint stability to prevent posterior tibial subluxation, prone PROM

pattern of strain in PCL during passive knee flexion

increases especially at 60 degrees, more strain with IR

tibial movement in OKC knee extension (0-60 degrees)

anterior tibial translation

tibial movement in OKC knee extension (60-75 degrees)

no translation only roll/rotation

tibial movement in OKC knee extension (90 degrees)

posterior tibial translation

early exercise ROM for PCL rehab

hamstring exercises in shallow range ROM because there is less strain

typical time for PCL rehab protocol

20 weeks

precautions for partial menisectomy

no modifications

precautions for meniscal repair

no modifications, WB in full extension is okay

precautions for chondroplasty

restricted WB for 4 weeks, consider tibiofemoral unloading brace if limited by pain

precautions for MCL injury

restrict saggital plane motion 4-6 weeks decrease strain on MCL

types of autografts for ACLR

BPTB, quad tendon, hamstring tendon, allograft

pros of hamstring autograft

decreased graft site morbidity, faster recovery of knee extensor strength

cons of hamstring autograft

higher failure rate, knee flexion strength deficits

rehab considerations of hamstring tendon autograft

relative protection (limit HS exercises) for 8-12 weeks, ER compensation with biceps femoris

pros of quad tendon autograft

decreased graft site morbidity

cons of quad tendon autograft

prolonged quad weakness

considerations for rehab of quad tendon autograft

patellar mobility, consider stretching/strengthening in hip extension because it is a 2 joint muscle

pros of BPTB

faster graft maturation, low re-injury rates

cons of BPTB

more anterior knee pain, prolonged quad weakness, heightened risk of OA, risk of patellar fracture

what does a patellar tendon graft site look like post op

lumpy and less striated

patellar tendon CSA vs quad CSA

patellar tendon CSA tells you more about quad LSI (strength)

recovery of hamstring vs BPTB autograft

hamstring recovers strength faster

healing of ACL after non-op

53% healed after 2 years

characteristics of BEAR implant

sponge-like implant, ACL repair, absorbed within 8 days

re-injury rate of ACLR

17-20%, contralateral: 12-25%

important points of pt education

does not guarantee RTS, risk of re-injury is higher in the near term, risk of OA is high

outcome of delayed surgery

no difference in outcome if you do rehab