ACL surgery/rehab and cartilage procedures

Question 1

What is an ACL reconstruction

Answer 1

• the surgeon tries to recreate the native foot print of the ACL
• typically bone-tendon-bone= gold standard

Question 2

What is the weak link after an ACL reconstruction. of a bone-tendon-bone graft

Answer 2

• where it attaches to the bone during the first 8 weeks
• after 8 weeks it becomes the graft itself
• infra patellar graft

Question 3

What are the goals of ACL reconstruction

Answer 3

• restore functional knee stability
• reproduce structural properties of ACL
• retain full knee ROM
• allow early return of muscle strength –still requires dynamic strength
• minimize time required for safe return to full activity

Question 4

ACL grafts: autograft

Answer 4

• patellar tendon
• hamstring (hamstring)
• sometimes quad tendon
• autograft = 2nd trauma site

Question 5

Patellar tendon graft strength

Answer 5

• the smaller the graft = the less strength
• generally the graft is stronger than the original ACL at first
• after 8 weeks the graft undergoes revascularization and becomes a ligament therefore losing some of the tensile strength (50-80% of the original strength)

Question 6

Patellar tendon BTB disadvantages

Answer 6

• donor sit morbidity (trauma to extensor mechanism)
• patella fx
• patella tendonitis
• patella tendon rupture
• anterior knee numberless

Question 7

Hamstring (semitendonosis)

ACL graft

Answer 7

• strip a section
• tendon healing to bone
• Early on weakness is in the insertion sites
• can take up to 12 weeks for the tendon to bone attachment

Question 8

hamstring graft strength

Answer 8

• 4 strand = how many times the fold it tends to be stronger

Question 9

Hamstring disadvantages

Answer 9

• variability of tendon size
• decreased stiffness associated with soft tissue fixation
• potential for residual hamstring weakness which dynamically supports the ACL

Question 10

Autograft incorporation time line

Answer 10

• 0-8 weeks: neovascularization
• 8-50 weeks: rapid remodeling
• 1-3 years: maturation

Question 11

Clinical outcomes of ACL reconstruction

Answer 11

• subjectively: BTB 70-90 and STG = 80-90
• objectively: 70-93 BTB and 70-90 STG <3 mm slide to side difference
• arthrometer fits onto tibia and lockmens test is preformed and translation is measured and compared to other side

Question 12

Allograft choice

Answer 12

• cadaver graft
• patellar tendon
• achilles tendon

Question 13

Allograft clinical outcome

Answer 13

• 7.7 failure rate in young population
• Radiation alters biomechanics properties
• elongation

Question 14

Rehab of ACL reconstruction

Answer 14

• pain management through early ROM and cryotherapy
• initial goal: re-estabilish ROM (passive extension/no open chain TKE)
• protect healing graft (caution 0-45º OKC)
• caution CKC squatting 60-90 initially

Question 15

Look over ACL rehab in kisner and Colby/power points

Question 16

What exercises produce the most strain to the ACL

Answer 16

• isometric leg extension seated
• dynamic leg extension seated with 45 N of resistance
• Lachmans test
• higher strain puts the graft at risk

Question 17

Outcomes of ACL with OA

Answer 17

• 50% will have OA within 10-20 year follow up
• 21-48% with concomitant meniscal resection develop OA in 10 years
• trauma to ACL = probably damage/bruising of articular cartilage

Question 18

Prehab

Answer 18

• quiet knee
• get person over the trauma of the tear
• full AROM/PROM knee extension
• trace to 0 effusion
• no quad lag
• quad strength index >80%
• these patients tend to have less complications post op

Question 19

Additional considerations for quad strength during ACL rehab

Answer 19

• important for RTS and reducing OA
• OKC knee extension strain and squatting strain similar (4-5%)
• strain during gait: midstance and late swing 13%
• greater emphasis on restoring quadricep strength and normalizing gait pattern

Question 20

Addition ACL rehab considerations

Answer 20

• immediate OKC through full ROM using effusion as guide (don’t progress if sweep test >1+)
• RTS 9-12 months pending completion of battery of functional test: allograft 12 months, 7x greater risk of new injury for athletes returning before 9 months
• up to 2 years + for graft to mature

Question 21

Return to sport criteria for ACL rehab

Answer 21

• ≥ 90% quad strength
• ≥ 90% symmetry on hop test battery
• ≥ 90%KOS-ADLS
• ≥ 80% ACL-RSI
• Achieve step-wise pre-injury level of conditioning (in shape to play)
• 2 week maintenance during career: Copenhagen plans; nordic curls

Question 22

Repair techniques for ACL

Answer 22

• BEAR (bridge enhanced ACL repair) technique
• protein/collagen scaffold acts as bridge from ACL stump to femur (stands the tear and collagen grows along it)
• Anchored to femur and tibia with sutures
• scaffold injected with 10 mL blood to facilitate healing

Question 23

OATS (osteochondral autograft transfer) mosaic-pasty

Answer 23

• small/local chondral defect
• osteochondral donor plug from the patient
• 12 weeks for normal stiffness
• limited or controlled WB
• small plug –> larger defect is better than nothing

Question 24

Microfracture (PIC) procedure

Answer 24

• poke holes in chondral defect
• induces bleeding and scar forms
• fibrocartilage fills the hole which is not the same quality
• Bleeding results in fibrocartilage
• initial limited WB – tissue thats filling a void
• poorer prognosis: than other cartilage repair

Question 25

Autologous chondrocyte implantation

Answer 25

• growth of chondrocytes in vitro
• periosteal patch from tibia (outer layer used to hold chondrocytes in place for them to mature)
• cultured chondrocytes injected into defect
• chondrocytes mature to form hyaline cartilage
• 15-18 months