Therapy Information Systems - Orthopedics II

TIS

Chapter 11
ACL, PCL and Combination Injuries

ACL anatomy
1. attachments:
  - tibial attachment is wider and stronger than femoral attachment; femoral attachment is behind axis of flexion while tibial attachment is in front of axis
2. bundles: based upon relative attachments on tibia
  - anteromedial: femoral attachment from posterior and superior convexity, tibial attachment forms medial corner of tibial attachment
  - posterolateral: femoral attachment anterior and inferior, tibial attachment represents posterior apex of triangle
3. blood supply: major supply from the branches of the middle geniculate artery; vessels predominantly in the soft tissues (fat pad, synovial membrane) and not bone

Mechanism of injury/acute eval
- plant and twist
- hyperextension
- acute, tense effustion
- + Lachman's
- watch for tibial spine avulsion in adolescents

Natural history of ACL deficient knee
1. Noyes (1983)
  - 35% reinjury within 6 mos, 51% within 1 yr
  - at 5 year R/U: significant subjective disability, pain, giving way and 44% of those with the longest R/U has significant x-ray DJD changes
2. Kannus (1986)
  - 80% decreased activities
  - 40% reinjuries
  - 70% x-ray DJD
3. Hawkins (1986)
  - 87.5% fair or poor result
  - 10% returned to unlimited activities
4. Barrach (1989)
  - 59% poor
  - 5% returned to sports at a 33% lower level

ACL repair
- doesn't work

Extra-articular reconstruction
- generally used in adolescents; poor results
- Chick (1981): 89% had rotary instability and 84% pivot shift

Intra-articular reconstruction

Autogenous:
- currently providing the best results
- most use central 1/3 of patellar tendon
- ITB or semitendonous also used
Synthetics:
- permanent substitutes (Goretex, Dacron)
- stents - support/sustain autogenous tissue (LAD)
- scaffolds - stimulate and allow tissue ingrowth
* these materials currently performing poorly; ie. instability, sterile effusions, material breakdown, etc.

Allografts:
- indications generally failed autogenous PT (patellar tendon) reconstruction, or the presence of patella baja
- Jackson (1991) found autografts to give better results than allografts
- Noyes (1990) found good clinical results in two groups using either a fascia lata or BPT allograft
- with bone plugs: better fixation but greater likelihood of rejection
- without bone plugs: fixation problems
- HIV issues: ethylene oxide or gamma irradiation; fresh-frozen vs. freeze dried
* OUTCOME STILL VERY DEPENDENT UPON SURGEON SKILL AND TECHNIQUE!
Graft placement is critical to assure isometric placement and adequate fixation, and avoiding graft impingement. Additionally, they are still the gatekeeper for rehab; therapist's skills are challenged when the patient doesn't show up for the first 6 weeks

Post-op rehabilitation considerations
- associated injuries/pathologies
  - meniscal
  - capsular
  - ligamentous
  - PF
  - DJD
- time constraints of healing; don't let a healthy-looking athlete fool you
  - presence of effusion
  - patellar mobility
  - patient compliance/pain tolerance
  - patient activities/goals

PCL ANATOMY, SURGERY, REHAB

PCL anatomy
- invested in synovium
- near longitudinal axis just medial to center of knee
- strength to failure 2x that of the ACL
- two bands (oversimplification)
- attachments
  - femoral: lat portion of MFC in semicircle oriented horizontally
  - tibial: depression on post tibia between 2 plateaus, 1 cm below articular margin (important in TKR)
- blood supply: medial geniculate artery
- meniscofemoral ligaments: stabilize meniscus
  - Humphrey - anterior, 1/3 PCL (size)
  - Wrisbery - posterior, 1/2 PCL (size)
  * 70-100% of population has both

Biomechanics
- resists 95% of posterior displacement force
- isolated PCL tear increases post translation at all flexion angles; greatest at 90 degrees
- PCL + PL corner or collateral lig injury: 15-25 mm post displacement; PL alone = 3 mm
Contact pressures:
- increase medial compartment with peak at 60 degrees
- increase PF joint with peak at 90 degrees

Mechanism of injury
- posterior force with knee flexed, foot PL flexed
- hyperflexion or hyperextension (ACL goes first)
- varus/valgus (collateral goes first)

Natural history of PCL deficient knees
1. pain
  - with activity 70%
  - patellofemoral 50%
2. DJD
  - Clancy: 48% med>lat, 71% @ 2-4 yrs; 90% @ >4 yrs
  - Kennedy: 44% @ 61 mos
3. instability
  - 8-59% instability with activity
  - up to 40% instability with ADL

Treatment
- isolated injuries appear to be best-treated conservatively; however, this requires a thorough exam
- combined instability with MDI should be reconstructed using static restraints

POSTEROLATERAL KNEE INSTABILITY

Pertinent anatomy

Arcuate Ligament Complex
- arcuate ligament: y-shaped structure that extends from the fibular head over the popliteus and is continuous with the oblique popliteal ligament of Winslow
- LCL
- popliteus
- lateral head of gastroc
Three Layer Organization
- layer 1: iliotibial tract and its expansion, and the superficial portion of the biceps
- layer 2: anteriorly is the quadriceps expansion; posteriorly incomplete & is represented by two patellofemoral ligaments (lat intermuscular septum and fabella)
- layer 3: part of the joint capsule; attaches to the lateral meniscus as the coronary ligament; deep lamina: arcuate ligament

Biomechanics
- posterior translation, varus rotation and external rotation are most useful in detecting posterolateral injuries; with complete PL disruption and intact PCL, maximum motions are noted at 30 degrees
- large increase in ER at 90 degrees suggests PCL injury
- LCL is primary restraint to varus force, so rare to get deep posterolateral complex without LCL

Mechanism of injury
- usually a posteriorly directed forced to anteromedial knee in extension producing hyperextension and varus
- posterolaterally directed force on the anteromedial aspect of a flexed knee
- occasionally, extreme ER of tibia

Evaluation
- CC: inability to descend stairs; demonstrates valgus thrust
- varus at 30 degrees is most sensitive test
- tibial ER at 30 and 90 degrees (10 degree diff in ER at 30 degrees is significant for PL injury)
- ER recurvatum
- posterolateral drawer
- reverse pivot

Treatment
- failure to treat the posterolateral corner in a combination PCL-PL injury will result in a functionally lax PCL
- PL reconstruction consisting of anterior and superior advancement of the lateral gastroc tendon, superior posterolateral capsule, LCL, and popliteus tendon has been advaocated by Hughston, but has not produced good results
- Andrews advocates rerouting the common biceps tendon to the lateral femoral condyle, while leaving the distal tendon attached to the fibula; this creates a new LCL and tightens the deep inferior PL arcuate complex via its attachment to the biceps tendon complex
- rehab will depend upon associated injuries and reconstructive procedures

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