1. primary stabilizer
· prevents anterior translation and hyperextension
2. secondary stabilizer
· lateral (and medial) stability
3. contributes to screw-home mechanism
· rotation around its axis
4. protector of menisci
· pivot effect for glide/roll of menisci
· usually non-contact sports that involve jumping and pivoting
· most common injury patterns are
· deceleration/rotation/valgus
· hyperextension
· 75% associated with haemarthrosis
· 50% associated with meniscal injury
Grading
· 0 - normal
· 1+ - < 5 mm
· 2+ - 5-10 mm with solid end-point
· 3+ - > 10 mm with no end-point
Lachman's
· done at 15o flexion
· to eliminate effects of bony contour and menisci
· tibia subluxed forward with one hand as other hand stabilises femur
· ACL is primary stabiliser (provides 85% resistance)
· MCL, LCL and post capsule are 2o stabilizers
· sensitive test
· positive in 85% (awake) and 100% (asleep)
Anterior drawer
· described by Slocum
· knee at 90o flexion with hamstrings relaxed
· performed in three positions wrt. foot
1. foot in neutral
· ACL is chief stabiliser
2. foot in 15o of ER
· medial structures tightened
· forward movement of medial tibial plateau suggests anteromedial instability
· damage of ACL, MCL, medial capsule, oblique popliteal ligament
3. foot in 30o of IR
· lateral structures tightened
· forward movement of lateral plateau suggests anterolateral instability
· damage of ACL, LCL, arcuate complex
· not always positive in acute ACL deficiency
· depends on 2o stabilisers
· positive in 25% (awake) and 60% (asleep)
· usually positive in chronic ACL deficiency
· 2o stabilisers stretched
· positive in 95%
· first described Losey & McIntosh 1947
· subjective description used by patient to describe sequence of knee going out
· many tests described to elicit pivot shift
· all performed with valgus thrust to knee during flexion/extension
· valgus mimics weight-bearing
· usually too painful on acute knee
· good prognostic indicator
Macintosh pivot shift test
· internally rotate foot with one hand
· place valgus stress on proximal tibia while flexing knee with other hand
· in extension in ACL deficient knee
· lateral tibial condyle subluxed forward
· ITB in front of flexion axis and is extensor
· with flexion
· ITB passes behind flexion axis and becomes flexor (20-40o)
· lateral tibial condyle snaps backward and reduces
· contribution by bony contours
· graded on degree
· I - normal
· II - slide or glide
· III - clunk or jerk
Other tests
· ALRI
· patient on side
· jerk
· knee starts flexed (reduced)
· Losee
· use thumb to pull tibial plateau forward
· usually normal
· may see small avulsion fracture of lateral aspect of tibia
· Sigund’s fracture
Tibial avulsion
· occasionally see avulsion of tibial spine
· more common in children
· Meyers classification
· I - undisplaced avulsion fracture from tibial plateau
· II - anterior part of avulsion fracture from tibial plateau superiorly displaced
· III - whole avulsion fracture from tibial plateau superiorly displaced
· IV - avulsion fracture from tibial plateau displaced and rotated
· not always accurate for ACL
· ACL is helicoid shape
· 15o out of plane of cut
· rarely indicated in isolated ligament injury
· useful to detect associated meniscal tears
· most common is KT 1000
· equivalent of instrumented Lachman's test at 30o
· most specific and sensitive
· Marshall 1978
· “natural history is progressive functional and anatomic deterioration of the knee"
· supported since with demonstration of
· meniscal damage
· stretching of 2o restraints
· articular cartilage damage
· early OA
· Noyes 1983
· 103 knees at 5.5 yrs
1. nonrehabilitated
· 80% return to sports but 35% to preinjury level
· reinjury of 1/3 at 6 mths and 1/2 at 12 mths
· pain and disability reported by 1/3 with walking, 1/2 with ADL and 3/4 with twisting sport
· radiographic OA in 50% at 10 yrs
2. rehabilitated
· 84 patients rehabilitated and assessed at 8 yrs
· involved counselling, activity modification and exercise programme
· continued for 6 months
· 1/3 improved, 1/3 stayed the same and 1/3 became worse
· developed rule of thirds
· 1/3 will compensate and be able to pursue recreational activities
· 1/3 will compensate but have to give up significant activities
· 1/3 will do poorly and require reconstruction
· concern is that return to high-level pivoting sport usually associated with tear of medial meniscus
· clearly shown that meniscal tear predisposes to OA
· individualise treatment
· determine
· premorbid activity level
· post-treatment expectations and requirements
· willingness to modify activities
· motivation to participate in rehabilitation
· economic factors and occupational commitments
· control pain and inflammation
· analgesics
· ice and elevation
· splint only in first few days if required
· weight-bearing
· as tolerated
· often need crutches early
· range-of-movement exercises
· started early
· aim to regain full flexion and extension
· muscle-strengthening exercises
· started once full ROM achieved
· quadriceps and hamstring strengthening
· resumption of activities
· once strengthening progressed
· non-ACL-stressing (cycling, swimming, jogging)
· avoid ACL-stressing activities
· jumping, pivoting, twisting
· may exacerbate injury
· may elicit instability
· may tear medial meniscus
Indications
· older patient willing to modify activities
· minimal instability
Technique
· quadriceps and hamstring rehabilitation
Indications
· young patient with desire to return to high-level ACL-stressing sports
· recurrent instability causing significant disability
Requirements
· able to comply with vigorous postoperative rehabilitation programme
Primary repair
· not effective alone as ligament does not heal
· may be due to
· failure of clot formation because of synovial fluid
· tension on ligament
· intrinsic deficiency in healing potential
· can be combined with extra-articular or intra-articular augmentation
· results inconsistent
Extra-articular augmentation
· goal is to prevent anterior subluxation of lateral tibial plateau
· most procedures use section of iliotibial tract to keep tibia posterior to centre of rotation
· popularity waned
Reconstruction
· current gold standard
Grade I and II
· patellar cylinder with knee in full extension for 6 weeks
Grade III and IV
· open reduction and internal fixation
· can use variety of techniques
· suture
· K-wire
· screw
Autograft
Choices
· middle third of patella tendon
· hamstrings (semitendinosus and gracilis)
· iliotibial band
Strength
· cf. ACL
· middle third of patella tendon - 168%
· semitendinosus - 70%
· gracilis - 50%
· double strand - 240%
· ITB - 45%
Advantages
· no risk of disease transmission
· better incorporation and healing
Disadvantages
· donor site morbidity
· anterior knee pain
· pain on kneeling
· hamstring weakness
· donor site complications
· patellar fracture
· patellar tendon avulsion
· hamstring haematoma
Allograft
Advantages
· similar incorporation and healing to autograft
· no donor site morbidity
· various shapes and sizes
· unlimited supply
· decreased surgical time
Disadvantages
· potential for disease transmission
· weakening with sterilisation
Synthetic
Advantages
· no donor site morbidity
· various shapes and sizes
· unlimited supply
· decreased surgical time
· no risk of disease transmission
Disadvantages
· increased risk of infection
· significant long-term failure rate with rupture
· synovitis and wear debris
· should be performed
· when knee has full painless ROM
· at least 6 weeks after initial injury to minimise arthrofibrosis
· may be
· open
· arthroscopic
· arthroscopically assisted
· isometricity does not exist
· no point on femur that maintains fixed distance from point on tibia
· up to 3 mm elongation acceptable
· graft should tighten with increased extension
· weakest link initially is fixation
· greatest strength achieved with bone plugs and interference screws
· subsequently weak part is graft
· race between
· necrosis
· healing
· graft undergoes ischaemic necrosis
· graft also undergoes synovialisation
· becomes enveloped with vascular synovial tissue
· from infrapatellar fat pad and synovium
· occurs at 4-6 wks postop
· synovialisation provides source for
· neovascularisation
· cellular proliferation
· strength of graft is 70% at 6/52
· never reaches preimplant strength
Meniscal injury
· meniscal repair should be combined with ACL reconstruction
· only 60-70% success of meniscal repair in ACL deficient knee
· 90% success if ACL reconstructed
· should be performed at same time
· meniscectomy should be performed
· if meniscus irrepairable
· if ACL repair not contemplated
Collateral injury
· should treat MCL nonoperatively
· then perform delayed reconstruction of ACL if indicated
· early problems because focus on achievement of strength and stability
· focus now to is to avoid complications of surgery
· stiffness with lack of full ext
· anterior crepitus and scarring
· rehabilition program consists of
· fast return to ADL's
· early return to sports
· divided into phases
1. pre-operative rehabilitation & education
· helps avoid complications
2. early post-op (1-2 days)
· passive ROM exercises started
· full extension to 90o flexion
· may use CPM
· discharge on day 2
3. early recovery (2-14 days)
· knee immobiliser for comfort and maintenance of extension for 7-10 days
· partial weight bearing and crutches for 10-14 days
4. start formal rehabilitation (2-8 wks)
· supervised by physiotherapy
· flexibility, strength and balance control
· "closed kinetic chain strengthening" exercises with foot and knee loaded
5. resume functional activities (2-4 mths)
· dynamic exercises
· resisted strengthening
· proprioception
· minitrampoline
· swimming and cycling
6. gradual resumption of sport (4-6 mths)
· straight line jog at 4 mths
· training at 5 mths
· contact sport at 6 mths
· 2/3 of patients return to pre-injury sporting level
· graft failure rate is 10%
General
· haemarthrosis
· haematoma
· DVT
· RSD
· compartment syndrome
Stiffness
· most commonly flexion deformity
· associated with
· arthrofibrosis (esp. with surgery in acute period)
· rehabilitation that restricts extension
· nonisometric graft placment
· cyclops lesion (fibrous nodule anterolateral to tibial tunnel)
· avoided by
· delaying surgery until full painless ROM (at least 6 weeks)
· allowing early extension
· performing adequate notchplasty
· placing graft in ‘isometric’ position
· placing graft posteriorly enough to prevent impingement
Patellofemoral
Failure of extensor mechanism
· in form of
· patellar fracture
· patellar tendon rupture
· uncommon
· related to size of graft harvested
Patello-femoral pain
· with patellofemoral technique
· incidence of 20-30%
· more common with open technique
· may be
· scar tenderness with difficulty kneeling
· retropatellar pain with chondromalacia
Hardware
· staple or screw failure
· articular cartilage damage
· 10 times less common than ACL
· posteriorly directed force on flexed knee
· dashboard injury
· forced hyperextension of knee
· posterior rotatory force
· posterior sag
· posterior draw sign
· reverse pivot shift
· knee extended from flexed position
· with valgus force and foot externally rotated
· associated features of posterolateral instability
· rarely associated with meniscal injury
· usually results in little functional instability
· chronic instability may lead to early OA
· mainstay of treatment
· quadriceps strengthening stressed
Indications
· failure of nonoperative treatment
· combined ligamentous injuries
· esp. with dislocation of knee
· multidirectional instability
Technique
· reconstruction